Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
Fluorescent lamp and metal halide lamp
TECHNICAL FIELD
The present invention relates to a high efficiency
~ min~ting light source which ensures such a level of
color reproduction that allows categorical color
perception for surfacecolors ofat least red, green, blue,
yellow, white and black on which categorical color
perception of the human visual characteristics is based.
The invention relates to the following three major
technologies.
The first is a fluorescent lamp and a metal halide
lamp for providing high-efficiency illllm;n~ting light
source which allows high luminous brightness in mesopic
vision and scotopic vision or in wide visual field, while
ensuring such a level of color reproduction that allows
categorical color perception for surface colors of at
least red, green, blue, yellow, white and black.
The second is a fluorescent lamp and a metal halide
lamp for providing illumination which has whiteness in
the light color without causing sense of incongruity when
used in conjunction with a conventional high temperature
light source, while ensuring such a level of color
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reproductionthat allowscategoricalcolor perceptionfor
surface colors of at least red, green, blue, yellow, white
and black.
The third is a fluorescent lamp and a metal halide
lampfor providing high-efficiency illll~;nAtion whichhas
light color equivalent to incandescent lamp color without
causingsense of incongruitywhen used inconjunction with
a conventional low color temperature light source, while
ensuring such a level of color reproduction that allows
categorical color perception for surface colors of at
least red, green, blue, yellow, white and black.
BACKGROUND ART
In conventional lamps, spectral characteristic has
been designed by evaluating the subtle color reproduction
quality in terms of general color rendering index (Ra)
with reference to a reference light source (black body
radiation,reconstituteddaylightradiator).Incontrast,
a Japanese patent application (Application No. JAP-HEI
7-242863(September 21,1995),PCT/jp96/02618 based on said
Japanese application, discloses a method of optimizing
the design of spectral characteristic by applying such
human visual characteristics that human recognizes color
roughly (namely categorical color perception).
This method made it possible to provide high-
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efficiency light sources while ensuring such a level of
color reproduction that allows categorical color
perceptionforsurfacecolorsofat leastred, green,blue,
yellow, white and black on which categorical color
perception of the human visual characteristics is based.
A point of achieving the light source realizing
categorical color perception with high-efficiency is to
concentrate the wavelength of light into wavelength bands
mA;nly of green and red. Such a light source will be called
new high-efficiency light source hereinafter.
The new high-efficiency light source which is
designed with preference placed on the light emission
efficiency while satisfying the m; ~;mllm requirement of
color reproduction is often used for exterior lighting,
load lighting, street lighting, etc. This is because
exterior, road, street, etc. does not require high
fidelity quality color reproduction which is required for
interior lighting, with emphasis placed on the luminous
efficacy of the light source.
And another point to realizing such new high-
efficiency light source is to set the deviation from
Planckian locus (Duv) to be O or positive on uv
chromaticity coordinates.
- The range where deviation from Planckian locus (Duv)
is O or higher is the region which allows categoricalcolor
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perception of the basic colors with high efficiency.
Therefore, the new high-efficiency light source takes
positive values of Duv as far as categorical color
reproduction of the basic colors can be maintained.
Now a portion which has not been utilized in the
conventional light sources other than the new high-
efficiency light source, in the ~ange of positive Duv
values will be described in detail below.
As an international standard related to the
classification of chromaticity of ill-lrinAting light
sources for describing the light source colors, IEC
(International Electrotechnical Commission) standard has
been used. Various count~ies of the world also have their
own standards. One of these is the chromaticity
classification stAn~Ard for fluorescent lamps specified
in JIS (Japanese Industrial Standards) used in Japan.
The IEC standard determines light colors in terms of
tolerance with referenceto acentral point whichispreset
in the vicinity of the Planckian locus, while the JIS
defines upper and lower limitation lines in the vicinity
of the Planckian locus and specifies the inner region of
the limitation lines as the tolerable region.
Conventional lamps have been developed with care not
to allow the emission to deviate upward from the Planckian
locus (positive side of Duv), from the viewpoint of
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evaluating the color rendering performance of the prior
art.
In actuality, however, width of the tolerable range
is from 7.5 to 9.5 in terms of Duv in the vertical direction
in the case of the IEC, and from 10 to 19 in the case of
JIS, and therefore illllminAting light sources having
light colors in a range from O to 5 of Duv on the positive
side have been used in the prior art.
As a standard for describing the applicable range of
light source in terms of white color from a different point
of view, there is the CIE standard for signal light color.
According to this standard, the region on the positive
side of Duv out of a narrow white color region specified
along the Planckian locus has not been utilized as
illll~;nAting light source of white light.
An object of the invention is to improve the
impression of brightness in mesopic vision and scotopic
vision of the new high-efficiency light source.
It is known that, under photopic vision condition where
the illllminAnce is high, cone cells among the visual cells
work, and under scotopic vision where the illllmin~nce is
low, rod cells among the visual cells work, while under
mesopic vision where the illllmin~nce is at the
intermediate level between the above two, both cone cells
and rod cells work. However, spectral characteristic of
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conventional illllminAting light sources has been designed
assuming photopic vision wherein cone cells work.
In a situation where the new high-efficiency light
source is used, instead of a conventional light source
designed for exact color reproduction, on the other hand,
the illumination is designed with relatively low
illll~;nAnce (scotopic vision, mesopic vision).
Therefore, it is the first object of the invention
to design the spectral characteristic by placing emphasis
on a condition of relatively low illllmi~Ance while taking
into consideration the effect of the rod cells for the
new high-efficiency light source.
Second object of the invention is to improve the
impression of brightness in wide visual field of the new
high-efficiency light source.
While illllm;nAnce and l-lminAnce are used as the
photometric quantities of brightness, spectral
characteristic of illuminance and lllm;nAnce are based on
the spectral characteristic of brightness measured in a
visual angle of 2 in the fovea centralis of the eye.
However, because the eye receives light not only from a
range limited around the fovea centralis but also from
a wider visual field in the actual illllm;nAtion
environment, there have been such cases that actual
impression of brightness is different from the
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~ m;~nce, depending on the spectral distribution of
the light source.
Thus the second object of the invention is to set such
spectral characteristic of the new high-efficiency light
source that improves the impression of brightness in a
wide field of view which is felt when entering an actual
illllm;nAtion environment.
Third object of the invention is to improve the
whiteness of light color ofthenew high-efficiency light
source. The whiteness of the new high-efficiency light
source 1S poor.
Hence the invention aims to improve the whiteness of
the new high-efficiency light source as the third object.
Fourth object of the invention is to provide
incandescent lamp type color image to the new high-
efficiency light source.
That is, the invention aims to provide the impression
of an incandescent lamp type color to the new high-
efficiency light as a low color temperature light source.
DISCLOSURE OF THE I-NV~;N'1'1ON
An illuminating light source of the invention has the
following means for improving the luminous brightness in
mesopic vision and scotopic vision and improving the
brightness in wide field view of the new high-efficiency
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light source.
The present invention ofclaim lis afluorescent lamp
which ensures categorical color perception for surface
colors of at least red, green, blue, yellow and white,
while improving the luminous efficiency in scotopic
vision and mesopic vision or in a wide visual field,
wherein dominant radiation is obtained from a phosphor
which has peak emission wavelength in a wavelength region
from 530 to 580nm and a region from 600 to 650nm, flux
ratio of a phosphor having peak emission wavelength in
a wavelength region from 420 to 530nm is set to 4 to 40%
ofthetotalfluxradiatedinthedominantwavelengthband,
correlated color temperature of the lamp light color is
set to 3500R to ~ and Duv (distance from perfect radiator
locus on uv coordinates) is set within a range from 5 to
70.
The present inventionofclaim2 is afluorescent lamp
which ensures categorical color perception for surface
colors of at least red, green, blue, yellow and white,
while improving the luminous efficiency in scotopic
vision and mesopic vision or in a wide visual field,
wherein ~om; n~nt radiation is obtained from a phosphor
which has peak emission wavelength in a wavelength region
from 530 to 580nm and a region from 600 to 650nm, flux
ratio from a phosphor having peak emission wavelength in
... ......... ...
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a wavelength region from 470 to 530nm is set to 4 to 40%
of thetotalflux radiatedinthe ~omi n~nt wavelengthband,
correlated color temperature of the lamp light color is
set to 3500K to ~ and Duv (distance from perfect radiator
locus on uv coordinates) is set within a range from 5 to
70.
The present invention ofclaim 3 is a fluorescent lamp
which ensures categorical color perception for surface
colors of at least red, green, blue, yellow and white,
while improving the luminous efficiency in scotopic
vision and mesopic vision or in a wide visual field,
comprising phosphors having peak emission wavelengths in
wavelength regions from 420 to 530nm, 530 to 580nm and
600 to 650nm and light colors in aregion of y<-0.43x+0.60,
y~0.64x+0.15 and x>0.16 on the x-y chromaticity
coordinate plane.
The present invention of claim 4 is a fluorescent lamp
which ensures categorical color perception for surface
colors of at least red, green, blue, yellow and white,
while improving the luminous efficiency in scotopic
vision and mesopic vision or in a wide visual field,
comprising phosphors having peak emission wavelength in
wavelength regions from 470 to 530nm, 530 to 580nm and
600to650nm andlight colorsin aregion of y<-0.43x+0.60,
y>0.64x+0.15 and x>0.16 on the x-y chromaticity
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coordinate plane.
The present invention of claim 5 is the fluorescent
lamp of any one of the claims 1 through 4, wherein the
phosphor usedto obtainthe ~o~;nAnt radiation havingpeak
emission wavelength in a wavelength band from 530 to 580nm
is aphosphoractivatedwithterbiumorterbium andcerium,
a phosphor havingpeakemissionwavelength in awavelength
band from 600 to 650nm is a phosphor activated with
europium or manganese, a phosphor having peak emission
wavelength in a wavelength band from 420 to 530nm and a
phosphor having peak emission wavelength in a wavelength
band from 470 to 530nm are phosphors activated with
europium or europium and manganese, or antimony or
manganese, or antimony and manganese.
The present invention of claim 6 is the fluorescent
lamp of one of the claims 1 through 5, wherein phosphor
having peak emission wavelength in wavelength regions
from 530 to 580nm and 600 to 650nm comprises a single
phosphor made of (Ce,Gd,Tb)(Mg,Mn)B5O10 and
(ce~Gd)(Mg~Mn)Bsolo
The present invention of claim 7 is the fluorescent
lamp of one of the claims 1 through 6, wherein a phosphor
having peak emission wavelength in a wavelength region
from 420 to 530nm and a phosphor having peak emission
wavelength in a wavelength region from 470 to 530nm are
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halophosphate phosphor.
The present invention of claim 8 is the fluorescent
lamp of one of the claims 1 through 6, wherein a phosphor
having peak emission wavelength in wavelength region from
420 to 530nm is BaMgAll00l7:Eu, (Sr,Ca,Ba)lO(PO4)6Cl2:Eu or
BaMgAll00l7:Eu, Mn.
The present invention of claim 9 is the fluorescent
lamp of one of the claims 1 through 6, wherein a phosphor
having peak emission wavelength in wavelength region from
470 to 530nm is Sr4Al14025:Eu or Ce(Mg,Zn)Al1l0l9: Mn.
The present invention of claim 10 is the fluorescent
lamp of one of the claims 1 through 9, which includes a
phosphor having peak emission wavelength in wavelength
regions from 420 to 470nm and a phosphor having peak
emission wavelength in wavelength regions from 470 to
53Onm at the same time.
The present invention of claim 11 is the fluorescent
lamp of the claim 10, wherein the phosphor having peak
emission wavelength in wavelength regions from 420 to
470nm and the phosphor having peak emission wavelength
in wavelength regions from 470 to 530nm are
(Ba,Sr)MgAll00l7:Eu,Mn.
When the new high-efficiency light source is used in
conjunction with the conventional high color temperature
light source, the illuminating light source of the
.. , ................................. ,, ,, " " ........
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invention has the following means for improving the
whiteness of the light color.
The present invention of claim 12 is a fluorescent
lamp which ensures categorical color perception for
surface colors of at least red, green, blue, yellow and
white, while improving the whiteness of the light color,
wherein dominant radiation is obtained from a phosphor
which has peak emission wavelengths in a wavelength region
from 530 to 58Onm and aregion from 600to 65Onm, aphosphor
which has peak emission wavelength in a wavelength region
from at least 420 to 470nm is included as sub-emission,
correlated color temperature is set to 3500K to ~, Duv
(distance from perfect radiator locus on uv coordinates)
is set within an area of y<-0.43x+0.60 in the range from
5 to 70 on the x-y chromaticity coordinate plane.
The present invention of claim 13 is a fluorescent
lamp which ensures categorical color perception for
surface colors of at least red, green, blue, yellow and
white, while improving the whiteness of the light color,
wherein dominant radiation is obtained from a phosphor
which has peak emission wavelength in a wavelength region
from 530 to 580nm and aregion from600 to 650nm, aphosphor
which has peak emission wavelength in a wavelength region
from at least 420 to 470nm is included as sub-emission,
and chromaticity points (x, y) are located in an area of
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y<-0.43x + 0.60 within the region enclosed by a: (0.228,
0.351), b: (0.358, 0.551), c: (0.525, 0.440), d: (0.453,
0.440, e: (0.285, 0.332) on the x-y chromaticity
coordinate plane.
The present invention of claim 14 is a fluorescent
lamp which ensures categorical color perception for
surface colors of at least red, green, blue, yellow and
white, while improving the whiteness of the light color,
wherein dominant radiation is obtained from a phosphor
which has peak emission wavelength in a wavelength region
from 530 to 580nm, and chromaticity points (x, y) are
located in an area of y<-0.43x + 0.60 within the region
enclosedbya:(0.228,0.351),b:(0.358,0.551),c:(0.525,
0.440), d: (0.453, 0.440, e: (0.285, 0.332) on the x-y
chromaticity coordinate plane.
The present invention of claim 15 is the fluorescent
lamp of one ofthe claims 12 through 14, wherein proportion
of flux emitted by a phosphor which has peak emission
wavelength in the sub-emission wavelength region from 420
to 47Onm and flux emitted by a phosphor which has peak
emission wavelength in wavelength region from 530 to 580nm
is set to B: G with B being set within a range from 4 to
11% and G being set within a range from 96 to 89%.
- The present invention of claim 16 is the fluorescent
lamp of one of the claims 12 through 15, wherein flux
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emitted by a phosphor which has peak emission wavelength
in a range from 600 to 650nm and the sum of flux emitted
by a phosphor which has peakemission wavelength in arange
from 420 to 470nm and flux emitted by a phosphor which
has peak emission wavelength in a range from 530 to 580nm
are blended in a ratio of R: (B+G) where R is set within
a range from 0 to 28% and B+G is within a range from 100
to 72 %.
The present invention of claim 17 is the fluorescent
lamp of one of the claims 12 through 15, wherein a phosphor
activated with europium is used as the phosphor having
peak emission wavelength in a range from 420 to 470nm,
a phosphor activated with terbium or terbium and cerium
is used as the phosphor having peak emission wavelength
in a region from 530 to 580nm, and a phosphor activated
with manganese or europium is used as the phosphor having
peak emission wavelength in a range from 600 to 650nm.
The present invention of claim 18 is the fluorescent
lamp of the claim 14 which is constituted from a phosphor
activated with terbium having peak emission wavelength
in a region from 530 to 580nm and halophosphate phosphor.
The present invention of claim 19 is the fluorescent
lamp of one of the claims 12 through 17, wherein phosphor
having peak emission wavelength in wavelength regions
from 530 to 580nm and 600 to 650nm comprises a single
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phosphor made of (Ce,Gd,Tb)(Mg,Mn)B5O10 and
(ce~Gd)(Mg~Mn)Bsolo~
The present invention of claim 20 is the fluorescent
lamp of one of the claims 12 through 17 or claim 19, wherein
a phosphor having peak emission wavelength in wavelength
region from 420 to 470nm is BaMgAll0Ol7:Eu,
(Sr~ca~Ba)~o( PO4)6Cl2: Eu or BaMgAl10O17:Eu, Mn.
When the new high-efficiency light source is used in
conjunction with the conventional low color temperature
light source, the illuminating light source of the
invention has the following means for improving the sense
of incongruity of the light color as incandescent color.
The present invention of claim 21 is a fluorescent
lamp which ensures categorical color perception for
surface colors of at least red, green, blue, yellow and
white, wherein ~om;n~nt radiation is obtained from a
phosphor which has peak emission wavelength in a
wavelength region from 530 to 580nm and a region from 600
to 650nm, correlated color temperature is set to 1700K
to ~, and the emission light color is set within a range
where the region of Duv (distance from perfect radiator
locus on uv coordinates) from 5 to 70 and the region of
chromaticity point (x, y) inside quadratic curve of
fx2+gy2+hxy+ix+jy+k=0 (f=0.6179, g=0.6179, h=-0.7643,
i=-0.2205, j=-0.1765, k=0.0829) overlap each other on the
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x-y chromaticity coordinate plane.
The present invention of claim 22 is a ~luore~cen~
lamp which ensures categorical color perception for
surface aolors of at least red, green, ~lue,.ye~low and
white, wherein dominant ra~ation is obtained from a
phosphor which ha~3 peak emis~ion wavelength in a
wavelength region from 530 to 580nm and a region from 600
to 650nm, the region of chromaticity point (x, y) i~ in
a region which is the inside part of the quadratic curve
of fx2+gy2+h~y+ix~jy+k=0 (f=0.6~79, g=0.6179, h--0.7643,
i=-0.2205, j=-0.1765, k-0.0829) other than the area
defined ~y 1 ~o v range enclosed by line seg~ent~
connecting the chromaticity points l: (0.4775, 0.4283~,
m: (0~4594, 0.3971), n: (0.4214, 0.3887), Ot (0.4171r
0.3846), p: (0.3903, 0.371g), ~: tO.3805,Ø3642~, ~s
(0.36~6, 0.3905), 8: (0.3938, 0.40g7), t: (0.4021~
0.4076), u: (0.4341, 0.4233) and v: (0.4348, 0.4185) on
the x-y ~hromaticity coordinate plane.
The present invention o~ claim 23 i~ the fluorescent
la~p of one of the claims 21 through 22 which obtains
predominant radiation from a phosphor having peak
emission wavelength in a wavelength region from 530 to
560nm and a region from 600 to 650nm, wheroin ~:coportion
of flux emitted ~y a phosphor which ha~ peak emi6~ion
wavelength in the wavelength region from 530 to 560nm ~nd
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flux emitted by a phosphor which has peak emission
wavelength in wavelength region from 600 to 650nm is set
to G: R (%) with G being set within a range from 70 to
59 and R belng set within a range from 30 to 41.
The present invention of claim 24 is the fluorescent
lamp of one of the claims 21 through 23 which obtains
pre~om;n~nt radiation from a phosphor having peak
emission wavelengths in a wavelength region from 530 to
560nm and a region from 600 to 620nm and sub-emission is
obtained from a phosphor having peak emission wavelength
in a wavelength region from 420 to 530nm, wherein flux
ratio (B+BG): G: R (%) of phosphors having peak emission
wavelength in wavelength regions from 420 to 530nm (B+BG),
530 to 560nm (G) and 600 to 620nm (R) is set so that B+BG
is from 0 to 3, G is from 59 to 71 and R is from 41 to
26.
The present invention of claim 25 is the fluorescent
lamp of one of the claims 21 through 24, wherein a phosphor
activated with terbium or terbium and cerium is used as
the phosphor having peak emission wavelength in a region
from 530 to 580nm, and a phosphor activated with europium
or manganese is used as the phosphor having peak emission
wavelength in a range from 600 to 650nm.
- The present invention of claim 26 is the fluorescent
lamp of one of the claims 21 through 25, wherein phosphor
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having peak emission wavelength in wavelength regions
from 530 to 580nm and 600 to 650nm comprises a single
phosphor made of (Ce,Gd,Tb)(Mg,Mn)B5O10 and
(Ce,Gd)(Mg,Mn)B5O10
When the invention is applied to a light source other
than fluorescent lamp, the illuminating light source of
the invention has the following meAn~ for solving
problems.
The present invention of claim 27 is the fluorescent
lamp of one of the claims 1 through 26 which is used as
exterior lighting , road lighting , street lighting,
security lighting ,car lights, tunnel lighting, public
square lighting, warehouse lighting ,standby lighting or
industrial lighting.
The present invention of claim 28 is a metal halide
lamp which has light color and emission spectrum
equivalent to those of the fluorescent lamp of one of the
claims 1 through 26.
The present invention of claim 29 is the metal halide
lamp of the claim 28 which is used as exterior lighting ,
road lighting , street lighting, security lighting ,car
lights, tunnel lighting, public square lighting,
warehouse lighting ,standby lighting or industrial
lighting.
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig.1 is a graph showing the spectral characteristic
of a fluorescent lamp according to a typical embodiment
of the invention.
Fig.2 and Fig.3 show the comparison of various
relative luminous efficiency normalized to peak height
which is set to 1.
Fig.4 shows difference between Vb10(~) and Vb 2( ~ ) ~
difference between VM( ~ ) and V(~), difference between
V10(~) and V(~)=V2(~) and difference between V'(~) and
V( ~ ).
Fig.5 shows the basic spectral sensitivity of three
kinds of cone cell (S cone cell, M cone cell, L cone cell)
of the eye and the basic spectral sensitivity of rod cell,
normalized to peak height which is set to 1.
Fig.6 shows the range of colors the fluorescent lamp
of the invention (claims 3, 4) on x-y chromaticity
coordinate plane.
Fig.7 shows the theoretical efficiency of light on
x-y chromaticity coordinate plane.
Fig.8 shows the correction factor F of lllmi~nce on
x-y chromaticity coordinate plane.
Fig.9 shows points on spectral locus of unique
colors.
Fig.10 shows chromaticity values x, y of light
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sources 17 (la) through 21 (le) and regression line 22
(y=-0.43x + 0.58) thereof on x-y chromaticity coordinate
plane.
Fig.11 shows the relation between chromaticity
values (x, y) = a: (0.228, 0.351), b: (0.358, 0.551), c:
(0.525, 0.440), d: (0.453, 0.440, e: (0.285, 0.332),
straight line 23 (y<-0.43x + 0.60) and color names of the
light source in the case of claims 13 and 14.
Fig.12 through Fig.16 show the spectral
distributions of light sources (lf) through (lj) which
ar constitutede from_20W fluorescent lamps.
Fig.17 shows the spectralcharacteristic when the new
high-efficiency light source is realized by the
fluorescent lamp.
Fig.18 shows the chromaticity range 25 defined by the
chromaticity values (x, y) = a: (0.228, 0.351), b: (0.358,
0.551), c: (0.525, 0.440), d: (0.453, 0.440), e: (0.285,
0.332), (y<-0.43x + 0.60) on chromaticity coordinate
plane in the case of claims 13 and 14 of the invention.
Fig.19 shows 21 light colors of tl through t21 on x-y
color point coordinate.
Fig.20 shows the acceptance rate of each test light
source as incandescent lamp type color with the
chromaticity point (x, y) thereof.
Fig.21 shows the relation between points l through
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v of claim 21 of the invention and the curve 23.
Fig.22 shows the range of the light colors of
fluorescent lamps qualified by JIS used as reference.
Fig.23 through Fig.26 show the spectral distribution
of an embodiment with fluorescent lamp when flux ratio
LAP:YOX is varied.
Fig.27 shows the spectral distribution of a
fluorescent lamp according to another embo~;me~t of the
invention.
Fig.28 shows the relation between the value of
V'(~)/V(~) and the various light sources.
Fig.29 shows the relation between the value of
Vl0(~)/V(~) and the various light sources.
BEST MODE FOR EXECUTING THE PRESENT INVENTION
The new high-efficiency light source provides a light
source of high efficiency while ensuring such a level of
color reproduction that allows categorical color
perception for surfacecolors ofat least red, green, blue,
yellow, white and black, by concentrating the radiation
energy in a wavelength band consisting mainly of green
and red. In addition to this, the first embodiment of the
invention adds radiation in blue or blue-green band
thereby to improve the luminous brightness in mesopic
vision and scotopic vision or the luminous brightness in
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wide visual field.
A fluorescent lamp as a typical embodiment of the
invention is shown in Fig.l.
Solid line 1 in Fig.l shows the spectral distribution
generated when the invention is embodied with fluorescent
lamps. Dashed line 2 shows the spectral distribution
generated when the new high-efficiency light source is
constituted from fluorescent lamp. According to the
invention, as shown in Fig.l, luminous brightness in
mesopic vision and scotopic vision and luminous
brightness in wide field of view can be improved over the
new high-efficiency light source, by emphasizing the
relative power of spectral characteristic of blue or
blue-green. The basis for this will be explained in detail
below.
Response characteristic to brightness of light
varies depending on the spectrum, and is called the
relative luminous efficiency or relative luminous
efficiency function. Brightness of ill-l~in~tion is
generally evaluated in terms of the standard photopic
vision spectral luminous efficacy function (hereinafter
referred to as V(~)) defined by CIE (Commission
Internationale de I'Eclairage). This is based on the
sensitivity characteristic of the cone cells to
brightness under such a condition that the eyes have
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accustomed to bright environment, namely photopic vision.
It is known that the center of sensitivity under this
condition is located at 555nm, and ill--mi n~ting light
sources are usually evaluated in terms of the efficiency
of spectral characteristic with respect to V(~).
On the other hand, as an evaluation criterion based
on the sensitivity characteristic of rod cells to
brightness under such a condition that the eyes have
accustomed to dark environment, namely standard scotopic
vision, standard scotopic vision spectral luminous
efficacy function (hereinafter referred to as V'(~))
defined by CIE (International Illumination Commission)
is used. It is known that the peak of sensitivity under
this condition is located at 507nm
It is said that eyes work with an intermediate
relative luminous efficiency characteristic between the
above two, in mesopic vision environment where brightness
is at an intermediate level between photopic vision and
scotopic vision. Thus the characteristic varies depending
on the condition of the eye adapting to the environment.
That is, there is a fact that, in scotopic vision or
mesopic vision, sensitivity of the eye to light becomes
higher in blue or blue-green band compared to photopic
vision. It is indicated that effective or luminous
brightness can be improved by enh~ncing the blue or
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CA 02249613 1998-09-18
blue-green portion of the spectrum of the new high-
efficiency light source which is often used in environment
designed lower illll~inAnce level than the conventional
illllmin~ting light sources which are normally designed
on the basis of efficiency in photopic vision.
Meanwhile various modifications have been made to
the V(~).
First, Judd's modified color matching function
(hereinafter referredto as VM( ~ ) ) willbe describedhere.
This modification is based on the fact that Vt~) assigns
lower than actual values to blue band in the shorter
wavelength region. Although it is true that VM( ~ )
represents the actual response more accurately, it cannot
also be denied that changing the photometry system is not
desirable. Thus the modified function is not employed in
evaluating the brightness of general lamps, although it
is authorized as CIE Publication No.86: 2 Spectral
luminous efficiency function for photopic vision (1990).
Now a model of relative luminous efficiency based on
a different magnitude of view field than V(~) will be
described below. While V(~) is V2(~) which isconstructed
on the basis of central view with a visual angle of 2~
in the foveacentraliswherethevisualacuity ishighest,
there is another functionconstructedonthe basis ofwider
visual field (10~ ), namely V10(~) which is recommended
- 24 -
CA 02249613 1998-09-18
as CIE 1964 supplementary photometry system.
Because light entering the eye in an actual
environment is not limited to that coming in a narrow
visual field but includes that coming in a wider visual
field, V10(~) is considered to better reflect the actual
situation when evaluating the impression of brightness
in wider visual field.
Cone cells include S (blue) conecell which has higher
sensitivity in short wavelengths, L (red) cone cell which
has higher sensitivity in long wavelengths and M (green)
cone cell which has higher sensitivity in intermediate
wavelengths. Because there are few S cone cells in the
fovea centralis and there are many S cone cells at
peripheral vision in higher concentration, assuming a
greater visual field leads to greater emphasis being
placed on the sensitivity to blue light.
Because the fovea centralis is also void of rod cells
and V~(~) is a relative luminous efficiency constructed
at points away from the fovea centralis, it can be seen
that blue or blue-green band has greater weight in the
correction of light source brightness designed for use
with lower ill~ n~nce in scotopic vision, mesopic vision
and in the correction of brightness perception for light
incident on the eye from wider field of view in the actual
environment.
- 25 -
CA 02249613 1998-09-18
In contrast to V(~) which is constructed on the basis
of results obtained by the flicker photometry technique
wherein the subject eye is exposed alternately to light
of different colors while minimizing the flicker or the
sequential comparison technique wherein light of slightly
different colors is matched, relative luminous efficiency
constructed by the direct matching method wherein
brightness is directly compared will be described below.
This technique directly extracts the visual
perception of brightness, and is specified as CIE
Publication No.75: Spectral luminous efficiency
functions based upon brightness matching for
monochromatic point sources 2~ and 10~ fields (1988).
Function based on 2~ field is called Vb 2(~1 ) and one based
on 10~ field iscalledVb10(~), inwhichcase direct visual
perception of brightness is well represented but smooth
profile is not provided.
However, the direct matching method also
overestimates the sensitivity to blue when the field of
view is wider, when the difference between Vb 2(~1,) and
Vb10(~) is taken into consideration.
Although V10(~)~ VM( ~ ), V' ( ~ )~ Vb 2( ~ ) and Vblo(~)
well reflect the actual situation than V(~) depending on
- the time and occasion, they are regarded as auxiliary
photmetric quantities of brightness and are not used in
- 26 -
.. ..
CA 02249613 1998-09-18
the brightness evaluation and development of ordinary
lamps.
However, on the actual situation when these
evaluation functions V10(~), VN( ~, ), V' (~ ), Vb2(~ ) and
Vb1O(~) are used integrally, it is made possible to
improve the l-lminous or effective brightness of the new
high-efficiency light source which is typically used
under relatively low illllm;nAnce.
Fig.2 and Fig.3 compare various relative luminous
efficiencies normalized to the peak height which is set
to 1. Fig.2 shows V(~), V10(~), VM( ~ ) and V'(~). Fig.3
shows Vb 2( ~ ) and Vb1O(~) which are derived by a
psycophysical technique different from that employed for
V(~), with V(~) shown as reference.
Based on the above discussion, Fig.4 shows the
difference among various relative luminous efficiencies
as difference between Vb1O(~) and Vb2(~), difference
between VM( ~ ) and V(~), difference between V10(~) and
V(~)=V2(~) and difference between V'(~) and V(~).
When these various measures of relative luminous
efficiency are taken into consideration, positive side
of the graph corresponds to the portion which has been
underestimated in theconventional V(~), showingthat the
spectral power is concentrated in blue or blue-greenband.
When these are studied individually, the following
- 27 -
CA 02249613 1998-09-18
relationships can be derived for the pea~s and the ranges
of various measures of relative luminous efficiency.
* Peak of difference between Vb10(~) and Vb2(~)
occurs at 500nm, while width of 50% height of peak is in
a region from 460 to 520nm, and width of 80% height of
peak is in a region from 480 to 505nm.
* Peak of difference between VM( ~ ) and V(~) occurs
at 435nm, while width of 50% height of peak is in a region
from 415 to 450nm, and width of 80% height of peak is in
a region from 420 to 445nm.
* Peak of difference between V10(~) and V(~) =V2(~)
occurs at 500nm, while width of 50% height of peak is in
a region from 465 to 515nm, and width of 80% height of
peak is in a region from 480 to 505nm.
* Peak of difference between V~(~) and V(~) occurs
at 490nm, while width of 50% height of peak is in a region
from 445 to 515nm, and width of 80% height of peak is in
a region from 470 to 505nm.
The following findings have also be known which are
shown here as mere reference because these are derived
by different techniques and therefore cannot be directly
compared with the above.
* Peak of difference between Vb,2(~) and V(~) occurs
at 530nm, while width of 50% height of peak is divided
into a region from 430 to 480nm and a region from 510 to
- 28 -
CA 02249613 1998-09-18
535nm because of distortion in the relative luminous
efficiency, and width of 80% height of peak is in a region
of 530nm+2.5nm.
*Peak of difference between Vb10(~) and V(~) occurs
at 500nm, while width of 50% height of peak is in a region
from 450 to 520nm, and width of 80% height of peak is in
a region from 475 to 510nm.
Under such consideration such range which is on a
considerablly positive side and is to be modified on
spectral distribution on FIG. 4 ,is described below.
Bycombining these correctionbands in thewavelength
band below the major emission wavelength of the new
high-efficiency light source, it can be concluded that
the range where correction should be applied is from 420
to 530nm at the ~ m.
The invention is based on this range.
Further in this range, a region which allows particularly
high effect will be discussed below.
Because VM( ~ ) primarily represents correction in
blue band of wavelengths below 455nm where S cone cells
work and many of corrections made in short wavelength
region of the visible radiation are for intrinsically low
sensitivity, the region where the highest effect of
corrections other than difference between VM( ~ ) and V(~)
can be obtained within the width of 80% height of peak
- 29 -
. .. ~, . .= ..
CA 02249613 1998-09-18
is from 470 to 530nm.
Fig.5 shows the basic spectral sensitivity of three
kinds of cone cell (S cone cell, M cone cell, L cone cell)
of the eye and the basic spectral sensitivity of rod cell,
normalized to peak height which is set to 1.
It canbe seenthatthe rodcellwhich works in mesopic
and acotopic vision and has a peak of spectral sensitivity
between those of the S cone cell and the M cone cell.
Ordinary illuminating light sources aim at
stimulating three kinds of cone cells (L cone cell, M cone
cell and L cone cell) which work in photopic vision, but
radiation energy of the new high-efficiency light source
is concentrated in green and red bands, thereby to
stimulate r~;~ly two kinds of cone cells (M cone cell and
L cone cell), thus giving stimulus to the r-g opponent
color response system of the visual system.
In the design of conventional illllm;n~ting light
source, because use in photopic vision is assumed,
spectral sensitivity of the rod cells has not been taken
into consideration. In contrast, the improvement of
scotopic vision, mesopic vision and luminous brightness
among the technologies of the invention is based on the
stimulation of the two kinds of cone cells (M cone cell
and L cone cell) and the rod cells. Thus it is effective
to concentrate the portion of radiation energy to be added
- 30 -
.
CA 02249613 1998-09-18
in the new high-efficiency light source in the blue-green
band of wavelengths from 470 to 530nm, in order to decrease
the stimulation to the S cone cell which contributes less
to the improvement of brightness perception and improve
the efficiency of the stimulation to the rod cells.
Also because the S cone cells are densely distributed
around the fovea centralis of the retina, wider field of
view leads to overestimation of the sensitivity related
totheScone cells. Therefore, theimprovement ofluminous
brightness in a wide view field among the technologies
of the invention can be achieved by placing emphasis on
the stimulation of the S cone cells which are densely
distributed around the fovea centralis. For this purpose,
it is effective to concentrate the portion of radiation
to be added in the new high-efficiency light source in
the blue band of wavelengths from 420 to 470nm
Because ranges of relative luminous efficiency of the S
conecell androdcellsoverlap onthe spectrum, wavelength
band where both the luminous brightness in mesopic vision
and scotopic vision and the luminous brightness in wide
field view aretobe improvedis from 420to 530nm. However,
since the values of relative luminous efficiency are
intrinsically low in short wavelength region of the
visible radiation, e~rhA~is is preferably placed on the
region from 470 to 530nm in order to improve the above
., . . ,~ ." . ,. ~
CA 02249613 1998-09-18
two aspects.
In order to improve the luminous brightness in
mesopic vision and scotopic vision or in a wide field of
view while ensuring categorical color perception for
~ m;n~ted object surface colors of at least red, green,
blue, yellow and white, it is preferable to enh~nce the
blue or blue-green component of the lamp color. For this
purpose, it is preferable that the correlated color
temperature of the lamp color be set to a high level and,
in case thecorrelatedcolortemperaturewhich istheindex
of ordinary light source colors is used as the index, it
is preferably set to 3500K or higher or alternatively the
chromaticity of the lamp color in a range of y < -0.43x
+ 0.60 on the x-y chromaticity coordinate plane.
Fig.6 shows the range of the light colors generated
by the fluorescent lamps of the invention (claims 3, 4)
on the x-y chromaticity coordinate plane. These
inventions can be realized by producing the light colors
in the region determined by three relations of inequality,
y<-0.43x + 0.60 of Fig.6-3, y>0.64x + 0.15 of Fig.6-4 and
x>0.16 of Fig.6-5. The reason will be described below.
The region of y=0.64x + 0.15 corresponds to the upper
limit of the white lamp light toward green specified in
the CIE Technical Report CIE 107-1994;Review of the
official recommendations of the CIE for the colours of
- 32 -
.
CA 02249613 1998-09-18
signal lights.
Thus it is indicated that the invention provides light
colors which have values of Duv on the positive side of
the light generally used as white light of Fig.6-6 and
belong to a region of illuminating light which has not
been used in the prior art.
The region of y<-0.43x + 0.60 is a result of adding
a phosphor having peak emission wavelength in a region
from 420 to 530nm or a phosphor having peak emission
wavelength in a region from 470 to 530nm to the new
high-efficiency light source which emits radiation in
green and red bands, thereby deter~ini~g the point where
chromaticness ~;r;nishes, through a process of visual
experiment.
In the experiment, as a typical sample of the new
high-efficiency light source which emits radiation in
green and red bands, such a light source was used as light
from a fluorescent lamp coated with [chemical formula 1]
LaPO4: Ce, Tb (LAP), which is commonly used as green light
emitting phosphor, and a fluorescent lamp coated with
[chemical formula 2] Y2O3: Eu, (YOX), which is commonly
used as red light emitting phosphor, were blended. Then
light fromthis light source was furtherblended with light
from a fluorescent lamp coated with [chemical formula 3]
(Sr, Ca, Ba)1O(PO4)6Cl2: Eu (SCA) which is commonly used
CA 02249613 1998-09-18
as blue light emitting phosphor having peak emission
wavelength in a range from 420 to 470nm or light from a
fluorescent lamp coated with [chemical formula 4]
Sr4All4O25: Eu (SAE) which is commonly used as blue-green
light emitting phosphor having peak emission wavelength
in a range from 470 to 530nm, and a point where
chromaticness diminished was determined by subjective
evaluation.
Result of the experiment is shown in Fig.6. Positions
of light colors of these fluorescent lamps, which are
coated with the phosphors individually, on the x-y
chromaticity coordinate plane are also shown in the
drawing: numeral 7 indicating LAP, 8 indicating YOX, 9
indicating SCA and 10 indicating SAE.
Values of x-y chromaticitycoordinates of these light
colors are as follows.
7 for LAP: x=0.332, y=0.540
8 for YOX: x=0.596, y=0.332
9 for SCA: x=0.156, y=0.079
10 for SAE: x=0.152, y=0.356
Point 11 in Fig.6 is a plot of a point where
chromaticness of the light source begins to ~;m; n;sh while
blue light (chemical formula 3) is gradually blended with
the light emitted by the sample of the new high-efficiency
light source which is constituted so that flux ratio of
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~ .. ...... .. . . .
CA 02249613 1998-09-18
green light [chemical formula 1] to red light [chemical
formula 2] is LAP (green): YOX (red)=100:0. Point 12 is
a plot of the result of the subjective evaluation
experiment with blending ratio of LAP: YOX=95: 5. Point
13 is a plot ofthe result of similar subjective evaluation
experiment with blending ratio of LAP: YOX=90: 10. Point
14 is a plot of the result of similar subjective evaluation
experiment with blending ratio of LAP: YOX=85: 15. Point
15 is a plot of the result of similar subjective evaluation
experiment with blending ratio of LAP: YOX=80: 20.
From the results 11 through 15, regression line of
y=-0.43x+0.58 is obtained. However, because subjective
evaluation involves variations, digit of the second
decimal place of the y intercept was carried up so that
all plots are included, thereby to give y<-.43x+0.60
(equation 1).
Second embodiment of the invention where whiteness
of the light emitted by the new high-efficiency light
source is ~nhAnced will be described in detail below.
Point 16 in Fig.6 is a plot of a point where
chromaticness of the light emitted by the lamp begins to
~im;nish while blue-green light of a phosphor (chemical
formula 4) is gradually blended with the light emitted
by the sample which was constituted to have a flux ratio
of LPA ( green): YOX (red)=80: 20.
.. ~ . . .. .
CA 02249613 1998-09-18
This result is also similar to that of the experiment
described above where light emitted by the blue phosphor
was blended, giving the relationship y<-.43x+0.60. Thus
it can be seen that major factor which determines the point
where whiteness beginstobe perceived inthe blended light
color is the chromaticity rather than the bandwidth of
the blended light. And the equation (1) represents the
border where the yellow-greenishness of the light of the
new high-efficiency light source changes to blue-greenish
light as the radiation in blue or blue-green band is
enh~nced, namely chromaticness begins to ~;minish as blue
and yellow which are mutually opponent colors cancel each
other.
The region of x>0.16 represents the tolerable limit
for the intensity of chromaticness in the directiontoward
blue or blue-green. Points 9 and 10 of Fig.6 represent
the light colors of fluorescent lamps made by using the
phosphors of [chemical formula 3] and [chemical formula
4] plotted on the chromatic diagram. The inequality x>0.16
is determined in consideration of the practical
feasibility so that the chromaticities of the points 9
and 10 are not included.
Although increasing the radiation in blue or blue-green
region improves the spectral luminous efficiency in
scotopic vision andmesopic visionor wideview fieldunder
- 36 -
... .
CA 02249613 1998-09-18
the same illuminance (same luminous flux), the increase
of the radiation in these regions intrinsically leads to
a decrease in the efficiency of the light source in terms
of photometric quantity V(~). The increase of the
radiation in these regions also causes the radiation in
red region to relatively decrease, resulting in lower
reproduction of red light colorwhich isused for important
signs such as the indication of danger.
Radiation intensity of light is related to the
photometric quantity of illumination via V(~), while
efficiency of mono-color having a wavelength of 555nm at
the peak of V(~) reaches the mA~;mllm of 683 lm/W. While
efficiency of light of wavelengths other than 555nm is
lower than 683 lm/W, this relation is indicated in Fig.7
where the theoretical efficiency of light is plotted on
the x-y chromaticity coordinate plane.
From this result, it can be seen that the theoretical
efficiency of light decreases toward bottom right (blue
or blue-green) on the x-y chromaticity coordinate plane.
Although it would be expected that light of the same
lllm;n~nce is perceived to be of the same brightness
regardless of whether it is white light or light colored
in blue-green, chromatic light is felt to be brighter than
white light in actuality. Denote the brightness perceived
of chromatic light be B and lnm;nAnce of chromatic light
CA 02249613 1998-09-18
be L, then the ratio B/L of the chromatic light changes
on the x-y chromaticity coordinate plane. Value of
log(L)+F (F is a correction factor) corresponds to the
brightness B, and the relation between the correction
factor F of l-lrin~nce and the position on the x-y
chromaticity coordinate plane is represented by the
correction factor F of lllrin~nce on the x-y chromaticity
coordinate plane of Fig.8. The correction factor F is
supposedly required because Abney's law, which asserts
that light fluxes having different spectra are additive,
is not expected to hold strictly, and profile of V(~)
which is the basis for the additiveness is not complete.
It can be seen that proportion of the correction
increases toward bottom right (blue or blue-green) on the
chromaticity coordinate plane. While this indicates the
underestimation of V(~) in blue or blue-green region, the
region of light colors on the x-y chromaticity coordinate
plane oftheinventioncoverstheblueandblue-greenlight
colors which have been theoretically underestimated.
Fig.9 shows the positions of unique hues on the
spectral locus. Unique hue refers to the light stimulus
of wavelength which gives the color perception responsive
to the stimuli of pure red, green, blue and yellow, when
single spectrum only is extracted from wavelengths of
light.
- 38 -
CA 02249613 1998-09-18
When light having an intermediate spectrum between the
unique yellow and unique green is viewed, for example,-
both yellowishness and greenishness are perceived.
Fig.9 shows the unique colors of red, green, blue and
yellow connected with the equal-energy white color W by
line segments.
In theory, light in the region defined by unique
yellow, unique green and equal-energy white color W on
the x-y chromaticity coordinate plane causes the
perception of yellowishness and greenishness. As the
spectrum departs from white and becomes nearer to Gaussian
spectrum of edge of mono-color, the chromaticness thereof
is intensified.
Theoretically speaking, opponent colors of
yellowishness and bluishness compete with each other on
the line (LN) connecting unique green and white, provided
the color difference from white is the same.
The line LN is similar to the line of the subjective
evaluation experiment (equation 1) described previously,
and it is supposed that the result of the subjective
evaluation issupportedbysuchatheory as describedabove
It is thought that yellowishness and bluishness compete
with each other when the rate of stimulus to the S cone
cell exceeds a certain level with respect to the rate of
stimulus to the M cone cell and the L cone cell.
- 39 -
, . . ..
CA 02249613 1998-09-18
As described above, a light source of high spectral
luminous efficiency and mitigated intensity of
chromaticness received from colored light can be made by
applying the chromaticity range of the invention.
In this range, use of a range of colors which are near
white and where perception of yellowish green is
overridden by the perception of bluish green is
particularly desirable, from the view point of spectral
luminous efficiency and light color.
With this respect, the new high-efficiency light
source modified to emit light of increased whiteness
according to the second embodiment of the invention will
be described in detail below.
When constituting the light source of the invention
from fluorescent lamp, radiation energy emitted thereby
can beconcentratedin aspecifiedwavelength band byusing
rare-earth element phosphors.
In this embo~ime~t, phosphors having peak wavelength
for a region from 530 to 580 nm is a phosphor activated
withterbium orterbium andcerium , aphosphor for aregion
from 600 to 650 nm is a phosphor activated with europium
or europium or a manganese, a phosphor for a region from
420 to 530 nm and a phosphor for region from 470 to 530
nm are such phosphor activated with europium, or europium
and manganese, or antimony, or manganese, or antimony and
- 40 -
~,
CA 02249613 1998-09-18
manganese.
More specifically, phosphors having peak wavelength
band from 530 to 58Onm is [chemical formula 1] LaPO4: Ce,Tb,
[chemical formula 5] CeMgAll10l9: Tb, [ chemical formula 6]
(Ce, Gd)MgB50l0:Tb or [chemical formula 7] La203 ~ 0.2SiO2 -
O.9P205:Ce,Tb, phosphor from 600 to 650nm is [chemical
formula 2] Y203:Eu or [chemical formula 8~ (YGd)203:Eu.
These phosphors for generating main wavelength are as
described in the foregoing application of
PCT/JP96/02618(Light Source).
As examples of phosphors having peak emission
wavelength in a band from 420 to 530nm, there are phosphors
which have peak wavelength in a region from 420 to 470nm
and are made of [chemical formula 9] BaMgAll00l7:Eu and
[chemical formula 3] (Sr,Ca,Ba)lO(PO4) 6C12: Eu- While there
are many phosphors of chemical compositions similar to
these, [chemical formula 10] (Sr,Ca,Ba,Mg)lO(PO4) 6ClZ Eu
which includes Mg added thereto is included in the scope
of the invention. And phosphors which have peak wavelength
in a region from 470 to 530nm are [chemical formula 4]
Sr4All4025:Eu or [chemical formula 11] Ce(Mg,Zn)AlllOlg:Mn.
Then radiation in a region from 420 to 530nm can be
achieved by making a phosphor layer comprising two
phosphors which have peak emission wavelength in regions
from 420 to 470nm and from 470 to 530nm, respectively.
- 41 -
CA 02249613 1998-09-18
In this case, in addition to the improvements of luminous
brightness in scotopic vision, mesopic vision and in wide
field of view, perception of whiteness can be efficiently
improved.
As another example of phosphor which radiates in the
region from 420 to 530nm, there is [chemical formula 12]
(Ba,Sr)MgAl100l7:Eu,Mn. Scope of the invention also
includes [chemical formula 13] BaMgAll0017:Eu,Mn which
does not include Sr. Increasing the concentration of
activation component Eu causes the radiation in a region
from 420 to 470nm to increase, and increasing the
concentration of activation component Mn achieves the
radiation in a region from 470 to 530nm.
In this case, because proportion of radiation in the region
from 420 to 470nm and that in the region from 470 to 530nm
can be set with a single phosphor, color tone can be set
easily and color unevenness can be suppressed during
manufacture of the lamp.
By making the phosphor having peak emission
wavelength in a region from 530 to 580nm from [chemical
formula 14] (Ce,Gd,Tb)(Mg,Mn)B5010 and making the phosphor
having peak emission wavelength in a region from 600 to
65Onm from [chemical formula 15] (Ce,Gd)(Mg,Mn)B50l0,
proportion of radiation in the region from 530 to 580nm
and that in the region from 600 to 650nm can be set with
- 42 -
... ......... . .. . ...
CA 02249613 1998-09-18
a single phosphor by using the same base material for the
phosphors, and therefore color tone can be set easily and
color unevenness can be suppressed during manufacture of
the lamp.
The fluorescent lamp of the invention can also be
manufactured with a low cost when calcium halophosphate
phosphpor [chemical formula 16] Ca5(PO4)3(F,Cl):Sb,Mn is
used for the phosphor having peak emission wavelength in
a region from 420 to 530nm. In this phosphor, because the
activation agent Mn has peak of radiation in yellow region
and the activation agent Sb has peak of radiation in
blue-green region, light in blue-green region can be
increased by increasing the concentration of the
activation agent Mn. The claims of the invention includes
a case where Mn is omitted and, in this case, single-
peak radiation having blue-white light color is obtained.
Now the second embodiment of the invention will be
described below.
The second embodiment of the invention is the new
high-efficiency light source wherein chromaticity of the
light color is decreased and whiteness is e~h~nced.
According to the second embo~;ment of the invention,
radiation in a region from 420 to 470nm is increased
thereby to decrease the chromaticity of the light color
of the new high-efficiency light source and increase
- 43 -
CA 02249613 1998-09-18
whiteness, while minimizing the increase in radiation in
regions other than the ~m; nAnt radiation wavelength
bands from 530 to 580nm and from 600 to 650. For this
purpose, unlike the first embodiment of the invention,
radiation is added to the blue region of wavelengths from
420 to 470nm. Constitution of the phosphors is based on
the first embodiment.
In this embodiment, light color of the light source
ean be greatly changed with a m;~imum addition of
sub-emission, by inereasing the radiation in shorter
wavelength compared to the case of the first embo~;ment.
Speeifically, subjeetive evaluation similar to that
of the first embo~;m~nt of the invention was eondueted
as follows. As a sample of the new high-effieieney light
souree whieh emits radiation coneentrated in green and
red regions, sueh a light source was used whieh emits
blended lights from a fluoreseent lamp eoated with
[chemical formula 1] LaPO4: Ce, Tb (LAP) whieh is eommonly
used as green light emitting phosphor and from a
fluoreseent lamp coated with [ehemieal formula 2] Y2O3:
Eu, (YOX) which is eommonly used as red light emitting
phosphor. Then light emitted by this light source was
further blended with light emitted by a fluorescent lamp
coated with [chemical formula 3] (Sr, Ca, Ba)lO(POg)6Cl2:
Eu (SCA) which is eommonly used as blue light emitting
- 44 -
.. ..
CA 02249613 1998-09-18
phosphor having peak emission wavelength in a range from
420 to 470nm, and a point where chromaticness diminished
and whiteness increased was determined by adjustment
method.
In the subjective evaluation, subjects were four
adult persons having normal color vision and three trials
were made under one condition.
Flux ratio of green light emission [chemical formula
1] and red light emission [chemical formula 2] in the
sample of the new high-efficiency light source waschanged
in five steps from LAP (green): YOX (red)=100: 0, LAP
(green): YOX (red)=95: 5, LAP (green): YOX (red)=90: 10,
LAP (green): YOX (red)=85: 15to LAP(green): YOX (red)=80:
20. Chromaticity values x and y, calcium halophosphate
phosphpor and Duv are shown in Table 1.
[Table 1] Blendedlight with different proportions of LAP
and YOX (5 variations)
Correlated
LAP : YOX color
(Flux x y Duv
ratio, %) temperature
100 : 0 0.3323 0.5397 5531 74.5
95 : 5 0.3552 0.5234 5096 62.9
90 : 10 0.3721 0.5083 4757 53.3
85 : 15 0.3934 0.4897 4311 41.3
- 45 -
CA 02249613 1998-09-18
80 : 20 1 0.4086 1 0.4792 1 3992 1 33.9
Results of the subjective evaluation are shown in Table
2.
[Table 2] Experimental comparison of flux ratio,
chromaticity values x & y, correlated color temperature
and Duv of light sources when chromaticness A;min;shes
and light begins to be perceived as white
Correlated
LAP : YOX : SCA color
(Flux ratio, %) x Y temperature Duv
[K]
Light
e 4.;6 0.2966 0.4474 6494 59
(la)
Light
sourc 91.60 : 4.57 : 0.3162 0.4439 5953 50
e 3.84
(lb)
Light
sourc 87.51 : 8.68 : 0 3304 0 4339 5576 41
e 3.81
( lc )
Light
sourc 82.78 : 13.91 : 0 3506 0 4314 5041 33
e 3.31
(ld)
Light
sourc 78.90 : 17.66 : o 3615 0 4174 4722 24
e 3.44
(le)
Table 2 shows the mean value of flux ratio (%) of LAP:
YOX: SCA which causes the subjects to begin to feel that
chromaticity has decreased and the light has become
- 46 -
CA 02249613 1998-09-18
whitish, in terms of flux ratio. The light sources are
denoted as la through le, and chromaticity values x and
y, calcium halophosphate phosphpor and Duv at this time
are shown.
Fig.10 shows chromaticity values x and y of the light
sources 17 (la) through light sources 21 (le) and
regression line22 thereof(y=-0.43x+0.58). Straight line
23 shown in this drawing is a parallel displacement of
the regression line with the digit at the second decimal
place of the y intercept of the line being carried up,
sothat allchromaticityvaluesxandyofthe light sources
(la) through (le) are included. Hatched area24represents
the range of claims 13 and 14.
Fig.ll shows the chromaticity values (x, y) of claims
13 and 14, a: (0.228, 0.351), b: (0.358, 0.551), c: (0.525,
0.440), d: (0.453, 0.440) and e: (0.285, 0.332), for
comparison,
and the relation between the line 23 (y<-0.43x+0.60)
and the color names of light emitted by the light source.
A fluorescent lamp which emits light of less chromaticity
and white impression can be made by setting the condition
of the fluorescent lamp of the invention under the line
of y=-0.43x+0.60.
- Weight proportions of LAP, YOX and SCA phosphors,
chromaticity values x & y, halophosphate phosphpor and
- 47 -
...... .... . ..... .
CA 02249613 1998-09-18
Duv of light sources which correspond to the light sources
(la) through (le) of Table 2 made as prototypes by using
20 fluorescent lamps are shown as light sources lf through
lj in Table 3.
[Table 3] Comparison of blending ratio, chromaticity
values x & y, correlated color temperature and Duv of
various 20W fluorescent lamps when chromaticness
;~;shes and light begins to be perceived as whiteness
Correlated
LAP: YOX: SCA color
(Blending x y Duv
temperature
ratio, %) [K]
Light
e 16 58 0.3004 0.4380 6419 54.5
(lf)
Light
sourc 69 05 : 17.97 : o 3177 0 4451 5911 50.3
(lg)
Light
sourc 61.43 : 27.24 : 0 3320 0 4307 5530 39.6
e 11.33
(lh)
Light
sourc 51;29 : 41-95 0.3568 0-4388 4906 33-9
(li)
Light
sourc 48.70 : 43.29 : o 3656 0 4233 4641 24.9
e 8.01
(lj)
~ Fig.12 through Fig.16 show the spectral
distributions of light sources lf through lj which are
- 48 -
CA 02249613 1998-09-18
the embodiments of the invention by means of 20W
fluorescent lamps.
In these spectral distributions, in comparison to the
embo~iment where the new high-efficiency light source
having the spectral distribution shown in Fig.17 is made
by using the fluorescent lamps, relative spectral power
generated by the phosphor which has the peak emission
wavelength in a wavelength band from 420 to 470nm exists,
and chromaticness can be decreased and whiteness can be
increased in the light color of the new fluorescent lamp
by adding radiation in this wavelength band.
Also it ismade possibleto improvethe luminousbrightness
in scotopic vision, mesopic vision and in wide field of
view, as well as improve the whiteness.
[Table 4] Flux ratios (%) of light sources (i) through
(m) consisting of only LAP and SCA determined from
experiments
Flux ratio of
LAP Flux ratio of SCA
Light source 95.84 4.16
(lb) 95.98 4.02
(lc) 95.83 4.17
(ld) 96.16 3.84
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CA 02249613 1998-09-18
Light source 95.82 4.18
Average 95.92 4.08
Table 4 shows the blending ratio of only the LAP and
SCA of the light sources la through le in terms of flux
ratio, based on the blending ratio in terms of flux ratio
of the three fluorescent lamps which have the three kinds
of single phosphors shown in Table 2.
It is shown that the blending ratio (%) of LAP and
SCA is 96: 4 in almost every light source. The chromaticity
point (0.285, 0.332) of the chromaticity range of the
invention is located farthest toward blue region, and
therefore blending ratio of SCA is maximum at this point.
Flux ratio (%) ofLAP, YOX andSCA atthischromaticity
point is 81: 9: 10 when calculated from the chromaticity
values of the monochromatic fluorescent lamps which have
the three kinds of single phosphors for color blending,
by the equation of additive color blending. The flux ratio
becomes 89: 11 in the case of LAP and SCA.
Thus when light generated by a phosphor as like SCA
having peak emission wavelength in a range from 420 to
470nm and a phosphor as like LAP having peak emission
wavelength in a range from 530 to 580nm are blended in
a flux ratio (%) of B:G where B is from 4 to 11 (%) and
G is from 96 to 89 (%), a fluorescent lamp having whiteness
with less chromaticness in the light can be made.
- 50 -
CA 02249613 1998-09-18
In the range of chromaticity of the invention, the
color point where the flux ratio (%) of YOX becomesmAximllm
is the intersection of the lines y=-0.43x+0.60 and
y=0.15+0.64x. Flux ratio (%) of LAP, YOX and SCA at this
intersection is, when calculated by the equation of
additive color blending, 70: 28: 2. Based on this finding,
a light colour having whiteness with less chromaticness
in the light can be made with obtA; n; ng categorical colour
perception with high efficiency by blending the flux R
emitted by a phosphor which has peak emission wavelength
in a range from 600 to 650nm such as YOX and sum of B+G
of flux emitted by a phosphor which has peak emission
wavelength in a range from 420 to 470nm such as SCA and
flux emitted by a phosphor which has peak emission
wavelength in a range from 530 to 580nm such as LAP in
a ratio of R: B+G where R is set within a range from 0
to 28(%) and B+G within a range from 100 to 72 (%).
Fig.18 shows the chromaticity range 25 of claims 13
and 14 of the invention being defined by the chromaticity
values (x,y) a: (0.228, 0.351), b: (0.358, 0.551), c:
(0.525, 0.440), d: (0.453, 0.440) and e: (0.285, 0.332)
and y<-0.43x+0.60, fluorescent lamp 26 having the single
phosphor of LAP, chromaticity values x & y of the light
source (lk) 27 coated with halophosphate phosphor of
daylight color, chromaticity values x ~ y of the light
CA 02249613 1998-09-18
source (11) 28 coated with halophosphate phosphor of
neutral white color, and chromaticity values x & y of the
light source (lm) 29 coated with halophosphate phosphor
of white color being plotted on the x-y chromaticity
coordinate plane. By blending the light source 26 and one
of the light sources lk 27 through lm 29, and light sources
having chromaticity x, y of dashed lines (1) 30, (2) 31
and (3) 32, it is made possible to realize the light source
having the chromaticity range 25 of the invention.
Table 5 compares the lamp efficiencies of the light
sources lf through lj employing 20W fluorescent lamps,
the new fluorescent lamp having the spectral
characteristic shown in Fig.ll, the conventional white
fluorescent lamp employing halophosphate phosphor and a
three band radiation type daylight fluorescent lamp.
[Table 5] Lamp efficiencies of various light sources
(20W)
Type of lamp (lm/W)
Light source (lf) 106.0
Light source (lg) 101.5
Light source (lh) 97.6
Light source (li) 96.3
Light source (lj) 91.4
New high-efficiency 96.9
light source
CA 02249613 1998-09-18
White fluorescent
lamp (Halophosphate 73.9
phosphor)
White daylight
fluorescent lamp
(Three band 78.7
radiation type)
Lamp efficiencies of the light sources lf through lj
are about 24 to 43% higher than those of the conventional
white fluorescent lamp which uses halophosphate phosphor
and about 10 to 35% higher than that of the conventional
three band radiation type daylight fluorescent lamp.
Now thethirdembodiment ofthe invention willbe described
below.
The third embo~;ment of the invention renders
incandescent color to the light of the new high-efficiency
light source. Specific configuration of the phosphor is
similar to that of the first embodiment.
The embo~iment of the invention is based on
experimental data obtained through subjective evaluation
of light sources whether light color thereof is acceptable
or not as incandescent lamp light color.
In this experiment, two lighting areas each having
~;men~ion of 2~ in terms of the angle of view were
presented at the same time, one as a test stimulus and
the other as a reference stimulus in dark field of view.
The test stimulus was designed to be able to randomly
present 21 kinds of light colors tl through t21. Each test
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,. ~.. ~ .. . ..
CA 02249613 1998-09-18
stimulus was produced by adjusting the ratio of blending
the fluorescent lamp (LAP) characterized by the green
light of [chemical formula 1] LaPO4: Ce,Tb, the
fluorescent lamp (YOX) characterized by the red light of
[chemical formula 2] Y203:Eu, the fluorescent lamp (SCA)
characterized by the blue light of [chemical form-lla 3]
(Sr,Ca,Ba)lO(PO4) 6Cl2 Eu and a fluorescent lamp emitting
pure yellow light havingpeakemission wavelength of580nm
andchromaticity values x, y of (0.515, 0.472). Properties
of the test stimuli are shown in Table 6.
[Table 6] Chromaticity values x, y, correlated color
temperature and Duv of test st;m~ tl through t21 1.
No. x y Tc(R) Duv
tl 0.4860 0.4620 2731 15.6
t2 0.4714 0.4501 2834 12.9
t3 0.4538 0.4339 2964 9.2
t4 0.4077 0.4607 3915 27.5
t5 0.4232 0.4497 3571 20.0
t6 0.4336 0.4352 3295 12.6
t7 0.3756 0.3626 4030 -5.4
t8 0.3927 0.3742 3657 -4.6
t9 0.4143 0.3948 3344 -0.1
tlO 0.4626 0.3665 2310 -16.7
- tll 0.4559 0.3812 2518 -10.8
tl2 0.4438 0.3931 2798 -5.2
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.. ~ . ,, . .. , , . ~ . ..
CA 02249613 1998-09-18
tl4 0.3942 0.4385 4062 22.6
tl4 0.4090 0.4285 3701 15.0
tl5 0.4239 0.4244 3389 10.2
tl6 0.4869 0.4018 2299 -4.4
tl7 0.4810 0.4155 2466 0.5
tl8 0.4666 0.4258 2724 4.9
tl9 0.4062 0.3475 3074 -20.1
t20 0.4127 0.3656 3115 -12.7
t21 0.4230 0.3875 3110 -4.8
As the reference stimulus, an incandescent lamp light
color (correlated color temperature 2800K and
chromaticity values x, y (0.452, 0.406) was presented.
In the experiment, test stimuli were presented
randomly to subjects who were asked to compare the test
stimuli with the reference stimulus and determine whether
the light color of the test stimulus is acceptable as
incandescent lamp light color or not.
Evaluation was repeated three times under the same
condition by seven subjects having normal color vision.
While the light emitting area was shown at two levels of
lllm;n~nce, 3000cd/cm2 and 300cd/cm2, result of the
experiment showed no difference in the evaluation of the
light color between the two levels of lllm;n~ce.
- Fig.20 shows the acceptance rates of the test light
sources as incandescent color with decimal point form
CA 02249613 1998-09-18
every ehromatieity point (x, y) thereof. Curve 23 is the
regression eurve of 50% aeeeptanee rate. That is, the area
within the curve 23 represents the range of light color
aeeepted as ineandeseent eolor by at least half of the
subjeets.
Fig.21 shows the relation between the area defined
by 1 to v range enelosed by line segments eonneeting the
ehromatieity points l: (0.4775, 0.4283), m: (0.4594,
0.3971), n: (0.4214, 0.3887), o: (0.4171, 0.3846), p:
(0.3903, 0.3719), q: (0.3805, 0.3642), r: (0.3656,
0.3905), s: (0.3938, 0.4097), t: (0.4021, 0.4076), u:
(0.4341, 0.4233) and v: (0.4348, 0.4185) of elaim 21 of
the invention and the curve 23.
The area defined by i to v represents the range of
light eolors of the conventional lamp obtained by the JIS
method wherein upper and lower delimiting lines are set
in the vieinity of the Planekian loeus and speeifying the
inside thereof as tolerable range. The chromatieity for
fluoreseent lamps speeified by IEC is ineluded in this
range. Claim 22 of the invention is the range whieh is
left when the area defined by 1 to v is subtraeted from
the inside of the eurve 23.
The straight line 24 shows the ehange in ehromatieity
when the flux ratio of hAP: YOX is ehanged in a fluoreseent
lamp made by using only the LAP phosphor having peak
- 56 -
.
CA 02249613 1998-09-18
emission wavelength in a region from 530 to 580nm and the
YOX phosphor having peak emission wavelength in a region
from 600 to 650nm.
Point 25 represents the chromaticity in the case of
LAP: YOX=70: 30, where the correlated color temperature
is about 3500K and Duv is about 19, while point 26
represents the chromaticity in the case of LAP: YOX=65:
35, where the correlated color temperature is about 3100K
and Duv is about 12, point 27 represents the chromaticity
in the case of LAP: YOX=60: 40, where the correlated color
temperature is about 2800K and Duv is about 6, and point
28 represents the chromaticity in the case of LAP: YOX=55:
45, where the correlated color temperature is about 2600K
and Duv is about 1.
Thus it is shown that, for a fluorescent lamp having
dominant radiation wavelengths in a region from 530-to
580nm and in a region from 600 to 650nm, correlated color
temperature of about 350OK determines the borderline
between incandescent light color and white light color
when correlated color temperature is used as an index.
Fig.22 shows for reference the relation between the
chromaticity of l to v of claim 21 and the range of light
color of fluorescent lamp of JIS.
~ In Fig.22, area29 represents the chromaticity region
of cool white light, area 30 represents the chromaticity
.... , .. . .. ~ . , "
CA 02249613 1998-09-18
region of warm white light and area 31 represents the
chromaticity region of incandescent lamp type color of
fluorescent lamp. From the Fig. 22 it is apparent that
the vertexes other than left-low one of the range of white
chromaticity correspond to the l to v. Spectral
distribution of an embodiment ofthe fluorescent lamp when
the flux ratio LAP: YOX is changed as shown in 25 through
28 of Fig.21 are shown in Fig.23 through Fig.26.
As an embo~;ment of the new high-efficiency light
source of the invention emitting light of incandescent
color, LAP [chemical formula 1] LaPO4: Ce,Tb used as a
phosphor having peak emission wavelength in a region from
540 to 560nm and YOX [chemical formula 2] Y2O3:Eu used as
a phosphor having peak emission wavelength in a region
from 600 to 620nm were combined while changing the flux
ratio from LAP:YOX=60: 40 to LAP:YOX=70: 30.
When the flux ratio is set to LAP:YOX=70: 30,
efficiency can be increased by 10% while decreasing the
kinds of phosphor, compared to the conventional three band
radiation type fluorescent lamp color.
Fig.27 shows the spectral characteristic of another
embodiment of the invention wherein SCA having the
composition of (Sr,Ca,Ba) 10( PO4)6Cl2 Eu is used as a
phosphor having peak emission wavelength in a region from
440 to 460nm, LAP having the composition of LaPO4: Ce,Tb
- 58 -
CA 02249613 1998-09-18
used as a phosphor having peak emission wavelength in a
region from 540 to 560nm and YOX having the composition
of Y2O3:Eu used as the phosphor having peak emission
wavelength in the region from 600 to 620nm were combined
in a flux ratio of 1: 67: 32.
Chromaticity values x & y of the fluorescent lamp are
(0.4315, 0.4334), while the correlated color temperature
is 3317K and Duv is 12.3. This embodiment makes it possible
to generate any desired light color in the chromaticity
range of claim 21 and the claim 22 of the invention, by
adding a sub-emission to wavelength regions other than
the ~om; n~nt radiation wavelengths.
When constituting.the new high-efficiency light
source, similar effect can also be achieved by producing
light color equivalent to that of the fluorescent lamp
of the invention by means of a metal halide lamp, besides
the embo~;ment which employs the fluorescent lamp
described above, thereby providing the following lamps.
The first is a metal halide lamp which has high
luminous brightness in mesopic vision and scotopic vision
or in a wide field of view while ensuring such a level
of color reproduction that allows categorical color
perceptionforsurfacecolorsofat leastred, green,blue,
yellow, white and black.
The second is a metal halide lamp which has whiteness
- 59 -
CA 02249613 1998-09-18
inthe light color withoutcausingthesense ofincongruity
in the light color when used in conjunction with a
conventional high temperature light source, while
ensuring such a level of color reproduction that allows
categorical color perception for surface colors of at
least red, green, blue, yellow, white and black.
The third is a metal halide lamp used as a high-
efficiency illllm;n~ting light source which has light
color equivalent to incandescent color without causing
the sense of incongruity in the light color when used in
conjunction with a conventional low color temperature
light source, while ensuring such a level of color
reproduction that allows categorical color perception for
surface colors of at least red, green, blue, yellow, white
and black.
In the case of metal halide lamp, the invention can
be achieved by adding a metal halide having radiation in
a region from 420 to 530nm and a metal halide having
radiation in a region from 470 to 530nm to a metal halide
having ~omin~nt radiation wavelengths in a region from
530 to 580nm and a region from 600 to 650nm. While ordinary
metal halide lamps employ In (blue radiation), Tl (green
radiation) and Na (yellow, red radiation), the invention
can be achieved by combining these elements while
increasing the In content thereby increasing the
- 60 -
CA 02249613 1998-09-18
intensity of blue radiation.
The invention can also be achieved by combining
[chemical formula 17] NaI AlCl3 or [chemical formula 18]
CaI2-AlCl3 and with thallium halide (for example
thallium ionide).
Another metal halide lamp in common use is based on
Sc-Na-(Th). The invention can also be achieved by
combining this lamp and thallium halide (for e~mple
thallium ionide).
The invention can also be aehieved by combining a phosphor
based on Ce-Na-Cs-(Sm) (for example ionides of these
elements) of which Sm content is deereased thereby to
deerease the blue radiation component and thallium halide
(for example thallium ionide).
As described above, the invention is capable of
aehieving the following improvements for the new
high-effieiency light source.
The first is a light source which has high luminous
brightness in mesopie vision and seotopic vision and in
wide field of view while ensuring such a level of color
reproduction that allows categorical color perception for
surface colors of at least red, green, blue, yellow, white
and black.
- The second is a light source which has whiteness in
the light color without causing the sense of incongruity
- 61 -
CA 02249613 1998-09-18
when used in conjunction with the conventional high
temperature light source, while ensuring such a level of
color reproduction that allows categorical color
perceptionforsurfacecolorsofat leastred, green,blue,
yellow, white and black.
The third is a light source which can be used as high
efficiency illllm;nAting light source and has light color
equivalent to incandescent lamp without causing the sense
of incongruity when used in conjunction with the
conventional low color temperature light source, while
ensuring such a level of color reproduction that allows
categorical color perception for surface colors of at
least red, green, blue, yellow, white and black.
The invention has high practical applicability as an
efficiency-oriented light source used in such places as
emphasis is not placed on the fidelity of color
reproduction. For example, the invention is particularly
promising as an outdoor illuminating light source, and
can be used as outdoor illnm;nAtion, road illllm;nAtion,
streetillumination,vehicle lights,tunnelillllm;nAtion,
public square illumination, warehouse illllm;nAtion,
factory illumination, etc.
Effect of the invention can be m-~;m;zed when the
light source is used with a low illllm;n~nce in places where
emphasis is not placed on the fidelity of color
- 62 -
........ . .......... ....
CA 02249613 1998-09-18
reproduction, thus making it possible to use the light
source in a range of visual environments from scotopic
vision to mesopic vision.
According to the invention, proportions of radiation in
visual radiation wavelength bands 420 to 530nm (more
specifically 420 to 470nm and 470 to 530nm), 530 to 580mn
and 600 to 650nm are controlled in the new high-efficiency
light source.
This configuration makes it possible to provide
further the following effects.
One is to achieve a high-efficiency illllm;n~ting
light source which ensures categorical color perception
for surface colors of at least red, green, blue, yellow
and white, while improving the luminous efficiency in
scotopic vision and mesopic vision or in a wide field of
view.
Another is to achieve an illuminating light source which
has whiteness in the light color, while ensuring such a
level of color reproduction that allows categorical color
perception for surfacecolors of at least red, green, blue,
yellow, white and black.
The third is to achieve a high-efficiency
illllm;n~ting light source which has light color
equivalent to incandescent lamp, while ensuring such a
level of color reproduction that allows categorical color
- 63 -
, ......... , .. ~.~ .. . . .
CA 02249613 1998-09-18
perception forsurfacecolors of at least red, green, blue,
yellow, white and black.
It is said from experience that, even in the
environment of the same illuminance, ordinary
~ minAting light sources cause brighter sensation when
the correlated color temperature is higher. This is
supposedly because radiation from a light source of higher
correlated color temperature includes higher inensity of
blue or blue-green component.
The effects of the invention will now be described
below in comparison with these ordinary ill-l~in~ting
light sources.
Major references of comparison are three band
radiation type fluorescent lamps of incandescent lamp
light color (3000K): EX-L, neutral color(5000K): EX-N and
daylight color( 6700K): EX-D. Also used as references of
comparison are: ordinary white color fluorescent lamp:
FLW which uses halophosphate phosphpor, efficiency-
oriented high-pressure sodium lamp: NH1, low-pressure
sodium lamp: NX, color rendering-improved high-pressure
sodium lamp: NH2, fluorescent mercury lamp: HF and metal
halide lamp: MHL.
In order to ensure that the lamp efficiency is not
lower than 10%, the invention provides 2B+SCA by adding
[chemical formula 3] (Sr,Ca,Ba)10( PO4)6C12: Eu to the new
- 64 -
CA 02249613 1998-09-18
high-efficiency light source: 2B (2L), 2B+halo-W by
adding calcium halophosphate phosphpor (chemical formula
16) Cas(PO4)3(F,Cl):Sb,Mn and 2B+SAE by adding [chemical
formula 11] Sr4All4O25:Eu. Because the new high-efficiency
light source (dual band radiation type fluorescent lamp)
has an efficiency 20% or more higher than the three band
radiation type daylight fluorescent lamp, even the
ordinary flux is superior over the three band radiation
type daylight fluorescent lamp. Apart from this,
subjective reproduction of brightness will be discussed
below.
In the verification of the effect of luminous
brightness in mesopic vision and scopic vision,
V'(~)/V(~) is used as the representative index, and in
the verification of the effect of improving the luminous
brightness in wide field view, V10(~)/V(~) is used
representative index.
Fig.28 shows the relation between the values of
V'(~)/V(~) and various light sources, and Fig.29 shows
the relation between the values of V10(~)/V(~) and
various light sources.
These data show that the effect of adding phosphors
to the new high-efficiency light source in improving the
spectral luminous efficiency is smaller in the case of
light emitted over a wide wavelength band such as calcium
- 65 -
..... ..
CA 02249613 1998-09-18
halophosphate phosphpor used in the ordinary illuminating
light sources, and is greater in the case of phosphors
emitting light in a relatively narrower band. That is,
the phosphor [chemical formula 3] (Sr,Ca,Ba)10(PO4) 6C12: Eu
which radiates in a relatively narrow band with peak
emission wavelength in a band from 420 to 470nm has a
sufficient effect of improvement. The phosphor [chemical
formula 11~ Sr2All4O25:Eu which radiates in a relatively
narrow band with peak emission wavelength in a band from
470 to 530nm has a great effect of improvement.
While the data of Fig.28 and Fig.29 are meaningful
only in the mutual relationship thereof, the effect of
adding radiation in a region from 470 to 530nm to the new
high-efficiency light source in improving the various
luminous efficiencies is greater than the difference
between the brightness felt from EX-L(incandescent lamp
light color of three band radiation type fluorescent lamp)
and the brightness felt from EX-D(day-white color of that
of fluorescent lamp) ,while the illllmin~nce of the
r;n~tion of environment of EX-L and that of EX-D are
set same.
These effects of the invention have wide applications
such as traffic ill--rnin~tion, sreet illumination, safety
light, night light, ill-lmin~tion of automated factory and
public illl-min~tion for unfrequented space, where such
- 66 -
.. ,~
CA 02249613 1998-09-18
features as energy saving and economy are preferred while
the light sources are not required to have a high fidelity
of color reproduction and are used with low design
r;n~nce in scotopic vision and mesopic vision.
Also accordingtothe invention,chromaticness of the
new fluorescent lamp can be decreased and whiteness can
be provided while maint~in;ng the high efficiency, by
enh~ncing the radiation in the wavelength band from 420
to 530nm.
In order to further efficiently decrease the
chromaticness and increase the whiteness, it is
preferable that the radiated light energy be concentrated
in the wavelength band from 420 to 470nm on the shorter
wavelength side.
There may be an opposite case where incandescent
light color of lower correlated color temperature is
desirable from the aesthetic point of view. In such a case,
because the chromaticity range of light which is
acceptable as incandescent color is determined by the
invention, a light source which radiates light in this
chromaticity range can be made.
INDUSTRIAL APPLICABILITY
- AS will be understood from the above description, it
is made possible to provide a variety of light colors
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., ., i " .. ~.......................... . ... . ....
CA 02249613 1998-09-18
having high whiteness with less sense of incongruity, by
using the new high-efficiency light source of the
invention in conjunction with a high color temperature
light source, and provide a variety of light colors
equivalent to incandescent color with less sense of
incongruity by using the new high-efficiency light source
of the invention in conjunction with TS and low color
temperature light source.
- 68 -
