Note: Descriptions are shown in the official language in which they were submitted.
llS2789
i BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an infrared
condensiilg lens (here~after referred ~o also as an infrared rays condensing lens).
2. Brief Description of Prior Art
It is known of infrared rays sensing elements
composed of materials givinglsome electrical response upon
the radiation of infrared rays, such materials being as a
pyroelectric material producing electric charges by the radia-
tion of infrared rays and a photoconductive material changingits electroconductivity by the radiation of infrared rays.
The infrared rays sensing elements have been used in a
combination with infrared ray condensers for a variety of
infrared ray sensors which have been employed as an infrared
ray detecting part in apparatuses such as, for example,
a fire alarm for detecting a fire; an invader detecting
device for detecting the infrared rays radiating from the
human body or other living bodies; a transfer detecting
device for detecting a transferring object such as human
beings, vehicles or the like passing through a passage or the
like on which infrared rays are being radiated; an infrared
ray image pickup unit for producing electrical signals correspond-
ing to optical images of infrared rays; an infrared ray
communication unit for communicating apart with infrared
rays and so on.
As an infrared ray condenser, there has been used
a con~ex lens in a u~ual form or a concave mirror. Where it
is used merely for the detection of infrared rays, the infra-
red condenser is designed in a manner adaptable to receive
infrared rays from their source at an area as wide as possible
i
1152789
and condense them on an infrared rays sensing element, whereby
the sensitivity of the infrared ray sensor is rendered high.
Where it is employed for picking up infrared ray images, the
infrared ray condenser can provide a function to focus an
outside infrared ray image into t~e image on the sensing
surface of its infrared ray sensing element. In either case,
the surface of the condenser receiving infrared rays is
preferably as big as possible within the scope acceptable
from the design of an apparatus or device.
Both the pyroelectric and photoconductive
materials constituting the infrared rays sensing elements
are also highly sensitive to visible rays so that it is
desired to remove noises resulting from the visible rays
with the infrared ray condenser in an infrared ray sensor
particularly where accurate information with respect to the
infrared rays to be sensed is required.
Whexe prior art infrared ray condensers
are composed of convex lenses or spherical lenses, D
materials capable of transmitting a wide range of infrared
rays and interrupting visible rays have heretofore been used, ¦~
such material being as crystalline materials such as silicone,
germanium, sapphire or the like. When such an extremely hard
and neve~theless brittle material is used to gi-~e a convex lens
or a spherical lens, however, many skilled laborious ~70rk
is required to cut the single crystal plate of the crystalline
material into a convex shape and then grind and polish it
elaborately, thereby causing the manufacturing and material
costs to rîse. Accordingly, the use of such crystalline
material for usual infrared ray condensers other than high-
quality ones such as the infrared ray image ~icku~ unit is not
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115~789
very appropriate.
On the other hand, where the infrared ray
condensers have been of a condensing mirror or a convex
mirror, it is required to provide an infrared rays sensing
element at the side of the mirror receiving the infrared
rays so that the shadow of the infrared rays sensing element
falling on the mirror surface becomes the dead angle.
Therefore r where the condensing mirror is used, for example,
the infrared ray image pickup unit presents problems that the image
are broken or get blurred so that it is inappropriate to
apply the condensing mirror to such a unit. And, where the
condensing mirror is applied to an apparatus or device
which is used merely for the detection of infrared rays,
it causes a defect that an amount of the infrared rays to
be sensed is reduced. Furthermore, where the condensing
point of the condensing mirror is adjacent to the surface
of the mirror receiving the infrared rays, it is necessary
to mount the infrared rays sensing element adjacent to the
infrared rays receiving surface so that it causes disadvan-
tages that there are many limits in manufacturing and design-
ing on procedures for mounting the sensing element and wiring.
In order to improve the defects and disad-
vantages presented in the convex lens and the concave mirror
as stated hereinabove, it has now been found that a convex
lens composed of a synthetic resin which is very easy to be
processed to form a desired shape can be used for an infrared
ray condenser in an infrared ray sensor. It has been found,
howeverr that as the transmittance of infrared rays of the
synethetic resin is unexpectedly poor and the synthetic resin
having a little bit greater thickness does not permeate or
transmit most of the effective infrared rays, it is found
difficult to provide a practically applicable infrared ray
condenser with a high condensing efficiency from a convex
lens prepared as from such a synthetic resin.
Thus, wavelengths of predominant infrared
rays radiating from the human body that is the object for
detection by means of an invader detecting device are ~rom 8
to 13 microns and average about lo microns. The wavelength
of the infrared rays from carbon dioxide flame that is the
main object for detection by means of a fire alarm is about
4.3 microns. Currently known synthetic resins, however,
absorb well infrared rays having wavelengths ranging from
several microns to several tens microns. Among those synthe-
tic resins, a polyethylene which is relatively small in
absorbing the infrared rays in the above wavelength range q
can transmit only from 20 to 30 percent of the infrared
rays having the wavelength of 10 microns when the polyethy-
lene lens is 1 mm thick, although the polyethylene lens
having a thickness of 0.1 r~m can transmit from 85 to 90 percent
of the 10 microns infrared rays.
Where a convex lens is prepared from a mate-
rial having a poor transmittance of infrared rays, the size
of the lens having a thin thickness as stated here~nabove
and a desired shape is rendered so larger while keeping its
- 25 similar figures that its thickness is f~rther increased,
whereby the convex lens cannot allow most of the effective
infrared rays at its central portion to transmit therethrough.
Furthermore, the enlargement of the size of the lens while
keeping its similar figures lengthens its focal length
so that, in order to control an increase in the focal
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1152789
length, the enlargement of the curvatuxe of the lens causes
a further increase in the thickness thereof at its center
portion.
For example, when a convex lens for condens-
ing infrared rays, having the focal length of 50 mm, capable
of transmitting 50% or more of the infrared rays having a
wavelength of 10 microns at the maximal thickness portion
thereof is prepared by a polyethylene, the thickness of the
lens should be at largest 600 microns when calculated from
the transmittance of infrared rays of the polyethylene so
that its maximum size is restricted to about 11 mm. Such a
lens is too small in a condensing area and its transmittance
of infrared rays is poor. When such a lens having the focal
length of 300 microns is preparedj its-transmittance of- -
infrared rays is increased to about 70%, but the size ofthe lens is reduced to 7.7 mm so that the condensing area
is half as much as a lens having the thickness of 600 microns.
As stated already hereinabove, infrared
ray condensers for use in an infrared ray sensor is necessarily
designed so as not to transmit visible rays. Since a synthetic
resin such as a polyethylene has a transmittance of visible
rays larger than silicon, germanium or sapphire, this all
the more prevents the synthetic resinous convex lens from
being empLoyed as an infrared ray condenser.
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lS2789
S~MMARY OF THE INVENTION
Therefore, an object of the present invention is to
provide an infrared condensing lens having a large aperture
and a great transmittance of infrared rays, thus a large
amount of transmission of the infrared rays.
; Another object of the present invention is to
provide an infrared condensing lens having a short focal
length in comparison with a large amount of the transmission
of the infrared rays.
A further object of the present invention is to
provide an infrared condensing lens having a small
transmittance o~ visible rays in comparison with a favorable
transmittance of infrared rays.
A still further object of the present invention is
to provide an infrared rays condensing lens which can be
manufactured by means of simple manufacturing steps with a
cheap material.
Accordingly there is provided an infrared condensing
lens comprising a Fresnel convex lens made of a synthetic
resin capable of transmitting infrared rays toward the
thic~ness of said lens and a membrane or film for preventing
the penetration or transmission of visible rays, said membrane
or film disposed on at least one of the surfaces perpendicular
to the thickness direction of said Fresnel convex lens, being
made of an inorganic material capable of substantially
interrupting visible rays and providing a transmittance of at
least a portion of rays in the infrared range.
~arious other objects, advantages and features of
the present invention will become readily apparent from the
- 30 ensuing detailed description, and the novel features will be
paxticularly pointed out in the appended claims.
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52789
BRIEF DESCRIPTION OF THE DRAWINGS
.
FIG. 1 is a schematic representation illustrating
an example of the infrared ray sensors using an infrared
rays condensing lens according to the present invention.
FIG. 2 is a partially notched perspecti~e view
illustrating one embodiment of the structure of the infrared
ray sensor of FIG. 1.
-7a-
1~152~789
FIG. 3 is a cross-sectional
view illustrating the infrared rays condensing lens shown
in FIGS. 1 and 2.
FIG. 4 is a schematic representation illus-
trating another embodiment using the infrared rays condensing
lens according to the present invention.
FIG. 5 is a schematic representation in
' perspective illustrating an example of an infrared ray image pickup
unit to which the infrared rays condensing lens according to
the present invention is adaptable.
FIG. 6 is an exploded perspective view
illustrating infrared rays sensing elements and electrodes
~ in the infrared ray image pickup unit shown in FIG. 5.
s DESCRIPTION OF THE PREFERRED EMBODIMENTS
,. ..
The infrared ray sensorsas shown in FI~S. 1
to 3 will be described in detail hereinafter.
Referring to FIG. 1 showing the schematic
representation illustrating the infrared ray sensor, an infra-
s red rays sensing element 10 is composed of a pyroelectric
membrane 12 obtainable from a pyroelectric polymer such as,
for example, a fluorine compound, e.g., polyvinylidene fluo-
ride, polyvinyl fluoride, a vinylidene fluoride-trifluoroethy-
lene copolymer or the like, a pyroelectric inorganic material
such as, for example, a titan compound, e.g., lead titanate,
barium titanate, lead titanzirconate or the like or other
pyroelectric materials.
The pyroelectric membrane 12 is provided at
its both sides with electrodes 14a and 14b. The electrode 14b
? at the side receiving the infrared rays may be composed of
a thin layer prepared from a material capable of absorbing
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1:1527~39
infrared rays well, such as gold black or the like. The
electrode 14a at the side opposite to the side receiving
infrared rays may be composed of a material reflectingthe
infrared rays such as aluminum or the like. Both of the
electrodes 14a and 14b are preferably designed so as to
allow their surfaces to introduce the infrared rays in an
effective manner to the pyroelectric membrane 12. As long
as the purpose is fulfilled, any variation and modification
may be made in a manner, for example, such that the electrode
14b at the side receiving the infrared rays may be a t~ans-
parent electrode, while the electrode 14a at the side opposite
to the infrared rays receiving side is composed of an infra-
red rays absorbing material as stated hereinabove or such
that the electrode 14b may be a transparent electrode, while
a pigment capable of absorbing infrared rays may be mixed in
pyroelectric membrane 1~ or coated thereon.
The electrodes 14a and 14b may be substan-
tially the same in shape and form as the pyroelectric membrane
12 where the infrared ray sensor is employed merely for the
purpose of detecting a fire or detecting an invader. However,
where the infrared ray sensor is employed for the infrared
ray image pickup unit or for detecting the position of a fire for
an automatic fire-extinguishing unit, at least one of the elec-
trodes may be preferably a structure comprised of
a plurality of divided strips or pieces. Accordingly, the shape,
size and number of the electrodes may vary in an appropriate
manner accordlng to the purpose of use, design and the like
of the infrared ray sensors. When the electrodesl4a and/or
14b are divided into plural strips or pieces, impedance
converting circuits 16 and detecting circuits 18 may be
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1152789
provided according to the number of the divided electrodes.
; One of the electrode 14a of the infrared
~, rays sensing element 10 is grounded and the other of the
, electrode 14b is connected to the impedance converting
circuit 16 comprised of a field effect transistor (FET).
The output side of the impedance converting circuit 16 is
in turn connected to the detecting circuit 18 for detecting
electric signals (electric current or voltage) from which
a desired output can be obtained. The structure as stated
hereinabove is generally known so that a detailed descrip-
, tion thereon is omitted herein.
, The condensing of infrared rays on the
infrared rays sensing element 10 may be conducted by means
of the infrared rays condensing lens 20 according to the
~,~ 15 present invention which is disposed in front of the infrared
" rays sensing element. Turning now to FIG. 2, there is shown
an embodiment illustrating the structure of an infrared ray
sensor 24 in which the infrared rays sensing element 10
and the infrared rays condensing lens 20 are assembled in
, 20 a cylindrical housing 22.
s As shown in FIG. 2, the infrared rays
' condensing lens 20 is provided at the front open side of
the cylindrical case 22. At the middle portion of the cylin-
drical housing 22 is provided with a printed circuit board 26
; 25 in an arrangement substantially parallel to the lens 20.
At the front side of the printed circuit board 26 facing the
,, lens 20, there is attached the infrared rays sensing element
, 10, and at the rear or back side thereof opposite to the
above front side, there are attached electrical parts 28
,,.
, 30 constituting necessary circuits. A signal line or code 30
,.,
-- 10 --
1~5*789
is drawn to the outside from the rear or back end portion of
the cylindrical housing 22 opposite to the front end portion where
the lens 20 is mounted. The signal line or code is connected
at the other end to a signal presenting unit 32 for indicating
signals to the outside such as an alarm, a display device or
a voice producing device or a computer or the like.
Referring to FIG. 3, there is shown a detail
of the infrared rays condensing lens according to the present
invention. The lens 20 is composed of a Fresnel convex lens
~, 10 34 and a membrane or film 36 for preventing the penetration or
transmission o~ visible rays, said membrane or film being pro-
vided on the flat surface of the lens 34. The lens 34 may ~e
comprised of a synthetic resin having a favorable transmittance
of infrared rays inciuding a thermoplastic resin such as, for
example, olefinic resins, e.g., polyethylene, polypropylene
or ethylene-propylene copolymer; fluorine-containing resins,
e.g., polyvinyl fluoride, polyvinylidene fluoride or polytetra-
fluoroethylene; or an acetylenic resin, e.g., polyacetylene.
The membrane or film 36 for preventing the penetration of visible
rays may be comprised of an inorganic material capable of
substantially interrupting the visible rays and penetrating
or transmitting at least a portion of rays in the infrared
range, said inorganic material being, for example, germanium,
silicon, an indium compound, e.g., indium antimonide, indium
phosphide or indium arsenide or a gallium compound, e.g.,
gallium antimonide or gallium arsenide. The inorganic material
may be allowed to adhere to the flat surface of the lens 34
indirectly or directly ~y spattering, vacuum deposition or
other appropriate techniques. The membrane or film 36 is not
necessarily provided on the flat surface of the lens and may
: ` ~
~s~9 ~
be disposed on a surface opposite to the flat surace thereof
or on both of the surfaces thereof.
Generally, a Fresnel lens can ~e greatly
reduced in weight by dividing the continuous lens surface
into a succession of concentric rings having a cross section
as indicated in FIG. 3, the rings being assembled in correct
relationship on the flat surface thereof. The surface of
the ring is not necessarily a surface (for example, a
portion of a sphere) whose cross section in the radial direc-
~0 tion has a curved line like the continuous lens surface.
The ring surface may be in a form of the circumferential
surface of a truncated cone. In other words, it may be
a surface whose cross section has a straight line (or a
tangent line) represented by differentiating the above curved
line. Accordingly~ the ring may be a small prism in the form
of a ring having the surface as described hereinabove. The
Fresnel convex lens is a Fresnel lens of the type having the
continuous lens surface which corresponds to a surface of a
convex lens.
As a Fresnel convex lens is designed by
removing portions as much as possible where the rays are penet-
rating or transmitting straight through, as compared with
usual convex lenses or spherical lenses, it may be rendered
considerably thinner than usual convex lenses having the
identical focal length and a ratio of the central portion
to the circumferential porion thereof in thickness may be
rendered small. Accordingly, for example, where a Fresnel
convex lens having a lens diameter of several tens mm is
prepared by, for example, a polyethylene, the thickness of
the Fresnel convex lens may be to the extent of several tens
- ~2 -
1152783
~,
microns to several hundreds microns and the Fresnel lens can
provide a good transmittance of infrared rays and allow a
small difference in the infrared ray transmittance between
the central portion and the circumferential portion thereof.
Referring to FIG. 3, the thickness of the
, Fresnel convex lens 34 may be determined according to the
thickness of a flat plate or a base plate excluding nearly
triangular cross-sectional portions 34a, the lens size, the
focal length, the number of the concentric rings or the like.
If the number of the concentric rings would be increased,
it is theoretically possible to provide a Fresnel convex lens
having any thin triangular cross-sectional portions 34a.
However, if the number of the concentric rings would be too
many, there may be a case where the annular concentric grooves 34c
between each adjacent rings formed on the surface thereof may
act as a lattice. Accordingly, as it is difficult to assemble
too many concentric rings on the lens surface in order to make
the triangular cross-sectional portions 34a extremely
thin, the thickness of the Fresnel convex lens may range gene-
rally ~bout 10 microns or more, preferably from about 10 microns
to 1,000 microns, and more preferably from about 50 microns to
500 microns. A Fresnel lens composed of a synthetic resin
having a thickness thicker than 1,000 microns is not practical
because of poor transmittance resulting from the absorption
of infrare~ rays by the synthetic resin used. For example,
where a polyethylene which is said to be least in the absorp-
tion of infrared rays, it can transmit or penetrate only 20 to
30% of the infrared rays when its thickness is 1,000 microns,
although it can penetrate ~5 to 90~ of the rays when its thick-
ness is 100 microns. Although the infrared ray absorption
~ 13 -
115Z7~39
of Fresnel convex lenses 34 may vary greatly with the type
and kind of synthetic resins to be used as a material therefor,
it is preferred that the Fresnel convex lenses have 30% or
more, preferably 50~ or more, of the transmittance of infrared
rays having a wavelength of at least one of 4.3 microns and
lO microns.
The Fresnel convex lens 34 may be designed
so as to have, for example, a focal length of 40 mm, a diameter
of about 50 mm, a pitch width (a distance between the grooves
34c) of about 0.2 mm (200 microns) and a thickness of about
0.4 mm (400 microns). In this case, the number of the concen-
tric rings may be about 250. The thickness of the lens~may
be such that the thickness of the flat portion or base portion
34b is about 0.2 mm,and the both thickest or outermost triangular cross-
sectional portions 34a may be about 0.2 m~ (200 microns) thick.
The membrane or film 36 for preventing the
penetration or transmission of visible rays may be preferably
0.02 micron or thicker, although a membrane or film having
i a thlckness of 0.01 micron may be optionally used because it
can interrupt a considerable amount of visible rays. The upper
limit on the thickness of the membrane or film 36 is not
particularly necessary; however, the thicker the membrane or
film is, the more the differential thickness due to irregularity
in thicknesses may also be. Accordingly, the reflective
index of the infrared rays in the membrane or film 36 composed
of germanium, silicon or the like is so irregular that the
condensing performance or effect of the lens is impaired.
It is accordingly disadvantageous to thicken the membrane or
film 36 to an unnecessary level and its thickness may be
s
` - 14 -
`~
~1527~1g
~,
preferably about 1 micron or thinner.
For example, another membrane or film for the
prevention of reflection may be provided on the membrane or
film 36 for preventing the penetration of visible rays.
S The reflection preventing membrane or film may be composed
of, for example, silicon monoxide, cerium dioxide, zinc
sulfide or the like and disposed on the surface of the mem-
brane or film 36 for preventing the penetration of the
visible rays by means of vacuum de~osition or other suitable J
techniques. As the reflection preventing membrane or film
is required to be provided at the incidence side of the Fresnel g
convex lens 34, it is at the side of the flat surface of the
lens when the rays are falling upon the flat surface thereof
and vice versa. Accordingly, where the membrane or film 36
is at a side opposite to the incidence side of the Fresnel
convex lens 34, the membrane or film for the prevention of
reflection is provided at the side opposite to the membrane
or film 36. As shown in FIG. 3, however, the reflection
preventing membrane or film may be provided on the surface
of the membrane or film 36 for preventing the penetration
or transmission of visible'rays, whereby both of the membranes
or films having uniform thicknesses may be easily formed.
The thickness of the reflection preventing
membrane or film may be, in the visible range, as conventionally
, 25 presented, as follows:
, d =
~ '
, ! - 15 - ~
j;.
,
~152'789
were: d = thickness~
A = wavelength of infrared rays
whose incidence should be
prevented, and
n = reflective index,
The thickness of the reflection preventing film or membrane
may be~ for example, about 0,1 micron.
In the infrared ray sensors as shown in
FIGS. ~ to 3, infrared rays 40 is radiated from the side of
the visible rays preventing membrane or film 36 on the
infrared rays condensing lens 20. The infrared rays 40 is
condensed by means of the Fresnel convex lens 34 after
the penetration or transmission of the membrane or film 36
and then introduced into the pyroelectric membrane 12 of
the infrared rays sensing element 10. The infrared rays
which fell upon the sensing element 10 cause the production
of electric charges due to polarization and produce a
potential between the electrodes 14a and 14b on the sensing
element 10~ This potentia,l or electric signals are fed through
the impedance converting circuit 16 to the detecting unit 18
from which the detecting signals are dispatched. The detecting
signals are then fed to the signal presenting unit 32, thereby
giving a desired presentation or producing a necessary represen-
', ~ tation.
, 25 In place of the pyroelectric light sensing
element as employed in the infrared ray sensors shown in
FIGS. 1 to 3, inclusive, an infrared photoconductive material
comprising an infrared semiconductor such as an infrared
photo diode, an infrared photo transistor, an infrared photo
- 16 -
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llS2789
thyr1stor or the like may be employed as an infrared rays
sensing element.
FIG. 4 illustrates an example of an infrared
ray sensor that uses as an infrared rays sensing element an
infrared photoconductive material such as, for example, lead
sulfide (PbS), indium antimonide (InSb), cadmium sulfide (CdS)
or the like. In FIG. 4, the parts in common with the infrared
sensors presented in FIGS. 1 to 3 are indicated by the same
numerals. Accordingly, a description thereon is omitted
from the description which follows.
In the infrared ray sensor i~lustrated in
FIG. 4, too, the same infrared rays condensing lens 20 as
used in the infrared ray sensors illustrated in FIGS. 1 to
3 is employed. A pair of the electrodes 14a and 14b are
provided at the both sides thereof and connected in series
to a bias power source 52 and an ampere méter 54 and, when
necessary, to the signal presenting unit 32. In this case,
where the infrared ray sensor is used merely for the detec-
tion of a ~ire or for the detection of an invader, the elec-
trodes 14a and 14b may be in each case a solid electrode which maybe composed of one piece and which may have a margin portion for
the protection of a short circuit at the peripheral pcrtion
thereof when needed.
Accordin~ly, when infrared rays 40 are
radiated upon the infrared ~hotoconductive material 50,
the electric current flowin~ through the ampere meter 54
¦ ~s increased so that the rneasurement of the current can
detect the amount of the infrared rays.
- 17 -
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! In FIGS. 5 and 6 there is shown an example
of the infrared ray image pickup unit in which the same infrared d
rays condensing lens as used in the infrared ray sensors
illustrated in FIGS. 1 to 3 is mounted at the front side of
an infrared rays sensing element 60, although an i
llustration
thereon is omitted in the drawings for brevity. In this
example, the parts in common with the infrared ray sensor
illustrated in FIG. 4 are indicated by the same numericals,
and a description thereon is omitted for avoiding duplicate d
explanation.
As shown in FIGS~ 5 and 6, there are provided d
at either of the both sides of the sensing element 60 a
number of strip electrodes 62a, 62b, ..., and 62n which are
arranged in a relationship parallel to each other and also
at the other side thereof a number of strip electrodes 64a,
64b, ..., and 64n which are in turn arranged parallel to
each other. In FIGS, 5 and 6, the strip electrodes 62a, ~i
62b, ..., and 62n are arranged in a relationship substantially
orthogonally intersecting the other group of the strip elec-
trodes 64a, 64b, ... , and 64n. However, this orthogonally
intersecting arrangement between the two groups of the strip
electrodes is not required and one of the groups of the .
strip electrodes may be arranged in an intersecting relation-
ship with the other group of the strip electrodes obliguely at an
appropriate angle to each other.
The strip electrodes 62a, 62b, ..., and 62n
are commonly connected to each other through ON-OFF switches
66a, 66b, ..., and 66n, respectively. Similarly, the strip
electrodes 64a, 64b, ..., and 64n are commonly connected to
each other through ON-OFF switches 66a, 66b, .. , and 66n, ~-
. ,;
- 18- 1
!
,. . . ...
1152 7~39
- i
ii
respectively. One of the common connections is connected
in series through the bias power source 52 and the ampere
meter 54 to the other common connection and, when necessary,
to the signal presenting unit 32.
Thus, when the ON-OFF switches 66a, 66b,
and 66n are turned on and off in turn at . constant time
intervals and the other group of the ON-OFF switches 68a,
68b, ..., 68n is turned on and off in turn at intervals
of a period of time for which the ON-OFF switches 66a,
10 66b, , and 66n aré being turned on and off in turn in
the whole round, image PiCkUp signals corresponding to the shape,
distribution and the like of an infrared ray image in front
of the infrared condensing lens are produced.
Accordingly, with a picture receiving device or unit as
the signal presenting unit, the respective infrared ray F
image can be reproduced.
Either of the groups of the strip electrodes
may be replaced by a printed electrode as in the case of
FIG. 4. In this case, there may be provided a slit plate t
20 having a slit extendingin directions perpendicularly or
obliquely intersecting the lengthwise directions of the
. rest of the strip electrodes. As the slit plate is moved .
or transferred in a straight direction at a ~,~
; constant speed, an infrared ray i.mage can be produced in such
a mode as in FIGS. 5 and 6.
Where an optical chopper capable of intro-
ducing infrared rays intermittantly into the infrared rays
sensing element is disposed in front of the sensing element
~,
- 19 -
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:IL1527B9
`
as in the example illustrated in F~GS. 5 and 6 as well as
in the examples illustrated in FIGS. 1 to 4, intermittant
infrared ray detecting signals can be produced.
While the present invention is illustrated
1 5 with specific embodiments, it will be recognized by those
-¦ skilled in the art that any variation thereon and modifica-
tion therefrom may be made therein without departing from
the scope of the present inventive concepts of the present
invention as defined by the following claims.
' '~
~1,
,
.-
~ .
- 20 - :1
