Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a method and
apparatus of savin~ energy in operating radiant devices.
More particularly the invention relates to a method
and apparatus of saving energy in operating such radiant
devices wherein the radiation is produced by heating a
solid body and/or by gas discharge by means of a voltage
source supplying a sinusoidal A.C. voltage or a substan-
tially uniformly pulsating D.C. voltage.
The invention is primarily but not exclusively
intended for power-saving in the lighting field.
Lighting of different forms accounts for an important
part of the total consumptio,n of electric power. Accordingly
it is of great interest to be able to reduce the power
consumption in the lighting field. One example of such
power saving is e.g. the use of fluorescent tubes instead
of common bulbs,because the tubes are less energy-consuming.
However, due to certain properties of the fluorescent tube,
this is less attractive in many connections; Moreover, i.t
is known that e.g. a 125 V bulb provides a higher light
yield at the same power consumption than a corresponding
220 V bulb. In order to take advantage of this the normal
line voltage of 220 V can be stepped down to 127 V so that
127 V bulbs can be u~ed in connection with the 220 V mains
but this involves relatively high initial expenses in
relation to the power saving achieved as well as power
losses in the transformer.
It is a primary object of this invention to provide
a new and improved method of operating radiant devices
which provides an increase of the radiation yield of the
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radiant device, the power consumption thus being
reduced.
It is a further object of this invention to provide
a new and improved method of considerably saving energy
in operating radiant devices, which can easily be used
when connecting any radiant device for example to the common
mains.
It is a still further object of the invention to
provide a new and improved method of the kind referred to
~hich can be worked by using inexpensive and simple appar-
atus.
Further object of the invention is to provide an ..
apparatus for work~ng the method, which can be constructed
of standard components and is well suited to be integrated
wi.th lighting devices of conventional constructions and
types.
Additional objects and advantages.of the invention
in part will be set forth in the description which follows
and in part be obvious from the description, or may be
learned by practice of the invention. The objects and
advantages of the invention may be realized and attained
by means of the instrumentalities and combinations parti-
cularly pointed out in the appended claims.
. To achieve the foregoing objects and in accordance
with.the purpose of the invention, as embodied and broadly
described herein,;.the invention provides a novel method
of saving energy in operating radiant devices and particu-
larly radiant devices producing a visible light for lighting
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purposes, such as bulbs, fluorescent tubes etc of the kind
referred to initially, which is characterized in that in order
to increase the radiation yield and thus decrease the power
consumption a predetermined constant portion of each half
period of said A.C. voltage or each period of said D.C. voltage,
respectively, is cut away and that the discontinuous voltage
thus obtained is supplied to a radiant device the rated voltage
of which is of the same order as the true effective value of
the discontinuous operating voltage, e.g. the rated voltage
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The top value of the discontinuous operating voltage
then will be larger than the top value of a continuous voltage ~ -
of the same effective value. When the (lower) discontinuous
operating voltage obtained is supplied e.g. to a bulb having
a rated voltage of the same order as the effective value of
the operating voltage the bulb will emit, during the short
time when it is under the relatively high top voltage, a
larger light flow than the maximum light flow supplied thereby
in "normal" operation at the rated voltage. It has surprisingly
been found that the human eye due to the inertia thereof to a
considerably greater extent than can be indicated by means of
a conventional luxmeter perceives the "discontinuous" light
not only as continuous but also as substantially more intense
than the light obtained at normal operation. Thus, it will be
possible to obtain in this way the same intensity of illumi-
nation at a considerably red~ced power consumption which
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338
will be illustrated in more detail below.
The cut-away or blackout of a portion of each half
period of the A.C. voltage or each period of the uniformly
pulsating D .C. voltage can be performed by means of an appara-
tus which is characterized in that it comprises conducting
means connecting the radiant device to said voltage source
and an electronic clipping circuit in said conducting means,
which is arranged to cut away a predetermined and constant
portion of each ~alf period of the A.C. voltage or each period
of the D.C. voltage, respectively t from said voltage source
and to supply continuously, as operating voltage, the dis-
continuous voltage thus obtained to the radiant device the
rated voltage of which is of the same order as the true
effective value of the discontinuous operating voltage, the
radiation yield being increased hereby.
Several clipping circuits can be connected individually
one to each radiation source or one clipping circuit can serve
several radiation ~ources. Such clipping circuits are known
per se and can be based for example on thyratrons or preferably
siliccn controlled rectifiers. For cutting away the leading
portion of each half period of an A.C. voltage there is
preferably used e.g. a circuit comprising a so-called "triac"
(a semi-conductor component which principally consists of two
oppositely directed silicon controlled rectifiers~ or silicon
controlled rectifiers arranged in an analogue manner, or
thyratrons. Other components/circuits having an analogue
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function can of course also be used for cutting the pulsating
voltage. Considering the very small size of particularly such
a semi-conductor circuit it can easily be arranged for example
in lighting devices preferably in a lamp holder or the like.
However, as will be understood the clipping circuit can be
connected at any place between the voltage and radiation
sources. A semi-conductor circuit having the function described ~ ;
above can be produced at very low costs.
How large a portion of each voltage wave to be cut
away or blacked out is determined with due consideration of
the actual voltage source, and the actual radiation source
(i.e. the desired effective value), the desired top voltage
etc. Principally, the voltage can be blacked out during any
part of the oscillating process but it is preferred to cut
away the leading or lagging portion of each half period of an
A.C. voltage (alternatively period in case of a pulsating D.C.
voltage). For illustration it can be mentioned that there is
obtained by cutting away slightly more than one half of each
half period of a 50 c.p.s. sinusoidal A.C. voltage of 220 V
in this manner, an effective voltage of about 125 V and a top
voltage of about 300 V during about 0.2 ms. of each half period.
As indicated above, the invention can be used also
for other radiant devices than bulbs, and thus a corresponding
power saving can be obtained in connection with e.g. radiant
sources producing I.R. radiation, sodium lamps, mercury lamps,
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fluorescent tubes, haloyen lamps, and the like.
The accompanying drawings, which are incorporated in
and constitute a part of this specification, illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention.
Of the drawings:
FIG. 1 is a basic diagram of a powersaving apparatus
according to the invention;
FIGS. 2a and 2b illustrate an A.C. voltage portions of
which have been cut away according to the invention;
FIGS. 3 and 4 illustrate two alternative connections
of the apparatus according to the invention;
FIG. 5 is an example of a silicon controlled recti-fier
circuit for cutting away the leading portion of a
sinus half wave; and
FIG. 6 is an example of a silicon controlled rectifier
circuit for cutting away the lagging portion of a sinus
haLf wave.
Reference will now be made in detail to the present
2a preferred embodiments of the invention, examples of which
are illustrated in the accompanying drawings.
FIG. 1 illustrates the principle of a device accor~iny
to the invention. A voltage source 3, for example the ma:ins of
220 V A.C., is connected through a clipping circuit 2 -to a
radiant source 1 such as a 125 V bulb by conduits 4. The
clipping circuit 2 is arranged such that it cuts away a
suitable portion for example one half or more oE each ha-l r-
6.
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:
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wave of the applied sinusoidal A.C. voltage as is shown in
Figure 2a (a portion of the leading half-wave is cut away)
and 2b (a portion of the lagging half-wave is cut away3.
In Figures 3 and 4 there are shown two alternative
possibilities of connecting the clipping circuit. Thus, in
Figure 3 the voltage source 3 is connected over a central
clipping circuit 2 to several radiant sources 1 (e.g. bulbs)
by the conduits 4 while in Figure 4 the voltage source 3 is
connected to the radiant sources 1 over several clipping
circuits 2, one for each radiant source 1.
In Figure 5 there is shown an example of a connection
o~ a silicon controlled rectifier circuit for obtaining a
discontinuous A.C. voltage according to Figure 2a. The anode
of a triac 5 is connected to one pole 3a of the A.C. voltage
source 3 by a conduit 4a. The other pole 3b of the voltage
source is connected by a conduit 4b to the radiant source 1
which is connected by a conduit 4c to the cathode input of
said triac 5. The gate input of the triac 5 is connected by
a diac 6 to the connection between a resistor 8 and a condensor
11 ~hich are connected in series between the condui~s 4a and
4c. A second circuit comprising a resistor 7 and a condensor
10 connected in series, is connected in parallel with the
circuit 8, 10. A resistor 9 is connected between the circuits
7, 10 and 8, 11, the connection to each circuit being made
between the resistor and condensor therein.
In Figure 6 there is disclosed an example of a possible
connection of a silicon controlled rectifier circuit for
obtaining a discontinuous A.C. ~oltage according to Figure 2b.
In the circuit disclosed in Figure 6 the triac 5 of Figure S is
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replaced by a silicon controlled rectifier 5'. Furthermore,
the circuit is supplemented with a rectifier bridge 15 for
full wave rectifying and a transistor circuit. The rectifier
bridge 15 comprising four diodes is connected between the
voltage source 3 and the rest of the circuit such that the
conduit 4a is connected to the negative pole of the rectifier
bridge 15 and the conduit 4c is connected over a resistor 12
to the positive pole of the rectifier bridge 15. A transistor
17 is connected with the emitter thereof to the cathode of
the silicon controlled rectifier 5' and with the base thereof
over a resistor 13 and a diode 16 to the anode of the silicon
controlled rectifier 5' a resistor 14 moreover being connected
between the emitter and base of the transistor 17. The radiant
source 1 is connected between the collector of the transistor
17 and the positive pole of the rectifier bridge 15.
At a test which illustrates the considerable power
saving that can be obtained by the method and the apparatus,
respectively, according to the invention the power consumption
and the lighting intensity were first measured for a number
Of bulbs having different rated powers at 220 V sinusoidal
voltage (50 c.p.s.) of the mains. Then, a silicon controlled
rectifier circuit (a so-called "dimer") according to Figure 5
was connected between the voltage souxce and a number of bulbs
the same measurements then being made. For the silicon con-
trolled rectifier circuit or "dimer" the following values
applied for the different components:
~0
-- 8 --
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Triac 5: Type 40669; 400 V, 8 A, gate 1.25 V,
15mA
Diac 6: Type 40512
Condensors 10 and 11: 0.1 ~F
Resistor 7: 100 k
Resistor 9: 120 k ~
The resistor 8 was constructed as a combination of
two separate resistors connected in series one re istor being
fixed (4.7 kJL) and one being adjustable (470 k~L). The
adjustable resistor was set to provide an effective value of
125 V (corresponding to a blackout of the voltage pulse over
slightly more than one half of each half period and a top
voltage of about 300 V). The power was measured by means of
a wattmeter and the light intensity was measured by mean$ of
a luxmeter. The distance from bulb to luxmeter was 220 mm.
The test results are shown in the table below.
Conventional operation with continuous voltage
Bulb Effective Current Resistance Light Power
voltage (mA) (Kohm) intensity (W)
(V sinus) (Lux)
220-230 V
15W ball
frosted 220 63 3.492 410 14
230-240V
25 W frosted 220 100 2.200 490 22
220-230V
40W frosted 220 173 1.271 850 38
220-230V
60W frosted 220 264 0.833 1400 58
230-240V
75W clear 220 309 0.712 2000 68
220-230V
lOOW frosted 220 427 0.515 3200 94
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Operation according to the invention with discontinuous
voltage. ` ` `
Bulb Effective Current Resistance Light Power
voltage (mA) (Kohm) intensity (W)
~V sinus) (Lux)
140V
25W frosted 125 176 0.710 520 22
125-130V
40W frosted 125 320 0.390 1550 40
125-130V
75W clear 125 576 0.217 3450 72
From the table it can be seen for example that with a
40 W 125-130 ~ bulb operated at 125 V according to the invention
there is obtained a higher light intensity than with a 60 W
220-230 V bulb connected directly to the line voltage. By
arranging the lighting according to the invention, i.e. for
example by replacing 220-230 V bulbs by 125-130 V bulbs with
a lower rated power and by connecting a clipping circuit having
the function described above between the bulb(s) and the mains
or other voltage source there can be obtained an unchanged
light intensity at a considerably reduced power consumption.
To the value~ of the light intensity obtained by means
of the luxmeter there has been added 15% for an indication
error. An indication error of this order is obtained with a
luxmeter when a discontinuous voltage i8 supplied to the bulb
in accordance with the invention. This indication error was
found in the following manner.
A test person was allowed to watch through an opening
in a screen a white cardboard panel angled at 90 and arranged
with the angle tip towards the watcher such that each half of
the cardboard panel formed an angle of 45 to the viewing
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direction. The light from a 220 V bulb connected to 220 V
sinusoidal A.C. voltage, 50 c.p.s. of the mains was directed
towards one half of the cardboard panel at an angle of 45
while the light from a 125 V bulb in a corresponding manner
was projected towards the other half of the panel. An adjustable
clipping cixcuit of the silicon controlled rectifier type as
described above was connec~ed to the 125 V lamp and by means
thereof the test person adjusted the voltage supplied to the
125 V bulb such that the same light intensity was perceived
from the two halves of the cardboard panel. The adjusted
~oltage was recorded after each adjustment by means of a
digital voltmeter indicating the true effective value of a
discontinuous A.C. voltage. Ten test persons made totally
150 adjustments in the manner described above, the average
voltage value obtained being 117.3 V. Then, the light intensity
of the 125 V bulb was measured at this effective voltage by
means of a luxmeter at a distance of 300 mm and was found to be
1100 lux. ~he corresponding value for the 220 V bulb connected
to the mains was found to be 1300 lux. Thus, the luxmeter
showed a value about 18% lower than the light intensity per-
ceived by the human eye.
When determining the temperature of the incandescent
filament by means of a pyrometer it has been found that the
temperature of a 125 V bulb i8 about 20% higher when the bulb
is connected to 125 V sinus and non-sinus A.C. voltage compared
with a 220 V bulb having the same rated power and connected
to the mains. As mentioned already above, the
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method according to the invention therefore could be
used for the same power saving purpose also with other
types of radiant sources such as sources producing I . R.
radiation as well as sodium lamps, mercury lamps, fluor-
S escent tubes, halogen lamps, etc.
The invent~on is not, of co~rse, limited to the
specific em~odiments described above and shown in the
drawings. ~lany var~ations and modifications are possible
within the scope of the generic inventive concept. It should
be stressed specifically that the invention is not, of course,
limited to the voltage and frequency ranges specifically
stated.
12.
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