JPH0466492B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power source device for a light source that supplies driving direct current with constant current characteristics to a projection lamp of a movie projector.

[Conventional technology]

Traditionally, large movie projectors used in movie theaters and the like use discharge lamps such as xenon lamps that are activated at high pressure as projection lamps. People are starting to do this.

Furthermore, the frame advance of the film is performed at 24 frames/second.

Further, the shutter is formed in the shape of a propeller, for example, and normally opens and closes repeatedly in one frame period in synchronization with the frame feeding, and at this time, the change from completely open to completely closed and vice versa This is done through a relatively long transient period as shown in Figure a.

A conventional light source power supply device that supplies a direct current drive current to a projection lamp consisting of a discharge lamp is constructed approximately as shown in FIG.
is a commercial power supply terminal, 2 is an input side rectifier that rectifies the commercial alternating current from the power supply terminal 1, 3 is an input side smoothing capacitor that smoothes the rectified output of the rectifier 2, 4 is four NPN type switching transistors 5, 6, 7,8
This is a high-frequency switching circuit formed by bridge-connecting the 2-channel circuits, and converts the direct current formed by the smoothing of the capacitor 3 into high-frequency alternating current.

Reference numeral 9 denotes an output transformer through which the high frequency alternating current of the switching circuit 4 is input to the primary winding 9a, and an intermediate tap 10 is provided on the secondary winding 9b. 11
is an output side rectifier consisting of two diodes 12 and 13 for full-wave rectification, and rectifies the output AC of the secondary winding 9b. Reference numerals 14 and 15 indicate a smoothing reactor for smoothing the rectified output of the rectifier 11, an output side smoothing capacitor, and 16 a projection lamp provided in the projector 17, which is composed of a xenon lamp and is formed by smoothing the reactor 13 and the capacitor 14. DC drive current is supplied.

Reference numeral 18 denotes a current detector which detects the driving direct current flowing to the intermediate tap 10 via the lamp 16 and outputs a voltage signal proportional to the driving current as a detection signal. A variable DC power supply 19 outputs a set voltage signal as a drive DC control reference signal.

An error amplifier 20 calculates the difference between the detection signal of the detector 18 and the control reference signal using the control reference signal from the power supply 19 as a reference, and outputs a drive control signal that changes in proportion to the error. Reference numeral 21 denotes a drive control circuit to which a drive control signal for the amplifier 20 is input, and variably controls the switching frequencies of the transistors 5 to 8 from the reference frequency so that the difference becomes zero.

Then, when a lighting switch (not shown) is turned on, the commercial alternating current at the power supply terminal 1 is input to the rectifier 2, and the commercial alternating current is converted to direct current by rectification by the rectifier 2 and smoothing by the capacitor 3. The high frequency switching of the switching circuit 4 converts the direct current into high frequency alternating current.

Furthermore, the high frequency alternating current of the switching circuit 4 is input to the rectifier 11 via the transformer 9, and is rectified by the rectifier 11, reactor 14, and capacitor 1.
High frequency alternating current is converted to direct current by the smoothing of 5,
The direct current is applied to lamp 16.

By the way, in order to start lighting the lamp 16, a high frequency high voltage from a high frequency high voltage generator (not shown) is also applied to the lamp 16, for example, for a short time immediately after the aforementioned lighting switch is turned on.

Then, when the lamp 16 is discharged and turned on based on the application of high frequency and high voltage, a driving current formed by smoothing the reactor 14 and the capacitor 15 flows through the electric path between the lamp 16 and the detector 18, and is detected. The drive current is detected by the device 18.

Furthermore, the detection signal of the detector 18 is input to the amplifier 20, and a drive control signal proportional to the difference between the detection signal and the control reference signal from the power supply 19 is outputted from the amplifier 20 to the control circuit 21.

Note that the voltage of the control reference signal is set in advance based on the amount of light from the lamp 16 and the like.

Further, when the amplifier 20 is driven by a single positive power supply, the drive control signal changes from the reference voltage in proportion to the difference.

Then, based on the drive control signal, the control circuit 2
1 controls the switching of transistors 5 to 8 of the switching circuit 4 so that the detection signal matches the control reference signal and the difference becomes zero.

Therefore, based on the feedback control of the detector 18, the amplifier 20, and the control circuit 21, the drive current is constant current controlled to the current value set by the control reference signal, and a drive current with constant current characteristics is supplied to the lamp 16. , the lamp 16 during projection is lit with a constant light intensity determined by the drive current.

[Problem that the invention seeks to solve]

By the way, in the case of the conventional light source power supply device,
Regardless of whether the shutter shown in Figure 8a is opened or closed,
The drive current of the predetermined current value Ia shown in the figure b is applied to the lamp 1.
6 and the lamp 16 continues to be lit at a constant light intensity suitable for projection, the efficiency of power usage is low.Moreover, in order to increase the light intensity of the lamp 16, an expensive one with a large rated value must be used. There are some unavoidable problems.

This invention has been made with the above-mentioned problems in mind.

[Means for solving problems]

Means for solving the above problems will be explained below.

In a light source power supply device that supplies a direct current drive current to a projection lamp consisting of a discharge lamp of a projector, and performs feedback control of the drive current so that a detection signal of the drive current matches a control reference signal, comprising: A shutter opening/closing detection device outputting a shutter opening/closing detection signal; a closing reference signal output means outputting a closing reference signal for weak lighting of the lamp; and an opening reference signal outputting means for outputting an open reference signal greater than the closing reference signal. means for closing the shutter based on the detection signal;
A technical measure is taken to include gate means for switching and outputting the closed reference signal and the open reference signal as the control reference signal in synchronization with the opening.

A shutter opening/closing detection device for outputting an opening/closing detection signal for the shutter of the projector; a closing reference signal output means for outputting a closing reference signal for weak lighting of the lamp; auxiliary open reference signal output means for outputting a reference signal; main open reference signal output means for outputting a main open reference signal for a full open period that is greater than the auxiliary open reference signal; A technical measure is taken to provide a gate means for switching and outputting the closed reference signal and the main and auxiliary open reference signals as the control reference signal.

A shutter opening/closing detection device for outputting an opening/closing detection signal for the shutter of the projector; a closing reference signal output means for outputting a closing reference signal for weak lighting of the lamp; auxiliary open reference signal output means for outputting a reference signal; main open reference signal output means for outputting a main open reference signal for a full open period that is greater than the auxiliary open reference signal; gate means for switching and outputting the closed reference signal and the main and auxiliary open reference signals as the control reference signals; A technical measure is taken to include a reference signal variable means for varying the sub-open reference signal.

a shutter opening/closing detection device for outputting an opening/closing detection signal for the shutter of the projector; a closing reference signal outputting means for outputting a closing reference signal for weak lighting of the lamp; a reference signal output means; a changeover switch means for fixed and variable setting of the control reference signal; outputting a fixed reference signal for a constant light amount when the switch means is set to the fixed state; and outputting the fixed reference signal for a constant light amount when the switch means is set to the variable state; Based on this, a technical measure is taken to provide a gate means for switching and outputting the close reference signal and the open reference signal as the control reference signal in synchronization with the opening and closing of the shutter.

[Effect]

Therefore, the technical problem is solved as follows.

The drive current supplied to the projection lamp in synchronization with the opening and closing of the shutter changes in large and small pulses, and even if the current value when the shutter opens is larger than before, the average value of the drive current is lower than before. This will improve the efficiency of power usage.

The drive current is varied in three stages in synchronization with the opening and closing of the shutter, significantly improving power usage efficiency.
In addition, since the drive current changes from a minute value during the closed period to a maximum value during the fully open period via a current value during the opening/closing transition period, or vice versa, stress on the projection lamp can be suppressed.

The drive current is varied in three stages in synchronization with the opening and closing of the shutter, significantly improving power usage efficiency.
In addition, since the drive current changes from a small value during the closing period to a maximum value during the fully open period via the current value during the opening/closing transition period, or vice versa, stress on the projection lamp is suppressed. The reference signal can always be variably set at a constant ratio, and the drive current can be easily variably set while maintaining the best condition with less stress.

The drive current is large in synchronization with the opening and closing of the shutter.
The control reference signal can be changed to a fixed reference signal for a constant amount of light as in the conventional case, as required, by switching the changeover switch means.

〔Example〕

Next, this invention will be described in the first part showing its embodiment.
This will be explained in detail with reference to FIGS.

(One Embodiment) First, FIGS. 1 to 3 showing one embodiment will be explained.

In FIG. 1, the same symbols as in FIG. 7 indicate the same or equivalent parts, and 22 is the projection lamp 16.
23 is a shutter opening/closing detection device built into the projector 22, which detects the opening/closing of the shutter (not shown) shown in FIG. The opening/closing detection signal that is inverted is optically transmitted.

Reference numeral 24 denotes a signal switching circuit into which the detection signal of the detection device 23 is received and input, and by switching the signal based on the detection signal, the output voltage of the variable DC power supply 25, which forms the closing reference signal output means, is changed in synchronization with the opening and closing of the shutter. The main and auxiliary open reference signals formed based on the closed reference signal and the output voltage signal of the variable DC power supply 26 are switched and outputted to the amplifier 20 as control reference signals.

The closing reference signal is a reference signal for weak lighting during the complete closing period when the shutter is completely closed, and controls the drive current to a weak current value Ib ₁ that does not cause the activated lamp 16 to go out.

The main open reference signal is a reference signal for the full open period when the shutter is completely opened, and in order to set the light intensity of the lamp 16 to a large light intensity that is higher than the conventional light intensity, the drive current is changed to a predetermined current close to the maximum current of the lamp 16. Control to value Ip.

Furthermore, the sub-open reference signal is a reference signal during the opening/closing transition period when the shutter changes from open to closed and vice versa.In order to make the amount of light during the opening/closing transition period less than that during the fully open period, the drive current is set to a predetermined value lower than the current value Ip. The current value is controlled to a current value Ib ₂ (Ip<Ib ₂ <<Ib ₁ ), for example, 1/3 of Ip.

By the way, the switching circuit 24 is configured as shown in FIG. 3 in order to switch and output the aforementioned close reference signal and the main and sub-open reference signals in synchronization with the opening and closing of the shutter.

In FIG. 3, 27 is the detection device 23.
This detector is formed using a position detection sensor, etc., and outputs the above-mentioned opening/closing detection signal. A light emitting diode 28 for optical transmission is connected to the detector 27 via a current limiting resistor 29, and emits light with an amount of light according to the level of the detection signal, and optically transmits the detection signal.

Reference numeral 30 denotes an NPN type phototransistor provided in the switching circuit 24, and receives the optical signal from the light emitting diode 28. 31 is an NPN buffer transistor whose base receives the emitter voltage of transistor 31; 32 is a backflow prevention diode whose anode receives the collector voltage of transistor 31; and 33, whose input terminal i is connected to inverter 3.
A first monostable multivibrator (hereinafter referred to as a monostable multivibrator) is connected to the cathode of the diode 32 via the input terminal i, and is triggered by the rise of the level of the input terminal i. A high level signal is output from the output terminal q for the time set by the resistor 35 and capacitor 36, that is, the first opening/closing transition period τa of the shutter.

37 is a second mono multi whose input terminal is connected to the output terminal q of the mono multi 33, which is triggered by the fall of the level of the input terminal i, and is set by a time constant resistor 38 and capacitor 39. time, i.e., the fully open period τb of the shutter.
A high level signal is output from output terminal q.

40 is the output terminal q of multi-37 whose anode is mono
41 is an inverter whose input terminal is connected to the cathode of the diode 40, and 42 and 43 are backflow prevention diodes whose anodes are connected to the cathode of the diode 40 and the output terminal of the inverter 41, respectively. There are two diodes.

44 is a level adjuster formed using an operational amplifier 45, and resistors 46, 4 for setting a multiplier on the output voltage signal of the power supply 26, that is, the main open reference signal.
Multiply by a multiplier α (0<α<1) determined by 7,48,
A sub-open reference signal having a voltage α times that of the main open reference signal is formed and output. 49 and 50 are diodes 42 and 4
These are two analog switches for gates that are turned on at the high level of the output signals of 3 and 2.
The main open reference signal of 6 and the auxiliary open reference signal of regulator 44 are output from switches 49 and 50, respectively.

51 is two diodes 52, 5 for backflow prevention.
3 forms a signal selection gate circuit, and input resistors 54 and 55 are connected to the anode of the diode 52.
The main open reference signal from the switch 49 via the input resistor 54 and the auxiliary open reference signal from the switch 50 via the input resistors 54 and 56 are input to the anode of the diode 53, and the power supply 25 via the input resistor 57 is input. The output voltage signal of, ie, the closed reference signal, is input.

58 is an NPN type transistor whose base is connected to the cathode of the diode 32, and whose collector is connected to the anode of the diode 51 and whose emitter is grounded. is muted to turn off the diode 51. Reference numeral 59 denotes an amplifier that amplifies the output signals of the cathodes of the diodes 52 and 53, and outputs the output signals to the amplifier 20 as control reference signals.

Note that 60 and 61 are resistors for base bias and collector load of the transistor 31, and +B is a positive power supply terminal.

In addition, a light emitting diode 28, a transistor 30
consists of a photocoupler.

The power supply 26 forms a main open reference signal output means, and the power supply 26 and the regulator 44 form a auxiliary open reference signal output means.

Furthermore, a light emitting diode 30 and a transistor 3
1, inverters 34, 41, and monomulti 3
3 and 37 form a timer circuit 62 for generating a switching control signal for the closed reference signal and the main and auxiliary open reference signals, and the analog switches 49 and 50, the gate circuit 51, and the transistor 58 form a signal switching gate. Gate means is formed by the circuit 62 and the signal switching gate.

Then, as shown in FIGS. 2a and 4a, the detection device 23 optically transmits a detection signal whose level changes in synchronization with the opening and closing of the shutter from the light emitting diode 28. Upon receiving even a small amount of an optical signal, the transistor 30 is immediately turned on.

Therefore, when the shutter is completely closed and no optical signal is output, the transistors 30 and 31
is turned off, and the transistor 3 is turned off as shown in FIG. 4b.
As the collector voltage of 1 becomes high level,
The input terminal i of the monomulti 33 is held at a low level, and at this time, the level of the output terminal q of the monomulti 33 becomes a low level as shown in c in the figure.
The level of the output terminal q of the monomulti 37 also becomes low level as shown in d of the same figure.

Then, due to the high level of the collector voltage of the transistor 31, the transistor 58 is turned on and the input signal of the diode 53 is muted, and the closed reference signal of the power supply 25 is output from the gate circuit 51.
The closed reference signal via the amplifier 59 is output to the amplifier 20, and the drive current of the lamp 16 is controlled to a constant current value Ib ₁ as shown in FIG. 2b, so that the lamp 16 is slightly lit.

Next, when the shutter begins to change from closed to open and an optical signal begins to be output from the light emitting diode 28, the transistor 30 is immediately turned on, the transistor 31 is turned on, the transistor 58 is turned off, and the monomulti 33 is triggered,
For example, the Q output terminal q of the monomulti 33 becomes high level only during the switching transition period τa shown from t ₀ to _{t 1} in FIGS. 4b and 4c.

Furthermore, when the Q output terminal q of the monomulti 33 falls to a low level after the period τa has elapsed, the mono multi 37 is triggered, and for example, only during the fully open period from t ₁ to t ₂ shown in FIG. 4 b and d. The Q output terminal q of the monomulti 37 becomes high level.

Therefore, during the period τa during which the shutter changes from closed to open, the mute state of the diode 51 is released by turning off the transistor 58, and the high level of the inverter 41 based on the low level of the Q output terminal q of the monomulti 37 is The switch 50 is turned on by the output signal of the regulator 44 because the voltage of the sub-open reference signal is higher than that of the closed reference signal.
The driving current of the lamp 16 is the current value.
Ib ₂ , and the amount of light from the lamp 16 increases.

Next, when the transient period τa has elapsed and the shutter is completely opened, the monomulti 37 is triggered and the output terminal q of the mono multi 37 becomes high level, as described above, and at this time, the switch 50 is turned off. The switch 49 is turned on.

Therefore, the main open reference signal of the power supply 26 is selected and outputted from the gate circuit 51, and the drive current of the lamp 16 is constant current controlled to the largest current value Ip,
The amount of light from the lamp 16 is maximized.

Next, a transition period τb elapses and, for example, the fourth
At t ₂ in Figures b and d, when the shutter begins to change from open to closed, the output terminal q of the monomulti 37 becomes low level during the second opening/closing transition period τa' until the shutter completely closes t ₃ . , the switch 49 is turned off and the switch 50 is turned on again.

Therefore, the sub-open reference signal of the regulator 44 is selected again and output from the gate circuit 51, and the lamp 1
The driving current of lamp 16 decreases to the current value Ib ₂ , and the lamp 16
light intensity decreases.

Then, when the transient period τa' has elapsed and the shutter is completely closed again, the light signal from the light emitting diode 28 is cut off, and the transistors 30 and 58 are turned off.
The close reference signal is selected again and outputted from the gate circuit 51, the driving current for the lamp 16 is reduced to the current value _Ib1 , and the lamp 16 lights up weakly until the shutter starts to open again by frame feeding of the film.

Therefore, the drive current of the lamp 16 changes in a pulsed manner as shown in FIG.
At the same time, the current value becomes Ib ₁ , the largest current value Ip during the fully open period τb of the shutter, and a current value Ib ₂ which is 1/α times the current value Ip during the shutter opening/closing transition period τa, τa'.

Therefore, even if the current value Ip during the fully open period in which a complete image is projected by the light of the lamp 16 is made higher than before, the average value of the drive current is lower than before, and it is possible to achieve a higher light intensity than before with less power consumption. Projection can be performed, power efficiency is significantly improved, and projection with a large amount of light can be performed using the lamp 16 with a small rated value.

Note that the ratio of the main and auxiliary open reference signals, that is, α
is set in consideration of the power supply efficiency and the stress on the lamp 16, and is set to a value that improves the power supply efficiency and causes less stress on the lamp 16 so as not to impair its life.

By the way, in the case of the above embodiment, the power supply 26 and the regulator 44 form the reference signal variable means, and the main open reference signal of the power supply 26 is multiplied by 1/α by the regulator 44 to form the auxiliary open reference signal. When the power supply 26 is variably adjusted and the level of the main open reference signal is adjusted and set according to the usage conditions, the sub-open reference signal is automatically set to 1/α times the main open reference signal, and the main and sub-open reference signals are The ratio of the reference signal is always constant.

Therefore, if the power supply 26 is set variably in order to adjust the light intensity of the lamp 16, the power supply efficiency will be improved and the stress will be reduced at a constant rate.
Main and sub open reference signals can be set.

In the above embodiment, the drive current during the transient periods τa and τa' where no problem occurs even if the amount of light is small or small is made smaller than when the switch is completely opened, and the drive current is varied in three stages to improve power supply efficiency. However, by fixing the drive current during the shutter open period including the transient periods τa and τa′ to the current value Ip, and synchronizing with the opening and closing of the shutter,
Even if the drive current is switched to two levels of current values Ip and Ib ₁ ,
Power supply efficiency is improved compared to conventional models.

When switching the drive current to two stages,
Instead of the switching circuit 24, for example, the transistors 30, 31, 58 and the gate circuit 5 of FIG.
1. A signal switching circuit including only a gate means consisting of an amplifier 59 is provided, and the power supply 26 is provided as an open reference signal output means, and the open reference signal of the power supply 26 is directly input to the diode 52 of the gate circuit 51, and the shutter Transistor 5 synchronized to open and close
8, the open reference signal and the closed reference signal of the power supplies 26 and 25 may be switched and outputted to the amplifier 20 as control reference signals.

(Other Embodiments) Next, FIGS. 5 and 6 showing other embodiments will be described.

In FIGS. 5 and 6, the same symbols as in FIGS. 1, 3, and 7 indicate the same or equivalent components, and 63 is provided in place of the switching circuit 24 in FIGS. 1 and 3. This is a signal switching circuit that includes a power supply 25 for the closed reference signal, a power supply 26 for the main and auxiliary open reference signals,
A power source 19 for a conventional reference signal, that is, a fixed reference signal for a constant amount of light, is connected.

64 is a changeover switch having two contacts v and w, and a changeover piece is connected to the power supply terminal +B. 6
5 is a changeover switch having two contacts v' and w';
It is inserted into the collector path of the transistor 58, the switching piece is connected to the collector of the transistor 58, and the contact point v' is connected to the anode of the diode 52, and when operated, it is switched in conjunction with the switch 64, thereby operating the changeover switch means. Form.

66 and 67 are two diodes for backflow prevention whose anodes are connected to contacts v and w, respectively;
Reference numerals 8 and 69 are two analog switches for gates that are turned on when the output signals of the diodes 66 and 67 are at high level, respectively.
9 is output to the regulator 44 and switch 49 via the input resistor 70.

71 is a backflow prevention diode whose anode is connected to contact w, and whose cathode is connected to diode 4.
Connected to the cathode of 2. 72 is a backflow prevention diode whose anode is connected to contact w;
73 is an NPN type transistor whose base is connected to the cathode of the diode 72 via an input resistor 74, whose collector is connected to the cathode of the diode 43, and whose emitter is grounded.

Note that each part of the switching circuit 63 except for the regulator 44 and the timer circuit 62 forms a gate means.

That is, the switching circuit 63 causes the switching circuit 24 to
Close reference signal, main and auxiliary open reference signals, and power supply 19
It is formed by adding a gate that switches between and outputs a fixed reference signal.

Normally, the switches 64 and 65 are held at the contacts v and v', and at this time, the high level of the contact v turns on the switch 68, and the contact w
The low level turns off switch 69 and turns off transistor 73, and furthermore, the collector of transistor 58 is connected to the anode of diode 52 via contact v'.

Therefore, the switching circuit 63 operates in the same manner as the switching circuit 24, and switches and outputs the closed reference signal and the main and sub-open reference signals to the amplifier 20 in synchronization with the opening and closing of the shutter.

By the way, when used as a power supply device for an existing projector not provided with the detection device 23, the switches 64 and 65 are switched to the contacts w and w'.

At this time, the switches 68 and 69 are turned off by the low level and high level of the contacts v and w, respectively.
The fixed reference signal of the power supply 19 is output to the switch 49 and regulator 44 instead of the main open reference signal.

Also, depending on the high level of contact w, switch 4
9. The transistor 73 turns on and the contact
Switching to w' disconnects the collector of transistor 58 from the anode of diode 52.

Then, by turning on the transistor 73, the high level signal output from the inverter 41 to the switch 50 via the diode 43 is muted, and the switch 50 is kept off, so that the fixed reference signal via the switch 49 is output from the diode. 52
At this time, since the fixed reference signal has a higher voltage than the closed reference signal, the fixed reference signal is output from the gate circuit 51 regardless of whether the shutter is opened or closed.

Therefore, the switches 64 and 65 are the contacts w,
When switched to w', the fixed reference signal is output as a control reference signal from the switching circuit 63 to the amplifier 20 regardless of whether the shutter is opened or closed, and the drive current is fixed at a constant value Ia determined by the fixed reference signal. It is current controlled and operates like a conventional power supply.

Therefore, in this embodiment, switch 6
To provide a highly versatile power supply device which can be used by switching between the power supply device of the first embodiment and a conventional power supply device based on the switching of the power supply device No. 4 and 65, and which has the same effects as the first embodiment. It produces the effect that can be achieved.

Note that when the switches 64 and 65 are switched to the contacts v and v', the drive current may be switched in two stages in synchronization with the opening and closing of the shutter. , for example, transistors 30, 31, 58, diodes 66, 67, switches 68, 69, gate circuit 5
1. A signal switching circuit including only a gate means consisting of an amplifier 59 is provided, a power supply 26 is provided as an open reference signal output means, and switches 68, 69 are provided.
The open reference signal and fixed reference signal of the power supplies 26 and 19 via the gate circuit 51 may be input directly to the diode 52 of the gate circuit 51.

Incidentally, in both of the above embodiments, the lamp 16 is formed of a xenon lamp, but it goes without saying that the lamp 16 may be formed of any of various discharge lamps for projection purposes.

〔Effect of the invention〕

As described above, according to the power supply device for a light source of the present invention, a large drive current is generated in synchronization with opening and closing of the shutter.
This makes it possible to project a large amount of light with the same amount of power consumption as the conventional one.

The drive current is varied in three stages in synchronization with the opening and closing of the shutter, significantly improving power usage efficiency.
It is possible to project a significantly large amount of light with the same power consumption as conventional models, and the drive current changes from a small value during the closed period to a maximum value during the fully open period via the current value during the opening/closing transition period, or vice versa. , it is possible to suppress stress on the projection lamp and extend the lamp life.

The drive current is varied in three stages in synchronization with the opening and closing of the shutter, significantly improving power usage efficiency.
It is possible to project a significantly large amount of light with the same power consumption as conventional models, and the drive current changes from a small value during the closed period to a maximum value during the fully open period via the current value during the opening/closing transition period, or vice versa. , the stress on the projection lamp can be suppressed to extend the lamp life, and the main and sub-opening reference signals can always be variably set at a constant ratio, making it easy to control the drive current by keeping the stress in the best condition. It can be set variably.

The drive current is large in synchronization with the opening and closing of the shutter.
It is possible to project a large amount of light with the same amount of power consumption as before, and it is possible to project a large amount of light with the same level of power consumption as before.Furthermore, based on the changeover of the changeover switch means, the control reference signal can be changed to a constant light amount like before. This makes it possible to switch to a fixed reference signal for use in other applications, thereby providing a highly versatile device.

[Brief explanation of drawings]

1 to 4 show one embodiment of the power supply device for a light source according to the present invention, FIG. 1 is a block diagram, and FIG. 2 is a block diagram.
Figures a and b are explanatory diagrams of shutter opening/closing and drive current, respectively, Figure 3 is a detailed wiring diagram of the signal switching circuit,
4a to 4d are timing charts for explaining the operation of FIG. 3, FIGS. 5 and 6 show other embodiments of the present invention, FIG. 5 is a block diagram, and FIG. 6 is a signal switching circuit. 7 is a block diagram of a conventional power supply device for a light source, and FIGS. 8a and 8b are explanatory diagrams of opening/closing of the shutter and drive current shown in FIG. 7, respectively. 2, 11... Rectifier, 3, 15... Smoothing capacitor, 4... High frequency switching circuit, 9... Output transformer, 14... Smoothing reactor, 16...
Projection lamp, 18...Current detector, 20...Error amplifier, 21...Drive control circuit, 23...Shutter opening/closing detection device, 24, 63...Signal switching circuit,
19, 25, 26...Variable DC power supply, 64, 65
...changeover switch.

Claims (1)

[Scope of Claims] 1. A light source for supplying a direct current drive current to a projection lamp consisting of a discharge lamp of a projector, and controlling the drive current in feedback so that a detection signal of the drive current matches a control reference signal. The power supply device includes: a shutter opening/closing detection device for outputting an opening/closing detection signal for the shutter of the projector; a closing reference signal output means for outputting a closing reference signal for weak lighting of the lamp; and an open reference signal greater than the closing reference signal. and gate means for switching and outputting the close reference signal and the open reference signal as the control reference signal in synchronization with closing and opening of the shutter based on the detection signal. A power supply device for a light source characterized by: 2. In a light source power supply device that supplies a direct current drive current to a projection lamp consisting of a discharge lamp of a projector, and performs feedback control of the drive current so that a detection signal of the drive current matches a control reference signal, comprising: a shutter opening/closing detection device that outputs an opening/closing detection signal for the shutter; a closing reference signal output means for outputting a closing reference signal for weak lighting of the lamp; and a sub-opening reference signal for an opening/closing transition period that is greater than the closing reference signal. a main open reference signal output means for outputting a main open reference signal for a fully open period that is greater than the sub open reference signal; 1. A power supply device for a light source, comprising: a closing reference signal; and gate means for switching and outputting the main and auxiliary open reference signals as the control reference signal. 3. A light source power supply device that supplies a direct current drive current to a projection lamp consisting of a discharge lamp of a projector, and performs feedback control of the drive current so that a detection signal of the drive current matches a control reference signal, comprising: a shutter opening/closing detection device that outputs an opening/closing detection signal for the shutter; a closing reference signal output means for outputting a closing reference signal for weak lighting of the lamp; and a sub-opening reference signal for an opening/closing transition period that is greater than the closing reference signal. a main open reference signal output means for outputting a main open reference signal for a fully open period that is greater than the sub open reference signal; gate means for switching and outputting a closing reference signal and the main and auxiliary open reference signals as the control reference signals; 1. A power supply device for a light source, comprising: reference signal variable means for varying an open reference signal. 4. In a light source power supply device that supplies a direct current drive current to a projection lamp consisting of a discharge lamp of a projector, and performs feedback control of the drive current so that a detection signal of the drive current matches a control reference signal, a shutter opening/closing detection device that outputs an opening/closing detection signal for the shutter; a closing reference signal output means for outputting a closing reference signal for weak lighting of the lamp; and an open reference signal outputting an open reference signal greater than the closing reference signal. output means; a changeover switch means for fixed and variable setting of the control reference signal; outputting a fixed reference signal for a constant light amount when the switch means is set to the fixed state; and outputting a fixed reference signal for a constant light amount when the switch means is set to the variable state; A power supply device for a light source, comprising gate means for switching and outputting the close reference signal and the open reference signal as the control reference signal in synchronization with opening and closing of the shutter.