JP2008177049A - Lighting device and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device capable of simplifying a structure of a device at a low cost, and a projector equipped with this lighting device. <P>SOLUTION: Detection circuits 21R, 21G, 21B installed a plurality of pieces for every color detect electric current flowing in light-emitting elements 2R, 2G, 2B of each color and output a detection signal corresponding to detected current to a first switch 11. A memory part 9 stores a reference signal to become a reference for every color and outputs the reference signal to a second switch 12. A power control part 8 outputs a power control signal based on a difference between the detection signal output via the first switch 11 and the reference signal output via the second switch 12 to a third switch 13. The third switch 13 switches the outputting address of the power control signal output from the power control part 8 to any of a plurality of drive circuits 20R, 20G, 20B. A synchronized control part 7 controls in synchronization the first to the third switches 11-13 for every color. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device of a plurality of colors, a lighting device including a driving circuit that sequentially controls lighting of each color with predetermined power by controlling a main switch of the light emitting device, and a projector including the lighting device.

There is a projector as a display device that projects light onto a screen to display an image. In recent years, solid-state light-emitting elements such as LEDs (Light Emitting Diodes) have attracted attention in terms of convenience and environmental load, instead of conventional mercury discharge lamps such as metal halide lamps as light sources for projectors. When displaying a color image, red, green, and blue LEDs are usually used. A system is known in which each color LED is controlled to be sequentially turned on in synchronization with an input video signal by a switching element such as a power FET (Field-Effect Transistor) and displayed in color. The projector can easily add yellow, cyan, or the like to the three primary colors of red, green, and blue, and is currently the only display device that can be commercialized with multiple primary colors. In order to light the light emitting element stably, a red driving circuit, a green driving circuit, and a blue driving circuit are provided for each color. Further, an error amplifier is provided to supply predetermined power to the light emitting element, and a power control signal such as PWM (Pulse Width Modulation) is generated based on the output of the error amplifier to perform switching control (for example, Patent Document 1 and 2).
JP 2004-163527 A JP 2006-229209 A

  In such a projector, in order to facilitate the design of the optical system, a small number of (for example, one) power LEDs having a small light emitting area are used. As the corresponding screen size increases, higher power LEDs are used. For this reason, there is a tendency that the rating of the switching element FET, the FET driver for driving it, the snubber, and the heat radiation fin are increased in size and scale. For this reason, a technique different from the backlight of a direct-viewing type liquid crystal display device in which a large number of relatively small LEDs can be arranged and general lighting equipment is required. Further, in order to cause each color LED to emit light sequentially in a time-sharing manner, it is necessary to operate the drive circuit intermittently at a frequency several times the frequency of the vertical synchronizing signal of the video. Therefore, a technique different from that of a general switching power supply circuit is required.

  However, the lighting device described in Patent Document 1 is provided with an error amplifier for each color in addition to a drive circuit for each color, resulting in variations in control characteristics, an increase in the number of components, an increase in size of the device, and an increase in cost. There was a problem. The LED driving device described in Patent Document 2 uses a single error amplifier, but there are many switching elements that turn on and off the power line, and the power LED driving circuit is operated intermittently for time-division emission. There was a problem of not touching the issues to be made. As the rated power of LEDs increases in capacity and multi-primary colors, the above problem becomes more apparent.

  The present invention has been made in view of such circumstances, and an object of the present invention is to detect an electric quantity related to driving of a light emitting element for each color, prepare a reference signal for each color, and set the first and second switches. Synchronously controlled, a power control signal is output by one power control unit, and the power control signal is output to a plurality of drive circuits provided for each color through a third switch that is synchronously controlled, thereby reducing the cost of the apparatus. An object of the present invention is to provide a lighting device capable of simplifying the configuration and a projector including the lighting device.

  Another object of the present invention is to detect the intensity of light by a light emitting element and output a power control signal to a drive circuit in consideration of a signal based on the detected light emission intensity, a synchronously controlled reference signal, and a detection signal. Accordingly, an object of the present invention is to provide a lighting device that can perform lighting control of a light emitting element with higher accuracy and a projector including the lighting device.

  A lighting device according to the present invention is a lighting device including a plurality of color light emitting elements, and a plurality of drive circuits provided for each color for controlling the lighting and power of the light emitting elements by turning on and off the main switch. A plurality of detection circuits for detecting the amount of electricity related to driving, a first switch for switching input of detection signals based on the amount of electricity output from the plurality of detection circuits, and a plurality of memories storing reference signals for each color , A second switch for switching input of reference signals output from the plurality of storage units, a detection signal output via the first switch, and a reference signal output via the second switch A power control unit that outputs a power control signal based on the difference; a third switch that switches an output destination of the power control signal output from the power control unit to any of the plurality of drive circuits; Characterized in that it comprises a synchronization control unit for controlling synchronization of the switches for each color of light emitting elements.

  The lighting device according to the present invention further includes an intensity detection circuit that detects light emission intensity of the light emitted from the light emitting element, and the power control unit includes a detection signal output via the first switch and the intensity detection circuit. A power control signal is output based on a difference between a signal based on the detected emission intensity and a value obtained by subtracting a reference signal output via the second switch.

  A projector according to the present invention includes the above-described lighting device.

  In the present invention, the lighting device includes a plurality of light emitting elements and a plurality of drive circuits provided for each color. The drive circuit controls lighting of the light emitting element by turning on and off the main switch. A plurality of detection circuits provided for each color detects the amount of electricity related to driving the light emitting elements of each color, and outputs a detection signal based on the detected amount of electricity to the first switch. The first switch switches input of detection signals output from the plurality of detection circuits.

  A plurality of storage units provided for each color stores a reference signal that is a reference for each color, and outputs the reference signal to the second switch. The second switch switches input of the reference signal output from the plurality of storage units. The power control unit outputs a power control signal based on a difference between a detection signal output via the first switch and a reference signal output via the second switch to the third switch. The third switch switches the output destination of the power control signal output from the power control unit to one of the plurality of drive circuits. The synchronization control unit synchronously controls the first to third switches for each color of the light emitting element. The power control signal output for each color by the synchronization control is output to the drive circuit, and the lighting control of the light emitting element is performed by the switching control according to the power control signal.

  In the present invention, the intensity detection circuit detects the light emission intensity of the light emitted from the light emitting element. The power control unit is a value obtained by subtracting the reference signal output via the second switch from the detection signal output via the first switch and the signal based on the emission intensity detected by the intensity detection circuit. A power control signal based on the difference between the two is output.

  In the present invention, the power control signal based on the difference between the detection signal output via the first switch and the reference signal output via the second switch is output to the third switch. The third switch switches the output destination of the power control signal output from the power control unit to one of the plurality of drive circuits. The power control signal output for each color by the synchronization control is output to the drive circuit, and the lighting control of the light emitting element is performed by the switch control according to the power control signal. Thus, a single power control unit can output a power control signal to a plurality of drive circuits for each color, and the device can be reduced in size and cost.

  In the present invention, the intensity detection circuit detects the light emission intensity of the light emitted from the light emitting element. The power control unit is a value obtained by subtracting the reference signal output via the second switch from the detection signal output via the first switch and the signal based on the emission intensity detected by the intensity detection circuit. A power control signal based on the difference between the two is output. With this configuration, it is possible to obtain a power control signal that also considers the light emission intensity in addition to the reference signal for each color related to the reference voltage or current, and to realize more detailed lighting control. Become.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a projector according to the present invention. The projector includes a lighting device 1, a condenser lens 5, an image forming element (hereinafter, DMD (Digital Micromirror Device (registered trademark)) 4, an image forming element control circuit 41, and a projection lens 6. Red, green and blue Light emitted from each light emitting element (hereinafter, LED) 2R, 2G, 2B (hereinafter abbreviated as R, G, B in some cases) is collected by the condenser lens 5 and irradiated to the DMD 4.

  The DMD 4 is driven and controlled by the image forming element control circuit 41. The video forming element control circuit 41 drives the DMD 4 according to the input video signal. Specifically, by turning on or off each cell or micromirror of the DMD 4 according to the input video signal, the irradiated R, G, and B light is reflected in a pixel unit to perform light modulation, and image light is converted. Form. The formed image light is incident on the projection lens 6 and is enlarged and projected on a screen or the like (not shown) by the projection lens 6.

  The lighting device 1 includes a power supply circuit 3, drive circuits 20R, 20G, and 20B (hereinafter, represented by the drive circuit 20 in some cases), LEDs 2R, 2G, and 2B (hereinafter, represented by the LED 2 in some cases), a first switch 11, The synchronization control unit 7, the storage unit 9, the second switch 12, the power control unit 8, and the third switch 13 are included. The drive circuits 20R, 20G, and 20B are connected in parallel to the power supply circuit 3 that supplies a DC voltage. The drive circuits 20R, 20G, and 20B are provided for the three colors R, G, and B, and a step-up / step-down DC-DC converter or the like is used. In the present embodiment, a description will be given with respect to an embodiment in which LEDs 2 of three colors R, G, and B are used, but in addition to these, a configuration may be adopted in which LEDs of yellow or cyan are further added.

  The drive circuit 20R includes a switching element drive circuit 23R, a main switch (hereinafter referred to as a switch) 22R, and a detection circuit 21R. The switching element drive circuit 23R turns on / off the switch 22R by PWM control based on the pulse width related to the power control signal output from the power control unit 8. When the duty ratio is large, the ON time of the switch 22R becomes long, and a large amount of current flows to the LED 2R. Further, when the duty ratio is small, the ON time of the switch 22R is shortened, and the current flowing to the LED 2R is reduced. The LED 2R is a single red LED or a plurality of red LEDs arranged in an array, and the red light emitted from the LED 2R is incident on the condenser lens 5. The first switch 11, the second switch 12, and the third switch 13 are switched in synchronization with the input video signal. A PWM signal is sent only to the color switch 22R, switch 22G or switch 22B selected by these switches, and only the corresponding color LED 2 is lit. The LED 2 in the non-selected state is turned off. The first switch 11, the second switch 12, and the third switch 13 are elements that switch small signals, and their cost and size are so small that they cannot be compared with the switch 22 that switches large power. In this embodiment, the lighting control of the LED 2 is described as being performed by PWM control. However, the present invention is not limited to this, and may be performed by PFM (Pulse Frequency Modulation) control.

  The detection circuit 21 </ b> R is a circuit that detects the amount of electricity related to the driving of the LED 2 </ b> R, specifically, the current flowing through the LED 2 </ b> R, and outputs a detection signal corresponding to the detection current to the first switch 11. It should be noted that LEDs generally exhibit constant voltage load characteristics and current consumption is likely to fluctuate, so it is common to detect current and stabilize lighting, but when other lamps are used, etc. The detected voltage may be detected. The drive circuit 20G also includes a switching element drive circuit 23G, a switch 22G, and a detection circuit 21G, and the drive circuit 20B also includes a switching element drive circuit 23B, a switch 22B, and a detection circuit 21B. Since these configurations are the same as the configuration of the drive circuit 20R, description thereof is omitted. In the following, the switching element drive circuits 23R, 23G, and 23B are represented by the switching element drive circuit 23, the switches 22R, 22G, and 22B are represented by the switch 22, and the detection circuits 21R, 21G, and 21B are represented by the detection circuit 21, as the case may be.

  The detection circuits 21R, 21G, and 21B are connected to the input terminals 11R, 11G, and 11B of the first switch 11, respectively. The first switch 11 switches to one of the input terminals 11R, 11G, and 11B according to the synchronization signal output from the synchronization control unit 7. The RGB color detection signals output from the detection circuit 21 are input to the power control unit 8 via the output terminal of the first switch 11 in synchronization with the switching of the first switch 11. The synchronization control unit 7 outputs a synchronization signal synchronized with RGB switching based on the video signal of the DMD 4 in the video forming element control circuit 41 to the first switch 11, the second switch 12 and the third switch 13 described later.

  The storage unit 9 stores an R reference signal storage unit 9R, a G reference signal storage unit 9G, and a B reference signal storage unit 9B. The R reference signal storage unit 9R stores a reference signal voltage representing a rated current or a desired current value of the LED 2R, and is configured by, for example, a zener diode, a shunt regulator, an IC (Integrated circuit), or the like that exhibits constant voltage characteristics. In the following description, it is assumed that a reference signal corresponding to a reference current is output from the R reference signal storage unit 9R to the second switch 12. Similarly, the G reference signal storage unit 9G and the B reference signal storage unit 9B store reference signals. The reference signal amounts for these colors may be set to different values in consideration of individual differences between the LEDs 2R, 2G, and 2B and the color temperature of the display image. When the reference signal storage unit 9 is configured by a look-up table ROM, the second switch 12 uses a DA (Digital-to-Analog) converter. The second switch 12 may not be a so-called switch such as an analog multiplexer.

  The R reference signal storage unit 9R is connected to the input terminal 12R of the second switch 12, the G reference signal storage unit 9G is connected to the input terminal 12G of the second switch 12, and the B reference signal storage unit 9B is connected to the input terminal 12R of the second switch 12. Each is connected to the input terminal 12B. The second switch 12 switches to one of the input terminals 12R, 12G, and 12B according to the synchronization signal of the synchronization control unit 7. Output to the power control unit 8 from the R reference signal storage unit 9R, the G reference signal storage unit 9G, and the B reference signal storage unit 9B via the input terminals 12R, 12G, 12B and the output terminal of the second switch 12, respectively. A reference signal is input.

  The power control unit 8 outputs a detection signal output from the detection circuit 21R via the input terminal 11R of the first switch 11 and is output from the R reference signal storage unit 9R via the input terminal 12R of the second switch 12. And a modulation signal for power control such as PWM is generated based on the deviation and output to the third switch 13. When the detection signal from the detection circuit 21R is smaller than the reference signal from the R reference signal storage unit 9R, the duty ratio of the PWM signal is increased and the ON time of the switch 22R is increased. On the other hand, when the detection signal from the detection circuit 21R is larger than the reference signal from the R reference signal storage unit 9R, the duty ratio of the PWM signal is reduced and the ON time of the switch 22R is reduced. Since G and B perform the same operation as soon as they are selected by the first switch 11, the second switch 12, and the third switch 13, the description thereof is omitted. The third switch 13 includes output terminals 13R, 13G, and 13B, and switches to any one of the output terminals 13R, 13G, and 13B according to the synchronization signal of the synchronization control unit 7. The output terminal 13R is connected to the switching element drive circuit 23R, the output terminal 13G is connected to the switching element drive circuit 23G, and the output terminal 13B is connected to the switching element drive circuit 23B.

  The PWM signal output from the power control unit 8 via the input terminal and the output terminal 13R of the third switch 13 is input to the switching element drive circuit 23R. The switching element drive circuit 23R is a circuit that charges and discharges the capacitance of the FET gate terminal of the switch 22R, and controls the switch 22R on / off based on the PWM signal. Note that the same operation is performed as soon as G and B are selected, so that the description thereof is omitted. The synchronization control unit 7 controls the first switch 11, the second switch 12, and the third switch 13 in synchronization with each other based on the synchronization signal, so that the currents flowing through the LEDs 2R, 2G, and 2B sequentially according to the stored contents of the storage unit 9. It will be feedback controlled.

  FIG. 2 is a circuit diagram showing a circuit configuration of the power control unit 8. The power control unit 8 includes an adjustment unit 81 and an operation unit 82 as shown in FIG. The adjustment unit 81 includes a resistor Ri, a resistor Rf, a capacitor Cf, and an error amplifier 811. A resistor Ri, a resistor Rf, and a capacitor Cf are connected to the first switch 11 in series. One end of a resistor Ri that is an input resistor of the error amplifier 811 is connected to the resistor Rf and an inverting input terminal of the error amplifier 811. The second switch 12 is connected to the non-inverting input terminal of the error amplifier 811. The error amplifier 811 multiplies a deviation obtained by subtracting the detection signal input via the first switch 11 from the reference signal input via the second switch 12, and outputs the result to the operation unit 82. .

  The operation unit 82 includes a comparator 812 and a sawtooth wave oscillator 813. The signal output from the adjustment unit 81 is input to the non-inverting input terminal of the comparator 812, and the sawtooth wave output from the sawtooth oscillator 813 is input to the inverting input terminal of the comparator 812. The comparator 812 compares the voltages of the two input signals to determine the duty ratio of the PWM signal. The PWM signal thus generated is output to the third switch 13. The analog control circuit shown in FIG. 2 is merely an example, and the present invention is not limited to this form. According to the present embodiment, only one power control analog IC (power control unit 8) and a few inexpensive small signal switches (first switch 11, second switch 12, third switch 13) are used. Three LED drive circuits (drive circuit 20) can be controlled. At this time, there is no addition of a high-power switch (not shown), a circuit for driving the switch, a snubber or a radiation fin. In addition to being expensive, it has a large volume and mass, and there is no additional power member with a high failure rate. Therefore, it is possible to provide an LED projector that is low in cost, highly resistant to shocks and vibrations, highly portable, highly reliable and difficult to break down. . In addition, when an LED with a large rated power is adopted, the accompanying cost increase can be suppressed.

  FIG. 3 is a circuit diagram showing another circuit configuration of the power control unit 8. The analog control circuit shown in FIG. 2 may be realized by a digital control circuit. The power control unit 8 includes an adjustment unit 81 and an operation unit 82 equivalent to the circuit shown in FIG. The adjustment unit 81 includes A / D converters 812A and 813A, a subtracter 814, adders 817 and 819, a delay element 818, and multipliers 815 and 816. The A / D converter 812A is provided between the first switch 11 and the subtractor 814, and digitizes the detection signal input via the first switch 11. The sampling time of the A / D converter 812A is assumed to be Δt. The A / D converter 813A is provided between the second switch 12 and the subtractor 814, and digitizes a reference signal input via the second switch 12.

  The subtractor 814 subtracts the reference signal from the detection signal and outputs the subtracted value to the multiplier 815 and the multiplier 816. The coefficient of the multiplier 815 is P, and this P can be expressed as P = −Rf / Ri using the resistance value Rf of the resistor Rf and the resistance value Ri of the resistor Ri. The value after the multiplication process is output to an adder 819 connected to the output terminal of the multiplier 815. The coefficient of the multiplier 816 is I, and this I can be expressed as I = −Δt / Cf · Ri using the sampling time Δt, the capacitance Cf of the capacitor Cf, and the resistance value Ri of the resistor Ri. The value after the multiplication process is output to an adder 817 connected to the output terminal of the multiplier 816. The delay element 818 delays the time Δt and outputs the delayed value to the adder 817.

  The adder 817 adds the value output from the multiplier 816 and the value output from the delay element 818 and outputs the result to the adder 819. The adder 819 adds the value output from the adder 817 and the value output from the multiplier 815 and outputs the result to the operation unit 82 as an operation amount.

  The operation unit 82 includes comparators 824 and 825, a counter 826, and a flip-flop 827. A value related to the operation amount output from the adder 819 is input to the comparator 824. The counter 826 simulates a sawtooth wave oscillator 813 and counts up to 0, 1, 2,... Every clock. The value of counter 826 is output to comparators 824 and 825. The comparator 824 compares the value related to the operation amount output from the adder 819 with the value of the counter output from the counter 826. When the value of the counter 826 reaches the value related to the operation amount, the switching element In order to cause the drive circuit 23 to perform the off control of the switch 22, a falling timing signal of the PWM signal is generated, and the PWM signal is output to the third switch 13 via the flip-flop 827.

On the other hand, the value of the counter output from the counter 826 and a predetermined value based on the PWM cycle are input to the comparator 825. The comparator 825 compares the count number output from the counter 826 with a predetermined value, and when the count number reaches the predetermined value, the counter 826 is cleared to 0 and the switch 22 is turned on with respect to the switching element drive circuit 23. In order to execute the control, a rise timing signal of the PWM signal is generated, and the PWM signal is output to the third switch 13 via the flip-flop 827.
The digital control circuit shown in FIG. 3 is merely an example, and the present invention is not limited to this form. Further, at least the power control unit 8 shown in FIG. 3, and in addition to this, the first switch 11, the second switch 12, the third switch 13, the synchronization control unit 7 and the storage unit 9 shown in FIG. By further integrating into one IC, further cost reduction can be achieved. In addition to easily changing the specifications, it is also possible to reduce variations in temperature characteristics and elements. If the variation is reduced, margins such as the choke coil and the switch 22 of the DC / DC converter can be cut off, the rating can be lowered, and the volume can be reduced. Analog functional elements such as operational amplifiers are not guaranteed for transient characteristics at start-up, or may temporarily malfunction at the moment of switching input / output, making them difficult to use for applications where projector power LEDs are turned on intermittently sequentially However, in this embodiment, there is no such problem. If the storage unit 9 is composed of digital elements (ROM, DIP switch, etc.), the A / D converter 813A can be omitted.

Embodiment 2
FIG. 4 is a block diagram showing a configuration of the projector according to the second embodiment. In addition to the configuration of the first embodiment, an intensity detection circuit 90 and an auxiliary adjustment unit 91 are added. The intensity detection circuit 90 is disposed in the vicinity of the light emitting surfaces of the LED 2R, LED 2G, and LED 2B. The intensity detection circuit 90 includes an optical sensor (not shown) inside, collects light emitted from the LED 2R, LED 2G, and LED 2B, and sequentially outputs a signal based on the light emission intensity to the auxiliary adjustment unit 91.

  The signal based on the emission intensity relating to R, G, B from the intensity detection circuit 90 and the reference signal relating to R, G, B sequentially output from the storage unit 9 via the second switch 12 are the auxiliary adjustment unit. 91 is input. The auxiliary adjustment unit 91 receives the R reference signal storage unit 9R, the G reference signal storage unit 9G, and the B reference signal storage unit from the signal based on the emission intensity related to R, G, and B from the intensity detection circuit 90 via the switch 12. A reference signal related to R, G, and B sequentially output from 9B is subtracted to obtain a desired amount of electricity and output it to the power control unit 8. Since the subsequent processing is the same as that of the first embodiment, detailed description thereof is omitted.

  FIG. 5 is a circuit diagram showing circuit configurations of the auxiliary adjustment unit 91 and the power control unit 8 according to the second embodiment. In addition to the configuration of the first embodiment, a configuration using an auxiliary adjustment unit 91 realized by a digital control circuit will be described. Of course, as described above, an analog control circuit equivalent to this may be realized. The auxiliary adjustment unit 91 includes A / D converters 912 and 913, a subtracter 914, adders 917 and 919, a delay element 918, and multipliers 915 and 916. The A / D converter 912 is provided between the intensity detection circuit 90 and the subtracter 914, and digitizes a signal based on the emission intensity. The A / D converter 913 is provided between the second switch 12 and the subtracter 914, and digitizes the reference signals related to R, G, and B input via the second switch 12.

The subtracter 914 subtracts the reference signal from the signal based on the light emission intensity, and outputs the subtracted value to the multiplier 915 and the multiplier 916. The coefficient of the multiplier 915 is P ₂ , and this P ₂ is P ₂ = −Rf ₂ / Ri ₂ as in the first embodiment. Here, not necessarily P ₂ is the same value as P (hereinafter the same). The value after the multiplication processing is output to an adder 919 connected to the output terminal of the multiplier 915. Coefficient of the multiplier 916 is _{I 2,} the _{I 2} is like the first embodiment _{I 2 = -Δt 2 / Cf 2} · Ri 2. The value after the multiplication process is output to an adder 917 connected to the output terminal of the multiplier 916. Delay element 918 performs a delay of time Δt ₂ and outputs the delayed value to adder 917. The adder 917 adds the value output from the multiplier 916 and the value output from the delay element 918 and outputs the result to the adder 919. The adder 919 adds the value output from the multiplier 915 and the value output from the adder 917 and outputs the result to the adjustment unit 81. That is, a signal corresponding to a value obtained by subtracting the reference signal related to R, G, B from the signal based on the emission intensity related to R, G, B is input from the adder 919 to the subtracter 814 of the adjustment unit 81. In the subtractor 814, a process corresponding to a value obtained by subtracting the reference signal from the signal based on the light emission intensity described above is performed from the detection signal input from the first switch 11. Since the subsequent processing is the same as that of the first embodiment, detailed description thereof is omitted.

  The intensity of recombination light emission of an AlGaInP-based semiconductor often used for red LEDs greatly depends not only on the forward current but also on the temperature of the junction. Even the blue LED InGaN system does not have any dependence. The strength also changes due to aging of semiconductors and sealing resins. The intensity detection circuit 90 sequentially detects the light emission intensity of each color LED. The storage unit 9 according to the first embodiment holds a desired amount of electricity, whereas the storage unit 9 according to the second embodiment holds a desired light emission intensity. The auxiliary adjustment unit 91 supplies a reference signal (a desired amount of forward current of the LED) for driving the light emitting element so that the light emission intensity of each color matches the desired intensity input via the second switch 12. Value) is determined and updated and sent to the adjustment unit 81. Three types of electric circuits, a power supply circuit, an analog circuit, and a digital circuit, are completely different in the current that flows to the ground, the heat dissipation performance of the heat sink, and the appropriate printed circuit board material. The physical size, rating, and cost of the transistors used are also different. If the portion of FIG. 3 of the first embodiment is mounted on the same printed circuit board as the auxiliary adjustment unit 91 of FIG. 5 which is a peripheral circuit, sometimes in the same package and on the same wafer, the circuit of FIG. Cost can be reduced.

  The second embodiment has the above-described configuration, and the other configurations are the same as those of the first embodiment. Therefore, the corresponding parts are denoted by the same reference numerals and detailed description thereof is omitted.

It is a block diagram which shows the structure of the projector which concerns on this invention. It is a circuit diagram which shows the circuit structure of an electric power control part. It is a circuit diagram which shows the other circuit structure of an electric power control part. FIG. 6 is a block diagram illustrating a configuration of a projector according to a second embodiment. 6 is a circuit diagram illustrating a circuit configuration of an auxiliary adjustment unit and a power control unit according to Embodiment 2. FIG.

Explanation of symbols

1 lighting device 2 LED
3 Power supply circuit 4 DMD
DESCRIPTION OF SYMBOLS 5 Condenser lens 7 Synchronization control part 8 Power control part 9 Memory | storage part 20 Drive circuit 11 1st switch 12 2nd switch 13 3rd switch 21 Detection circuit 23 Switching element drive circuit 81 Adjustment part 82 Operation part 90 Strength detection circuit 91 Auxiliary adjustment Part

Claims (3)

In a lighting device comprising a plurality of color light emitting elements, and a plurality of drive circuits provided for each color to control lighting and power control by turning on and off the main switch of the light emitting elements,
A plurality of detection circuits for detecting the amount of electricity related to driving of the light emitting elements of each color;
A first switch for switching an input of a detection signal based on an electric quantity output from the plurality of detection circuits;
A plurality of storage units storing reference signals for each color;
A second switch for switching input of the reference signal output from the plurality of storage units;
A power control unit that outputs a power control signal based on a difference between a detection signal output via the first switch and a reference signal output via the second switch;
A third switch that switches an output destination of the power control signal output from the power control unit to any of the plurality of drive circuits;
A lighting device comprising: a synchronization control unit that controls the first to third switches for each color of the light emitting element. An intensity detection circuit for detecting the intensity of light emitted by the light emitting element;
The power control unit
Electric power based on the difference between the detection signal output via the first switch and the value obtained by subtracting the reference signal output via the second switch from the signal based on the emission intensity detected by the intensity detection circuit The lighting device according to claim 1, wherein the lighting device is configured to output a control signal.   A projector comprising the lighting device according to claim 1.

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