JP2006066188A - Pwm control for discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique which realizes a PWM control for a discharge lamp with ease. <P>SOLUTION: A waveform generator 100 generates a sinusoidal signal A1 and a sawtooth signal A2. A PWM controller 200 generates a first PWM signal A3, a mask signal A4, and a polarity signal A5 for showing the polarity of the sinusoidal signal A1 from the sinusoidal signal A1 and the sawtooth signal A2. An AND circuit 300 generates a second PWM signal A6, from the first PWM signal A3 and the mask signal A4. A polarity inverter 400 and a driving circuit 500 control a voltage for being applied to a discharge lamp 600 on the basis of the second PWM signal A6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for controlling a lighting state of a discharge lamp.

  Patent Document 1 discloses a technique for lighting a discharge lamp using a dimming circuit and a lighting circuit using a PWM signal.

JP-A-6-302387

  However, the configuration of the discharge lamp control circuit described in Patent Document 1 is complicated.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a technique for easily realizing PWM control of a discharge lamp.

In order to solve at least a part of the above problems, a discharge lamp control device according to the present invention includes:
A waveform generator for generating a reference wave signal having a waveform other than a rectangle, and a comparison wave signal having a waveform other than a rectangle having a shorter wavelength than the wavelength of the reference wave signal;
A first PWM signal generator that compares the reference wave signal and the comparison wave signal to generate a first PWM signal;
And a voltage control unit that controls a voltage applied to the discharge lamp based on the first PWM signal.

  According to the present invention, PWM control of the discharge lamp can be easily realized. For example, the discharge lamp control device of the present invention can be made into logic and can be easily made into an IC.

The voltage controller is
A dimming value setting unit for setting a dimming value for adjusting the luminance of the discharge lamp;
A second PWM signal generation unit configured to mask the first PWM signal and generate a second PWM signal based on the dimming value;
The voltage applied to the discharge lamp may be controlled based on the second PWM signal.

  According to this, since the applied voltage is controlled based on the dimming value, the dimming can be easily performed only by setting the dimming value.

  The second PWM signal generation unit may mask the first PWM signal in a symmetric time range centering on a timing at which the polarity of the reference wave signal is inverted.

  According to this, dimming with excellent power efficiency can be realized because dimming is performed by masking the first PWM signal in a period in which the luminance is not effectively increased with respect to the voltage applied to the discharge lamp.

  The reference wave signal may be a sine wave.

  According to this, since the first PWM signal becomes a signal showing a sine waveform in a simulated manner, if the voltage is controlled based on the first PWM signal, the voltage during a period in which only a small amount of current is likely to flow. It is possible to reduce power loss and improve power efficiency. With improvement in power efficiency, radiation noise can be reduced.

Furthermore, the discharge lamp control device of the present invention is:
A voltage control unit for controlling the voltage applied to the discharge lamp;
The voltage controller is
A dimming value setting unit for setting a dimming value for adjusting the luminance of the discharge lamp;
A PWM signal generation unit that generates a PWM signal by masking a predetermined signal input to the voltage control unit based on the dimming value,
The voltage applied to the discharge lamp may be controlled based on the PWM signal.

  According to the present invention, since the applied voltage is controlled by masking a predetermined signal based on the dimming value, the dimming can be easily performed only by setting the dimming value.

  The present invention can be further realized in various forms. For example, the present invention may be realized as a discharge lamp control method or an illumination device including a discharge lamp and a discharge lamp control device.

  Furthermore, the present invention may be realized as a projection type image display apparatus including a discharge lamp, a projection display unit that projects and displays an image using illumination light of the discharge lamp, and a discharge lamp control device.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid crystal projector 10 as an embodiment of a projection type image display apparatus of the present invention. The liquid crystal projector 10 includes a receiver 20, an image processing unit 30, a liquid crystal panel driving unit 40, a liquid crystal panel 50, a projection optical system 60 for projecting transmitted light that has passed through the liquid crystal panel 50 onto the screen SC, CPU700. The liquid crystal projector 10 further includes a discharge lamp 600 for illuminating the liquid crystal panel 50 and a discharge lamp control unit 1000 for controlling the discharge lamp 600. In this embodiment, the discharge lamp 600 is a high-pressure mercury lamp using arc discharge. As the discharge lamp 600, other discharge lamps such as a metal halide lamp and a xenon lamp may be used.

  The receiver 20 receives an image signal VS supplied from a personal computer (not shown) and converts the image signal into a format that can be processed by the image processing unit 30. The image processing unit 30 performs various image processing such as brightness adjustment and color balance adjustment on the image data input via the receiver 20. The liquid crystal panel drive unit 40 generates a drive signal for driving the liquid crystal panel 50 based on the image data subjected to the image processing in the image processing unit 30. The liquid crystal panel 50 modulates illumination light according to the drive signal generated by the liquid crystal panel drive unit 40. The projection optical system 60 includes a projection lens having a zoom function (not shown), and changes the zoom ratio of the projection lens and changes the focal length, thereby changing the size of the projected image while maintaining the focus. Let The liquid crystal panel drive unit 40, the liquid crystal panel 50, the projection optical system 60, and the screen SC correspond to the projection display unit of the present invention that projects and displays an image using the illumination light of the discharge lamp 600.

  The CPU 700 controls the image processing unit 30 and the projection optical system 60 according to an operation of a remote controller (not shown) or an operation button provided on the liquid crystal projector 10 main body. Further, the CPU 700 has a function of setting a dimming value used by the discharge lamp control unit 1000. The dimming value will be described later. The discharge lamp control unit 1000 and the CPU 700 correspond to the discharge lamp control device of the present invention.

  FIG. 2 is a block diagram of the discharge lamp control unit 1000. The discharge lamp control unit 1000 includes a waveform generation unit 100, a PWM control unit 200, an AND circuit 300, a polarity conversion unit 400, and a drive circuit unit 500. Hereinafter, the function of each block will be described with reference to FIGS.

  3 and 4 are timing charts showing signal waveforms of the signals A1 to A9. FIG. 3 is a timing chart when the light is adjusted to be “brightly lit”, and FIG. 4 is a timing chart when the light is adjusted to be “darkly lit”. “Bright lighting” is a relatively bright lighting, and “dark lighting” is a relatively dark lighting.

  The waveform generating unit 100 generates a sine wave signal A1 and a sawtooth wave signal A2 based on parameters set by the CPU 700. The PWM control unit 200 generates a first PWM signal A3, a mask signal A4, and a signal A5 indicating the polarity of the sine wave signal A1 (hereinafter referred to as a polarity signal A5) from the sine wave signal A1 and the sawtooth wave signal A2. To do. The difference in the waveform of the mask signal A4 in FIG. 3 and FIG. 4 is based on the difference in the light control value set by the CPU 700, which will be described in detail later. The AND circuit 300 generates a second PWM signal A6 from the first PWM signal A3 and the mask signal A4. The difference in waveform of the second PWM signal A6 in FIGS. 3 and 4 is based on the difference in the mask signal A4. The polarity converter 400 converts the polarity of the second PWM signal A6 based on the polarity signal A5, and generates a first drive signal A7 and a second drive signal A8. The drive circuit unit 500 applies a voltage corresponding to the applied signal A9 to the discharge lamp 600 based on the first drive signal A7 and the second drive signal A8. The waveforms of the discharge lamp voltages V2 and V3 in FIGS. 3 and 4 are waveforms that simulate the voltages actually applied to the discharge lamp 600 when a voltage corresponding to the applied voltage A9 is applied to the discharge lamp 600, respectively. It is.

  The waveform generation unit 100, the PWM control unit 200, the AND circuit 300, the polarity conversion unit 400, and the drive circuit unit 500 will be described in detail below.

  FIG. 5 is a block diagram of the waveform generator 100. The waveform generation unit 100 includes a frequency generation unit 110, a counter unit 120, a sine wave table unit 140, a sawtooth wave table unit 150, and a counter unit 160.

  FIG. 6 is a block diagram of the frequency generator 110 in the waveform generator 100. The frequency generator 110 includes an oscillator (OSC) 111, an M divider 112, a phase comparator 113, a low pass filter (LPF) 114, a voltage controlled oscillator (VCO) 115, an X divider 116, N frequency divider 117.

The OSC ₁₁₁ generates a rectangular wave signal S ₁₁₁ having a predetermined frequency fosc. The M divider 112 _divides the frequency of the rectangular wave signal S ₁₁₁ by 1 / M. The output signal S ₁₁₂ of the M divider ₁₁₂ is input to the phase comparator 113 together with the output signal S ₁₁₇ of the N divider 117. The phase comparison unit 113, the LPF 114, the VCO 115, and the N dividing unit 117 constitute a PLL (Phase Locked Loop) circuit. That is, the phase comparator 113, the LPF 114, the VCO 115, and the N divider 117 output from the VCO 115 so that the frequencies of the two signals S ₁₁₂ and S ₁₁₇ input to the phase comparator 113 are the same. And the function of adjusting the frequency of the signal S ₁₁₅ to be transmitted. Specifically, the frequency ft of the output signal S ₁₁₅ of the VCO ₁₁₅ is given by the following equation (1).
ft = fosc * N / M (1)

The X divider 116 divides the output of the VCO 115 by 1 / X and outputs a rectangular wave signal S ₁₁₆ having a frequency fsin given by the following equation (2).
fsin = fosc * N / (M * X) (2)
The CPU 700 can adjust the frequency ft and the frequency fsin by appropriately changing the parameters M, N, and X.

Returning to FIG. 5 again, the waveform generator 100 will be described. A rectangular wave signal _{S 116} of the frequency fsin frequency generating unit 110 outputs a rectangular wave signal _{S 115} of the frequency ft is input to each counter 120 and the counter 160. The counter unit 120 counts the number of pulses of the rectangular wave signal S ₁₁₆ up to the Max value, and restarts counting from the initial value when the Max value is reached. The sine wave table unit 140 outputs data A1 corresponding to the value counted by the counter unit 120. 3 and 4, the horizontal axis corresponds to the value counted by the counter unit 120, and the vertical axis corresponds to the data output from the sine wave table unit 140. Thus, the counter unit 120 and the sine wave table 140, based on the square wave signal _{S 116,} and outputs a sine wave signal A1. As shown in FIGS. 3 and 4, the sine wave signal A1 varies between the GND point and the VDD point. The data value at the GND point is expressed by “0” in the 8-bit signal, and the data value at the VDD point is expressed by “255” in the 8-bit signal. The “hysteresis upper limit value” and “hysteresis lower limit value” in FIGS. 3 and 4 will be described later.

Counter 160 and the sawtooth wave table section 150 is likewise based on the square wave signal _{S 115} of the frequency ft, and outputs the sawtooth signal A2. The sine wave signal A1 in FIGS. 3 and 4 has a waveform other than a rectangle and corresponds to the reference wave signal of the present invention. The sawtooth wave signal A2 in FIGS. 3 and 4 has a shorter wavelength than the wavelength of the sine wave signal A1, has a waveform other than a rectangle, and corresponds to the comparison wave signal of the present invention.

  The CPU 700 can adjust the waveforms of the sine wave signal A1 and the sawtooth wave signal A2 by appropriately changing the Max value, the initial values of the counter unit 120 and the counter unit 160, and the like. As shown in FIG. 2, the sine wave signal A <b> 1 and the sawtooth wave signal A <b> 2 output from the waveform generator 100 are input to the PWM controller 200.

  FIG. 7 is a block diagram of the PWM control unit 200. The PWM control unit 200 includes a PWM comparison unit 210, a mask signal generation unit 220, and a polarity signal generation unit 230. The PWM comparison unit 210 generates the first PWM signal A3 by comparing the sine wave signal A1 and the sawtooth wave signal A2. The PWM comparison unit 210 corresponds to the first PWM signal generation unit in the present invention.

  The mask signal generation unit 220 inputs the sine wave signal A1 and a dimming value for adjusting the luminance of the discharge lamp 600, and outputs a mask signal A4. FIG. 8 is an explanatory diagram showing the internal configuration of the mask signal generation unit 220. “Hysteresis upper limit value” and “hysteresis lower limit value” in FIG. 8 correspond to “light control value”. As also shown in the lower part of FIG. 8, the hysteresis upper limit value and the hysteresis lower limit value are set to the same value as the difference between the values corresponding to VDD / 2 (128 for an 8-bit signal).

  The mask signal generation unit 220 includes two operational amplifiers OP 1 and OP 2 and an OR circuit 221. The first operational amplifier OP1 generates a first mask signal TP from the sine wave signal A1 and the hysteresis upper limit value. As shown in the lower part of FIG. 8, the mask signal TP is a signal that is at the H level in the time range in which the sine wave signal A1 is equal to or higher than the hysteresis upper limit value, and is at the L level in the other time ranges. The second operational amplifier OP2 generates the second mask signal BT from the sine wave signal A1 and the hysteresis lower limit value. As shown in the lower part of FIG. 8, this mask signal BT is a signal that is at the H level in the temporal range where the sine wave signal A1 is equal to or lower than the hysteresis lower limit value, and is at the L level in the other temporal ranges. . The OR circuit 221 generates a mask signal A4 from the two mask signals TP and BT. As shown in the lower part of FIG. 8, the mask signal A4 becomes H level in a temporal range in which the sine wave signal A1 is equal to or higher than the hysteresis upper limit value and in a temporal range in which the sine wave signal A1 is equal to or lower than the hysteresis lower limit value. These signals are L level in other time ranges.

  As can be seen from the above generation process of the mask signal A4, if the hysteresis upper limit value is increased, the time range of the H level of the signal TP is narrowed, and if the hysteresis upper limit value is decreased, the time of the H level of the signal TP is decreased. Since the target range becomes wide, the mask signal A4 can be adjusted by changing the hysteresis upper limit value. The same applies to the lower limit of hysteresis. As will be described in detail later, the mask signal A4 is a signal for adjusting the luminance of the discharge lamp 600, and the luminance of the discharge lamp 600 increases as the mask signal A4 is a signal in the H level over a wide range. Therefore, the CPU 700 corresponds to a dimming value setting unit of the present invention that adjusts the luminance of the discharge lamp 600 by setting a hysteresis upper limit value and a hysteresis lower limit value that are dimming values.

  Specifically, the CPU 700 sets the hysteresis upper limit value to a smaller value and sets the hysteresis lower limit value to a larger value when bright lighting is performed as shown in FIG. Thus, the mask signal A4 at the time of bright lighting becomes an H level signal in a wide time range as shown in FIG. On the other hand, when dark lighting is performed as shown in FIG. 4, the CPU 700 sets the hysteresis upper limit value larger and the hysteresis lower limit value smaller. Thereby, the mask signal A4 at the time of dark lighting becomes an H level signal in a narrow time range as shown in FIG. In this embodiment, the hysteresis lower limit value is given by (255−hysteresis upper limit value), but the hysteresis upper limit value and the hysteresis lower limit value may be set independently.

  Returning again to FIG. The polarity signal generation unit 230 of the PWM control unit 200 has an H level in which the sine wave signal A1 is in the positive time range (phase is in the range of 0 to π) and the sine wave signal A1 is in the negative time range (in which the phase is A polarity signal A5 that is L level in the range of π to 2π is generated from the sine wave signal A1. As described above, the PWM control unit 200 outputs the first PWM signal A3, the mask signal A4, and the polarity signal A5.

  Returning to FIG. The first PWM signal A3 and the mask signal A4 output from the PWM control unit 200 are input to the AND circuit 300. The AND circuit 300 generates and outputs a second PWM signal A6 from the first PWM signal A3 and the mask signal A4. As can be seen from the waveform of the second PWM signal A6 in FIG. 3 and FIG. 4, the mask signal A4 can be considered as a signal that outputs the first PWM signal A3 as it is when it is in the H level range. Can be considered as a signal for setting the first PWM signal A3 to 0 in the range of L level. Therefore, the signal A4 is called a “mask signal”. It may be called “permission signal”. Since the mask signal generation unit 220 and the AND circuit 300 generate the second PWM signal A6 by masking the first PWM signal A3 based on the dimming value, the second PWM signal of the present invention is generated. It corresponds to a generation unit or a PWM signal generation unit.

  The polarity converter 400 receives the second PWM signal A6 and the polarity signal A5, and outputs the first and second drive signals A7 and A8. The first drive signal A7 is a signal obtained by outputting the second PWM signal A6 in a range where the polarity signal A5 is at the H level (see FIGS. 3 and 4). On the other hand, the second drive signal A8 is a signal output by reversing the polarity of the second PWM signal A6 in the range where the polarity signal A5 is at the L level (see FIGS. 3 and 4).

  The drive circuit unit 500 amplifies the two drive signals A7 and A8 and supplies them to the discharge lamp 600. FIG. 9 is an explanatory diagram showing the drive circuit unit 500 and the discharge lamp 600. The drive circuit unit 500 includes a level shifter 510 that amplifies two drive signals A7 and A8, and an H-type bridge circuit that includes four transistors T1 to T4. The amplified first drive signal A7 is applied to the gates of the transistors T1 and T4, and the second drive signal A8 is applied to the gates of the transistors T2 and T3. At this time, the voltage applied to the transistors T1 to T4 is shown in the lower timing chart of FIG. When the first drive signal A7 is applied to the discharge lamp 600, a current I1 flows through the discharge lamp 600, and when the second drive signal A8 is applied, a reverse current I2 flows. Since the first drive signal A7 and the second drive signal A8 apply opposite voltages to the discharge lamp 600, the discharge lamp 600 has a voltage corresponding to the applied signal A9 in FIGS. Is applied. The polarity conversion unit 400 and the drive circuit unit 500 together correspond to the voltage control unit of the present invention.

  As can be seen from the discharge lamp voltages V2 and V3 in FIGS. 3 and 4, the longer the period of time at which the mask signal A4 is at the H level, the longer the time for applying the voltage to the discharge lamp 600. growing. That is, as described above, the mask signal A4 is a signal for adjusting the luminance of the discharge lamp 600, and the luminance of the discharge lamp 600 increases as the mask signal A4 is a signal in a wide range and at an H level. .

  FIG. 3 shows a discharge lamp when the hysteresis upper limit value and the hysteresis lower limit value are both values corresponding to VDD / 2 points (128 for an 8-bit signal), that is, when the mask signal A4 is always at the H level. The voltage V1 is also shown. When the discharge lamp voltage is V1, the discharge lamp 600 has the brightest maximum lighting. When dimming is not performed, the hysteresis upper limit value and the hysteresis lower limit value are both values corresponding to VDD / 2 points.

  FIG. 10 is an explanatory diagram illustrating an example of dimming adjustment by the discharge lamp control unit 1000 and the CPU 700. The horizontal axis represents the hysteresis upper limit value, and the vertical axis represents the luminance [lm]. As described above, when the hysteresis upper limit value is decreased (when the hysteresis lower limit value is increased), the luminance is increased, and when the hysteresis upper limit value is increased (when the hysteresis lower limit value is decreased), the luminance is decreased. When the hysteresis upper limit value and the hysteresis lower limit value are both values corresponding to VDD / 2 points (128 for an 8-bit signal), the luminance is the maximum Lmax.

  Thus, according to the present embodiment, PWM control of the discharge lamp 600 can be easily realized. The discharge lamp control unit 1000 has a logic circuit configuration and can be easily integrated.

  Furthermore, in the discharge lamp control unit 1000 and the CPU 700 of the present embodiment, the luminance can be adjusted simply by setting the hysteresis upper limit value and the hysteresis lower limit value, and dimming is easy.

  Further, as can be seen from the lower diagram of FIG. 8, the H level period of the signal TP has a symmetric shape centered on the timing at which the sine wave signal A1 exhibits a maximum value. Similarly, the H level period of the signal BT has a symmetrical shape with the timing at which the sine wave signal A1 exhibits a minimum value as the center. As described above, the period in which the mask signal A4 including the signal TP and the signal BT is at the H level is centered on the timing at which the sine wave signal A1 shows the peak value, as can be understood by comparing FIG. 3 and FIG. It has a symmetrical shape. In other words, the mask period of the first PWM signal A3 is set such that the first PWM signal A3 is masked in a symmetric time range centered on the timing at which the polarity of the sine wave signal A1 is inverted. It is also possible to think that That is, the liquid crystal projector 10 according to the present embodiment performs light control by masking the first PWM signal A3 in a period in which the luminance is not effectively increased with respect to the voltage to which the discharge lamp 600 is applied. Excellent light control can be realized.

Other examples:
(1) In the above embodiment, the reference wave signal of the present invention is a sine wave signal, but the reference wave signal may be a signal having a waveform other than a rectangle other than a sine wave signal. For example, a triangular wave signal or a sawtooth wave signal may be used. However, in the case of a sine wave, it is possible to reduce voltage loss while only a small amount of current is flowing and to improve power efficiency, and there is an advantage that radiation noise can be reduced as power efficiency is improved. As a result, countermeasure parts can be reduced. In the above embodiment, the reference wave signal of the present invention is generated by the counter unit 120 and the sine wave table unit 140, but is not generated by the counter unit 120 and the sine wave table unit 140. It may be generated by duty control using a signal. In the above-described embodiment, the comparison wave signal of the present invention is a sawtooth wave signal. However, the comparison wave signal has a waveform other than a rectangular wave having a wavelength shorter than that of the sine wave signal A1, even if it is not a sawtooth wave signal. Any signal may be used. For example, a triangular wave signal may be used.

(2) In the above embodiment, the mask period of the first PWM signal A3 is such that the first PWM signal A3 is masked in a symmetrical time range centering on the timing at which the polarity of the discharge lamp voltage is inverted. However, the mask period is not limited to this, and dimming may be performed by masking an arbitrary period of the first PWM signal A3.

(3) In the mask signal generation unit 220 and the AND circuit 300 of the above embodiment, the first PWM signal A3 is set to be masked, but the masked signal is not limited to this, and the reference wave signal Dimming may be performed by masking a signal serving as a reference for the voltage applied to A1 and other discharge lamps. In that case, it is desirable to convert the signal generated by masking into a PWM signal.

(4) In the above embodiment, the mask signal generation unit 220 as the second PWM signal generation unit in the present invention and the AND circuit 300 are provided, and the CPU 700 as the dimming value setting unit sets the hysteresis upper limit value and the hysteresis lower limit value. However, these are not always necessary, and the light may not be adjusted. In this case, the discharge lamp control unit 1000 inputs the first PWM signal A3 directly to the polarity conversion unit 400.

(5) In the above embodiment, the liquid crystal projector 10 has been described as the projection type image display device. However, the projection type image display device is not limited to this, and a projection type image display device of DLP (registered trademark of Texas Instruments Inc.) system. It may be. The present invention can also be configured as a lighting device. FIG. 11 is an explanatory diagram showing an in-vehicle illumination device as an example of the illumination device. The in-vehicle illumination device includes a headlamp 600A as an example of a discharge lamp and a headlamp control unit 1000A. The headlamp control unit 1000A includes a waveform generation unit 100A, a PWM comparison unit 210A, and a voltage control unit 450A. The waveform generator 100A and the PWM comparator 210A have the same functions as the waveform generator 100 and the PWM comparator 210 described in the above embodiments, respectively. The voltage control unit 450A has the same functions as the polarity conversion unit 400 and the drive circuit unit 500 described in the above embodiments. The headlamp control unit 1000A may further have the same configuration as the discharge lamp control unit 1000 of the above embodiment, such as including a mask signal generation unit 220. The in-vehicle illumination device may further include a dimming value setting unit having the same function as the CPU 700. The lighting device is not limited to the in-vehicle lighting device, and may be used for various purposes.

  As described above, the discharge lamp control device, the discharge lamp control method, the projection type image display device, and the illumination device according to the present invention have been described based on the embodiments. However, the embodiment of the present invention described above makes it easy to understand the present invention. The present invention is not intended to limit the present invention. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

2 is an explanatory diagram illustrating a schematic configuration of a liquid crystal projector. FIG. The block diagram of the discharge lamp control part 1000. FIG. The timing chart which shows the signal waveform of the signal A1-signal A9 at the time of adjusting light so that it may become "bright lighting." The timing chart which shows the signal waveform of the signal A1-signal A9 at the time of adjusting light so that it may become "dark lighting." The block diagram of the waveform generation part 100. FIG. The block diagram of the frequency generation part 110. FIG. The block diagram of the PWM control part 200. FIG. 4 is an explanatory diagram showing an internal configuration of a mask signal generation unit 220. FIG. FIG. 3 is an explanatory diagram showing a drive circuit unit 500 and a discharge lamp 600. Explanatory drawing which shows the dimming adjustment example by the discharge lamp control part 1000 and CPU700. Explanatory drawing which shows the vehicle-mounted illuminating device as an example of an illuminating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal projector 20 ... Receiver 30 ... Image processing part 40 ... Liquid crystal panel drive part 50 ... Liquid crystal panel 60 ... Projection optical system 100,100A ... Waveform generation part 110. .. Frequency generator 111 ... OSC
112 ... M frequency divider 113 ... Phase comparator 114 ... LPF
115 ... VCO
116 ... X frequency dividing unit 117 ... N frequency dividing unit 120 ... Counter unit 140 ... Sine wave table unit 150 ... Sawtooth wave table unit 160 ... Counter unit 200 ... PWM control Unit 210 ... PWM comparison unit 220 ... mask signal generation unit 221 ... OR circuit 230 ... polarity signal generation unit 300 ... AND circuit 400 ... polarity conversion unit 450A ... voltage control unit 500 ... Drive circuit unit 510 ... Level shifter 600 ... Discharge lamp 600A ... Head lamp 1000 ... Discharge lamp control unit 1000A ... Head lamp control unit OP1, OP2 ... Operational amplifiers V1, V2 ... Discharge lamp voltage T1-T4 ... Transistor SC ... Screen

Claims (8)

A discharge lamp control device comprising:
A waveform generator for generating a reference wave signal having a waveform other than a rectangle, and a comparison wave signal having a waveform other than a rectangle whose wavelength is shorter than the wavelength of the reference wave signal;
A first PWM signal generator that compares the reference wave signal and the comparison wave signal to generate a first PWM signal;
A discharge lamp control device comprising: a voltage control unit that controls a voltage applied to the discharge lamp based on the first PWM signal. The discharge lamp control device according to claim 1,
The voltage controller is
A dimming value setting unit for setting a dimming value for adjusting the luminance of the discharge lamp;
A second PWM signal generation unit configured to mask the first PWM signal and generate a second PWM signal based on the dimming value;
A discharge lamp control device that controls a voltage applied to the discharge lamp based on the second PWM signal. The discharge lamp control device according to claim 2,
The second PWM signal generator is a discharge lamp control device that masks the first PWM signal in a symmetrical time range centered on a timing at which the polarity of the reference wave signal is inverted. The discharge lamp control device according to claim 1, wherein
The discharge lamp control device according to claim 1, wherein the reference wave signal is a sine wave. A discharge lamp control device comprising:
A voltage control unit for controlling the voltage applied to the discharge lamp;
The voltage controller is
A dimming value setting unit for setting a dimming value for adjusting the luminance of the discharge lamp;
A PWM signal generation unit that generates a PWM signal by masking a predetermined signal input to the voltage control unit based on the dimming value,
A discharge lamp control device that controls a voltage applied to the discharge lamp based on the PWM signal. A discharge lamp control method comprising:
A waveform generation step for generating a reference wave signal having a waveform other than a rectangle, and a comparison wave signal having a waveform other than a rectangle having a shorter wavelength than the wavelength of the reference wave signal;
A first PWM signal generation step of generating a first PWM signal by comparing the reference wave signal and the comparison wave signal;
A discharge lamp control method comprising: a voltage control step of controlling a voltage applied to the discharge lamp based on the first PWM signal. A lighting device,
A discharge lamp;
A discharge lamp control device for controlling the discharge lamp,
The discharge lamp control device comprises:
A waveform generator for generating a reference wave signal having a waveform other than a rectangle, and a comparison wave signal having a waveform other than a rectangle having a shorter wavelength than the wavelength of the reference wave signal;
A first PWM signal generator that compares the reference wave signal and the comparison wave signal to generate a first PWM signal;
A voltage control unit that controls a voltage applied to the discharge lamp based on the first PWM signal. A projection-type image display device,
A discharge lamp;
A projection display unit for projecting and displaying an image using illumination light of the discharge lamp;
A discharge lamp control device for controlling the discharge lamp,
The discharge lamp control device comprises:
A waveform generator for generating a reference wave signal having a waveform other than a rectangle, and a comparison wave signal having a waveform other than a rectangle whose wavelength is shorter than the wavelength of the reference wave signal;
A first PWM signal generation unit that compares the reference wave signal and the comparison wave signal to generate a first PWM signal;
A projection-type image display device comprising: a voltage control unit that controls a voltage applied to the discharge lamp based on the first PWM signal.

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