JP2009134983A - Discharge lamp lighting device and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid a temperature rise when a voltage drops. <P>SOLUTION: A discharge lamp lighting device 10 to light a discharge lamp 20 includes a power supply circuit 100 to convert an ac voltage AC supplied from the outside to a dc voltage DC, a rectifier 110 to output a rectified voltage RV obtained by rectifying the ac voltage AC, a comparator 120 to output a comparison pulse obtained by comparing the rectified voltage RV with a grounding potential GND, a pulse width monitoring part 130 to output monitored results PW by monitoring whether the width of the comparison pulse output from the comparator 120 is not less than a prescribed width, and a power control circuit 140 to control power supplied to the discharge lamp 20 from a DC/DC converter 150 based on the monitored results. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device and a projector for lighting a discharge lamp.

  Projection type display devices such as projectors and rear projection televisions that use a discharge lamp point as a light source modulate a light beam emitted from the discharge lamp into an optical image by a light modulation element and project an image on a screen. The discharge lamp lighting device used for such a projection display device controls the driving power supplied to the discharge lamp to be constant in order to light the discharge lamp stably. However, if the supply of commercial power is cut off due to a power failure or the like, the charge operation charging the capacitor of the power supply circuit is stopped.

  In order to solve this problem, for example, in Patent Document 1, the input voltage is monitored, and when the voltage drops below a predetermined voltage value, the current output from the power supply is reduced to supply power even when the commercial power supply is momentarily interrupted. An uninterruptible power supply is described.

JP 2004-303507 A

  However, the conventional method has a problem that if the low input voltage state continues, the power conversion efficiency of the power supply circuit decreases and the temperature of the power supply component rises. In addition, there is a problem in that the lamp flickers and the operation of the device is unstable, giving the user the impression of a malfunction.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A discharge lamp lighting device for lighting a discharge lamp, a rectifier that rectifies an AC voltage supplied from the outside, a comparator that outputs a result of comparing an output voltage of the rectifier and a ground potential, and the AC voltage A power supply circuit that converts and outputs a DC voltage of a predetermined voltage, a DC / DC converter that converts the DC voltage into driving power for the discharge lamp, and the discharge from the DC / DC converter based on the output of the comparator. A discharge lamp lighting device comprising: a power control circuit that controls power supplied to the lamp.

  According to this configuration, by reducing the power supplied to the discharge lamp when the AC voltage supplied from the outside decreases, the amount of current flowing through the power supply component can be reduced, and the temperature rise of the power supply component can be suppressed.

[Application Example 2]
In the above discharge lamp lighting device, the comparator may have a hysteresis function.

  According to this configuration, since the comparison pulse can be stabilized by using a comparator having a hysteresis function when fluctuation of the AC voltage supplied from the outside continues, flickering of the discharge lamp can be prevented. .

[Application Example 3]
In the above discharge lamp lighting device, the comparator may have a latch function.

  According to this configuration, since the comparison pulse can be stabilized by using a comparator having a latch function when the fluctuation of the AC voltage supplied from the outside continues, flickering of the discharge lamp can be prevented. .

[Application Example 4]
In the above discharge lamp lighting device, the discharge lamp lighting device may further include a display unit that displays a status based on an output of the comparator.

  According to this configuration, it is possible to inform the user that the power supplied to the discharge lamp is reduced when the AC voltage supplied from the outside decreases.

[Application Example 5]
A projector comprising a discharge lamp and the discharge lamp lighting device described above.

  According to this configuration, since the power supplied to the discharge lamp is reduced when the AC voltage supplied from the outside is reduced, heat generation of the power supply circuit when the power supply voltage is reduced and the lamp is turned off at the time of a momentary interruption can be prevented. A projector that operates stably can be provided.

  Hereinafter, embodiments of a discharge lamp lighting device and a projector will be described with reference to the drawings.

(First embodiment)
<Configuration of projector>
FIG. 1 is a block diagram showing a schematic configuration of the discharge lamp lighting device 10 and the projector 1. As shown in FIG. 1, the projector 1 includes an image projection unit 2 that projects an image, a control unit 4, an operation unit 6, an image processing unit 8, and a discharge lamp lighting device 10. .

  First, the image projection unit 2 will be described. The image projection unit 2 includes a discharge lamp 20, three liquid crystal light valves 240R, 240G, and 240B, a projection lens 26, a light valve driving unit 22, and the like.

  FIG. 2 is a configuration diagram showing the configuration of the image projection unit 2 in more detail, and shows an optical path from the light emitted from the discharge lamp 20 to the screen SC.

  As shown in FIG. 2, the image projection unit 2 includes an illumination optical system 23, a color light separation optical system 25, a relay optical system 27, three liquid crystal light valves 240R, 240G, and 240B as light modulation devices, and a cross A dichroic prism 29 and a projection lens 26 are provided.

  The illumination optical system 23 includes, as a light source, a discharge lamp 20 that is a discharge type light source lamp such as an ultra-high pressure mercury lamp or a metal halide lamp, a first lens array 230, a second lens array 232, a polarization conversion element 234, And a superimposing lens 236. The light bundle emitted from the discharge lamp 20 is divided into a large number of minute light bundles by the first lens array 230 in which minute lenses 230a are arranged in a matrix. The second lens array 232 and the superimposing lens 236 are provided such that each of the divided light bundles irradiates the entire three liquid crystal light valves 240R, 240G, and 240B that are illumination targets. For this reason, the light beams are superimposed by the liquid crystal light valves 240R, 240G, and 240B, and the entire liquid crystal light valves 240R, 240G, and 240B are illuminated almost uniformly.

  The polarization conversion element 234 has a function of aligning polarized light having a specific polarization direction so that the light from the discharge lamp 20 can be efficiently used by the liquid crystal light valves 240R, 240G, and 240B. The polarized light emitted from the illumination optical system 23 enters the color light separation optical system 25.

  The color light separation optical system 25 includes a first dichroic mirror 250, a first reflection mirror 252, and a second dichroic mirror 254. The light emitted from the illumination optical system 23 has a different wavelength range. Separate into three colors of light. The first dichroic mirror 250 transmits substantially red light and reflects light having a shorter wavelength than the transmitted light. The red light R that has passed through the first dichroic mirror 250 is reflected by the first reflecting mirror 252 and illuminates the liquid crystal light valve 240R for red light.

  Of the light reflected by the first dichroic mirror 250, the green light G is reflected by the second dichroic mirror 254 and illuminates the liquid crystal light valve 240G for green light. Further, the blue light B passes through the second dichroic mirror 254, passes through the relay optical system 27, and illuminates the liquid crystal light valve 240B for blue light.

  Since the path of the blue light B is longer than the paths of the other color lights, the blue light B is used to prevent the illumination efficiency to the liquid crystal light valve 240B from being reduced due to the divergence of the light beam. A relay optical system 27 is provided in the path. The relay optical system 27 includes an incident side lens 270, a second reflection mirror 272, a relay lens 274, a third reflection mirror 276, and an emission side lens 278. The blue light B emitted from the color light separation optical system 25 is converged in the vicinity of the relay lens 274 by the incident side lens 270 and diverges toward the emission side lens 278.

  Each of the liquid crystal light valves 240R, 240G, and 240B includes a liquid crystal panel 241 in which liquid crystal is sealed between a pair of transparent substrates, and an incident side polarizing plate is provided on each of an incident side surface and an emission side surface of the liquid crystal panel 241. 242 and an exit side polarizing plate 243 are attached. The incident-side polarizing plate 242 and the exit-side polarizing plate 243 can each transmit only polarized light having a specific polarization direction, and the incident-side polarizing plate 242 transmits polarized light having the polarization direction aligned by the polarization conversion element 234. It is possible. For this reason, most of each color light incident on each of the liquid crystal light valves 240R, 240G, and 240B is transmitted through the incident-side polarizing plate 242 and incident on the liquid crystal panel 241.

  On a transparent substrate (not shown) constituting the liquid crystal panel 241, a data line driving circuit 220 and a scanning line driving circuit 222 constituting the light valve driving unit 22 (see FIG. 1) are formed. The scanning line driving circuit 222 is connected to scanning lines Y1 to Yn (not shown) formed on the transparent substrate, and sequentially selects one scanning line from among the plurality of scanning lines Y1 to Yn. The data line driving circuit 220 is connected to data lines X1 to Xm (not shown) formed on the transparent substrate, and supplies signals corresponding to image data to the data lines X1 to Xm. When the data line driving circuit 220 supplies a signal corresponding to image data to each of the data lines X1 to Xm while the scanning line driving circuit 222 selects one scanning line, the selected pixel (selected scanning) is selected. A driving voltage is applied to a horizontal row of pixels connected to the line), and this is repeated for all the scanning lines Y1 to Yn, so that the voltage corresponding to the image data is time-divided for all the pixels on the liquid crystal panel. And an optical image for one screen (one frame) is formed.

  Returning to FIG. 2, the optical image composed of each color light emitted from the liquid crystal light valves 240R, 240G, and 240B enters the cross dichroic prism 29. The cross dichroic prism 29 combines the optical images of the respective colors emitted from the liquid crystal light valves 240R, 240G, and 240B for each pixel to form an optical image representing a color image. The optical image synthesized by the cross dichroic prism 29 is enlarged and projected on the screen SC by the projection lens 26 and displayed as an image.

  Returning to FIG. 1, the control unit 4 includes a CPU (Central Processing Unit) 40, a ROM 42 as a nonvolatile storage unit including a flash ROM (Read Only Memory), and a RAM (Random) used for temporary storage of various data. Access Memory) 44, other electric circuits, and the like, and the CPU 40 operates in accordance with a control program stored in the ROM 42, thereby performing overall control of the operation of the projector 1.

  An operation panel 64 and a remote control 60 that constitute the operation unit 6 are for giving various instructions to the projector 1. When the user operates the operation panel 64, the operation panel 64 corresponds to the operation content of the user. An operation signal is output to the control unit 4. Further, when the user operates the remote controller 60, the remote controller 60 generates an infrared operation signal corresponding to the user's operation content, and the remote control signal receiving unit 62 receives this and transmits it to the control unit 4.

Next, the image data conversion unit 80, the image data processing unit 82, and the frame memory 84 constituting the image processing unit 8 will be described.
The image data conversion unit 80 can input image data of various formats from an external image supply device (an image reproduction device, a personal computer, etc.) (not shown), and the input image data is input according to an instruction from the control unit 4. The image data is converted into image data in a format that can be processed by the image data processing unit 82 and output to the image data processing unit 82.

  The image data processing unit 82 can sequentially store (store) input image data in the frame memory 84 and read out the stored image data. Further, according to the instruction of the control unit 4, various kinds of resolution conversion, brightness adjustment, contrast adjustment, sharpness adjustment, etc., for adjusting the resolution to the resolution (number of pixels) of the liquid crystal light valves 240R, 240G, 240B with respect to the read image data Image quality adjustment or processing for synthesizing OSD (on-screen display) images such as menus and messages is performed, and the processed image data is output to the light valve drive unit 22. The light valve driving unit 22 drives the liquid crystal light valves 240R, 240G, and 240B based on the image data input from the image processing unit 8, and modulates the light beam emitted from the discharge lamp 20 into image light.

<Configuration of discharge lamp lighting device>
Next, the configuration of the discharge lamp lighting device according to the first embodiment will be described with reference to FIG. FIG. 3 is a circuit diagram showing a configuration of the discharge lamp lighting device according to the first embodiment.

  As shown in FIG. 3, the discharge lamp lighting device 10 includes a power supply circuit 100, a diode 110 as a rectifier, a hysteresis comparator 120 as a comparator, a pulse width monitoring unit 130, a power control circuit 140, a DC / DC A DC converter 150, an inverter circuit 160, an igniter circuit 170, and a display unit 180 are included.

  The power supply circuit 100 converts the AC voltage AC supplied from the commercial power supply 1000 into a DC voltage DC. The diode 110 outputs a rectified voltage RV obtained by half-wave rectifying the AC voltage AC. The hysteresis comparator 120 outputs a comparison pulse CP that compares the rectified voltage RV and the ground potential GND. The pulse width monitoring unit 130 monitors whether or not the width of the comparison pulse CP is equal to or greater than a predetermined width, and outputs a monitoring result PW. The power control circuit 140 controls the power DX supplied from the DC / DC converter 150 to the discharge lamp 20 based on the monitoring result PW. Inverter circuit 160 converts DC power DX output from DC / DC converter 150 into AC power AX. The igniter circuit 170 generates a pulse voltage PS for starting the discharge lamp 20 from the AC power AX. When the discharge lamp 20 is started, the igniter circuit 170 stops functioning, and the AC power AX that is the output of the inverter circuit 160 is supplied to the discharge lamp 20, so that the steady lighting state is maintained. The display unit 180 displays the situation based on the monitoring result PW.

<Operation of discharge lamp lighting device>
Next, the operation of the discharge lamp lighting device will be described with reference to FIG. FIG. 4 is a waveform diagram showing the operation of the discharge lamp lighting device.

  As shown in FIG. 4A, for example, the waveform of the AC voltage AC supplied from the commercial power supply 1000 having an effective voltage of 100 V is a sine wave having a maximum value of 100 V × √2 and a minimum value of −100 V × √2. It becomes. A rectified voltage RV obtained by half-wave rectifying the AC voltage AC with the diode 110 has a waveform of a positive portion of the sine wave of the AC voltage AC. It is assumed that the comparison pulse CP obtained by comparing the rectified voltage RV and the ground potential GND by the hysteresis comparator 120 has a pulse width of W1. For example, if the pulse width of the comparison pulse CP when the guaranteed lower limit voltage of the projector using the discharge lamp lighting device 10 is 90 V is W, W1> W. The monitoring result PW at this time is set to H level.

  Next, FIG. 4B shows the waveform of the AC voltage AC, the waveform of the rectified voltage RV, and the waveform of the comparison pulse CP when the commercial power supply 1000 drops below 90V. If the pulse width at this time is W2, W2 <W, and the monitoring result PW at this time is at the L level. When the monitoring result PW becomes L level, the power control circuit 140 reduces the power DX output from the DC / DC converter 150 to reduce the current flowing through the electronic components such as the inverter circuit 160 and the igniter circuit 170. Operate. When the commercial power supply 1000 recovers to 90 V or higher and the monitoring result PW becomes H level, the power control circuit 140 controls the DC / DC converter 150 to return the power DX to the original value.

  According to the present embodiment described above, the following effects can be obtained.

  In this embodiment, by reducing the power supplied from the power supply circuit to the discharge lamp when the AC voltage supplied from the outside decreases, the amount of current flowing through the power supply component can be reduced, and the temperature rise of the power supply component is suppressed. This can prevent the flickering of the discharge lamp.

  As mentioned above, although embodiment of the discharge lamp lighting device was described, it is not limited to such embodiment at all and can be implemented with various forms within the range which does not deviate from the meaning. Hereinafter, a modification will be described.

  (Modification 1) Modification 1 of the discharge lamp lighting device will be described. In the first embodiment, the hysteresis comparator 120 as illustrated in FIG. 3 is exemplified as the comparator. However, as illustrated in FIG. 5, the latch comparator is a comparator having a latch function in which a latch circuit is added to the output of the comparator. It may be 122.

  (Modification 2) Modification 2 of the discharge lamp lighting device will be described. The display unit 180 may light up a green lamp indicating a normal state when the monitoring result PW is at an H level, and light a red lamp indicating an abnormal state when the monitoring result PW is at an L level. Alternatively, a message such as “voltage drop” may be displayed on the screen of the projector.

  (Modification 3) Modification 3 of the discharge lamp lighting device will be described. In the first embodiment, the half-wave rectifier using the diode 110 as the rectifier has been described. However, a full-wave rectifier may be used.

1 is a block diagram showing a configuration of a projector according to a first embodiment. FIG. 3 is a diagram illustrating a configuration of an optical system of the projector according to the first embodiment. The circuit diagram which shows the structure of the discharge lamp lighting device which concerns on 1st Embodiment. The wave form diagram which shows operation | movement of a discharge lamp lighting device. FIG. 9 is a circuit diagram showing a configuration of a comparator according to Modification 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Projector, 10 ... Discharge lamp lighting device, 20 ... Discharge lamp, 100 ... Power supply circuit, 110 ... Diode, 120 ... Hysteresis comparator, 122 ... Latch comparator, 130 ... Pulse width monitoring part, 140 ... Power control circuit, 150 ... DC / DC converter, 160 ... inverter circuit, 170 ... igniter circuit, 180 ... display unit, 1000 ... commercial power supply.

Claims (5)

A discharge lamp lighting device for lighting a discharge lamp,
A rectifier for rectifying an AC voltage supplied from the outside;
A comparator that outputs a result of comparing the output voltage of the rectifier and the ground potential;
A power supply circuit that converts the AC voltage into a DC voltage of a predetermined voltage and outputs it;
A DC / DC converter that converts the DC voltage into driving power for the discharge lamp;
A power control circuit for controlling power supplied from the DC / DC converter to the discharge lamp based on the output of the comparator;
A discharge lamp lighting device comprising:   2. The discharge lamp lighting device according to claim 1, wherein the comparator is a comparator having a hysteresis function.   2. The discharge lamp lighting device according to claim 1, wherein the comparator is a comparator having a latch function.   The discharge lamp lighting device according to claim 1, further comprising a display unit that displays a status based on an output of the comparator.   A projector comprising a discharge lamp and the discharge lamp lighting device according to any one of claims 1 to 4.

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