JP2006185665A - Lighting device, and projector using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device in which a part of colors of a color filter is not emphasized, and variations do not occur in a tone color even if light of a high pressure discharge lamp is projected via a rotating color filter in which a plurality of colors are arranged, and provide a projector using it. <P>SOLUTION: A frequency control circuit 34 which changes a voltage frequency of an AC lamp voltage has been installed in an AC conversion circuit 23 so that the voltage frequency of the AC lamp voltage applied to the high pressure discharge lamp 21 can be synchronized with the cycle of rotation of the color filter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lighting device in which a high-pressure discharge lamp such as a high-pressure mercury lamp or a metal halide lamp is mounted in various electronic devices, and a projector device using the lighting device.

  Hereinafter, a conventional lighting device will be described with reference to the drawings.

  FIG. 7 is a block diagram of a conventional lighting device, FIG. 8 is an equivalent circuit diagram of an AC conversion circuit in the block diagram of the lighting device, and FIG. 9 is an operation waveform diagram of the lighting device.

  7 and 8, the conventional lighting device includes a high-pressure discharge lamp 1 such as a high-pressure mercury lamp, an igniter circuit 2 that applies an AC starting voltage for initial starting of the high-pressure discharge lamp 1, and a normal high-pressure discharge lamp 1. And an AC conversion circuit 3 for applying an AC lamp voltage for starting.

  Further, the drive circuit 4 for driving is connected to the AC conversion circuit 3 described above, and the voltage of the DC power source is converted into a high frequency voltage of several tens of kHz and smoothed by the PWM control signal from the control circuit 5. A DC-DC converter circuit 6 for generating a desired output voltage is connected.

  This AC conversion circuit 3 includes a first switch 7 and a second switch 8 connected in series, and a third switch 9 and a fourth switch 10 connected in series with each other in parallel, and one end of the high-pressure discharge lamp 1. The side is connected between the first switch 7 and the second switch 8, and the other end of the high pressure discharge lamp 1 is connected between the third switch 9 and the fourth switch 10.

  Furthermore, a DC voltage is applied to the AC conversion circuit 3, and the drive circuit 4 connected to the AC conversion circuit 3 is driven by controlling the switching timing of energization of the first switch 7 to the fourth switch 10. The first energization from the first switch 7 to the fourth switch 10 via the high-pressure discharge lamp 1 and the second energization from the third switch 9 to the second switch 8 via the high-pressure discharge lamp 1 are alternately performed. By switching to, the AC lamp voltage for normal starting is applied to the high pressure discharge lamp.

  At this time, the operation waveform of the lighting device is as shown in FIG.

  The voltage waveform of the AC lamp voltage for normal starting applied to the high pressure discharge lamp 1 and the current waveform of the AC lamp current for normal starting applied to the high pressure discharge lamp 1 are substantially similar and are both rectangular. It becomes a shape. Since this rectangular voltage waveform has an overshoot 20 at discontinuous points, a similar overshoot 20 is also generated in the current waveform of the AC lamp current.

  The general configuration of the high-pressure discharge lamp 1 is as follows.

  As shown in FIG. 10, the general high-pressure discharge lamp 1 includes an arc tube 11 made of quartz glass, a sealing portion 12 extending from both ends of the arc tube 11, and a lead portion 13 from the sealing portion 12. And a pair of electrodes 14 protruding from the arc tube.

  The arc tube 11 is filled with a rare gas such as mercury or argon, and a small amount of halogen such as bromine, and the electrode 14 is made of tungsten.

  The operating principle of the high-pressure discharge lamp 1 is that when an AC starting voltage for initial startup is applied between a pair of electrodes 14, a breakdown is formed between the electrodes 14 and a discharge path is formed. An arc discharge is generated between the electrodes 14 by the application of the lamp voltage. By this discharge, the temperature in the arc tube 11 rises, mercury is heated and vaporized, and mercury atoms are excited at the arc center between the electrodes 14 to emit light. The higher the mercury vapor pressure of the high-pressure discharge lamp 1, the more suitable as a light source for a projector or the like, but from the viewpoint of the physical pressure resistance of the arc tube 11, the mercury vapor pressure in the range of about 15 to 20 MPa (150 to 200 atmospheres). Often designed.

  In the arc tube 11, tungsten evaporates and adheres to the inner wall of the arc tube 11 due to the temperature rise of the electrode due to arc discharge. Tungsten adhering in the arc tube 11 reacts with the halogen enclosed in the arc tube 11 to become tungsten halide. The tungsten halide floats in the arc tube 11, and the high temperature electrode 14 When the tip is reached, it is again dissociated into the original halogen and tungsten, and tungsten returns to the tip of the electrode 14. The so-called halogen cycle is repeated.

  The above lighting device is used, for example, in the following projector device.

  As shown in FIG. 11, this projector device is mounted with the above-described lighting device, and the light 19 of the high-pressure discharge lamp 1 is irradiated through the lens 15. The red (R), green (G), and blue (B ) In the rotation direction, a digital micromirror element 17 that is irradiated with the light 19 of the high-pressure discharge lamp 1 through the rotating color filter 16 and the lens 15, and the digital micromirror element 17 And the lens 15 that projects the light 19 of the high-pressure discharge lamp 1 reflected on the screen 18.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2004-134176 A

  In the above configuration, an overshoot 20 is generated at a discontinuous point of the AC lamp voltage voltage waveform. Therefore, an overshoot 20 is also generated in a current waveform of an AC lamp current similar to this voltage waveform, and the high pressure discharge lamp 1 Abnormal AC lamp current is applied.

  As a result, the high-pressure discharge lamp 1 is not stably energized. In particular, the plate-shaped color filter 16 in which red (R), green (G), and blue (B) are arranged in the rotation direction is rotated. When used in a projector apparatus that projects the light of the high-pressure discharge lamp 1 through the color filter 16, the color of a part of the color filter 16 is emphasized at the moment of the overshoot 20 of the AC lamp current, There was a problem that variation in color tone occurred.

  The present invention solves the above-described problems. Even when a plurality of colors are arranged and light from a high-pressure discharge lamp is projected through a rotating color filter, some colors of the color filter are not emphasized, and the color tone is not enhanced. It is an object of the present invention to provide a lighting device that does not vary and a projector device using the same.

  In order to solve the above-described problems, the present invention particularly has a configuration in which the AC converter circuit is provided with a frequency control circuit that changes the voltage frequency of the AC lamp voltage so as to synchronize with the period of the reference rectangular wave.

  With the above configuration, the voltage frequency of the AC lamp voltage can be changed so as to synchronize with the cycle of the reference rectangular wave. For example, the light of the high-pressure discharge lamp is arranged through a color filter that arranges a plurality of colors and rotates. Even when a lighting device is used in a projector device that projects light onto the screen, the period of the color boundary portion where each color boundary portion arranged in the color filter appears in the rotation direction and the cycle of the reference rectangular wave of the lighting device are synchronized. If the AC lamp voltage frequency is changed so as to be synchronized with the period of the reference rectangular wave synchronized with the period of the color boundary portion, the color filter that rotates the overshoot at the discontinuous point of the voltage waveform of the AC lamp voltage Can be generated at the color boundary.

  That is, some colors of the color filter are not emphasized, and variations in color tone can be suppressed.

  DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram of a lighting device according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of the lighting device, and FIG. 3 is an enlarged view of a color filter of the projector device.

  1 and 2, a lighting device according to an embodiment of the present invention includes a high-pressure discharge lamp 21 such as a high-pressure mercury lamp, an igniter circuit 22 that applies an AC starting voltage for initial starting of the high-pressure discharge lamp 21, And an AC conversion circuit 23 for applying an AC lamp voltage for normal starting of the high-pressure discharge lamp 21.

  A driving circuit 24 for driving is connected to the AC conversion circuit 23, and the voltage of the DC power source is converted into a high frequency voltage of several tens of kHz and smoothed by a PWM control signal from the control circuit 25. The DC-DC converter circuit 26 that generates the output voltage is connected. A desired voltage generated from the DC-DC converter circuit 26 is converted into an alternating current by using a switch element such as a varistor or an arrester and a capacitor in an igniter circuit 22, and is converted by a transformer 29 having a primary winding 27 and a secondary winding 28. The AC lamp voltage for initial start-up is applied to the high-pressure discharge lamp 21.

  The AC conversion circuit 23 includes a first switch 30 and a second switch 31 connected in series, and a third switch 32 and a fourth switch 33 connected in series with each other in parallel. One end side is connected between the first switch 30 and the second switch 31 via the secondary winding 28 of the transformer 29, and the other end side of the high pressure discharge lamp 21 is connected to the third switch 32 and the fourth switch 33. It is formed by connecting between the two. FETs are used for the first switch 30 to the fourth switch 33.

  A DC voltage is applied to the AC conversion circuit 23, and the drive circuit 24 connected to the AC conversion circuit 23 is driven by controlling the switching timing of energization of the first switch 30 to the fourth switch 33. A first energization that energizes the fourth switch 33 from the first switch 30 via the high-pressure discharge lamp 21 and a second energization that energizes the second switch 31 from the third switch 32 via the high-pressure discharge lamp 21 are alternately switched. Thus, the AC lamp voltage for normal starting is applied to the high pressure discharge lamp 21.

  The above lighting device is used in the following projector device.

  As described in the background art, this projector device has a configuration as shown in FIG. 11, but an AC lamp voltage applied to the high-pressure discharge lamp 21 is applied to the AC conversion circuit 23 of the lighting device mounted on the projector device. Is provided with a frequency control circuit 34 for changing the voltage frequency of the AC lamp voltage so that the voltage frequency can be synchronized with the rotation period of the color filter 16.

  That is, as shown in FIG. 3, the color boundary portions 36 of red (R), green (G), and blue (B) arranged on the rotating color filter 16 are constant with respect to the rotation direction of the color filter 16. Therefore, the reference rectangular wave based on the period of the color boundary portion 36 is controlled to be synchronized with the voltage frequency of the AC lamp voltage.

  4A is a waveform diagram showing the period of the color boundary portion of the color filter in the projector apparatus, FIG. 4B is a waveform diagram of a reference rectangular wave based on the period of the color boundary portion of the color filter, FIG. 4 (c) is a voltage waveform diagram of an AC lamp voltage for normal starting applied to a high pressure discharge lamp, FIG. 4 (d) is a current waveform diagram of an AC lamp current passed through the high pressure discharge lamp, and FIG. FIG. 4F is a signal waveform diagram showing ON / OFF switching of the second switch of the AC conversion circuit of the lighting device, and FIG. 4F is a signal waveform diagram showing ON / OFF switching of the second switch of the AC conversion circuit of the lighting device. 4 (g) is a signal waveform diagram showing ON / OFF switching of the third switch of the AC conversion circuit of the lighting device, and FIG. 4 (h) is ON / OFF switching of the fourth switch of the AC conversion circuit of the lighting device. It is a signal waveform diagram shown.

  As shown in FIG. 4A, the color boundary portions 36 of red (R), green (G), and blue (B) arranged on the rotating color filter 16 sequentially appear at a constant cycle. A reference rectangular wave based on the period of the color boundary portion 36 is as shown in FIG. Since this reference rectangular wave is based on the period of the color boundary part 36 of the color filter 16, the discontinuous point 37 of the reference rectangular wave is exactly synchronized with the period of the color boundary part 36 and the voltage of the AC lamp voltage. The waveform discontinuity point 37 is also synchronized with the period of the color boundary portion 36.

  That is, since the reference rectangular wave and the voltage frequency of the AC lamp voltage are synchronized with each other, the overshoot 38 generated at the discontinuous point 37 in the voltage waveform of the AC lamp voltage also matches the period of the color boundary portion 36. Here, the reference rectangular wave and the voltage frequency of the AC lamp voltage are synchronized with each other, one of the discontinuous point 37 of the reference rectangular wave and the discontinuous point 37 of the AC lamp voltage is the other discontinuous point 37. It appears at the same timing as the discontinuous point 37.

  Further, the frequency control circuit 34 changes the voltage frequency of the AC lamp voltage to an integer multiple or an integer frequency. In particular, when the voltage value of the AC lamp voltage is lower than the reference value, the AC lamp voltage The voltage frequency is controlled to increase. The voltage value of the AC lamp voltage is always detected by the monitor circuit 35. If the detected voltage value is fed back to the frequency control circuit 34 and is lower than the voltage value of the reference value, the AC lamp voltage The voltage frequency is increased.

  This is because if the voltage frequency of the AC lamp voltage is changed, the amount of tungsten deposited on the electrode 14 can be controlled during the halogen cycle. Therefore, when controlling the amount of tungsten deposited, the voltage of the AC lamp voltage is controlled. This is done in order to synchronize each other so that the waveform discontinuities 37 are located just at the color boundary 36 of the color filter 16.

  In general, in the course of the halogen cycle, tungsten halide dissociates into halogen and tungsten, and tungsten returns to the tip of the electrode 14 again. However, if the voltage frequency of the AC lamp voltage is increased, as shown in FIG. If a small amount of tungsten adheres to the tip of the electrode 14 as the deposit 39 and the voltage frequency of the AC lamp voltage is reduced, a large amount of tungsten adheres to the tip of the electrode 14 as the deposit 39 as shown in FIG. .

  At this time, if tungsten adheres in a direction in which the distance between the pair of electrodes 14 is shortened, the voltage value of the AC lamp voltage is greatly reduced by the amount of deposit 39, and the brightness of the high-pressure discharge lamp 21 is kept constant. In order to maintain the brightness of the AC lamp current, it may be necessary to pass a current exceeding the current limit value of the AC lamp current (in general, in order to keep the brightness of the high-pressure discharge lamp 21 constant, the AC lamp voltage and the AC lamp In order to suppress this, the amount of tungsten deposited on the electrode 14 is controlled. Accordingly, in order to intentionally reduce the adhesion amount of tungsten adhering in the direction in which the gap between the pair of electrodes 14 is shortened according to the ratio with the evaporation amount of tungsten evaporated from the electrode 14, in order to keep the power constant, There is no need to pass a current exceeding the limit current value.

  With the above configuration, the voltage frequency of the AC lamp voltage can be changed so as to synchronize with the cycle of the reference rectangular wave. For example, a plurality of colors are arranged and the high-pressure discharge lamp 21 is rotated via the rotating color filter 16. Even if the lighting device is used in a projector device that projects light, the period of the color boundary portion 36 where each color boundary portion 36 arranged in the color filter 16 appears in the rotation direction, and the cycle of the reference rectangular wave of the lighting device And the voltage frequency of the AC lamp voltage is changed so as to synchronize with the period of the reference rectangular wave synchronized with the period of the color boundary portion 36, and the overshoot at the discontinuous point 37 of the AC lamp voltage waveform. 38 can be generated at the color boundary 36 of the rotating color filter 16.

  Therefore, some of the colors of the color filter 16 are not emphasized, and variations in color tone can be suppressed.

  Further, when the amount of tungsten deposited on the electrode 14 is controlled by changing the voltage frequency of the AC lamp voltage so that it is not necessary to supply a current exceeding the limit current value of the AC lamp current, the AC lamp voltage is also controlled. By changing the voltage frequency to an integral multiple or to an integer division, an overshoot 38 that occurs at the discontinuous point 37 of the voltage waveform of the AC lamp voltage is generated at the color boundary portion 36 of the color filter 16. And variation in color tone can be suppressed.

  In particular, by dividing by an integer, even if there is a variation in the voltage frequency of the AC lamp voltage (even if the wavelength in each rectangular wave does not match completely, a variation occurs), the variation is absorbed. Can do. That is, when the wavelength of each rectangular wave is varied, the AC lamp voltage applied to the left and right electrodes of the high-pressure discharge lamp 21 is different, and the amount of the deposit 39 attached to the electrodes is also different depending on the left and right electrodes. become. And the light spot (center position) between electrodes shift | deviates and the problem that the focus of the light irradiated from the high pressure discharge lamp 21 shifts arises, but this can be suppressed by dividing.

  The high pressure discharge lamp 21 may be a metal halide lamp or the like in addition to the high pressure mercury lamp.

  As described above, the lighting device according to the present invention and the projector device using the same are arranged in a plurality of colors, and even if the light of the high pressure discharge lamp is projected through the rotating color filter, a part of the color filter is used. Since the color is not emphasized and the color tone does not vary, the present invention can be applied to various electronic devices.

The block diagram of the lighting device in one embodiment of this invention Equivalent circuit diagram of the lighting device Enlarged view of the color filter of the projector device Operation waveform diagram of the lighting device Cross section of high pressure discharge lamp when a small amount of tungsten is deposited Cross section of high pressure discharge lamp when a large amount of tungsten is deposited Block diagram of a conventional lighting device Equivalent circuit diagram of AC converter circuit in block diagram of lighting device Operation waveform diagram of the lighting device Cross section of high pressure discharge lamp Schematic diagram of projector device

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 High pressure discharge lamp 22 Igniter circuit 23 AC converter circuit 24 Drive circuit 25 Control circuit 26 DC-DC converter circuit 27 Primary winding 28 Secondary winding 29 Transformer 30 1st switch 31 2nd switch 32 3rd switch 33 4th switch 34 Frequency control circuit 35 Monitor circuit 36 Color boundary 37 Discontinuity point 38 Overshoot 39 Deposit

Claims (4)

An AC converter circuit for applying an AC lamp voltage to the high-pressure discharge lamp is provided, and the AC converter circuit is provided with a frequency control circuit for changing the voltage frequency of the AC lamp voltage so as to be synchronized with a cycle of a reference rectangular wave. Lighting device. The lighting device according to claim 1, wherein the frequency control circuit changes the voltage frequency of the AC lamp voltage to an integral multiple. The lighting device according to claim 1, wherein the frequency control circuit changes the voltage frequency of the AC lamp voltage to an integer frequency division. A plate-shaped color filter in which a plurality of colors are arranged in the rotation direction, a digital micromirror element that is irradiated with light from the high-voltage discharge through the rotating color filter, and the high-pressure that is irradiated to the digital micromirror element A lens for projecting light from a discharge lamp, and the period of the reference rectangular wave is synchronized with the period of the color boundary part where each color boundary part arranged in the color filter appears in the rotation direction. A projector device using the lighting device described.

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