JP4665799B2 - High pressure discharge lamp lighting device and image display device - Google Patents

Description

  The present invention relates to a high pressure discharge lamp lighting device suitable for lighting a high pressure discharge lamp used as a light source of a projection type image display device, and an image display device using the high pressure discharge lamp lighting device.

  2. Description of the Related Art Conventionally, a projection type image display apparatus that projects an image on a screen has been provided. In recent years, this type of image display device has a type in which light from a light source is transmitted through a liquid crystal display and an element called DMD (Digital Micro Mirror Device) in which a large number of minute mirrors are arranged. A type that reflects light has become widespread. Further, a general projector that projects an image from the front of the screen and a rear projection system that projects from the rear are known. A high pressure discharge lamp (HID lamp) is adopted as a light source of this type of image display apparatus because it is small and has high luminance.

  Regardless of whether a liquid crystal display or a DMD is used for image formation, there is a problem of suppressing flickering with the light source of this type of image display apparatus. Since the high pressure discharge lamp used for the light source of the image display device is close to a point light source, the arc length is as short as about 2 mm. Therefore, even if the electrode shape is slightly changed, the position of the arc is shifted. That is, the arc end position becomes unstable depending on the temperature of the electrode and the surface condition, and a phenomenon called arc jump in which the arc end position jumps easily occurs. When an arc jump occurs, flickering occurs in the light output from the high-pressure discharge lamp, resulting in a problem that the brightness of the projected image is lowered or the image becomes difficult to see due to a change in the brightness of the image.

  As a technique for suppressing the occurrence of flicker in a high-pressure discharge lamp that is operated with alternating current, in order to suppress a decrease in the temperature of the electrode of the high-pressure discharge lamp and a decrease in the temperature in the bulb, there are a plurality of polarities of voltages applied to the high-pressure discharge lamp. There is a technique for increasing the absolute value of the lamp current in the period until the next polarity inversion at least once each time it is inverted (see, for example, Patent Document 1).

  Patent Document 1 exemplifies a case where a high pressure discharge lamp is used as a light source of a projector using DMD. In a projector using a DMD, a color filter in which a plurality of color regions are arranged in a rotation direction is rotated, and light from a high-pressure discharge lamp is allowed to pass through the color filter to change the light color with time. That is, the light color of the image to be displayed is changed by changing the light color applied to the DMD as time elapses.

  Since the light output of the high-pressure discharge lamp decreases when the polarity of the voltage applied to the high-pressure discharge lamp is reversed, Patent Document 1 discloses a high-pressure discharge lamp in order to suppress the influence on the image due to the change in the light output. Describes that the timing of reversing the polarity of the voltage applied to is synchronized with the boundary of each color of the color filter. However, in the configuration described in Patent Document 1, the time for the light from the high-pressure discharge lamp to pass through the red region in the color filter is set longer than the time for the light from the high-pressure discharge lamp to pass through the other color region. The polarity of the voltage applied to the high-pressure discharge lamp is switched only during the period during which light is transmitted through the red region.

  By the way, in the configuration example described in Patent Document 1, the polarity of the voltage applied to the high-pressure discharge lamp is reversed at all the boundaries of each color of the color filter, but depending on the timing of reversing the polarity of the applied voltage, The following problems arise.

  Here, it is assumed that the color filter 20 is color-coded as shown in FIG. The illustrated color filter 20 is formed in a disk shape and rotates in one direction indicated by an arrow in the drawing. In the rotation direction, a substantially half-circular region is a red region R, and the remaining half-circular region is a green region. It is divided into G and blue region B. Further, the blue region B is larger than the green region G in the range in the rotation direction. An arrow X indicates the direction of rotation of the color filter 20. Therefore, light from the high-pressure discharge lamp is transmitted in the order of red region R → green region G → blue region B → red region R.

  Consider the case where the polarity of the voltage applied to the high-pressure discharge lamp is reversed each time the color filter rotates once. FIG. 17A shows the color region of the color filter 20 through which light from the high-pressure discharge lamp passes. As described above, the color region changes with time as the color filter 20 rotates. Represents. FIG. 17B shows a synchronization signal (the figure shows a timing signal corresponding to the rising edge of the synchronization signal) taken out when the color filter 20 is rotated by a drive source (generally an electric motor). In this case, one synchronization signal is generated for each rotation of the color filter 20.

  As a technique for generating a synchronization signal in synchronization with the rotation of the color filter 20, when the drive source is a step motor, a technique for generating a synchronization signal from a signal applied to the drive source can be adopted and applied to the drive source. When the synchronization signal cannot be generated from the signal, a technique of extracting a synchronization signal by coupling a sensor such as a rotary encoder to the rotation shaft of the color filter 20 can be employed. Alternatively, a technique of forming a through hole for detecting the rotational position at an appropriate position of the color filter 20 and detecting the position of the through hole by a photo interrupter can be employed.

  FIG. 17C shows the lamp current flowing through the high-pressure discharge lamp. Here, the polarity (the polarity of the voltage applied to the high-pressure discharge lamp) is reversed every time the color filter 20 rotates once and the synchronization signal is generated. I am letting. As described above, in order to suppress a decrease in the temperature of the electrode and the temperature in the bulb, the illustrated example shows an operation of increasing the lamp current more than the other period every time the polarity of the applied voltage is reversed three times. Yes.

  If the lamp current of the high-pressure discharge lamp is controlled so as to achieve the operation shown in FIG. 17, the light output increases once every time the color filter 20 rotates three times. Even if the color changes, the light output does not change. Therefore, although the brightness changes periodically, the light color does not change. Further, there is no problem in changing the brightness if the color filter 20 is rotated at a high speed so that the change in brightness is not perceived, and there is no inconvenience in the color tone of the display image.

  However, the time interval of the polarity reversal of the voltage applied to the high-pressure discharge lamp coincides with the time of one rotation of the color filter 20, and the number of rotations of the color filter 20 is limited. There is a possibility that a time interval suitable for maintaining the temperature cannot be set.

The rotation speed of the color filter 20 is generally 3000 to 10800 rpm, and when the polarity of the voltage applied to the high-pressure discharge lamp is reversed every time the color filter 20 rotates as described above, the application to the high-pressure discharge lamp is performed. The frequency of the voltage is 25 to 90 Hz. At such a low frequency, it is difficult to maintain the temperature of the electrode and the temperature in the bulb, and the light output changes as the temperature decreases, causing flickering or shortening the lamp life. there is a possibility.
JP 2005-38815 A

  On the other hand, in the configuration described in Patent Document 1, the polarity of the voltage applied to the high-pressure discharge lamp is reversed for each color region boundary of the color filter 20, so that the applied voltage is not changed during one rotation of the color filter 20. The polarity changes a plurality of times (at least as many times as the number of color regions provided in the color filter 20). For example, a period for increasing the lamp current once every time the color filter 20 rotates (a period from polarity inversion to the next inversion) is provided. Therefore, in the operation shown in FIG. 17, when the color filter 20 rotates twice, the lamp current is increased by the next rotation, whereas the lamp current is increased every time the color filter 20 rotates one time. Therefore, it is possible to suppress a decrease in the temperature of the electrodes and valves. In the example described in Patent Document 1, a period in which the lamp current is increased in synchronization with the red region of the color filter 20 is provided.

  Incidentally, in order to increase the lamp current in an appropriate period during one rotation of the color filter 20, when each color region of the color filter 20 changes as shown in FIG. 18A, as shown in FIG. It is necessary to generate a synchronization signal whenever the color region changes. However, since the synchronization signal does not include the information on the color region of the color filter 20, as shown in FIG. 18C, the ramp is generated by the synchronization signal generated at the timing of the boundary between the blue region and the red region in the initial state. Even if the timing for increasing the current is set and thereafter a period for increasing the lamp current is provided for every three polarity inversions, the green region as shown in FIG. There is a possibility that the lamp current increases in synchronism with the above, or the lamp current increases in synchronism with the blue region as shown in FIG. 148e). As described above, when the relationship between the period in which the lamp current is increased and the color region of the color filter 20 is deviated, there arises a problem that the color tone is changed.

  The present invention has been made in view of the above reasons, and its object is to increase the number of times of polarity inversion of the voltage applied to the high-pressure discharge lamp more than the number of generation of the synchronization signal and to shorten the period in which the lamp current is increased. To provide a high pressure discharge lamp lighting device that can easily maintain the temperature of the electrode and the temperature in the bulb and suppress the change in light output, and further to provide an image display device using the high pressure discharge lamp lighting device. It is in.

  The invention according to claim 1 is based on a DC power supply circuit whose output is variable, a polarity inversion circuit for applying an alternating voltage generated from the output of the DC power supply circuit to the high-pressure discharge lamp, and a synchronization signal supplied from the outside. A control circuit that controls the output of the DC power supply circuit and the timing of polarity reversal by the polarity reversing circuit at the timing, and the control circuit reverses the polarity of the voltage applied to the high-pressure discharge lamp for each synchronization signal and The lamp current during the period from when the polarity of the voltage applied to the lamp is reversed to the next is selected from a specified value for lighting the high-pressure discharge lamp and an increased value larger than the specified value. When selecting, the polarity of the voltage applied to the high-pressure discharge lamp is reversed within a period between a pair of adjacent synchronization signals, and the lamp current increases within the period. Characterized in that it is set shorter than the period in which the period between the specified value.

  According to this configuration, when providing a period for increasing the lamp current, the polarity of the voltage applied to the high-pressure discharge lamp is inverted within the period between the pair of adjacent sync signals, and the period for increasing the lamp current is Compared with the conventional configuration in which the polarity of the voltage applied to the high-pressure discharge lamp is reversed only at the timing of generation of the synchronization signal because the period is shorter than the specified value period, the period per one time for increasing the lamp current is shortened and conversely the lamp By increasing the frequency of increasing the current, it becomes easier to maintain the temperature in the electrodes and bulbs of the high-pressure discharge lamp, and it is possible to suppress changes in light output and electrode wear.

  According to a second aspect of the present invention, in the first aspect of the present invention, the ratio between the specified value and the increased value is constant regardless of the lamp voltage.

  According to this configuration, even if the lamp voltage fluctuates, the relative ratio of the light output of the high-pressure discharge lamp corresponding to the specified value and the increased value is kept constant. The light output does not increase drastically when increasing, and there is no sense of incongruity.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the control circuit limits the time limit longer than the time interval to which the synchronization signal is applied every time the synchronization signal is applied. When the time limit of the time limit ends without a synchronization signal being given during the time limit, the lamp current and the polarity of the voltage are controlled according to a preset control pattern.

  According to this configuration, even when the next synchronization signal is not given, it is possible to prevent the direct current from continuing to flow without the polarity of the voltage applied to the high-pressure discharge lamp being inverted. In other words, the polarity of the voltage applied to the high-pressure discharge lamp is reversed if the time limit elapses even if the next synchronization signal is not given after the synchronization signal is given. it can.

  The invention of claim 4 is an image display device comprising the high-pressure discharge lamp lighting device according to any one of claims 1 to 3, wherein the high-pressure discharge lamp is used as a light source. To do.

  According to this configuration, it is possible to provide an image display device with little change in light output and little flickering or color change. In addition, since the wear of the electrodes of the high-pressure discharge lamp can be suppressed, the replacement frequency of the lamp can be reduced.

  According to a fifth aspect of the invention, there is provided a color filter according to the fourth aspect of the invention, wherein the color filter has a plurality of color regions and periodically transmits light from the high-pressure discharge lamp to each color region over time. A main control circuit that generates the synchronization signal at a timing at which light from the high-pressure discharge lamp passes through each color region, and the control circuit applies to the high-pressure discharge lamp as a period of one cycle of color change of the color filter. A period in which the polarity of the voltage is inverted an odd number of times and a period in which the voltage applied to the high-pressure discharge lamp is inverted an even number of times are alternately provided.

  This configuration is based on the premise that the color region through which the light from the high-pressure discharge lamp passes is used in combination with a color filter that changes over time, and the lamp current increases when averaged over multiple cycles of color change of the color filter. Since the period is the same for each color region, even if there is a deviation in the period for increasing the lamp current with respect to the sync signal, the average of the color filter's color change varies in the period in which the lamp current increases. Does not occur. In other words, if the color change period of the color filter is set to be short enough that the color change between a plurality of periods of the color change of the color filter is not perceived, no substantial change in color due to the shift of the synchronization signal will occur. .

  The invention of claim 6 is characterized in that, in the invention of claim 4, light is not projected at least during a period in which the lamp current is an increase value.

  According to this configuration, since the light from the high-pressure discharge lamp is not used during the period when the lamp current is increasing, the increase in the light output accompanying the increase in the lamp current is not reflected in the display, and the lamp current is reduced. In the increasing period, it is possible to provide an optimum lamp current for suppressing the fluctuation of the light output of the high-pressure discharge lamp and the wear of the electrodes.

  According to a seventh aspect of the invention, there is provided a color filter according to the sixth aspect of the invention, wherein the color filter has a plurality of color regions and periodically transmits the light from the high-pressure discharge lamp to each color region over time. A main control circuit that generates the synchronization signal at a timing at which light from the high-pressure discharge lamp passes through each color region, and the control circuit applies a voltage applied to the high-pressure discharge lamp during a period of one color change of the color filter. The polarity is inverted an odd number of times.

  According to this configuration, since the polarity of the voltage applied to the high-pressure discharge lamp is inverted an odd number of times in one cycle of the color change of the color filter, the polarity in which the lamp current increases is inverted every time the color change of the color filter is performed. As a result, there is no bias in electrode wear. Further, since the light from the high-pressure discharge lamp is not used during the period when the lamp current increases, the color of the projected image is changed even if the relationship between the timing of increasing the lamp current and the synchronization signal is shifted. There is nothing.

  According to the configuration of the present invention, when a period for increasing the lamp current is provided, the polarity of the voltage applied to the high-pressure discharge lamp is inverted within the period between a pair of adjacent synchronization signals, and the lamp current is increased. Since the period is shorter than the period of the specified value, the period for increasing the lamp current is shortened compared to the conventional configuration in which the polarity of the voltage applied to the high-pressure discharge lamp is reversed only at the generation timing of the synchronization signal. The frequency of increasing the lamp current increases. As a result, it is easy to maintain the temperature in the electrodes and bulbs of the high-pressure discharge lamp, and there is an effect that changes in light output and electrode wear can be suppressed.

  Further, when this high pressure discharge lamp lighting device is used in an image display device using a high pressure discharge lamp as a light source, it is possible to display an image without flickering and no change in color, and the replacement frequency of the high pressure discharge lamp is reduced. can do.

  The high-pressure discharge lamp lighting device used in each embodiment described below is assumed to have the configuration shown in FIG. However, this configuration example is merely an example, and it is not necessary to match the circuit configuration illustrated in FIG. 6 as long as the same operation is possible. The high pressure discharge lamp lighting device shown in FIG. 6 is particularly suitable for a projector using a DMD as shown in FIG. 7, and the timing for reversing the polarity of the voltage applied to the high pressure discharge lamp is given to the projector. A configuration that synchronizes with the rotation of the provided color filter is employed.

  As shown in FIG. 7, the projector includes a main control circuit 21 for controlling a drive source (not shown) for rotating the color filter 20, and the main control circuit 21 receives a control signal Sc for controlling the drive source. A synchronization signal Ss synchronized with the rotation of the color filter 20 is output. The timing for generating the synchronization signal will be described in each embodiment.

  A high-pressure discharge lamp La as a light source is disposed on one surface side of the color filter 20, and a DMD 11 is disposed on the other surface side. Further, lenses 12 and 13 are disposed between the high-pressure discharge lamp La and the color filter 20 and between the color filter 20 and the DMD 11, respectively, and converge the light emitted from the high-pressure discharge lamp La to converge the color filter 20. The light passing through the color filter 20 is diverged to irradiate the DMD 11. The light reflected by the DMD 11 is projected onto the screen through the projection lens 14.

  The high pressure discharge lamp La is supplied with electric power from the high pressure discharge lamp lighting device 30. The synchronization signal Ss output from the main control circuit 21 is input to the high pressure discharge lamp lighting device 30.

  As shown in FIG. 6, the high pressure discharge lamp lighting device 30 has a step-down chopper circuit 1 as a DC power supply circuit that steps down the voltage of the DC power supply DC, and a DC voltage output from the step-down chopper circuit 1 into a rectangular wave alternating voltage. A full bridge circuit 2 for conversion, a control circuit 3 for controlling the operation of the chopper circuit 1 and the full bridge circuit 2, a resonance circuit 4 that resonates by a rectangular wave alternating voltage output from the full bridge circuit 2, and a smoothing capacitor C1. And a voltage detection circuit 5 that detects the terminal voltage as a voltage corresponding to the lamp voltage Vla of the high-pressure discharge lamp La. The full bridge circuit 2 and the resonance circuit 4 function as a polarity inversion circuit that applies an alternating voltage to the high-pressure discharge lamp La. The voltage detection circuit 5 is a series circuit of resistors R2 and R3, connected in parallel to the smoothing capacitor C1, and detects the voltage across the resistor R3 as a voltage corresponding to the lamp voltage Vla (hereinafter, the voltage across the resistor R3 is referred to as the voltage across the resistor R3). Lamp voltage Vla).

  The DC power source DC that provides the input voltage to the chopper circuit 1 does not necessarily need to be a stable voltage, and may be a pulsating current obtained by rectifying a commercial power source. The chopper circuit 1 has a configuration in which a series circuit of a switching element Q1, an inductor L1, and a smoothing capacitor C1 is connected between both ends of the DC power source DC, and a diode D1 is connected in parallel to the series circuit of the inductor L1 and the smoothing capacitor C1. Have. The diode D1 has an anode connected to the negative electrode of the smoothing capacitor C1. Further, a resistor R1 for detecting a chopper current when the switching element Q1 is on is inserted between the anode of the diode D1 and the negative electrode of the DC power source DC.

  The full bridge circuit 2 is a circuit in which four switching elements Q2 to Q5 are bridge-connected, and a series circuit of switching elements Q2 and Q3 and a series circuit of switching elements Q4 and Q5 are respectively connected between both ends of the smoothing capacitor C1. It has a connected configuration. On / off of each of the switching elements Q2 to Q5 is controlled by outputs of drive circuits (for example, IR2111 manufactured by IR) DV1 and DV2. As basic operations, switching elements Q2 and Q5 are simultaneously turned on and switching elements Q3 and Q4 are both turned off, and switching elements Q3 and Q4 are simultaneously turned on and both switching elements Q2 and Q5 are turned off. It operates so as to alternately repeat the period. Therefore, the voltage between the connection point of switching elements Q2 and Q3 and the connection point of switching elements Q4 and Q5 can be alternated.

  Between the connection point of the switching elements Q2 and Q3 and the connection point of the switching elements Q4 and Q5, a resonance circuit 4 comprising a series circuit of an inductor L2 and a capacitor C2 is connected, and the capacitor C2 is further connected to a high-pressure discharge lamp La. Are connected in parallel. When starting the high-pressure discharge lamp La, the switching elements Q2 to Q5 are switched at a high frequency, and the resonance circuit 4 is provided so that a resonance voltage of several kV is applied to the high-pressure discharge lamp La. After starting the high-pressure discharge lamp La, a rectangular wave alternating voltage is applied to the high-pressure discharge lamp La at a low frequency of several tens to several hundreds Hz. In addition to the MOSFET shown in the figure, a diode is connected in antiparallel to the collector-emitter of the bipolar transistor in the switching elements Q1 to Q5 (connected in parallel so that the direction opposite to the direction of the current flowing through the collector-emitter is the forward direction). A thing, IGBT, etc. can be used.

  On / off of the switching element Q1 of the chopper circuit 1 and the switching elements Q2 to Q5 of the full bridge circuit 2 is controlled by the control circuit 3. The control circuit 3 receives the synchronization signal Ss output from the main control circuit 21, and two types corresponding to the group that is simultaneously turned on and the group that is simultaneously turned off among the switching elements Q2 to Q5 of the full bridge circuit 2. Polarity inversion processing unit 31 for generating the bridge control signals FB1 and FB2 of.

  The polarity inversion processing unit 31 detects the rising edge or the falling edge of the synchronization signal Ss, or detects the change point of the synchronization signal Ss, and generates the full bridge control signals FB1 and FB2 based on the detected starting point. The bridge control signals FB1 and FB2 are rectangular wave signals in which one is at the H level and the other is at the L level. When the bridge control signals FB1 and FB2 are input to the full bridge control unit 32, the switching elements Q2 to FB2 are input. A control signal for controlling on / off of Q5 is generated, and the control signal is used to control on / off of each switching element Q2-Q5 through each drive circuit DV1, DV2.

  The polarity inversion processing unit 31 also has a function of generating a switching signal S1 to be described later with the synchronization signal Ss. As in the conventional configuration, the present invention provides a period in which the lamp current is increased temporarily during the period in which the high-pressure discharge lamp La is stably lit, and the lamp current is increased. The period is determined by the switching signal S1.

  Hereinafter, the lamp current during the period when the high-pressure discharge lamp La is stably lit is referred to as a specified value. If the average current when constant power control is performed so as to keep the power supplied to the high-pressure discharge lamp La constant, the reference value is set, and the specified value is set so that the average current including the increased value is maintained at the reference value. The power supplied to the lamp La is equal to the lamp current as a reference value, and if the specified value is set so that the average current not including the increased value is kept at the reference value, the power supplied to the high-pressure discharge lamp La is It increases compared to the case where is used as a reference value. The relationship between the specified value and the increase value is one of the two types of relationships described above.

  The lamp current is adjusted by changing the output voltage of the chopper circuit 1. That is, the lamp current is adjusted by changing the on-duty of the switching element Q1 of the chopper circuit 1. The PWM control circuit 36 generates a PWM signal for controlling on / off of the switching element Q1, and the PWM control circuit 36 outputs an on-duty PWM signal corresponding to the input voltage. Therefore, two types of voltages are generated in advance, and the input voltage to the PWM control circuit 36 is switched in synchronization with the switching signal S1, thereby switching the two types of on-duty PWM signals in synchronization with the switching signal S1. It becomes possible to give to the element Q1.

  In order to generate two types of voltages to be applied to the PWM control circuit 36, the control circuit 3 has data in which the lamp voltage Vla detected by the voltage detection circuit 5 is associated with the two stages of lamp current data Ip1 and Ip2. A table 33 is provided. The lamp current data Ip1 is data having a lamp current value (specified value) corresponding to the lamp voltage Vla when the high-pressure discharge lamp La is stably lit, and the lamp current data Ip2 is lamp current data for the same lamp voltage Vla. It is set to have a value (increase value) larger than Ip1. The ratio of the value of the lamp current data Ip2 to the lamp current data Ip1 is set empirically.

  As shown in FIG. 8, the ratio (Ip2 / Ip1) between the lamp current data Ip1 and the lamp current data Ip2 may be constant regardless of the lamp voltage Vla, or may be changed according to the lamp voltage Vla. In the data table 33, the range of the lamp voltage Vla for setting the lamp current data Ip2 may be a normal operating voltage range Dv for steady lighting of the high-pressure discharge lamp La.

  When changing according to the lamp voltage Vla, as shown in FIG. 9, the ratio of the lamp current data Ip2 to the lamp current data Ip1 is increased in a range where the lamp voltage Vla exceeds the specified voltage Vd in the use voltage range Dv. Is desirable. This is because, in a high pressure discharge lamp such as an ultra high pressure mercury lamp, constant power control is performed at the time of steady lighting, so when the lamp voltage Vla increases, the lamp current decreases and the temperature in the electrodes and bulbs decreases. This is because it may become easy to cause flicker.

  Only the operation related to the steady lighting of the high pressure discharge lamp La will be described here, the operation from the start of the high pressure discharge lamp La, the operation from the start to the steady lighting, and when the abnormality occurs in the high pressure discharge lamp La. The operation, no-load operation, etc. are not specifically described.

  In order to collate the lamp voltage Vla detected by the voltage detection circuit 5 with the data table 33, an A / D converter 34 for analog-digital conversion of the lamp voltage Vla is provided. The values of the lamp current data Ip1 and Ip2 obtained by comparing the lamp voltage Vla with the data table 33 are converted into duty signals (rectangular wave signals having on-duty according to the input data) by the PWM signal generation processing unit 35. Is done. Therefore, the input voltage applied to the PWM control circuit 36 can be obtained by integrating or smoothing the duty signal. The integrating circuit that performs integration or smoothing includes a resistor R4 and a capacitor C4 for the lamp current data Ip1, and includes a resistor R5 and a capacitor C5 for the lamp current data Ip2.

  A change-over switch SW1 is provided to input one of the terminal voltages of the capacitors C4 and C5 to the PWM control circuit 36. By controlling the change-over switch SW1 with the above-described change-over signal S1, any one of the capacitors C4 and C5 is provided. One terminal voltage is input to the PWM control circuit 36. A MOSFET, a transistor, or an analog switch is used as the changeover switch SW1.

  By the way, the voltage across the resistor R1 is also input to the PWM control circuit 36. In the PWM control circuit 36, the chopper current when the switching element Q1 detected as the voltage across the resistor R1 is turned on via the changeover switch SW1. The on-duty of the switching element Q1 is controlled so that the lamp current data Ip1 and Ip2 given to the control circuit 36 are maintained. That is, the lamp current data Ip1 and Ip2 are given to the PWM control circuit 36 as a target value of the lamp current corresponding to the lamp voltage Vla.

  In the control circuit 3 described above, the polarity inversion processing unit 31, the data table 33, and the A / D conversion unit 34 are configured using a microcomputer (for example, M37540, M37542, M37546 manufactured by Renesas Technology Corp.). The Further, instead of using the data table 33, lamp current data Ip1 and Ip2 may be obtained by performing an appropriate calculation.

  In each embodiment described below, the operation of the polarity inversion processing unit 31 will be mainly described. That is, the relationship between the synchronization signal Ss given from the main control circuit 21 to the control circuit 3, the polarity inversion timing in the full bridge circuit 2, and the switching signal S1 will be described. The configuration of the color filter 20 is basically assumed to have a configuration in which the color area is divided into three as shown in FIG. 12 (the color area is called a segment, and the three-division filter is divided into three segments). In addition, various color filters 20 as shown in FIGS. 10 to 15 may be used. Each of FIGS. 10A to 15A shows the color arrangement of the color filter 20, and each of FIGS. 10B to 15B shows a color change with time when the color filter 20 is rotated.

  FIG. 10 shows three segments of a red region R, a green region G, and a blue region B, and each region is equally divided in the rotation direction. In addition, the one shown in FIG. 11 has four segments with a white area W added, and the one shown in FIG. 12 has a yellow area Y, a cyan area C, and a magenta area M added to a red area R, a green area G, and a blue area B. 6 segments. FIG. 13 also shows 6 segments, which are provided with two red regions R, green regions G, and blue regions B, respectively. 14 and 15 both show a 7-segment color filter 20, and the one shown in FIG. 14 is provided with a dark green region DG between the green region G and the cyan region C in the configuration shown in FIG. In the configuration shown in FIG. 15, a dark green region DG is provided between the green region G and the blue region B in the configuration shown in FIG. 13. The dark green region DG has functions of a green filter and an ND filter, and selectively transmits green and reduces light.

  In each of the embodiments described below, in order to facilitate comparison with the conventional configuration, an example is shown in which three segments and a large red region R are taken as in the color filter 20 shown in FIG. However, even when the color filter 20 having the configuration shown in FIGS. 10 to 15 is used, the same configuration can be adopted.

(Embodiment 1)
In this embodiment, as shown in FIG. 1, the synchronization signal Ss is received from the main control circuit 21 every rotation of the color filter 20 (see FIG. 1A). As in 1 (b), a timing signal that coincides with the timing at which the light beam from the high-pressure discharge lamp La passes through the boundary line from the blue region B to the red region R of the color filter 20 is generated. Here, in the present embodiment, it is assumed that the synchronization signal Ss from the main control circuit 21 rises at the boundary line from the blue region B to the red region R.

  The polarity inversion processing unit 31 inverts the on / off states of the switching elements Q2 to Q5 provided in the full bridge circuit 2 at a timing synchronized with the timing signal shown in FIG. 1B, as shown in FIG. The polarity of the voltage applied to the high-pressure discharge lamp La is reversed. Also, every time a timing signal is generated, a period in which the polarity is not changed until the next timing signal is generated and a period in which the polarity is inverted until the next timing signal is generated are alternately provided.

  When the polarity is inverted between a pair of adjacent timing signals, the polarity is inverted during the passage period of the red region R having the longest light transit time from the high-pressure discharge lamp La among the color regions of the color filter 20. It is desirable to do it. Although the timing signal generated based on the synchronization signal Ss corresponds to the boundary between the blue region B and the red region R, it cannot be determined whether or not the light is passing through the red region R. Therefore, the polarity inversion timing is set to a predetermined time from the generation of the timing signal. In other words, the polarity inversion processing unit 31 is provided with a timer that limits a certain time from the generation of the timing signal, and inverts the polarity of the voltage applied to the high-pressure discharge lamp La when the timer expires. Within the period between a pair of adjacent synchronization signals Ss, the time limit by the timer (the period during which the lamp current is increased) is set shorter than the period during which the specified value is reached.

  As is clear from the above-described operation, a period for performing the timed operation by the timer and a period for not performing the timed operation by the timer are alternately provided every time the timing signal is generated. Further, when performing a timed operation by the timer, the changeover switch SW1 is controlled by the changeover signal S1, and an input voltage corresponding to the lamp current data Ip2 is set so that the lamp current is temporarily set to an increased value larger than a specified value. This is given to the PWM control circuit 36.

  Since the lamp current is increased during the timed operation of the timer, the light output of the high-pressure discharge lamp La may change or the electrodes of the high-pressure discharge lamp La may be damaged if the timer time is long. There is. Therefore, it is desirable to set the timed operation of the timer to less than 20 ms.

  In the present embodiment, since the timing signal is generated every rotation of the color filter 20, as compared with the case where the synchronization signal is generated every time the color region changes as in the conventional configuration shown in FIG. The possibility of a shift in the relationship between the period in which the lamp current is temporarily increased and the color area is reduced. In addition, as in the configuration illustrated in FIG. 17, the frequency of temporarily increasing the lamp current can be increased as compared with the case where the polarity of the lamp current is not changed during the period in which the color filter 20 rotates once.

  For example, if the polarity of the lamp current is not reversed during the period in which the color filter 20 rotates once, if the lamp current is an increase value in one of the three rotations, the color filter 20 corresponds to two rotations of the six rotations. During this period, the lamp current increases. Therefore, the frequency of increasing the lamp current is low (once while the color filter 20 is rotated three times), and the time per time is increased (period in which the color filter 20 is rotated once).

  On the other hand, in the operation of the present embodiment, since the lamp current increases only for a part of the three rotations of the color filter 20 in six rotations, the frequency of increasing the lamp current increases (color filter 20 1 time during two rotations), the time per one time is shortened (shorter than the period in which the color filter 20 is half-rotated). However, since the polarity of the lamp current is reversed in the red region R, the luminance changes in the red region R. However, the red region R has a sufficiently large area compared to the green region G and the blue region B, and the color filter Since the lamp current increases only in a part of the red region R during 20 rotations, the luminance change in the red region R is hardly perceived visually, and the substantial color change is not perceived.

  In the operation of the present embodiment, it is possible to set a time interval suitable for maintaining the temperature in the electrode and bulb of the high-pressure discharge lamp La, and the time for increasing the lamp current is relatively short. Therefore, the electrode is hardly damaged.

(Embodiment 2)
In the first embodiment, each time the synchronization signal Ss is generated, a period until the next synchronization signal Ss is generated includes a period during which the polarity of the lamp current is inverted and a period during which the polarity of the lamp current is not inverted between the red regions R. Therefore, a slight luminance change occurs in the red region R between the period in which the polarity of the lamp current is inverted and the period in which the polarity is not inverted. That is, when the polarity is reversed, the luminance of the high-pressure discharge lamp La decreases for a moment.

  Therefore, in the present embodiment, as shown in FIG. 2C, the adjustment is a fixed time from the generation of the timing signal (see FIG. 2B) corresponding to the synchronization signal Ss in the period in which the lamp current is increased. When the lamp current is increased by the period Δt, the polarity of the lamp current is reversed after the adjustment period Δt has elapsed from the generation of the timing signal in the period in which the lamp current is the specified value. In other words, the polarity of the lamp current is inverted every time the color filter 20 rotates twice, and the timing of the polarity inversion is set after the adjustment period Δt from the generation of the timing signal, and after the polarity inversion until the next polarity inversion. The absolute value of the lamp current is increased for the adjustment period Δt in synchronism with the timing signal generated between them, with the lamp current having the opposite polarity.

  In the operation of the present embodiment, since the polarity of the lamp current is inverted corresponding to the red region R every time the color filter 20 rotates, the luminance does not change due to the polarity inversion. It cannot be said at a glance whether there is more luminance change due to lamp current change or luminance change due to polarity reversal, but in this embodiment, the luminance is different for each rotation period of the color filter 20 as compared with the first embodiment. It is possible to reduce factors that cause changes. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 3)
In the first embodiment, the configuration in which the synchronization signal Ss is generated from the main control circuit 21 every rotation of the color filter 20 is adopted. However, in the present embodiment, as shown in FIG. The synchronization signal Ss is generated from the main control circuit 21. Therefore, as shown in FIG. 3B, a timing signal is generated every time the color region of the color filter 20 changes. When a plurality of timing signals are generated during one rotation of the color filter 20 as described above, even if an attempt is made to increase the lamp current in the same color region every time the color filter 20 rotates, the lamp current is caused by a slight deviation in timing. Deviation may occur in the color region that increases the image quality.

  For example, in the case where the lamp current is designed to increase in the red region R as in the first embodiment, there is a possibility that a timing shift occurs so that the lamp current increases in the green region G and the blue region B in the middle. There is. Even if a timing shift occurs, it is only necessary to return to the original state. However, if the timing shift state is maintained, the lamp current increases in a color region different from the designed color region. Changes in color.

  Therefore, in the present embodiment, as the period in which the color filter 20 rotates once, the number of times of reversing the polarity is an odd number (5 times in the illustrated example), and the even number (4 times in the illustrated example) is a period. Are repeated alternately. In the illustrated example, when the color filter 20 is provided with three color regions and a timing signal is generated for each color region, the period in which the lamp current is increased every time the polarity is inverted three times. In addition, the period in which the lamp current is increased is set shorter than the period until the next timing signal is generated. In other words, the lamp current is increased twice during a period where the number of polarity reversals is large, and the lamp current is increased once during a period where the number of polarity reversals is small.

  If the period in which the lamp current is increased is set as in the present embodiment, the color region corresponding to the period in which the lamp current is increased varies with each rotation of the color filter 20, and a plurality of color filters 20 are provided. If the period of rotation is averaged, the period in which the lamp current is increased will not be biased to a specific color area, so even if the relationship between the period in which the lamp current is increased and the color area is deviated as a whole There is no change in color. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 4)
In each of the above-described embodiments, it is assumed that the synchronization signal Ss is always input from the main control circuit 21 to the polarity inversion processing unit 31. However, noise is generated after the synchronization signal Ss is once input to the polarity inversion processing unit 31. In some cases, the next synchronization signal Ss cannot be received due to disconnection.

  Therefore, in the present embodiment, when the next synchronization signal Ss cannot be received even after the time to receive the next synchronization signal Ss after the synchronization signal Ss is received, the polarity inversion processing unit 31 bridges at an appropriate timing. The control signals FB1, FB2 and the switching signal S1 are automatically generated. That is, when the polarity reversal processing unit 31 has a built-in timer and the synchronization signal Ss is received, the next synchronization signal Ss cannot be received even after a predetermined scheduled time limited by the timer has elapsed. The polarity of the lamp current is inverted and the lamp current is increased at a timing preset in the timer.

  An operation example of this embodiment is shown in FIG. In the illustrated example, it is assumed that the synchronization signal Ss is generated at the time interval T. When the synchronization signal Ss is input to the polarity determination processing unit 31 (when the timing signal is generated), the time limit of the time limit t1 (> T) set longer than the time interval T by the timer is started. If the next timing signal is generated by the end of the time limit of the time limit t1, the timer is retriggered to time the time limit t1 again. That is, the timer is configured to be retriggerable.

  On the other hand, when the time limit of the time limit t1 has ended, the polarity of the lamp current is inverted and the lamp current is increased with a preset control pattern. Here, since the polarity of the voltage applied between the electrodes of the high-pressure discharge lamp La is not reversed during the time limit t1, only one electrode of the high-pressure discharge lamp La may be worn out. Therefore, the time limit t1 is longer than the time interval T at which the synchronization signal Ss is generated, but is set to such a time that the electrodes of the high-pressure discharge lamp La are not consumed.

  The control pattern after the elapse of the limit time t1 is set, for example, within a time longer than the time for the color filter 20 to rotate once and shorter than the time for two rotations, and the lamp current is set only once in the middle of this time. The control pattern is set so that a period for the increase value occurs. That is, a period in which the lamp current is a specified value is provided before and after the period in which the lamp current is an increase value. Further, the polarity is inverted between the period in which the lamp current is increased and the period in which the lamp current is the specified value. Here, when the period in which the lamp current is increased is continued for the time t3, and the period in which the lamp current is increased before and after that is continued for the time t2, t4, the time t2, t4 is It is desirable to set them equal, but they may be different. Further, the relationship between time t2, t4 and time t3 may be set in any way.

  When the synchronization signal Ss is no longer input to the polarity inversion processing unit 31, the bridge control signals FB1 and FB2 and the switching signal S1 are generated so as to control the polarity of the voltage applied to the high-pressure discharge lamp La and the lamp current according to the control pattern described above. Then, the above-described operation according to the control pattern is repeated until the synchronization signal Ss is input. Note that, when the synchronization signal Ss is not input, there is a possibility that an abnormality has occurred. Therefore, when the operation according to the control pattern continues for a specified time, the abnormality may be notified. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 5)
In the operation described in the second embodiment, since the configuration in which the polarity of the lamp voltage applied to the high-pressure discharge lamp La is reversed in the red region R of the color filter 20 is employed, the luminance change occurs in the red region R. This luminance change is hardly perceived, but may cause a slight change in color.

  Therefore, in the present embodiment, in the operation of FIG. 2, light is not projected onto the screen during the adjustment period Δt from the generation of the timing signal corresponding to the synchronization signal Ss. That is, the light is not used in the adjustment period Δt from the generation of the timing signal. Specifically, the DMD 11 is controlled so that the light from the high-pressure discharge lamp La is not reflected toward the projection lens 14 in the adjustment period Δt. Either a technique for providing a light blocking area for blocking light in an area corresponding to the adjustment period Δt in the color filter 20 is employed. With this operation, no light is projected during a period in which the lamp current is an increased value, and no light is projected during the adjustment period Δt even if the lamp current is a specified value.

  The DMD 11 is an array of a number of minute mirrors as described in the prior art. By changing the direction of the mirrors, the DMD 11 reflects light toward the projection lens 14 and the high-pressure discharge lamp la A state in which light does not pass through the projection lens 14 can be selected. In the DMD 11, the former state is called “on” and the latter state is called “off”. Therefore, by turning off the DMD 11 during the adjustment period Δt from the generation of the timing signal, it is possible to create a state in which no light is projected onto the screen during the adjustment period Δt.

  In practice, it is difficult to match the time for turning off the DMD 11 and the time for the light shielding region to pass with the adjustment period Δt. Therefore, the time for turning off the DMD 11 and the time for the light shielding region to pass through the adjustment period Δt. It is desirable to set a longer time. Other configurations and operations are the same as those of the second embodiment.

(Embodiment 6)
In the present embodiment, as in the third embodiment, the synchronization signal Ss is generated from the main control circuit 21 every time the color region of the color filter 20 changes. However, in the third embodiment, the period in which the lamp current is increased during one rotation of the color filter 20 is alternately repeated between the odd-numbered period and the even-numbered period. In the present embodiment, FIG. As shown, the number of times of reversing the polarity of the voltage applied to the lamp during one rotation of the color filter 20 is always an odd number (5 in the illustrated example).

  In the example shown in FIG. 5C, the lamp current is increased by the adjustment period Δt in association with the green region G and the blue region B. In the example shown in FIG. In association with the lamp current, the lamp current is increased by the adjustment period Δt. Further, in the example shown in FIGS. 5C and 5D, immediately after the timing signal is generated in the color region (the red region R in FIG. 5C and the green region G in FIG. 5D) in which the lamp current is a specified value. However, as shown in FIG. 5E, the polarity may be reversed after the adjustment period Δt has elapsed since the generation of the timing signal. In short, the same operation as in the second embodiment may be performed.

  5C, 5D, and 5E, similarly to the fifth embodiment, light is not projected from the projection lens 14 onto the screen at least during the adjustment period Δt from the generation of the timing signal. You may adopt the technology to That is, the DMD 11 may be turned off during the adjustment period Δt, or the area corresponding to the adjustment period Δt in the color filter 20 may be set as a light shielding area. Other configurations and operations are the same as those of the first embodiment.

FIG. 3 is an operation explanatory diagram illustrating the first embodiment. FIG. 10 is an operation explanatory diagram illustrating the second embodiment. FIG. 10 is an operation explanatory diagram illustrating the third embodiment. FIG. 10 is an operation explanatory diagram illustrating the fourth embodiment. FIG. 10 is an operation explanatory diagram illustrating the sixth embodiment. It is a circuit diagram which shows the high pressure discharge lamp lighting device used in common with each embodiment. It is a schematic block diagram of the image display apparatus used in common with each embodiment. It is a figure which shows the example of a setting of the data table used for the same as the above. It is a figure which shows the other example of a setting of the data table used for the same as the above. The color filter used for the above is shown, (a) is a diagram showing the arrangement of the color region, (b) is a diagram showing the change of the color region. The color filter used for the above is shown, (a) is a diagram showing the arrangement of the color region, (b) is a diagram showing the change of the color region. The color filter used for the above is shown, (a) is a diagram showing the arrangement of the color region, (b) is a diagram showing the change of the color region. The color filter used for the above is shown, (a) is a diagram showing the arrangement of the color region, (b) is a diagram showing the change of the color region. The color filter used for the above is shown, (a) is a diagram showing the arrangement of the color region, (b) is a diagram showing the change of the color region. The color filter used for the above is shown, (a) is a diagram showing the arrangement of the color region, (b) is a diagram showing the change of the color region. It is a figure which shows arrangement | positioning of the color area | region of a color filter. It is operation | movement explanatory drawing of a conventional structure. It is operation | movement explanatory drawing of another conventional structure.

Explanation of symbols

1 Step-down chopper circuit (DC power supply circuit)
2 Full bridge circuit (polarity inversion circuit)
３ Control circuit
20 Color filter 21 Main control circuit 30 High pressure discharge lamp lighting device 33 Data table La High pressure discharge lamp Ss Synchronization signal t1 Time limit

Claims (7)

  DC power supply circuit with variable output, polarity inversion circuit that applies alternating voltage generated from output of DC power supply circuit to high-pressure discharge lamp, and output of DC power supply circuit at the timing based on the synchronization signal given by synchronization signal from outside And a control circuit for controlling the timing of polarity reversal by the polarity reversing circuit, and the control circuit inverts the polarity of the voltage applied to the high-pressure discharge lamp for each synchronization signal and the polarity of the voltage applied to the high-pressure discharge lamp. Is selected from a specified value at which the high-pressure discharge lamp is lit and an increased value larger than the specified value, and when an increased value is selected as the lamp current, The period during which the polarity of the voltage applied to the high-pressure discharge lamp is reversed within the period between the synchronization signals and the lamp current is increased within the period High-pressure discharge lamp lighting device characterized in that it is set shorter than would period.   The high pressure discharge lamp lighting device according to claim 1, wherein the ratio between the specified value and the increased value is constant regardless of a lamp voltage.   The control circuit time-limits a time limit longer than the time interval to which the synchronization signal is applied every time the synchronization signal is applied, and when the time limit of the time limit ends without a synchronization signal being applied during the time limit of the time limit 3. The high pressure discharge lamp lighting device according to claim 1, wherein the lamp current and the polarity of the voltage are controlled according to a preset control pattern.   An image display device comprising the high pressure discharge lamp lighting device according to any one of claims 1 to 3, wherein the high pressure discharge lamp is used as a light source.   A color filter that has a plurality of color regions and periodically transmits the light from the high-pressure discharge lamp to each color region over time, and the timing at which the light from the high-pressure discharge lamp passes through each color region of the color filter. A main control circuit for generating the synchronization signal, the control circuit as a period of one cycle of color change of the color filter, a period for inverting the polarity of the voltage applied to the high-pressure discharge lamp an odd number of times, and a high-pressure discharge lamp The image display apparatus according to claim 4, wherein periods for reversing the voltage applied to the even number of times are alternately provided.   The image display apparatus according to claim 4, wherein light is not projected at least during a period in which the lamp current is an increase value.   A color filter that has a plurality of color regions and periodically transmits the light from the high-pressure discharge lamp to each color region over time, and the timing at which the light from the high-pressure discharge lamp passes through each color region of the color filter. And a main control circuit for generating the synchronization signal, wherein the control circuit inverts the polarity of the voltage applied to the high-pressure discharge lamp an odd number of times during one period of color change of the color filter. 6. The image display device according to 6.

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