JP5874846B2 - Discharge lamp driving device and driving method, light source device, and image display device - Google Patents

Description

  The present invention relates to a driving technique for a discharge lamp that is lit by discharge between electrodes.

  As a light source used for an image display device such as a projector, a high-intensity discharge lamp such as a high-pressure gas discharge lamp is used. In such a high-intensity discharge lamp, the deterioration of the electrode proceeds with energization. When the electrode deteriorates, there is a risk of arc jump or flicker that moves the light arc generation position. Normally, when the electrodes deteriorate, the voltage between the electrodes (lamp voltage) increases. Therefore, the lamp voltage is detected, the driving condition (power feeding condition) of the high-intensity discharge lamp is changed based on the detected lamp voltage, and the deteriorated electrode is repaired.

US Pat. No. 6,232,725

  However, the power supply condition (high voltage side power supply condition) used in a state where the lamp voltage is higher is suitable for repairing the electrode. However, if the driving is continued under this condition for a long period of time, it causes a harmful effect such as blackening. There is a fear. In addition, the power supply condition (low voltage side power supply condition) used in a state where the lamp voltage is lower does not cause a negative effect such as blackening, but the deterioration of the electrode proceeds slowly. This problem is not limited to high-intensity discharge lamps, but is common to various discharge lamps (discharge lamps) that emit light by arc discharge between electrodes.

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a technique for suppressing deterioration of a discharge lamp without causing adverse effects such as blackening.

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.
[Form 1]
A discharge lamp driving device comprising:
By supplying an alternating current to the discharge lamp, a discharge lamp lighting unit that turns on the discharge lamp by supplying power between two electrodes of the discharge lamp;
An interelectrode voltage detector for detecting an interelectrode voltage when a predetermined power is supplied between the two electrodes;
Based on the detected interelectrode voltage, power supply by the discharge lamp lighting unit is performed between a first power supply condition and a second power supply condition different from the first power supply condition, and the second power supply condition. A power supply condition switching unit that switches between a first power supply condition and a third power supply condition different from the first power supply condition with a predetermined hysteresis;
With
Each of the power supply conditions is as follows:
It is switched by changing at least one of the frequency of the alternating current, the duty ratio of the alternating current, the modulation pattern of the frequency, and the modulation pattern of the duty ratio,
In order from the lowest detected interelectrode voltage, the first power supply condition, the second power supply condition, and the third power supply condition,
The hysteresis width for switching between the second power feeding condition and the third power feeding condition is larger than the hysteresis width for switching between the first power feeding condition and the second power feeding condition,
A driving device for a discharge lamp.
According to this configuration, since the power supply conditions can be switched in more detail, the deterioration of the discharge lamp can be suppressed more appropriately. In a state where switching from the third power supply condition to the second power supply condition can occur by increasing the hysteresis width in a state where the voltage between the electrodes where deterioration of the discharge lamp tends to proceed is high, the second power supply condition Switching to is further suppressed, and the driving time under the third power supply condition becomes longer. In this configuration, since the drive time under the third power supply condition in a state where the switching to the second power supply condition can occur as described above can be made longer, the protrusion can be more reliably repaired. Deterioration of the discharge lamp is suppressed.
[Form 2]
A discharge lamp driving device comprising:
By supplying an alternating current to the discharge lamp, a discharge lamp lighting unit that turns on the discharge lamp by supplying power between two electrodes of the discharge lamp;
An interelectrode voltage detector for detecting an interelectrode voltage when a predetermined power is supplied between the two electrodes;
Based on the detected interelectrode voltage, power supply by the discharge lamp lighting unit is provided with a predetermined hysteresis between a first power supply condition and a second power supply condition different from the first power supply condition. Power supply condition switching unit to be switched,
With
The power supply conditions are switched by changing at least one of the frequency of the alternating current, the duty ratio of the alternating current, the modulation pattern of the frequency, and the modulation pattern of the duty ratio,
The power supply condition switching unit is a discharge lamp driving device that changes a width of the hysteresis based on a usage time of the discharge lamp.
If the discharge lamp is used for a long period of time, the shape of the electrode is rough due to a change with time, and it is difficult to melt the tip of the electrode, and it may be difficult to recover the shape of the electrode. Therefore, if the hysteresis width is increased to a predetermined width according to the usage time of the discharge lamp, the shape of the electrode can be sufficiently recovered.
[Form 3]
A discharge lamp driving device according to Aspect 2,
The power feeding condition switching unit is a discharge lamp driving device that increases a width of the hysteresis when a usage time of the discharge lamp reaches a predetermined time.

[Application Example 1]
A discharge lamp driving device comprising:
By supplying an alternating current to the discharge lamp, a discharge lamp lighting unit that turns on the discharge lamp by supplying power between two electrodes of the discharge lamp;
An interelectrode voltage detector for detecting an interelectrode voltage when a predetermined power is supplied between the two electrodes;
Based on the detected interelectrode voltage, power supply by the discharge lamp lighting unit is provided with a predetermined hysteresis between a first power supply condition and a second power supply condition different from the first power supply condition. Power supply condition switching unit to be switched,
With
Each of the power supply conditions is switched by changing at least one of the frequency of the alternating current, the duty ratio of the alternating current, the modulation pattern of the frequency, and the modulation pattern of the duty ratio. Drive device.

  According to this configuration, the power supply condition is switched based on the voltage between the electrodes when predetermined power is supplied between the two electrodes. Since the interelectrode voltage when a predetermined power is supplied between the two electrodes is one parameter representing the deterioration state of the discharge lamp, the discharge lamp is based on the interelectrode voltage detected by the interelectrode voltage detector. By switching to a power supply condition that suppresses the deterioration of the discharge lamp, it is possible to appropriately suppress the deterioration of the discharge lamp. Further, by providing hysteresis for the switching, it is possible to suppress frequent switching of power supply conditions and perform stable power supply control.

  The frequency and duty ratio of the alternating current are parameters that can be easily set by a general inverter circuit. Therefore, the frequency, the duty ratio, and the modulation patterns can be changed by using a general inverter circuit, so that the configuration of the discharge lamp driving device becomes easier.

[Application Example 2]
A discharge lamp driving device according to Application Example 1,
The power supply condition switching unit
A discharge lamp driving device that changes a width of the hysteresis according to a predetermined parameter based on an electrical behavior of the discharge lamp.

  The electrical behavior of the discharge lamp varies depending on the state of the electrode of the discharge lamp. Therefore, for example, if the second power supply condition is more suitable for restoring the shape of the electrode than the first power supply condition, the parameter based on the electrical behavior of the discharge lamp is In this case, if the hysteresis width is increased, the shape of the electrode can be sufficiently recovered under the second power feeding condition, so that the deterioration of the discharge lamp can be appropriately suppressed.

[Application Example 3]
A discharge lamp driving device according to Application Example 2,
The discharge lamp driving apparatus, wherein the parameter based on the electrical behavior of the discharge lamp is a fluctuation range of the interelectrode voltage detected by the interelectrode voltage detection unit.

  The fluctuation range of the voltage between the electrodes of the discharge lamp varies depending on the state of the electrodes of the discharge lamp. That is, the fluctuation range of the voltage between the electrodes of the discharge lamp can be said to be one parameter representing the state (deterioration) of the electrodes of the discharge lamp. Therefore, for example, if the second power supply condition is more suitable for recovering the shape of the electrode than the first power supply condition, the fluctuation width of the voltage between the electrodes may deteriorate the electrode of the discharge lamp. In this case, if the hysteresis width is increased, the shape of the electrode can be sufficiently recovered under the second power supply condition, so that the deterioration of the discharge lamp can be appropriately suppressed.

[Application Example 4]
A discharge lamp driving device according to Application Example 3,
The power supply condition switching unit
The discharge lamp driving device, wherein the hysteresis width is increased as the fluctuation width of the interelectrode voltage is increased.

  In the discharge lamp, when the tip shape of the electrode is rough (that is, when it deteriorates), the fluctuation range of the voltage between the electrodes may increase. For example, if the second power supply condition is more suitable for recovering the shape of the electrode than the first power supply condition, the hysteresis width is increased as the fluctuation range of the interelectrode voltage is larger. In this case, since the shape of the electrode can be sufficiently recovered under the second power supply condition, deterioration of the discharge lamp can be appropriately suppressed.

[Application Example 5]
A discharge lamp driving device according to Application Example 2,
The discharge lamp driving apparatus, wherein the parameter based on the electrical behavior of the discharge lamp is electric power supplied between the two electrodes of the discharge lamp by the discharge lamp lighting unit.

  In the discharge lamp, the degree of change in the electrode shape varies depending on the electric power supplied between the two electrodes. Therefore, for example, if the second power supply condition is more suitable for recovering the shape of the electrode than the first power supply condition, the power supplied between the two electrodes is If the electrode is at a power level that easily deteriorates, if the hysteresis width is increased, the shape of the electrode can be sufficiently recovered under the second power supply condition, so that the deterioration of the discharge lamp can be appropriately suppressed. .

[Application Example 6]
A discharge lamp driving device according to Application Example 5,
The power supply condition switching unit
The discharge lamp driving device, wherein the hysteresis is increased as the electric power supplied between the two electrodes of the discharge lamp is smaller.

  The discharge lamp may have a rougher electrode shape as the power supplied between the two electrodes is smaller. For example, if the second power supply condition is more suitable for recovering the shape of the electrode than the first power supply condition, the smaller the power supplied between the two electrodes of the discharge lamp, If the width of the hysteresis is increased, the shape of the electrode can be sufficiently recovered under the second power supply condition, so that the deterioration of the discharge lamp can be appropriately suppressed.

[Application Example 7]
A discharge lamp driving device according to Application Example 1,
The power supply condition switching unit
Based on the detected interelectrode voltage, power supply by the discharge lamp lighting unit has a predetermined hysteresis between the second power supply condition and a third power supply condition different from the first power supply condition. Switch the discharge lamp drive.

  According to this configuration, since the power supply conditions can be switched in more detail, the deterioration of the discharge lamp can be suppressed more appropriately.

[Application Example 8]
A discharge lamp driving device according to Application Example 7,
Each of the power supply conditions is a first power supply condition, a second power supply condition, and a third power supply condition in descending order of the detected interelectrode voltage,
The discharge lamp driving device, wherein a hysteresis width for switching between the second power feeding condition and the third power feeding condition is larger than a hysteresis width for switching between the first power feeding condition and the second power feeding condition.

  In a state where switching from the third power supply condition to the second power supply condition can occur by increasing the hysteresis width in a state where the voltage between the electrodes where deterioration of the discharge lamp tends to proceed is high, the second power supply condition Switching to is further suppressed, and the driving time under the third power supply condition becomes longer. In this configuration, since the drive time under the third power supply condition in a state where the switching to the second power supply condition can occur as described above can be made longer, the protrusion can be more reliably repaired. Deterioration of the discharge lamp is suppressed.

[Application Example 9]
A discharge lamp driving device according to Application Example 1,
The power supply condition switching unit
The power supply condition for the power supplied between the two electrodes is changed from the first power supply condition to the first power supply condition when the voltage between the electrodes rises and reaches a first upper limit voltage under the first power supply condition. When the power supply condition is switched to 2 and the voltage between the electrodes decreases under the second power supply condition and reaches a second lower limit voltage lower than the first upper limit voltage, the second power supply condition is A discharge lamp driving device that switches to the first power supply condition.

  According to this configuration, switching from the second power supply condition to the first power supply condition is performed when the second lower limit voltage lower than the first upper limit voltage is reached. Therefore, when the voltage between the electrodes decreases under the second power supply condition, the first power supply condition is switched after the voltage between the electrodes is sufficiently decreased, and the second power supply after switching to the first power supply condition. Switching to the condition is suppressed. When the load on the discharge lamp is small compared to the second power supply condition in the first power supply condition, the second power supply condition after the power supply condition returns to the first power supply condition in this way. When the switching is suppressed, the driving time under the first power supply condition becomes long, and the deterioration of the discharge lamp is suppressed without causing adverse effects such as blackening of the electrodes of the discharge lamp.

[Application Example 10]
A discharge lamp driving device according to Application Example 7,
The power supply condition switching unit
The power supply condition for the power supplied between the two electrodes is changed from the second power supply condition to the first power supply voltage when the voltage between the electrodes rises and reaches a second upper limit voltage under the second power supply condition. When the third power supply condition is switched and the interelectrode voltage decreases under the third power supply condition and reaches a third lower limit voltage lower than the second upper limit voltage, the third power supply condition starts. A discharge lamp driving device that switches to the second power supply condition.

  According to this application example, when the inter-electrode voltage increases under the second power supply condition and reaches the second upper limit voltage, the power supply condition is switched to the third power supply condition. The switching from the third power supply condition to the second power supply condition is performed when the third lower limit voltage lower than the second upper limit voltage is reached. Therefore, when the voltage between the electrodes decreases under the third power supply condition, the second power supply condition is switched after the voltage between the electrodes is sufficiently decreased, and the third power supply after switching to the second power supply condition. Switching to the condition is suppressed. As described above, since the switching to the third power supply condition after the power supply condition returns to the second power supply condition is suppressed, the driving time under the second power supply condition is lengthened, and there is an adverse effect such as blackening. The deterioration of the discharge lamp is suppressed without causing

  Note that the present invention can be realized in various modes. For example, the present invention can be realized in aspects such as a discharge lamp driving device and driving method, a light source device using a discharge lamp and its control method, an image display device using the light source device, and the like.

1 is a schematic configuration diagram of a projector to which a first embodiment of the present invention is applied. Explanatory drawing which shows the structure of a light source device. The block diagram which shows the structure of a discharge lamp drive device. Explanatory drawing which shows a mode that the duty ratio of alternating current pulse current is modulated. Explanatory drawing which shows a mode that an anode duty ratio is modulated and a discharge lamp is driven. The flowchart which shows the setting process of the electric power feeding condition in 1st Example. The table | surface which shows the content of the power supply condition setting table referred when a power supply condition setting part performs the setting process of power supply conditions. Explanatory drawing which shows a mode that a power supply condition is set according to a lamp voltage by the setting process of the power supply condition of FIG. Explanatory drawing which shows the influence which the raise of an anode duty ratio has with respect to an electrode. The table | surface which shows the content of the electric power feeding condition setting table in 2nd Example. Explanatory drawing which shows a mode that power supply conditions are set according to a lamp voltage with reference to the power supply condition setting table shown in FIG. The table | surface which shows the content of the electric power feeding condition setting table in 3rd Example. Explanatory drawing which shows a mode that power supply conditions are set according to a lamp voltage with reference to the power supply condition setting table shown in FIG.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First Example (Example in which the duty ratio modulation range is switched):
B. Second Example (Example in which the hysteresis width is changed according to the lamp voltage):
C. Third embodiment (embodiment for switching the driving frequency):
D. Variations:

A. First Example (Example in which the duty ratio modulation range is switched):
FIG. 1 is a schematic configuration diagram of a projector 1000 to which the first embodiment of the present invention is applied. The projector 1000 includes a light source device 100, an illumination optical system 310, a color separation optical system 320, three liquid crystal light valves 330R, 330G, and 330B, a cross dichroic prism 340, and a projection optical system 350.

  The light source device 100 includes a light source unit 110 to which a discharge lamp 500 is attached, and a discharge lamp driving device 200 that drives the discharge lamp 500. The discharge lamp 500 receives electric power from the discharge lamp driving device 200 and discharges to emit light. The light source unit 110 emits the emitted light from the discharge lamp 500 toward the illumination optical system 310. Note that specific configurations and functions of the light source unit 110 and the discharge lamp driving device 200 will be described later.

  The light emitted from the light source unit 110 is made uniform in illuminance by the illumination optical system 310 and the polarization direction is aligned in one direction. The light whose illumination intensity is uniformed and the polarization direction is aligned through the illumination optical system 310 is separated into three color lights of red (R), green (G) and blue (B) by the color separation optical system 320. . The three color lights separated by the color separation optical system 320 are modulated by the corresponding liquid crystal light valves 330R, 330G, and 330B. The three color lights modulated by the liquid crystal light valves 330R, 330G, and 330B are combined by the cross dichroic prism 340 and enter the projection optical system 350. The projection optical system 350 projects the incident light onto a screen (not shown), so that an image is displayed on the screen as a full-color image in which images modulated by the liquid crystal light valves 330R, 330G, and 330B are combined. . In the first embodiment, the three color light beams are separately modulated by the three liquid crystal light valves 330R, 330G, and 330B. However, the light may be modulated by one liquid crystal light valve having a color filter. Good. In this case, the color separation optical system 320 and the cross dichroic prism 340 can be omitted.

  FIG. 2 is an explanatory diagram showing the configuration of the light source device 100. The light source device 100 has the light source unit 110 and the discharge lamp driving device 200 as described above. The light source unit 110 includes a discharge lamp 500, a main reflecting mirror 112 having a spheroidal reflecting surface, and a collimating lens 114 that makes emitted light substantially parallel. However, the reflecting surface of the main reflecting mirror 112 does not necessarily need to be a spheroid. For example, the reflecting surface of the main reflecting mirror 112 may be a paraboloid. In this case, if the light emitting part of the discharge lamp 500 is placed at the so-called focal point of the parabolic mirror, the collimating lens 114 can be omitted. The main reflecting mirror 112 and the discharge lamp 500 are bonded with an inorganic adhesive 116.

  The discharge lamp 500 is formed by adhering a discharge lamp main body 510 and a sub-reflecting mirror 520 having a spherical reflecting surface with an inorganic adhesive 522. The discharge lamp main body 510 is made of a glass material such as quartz glass, for example. The discharge lamp main body 510 is provided with two electrodes 532 and 542 made of a high melting point metal material such as tungsten, two connection members 534 and 544, and two electrode terminals 536 and 546. . The electrodes 532 and 542 are arranged so that the tip portions thereof are opposed to each other in a discharge space 512 formed in the center portion of the discharge lamp main body 510. The discharge space 512 is filled with a gas containing a rare gas, mercury, a metal halide compound, or the like as a discharge medium. The connection members 534 and 544 are members that electrically connect the electrodes 532 and 542 and the electrode terminals 536 and 546, respectively.

  The electrode terminals 536 and 546 of the discharge lamp 500 are connected to the output terminals of the discharge lamp driving device 200, respectively. The discharge lamp driving device 200 supplies a pulsed alternating current (alternating pulse current) to the electrode terminals 536 and 546. When an AC pulse current is supplied to the electrode terminals 536 and 546, an arc AR is generated between the tips of the two electrodes 532 and 542 in the discharge space 512. The arc AR radiates light in all directions from the generation position of the arc AR. The sub-reflecting mirror 520 reflects the light emitted in the direction of the one electrode 542 toward the main reflecting mirror 112. Thus, by reflecting the light emitted in the direction of the electrode 542 toward the main reflecting mirror 112, the parallelism of the light emitted from the light source unit 110 can be further increased. Hereinafter, the electrode 542 on the side where the sub-reflecting mirror 520 is provided is also referred to as a “sub-mirror side electrode 542”, and the other electrode 532 is also referred to as a “primary mirror-side electrode 532”.

  FIG. 3 is a block diagram illustrating a configuration of the discharge lamp driving device 200. The discharge lamp driving device 200 includes a drive control unit 210 and a lighting circuit 220. The drive control unit 210 is a computer including a CPU 610, a ROM 620, a RAM 630, a timer 640, an output port 650 that outputs a control signal to the lighting circuit 220, and an input port 660 that acquires a signal from the lighting circuit 220. It is configured. The ROM 620 stores a program (not shown) executed by the CPU 610 and a power supply condition setting table 622. The CPU 610 of the drive control unit 210 refers to the power supply condition setting table 622 and executes a program stored in the ROM 620 based on the output of the timer 640. Thereby, the CPU 610 realizes the functions of the power supply state control unit 612 and the power supply condition setting unit 614. The contents of the power supply condition setting table 622 and the functions of the power supply state control unit 612 and the power supply condition setting unit 614 will be described later.

  The lighting circuit 220 includes an inverter 222 that generates an AC pulse current. The lighting circuit 220 supplies a constant power (for example, 200 W) alternating current pulse current to the discharge lamp 500 by controlling the inverter 222 based on a control signal supplied from the drive control unit 210 via the output port 650. To do. Specifically, the lighting circuit 220 controls the inverter 222 to generate an AC pulse current corresponding to a power supply condition (for example, AC pulse current frequency, duty ratio, and current waveform) specified by the control signal. To generate. The lighting circuit 220 supplies the AC pulse current generated by the inverter 222 to the discharge lamp 500.

  Further, the lighting circuit 220 detects the voltage between the electrodes 532 and 542 of the discharge lamp 500 and outputs it as a lamp voltage. In the present embodiment, the voltage between the electrodes 532 and 542 is directly detected. However, as long as the parameter reflects the voltage between the electrodes, other parameters may be detected and handled as the voltage between the electrodes. For example, the voltage may be obtained from the power consumption and current value of the discharge lamp, or the voltage can be estimated from the current value and the brightness of the discharge lamp.

  In the first embodiment, the power supply state control unit 612 of the drive control unit 210 modulates the duty ratio of the AC pulse current within a preset modulation period (for example, 200 seconds). FIG. 4 is an explanatory diagram showing how the duty ratio of the AC pulse current is modulated. The graph of FIG. 4 shows the time change of the anode duty ratios Dam and Das. Here, the anode duty ratios Dam and Das are ratios of time (anode time) in which each of the two electrodes 532 and 542 operates as an anode with respect to one cycle of the AC pulse current. In the graph of FIG. 4, the solid line indicates the anode duty ratio Dam of the primary mirror side electrode 532, and the broken line indicates the anode duty ratio Das of the secondary mirror side electrode 542.

  In the example of FIG. 4, the power supply state control unit 612 (FIG. 3) has a predetermined change width ΔD (2%) every time a step time Ts (10 seconds) that is 1/20 of the modulation period Tm (200 seconds) has elapsed. ) To change the anode duty ratios Dam and Das. As described above, by modulating the anode duty ratios Dam and Das within the modulation period Tm, it is possible to suppress uneven wear of the electrode and abnormal discharge due to the growth of needle-like crystals of the electrode material on the electrode surface. . In the first embodiment, the modulation period Tm is 200 seconds and the step time Ts is 10 seconds. However, the modulation period Tm and the step time Ts can be changed as appropriate based on the characteristics of the discharge lamp 500, power supply conditions, and the like.

  As is apparent from FIG. 4, in the first embodiment, the maximum value of the anode duty ratio Dam of the primary mirror side electrode 532 is set to be higher than the maximum value of the anode duty ratio Das of the secondary mirror side electrode 542. ing. However, the maximum value of the anode duty ratio of the two electrodes 532 and 542 is not necessarily different. However, when the maximum value of the anode duty ratio is increased, the maximum temperature of the electrodes 532 and 542 is increased as will be described later. On the other hand, when the discharge lamp 500 having the sub-reflecting mirror 520 is used as shown in FIG. 2, the heat from the sub-mirror side electrode 542 becomes difficult to be released. Therefore, setting the maximum value of the anode duty ratio Das of the secondary mirror side electrode 542 to be lower than the maximum value of the anode duty ratio Dam of the primary mirror side electrode 532 can suppress an excessive temperature rise of the secondary mirror side electrode 542. And more preferable. In general, when the two electrodes 532 and 542 are driven under the same operating conditions, if the temperature of one electrode becomes higher than the temperature of the other electrode due to the influence of the cooling method or the like, the anode of the one electrode It is more preferable that the duty ratio is lower than the other anode duty ratio.

  In the first embodiment, the anode duty ratio Dam of the primary mirror side electrode 532 is increased for each step time Ts in the first half of the modulation period Tm, and is decreased for each step time Ts in the second half. However, the change pattern of the anode duty ratios Dam and Das is not necessarily limited to this. For example, the anode duty ratio Dam of the primary mirror side electrode 532 may be monotonously increased or may be monotonously decreased within the modulation period Tm.

  FIG. 5 is an explanatory diagram showing a state in which the discharge lamp 500 is driven by modulating the anode duty ratio. FIG. 5A is different from FIG. 4 in that the temporal change of the anode duty ratios Dam and Das is shown only for one modulation period (1 Tm). The other points are almost the same as those in FIG. FIG. 5B shows the main period in three periods T1 to T3 in which the anode duty ratio Dam of the primary mirror side electrode 532 is set to different values (45%, 55%, 65%) in FIG. 5 is a graph showing a change over time in the operating state of a mirror side electrode 532;

  As shown in FIG. 5B, the switching period Tp in which the polarity of the primary mirror side electrode 532 is switched is constant in any of the three periods T1 to T3 having different anode duty ratios Dam. Thus, in the first embodiment, the frequency (fd = 1 / Tp) of the AC pulse current is set to a constant frequency (for example, 80 Hz) over the entire period of the modulation period Tm. On the other hand, the anode times Ta1 to Ta3 of the primary mirror side electrode 532 are set to different values in the periods T1 to T3 in which the anode duty ratio Dam is different. As described above, in the first embodiment, the anode duty ratio Dam is modulated by changing the anode time Ta while keeping the frequency fd of the AC pulse current (hereinafter also referred to as “drive frequency fd”) constant. Done.

  In the first embodiment, the power supply condition setting unit 614 (FIG. 3) of the drive control unit 210 supplies power to the discharge lamp 500 based on the lamp voltage of the discharge lamp 500 and the power supply condition setting table 622 stored in the ROM 620. Set conditions. Here, the lamp voltage is a voltage between the electrodes 532 and 542 when the discharge lamp 500 is driven with a constant power, and is one parameter representing a deterioration state of the discharge lamp 500. Specifically, the power supply condition setting unit 614 refers to the power supply condition setting table 622 based on the lamp voltage acquired via the input port 660 and sets the range of the anode duty ratio (modulation) set within the modulation cycle Tm. Range). A method for setting the power supply condition (anode duty ratio modulation range) by the power supply condition setting unit 614 will be described later.

  The power supply state control unit 612 controls the lighting circuit 220 based on the modulation range set by the power supply condition setting unit 614 so that the anode duty ratio is changed every step time Ts. The modulation range is changed by changing the change width ΔD of the anode duty ratios Dam and Das for each step time Ts.

  FIG. 6 is a flowchart showing a power supply condition setting process in the first embodiment. This power supply condition setting process is always executed while the discharge lamp driving device 200 is driving the discharge lamp 500 in a steady state.

  FIG. 7 is a table showing the contents of the power supply condition setting table 622 that is referred to when the power supply condition setting unit 614 performs the power supply condition setting process. In the power supply condition setting table 622, the lower and upper thresholds of the lamp voltage serving as a reference for switching the power supply conditions and the power supply conditions to be set, that is, the anode duty of the primary mirror side electrode 532, corresponding to each of the power supply conditions. The minimum value and the maximum value of the ratio Dam are stored. In the power supply condition setting table 622 in FIG. 7, four power supply conditions (# 1 to # 4) are defined according to the lamp voltage, but the number of power supply conditions is any number as long as it is two or more. Can do. Hereinafter, of the two power supply conditions, a power supply condition corresponding to a lower lamp voltage is also referred to as a “low voltage side power supply condition”, and a power supply condition corresponding to a higher lamp voltage is also referred to as a “high voltage side power supply condition”. Call. For example, among the first and second power supply conditions (# 1, # 2), the first power supply condition (# 1) is also called a low voltage side power supply condition, and the second power supply condition (# 2) is a high voltage. Also called side power supply conditions.

  In the example of FIG. 7, the modulation range of the anode duty ratio is defined in the power supply condition setting table 622 by the minimum value and the maximum value of the anode duty ratio Dam, but the modulation range of the anode duty ratio is defined by other parameters. You can also. The modulation range of the anode duty ratio can be defined by the maximum value or the minimum value of the anode duty ratios Dam and Das of the primary mirror side electrode 532 and the secondary mirror side electrode 542, for example. Also, the modulation range can be defined by the change width ΔD of the anode duty ratios Dam and Das for each step time Ts.

  In step S110, the power supply condition setting unit 614 obtains a lamp voltage threshold value corresponding to the currently set power supply condition. Specifically, the power supply condition setting unit 614 refers to the power supply condition setting table 622 (FIG. 7), and sets the lower threshold value (lower threshold voltage) of the lamp voltage corresponding to the currently set power supply condition. The upper threshold value (upper threshold voltage) is acquired.

  In step S120, the power supply condition setting unit 614 acquires a lamp voltage (detected lamp voltage) from the lighting circuit 220 connected via the input port 660.

  In step S130, the power supply condition setting unit 614 determines whether or not the detected lamp voltage acquired in step S120 is equal to or higher than the upper threshold voltage. If the detected lamp voltage is greater than or equal to the upper threshold voltage, the process proceeds to step S140. If the detected lamp voltage is lower than the upper threshold voltage, the process proceeds to step S150.

  In step S140, the power supply condition setting unit 614 changes the power supply condition to the one-stage high voltage side power supply condition. As shown in FIG. 7, in the power supply condition of the first embodiment, the maximum value of the anode duty ratio increases as the lamp voltage increases. Therefore, in step S140, the maximum value of the anode duty ratio is set to a higher value than before the change. After changing the power supply condition in step S140, the process returns to step S110.

  In step S150, the power supply condition setting unit 614 determines whether or not the detected lamp voltage acquired in step S120 is equal to or lower than the lower threshold voltage. If the detected lamp voltage is equal to or lower than the lower threshold voltage, the process proceeds to step S160. If the detected lamp voltage is higher than the lower threshold voltage, the process returns to step S110.

  In step S <b> 160, the power supply condition setting unit 614 changes the power supply condition to a power supply condition where the lamp voltage is one step low voltage side. As described above, in the power supply condition of the first embodiment, the maximum value of the anode duty ratio increases as the lamp voltage increases. Therefore, in step S160, the maximum value of the anode duty ratio is set to a lower value than before the change. After changing the power supply condition in step S160, the process returns to step S110.

  In this manner, the power supply condition setting unit 614 continuously executes the power supply condition setting process while the discharge lamp 500 is being driven steadily by repeatedly executing the steps after step S110 in FIG. However, the power supply condition setting process does not necessarily need to be continuously executed. For example, the timer 640 (FIG. 3) is configured to generate an interval signal each time a lighting time of the discharge lamp 500 elapses a predetermined time (for example, 10 hours), and power is supplied when the CPU 610 receives the interval signal. A condition setting process may be executed. In this case, the process ends without returning to step S110.

  As is clear from the flowchart shown in FIG. 6, the power supply condition setting unit 614 switches the power supply condition according to the detected lamp voltage. Therefore, the power supply condition setting unit 614 can also be referred to as a “power supply condition switching unit” that switches power supply conditions. Further, the upper threshold voltage and the lower threshold voltage are upper limit and lower limit voltages that are continuously used in power supply conditions, and can also be referred to as “upper limit voltage” and “lower limit voltage”, respectively.

  FIG. 8 is an explanatory diagram showing how the power supply conditions are set according to the lamp voltage by the power supply condition setting process of FIG. In the graph of FIG. 8, the horizontal axis indicates the lamp voltage Vp, and the vertical axis indicates the maximum value of the anode duty ratio Dam of the main mirror side electrode 532.

  When the discharge lamp 500 is driven under the first power supply condition (# 1), the upper threshold voltage is set to 82V. Therefore, when the currently set power supply condition is the first power supply condition (# 1), the discharge lamp 500 has the anode duty ratio Dam of the main mirror side electrode 532 until the lamp voltage Vp reaches 82V. Is driven to a maximum value of 65%. When the lamp voltage Vp reaches 82 V, the power supply condition to be used is switched to the second power supply condition (# 2), and the maximum value of the anode duty ratio Dam of the primary mirror side electrode 532 is 65% to 70%. Changed to

  When the power supply condition is switched to the second power supply condition (# 2), the upper threshold voltage is set to 92V and the lower threshold voltage is set to 78V. In the second power supply condition (# 2), the maximum value of the anode duty ratio Dam of the primary mirror side electrode 532 is changed to 70%. Thus, the maximum value of the anode duty ratio Dam of the primary mirror side electrode 532 under the second power supply condition (# 2) is set higher than the maximum value (65%) of the anode duty ratio Dam under the first power supply condition. Has been. Further, as shown in FIG. 7, the minimum value of the anode duty ratio Dam of the main mirror side electrode 532 under the second power supply condition (# 2) is the minimum value of the anode duty ratio Dam under the first power supply condition (# 1). It is set to 40% lower than (45%). Therefore, the maximum value of the anode duty ratio Das of the secondary mirror side electrode 542 in the second power supply condition (# 2) is larger than the maximum value (55%) of the anode duty ratio Das in the first power supply condition (# 1). A high 60% is set.

  FIG. 9 is an explanatory diagram showing the effect of an increase in the anode duty ratio on the electrodes. FIG. 9A and FIG. 9B show the state of the primary mirror side electrode 532 in a state where the primary mirror side electrode 532 is operating as an anode. FIG. 9C is a graph showing the time change of the operating state of the primary mirror side electrode 532. FIG. 9D is a graph showing the change over time of the temperature of the primary mirror side electrode 532.

  In a state where the deterioration of the discharge lamp 500 has not progressed, dome-shaped protrusions 538 and 548 are formed at the tip portions of the electrodes 532 and 542 toward the opposing electrodes, as indicated by broken lines in FIG. Has been. As the discharge lamp 500 is used, the electrode material evaporates from the dome-shaped protrusions 538 and 548, and the tips of the protrusions 538a and 548a are flattened as indicated by the solid line. If the tips of the protrusions 538a and 548a are smoothed in this way, the arc generation position becomes unstable, and there is a high possibility that a so-called arc jump in which the arc position moves during lighting will occur. In addition, the lamp voltage increases as the distance between the electrodes 532 and 542 increases. In the first embodiment, by increasing the anode duty ratio, the dome-shaped protrusions 538 and 548 are re-formed from the protrusions 538a and 548a thus flattened.

  As shown in FIGS. 9A and 9B, when the primary mirror side electrode 532 operates as an anode, electrons are emitted from the secondary mirror side electrode 542 and collide with the primary mirror side electrode 532. . Due to the collision of electrons, the kinetic energy of electrons is converted into thermal energy in the primary mirror side electrode 532 on the anode side, and the temperature of the primary mirror side electrode 532 rises. On the other hand, since no collision of electrons occurs in the secondary mirror side electrode 542 on the cathode side, the temperature of the secondary mirror side electrode 542 decreases due to heat conduction or radiation. Similarly, during the period when the primary mirror side electrode 532 operates as a cathode, the temperature of the primary mirror side electrode 532 decreases and the temperature of the secondary mirror side electrode 542 increases.

  Therefore, when the anode duty ratio of the primary mirror side electrode 532 is increased as shown in FIG. 9C, the time during which the temperature of the primary mirror side electrode 532 rises as shown in FIG. The time for the temperature of the primary mirror side electrode 532 to decrease is shortened. Thus, by increasing the anode duty ratio of the primary mirror side electrode 532, the maximum temperature of the primary mirror side electrode 532 becomes high. When the maximum temperature of the primary mirror side electrode 532 becomes high, as shown in FIG. 9B, a melted portion MR in which the electrode material is melted is generated at the tip of the protrusion 538. The melted portion MR in which the electrode material is melted has a dome shape due to surface tension.

  In the first embodiment, the maximum values of the anode duty ratios Dam and Das of the primary mirror side electrode 532 and the secondary mirror side electrode 542 in the second power supply condition (# 2) are the first power supply conditions (# 1). ) Is set higher. Therefore, dome-shaped protrusions 538 and 548 are re-formed at the two electrodes 532 and 542. This stabilizes the arc generation position and reduces the risk of arc jumps. Further, the dome-shaped protrusions 538 and 548 are formed again, so that the distance between the electrodes 532 and 542 is shortened and the lamp voltage Vp is lowered.

  As described above, when the discharge lamp 500 is driven under the second power supply condition (# 2) and the lamp voltage Vp decreases due to the formation of the dome-shaped protrusion, as shown in FIG. Is driven under the second power supply condition (# 2) until the voltage drops to 78V. Therefore, the dome-shaped protrusions 538 and 548 are sufficiently reformed (repaired). As described above, by sufficiently repairing the protrusions 538 and 548, an increase in the lamp voltage Vp is suppressed, and the drive time under the first power supply condition (# 1) can be further extended.

  On the other hand, when the lamp voltage Vp rises also in the second power supply condition (# 2), as shown in FIG. 8, when the lamp voltage Vp reaches 92V, the power supply condition is the second power supply condition (# 2). ) To the third power supply condition (# 3). When the lamp voltage Vp is reduced by driving under the third power supply condition (# 3) and the lamp voltage Vp is reduced to 88V, the power supply condition is changed from the third power supply condition (# 3) to the second power supply condition (# 3). To # 2).

  Similarly, when the lamp voltage Vp increases, when the lamp voltage Vp reaches 112V, the power supply condition is switched from the third power supply condition (# 3) to the fourth power supply condition (# 4). When the lamp voltage Vp decreases to 108V, the power supply condition is switched from the fourth power supply condition (# 4) to the third power supply condition (# 3).

  In the first embodiment, as shown in FIG. 7, when the lamp voltage increases between two power supply conditions, the lamp voltage (upper threshold voltage) at which the power supply condition is switched decreases. In this case, it is set higher than the lamp voltage (lower threshold voltage) at which the power supply condition is switched. For this reason, switching of the power supply condition with respect to the change in the lamp voltage is performed at different voltages when the lamp voltage increases and decreases, and as shown in FIG. 8, the power supply condition (primary mirror) set by the power supply condition setting unit 614 is set. The maximum value of the anode duty ratio Dam of the side electrode 532 has a hysteresis characteristic with respect to the lamp voltage Vp.

  As described above, since the power supply condition has a hysteresis characteristic with respect to the lamp voltage Vp, the lamp voltage Vp is lower than the lower threshold voltage even if the protrusions 538 and 548 at the electrode tip are repaired and the lamp voltage Vp is lowered. Until the voltage is lowered, the discharge lamp 500 is driven under a high-voltage power supply condition with a high effect of repairing the protrusions 538 and 548. Therefore, the protrusions 538 and 548 are sufficiently repaired under the power supply condition on the high voltage side, and the time during which driving is possible under the power supply condition on the low voltage side becomes longer. In general, driving under power supply conditions on the high voltage side has a great effect of repairing the electrodes. However, if the driving is continued for a long time, there is a risk of causing problems such as blackening. Therefore, it is possible to suppress deterioration of the discharge lamp 500 without causing adverse effects such as blackening by providing the power supply conditions with hysteresis characteristics with respect to the lamp voltage Vp and extending the drive time of the power supply conditions on the low voltage side. Is possible.

B. Second Example (Example in which the hysteresis width is changed according to the lamp voltage):
FIG. 10 is a table showing the contents of the power supply condition setting table 622 in the second embodiment. In the second embodiment, the contents of the power supply condition setting table 622 are different from those in the first embodiment. Other points are the same as the first embodiment.

  As shown in FIG. 10, the power supply condition setting table 622 of the second embodiment also includes lower and upper threshold values (lower threshold voltage and upper threshold voltage) of the lamp voltage corresponding to each of the plurality of power supply conditions. The modulation range of the anode duty ratio Dam of the primary mirror side electrode 532 as the power supply condition is stored. In the power supply condition setting table 622 of the second embodiment, the lower threshold voltage and the upper threshold voltage corresponding to the second to fourth power supply conditions (# 2 to # 4) are the same as those of the first embodiment shown in FIG. This is different from the power supply condition setting table 622. The other points are the same as the power supply condition setting table 622 of the first embodiment. As shown in FIG. 10, in the power supply condition setting table 622 of the second embodiment, the difference (hysteresis width) between the upper threshold voltage and the lower threshold voltage used for switching between the two power supply conditions increases the lamp voltage. It grows according to.

  FIG. 11 is an explanatory diagram illustrating a state in which the power supply condition is set according to the lamp voltage by referring to the power supply condition setting table 622 illustrated in FIG. 10. In the graph of FIG. 11, the horizontal axis indicates the lamp voltage Vp, and the vertical axis indicates the maximum value of the anode duty ratio Dam of the main mirror side electrode 532.

  As described above, in the second embodiment, the hysteresis width between the two power supply conditions increases as the power supply condition becomes higher. As described above, in the second embodiment, when the driving is performed under the power supply condition (# 3, # 4) corresponding to the state where the lamp voltage Vp is high, the lamp voltage at which the power supply condition is switched to the low voltage side is lower. Is set to the side. Therefore, in the state where the lamp voltage Vp is high, the protrusion is sufficiently repaired by driving under the power supply condition on the high voltage side, compared with the case where the hysteresis width is small. In general, a state in which the lamp voltage Vp is high is a state in which the discharge lamp 500 is used for a long time and it is more difficult to melt the tip than when the discharge lamp 500 is used. Therefore, as in the second embodiment, by increasing the hysteresis width as the lamp voltage Vp increases, the protrusions can be repaired more reliably and used after the repair even when it becomes difficult to melt the tip. The driveable time can be extended under the low voltage side power supply condition. Further, when the lamp voltage Vp is low, the switching to the power supply condition on the low voltage side is performed earlier. For this reason, it is possible to suppress the deterioration of the discharge lamp 500 due to driving under power supply conditions on the high voltage side.

  In the second embodiment, the upper threshold voltage and the lower threshold voltage are different values for all boundaries of the power supply condition. However, the upper threshold voltage and the lower threshold voltage are only determined for a part of the boundary of the power supply condition. And may be different values. In this case, regarding the boundary when the lamp voltage is low (for example, the boundary between the first and second power supply conditions), the upper threshold voltage and the lower threshold voltage are set to the same value, and the switching of the power supply condition has a hysteresis characteristic. It may not be.

  Further, depending on the power supply conditions to be switched, the hysteresis width in a state where the lamp voltage Vp is low may be larger than the hysteresis width in a state where the lamp voltage Vp is high. For example, the hysteresis width for switching between the first power supply condition and the second power supply condition may be larger than the hysteresis width for switching between the second power supply condition and the third power supply condition. Depending on the state of the electrode of the discharge lamp, the voltage between the electrodes may be lower than its rated value. In such a case, the first power supply condition is set so as to promote an increase in the interelectrode voltage. Therefore, when the driving time under the first power supply condition becomes long, the deterioration of the discharge lamp may progress. According to this configuration, by increasing the hysteresis width of power supply condition switching when the voltage between the electrodes is low, switching from the second power supply condition to the first power supply condition is further suppressed, and deterioration of the discharge lamp is suppressed. can do.

C. Third embodiment (embodiment for switching the driving frequency):
FIG. 12 is a table showing the contents of the power supply condition setting table 622 in the third embodiment. The third embodiment is different from the first embodiment in that the contents of the power supply condition setting table 622 are different from each other and in that the power supply conditions having different drive frequencies fd are used as a plurality of power supply conditions. Other points are the same as the first embodiment.

  As shown in FIG. 12, in the power supply condition setting table 622 of the third embodiment, the lower and upper thresholds (lower threshold voltage and upper threshold voltage) of the lamp voltage corresponding to each of the plurality of power supply conditions. The drive frequency fd as a power supply condition is stored. In the power supply condition setting table 622 of the third embodiment, similarly to the power supply condition setting table 622 of the first embodiment shown in FIG. 7, the hysteresis width at all boundaries of the power supply conditions is set to the same value (4 V). .

  In the third embodiment, as shown in FIG. 12, the drive frequency fd is set to increase as the lamp voltage increases. Therefore, when the power supply condition is switched from the low voltage side to the high voltage side, the drive frequency fd becomes higher than before the switching, and when the power supply condition is switched from the high voltage side to the low voltage side, the drive frequency fd is lower than before the switching. Become. Such a change in the drive frequency fd is performed by the power supply state control unit 612 (FIG. 3) giving an instruction to change the switching cycle Tp (FIG. 5) to the lighting circuit 220. In the third embodiment, the anode duty ratio Dam of the primary mirror side electrode 532 is 55%, and the anode duty ratio Das of the secondary mirror side electrode 542 is 45%. However, these anode duty ratios Dam and Das are not necessarily fixed, and may be modulated with a predetermined modulation period as shown in FIGS.

  In general, when the driving frequency fd of the discharge lamp 500 is increased, the protrusions 538 and 548 (FIG. 9) extend toward the electrodes 532 and 542 facing each other. For this reason, when the lamp voltage Vp becomes high, the extension of the protrusions 538 and 548 is promoted by increasing the drive frequency fd. Then, the protrusions 538 and 548 expand and the distance between the electrodes 532 and 542 becomes short, so that the lamp voltage Vp decreases. Further, the protrusions 538 and 548 extend, so that an arc is stably formed between the tips of the protrusions. Therefore, the occurrence of arc jump or the like can be suppressed by increasing the drive frequency fd.

  FIG. 13 is an explanatory diagram showing a state where the power supply condition is set according to the lamp voltage by referring to the power supply condition setting table 622 shown in FIG. In the graph of FIG. 13, the horizontal axis indicates the lamp voltage Vp, and the vertical axis indicates the drive frequency fd.

  Similar to the first embodiment, the drive frequency fd has a hysteresis characteristic with respect to the lamp voltage Vp. Therefore, the switching of the power supply condition from the high voltage side to the low voltage side is performed after the protrusions are sufficiently extended under the power supply condition on the high voltage side where the drive frequency fd is higher. Therefore, similarly to the first embodiment, the drive time under the power supply condition on the low voltage side can be made longer, and the discharge lamp 500 can be used for a longer period of time.

  In the third embodiment, the discharge lamp 500 is driven with a single drive frequency fd under each power supply condition (# 1 to # 4), but the drive frequency fd is modulated with a predetermined period. It is also possible. In this case, the anode duty ratios Dam and Das of the electrodes 532 and 542 may be modulated in accordance with the modulation of the drive frequency fd.

D. Variations:
In addition, this invention is not restricted to the said Example and embodiment, It can implement in a various aspect in the range which does not deviate from the summary, For example, the following deformation | transformation is also possible.

D1. Modification 1:
In each of the above embodiments, a rectangular pulse current is supplied to the discharge lamp, but the waveform of the AC pulse current supplied to the discharge lamp 500 is not necessarily rectangular. For example, the waveform of the AC pulse current may be a waveform in which a ramp wave is superimposed on a rectangular wave, or a waveform in which a rectangular pulse waveform is further superimposed on the rear end portion of the rectangular wave. However, it is more preferable that the AC pulse current is a rectangular wave in that fluctuations in the amount of light emitted by the discharge lamp 500 can be suppressed.

D2. Modification 2:
In each of the above embodiments, the liquid crystal light valves 330R, 330G, and 330B are used as the light modulation means in the projector 1000 (FIG. 1). However, as the light modulation means, DMD (digital micromirror device: trademark of Texas Instruments) is used. It is also possible to use any other modulation means such as In addition, the present invention can be applied to various image display devices including a liquid crystal display device, an exposure device, and an illumination device as long as the device uses a discharge lamp as a light source.

D3. Modification 3:
In the second embodiment, the hysteresis width is changed according to the lamp voltage. However, the hysteresis width may be changed based on the behavior of other discharge lamps. For example, the hysteresis width may be changed according to the fluctuation width of the lamp voltage. If the discharge lamp is used for a long period of time, the shape of the electrode may be rough due to a change with time, and the fluctuation range of the voltage between the electrodes may increase. Thus, if the shape of the electrode is rough, it becomes difficult to melt the tip of the electrode. Therefore, when the fluctuation range of the electrode voltage is large, the electrode shape can be sufficiently recovered by increasing the hysteresis width. In addition, when the fluctuation range of the electrode voltage is small, the electrode shape can be recovered relatively easily. Therefore, by reducing the hysteresis width, it is possible to suppress the adverse effects such as blackening of the electrode. As a whole, the deterioration of the discharge lamp can be suppressed. Increasing the hysteresis width when the fluctuation width of the interelectrode voltage is small is more effective in suppressing the deterioration of the discharge lamp.If the fluctuation width of the interelectrode voltage is small, increasing the hysteresis width Good.

  In addition, when the behavior of the discharge lamp changes according to the usage time of the discharge lamp, the hysteresis width may be changed based on the usage time of the discharge lamp. For example, when the usage time of the discharge lamp reaches 10,000 hours, the hysteresis width may be expanded to a predetermined width. As mentioned above, when the discharge lamp has been used for a long time, due to changes over time, the shape of the electrode becomes rough and it becomes difficult to melt the tip of the electrode, making it difficult to recover the shape of the electrode There is. Therefore, if the hysteresis width is increased to a predetermined width according to the usage time of the discharge lamp, the shape of the electrode can be sufficiently recovered.

  Further, the hysteresis width may be changed based on the power supplied between the two electrodes of the discharge lamp. There are cases where a plurality of discharge lamp drive modes are prepared in accordance with the supplied power. For example, when three types of modes, ie, a normal mode (200 W), a power saving mode (160 W), and a low noise mode (140 W) are prepared, the hysteresis width may be increased as the set power is lower. . When the set power is low, the tip shape of the electrode tends to be rough, and it may be difficult to recover the shape of the electrode. Therefore, the shape of the electrode can be sufficiently recovered by increasing the hysteresis width as the set power is lower. If the hysteresis width is increased as the set power is higher, the hysteresis width may be increased as the set power is higher.

DESCRIPTION OF SYMBOLS 100 ... Light source device 1000 ... Projector 110 ... Light source unit 112 ... Main reflecting mirror 114 ... Parallelizing lens 116 ... Inorganic adhesive 200 ... Discharge lamp drive device 2005 ... Unexamined-Japanese-Patent No. 210 ... Drive control part 220 ... Lighting circuit 222 ... Inverter 310 ... Illumination optical system 320 ... Color separation optical system 330R, 330G, 330B ... Liquid crystal light valve 340 ... Cross dichroic prism 350 ... Projection optical system 500 ... Discharge lamp 510 ... Discharge lamp body 512 ... Discharge space 520 ... Sub-reflecting mirror 522 ... Inorganic bonding Agents 532, 542 ... Electrodes 534, 544 ... Connection members 536, 546 ... Electrode terminals 538, 548 ... Projections 538a, 548a ... Projections 610 ... CPU
612 ... Power supply state control unit 614 ... Power supply condition setting unit 620 ... ROM
622 ... Power supply condition setting table 630 ... RAM
640 ... Timer 650 ... Output port 660 ... Input port AR ... Arc MR ... Melting zone

Claims (8)

A discharge lamp driving device comprising:
By supplying an alternating current to the discharge lamp, a discharge lamp lighting unit that turns on the discharge lamp by supplying power between two electrodes of the discharge lamp;
An interelectrode voltage detector for detecting an interelectrode voltage when a predetermined power is supplied between the two electrodes;
Based on the detected interelectrode voltage, power supply by the discharge lamp lighting unit is performed between a first power supply condition and a second power supply condition different from the first power supply condition , and the second power supply condition. A power supply condition switching unit that switches between a first power supply condition and a third power supply condition different from the first power supply condition with a predetermined hysteresis;
With
Each of the power supply conditions is as follows:
The frequency of the alternating current, and the duty ratio of the alternating current, a modulation pattern of the frequency switching et been by changing at least one of a modulation pattern of the duty ratio,
In order from the lowest detected interelectrode voltage, the first power supply condition, the second power supply condition, and the third power supply condition,
The hysteresis width for switching between the second power feeding condition and the third power feeding condition is larger than the hysteresis width for switching between the first power feeding condition and the second power feeding condition,
A driving device for a discharge lamp.   A discharge lamp driving device comprising:
  By supplying an alternating current to the discharge lamp, a discharge lamp lighting unit that turns on the discharge lamp by supplying power between two electrodes of the discharge lamp;
  An interelectrode voltage detector for detecting an interelectrode voltage when a predetermined power is supplied between the two electrodes;
  Based on the detected interelectrode voltage, power supply by the discharge lamp lighting unit is provided with a predetermined hysteresis between a first power supply condition and a second power supply condition different from the first power supply condition. Power supply condition switching unit to be switched,
  With
  The power supply conditions are switched by changing at least one of the frequency of the alternating current, the duty ratio of the alternating current, the modulation pattern of the frequency, and the modulation pattern of the duty ratio,
  The power supply condition switching unit is a discharge lamp driving device that changes a width of the hysteresis based on a usage time of the discharge lamp. The discharge lamp driving device according to claim 2,
The power feeding condition switching unit is a discharge lamp driving device that increases a width of the hysteresis when a usage time of the discharge lamp reaches a predetermined time .
A driving device for a discharge lamp. The discharge lamp driving device according to any one of claims 1 to 3 ,
The power supply condition switching unit
The power supply condition for the power supplied between the two electrodes is changed from the first power supply condition to the first power supply condition when the voltage between the electrodes rises and reaches a first upper limit voltage under the first power supply condition. When the power supply condition is switched to 2 and the voltage between the electrodes decreases under the second power supply condition and reaches a second lower limit voltage lower than the first upper limit voltage, the second power supply condition is A discharge lamp driving device that switches to the first power supply condition. The discharge lamp driving device according to claim 1 ,
The power supply condition switching unit
The power supply condition for the power supplied between the two electrodes is changed from the second power supply condition to the first power supply voltage when the voltage between the electrodes rises and reaches a second upper limit voltage under the second power supply condition. When the third power supply condition is switched and the interelectrode voltage decreases under the third power supply condition and reaches a third lower limit voltage lower than the second upper limit voltage, the third power supply condition starts. A discharge lamp driving device that switches to the second power supply condition. A light source device,
A discharge lamp,
The discharge lamp driving device according to any one of claims 1 to 5,
A light source device. An image display device,
A discharge lamp as a light source for image display;
The discharge lamp driving device according to any one of claims 1 to 5,
An image display device comprising: A method of driving a discharge lamp by supplying alternating current to the discharge lamp to supply power between two electrodes of the discharge lamp to light the discharge lamp,
Detecting a voltage between electrodes when a predetermined power is supplied between the two electrodes;
Based on the detected interelectrode voltage, power supply by the discharge lamp lighting unit is performed between a first power supply condition and a second power supply condition different from the first power supply condition , and the second power supply condition. And switching with a predetermined hysteresis between the first power supply condition and a third power supply condition different from the first power supply condition ,
Each of the power supply conditions is as follows:
The frequency of the alternating current, and the duty ratio of the alternating current, a modulation pattern of the frequency switching et been by changing at least one of a modulation pattern of the duty ratio,
In order from the lowest detected interelectrode voltage, the first power supply condition, the second power supply condition, and the third power supply condition,
The hysteresis width for switching between the second power feeding condition and the third power feeding condition is larger than the hysteresis width for switching between the first power feeding condition and the second power feeding condition,
How to drive a discharge lamp.

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