JP2018107072A - Electric-discharge lamp drive device, light source device, projector, and electric-discharge lamp drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric-electric-discharge lamp drive device allowing for extension of the life of an electric-discharge lamp.SOLUTION: The electric-discharge lamp drive device according to one embodiment, comprises an electric-discharge lamp drive part which supplies a driving current to an electric-discharge lamp including an electrode, and a control part which controls the electric-discharge lamp drive part. The electric-discharge lamp drive part has a first mode in which predetermined drive power is supplied to the electric-discharge lamp, and a second mode in which a value of the drive power temporally change. The control part changes a drive pattern of the drive current supplied to the electric-discharge lamp in accordance with the change of the drive power in the second mode. When a ratio of a period in which the value of the drive power becomes equal to or less than a predetermined value during a predetermined period becomes greater than a predetermined ratio in the second mode, the control part switches the drive pattern in the period in which the drive power becomes equal to or less than the predetermined value from a first drive pattern to a second drive pattern in which a thermal load applied to the electrode is greater than that of the first drive pattern.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a discharge lamp driving device, a light source device, a projector, and a discharge lamp driving method.

  There is known a lighting device that changes a lamp control pattern in accordance with a lamp lighting pattern (see, for example, Patent Document 1).

Japanese Patent No. 4003796

  By the way, as the lighting pattern of the lamp (discharge lamp) described above, there is driving that changes the driving power supplied to the lamp in accordance with the video signal. In such a drive, when a state where the value of the drive power is relatively small is provided for a relatively long time, it is difficult to sufficiently grow the protrusion of the electrode, and the lamp life may be reduced.

  One aspect of the present invention is made in view of the above problems, and is a discharge lamp driving device capable of improving the life of a discharge lamp, a light source device including such a discharge lamp driving device, and such Another object is to provide a projector provided with a simple light source device. Another object of one aspect of the present invention is to provide a discharge lamp driving method capable of improving the life of a discharge lamp.

  One aspect of the discharge lamp driving device of the present invention includes a discharge lamp driving unit that supplies a driving current to a discharge lamp having an electrode, and a control unit that controls the discharge lamp driving unit, and the discharge lamp driving unit Has a first mode in which predetermined driving power is supplied to the discharge lamp, and a second mode in which the value of the driving power changes with time, and the control unit is The control unit changes the drive pattern of the drive current supplied to the discharge lamp according to the change of the drive power, and the control unit has a value of the drive power in a predetermined period equal to or less than a predetermined value in the second mode. When the ratio of the period is larger than the predetermined ratio, the driving pattern in the period in which the driving power is equal to or less than the predetermined value is changed from the first driving pattern, and the thermal load applied to the electrode is higher than that of the first driving pattern. Big second And wherein the switching to the drive pattern.

  According to one aspect of the discharge lamp driving device of the present invention, when the state in which the value of the driving power is relatively small is provided for a relatively long time in the second mode, the period during which the driving power is a predetermined value or less. By switching the drive pattern to the second drive pattern, it is possible to apply a heat load to the electrode suitably, and it is possible to grow the protrusion of the electrode suitably. Thereby, according to the one aspect | mode of the discharge lamp drive device of this invention, the lifetime of a discharge lamp can be improved.

The second drive pattern may be the same as the drive pattern of the drive current supplied to the discharge lamp in the first mode.
According to this configuration, when the value of the driving power is relatively small in the second mode, a thermal load can be applied to the electrode as in the case of executing the first mode, and the protrusion of the electrode is more suitable. Can grow into. Therefore, the life of the discharge lamp can be further improved.

When the predetermined time has elapsed since the control unit switched from the first drive pattern to the second drive pattern, the control unit changes the drive pattern in the period in which the drive power is equal to or less than the predetermined value from the second drive pattern to the second drive pattern. It is good also as a structure switched to a 1st drive pattern.
According to this configuration, the first drive pattern and the second drive pattern are preferably switched, and a thermal load is easily applied to the electrodes. Thereby, the lifetime of a discharge lamp can be improved more.

The said control part is good also as a structure which changes the said predetermined time according to the voltage between the electrodes of the said discharge lamp.
According to this configuration, the execution time of the second drive pattern can be easily changed according to the deterioration of the discharge lamp, and the life of the discharge lamp can be further improved.

The control unit is configured to make the predetermined time when the inter-electrode voltage becomes the first voltage longer than the predetermined time when the inter-electrode voltage becomes the second voltage smaller than the first voltage. Also good.
According to this configuration, as the discharge lamp is deteriorated, the execution time of the second drive pattern is easily increased, and the heat load applied to the electrode can be increased. Thereby, the lifetime of a discharge lamp can be improved more.

In the second mode, the control unit is configured such that a driving pattern in a period in which the driving power is equal to or less than the predetermined value is the second driving pattern, and a value of the driving power in the predetermined period is equal to or less than the predetermined value. When the ratio of the period becomes equal to or less than the predetermined ratio, the drive pattern in the period where the drive power is equal to or less than the predetermined value may be switched from the second drive pattern to the first drive pattern.
According to this configuration, the first drive pattern and the second drive pattern can be suitably switched according to the state of change in the value of the drive power. Therefore, the life of the discharge lamp can be further improved.

  One aspect of the light source device of the present invention includes a discharge lamp that emits light and the discharge lamp driving device.

  According to one aspect of the light source device of the present invention, since the discharge lamp driving device is provided, the life of the discharge lamp can be improved.

  One aspect of the projector of the present invention includes the light source device, a light modulation device that modulates light emitted from the light source device according to an image signal, and a projection that projects light modulated by the light modulation device. And an optical system.

  According to one aspect of the projector of the present invention, since the light source device is provided, the life of the discharge lamp can be improved.

  One aspect of the discharge lamp driving method of the present invention is a discharge lamp driving method for driving a discharge lamp by supplying a driving current to a discharge lamp having an electrode, wherein predetermined driving power is supplied to the discharge lamp. And the second mode in which the value of the driving power changes with time, and the driving supplied to the discharge lamp in accordance with the change in the driving power in the second mode When the current drive pattern is changed and the ratio of the period in which the value of the drive power in the predetermined period is less than or equal to a predetermined value in the second mode is greater than the predetermined ratio, the drive power is less than or equal to the predetermined value. The driving pattern in a certain period is switched from the first driving pattern to a second driving pattern in which a thermal load applied to the electrode is larger than the first driving pattern.

  According to one aspect of the discharge lamp driving method of the present invention, the life of the discharge lamp can be improved in the same manner as described above.

It is a schematic block diagram of the projector of this embodiment. It is a figure which shows the discharge lamp in this embodiment. It is a block diagram which shows the various components of the projector of this embodiment. It is a circuit diagram of the discharge lamp lighting device of this embodiment. It is a block diagram which shows the example of 1 structure of the control part of this embodiment. It is a figure which shows the mode of the protrusion of the electrode tip of a discharge lamp. It is a figure which shows the mode of the protrusion of the electrode tip of a discharge lamp. It is a schematic diagram which shows an example of the drive pattern in the low power drive mode of this embodiment. It is a figure which shows an example of the drive current supplied to a discharge lamp in the mixing period of this embodiment. It is a figure which shows an example of the drive current supplied to a discharge lamp in the offset period of this embodiment. It is a figure which shows an example of the change of the drive pattern of the drive current with respect to the change of drive power in the light control drive mode of this embodiment. It is a schematic diagram which shows an example of the drive pattern in the light control drive mode of this embodiment. It is a figure which shows another example of the change of the drive pattern of the drive current with respect to the change of drive power in the light control drive mode of this embodiment.

Hereinafter, a projector according to an embodiment of the invention will be described with reference to the drawings.
The scope of the present invention is not limited to the following embodiment, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each structure easy to understand, the actual structure may be different from the scale, number, or the like in each structure.

  As shown in FIG. 1, the projector 500 of the present embodiment includes a light source device 200, a collimating lens 305, an illumination optical system 310, a color separation optical system 320, and three liquid crystal light valves (light modulation devices) 330R. , 330G, 330B, a cross dichroic prism 340, and a projection optical system 350 are provided.

  Light emitted from the light source device 200 passes through the collimating lens 305 and enters the illumination optical system 310. The collimating lens 305 collimates the light from the light source device 200.

  The illumination optical system 310 adjusts the illuminance of light emitted from the light source device 200 to be uniform on the liquid crystal light valves 330R, 330G, and 330B. Furthermore, the illumination optical system 310 aligns the polarization direction of the light emitted from the light source device 200 in one direction. The reason is that the light emitted from the light source device 200 is effectively used by the liquid crystal light valves 330R, 330G, and 330B.

  The light whose illuminance distribution and polarization direction are adjusted enters the color separation optical system 320. The color separation optical system 320 separates incident light into three color lights of red light (R), green light (G), and blue light (B). The three color lights are respectively modulated according to the video signal by the liquid crystal light valves 330R, 330G, and 330B associated with the respective color lights. The liquid crystal light valves 330R, 330G, and 330B include liquid crystal panels 560R, 560G, and 560B, which will be described later, and polarizing plates (not shown). The polarizing plates are disposed on the light incident side and the light emitting side of the liquid crystal panels 560R, 560G, and 560B, respectively.

  The three modulated color lights are combined by the cross dichroic prism 340. The combined light enters the projection optical system 350. The projection optical system 350 projects incident light onto the screen 700 (see FIG. 3). As a result, an image is displayed on the screen 700. As each configuration of the collimating lens 305, the illumination optical system 310, the color separation optical system 320, the cross dichroic prism 340, and the projection optical system 350, a well-known configuration can be adopted.

  FIG. 2 is a cross-sectional view showing the configuration of the light source device 200. The light source device 200 includes a light source unit 210 and a discharge lamp lighting device (discharge lamp driving device) 10. FIG. 2 shows a cross-sectional view of the light source unit 210. The light source unit 210 includes a main reflecting mirror 112, a discharge lamp 90, and a sub reflecting mirror 113.

  The discharge lamp lighting device 10 supplies the drive current I to the discharge lamp 90 to light the discharge lamp 90. The main reflecting mirror 112 reflects the light emitted from the discharge lamp 90 in the irradiation direction D. The irradiation direction D is parallel to the optical axis AX of the discharge lamp 90.

  The shape of the discharge lamp 90 is a rod shape extending along the irradiation direction D. One end of the discharge lamp 90 is a first end 90e1, and the other end of the discharge lamp 90 is a second end 90e2. The material of the discharge lamp 90 is a translucent material such as quartz glass, for example. The central portion of the discharge lamp 90 swells in a spherical shape, and the inside is a discharge space 91. The discharge space 91 is filled with a gas that is a discharge medium containing a rare gas, a metal halide, or the like.

  In the discharge space 91, the tips of the first electrode (electrode) 92 and the second electrode (electrode) 93 protrude. The first electrode 92 is disposed on the first end portion 90 e 1 side of the discharge space 91. The second electrode 93 is disposed on the second end 90 e 2 side of the discharge space 91. The shape of the first electrode 92 and the second electrode 93 is a rod shape extending along the optical axis AX. In the discharge space 91, the electrode tip portions of the first electrode 92 and the second electrode 93 are arranged to face each other with a predetermined distance. The material of the first electrode 92 and the second electrode 93 is, for example, a metal such as tungsten.

  A first terminal 536 is provided at the first end 90 e 1 of the discharge lamp 90. The first terminal 536 and the first electrode 92 are electrically connected by a conductive member 534 that penetrates the inside of the discharge lamp 90. Similarly, a second terminal 546 is provided at the second end 90e2 of the discharge lamp 90. The second terminal 546 and the second electrode 93 are electrically connected by a conductive member 544 that penetrates the inside of the discharge lamp 90. The material of the first terminal 536 and the second terminal 546 is, for example, a metal such as tungsten. As a material of the conductive members 534 and 544, for example, a molybdenum foil is used.

  The first terminal 536 and the second terminal 546 are connected to the discharge lamp lighting device 10. The discharge lamp lighting device 10 supplies a driving current I for driving the discharge lamp 90 to the first terminal 536 and the second terminal 546. As a result, arc discharge occurs between the first electrode 92 and the second electrode 93. Light (discharge light) generated by the arc discharge is radiated in all directions from the discharge position, as indicated by the dashed arrows.

  The main reflecting mirror 112 is fixed to the first end 90e1 of the discharge lamp 90 by a fixing member 114. The main reflecting mirror 112 reflects the light traveling toward the opposite side of the irradiation direction D in the discharge light toward the irradiation direction D. The shape of the reflecting surface (the surface on the discharge lamp 90 side) of the main reflecting mirror 112 is not particularly limited as long as the discharge light can be reflected in the irradiation direction D. Parabolic shape may be sufficient. For example, when the shape of the reflecting surface of the main reflecting mirror 112 is a parabolic shape, the main reflecting mirror 112 can convert the discharge light into light substantially parallel to the optical axis AX. Thereby, the collimating lens 305 can be omitted.

  The sub-reflecting mirror 113 is fixed to the second end 90 e 2 side of the discharge lamp 90 by a fixing member 522. The shape of the reflecting surface (surface on the discharge lamp 90 side) of the sub-reflecting mirror 113 is a spherical shape surrounding the portion of the discharge space 91 on the second end 90e2 side. The sub-reflecting mirror 113 reflects the light traveling toward the side opposite to the side on which the main reflecting mirror 112 is disposed in the discharge light toward the main reflecting mirror 112. Thereby, the utilization efficiency of the light radiated | emitted from the discharge space 91 can be improved.

  The material of the fixing members 114 and 522 is not particularly limited as long as it is a heat-resistant material that can withstand the heat generated from the discharge lamp 90, and is, for example, an inorganic adhesive. The method of fixing the arrangement of the main reflecting mirror 112 and the sub reflecting mirror 113 and the discharge lamp 90 is not limited to the method of fixing the main reflecting mirror 112 and the sub reflecting mirror 113 to the discharge lamp 90, and any method can be adopted. . For example, the discharge lamp 90 and the main reflecting mirror 112 may be independently fixed to the housing (not shown) of the projector 500. The same applies to the sub-reflecting mirror 113.

Hereinafter, the circuit configuration of the projector 500 will be described.
FIG. 3 is a diagram illustrating an example of a circuit configuration of the projector 500 according to the present embodiment. In addition to the optical system shown in FIG. 1, the projector 500 includes an image signal conversion unit 510, a DC power supply device 80, liquid crystal panels 560R, 560G, and 560B, an image processing device 570, and a CPU (Central Processing Unit) 580. It is equipped with.

  The image signal conversion unit 510 converts an image signal 502 (such as a luminance-color difference signal or an analog RGB signal) input from the outside into a digital RGB signal having a predetermined word length to generate image signals 512R, 512G, and 512B. This is supplied to the image processing device 570.

  The image processing device 570 performs image processing on each of the three image signals 512R, 512G, and 512B. The image processing device 570 supplies drive signals 572R, 572G, and 572B for driving the liquid crystal panels 560R, 560G, and 560B to the liquid crystal panels 560R, 560G, and 560B, respectively.

  The DC power supply device 80 converts an AC voltage supplied from an external AC power supply 600 into a constant DC voltage. The DC power supply device 80 includes an image signal conversion unit 510 on the secondary side of a transformer (not shown, but included in the DC power supply device 80), an image processing device 570, and a discharge lamp lighting device 10 on the primary side of the transformer. Supply DC voltage.

  The discharge lamp lighting device 10 generates a high voltage between the electrodes of the discharge lamp 90 at the time of startup, and causes a dielectric breakdown to form a discharge path. Thereafter, the discharge lamp lighting device 10 supplies the drive current I for the discharge lamp 90 to maintain the discharge.

  Liquid crystal panels 560R, 560G, and 560B are provided in the liquid crystal light valves 330R, 330G, and 330B, respectively. The liquid crystal panels 560R, 560G, and 560B modulate the transmittance (luminance) of color light incident on the liquid crystal panels 560R, 560G, and 560B via the optical system described above based on the drive signals 572R, 572G, and 572B, respectively. .

  The CPU 580 controls various operations from the start of lighting of the projector 500 to the turning off of the projector 500. For example, in FIG. 3, a lighting command or a lighting command is output to the discharge lamp lighting device 10 via the communication signal 582. The CPU 580 receives lighting information of the discharge lamp 90 from the discharge lamp lighting device 10 via the communication signal 584.

Hereinafter, the configuration of the discharge lamp lighting device 10 will be described.
FIG. 4 is a diagram illustrating an example of a circuit configuration of the discharge lamp lighting device 10.
As shown in FIG. 4, the discharge lamp lighting device 10 includes a power control circuit 20, a polarity inversion circuit 30, a control unit 40, an operation detection unit 60, and an igniter circuit 70.

  The power control circuit 20 generates drive power Wd to be supplied to the discharge lamp 90. In the present embodiment, the power control circuit 20 includes a down chopper circuit that receives the voltage from the DC power supply device 80 as an input, steps down the input voltage, and outputs a DC current Id.

  The power control circuit 20 includes a switch element 21, a diode 22, a coil 23, and a capacitor 24. The switch element 21 is composed of, for example, a transistor. In the present embodiment, one end of the switch element 21 is connected to the positive voltage side of the DC power supply device 80, and the other end is connected to the cathode terminal of the diode 22 and one end of the coil 23.

  One end of a capacitor 24 is connected to the other end of the coil 23, and the other end of the capacitor 24 is connected to the anode terminal of the diode 22 and the negative voltage side of the DC power supply device 80. A current control signal is input to the control terminal of the switch element 21 from a control unit 40 described later, and ON / OFF of the switch element 21 is controlled. For example, a PWM (Pulse Width Modulation) control signal may be used as the current control signal.

  When the switch element 21 is turned on, a current flows through the coil 23 and energy is stored in the coil 23. Thereafter, when the switch element 21 is turned OFF, the energy stored in the coil 23 is released through a path passing through the capacitor 24 and the diode 22. As a result, a direct current Id corresponding to the proportion of time during which the switch element 21 is turned on is generated.

  The polarity inversion circuit 30 inverts the polarity of the direct current Id input from the power control circuit 20 at a predetermined timing. As a result, the polarity inversion circuit 30 generates and outputs a drive current I that is a direct current that lasts for a controlled time, or a drive current I that is an alternating current having an arbitrary frequency. In the present embodiment, the polarity inverting circuit 30 is configured by an inverter bridge circuit (full bridge circuit).

  The polarity inversion circuit 30 includes, for example, a first switch element 31, a second switch element 32, a third switch element 33, and a fourth switch element 34 configured by transistors. In the polarity inversion circuit 30, the first switch element 31 and the second switch element 32 connected in series, and the third switch element 33 and the fourth switch element 34 connected in series are connected in parallel to each other. It has a configuration. The polarity inversion control signal is input from the control unit 40 to the control terminals of the first switch element 31, the second switch element 32, the third switch element 33, and the fourth switch element 34, respectively. Based on this polarity inversion control signal, the ON / OFF operation of the first switch element 31, the second switch element 32, the third switch element 33, and the fourth switch element 34 is controlled.

  In the polarity inversion circuit 30, the operation of alternately turning on / off the first switch element 31 and the fourth switch element 34, and the second switch element 32 and the third switch element 33 is repeated. Thereby, the polarity of the direct current Id output from the power control circuit 20 is alternately inverted. The polarity inversion circuit 30 is controlled from the common connection point between the first switch element 31 and the second switch element 32 and the common connection point between the third switch element 33 and the fourth switch element 34. A drive current I that is a direct current that continues the same polarity state or a drive current I that is an alternating current having a controlled frequency is generated and output.

  In other words, the polarity inverting circuit 30 is configured such that when the first switch element 31 and the fourth switch element 34 are ON, the second switch element 32 and the third switch element 33 are OFF, When the fourth switch element 34 is OFF, the second switch element 32 and the third switch element 33 are controlled to be ON. Therefore, when the first switch element 31 and the fourth switch element 34 are ON, the drive current I flowing from the one end of the capacitor 24 in the order of the first switch element 31, the discharge lamp 90, and the fourth switch element 34 is generated. To do. When the second switch element 32 and the third switch element 33 are ON, a drive current I that flows from one end of the capacitor 24 in the order of the third switch element 33, the discharge lamp 90, and the second switch element 32 is generated.

  In the present embodiment, the combined portion of the power control circuit 20 and the polarity inversion circuit 30 corresponds to the discharge lamp driving unit 230. That is, the discharge lamp driving unit 230 supplies the driving current I for driving the discharge lamp 90 to the discharge lamp 90.

  The control unit 40 controls the discharge lamp driving unit 230. In the example of FIG. 4, the control unit 40 controls the power control circuit 20 and the polarity inversion circuit 30, so that the holding time during which the drive current I continues the same polarity, the current value of the drive current I, and the power of the drive power Wd Control parameters such as value and frequency. The control unit 40 performs polarity reversal control for the polarity reversing circuit 30 to control the holding time during which the drive current I continues at the same polarity, the frequency of the drive current I, and the like according to the polarity reversal timing of the drive current I. The control unit 40 performs current control for controlling the current value of the output direct current Id on the power control circuit 20.

  The configuration of the control unit 40 is not particularly limited. In the present embodiment, the control unit 40 includes a system controller 41, a power control circuit controller 42, and a polarity inversion circuit controller 43. Note that a part or all of the control unit 40 may be configured by a semiconductor integrated circuit.

  The system controller 41 controls the power control circuit 20 and the polarity inversion circuit 30 by controlling the power control circuit controller 42 and the polarity inversion circuit controller 43. The system controller 41 may control the power control circuit controller 42 and the polarity inversion circuit controller 43 based on the lamp voltage (interelectrode voltage) Vla and the drive current I detected by the operation detection unit 60.

In the present embodiment, a storage unit 44 is connected to the system controller 41.
The system controller 41 may control the power control circuit 20 and the polarity inversion circuit 30 based on information stored in the storage unit 44. The storage unit 44 may store, for example, information related to drive parameters such as a holding time during which the drive current I continues with the same polarity, a current value of the drive current I, a frequency, a waveform, and a modulation pattern.

  The power control circuit controller 42 controls the power control circuit 20 by outputting a current control signal to the power control circuit 20 based on the control signal from the system controller 41.

  The polarity inversion circuit controller 43 controls the polarity inversion circuit 30 by outputting a polarity inversion control signal to the polarity inversion circuit 30 based on the control signal from the system controller 41.

  The control unit 40 is realized using a dedicated circuit, and can perform the above-described control and various types of control of processing to be described later. On the other hand, for example, the control unit 40 can function as a computer when the CPU executes a control program stored in the storage unit 44, and can perform various controls of these processes.

  FIG. 5 is a diagram for explaining another configuration example of the control unit 40. As shown in FIG. 5, the control unit 40 is configured to function as a current control unit 40-1 that controls the power control circuit 20 and a polarity reversal control unit 40-2 that controls the polarity reversing circuit 30 according to a control program. May be.

  In the example shown in FIG. 4, the control unit 40 is configured as a part of the discharge lamp lighting device 10. On the other hand, the CPU 580 may be configured to bear a part of the function of the control unit 40.

  In the present embodiment, the operation detection unit 60 includes a voltage detection unit that detects the lamp voltage Vla of the discharge lamp 90 and outputs lamp voltage information to the control unit 40. Further, the operation detection unit 60 may include a current detection unit that detects the drive current I and outputs drive current information to the control unit 40. In the present embodiment, the operation detection unit 60 is configured to include a first resistor 61, a second resistor 62, and a third resistor 63.

  In the present embodiment, the voltage detection unit of the operation detection unit 60 detects the lamp voltage Vla in parallel with the discharge lamp 90 using the voltage divided by the first resistor 61 and the second resistor 62 connected in series with each other. . In the present embodiment, the current detection unit detects the drive current I based on the voltage generated in the third resistor 63 connected in series to the discharge lamp 90.

  The igniter circuit 70 operates only when the discharge lamp 90 starts to be lit. The igniter circuit 70 is a high voltage (discharge) necessary for forming a discharge path by dielectric breakdown between the electrodes of the discharge lamp 90 (between the first electrode 92 and the second electrode 93) at the start of lighting of the discharge lamp 90. (A voltage higher than that during normal lighting of the lamp 90) is supplied between the electrodes of the discharge lamp 90 (between the first electrode 92 and the second electrode 93). In the present embodiment, the igniter circuit 70 is connected in parallel with the discharge lamp 90.

  6A and 6B show the tip portions of the first electrode 92 and the second electrode 93. Protrusions 552p and 562p are formed at the tips of the first electrode 92 and the second electrode 93, respectively.

  The discharge generated between the first electrode 92 and the second electrode 93 is mainly generated between the protrusion 552p and the protrusion 562p. When there are the protrusions 552p and 562p as in the present embodiment, the movement of the discharge position (arc position) in the first electrode 92 and the second electrode 93 can be suppressed as compared with the case where there is no protrusion.

  FIG. 6A shows a first polarity state in which the first electrode 92 operates as an anode and the second electrode 93 operates as a cathode. In the first polarity state, electrons move from the second electrode 93 (cathode) to the first electrode 92 (anode) by discharge. Electrons are emitted from the cathode (second electrode 93). Electrons emitted from the cathode (second electrode 93) collide with the tip of the anode (first electrode 92). Heat is generated by this collision, and the temperature of the tip (projection 552p) of the anode (first electrode 92) rises.

  FIG. 6B shows a second polarity state in which the first electrode 92 operates as a cathode and the second electrode 93 operates as an anode. In the second polarity state, electrons move from the first electrode 92 to the second electrode 93, contrary to the first polarity state. As a result, the temperature of the tip (projection 562p) of the second electrode 93 rises.

  Thus, the drive current I is supplied to the discharge lamp 90, so that the temperature of the anode where the electrons collide increases. On the other hand, the temperature of the cathode that emits electrons decreases while the electrons are emitted toward the anode.

  The interelectrode distance between the first electrode 92 and the second electrode 93 increases with the deterioration of the protrusions 552p and 562p. This is because the protrusions 552p and 562p are worn out. As the distance between the electrodes increases, the resistance between the first electrode 92 and the second electrode 93 increases, and the lamp voltage Vla increases. Therefore, by referring to the lamp voltage Vla, it is possible to detect a change in the distance between the electrodes, that is, the degree of deterioration of the discharge lamp 90.

  In addition, since the 1st electrode 92 and the 2nd electrode 93 are the same structures, in the following description, only the 1st electrode 92 may be demonstrated as a representative. In addition, since the protrusion 552p at the tip of the first electrode 92 and the protrusion 562p at the tip of the second electrode 93 have the same configuration, in the following description, only the protrusion 552p may be described as a representative.

  Next, control of the discharge lamp driving unit 230 by the control unit 40 will be described. In the present embodiment, the control unit 40 can perform low power driving and dimming driving as driving for driving the discharge lamp driving unit 230. That is, the discharge lamp driving unit 230 includes, as drive modes, a low power drive mode (first mode) ML in which low power drive is executed, and a dimming drive mode (second mode) MC in which dimming drive is executed. Have. Note that the low power drive mode ML and the dimming drive mode MC correspond to the modes of the projector 500 that can be selected by the user using an operation unit such as an operation button (not shown) of the projector 500 or an external device such as a remote controller.

  The low power drive mode ML is a mode in which predetermined drive power Wd is supplied to the discharge lamp 90. In the low power drive mode ML, drive power Wd that is relatively smaller than the rated power of the discharge lamp 90 is supplied to the discharge lamp 90. In the low power driving mode ML, the driving current I of the low power driving pattern (second driving pattern) DWL is supplied to the discharge lamp 90. When the rated power is 215 W, the driving power Wd supplied to the discharge lamp 90 in the low power driving mode ML is, for example, 160 W.

  FIG. 7 is a schematic diagram illustrating an example of a low power drive pattern DWL in the low power drive mode ML of the present embodiment. As shown in FIG. 7, in the low power drive pattern DWL of the present embodiment, the mixing period PH1 in which the AC period P1 and the DC period P2 are alternately repeated and the offset period P3 are alternately repeated. The number of AC periods P1 and the number of DC periods P2 in the mixing period PH1 are not particularly limited.

  FIG. 8 is a diagram illustrating an example of the drive current I supplied to the discharge lamp 90 in the mixing period PH1. In FIG. 8, the vertical axis represents the drive current I, and the horizontal axis represents time T. The drive current I is shown as positive when it is in the first polarity state and negative when it is in the second polarity state.

  As shown in FIG. 8, the AC period P <b> 1 is a period in which an AC current is supplied to the discharge lamp 90. In the present embodiment, the AC period P1 includes a first AC period P11, a second AC period P12, a third AC period P13, and a fourth AC period P14. The first AC period P11, the second AC period P12, the third AC period P13, and the fourth AC period P14 are continuously provided in this order.

  In the present embodiment, the alternating current in the first alternating period P11, the second alternating period P12, the third alternating period P13, and the fourth alternating period P14 is, for example, between the current value Im1 and the current value −Im1. And a rectangular wave alternating current whose polarity is inverted a plurality of times.

  The frequency f11 in the first AC period P11, the frequency f12 in the second AC period P12, the frequency f13 in the third AC period P13, and the frequency f14 in the fourth AC period P14 are different from each other. That is, the AC period P1 has a plurality of AC periods in which the frequency f of the AC current supplied to the discharge lamp 90 is different from each other.

  In the present embodiment, the frequency f11, the frequency f12, the frequency f13, and the frequency f14 decrease in this order. That is, in the AC period P1, the frequency f of the AC current becomes lower in the AC period provided later in time.

  In the present embodiment, the length t11 of the first AC period P11, the length t12 of the second AC period P12, the length t13 of the third AC period P13, and the length t14 of the fourth AC period P14 are: For example, it is the same. In the present embodiment, the length t1 of the AC period P1, that is, the total length of the lengths t11 to t14 is, for example, not less than 10 ms (milliseconds) and not more than 10 s (seconds). By setting the length t1 of the AC period P1 in this way, a heat load can be suitably applied to the protrusion 552p of the first electrode 92.

  The direct current period P <b> 2 is a period during which a direct current is supplied to the discharge lamp 90. In the example shown in FIG. 8, the drive current I having the first polarity having a constant current value Im1 is supplied to the discharge lamp 90 in the DC period P2. The polarity of the direct current supplied to the discharge lamp 90 in the direct current period P2 is reversed every time the direct current period P2 is provided.

  That is, in the mixing period PH1 shown in FIG. 7, the direct current of the direct current period P2 provided immediately before the alternating current period P1 and the direct current of the direct current period P2 provided immediately after the alternating current period P1 have different polarities. For example, when the polarity of the direct current in the direct current period P2 provided immediately before the alternating current period P1 is the first polarity like the direct current in the direct current period P2 shown in FIG. 8, the direct current period provided immediately after the alternating current period P1. The polarity of the direct current of P2 is the second polarity opposite to the first polarity. In this case, in the direct current period P <b> 2 provided immediately after the alternating current period P <b> 1, the second polarity driving current I having a constant current value −Im is supplied to the discharge lamp 90.

  The length t2 of the direct current period P2 shown in FIG. 8 is longer than the length of the half cycle of the alternating current in the alternating current period P1. The length t2 of the DC period P2 is, for example, not less than 10 ms (milliseconds) and not more than 20 ms (milliseconds). By setting the length t <b> 2 of the direct current period P <b> 2 in this way, a heat load can be suitably applied to the protrusion 552 p of the first electrode 92.

  FIG. 9 is a diagram illustrating an example of the drive current I supplied to the discharge lamp 90 in the offset period P3. In FIG. 9, the vertical axis represents the drive current I, and the horizontal axis represents time T. The drive current I is shown as positive when it is in the first polarity state and negative when it is in the second polarity state.

  As shown in FIG. 9, the offset period P3 is a period including the first DC period P31 and the second DC period P32 alternately. The first DC period P31 is a period in which a DC current is supplied to the discharge lamp 90. In the example shown in FIG. 9, in the first DC period P31, the first polarity driving current I having a constant current value Im1 is supplied to the discharge lamp 90.

  The second DC period P32 is a period in which a DC current having a polarity opposite to the polarity of the DC current supplied to the discharge lamp 90 in the first DC period P31 is supplied to the discharge lamp 90. That is, in the example shown in FIG. 9, in the second DC period P <b> 32, the second polarity drive current I having a constant current value −Im is supplied to the discharge lamp 90.

  The polarity of the direct current supplied to the discharge lamp 90 in the first direct current period P31 and the polarity of the direct current supplied to the discharge lamp 90 in the second direct current period P32 are reversed every time the offset period P3 is provided. That is, in the offset period P3 provided next to the offset period P3 shown in FIG. 9, the polarity of the DC current supplied to the discharge lamp 90 in the first DC period P31 becomes the second polarity, and the second DC period P32 The polarity of the direct current supplied to the discharge lamp 90 is the first polarity.

  The length t31 of the first DC period P31 is longer than the length t32 of the second DC period P32. The length t31 of the first DC period P31 is, for example, not less than 10 times the length t32 of the second DC period P32. By setting the length t31 of the first DC period P31 in this way, it is possible to suitably suppress the temperature of the other electrode from being excessively lowered while appropriately heating one electrode in the offset period P3.

  The length t31 of the first DC period P31 is, for example, not less than 5.0 ms (milliseconds) and not more than 20 ms (milliseconds). The length t32 of the second DC period P32 is smaller than 0.5 ms (milliseconds).

  The sum of the lengths t31 of the first DC periods P31 in the offset period P3 is greater than the length t2 of the DC periods P2. The sum of the lengths t31 of the first DC periods P31 in the offset period P3 is a length obtained by adding the lengths t31 of all the first DC periods P31 included in the offset period P3. In the example shown in FIG. 9, the offset period P3 includes, for example, four first DC periods P31. Therefore, the sum of the lengths t31 of the first DC periods P31 in the offset period P3 is a length obtained by adding the lengths t31 of the four first DC periods P31.

  The total length t31 of the first DC period P31 in the offset period P3 is, for example, not less than 10 ms (milliseconds) and not more than 1.0 s (seconds). By setting the total length t31 of the first DC period P31 in the offset period P3 in this way, it is possible to suitably increase the heat load applied to the protrusion 552p of the first electrode 92. The length t31 of the first DC period P31 may be the same or different from each other. In the example shown in FIG. 9, the length t31 of the first DC period P31 is the same.

  The interval at which the offset period P3 is provided, that is, the length of the mixing period PH1 is, for example, 30 s (seconds). The length of the offset period P3 is, for example, 100 ms (milliseconds). As shown in FIG. 7, in the present embodiment, the offset period P3 is provided immediately after the AC period P1. Immediately after the offset period P3, an AC period P1 is provided. That is, the offset period P3 is provided so as to be sandwiched in time by the AC period P1.

  The dimming drive mode MC is a mode in which the value of the drive power Wd changes with time. In the dimming drive mode MC, the value of the drive power Wd changes according to the video signal input to the projector 500. Specifically, the control unit 40 increases the driving power Wd as the luminance of the video signal input to the projector 500 is higher, and decreases the driving power Wd as the luminance of the video signal input to the projector 500 is lower.

  In the dimming drive mode MC of the present embodiment, the drive pattern of the drive current I supplied to the discharge lamp 90 changes according to the change of the drive power Wd. That is, the control unit 40 changes the drive pattern of the drive current I supplied to the discharge lamp 90 in accordance with the change in the drive power Wd in the dimming drive mode MC. The dimming driving mode MC includes a first dimming driving mode (first power change mode) Md1 and a second dimming driving mode (first dimming driving mode in which the thermal load applied to the first electrode 92 is larger than the first dimming driving mode. 2 power change mode) Md2. When executing the dimming drive, the control unit 40 sets the driving mode (the dimming driving mode MC) of the discharge lamp driving unit 230 based on a predetermined condition, the first dimming driving mode Md1 and the second dimming driving mode. Switch between Md2.

  FIG. 10 is a diagram illustrating an example of a change in the drive pattern of the drive current I with respect to a change in the drive power Wd in the dimming drive mode MC of the present embodiment. The upper diagram of FIG. 10 is a diagram showing changes in the drive power Wd, the vertical axis shows the drive power Wd, and the horizontal axis shows the time T. The lower diagram of FIG. 10 is a schematic diagram showing changes in the drive pattern of the drive current I, and the horizontal axis shows time T. FIG.

  As shown in FIG. 10, in the first dimming drive mode Md1, the drive pattern of the drive current I changes among the drive pattern (first drive pattern) DW1, the drive pattern DW2, and the drive pattern DW3. In the first dimming drive mode Md1, when the value of the drive power Wd is within the first range WA1 of the first power Wd1 or more and the second power (predetermined value) Wd2 or less, the drive current I of the drive pattern DW1 is the discharge lamp 90. To be supplied. In the first dimming drive mode Md1, the drive current I of the drive pattern DW2 is supplied to the discharge lamp 90 when the value of the drive power Wd is greater than the second power Wd2 and falls within the second range WA2 below the third power Wd3. Is done. In the first dimming drive mode Md1, the drive current I of the drive pattern DW3 is supplied to the discharge lamp 90 when the value of the drive power Wd is larger than the third power Wd3 and falls within the third range WA3 below the fourth power Wd4. Is done. The first power Wd1, the second power Wd2, the third power Wd3, and the fourth power Wd4 increase in this order. The fourth power Wd4 is, for example, rated power or drive power close to the rated power.

  FIG. 11 is a schematic diagram illustrating an example of drive patterns DW1 to DW3 in the dimming drive mode MC of the present embodiment. As shown in FIG. 11, in the drive patterns DW1 to DW3 of the present embodiment, the AC period P1 and the DC period P2 described above are alternately repeated. In the drive patterns DW1 to DW3 in the dimming drive mode MC of this embodiment, unlike the low power drive pattern DWL in the low power drive mode ML, the offset period P3 is not provided.

  In the present embodiment, the drive patterns DW1 to DW3 are different from each other in, for example, the frequency f of the drive current I in the AC period P1 and the length t2 of the DC period P2. The thermal load applied to the first electrode 92 by the drive pattern DW1 is larger than the thermal load applied to the first electrode 92 by the drive pattern DW2. The thermal load applied to the first electrode 92 by the drive pattern DW2 is larger than the thermal load applied to the first electrode 92 by the drive pattern DW3. That is, in the drive pattern DW3, the drive pattern DW2, and the drive pattern DW1, the thermal load applied to the first electrode 92 in this order increases. Thereby, the heat load applied to the first electrode 92 increases as the drive power Wd decreases.

  As shown in FIG. 10, in the second dimming drive mode Md2, the drive pattern of the drive current I is the drive pattern DW2, the drive pattern DW3, and the low power drive pattern DWL (second drive pattern) shown in FIG. Vary between. When the value of the driving power Wd is in the second range WA2 in the second dimming driving mode Md2, the driving current I of the driving pattern DW2 is supplied to the discharge lamp 90 as in the first dimming driving mode Md1. When the value of the driving power Wd is in the third range WA3 in the second dimming driving mode Md2, the driving current I of the driving pattern DW3 is supplied to the discharge lamp 90 as in the first dimming driving mode Md1. The driving pattern of the driving current I supplied to the discharge lamp 90 when the value of the driving power Wd is larger than the second power Wd2 in the second dimming driving mode Md2 is the driving power Wd in the first dimming driving mode Md1. This is the same as the drive pattern of the drive current I supplied to the discharge lamp 90 when the value is larger than the second power Wd2.

  On the other hand, when the value of the drive power Wd is in the first range WA1 in the second dimming drive mode Md2, the drive current I of the low power drive pattern DWL is supplied to the discharge lamp 90, unlike the first dimming drive mode Md1. Is done. That is, when the value of the drive power Wd is within the first range WA1 in the second dimming drive mode Md2, the drive current I having the same drive pattern as that in the low power drive mode ML is supplied to the discharge lamp 90.

  The thermal load applied to the first electrode 92 by the low power drive pattern DWL is larger than the thermal load applied to the first electrode 92 by the drive pattern DW1 in the first dimming drive mode Md1. Thereby, the thermal load applied to the first electrode 92 in the second dimming drive mode Md2 is larger than the thermal load applied to the first electrode 92 in the first dimming drive mode Md1.

  In the present specification, the fact that the thermal load applied to the first electrode 92 in the second dimming drive mode Md2 is greater than that in the first dimming drive mode Md1 depends on each drive pattern switched in each dimming drive mode. It includes that the average value of the thermal load applied to the first electrode 92 is larger in the second dimming drive mode Md2 than in the first dimming drive mode Md1.

  Further, in the present embodiment, as described above, the dimming drive mode MC includes the first dimming drive mode Md1 and the second dimming drive mode Md2, and the control unit 40 determines that the value of the drive power Wd is the first. The drive pattern in the range WA1 is configured such that the first dimming drive mode Md1 is set to the drive pattern DW1, and the second dimming drive mode Md2 is set to the low power drive pattern DWL. Absent. The dimming drive mode MC is a single mode, and may be configured to simply change (switch) the drive pattern of the drive current I when a predetermined condition is satisfied.

  In the present embodiment, the drive patterns DW1, DW2, DW3, DWL in the first dimming drive mode Md1 and the second dimming drive mode Md2 have current values as shown in FIGS. As an example, the driving current I includes the AC period P1, the DC period P2, and the offset period P3 in which is constant at Im and −Im. However, in the dimming drive mode MC in which the value of the drive power Wd supplied to the discharge lamp 90 varies with time as shown in FIG. 10, the drive current I supplied to the discharge lamp 90 in each period P1 to P3. Are not constant current values (Im1 and -Im1), but actually change with time. Thus, the control unit 40 changes the drive power Wd with time by changing the current value of the drive current I with time.

  Table 1 shows an example of drive pattern parameters in each drive mode.

  In Table 1, the frequency f range of the AC period P1 includes the frequency f11 of the first AC period P11, the frequency f12 of the second AC period P12, the frequency f13 of the third AC period P13, and the frequency f14 of the fourth AC period P14. Indicates the range to be selected. In the example shown in Table 1, the first power Wd1 is 160W. The second power Wd2 is 170W. The third power Wd3 is 180W. The fourth power Wd4 is 215W. In Table 1, the low power drive pattern DWL is different from the drive pattern DW1 only in that the offset period P3 is provided. By providing the offset period P3, the thermal load applied to the first electrode 92 by the low power drive pattern DWL is larger than the thermal load applied to the first electrode 92 by the drive pattern DW1.

  In the dimming drive mode MC (first dimming drive mode Md1), the control unit 40 has a predetermined ratio of a period during which the value of the drive power Wd in the determination period (predetermined period) PHj shown in FIG. When the ratio is larger than the ratio, the driving mode of the discharge lamp driving unit 230 is switched from the first dimming driving mode Md1 to the second dimming driving mode Md2. That is, in the dimming drive mode MC, the control unit 40 determines that the value of the drive power Wd is equal to or less than the predetermined value when the ratio of the period in which the value of the drive power Wd in the predetermined period is equal to or less than the predetermined value is greater than the predetermined value. The driving pattern in the period is switched from the driving pattern DW1 (first driving pattern) to the low power driving pattern DWL (second driving pattern) in which the thermal load applied to the first electrode 92 is larger than the driving pattern DW1. In the present embodiment, the predetermined value is the second power Wd2. That is, in the present embodiment, the period in which the value of the drive power Wd is equal to or less than the predetermined value is a period within the first range WA1 in which the drive power Wd is equal to or greater than the first power Wd1 and equal to or less than the second power Wd2.

  As described above, when the value of the drive power Wd is equal to or less than the predetermined value (second power Wd2) in the first dimming drive mode Md1, that is, when the value of the drive power Wd falls within the first range WA1. The drive pattern of the drive current I supplied to is the drive pattern DW1. In the second dimming drive mode Md2, when the value of the drive power Wd is less than or equal to a predetermined value (second power Wd2), that is, when the value of the drive power Wd is within the first range WA1, the drive supplied to the discharge lamp 90 The drive pattern of the current I is a low power drive pattern DWL.

  When the ratio of the length tw1 of the period in which the drive power Wd is within the first range WA1 to the length tj of the determination period PHj is greater than a predetermined ratio, the control unit 40 The driving mode 230 is switched from the first dimming driving mode Md1 to the second dimming driving mode Md2. The length tw1 of the period during which the drive power Wd is within the first range WA1 is the length of the period during which the drive current I of the drive pattern DW1 is supplied to the discharge lamp 90. The predetermined ratio is, for example, about 70% or more and 90% or less.

  In the example illustrated in FIG. 10, the determination period PHj includes two periods in which the drive power Wd is within the first range WA1, two periods in which the drive power Wd is within the second range WA2, and the drive power Wd is the first. One period is provided in each of the three ranges WA3. The sum of these periods is the length tj of the determination period PHj. In FIG. 10, since the sum of the lengths tw1 of the periods in which the drive power Wd included in the determination period PHj is within the first range WA1 is greater than a predetermined ratio with respect to the length tj of the determination period PHj, the control unit 40 switches the driving mode of the discharge lamp driving unit 230 from the first dimming driving mode Md1 to the second dimming driving mode Md2.

  The determination period PHj is a period from the timing at which the control unit 40 determines the switching of the drive mode to the first predetermined time before. The first predetermined time is, for example, about 0.5 min (min) or more and 5 min (min) or less. The first predetermined time corresponds to the length tj of the determination period PHj. The control unit 40 may make a determination at any time or may make a determination at a predetermined interval. In the example shown in FIG. 10, the boundary between the first dimming drive mode Md1 and the second dimming drive mode Md2 is one of the timings for determining the switching of the drive mode.

  When the second predetermined time (predetermined time) has elapsed since the control unit 40 switched the driving mode of the discharge lamp driving unit 230 from the first dimming driving mode Md1 to the second dimming driving mode Md2, the discharge lamp driving unit The driving mode 230 is switched from the second dimming driving mode Md2 to the first dimming driving mode Md1. That is, the control unit 40, when the predetermined time has elapsed since the drive pattern DW1 was switched from the drive pattern DW1 to the low power drive pattern DWL during the period in which the value of the drive power Wd is equal to or less than the predetermined value in the dimming drive mode MC. The drive pattern is switched from the low power drive pattern DWL to the drive pattern DW1. The second predetermined time corresponds to a length for which the second dimming drive mode Md2 is executed.

  The control unit 40 changes the second predetermined time according to the lamp voltage Vla. Specifically, the control unit 40 increases the second predetermined time as the lamp voltage Vla increases. That is, the control unit 40 makes the second predetermined time when the lamp voltage Vla becomes the first voltage longer than the second predetermined time when the lamp voltage Vla becomes the second voltage lower than the first voltage. The second predetermined time is, for example, about 1 min (min) or more and 30 min (min) or less.

  Thereafter, the control unit 40 performs the determination by the determination period PHj in the same manner as described above, and sets the driving mode of the discharge lamp driving unit 230 between the first dimming driving mode Md1 and the second dimming driving mode Md2. Switch.

  The discharge lamp lighting device 10 including the control unit 40 that performs the control described above can also be expressed as a discharge lamp driving method. That is, one aspect of the discharge lamp driving method of the present embodiment is a discharge lamp driving method for driving the discharge lamp 90 by supplying the driving current I to the discharge lamp 90 having the first electrode 92 and the second electrode 93. A low power driving mode ML in which a predetermined driving power Wd is supplied to the discharge lamp 90, and a dimming driving mode MC in which the value of the driving power Wd changes with time, and the dimming driving mode MC , The drive pattern of the drive current I supplied to the discharge lamp 90 is changed in accordance with the change of the drive power Wd, and in the dimming drive mode MC, the period during which the value of the drive power Wd in the determination period PHj is a predetermined value or less When the ratio of the power is larger than the predetermined ratio, the drive pattern in the period in which the drive power Wd is equal to or less than the predetermined value is switched from the drive pattern DW1 to the low power drive pattern DWL. That.

  In the dimming drive mode MC, since the drive power Wd supplied to the discharge lamp 90 changes, the thermal load applied to the first electrode 92 changes according to the change of the drive power Wd. As a result, the first electrode 92 is easily stimulated by a change in thermal load, and the protrusion 552p is likely to grow. In this case, if the driving pattern of the driving current I supplied to the discharge lamp 90 is the same as the driving pattern of the low power driving mode ML, the thermal load applied to the first electrode 92 becomes excessive and the protrusion 552p is melted. There are cases where too much is done. Therefore, the drive pattern of the drive current I supplied to the discharge lamp 90 in the dimming drive mode MC is in addition to the first electrode 92 than the drive pattern of the drive current I supplied to the discharge lamp 90 in the low power drive mode ML. The heat load that is generated is set to be small.

  In such dimming drive mode MC, for example, when the state in which the value of the drive power Wd is relatively smaller than the rated power is provided for a relatively long time, the dimming drive mode MC of the dimming drive mode MC having a relatively small thermal load. In the drive pattern, the thermal load applied to the first electrode 92 becomes insufficient, and the protrusion 552p may not be sufficiently grown. In addition, the protrusion 552p may be likely to be thinner than when the drive power Wd has a relatively long state in which the value of the drive power Wd is a value close to the rated power or the rated power. Thereby, the life of the discharge lamp 90 may be reduced. In the case where the state where the value of the driving power Wd is relatively smaller than the rated power is provided relatively long, the state where the value of the driving power Wd is relatively smaller than the rated power is relatively long. It includes the case where the drive power Wd is provided continuously over time and the case where the state where the value of the drive power Wd is relatively smaller than the rated power is frequently provided across other states.

  On the other hand, according to the present embodiment, the control unit 40, when the ratio of the period in which the value of the driving power Wd in the determination period PHj is equal to or less than the predetermined value is larger than the predetermined ratio, The driving mode 230 is switched from the first dimming driving mode Md1 to the second dimming driving mode Md2. In the second dimming drive mode Md2, the thermal load applied to the first electrode 92 is larger than that in the first dimming drive mode Md1. Therefore, when the state in which the value of the drive power Wd is relatively smaller than the rated power is provided for a relatively long time in the first dimming drive mode Md1, a heat load can be suitably applied to the first electrode 92. The protrusion 552p can be preferably grown. Further, the protrusion 552p can be thickened. Thereby, according to this embodiment, the lifetime of the discharge lamp 90 can be improved.

  Further, according to the present embodiment, in the dimming drive mode MC, the drive pattern of the drive current I changes according to the change of the drive power Wd. The drive pattern of the drive current I when the value of the drive power Wd is equal to or less than a predetermined value in the second dimming drive mode Md2 is the low power drive pattern DWL. The low power driving pattern DWL has a larger thermal load applied to the first electrode 92 than the driving pattern DW1 of the driving current I when the value of the driving power Wd is equal to or less than a predetermined value in the first dimming driving mode Md1. For this reason, in the second dimming drive mode Md2, when the value of the drive power Wd becomes a relatively small value than the rated power, the heat load applied to the first electrode 92 can be increased by the low power drive pattern DWL. it can. Therefore, in the second dimming drive mode Md2, it is easy to suitably apply a heat load to the first electrode 92, and it is easy to grow the protrusion 552p suitably. Therefore, the life of the discharge lamp 90 can be further improved.

  In addition, according to the present embodiment, the drive pattern of the drive current I supplied to the discharge lamp 90 when the drive power Wd becomes a predetermined value or less in the second dimming drive mode Md2 is released in the low power drive mode ML. The drive pattern of the drive current I supplied to the lamp 90 is the same. Therefore, when the value of the drive power Wd is relatively smaller than the rated power in the second dimming drive mode Md2, the thermal load is applied to the first electrode 92 as in the case of executing the low power drive mode ML. Thus, the protrusion 552p can be grown more suitably. Therefore, the life of the discharge lamp 90 can be further improved.

  Further, according to the present embodiment, the driving pattern of the driving current I supplied to the discharge lamp 90 when the value of the driving power Wd is larger than the predetermined value in the second dimming driving mode Md2 is the first dimming driving. This is the same as the drive pattern of the drive current I supplied to the discharge lamp 90 when the value of the drive power Wd is larger than a predetermined value in the mode Md1. Therefore, when the value of the driving power Wd in the second dimming driving mode Md2 is larger than the value close to the driving power Wd supplied to the discharge lamp 90 in the low power driving mode ML, the first dimming driving mode Md1 Similarly, the heat load applied to the first electrode 92 can be suitably adjusted by changing the drive pattern. Thereby, the lifetime of the discharge lamp 90 can be further improved.

  Further, according to the present embodiment, the control unit 40, when the second predetermined time has elapsed since the driving mode of the discharge lamp driving unit 230 was switched from the first dimming driving mode Md1 to the second dimming driving mode Md2. Then, the driving mode of the discharge lamp driving unit 230 is switched from the second dimming driving mode Md2 to the first dimming driving mode Md1. Therefore, the first dimming drive mode Md1 and the second dimming drive mode Md2 are preferably switched to easily apply a heat load to the first electrode 92. Thereby, the lifetime of the discharge lamp 90 can be further improved.

  For example, as the discharge lamp 90 is deteriorated, the protrusion 552p of the first electrode 92 is less likely to grow. On the other hand, according to the present embodiment, the control unit 40 changes the second predetermined time described above according to the lamp voltage Vla of the discharge lamp 90. Therefore, the execution time of the second dimming drive mode Md2 can be changed according to the deterioration of the discharge lamp 90. Specifically, the execution time of the second dimming drive mode Md2 is increased as the lamp voltage Vla is increased as the lamp voltage Vla is increased, so that the discharge lamp 90 is degraded. The heat load applied to the first electrode 92 can be increased. Thereby, even when the discharge lamp 90 is deteriorated, the protrusion 552p can be grown. Therefore, the life of the discharge lamp 90 can be further improved.

  In the present embodiment, the following configurations and methods may be employed.

  In the second dimming drive mode Md2, the control unit 40 sets the drive mode of the discharge lamp drive unit 230 when the ratio of the period during which the value of the drive power Wd in the determination period PHj is equal to or less than a predetermined value is equal to or less than a predetermined ratio. The second dimming drive mode Md2 may be switched to the first dimming drive mode Md1. That is, in the dimming drive mode MC, the control unit 40 has a low power drive pattern DWL in a period in which the drive power Wd is equal to or less than a predetermined value, and the drive power Wd in the predetermined period (determination period PHj). When the ratio of the period in which the value is equal to or less than the predetermined value is equal to or less than the predetermined ratio, the drive pattern in the period in which the drive power Wd is equal to or less than the predetermined value is switched from the low power drive pattern DWL to the drive pattern DW1. According to this configuration, the first dimming drive mode Md1 and the second dimming drive mode Md2 can be suitably switched according to the state of change in the value of the driving power Wd. Therefore, the life of the discharge lamp 90 can be further improved.

  Further, the drive pattern of the drive current I supplied to the discharge lamp 90 when the value of the drive power Wd is equal to or less than a predetermined value in the second dimming drive mode Md2 is supplied to the discharge lamp 90 in the low power drive mode ML. The driving current I may not be the low power driving pattern DWL. In this case, the drive pattern of the drive current I supplied to the discharge lamp 90 when the value of the drive power Wd is equal to or less than a predetermined value in the second dimming drive mode Md2 is applied to the first electrode 92 rather than the drive pattern DW1. If the thermal load is large, the thermal load applied to the first electrode 92 may be smaller or larger than the low power drive pattern DWL.

  In the second dimming drive mode Md2, the drive pattern does not have to change according to the drive power Wd. In this case, in the second dimming drive mode Md2, the control unit 40 continues to supply the drive current I having the same drive pattern to the discharge lamp 90 regardless of the change in the drive power Wd. Also, in the first dimming drive mode Md1, the drive pattern may not change according to the drive power Wd.

  In addition, in the second dimming drive mode Md2, the control unit 40 reduces the total power of the period tw1 during which the drive power Wd is within the first range WA1, that is, the low power after switching to the second dimming drive mode Md2. When the cumulative time during which the drive current I of the drive pattern DWL is supplied to the discharge lamp 90 becomes longer than the third predetermined time, the drive mode of the discharge lamp drive unit 230 is changed from the second dimming drive mode Md2 to the first. You may switch to the dimming drive mode Md1.

  For example, even after switching to the second dimming drive mode Md2, the drive power Wd does not fall within the first range WA1, that is, the drive power Wd falls within the second range WA2 or the third range WA3. The drive pattern of the drive current I is the same as the drive pattern of the drive current I supplied in the first dimming drive mode Md1. Therefore, even if the dimming drive mode MC is switched to the second dimming drive mode Md2, the drive current I of the low power drive pattern DWL is hardly supplied to the discharge lamp 90 depending on how the drive power Wd is changed. It may be difficult to apply a sufficient heat load to one electrode 92.

  On the other hand, in the second dimming drive mode Md2, when the cumulative time during which the drive current I of the low power drive pattern DWL is supplied to the discharge lamp 90 is greater than the third predetermined time, the discharge lamp driving unit 230 By switching the driving mode from the second dimming driving mode Md2 to the first dimming driving mode Md1, the time during which the driving current I of the low power driving pattern DWL is supplied to the discharge lamp 90 is secured for a third predetermined time. can do. Therefore, a sufficient thermal load can be applied to the first electrode 92 in the second dimming drive mode Md2 regardless of how the drive power Wd changes.

  Further, the control unit 40 may lengthen the above-described third predetermined time as the lamp voltage Vla increases. As described above, when the drive power Wd is within the second range WA2 or the third range WA3, the drive pattern of the drive current I supplied to the discharge lamp 90 in the second dimming drive mode Md2 is the first. It is the same as the drive pattern of the drive current I supplied to the discharge lamp 90 in the dimming drive mode Md1. Therefore, even if the execution time of the second dimming drive mode Md2 is increased, that is, the second predetermined time is lengthened, the drive current I of the low power drive pattern DWL is supplied to the discharge lamp 90 depending on how the drive power Wd changes. The accumulated time may not change or may become shorter.

  In contrast, when the discharge lamp 90 is deteriorated by increasing the third predetermined time as the lamp voltage Vla increases, the drive current I of the low power drive pattern DWL in the second dimming drive mode Md2 is released. The accumulated time supplied to the electric lamp 90 can be increased, and a heat load can be suitably applied to the first electrode 92.

  FIG. 12 is a diagram illustrating another example of the change in the drive pattern of the drive current I with respect to the change in the drive power Wd in the dimming drive mode MC. The upper diagram of FIG. 12 is a diagram showing changes in the drive power Wd, the vertical axis shows the drive power Wd, and the horizontal axis shows the time T. The lower diagram of FIG. 12 is a schematic diagram showing changes in the drive pattern of the drive current I, and the horizontal axis shows time T.

  As shown in FIG. 12, in the first dimming drive mode Md1, the control unit 40 is a period in which the value of the drive power Wd is equal to or less than a predetermined value, that is, in this embodiment, the value of the drive power Wd is within the first range WA1. When the length tw1 of the period becomes larger than a predetermined length, the driving mode of the discharge lamp driving unit 230 may be switched from the first dimming driving mode Md1 to the second dimming driving mode Md2. In this case, the control unit 40 determines that the value of the drive power Wd in the determination period PHj is a predetermined value when the length tw1 of the period in which the value of the drive power Wd is within the first range WA1 is greater than the predetermined length. It is determined that the ratio of the following period has become larger than the predetermined ratio. The predetermined length is, for example, about 0.5 min (min) or more and 2 min (min) or less.

  In the example illustrated in FIG. 12, the control unit 40 determines that the length tw1 of the period in which the value of the drive power Wd is within the first range WA1 during the period in which the drive power Wd is the first power Wd1 is greater than the predetermined length When it becomes larger, the driving mode of the discharge lamp driving unit 230 is switched from the first dimming driving mode Md1 to the second dimming driving mode Md2. Accordingly, the drive pattern is switched from the drive pattern DW1 to the low power drive pattern DWL during the period in which the drive power Wd is the first power Wd1.

  In the above-described embodiment, an example in which the present invention is applied to a transmissive projector has been described. However, the present invention can also be applied to a reflective projector. Here, the “transmission type” means that a liquid crystal light valve including a liquid crystal panel or the like is a type that transmits light. “Reflective type” means that the liquid crystal light valve reflects light. The light modulation device is not limited to a liquid crystal panel or the like, and may be a light modulation device using a micromirror, for example.

  In the above-described embodiment, the example of the projector 500 using the three liquid crystal panels 560R, 560G, and 560B (liquid crystal light valves 330R, 330G, and 330B) has been described. However, the present invention uses only one liquid crystal panel. The present invention can also be applied to a projector using four or more liquid crystal panels.

  In addition, the configurations described in the above embodiments can be combined with each other within a consistent range.

  DESCRIPTION OF SYMBOLS 10 ... Discharge lamp lighting device (discharge lamp drive device), 40 ... Control part, 90 ... Discharge lamp, 92 ... 1st electrode (electrode), 93 ... 2nd electrode (electrode), 200 ... Light source device, 230 ... Discharge lamp Drive unit, 330R, 330G, 330B ... Liquid crystal light valve (light modulation device), 350 ... Projection optical system, 500 ... Projector, 502, 512R, 512G, 512B ... Image signal, DW1 ... Drive pattern (first drive pattern), DW2, DW3 ... drive pattern, DWL ... low power drive pattern (second drive pattern), I ... drive current, MC ... dimming drive mode (second mode), ML ... low power drive mode (first mode), PHj ... judgment period (predetermined period), Vla ... lamp voltage (interelectrode voltage), Wd ... drive power, Wd2 ... second power (predetermined value)

Claims (9)

A discharge lamp driving section for supplying a driving current to a discharge lamp having an electrode;
A control unit for controlling the discharge lamp driving unit;
With
The discharge lamp driving unit has a first mode in which predetermined driving power is supplied to the discharge lamp, and a second mode in which the value of the driving power changes with time.
In the second mode, the control unit changes a driving pattern of the driving current supplied to the discharge lamp according to a change in the driving power,
In the second mode, when the ratio of the period in which the value of the driving power in the predetermined period is equal to or less than the predetermined value is greater than the predetermined ratio, the control unit is in the period in which the driving power is equal to or less than the predetermined value. A discharge lamp driving device, wherein the driving pattern is switched from the first driving pattern to a second driving pattern in which a thermal load applied to the electrode is larger than the first driving pattern.   2. The discharge lamp drive device according to claim 1, wherein the second drive pattern is the same as the drive pattern of the drive current supplied to the discharge lamp in the first mode.   When the predetermined time has elapsed since the control unit switched from the first drive pattern to the second drive pattern, the control unit changes the drive pattern in the period in which the drive power is equal to or less than the predetermined value from the second drive pattern to the second drive pattern. The discharge lamp driving device according to claim 1, wherein the discharge lamp driving device is switched to the first driving pattern.   The discharge lamp driving device according to claim 3, wherein the control unit changes the predetermined time according to a voltage between the electrodes of the discharge lamp.   The control unit makes the predetermined time when the interelectrode voltage becomes a first voltage longer than the predetermined time when the interelectrode voltage becomes a second voltage lower than the first voltage. Item 5. The discharge lamp driving device according to Item 4.   In the second mode, the control unit is configured such that a driving pattern in a period in which the driving power is equal to or less than the predetermined value is the second driving pattern, and a value of the driving power in the predetermined period is equal to or less than the predetermined value. 2. When the ratio of the period to be equal to or less than the predetermined ratio, the drive pattern in the period in which the drive power is equal to or less than the predetermined value is switched from the second drive pattern to the first drive pattern. 2. The discharge lamp driving device according to 2. A discharge lamp that emits light;
The discharge lamp driving device according to any one of claims 1 to 6,
A light source device comprising: The light source device according to claim 7;
A light modulation device that modulates light emitted from the light source device according to an image signal;
A projection optical system that projects the light modulated by the light modulation device;
A projector comprising: A discharge lamp driving method for driving a discharge lamp by supplying a driving current to a discharge lamp having an electrode,
A first mode in which predetermined driving power is supplied to the discharge lamp; and a second mode in which the value of the driving power changes with time.
In the second mode, the drive pattern of the drive current supplied to the discharge lamp is changed according to the change in the drive power,
In the second mode, when the ratio of the period in which the value of the driving power in the predetermined period is equal to or less than the predetermined value is greater than the predetermined ratio, the driving pattern in the period in which the driving power is equal to or less than the predetermined value is A discharge lamp driving method characterized by switching from one driving pattern to a second driving pattern in which a thermal load applied to the electrode is larger than the first driving pattern.

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