JP6547337B2 - Discharge lamp driving device, light source device, projector, and discharge lamp driving method - Google Patents

Description

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

  For example, Patent Document 1 discloses a discharge lamp in which an alternating current having a steady lighting frequency and an alternating current having a frequency lower than the steady lighting frequency are supplied to a discharge lamp to form a protrusion at an electrode tip of the discharge lamp. A lighting device is described.

Unexamined-Japanese-Patent No. 2006-59790

  By the way, the projections on the electrode tip of the discharge lamp (discharge lamp) are less likely to be formed as they deteriorate. Therefore, in the method of driving a discharge lamp as described above, when the discharge lamp is deteriorated, it is difficult to maintain a stable electrode shape. As a result, there is a possibility that the life of the discharge lamp can not be sufficiently improved.

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

  According to one aspect of the discharge lamp drive device of the present invention, a discharge lamp drive unit for supplying a drive current to a discharge lamp, a control unit for controlling the discharge lamp drive unit, and a voltage for detecting an inter-electrode voltage of the discharge lamp A detection unit, wherein the control unit can execute first control and second control for supplying the drive current including a direct current and an alternating current to the discharge lamp, and the electrode at a predetermined setting timing In the case where the inter-voltage is equal to or less than the threshold voltage, the first control is performed, and in the case where the inter-electrode voltage is larger than the threshold voltage at the predetermined setting timing, the second control is performed. The ratio of the direct current is characterized by being larger than the ratio of the direct current in the first control.

  According to one aspect of the discharge lamp driving device of the present invention, the first control and the second control are appropriately executed according to the voltage between the electrodes. The proportion of direct current in the second control is larger than the proportion of direct current in the first control. Therefore, when the protrusion at the electrode tip of the discharge lamp is worn out by the first control and the inter-electrode voltage becomes larger than the threshold voltage, the protrusion is switched by switching to the second control in which the ratio of direct current is larger than the first control. Can grow.

Here, for example, after switching to the second control, if the control of the discharge lamp driving unit is continued by the second control, the electrode is melted, and as a result, the protrusion is formed, but the electrode body in which the protrusion is formed is worn out And the shape of the stable electrode can not be maintained.
On the other hand, according to one aspect of the discharge lamp driving device of the present invention, after switching to the second control, when the protrusion grows and the inter-electrode voltage becomes equal to or less than the threshold voltage, the discharge lamp drive The control method of the unit is switched to the first control again. Thereby, wear and tear of the electrode body can be suppressed. In addition, the inter-electrode voltage can be maintained within a certain range centered on the threshold voltage.

  As described above, according to one aspect of the discharge lamp driving device of the present invention, by appropriately switching the first control and the second control, a stable electrode shape is maintained while maintaining the inter-electrode voltage in a certain range. Can be maintained. As a result, the life of the discharge lamp can be improved.

The alternating current in the first control includes a first alternating current having a first frequency, and a second alternating current having a second frequency lower than the first frequency, and the control unit determines the threshold voltage. The ratio of the first alternating current and the ratio of the second alternating current may be adjusted based on the above.
According to this configuration, since the drive current waveform in the first control can be appropriately set based on the magnitude of the threshold voltage, the life of the discharge lamp can be further improved.

The control unit makes the ratio of the second alternating current larger than the ratio of the first alternating current when the threshold voltage is equal to or less than a predetermined value, and when the threshold voltage is larger than a predetermined value, the first control unit The ratio of the alternating current may be larger than the ratio of the second alternating current.
According to this configuration, it is possible to appropriately set the first control with respect to the threshold voltage by determining whether the threshold voltage is equal to or less than a predetermined value.

The first frequency may be 500 Hz or more.
According to this configuration, excessive wear of the electrode can be suppressed.

The second frequency may be 280 Hz or less.
According to this configuration, excessive growth of the electrode can be suppressed.

The predetermined setting timing may be provided at predetermined time intervals.
According to this configuration, since the first control and the second control can be alternately performed for a certain period of time, it is easy to maintain a stable electrode shape.

  One aspect of the light source device of the present invention is characterized by comprising the discharge lamp for emitting light and the discharge lamp driving device described above.

  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 a projector according to the present invention is a light source device described above, a light modulation element that modulates light emitted from the light source device according to a video signal, and a projection that projects light modulated by the light modulation element And an optical system.

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

  One aspect of the discharge lamp driving method according to the present invention is a discharge lamp driving method for driving a discharge lamp by supplying a driving current to the discharge lamp, wherein the discharge lamp includes a direct current and an alternating current. When the voltage between the electrodes is equal to or less than the threshold voltage at a predetermined setting timing, including the first control and the second control for supplying the driving current, the first control is executed, and the voltage between the electrodes at the predetermined setting timing Is larger than the threshold voltage, the second control is performed, and the ratio of the direct current in the second control is larger than the ratio of the direct current in the first control.

  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 sectional drawing of the discharge lamp in this embodiment. FIG. 2 is a block diagram showing various components of the projector of the present embodiment. It is a circuit diagram of the discharge lamp lighting device of this embodiment. It is a block diagram showing an example of 1 composition of a control part of this embodiment. It is a figure which shows the appearance of the processus | protrusion of the electrode tip of a discharge lamp. It is a flowchart which shows an example of the control procedure of the discharge lamp drive part by the control part of this embodiment. It is a figure which shows an example of the drive current waveform of this embodiment. It is a figure which shows an example of the drive current waveform of this embodiment. It is a figure which shows the change of the electrode of a discharge lamp.

Hereinafter, a projector according to an embodiment of the present invention will be described with reference to the drawings.
The scope of the present invention is not limited to the following embodiments, 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 intelligible, a scale, the number, etc. in an actual structure and each structure may be varied.

  As shown in FIG. 1, a projector 500 according to this 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 elements) 330R. 330G, 330B, a cross dichroic prism 340, and a projection optical system 350.

  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 the 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 modulated three 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). Thus, an image is displayed on the screen 700. As the configuration of each 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 known configuration can be adopted.

  FIG. 2 is a cross-sectional view showing the configuration of the light source device 200. As shown in FIG. The light source device 200 includes a light source unit 210 and a discharge lamp lighting device (discharge lamp driving device) 10. A cross-sectional view of the light source unit 210 is shown in FIG. The light source unit 210 includes a main reflector 112, a discharge lamp 90, and a sub reflector 50.

  The discharge lamp lighting device 10 supplies a drive current I to the discharge lamp 90 to light the discharge lamp 90. The main reflector 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-like shape extending along the irradiation direction D. One end of the discharge lamp 90 is a first end 90 e 1, and the other end of the discharge lamp 90 is a second end 90 e 2. The material of the discharge lamp 90 is, for example, a translucent material such as quartz glass. The central portion of the discharge lamp 90 bulges in a spherical shape, and the inside thereof is a discharge space 91. In the discharge space 91, a gas which is a discharge medium containing a rare gas, a metal halide compound and the like is sealed.

  The tips of the first electrode (electrode) 92 and the second electrode (electrode) 93 project into the discharge space 91. The first electrode 92 is disposed on the first end 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 shapes of the first electrode 92 and the second electrode 93 are in the shape of bars extending along the optical axis AX. In the discharge space 91, electrode tip portions of the first electrode 92 and the second electrode 93 are disposed to face each other with a predetermined distance therebetween. 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 penetrating the inside of the discharge lamp 90. Similarly, a second terminal 546 is provided at the second end 90 e 2 of the discharge lamp 90. The second terminal 546 and the second electrode 93 are electrically connected by a conductive member 544 penetrating 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 drive 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. The light (discharge light) generated by the arc discharge is emitted in all directions from the discharge position, as indicated by the broken arrow.

  The main reflecting mirror 112 is fixed to a first end 90 e 1 of the discharge lamp 90 by a fixing member 114. The main reflecting mirror 112 reflects, of the discharge light, light traveling toward the opposite side to the irradiation direction D toward the irradiation direction D. The shape of the reflection surface (surface on the discharge lamp 90 side) of the main reflection mirror 112 is not particularly limited in the range in which the discharge light can be reflected in the irradiation direction D, and for example, even if it is a rotation elliptical shape It may be parabolic. For example, when the shape of the reflecting surface of the main reflecting mirror 112 is a paraboloid of revolution, 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 reflection mirror 50 is fixed to the second end 90 e 2 side of the discharge lamp 90 by a fixing member 522. The shape of the reflection surface (surface on the discharge lamp 90 side) of the sub-reflecting mirror 50 is a spherical shape surrounding a portion on the second end 90 e 2 side of the discharge space 91. The sub-reflecting mirror 50 reflects, toward the main reflecting mirror 112, light traveling toward the side opposite to the side where the main reflecting mirror 112 is disposed among the discharge light. Thereby, the utilization efficiency of the light radiated from the discharge space 91 can be enhanced.

  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 generation 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 50 and the discharge lamp 90 is not limited to the method of fixing the main reflecting mirror 112 and the sub reflecting mirror 50 to the discharge lamp 90, but any method can be adopted. . For example, the discharge lamp 90 and the main reflecting mirror 112 may be fixed to the housing (not shown) of the projector 500 independently. The same applies to the sub-reflecting mirror 50.

Hereinafter, the circuit configuration of the projector 500 will be described.
FIG. 3 is a diagram showing an example of a circuit configuration of the projector 500 of the present embodiment. 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, in addition to the optical system shown in FIG. And.

  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 of a predetermined word length to generate image signals 512R, 512G, and 512B. The image processing device 570 is supplied.

  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, 572B for driving the liquid crystal panels 560R, 560G, 560B to the liquid crystal panels 560R, 560G, 560B.

  The DC power supply device 80 converts an AC voltage supplied from the 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 the 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 start-up to cause 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.

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

  The CPU 580 controls various operations from the lighting start of the projector 500 to the lighting off. For example, in the example of FIG. 3, the lighting instruction and the lighting off instruction are 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 showing an example of a circuit configuration of the discharge lamp lighting device 10. As shown in FIG.
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 to be supplied to the discharge lamp 90. In the present embodiment, the power control circuit 20 is configured of a down chopper circuit that receives a voltage from the DC power supply device 80, 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 configured 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.

  The other end of the coil 23 is connected to one end of the capacitor 24, 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 80. A current control signal is input to the control terminal of the switch element 21 from the control unit 40 described later to control ON / OFF of the switch element 21. 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 along the path passing through the capacitor 24 and the diode 22. As a result, a direct current Id is generated in accordance with the ratio of the time during which the switch element 21 is turned on.

  The polarity inverting 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 inverting circuit 30 generates and outputs a drive current I which is a direct current which lasts for a controlled time, or a drive current I which 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, each of which is a transistor or the like. In the polarity inverting 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 with each other. It has composition. A polarity inversion control signal from the control unit 40 is input to 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. 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 based on the polarity inversion control signal.

  In the polarity inverting 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 of the first switch element 31 and the second switch element 32 and the common connection point of the third switch element 33 and the fourth switch element 34. A drive current I which is a direct current which continues the same polarity state only, or a drive current I which is an alternating current having a controlled frequency is generated and output.

  That is, in the polarity inverting circuit 30, 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, and the first switch element 31 and the third switch element 33 When the fourth switch element 34 is off, control is performed so that the second switch element 32 and the third switch element 33 are 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. Do. When the second switch element 32 and the third switch element 33 are ON, a drive current I is generated which flows from the 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.

  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 a drive 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 to maintain the drive current I in the same polarity for the holding time, the current value of the drive current I (power value of the drive power Control parameters such as frequency). The control unit 40 performs polarity inversion control on the polarity inversion circuit 30 to control the holding time in which the drive current I continues with the same polarity and the frequency of the drive current I at the polarity inversion timing of the drive current I. The control unit 40 performs current control on the power control circuit 20 to control the current value of the output direct current Id.

  The control unit 40 can execute the first control and the second control for supplying the drive current I including the direct current and the alternating current to the discharge lamp 90 as a control method of the discharge lamp driving unit 230. The control unit 40 selects one of the first control and the second control based on the lamp voltage (inter-electrode voltage) Vla, and controls the discharge lamp driving unit 230. Details will be described later.

  The configuration of the control unit 40 is not particularly limited. In the present embodiment, the control unit 40 is configured to include a system controller 41, a power control circuit controller 42, and a polarity inversion circuit controller 43. The control unit 40 may be configured partially or entirely 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 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 the information stored in the storage unit 44. The storage unit 44 may store, for example, information on drive parameters such as a retention time in which the drive current I continues with the same polarity, a current value of the drive current I, a fundamental frequency, a waveform, and a modulation pattern. The fundamental frequency is the frequency of the drive current I supplied to the discharge lamp 90 in the steady lighting mode.

  In the present embodiment, the storage unit 44 uses, for example, a drive current waveform of the drive current I supplied to the discharge lamp 90 in each of the first control and the second control, and is used to select the first control and the second control described later. The value of threshold voltage Vla1 and the like are stored.

  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 a 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 by using a dedicated circuit, and can perform the above-described control and various controls of processing to be described later. On the other hand, the control unit 40 can function as a computer, for example, by the CPU executing 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. 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 inversion control unit 40-2 that controls the polarity inversion circuit 30 according to a control program. It may be done.

  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 be responsible for a part of the functions 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. In addition, 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 based on the voltage divided by the first resistor 61 and the second resistor 62 connected in series with each other in parallel with the discharge lamp 90 . Further, in the present embodiment, the current detection unit detects the drive current I by the voltage generated in the third resistor 63 connected in series to the discharge lamp 90.

  The igniter circuit 70 operates only at the start of lighting of the discharge lamp 90. The igniter circuit 70 performs high voltage (discharge) necessary to form 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. The 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 tip portions of the first electrode 92 and the second electrode 93. As shown in FIG. Protrusions 552 p and 562 p are formed on the tips of the first electrode 92 and the second electrode 93, respectively. The protrusion 552 p protrudes from the electrode body 92 a of the first electrode 92 toward the second electrode 93. The protrusion 562 p protrudes from the electrode main body 93 a of the second electrode 93 toward the first electrode 92.

  The discharge generated between the first electrode 92 and the second electrode 93 mainly occurs between the protrusion 552 p and the protrusion 562 p. When the protrusions 552 p and 562 p are present 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 are no protrusions.

  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). The collision generates heat and the temperature of the tip (protrusion 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 (protrusion 562p) of the second electrode 93 rises.

  Thus, by supplying the drive current I to the discharge lamp 90, the temperature of the anode with which the electrons collide increases. On the other hand, the temperature of the cathode emitting electrons decreases while emitting electrons toward the anode.

  The inter-electrode 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 away. 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 inter-electrode distance, that is, the degree of deterioration of the discharge lamp 90.

  Since the first electrode 92 and the second electrode 93 have the same configuration, in the following description, only the first electrode 92 may be representatively described. Further, 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 representatively described.

Next, control of the discharge lamp driving unit 230 by the control unit 40 of the present embodiment will be described.
FIG. 7 is a flowchart showing a procedure of control of the discharge lamp driving unit 230 by the control unit 40 of the present embodiment.

  After the start of lighting of the discharge lamp 90 (step S1), the control unit 40 measures the lamp voltage Vla by the voltage detection unit of the operation detection unit 60 (step S2). Then, the control unit 40 determines whether the measured lamp voltage Vla is less than or equal to the threshold voltage Vla1 (step S3). If the measured lamp voltage Vla is equal to or lower than the threshold voltage Vla1 (step S3: YES), the control unit 40 sets the control method of the discharge lamp driving unit 230 to the first control (step S4). If the measured lamp voltage Vla is larger than the threshold voltage Vla1 (step S3: NO), the control unit 40 sets the control method of the discharge lamp driving unit 230 to the second control (step S5). The control unit 40 controls the discharge lamp driving unit 230 according to the set control method (step S6).

  In the first control and the second control, the discharge lamp 90 is supplied with a drive current I including a direct current and an alternating current. The proportion of direct current in the second control is larger than the proportion of direct current in the first control.

  FIGS. 8A to 8C and FIGS. 9A to 9C are diagrams showing examples of portions of drive current waveforms in the first control and the second control. In FIGS. 8A to 8C and FIGS. 9A to 9C, the vertical axis indicates the driving current I, and the horizontal axis indicates the time T. The drive current I is shown as positive when it is in the first polarity state and as negative when it is in the second polarity state.

The waveforms shown in FIGS. 8A to 8C and FIGS. 9A to 9C are drive current waveforms per unit time t1. In the following description, portions of drive current waveforms shown in FIGS. 8A to 8C and 9A to 9C will be referred to as unit waveforms.

  In the present embodiment, the drive current waveforms in the first control and the second control are configured by combining the unit waveforms shown in FIGS. 8A to 8C and 9A to 9C. .

  A unit waveform DWa1 shown in FIG. 8A includes a DC period PH11 in which a DC current is supplied to the discharge lamp 90, and an opposite polarity period PH21 in which a current of the opposite polarity to the DC period PH11 is supplied to the discharge lamp 90. Have.

  In the direct current period PH11, the driving current I of the first polarity having a constant current value Im is supplied to the discharge lamp 90. In the opposite polarity period PH21, the drive current I of the second polarity having a constant current value -Im is supplied to the discharge lamp 90.

  The unit waveform DWb1 shown in FIG. 8B and the unit waveform DWc1 shown in FIG. 8C are current waveforms of alternating current whose polarity is inverted a plurality of times between the current value Im1 and the current value -Im1. The frequency (second frequency) of the alternating current (second alternating current) in the unit waveform DWc1 is lower than the frequency (first frequency) of the alternating current (first alternating current) in the unit waveform DWb1. In other words, the alternating current in the first control and the alternating current in the second control include a first alternating current having a first frequency and a second alternating current having a second frequency lower than the first frequency.

  The frequency (first frequency) of the alternating current in the unit waveform DWb1 is, for example, 500 Hz or more. The frequency (second frequency) of the alternating current in the unit waveform DWc1 is, for example, 280 Hz or less. By setting the frequency of the alternating current in the unit waveforms DWb1 and DWc1 in this manner, the protrusion 552p of the first electrode 92 can be easily maintained in a stable shape.

  A unit waveform DWa2 shown in FIG. 9A includes a DC period PH12 in which a DC current is supplied to the discharge lamp 90, and an opposite polarity period PH22 in which a current of the opposite polarity to the DC period PH12 is supplied to the discharge lamp 90. Have. The unit waveform DWa2 is the same as the unit waveform DWa1 except that the polarity is inverted.

The unit waveform DWb2 shown in FIG. 9B is the same as the unit waveform DWb1 except that the polarity is inverted.
The unit waveform DWc2 shown in FIG. 9C is the same as the unit waveform DWc1 except that the polarity is inverted.

  In the first control of the present embodiment, a cycle C11 in which the unit waveform DWa1, the unit waveform DWb1, the unit waveform DWc1, the unit waveform DWa2, the unit waveform DWb2, and the unit waveform DWc2 are arranged in this order is repeated. Each unit waveform is provided once or a plurality of times in one cycle C11. An example of the cycle C11 of the first control is shown in Table 1.

  In the example of Table 1, in cycle C11, unit waveform DWa1 is one time, unit waveform DWb1 is one time, unit waveform DWc1 is continuous 1000 times, unit waveform DWa2 is one time, unit waveform DWb2 is one time, unit waveform The DWc2 is provided 1000 times in succession in this order.

  In the second control of the present embodiment, as in the first control, the cycle C2 in which the unit waveform DWa1, the unit waveform DWb1, the unit waveform DWc1, the unit waveform DWa2, the unit waveform DWa2, the unit waveform DWb2, and the unit waveform DWc2 are arranged in this order is repeated. . Each unit waveform is provided once or a plurality of times in one cycle C2. An example of the cycle C2 of the second control is shown in Table 2.

  In the example of Table 2, in the cycle C2, the unit waveform DWa1 is continuously performed four times, the unit waveform DWb1 is continuously performed twelve times, the unit waveform DWc1 is continuously performed one time, and the unit waveform DWa2 is continuously performed four times. The unit waveform DWb2 is continuously provided 12 times, and the unit waveform DWc2 is continuously provided once in this order.

  As shown in Tables 1 and 2, the ratio of the unit waveforms DWa1 and DWa2 in the cycle C2 of the second control is larger than the ratio of the unit waveforms DWa1 and DWa2 in the cycle C11 of the first control. In other words, the DC current in the second control, that is, the ratio of the DC periods PH11 and PH12 is larger than the DC current in the first control, that is, the ratio of the DC periods PH11 and PH12.

  In the present specification, the ratio of the direct current in the first control or the second control means the ratio of the time when the direct current is supplied to the discharge lamp 90 to the execution time when the first control or the second control is executed. It is.

  Returning to FIG. 7, the control unit 40 determines whether or not a predetermined time has elapsed since the control of the discharge lamp driving unit 230 by the set control method (step S7). If the predetermined time has not elapsed (step S7: NO), the control unit 40 controls the discharge lamp driving unit 230 by the control method set subsequently. If the predetermined time has passed (step S7: YES), the control unit 40 again measures the lamp voltage Vla (step S2), and sets the control method (steps S3 to S5).

  That is, in the present embodiment, the lamp voltage Vla is measured (step S2), and the control method of the discharge lamp driving unit 230 is set (steps S3 to S5). The predetermined setting timing is provided for each predetermined time.

  The predetermined time from the predetermined setting timing to the next predetermined setting timing is preferably set to 60 seconds (seconds) or more, and more preferably set to about 300 seconds (seconds). By setting the predetermined time in this manner, it is possible to execute the first control and the second control for a relatively long time, and it is easy to maintain the protrusion 552p of the first electrode 92 in a stable shape.

The control of the control unit 40 described above will be described more specifically.
When the initial lamp voltage Vla of the discharge lamp 90 is 65 V, the threshold voltage Vla1 is set to 70 V, for example. At the initial stage of lighting of the discharge lamp 90, the lamp voltage Vla is equal to or lower than the threshold voltage Vla1. Therefore, the control unit 40 sets the control method of the discharge lamp driving unit 230 to the first control, and controls the discharge lamp driving unit 230 by the first control.

  When the discharge lamp 90 is driven for a long time by the first control, the discharge lamp 90 is degraded to make it difficult to form the protrusions 552p, and the distance between the electrodes becomes large. Thereby, the lamp voltage Vla rises. When the lamp voltage Vla becomes larger than the threshold voltage Vla1, the control unit 40 sets the control method of the discharge lamp driving unit 230 from the first control to the second control at a predetermined setting timing.

  Here, the ratio of the direct current in the second control is larger than the ratio of the direct current in the first control. Therefore, in the second control, the first electrode 92 is easily melted, and the protrusion 552p is easily formed as compared with the first control. As a result, the protrusions 552p grow, the distance between the electrodes becomes smaller, and the lamp voltage Vla becomes smaller. Then, when the lamp voltage Vla becomes equal to or lower than the threshold voltage Vla1, the control unit 40 sets the control method of the discharge lamp driving unit 230 to the first control again at a predetermined setting timing.

  By repeating the setting of the first control and the second control described above, the lamp voltage Vla is maintained within a certain range centered on the threshold voltage Vla1 while repeatedly rising and falling at the threshold voltage Vla1. Ru.

  The control by the control unit 40 described above can also be expressed as a discharge lamp driving method. That is, the discharge lamp driving method of the present embodiment is a discharge lamp driving method of supplying the drive current I to the discharge lamp 90 to drive the discharge lamp 90, and the discharge lamp 90 includes a direct current and an alternating current. When the lamp voltage Vla is equal to or lower than the threshold voltage Vla1 at a predetermined setting timing, including the first control and the second control for supplying the driving current I, the first control is executed, and the lamp voltage Vla is a threshold at the predetermined setting timing When the voltage is larger than the voltage Vla1, the second control is performed, and the ratio of the direct current in the second control is characterized by being larger than the ratio of the direct current in the first control.

  According to the present embodiment, the control unit 40 can execute the first control and the second control in which the ratio of the direct current is larger than that of the first control. The control unit 40 controls the discharge lamp driving unit 230 by setting the first control or the second control based on the lamp voltage Vla. Therefore, according to the present embodiment, the life of the discharge lamp 90 can be improved. The details will be described below.

For example, when supplying a plurality of drive current which is a combination of alternating current and a direct current of a frequency to the discharge lamp 90, in the initial stage, the protrusions 552p are formed. However, as the discharge lamp 90 is deteriorated due to long-term use, the protrusions 552p may be gradually less likely to be formed, and a stable electrode shape may not be maintained.

  FIGS. 10A to 10C are diagrams showing changes of the first electrode 92 of the discharge lamp 90. FIG. FIG. 10A is a diagram showing the first electrode 92 when the discharge lamp 90 is driven for a long time using only the first control. FIG. 10B is a diagram showing the first electrode 92 when the discharge lamp 90 is driven for a long time using only the second control. FIG. 10C is a diagram showing a case where the discharge lamp 90 is driven for a long time by appropriately setting the first control and the second control as described above.

  As shown in FIG. 10A, for example, when the control of the discharge lamp driving unit 230 is continued for a long time using the first control, the protrusion 552p of the first electrode 92 disappears, and the tip of the electrode main body 92a is flat. It becomes a shape.

  On the other hand, in the second control, since the ratio of direct current is larger than that in the first control, the first electrode 92 is easily melted, and the protrusion 552p is easily grown as compared to the first control. However, as shown in FIG. 10B, when the control of the discharge lamp driving unit 230 is continued for a long time using the second control, the projection 552p of the first electrode 92 is formed, but the electrode main body 92a is consumed. Become thinner.

  Thus, only by using one control method, for example, any one of the first control and the second control, the discharge lamp 90 is driven for a long time to be deteriorated, so that the first electrode 92 is deteriorated. In some cases, the life of the discharge lamp 90 can not be sufficiently improved.

  On the other hand, according to the present embodiment, the first control and the second control are appropriately set according to whether the lamp voltage Vla is equal to or lower than the threshold voltage Vla1, and the first control and the second control Are alternately repeated. Therefore, in the present embodiment, as shown in FIG. 10C, the protrusion 552p is formed by the second control at the tip of the electrode body 92a to be planarized by the first control. Thus, according to the present embodiment, the shape of the first electrode 92 can be stably maintained even when driven for a long time.

  As described above, according to the present embodiment, the shape of the protrusion 552p of the first electrode 92 can be stably maintained, and as described above, the lamp voltage Vla is in a certain range centered on the threshold voltage Vla1. Easy to maintain for a long time inside. As a result, according to the present embodiment, the life of the discharge lamp 90 can be improved.

  Further, for example, when the drive power supplied to the discharge lamp 90 changes, such as a 3D-compatible projector, the discharge lamp 90 is particularly easily degraded. Therefore, when the drive power supplied to the discharge lamp 90 changes, the effect of the present embodiment is particularly large.

  Further, according to the present embodiment, the predetermined setting timing at which the first control and the second control are set is provided at predetermined time intervals. Therefore, for example, even if the lamp voltage Vla becomes equal to or lower than the threshold voltage Vla1 immediately after switching from the first control to the second control, until the predetermined time elapses after switching to the second control, The discharge lamp 90 is driven by the second control. Thereby, since it is possible to alternately execute the first control and the second control for a certain period of time, it is easy to maintain the shape of the first electrode 92 in a stable shape. Therefore, according to the present embodiment, the life of the discharge lamp 90 can be further improved.

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

  In the present embodiment, the predetermined setting timing at which the control method is set may be provided once each time the power of the projector 500 is turned on. In this case, the discharge lamp driving unit 230 is controlled by only one of the first control and the second control during one period from when the power of the projector 500 is turned on to when it is turned off. Ru.

  Further, in the present embodiment, based on the value of threshold voltage Vla1, control unit 40 determines unit waveforms DWb1 and DWb2 in the first control, that is, the ratio of the first alternating current, and unit waveform DWc1 in the first control. The DWc 2, that is, the ratio of the second alternating current may be adjusted.

  Specifically, when the threshold voltage Vla1 is equal to or less than a predetermined value, the control unit 40 sets the ratio of the unit waveforms DWc1 and DWc2 larger than the ratio of the unit waveforms DWb1 and DWb2 as shown in Table 1. When threshold voltage Vla1 is larger than a predetermined value, control unit 40 sets the ratio of unit waveforms DWb1 and DWb2 larger than the ratio of unit waveforms DWc1 and DWc2. The predetermined value is, for example, a value of about +5 V with respect to the initial lamp voltage Vla.

  The example of the first control shown in Table 1 is, for example, an example where the threshold voltage Vla1 is equal to or less than a predetermined value. On the other hand, Table 3 shows an example of the first control when the threshold voltage Vla1 is larger than a predetermined value.

  In the example of Table 3, in the cycle C12 of the first control, the unit waveform DWa1 is once, the unit waveform DWb1 is continuously 1000 times, the unit waveform DWc1 is once, the unit waveform DWa2 is once, and the unit waveform DWb2 is continuous. Then, the unit waveform DWc2 is provided once in this order 1000 times.

  As described above, by alternately repeating the first control and the second control, the lamp voltage Vla is maintained within a predetermined range centered on the threshold voltage Vla1. Therefore, when threshold voltage Vla1 is relatively small, the maintained lamp voltage Vla is relatively small. That is, the first electrode 92 of the discharge lamp 90 is maintained in a relatively low degree of deterioration. In this case, the projections 552p may grow excessively in the first control, and the shape of the first electrode 92 of the discharge lamp 90 may not be stably maintained.

  On the other hand, according to this configuration, when threshold voltage Vla1 is relatively small, that is, less than a predetermined value, the ratio of unit waveforms DWb1 and DWb2 in cycle C11 of the first control illustrated in Table 1 The ratio of unit waveforms DWc1 and DWc2 is set larger than that. The alternating current having a low frequency gives a large thermal load to the first electrode 92, and the protrusion 552p is easily melted. Therefore, by making the ratio of unit waveforms DWc1 and DWc2 whose frequencies are lower than unit waveforms DWb1 and DWb2 larger than the ratio of unit waveforms DWb1 and DWb2, excessive growth of the protrusion 552p can be suppressed.

  On the other hand, when the threshold voltage Vla1 is relatively large, the maintained lamp voltage Vla becomes relatively large. That is, the first electrode 92 of the discharge lamp 90 is maintained in a state in which the degree of deterioration is relatively large. In this case, the deterioration of the first electrode 92 tends to progress, and the first electrode 92 may be worn out excessively.

  On the other hand, according to this configuration, when threshold voltage Vla1 is relatively large, that is, larger than the predetermined value, in cycle C12 of the first control illustrated in Table 3, unit waveforms DWc1 and DWc2 are selected. The ratio of unit waveforms DWb1 and DWb2 is set larger than the ratio. Therefore, by setting the ratio of unit waveforms DWb1 and DWb2 whose frequency is higher than that of unit waveforms DWc1 and DWc2 larger than the ratio of unit waveforms DWc1 and DWc2, excessive wear of protrusion 552p can be suppressed.

  Further, the above-described effect of this configuration is more pronounced when the frequency (first frequency) of unit waveforms DWb1 and DWb2 is set to 500 Hz or more and the frequency (second frequency) of unit waveforms DWc1 and DWc2 is set to 280 Hz or less. It is obtained large.

  Further, in the above description, the drive current waveforms in the first control and the second control are configured to be composed of a direct current and two types of alternating currents having different frequencies, but the present invention is not limited to this. In the present embodiment, the alternating current constituting the drive current waveform in the first control and the second control may be of one type, or may include three or more types of alternating current having different frequencies. Furthermore, in the present embodiment, two or more types of direct current may be used to form the drive current waveform in the first control and the second control. The two or more types of direct current include two or more types of direct current having different absolute values of the current value supplied to the discharge lamp 90.

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

  In the above embodiment, an example of the projector 500 using the three liquid crystal panels 560R, 560G, 560B (liquid crystal light valves 330R, 330G, 330B) has been described, but the present invention uses only one liquid crystal panel The present invention is also applicable to a projector that has been used or a projector that uses four or more liquid crystal panels.

  Moreover, each structure demonstrated above can be combined suitably in the range which does not contradiction mutually.

  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 element) 350 Projection optical system 500 Projector I Drive current Vla Lamp voltage (voltage between electrodes) Vla1 threshold voltage

Claims (8)

A discharge lamp drive unit for supplying a drive current to the discharge lamp;
A control unit that controls the discharge lamp driving unit;
A voltage detection unit that detects an inter-electrode voltage of the discharge lamp;
Equipped with
The control unit
It is possible to execute first control and second control for supplying the drive current including direct current and alternating current to the discharge lamp,
If the inter-electrode voltage is equal to or lower than a threshold voltage at a predetermined setting timing, the first control is performed,
If the inter-electrode voltage is larger than the threshold voltage at the predetermined setting timing, the second control is performed,
The proportion of the DC current in the second control is much larger than the percentage of the DC current in the first control,
The alternating current in the first control includes a first alternating current having a first frequency, and a second alternating current having a second frequency lower than the first frequency,
The control unit
When the threshold voltage is equal to or less than a predetermined value, the ratio of the second alternating current is made larger than the ratio of the first alternating current,
A discharge lamp driving device characterized in that, when the threshold voltage is larger than a predetermined value, the ratio of the first alternating current is made larger than the ratio of the second alternating current . The discharge lamp driving device according to claim 1, wherein
A discharge lamp driving device, wherein a total length of DC periods to which the DC current is supplied in the second control is larger than a total length of DC periods to which the DC current is supplied in the first control. The discharge lamp driving device according to claim 1 or 2 , wherein
The discharge lamp driving device, wherein the first frequency is 500 Hz or more. The discharge lamp driving device according to any one of claims 1 to 3 , wherein
The discharge lamp driving device, wherein the second frequency is 280 Hz or less. The discharge lamp driving device according to any one of claims 1 to 4 , wherein
The discharge lamp driving device, wherein the predetermined setting timing is provided every predetermined time. The discharge lamp emitting light;
A discharge lamp driving device according to any one of claims 1 to 5 ,
A light source device comprising: A light source device according to claim 6 ,
A light modulation element that modulates light emitted from the light source device according to a video signal;
A projection optical system that projects the light modulated by the light modulation element;
A projector comprising: A discharge lamp driving method for driving a discharge lamp by supplying a driving current to the discharge lamp, comprising:
Detecting an inter-electrode voltage of the discharge lamp;
Performing a first control of supplying a driving current including a direct current and an alternating current to the discharge lamp when the inter-electrode voltage is equal to or lower than a threshold voltage at a predetermined setting timing;
Performing a second control of supplying a driving current including a direct current and an alternating current to the discharge lamp when the inter-electrode voltage is larger than the threshold voltage at the predetermined setting timing;
Including
The proportion of the DC current in the second control is much larger than the percentage of the DC current in the first control,
The alternating current in the first control includes a first alternating current having a first frequency, and a second alternating current having a second frequency lower than the first frequency,
When the threshold voltage is equal to or less than a predetermined value, the ratio of the second alternating current is made larger than the ratio of the first alternating current,
A method of driving a discharge lamp , wherein the ratio of the first alternating current is made larger than the ratio of the second alternating current when the threshold voltage is larger than a predetermined value .

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