JP5673222B2 - projector - Google Patents

Description

  The present invention relates to a projector.

  Projectors using discharge lamps such as high-pressure mercury lamps and metal halide lamps have been put into practical use. When the discharge lamp continues to operate with the power supplied to the discharge lamp lowered while maintaining the lighting state, the electrode temperature of the discharge lamp decreases, and blackening occurs in which electrode materials (tungsten, etc.) are deposited on the discharge lamp envelope. The phenomenon tends to occur. When the blackening phenomenon occurs, the blackened portion absorbs light and the temperature of the discharge lamp rises, and the glass used for the envelope crystallizes, causing devitrification. When the devitrification phenomenon occurs, the illuminance of the discharge lamp is reduced and the envelope is easily damaged. Therefore, it is important not to cause the blackening phenomenon in order to extend the life of the discharge lamp.

  In order to extend the life of a discharge lamp, for example, Patent Document 1 discloses a discharge lamp that changes the power supplied to the discharge lamp using a power change pattern whose parameters are a power change range, a power change period, and a change waveform. A lighting device is disclosed.

JP 2005-209572 A

  However, when the power supplied to the discharge lamp is changed in the projector, there arises a problem that the brightness changes. For this reason, in order to apply the discharge lamp lighting device disclosed in Patent Document 1 to a projector, in order to obtain a change in brightness such that the user cannot visually recognize the change, There were restrictions.

  The present invention has been made in view of the above problems. According to some aspects of the present invention, it is possible to provide a projector that can suppress deterioration of a discharge lamp while suppressing a change in brightness.

  The projector according to the present invention includes a plurality of light source units and a control unit that controls the light source unit, wherein the light source units supply driving power to the discharge lamp and the discharge lamp, respectively. A discharge lamp drive unit that drives the discharge lamp drive unit, wherein the control unit sets a total value of the drive power supplied to each of the discharge lamps to a constant value and supplies the drive to each of the discharge lamps Each of the discharge lamp driving units is controlled so as to supply power to each of the discharge lamps while changing electric power over time.

  According to the present invention, the discharge lamp driving unit is controlled so as to be supplied to the discharge lamp while changing the driving power with time, so that the state where the electrode temperature of the discharge lamp is low does not continue for a long time. Therefore, a projector that can suppress the deterioration of the discharge lamp can be realized.

  In addition, according to the present invention, the discharge lamp driving unit is controlled so that the total value of the driving power supplied to the respective discharge lamps becomes a constant value, so that it is possible to realize a projector that can suppress a change in brightness.

  In the projector, each of the discharge lamp driving units supplies an AC current as a driving current to the discharge lamp to supply the driving power to the discharge lamp, and the control unit has a polarity of the driving current. The discharge lamp driving unit may be controlled so as to supply the driving current to each of the discharge lamps so that the average value of the driving power per one inversion period is temporally changed.

  Thereby, the electrode temperature of the discharge lamp can be increased more reliably, and the state where the electrode temperature of the discharge lamp is low is not continued for a long time. Thereby, the occurrence of the blackening phenomenon of the discharge lamp can be suppressed.

  In this projector, the minimum value of the driving power supplied to each of the discharge lamps may be electric power that allows each of the discharge lamps to maintain a lighting state.

  As a result, the discharge lamp can be kept lit even if the supplied driving power changes. Therefore, when the projected image is brightened based on the user's operation or the like, it is not necessary to relight the discharge lamp, and the brightness can be changed in a short time.

Explanatory drawing which shows the optical system of the projector 500 which concerns on this embodiment. Explanatory drawing which shows the structure of the light source part 200-1. FIG. 3 is a diagram illustrating an example of a circuit configuration of a projector according to an embodiment. The figure which shows an example of the circuit structure of the discharge lamp lighting device 10-1. The figure for demonstrating the other structural example of the light source control part. 6A to 6D are explanatory diagrams showing the relationship between the polarity of the drive current I supplied to the discharge lamp 90-1 and the electrode temperature. 7A, 7B, and 7C are graphs for explaining an example of drive power control in the projector 500 according to the present embodiment. 6 is a timing chart schematically showing an example of the relationship between the driving power W1 and the driving current I in the projector 500 according to the present embodiment. FIG. 9A, FIG. 9B, and FIG. 9C are graphs for explaining a first modified example of drive power control in the projector 500 according to the present embodiment. FIGS. 10A, 10 </ b> B, and 10 </ b> C are graphs for explaining a second modified example of the drive power control in the projector 500 according to the present embodiment. FIGS. 11A, 11 </ b> B, and 11 </ b> C are graphs for explaining a third modification of control of driving power in the projector 500 according to the present embodiment. FIGS. 12A, 12 </ b> B, and 12 </ b> C are graphs for explaining a fourth modification of control of drive power in the projector 500 according to the present embodiment. FIG. 13A, FIG. 13B, and FIG. 13C are graphs for explaining a fifth modification of control of drive power in the projector 500 according to the present embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. FIG. 1 is an explanatory diagram showing an optical system of a projector 500 according to the present embodiment. The projector 500 includes a light source unit 200-1, a collimating lens 305, an illumination optical system 310, a color separation optical system 320, three liquid crystal light valves 330R, 330G, and 330B, a cross dichroic prism 340, and projection optics. System 350. As will be described later, the projector 500 according to the present embodiment includes a plurality of light source units. More specifically, the projector 500 according to the present embodiment includes two light source units 200-1 and 200-2. In addition, since the structure of the light source part 200-1 and the light source part 200-2 is the same, illustration of the light source part 200-2 is abbreviate | omitted in FIG. Moreover, the number of light source parts should just be two or more, and may be three or more.

  Each of the plurality of light source units 200-1 and 200-2 includes a discharge lamp and a discharge lamp driving unit that drives the discharge lamp by supplying driving power to the discharge lamp. In the example shown in FIG. 1, the light source unit 200-1 supplies driving power to the light source unit 210-1 configured to include the discharge lamp 90-1 and the discharge lamp 90-1, and the discharge lamp 90- 1 and a discharge lamp lighting device 10-1 configured to include a discharge lamp driving unit 230-1 (described later).

  In the example shown in FIG. 1, the light source unit 210-1 has a main reflecting mirror 112-1 and a sub-reflecting mirror 50-1 (described later). The main reflecting mirror 112-1 reflects the light emitted from the discharge lamp 90-1 in the irradiation direction D. The irradiation direction D is parallel to the optical axis AX. The light from the light source unit 210-1 passes through the collimating lens 305 and enters the illumination optical system 310. The collimating lens 305 collimates the light from the light source unit 210-1.

  The illumination optical system 310 makes the illuminance of light from the light source unit 200-1 uniform in the liquid crystal light valves 330R, 330G, and 330B. Further, the illumination optical system 310 aligns the polarization direction of the light from the light source unit 200-1 in one direction. This is because the light from the light source unit 200-1 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 (R), green (G), and blue (B). The three color lights are respectively modulated by the liquid crystal light valves 330R, 330G, and 330B associated with the respective colors. The liquid crystal light valves 330R, 330G, and 330B include liquid crystal panels 560R, 560G, and 560B (described later) and polarizing plates (not shown) disposed on the light incident side and the emission 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 a screen (not shown). As a result, an image is displayed on the screen.

  Note that various well-known configurations can be adopted as the configurations 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.

  FIG. 2 is an explanatory diagram illustrating a configuration of the light source unit 200-1. The configuration of the light source unit 200-2 is the same as that of the light source unit 200-1. The light source unit 200-1 includes a light source unit 210-1 and a discharge lamp lighting device 10-1. In the drawing, a cross-sectional view of the light source unit 210-1 is shown. The light source unit 210-1 includes a main reflecting mirror 112-1, a discharge lamp 90-1, and a sub-reflecting mirror 50-1.

  The shape of the discharge lamp 90-1 is a rod shape extending along the irradiation direction D from the first end 90e1 to the second end 90e2. The material of the discharge lamp 90-1 is, for example, a translucent material such as quartz glass. The central portion of the discharge lamp 90-1 swells in a spherical shape, and a discharge space 91-1 is formed therein. The discharge space 91-1 is filled with a gas that is a discharge medium containing mercury, a rare gas, a metal halogen compound, and the like.

  The discharge lamp 90-1 includes a first electrode 92-1 and a second electrode 93-1. In the example shown in FIG. 2, the first electrode 92-1 and the second electrode 93-1 are provided so as to protrude into the discharge space 91-1. The first electrode 92-1 is disposed on the first end 90e1 side of the discharge space 91-1, and the second electrode 93-1 is disposed on the second end 90e2 side of the discharge space 91-1. The shapes of the first electrode 92-1 and the second electrode 93-1 are rod shapes extending along the optical axis AX. In the discharge space 91-1, the electrode tip portions (also referred to as “discharge ends”) of the first electrode 92-1 and the second electrode 93-1 face each other with a predetermined distance. The material of the first electrode 92-1 and the second electrode 93-1 is a metal such as tungsten, for example.

  A first terminal 536 is provided at the first end 90e1 of the discharge lamp 90-1. The first terminal 536 and the first electrode 92-1 are electrically connected by a conductive member 534 that passes through the inside of the discharge lamp 90-1. Similarly, a second terminal 546 is provided at the second end 90e2 of the discharge lamp 90-1. The second terminal 546 and the second electrode 93-1 are electrically connected by a conductive member 544 that passes through the inside of the discharge lamp 90-1. The material of the first terminal 536 and the second terminal 546 is, for example, a metal such as tungsten. Further, as each 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 10-1. The discharge lamp lighting device 10-1 supplies driving power to the discharge lamp 90-1 by supplying a driving current for driving the discharge lamp 90-1 to the first terminal 536 and the second terminal 546. As a result, arc discharge occurs between the first electrode 92-1 and the second electrode 93-1. The light (discharge light) generated by the arc discharge is radiated in all directions from the discharge position, as indicated by the dashed arrow.

  The main reflecting mirror 112-1 is fixed to the first end 90e1 of the discharge lamp 90-1 by a fixing member 114. The shape of the reflecting surface (surface on the discharge lamp 90-1 side) of the main reflecting mirror 112-1 is a spheroid shape. The main reflecting mirror 112-1 reflects the discharge light in the irradiation direction D. The shape of the reflecting surface of the main reflecting mirror 112-1 is not limited to the spheroid shape, and various shapes that reflect the discharge light toward the irradiation direction D can be employed. For example, a rotating parabolic shape may be adopted. In this case, the main reflecting mirror 112-1 can convert the discharge light into light substantially parallel to the optical axis AX. Therefore, the collimating lens 305 can be omitted.

  The sub-reflecting mirror 50-1 is fixed to the second end 90e2 side of the discharge lamp 90-1 by a fixing member 522. The shape of the reflecting surface (surface on the discharge lamp 90-1 side) of the sub-reflecting mirror 50-1 is a spherical shape that surrounds the second end 90e2 side of the discharge space 91-1. The sub-reflecting mirror 50-1 reflects the discharge light toward the main reflecting mirror 112-1. Thereby, the utilization efficiency of the light radiated | emitted from the discharge space 91-1 can be improved.

  In addition, as a material of the fixing members 114 and 522, any heat-resistant material (for example, an inorganic adhesive) that can withstand the heat generated by the discharge lamp 90-1 can be used. As a method of fixing the arrangement of the main reflecting mirror 112-1, the sub reflecting mirror 50-1, and the discharge lamp 90-1, the main reflecting mirror 112-1 and the sub reflecting mirror 50-1 are replaced with the discharge lamp 90-1. Any method can be adopted without being limited to the fixing method. For example, the discharge lamp 90-1 and the main reflecting mirror 112-1 may be independently fixed to a housing (not shown) of the projector. The same applies to the sub-reflecting mirror 50-1.

2. 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 described above, the projector 500 includes a video signal conversion unit 510, a DC power supply device 80, liquid crystal panels 560R, 560G, and 560B, a video processing device 570, a control unit 580, and an operation reception unit 590. Also good.

  The video signal converter 510 converts an externally input video signal 502 (such as a luminance-color difference signal or an analog RGB signal) into a digital RGB signal having a predetermined word length to generate video signals 512R, 512G, and 512B. This is supplied to the video processing device 570. In addition, the video signal conversion unit 510 may output information on the presence / absence of wiring for inputting the video signal 502 and information on the presence / absence of the video signal 502 to the control unit 580 via the communication signal 514.

  The video processing device 570 performs video processing on each of the three video signals 512R, 512G, and 512B, and supplies driving signals 572R, 572G, and 572B for driving the liquid crystal panels 560R, 560G, and 560B, respectively, to the liquid crystal panels 560R and 560G. 560B. Based on the drive signals 572R, 572G, and 572B input to the liquid crystal panels 560R, 560G, and 560B, an image is projected onto the screen 700 by the optical system described with reference to FIG.

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

  The discharge lamp lighting device 10-1 generates a high voltage between the electrodes of the discharge lamp 90-1 at the time of start-up to cause a dielectric breakdown to form a discharge path, and thereafter, the discharge lamp 90-1 is maintained for discharging. The driving power is supplied by supplying the driving current to the discharge lamp 90-1 by the discharge lamp driving unit 230-1 of the discharge lamp lighting device 10-1. The discharge lamp lighting device 10-2 generates a high voltage between the electrodes of the discharge lamp 90-2 at the time of startup to cause a dielectric breakdown to form a discharge path, and thereafter the discharge lamp 90-2 is maintained for discharging. The driving power is supplied by supplying the driving current to the discharge lamp 90-2 by the discharge lamp driving unit 230-2 of the discharge lamp lighting device 10-2.

  The liquid crystal panels 560R, 560G, and 560B modulate the luminance of the color light incident on each liquid crystal panel via the optical system described above based on the drive signals 572R, 572G, and 572B, respectively.

  The operation reception unit 590 receives an operation 592 for the projector 500 and outputs information related to the operation 592 to the control unit 580 via the communication signal 594. The operation reception unit 590 may include various known configurations such as buttons, levers, and switches.

  The control unit 580 controls the operation from the start of lighting of the projector to the extinction thereof. The control unit 580 outputs, for example, a lighting command or a light-off command to the discharge lamp lighting device 10-1 of the light source unit 200-1 via the communication signal 582 or the light source unit 200-2 via the communication signal 586. It may be output to the discharge lamp lighting device 10-2. Further, the control unit 580 receives lighting information indicating the lighting state of the discharge lamp 90-1 from the discharge lamp lighting device 10-1 of the light source unit 200-1 via the communication signal 584, or the light source unit 200-2. Lighting information indicating the lighting state of the discharge lamp 90-2 may be received from the discharge lamp lighting device 10-2 via the communication signal 588. Further, the control unit 580 may receive information regarding the operation 592 received by the operation receiving unit 590 via the communication signal 594. In the present embodiment, the control unit 580 controls the light source units 200-1 and 200-2 based on the communication signal 594.

  Note that the control unit 580 can be realized by a dedicated circuit to perform the above-described control and various types of control of processing to be described later. For example, a CPU (Central Processing Unit) is stored in a storage unit (not illustrated) or the like. It is also possible to function as a computer by executing the control program and to perform various controls of these processes.

3. Configuration of Discharge Lamp Lighting Device in the Present Embodiment FIG. 4 is a diagram illustrating an example of a circuit configuration of the discharge lamp lighting device 10-1. The circuit configuration of the discharge lamp lighting device 10-2 is the same as that of the discharge lamp lighting device 10-1.

  The discharge lamp lighting device 10-1 includes a power control circuit 20. The power control circuit 20 generates drive power to be supplied to the discharge lamp 90-1. In the present embodiment, the power control circuit 20 includes a down chopper circuit that receives the DC power supply 80 and steps down the input voltage to output a DC current Id.

  The power control circuit 20 can include a switch element 21, a diode 22, a coil 23, and a capacitor 24. The switch element 21 can be 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 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 80. A power control signal is input to the control terminal of the switch element 21 from a light source 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 power control signal.

  Here, 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 discharge lamp lighting device 10-1 includes a polarity inversion circuit 30. The polarity inversion circuit 30 receives the direct current Id output from the power control circuit 20 and reverses the polarity at a given timing, so that the polarity inversion circuit 30 can be a direct current that lasts for a controlled time or has an arbitrary frequency. The drive current I is generated and output. 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, and the first switch element 31 connected in series. The switch element 31 and the second switch element 32, and the third switch element 33 and the fourth switch element 34 connected in series are connected in parallel to each other. Polarity inversion control signals are input from the light source 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 the signal, ON / OFF of the first switch element 31, the second switch element 32, the third switch element 33, and the fourth switch element 34 is controlled.

  The polarity inversion circuit 30 repeats the ON / OFF operation of the first switch element 31 and the fourth switch element 34, and the second switch element 32 and the third switch element 33 alternately. The polarity of the direct current Id to be output is alternately inverted, and the common connection point between the first switch element 31 and the second switch element 32 and the common connection between the third switch element 33 and the fourth switch element 34. From this point, a drive current I that is a direct current that lasts for a controlled time or an alternating current that has a controlled frequency is generated and output.

  That is, 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 turned OFF, and the first switch element 31 and the fourth switch element 34 are When the switch is OFF, the second switch element 32 and the third switch element 33 are controlled to be turned ON. Therefore, when the first switch element 31 and the fourth switch element 34 are ON, the drive current I flows from the one end of the capacitor 24 in the order of the first switch element 31, the discharge lamp 90-1, and the fourth switch element 34. Occurs. When the second switch element 32 and the third switch element 33 are ON, the drive current I flows from the one end of the capacitor 24 in the order of the third switch element 33, the discharge lamp 90-1, and the second switch element 32. Occurs.

  In the present embodiment, the power control circuit 20 and the polarity inversion circuit 30 are combined to correspond to the discharge lamp driving unit 230-1. That is, the discharge lamp driving unit 230-1 supplies the driving electric power to the discharge lamp 90-1 by driving the discharge lamp 90-1 by supplying the driving current I to the discharge lamp 90-1.

  The discharge lamp lighting device 10-1 may include a light source control unit 40. In the example shown in FIG. 4, the light source control unit 40 receives operation mode information that is information related to the operation mode determined by the determination unit 150 configured as a part of the control unit 580 via the communication signal 582. The discharge lamp driving unit 230-1 is controlled based on the received operation mode information.

  In the example shown in FIG. 4, the light source control unit 40 controls the power control circuit 20 and the polarity inversion circuit 30 so that the driving power and the driving current I supplied to the discharge lamp 90-1 have the same polarity. The holding time to be continued, the current value of the drive current I, the frequency, and the like are controlled. The light source control unit 40 performs polarity reversal control for controlling the holding time for the drive current I to remain the same polarity, the frequency of the drive current I, and the like based on the polarity reversal timing of the drive current I. Further, the light source control unit 40 controls the power control circuit 20 to control the driving power supplied to the discharge lamp 90-1 by controlling the current value of the output direct current Id. .

  The configuration of the light source control unit 40 is not particularly limited, but in the present embodiment, the light source control unit 40 includes a system controller 41, a power control circuit controller 42, and a polarity inversion circuit controller 43. . The light source control unit 40 may be partially or entirely configured with a semiconductor integrated circuit.

  The system controller 41 controls the power control circuit 20 and the polarity reversing circuit 30 by controlling the power control circuit controller 42 and the polarity reversing circuit controller 43. The system controller 41 is based on the drive voltage Vla and the drive current I detected by the voltage detection unit of the state detection unit 60 provided in the discharge lamp lighting device 10-1 to be described later. The circuit controller 43 may be controlled.

  In the present embodiment, the system controller 41 includes a storage unit 44. The storage unit 44 may be provided independently of 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 information on 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 power 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 light source control unit 40 can be realized by a dedicated circuit to perform the above-described control and various types of control of processing to be described later. For example, a CPU (Central Processing Unit) is stored in the storage unit 44 or the like. By executing the control program, it can function as a computer to perform various controls of these processes. FIG. 5 is a diagram for explaining another configuration example of the light source control unit 40. As shown in FIG. 5, the light source control unit 40 functions as power control means 40-1 for controlling the power control circuit 20 and polarity inversion control means 40-2 for controlling the polarity inversion circuit 30 according to the control program. You may comprise.

  In the example shown in FIG. 4, the light source control unit 40 is configured as a part of the discharge lamp lighting device 10-1, but the control unit 580 takes part or all of the functions of the light source control unit 40. It may be configured as follows.

  The discharge lamp lighting device 10-1 may include an operation detection unit 60. The operation detection unit 60 may include, for example, a voltage detection unit that detects the drive voltage Vla of the discharge lamp 90-1 and outputs drive voltage information, and a current detection unit that detects the drive current I and outputs drive current information. Good. In the present embodiment, the voltage detection unit is configured to include the first and second resistors 61 and 62, and the current detection unit is configured to include the third resistor 63.

  In the present embodiment, the voltage detection unit detects the drive voltage Vla by 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 90-1. 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 90-1.

  The discharge lamp lighting device 10-1 may include an igniter circuit 70. The igniter circuit 70 operates only at the start of lighting of the discharge lamp 90-1, and between the electrodes of the discharge lamp 90-1 (between the first electrode 92 and the second electrode 93) at the start of lighting of the discharge lamp 90-1. A high voltage (a voltage higher than that during normal lighting of the discharge lamp 90-1) necessary for forming a discharge path by dielectric breakdown is transferred between the electrodes of the discharge lamp 90-1 (the first electrode 92 and the second electrode 93). During). In the present embodiment, the igniter circuit 70 is connected in parallel with the discharge lamp 90-1.

4). Relationship between Polarity of Drive Current and Electrode Temperature FIGS. 6A to 6D are explanatory diagrams showing the relationship between the polarity of the drive current I supplied to the discharge lamp 90-1 and the electrode temperature. . Note that the description in this section regarding the discharge lamp 90-1 holds true for the discharge lamp 90-2. 6A and 6B show the operating state of the first electrode 92-1 and the second electrode 93-1. In the drawing, the tip portions of the first electrode 92-1 and the second electrode 93-1 are shown. Protrusions 552p and 562p are provided at the tips of the first electrode 92-1 and the second electrode 93-1, respectively. The discharge generated between the first electrode 92-1 and the second electrode 93-1 mainly occurs between the protrusion 552p and the protrusion 562p. In the present embodiment, the movement of the discharge position (arc position) in the first electrode 92-1 and the second electrode 93-1 can be suppressed as compared with the case where there is no protrusion. However, such protrusions may be omitted.

  FIG. 6A shows a first polarity state P1 in which the first electrode 92-1 operates as an anode and the second electrode 93-1 operates as a cathode. In the first polarity state P1, electrons move from the second electrode 93-1 (cathode) to the first electrode 92-1 (anode) by discharge. Electrons are emitted from the cathode (second electrode 93-1). Electrons emitted from the cathode (second electrode 93-1) collide with the tip of the anode (first electrode 92-1). Heat is generated by this collision, and the temperature of the tip (projection 552p) of the anode (first electrode 92-1) rises.

  FIG. 6B shows a second polarity state P2 in which the first electrode 92-1 operates as a cathode and the second electrode 93-1 operates as an anode. In the second polarity state P2, in contrast to the first polarity state P1, electrons move from the first electrode 92-1 to the second electrode 93-1. As a result, the temperature of the tip (projection 562p) of the second electrode 93-1 rises.

  Thus, the temperature of the anode tends to be higher than that of the cathode. Here, the continued high state of the temperature of one electrode compared to the other electrode can cause various problems. For example, when the tip of the high temperature electrode melts excessively, unintended electrode deformation may occur. As a result, the arc length may deviate from an appropriate value. Moreover, when the melting | fusing of the front-end | tip of a low-temperature electrode is inadequate, the fine unevenness | corrugation produced at the front-end | tip may remain without melting. As a result, a so-called arc jump may occur (the arc position moves without being stable).

  As a technique for suppressing such inconvenience, an AC drive that supplies the discharge lamp 90-1 with an AC current that repeatedly changes the polarity of each electrode can be used as the drive current I. FIG. 6C is a timing chart showing an example of the drive current I supplied to the discharge lamp 90-1 (FIG. 2). The horizontal axis indicates time T, and the vertical axis indicates the current value of the drive current I. The drive current I indicates a current flowing through the discharge lamp 90-1. A positive value indicates the first polarity state P1, and a negative value indicates the second polarity state P2. In the example shown in FIG. 6C, a rectangular wave alternating current is used as the drive current I. In the example shown in FIG. 6C, the first polarity state P1 and the second polarity state P2 are alternately repeated. Here, the first polarity section Tp indicates the time that the first polarity state P1 continues, and the second polarity section Tn indicates the time that the second polarity state P2 continues. In the example shown in FIG. 6C, the average current value in the first polarity section Tp is Im1, and the average current value in the second polarity section Tn is -Im2. The frequency of the drive current I suitable for driving the discharge lamp 90-1 can be determined experimentally according to the characteristics of the discharge lamp 90-1 (for example, a value in the range of 30 Hz to 1 kHz is adopted). ) Other values Im1, −Im2, Tp, and Tn can be determined experimentally in the same manner.

  FIG. 6D is a timing chart showing a temperature change of the first electrode 92-1. The horizontal axis represents time T, and the vertical axis represents temperature H. In the first polarity state P1, the temperature H of the first electrode 92-1 increases, and in the second polarity state P2, the temperature H of the first electrode 92-1 decreases. Further, since the first polarity state P1 and the second polarity state P2 state are repeated, the temperature H periodically changes between the minimum value Hmin and the maximum value Hmax. In addition, although illustration is abbreviate | omitted, the temperature of the 2nd electrode 93-1 changes with the phase opposite to the temperature H of the 1st electrode 92-1. That is, in the first polarity state P1, the temperature of the second electrode 93-1 decreases, and in the second polarity state P2, the temperature of the second electrode 93-1 increases.

  In the first polarity state P1, the tip of the first electrode 92-1 (projection 552p) is melted, so the tip of the first electrode 92-1 (projection 552p) is smooth. Thereby, the movement of the discharge position in the first electrode 92-1 can be suppressed. In addition, since the temperature of the tip of the second electrode 93-1 (projection 562p) falls, excessive melting of the second electrode 93-1 (projection 562p) is suppressed. Thereby, unintended electrode deformation can be suppressed. In the second polarity state P2, the positions of the first electrode 92-1 and the second electrode 93-1 are reversed. Therefore, by repeating the two states P1 and P2, problems in each of the first electrode 92-1 and the second electrode 93-1 can be suppressed.

  Here, when the waveform of the current I is symmetric, that is, when the waveform of the current I satisfies the condition “| Im1 | = | −Im2 |, Tp = Tn”, the first electrode 92-1 and the second electrode The condition of the supplied electric power is the same between the two electrodes 93-1. Therefore, if the first electrode 92-1 and the second electrode 93-1 have the same thermal conditions (ease of temperature rise and fall), the first electrode 92-1 and the second electrode 93-1 It is estimated that the temperature difference between them becomes small.

  Further, if the electrode is heated too much over a wide range (an arc spot (a hot spot on the electrode surface accompanying arc discharge) becomes large), the shape of the electrode is destroyed due to excessive melting. On the other hand, if the electrode is too cold (the arc spot is small), the tip of the electrode cannot be melted sufficiently, and the tip cannot be returned smoothly, that is, the tip of the electrode is easily deformed. Therefore, when the uniform energy supply state is continued with respect to the electrode, the tip of the electrode (the protrusion 552p and the protrusion 562p) easily deforms into an unintended shape.

  If the electric power supplied to the first electrode 92-1 and the second electrode 93-1 of the discharge lamp 90-1 is kept down while the lighting state of the discharge lamp 90-1 is maintained, the discharge lamp 90- The temperature of the first electrode 92-1 and the second electrode 93-1 decreases, and a blackening phenomenon in which an electrode material (tungsten or the like) precipitates on the envelope of the discharge lamp 90-1 is likely to occur. When the blackening phenomenon occurs, the blackened portion absorbs light and the temperature of the discharge lamp rises, and the glass used for the envelope crystallizes, causing devitrification. When the devitrification phenomenon occurs, the illuminance of the discharge lamp decreases or the envelope is easily damaged.

5. Next, a specific example of driving power control in the projector 500 according to the present embodiment will be described.

  In the present embodiment, the control unit 580 of the projector 500 sets the total value WT of the driving power supplied to the respective discharge lamps 90-1 and 90-2 to a constant value, and also uses the respective discharge lamps 90-1 and 90. -2 is controlled such that the driving power W1 and W2 supplied to -2 are supplied to the respective discharge lamps 90-1 and 90-2 while being temporally changed. To do.

  When the discharge lamp driving units 230-1 and 230-2 supply driving power to the discharge lamps 90-1 and 90-2 by supplying an alternating current as the driving current I to the discharge lamps 90-1 and 90-2. Alternatively, the driving power W1 supplied to the discharge lamp 90-1 and the driving power W2 supplied to the discharge lamp 90-2 may be average power per cycle of the driving current I.

  FIG. 7A, FIG. 7B, and FIG. 7C are graphs for explaining an example of drive power control in the projector 500 according to the present embodiment. In FIG. 7A, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W1 supplied to the discharge lamp 90-1 to the rated power of the discharge lamp 90-1. In FIG. 7B, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W2 supplied to the discharge lamp 90-2 to the rated power of the discharge lamp 90-2. In FIG. 7C, the horizontal axis represents time, and the vertical axis represents the ratio of the total value WT of the drive power supplied to the discharge lamps 90-1 and 90-2 to the rated power of the discharge lamps 90-1 and 90-2. . In the present embodiment, the rated power of the discharge lamps 90-1 and 90-2 is the same. In the present embodiment, the time t0 to the time t6 are all equally spaced.

  The controller 580 releases the driving power W1 supplied to the discharge lamp 90-1 and the driving power W2 supplied to 90-2 to the discharge lamps 90-1 and 90-2 while being temporally changed. The lamp driving units 230-1 and 230-2 are controlled. In the example shown in FIGS. 7A and 7B, the driving power W1 and the driving power W2 are temporally within a range of 30% to 80% of the rated power of the discharge lamps 90-1 and 90-2. To change.

  The method of changing the driving power supplied to the discharge lamps 90-1 and 90-2 may be changed in a periodic pattern or may be changed randomly. In the example shown in FIGS. 7A and 7B, the driving power supplied to the discharge lamps 90-1 and 90-2 is changed in a periodic pattern. The period length when the drive powers W1 and W2 are changed in a periodic pattern may be, for example, about 10 seconds to 1 minute. Further, the interval at which the drive powers W1 and W2 take the maximum value or the interval at which the drive powers W1 and W2 take the minimum value may be, for example, about 10 seconds to 1 minute.

  In the example shown in FIG. 7A, the driving power W1 is rated for the discharge lamp 90-1 during the period from time t0 to time t1, the period from time t2 to time t3, and the period from time t4 to time t5. In the period from time t1 to time t2, the period from time t3 to time t4, and the period from time t5 to time t6, the driving power W1 is 30% of the rated power of the discharge lamp 90-1. The driving power W1 is changed in a periodic pattern so as to be constant at%.

  In the example shown in FIG. 7B, in the period from time t0 to time t1, the period from time t2 to time t3, and the period from time t4 to time t5, the driving power W2 is rated for the discharge lamp 90-2. In the period from time t1 to time t2, the period from time t3 to time t4, and the period from time t5 to time t6, the driving power W2 is 80% of the rated power of the discharge lamp 90-1. The driving power W2 is changed in a periodic pattern so as to be constant at%.

  The control unit 580 discharges the discharge lamp driving units 230-1 and 230- so that the total value WT of the driving power W1 supplied to the discharge lamp 90-1 and the driving power W2 supplied to 90-2 becomes a constant value. 2 is controlled. The constant value is a value corresponding to the brightness set based on, for example, an operation by the user. Accordingly, when the set brightness is different, different constant values are set. In the example shown in FIG. 7C, the total value WT is a constant value at 110% of the rated power of the discharge lamps 90-1 and 90-2.

  According to the present embodiment, the discharge lamp driving units 230-1 and 230-2 are controlled so as to be supplied to the discharge lamps 90-1 and 90-2 while temporally changing the driving power W1 and W2. The state where the electrode temperatures of the discharge lamps 90-1 and 90-2 are low is not continued for a long time. Therefore, a projector that can suppress the deterioration of the discharge lamp can be realized. In addition, since the range of change in the total value of drive power can be widened within a range where the discharge lamp does not deteriorate, a projector with a wide range of brightness selection can be realized.

  The illuminance of the discharge lamps 90-1 and 90-2 is generally proportional to the supplied drive power. According to the present embodiment, the discharge lamp driving units 230-1 and 230-2 are configured so that the total value WT of the driving powers W1 and W2 supplied to the respective discharge lamps 90-1 and 90-2 is a constant value. Since it is controlled, it is possible to realize a projector that can suppress changes in brightness. Further, since the change in brightness can be suppressed, the degree of freedom in the change cycle and change width of the drive power supplied to each discharge lamp is increased. As a result, a projector that can be driven more appropriately according to the characteristics of the discharge lamp can be realized.

  In the projector 500 according to the present embodiment, the maximum values of the driving power W1 and W2 supplied to the respective discharge lamps 90-1 and 90-2 are such that the respective discharge lamps 90-1 and 90-2 are lit for a long time. However, electric power that does not cause a blackening phenomenon may be used. The power that does not cause blackening even when the discharge lamps 90-1 and 90-2 are lit for a long time is usually about 70% or more of the rated power of the discharge lamps 90-1 and 90-2.

  In the projector 500 according to the present embodiment, the minimum values of the driving power W1 and W2 supplied to the respective discharge lamps 90-1 and 90-2 are maintained in the lighting state of the respective discharge lamps 90-1 and 90-2. Electric power that can be used. The power with which the discharge lamps 90-1 and 90-2 can maintain the lighting state is normally about 20% or more of the rated power of the discharge lamps 90-1 and 90-2.

  By setting the minimum value of the drive powers W1 and W2 to be the power that allows the discharge lamps 90-1 and 90-2 to maintain the lighting state, the discharge lamps 90-1 and 902 even if the supplied drive powers W1 and W2 change. -2 can maintain the lighting state. Therefore, when the projected image is brightened based on the user's operation or the like, it is not necessary to relight the discharge lamps 90-1 and 90-2, and the brightness can be changed in a short time.

6). Example of Driving Current Control in the Present Embodiment Next, a specific example of driving current control in the projector 500 according to the present embodiment will be described.

  FIG. 8 is a timing chart schematically showing an example of the relationship between the driving power W1 and the driving current I in the projector 500 according to the present embodiment. In the upper graph of FIG. 8, the horizontal axis represents time, and the vertical axis represents the driving power W1 of the discharge lamp 90-1. In the lower graph of FIG. 8, the horizontal axis represents time, and the vertical axis represents the drive current I of the discharge lamp 90-1. In the lower graph of FIG. 8, the driving current I when the first electrode 92-1 of the discharge lamp 90-1 is the anode (the second electrode 93-1 is the cathode) is a positive value, and the discharge lamp 90- The drive current I when one second electrode 93-1 is an anode (the first electrode 92-1 is a cathode) is represented as a negative value. In the following, the relationship between the driving power W1 and the driving current I in the discharge lamp 90-1 will be mainly described, but the same holds true for the discharge lamp 90-2.

  The upper graph in FIG. 8 is a graph corresponding to the period from time t0 to time t2 in the graph shown in FIG. The lower graph in FIG. 8 schematically shows the drive current I corresponding to the upper graph in FIG. 8, that is, the drive current I in the period from time t0 to time t2.

  When the drive voltage Vla of the discharge lamp 90-1 is constant, the drive power W1 of the discharge lamp 90-1 and the absolute value of the drive current I are in a proportional relationship. Therefore, the drive power W1 of the discharge lamp 90-1 can be changed by changing the drive current I of the discharge lamp 90-1.

  In the present embodiment, each of the discharge lamp driving units 230-1 and 230-2 supplies driving electric power W1 and W2 to the discharge lamp 90 by supplying an alternating current as the driving current I to the discharge lamps 90-1 and 90-2. -1 and 90-2. The advantages of supplying an alternating current as the drive current I to the discharge lamps 90-1 and 90-2 are as described in the section “4. Relationship between polarity of drive current and electrode temperature”.

  In the following description, one polarity reversal period is the latest polarity from which the drive current I changes from the first polarity to the second polarity from the polarity inversion timing at which the drive current I changes from the first polarity to the second polarity. From the period until the reversal timing, or from the polarity reversal timing at which the drive current I changes from the second polarity to the first electrode, to the most recent polarity reversal timing at which the drive current I changes from the second polarity to the first polarity It is a period. Also, the polarity reversal half cycle is from the polarity reversal timing at which the drive current I changes from the first polarity to the second polarity to the most recent polarity reversal timing at which the drive current I changes from the second polarity to the first polarity. This is the period, or the period from the polarity inversion timing at which the drive current I changes from the second polarity to the first electrode to the most recent polarity inversion timing at which the drive current I changes from the first polarity to the second polarity.

  In the example shown in FIG. 8, the absolute value of the drive current I is constant during the period of one cycle of polarity inversion of the drive current I. That is, the waveform of the drive current I is a so-called rectangular waveform. Note that the waveform of the drive current I is not limited to this, and the absolute value of the drive current I starts in a period in which the absolute value of the drive current I becomes the first current value during the half period of the polarity inversion of the drive current I. One period of polarity reversal of the drive current I, such as a waveform ending in a period when the second current value is larger than or a waveform in which the absolute value of the drive current I monotonously increases during the period of the polarity reversal half of the drive current I During this period, the waveform may be such that the absolute value of the drive current I is different.

  In the present embodiment, the control unit 580 changes each of the discharge lamps while changing the drive current I with time so as to change the average value of the drive powers W1 and W2 per one cycle of polarity inversion of each drive current I. The discharge lamp driving units 230-1 and 230-2 may be controlled so as to be supplied to 90-1 and 90-2. In this case, when the drive powers W1 and W2 are changed in a periodic pattern, one cycle of change of the drive powers W1 and W2 is longer than one cycle of polarity inversion of the drive current I. In the example shown in FIG. 8, the average value of the drive power W1 is changed every 10 cycles of polarity inversion of the drive current I.

  According to the projector 500 according to the present embodiment, the control unit 580 releases the drive current I while changing the drive current I so as to change the average value of the drive powers W1 and W2 per one cycle of polarity inversion of the drive current I. By controlling the discharge lamp driving units 230-1 and 230-2 so as to be supplied to the electric lamps 90-1 and 90-2, the electrode temperatures of the discharge lamps 90-1 and 90-2 can be more reliably increased. it can. As a result, the state in which the electrode temperatures of the discharge lamps 90-1 and 90-2 are low is not continued for a long time. Therefore, the occurrence of the blackening phenomenon of the discharge lamps 90-1 and 90-2 can be suppressed.

7). FIG. 9A, FIG. 9B, and FIG. 9C are graphs for explaining a first modification of the drive power control in the projector 500 according to the present embodiment. It is. In FIG. 9A, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W1 supplied to the discharge lamp 90-1 to the rated power of the discharge lamp 90-1. In FIG. 9B, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W2 supplied to the discharge lamp 90-2 to the rated power of the discharge lamp 90-2. In FIG. 9C, the horizontal axis represents time, and the vertical axis represents the ratio of the total value WT of the drive power supplied to the discharge lamps 90-1 and 90-2 to the rated power of the discharge lamps 90-1 and 90-2. . Below, it demonstrates centering around difference with the control demonstrated using FIG. 7 (A), FIG.7 (B), and FIG.7 (C).

  In the example shown in FIG. 9A, the driving power W1 supplied to the discharge lamp 90-1 is changed in a periodic pattern. In the example shown in FIG. 9A, the driving power W1 is discharged from the discharge lamp 90-1 in the period from time t0 to time t1, in the period from time t2 to time t3, and in the period from time t4 to time t5. Drive power W1 is released during the period from time t1 to time t2, the period from time t3 to time 4, and the period from time t5 to time t6. The drive power W1 is changed in a periodic pattern so as to linearly monotonously decrease from 80% to 30% of the rated power of the lamp 90-1.

  In the example shown in FIG. 9B, the driving power W2 supplied to the discharge lamp 90-2 is changed in a periodic pattern. In the example shown in FIG. 9B, the driving power W2 is supplied to the discharge lamp 90-2 in the period from time t0 to time t1, in the period from time t2 to time t3, and in the period from time t4 to time t5. Drive power W2 is released during the period from time t1 to time t2, the period from time t3 to time t4, and the period from time t5 to time t6. The drive power W2 is changed in a periodic pattern so as to linearly and monotonously decrease from 80% to 30% of the rated power of the lamp 90-2.

  By supplying driving power W1 and W2 to the discharge lamps 90-1 and 90-2 as shown in FIG. 9 (A) and FIG. 9 (B), as shown in FIG. 9 (C), the discharge lamp The total value WT of the drive powers W1 and W2 supplied to 90-1 and 90-2 becomes a constant value at 110% of the rated power of the discharge lamps 90-1 and 90-2.

  FIGS. 10A, 10 </ b> B, and 10 </ b> C are graphs for explaining a second modified example of the drive power control in the projector 500 according to the present embodiment. 10A, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W1 supplied to the discharge lamp 90-1 to the rated power of the discharge lamp 90-1. In FIG. 10B, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W2 supplied to the discharge lamp 90-2 to the rated power of the discharge lamp 90-2. In FIG. 10C, the horizontal axis represents time, and the vertical axis represents the ratio of the total value WT of the drive power supplied to the discharge lamps 90-1 and 90-2 to the rated power of the discharge lamps 90-1 and 90-2. . Below, it demonstrates centering around difference with the control demonstrated using FIG. 7 (A), FIG.7 (B), and FIG.7 (C).

  In the example shown in FIG. 10A, the driving power W1 of the discharge lamp 90-1 is changed in a periodic pattern. In the example shown in FIG. 10A, the period from time t0 to time t2, the period from time t2 to time t4, and the period from time t4 to time t6 are each one cycle, and the discharge lamp 90-1 The driving power W1 is changed in a periodic pattern so that a sinusoidal curve having a maximum value of 80% and a minimum value of 30% is obtained.

  In the example shown in FIG. 10B, the driving power W2 of the discharge lamp 90-2 is changed in a periodic pattern. In the example shown in FIG. 10B, the period from time t0 to time t2, the period from time t2 to time t4, and the period from time t4 to time t6 are each one cycle, and the discharge lamp 90-2 The drive power W2 is changed in a periodic pattern so that a sinusoidal curve having a maximum value of 80% and a minimum value of 30% is obtained.

  In the example shown in FIGS. 10A and 10B, the driving power W1 supplied to the discharge lamp 90-1 and the driving power W2 supplied to the discharge lamp 90-2 are mutually in phase. The driving powers W1 and W2 of the discharge lamps 90-1 and 90-2 are changed in a periodic pattern so as to form a sinusoidal curve shifted by 180 degrees. Therefore, as shown in FIG. 10C, the total value WT of the drive powers W1 and W2 supplied to the discharge lamps 90-1 and 90-2 is the rated power of the discharge lamps 90-1 and 90-2. It becomes a constant value at 110%.

  FIGS. 11A, 11 </ b> B, and 11 </ b> C are graphs for explaining a third modification of the drive power control in the projector 500 according to the present embodiment. In FIG. 11A, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W1 supplied to the discharge lamp 90-1 to the rated power of the discharge lamp 90-1. In FIG. 11B, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W2 supplied to the discharge lamp 90-2 to the rated power of the discharge lamp 90-2. In FIG. 11C, the horizontal axis represents time, and the vertical axis represents the ratio of the total value WT of the drive power supplied to the discharge lamps 90-1 and 90-2 to the rated power of the discharge lamps 90-1 and 90-2. . Below, it demonstrates centering around difference with the control demonstrated using FIG. 7 (A), FIG.7 (B), and FIG.7 (C).

  In the example shown in FIG. 11A, the driving power W1 supplied to the discharge lamp 90-1 is changed in a periodic pattern. In the example shown in FIG. 11A, the period from time t0 to time t4 is one period, and the drive power W1 is changed stepwise in 12 steps per period. Further, the drive power W1 is changed so that 80% of the rated power of the discharge lamp 90-1 is the maximum value and 30% is the minimum value. Further, the driving power W1 is changed so as to be the maximum value at time t1 and time t5 and the minimum value at time t3.

  In the example shown in FIG. 11B, the driving power W2 supplied to the discharge lamp 90-2 is changed in a periodic pattern. In the example shown in FIG. 11B, the period from time t0 to time t4 is one cycle, and the drive power W2 is changed stepwise in 12 steps per cycle. Further, the drive power W2 is changed so that 80% of the rated power of the discharge lamp 90-1 is the maximum value and 30% is the minimum value. Further, the driving power W2 is changed so as to be the minimum value at time t1 and time t5 and the maximum value at time t3.

  By supplying driving power W1 and W2 to the discharge lamps 90-1 and 90-2 as shown in FIG. 11 (A) and FIG. 11 (B), as shown in FIG. 11 (C), the discharge lamp The total value WT of the drive powers W1 and W2 supplied to 90-1 and 90-2 becomes a constant value at 110% of the rated power of the discharge lamps 90-1 and 90-2.

  FIGS. 12A, 12 </ b> B, and 12 </ b> C are graphs for explaining a fourth modification of control of drive power in the projector 500 according to the present embodiment. In FIG. 12A, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W1 supplied to the discharge lamp 90-1 to the rated power of the discharge lamp 90-1. In FIG. 12B, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W2 supplied to the discharge lamp 90-2 to the rated power of the discharge lamp 90-2. In FIG. 12C, the horizontal axis represents time, and the vertical axis represents the ratio of the total value WT of the drive power supplied to the discharge lamps 90-1 and 90-2 to the rated power of the discharge lamps 90-1 and 90-2. . Below, it demonstrates centering around difference with the control demonstrated using FIG. 7 (A), FIG.7 (B), and FIG.7 (C).

  In the example shown in FIG. 12A, the driving power W1 supplied to the discharge lamp 90-1 is changed in a periodic pattern. In the example shown in FIG. 12A, the period from time t0 to time t1, the period from time t1 to time t2, the period from time t2 to time t3, the period from time t3 to time 4, and the time In the period from t4 to time t5 and in the period from time t5 to time t6, the driving power W1 increases linearly and monotonically from 30% to 80% of the rated power of the discharge lamp 90-1, respectively. The driving power W1 is changed in a periodic pattern so as to instantaneously decrease from 80% to 30% of the rated power of the discharge lamp 90-1.

  In the example shown in FIG. 12B, the driving power W2 supplied to the discharge lamp 90-2 is changed in a periodic pattern. In the example shown in FIG. 12B, the period from time t0 to time t1, the period from time t1 to time t2, the period from time t2 to time t3, the period from time t3 to time 4, and the time In the period from t4 to time t5 and in the period from time t5 to time t6, the driving power W1 decreases linearly from 80% to 30% of the rated power of the discharge lamp 90-2, respectively, and then at the end of the period. The driving power W2 is changed in a periodic pattern so as to increase instantaneously from 30% to 80% of the rated power of the discharge lamp 90-2.

  By supplying drive power W1 and W2 to the discharge lamps 90-1 and 90-2 as shown in FIG. 12 (A) and FIG. 12 (B), as shown in FIG. 12 (C), the discharge lamp The total value WT of the drive powers W1 and W2 supplied to 90-1 and 90-2 becomes a constant value at 110% of the rated power of the discharge lamps 90-1 and 90-2.

  FIG. 13A, FIG. 13B, and FIG. 13C are graphs for explaining a fifth modification of control of drive power in the projector 500 according to the present embodiment. In FIG. 13A, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W1 supplied to the discharge lamp 90-1 to the rated power of the discharge lamp 90-1. In FIG. 13B, the horizontal axis represents time, and the vertical axis represents the ratio of the driving power W2 supplied to the discharge lamp 90-2 to the rated power of the discharge lamp 90-2. In FIG. 13C, the horizontal axis represents time, and the vertical axis represents the ratio of the total value WT of the drive power supplied to the discharge lamps 90-1 and 90-2 to the rated power of the discharge lamps 90-1 and 90-2. . 13A, 13B, and 13C, time t11 is an intermediate time between time t0 and time t1, and time t13 is an intermediate time between time t2 and time t3, time t15. Is an intermediate time between time t4 and time t5. Below, it demonstrates centering around difference with the control demonstrated using FIG. 7 (A), FIG.7 (B), and FIG.7 (C).

  In the example shown in FIG. 13A, the driving power W1 supplied to the discharge lamp 90-1 is changed in a periodic pattern. In the example shown in FIG. 13A, the driving power W1 is the discharge lamp 90-1 in the period from time t0 to time t11, in the period from time t2 to time t13, and in the period from time t4 to time t15. In the period from time t11 to time t2, the period from time t13 to time t4, and the period from time t15 to time t6, the driving power W1 is the rated power of the discharge lamp 90-1. The driving power W1 is changed in a periodic pattern so as to be constant at 30% of the above. That is, in the example shown in FIG. 13A, the ratio of the time when the drive power W1 is the maximum value is smaller than the ratio of the time when the drive power W1 is the minimum value.

  In the example shown in FIG. 13B, the driving power W2 supplied to the discharge lamp 90-2 is changed in a periodic pattern. In the example shown in FIG. 13B, the driving power W2 is supplied to the discharge lamp 90-2 in the period from time t0 to time t11, in the period from time t2 to time t13, and in the period from time t4 to time t15. In the period from time t11 to time t2, the period from time t13 to time t4, and the period from time t15 to time t6, the driving power W2 is the rated power of the discharge lamp 90-1. The driving power W2 is changed in a periodic pattern so as to be constant at 80%. That is, in the example shown in FIG. 13B, the ratio of the time when the drive power W2 is the maximum value is larger than the ratio of the time when the drive power W2 is the minimum value.

  By supplying drive power W1 and W2 to the discharge lamps 90-1 and 90-2 as shown in FIG. 13 (A) and FIG. 13 (B), as shown in FIG. 13 (C), the discharge lamp The total value WT of the drive powers W1 and W2 supplied to 90-1 and 90-2 becomes a constant value at 110% of the rated power of the discharge lamps 90-1 and 90-2.

  In the example shown in FIGS. 13A and 13B, the average value of the driving power W1 supplied to the discharge lamp 90-1 and the average of the driving power W2 supplied to the discharge lamp 90-2. The value is different. Accordingly, discharge lamps having different specifications can be used for the discharge lamp 90-1 and the discharge lamp 90-2. That is, the choice of the discharge lamp used for the projector 500 increases.

  Also in the first modification, the second modification, the third modification, the fourth modification, and the fifth modification, the discharge lamp 90-1 and the driving lamps W-1 and W2 are changed with time. Since the discharge lamp driving units 230-1 and 230-2 are controlled so as to be supplied to 90-2, the state where the electrode temperatures of the discharge lamps 90-1 and 90-2 are low does not continue for a long time. Therefore, a projector that can suppress the deterioration of the discharge lamp can be realized. In addition, since the range of change in the total value of drive power can be widened within a range where the discharge lamp does not deteriorate, a projector with a wide range of brightness selection can be realized.

  Further, since the discharge lamp driving units 230-1 and 230-2 are controlled so that the total value WT of the driving power W1 and W2 supplied to the respective discharge lamps 90-1 and 90-2 becomes a constant value, A projector capable of suppressing changes in brightness can be realized. Further, since the change in brightness can be suppressed, the degree of freedom in the change cycle and change width of the drive power supplied to each discharge lamp is increased. As a result, a projector that can be driven more appropriately according to the characteristics of the discharge lamp can be realized.

  In each of the embodiments described above, the projector having two light source units including the discharge lamp has been described as an example. However, the present invention is not limited to this, and the projector has three or more light source units including the discharge lamp. It is also applicable to.

  In each of the above embodiments, a projector using three liquid crystal panels has been described as an example. However, the present invention is not limited to this, and one, two, four or more liquid crystal panels are used. It can also be applied to projectors.

  In each of the above embodiments, a transmissive projector has been described as an example. However, the present invention is not limited to this, and can be applied to a reflective projector. Here, “transmission type” means that an electro-optic modulation device as a light modulation means such as a transmission type liquid crystal panel transmits light, and “reflection type” means This means that an electro-optic modulator as a light modulator such as a reflective liquid crystal panel or a micromirror type light modulator is a type that reflects light. As the micromirror light modulator, for example, DMD (digital micromirror device; trademark of Texas Instruments) can be used. Even when the present invention is applied to a reflective projector, the same effect as that of a transmissive projector can be obtained.

  The present invention can be applied to a front projection type projector that projects from the side that observes the projected image, or to a rear projection type projector that projects from the side opposite to the side that observes the projected image. is there.

  In addition, this invention is not limited to the above-mentioned embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

10-1, 10-2 Discharge lamp lighting device, 20 power control circuit, 21 switch element, 22 diode, 23 coil, 24 capacitor, 30 polarity inversion circuit, 31 first switch element, 32 second switch element, 33 3rd switch element, 34 4th switch element, 40 control part, 40-1 power control means, 40-2 polarity inversion control means, 41 system controller, 42 power control circuit controller, 43 polarity inversion circuit controller, 44 memory Unit, 50-1 sub-reflecting mirror, 60 operation detection unit, 61 first resistor, 62 second resistor, 63 third resistor, 70 igniter circuit, 80 DC power supply, 90-1, 90-2 discharge lamp , 90e1 first end, 90e2 second end, 91-1 discharge space, 92-1 first electrode, 93-1 first Electrode, 112-1 Main reflector, 114 Fixing member, 200-1, 200-2 Light source unit, 210-1 Light source unit, 230-1, 230-2 Discharge lamp driving unit, 305 Parallelizing lens, 310 Illumination optical system , 320 color separation optical system, 330R, 330G, 330B liquid crystal light valve, 340 cross dichroic prism, 350 projection optical system, 500 projector, 502 video signal, 510 video signal converter, 512R, 512G, 512B video signal, 514 communication signal 522 fixing member, 534 conductive member, 536 first terminal, 544 conductive member, 546 second terminal, 552p protrusion, 560R, 560G, 560B liquid crystal panel, 562p protrusion, 570 video processing device, 572R, 572G, 572B drive Signal, 580 Control unit, 5 80-1 1st mode control means, 580-2 2nd mode control means, 582, 584, 586, 588 communication signal, 590 operation accepting unit, 592 operation, 594 communication signal, 600 AC power supply, 700 screen

Claims (7)

A plurality of light source units;
And a control unit for controlling the plurality of light source sections,
Each of the plurality of light source units includes a discharge lamp, and a discharge lamp driving unit that supplies driving power to the discharge lamp to drive the discharge lamp,
The controller is
A total value of the driving power supplied to each of the discharge lamps is a constant value, and
Each of the discharge lamps is supplied to each of the discharge lamps in a periodic pattern in which the drive power periodically increases or decreases while the drive power supplied to each of the discharge lamps is temporally changed. A projector that controls the drive unit.   The projector according to claim 1.
  The periodic pattern includes a pattern in which the driving power is 70% or more of each rated power of the plurality of light source units.   The projector according to claim 1 or 2,
  The plurality of light source units include a first light source unit and a second light source unit,
  The control unit supplies driving power based on a first periodic pattern to the first light source unit, and supplies driving power based on a second periodic pattern to the second light source unit,
  The projector in which the first periodic pattern and the second periodic pattern are patterns having different average values of the driving power.   The projector according to claim 1 or 2,
  The plurality of light source units include a first light source unit and a second light source unit,
  The control unit supplies driving power based on a first periodic pattern to the first light source unit, and supplies driving power based on a second periodic pattern to the second light source unit,
  The first periodic pattern includes a pattern that monotonously increases and then decreases instantaneously;
  The projector, wherein the second periodic pattern includes a pattern that increases monotonously and then increases instantaneously.   The projector according to any one of claims 1 to 4, wherein:
  The said control part is a projector which controls the said discharge lamp drive part so that the total value of the said drive power may become more than each rated power of these light source parts. The projector according to any one of claims 1 to 5 ,
Each of the discharge lamp driving units supplies the driving power to the discharge lamp by supplying an alternating current to the discharge lamp as a driving current,
The control unit drives the discharge lamp so as to supply the drive current to each discharge lamp so as to temporally change the average value of the drive power per one cycle of polarity inversion of the drive current. Projector that controls the unit. The projector according to any one of claims 1 to 6 ,
The minimum value of the driving power supplied to each of the discharge lamps is a projector that can maintain the lighting state of each of the discharge lamps.

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