JP2014160585A - Discharge lamp drive unit, projector and discharge lamp drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp drive unit, projector and discharge lamp drive method, capable of optimizing lighting operations of a discharge lamp with simple control.SOLUTION: The discharge lamp drive unit includes: drive circuits 20 and 30 that supplies electric power to a discharge lamp 90 for lighting-on, and a control section 40 that controls electric power supplied to the discharge lamp 90 by the drive circuits 20 and 30. The control section 40, after starting power supply to the discharge lamp under a lighting-off state, changes an electric current running through the discharge lamp 90 according to a change in a voltage between electrodes of the discharge lamp 90.

Description

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

  Generally, a discharge lamp such as an ultra high pressure mercury lamp is used as a light source of a projector. It is known that the shape of the tip portion of an electrode is deformed due to deterioration or wear of the electrode during lighting. Depending on the shape of the electrode, the temperature at the tip tends to rise, the electrode is overloaded, and problems such as disappearance of electrode protrusions may occur. When the electrode protrusion disappears, the illuminance of the discharge lamp is insufficient due to the increase in the distance between the electrodes. For this reason, conventionally, in the initial lighting section after the start of the discharge lamp lighting, a low power lighting section that maintains the lighting of the discharge lamp with a constant power lower than the rated power is provided, and a method of suppressing an excessive temperature rise at the tip of the electrode Has been proposed (see, for example, Patent Document 1).

JP 2012-109267 A

In order to control the driving power of the discharge lamp to be constant as in the conventional method described above, it is desirable to monitor and control both the current flowing through the discharge lamp and the voltage between the electrodes, but the control becomes complicated. There was a problem that.
The present invention provides a discharge lamp driving device, a projector, and a discharge lamp driving method capable of solving the problems of the conventional techniques described above and optimizing the lighting operation of the discharge lamp by simple control. With the goal.

In order to achieve the above object, the present invention provides, in a discharge lamp driving apparatus, a driving circuit that supplies electric power to a discharge lamp to light it, and a control unit that controls electric power supplied to the discharge lamp by the driving circuit. And the control means changes the current flowing through the discharge lamp in accordance with the change in the voltage between the electrodes of the discharge lamp after the supply of power to the discharge lamp in the extinguished state is started.
According to this configuration, the lighting operation of the discharge lamp can be optimized by simple control of changing the current flowing through the discharge lamp in accordance with the change in the voltage between the electrodes of the discharge lamp.

In the discharge lamp driving device according to the present invention, the control unit may start the power supply to the discharge lamp in the extinguished state, and then perform the power supply before the steady driving for turning on the power supplied to the discharge lamp at a constant power. In the start-up drive section, a current flowing through the discharge lamp is changed in accordance with a change in the voltage between the electrodes of the discharge lamp.
According to this configuration, it is possible to optimize the lighting operation of the discharge lamp in the start-up drive section with simple control, and when starting the steady drive, the temperature of the electrode greatly exceeds a predetermined temperature. It can be controlled so that it is not.

In the discharge lamp driving device according to the present invention, the control means may use a comparison result obtained by comparing a change in the voltage between the electrodes of the discharge lamp per unit time with at least one threshold value after starting the start-up driving. Based on this, the current flowing through the discharge lamp is changed.
According to this configuration, the current flowing in the discharge lamp can be changed according to the change in voltage per unit time, that is, the state of the electrode, and the lighting operation of the discharge lamp can be optimized with simple control. it can.

According to the present invention, in the discharge lamp driving device, the control means determines a current flowing through the discharge lamp based on a comparison result between a change in the interelectrode voltage of the discharge lamp per unit time and the at least one threshold value. It is characterized by lowering.
According to this configuration, when the temperature of the electrode is likely to rise, the startup drive section can be controlled so that the temperature of the electrode does not greatly exceed a predetermined temperature. The lighting operation of the discharge lamp can be optimized.

According to the present invention, in the discharge lamp driving device, the control means determines a current flowing through the discharge lamp based on a comparison result between a change in the interelectrode voltage of the discharge lamp per unit time and the at least one threshold value. It is characterized by increasing.
According to this configuration, when it takes time for the electrode to warm up to the predetermined temperature, the temperature of the electrode is controlled to be warmed to the predetermined temperature during the startup drive section. Thereby, it is possible to perform control for increasing the brightness of the discharge lamp earlier, and it is possible to optimize the lighting operation of the discharge lamp in the startup drive section.

Further, the present invention is characterized in that, in the discharge lamp driving device, when the cumulative lighting time of the discharge lamp is longer than a predetermined time, the current flowing through the discharge lamp is not increased beyond a specified current, or the increase width is reduced. And
According to this configuration, it is possible to suppress rapid deterioration and wear of the electrode of the discharge lamp, and to extend the life of the discharge lamp.

Further, the present invention provides the discharge lamp driving device further comprising storage means for storing the voltage between the electrodes of the discharge lamp at the time of steady driving in which the electric power supplied from the driving circuit to the discharge lamp is made constant. The control means limits the current flowing through the discharge lamp or the amount of change in the current based on the voltage between the electrodes during the last steady drive stored in the storage means.
According to this configuration, it is possible to suppress rapid deterioration and wear of the electrode of the discharge lamp, and to extend the life of the discharge lamp.

In order to achieve the above object, the present invention is a projector including a discharge lamp as a light source, and a driving circuit that supplies power to the discharge lamp to light it, and is supplied to the discharge lamp by the driving circuit. Control means for controlling electric power, and the control means changes the current flowing through the discharge lamp in accordance with a change in the voltage between the electrodes of the discharge lamp after starting the supply of power to the discharge lamp in the extinguished state. It is characterized by making it.
According to this configuration, the lighting operation of the discharge lamp can be optimized by simple control of changing the current flowing through the discharge lamp in accordance with the change in the voltage between the electrodes of the discharge lamp.

In order to achieve the above object, according to the present invention, in the discharge lamp driving method, the power supplied to the discharge lamp is controlled by a driving circuit that supplies power to the discharge lamp to light it, and the discharge lamp is turned off. After the power supply is started, the current flowing through the discharge lamp is changed in accordance with the change in the voltage between the electrodes of the discharge lamp.
According to this configuration, the lighting operation of the discharge lamp can be optimized by simple control of changing the current flowing through the discharge lamp in accordance with the change in the voltage between the electrodes of the discharge lamp.

  According to the present invention, the lighting operation of the discharge lamp can be optimized by simple control of changing the current flowing through the discharge lamp in accordance with the change in the interelectrode voltage of the discharge lamp.

FIG. 2 is a functional block diagram illustrating a configuration of a projector according to an embodiment of the invention. It is a circuit diagram of a discharge lamp drive device. It is a sequence diagram which shows the lighting sequence of a discharge lamp. It is a chart which shows the state of the drive power in the lighting sequence of a discharge lamp, a drive voltage, and drive current, (A) shows drive power, (B) shows drive voltage, and (C) shows the waveform of drive current. It is a flowchart which shows operation | movement of a discharge lamp drive device. It is a flowchart which shows the modification of operation | movement of a discharge lamp drive device.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
FIG. 1 is a block diagram illustrating a functional configuration of a projector 100 according to the embodiment.
The projector 100 is connected to an image supply unit (not shown) such as a PC (Personal Computer) by an image signal cable or by wireless communication using a wireless LAN or the like. The projector 100 projects a display image on a screen SC as a projection surface (display surface) based on the image data 104 input from the image supply unit.
The projector 100 includes an image processing unit 102, a projection unit 103, and a projector control unit 101 that controls these units.
The projector 100 includes a discharge lamp 90 as a light source composed of an ultrahigh pressure mercury lamp, and a discharge lamp driving device 10 that controls driving of the discharge lamp 90.

The image processing unit 102 executes display image processing based on the image data 104. Although not shown, the image processing unit 102 develops an image in a frame memory according to the control of the image input unit to which the image data 104 is input, the display control unit that processes the input image data 104, and the display control unit. An image processing unit that generates an image to be projected is provided.
The projection unit 103 projects the image processed by the image processing unit 102 onto the screen SC according to the control of the image processing unit 102. Although not shown, the projection unit 103 includes an illumination optical system, a light modulation device, a projection unit including the projection optical system, a light modulation device driving unit that drives the light modulation device, and a projection that drives the projection optical system. And an optical system driving unit. The light emitted from the discharge lamp 90 is guided to the light modulation device by the illumination optical system. The light modulation device includes, for example, three liquid crystal panels corresponding to the three primary colors of RGB. Light from the illumination optical system is separated into three color lights of RGB, and each color light enters each corresponding liquid crystal panel. The color light modulated by passing through each liquid crystal panel is combined by a combining optical system such as a cross dichroic prism and emitted to a projection optical system. The projection optical system includes a zoom lens that enlarges / reduces a projected image and adjusts the focus, a zoom adjustment motor that adjusts the degree of zoom, a focus adjustment motor that adjusts focus, and the like.

The projection optical system drive unit drives each motor included in the projection optical system according to the control of the image processing unit 102. The light modulation device driving unit performs drawing by driving the light modulation device based on the image signal output from the image processing unit 102.
The projector control unit 101 includes a CPU (not shown), a non-volatile memory, a RAM, and the like. The projector control unit 101 reads out and executes a control program stored in a storage unit (not shown) connected to the projector control unit 101, and each unit of the projector 100. To control.

FIG. 2 is an example of a circuit diagram of the discharge lamp driving device 10 according to the embodiment to which the present invention is applied.
The discharge lamp driving device 10 includes a power control circuit (discharge lamp lighting circuit) 20, an AC conversion circuit (discharge lamp lighting circuit) 30, a control unit (control means) 40, an operation detection unit 60, and a high voltage generation circuit 70. Then, the discharge lamp 90 is driven. Among these, the power control circuit 20 and the AC conversion circuit 30 can be collectively referred to as a discharge lamp lighting circuit (drive circuit).
The discharge lamp 90 includes two electrodes (cathode / anode) inside a discharge lamp formed of a translucent material such as quartz glass, and a gas as a discharge medium is sealed therein. The discharge lamp driving device 10 supplies an alternating current between the electrodes of the discharge lamp 90 to cause arc discharge between the two electrodes.

The power control circuit 20 generates driving power to be supplied to the discharge lamp 90. In the present embodiment, the power control circuit 20 is composed of a down chopper circuit that receives a DC power supply 80 and steps down the input voltage to output a DC current Id. The DC power source 80 is a rectifier circuit connected to a commercial AC power source, for example.
The power control circuit 20 can be configured to 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 current control signal is input from the control unit 40 to the control terminal of the switch element 21, and ON / OFF of the switch element 21 is controlled by the control unit 40. For example, a PWM (Pulse Width Modulation) control signal may be used as the current control signal.

  When the switch element 21 is switched ON by the control of the control unit 40, a current flows through the coil 23 and energy is stored in the coil 23. Thereafter, when the switch element 21 is switched to OFF, the energy stored in the coil 23 is released through a path that passes through the capacitor 24 and the diode 22. As a result, a direct current Id corresponding to the ON time of the switch element 21 is generated.

  The AC conversion circuit 30 receives the DC current Id output from the power control circuit 20, and generates and outputs a driving current for driving a discharge lamp having an arbitrary frequency by inverting the polarity at a given timing. . In the present embodiment, the AC conversion circuit 30 is configured by an inverter bridge circuit (full bridge circuit).

  The AC conversion 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. The first switch element 31 and the second switch element 32 are directly connected, the third switch element 33 and the fourth switch element 34 are connected in series, and these switch groups are connected in parallel to each other. A frequency control signal is input from the control unit 40 to the control terminals of the first switch element 31 to the fourth switch element 34. Thereby, ON / OFF of the 1st switch element 31-the 4th switch element 34 is controllable for every switch element by the control part 40. FIG.

  Under the control of the control unit 40, the AC conversion circuit 30 operates to alternately turn 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. repeat. As a result, the polarity of the direct current Id output from the power control circuit 20 is alternately inverted by the AC conversion circuit 30, and the common connection point of the first switch element 31 and the second switch element 32 and the third switch element An AC drive current I having a controlled frequency is output from a common connection point of 33 and the fourth switch element 34.

  That is, under the control of the control unit 40, 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 is turned OFF. When the fourth switch element 34 is OFF, the second switch element 32 and the third switch element 33 are turned ON. When the first switch element 31 and the fourth switch element 34 are ON, an AC drive current I that flows from 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. . When the second switch element 32 and the third switch element 33 are ON, the AC drive current I that 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 is Occur.

  In a discharge lamp, in general, the temperature of the anode tends to be higher than that of the cathode. If the temperature of one electrode continues to be higher than that of the other electrode, for example, the tip of the electrode on the high temperature side may be excessively melted and unintended electrode deformation may occur. As a result, the arc length may deviate from an appropriate value. Further, in the electrode on the low temperature side, the melting of the tip becomes insufficient, and minute irregularities generated at the tip may remain undissolved. As a result, a so-called arc jump may occur in which the arc position moves without being stabilized. In order to suppress such problems, the projector 100 according to the present embodiment performs AC driving in which the polarity of each electrode is repeatedly changed by the AC conversion circuit 30.

The control unit 40 controls the current value and the frequency of the AC drive current I by controlling the power control circuit 20 and the AC conversion circuit 30. The control unit 40 performs AC conversion control for controlling the frequency of the AC conversion circuit 30 by adjusting the polarity inversion timing of the AC drive current I. Further, the control unit 40 performs current control on the power control circuit 20 to control the current value of the direct current Id output from the power control circuit 20.
Although the configuration of the control unit 40 is not particularly limited, in the present embodiment, the control unit 40 includes a system controller 41, a power control circuit controller 42, and an AC conversion circuit controller 43. Note that a part or all of the control unit 40 may be configured by a semiconductor integrated circuit.

The system controller 41 controls the power control circuit 20 and the AC conversion circuit 30 by controlling the power control circuit controller 42 and the AC conversion circuit controller 43. The system controller 41 controls the power control circuit controller 42 and the AC conversion circuit controller 43 based on the discharge lamp driving voltage and the AC driving current I detected by an operation detection unit 60 provided in the discharge lamp driving device 10 described later. Also good.
The system controller 41 includes a storage unit 44. The storage unit 44 may be provided independently of the system controller 41. Although details will be described later, the storage unit 44 stores information (threshold value for the voltage increase Δv per unit time Δt) for controlling the current value flowing into the discharge lamp 90 during the startup drive section of the discharge lamp 90. Has been. The storage unit 44 may store, for example, information related to at least one of the current value, frequency, duty ratio, and waveform of the AC drive current I and information related to the specification of the discharge lamp 90.

The power control circuit controller 42 controls the power control circuit 20 by outputting a current control signal to the power control circuit 20 based on the control signal from the system controller 41.
The AC conversion circuit controller 43 controls the AC conversion circuit 30 by outputting an AC conversion control signal to the AC conversion circuit 30 based on the control signal from the system controller 41.

The operation detector 60 includes, for example, a voltage detector that detects the discharge lamp drive voltage Vd of the discharge lamp 90 and outputs drive voltage information, and a current detector that detects the AC drive current I and outputs drive current information. But you can. In the present embodiment, the operation detection unit 60 includes a first resistor 61, a second resistor 62, and a third resistor 63.
The voltage detection unit detects the discharge lamp driving voltage (voltage between the electrodes of the discharge lamp 90) 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. . The current detection unit detects the AC drive current I based on the voltage generated in the third resistor 63 connected in series with the discharge lamp 90.

  The high voltage generation circuit 70 operates only when the discharge lamp 90 starts to light up. When the discharge lamp 90 starts to light, a high voltage (normal control operation) required for dielectric breakdown between the electrodes of the discharge lamp 90 to form a discharge path. A voltage higher than the time) is supplied between the electrodes of the discharge lamp 90. In the present embodiment, the high pressure generation circuit 70 is connected in parallel with the discharge lamp 90.

FIG. 3 is a sequence diagram showing a lighting sequence of the discharge lamp 90, and FIG. 4 is a graph schematically showing waveforms of drive power, drive voltage, and drive current.
As shown in FIG. 3 and FIG. 4, the discharge lamp 90 in the extinguished state passes through the dielectric breakdown section, the start section, and the startup drive section, transitions to the steady drive section, and enters a state where light is steadily emitted.
In the dielectric breakdown section, a high voltage is supplied between the electrodes of the discharge lamp 90 by the high voltage generation circuit 70, and the dielectric breakdown between the electrodes is performed to form a discharge path.
When the discharge path is formed, it becomes a glow discharge section in which glow discharge occurs between the electrodes. When the two electrodes of the discharge lamp 90 reach the temperature of thermionic emission due to glow discharge, an arc discharge section in which arc discharge occurs between the electrodes is formed. In the arc discharge section, the effective value of the drive voltage is smaller than that in the glow discharge section, and the effective value of the AC drive current is increased. The glow discharge section and the arc discharge section are collectively referred to as a start section.
After that, it becomes a start-up section in which the supplied power is raised to a predetermined driving power, and after reaching the predetermined driving power, it becomes a steady operation section in which constant power driving is performed.
The control unit 40 controls the current and voltage supplied to the discharge lamp 90, thereby realizing each of the dielectric breakdown section, the start section, the start-up drive section, and the steady drive section, and turns on the discharge lamp 90. .

Next, a specific example of control of the discharge lamp driving device 10 will be described.
FIG. 4 is a chart showing the states of drive power, drive voltage, and drive current in the lighting sequence of the discharge lamp 90 when the discharge lamp 90 is driven by the discharge lamp driving device 10. Specifically, it is a graph schematically showing waveforms of drive power (FIG. 4A), drive voltage (FIG. 4B), and drive current (FIG. 4C), with the horizontal axis representing time. Represent.
As shown in FIG. 4B, the control unit 40 detects a voltage change Δv of the driving voltage of the discharge lamp 90 per predetermined unit time Δt in the start-up driving section after the discharge lamp 90 is turned on. (Refer to the enlarged view of part B). A section in which the voltage change Δv per unit time Δt is detected is called a voltage change detection section, and is provided at the beginning of the startup drive section. Control unit 40, pouring a predetermined set current I _s to the discharge lamp 90, the detection based on the drive voltage of the discharge lamp 90 to be input voltage variation Δv per unit time Δt by the setting current I _s from the operation detecting unit 60 To do.

In the voltage change detection section, when the voltage change Δv per unit time Δt is large, it is conceivable that the electrode is rapidly warmed. The storage unit 44 stores a threshold value of the voltage change Δv per unit time Δt set in advance by an experiment or the like. When the threshold is greater than the voltage change Δv per unit time Δt is stored in the storage unit 44, the control unit 40, sets the current value flow into the discharge lamp 90 in the launch driving section a low-current pattern I _L To do. Thereby, the control unit 40 performs drive control of the discharge lamp so that the electrode temperature does not greatly exceed a predetermined temperature in the startup drive section.

On the other hand, if the voltage change Δv per unit time Δt is small in the voltage change detection section, it may take time to warm the electrode to a predetermined temperature. The discharge lamp continues to increase in brightness until the electrode is warmed to a predetermined temperature. Therefore, when the voltage change Δv per unit time Δt is equal to or less than the threshold value stored in the storage unit 44 described above, the control unit 40 sets the current value flowing into the discharge lamp 90 during the start-up drive section to the high current pattern I _H. Set to. As a result, the control unit 40 performs control to warm the temperature of the electrode to a predetermined temperature during the start-up drive section and to quickly increase the brightness of the discharge lamp 90.

Next, operation | movement of the discharge lamp drive device 10 is demonstrated using the flowchart of FIG. When a drive switch (not shown) of the discharge lamp driving device 10 is turned on (for example, when the projector is activated), the control unit 40 controls the high-voltage generation circuit 70 to cause dielectric breakdown between the electrodes of the discharge lamp 90 ( Step S1). Next, the control unit 40 controls the voltage and current flowing into the discharge lamp 90 in the starting drive section (step S2). The starting drive is performed for a predetermined time set in advance, and when the predetermined time has elapsed, the start-up drive is started (step S3). Control unit 40, at the beginning of the voltage change detecting section of the rising drive section, pouring over the set current I _s to the discharge lamp 90 in a unit time Delta] t, to detect a voltage change Δv per unit time Delta] t (Step S4) .

The control unit 40 compares the detected voltage change Δv per unit time Δt with a threshold value stored in advance in the storage unit 44 and determines whether the voltage change Δv per unit time Δt exceeds the threshold value ( Step S5). If the voltage change Δv per unit time Δt exceeds the threshold value (threshold value greater than) (Step S5: Yes), the control unit 40, a low current pattern I _L obtained by setting the current to be lower on the basis of the comparison result Then, the startup drive is performed (step S6). On the other hand, when the voltage change Δv per unit time Δt does not exceed the threshold value (below the threshold value) (step S5: No), the control unit 40 sets the high current pattern I set to a higher current based on the comparison result. Start-up driving is performed according to _H (step S7). When the start-up drive is performed according to the low current pattern I _L or the high current pattern I _{H and} the power of the discharge lamp 90 reaches a predetermined drive power, the control unit 40 starts a steady drive (step S8). In the present embodiment, the current value of the low current pattern I _L is set to the following values set current I _s, for example, they are set substantially equal to or slightly higher as the current value in the steady driving period. The current value of the high current pattern I _H is set to a value larger than a predetermined current I _s, is set to a value higher than the current value in the steady driving period.

In the present embodiment, a current value flowed to the discharge lamp 90, if the change Δv in the inter-electrode voltage exceeds the threshold value of the predetermined value is set to a low current pattern I _L, the change in the inter-electrode voltage Δv When the value is equal to or less than the predetermined threshold value, the high current pattern I _H is set. This embodiment does not limit the present invention. For example, the change Δv in the voltage between the electrodes of the discharge lamp 90 is compared with a plurality of thresholds, and a plurality of current values are supplied to the discharge lamp 90 based on the voltage change Δv. It may be configured to be set to any one of the current patterns. Although not shown, for example, there are two upper and lower threshold values, and the current value flowing into the discharge lamp 90 is set to one of three patterns based on the comparison result between the voltage change Δv and these threshold values. Good. When the voltage change Δv exceeds the upper limit threshold, the current value flowing into the discharge lamp 90 is set to a current increasing pattern, and when the voltage change Δv is lower than the upper limit threshold and higher than the lower limit threshold, the discharge lamp 90 is set. The current value flowing into the discharge lamp 90 is set in the current standard pattern, and when the voltage change Δv falls below the lower limit threshold, the current value flowing into the discharge lamp 90 may be set in the current lowering pattern. In this case, the current value in each of the current increasing pattern, current standard pattern, and current lowering pattern can optimize the lighting operation of the discharge lamp based on the voltage change Δv between the electrodes in the voltage change detection section. The predetermined value is set in advance.

  As described above, according to the embodiment to which the present invention is applied, the driving circuits 20 and 30 that supply the electric power to the discharge lamp 90 to light and the electric power supplied to the discharge lamp 90 by the driving circuits 20 and 30 are supplied. A controller 40 that controls the discharge lamp 90, and after starting to supply power to the discharge lamp 90 in the extinguished state, the controller 40 changes the current flowing through the discharge lamp 90 in accordance with the change in the interelectrode voltage of the discharge lamp 90. . According to this configuration, the lighting operation of the discharge lamp can be optimized by simple control of changing the current flowing through the discharge lamp 90 in accordance with the change in the interelectrode voltage of the discharge lamp 90. Thereby, it is possible to prevent the discharge lamp 90 from becoming insufficient in illuminance due to a problem such as loss of electrode protrusions. In addition, rapid deterioration and consumption of the electrodes of the discharge lamp 90 can be suppressed, and the life of the discharge lamp 90 can be extended.

  In addition, according to the embodiment to which the present invention is applied, the control unit 40 starts supplying power to the discharge lamp 90 in the extinguished state, and then before steady driving for turning on the power supplied to the discharge lamp 90 with constant power. In the start-up drive section, the current flowing through the discharge lamp 90 is changed in accordance with the change in the interelectrode voltage of the discharge lamp 90. According to this configuration, the lighting operation of the discharge lamp can be optimized in the startup drive section with simple control. Therefore, when the steady driving is started, the temperature of the electrode does not rise greatly exceeding the predetermined temperature. Accordingly, it is possible to prevent a problem such as an electrode protrusion being lost due to an overload applied to the electrode during steady driving in which the discharge lamp 90 is driven with a predetermined driving power.

  In addition, according to the embodiment to which the present invention is applied, the control unit 40 compares the change Δv in the voltage between the electrodes of the discharge lamp 90 per unit time Δt after the start-up driving is compared with at least one threshold value. Based on the result, the current flowing through the discharge lamp 90 is changed. According to this configuration, drive control of the discharge lamp can be performed according to the state of the electrode. Therefore, the lighting operation of the discharge lamp 90 can be optimized in the start-up drive section with simple control.

  Further, according to the embodiment to which the present invention is applied, the control unit 40 determines the current flowing through the discharge lamp 90 based on the comparison result between the change in the interelectrode voltage of the discharge lamp 90 per unit time and at least one threshold value. Reduce. According to this configuration, when the temperature of the electrode is likely to rise due to the state of the electrode, it flows to the discharge lamp 90 during the start-up drive section so that the temperature of the electrode does not greatly exceed a predetermined temperature. Control to reduce the current. Thereby, the lighting operation of the discharge lamp 90 can be optimized in the start-up drive section with simple control.

  Further, according to the embodiment to which the present invention is applied, the control unit 40 determines the current flowing through the discharge lamp 90 based on the comparison result between the change in the interelectrode voltage of the discharge lamp 90 per unit time and at least one threshold value. Increase. According to this configuration, when it takes time to warm the electrode to a predetermined temperature depending on the state of the electrode, the current flowing through the discharge lamp 90 is increased in order to warm the electrode temperature to the predetermined temperature in the start-up drive section. Take control. Thereby, it is possible to perform control for increasing the brightness of the discharge lamp 90 faster. Therefore, the lighting operation of the discharge lamp 90 can be optimized in the start-up drive section with simple control.

Next, a modified example of the operation of the discharge lamp driving device 10 will be described using the flowchart of FIG.
As shown in FIG. 6, the control unit 40 of the discharge lamp driving device 10 determines the current flowing in the discharge lamp 90 during the start-up drive section based on the cumulative driving time of the discharge lamp 90 stored in the storage unit 44 so as to be overwritten. It may be configured to control the above.
When a drive switch (not shown) of the discharge lamp driving device 10 is turned on, the control unit 40 controls the high voltage generation circuit 70 to cause dielectric breakdown between the electrodes of the discharge lamp 90 (step S11). Next, the control unit 40 controls the voltage and current flowing into the discharge lamp 90 in the starting drive section (step S12). The starting drive is performed for a predetermined time set in advance, and when the predetermined time has elapsed, the start-up drive is started (step S13).

When the start-up driving is started, the control unit 40 accumulates the cumulative driving time of the discharge lamp 90 stored in the storage unit 44 so as to be overwritten, or the driving voltage when the discharge lamp 90 was lit in steady driving last time. Is acquired (step S14). Next, the control unit 40 determines whether the acquired cumulative drive time of the discharge lamp 90 or the drive voltage at the time of previous steady drive lighting exceeds a predetermined threshold stored in the storage unit 44 in advance. Is determined (step S15). When it is determined that the cumulative driving time of the discharge lamp 90 or the driving voltage at the time of previous steady driving lighting exceeds the threshold value (step S15: Yes), the control unit 40 subsequently calculates the voltage change Δv. It detects (step S16). In detail, the control unit 40, pouring over the set to a specified value current I _s a unit to the discharge lamp 90 Time Delta] t, to detect a voltage change Δv per unit time Delta] t.

Next, the control unit 40 determines whether or not the detected voltage change Δv per unit time Δt exceeds a threshold value stored in advance in the storage unit 44 (step S17). If exceeds the voltage change Δv threshold per unit time Delta] t (greater than the threshold value) (step S17: Yes), the control unit 40, according to the low current pattern I _L obtained by setting the current to a lower, raising the drive Is performed (step S19). On the other hand, a voltage change Δv per unit time Δt is not greater than the threshold value (threshold value or less) in the case (step S17: No), the control unit 40 does not a current value flowed to the discharge lamp 90 increases than the set current I _s Alternatively, the rising drive is performed with the current increase width smaller than the high current pattern I _H (step S18).
According to this configuration, when the cumulative drive time of the discharge lamp 90 is long or when the drive voltage at the time of previous steady drive lighting is high, control is performed to limit the current flowing into the discharge lamp 90 or the amount of change in the current. be able to. As a result, when there is a possibility that the load on the electrode is large at the time of lighting, the current flowing into the discharge lamp 90 can be set to a current that suppresses rapid deterioration and consumption of the electrode of the discharge lamp 90. It is possible to extend the service life.

In addition, when it is determined that the cumulative driving time of the discharge lamp 90 or the driving voltage at the time of previous steady driving lighting does not exceed the threshold value (step S15: No), the control unit 40 continues to set current I. A voltage change Δv per unit time Δt due to _s is detected. Next, the control unit 40 determines whether or not the detected voltage change Δv per unit time Δt exceeds a threshold value stored in advance in the storage unit 44 (step S21). If exceeds the voltage change Δv threshold per unit time Delta] t (greater than the threshold value) (step S21: Yes), the control unit 40, according to the low current pattern I _L obtained by setting the current to a lower, raising the drive Is performed (step S19). On the other hand, when the voltage change Δv per unit time Δt does not exceed the threshold (below the threshold) (step S21: No), the control unit 40 starts up according to the high current pattern I _H set to a higher current. Driving is performed (step S7). When the start-up drive is performed according to the low current pattern I _L , the high current pattern I _H , or a pattern in which the current is not increased or the increase width is reduced, and the power of the discharge lamp 90 reaches a predetermined drive power, the control unit 40 Then, steady driving is started (step S23).

  According to this modification, the control unit 40 limits the current flowing through the discharge lamp 90 or the amount of change in the current when the cumulative lighting time of the discharge lamp 90 is longer than a predetermined time. According to this configuration, when the cumulative driving time of the discharge lamp 90 is long, it is possible to perform control for limiting the current flowing into the discharge lamp 90 or the amount of change in the current. As a result, when the accumulated driving time is long and the load on the electrode may be large at the time of lighting, the current flowing into the discharge lamp 90 is limited so as not to exceed the specified current, or the increase width is reduced. Therefore, rapid deterioration and consumption of the electrodes of the discharge lamp 90 can be suppressed, and the life of the discharge lamp 90 can be extended.

  In addition, according to the above-described modification, the storage unit 44 that stores the voltage between the electrodes of the discharge lamp 90 at the time of steady driving in which the electric power supplied from the drive circuits 20 and 30 to the discharge lamp 90 is kept constant is provided. The unit 40 limits the current flowing through the discharge lamp 90 or the amount of change in the current based on the voltage between the electrodes of the discharge lamp 90 during the previous steady driving stored in the storage unit 44. According to this configuration, when the drive voltage at the time of previous steady drive lighting is high, it is possible to perform control for limiting the current flowing into the discharge lamp 90 or the amount of change in the current. Thereby, when the drive voltage at the time of the last steady drive lighting is high and there is a possibility that the load on the electrode is large at the time of lighting, the current flowing into the discharge lamp 90 is not increased beyond the specified current, or the increase width is reduced. Therefore, rapid deterioration and consumption of the electrodes of the discharge lamp 90 can be suppressed, and the life of the discharge lamp 90 can be extended.

In addition, the said embodiment is only an example of the specific aspect to which this invention is applied, This invention is not limited, It is also possible to apply this invention as an aspect different from the said embodiment.
For example, in the above-described embodiment, the configuration in which the light modulation device uses three transmissive or reflective liquid crystal panels corresponding to each color of RGB as the means for modulating the light emitted from the light source has been described as an example. However, the present invention is not limited to this, for example, a system using one liquid crystal panel and a color wheel, a system using three digital mirror devices (DMD), a single digital mirror device, You may comprise by the DMD system etc. which combined the color wheel.

  Further, each functional unit of the projector 100 shown in FIG. 1 or each functional unit of the discharge lamp driving device 10 shown in FIG. 2 shows a functional configuration realized by cooperation of hardware and software. Thus, the specific mounting form is not particularly limited. Therefore, it is not always necessary to mount hardware corresponding to each function unit individually, and it is of course possible to realize a function of a plurality of function units by one processor executing a program. In addition, in the above embodiment, a part of the function realized by software may be realized by hardware, or a part of the function realized by hardware may be realized by software. In addition, the specific detailed configuration of each part can be arbitrarily changed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Discharge lamp drive device, 20 ... Power control circuit (drive circuit), 30 ... AC converter circuit (drive circuit), 40 ... Control part (control means), 41 ... System controller, 42 ... Power control circuit controller, 43 ... AC conversion circuit controller, 44 ... storage unit, 60 ... motion detection unit, 70 ... high pressure generation circuit, 90 ... discharge lamp, 100 ... projector, 101 ... projector control unit, 102 ... image processing unit, 103 ... projection unit, _IH ... High current pattern, I _L ... Low current pattern, I _S ... Set current, SC ... Screen, Δt ... Unit time, Δv ... Voltage change.

Claims (9)

A drive circuit for supplying power to the discharge lamp to light it, and a control means for controlling the power supplied to the discharge lamp by the drive circuit,
The control means changes the current flowing through the discharge lamp in accordance with a change in the voltage between the electrodes of the discharge lamp after power supply to the discharge lamp in the extinguished state is started. The discharge lamp driving device according to claim 1,
The control means starts the supply of power to the discharge lamp in the extinguished state, and then sets the power supplied to the discharge lamp to a constant power before starting the steady drive and between the electrodes of the discharge lamp. A discharge lamp driving device that changes a current flowing through the discharge lamp in accordance with a change in voltage. The discharge lamp driving device according to claim 2,
The control means changes the current flowing through the discharge lamp based on a comparison result obtained by comparing a change in the voltage between the electrodes of the discharge lamp per unit time with at least one threshold value after starting the start-up drive. A discharge lamp driving device characterized by the above. The discharge lamp driving device according to claim 3,
The control means reduces the current flowing through the discharge lamp based on a comparison result between a change in the voltage between the electrodes of the discharge lamp per unit time and the at least one threshold value. The discharge lamp driving device according to claim 3,
The control means increases the current flowing through the discharge lamp based on a comparison result between a change in the voltage between the electrodes of the discharge lamp per unit time and the at least one threshold value. The discharge lamp driving device according to any one of claims 1 to 5,
The control means limits the current flowing through the discharge lamp or the amount of change in the current when the cumulative lighting time of the discharge lamp is longer than a predetermined time. The discharge lamp driving device according to any one of claims 1 to 6,
A storage means for storing the voltage between the electrodes of the discharge lamp at the time of steady driving for lighting the electric power supplied from the drive circuit to the discharge lamp with a constant power;
The discharge lamp driving device characterized in that the control means limits the current flowing through the discharge lamp or the amount of change in the current based on the voltage between the electrodes at the time of the previous steady drive stored in the storage means. A projector comprising a discharge lamp as a light source,
A drive circuit for supplying power to the discharge lamp to light it, and a control means for controlling the power supplied to the discharge lamp by the drive circuit,
The control means, after starting power supply to the discharge lamp in the extinguished state, changes a current flowing through the discharge lamp in accordance with a change in an interelectrode voltage of the discharge lamp. Controlling the power supplied to the discharge lamp by a driving circuit for supplying power to the discharge lamp and lighting it;
After starting the power supply to the discharge lamp in the extinguished state, a current flowing through the discharge lamp is changed in accordance with a change in the voltage between the electrodes of the discharge lamp.