JP2017188314A - Discharge lamp driving device, light source device, projector, and discharge lamp driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp drive device capable of inhibiting a distance between electrodes of a discharge lamp from be excessively small.SOLUTION: A discharge lamp drive device comprises: a discharge lamp drive section supplying a driving current to a discharge lamp having a first electrode and a second electrode; a control section controlling the discharge lamp drive section; and a voltage detection section detecting a voltage between the electrodes of the discharge lamp. The control section controls the discharge lamp drive section such that a thermal load adjustment period when a thermal load applied to the first electrode and the second electrode is adjusted according to the voltage between the electrodes is provided at least in a part of a rise period from a lighting start of the discharge lamp to performance of steady lighting drive, and, when the voltage between the electrodes detected by the voltage detection section is smaller than a first voltage, makes the thermal load in the thermal load adjustment period larger than the thermal load in the thermal load adjustment period when the voltage between the electrodes is equal to the first voltage or more.SELECTED DRAWING: Figure 9

Description

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

For the purpose of forming a projection on the electrode and forming a stable arc discharge, it has been proposed to drive a lamp in which an alternating current of a low frequency is inserted at a selected interval with respect to an alternating current of a steady lighting frequency ( For example, Patent Document 1).

JP 2006-59790 A

However, in the initial state in which the lamp is not relatively deteriorated, the projections of the electrodes may grow during the execution of the driving as described above, and the distance between the electrodes may become too small. In this case, the lamp voltage becomes excessively low, and it may be necessary to supply a driving current larger than the limit current value to the lamp in order to supply a desired driving power to the discharge lamp. As a result, the desired drive power may not be obtained, and the lamp brightness may be lowered. In addition, when the distance between the electrodes becomes too small, mercury sealed in the lamp may adhere to the electrodes and a mercury bridge may be formed in which the opposing electrodes are short-circuited.

One aspect of the present invention has been made in view of the above problems, and includes a discharge lamp driving device that can suppress the distance between electrodes of the discharge lamp from becoming too small, and such a discharge lamp driving device. An object is to provide a light source device and a projector including such a light source device. Another object of one aspect of the present invention is to provide a discharge lamp driving method that can prevent the distance between electrodes of the discharge lamp from becoming too small.

One aspect of the discharge lamp driving device of the present invention includes a discharge lamp driving unit that supplies a driving current to a discharge lamp having a first electrode and a second electrode, a control unit that controls the discharge lamp driving unit, and the discharge lamp. A voltage detection unit that detects a voltage between electrodes of the electric lamp, and the control unit includes at least a part of a startup period from when the discharge lamp starts lighting until steady lighting driving is performed. The discharge lamp driving unit is controlled to provide a thermal load adjustment period in which a thermal load applied to the first electrode and the second electrode is adjusted according to the voltage between the electrodes, and the control unit detects the voltage When the inter-electrode voltage detected by the unit is smaller than the first voltage, the thermal load in the thermal load adjustment period is the heat load in the thermal load adjustment period when the inter-electrode voltage is equal to or higher than the first voltage. Must be larger than the load The features.

According to one aspect of the discharge lamp driving device of the present invention, when the voltage between the electrodes decreases and becomes lower than the first voltage, the first electrode and the first electrode in the thermal load adjustment period provided in the rising period The heat load applied to the second electrode is increased. Therefore, it is possible to suppress the degree of melting of the protrusion from increasing and the distance between the electrodes of the discharge lamp from becoming too small. Therefore, in the initial state where the discharge lamp is not relatively deteriorated, it is possible to suppress the brightness of the discharge lamp from being lowered and to suppress the occurrence of a mercury bridge.

When the detected voltage between the electrodes is smaller than the first voltage, the control unit may increase the thermal load in the thermal load adjustment period as the detected voltage between the electrodes is smaller.
According to this configuration, the smaller the distance between the electrodes, the greater the heat load during the heat load adjustment period, and the greater the degree of melting of the protrusions. Thereby, it is easy to adjust a heat load appropriately according to the change of the distance between electrodes, and it can suppress more that the distance between electrodes of a discharge lamp becomes small too much.

Further, by increasing the thermal load in the thermal load adjustment period as the inter-electrode voltage is smaller, the thermal load in the thermal load adjustment period can be relatively reduced as the inter-electrode voltage is larger. Therefore, when the voltage between the electrodes is relatively large (when the distance between the electrodes is relatively large), the heat load during the heat load adjustment period can be relatively small, and the protrusion can be prevented from being melted excessively.

The rising period is a rising period in which the value of the driving current supplied to the discharge lamp increases,
A constant current period that is provided after the rising period and maintains a constant value of the drive current supplied to the discharge lamp, and the thermal load adjustment period is the constant current period It is good also as a structure provided in at least one part.
According to this configuration, the interelectrode voltage is relatively stable during the rising period during the constant current period. Therefore, by providing a thermal load adjustment period in the constant current period and adjusting the thermal load in the thermal load adjustment period, the protrusions can be easily melted suitably. Therefore, it can suppress more effectively that the distance between electrodes becomes small too much.

The said control part is good also as a structure which adjusts the said thermal load in the said thermal load adjustment period based on the said voltage between electrodes detected in the said steady lighting drive performed last time.
According to this configuration, it is not necessary to estimate the voltage between the electrodes in the steady lighting period in which the steady lighting drive is executed in the start-up period, which is simple.

The said control part is good also as a structure which adjusts the said thermal load in the said thermal load adjustment period based on the said voltage between electrodes detected in the said starting period.
According to this configuration, it is not necessary to store the value of the voltage between the electrodes in the steady lighting period in which the steady lighting driving is executed, which is simple. Even when the discharge lamp is turned on for the first time, the control unit can determine whether or not to increase the thermal load during the thermal load adjustment period.

When the detected voltage between the electrodes is smaller than the first voltage, the control unit determines whether or not the thermal load adjustment period is based on the driving power supplied to the discharge lamp in the steady lighting driving executed last time. The heat load may be adjusted.
According to this configuration, it is possible to appropriately apply a thermal load to the first electrode and the second electrode according to the thickness of the protrusion formed in the steady lighting drive executed last time.

When the detected voltage between the electrodes is smaller than the first voltage, the control unit reduces the thermal load adjustment period as the driving power supplied to the discharge lamp in the steady lighting driving executed last time is smaller. It is good also as a structure which makes the said heat load in small.
According to this structure, it can suppress that a protrusion melt | dissolves too much.

The controller may be configured to reduce the thermal load in the thermal load adjustment period when the interelectrode voltage detected in the thermal load adjustment period is equal to or greater than a second voltage that is greater than the first voltage. .
According to this structure, it can suppress that the distance between electrodes becomes large too much in a thermal load adjustment period.

The control unit is a case where the thermal load in the previous thermal load adjustment period is increased, and when the inter-electrode voltage detected this time is smaller than the first voltage, the current thermal load adjustment period. It is good also as a structure which makes the said heat load larger than the said heat load made large in the said last heat load adjustment period.
According to this configuration, once the thermal load in the thermal load adjustment period is increased, the voltage between the electrodes does not become the first voltage or higher (or even if it temporarily becomes the first voltage or higher, the voltage is again higher than the first voltage. In the next heat load adjustment period, a larger heat load can be applied to the first electrode and the second electrode. Therefore, the magnitude of the thermal load in the thermal load adjustment period can be adjusted appropriately, and the interelectrode distance can be further suppressed from becoming too small.

The drive current supplied to the discharge lamp in the thermal load adjustment period is an alternating current, and the controller increases the thermal load in the thermal load adjustment period by lowering the frequency of the alternating current. It is good also as composition to do.
According to this configuration, it is possible to adjust both the thermal load applied to the first electrode and the second electrode only by changing the frequency.

In the thermal load adjustment period, the driving current may alternately include a direct current period in which a direct current is supplied to the discharge lamp and an alternating current period in which an alternating current is supplied to the discharge lamp.
According to this configuration, the degree of melting of the protrusion can be increased by the direct current period, while the protrusion can be grown by the alternating current period. Thereby, even when the thermal load in the thermal load adjustment period is increased, it is easy to adjust the length of the protrusion so that the protrusion is not shortened and the distance between the electrodes is not increased too much.

The controller may be configured to increase the thermal load in the thermal load adjustment period by increasing the length of the direct current period.
According to this configuration, it is easy to increase the thermal load during the thermal load adjustment period, and it is easier to suppress the interelectrode distance from becoming too small.

The said control part is good also as a structure which enlarges the said thermal load in the said thermal load adjustment period by making low the frequency of the said alternating current in the said alternating period.
According to this configuration, it is possible to increase both the thermal loads applied to the first electrode and the second electrode.

The controller may be configured to increase the thermal load in the thermal load adjustment period by reducing the length of the AC period.
According to this configuration, the interval in which the DC period is provided can be reduced, and the thermal load applied to the first electrode and the second electrode can be easily increased.

The DC period includes a first DC period in which a first polarity DC current is supplied to the discharge lamp, and a second DC period in which a second polarity DC current opposite to the first polarity is supplied to the discharge lamp. And the drive current has a first mixing period alternately including the first DC period and the AC period, and the control unit includes the first DC period included in the first mixing period. It is good also as a structure which enlarges the said thermal load in the said thermal load adjustment period by increasing the number of.
According to this configuration, the temperature of the first electrode can be made relatively high, and the protrusions of the first electrode can be more easily melted. Therefore, it is easier to suppress the interelectrode distance from becoming too small.

The controller may be configured to increase the thermal load during the thermal load adjustment period by increasing the drive current.
According to this configuration, it is possible to suppress the interelectrode distance from becoming too small by increasing the degree of melting of the protrusions without changing the waveform of the drive current during the thermal load adjustment period. for that reason,
Control of the discharge lamp driving unit is simple.

The controller may be configured to increase the thermal load during the thermal load adjustment period by increasing the driving power supplied to the discharge lamp.
According to this configuration, it is possible to suppress the interelectrode distance from becoming too small by increasing the degree of melting of the protrusions without changing the waveform of the drive current during the thermal load adjustment period. for that reason,
Control of the discharge lamp driving unit is simple.

One aspect of the light source device of the present invention includes a discharge lamp that emits light, the discharge lamp driving device, and
It is characterized by providing.

According to one aspect of the light source device of the present invention, since the discharge lamp driving device is provided, it is possible to suppress the distance between the electrodes of the discharge lamp from becoming too small.

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

According to one aspect of the projector of the present invention, since the light source device is provided, it is possible to suppress the distance between the electrodes of the discharge lamp from becoming too small.

One aspect of the discharge lamp driving method of the present invention is a discharge lamp driving method for driving a discharge lamp by supplying a driving current to a discharge lamp having a first electrode and a second electrode. In at least a part of the rising period from the start of lighting until the steady lighting drive is performed, the first
A thermal load adjustment period in which a thermal load applied to the electrode and the second electrode is adjusted according to an inter-electrode voltage of the discharge lamp, and when the detected inter-electrode voltage is smaller than the first voltage, The thermal load in the load adjustment period is made larger than the thermal load in the thermal load adjustment period when the voltage between the electrodes is equal to or higher than the first voltage.

According to one aspect of the discharge lamp driving method of the present invention, it is possible to suppress the distance between the electrodes of the discharge lamp from becoming too small in the same manner as described above.

It is a schematic block diagram of the projector of 1st Embodiment. It is a figure which shows the discharge lamp in 1st Embodiment. It is a block diagram which shows the various components of the projector of 1st Embodiment. It is a circuit diagram of the discharge lamp lighting device of a 1st embodiment. It is a block diagram which shows the example of 1 structure of the control part of 1st Embodiment. It is a figure which shows the mode of the protrusion of the electrode tip of a discharge lamp. It is a figure which shows the mode of the protrusion of the electrode tip of a discharge lamp. It is a graph which shows the change of the absolute value of the drive current in 1st Embodiment. It is a graph which shows an example of the drive current in the thermal load adjustment period of 1st Embodiment. It is a flowchart which shows an example of the control procedure by the control part of 1st Embodiment. It is a graph which shows an example of the change of the lamp voltage in the starting period of 1st Embodiment. It is a graph which shows an example of the drive current in the thermal load adjustment period of 2nd Embodiment. It is a graph which shows an example of the drive current in the thermal load adjustment period of 3rd Embodiment.

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

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

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

The illumination optical system 310 converts the illuminance of light emitted from the light source device 200 to the liquid crystal light valve 3.
It adjusts so that it may become uniform on 30R, 330G, 330B. Furthermore, the illumination optical system 310 aligns the polarization direction of the light emitted from the light source device 200 in one direction. The reason is,
This is because the light emitted from the light source device 200 is effectively used by the liquid crystal light valves 330R, 330G, and 330B.

The light whose illuminance distribution and polarization direction are adjusted enters the color separation optical system 320. The color separation optical system 320 separates incident light into three color lights of red light (R), green light (G), and blue light (B). The three color lights are liquid crystal light valves 330R, 330G, and 33 associated with the respective color lights.
By 0B, each is modulated according to the video signal. Liquid crystal light valve 330R, 330
G and 330B include liquid crystal panels 560R, 560G, and 560B, which will be described later, and polarizing plates (not shown). The polarizing plates are disposed on the light incident side and the light emitting side of the liquid crystal panels 560R, 560G, and 560B, respectively.

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

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

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

The shape of the discharge lamp 90 is a rod shape extending along the irradiation direction D. One end of the discharge lamp 90 is a first end 90e1, and the other end of the discharge lamp 90 is a second end 90e2. Discharge lamp 9
The material of 0 is, for example, a translucent material such as quartz glass. The central portion of the discharge lamp 90 swells in a spherical shape, and the inside is a discharge space 91. The discharge space 91 is filled with a gas that is a discharge medium containing a rare gas, a metal halide, or the like.

In the discharge space 91, the tips of the first electrode 92 and the second electrode 93 protrude. The first electrode 92 is disposed on the first end portion 90 e 1 side of the discharge space 91. The second electrode 93 is disposed on the second end 90 e 2 side of the discharge space 91. The shape of the first electrode 92 and the second electrode 93 is a rod shape extending along the optical axis AX. In the discharge space 91, the electrode tip portions of the first electrode 92 and the second electrode 93 are arranged to face each other with a predetermined distance. First electrode 9
The material of the second and second electrodes 93 is, for example, a metal such as tungsten.

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

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

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

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

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

Hereinafter, the circuit configuration of the projector 500 will be described.
FIG. 3 is a diagram illustrating an example of a circuit configuration of the projector 500 according to the present embodiment. In addition to the optical system shown in FIG. 1, the projector 500 includes an image signal converter 510 and a DC power supply 8.
0, liquid crystal panels 560R, 560G, and 560B, an image processing device 570, and a CPU (Ce
ntral Processing Unit) 580.

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

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

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

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

The liquid crystal panels 560R, 560G, and 560B include the liquid crystal light valves 330R and 3 described above.
30G and 330B are provided respectively. Liquid crystal panel 560R, 560G, 560B
Modulates the transmittance (luminance) of color light incident on the liquid crystal panels 560R, 560G, and 560B via the optical system described above based on the drive signals 572R, 572G, and 572B, respectively.

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

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

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

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

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

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

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

The polarity inversion circuit 30 is, for example, a first switch element 3 constituted by a transistor or the like.
1, second switch element 32, third switch element 33, and fourth switch element 34
Is included. The polarity inversion circuit 30 includes a first switch element 31 and a second switch connected in series.
The 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. The polarity inversion control signal is input from the control unit 40 to the control terminals of the first switch element 31, the second switch element 32, the third switch element 33, and the fourth switch element 34, respectively. Based on this polarity inversion control signal, the ON / OFF operation of the first switch element 31, the second switch element 32, the third switch element 33, and the fourth switch element 34 is controlled.

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

That is, the polarity inverting circuit 30 includes the first switch element 31 and the fourth switch element 3.
When 4 is ON, the second switch element 32 and the third switch element 33 are OFF, and when the first switch element 31 and the fourth switch element 34 are OFF, the second switch element 32 and the third switch element 32 Control is performed so that the switch element 33 is ON. Therefore, when the first switch element 31 and the fourth switch element 34 are ON, the drive current I flowing from the one end of the capacitor 24 in the order of the first switch element 31, the discharge lamp 90, and the fourth switch element 34 is generated. To do. Second switch element 32 and third switch element 33
Is ON, the third switch element 33, the discharge lamp 90,
A drive current I that flows in the order of the second switch element 32 is generated.

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

The control unit 40 controls the discharge lamp driving unit 230. In the example of FIG. 4, the control unit 40 controls the power control circuit 20 and the polarity inversion circuit 30, so that the drive current I maintains the same polarity, the current value of the drive current I (the power of the drive power Wd) Value), frequency, and other parameters. The control unit 40 performs polarity reversal control for the polarity reversing circuit 30 to control the holding time during which the drive current I continues at the same polarity, the frequency of the drive current I, and the like according to the polarity reversal timing of the drive current I. The controller 40 outputs an output direct current I to the power control circuit 20.
Current control for controlling the current value of d is performed.

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

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

In the present embodiment, the system controller 41 includes a storage unit 44 and a measurement unit 4.
5 is connected.
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 f, a waveform, and a modulation pattern.

The measurement unit 45 measures the number of thermal load adjustment periods HL, which will be described later, executed in a state where the thermal load applied to the first electrode 92 and the second electrode 93 is increased. The control unit 40 includes the measurement unit 4
The number of thermal load adjustment periods HL measured according to 5 is stored in the storage unit 44. Note that the measurement unit 45 may be incorporated in the storage unit 44, for example.

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

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

The control unit 40 is realized using a dedicated circuit, and can perform the above-described control and various types of control of processing to be described later. On the other hand, the control unit 40 is configured such that, for example, the CPU stores the storage unit 4.
It is also possible to function as a computer by executing the control program stored in 4, and to perform various controls of these processes.

FIG. 5 is a diagram for explaining another configuration example of the control unit 40. As shown in FIG. 5, the control unit 40 includes a current control unit 40 that controls the power control circuit 20 according to a control program.
-1, it may be configured to function as polarity inversion control means 40-2 for controlling the polarity inversion circuit 30.

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

In the present embodiment, the operation detection unit 60 includes a voltage detection unit 64 that detects the lamp voltage Vla of the discharge lamp 90 and outputs lamp voltage information to the control unit 40. Further, the operation detection unit 60 may include a current detection unit that detects the drive current I and outputs drive current information to the control unit 40. In the present embodiment, the operation detection unit 60 includes a first resistor 61 and a second resistor 62.
And a third resistor 63.

In the present embodiment, the voltage detector 64 of the operation detector 60 detects the lamp voltage Vla in parallel with the discharge lamp 90 by the voltage divided by the first resistor 61 and the second resistor 62 connected in series with each other. To do. In the present embodiment, the current detection unit detects the drive current I based on the voltage generated in the third resistor 63 connected in series to the discharge lamp 90.

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

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

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

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

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

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

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

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

FIG. 7 is a graph showing changes in the absolute value Ia of the drive current I in the present embodiment. FIG.
, The vertical axis indicates the absolute value Ia of the drive current I, and the horizontal axis indicates the time T. FIG. 7 shows a change in the driving current I from the time when the discharge lamp 90 is turned on until the steady lighting state is obtained. In FIG. 7, the time when dielectric breakdown occurs between the first electrode 92 and the second electrode 93 is defined as time T0 when the discharge lamp 90 starts to light.

As shown in FIG. 7, when the discharge lamp 90 starts to light, a steady lighting period ST is provided after a start-up period RP. The start-up period RP is a period from when the discharge lamp 90 starts to be lit until steady lighting driving is performed. The rising period RP includes a start period RP1, a rising period RP2, a constant current period RP3, and an adjustment period RP4 in this order.

The starting period RP1 is provided from the time (time T0) when the discharge lamp 90 starts to be lit to time T1. In the starting period RP1, the absolute value Ia of the drive current I is constant. Start period RP
The length of 1 is, for example, about 5 s (seconds).

The rising period RP2 is a period in which the value (absolute value Ia) of the drive current I supplied to the discharge lamp 90 increases. In the rising period RP2 of the present embodiment, the absolute value Ia of the driving current I rises linearly as the time T increases. The rising period RP2 is the absolute value I of the drive current I.
It is provided until time T2 when a reaches the limit current value Ir.

The constant current period RP3 is provided after the rising period RP2 in terms of time, and is a period in which the value of the drive current I (absolute value Ia) supplied to the discharge lamp 90 is kept constant. In the present embodiment, the constant current period RP3 is provided from the time when the rising period RP2 ends (time T2) to the time T3. In the constant current period RP3, the absolute value Ia of the drive current I is maintained at the limit current value Ir.

In the adjustment period RP4, the absolute value Ia of the drive current I is changed to the discharge lamp 90 in the steady lighting period ST.
This is a period for adjusting to the absolute value Ia of the drive current I supplied to. In the present embodiment, the adjustment period RP4 is provided from the end of the constant current period RP3 (time T3) to the time T4. In the adjustment period RP4 of the present embodiment, the absolute value Ia of the drive current I increases linearly as the time T increases.

The steady lighting period ST is a period during which steady lighting driving is performed in which the discharge lamp 90 is stably lit. The absolute value Ia of the drive current I in the steady lighting period ST of the present embodiment is, for example, the steady current value Is. The steady current value Is is larger than the limit current value Ir. The steady current value Is may be smaller than the limit current value Ir.

The control unit 40 controls the discharge lamp driving unit 230 so that the thermal load adjustment period HL is provided in at least a part of the rising period RP. In the present embodiment, the thermal load adjustment period HL is provided in at least a part of the constant current period RP3. More specifically, in the present embodiment, the thermal load adjustment period HL is the entire constant current period RP3. The thermal load adjustment period HL is the first electrode 9
This is a period in which the thermal load applied to the second and second electrodes 93 is adjusted according to the lamp voltage Vla.

FIG. 8 is a graph showing an example of the drive current I in the thermal load adjustment period HL of the present embodiment. In FIG. 8, the vertical axis represents the drive current I, and the horizontal axis represents time T. The drive current I is shown as positive when it is in the first polarity state and negative when it is in the second polarity state.

As shown in FIG. 8, in this embodiment, the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL is an alternating current. In the thermal load adjustment period HL, the drive current I has a plurality of AC periods AC. In the example of FIG. 8, the drive current I in the thermal load adjustment period HL is
It has 1st alternating current period AC1, 2nd alternating current period AC2, and 3rd alternating current period AC3. First
The AC period AC1 to the third AC period AC3 are periods in which an AC current is supplied to the discharge lamp 90. In the example of FIG. 8, in each AC period AC, a rectangular wave driving current I whose polarity is inverted a plurality of times between the current value Im1 and the current value −Im1 is supplied to the discharge lamp 90.

The first AC period AC1, the second AC period AC2, and the third AC period AC3 are periodically and repeatedly provided in this order. The frequency f1 of the alternating current supplied to the discharge lamp 90 in the first AC period AC1 and the frequency f of the AC current supplied to the discharge lamp 90 in the second AC period AC2
2 and the frequency f3 of the alternating current supplied to the discharge lamp 90 in the third alternating period AC3 are:
Different from each other. That is, in the thermal load adjustment period HL of the present embodiment, the drive current I has a plurality of periods in which the alternating current frequency f is different from each other. In the example of FIG. 8, each frequency f becomes higher in the order of frequency f2, frequency f1, and frequency f3.

The length ta1 of the first AC period AC1, the length ta2 of the second AC period AC2, and the length ta3 of the third AC period AC3 may be the same or different from each other.
In the example of FIG. 8, the number of periods of the alternating current supplied to the discharge lamp 90 in each AC period AC is the same, and the length of each AC period is different.

In the present embodiment, the control unit 40 determines the thermal load adjustment period HL based on the lamp voltage Vla.
The magnitude of the thermal load applied to the first electrode 92 and the second electrode 93 is adjusted. FIG.
These are flowcharts which show an example of the control procedure by the control part 40. FIG.

As shown in FIG. 9, the control unit 40 detects the lamp voltage Vl detected by the voltage detection unit 64.
It is determined whether a is smaller than the first voltage Vla1 (step S1). The determination in step S1 is performed, for example, in a period from when the power source of the projector 500 is turned on to before the constant current period RP3. More specifically, the determination in step S1 is performed, for example, in the starting period RP1 or the rising period RP2.

Here, in the present embodiment, the lamp voltage Vla used for the determination in step S1 is, for example, the lamp voltage Vla detected in the steady lighting drive executed last time. The steady lighting drive executed last time is the steady lighting drive that was executed when the power of the projector 500 was turned on before the power of the projector 500 was turned on this time. Control unit 40
Causes the storage unit 44 to store the value of the lamp voltage Vla when the steady lighting drive is being executed. The control unit 40 refers to the lamp voltage Vla detected in the steady lighting drive executed last time from the storage unit 44 and performs the determination in step S1. The control unit 40, for example, last time the lamp voltage V of steady lighting driving immediately before the power of the projector 500 is turned off.
la is used for the determination in step S1.

When the lamp voltage Vla is equal to or higher than the first voltage Vla1 (Step S1:
NO), the heat load in the heat load adjustment period HL is set to a predetermined size (step S2).
. The predetermined thermal load is, for example, the magnitude of the thermal load applied to the first electrode 92 and the second electrode 93 by a drive current waveform or the like set in advance to extend the life of the discharge lamp 90. is there.

On the other hand, when the lamp voltage Vla is smaller than the first voltage Vla1 (step S1: YES), the control unit 40 sets the thermal load in the thermal load adjustment period HL to be larger than a predetermined magnitude (step S3). That is, when the lamp voltage Vla detected by the voltage detection unit 64 is smaller than the first voltage Vla1, the control unit 40 determines the thermal load during the thermal load adjustment period HL and the case where the lamp voltage Vla is equal to or higher than the first voltage Vla1. It is made larger than the heat load in the heat load adjustment period HL. The controller 40 starts the thermal load adjustment period HL (constant current period RP3) with the set thermal load (step S4).

In this specification, “thermal load in the thermal load adjustment period” means the thermal load adjustment period H
The sum of the thermal loads applied to the first electrode 92 and the second electrode 93 in the entire L is included.

In the present embodiment, the control unit 40 adjusts the thermal load in the thermal load adjustment period HL by adjusting the frequency f of the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL. Specifically, when increasing the thermal load in the thermal load adjustment period HL, the control unit 40 increases the thermal load in the thermal load adjustment period HL by reducing the frequency f of the drive current I.
That is, when the lamp voltage Vla detected by the voltage detector 64 is smaller than the first voltage Vla1, the control unit 40 determines the frequency of the alternating current supplied to the discharge lamp 90 in the thermal load adjustment period HL as the lamp voltage Vla. Thermal load adjustment period HL when is equal to or higher than the first voltage Vla1
The frequency of the alternating current supplied to the discharge lamp 90 is set to be lower. When it has several AC periods (1st AC period AC1-3rd AC period AC3) from which frequency f differs like this embodiment, the control part 40 makes the average frequency of the whole some AC period low. In this case, if the average frequency of the plurality of AC periods as a whole is low, the frequency f may not change or the frequency f may be high in some AC periods.

When the detected lamp voltage Vla is smaller than the first voltage Vla1, the control unit 40 increases the thermal load in the thermal load adjustment period HL as the detected lamp voltage Vla is smaller. In the present embodiment, the control unit 40 decreases as the detected lamp voltage Vla decreases.
Frequency f of alternating current (drive current I) supplied to the discharge lamp 90 in the thermal load adjustment period HL
Lower. An example of the frequency f corresponding to the lamp voltage Vla is shown in Table 1.

In the example of Table 1, the first voltage Vla1 is 60V. In the examples of Table 2 to Table 7 described below, the first voltage Vla1 is 60V. In this embodiment,
The thermal load set to a predetermined magnitude in the thermal load adjustment period HL corresponds to the thermal load in the thermal load adjustment period HL when the lamp voltage Vla is equal to or higher than the first voltage Vla1. For example, in Table 1, the thermal load set to a predetermined magnitude in the thermal load adjustment period HL is set such that the frequency f1 of the alternating current supplied to the discharge lamp 90 in the first alternating period AC1 is set to 280 Hz. The frequency f2 of the alternating current supplied to the discharge lamp 90 during the alternating period AC2 is 190.
This is equivalent to setting the frequency f3 of the alternating current supplied to the discharge lamp 90 to 370 Hz in the third AC period AC3.

Moreover, in the example of Table 1, the magnitude relationship of the frequency f of the alternating current in each AC period AC is the same regardless of the lamp voltage Vla. Note that the magnitude relationship of the frequency f of the alternating current in each AC period AC may change according to the lamp voltage Vla.

As described above, the control unit 40 adjusts the thermal load in the thermal load adjustment period HL based on the lamp voltage Vla detected in the steady lighting drive executed last time.

The controller 40 causes the voltage detector 64 to detect the lamp voltage Vla in the thermal load adjustment period HL. The controller 40 determines that the lamp voltage Vla detected in the thermal load adjustment period HL is the second
It is determined whether or not the voltage is Vla2 or higher (step S5). The second voltage Vla2 is the first voltage Vla
It is larger than la1. When the lamp voltage Vla is smaller than the second voltage Vla2 (step S5: NO), the control unit 40 maintains the heat load in the heat load adjustment period HL as the set heat load (step S6).

On the other hand, when the lamp voltage Vla detected in the thermal load adjustment period HL is equal to or higher than the second voltage Vla2 (step S5: YES), the control unit 40 reduces the thermal load in the thermal load adjustment period HL (step S7). . For example, when the thermal load in the thermal load adjustment period HL is set to be larger than a predetermined magnitude according to the determination in step S1, the control unit 40 changes the thermal load in the thermal load adjustment period HL to a predetermined magnitude. Let In the present embodiment, the control unit 40 increases the frequency f of the alternating current (drive current I) supplied to the discharge lamp 90 during the thermal load adjustment period HL, and decreases the thermal load during the thermal load adjustment period HL. The second voltage Vla2 is about 75V as an example.

The controller 40 determines whether or not a predetermined time has elapsed since the start of the thermal load adjustment period HL (step S8). If the predetermined time has not elapsed (step S8: NO), the thermal load adjustment is performed. Continue the period HL. When a predetermined time has elapsed since the start of the thermal load adjustment period HL (step S8: YES), the control unit 40 ends the thermal load adjustment period HL (step S9).
.

The discharge lamp lighting device 10 including the control unit 40 that performs the control described above can also be expressed as a discharge lamp driving method. That is, one aspect of the discharge lamp driving method of the present embodiment is a discharge lamp driving method for driving the discharge lamp 90 by supplying the driving current I to the discharge lamp 90 having the first electrode 92 and the second electrode 93. In addition, the heat load applied to the first electrode 92 and the second electrode 93 during at least a part of the start-up period RP from when the discharge lamp 90 starts to light until the steady lighting drive is performed. When the detected lamp voltage Vla is smaller than the first voltage Vla1, the thermal load in the thermal load adjustment period HL is set to the first load voltage Vla. Thermal load adjustment period HL for voltage Vla1 or higher
It is characterized by being larger than the heat load at.

In an initial state in which the discharge lamp 90 is not relatively deteriorated, the first operation is performed during the steady lighting drive.
In some cases, the protrusion 552p of the electrode 92 grows and the distance between the electrodes becomes too small. In this case, the lamp voltage Vla becomes excessively low, and it may be necessary to supply the discharge lamp 90 with a drive current I that is larger than the limit current value Ir in order to supply the desired drive power Wd to the discharge lamp 90. As a result, the desired drive power Wd may not be obtained as a result, and the luminance of the discharge lamp 90 may be lowered. If the distance between the electrodes becomes too small, mercury Hg sealed in the discharge space 91 adheres to the first electrode 92 and the second electrode 93, and the first electrode 92 and the second electrode 93 are short-circuited. Mercury bridges may occur.

On the other hand, according to the present embodiment, when the lamp voltage Vla decreases and becomes lower than the first voltage Vla1 in the steady lighting driving, in the thermal load adjustment period HL provided in the rising period RP, The heat load applied to the first electrode 92 and the second electrode 93 is increased. Therefore, it is possible to suppress the degree of melting of the protrusions 552p and 562p from increasing and the distance between the electrodes of the discharge lamp 90 from becoming too small. Therefore, in the initial state in which the discharge lamp 90 is not relatively deteriorated, it is possible to suppress the brightness of the discharge lamp 90 from being lowered and to suppress the occurrence of a mercury bridge.

Further, for example, a method of increasing the lamp voltage Vla by increasing the frequency f of the drive current I when the lamp voltage Vla is lower than a predetermined value can be considered for the above-described problem. Then, the protrusions 552p and 562p are thin and small, and there is a problem of accelerating the deterioration of the discharge lamp 90. Further, when the lamp voltage Vla rises by this method and the driving returns to the steady lighting driving, the projections 552p and 562 narrowed due to a sudden change in the thermal load.
In some cases, p disappeared.

On the other hand, according to the present embodiment, the protrusions 552p, 56 in the heat load adjustment period HL.
The degree of melting of 2p increases, and the protrusions 552p and 562p can be formed thick and large. Thereby, it can suppress that deterioration of the discharge lamp 90 accelerates.

Further, according to the present embodiment, the thermal load adjustment period HL for increasing the thermal load is provided in the start-up period RP. Therefore, even if the brightness of the image projected from the projector 500 changes by adjusting the thermal load applied to the first electrode 92 and the second electrode 93, the influence on the user of the projector 500 can be reduced. Therefore, the convenience of the projector 500 can be improved.

In addition, since the influence on the user of the projector 500 can be reduced, it is possible to reduce the limit for adjusting each parameter of the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL. Thereby, it is easy to appropriately adjust each parameter of the drive current I supplied to the discharge lamp 90, and it is easy to appropriately adjust the thermal load applied to the first electrode 92 and the second electrode 93 in the thermal load adjustment period HL. Therefore, according to this embodiment, it is easier to suppress the first electrode 92 and the second electrode 93 from growing too much and the inter-electrode distance becoming too small.

Further, according to the present embodiment, the smaller the lamp voltage Vla, the greater the thermal load in the thermal load adjustment period HL. Therefore, the smaller the distance between the electrodes, the greater the heat load in the heat load adjustment period HL, and the greater the degree of melting of the protrusions 552p and 562p. Thereby, it is easy to adjust a heat load appropriately according to the distance between electrodes, and it can suppress more that the distance between electrodes of the discharge lamp 90 becomes small too much.

Further, for example, when the heat load in the heat load adjustment period HL is increased more than necessary, the protrusion 5
52p and 562p may melt too much. If the protrusions 552p and 562p are excessively melted, the shapes of the protrusions 552p and 562p are flattened, and the arc position is likely to change. For this reason, the angle of the light emitted from the discharge lamp 90 increases, and light that falls off the optical path may occur due to vignetting in the optical system of the projector 500. Thereby, the illuminance of the projector 500 may decrease. Further, the projector 50 is changed by changing the arc position.
In some cases, the illuminance of 0 changed and flicker occurred.

On the other hand, by increasing the thermal load in the thermal load adjustment period HL as the lamp voltage Vla is smaller, the thermal load in the thermal load adjustment period HL can be relatively reduced as the lamp voltage Vla is larger. Therefore, when the lamp voltage Vla is relatively large (when the distance between the electrodes is relatively large), the heat load during the heat load adjustment period HL can be relatively small, and the protrusion 5
It can control that 52p and 562p melt too much. As a result, the projector 500
Illuminance drop and flicker generation can be suppressed.

Further, according to the present embodiment, the thermal load adjustment period HL is provided in at least a part of the constant current period RP3. The constant current period RP3 is compared with the starting period RP1 and the rising period RP2.
The lamp voltage Vla is relatively stable. Therefore, by providing the thermal load adjustment period HL in the constant current period RP3 and adjusting the thermal load in the thermal load adjustment period HL, the protrusions 552p and 56
2p is easily melted suitably. Therefore, it can suppress more effectively that the distance between electrodes becomes small too much.

Further, the lamp voltage Vla in the rising period RP is different from the lamp voltage Vla in the steady lighting period ST. Therefore, for example, when the lamp voltage Vla detected by the voltage detector 64 in the rising period RP is used for the determination in step S1, the lamp voltage Vla in the steady lighting period ST is estimated from the lamp voltage Vla in the rising period RP. It takes time and effort. Further, in the rising period RP, the lamp voltage Vla is equal to the steady lighting period ST.
Therefore, the estimation accuracy of the lamp voltage Vla during the steady lighting period ST may be low.

On the other hand, according to the present embodiment, the thermal load in the thermal load adjustment period HL is set based on the lamp voltage Vla detected in the steady lighting drive executed last time. Therefore, there is no need to estimate the lamp voltage Vla in the steady lighting period ST, which is simple. As a result, the estimation accuracy of the lamp voltage Vla used for the determination in step S1 does not decrease.

FIG. 10 is a graph showing an example of a change in the lamp voltage Vla during the rising period RP.
In FIG. 10, the vertical axis represents the lamp voltage Vla, and the horizontal axis represents time T. As shown in FIG. 10, the ramp voltage Vla rises to the value VlaS in the rise period RP2. In the rising period RP2, the ramp voltage Vla rises linearly as the time T increases, for example.

Here, when the control unit 40 increases the thermal load in the thermal load adjustment period HL to be larger than a predetermined size, the inter-electrode distance may increase in the thermal load adjustment period HL, and the lamp voltage Vla may increase. At this time, the distance between the electrodes may increase rapidly due to, for example, the protrusions 552p and 562p becoming thin. In this case, the distance between the electrodes (lamp voltage Vla) becomes excessively large, and the illuminance of the projector 500 may decrease. In addition, the life of the discharge lamp 90 may be reduced.

On the other hand, according to the present embodiment, when the lamp voltage Vla detected in the thermal load adjustment period HL is equal to or higher than the second voltage Vla2 larger than the first voltage Vla1, the thermal load in the thermal load adjustment period HL is reduced. To do. Therefore, it can suppress that the distance between electrodes becomes large too much in the heat load adjustment period HL. Thereby, it can suppress that the illumination intensity of the projector 500 and the lifetime of the discharge lamp 90 fall.

Specifically, in the example of FIG. 10, the control unit 40 determines that the lamp voltage Vla is greater than the value VlaS of the lamp voltage Vla at the start time (time T2) of the thermal load adjustment period HL.
From time T2a when 2 is reached, the thermal load in the thermal load adjustment period HL is reduced. The value VlaS of the lamp voltage Vla is smaller than the first voltage Vla1. In the example of FIG.
In the thermal load adjustment period HL, the thermal load of the thermal load adjustment period HL is made larger than a predetermined size from time T2 to time T2a, and the thermal load adjustment is performed from time T2a to time T3 in the thermal load adjustment period HL. The heat load in the period HL is set to a predetermined size. From time T2a to time T3, since the thermal load in the thermal load adjustment period HL becomes small, the distance between the electrodes gradually decreases and the lamp voltage Vla decreases.

For example, in the thermal load adjustment period HL in which the thermal load is set to a predetermined size,
When the lamp voltage Vla becomes equal to or higher than the second voltage Vla2, the control unit 40 makes the thermal load in the thermal load adjustment period HL smaller than a predetermined magnitude.

Moreover, according to this embodiment, the control part 40 enlarges the thermal load in the thermal load adjustment period HL by lowering the frequency f of the alternating current. Therefore, both the thermal loads applied to the first electrode 92 and the second electrode 93 can be changed only by adjusting the frequency f.

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

In the present embodiment, the control unit 40 detects the lamp voltage Vla detected in the rising period RP.
Based on the above, the thermal load in the thermal load adjustment period HL may be adjusted. According to this configuration,
It is not necessary to store the value of the lamp voltage Vla in the steady lighting period ST in the storage unit 44.
Even when the power source of the projector 500 is turned on for the first time, the determination in step S1 can be performed. Therefore, for example, even when the discharge lamp 90 has a relatively small distance between the electrodes from the initial state due to manufacturing variations and the lamp voltage Vla is smaller than the first voltage Vla1, the power supply of the projector 500 is turned on for the first time. In the heat load adjustment period HL, the heat load can be made larger than a predetermined size. Thereby, it can suppress that the distance between electrodes becomes small irrespective of the manufacture variation of the discharge lamp 90. FIG.

In the present embodiment, the thermal load adjustment period HL may be provided only in a part of the constant current period RP3, or may be provided in a period other than the constant current period RP3 in the rising period RP. . Further, the entire rising period RP may be the thermal load adjustment period HL. In the present embodiment, a plurality of thermal load adjustment periods HL may be provided within the rising period RP.

In the present embodiment, the control unit 40 may increase the thermal load in the thermal load adjustment period HL by increasing the drive current I. That is, the control unit 40 includes the voltage detection unit 64.
Is smaller than the first voltage Vla1, the current value of the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL is the same as the case where the lamp voltage Vla is equal to or higher than the first voltage Vla1. The current value of the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL is made larger. In this configuration, the control unit 40 is, for example, a constant current period R
By increasing the limit current value Ir in P3 (thermal load adjustment period HL), the thermal load in the thermal load adjustment period HL is increased. According to this configuration, in the heat load adjustment period HL,
Without adjusting parameters other than the current value of the drive current I, the degree of melting of the protrusions 552p and 562p can be increased to prevent the interelectrode distance from becoming too small. Therefore, the control of the discharge lamp driving unit 230 is simple.

Table 2 shows an example in which the drive current I in the thermal load adjustment period HL is adjusted according to the lamp voltage Vla. Table 2 shows that the limit power value in the thermal load adjustment period HL is the lamp voltage Vla.
It shows the case where it is constant regardless.

In the present embodiment, the control unit 40 may increase the thermal load during the thermal load adjustment period HL by increasing the driving power Wd supplied to the discharge lamp 90. That is,
The controller 40 determines that the ramp voltage Vla detected by the voltage detector 64 is the first voltage Vla1.
Is smaller than the power value of the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL, the power value is supplied to the discharge lamp 90 in the thermal load adjustment period HL when the lamp voltage Vla is equal to or higher than the first voltage Vla1. Larger than the power value of the driving current I. In this configuration, the control unit 40 increases the thermal load in the thermal load adjustment period HL, for example, by increasing the power limit value in the constant current period RP3 (thermal load adjustment period HL). According to this configuration, as in the case of adjusting the value of the drive current I described above, the drive current I is adjusted during the thermal load adjustment period HL.
Without adjusting parameters other than the current value, the degree of melting of the protrusions 552p and 562p can be increased to prevent the interelectrode distance from becoming too small. Therefore, the discharge lamp driving unit 23
Control of 0 is simple.

Further, in this configuration, when the driving power Wd is increased, the luminance of light emitted from the discharge lamp 90 is increased in the thermal load adjustment period HL, and the luminance of the image emitted from the projector 500 is increased. However, as described above, according to the present embodiment, since the thermal load adjustment period HL is provided in the rising period RP, the influence of the luminance change on the user can be reduced.

Table 3 shows an example in which the drive power Wd in the thermal load adjustment period HL is adjusted according to the lamp voltage Vla. Table 3 shows a case where the limited current value Ir in the thermal load adjustment period HL is constant regardless of the lamp voltage Vla.

In the above description, three types of AC periods having different frequencies f are shown as the AC period AC of the drive current I in the thermal load adjustment period HL. However, the present invention is not limited to this. The number of AC periods with different frequencies f may be two, or four or more. In the present embodiment, the drive current I in the thermal load adjustment period HL may be an alternating current having one frequency f.

Second Embodiment
The second embodiment differs from the first embodiment in the waveform of the drive current I in the thermal load adjustment period HL. In addition, about the structure similar to the said embodiment, description may be abbreviate | omitted by attaching | subjecting the same code | symbol suitably.

FIG. 11 is a graph showing an example of the drive current I in the thermal load adjustment period HL of the present embodiment. In FIG. 11, the vertical axis indicates the drive current I, and the horizontal axis indicates time T. The drive current I is shown as positive when it is in the first polarity state and negative when it is in the second polarity state.

As shown in FIG. 11, in this embodiment, the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL includes a DC period DC in which a DC current is supplied to the discharge lamp 90, and a discharge lamp 9.
Alternating periods AC4 during which alternating current is supplied to zero.

The direct current period DC is a period during which direct current is supplied to the discharge lamp 90. The direct current period DC includes a first direct current period DC1 and a second direct current period DC2. The first DC period DC1 is the discharge lamp 9
This is a period during which 0 direct current of the first polarity is supplied. In the first DC period DC1 shown in FIG. 11, the value of the drive current I supplied to the discharge lamp 90 is constant at Im1. The second DC period DC2 is a period in which a DC current having a second polarity opposite to the first polarity is supplied to the discharge lamp 90.
In the second DC period DC2 shown in FIG. 11, the value of the drive current I supplied to the discharge lamp 90 is constant at −Im1.

The first DC period DC1 and the second DC period DC2 are alternately provided with the AC period AC4 interposed therebetween. The length td1 of the first DC period DC1 and the length td2 of the second DC period DC2 are, for example, the same. Note that the length td1 of the first DC period DC1 and the length td2 of the second DC period DC2 may be different from each other.

The AC period AC4 is a period in which an AC current having one type of frequency f4 is supplied to the discharge lamp 90. The length ta4 of the AC period AC4 may be longer, shorter, or the same as the length of the DC period DC. Other configurations of the AC period AC4 are the same as the configurations of the first AC period AC1 to the third AC period AC3 of the first embodiment.

In the present embodiment, the control unit 40 increases the thermal load in the thermal load adjustment period HL by increasing the length of the direct current period DC. More specifically, the control unit 40 performs the first DC period D
By increasing the length td1 of C1 and the length td2 of the second DC period DC2, the thermal load in the thermal load adjustment period HL is increased. That is, when the lamp voltage Vla detected by the voltage detector 64 is smaller than the first voltage Vla1, the controller 40 determines the length of the DC period DC in the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL. This is made larger than the length of the direct current period DC in the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL when the lamp voltage Vla is equal to or higher than the first voltage Vla1.

In the present embodiment, the control unit 40 determines the frequency f of the alternating current in the AC period AC4.
By making 4 low, the thermal load in the thermal load adjustment period HL is increased. That is, in this embodiment, the control unit 40 increases the thermal load in the thermal load adjustment period HL by increasing the length of the DC period DC and decreasing the frequency f4 of the AC current in the AC period AC4. Table 4 shows an example of the length of the direct current period DC for each lamp voltage Vla and the frequency f4 of the alternating current in the alternating current period AC4.

In Table 4, the length ta4 of the AC period AC4 is shown as the number of cycles of the AC period AC4. In Table 4, the length ta4 of the AC period AC4 is constant regardless of the lamp voltage Vla. In Table 4, the length td1 of the first DC period DC1 is shown, but the length td2 of the second DC period DC2 is also set in the same manner as the length td1 of the first DC period DC1.

In Table 4, the length td1 of the first DC period DC1 is 0 ms (milliseconds) indicates that the first DC period DC1 is not provided. In the example of Table 4, when the lamp voltage Vla is equal to or higher than the first voltage Vla1 (60V), the length td1 of the first DC period DC1 is 0 ms (
Milliseconds). That is, Table 4 shows that the drive current I in the thermal load adjustment period HL is composed of only the AC period AC4 when the thermal load in the thermal load adjustment period HL is set to a predetermined magnitude, and the lamp voltage Vla is the first voltage. 11 shows a case where the waveform shown in FIG. 11 is obtained when Vla1 becomes smaller than Vla1.

According to the present embodiment, the direct current period DC and the alternating current period AC4 are alternately provided in the thermal load adjustment period HL. Therefore, while the degree of melting of the protrusions 552p and 562p can be increased by the direct current period DC, the protrusions 552p and 562p can be grown by the alternating current period AC4. Thereby, even when the thermal load in the thermal load adjustment period HL is increased, the lengths of the protrusions 552p and 562p can be easily adjusted so that the protrusions 552p and 562p are not shortened and the distance between the electrodes is not excessively increased. .

Further, according to the present embodiment, the control unit 40 increases the length of the direct current period DC,
The heat load in the heat load adjustment period HL is increased. The thermal load applied to the first electrode 92 and the second electrode 93 in the direct current period DC is larger than the thermal load applied to the first electrode 92 and the second electrode 93 in the alternating current period AC4. Therefore, it is easy to increase the thermal load in the thermal load adjustment period HL, and it is easier to suppress the interelectrode distance from becoming too small.

Further, according to the present embodiment, the control unit 40 increases the thermal load in the thermal load adjustment period HL by reducing the frequency f4 of the alternating current in the AC period AC4. Therefore, both the heat loads applied to the first electrode 92 and the second electrode 93 can be increased.

Further, according to the present embodiment, the first direct current period DC1 and the second direct current period DC2 in which the polarity of the drive current I is opposite are alternately provided with the alternating current period AC4 interposed therebetween. Therefore, the first electrode 9
The heat load can be applied to the second electrode 93 and the second electrode 93 in a well-balanced manner. Thereby, both the protrusion 552p of the first electrode 92 and the protrusion 562p of the second electrode 93 can be easily formed into a suitable shape.

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

In the present embodiment, the control unit 40 may increase the thermal load in the thermal load adjustment period HL by reducing the length ta4 of the AC period AC4. That is, the control unit 40
When the lamp voltage Vla detected by the voltage detector 64 is smaller than the first voltage Vla1, the AC period A in the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL
The length ta4 of C4 is made smaller than the length ta4 of the AC period AC4 in the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL when the lamp voltage Vla is equal to or higher than the first voltage Vla1. According to this configuration, the interval at which the direct current period DC is provided can be reduced, and the first
It is easy to increase the thermal load applied to the electrode 92 and the second electrode 93.

An example of adjusting the length ta1 of the AC period AC4 is shown in Table 5. In Table 5,
The length ta1 of the AC period AC4 is shown as the number of cycles of the AC period AC4. In the example of Table 5, the frequency f4 of the AC period AC4 is constant. In the example of Table 5, the length of the direct current period DC is adjusted as in the example shown in Table 4.

<Third Embodiment>
The third embodiment differs from the second embodiment in that a mixing period is provided. In addition, about the structure similar to the said embodiment, description may be abbreviate | omitted by attaching | subjecting the same code | symbol suitably.

FIG. 12 is a graph showing an example of the drive current I in the thermal load adjustment period HL of the present embodiment. In FIG. 12, the vertical axis represents the drive current I, and the horizontal axis represents time T. The drive current I is shown as positive when it is in the first polarity state and negative when it is in the second polarity state.

As shown in FIG. 12, in the present embodiment, the drive current I supplied to the discharge lamp 90 in the thermal load adjustment period HL has a first mixing period MP1 and a second mixing period MP2. The first mixing period MP1 is a period having alternating first DC periods DC1 and AC periods AC4. The number of first DC periods DC1 and the number of AC periods AC4 included in the first mixing period MP1 may be the same or different. In the present embodiment, the number of first DC periods DC1 and the number of AC periods AC4 included in the first mixed period MP1 are the same, and the unit period in which the AC period AC4 and the first DC period DC1 are consecutive in this order. However, a plurality of first mixing periods MP1 are continuously formed.

The second mixing period MP2 is a period having the second DC period DC2 and the AC period AC4 alternately. The number of second DC periods DC2 and the number of AC periods AC4 included in the second mixing period MP2 may be the same or different. In the present embodiment, the second mixing period M
The number of second direct current periods DC2 and the number of alternating current periods AC4 included in P2 are the same, and a plurality of unit periods in which the alternating current period AC4 and the second direct current period DC2 are consecutive in this order are continuously mixed in the second mixed period. MP2 is configured.

The number of first DC periods DC1 included in the first mixing period MP1 and the number of second DC periods DC2 included in the second mixing period MP2 may be the same or different. In the present embodiment, the number of first DC periods DC1 included in the first mixing period MP1 and the number of second DC periods DC2 included in the second mixing period MP2 are, for example, the same.

In the present embodiment, the control unit 40 includes a first DC period DC1 included in the first mixing period MP1.
Is increased, the thermal load in the thermal load adjustment period HL is increased. That is, when the lamp voltage Vla detected by the voltage detector 64 is smaller than the first voltage Vla1, the controller 40 detects the first mixing period MP1 in the driving current I supplied to the discharge lamp 90 in the thermal load adjustment period HL. The number of first DC periods DC1 included in the driving current I supplied to the discharge lamp 90 in the thermal load adjustment period HL when the lamp voltage Vla is equal to or higher than the first voltage Vla1.
Is greater than the number of first DC periods DC1 included in the first mixing period MP1. Thereby, the heat load applied to the first electrode 92 can be increased. In the present embodiment, the control unit 40 increases the thermal load in the thermal load adjustment period HL by increasing the number of second DC periods DC2 included in the second mixing period MP2. Thereby, the heat load applied to the second electrode 93 can be increased.

The first mixing period MP without changing the length of each period included in the first mixing period MP1
When the number of first DC periods DC1 included in 1 is increased, the length tm1 of the first mixing period MP1
Will grow. Without changing the length of each period included in the second mixed period MP2, the second
When increasing the number of second DC periods DC2 included in the mixing period MP2, the second mixing period MP2
The length tm2 becomes larger.

Table 6 shows an example of the number of first DC periods DC1 included in the first mixing period MP1 for each lamp voltage Vla. In Table 6, in the heat load adjustment period HL, the length of the direct current period DC,
The length ta4 of the AC period AC4 and the frequency f4 of the AC period AC4 are determined by the lamp voltage Vla.
It shows an example of the case where it is constant regardless.

According to the present embodiment, in the first mixing period MP1, the first DC period DC1 in which the first polarity DC current is supplied to the discharge lamp 90 is continuously provided across the AC period AC4. Therefore, in the first mixing period MP1, the temperature of the first electrode 92 can be relatively high, and the protrusion 552p of the first electrode 92 can be more easily melted. According to the present embodiment, the control unit 40 increases the number of first DC periods DC1 included in the first mixing period MP1,
The heat load in the heat load adjustment period HL is increased. Therefore, it is easy to increase the thermal load in the thermal load adjustment period HL, and it is easier to suppress the interelectrode distance from becoming too small.
The same applies to the second mixing period MP2 except that the target electrode is the second electrode 93.

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

In the present embodiment, when the detected lamp voltage Vla is smaller than the first voltage Vla1, the control unit 40 adjusts the thermal load based on the driving power Wd supplied to the discharge lamp 90 in the steady lighting driving executed last time. The heat load in the period HL may be adjusted. According to this configuration, it is possible to appropriately apply a heat load to the first electrode 92 and the second electrode 93 according to the thickness of the protrusions 552p and 562p formed in the steady lighting drive executed last time.

In this configuration, when the detected lamp voltage Vla is smaller than the first voltage Vla1, the control unit 40 adjusts the thermal load as the drive power Wd supplied to the discharge lamp 90 in the previously performed steady lighting drive decreases. The heat load in the period HL is reduced.

As the driving power Wd in the steady lighting driving is smaller, the formed protrusions 552p and 562p are formed.
Tends to get thinner. Therefore, when the lamp voltage Vla is lower than the first voltage Vla1, if the thermal load in the thermal load adjustment period HL is excessively increased, the protrusions 552p and 562p may be melted and disappear. Thereby, the illuminance reduction and flicker of the projector 500 may occur.

On the other hand, according to this configuration, the driving power Wd in the steady lighting driving executed last time
Is smaller, the thermal load in the thermal load adjustment period HL when the lamp voltage Vla is smaller than the first voltage Vla1 can be reduced. Therefore, it is possible to suppress the protrusions 552p and 562p from being excessively melted, and to suppress a decrease in illuminance and occurrence of flicker of the projector 500.

Table 7 shows an example of the number of first DC periods DC1 included in the first mixed period MP1 for each drive power Wd in the steady lighting drive executed last time. In Table 7, the first DC period DC1
This is the same for the number of second DC periods DC2. In Table 7, the number of first DC periods DC1 being 0 indicates that the first DC period DC1 is not provided.

In this configuration, when the driving power Wd in the steady lighting driving executed last time is too small, the temperature in the discharge lamp 90 becomes relatively low, and the mercury Hg enclosed in the discharge lamp 90
May agglomerate. When mercury Hg aggregates, the lamp voltage Vla decreases. for that reason,
In such a case, it is preferable to determine the magnitude of the thermal load in the thermal load adjustment period HL in consideration of the decrease in the lamp voltage Vla due to the aggregation of mercury Hg.

In the present embodiment, the control unit 40 increases the thermal load in the previous thermal load adjustment period HL, and if the lamp voltage Vla detected this time is smaller than the first voltage Vla1, The heat load in the heat load adjustment period HL is the previous heat load adjustment period HL.
It may be larger than the heat load increased in step (b). According to this configuration, once the thermal load in the thermal load adjustment period HL is increased, the lamp voltage Vla does not become equal to or higher than the first voltage Vla1 (or even once temporarily exceeds the first voltage Vla1) 1 voltage Vla
In the next thermal load adjustment period HL, a larger thermal load can be applied to the first electrode 92 and the second electrode 93. Therefore, the magnitude of the thermal load in the thermal load adjustment period HL can be adjusted appropriately, and the interelectrode distance can be further suppressed from becoming too small.

Specifically, after determining that the lamp voltage Vla is smaller than the first voltage Vla1, the control unit 40 refers to the storage unit 44 and increases the thermal load in the previous thermal load adjustment period HL to be larger than the normal size. Determine whether or not. Then, if the thermal load has been larger than a predetermined size in the previous thermal load adjustment period HL, the thermal load in the current thermal load adjustment period HL is set larger.

The controller 40 increases the size of the heat load in the heat load adjustment period HL as the heat load adjustment period HL in which the heat load is larger than a predetermined size is continuously provided. Here, the measurement part 45 measures the continuous frequency | count of the thermal load adjustment period HL which made the thermal load larger than predetermined magnitude | size. That is, the measuring unit 45 measures the number of consecutive thermal load adjustment periods HL in which the thermal load is greater than a predetermined magnitude while the voltage detection unit 64 does not detect the lamp voltage Vla equal to or higher than the first voltage Vla1. The number of consecutive times measured by the measuring unit 45 is the storage unit 44.
Is remembered. The control unit 40 refers to the number of continuous times stored in the storage unit 44 and sets the size of the thermal load in the thermal load adjustment period HL.

Table 8 shows an example of the number of first DC periods DC1 included in the first mixing period MP1 with respect to the continuous number of times of the thermal load adjustment period HL in which the thermal load is increased. Table 8 shows an example up to the case where the thermal load adjustment period HL in which the thermal load is larger than a predetermined size is provided ten times continuously.

When the measurement unit 45 detects that the thermal load in the thermal load adjustment period HL has a predetermined magnitude, that is, the lamp voltage Vla detected by the voltage detection unit 64 is the first voltage Vl.
In the case of a1 or more, the number of continuous thermal load adjustment periods HL executed with the thermal load larger than a predetermined size is reset to 0 and stored in the storage unit 44.

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

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

In addition, the configurations described in the above embodiments can be combined with each other within a consistent range. In particular, the control unit may adjust the thermal load in the thermal load adjustment period HL by appropriately combining a plurality of parameters described in the above-described embodiments and adjusting one or more parameters. .

DESCRIPTION OF SYMBOLS 10 ... Discharge lamp lighting device (discharge lamp drive device), 40 ... Control part, 64 ... Voltage detection part, 90 ...
Discharge lamp, 92 ... first electrode, 93 ... second electrode, 200 ... light source device, 230 ... discharge lamp driving unit,
330R, 330G, 330B ... Liquid crystal light valve (light modulation device), 350 ... Projection optical system, 500 ... Projector, 502, 512R, 512G, 512B ... Image signal, AC4
... AC period, DC ... DC period, DC1 ... first DC period, DC2 ... second DC period, f, f1
, F2, f3, f4 ... frequency, HL ... thermal load adjustment period, I ... drive current, MP1 ... first mixing period, RP ... rising period, RP2 ... rising period, RP3 ... constant current period, Vla ... lamp voltage (
Voltage between electrodes), Vla1 ... first voltage, Vla2 ... second voltage, Wd ... drive power

Claims (20)

A discharge lamp driving unit for supplying a driving current to a discharge lamp having a first electrode and a second electrode;
A control unit for controlling the discharge lamp driving unit;
A voltage detector for detecting a voltage between the electrodes of the discharge lamp;
With
The control unit is configured such that a thermal load applied to the first electrode and the second electrode is applied to the electrode during at least a part of a start-up period from when the discharge lamp starts lighting until steady lighting driving is performed. Controlling the discharge lamp drive unit so as to provide a thermal load adjustment period that is adjusted according to the voltage between,
When the inter-electrode voltage detected by the voltage detection unit is smaller than the first voltage, the control unit determines the thermal load during the thermal load adjustment period, and the inter-electrode voltage is equal to or higher than the first voltage. The discharge lamp driving device characterized in that it is larger than the thermal load in the thermal load adjustment period. When the detected interelectrode voltage is smaller than the first voltage, the control unit increases the thermal load in the thermal load adjustment period as the detected interelectrode voltage is smaller.
The discharge lamp driving device according to claim 1. The startup period is
A rising period during which the value of the drive current supplied to the discharge lamp increases;
A constant current period that is provided later in time than the rising period, and the value of the driving current supplied to the discharge lamp is maintained constant;
Have
The discharge lamp driving device according to claim 1, wherein the thermal load adjustment period is provided in at least a part of the constant current period. The said control part adjusts the said heat load in the said heat load adjustment period based on the said voltage between the electrodes detected in the said steady lighting drive performed last time. Discharge lamp drive device. The discharge lamp drive according to any one of claims 1 to 3, wherein the control unit adjusts the thermal load in the thermal load adjustment period based on the inter-electrode voltage detected in the rising period. apparatus. When the detected voltage between the electrodes is smaller than the first voltage, the control unit determines whether or not the thermal load adjustment period is based on the driving power supplied to the discharge lamp in the steady lighting driving executed last time. The discharge lamp drive device according to any one of claims 1 to 5, wherein the heat load is adjusted. When the detected voltage between the electrodes is smaller than the first voltage, the control unit reduces the thermal load adjustment period as the driving power supplied to the discharge lamp in the steady lighting driving executed last time is smaller. The discharge lamp driving device according to claim 6, wherein the heat load in the lamp is reduced. The said control part makes small the said thermal load in the said thermal load adjustment period, when the said voltage between electrodes detected in the said thermal load adjustment period is more than 2nd voltage larger than the said 1st voltage. 8. The discharge lamp driving device according to any one of items 1 to 7. The control unit is a case where the thermal load in the previous thermal load adjustment period is increased, and when the inter-electrode voltage detected this time is smaller than the first voltage, the current thermal load adjustment period. The discharge lamp driving device according to any one of claims 1 to 8, wherein the thermal load in is made larger than the thermal load increased in the previous thermal load adjustment period. The drive current supplied to the discharge lamp in the thermal load adjustment period is an alternating current,
The discharge lamp driving device according to any one of claims 1 to 9, wherein the control unit increases the thermal load in the thermal load adjustment period by lowering a frequency of the alternating current. 10. The driving current according to claim 1, wherein the driving current in the thermal load adjustment period alternately includes a direct current period in which a direct current is supplied to the discharge lamp and an alternating current period in which an alternating current is supplied to the discharge lamp. The discharge lamp driving device according to any one of claims. The discharge lamp driving device according to claim 11, wherein the control unit increases the thermal load in the thermal load adjustment period by increasing the length of the direct current period. The discharge lamp driving device according to claim 11 or 12, wherein the control unit increases the thermal load in the thermal load adjustment period by lowering a frequency of the alternating current in the alternating period. The discharge lamp driving device according to any one of claims 11 to 13, wherein the control unit increases the thermal load in the thermal load adjustment period by reducing the length of the AC period. The DC period includes a first DC period in which a first polarity DC current is supplied to the discharge lamp, and a second DC period in which a second polarity DC current opposite to the first polarity is supplied to the discharge lamp. And including
The drive current has a first mixing period having the first DC period and the AC period alternately,
The control unit increases the number of the first DC periods included in the first mixing period,
The discharge lamp drive device according to any one of claims 11 to 14, wherein the thermal load in the thermal load adjustment period is increased. The discharge lamp driving device according to any one of claims 1 to 15, wherein the control unit increases the thermal load during the thermal load adjustment period by increasing the driving current. The discharge lamp drive device according to any one of claims 1 to 16, wherein the control unit increases the thermal load in the thermal load adjustment period by increasing drive power supplied to the discharge lamp. . A discharge lamp that emits light;
A discharge lamp driving device according to any one of claims 1 to 17,
A light source device comprising: The light source device according to claim 18;
A light modulation device that modulates light emitted from the light source device according to an image signal;
A projection optical system that projects the light modulated by the light modulation device;
A projector comprising: A discharge lamp driving method for driving a discharge lamp by supplying a driving current to a discharge lamp having a first electrode and a second electrode,
The thermal load applied to the first electrode and the second electrode during at least a part of the start-up period from when the discharge lamp starts lighting to when steady lighting driving is performed is the interelectrode voltage of the discharge lamp. A thermal load adjustment period that is adjusted according to
When the detected inter-electrode voltage is smaller than the first voltage, the thermal load in the thermal load adjustment period is greater than the thermal load in the thermal load adjustment period when the inter-electrode voltage is greater than or equal to the first voltage. A method for driving a discharge lamp, wherein

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