JP2013030298A - Light source apparatus, discharge lamp drive, and projector - Google Patents

Abstract

To provide a light source device, a discharge lamp driving method, and a projector capable of suppressing the blackening of a discharge lamp, maintaining a distance between electrodes at a constant distance, and driving the discharge lamp.
A light source device includes a discharge lamp, a drive device that supplies a drive current to a pair of electrodes and a distance between electrodes that detects the distance between the pair of electrodes. The drive device 200 generates an alternating current having a frequency of 1 kHz to 10 GHz, and the first section and the second section having an amplitude smaller than that of the first section are alternately repeated. As described above, the drive current obtained by amplitude-modulating the alternating current can be generated, and the modulation frequency of the amplitude modulation is set to 10 Hz or more and 1 kHz or less, and the modulation frequency is changed according to the detection result of the interelectrode distance detection unit. Or stop amplitude modulation.
[Selection] Figure 1

Description

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

As a light source of a projector, a discharge lamp (discharge lamp) such as a high-pressure mercury lamp or a metal halide lamp is used.
Such a discharge lamp is driven by, for example, a driving method that supplies a high-frequency alternating current as a driving current (see, for example, Patent Document 1). According to this driving method, discharge stability can be obtained, blackening and devitrification of the discharge lamp body can be prevented, and a reduction in the life of the discharge lamp can be suppressed.

  However, when the discharge lamp is lit, arc discharge is generated between the pair of electrodes, and the electrodes are at a high temperature, so that the electrodes are melted and the space between the electrodes is expanded. For example, in projector applications, in order to improve the light utilization efficiency, it is preferable to maintain a narrow state between the electrodes and reduce the size of light emission. The efficiency is lowered, which is not preferable. In addition, the change between the electrodes changes the impedance between the electrodes. Therefore, even if the discharge lamp can be lit efficiently at the beginning of lighting, impedance mismatch occurs over time, and reactive power is generated. There is a problem that the efficiency increases and the efficiency decreases.

On the other hand, there is also a driving method in which an alternating current (direct current alternating current) having a rectangular waveform at a low frequency is supplied as a driving current. According to this driving method, when the discharge lamp is lit, a protrusion is formed at the tip of the pair of electrodes, so that the gap between the electrodes can be kept narrow for a predetermined period after lighting. it can.
However, there is a problem that the discharge lamp main body is blackened, devitrified, etc., and the life of the discharge lamp is reduced. In addition, when a predetermined period is exceeded after lighting, there is a problem that the protrusion formed at the tip of the electrode becomes small and the space between the electrodes spreads.

JP2007-115534A

  An object of the present invention is to provide a light source device, a discharge lamp driving method, and a projector capable of suppressing the blackening of a discharge lamp, maintaining a distance between electrodes at a constant distance, and driving the discharge lamp. .

Such an object is achieved by the present invention described below.
A light source device of the present invention includes a light emitting container including a hollow portion in which a discharge medium is sealed, a discharge lamp having a pair of electrodes disposed so that the end portions face each other in the hollow portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The modulation frequency of the amplitude modulation is set to 10 Hz or more and 1 kHz or less,
The modulation frequency of the amplitude modulation is changed or the amplitude modulation is stopped according to a detection result of the inter-electrode distance detection unit.
As a result, blackening of the discharge lamp can be suppressed, the distance between the electrodes can be kept constant, and the discharge lamp can be driven.

In the light source device according to the aspect of the invention, the driving device may include a first driving condition in which a modulation frequency of the amplitude modulation is greater than 10 Hz and equal to or less than 1 kHz according to a detection result of the inter-electrode distance detection unit, and the amplitude modulation. It is preferable to select one of a second driving condition for making the modulation frequency of 1 kHz larger than 1 kHz or to stop the amplitude modulation to supply the driving current to the pair of electrodes.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

In the light source device according to the aspect of the invention, the driving device may include a first driving condition in which a modulation frequency of the amplitude modulation is greater than 10 Hz and equal to or less than 1 kHz according to a detection result of the inter-electrode distance detection unit, and the amplitude modulation. Either the second drive condition for increasing the modulation frequency of 1 kHz or stopping the amplitude modulation, and the third drive condition for reducing the modulation frequency of the amplitude modulation lower than the first drive condition. Preferably, the driving current is supplied to the pair of electrodes.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

A light source device of the present invention includes a light emitting container including a hollow portion in which a discharge medium is sealed, a discharge lamp having a pair of electrodes disposed so that the end portions face each other in the hollow portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The drive current is such that b / a is 0% or more, where a is the average amplitude of the alternating current in the first section and b is the average amplitude of the alternating current in the second section. % Or less,
The b / a in the amplitude modulation is changed or the amplitude modulation is stopped according to the detection result of the inter-electrode distance detector.
As a result, blackening of the discharge lamp can be suppressed, the distance between the electrodes can be kept constant, and the discharge lamp can be driven.

In the light source device of the present invention, the driving device has a first driving condition in which b / a in the amplitude modulation is set to be larger than 0% and not larger than 90% according to the detection result of the inter-electrode distance detecting unit; Preferably, the driving current is supplied to the pair of electrodes by selecting either b / a larger than 90% or the second driving condition for stopping the amplitude modulation.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

In the light source device of the present invention, the driving device has a first driving condition in which b / a in the amplitude modulation is set to be larger than 0% and not larger than 90% according to the detection result of the inter-electrode distance detecting unit; A second driving condition for setting b / a in the amplitude modulation to be larger than 90% or stopping the amplitude modulation; and a third driving condition for setting b / a in the amplitude modulation to be smaller than the first driving condition. It is preferable to select one of driving conditions and supply a driving current to the pair of electrodes.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

A light source device of the present invention includes a light emitting container including a hollow portion in which a discharge medium is sealed, a discharge lamp having a pair of electrodes disposed so that the end portions face each other in the hollow portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The drive current has a B / A of 10% or more, where A is a total period of one of the first sections and one of the second sections and B is a period of the one first section. Set to 90% or less,
The B / A in the amplitude modulation is changed or the amplitude modulation is stopped according to the detection result of the inter-electrode distance detection unit.
As a result, blackening of the discharge lamp can be suppressed, the distance between the electrodes can be kept constant, and the discharge lamp can be driven.

In the light source device according to the aspect of the invention, the driving device may include a first driving condition that sets B / A in the amplitude modulation to 10% or more and 90% or less according to a detection result of the inter-electrode distance detection unit, and the amplitude. The B / A in modulation is made smaller than 10%, or B / A is made larger than 90% or the second driving condition for stopping the amplitude modulation is selected, and the pair of It is preferable to supply a driving current to the electrodes.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

In the light source device according to the aspect of the invention, the driving device may include a first driving condition that sets B / A in the amplitude modulation to 10% or more and 90% or less according to a detection result of the inter-electrode distance detection unit, and the amplitude. B / A in modulation is made smaller than 10% or B / A is made larger than 90% or the amplitude modulation is stopped, and B / A in the amplitude modulation is changed to the first. Preferably, the driving current is supplied to the pair of electrodes by selecting any one of the third driving conditions that are closer to 50% than the first driving condition.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

In the light source device according to the aspect of the invention, it is preferable that the inter-electrode distance detector detects a reflected power with respect to an input power to the discharge lamp.
Thereby, when the frequency of a drive current is comparatively high, for example, when it is 1 MHz or more, the distance between electrodes can be detected indirectly.
In the light source device of the present invention, it is preferable that the driving device selects the first driving condition at the start of driving of the discharge lamp.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

In the light source device of the present invention, the driving device selects the second driving condition when the ratio of the reflected power to the input power to the discharge lamp or the value of the reflected power is larger than a predetermined value. It is preferable.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.
In the light source device of the present invention, the drive device has a ratio of the reflected power to the input power to the discharge lamp or the value of the reflected power becomes a reference value set smaller than the predetermined value. It is preferable to select the first driving condition.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

In the light source device according to the aspect of the invention, it is preferable that the inter-electrode distance detector detects a voltage between a pair of electrodes of the discharge lamp.
Thereby, when the frequency of a drive current is comparatively low, for example, when it is less than 1 MHz, the distance between electrodes can be detected indirectly.
In the light source device of the present invention, it is preferable that the driving device selects the first driving condition at the start of driving of the discharge lamp.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

In the light source device of the present invention, it is preferable that the driving device selects the second driving condition when a voltage between the pair of electrodes is smaller than a first value.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.
In the light source device of the present invention, the driving device may select the third driving condition when a voltage between the pair of electrodes is larger than a second value that is larger than the first value. preferable.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

In the light source device of the present invention, the driving device selects the second driving condition when the voltage between the pair of electrodes is smaller than a first value, and the voltage between the pair of electrodes is The third drive condition is selected when the second value is greater than the second value, which is greater than the first value, and the voltage between the pair of electrodes is between the first value and the second value. In the case of an intermediate value, it is preferable to select the first driving condition.
Thereby, the inter-electrode distance can be held at a constant distance more reliably.

In the light source device of the present invention, it is preferable that the amplitude of the alternating current is constant in the first section.
Thereby, a protrusion can be more reliably formed on the electrode.
In the light source device of the present invention, it is preferable that the amplitude of the alternating current is constant in the second section.
Thereby, a protrusion can be more reliably formed on the electrode.

In the light source device of the present invention, the frequency of the alternating current is preferably 1 kHz to 100 kHz, or 3 MHz to 10 GHz.
This can prevent the discharge from becoming unstable due to the acoustic resonance effect.
In the light source device of the present invention, when the discharge lamp is lit by the supply of the driving current, the temperature of the pair of electrodes fluctuates, and a protrusion is formed at the tip of the pair of electrodes. preferable.
Thereby, the distance between electrodes can be kept at a constant distance, and the discharge lamp can be driven efficiently.

A method for driving a discharge lamp according to the present invention is a method for driving a discharge lamp having a light emitting container including a cavity in which a discharge medium is enclosed, and a pair of electrodes whose ends are opposed to each other in the cavity. And
An alternating current having a frequency of 1 kHz to 10 GHz is generated;
The alternating current is amplitude-modulated such that the first interval and the second interval having an amplitude smaller than that of the first interval are alternately repeated, and the modulation frequency is 10 Hz to 1 kHz. Generate
Detecting the distance between the pair of electrodes;
Depending on the detection result of the distance between the electrodes, the drive current is adjusted by changing the modulation frequency of the amplitude modulation or by stopping the amplitude modulation,
The adjusted drive current is supplied to the pair of electrodes.
As a result, blackening of the discharge lamp can be suppressed, the distance between the electrodes can be kept constant, and the discharge lamp can be driven.

A method for driving a discharge lamp according to the present invention is a method for driving a discharge lamp having a light emitting container including a cavity in which a discharge medium is enclosed, and a pair of electrodes whose ends are opposed to each other in the cavity. And
An alternating current having a frequency of 1 kHz to 10 GHz is generated;
The first section and the second section having an amplitude smaller than that of the first section are alternately repeated, and the average value of the amplitude of the alternating current in the first section is a, the second section When the average value of the amplitude of the alternating current in the section is b, the alternating current is amplitude-modulated so that b / a is 0% or more and 90% or less, and a driving current is generated.
Detecting the distance between the pair of electrodes;
Depending on the detection result of the distance between the electrodes, the drive current is adjusted by changing b / a in the amplitude modulation or by stopping the amplitude modulation,
The adjusted drive current is supplied to the pair of electrodes.
As a result, blackening of the discharge lamp can be suppressed, the distance between the electrodes can be kept constant, and the discharge lamp can be driven.

A method for driving a discharge lamp according to the present invention is a method for driving a discharge lamp having a light emitting container including a cavity in which a discharge medium is enclosed, and a pair of electrodes whose ends are opposed to each other in the cavity. And
An alternating current having a frequency of 1 kHz to 10 GHz is generated;
A first section and a second section having an amplitude smaller than that of the first section are alternately repeated, and a total period of one of the first section and one of the second sections is represented by A When the period of the one first section is B, the AC current is amplitude-modulated so that B / A is 10% or more and 90% or less, and a drive current is generated.
Detecting the distance between the pair of electrodes;
Depending on the detection result of the distance between the electrodes, the drive current is adjusted by changing B / A in the amplitude modulation or by stopping the amplitude modulation,
The adjusted drive current is supplied to the pair of electrodes.
As a result, blackening of the discharge lamp can be suppressed, the distance between the electrodes can be kept constant, and the discharge lamp can be driven.

The projector of the present invention includes a light source device that emits light,
A modulation device that modulates light emitted from the light source device based on image information;
A projection device that projects the light modulated by the modulation device,
The light source device includes a light emitting container including a cavity portion in which a discharge medium is enclosed, a discharge lamp having a pair of electrodes whose end portions are opposed to each other in the cavity portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The modulation frequency of the amplitude modulation is set to 10 Hz or more and 1 kHz or less,
The modulation frequency of the amplitude modulation is changed or the amplitude modulation is stopped according to a detection result of the inter-electrode distance detection unit.
This suppresses blackening of the discharge lamp, keeps the distance between the electrodes constant, and can drive the discharge lamp, thereby reducing power consumption and displaying a stable and good image. can do.

The projector of the present invention includes a light source device that emits light,
A modulation device that modulates light emitted from the light source device based on image information;
A projection device that projects the light modulated by the modulation device,
The light source device includes a light emitting container including a cavity portion in which a discharge medium is enclosed, a discharge lamp having a pair of electrodes whose end portions are opposed to each other in the cavity portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The drive current is such that b / a is 0% or more, where a is the average amplitude of the alternating current in the first section and b is the average amplitude of the alternating current in the second section. % Or less,
The b / a in the amplitude modulation is changed or the amplitude modulation is stopped according to the detection result of the inter-electrode distance detector.
This suppresses blackening of the discharge lamp, keeps the distance between the electrodes constant, and can drive the discharge lamp, thereby reducing power consumption and displaying a stable and good image. can do.

The projector of the present invention includes a light source device that emits light,
A modulation device that modulates light emitted from the light source device based on image information;
A projection device that projects the light modulated by the modulation device,
The light source device includes a light emitting container including a cavity portion in which a discharge medium is enclosed, a discharge lamp having a pair of electrodes whose end portions are opposed to each other in the cavity portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The drive current has a B / A of 10% or more, where A is a total period of one of the first sections and one of the second sections and B is a period of the one first section. Set to 90% or less,
The B / A in the amplitude modulation is changed or the amplitude modulation is stopped according to the detection result of the inter-electrode distance detection unit.
This suppresses blackening of the discharge lamp, keeps the distance between the electrodes constant, and can drive the discharge lamp, thereby reducing power consumption and displaying a stable and good image. can do.

It is sectional drawing (a block diagram is also included) which shows 1st Embodiment of the light source device of this invention. It is sectional drawing which shows the discharge lamp of the light source device shown in FIG. It is a block diagram which shows the light source device shown in FIG. It is a figure which shows the alternating current and drive current which are produced | generated with the discharge lamp drive device of the light source device shown in FIG. It is a flowchart which shows the control operation of the light source device shown in FIG. It is a flowchart which shows the control action in 2nd Embodiment of the light source device of this invention. It is a figure which shows the envelope in the structural example of a drive current. It is a figure which shows the envelope in the structural example of a drive current. It is a figure which shows typically embodiment of the projector of this invention. It is a graph which shows the relationship between the distance between electrodes in the light source device shown in FIG. 1, and a standing wave ratio. It is a graph which shows the relationship between the distance between electrodes and the voltage between electrodes in 2nd Embodiment of the light source device of this invention.

Hereinafter, a light source device, a discharge lamp driving method, and a projector of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<First Embodiment of Light Source Device>
FIG. 1 is a cross-sectional view (including a block diagram) showing a first embodiment of the light source device of the present invention, FIG. 2 is a cross-sectional view showing a discharge lamp of the light source device shown in FIG. 1, and FIG. 4 is a block diagram showing the light source device shown in FIG. 4, FIG. 4 is a diagram showing alternating current and drive current generated by the discharge lamp driving device of the light source device shown in FIG. 1, and FIG. 5 is a control operation of the light source device shown in FIG. FIG. 10 is a graph showing the relationship between the distance between the electrodes and the standing wave ratio in the light source device shown in FIG. In FIG. 2, the sub-reflecting mirror is not shown. Further, the graph of FIG. 10 is not exact, and shows a tendency for the standing wave ratio to increase or decrease with respect to the distance between the electrodes.

As shown in FIG. 1, the light source device 1 includes a light source unit 110 having a discharge lamp 500, a discharge lamp driving device (driving device) 200 that drives the discharge lamp 500, and a detector (interelectrode distance detection unit) 35. It has. The discharge lamp 500 receives electric power from the discharge lamp driving device 200 to discharge and emit light.
The light source unit 110 includes a discharge lamp 500, a main reflecting mirror 112 having a concave reflecting surface, and a collimating lens 114 that makes emitted light substantially parallel. The main reflecting mirror 112 and the discharge lamp 500 are bonded with an inorganic adhesive 116. Further, the main reflecting mirror 112 has a surface (inner surface) on the discharge lamp 500 side as a reflecting surface, and this reflecting surface forms a spheroidal surface in the illustrated configuration.

Note that the shape of the reflecting surface of the main reflecting mirror 112 is not limited to the above shape, and other examples include a rotating paraboloid. Further, when the reflecting surface of the main reflecting mirror 112 is a rotating paraboloid, the collimating lens 114 can be omitted if the light emitting part of the discharge lamp 500 is arranged at the so-called focal point of the rotating paraboloid.
The discharge lamp 500 includes a discharge lamp main body 510 and a sub-reflecting mirror 520 having a concave reflecting surface. The discharge lamp main body 510 and the sub-reflecting mirror 520 are bonded with an inorganic adhesive 522. Further, in the sub-reflecting mirror 520, the surface (inner surface) on the discharge lamp 500 side is a reflecting surface, and this reflecting surface is a spherical surface in the illustrated configuration.

In the center of the discharge lamp main body 510, a light emitting container including a discharge space (hollow part) 512 hermetically sealed with a discharge medium described later is formed. At least a portion corresponding to the discharge space 512 of the discharge lamp main body 510 has light transmittance. Examples of the constituent material of the discharge lamp main body 510 include glass such as quartz glass and light-transmitting ceramics.
The discharge lamp main body 510 is provided with a pair of electrodes 610 and 710, a pair of conductive connection members 620 and 720, and a pair of electrode terminals 630 and 730. The electrode 610 and the electrode terminal 630 are electrically connected by a connection member 620. Similarly, the electrode 710 and the electrode terminal 730 are electrically connected by a connection member 720.

Each electrode 610, 710 is accommodated in the discharge space 512. In other words, the electrodes 610 and 710 are arranged such that their tip portions are spaced apart from each other by a predetermined distance in the discharge space 512 of the discharge lamp main body 510 and face each other.
The distance between the electrodes, which is the shortest distance between the electrode 610 and the electrode 710, is preferably 1 μm or more and 5 mm or less, and more preferably 500 μm or more and 1.5 mm or less.

  As shown in FIG. 2, the electrode 610 includes a core rod 612, a coil portion 614, and a main body portion 616. The electrode 610 is formed by winding a wire rod of an electrode material (tungsten or the like) around a core rod 612 to form a coil portion 614 before heating and melting the formed coil portion 614 before being enclosed in the discharge lamp main body 510. It is formed by doing. As a result, a body portion 616 having a large heat capacity is formed on the tip side of the electrode 610. Similarly to the electrode 610, the electrode 710 also includes a core rod 712, a coil portion 714, and a main body portion 716, and is formed in the same manner as the electrode 610.

In the state where the discharge lamp 500 has never been lit, the main body portions 616 and 716 are not formed with protrusions 618 and 718. However, if the discharge lamp 500 is lit even once under the conditions described later, the main body portion Protrusions 618 and 718 are formed at the tips of 616 and 716, respectively. The protrusions 618 and 718 are maintained while the discharge lamp 500 is turned on, and are also maintained after the lamp is turned off.
In addition, as a constituent material of each electrode 610,710, high melting point metal materials, such as tungsten, etc. are mentioned, for example.

Further, a discharge medium is enclosed in the discharge space 512. The discharge medium includes, for example, a discharge start gas, a gas that contributes to light emission, and the like. Further, the discharge medium may contain other gas.
Examples of the discharge starting gas include noble gases such as neon, argon, and xenon. Examples of the gas that contributes to light emission include mercury, vaporized metal halide, and the like. Examples of the other gas include a gas having a function of preventing blackening. Examples of the gas having a function of preventing blackening include a halogen (for example, bromine), a halogen compound (for example, hydrogen bromide), or a vaporized product thereof.
In addition, the atmospheric pressure in the discharge lamp main body 510 at the time of lighting is preferably 0.1 atm or more and 300 atm or less, and more preferably 50 atm or more and 300 atm or less.

  The electrode terminals 630 and 730 of the discharge lamp 500 are connected to the output terminal side of the discharge lamp driving device 200, respectively. The discharge lamp driving device 200 supplies a driving current (driving power) including a high frequency alternating current (alternating current power) to the discharge lamp 500. In other words, the discharge lamp driving device 200 supplies power to the discharge lamp 500 by supplying the drive current to the electrodes 610 and 710 via the electrode terminals 630 and 730. When the drive current is supplied to the electrodes 610 and 710, arc discharge (arc AR) is generated between the tips of the pair of electrodes 610 and 710 in the discharge space 512. Light (discharge light) generated by the arc discharge is radiated in all directions from the generation position (discharge position) of the arc AR. The sub-reflecting mirror 520 reflects the light emitted in the direction of the one electrode 710 toward the main reflecting mirror 112. In this way, by reflecting the light emitted in the direction of the electrode 710 toward the main reflecting mirror 112, the light emitted in the direction of the electrode 710 can be effectively used. In the present embodiment, the discharge lamp 500 includes the sub-reflecting mirror 520, but the discharge lamp 500 may be configured not to include the sub-reflecting mirror 520.

Next, the discharge lamp driving device 200 and the detector 35 will be described.
As shown in FIG. 3, the discharge lamp driving device 200 includes a high-frequency current generator 31 that generates a high-frequency alternating current, an amplitude modulator (amplitude modulator) 32, an amplifier 33 with a variable amplification factor, and a control. And an apparatus for supplying an amplitude-modulated alternating current to the pair of electrodes 610 and 710 of the discharge lamp 500 as a driving current. The control unit 34 controls the overall operation of the discharge lamp driving device 200 such as the high-frequency current generator 31, the amplitude modulator 32, and the amplifier 33. The detection result of a detector (interelectrode distance detection unit) 35 provided separately on the output side of the discharge lamp driving device 200 (between the discharge lamp 500 and the discharge lamp driving device 200) is sent to the control unit 34. Entered. In the present embodiment, the detector 35 is provided separately from the discharge lamp driving device 200, but may be configured to be incorporated in the discharge lamp driving device 200.

  In the present embodiment, a SWR (Standing Wave Ratio) meter is used as the detector 35. The detector 35 detects the input power input from the discharge lamp driving device 200 to the discharge lamp 500 and the reflected power reflected from the discharge lamp 500 side to the discharge lamp driving device 200 side. The ratio of the reflected power to (the standing wave ratio) is obtained. As will be described later, the detected standing wave ratio is used for driving control of the discharge lamp 500. Instead of the standing wave ratio, the value of the reflected power may be used for driving control of the discharge lamp 500. Here, the standing wave ratio is a value corresponding to the distance between the electrodes. Therefore, the distance between the electrodes is indirectly obtained by obtaining the standing wave ratio.

As shown in FIG. 10, when the interelectrode distance is a predetermined reference value, the reflected power is the same as the input power, and the standing wave ratio is 1.0. As the interelectrode distance increases from this reference value, the reflected power increases and the standing wave ratio increases above 1.0. Similarly, even if the distance between electrodes decreases from the reference value, the reflected power increases and the standing wave ratio increases from 1.0.
In the measurement with the SWR meter, it is unclear whether the distance between the electrodes is larger or smaller than the reference value, that is, whether the protrusions 618 and 718 are larger or smaller. However, in the present embodiment, in the adjustment of the driving condition of the discharge lamp 500, a driving condition in which protrusions 618 and 718 described later are extended as the first condition (first driving condition) of the driving condition of the discharge lamp 500. The initial value of the driving condition of the discharge lamp 500 (driving condition at the start of driving of the discharge lamp 500) is set as the first condition, and the distance between the electrodes is controlled within a range below the reference value. The change in which the standing wave ratio increases means that the distance between the electrodes has changed in a direction that becomes smaller than the reference value.

Moreover, in this embodiment, since reflected power is measured with a SWR meter, it is preferable to apply when the frequency of a drive current is 1 MHz or more.
In this discharge lamp driving device 200, the alternating current shown in FIG. 4A generated by the high-frequency current generator 31 is obtained from the first section 41 and the first section 41 as shown in FIG. 4B. Amplitude modulation is performed by the amplitude modulator 32 so that the second section 42 having a small drive current amplitude is alternately repeated. Then, the alternating current is amplified by the amplifier 33 to generate and output an alternating current that is a driving current for driving the discharge lamp. The drive current output from the discharge lamp driving device 200 is supplied to a pair of electrodes 610 and 710 of the discharge lamp 500.
Thereby, as described above, arc discharge occurs between the tip portions of the pair of electrodes 610 and 710, and the discharge lamp 500 is turned on.

Here, in the light source device 1, the discharge lamp 500 is lit using a driving current under the conditions described later. Therefore, when the discharge lamp 500 is lit, the temperature of the electrodes 610 and 710 varies. The protrusions 618 and 718 are formed at the tips of the electrodes 610 and 710, respectively, and the protrusions 618 and 718 can be maintained.
That is, first, in the first section 41 of the drive current, when the temperature of the electrodes 610 and 710 is increased, a part of the tip of the electrodes 610 and 710 is melted, and the melted electrode material is caused by the surface tension. Collects at the tip of the electrodes 610 and 710 On the other hand, in the second section 42, the temperature of the electrodes 610 and 710 is lowered, so that the molten electrode material is solidified. The protrusions 618 and 718 grow by repeating such a state in which the molten electrode material is collected at the tip portions of the electrodes 610 and 710 and a state in which the molten electrode material is solidified. Then, by performing drive control of the discharge lamp 500 as will be described later, the distance between the electrodes can be maintained at a constant distance, and a state where the distance between the electrodes is narrow can be maintained. Thereby, the discharge lamp 500 can be driven efficiently.

The protrusions 618 and 718 may be formed in advance before the light source device 1 is shipped, or are not formed when the light source device 1 is shipped, and then when the discharge lamp 500 is turned on. It may be formed.
Further, since the drive current includes an alternating current having a high frequency, blackening of the discharge lamp 500 can be suppressed, and the life can be extended.

Here, the rated power of the discharge lamp 500 is appropriately set depending on the application and the like, and is not particularly limited. However, the rated power is preferably 10 W or more and 5 kW or less, and more preferably 100 W or more and 500 W or less.
The frequency of the alternating current is 1 kHz to 10 GHz, preferably 1 kHz to 100 kHz, or 3 MHz to 10 GHz, and more preferably 1 kHz to 20 kHz, or 3 MHz to 3 GHz.

When the electrodes 610 and 710 operate as anodes, the electrode temperature is higher than when they operate as cathodes. By setting the frequency of the alternating current to be equal to or higher than the lower limit value, one cycle of the driving current is obtained. The fluctuation of the electrode temperature inside can be prevented.
However, if the frequency of the alternating current is smaller than the lower limit value, the temperature of the electrodes 610 and 710 fluctuates every cycle of the driving current, which makes it impossible to form and maintain the protrusions, and blackening occurs. May occur. In addition, a cost larger than the upper limit is high.

If the frequency of the alternating current is larger than 20 kHz and smaller than 3 MHz, the discharge becomes unstable due to the acoustic resonance effect depending on other conditions.
The modulation frequency of the drive current, the average value a of the amplitude when the average value of the drive current amplitude in the first section 41 is a, and the average value of the drive current amplitude in the second section 42 is b. The ratio b / a (see FIG. 4) of the average value b of the amplitude, the total period of one first section 41 and one second section 42 is A, and the period of one first section 41 is B And at least one of the ratio B / A (see FIG. 4) of the period A and the period B is defined as follows. In the following, a case where the modulation frequency of drive current, each of b / a and B / A is defined will be described.

First, the modulation frequency of the drive current is 10 Hz to 1 kHz, preferably 25 Hz to 750 Hz, and more preferably 50 Hz to 400 Hz.
If the modulation frequency of the drive current is smaller than the lower limit value, the protrusions extend too much, and if the modulation frequency is larger than the upper limit value, no protrusions are formed. Note that the protrusions 618 and 718 extend as the modulation frequency is lower.

In the present embodiment, the amplitude of the alternating current is constant in each of the first section 41 and the second section 42. Thereby, the protrusions 618 and 718 can be more reliably formed on the electrodes 610 and 710.
As shown in FIG. 4, when the average value of the amplitude of the alternating current in the first section 41 is a and the average value of the amplitude of the alternating current in the second section 42 is b, the amplitude a and the amplitude b The ratio b / a is 0 or more and 90% or less, more preferably 0 or more and 50% or less, and still more preferably 0 or more and 30% or less.

When b / a is larger than the upper limit, the protrusions 618 and 718 are not formed. As b / a is smaller, the protrusions 618 and 718 extend, and when b / a is 0, the protrusions 618 and 718 extend most.
Note that b / a is 0, that is, the drive current may be configured to be intermittently supplied to the electrodes 610 and 710, but when the drive current is continuously supplied to the electrodes 610 and 710, b / a is preferably 1% or more and 50% or less, and more preferably 1% or more and 30% or less.

Further, as shown in FIG. 4, when the total period of the first section 41 and the second section 42 is A and the period of the first section 41 is B, the ratio B / A is 10% or more and 90% or less, preferably 25% or more and 75% or less, and more preferably 45% or more and 55% or less.
When B / A is smaller than the lower limit value or larger than the upper limit value, the protrusions 618 and 718 are not formed. As B / A is closer to 50%, the protrusions 618 and 718 extend, and when B / A is 50%, the protrusions 618 and 718 extend most.

The modulation frequency of the drive current is preferably set according to b / a, the rated power of the discharge lamp 500, and the like. Thereby, the protrusions 618 and 718 can be more reliably formed on the electrodes 610 and 710.
That is, first, when b / a is greater than 75% and 90% or less, the modulation frequency is preferably set as follows according to the rated power.

When the rated power is 100 W or more and less than 150 W, the modulation frequency is preferably 100 Hz or more and 400 Hz or less.
When the rated power is 150 W or more and less than 250 W, the modulation frequency is preferably 100 Hz or more and 300 Hz or less.
When the rated power is 250 W or more and less than 300 W, the modulation frequency is preferably 100 Hz or more and 250 Hz or less.

When the rated power is 300 W or more and less than 400 W, the modulation frequency is preferably 100 Hz or more and 250 Hz or less.
When b / a is greater than 60% and 75% or less, the modulation frequency is preferably set as follows according to the rated power.
When the rated power is 100 W or more and less than 150 W, the modulation frequency is preferably 100 Hz or more and 500 Hz or less.

Moreover, when the rated power is 150 W or more and less than 250 W, the modulation frequency is preferably 100 Hz or more and 400 Hz or less.
When the rated power is 250 W or more and less than 300 W, the modulation frequency is preferably 100 Hz or more and 300 Hz or less.
When the rated power is 300 W or more and less than 400 W, the modulation frequency is preferably 100 Hz or more and 200 Hz or less.

When b / a is greater than 45% and 60% or less, the modulation frequency is preferably set as follows according to the rated power.
When the rated power is 100 W or more and less than 150 W, the modulation frequency is preferably 100 Hz or more and 700 Hz or less.
When the rated power is 150 W or more and less than 250 W, the modulation frequency is preferably 100 Hz or more and 500 Hz or less.
When the rated power is 250 W or more and less than 300 W, the modulation frequency is preferably 100 Hz or more and 400 Hz or less.
When the rated power is 300 W or more and less than 400 W, the modulation frequency is preferably 100 Hz or more and 300 Hz or less.

  In the light source device 1, the detector 35 detects the reflected power and the input power, obtains the ratio of the reflected power to the input power (standing wave ratio), and the detected standing wave ratio is determined by the control unit. 34. The control unit 34 adjusts the driving condition of the discharge lamp 500 according to the detection result of the detector 35, that is, the detected standing wave ratio. In this case, at least one of the modulation frequency, b / a and B / A of the drive current is changed, or amplitude modulation is not performed (amplitude modulation is stopped). In other words, the state in which the amplitude modulation of the driving current is not performed is a state in which an alternating current having a constant amplitude is supplied to the discharge lamp 500 as the driving current. In the following, the modulation frequency, b / a, and B / A will be described one by one. Good.

First, a case will be described in which control is performed such that the modulation frequency in amplitude modulation of the drive current is changed or amplitude modulation is not performed (stopped) in accordance with the detected standing wave ratio.
When the standing wave ratio detected by the detector 35 is input, the control unit 34 sets the modulation frequency in the amplitude modulation of the driving current as the driving condition of the discharge lamp 500 according to the detected standing wave ratio. A first condition (first driving condition) that is greater than 10 Hz and 1 kHz or less, and a second condition (second condition) in which the modulation frequency in amplitude modulation of the drive current is greater than 1 kHz or amplitude modulation is not performed. Drive condition). The first condition is a condition in which the protrusions 618 and 718 extend (a condition in which the protrusion increases, that is, a condition in which the distance between the electrodes decreases), and the second condition is a condition in which the protrusions 618 and 718 do not extend (the protrusion Is a condition in which the distance between the electrodes decreases, that is, a condition in which the distance between the electrodes increases. The same applies to the following.

Next, a description will be given of a case where control is performed such that b / a in amplitude modulation of the drive current is changed or amplitude modulation is not performed (stopped) according to the detected standing wave ratio.
When the standing wave ratio detected by the detector 35 is input, the control unit 34 sets b / a to be larger than 0% as a driving condition of the discharge lamp 500 according to the detected standing wave ratio. Either a first condition (first driving condition) that is 90% or less and a second condition (second driving condition) in which b / a is greater than 90% or amplitude modulation is not performed. Select.

Next, a description will be given of a case where control is performed such that B / A is changed or amplitude modulation is not performed (stopped) according to the detected standing wave ratio.
When the standing wave ratio detected by the detector 35 is input, the control unit 34 sets B / A to 10% or more and 90% as a driving condition of the discharge lamp 500 according to the detected standing wave ratio. A first condition (first driving condition) to be described below, and a second condition (B / A is made smaller than 10% or B / A is made larger than 90% or amplitude modulation is not performed) The second driving condition) is selected.

  In the adjustment of the driving condition of the discharge lamp 500, first, the initial value of the driving condition of the discharge lamp 500 (driving condition at the start of driving of the discharge lamp 500) is set to the first condition described above. Then, as shown by the arrow described as “first condition” in FIG. 10, the protrusions 618 and 718 extend, and the standing wave ratio deviates from the preset allowable range (below the predetermined upper limit value). And the driving condition of the discharge lamp 500 is set to the second condition.

As indicated by the arrow described as “second condition” in FIG. 10, the protrusions 618 and 718 become smaller, and then the standing wave ratio is within the allowable range (more than the predetermined upper limit value). When the reference value set in advance is small, the driving condition of the discharge lamp 500 is set again to the first condition.
Next, a control operation of the discharge lamp driving device 200 of the light source device 1 will be described based on FIG.

First, the initial value of the driving condition of the discharge lamp 500 is set to the first condition (the condition that the protrusion extends, that is, the condition that the distance between the electrodes is reduced), the driving current is supplied to the pair of electrodes 610 and 710, and the discharge lamp 500 is turned on (step S101). Accordingly, the protrusions 618 and 718 become larger.
Next, the reflected power and the input power are detected, and a standing wave ratio that is a ratio of the reflected power to the input power is obtained (step S102). The standing wave ratio is obtained by the detector 35, but is not limited thereto, and may be obtained by the control unit 34, for example.

  Next, it is determined whether or not the detected standing wave ratio is within an allowable range (step S103). Here, the allowable range of the standing wave ratio is set so that the distance between the electrodes is within the allowable range even if the detected standing wave ratio is slightly deviated from the allowable range. The upper limit value of the allowable range of the standing wave ratio is preferably set to a predetermined value within a range of 1.5 to 1.9, for example, 1.7, and preferably 1.2 to 1.25. More preferably, it is set to a predetermined value within the range, for example, 1.22. Note that the standing wave ratio increases from 1.0 regardless of whether the distance between the electrodes increases or decreases from the reference value, so the lower limit value of the allowable range of the standing wave ratio is 1.0.

  If the standing wave ratio is within the allowable range, the process returns to step S102, and step S102 and subsequent steps are executed again. Further, when the standing wave ratio is not within the allowable range, that is, when the standing wave ratio is larger than the upper limit value of the allowable range of the standing wave ratio, the driving condition is set to the second condition (the condition that the protrusion is reduced, that is, the distance between the electrodes). (Condition that increases) (step S104). Thereby, the protrusions 618 and 718 become smaller.

Next, the reflected power and the input power are detected, and the standing wave ratio is obtained (step S105).
Next, it is determined whether or not the detected standing wave ratio is a reference value (step S106). Here, the reference value of the standing wave ratio is preferably set to a predetermined value within a range of 1.0 to 1.1, for example, and a predetermined value within a range of 1.0 to 1.05 More preferably, the value is set.

When the standing wave ratio is not the reference value, that is, when the standing wave ratio is larger than the reference value, the second condition is continued as the driving condition, the process returns to step S105, and step S105 and subsequent steps are executed again. . If the standing wave ratio is the reference value, the drive condition is changed to the first condition (step S108), the process returns to step S102, and step S102 and subsequent steps are executed again. Thereby, the distance between electrodes is kept within an allowable range.
As described above, according to the light source device 1, it is possible to suppress the blackening of the discharge lamp 500 and extend the life. Further, the protrusions 618 and 718 are formed on the electrodes 610 and 710, the distance between the electrodes can be maintained at a constant distance, and the discharge lamp 500 can be driven efficiently.

  In the present embodiment, the initial value of the driving condition of the discharge lamp 500 is set to a driving condition in which the distance between the electrodes becomes small, and the case where the distance between the electrodes becomes too small from the standing wave ratio is detected. Change to a driving condition that increases. Then, it is detected from the standing wave ratio that the distance between the electrodes has increased to a predetermined distance, and the driving condition is returned to the condition where the distance between the electrodes is reduced again. On the other hand, it is also possible to control the expansion / contraction of the inter-electrode distance by a control opposite to this control, as in a modified example described later. That is, first, the initial value of the driving condition of the discharge lamp 500 is set to a driving condition in which the distance between the electrodes is increased, and the case where the distance between the electrodes is excessively increased from the standing wave ratio is detected. Change to the driving conditions. After that, it is detected from the standing wave ratio that the distance between the electrodes is reduced to a predetermined distance, and the driving condition is returned again to increase the distance between the electrodes. Even by such control, it is possible to keep the distance between the electrodes within an allowable range.

<Modification of First Embodiment of Light Source Device>
Hereinafter, modifications of the first embodiment will be described focusing on differences from the first embodiment described above, and descriptions of similar matters will be omitted.
In the light source device 1, in adjusting the driving condition of the discharge lamp 500, first, the initial value of the driving condition of the discharge lamp 500 (driving condition at the start of driving of the discharge lamp 500) is set to the second condition (second condition). Drive conditions). And the distance between electrodes is controlled in the range beyond the reference value. For this reason, a change in which the standing wave ratio increases means that the distance between the electrodes has changed in a direction larger than the reference value.

Then, when the protrusions 618 and 718 become smaller and the standing wave ratio deviates from the preset allowable range (becomes larger than the predetermined upper limit value), the driving condition of the discharge lamp 500 is set to the first condition described above. (First driving condition) is set.
When the protrusions 618 and 718 extend and the standing wave ratio becomes a preset reference value within the allowable range (smaller than the predetermined upper limit value), the driving condition of the discharge lamp 500 is set to the second. Set the conditions again.
In addition, although illustration and description of the flowchart corresponding to FIG. 5 in the light source device 1 are omitted, in the light source device 1, in FIG. 5, the first condition in step S101 is set as the second condition, and in step S104. The second condition may be the first condition, the second condition in step S107 may be the first condition, and the first condition in step S108 may be the second condition.

<Second Embodiment of Light Source Device>
FIG. 6 is a flowchart showing the control operation in the second embodiment of the light source device of the present invention, and FIG. 11 is a graph showing the relationship between the interelectrode distance and the interelectrode voltage in the second embodiment of the light source device of the present invention. is there. In addition, the graph of FIG. 11 is not exact | strict, and has shown the tendency of increase / decrease in the voltage between electrodes with respect to the distance between electrodes.

Hereinafter, the second embodiment will be described with a focus on the differences from the first embodiment described above, and the description of the same matters will be omitted.
In the light source device 1 of the second embodiment, a voltmeter is used as the detector 35. Then, the detector 35 detects the voltage between the pair of electrodes of the discharge lamp 500. This interelectrode voltage is a value corresponding to the interelectrode distance. Therefore, the interelectrode distance is obtained indirectly by obtaining the interelectrode voltage. As shown in FIG. 11, the greater the interelectrode voltage, the longer the interelectrode distance.

Moreover, in this embodiment, since the voltage between electrodes is measured with a voltmeter, it is preferable to apply when the frequency of a drive current is less than 1 MHz.
First, a case will be described in which control is performed such that the modulation frequency in the amplitude modulation of the drive current is changed or the amplitude modulation is not performed (stopped) according to the detected voltage value.
When the voltage value detected by the detector 35 is input, the control unit 34 sets the modulation frequency in the amplitude modulation of the drive current to be larger than 10 Hz as the driving condition of the discharge lamp 500 according to the detected voltage value. A first condition (first driving condition) of 1 kHz or less, and a second condition (second driving condition) in which the modulation frequency in amplitude modulation of the driving current is set to be higher than 1 kHz or amplitude modulation is not performed. Then, one of the third condition (third driving condition) for making the modulation frequency in the amplitude modulation of the driving current smaller than the first condition is selected. The first condition is a condition in which the protrusions 618 and 718 extend moderately and maintains a suitable size, and the second condition is a condition in which the protrusions 618 and 718 do not extend (a condition in which the protrusions become smaller, ie, The third condition is a condition in which the protrusions 618 and 718 extend further than the first condition (a condition in which the protrusions increase, that is, a condition in which the distance between the electrodes decreases). is there. Even if the conditions are set so that the protrusions 618 and 718 extend moderately, as a result, the protrusions 618 and 718 may become too large or too small. The same applies to the following.

Next, a description will be given of a case where control is performed such that b / a in amplitude modulation of the drive current is changed or amplitude modulation is not performed (stopped) in accordance with the detected voltage value.
When the voltage value detected by the detector 35 is input, the control unit 34 sets b / a in the amplitude modulation of the drive current from 0% as the drive condition of the discharge lamp 500 in accordance with the detected voltage value. And a second condition (second driving condition) where b / a in the amplitude modulation of the driving current is set to be larger than 90% or amplitude modulation is not performed. Driving condition) and a third condition (third driving condition) for reducing b / a in the amplitude modulation of the driving current to be smaller than the first condition.

Next, a description will be given of a case where control is performed such that B / A in amplitude modulation of drive current is changed or amplitude modulation is not performed (stopped) according to the detected voltage value.
When the voltage value detected by the detector 35 is input, the control unit 34 sets B / A in the amplitude modulation of the drive current as 10% or more as the drive condition of the discharge lamp 500 according to the detected voltage value. First condition (first driving condition) of 90% or less and B / A in amplitude modulation of driving current is made smaller than 10% or B / A is made larger than 90% or amplitude modulated And a third condition (third driving condition) in which B / A in amplitude modulation of the driving current is brought closer to 50% than the first condition. Choose one.

  In the adjustment of the driving condition of the discharge lamp 500, first, the initial value of the driving condition of the discharge lamp 500 (driving condition at the start of driving of the discharge lamp 500) is set to the first condition. Then, as indicated by the arrow described as “first condition” in FIG. 11, the protrusions 618 and 718 extend, and the voltage between the electrodes is lower than the lower limit value (first value) of the preset allowable range. If the value becomes smaller, the driving condition of the discharge lamp 500 is set to the second condition. Further, as indicated by an arrow described as “first condition” in FIG. 11, the protrusions 618 and 718 become smaller, and the upper limit value (second value) of the allowable range in which the interelectrode voltage is set in advance. If it becomes larger than this, the driving condition of the discharge lamp 500 is set to the third condition.

As shown by the arrow described as “second condition” in FIG. 11, the protrusions 618 and 718 become smaller, or as shown by the arrow described as “third condition”, the protrusions 618 and 718. Then, when the voltage between the electrodes reaches a preset reference value within the allowable range (between the first value and the second value), the driving condition of the discharge lamp 500 is changed to the first. Set the conditions.
Next, a control operation of the discharge lamp driving device 200 of the light source device 1 will be described based on FIG.

Here, the case where the initial value of the driving condition of the discharge lamp 500 is set to the first condition is representatively described here.
First, the initial value of the driving condition of the discharge lamp 500 is set to the first condition, the driving current is supplied to the pair of electrodes 610 and 710, and the discharge lamp 500 is turned on (step S201). Note that the protrusions 618 and 718 are set so as to extend moderately and maintain a suitable size, but may be too large or too small.

Next, the voltage between the electrodes is detected, and the fluctuation rate of the voltage between the electrodes is obtained (step S202). The variation rate of the inter-electrode voltage is as follows when the detected inter-electrode voltage is V and the reference value of the inter-electrode voltage (for example, the voltage value corresponding to the inter-electrode distance to be controlled) is V ₀ (1 ) Note that the control unit 34 obtains the variation rate of the interelectrode voltage.
(V−V ₀ ) / V ₀ × 100 (1)

  Next, it is determined whether or not the detected fluctuation rate of the inter-electrode voltage is within an allowable range (step S203). Here, the allowable range of the variation rate of the voltage between the electrodes is set so that the distance between the electrodes is within the allowable range even if the detected variation rate of the voltage between the electrodes slightly deviates from the allowable range. The upper limit value of the allowable range of the variation rate of the voltage between the electrodes is preferably set to a predetermined value (for example, 10%) within a range of 5% to 15%, and a range of 3% to 12%. It is more preferable to set to a predetermined value (for example, 5%), and it is even more preferable to set it to 1%. In addition, the lower limit value of the allowable range of the fluctuation rate of the interelectrode voltage is preferably set to a predetermined value (for example, −10%) within a range of −15% to −5%, and −12% or more More preferably, it is set to a predetermined value (for example, -5%) within a range of -3% or less, and more preferably set to -1%.

When the variation rate of the voltage between the electrodes is within the allowable range, the process returns to step S202, and step S202 and subsequent steps are executed again. If the fluctuation rate of the interelectrode voltage is not within the allowable range, it is determined whether or not the fluctuation rate of the interelectrode voltage is positive (step S204).
When the fluctuation rate of the voltage between the electrodes is negative, that is, when it is smaller than the lower limit value of the allowable range of the fluctuation rate of the voltage between the electrodes, the driving condition is changed to the second condition (step S205). Thereby, the protrusions 618 and 718 become smaller.

Further, when the fluctuation rate of the interelectrode voltage is positive, that is, when it is larger than the upper limit value of the allowable range of the fluctuation rate of the interelectrode voltage, the driving condition is changed to the third condition (step S206). Thereby, the protrusions 618 and 718 extend.
Next, the voltage between the electrodes is detected, and the fluctuation rate of the voltage between the electrodes is obtained (step S207).
Next, it is determined whether or not the detected fluctuation rate of the inter-electrode voltage is a reference value (step S208). Here, in this embodiment, since the voltage value corresponding to the inter-electrode distance that is the control target is V ₀ , the reference value of the variation rate of the inter-electrode voltage is 0%. However, the reference value of the fluctuation rate of the voltage between the electrodes is not limited to 0%, and is preferably set to a predetermined value within a range of ± 1%, for example, within a range of ± 0.5%. It is more preferable that the predetermined value is set.

If the fluctuation rate of the voltage between the electrodes is not the reference value, the process returns to step S207 without changing the driving condition, and step S207 and subsequent steps are executed again. If the fluctuation rate of the interelectrode voltage is the reference value, the driving condition is changed to the first condition (step S209), the process returns to step S202, and step S202 and subsequent steps are executed again. Thereby, the distance between electrodes is kept within an allowable range.
According to the light source device 1, the same effect as that of the first embodiment described above can be obtained.

In the present embodiment, the variation rate of the voltage between the electrodes is obtained from the detected voltage between the electrodes, and each determination is performed using the variation rate of the voltage between the electrodes. You may comprise so that each judgment may be performed using.
As mentioned above, although the light source device and the discharge lamp driving method of the present invention have been described based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is an arbitrary one having the same function. It can be replaced with that of the configuration. In addition, any other component may be added to the present invention.

In the above-described embodiment, the inter-electrode distance detection unit that indirectly detects the inter-electrode distance is used. However, the present invention is not limited to this, and the inter-electrode distance detection unit is configured to directly detect the inter-electrode distance. Also good. Examples of the interelectrode distance detection unit that directly detects the interelectrode distance include a device that optically detects the interelectrode distance, such as a device that measures the interelectrode distance using laser light.
In the embodiment described above, the modulation frequency, b / a, and B / A in the amplitude modulation of the drive current are constant except for the case of changing according to the detection result of the interelectrode distance detection unit. Then, the modulation frequency, b / a and B / A may each change over time.

Moreover, in the said embodiment, although the amplitude of alternating current is constant in each of the 1st area 41 and the 2nd area 42, in this invention, either of the 1st area 41 and the 2nd area 42 is used. On the other hand, the amplitude of the alternating current may change over time. In both the first section 41 and the second section 42, the amplitude of the alternating current may change over time.
First, a configuration example of the drive current in which the amplitude of the alternating current is constant in the second section 42 and the amplitude of the alternating current changes over time in the first section 41 will be described.

FIG. 7 is a diagram showing an envelope in the configuration example of the drive current.
In the configuration example illustrated in FIG. 7A, the envelope when the drive current is a positive value among the envelopes of the drive current (hereinafter simply referred to as “envelope”) is as follows: It rises over time (the amplitude of the alternating current gradually increases). That is, the envelope is a straight line with a positive inclination.
In the configuration example shown in FIG. 7B, the envelope decreases with time in the first section 41 (the amplitude of the alternating current gradually decreases). That is, the envelope has a linear shape with a negative slope.

In the configuration example shown in FIG. 7C, the envelope has a curved shape that is curved so as to protrude upward in the first section 41.
In the configuration example illustrated in FIG. 7D, the envelope curve has a curved shape that is curved to protrude downward in the first section 41.
In the configuration example shown in FIG. 7E, the envelope rises stepwise over time in the first section 41.

In the configuration example illustrated in FIG. 7F, the envelope is gradually lowered in the first section 41 over time.
In FIG. 7A to FIG. 7F, the envelope when the drive current is a negative value is the envelope when the drive current is a positive value, and the line where the current value is 0 is the axis of symmetry. As shown in FIG.

Next, a configuration example of a drive current in which the amplitude of the alternating current is constant in the first section 41 and the amplitude of the alternating current changes over time in the second section 42 will be described.
FIG. 8 is a diagram illustrating an envelope in the configuration example of the drive current.
In the configuration example shown in FIG. 8A, the envelope increases with time in the second section 42 (the amplitude of the alternating current gradually increases). That is, the envelope is a straight line with a positive inclination.

In the configuration example shown in FIG. 8B, the envelope decreases with time in the second section 42 (the amplitude of the alternating current gradually decreases). That is, the envelope has a linear shape with a negative slope.
In the configuration example shown in FIG. 8C, the envelope has a curved shape that is curved so as to protrude upward in the second section 42.
In the configuration example shown in FIG. 8D, the envelope curve has a curved shape that is curved to be convex downward in the second section 42.

In the configuration example shown in FIG. 8E, the envelope rises stepwise over time in the second section.
In the configuration example illustrated in FIG. 8F, the envelope decreases stepwise over time in the second section 42.
In FIG. 8A to FIG. 8F, the envelope when the drive current is a negative value is the envelope when the drive current is a positive value, and the line where the current value is 0 is the axis of symmetry. As shown in FIG.
Further, although not shown in the drawing, the configuration example of the drive current in which the amplitude of the alternating current changes with time in both the first section 41 and the second section 42 is the first section shown in FIG. The envelope curve in the section 41 and the envelope curve in the second section 42 shown in FIG. 8 can be arbitrarily combined.

<Projector>
FIG. 9 is a diagram schematically showing an embodiment of the projector of the present invention.
A projector 300 shown in FIG. 9 includes the light source device 1 described above, an illumination optical system including integrator lenses 302 and 303, a color separation optical system (light guide optical system), and a liquid crystal light corresponding to red (for red). A bulb 84, a liquid crystal light valve 85 corresponding to green (for green), a liquid crystal light valve 86 corresponding to blue (for blue), a dichroic mirror surface 811 reflecting only red light, and reflecting only blue light A dichroic prism (color combining optical system) 81 on which a dichroic mirror surface 812 is formed, and a projection lens (projection optical system) 82.

The color separation optical system includes mirrors 304, 306, and 309, a dichroic mirror 305 that reflects blue light and green light (transmits only red light), a dichroic mirror 307 that reflects only green light, and a dichroic that reflects only blue light. A mirror 308 and condensing lenses 310, 311, 312, 313, and 314 are included.
The liquid crystal light valve 85 includes a liquid crystal panel 16, a first polarizing plate (not shown) bonded to the incident surface side of the liquid crystal panel 16, and a second polarizing plate bonded to the output surface side of the liquid crystal panel 16. (Not shown). The liquid crystal light valves 84 and 86 have the same configuration as the liquid crystal light valve 85. The liquid crystal panels 16 of the liquid crystal light valves 84, 85 and 86 are respectively connected to drive circuits (not shown).

In the projector 300, the liquid crystal light valves 84, 85, 86 and the drive circuit constitute a main part of a modulation device that modulates the light emitted from the light source device 1 based on image information. The main part of the projection apparatus which projects the light modulated by the modulation apparatus is comprised.
Next, the operation of the projector 300 will be described.

First, white light (white light flux) emitted from the light source device 1 passes through the integrator lenses 302 and 303. The light intensity (luminance distribution) of this white light is made uniform by the integrator lenses 302 and 303.
The white light transmitted through the integrator lenses 302 and 303 is reflected to the left in FIG. 9 by the mirror 304, and blue light (B) and green light (G) of the reflected light are respectively reflected by the dichroic mirror 305 in FIG. The red light (R) is reflected downward and passes through the dichroic mirror 305.

The red light transmitted through the dichroic mirror 305 is reflected downward in FIG. 9 by the mirror 306, and the reflected light is shaped by the condenser lens 310 and enters the liquid crystal light valve 84 for red.
Green light of blue light and green light reflected by the dichroic mirror 305 is reflected to the left side in FIG. 9 by the dichroic mirror 307, and the blue light passes through the dichroic mirror 307.

The green light reflected by the dichroic mirror 307 is shaped by the condenser lens 311 and enters the green liquid crystal light valve 85.
Further, the blue light transmitted through the dichroic mirror 307 is reflected to the left side in FIG. 9 by the dichroic mirror 308, and the reflected light is reflected to the upper side in FIG. 9 by the mirror 309. The blue light is shaped by the condenser lenses 312, 313 and 314 and enters the blue liquid crystal light valve 86.

As described above, the white light emitted from the light source device 1 is separated into the three primary colors of red, green, and blue by the color separation optical system, and is guided to the corresponding liquid crystal light valves 84, 85, and 86, respectively, and enters. .
At this time, each pixel of the liquid crystal panel 16 of the liquid crystal light valve 84 is switching-controlled (on / off) by a drive circuit that operates based on the image signal for red, and the liquid crystal panel 16 of the liquid crystal light valve 85 is controlled. Each pixel is controlled by a drive circuit that operates based on a green image signal, and each pixel of the liquid crystal panel 16 of the liquid crystal light valve 86 is controlled by a drive circuit that operates based on a blue image signal. The switching is controlled.

Thereby, red light, green light, and blue light are modulated by the liquid crystal light valves 84, 85, and 86, respectively, and a red image, a green image, and a blue image are formed, respectively.
The red image formed by the liquid crystal light valve 84, that is, the red light from the liquid crystal light valve 84, is incident on the dichroic prism 81 from the incident surface 813, and is reflected by the dichroic mirror surface 811 to the left in FIG. The light passes through the mirror surface 812 and exits from the exit surface 816.

Further, the green image formed by the liquid crystal light valve 85, that is, the green light from the liquid crystal light valve 85, enters the dichroic prism 81 from the incident surface 814, and passes through the dichroic mirror surfaces 811 and 812, respectively. The light exits from the exit surface 816.
Further, the blue image formed by the liquid crystal light valve 86, that is, the blue light from the liquid crystal light valve 86 is incident on the dichroic prism 81 from the incident surface 815, and is reflected to the left side in FIG. 9 by the dichroic mirror surface 812. Then, the light passes through the dichroic mirror surface 811 and exits from the exit surface 816.

Thus, the light of each color from the liquid crystal light valves 84, 85 and 86, that is, the images formed by the liquid crystal light valves 84, 85 and 86 are synthesized by the dichroic prism 81, thereby forming a color image. The This image is projected (enlarged projection) onto the screen 320 installed at a predetermined position by the projection lens 82.
As described above, according to the projector 300, since the light source device 1 described above is included, power consumption can be reduced, and a stable and good image can be displayed.

  DESCRIPTION OF SYMBOLS 1 ... Light source device 31 ... High frequency current generator 32 ... Amplitude modulator 33 ... Amplifier 34 ... Control part 35 ... Detector 41 ... 1st area 42 ... 2nd area 110 ... Light source unit 112 ... Main reflector 114 ... Parallel 116 ... Inorganic adhesive 200 ... Discharge lamp driving device 500 ... Discharge lamp 510 ... Discharge lamp body 512 ... Discharge space 520 ... Sub-reflecting mirror 522 ... Inorganic adhesive 610, 710 ... Electrodes 612, 712 ... Core rods 614, 714 ... Coil part 616, 716 ... Main body part 618, 718 ... Projection 620, 720 ... Connection member 630, 730 ... Electrode terminal 16 ... Liquid crystal panel 81 ... Dichroic prism 811, 812 ... Dichroic mirror surface 813-815 ... Incident surface 816 ... Outgoing Surface 82 ... Projection lens 84-86 ... Liquid crystal light valve 300 ... Professional Jector 302, 303 ... Integrator lens 304, 306, 309 ... Mirror 305, 307, 308 ... Dichroic mirror 310-314 ... Condensing lens 320 ... Screen S101-S108 ... Step S201-S209 ... Step

Claims (28)

A discharge lamp having a light emitting container including a cavity portion in which a discharge medium is enclosed, a pair of electrodes whose end portions are arranged to face each other in the cavity portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The modulation frequency of the amplitude modulation is set to 10 Hz or more and 1 kHz or less,
The light source device characterized by changing the modulation frequency of the amplitude modulation or stopping the amplitude modulation according to the detection result of the inter-electrode distance detection unit.   The driving device includes: a first driving condition in which a modulation frequency of the amplitude modulation is set to be greater than 10 Hz and 1 kHz or less according to a detection result of the inter-electrode distance detection unit; 2. The light source device according to claim 1, wherein either the second driving condition for increasing or stopping the amplitude modulation is selected to supply the driving current to the pair of electrodes.   The driving device includes: a first driving condition in which a modulation frequency of the amplitude modulation is set to be greater than 10 Hz and 1 kHz or less according to a detection result of the inter-electrode distance detection unit; Either the second driving condition for increasing or stopping the amplitude modulation and the third driving condition for making the modulation frequency of the amplitude modulation smaller than the first driving condition are selected. The light source device according to claim 1, wherein the driving current is supplied to a pair of electrodes. A discharge lamp having a light emitting container including a cavity portion in which a discharge medium is enclosed, a pair of electrodes whose end portions are arranged to face each other in the cavity portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The drive current is such that b / a is 0% or more, where a is the average amplitude of the alternating current in the first section and b is the average amplitude of the alternating current in the second section. % Or less,
A light source device characterized by changing b / a in the amplitude modulation or stopping the amplitude modulation in accordance with a detection result of the inter-electrode distance detector.   The driving device has a first driving condition in which b / a in the amplitude modulation is set to be greater than 0% and equal to or less than 90% according to a detection result of the inter-electrode distance detection unit; The light source device according to claim 4, wherein the driving current is supplied to the pair of electrodes by selecting one of the second driving condition and the second driving condition for stopping the amplitude modulation.   The driving device includes: a first driving condition for setting b / a in the amplitude modulation to be greater than 0% and 90% or less according to a detection result of the inter-electrode distance detection unit; and b / a in the amplitude modulation. Is set to be larger than 90% or the second drive condition for stopping the amplitude modulation and the third drive condition for reducing b / a in the amplitude modulation to be smaller than the first drive condition. The light source device according to claim 4, wherein a driving current is selected and supplied to the pair of electrodes. A discharge lamp having a light emitting container including a cavity portion in which a discharge medium is enclosed, a pair of electrodes whose end portions are arranged to face each other in the cavity portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The drive current has a B / A of 10% or more, where A is a total period of one of the first sections and one of the second sections and B is a period of the one first section. Set to 90% or less,
A light source device characterized by changing B / A in the amplitude modulation or stopping the amplitude modulation in accordance with a detection result of the inter-electrode distance detector.   The drive device has a first drive condition in which the B / A in the amplitude modulation is set to 10% or more and 90% or less according to the detection result of the inter-electrode distance detection unit, and the B / A in the amplitude modulation is set to 10 The driving current is supplied to the pair of electrodes by selecting one of the second driving condition for stopping the amplitude modulation, or B / A being larger than 90%. The light source device according to claim 7.   The drive device has a first drive condition in which B / A in the amplitude modulation is set to 10% or more and 90% or less according to a detection result of the inter-electrode distance detection unit, and a B / A in the amplitude modulation of 10 % Or B / A greater than 90% or stop the amplitude modulation, and B / A in the amplitude modulation is 50% higher than the first drive condition. The light source device according to claim 7, wherein a driving current is supplied to the pair of electrodes by selecting any of the third driving conditions that are close to each other.   The light source device according to claim 2, wherein the inter-electrode distance detection unit detects reflected power with respect to input power to the discharge lamp.   The light source device according to claim 10, wherein the driving device selects the first driving condition when driving of the discharge lamp is started.   The said drive device selects the said 2nd drive condition, when the ratio of the said reflected power with respect to the input electric power to the said discharge lamp, or the value of the said reflected power is larger than predetermined value. Light source device.   The drive device sets the first drive condition when the ratio of the reflected power to the input power to the discharge lamp or the value of the reflected power becomes a reference value set smaller than the predetermined value. The light source device according to claim 12 to be selected.   The light source device according to any one of claims 3, 6, and 9, wherein the inter-electrode distance detection unit detects a voltage between a pair of electrodes of the discharge lamp.   The light source device according to claim 14, wherein the driving device selects the first driving condition at the start of driving of the discharge lamp.   The light source device according to claim 14 or 15, wherein the driving device selects the second driving condition when a voltage between the pair of electrodes is smaller than a first value.   The drive device according to any one of claims 14 to 16, wherein the drive device selects the third drive condition when a voltage between the pair of electrodes is larger than a second value larger than the first value. The light source device described.   The driving device selects the second driving condition when the voltage between the pair of electrodes is smaller than a first value, and the voltage between the pair of electrodes is smaller than the first value. When the third driving condition is selected when the second driving value is larger than the second value, and the voltage between the pair of electrodes is a value between the first value and the second value; The light source device according to claim 14 or 15, wherein the first driving condition is selected.   The light source device according to claim 1, wherein an amplitude of the alternating current is constant in the first section.   The light source device according to claim 1, wherein the amplitude of the alternating current is constant in the second section.   21. The light source device according to claim 1, wherein the frequency of the alternating current is 1 kHz to 100 kHz, or 3 MHz to 10 GHz.   The temperature of the pair of electrodes fluctuates when the discharge lamp is lit by supply of the driving current, and a protrusion is formed at the tip of the pair of electrodes. The light source device described. A discharge lamp driving method comprising: a light emitting container including a cavity portion in which a discharge medium is sealed; and a pair of electrodes whose end portions are arranged to face each other in the cavity portion,
An alternating current having a frequency of 1 kHz to 10 GHz is generated;
The alternating current is amplitude-modulated such that the first interval and the second interval having an amplitude smaller than that of the first interval are alternately repeated, and the modulation frequency is 10 Hz to 1 kHz. Generate and
Detecting the distance between the pair of electrodes;
Depending on the detection result of the distance between the electrodes, the drive current is adjusted by changing the modulation frequency of the amplitude modulation or by stopping the amplitude modulation,
A method for driving a discharge lamp, wherein the adjusted driving current is supplied to the pair of electrodes. A discharge lamp driving method comprising: a light emitting container including a cavity portion in which a discharge medium is sealed; and a pair of electrodes whose end portions are arranged to face each other in the cavity portion,
An alternating current having a frequency of 1 kHz to 10 GHz is generated;
The first section and the second section having an amplitude smaller than that of the first section are alternately repeated, and the average value of the amplitude of the alternating current in the first section is a, the second section When the average value of the amplitude of the alternating current in the section is b, the alternating current is amplitude-modulated so that b / a is 0% or more and 90% or less, and a driving current is generated.
Detecting the distance between the pair of electrodes;
Depending on the detection result of the distance between the electrodes, the drive current is adjusted by changing b / a in the amplitude modulation or by stopping the amplitude modulation,
A method for driving a discharge lamp, wherein the adjusted driving current is supplied to the pair of electrodes. A discharge lamp driving method comprising: a light emitting container including a cavity portion in which a discharge medium is sealed; and a pair of electrodes whose end portions are arranged to face each other in the cavity portion,
An alternating current having a frequency of 1 kHz to 10 GHz is generated;
A first section and a second section having an amplitude smaller than that of the first section are alternately repeated, and a total period of one of the first section and one of the second sections is represented by A When the period of the one first section is B, the AC current is amplitude-modulated so that B / A is 10% or more and 90% or less, and a drive current is generated.
Detecting the distance between the pair of electrodes;
Depending on the detection result of the distance between the electrodes, the drive current is adjusted by changing B / A in the amplitude modulation or by stopping the amplitude modulation,
A method for driving a discharge lamp, wherein the adjusted driving current is supplied to the pair of electrodes. A light source device that emits light;
A modulation device that modulates light emitted from the light source device based on image information;
A projection device that projects the light modulated by the modulation device,
The light source device includes a light emitting container including a cavity portion in which a discharge medium is enclosed, a discharge lamp having a pair of electrodes whose end portions are opposed to each other in the cavity portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The modulation frequency of the amplitude modulation is set to 10 Hz or more and 1 kHz or less,
A projector that changes the modulation frequency of the amplitude modulation or stops the amplitude modulation according to a detection result of the inter-electrode distance detection unit. A light source device that emits light;
A modulation device that modulates light emitted from the light source device based on image information;
A projection device that projects the light modulated by the modulation device,
The light source device includes a light emitting container including a cavity portion in which a discharge medium is enclosed, a discharge lamp having a pair of electrodes whose end portions are opposed to each other in the cavity portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The drive current is such that b / a is 0% or more, where a is the average amplitude of the alternating current in the first section and b is the average amplitude of the alternating current in the second section. % Or less,
In accordance with a detection result of the inter-electrode distance detection unit, b / a in the amplitude modulation is changed or the amplitude modulation is stopped. A light source device that emits light;
A modulation device that modulates light emitted from the light source device based on image information;
A projection device that projects the light modulated by the modulation device,
The light source device includes a light emitting container including a cavity portion in which a discharge medium is enclosed, a discharge lamp having a pair of electrodes whose end portions are opposed to each other in the cavity portion, and
A driving device for supplying a driving current to the pair of electrodes;
An inter-electrode distance detector for detecting the distance between the pair of electrodes,
The driving device generates an alternating current having a frequency of 1 kHz or more and 10 GHz or less, and the alternating current is generated so that a first section and a second section having an amplitude smaller than that of the first section are alternately repeated. Configured to generate the amplitude-modulated drive current;
The drive current has a B / A of 10% or more, where A is a total period of one of the first sections and one of the second sections and B is a period of the one first section. Set to 90% or less,
A projector that changes B / A in the amplitude modulation or stops the amplitude modulation according to a detection result of the inter-electrode distance detection unit.

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