JP2008181816A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device to generate auxiliary discharge while reducing an influence given to the light source device. <P>SOLUTION: This light source device has a discharge lamp having a pair of electrodes in an arc tube in which an auxiliary light source is provided on the outer surface of a sealed part, a lighting device to discharge the discharge lamp, a discharge generating device to discharge the auxiliary light source, and a timing control device connected to the discharge generating device. The lighting device impresses a breakdown voltage to the discharge lamp with a no load open-circuit voltage impressed on the electrode, the timing control device outputs a signal when no discharge is started between the electrodes even after a fixed time has elapsed since impression of the breakdown voltage, and the discharge generating device discharges the auxiliary light source by inputting the signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light source device with improved starting characteristics of a discharge lamp used for a light source such as a projector.

FIG. 11 is a diagram showing a light source device disclosed in Japanese Patent Laid-Open No. 2003-338264 as a conventional light source device.
The light source device includes a discharge lamp 1 and a lighting device 31. The discharge lamp 1 has a substantially spherical arc tube 2 formed by a discharge vessel made of quartz glass. In the arc tube 2, mercury, a rare gas, and a halogen gas as necessary are sealed, and an electrode 3. Are arranged so as to face each other. Sealing portions 5 are formed so as to extend from both ends of the arc tube 2, and a metal foil 6 is embedded in these sealing portions 5. An external electrode 4 is arranged on the outer surface of the sealing portion 5 so that the tip faces with a minute gap. The end of the electrode 3 is welded and electrically connected to one end of the metal foil 6. Leads 7 a and 7 b protruding to the outside are welded to the other end of the metal foil 6 and connected to the lighting device 31. The leads 7a and 7b are connected to the external electrodes 4a and 4b.

The lighting device 31 is a step-down chopper method. The switch element Qx turns on and off the current from the DC power source _VDC . When the switch element Qx is in the on state, charging to the smoothing capacitor Cx and supply of current to the discharge lamp 1 are performed from the DC power source _VDC via the choke coil Lx. When the switch element Qx is in the OFF state, charging to the smoothing capacitor Cx and current supply to the discharge lamp 1 are performed via the diode Dx by the inductive action of the choke coil Lx. The discharge current flowing between the pair of electrodes in the light emitting part of the discharge lamp 1, the voltage between the pair of electrodes, or the lamp power that is the product of these current and voltage is appropriate for the state of the discharge lamp 1 at that time. A gate signal having an appropriate duty cycle ratio is applied to the switch element Qx from the gate drive circuit Gx so as to be a value.

When the discharge lamp 1 is lit, a no-load open voltage is applied between the pair of electrodes in the light emitting part of the discharge lamp 1 prior to starting. At the same time, the discharge lamp 1 and a current flows into the capacitor C _A and the external electrodes 4 connected in parallel, an electric field is generated external electrodes 4a, even 4b, cause aerial discharge, ultraviolet rays are emitted. This ultraviolet light is irradiated into the arc tube 2 to promote ionization of the discharge medium in the arc tube 2 to assist in starting, to easily generate a discharge between the electrodes 3 at a low voltage, and to relight the discharge lamp 1 Even at times, the start-up lighting can be ensured.
JP 2003-338264 A

However, in the light source device shown in FIG. 11, the power supply line of the external electrode 4 is also connected to the electrode 3. When power is supplied to the discharge lamp 1, an auxiliary discharge is always generated by the external electrode 4 to assist in starting. Lights up. The starting assistance by the external electrode 4 is discharged in the atmosphere, so that the external electrode 4 is oxidized. For this reason, the external electrode 4 is worn out before the life of the discharge lamp 1 and cannot be discharged, and the discharge lamp 1 may not be lit.
On the other hand, when the discharge lamp 1 is in a temperature state of about room temperature, the voltage required for dielectric breakdown at start-up is lower than that at a high temperature immediately after the lamp is turned off. Sometimes it can be lit. Therefore, there is a problem in that the external electrode 4 is discharged and the electrode is consumed even when starting assistance is not necessarily required.

  In view of the above problems, the present invention provides a light source device that discharges an auxiliary light source only when it is necessary to light a discharge lamp, so that the auxiliary light source cannot be discharged before the life of the discharge lamp. For the purpose.

A first invention of the present application includes a discharge lamp having a pair of electrodes in an arc tube and an auxiliary light source provided on an outer surface of a sealing portion, a lighting device for discharging the discharge lamp, and the auxiliary light source. A discharge generator for discharging, and a timing control device connected to the discharge generator, the lighting device having a dielectric breakdown in the discharge lamp in a state where a no-load open-circuit voltage is applied to the electrode A voltage is applied, and the timing control device outputs a signal when a discharge has not started between the electrodes even after a lapse of a certain time from the application of the dielectric breakdown voltage, and the discharge generator receives the signal. In this case, the auxiliary light source is discharged.
In addition, in the second invention of the present application, in the first invention of the present application, the timing control device is applied to a counter to which an application start signal of the breakdown voltage is input from the lighting device and a lead of the discharge lamp. A voltage comparison circuit for comparing a voltage with a reference voltage, and an output of the counter and an output of the voltage comparison circuit are input to a logic operation circuit.
According to a third invention of the present application, in the first invention of the present application, the discharge generating device generates a voltage by a piezoelectric element.

  According to the light source device of the present invention, since the lighting device and the discharge generation device are included, the auxiliary light source can be supplied with power separately from the electrodes. In addition, the lighting device applies a breakdown voltage to the discharge lamp with a no-load open voltage applied to the electrodes, and the timing control device starts discharging between the electrodes even after a lapse of a certain time from the application of the breakdown voltage. Since the signal is output when the discharge lamp is not in operation and the discharge generator is operated to discharge the auxiliary light source, discharge of the discharge lamp is not started, and the auxiliary light source can be discharged only when necessary. Further, since the number of times the auxiliary light source discharges can be reduced, the auxiliary light source cannot be discharged before the life of the discharge lamp.

A first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view illustrating the configuration of the light source device of the present invention.
The light source device includes a discharge lamp 1, a lighting device 31, a timing control device 32, and a discharge generator 33, and the reflecting mirror 10 is disposed so as to surround the discharge lamp 1.
The discharge lamp 1 has a substantially spherical arc tube 2 formed by a discharge vessel made of quartz glass, and a pair of electrodes 3 are arranged in the arc tube 2 so as to face each other. Sealing portions 5 are formed so as to extend from both ends of the arc tube 2, and a metal foil 6 is embedded in these sealing portions 5. An external electrode 4 is arranged on the outer surface of the sealing portion 5 so that the tip faces with a minute gap. The end of the electrode 3 is welded and electrically connected to one end of the metal foil 6. Leads 7 a and 7 b projecting to the outside are welded to the other end of the metal foil 6, one lead 7 a is connected to a power supply line 41 a extending from the lighting device 31, and the other lead 7 b is also a power supply line extending from the lighting device 31. 42a. On the other hand, power supply lines 46 a and 46 b extending from the discharge generator 33 are connected to the external electrode 4.

The arc tube 2 is filled with mercury, a rare gas, and, if necessary, a halogen gas. Mercury is used to obtain necessary visible light, for example, radiated light having a wavelength of 380 to 770 nm, and an amount of 0.16 mg / mm ³ or more is enclosed. Although the amount of sealing varies depending on the temperature condition, the vapor pressure becomes extremely high at 150 atm or higher when the lamp is turned on. By enclosing more mercury, it is possible to make a discharge lamp with a high mercury vapor pressure of 200 atm or higher and 300 atm or higher when the lamp is turned on, and the higher the mercury vapor pressure, the more suitable the light source suitable for the projector device. it can. As the rare gas sealed for starting the lighting, for example, argon gas is sealed at about 13 kPa. Moreover, iodine, bromine, chlorine, etc. are enclosed with halogen gas, and the amount of enclosure is selected from the range of 10 ^{< -6} > -10 ^<-2 > micromol / mm ^{< 3} >, for example.

As an example of the dimensions of the discharge lamp, the maximum outer diameter of the arc tube is 9.5 mm, the distance between the electrodes is 1.5 mm, the arc tube inner volume is 75 mm ³ , the rated voltage is 80 V, and the rated power is 150 W. This discharge lamp is incorporated in a projector device or the like that is miniaturized, and the entire structure is extremely miniaturized, but a high light quantity is required. Therefore, the thermal conditions in the arc tube are extremely severe, and the tube wall load value is 0.8 to 2.0 W / mm ² , specifically 1.5 W / mm ² . The reflecting mirror 10 is made of, for example, a metal made of SUS, and is disposed so as to surround the discharge lamp 1.

FIG. 2 is a circuit diagram of the lighting device 31 of the present invention.
The lighting device 31 includes a step-down chopper circuit 51 and a high voltage generation circuit 53. A DC voltage _VDC is supplied to the step-down chopper circuit 51, and a high voltage generation circuit 53 is connected to the output side of the step-down chopper circuit 51. The output of the high voltage generation circuit 53 is connected in series to the lead of the discharge lamp 1.

The step-down chopper circuit 51 is connected to a DC power source _VDC , and includes a switching element Qx, a diode Dx, a coil Lx, a smoothing capacitor Cx, and a drive circuit Gx for the switching element Qx. The switching element Qx is turned on / off by the drive circuit Gx. By this driving, the duty ratio of the switching element Qx is adjusted, and the current or power supplied to the discharge lamp 10 is controlled. That is, the control circuit 55 feedback-controls the switching element Qx via the drive circuit Gx based on the current signal Si detected by the voltage signals Sv and R3 detected by the resistors R1 and R2. As a result, constant current control is performed in which the lamp current is a predetermined value during the initial lighting period, and constant power control is performed in which the lighting power of the discharge lamp is a constant value during steady lighting.

  The high voltage generation circuit 53 includes a switch element Q5, a drive circuit G5, a resistor R4, a capacitor C2, and a transformer T2. The energy accumulated in the capacitor C2 at the time of starting the discharge lamp 1 is applied to the transformer T2 by turning on the switch element Q5 by the drive circuit G5, and is boosted to generate a high voltage pulse. The high voltage pulse supplied by the high voltage generation circuit 53 is continuously superimposed on the no-load discharge voltage supplied by the step-down chopper circuit 51 for a predetermined period (one burst), and the high voltage pulse is applied between the electrodes to discharge the discharge lamp 1. Start. This embodiment shows a so-called internal trigger method. Further, the power supply line 44 is output from the drive circuit G5, and an application start signal for dielectric breakdown voltage is output.

  As shown in FIG. 1, feed lines 41, 42, 44 that are outputs of the lighting device 31 are connected to the discharge lamp 1 or the timing control device 32. The power supply line 41 is branched into two, the power supply line 41 a is connected to the lead wire 7 a connected to the electrode 3 of the discharge lamp 1, and the power supply line 41 b is connected to the timing control device 32. The power supply line 42 is branched into two, the power supply line 42 a is connected to the lead wire 7 b connected to the electrode 3 of the discharge lamp 1, and the power supply line 42 b is connected to the timing control device 32. The feeder line 44 is connected to the timing control device 32.

FIG. 3 is a diagram showing the timing control device 32 of the present invention. FIG. 3A is a circuit diagram of the timing control device 32, and FIG. 3B is a block diagram of the timing control device 32.
The timing control device 32 includes a rectifier circuit 61, a comparison circuit 62, and a logical operation circuit 63.
Feed lines 41b and 42b are input to the rectifier circuit 61, and a potential difference between the electrodes is detected. When no high voltage pulse is input from the high voltage generation circuit, a no-load open voltage is applied before the start of discharge, so there is a potential difference of 350 V between the electrodes. Falls to 100V. By detecting the potential difference between the electrodes, it can be confirmed whether or not the discharge has started. When AC power is supplied to the electrode 3 of the discharge lamp 1, a diode bridge that converts AC power into DC power is used as the rectifier circuit 61.
The voltage comparison circuit 62 compares the output of the rectifier circuit 61 with the reference voltage V. The output of the rectifier circuit 61 is a potential difference between the electric power of the discharge lamp 1. The reference voltage V is smaller than the potential difference between the electrodes before the start of discharge when the high voltage pulse from the high voltage generation circuit is not superimposed, and larger than the potential difference between the electrodes after the start of discharge. Therefore, if the output of the rectifier circuit 61 is larger than the reference voltage V, the discharge is not started between the electrodes, and if the output of the rectifier circuit 61 is smaller than the reference voltage V, the discharge is started between the electrodes. Recognize. An operational amplifier is used as the voltage comparison circuit 62.
The logic operation circuit 63 outputs a signal when the discharge between the electrodes has not started even after a certain time has elapsed since the start of power supply from the lighting device 31 to the discharge lamp 1. The power supply line 44 is connected to the counter 64, and receives a signal when the lighting device 31 starts supplying power. The counter 64 measures a certain period from the application of the dielectric breakdown voltage of the lighting device 31. The logical operation circuit 63 outputs a signal when a certain period of time has elapsed from the start of power supply and no discharge has started between the electrodes due to input from the counter 64 and input from the output signal of the voltage comparison circuit 62. Output. An AND circuit is used as the logic operation circuit 63.

  When a signal is output from the timing control device 32, the signal is input to the discharge generator 33 through the power supply lines 45a and 45b, as shown in FIG. The discharge generator 33 generates a high voltage necessary to generate an air discharge at the external electrode 4. A high voltage is supplied to the external electrode 4 by the power supply lines 46a and 46b, the external electrode 4 serves as an auxiliary light source, and the external electrode 4 causes all-path breakdown discharge such as spark discharge, glow discharge, arc discharge, Ultraviolet rays are emitted. This ultraviolet ray is irradiated into the arc tube 2 to promote ionization of the discharge medium in the arc tube 2. Thereby, discharge generation between the electrodes 3 is promoted, and it is possible to light up reliably even at the time of relighting.

FIG. 4 is a timing chart of voltages input to the discharge lamp 1 and the external electrode 4. This discharge lamp 1 is known to have a no-load open voltage of 350V and a voltage after the start of discharge of 100V. The lamp end voltage indicates a potential difference between the lead 7a and the lead 7b, the dielectric breakdown voltage indicates a high voltage pulse input from the high voltage generation circuit 53, and the starting auxiliary voltage indicates a voltage input to the external electrode 4. . When the discharge lamp 1 is lit, a no-load open voltage is applied between the electrodes prior to starting. Thereafter, a pulsed breakdown voltage is superimposed for a predetermined period (one burst), and the discharge medium is excited to start discharge. However, the voltage at the lamp end remains high at 350 V even after t ₁ after the end of the first burst after inputting a pulsed dielectric breakdown voltage for a predetermined period from the start of power supply. That is, although 10 kV is applied as a pulsed breakdown voltage for 1 burst, ionization of the discharge medium in the arc tube 2 is promoted, but the breakdown between the electrodes of the discharge lamp 1 cannot be performed and no discharge is generated. Therefore, the input time t ₂ of 2 bursts th pulsed breakdown voltage, by also inputting the voltage to the starting aid voltage, lamp end voltage is set to be a 100V from 350 V. That is, at the time t ₂ when the breakdown voltage of the second burst is input, not only the breakdown voltage but also the external electrode 4 is applied with 10 kV to promote ionization of the discharge medium in the arc tube 2, and between the electrodes of the discharge lamp 1. This causes breakdown and generates electric discharge.

This will be described with reference to FIG. The rectifier circuit 61 detects the lamp end voltage, and the comparator circuit 62 detects that the discharge lamp 1 is not discharged. The counter 64 counts a period from the start of dielectric breakdown voltage application to after the first burst dielectric breakdown voltage application, that is, a section T shown in FIG. In the logical operation circuit 63, between the breakdown voltage is applied after t ₁ of first burst until breakdown voltage applied t ₂ of 2 bursts th first burst breakdown voltage application after still discharge of the discharge lamp 1 It detects that it has not started, and outputs a signal for causing the external electrode 4 to generate auxiliary discharge. The dielectric breakdown voltage is applied again for the same period as the first burst after a pause period after the application of one burst. Unless a discharge starts between the electrodes of the discharge lamp 1, a pulsed breakdown voltage is applied in this cycle. For example, when it is desired to generate an auxiliary discharge when the discharge of the discharge lamp 1 is not started even when the breakdown voltage is applied for two bursts or more, the application of the breakdown voltage to the counter 64 is started after the breakdown voltage is applied. What is necessary is just to count the period until later.
That is, the counter 64 is allowed to measure a certain period of time from the start of applying the dielectric breakdown voltage of the lighting device 31 to the time after applying the dielectric breakdown voltage for one burst or more. Until the next breakdown voltage application, whether or not the discharge lamp 1 has started to be discharged is detected, and if the discharge lamp 1 has not started to discharge, the next breakdown voltage is applied simultaneously A signal is output to discharge the light source. Thus, the timing control device 32 can output a signal only when a discharge has not started between the electrodes even after a certain time has elapsed since the start of power supply from the lighting device 31 to the discharge lamp 1. .
As described above, the lighting device 31 applies a dielectric breakdown voltage to the discharge lamp 1 with a no-load open voltage applied to the electrode 3, and the timing control device 32 passes a certain time from the dielectric breakdown voltage application. After that, a signal is output when the discharge is not started between the electrodes, and the discharge generator 33 is operated to discharge the auxiliary light source. Therefore, the discharge to the external electrode 4 is performed only when the discharge lamp 1 is not started to discharge. A discharge can be generated. Further, since the number of times the auxiliary light source discharges can be reduced, the auxiliary light source cannot be discharged before the life of the discharge lamp.

A second embodiment of the present invention will be described. FIG. 5 is a cross-sectional view for explaining the structure of the light source device of the present invention.
In the second embodiment, the external light source AC lighting is used in the light source device of the first embodiment. Therefore, a metal wire is wound around the outer surface of the arc tube 2 and an external lead 8 is provided. A power supply line 43 extending from the lighting device 31 is also connected to the external lead 8.

FIG. 6 is a circuit diagram of the lighting device 31 of the present invention.
In the lighting device 31, a full bridge circuit 52 is added to the lighting device 31 shown in FIG. 2, and an external lead is connected to the output of the high voltage generation circuit 53. A full bridge circuit 52 is connected to the output side of the step-down chopper circuit 51, the full bridge circuit 52 changes a DC voltage to an AC voltage, and a high voltage generation circuit 53 is connected to the output side of the full bridge circuit 52. The lead of the discharge lamp 1 is supplied with power by connecting a coil L1 and a capacitor C1 in series with the output of the full bridge circuit 52, and the output of the high voltage generating circuit 53 is supplied to the external lead of the discharge lamp 1.

The full bridge circuit 52 includes switching elements Q1 to Q4 of transistors and FETs connected in a bridge shape, and driving circuits G1 to G4 for the switching elements Q1 to Q4. Note that a diode may be connected in parallel to each of the switching elements Q1 to Q4, but the diode is omitted in this embodiment. The switching elements Q1 to Q4 are driven by driving circuits G1 to G4 via a control unit (not shown).
In the operation of the full bridge circuit 52, the switching elements Q1 and Q4 and the switching elements Q2 and Q3 are alternately turned on and off repeatedly. When the switching elements Q1 and Q4 are turned on, a current flows through the path of the step-down chopper circuit 51 → the switching element Q1 → the coil L1 → the discharge lamp 10 → the switching element Q4 → the step-down chopper circuit 51. On the other hand, when the switching elements Q2 and Q3 are turned on, a current flows through a path of the step-down chopper circuit 51 → the switching element Q3 → the discharge lamp 10 → the coil L1 → the switching element Q2 → the step-down chopper circuit 51. In this way, an AC rectangular wave current is supplied to the discharge lamp 1.

  The high voltage generation circuit 53 includes a switch element Q5, a drive circuit G5, a resistor R1, a capacitor C2, and a transformer T2. The energy accumulated in the capacitor C2 at the start of the discharge lamp 1 is applied to the transformer T2 by turning on the switch element Q5 by the drive circuit G5 to boost the voltage, and a high voltage pulse is applied from the external lead to start the discharge lamp 1 Let This embodiment shows a so-called external trigger method. Further, the power supply line 44 is output from the drive circuit G5, and the discharge start signal of the discharge lamp 1 is detected.

  FIG. 7 is a timing chart of the voltage input to the discharge lamp 1. Unlike the first embodiment, the dielectric breakdown voltage is not superimposed on the lamp end voltage. Therefore, the lamp end voltage indicates only a no-load open voltage or a voltage after the start of discharge. The lamp end voltage remains high at 1.2 kV even after input of the first burst of breakdown voltage is completed. That is, although ionization of the discharge medium in the arc tube 2 was promoted by applying 10 kV to the external lead 8, the insulation between the electrodes of the discharge lamp 1 could not be broken and no discharge occurred. Therefore, when the dielectric breakdown voltage of the second burst is input, the lamp end voltage is changed from 1.2 kV to 100 V by inputting the voltage also to the starting auxiliary voltage. In other words, when the dielectric breakdown voltage of the second burst is input, not only the external lead 8 but also the external electrode 4 is applied with 10 kV to promote ionization of the discharge medium in the arc tube 2 and dielectric breakdown is caused between the electrodes of the discharge lamp 1. The discharge is generated.

This will be described with reference to FIG. The rectifier circuit 61 detects the lamp end voltage, and the comparator circuit 62 detects that the discharge lamp 1 is not discharged. The counter 64 measures a period from the start of dielectric breakdown voltage application to after the first burst dielectric breakdown voltage application, that is, a section T shown in FIG. The logical operation circuit 63 detects that the discharge lamp 1 has not yet started discharging even after applying the dielectric breakdown voltage of the first burst, and outputs a signal for causing the external electrode 4 to generate auxiliary discharge. In the external trigger method, unlike the internal trigger method, the breakdown voltage is not superimposed on the no-load open voltage, so that the lamp end voltage is detected while the breakdown voltage is applied, and the discharge lamp 1 is discharged. It can also be determined whether or not it has been started. However, if it is determined that the breakdown voltage is being applied, after it is determined that the discharge lamp 1 has not started discharging, the discharge lamp 1 starts to be discharged by the breakdown voltage that has been applied after the determination. There is a fear. In that case, since discharge of the discharge lamp 1 has started, it is not necessary to discharge the auxiliary light source at the timing of applying the next breakdown voltage. Therefore, even in the external trigger method, it is preferable to determine whether or not discharge of the discharge lamp 1 has been started between the application of the dielectric breakdown voltage and the application of the next dielectric breakdown voltage.
As described above, the lighting device 31 applies a dielectric breakdown voltage to the discharge lamp 1 with a no-load open voltage applied to the electrode 3, and the timing control device 32 passes a certain time from the dielectric breakdown voltage application. After that, a signal is output when the discharge is not started between the electrodes, and the discharge generator 33 is operated to discharge the auxiliary light source. Therefore, the discharge to the external electrode 4 is performed only when the discharge lamp 1 is not started to discharge. An auxiliary discharge can be generated. Further, since the number of times the auxiliary light source discharges can be reduced, the auxiliary light source cannot be discharged before the life of the discharge lamp.

A third embodiment of the present invention will be described. FIG. 8 is a cross-sectional view for explaining the structure of the light source device of the present invention.
In the third embodiment, the discharge generator 33 that generates a high voltage in the second embodiment is changed to a discharge generator 33 including an eccentric cam 33a and a piezoelectric element 33b. The piezoelectric element 33b refers to, for example, piezoelectric ceramics, and is generally used for applications such as lighters and gas appliances that perform ignition using high-pressure discharge. The piezoelectric element 33b can obtain a voltage sufficient for discharging when a large impact is applied instantaneously. When the eccentric cam 33a rotates, the lever 33c connected to the eccentric cam 33a is moved, and the lever 33c presses the piezoelectric element 33b. As a result, a voltage required for discharging the external electrode 4 is generated and supplied to the external electrode 4 through the power supply lines 46a and 46b. The external electrode 4 serves as an auxiliary light source, an air discharge occurs at the external electrode 4, and ultraviolet rays are emitted. This ultraviolet ray is irradiated into the arc tube 2 to promote ionization of the discharge medium in the arc tube 2. The generation of electric discharge between the electrodes 3 is promoted, and the light can be reliably turned on even at the time of relighting. Further, by configuring the discharge generator 33 with the eccentric cam 33a and the piezoelectric element 33b, a voltage necessary for discharging the external electrode 4 can be generated simply by rotating the eccentric cam 33a, thereby reducing energy consumption. be able to.

A fourth embodiment of the present invention will be described. 9 is a cross-sectional view for explaining the structure of the light source device of the present invention, FIG. 10 is a view showing the auxiliary light source 9, FIG. 10 (a) is a cross-sectional view in the tube axis direction of the auxiliary light source 9, and FIG. ) Is a cross-sectional view taken along the line ZZ ′ in FIG.
In the fourth embodiment, the external electrode 4 of the second embodiment is changed to an auxiliary light source 9. As shown in FIG.
The auxiliary light source 9 has a pair of first external electrode Eu and second external electrode Ev facing each other on the outer surfaces of both ends of a discharge vessel Bx made of, for example, quartz glass. Inside the discharge vessel Bx, an internal trigger Wx made of, for example, a metal bar or a foil piece is enclosed. The internal trigger Wx distorts the electric field in the auxiliary discharge space inside the auxiliary discharge vessel Bx, generates a high electric field locally, and generates a discharge at a relatively low voltage. The internal trigger Wx is shorter than the distance between the external electrodes Eu and Ev so as to be applied only to one external electrode Eu. A getter material Gx that absorbs impure gas is enclosed inside the discharge vessel Bx. As a discharge medium, in addition to a rare gas such as argon, xenon, or neon, one or more gases such as nitrogen or helium are enclosed.
As shown in FIG. 9, when a voltage is applied between the pair of external electrodes Eu and Ev of the auxiliary light source 9 from the power supply lines 46a and 46b, a dielectric barrier discharge is induced in the discharge space, and the auxiliary discharge starts. And ultraviolet rays are emitted. This ultraviolet ray is irradiated into the arc tube 2 to promote ionization of the discharge medium in the arc tube 2. The generation of electric discharge between the electrodes 3 is promoted, and the light can be reliably turned on even at the time of relighting. Further, since the ultraviolet light irradiation by the auxiliary light source 9 occurs inside the discharge container Bx of the auxiliary light source 9, the occurrence of malfunction in an electronic device such as a projector is suppressed.

Sectional drawing for description which shows the structure of the light source device of this invention Circuit diagram of lighting device of the present invention The figure which showed the timing control apparatus of this invention Voltage timing chart of the present invention Sectional drawing for description which shows the structure of the light source device of this invention Circuit diagram of lighting device of the present invention Voltage timing chart of the present invention Sectional drawing for description which shows the structure of the light source device of this invention Sectional drawing for description which shows the structure of the light source device of this invention Sectional drawing for description which shows the structure of the auxiliary light source of this invention Cross-sectional view for explaining a light source device according to the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discharge lamp 2 Arc tube 3 Electrode 4 External electrode 5 Sealing part 31 Lighting device 32 Timing control device 33 Discharge generator

Claims (3)

A discharge lamp having a pair of electrodes in the arc tube and an auxiliary light source provided on the outer surface of the sealing portion, a lighting device for lighting the discharge lamp, and a discharge generator for discharging the auxiliary light source And a timing control device connected to the discharge generator,
The lighting device applies a breakdown voltage to the discharge lamp in a state where a no-load open voltage is applied to the electrode, and the timing control device is configured to apply the electrode even after a lapse of a certain time from the application of the breakdown voltage. A signal is output when no discharge has started between the two, and the discharge generator discharges the auxiliary light source when the signal is input. The timing control device includes a counter to which an application start signal of the breakdown voltage is input from the lighting device, and a voltage comparison circuit that compares a voltage applied to a lead of the discharge lamp with a reference voltage, The light source device according to claim 1, wherein an output of the counter and an output of the voltage comparison circuit are input to a logic operation circuit. The light source device according to claim 1, wherein the discharge generator generates a voltage by a piezoelectric element.

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