JP2009295556A - Discharge lamp device - Google Patents

Abstract

In a discharge lamp device using a rare gas fluorescent lamp or the like, it is possible to reliably distinguish and detect when there is no load and when it is lit.
An AC conversion circuit 2 that alternately operates a first switch element and a second switch element to output an AC voltage, and a rare gas fluorescent lamp 4 on a secondary side of a transformer 3 that boosts the AC voltage. In the discharge lamp device described above, the first current path that flows when the first switch element is on and the second current path that flows when the second switch element are on overlap, and the currents that flow through the first current path and the second current path mutually The current waveform detection circuit 51 connected to the current path in the reverse direction and the detection current of the current waveform detection circuit are allowed to pass for approximately half a period including the ON period of the first switch element but not the ON period of the second switch element. A no-load detection circuit comprising a switch circuit 52, an averaging circuit 53 that averages the current that has passed through the switch circuit, and a comparison circuit 54 that compares the output value of the averaging circuit with a reference value. 5, characterized in that the provided.
[Selection] Figure 1

Description

  The present invention relates to a discharge lamp device, and more particularly to a discharge lamp device that uses a rare gas fluorescent lamp as a discharge lamp and is used for a backlight light source, an illumination light source, and the like of a liquid crystal display panel.

  Conventionally, cold cathode fluorescent lamps and hot cathode fluorescent lamps are often used as backlight sources and illumination light sources of liquid crystal display panels. These lamps contain a very small amount of mercury inside, and emit phosphors by ultraviolet rays generated from mercury excited by discharge, so that high-luminance and efficient light emission can be obtained. Are better.

  However, in recent years, a new light source that does not contain mercury is desired from the viewpoint of preventing environmental pollution. As a fluorescent lamp that does not contain mercury, a plurality of strip-shaped electrodes are arranged on the outer surface of a glass tube, and a high-frequency high voltage boosted by a transformer, for example, is applied to these electrodes to turn on the rare gas fluorescence. A lamp has been proposed.

  By the way, it is necessary to assume that the rare gas fluorescent lamp is in a so-called no-load state in which the wiring is disconnected for some reason or the arc tube is broken to cause a gas leak and cannot be turned on. When no load is applied, high voltage is generated due to resonance caused by parasitic capacitance and inductance in the circuit, and the high-frequency power supply in the device may be damaged, or an abnormal situation may occur in which the circuit insulation in the device is destroyed. There is. Therefore, it is necessary to take such measures as quickly detecting such a no-load state and stopping the apparatus.

  Patent Document 1 describes a discharge lamp lighting device that detects a no-load state by connecting a rare gas fluorescent lamp to the secondary side of an output transformer and detecting a current flowing through the secondary side of the output transformer. . However, the no-load detection means described in Patent Document 1 has a problem that it is easy to erroneously detect when no load is on due to a high-frequency oscillating current flowing through a stray capacitance such as a harness or transformer of a rare gas fluorescent lamp. Therefore, Patent Document 2 describes a discharge lamp lighting device in which high-frequency current bypass means is added to no-load detection means in order to prevent unload detection from being hindered by high-frequency current flowing through the stray capacitance at no load. Yes. More specifically, a configuration is shown in which a high-frequency current flowing when there is no load is shunted by connecting a capacitor or a series circuit of a capacitor and a resistor in parallel to the current detection portion of the no-load detection means.

FIG. 18 is a diagram showing a circuit configuration of a discharge lamp device according to the prior art as described in Patent Document 2. As shown in FIG.
In the figure, the DC voltage output from the DC power supply 101 is input to the AC conversion circuit 102. The AC conversion circuit 102 includes switching elements Q11, Q12, Q21, and Q22, and diodes D11, D12, D21, and D22, and constitutes a full bridge circuit. Switching elements Q11, Q22 and switching elements Q21, Q12 are each connected in series, and DC power supply 1 is connected to both ends thereof. Switching elements Q11 and Q21 are arranged on the high side, and switching elements Q22 and Q12 are arranged on the low side. Diodes D11, D12, D21, and D22 are individually connected in parallel to switching elements Q11, Q12, Q21, and Q22. The direction is the forward direction from the low potential side to the high potential side. The switching elements Q11, Q12, Q21, and Q22 are respectively input with signals S1, S1, S2, and S2 output from the switching element driving circuit 21, and are turned on when the signals are at a high level, and are turned on when the signals are at a low level. Operates to be off. Both ends of the primary side of the transformer 103 are connected to the connection point of the switching elements Q11 and Q21 and the connection point of the switching elements Q22 and Q12 of the AC conversion circuit 102, and the noble gas fluorescent lamp 104 is connected to both ends of the secondary side of the transformer 103. And a series circuit composed of a current waveform detection circuit 106 of the no-load detection circuit 105 is connected.

FIG. 19 is a circuit diagram showing a specific configuration of no-load detection circuit 105 shown in FIG.
In the figure, a current waveform detection circuit 106 comprises a resistor Rs, and outputs a current waveform signal proportional to the current that flows during lighting or no load. The current waveform signal is input to a high-frequency bypass circuit 107 formed of a low-pass filter including a resistor R1 and a capacitor C1. The output signal from the high frequency bypass circuit 107 is half-wave rectified by a rectifier circuit 108 formed of a diode D1, and is input to an averaging circuit 109 formed of a resistor R2 and a capacitor C2. The signal averaged by the averaging circuit 109 is input to the comparison circuit 110. The input signal input to the comparison circuit 110 is input to a series circuit of resistors R3 and R4, and the voltage divided by the resistors R3 and R4 is input between the base and emitter of the transistor Q1. When the base-emitter voltage exceeds about 0.6 V, the transistor Q1 is turned on, and the no-load detection signal is changed from the high level to the low level.

FIG. 20A is a diagram showing a signal waveform input to the averaging circuit 109 of the no-load detection circuit 105 when the rare gas fluorescent lamp 104 is lit in the discharge lamp device shown in FIG. Since the signal waveform is half-wave rectified by the rectifier circuit 108, the negative component is cut, and when the time average is performed in the period T, the average value has a certain magnitude that is positive. FIG. 20B is a diagram illustrating a signal waveform of an input signal input to the averaging circuit 109 of the no-load detection circuit 105 when the discharge lamp apparatus illustrated in FIG. 18 is not loaded. Since the signal waveform is half-wave rectified by the rectifier circuit 108, the negative component is cut, and when the time average is performed in the period T, the average value has a certain magnitude or more.
JP 2002-231478 A JP 2003-36987 A

  However, the no-load detection means described in Patent Document 2 is difficult to distinguish between no-load and lighting when the difference between the frequency components of the lamp current and the high-frequency vibration current is small, and there is a possibility of erroneous detection. . Therefore, in order to avoid false detection, in order to keep the difference between the lamp current and the frequency of the high-frequency oscillating current large, the capacitance of the rare gas fluorescent lamp discharge and the stray capacitance of the harness, transformer, etc. It is necessary to place constraints on the relationship. However, there is a problem that the length of the harness and the size of the rare gas discharge lamp cannot be determined freely. In addition, if a conductor is installed near a rare gas discharge lamp or harness, etc., and it is used under conditions that cannot be assumed at the time of design, the size of the stray capacitance changes, making it difficult to prevent false detection. There is a problem of becoming.

  In view of the above-described problems, an object of the present invention is to provide a discharge lamp device capable of reliably distinguishing between no-load and lighting when a rare gas fluorescent lamp is used as a light source. There is to do.

The present invention employs the following means in order to solve the above problems. The first means includes an AC conversion circuit that alternately switches one or one set of first switching elements and the other or other set of second switching elements to convert a DC voltage into an AC voltage; and In a discharge lamp apparatus comprising a transformer for boosting an AC voltage from an AC conversion circuit and a rare gas fluorescent lamp connected to a secondary side of the transformer, the second switching element includes an ON period of the first switching element. Means for detecting a current flowing for approximately half a cycle of the AC voltage not including an ON period of the switching element, an averaging circuit for averaging the detected current, and comparing an output value of the averaging circuit with a reference value And a no-load detection circuit comprising a comparison circuit.
The second means includes an AC conversion circuit that alternately switches one or one set of first switching elements and the other or the other set of second switching elements to convert a DC voltage into an AC voltage; and A first current path that flows when a first switching element is turned on in a discharge lamp device including a transformer that boosts an AC voltage from an AC conversion circuit and a rare gas fluorescent lamp connected to a secondary side of the transformer And the second current path that flows when the second switching element is turned on, and the current flowing through the first current path and the second current path are connected in series to current paths that are in opposite directions. A current waveform detection circuit, and an approximately half cycle of the AC voltage including an ON period of the first switching element and not including an ON period of the second switching element, A switch circuit that passes the current waveform signal detected by the current waveform detection circuit, an averaging circuit that averages the current waveform signal that has passed through the switch circuit, and a comparison that compares the output value of the averaging circuit with a reference value And a no-load detection circuit comprising a circuit.
A third means is the discharge lamp device according to the second means, wherein the current waveform detection circuit of the no-load detection circuit is connected to the secondary side of the transformer.
The fourth means includes an AC conversion circuit that alternately switches one or one set of first switching elements and the other or other set of second switching elements to convert a DC voltage into an AC voltage; and A first current path that flows when a first switching element is turned on in a discharge lamp device including a transformer that boosts an AC voltage from an AC conversion circuit and a rare gas fluorescent lamp connected to a secondary side of the transformer And a current waveform detection circuit connected in series to a current path that does not overlap with a second current path that flows when the second switching element is on, and a current waveform signal detected by the current waveform detection circuit is averaged A discharge lamp device comprising a no-load detection circuit comprising an averaging circuit and a comparison circuit that compares an output value of the averaging circuit with a reference value.
The fifth means includes an AC conversion circuit that alternately switches one or one set of first switching elements and the other or the other set of second switching elements to convert a DC voltage into an AC voltage; and A first current path that flows when a first switching element is turned on in a discharge lamp device including a transformer that boosts an AC voltage from an AC conversion circuit and a rare gas fluorescent lamp connected to a secondary side of the transformer And the second current path that flows when the second switching element is turned on, and the currents that flow through the first current path and the second current path are connected in series to the current paths that are in the same direction. A current waveform detection circuit, an averaging circuit that averages current waveform signals detected by the current waveform detection circuit, and a comparison circuit that compares an output value of the averaging circuit with a reference value; Providing the no-load detecting circuit consisting of a discharge lamp device according to claim.
A sixth means is a discharge lamp device characterized in that, in any one of the first means to the fifth means, an excimer lamp that irradiates ultraviolet rays is used instead of the rare gas fluorescent lamp. .

  According to the present invention, when a discharge lamp composed of a rare gas fluorescent lamp is used as a light source, it is possible to reliably distinguish between no-load and on-light, and the conventional false detection of no-load state Can be eliminated.

A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing a circuit configuration of a discharge lamp device according to the invention of this embodiment.
In the figure, 1 is a DC power supply, 2 is an AC conversion circuit, 21 is a switching element drive circuit, 22 is an RS flip-flop, 3 is a transformer, 4 is a rare gas fluorescent lamp, 5 is a no-load detection circuit, and 51 is a transformer 3. , A current waveform detection circuit for detecting a current flowing through the secondary side, 52 a switch circuit, 53 an averaging circuit, and 54 a comparison circuit.

FIG. 2 is a diagram showing the configuration of the rare gas fluorescent lamp 4 shown in FIG. 1, and FIG. 2 (a) is a cross-sectional view as viewed from a cross section perpendicular to the tube axis direction of the rare gas fluorescent lamp. (B) is a perspective view of a noble gas fluorescent lamp.
As shown in these drawings, the rare gas fluorescent lamp 4 is, for example, a straight tube envelope that is hermetically sealed with a glass tube 41, and has a rare earth phosphor and a halophosphate fluorescent lamp on its inner surface. A fluorescent material 42 made of a fluorescent material such as a body is formed. The sealing structure of the glass tube 41 is configured by sealing a disc-shaped sealing glass plate at the end of the glass tube 41. For example, the glass tube 41 is simply heated while the glass tube 41 is heated to melt and cut. It can also be constituted by a top seal. As the external electrodes 43 and 44, for example, an aluminum tape cut into a width of 1 mm is attached to an opposing position on the outer surface of the glass tube 41 across the central axis of the rare gas fluorescent lamp. Further, the external electrodes 43 and 44 may be formed by screen printing and baking a conductive paste, for example. The sealed space of the glass tube 41 is filled with a predetermined amount of a rare gas whose main component is at least one of He, Ar, Xe, and Kr that does not contain metal vapor such as mercury. The easily startable portion 45 is made of a conductive material or an easily electron emitting material, and is disposed at least one place inside the glass tube 41 in order to facilitate the start of discharge. Discharge occurs from the easily startable portion 45 and then spreads from there to the entire rare gas fluorescent lamp. Usually, it is provided at the end of the glass tube 41 or the like so as not to affect the light extraction efficiency during lighting.

FIG. 3 is a diagram showing an equivalent circuit of the rare gas fluorescent lamp 4.
As shown in the figure, in the rare gas fluorescent lamp 4, the capacitance Cg of the glass tube 41 and the discharge impedance p are connected in series, and the capacitance Cd of the discharge space is connected in parallel with the discharge impedance p. It is expressed in the form. The electrostatic capacitance Cs is a stray capacitance such as a harness or a transformer. Thus, the rare gas fluorescent lamp 4 is a capacitive load that discharges through the electrostatic capacity of the glass tube 41. When no load is applied, the discharge impedance p becomes infinite, so the rare gas fluorescent lamp 4 can be regarded as equivalent to a capacitor.

Next, returning to FIG. 1, the circuit configuration of the discharge lamp device of the present embodiment will be described in detail.
In the figure, the DC voltage output from the DC power source 1 is input to the AC conversion circuit 2. The AC conversion circuit 2 includes switching elements Q11, Q12, Q21, and Q22, and diodes D11, D12, D21, and D22, and constitutes a full bridge circuit. Switching elements Q11, Q22 and switching elements Q21, Q12 are each connected in series, and DC power supply 1 is connected to both ends thereof. Switching elements Q11 and Q21 are arranged on the high side, and switching elements Q22 and Q12 are arranged on the low side. Diodes D11 to D22 are parasitic diodes of switching elements Q11 to Q22, or are added separately, and are individually connected in parallel to switching elements Q11, Q12, Q21, and Q22. The direction is the forward direction from the low potential side to the high potential side. The switching elements Q11, Q12, Q21, and Q22 are respectively input with signals S1, S1, S2, and S2 output from the switching element driving circuit 21, and are turned on when the signals are at a high level, and are turned on when the signals are at a low level. Operates to be off. The primary side ends of the transformer 3 are connected to the connection points of the switching elements Q11 and Q22 of the AC conversion circuit 2 and the connection points of the switching elements Q21 and Q12, and the secondary side ends of the transformer 3 are connected to the rare gas fluorescent lamps. 4 and a current waveform detection circuit 51 of the no-load detection circuit 5 are connected. The no-load detection signal output from the no-load detection circuit 5 is input to the switching element drive circuit 21.

  In the figure, switching elements Q11 and Q12 are first switching elements, and switching elements Q21 and Q22 are second switching elements. Further, a path through which a current flows when the first switching elements Q11 and Q12 are on is defined as a first current path. Specifically, from the high potential side of the DC power supply 1, the primary side of the switching element Q11 and the transformer 3 is used. From the switching element Q12, a path that circulates to the low potential side of the DC power source 1, and the high potential terminal (hereinafter referred to as HV terminal) on the secondary side of the transformer 3, the rare gas fluorescent lamp 4 and the no-load detection circuit 5 The current waveform detection circuit 51 and a path that goes around to the low potential terminal (hereinafter referred to as LV terminal) of the transformer 3 are used. Further, a path through which current flows when the second switching elements Q21 and Q22 are on is defined as a second current path. Specifically, from the high potential side of the DC power supply 1, the primary side of the switching element Q21 and the transformer 3 is used. , The switching element Q22, a path that goes around to the low potential side of the DC power supply 1, and the LV terminal on the secondary side of the transformer 3, the current waveform detection circuit 51 of the no-load detection circuit 5, the rare gas fluorescent lamp 4, and the transformer 3 A route that goes around to the secondary side HV terminal.

  Here, the current waveform detection circuit 51 of the no-load detection circuit 5 includes a first current path and a second current path that overlap each other and the first switching element is turned on, As long as it is in the path | route where the direction of the electric current which flows initially when the switching element of 2 is turned on mutually reverses, you may provide.

FIG. 4 is a circuit diagram showing a specific configuration of the no-load detection circuit 5 shown in FIG.
In the figure, a current waveform detection circuit 51 is composed of a resistor Rs and outputs a current waveform signal having a magnitude proportional to the current. If the current path cannot be grounded, a current transformer may be used instead of the resistor Rs. The current waveform signal is input to the switch circuit 52. The input signal input to the switch circuit 52 is connected to the other end of the series circuit of the resistors R1 and R2 having one end connected to the DC voltage Va. A connection point between the resistors R1 and R2 is connected to one end of the switch AS1. Here, since an analog switch with a single power supply is used, the zero point of the current waveform signal is set to R2 × Va / (R1 + R2), and the vibration waveform is adjusted so as to be within a positive range. However, R1, R2 >> Rs. A switch circuit control signal is input to the switch AS1 from the RS flip-flop 22 shown in FIG. 1 as a control signal. When the switch circuit control signal is at a high level, the switch AS1 is turned on, and when the switch circuit control signal is at a low level, the switch AS1 is turned off. The output signal of the switch circuit 52 is input to the averaging circuit 53. The input signal input to the averaging circuit 53 is input to the other end of the capacitor C1 whose one end is grounded and averaged. The averaged signal is input to the comparison circuit 54. The comparison circuit 54 includes an operational amplifier OP1, resistors R3 to R11, a transistor Q1, and a DC voltage Va. The signal input to the comparison circuit 54 is input to a differential amplifier circuit for restoring the zero point shifted by the switch circuit 52. The differential amplifier circuit includes resistors R3, R4, R7, and R8 and an operational amplifier, and has a relationship of R3 = R7 and R4 = R8. A signal averaged by the capacitor C1 is input to the positive input side (R3 side) of the differential amplifier circuit, and the voltage Va is divided by the resistors R5 and R6 on the negative input side (R7 side). Is input. Here, by setting R5 = R1 and R6 = R2, even if the magnitude of the voltage Va changes, the magnitude of shifting the zero point of the current waveform signal is the same as the magnitude of returning the voltage Va, so the voltage Va This variation can be canceled. An output signal of the differential amplifier circuit, that is, an output signal of the operational amplifier OP1 is input to a series circuit of resistors R9 and R10, and a voltage divided by the resistors R9 and R10 is input between the base and emitter of the transistor Q1. When the base-emitter voltage exceeds about 0.6 V, the transistor Q1 is turned on, and the no-load detection signal is changed from the high level to the low level. In FIG. 1, when the no-load detection signal is at a low level, the switching element drive circuit 21 is kept oscillating. When the no-load detection signal is at a high level, the oscillation of the switching element drive circuit 21 is stopped. To work.

FIG. 5 is a timing chart for explaining the circuit operation of the discharge lamp device shown in FIG.
In the figure, a signal S1 is a repetitive signal in which a high level signal having a pulse width ton is repeated in a cycle T. The signal S2 is also a repetitive signal having a pulse width ton and a period T, and is output with a phase shifted by 180 ° with respect to the signal S1. The switch circuit control signal is high level from the time when the signal S1 becomes high level to the time when the signal S2 becomes high level, and after the signal S2 becomes high level until the signal S1 becomes high level. It is a signal that becomes a low level. The lamp voltage waveform of the rare gas fluorescent lamp 4 reverses its polarity from negative to positive when the signal S1 becomes high level, and reverses its polarity from positive to negative when the signal S2 becomes high level. Here, the current waveform signal detected by the current waveform detection circuit 51 is a signal proportional to the current flowing through the first and second current paths. The input signal that is controlled by the switch circuit 52 and input to the averaging circuit 53 corresponds to a current waveform signal that is extracted only while the switch circuit control signal is at a high level. In the present embodiment, the switch circuit control signal is the high level between the time when the signal S1 becomes high level and the time when the signal S2 becomes high level, and after the signal S2 becomes high level, the signal S1 The switch circuit control signal is controlled to be at a high level until the signal reaches a high level, but the ON period of the switch circuit control signal is a period of approximately a half cycle (T / 2) including the entire ON period of the signal S1. If there is, it is not necessary to limit to this.

Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 6 is a diagram showing a circuit configuration of the discharge lamp device according to the invention of the present embodiment. In the figure, the configuration other than the configuration of the no-load detection circuit 6 and the insertion position in the circuit corresponds to the configuration of the same symbol shown in FIG.
In the figure, switching elements Q11 and Q12 are first switching elements, and switching elements Q21 and Q22 are second switching elements. A path through which current flows when the first switching elements Q11 and Q12 are on is defined as a first current path. Specifically, from the high potential side of the DC power supply 1, the switching element Q11, the primary side of the transformer 3, the switching From the element Q12, the current waveform detection circuit 61 of the no-load detection circuit 6, the path that goes around to the low potential side of the DC power supply 1, and the HV terminal on the secondary side of the transformer 3, the rare gas fluorescent lamp 4 and the LV of the transformer 3 The route goes around to the terminal. Further, a path through which current flows when the second switching elements Q21 and Q22 are on is defined as a second current path. Specifically, from the high potential side of the DC power supply 1, the primary side of the switching element Q21 and the transformer 3 is used. , A path that circulates to the low potential side of the switching element Q22 and the DC power source 1, and a path that circulates from the LV terminal on the secondary side of the transformer 3 to the HV terminal on the secondary side of the rare gas fluorescent lamp 4 and transformer 3. And

  In the figure, the current waveform detection circuit 61 of the no-load detection circuit 6 is provided in the first current path. However, the current waveform detection circuit 61 is provided anywhere in the path where the first current path and the second current path do not overlap each other. good.

FIG. 7 is a circuit diagram showing a specific configuration of the no-load detection circuit 6 shown in FIG.
In the figure, a current waveform detection circuit 61 is composed of a resistor Rs and outputs a current waveform signal having a magnitude proportional to the current. If the current path cannot be grounded, a current transformer may be used instead of the resistor Rs. The output signal from the current waveform detection circuit 61 is input to an averaging circuit 62 composed of a resistor R1 and a capacitor C1, and is averaged. An output signal from the averaging circuit 62 is input to the comparison circuit 63. The input signal input to the comparison circuit 63 is input to the series circuit of the resistors R2 and R3, and the voltage divided by the resistors R2 and R3 is input between the base and emitter of the transistor Q1. When the base-emitter voltage exceeds about 0.6 V, the transistor Q1 is turned on, and the no-load detection signal is changed from the high level to the low level.

FIG. 8 is a timing chart for explaining the circuit operation of the discharge lamp device shown in FIG.
In the figure, a signal S1 is a repetitive signal in which a high level signal having a pulse width ton is repeated in a cycle T. The signal S2 is also a repetitive signal having a pulse width ton and a period T, and is output with a phase shifted by 180 ° with respect to the signal S1. The ramp voltage waveform reverses in polarity from negative to positive when the signal S1 goes high, and reverses in polarity from positive to negative when the signal S2 goes high. Here, the current waveform signal detected by the current waveform detection circuit 61 is a signal proportional to the current in one of the first and second current paths.

Next, a third embodiment of the present invention will be described with reference to FIGS.
FIG. 9 is a diagram showing a circuit configuration of the discharge lamp device according to the invention of the present embodiment. In the figure, the configuration other than the configuration of the no-load detection circuit 7 and the insertion position in the circuit corresponds to the configuration of the same reference numeral shown in FIG. The specific configuration of the no-load detection circuit 7 is the same as the circuit diagram described in FIG.
In the figure, switching elements Q11 and Q12 are first switching elements, and switching elements Q21 and Q22 are second switching elements. Further, a path through which a current flows when the first switching elements Q11 and Q12 are on is defined as a first current path. Specifically, from the high potential side of the DC power supply 1, the primary side of the switching element Q11 and the transformer 3 is used. From the switching element Q12, the current waveform detection circuit 71 of the no-load detection circuit 7, the path that goes around to the low potential side of the DC power supply 1, and the HV terminal on the secondary side of the transformer 3, the rare gas fluorescent lamp 4, the transformer 3 The route goes around to the LV terminal. Further, a path through which current flows when the second switching elements Q21 and Q22 are on is defined as a second current path. Specifically, from the high potential side of the DC power supply 1, the primary side of the switching element Q21 and the transformer 3 is used. From the switching element Q22, the current waveform detection circuit 71 of the no-load detection circuit 7, the path that goes around to the low potential side of the DC power supply 1, and the LV terminal on the secondary side of the transformer 3, the rare gas fluorescent lamp 4, the transformer 3 A route that goes around to the secondary side HV terminal.

  In the figure, the current waveform detection circuit 71 of the no-load detection circuit 7 includes a first current path and a second current path that overlap each other, and the first switching element is turned on and the direction of the current that flows first. As long as it is in a path in which the directions of the first flowing currents are the same with each other when the second switching element is turned on, it may be anywhere.

FIG. 10 is a timing chart for explaining the circuit operation of the discharge lamp device shown in FIG.
In the figure, a signal S1 is a repetitive signal in which a high level signal having a pulse width ton is repeated in a cycle T. The signal S2 is also a repetitive signal having a pulse width ton and a period T, and is output with a phase shifted by 180 ° with respect to the signal S1. The ramp voltage waveform reverses in polarity from negative to positive when the signal S1 goes high, and reverses in polarity from positive to negative when the signal S2 goes high. Here, the current waveform signal detected by the current waveform detection circuit 71 is a signal proportional to the current flowing through the first and second current paths.

Next, in the discharge lamp device according to the inventions of the first to third embodiments, the current waveform of each part when the rare gas fluorescent lamp 4 is turned on and when there is no load will be described.
FIG. 11A is a diagram showing a waveform of a current flowing on the secondary side of the transformer 3 when the rare gas fluorescent lamp 4 is turned on in the discharge lamp device according to the invention of the first to third embodiments.
FIG. 11B is a diagram showing a waveform of a current flowing on the secondary side of the transformer 3 when the rare gas fluorescent lamp 4 is not loaded in the discharge lamp device according to the invention of the first to third embodiments.

FIG. 12A shows an averaging circuit 53 of the no-load detection circuit 5 (when the noble gas fluorescent lamp 4 is turned on in the discharge lamp device according to the invention of the first embodiment (or the second embodiment). Or it is a figure which shows the waveform of the input signal input into the averaging circuit 62) of the no-load detection circuit 6, and when the time average of a waveform is performed with the period T, an average value has a magnitude | size beyond a certain fixed value. When the zero point is shifted, the shifted size is subtracted.
FIG. 12B shows an averaging circuit 53 (or no-load detection circuit 6) of the no-load detection circuit 5 when the discharge lamp device according to the first embodiment (or the second embodiment) is not loaded. The oscillating current that flows during no load is the oscillating current that flows through the capacitance and stray capacitance of the noble gas fluorescent lamp 4. DC component is not included. For this reason, when the waveform is time-averaged at the period T, the average value becomes substantially zero. When the zero point is shifted, the shifted size is subtracted.

FIG. 13A shows the waveform of the input signal input to the averaging circuit 72 of the no-load detection circuit 7 when the rare gas fluorescent lamp 4 is turned on in the discharge lamp device according to the invention of the third embodiment. When the time average of the waveform is performed at the period T, the average value has a certain size or more. In addition,
FIG. 13B is a diagram showing a waveform of an input signal inputted to the averaging circuit 72 of the no-load detection circuit 7 when the discharge lamp device according to the third embodiment of the invention is not loaded. The oscillating current that flows when there is no load is the oscillating current that flows through the capacitance and stray capacitance of the rare gas fluorescent lamp 4 and does not contain a direct current component. For this reason, when the waveform is time-averaged at the period T, the average value becomes substantially zero.

  As described above, according to the discharge lamp device according to the invention of the first embodiment (or the second embodiment), as shown in FIG. 12A, the averaging circuit of the no-load detection circuit 5 at the time of lighting. 53 (or the averaging circuit 62 of the no-load detection circuit 6) has a certain magnitude or more, while the average of the no-load detection circuit 5 at no load is obtained as shown in FIG. The output of the circuit 53 (or the averaging circuit 62 of the no-load detection circuit 6 at no load) becomes substantially zero. By measuring the output of the averaging circuit 5 (or the averaging circuit 6), it is possible to know whether it is in the lighting state or in the no-load state. The output difference of the averaging circuit 5 (or the averaging circuit 6) when lighting and no load is large and easy to distinguish, and the size of the stray capacitance etc. changes and the frequency of the oscillating current waveform changes. However, the integrated value at the time of no load is substantially 0, and does not affect the accuracy of non-lighting detection.

  Further, as described above, according to the discharge lamp device according to the invention of the third embodiment, as shown in FIG. 13A, the output of the averaging circuit 72 of the no-load detection circuit 7 during lighting is constant. On the other hand, as shown in FIG. 13B, the output of the averaging circuit 72 of the no-load detection circuit 7 at no load is substantially zero. By measuring the output of the averaging circuit 7, it is possible to know whether it is in a lighting state or in a no-load state. The output difference of the averaging circuit 72 during lighting and no load is large and easy to distinguish, and even when the size of the stray capacitance changes and the frequency of the oscillating current waveform changes, The integral value is approximately 0, and does not affect the accuracy of the non-lighting detection.

FIG. 14 shows the relative value of the time average value during no load with respect to the time average value during lighting in the averaging circuit of the discharge lamp device according to the invention of each of the first to third embodiments, and the prior art shown in FIG. It is the table | surface which showed the relative value of the time average value at the time of no load with respect to the time average value at the time of lighting in the averaging circuit of the discharge lamp apparatus which concerns on a technique.
As shown in the figure, in the discharge lamp devices according to the embodiments of the present invention, the relative value is 9%, and the difference between lighting and no load is 90% or more. Is big. In addition, even if the size of the stray capacitance changes, there is almost no effect on the size of the integrated value when there is no load, so that the difference between lighting and no load is not reduced. This is also clear by comparing and observing the input signal waveform input to the averaging circuit shown in FIG. 12 (a) and FIG. 12 (b) or FIG. 13 (a). On the other hand, in the discharge lamp device according to the prior art, the relative value is 65.3%, and the difference between lighting and no load is about 35%, so the tolerance for variation is small. Further, when the magnitude of the stray capacitance or the like changes, the current waveform at the time of no load changes and the integrated value changes, so that the difference between lighting and no load may be reduced. This is also clear by comparing and observing the input signal waveform input to the averaging circuit shown in FIGS. 20 (a) and 20 (b).

In the first to third embodiments, the AC conversion circuit 2 is configured by a full bridge method. However, the present invention is not limited to this, and the AC conversion circuit 2 may be configured by a push-pull method.
FIG. 15 is a diagram illustrating a circuit configuration of a discharge lamp device in which the AC conversion circuit 2 is configured by a push-pull method and a no-load detection circuit is omitted.
In the figure, here, one switching element Q1 is a first switching element, and the other switching element Q2 is a second switching element. The first current path is a path through which a current flows when the first switching element Q1 is turned on. This current flows from the high potential side of the DC power supply 1 to the low potential of the transformer 3, the switching element Q1, and the DC power supply 1. And a path that goes around from the secondary HV terminal of the transformer 3 to the rare gas fluorescent lamp 4 and the secondary LV terminal of the transformer 3. The second current path is a path through which a current flows when the second switching element Q2 is on. This current flows from the high potential side of the DC power supply 1 to the low potential of the transformer 3, the switching element Q2, and the DC power supply 1. And a path that goes around from the LV terminal on the secondary side of the transformer 3 to the HV terminal on the secondary side of the rare gas fluorescent lamp 4 and transformer 3.

Moreover, you may comprise the alternating current converter circuit 2 by a half bridge system.
FIG. 16 is a diagram illustrating a circuit configuration of a discharge lamp device in which the AC conversion circuit 2 is configured by a half-bridge method and the no-load detection circuit is omitted.
In the figure, here, one switching element Q1 is a first switching element, and the other switching element Q2 is a second switching element. The first current path is a path through which a current flows when the first switching element Q1 is on. This current flows from the high potential side of the capacitor C1 to the low potential side of the switching element Q1, the transformer 3, and the capacitor C1. And a path that goes around from the secondary HV terminal of the transformer 3 to the rare gas fluorescent lamp 4 and the secondary LV terminal of the transformer 3. The second current path is a path through which a current flows when the second switching element Q2 is on. This current flows from the high potential side of the capacitor C2 to the primary side of the transformer 3, the switching element Q2, and the capacitor C2. A path that goes around to the low potential side and a path that goes around from the LV terminal on the secondary side of the transformer 3 to the HV terminal on the secondary side of the rare gas fluorescent lamp 4 and transformer 3 flow.

  In FIG. 15 and FIG. 16, the first current path and the second current path overlap at a place where a no-load detection circuit corresponding to the no-load detection circuit 5 in the discharge lamp device of the first embodiment is inserted. In addition, the first current flowing when the first switching element is turned on and the first current flowing when the second switching element is turned on may be provided anywhere as long as the directions are opposite to each other. . In addition, a place where a no-load detection circuit corresponding to the no-load detection circuit 6 in the discharge lamp device of the second embodiment is inserted may be in a path where the first current path and the second current path do not overlap each other. Anywhere. Furthermore, in the place where the no-load detection circuit corresponding to the no-load detection circuit 7 in the discharge lamp device of the third embodiment is inserted, the first current path and the second current path overlap, and the first It may be provided anywhere as long as the current flowing first after the switching element is turned on and the current flowing first after the second switching element is turned on are in the same path.

The discharge lamp device of the present invention can also be applied to an excimer lamp instead of the rare gas fluorescent lamp.
FIG. 17 is a schematic cross-sectional view showing an example of an excimer lamp. As shown in the figure, this excimer lamp is of a cylindrical external radiation type, and the discharge vessel 46 is made of a dielectric such as quartz glass. The discharge vessel 46 includes a cylindrical outer wall 461, a cylindrical inner wall 462 having a common cylindrical axis inside thereof, and sealing walls 463 and 464 that seal the outer wall 461 and the inner wall 462 at both ends. A cylindrical area surrounded by these walls becomes a discharge space S. A net-like first electrode 47 is provided in close contact with the surface of the outer wall 461, and a second electrode 48 made of aluminum or the like is provided in close contact with the surface of the inner wall 462 on the cylinder axis side. A high frequency power supply 8 is connected between the first and second electrodes. When a high frequency voltage is applied between the first electrode 47 and the second electrode 48 by the high frequency power supply 8, a large number of diameters of about 0.02 to 0.2 mm due to dielectric barrier discharge are generated in the discharge space S. Microplasma is generated. As a result, excimer is generated in the discharge space S, and excimer light is emitted. This excimer light passes through the outer wall 461 and is emitted to the outside through the mesh of the first electrode 47. As the discharge gas sealed in the discharge space S, a rare gas or a mixed gas of a rare gas and a halogen gas is used, but excimer light having different emission center wavelengths is emitted by changing the type of the discharge gas. be able to. When a rare gas such as xenon (Xe), krypton (Kr), or argon (Ar) is used as the discharge gas, excimer light having emission center wavelengths of 172 nm, 146 nm, and 126 nm can be obtained. When a mixed gas of krypton (Kr) and chlorine (Cl) gas is used, excimer light having an emission center wavelength of 222 nm can be obtained.

It is a figure which shows the circuit structure of the discharge lamp apparatus which concerns on invention of 1st Embodiment. It is a figure which shows the structure of the noble gas fluorescent lamp 4 shown in FIG. 2 is a diagram showing an equivalent circuit of a rare gas fluorescent lamp 4. FIG. FIG. 2 is a circuit diagram showing a specific configuration of a no-load detection circuit 5 shown in FIG. 1. It is a timing chart for demonstrating the circuit operation | movement of the discharge lamp apparatus shown in FIG. It is a figure which shows the circuit structure of the discharge lamp apparatus which concerns on invention of 2nd Embodiment. It is a circuit diagram which shows the specific structure of the no-load detection circuit 6 shown in FIG. It is a timing chart for demonstrating the circuit operation | movement of the discharge lamp apparatus shown in FIG. It is a figure which shows the circuit structure of the discharge lamp apparatus which concerns on invention of 3rd Embodiment. 10 is a timing chart for explaining a circuit operation of the discharge lamp device shown in FIG. 9. In the discharge lamp apparatus according to the invention of the first to third embodiments, the current waveform flowing on the secondary side of the transformer 3 when the rare gas fluorescent lamp 4 is turned on, and the transformer 3 when the rare gas fluorescent lamp 4 is unloaded. It is a figure which shows the electric current waveform which flows into the secondary side. In the discharge lamp apparatus according to the first (or second) embodiment of the invention, the averaging circuit 53 (or the no-load detection circuit 6) of the no-load detection circuit 5 when the noble gas fluorescent lamp 4 is turned on and when there is no load. It is a figure which shows the electric current waveform of the input signal input into the averaging circuit 62). The figure which shows the electric current waveform of the input signal input into the averaging circuit 72 of the no-load detection circuit 7 at the time of lighting of the noble gas fluorescent lamp 4 and no load in the discharge lamp device according to the invention of the third embodiment. It is. In the averaging circuit of the discharge lamp device according to the invention of each of the first to third embodiments and the discharge lamp device according to the prior art shown in FIG. 17, the time average value at no load relative to the time average value at the time of lighting It is the table | surface which showed the relative value. It is a figure which shows the circuit structure of the discharge lamp apparatus which comprises AC conversion circuit 2 by a push pull system and abbreviate | omitted the no-load detection circuit. It is a figure which shows the circuit structure of the discharge lamp apparatus which comprises AC conversion circuit 2 by a half-bridge system and abbreviate | omitted the no-load detection circuit. It is a schematic sectional drawing which shows an example of an excimer lamp. It is a figure which shows the circuit structure of the discharge lamp apparatus which concerns on a prior art. FIG. 19 is a circuit diagram showing a specific configuration of a no-load detection circuit 105 shown in FIG. 18. In the discharge lamp apparatus shown in FIG. 18, the current waveform of the input signal input to the averaging circuit 108 of the no-load detection circuit 105 when the rare gas fluorescent lamp 104 is turned on, and when the rare gas fluorescent lamp 104 is not loaded. 6 is a diagram illustrating a current waveform of an input signal input to an averaging circuit 108 of a no-load detection circuit 105. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC power supply 2 AC conversion circuit 21 Switching element drive circuit 22 RS flip-flop 3 Transformer 4 Noble gas fluorescent lamp 41 Glass tube 42 Fluorescent material 43, 44 External electrode 45 Easy start part 46 Discharge vessel 461 Outer wall 462 Inner walls 463, 464 Sealing Wall 47 First electrode 48 Second electrode 5 No-load detection circuit 51 Current waveform detection circuit 52 Switch circuit 53 Averaging circuit 54 Comparison circuit 6 No-load detection circuit
61 Current waveform detection circuit 62 Averaging circuit 63 Comparison circuit 7 No load detection circuit 71 Current waveform detection circuit 72 Averaging circuit 73 Comparison circuit 8 High frequency power supplies Q11, Q12, Q21, Q22 Switching elements D11, D12, D21, D22 Diodes

Claims (6)

An alternating current conversion circuit for converting a direct current voltage into an alternating current voltage by alternately switching one or one set of first switching elements and the other or the other set of second switching elements; and alternating current from the alternating current conversion circuit In a discharge lamp device comprising a transformer for boosting voltage and a rare gas fluorescent lamp connected to the secondary side of the transformer,
Means for detecting a current flowing during a substantially half cycle of the AC voltage including an ON period of the first switching element and not including an ON period of the second switching element; and an averaging circuit for averaging the detected current And a no-load detection circuit comprising a comparison circuit that compares the output value of the averaging circuit with a reference value. An alternating current conversion circuit for converting a direct current voltage into an alternating current voltage by alternately switching one or one set of first switching elements and the other or the other set of second switching elements; and alternating current from the alternating current conversion circuit In a discharge lamp device comprising a transformer for boosting voltage and a rare gas fluorescent lamp connected to the secondary side of the transformer,
The first current path that flows when the first switching element is on and the second current path that flows when the second switching element are on overlap, and the first current path and the second current path are A current waveform detection circuit connected in series to current paths in which flowing currents are in opposite directions, and an abbreviation of the AC voltage that includes the ON period of the first switching element and does not include the ON period of the second switching element. A switch circuit that passes the current waveform signal detected by the current waveform detection circuit for a half cycle, an averaging circuit that averages the current waveform signal that has passed through the switch circuit, and an output value of the averaging circuit as a reference value A discharge lamp device comprising a comparison circuit for comparing with a no-load detection circuit.   The discharge lamp device according to claim 2, wherein a current waveform detection circuit of the no-load detection circuit is connected to a secondary side of the transformer. An alternating current conversion circuit for converting a direct current voltage into an alternating current voltage by alternately switching one or one set of first switching elements and the other or the other set of second switching elements; and alternating current from the alternating current conversion circuit In a discharge lamp device comprising a transformer for boosting voltage and a rare gas fluorescent lamp connected to the secondary side of the transformer,
A current waveform detection circuit connected in series to a current path that does not overlap a first current path that flows when the first switching element is on and a second current path that flows when the second switching element is on; A no-load detection circuit comprising an averaging circuit that averages current waveform signals detected by the current waveform detection circuit, and a comparison circuit that compares an output value of the averaging circuit with a reference value is provided. Discharge lamp device. An alternating current conversion circuit for converting a direct current voltage into an alternating current voltage by alternately switching one or one set of first switching elements and the other or the other set of second switching elements; and alternating current from the alternating current conversion circuit In a discharge lamp device comprising a transformer for boosting voltage and a rare gas fluorescent lamp connected to the secondary side of the transformer,
The first current path that flows when the first switching element is on and the second current path that flows when the second switching element are on overlap, and the first current path and the second current path are A current waveform detection circuit connected in series to current paths in which flowing currents are in the same direction, an averaging circuit that averages the current waveform signals detected by the current waveform detection circuit, and an output value of the averaging circuit A discharge lamp device comprising a no-load detection circuit comprising a comparison circuit for comparing the voltage with a reference value.   The discharge lamp device according to any one of claims 1 to 5, wherein an excimer lamp that irradiates ultraviolet rays is used instead of the rare gas fluorescent lamp.

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