WO2003013195A1

WO2003013195A1 - Discharge lamp operating device

Info

Publication number: WO2003013195A1
Application number: PCT/JP2001/006466
Authority: WO
Inventors: Shinsuke Funayama; Osamu Takahashi; Yoshitaka Igarashi; Naoki Wada
Original assignee: Mitsubishi Denki Kabushiki Kaisha; Mitsubishi Electric Lighting Corporation
Priority date: 2001-07-27
Filing date: 2001-07-27
Publication date: 2003-02-13
Also published as: JP5019694B2; JPWO2003013195A1

Abstract

A protection circuit (3) for a discharge lamp operating device comprises a voltage detecting circuit (4) including voltage dividing resistors (R11, R12) for which a predetermined voltage division ratio is set and a Zener diode (DZ) connected in series with the voltage dividing resistors (R11, R12).

Description

TECHNICAL FIELD The present invention relates to a discharge lamp lighting device for lighting a lamp with high-frequency power generated by an inverter, and particularly to a protection circuit for detecting abnormal discharge at the end of lamp life to protect the inverter. And a discharge lamp lighting device. BACKGROUND ART FIG. 7 is a circuit diagram showing an outline of a conventional discharge lamp lighting device. The discharge lamp lighting device shown in this figure is a half-bridge type inverter, in which switching elements Ql and Q2 connected in series to DC power supply E and lamp 1 connected in parallel with switching element Q2 are connected in series. Inductor L 1 and capacitors C 1 and C 2, oscillation circuit 2 that turns on and off switching elements Q 1 and Q 2 alternately with high-frequency signals, and abnormal discharge at the end of lamp 1 life And a protection circuit 3 for protection. The protection circuit 3 shuts off the output of the voltage detection circuit 4, the abnormal voltage detection circuit 5 that turns off the output when the voltage value detected by the voltage detection circuit 4 is equal to or more than a predetermined value, and the abnormal voltage detection circuit 5. And the oscillation stop circuit 6, which stops the operation of the oscillation circuit 2 when the operation is performed.

The voltage detection circuit 4 described above includes capacitors C3 and C4 for dividing the sum voltage of the lamp voltage and the charging voltage of the capacitor C2 (coupling capacitor), and peak-divided voltages by the capacitors C3 and C4. Diodes D 1 and D 2 detected by peak and peaks V 1 and V 2 detected by these diodes D l and D 2 (VI: voltage when the lamp is operating normally, V2: voltage when the lamp is abnormally operating) , For example, to divide the voltage by 1/2, and a smoothing capacitor C5 for smoothing the divided voltages VI1, V21. Note that this smoothing capacitor C5 has a capacity to be fully charged with a delay determined by the time constant of the resistor R1 so that the abnormal voltage detection circuit 5 does not malfunction due to a high voltage at the time of starting the lamp. The abnormal voltage detection circuit 5 includes a Zener diode (not shown) that conducts when a voltage equal to or higher than the X-ner voltage (predetermined value), that is, a voltage V 21 when the lamp is abnormally turned on, and a Zener diode And a transistor (not shown) that turns on and turns off the output when the diode 5a operates.

Next, the operation of the protection circuit of the conventional discharge lamp lighting device will be described.

The high-frequency voltage (sum of the lamp voltage and the charging voltage of the capacitor C2) applied to the lamp 1 by the alternating on / off operation of the switching elements Q1 and Q2 is converted to the capacitors C3 and C4 of the voltage detection circuit 4. The diodes D 1 and D 2 detect the divided voltage peak-to-peak to generate full-wave rectification. Then, these full-wave rectified voltages VI and V 2 are divided (V 11, V 21) by approximately 1 × 2 by the voltage dividing resistors R l and R 2, and the voltages VI 1 and V 2 1 is smoothed by the smoothing capacitor C5 and applied to the Zener diode of the abnormal voltage detection circuit 5.

The zener diode of the abnormal voltage detection circuit 5 does not conduct when the DC voltage smoothed by the smoothing capacitor C5 does not reach the zener voltage, but when the DC voltage is equal to or more than the zener voltage, a transistor (not shown) is used. ) Turn on to shut off the output. At this time, the oscillation stop circuit 6 stops the oscillating operation of the oscillating circuit 2 and stops the on / off operations of the switching elements Ql and Q2.

In the protection circuit of the conventional discharge lamp lighting device described above, the voltages V 1 and V 2 detected peak-to-peak by the capacitors C 3 and C 4 and the diodes D 1 and D 2 are substantially changed by the resistances 1 and R 2. Since the voltage is divided so as to be halved, as shown in Fig. 8, the peak voltage V1 when the lamp is lit normally becomes the voltage V11 (both ends of the resistor R2), and the peak voltage V2 when the lamp is lit abnormally is The voltage V 21 was obtained, and the voltage level difference V 3 between the respective voltages VII and V 21 also became smaller at the same ratio. Therefore, if there is an error (variation voltage) in the Zener voltage of the Zener diode of the abnormal voltage detection circuit 5, the Zener diode 5a conducts at the voltage V11 when the lamp is normally lit. Therefore, there is a problem that the oscillation circuit 2 is stopped, or the voltage V 21 when the lamp is abnormally turned on does not reach the zener voltage of the zener diode 5a. The present invention has been made in order to solve such a problem, and even if there is an error in the zener-diode zener voltage of the abnormal voltage detection circuit, the lamp malfunctions when the lamp is normally turned on or operates when the lamp is abnormally turned on. The purpose is to provide a discharge lamp lighting device that has never been found. DISCLOSURE OF THE INVENTION The discharge lamp lighting device according to claim 1 of the present invention comprises an inverter for applying a voltage to the discharge lamp based on an oscillation frequency of an oscillation circuit, and a voltage dividing the voltage applied to the discharge lamp for direct current. A voltage detecting circuit having a voltage converting section for converting the DC voltage converted by the voltage converting section, and a voltage dividing section for dividing the DC voltage converted by the voltage converting section; An abnormal voltage detection circuit that stops the oscillation circuit when the zener voltage of the zener diode is equal to or higher than a zener voltage, and a voltage dividing unit of the voltage detection circuit includes a voltage divided when the discharge lamp is normally turned on and abnormal discharge light of the discharge lamp. The DC voltage converted by the voltage converter is set so that the difference between the voltage and the divided voltage at the time is large, and the voltage divided at the time of abnormal lighting of the discharge lamp is equal to or more than the energy voltage of the energy diode. Those with a value content cutlet Bok constant voltage element, the remaining a partial dividing resistors at a predetermined division ratio of the voltage across the constant voltage element. This eliminates malfunctions during normal operation of the discharge lamp and malfunctions during abnormal operation of the discharge lamp, and also prevents inversion and damage to the discharge lamp socket due to reliable protection. it can. In addition, since only a constant voltage element is inserted, the solution can be achieved with a low-cost and simple circuit configuration.

In the discharge lamp lighting device according to claim 2 of the present invention, the voltage conversion unit of the voltage detection circuit includes a voltage dividing resistor that divides a voltage applied to the discharge lamp, and a voltage divided by the voltage dividing resistor. And a rectifying element for direct current. With this, it is possible to prevent a malfunction when the discharge lamp is normally lit and a failure to operate when the discharge lamp is illuminated abnormally with a simple circuit configuration.

A discharge lamp lighting device according to claim 3 of the present invention includes an inverter that applies a voltage to the discharge lamp based on an oscillation frequency of an oscillation circuit, and a voltage that is applied to the discharge lamp to divide the voltage. A voltage detecting circuit having a voltage converting section for converting to direct current and a voltage dividing section for dividing the DC voltage converted by the voltage converting section; and a zener diode, wherein the voltage divided by the voltage dividing section of the voltage detecting circuit is An abnormal voltage detecting circuit that stops the oscillation circuit when the Zener voltage of the Zener diode is higher than or equal to the Zener voltage, wherein a voltage converter of the voltage detecting circuit divides a voltage applied to the discharge lamp side; A pair of constant voltage elements that are connected in series and cut a voltage divided by a capacitor by a predetermined value, and a rectifying element that converts the remaining voltage via the constant voltage element to DC. The part consists of a voltage-dividing resistor that divides the voltage converted to DC by the rectifier element. Large difference between the divided voltage at the time of lighting, and in which the voltage divided at the discharge lamp abnormality lighting was set to above Tsuena voltage of the Dzuena one diode. This eliminates malfunctions during normal operation of the discharge lamp and malfunctions during abnormal operation of the discharge lamp.In addition, reliable protection prevents failure of the inverter and damage to the discharge lamp socket. it can. In addition, since only a constant voltage element is inserted, there is an effect that it can be solved with a low-cost and simple circuit configuration.

In the discharge lamp lighting device according to claim 4 of the present invention, the voltage conversion unit of the voltage detection circuit includes a voltage dividing resistor that divides a voltage applied to the discharge lamp side, and a voltage dividing resistor connected in series with the voltage dividing resistor. It comprises a constant voltage element for cutting the voltage divided by the piezoresistor by a predetermined value, and a rectifying element for converting the remaining voltage via the constant voltage element to DC. As a result, it is possible to prevent a malfunction when the discharge lamp is normally lit and a malfunction when the discharge lamp is abnormally lit. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram schematically showing a discharge lamp lighting device according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram of detected voltages at the time of normal lamp lighting and at the time of abnormal lamp lighting in the first embodiment.

FIG. 3 is a circuit diagram showing an outline of the discharge lamp lighting device according to the second embodiment. FIG. 4 is a circuit diagram showing an outline of the discharge lamp lighting device according to the third embodiment.

FIG. 5 is an explanatory diagram of detected voltages at the time of normal lamp lighting and at the time of abnormal lamp lighting in the third embodiment.

FIG. 6 is a circuit diagram showing an outline of a discharge lamp lighting device according to Embodiment 4.

FIG. 7 is a circuit diagram showing an outline of a conventional discharge lamp lighting device.

FIG. 8 is an explanatory diagram of the detected voltage at the time of normal lamp lighting and the abnormal lamp lighting of the conventional discharge lamp lighting device. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, some embodiments of the present invention will be described with reference to the drawings. The same or corresponding parts as those in the conventional example described with reference to FIG. Embodiment 1

The discharge lamp lighting device shown in Fig. 1 is a half-bridge type inverter. In the protection circuit 3, a voltage dividing resistor with a predetermined voltage dividing ratio set: R11, R12, and this voltage dividing resistor R1 1, a voltage detection circuit 4 having, for example, a Zener diode DZ connected in series to R12. The zener diode DZ has a zener voltage VZ, and the full-wave rectified voltages VI and V2 (VI: when the lamp is normally lit) converted by the capacitors C3 and C4 and the diodes D1 and D2. This is to cut off the voltage of V2 (voltage at lamp abnormal lighting) by one zener voltage VZ. This is determined by adjusting the voltage divider resistors R ll and R 12 so that the voltage at both ends of the resistor: R 12 when the lamp lights up normally and V 2 when the lamp abnormally lights up This is to increase the voltage level difference V4 from 2 (see Fig. 2). The larger the zener voltage VZ of the zener diode DZ, the larger the voltage level difference between the voltage VI2 during normal lamp operation and the voltage V22 during abnormal lamp operation can be obtained.

In the first embodiment, for example, the voltage V 12 detected when the lamp is lit normally is set to be substantially the same voltage level (VI 1) as the conventional one, and the voltage V 22 detected when the lamp is lit abnormally is abnormal. Zener diode provided in voltage detection circuit 5 (illustrated The value of the Zener voltage VZ of the Zener diode DZ and the resistance of each of the voltage dividing resistors R11 and R12 are adjusted so that the variation voltage of the Zener voltage does not exceed the voltage of the Zener diode DZ. If the voltage V12 detected when the lamp is normally turned on is set to be substantially the same as the conventional voltage level, the voltage dividing ratio of the voltage dividing resistors R11 and R12 becomes the conventional voltage dividing resistor Rl, described in FIG. It is larger than the partial pressure ratio of R2.

In the discharge lamp lighting device configured as described above, the high-frequency voltage at the time of normal lamp lighting is divided by the capacitors C3 and C4, and converted to the full-wave rectified voltage V1 by the diodes Dl and D2. Is done. Then, this voltage VI is cut by the Zener diode DZ by one zener voltage VZ as shown in the following equation (1), and the remaining voltage of the voltage V1 is divided by the voltage dividing resistors R11 and R12. The voltage becomes V12.

V 12 = (V 1 -VZ) xR 12 / (R 11 + R 12)… (1) Then, the divided voltage VI 2 is smoothed by the smoothing capacitor C 5, and the abnormal voltage detection circuit 5 Applied to the diode. In this case, since the smoothed voltage VI 2 is lower than the Zener voltage of the Zener diode, the output of the abnormal voltage detection circuit 5 is held, and the ON / OFF of the switching elements Q 1 and Q 2 by the oscillation circuit 2 is performed. The off control is continued.

Further, the high-frequency voltage at the time of abnormal lamp lighting is divided by the capacitors C3 and C4 in the same manner as described above, and is converted into the full-wave rectified voltage V2 by the diodes D1 and D2. This voltage V 2 is cut by a zener diode DZ by a zener diode DZ as shown in the following equation (2), and the remaining voltage of the voltage V 2 is divided by a voltage dividing resistor R 11,: 12. The voltage is divided to V22.

Ί 22: (V2 -VZ) xR 12 / (R 11 + R 12)… (2) The divided voltage V 22 is smoothed by the smoothing capacitor C 5, and the zener diode of the abnormal voltage detection circuit 5 Is applied to In this case, since the smoothed voltage V22 is equal to or higher than the Zener voltage of the Zener diode, the transistor (not shown) of the abnormal voltage detection circuit 5 is turned on to cut off the output. At this time, the oscillation stop circuit 6 stops the oscillation operation of the oscillation circuit 2 and stops the ON and OFF operations of the switching elements Ql and Q2. As described above, according to the first embodiment, the voltages V 1 and V 2 detected by the capacitors C 3 and C 4 and the diodes D 1 and D 2 are divided by the zener diode DZ into the zener voltage VZ. Since the remaining voltage is divided by the voltage dividing resistors R11 and R12, the voltage level difference V4 between the voltage V12 detected during normal lamp operation and the voltage V22 detected during abnormal lamp operation is increased. This makes it possible to eliminate the malfunction of the protection circuit 3 when the lamp is operating normally and that the protection circuit 3 did not operate when the lamp is abnormally turned on. Failure and damage to the lamp socket can be prevented. Also, since only a penetrating diode DZ is introduced, there is an effect that it can be solved with a low-cost and simple circuit configuration. '

In the first embodiment, the voltage V12 detected when the lamp is normally turned on is set to be substantially the same voltage level (VI1) as before, and the voltage V22 detected when the lamp is abnormally turned on is The value of the zener-voltage VZ of the zener-diode DZ and the resistance of each of the voltage dividing resistors R11 and R12 are set so as to be more than the variation voltage of the zener-voltage of the zener-diode provided in the abnormal voltage detection circuit 5. The value of the Zener voltage VZ of the Zener diode DZ and the voltage divider resistor Rl are set so that the voltage V22 detected when the lamp is abnormally turned on is almost the same voltage level (V21) as before. You may make it adjust each resistance value of l and R12. In this case, the voltage dividing ratio of the voltage dividing resistors R11 and R12 is smaller than that of the first embodiment. Embodiment 2.

In the first embodiment described above, the high-frequency voltage applied to the lamp 1 is converted into the voltages VI and V2 by the capacitors C3 and C4 and the diodes Dl and D2. As shown in Fig. 7, instead of the capacitors C3 and C4, voltage dividing resistors R13 and R14 are used, and the voltages VI and V2 divided by the voltage dividing resistors R13 and R14 are halved by the diode D2. Wave rectification is performed. The operation and effect of the second embodiment are the same as those of the first embodiment. Embodiment 3. In the third embodiment, as shown in FIG. 4, the Zener diodes DZ 1 and DZ 2 are connected between the capacitors C 3 and C 4 for dividing the high-frequency voltage applied to the lamp 1 so that the anodes face each other. Is inserted. The Zener diodes DZ 1 and DZ 2 have, for example, the same Zener voltage VZ as the Zener diode DZ used in the first embodiment, and have a Zener diode with respect to the voltage divided by the capacitors C 3 and C 4. The voltage VZ component is reduced.

When the zener diodes DZ1 and DZ2 are used to cut the high-frequency voltage divided when the lamp is normally lit as shown in Fig. 5 (a), the cutoff is divided by the penalty voltage VZ (shaded area), as shown in Fig. 5 (c). As shown in Fig. 5 (b), when the high-frequency voltage divided when the lamp is abnormally turned on is cut by a phantom voltage VZ (shaded area) as shown in Fig. 5 (b), the waveform becomes as shown in Fig. 5 (d) It becomes a waveform. As shown in (c) and (d), the voltage level difference V5 between the waveform when the lamp is lit normally and the waveform when the lamp is lit abnormally is larger than the voltage level difference V6 shown in (g) and (h). I'm sorry.

The waveform shown in (g) is obtained by dividing the waveform (e) when the lamp is lit normally by the capacitors C3 and C4, and the waveform shown in (h) is the waveform (f) when the lamp is lit abnormally. The voltage is divided by capacitors C3 and C4.

In the third embodiment, when the high-frequency voltage applied to the lamp 1 is divided by the capacitors C 3 and C 4, the zener voltage VZ is cut by the zener diodes DZ 1 and DZ 2. The voltage level difference between the waveform when the lamp is lit normally and the waveform when the lamp is lit abnormally can be made large, so that the protection circuit 3 malfunctions when the lamp is lit normally and protects when the lamp is lit abnormally. The fact that the circuit 3 did not operate is eliminated, and furthermore, since the protection is assured, the circuit failure and the damage to the lamp socket can be prevented. Embodiment 4.

In Embodiment 3 described above, two Zener diodes DZ 1 and DZ 2 were inserted between the capacitors C 3 and C 4 that divide the high-frequency voltage applied to the lamp 1. In the fourth embodiment, voltage dividing resistors R 13 and R 14 are used instead of the capacitors C 3 and C 4, and the voltage in only one direction of the high-frequency voltage is set to the Zener voltage V It is a Z component, a twisted diode DZ 1 inserted between its voltage dividing resistors R 13 and R 14.

In the fourth embodiment, the high-frequency voltage applied to the lamp 1 is divided by the voltage dividing resistors: 13 and R 14, and the divided one-way voltage is converted by the diode DZ 1 into the antenna. Since one voltage VZ is added, the remaining voltage is divided by the voltage dividing resistors R 11 and R 12, smoothed by the smoothing capacitor C 5, and applied to the abnormal voltage detection circuit 5.

As described above, since the zener diode DZ1 is inserted between the voltage dividing resistors R13 and R14, the voltage level difference between the voltage when the lamp is normally turned on and the voltage when the lamp is abnormally turned on is calculated. As a result, the protection circuit 3 does not malfunction when the lamp is lit normally, and the protection circuit 3 does not operate when the lamp is lit abnormally. And damage to the lamp socket. In each of the above-described embodiments, a description has been given by applying the invention to the half-bridge type inverter circuit.However, a circuit for turning on the lamp 1 using the resonance of the inductor L1 and the capacitors C1 and C2, For example, the present invention may be applied to a single-stone resonance type room.

Claims

The scope of the claims

1. Apply the voltage to the discharge lamp based on the oscillation frequency of the oscillation circuit.

A voltage conversion unit that divides the voltage applied to the discharge lamp and converts the voltage to DC, a voltage detection circuit that has a voltage division unit that divides the DC voltage converted by the voltage conversion unit, and a zener diode. An abnormal voltage detection circuit that stops the oscillation circuit when the voltage divided by the voltage division unit of the voltage detection circuit is equal to or higher than the zener voltage of the zener diode,

The voltage dividing section of the voltage detection circuit has a large difference between the voltage divided when the discharge lamp is normally turned on and the voltage divided when the discharge lamp is abnormally turned on. A constant voltage element for cutting the DC voltage converted by the voltage converter by a predetermined value so as to be equal to or higher than the diode voltage of the diode, and a remaining voltage via the constant voltage element at a predetermined voltage dividing ratio. A discharge lamp lighting device comprising a voltage dividing resistor for dividing a voltage.

2. The voltage conversion unit of the voltage detection circuit includes a voltage dividing resistor that divides a voltage applied to the discharge lamp side, and a rectifying element that converts the voltage divided by the voltage dividing resistor into DC. The discharge lamp lighting device according to claim 1, characterized in that:

3. Inverter that applies a voltage to the discharge lamp based on the oscillation frequency of the oscillation circuit, a voltage converter that divides the voltage applied to the discharge lamp and converts the voltage to DC, and the voltage converted by the voltage converter. A voltage detecting circuit having a voltage dividing section for dividing the DC voltage, and a zener diode, wherein the oscillation circuit is provided when the voltage divided by the voltage dividing section of the voltage detecting circuit is equal to or higher than the Zener voltage of the Zener diode. An abnormal voltage detection circuit for stopping

The voltage conversion unit of the voltage detection circuit includes a capacitor that divides the voltage applied to the discharge lamp side, and a pair of constants that are connected in series with the capacitor and cut the voltage divided by the capacitor by a predetermined value. A voltage element; and a rectifying element for converting the remaining voltage via the constant voltage element to DC. The voltage dividing unit includes a voltage dividing resistor for dividing the voltage converted to DC by the rectifying element.

The voltage divided by the voltage conversion unit and the voltage dividing unit when the discharge lamp is normally turned on and the discharge lamp A discharge lamp lighting device characterized in that the difference between the voltage and the voltage divided during abnormal lighting is large, and the voltage divided during abnormal lighting of the discharge lamp is equal to or higher than the zener voltage of the zener diode.

4. The voltage conversion unit of the voltage detection circuit includes a voltage dividing resistor that divides a voltage applied to the discharge lamp, and a voltage dividing unit that is connected in series to the voltage dividing resistor and determines the voltage divided by the voltage dividing resistor. 4. The discharge lamp lighting device according to claim 3, further comprising: a constant voltage element that cuts by a value, and a rectifying element that converts the remaining voltage via the constant voltage element to DC.