JP2006147367A - Pulse generation circuit, discharge lamp lighting device and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse generation circuit which can certainly turn off a thyristor after a lamp starts, prevents a resistor for supplying a power from being deteriorated by heating the resistor and can prevent that a wasteful power consumption occurs and to provide a discharge lamp lighting device and a lighting system. <P>SOLUTION: In the pulse generation circuit having a second capacitor C12 and the thyristor D12 which constitute a closed circuit with the primary winding of the transformer T1, a resistor R13 for supplying the power to the C12, and a control means for controlling on timing of the D12, a timer means for measuring the time duration in which a voltage is applied to an R13, and a means SW11 connected in series with the R13 to shut off the charging current of the C12 from the power supply when the timer means detects that a voltage is applied to the R13 beyond a fixed time duration from the time of the pulse generation in the primary winding are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pulse generation circuit, a discharge lamp lighting device, and an illumination device for starting and lighting a high-intensity discharge lamp (hereinafter, HID lamp).

  Conventionally, an igniter is used as a high-pressure pulse generating means for starting and lighting an HID lamp. The igniter includes a capacitor, a pulse transformer, and a switching element.

  As the igniter switching element, a large-capacity switching element such as a triac or thyristor is used. However, such an element cannot be turned off by an external signal, and the current flowing through the element falls below a certain value (holding current). Turn off.

  In a discharge lamp lighting device for an HID lamp, by applying the energy stored in the capacitor to the primary winding of the pulse transformer by turning on the thyristor, a voltage corresponding to an approximate turn ratio is generated in the secondary winding of the pulse transformer. The lamp can be started by being applied to the lamp. After turning on, a reverse voltage (voltage on the negative side of the oscillating voltage) is applied to the thyristor by an oscillating voltage (resonant voltage) by the primary winding of the capacitor and the pulse transformer, and the thyristor is turned off. As a simple method for storing energy in the capacitor at that time, there is a method of supplying a current from a power source through a resistor.

  However, since the current starts to flow in the secondary winding of the pulse transformer at the time of starting the lamp, the inductance seen from the primary winding becomes low. As a result, resonance hardly occurs and the time of the reverse voltage applied to the thyristor is shortened. Therefore, the thyristor may not be turned off. Furthermore, thyristors are less likely to turn off at higher temperatures due to their characteristics. As a result, if the thyristor cannot be turned off and continues to be turned on, a resistor for supplying power is heated to cause deterioration as a component, and wasteful power consumption occurs.

As a conventional high-pressure discharge lamp lighting device, in order to turn off the thyristor of the igniter, a bypass circuit for diverting the current to the thyristor is prepared, and after a predetermined time has elapsed since the thyristor was turned on, only for a certain period of time, There is one in which the thyristor can be turned off by driving (turning on) the bypass circuit so that the charging current becomes lower than the holding current (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-307285

  As described above, since the current flows without turning off the thyristor even after the lamp is started, the resistance for supplying power is heated to cause deterioration as a component, and wasteful power consumption occurs. was there.

  Therefore, in view of the above problems, the present invention can surely turn off the thyristor after starting the lamp, prevent the resistor for supplying power from being heated and causing deterioration, and prevent unnecessary power consumption from occurring. An object of the present invention is to provide a pulse generation circuit, a discharge lamp lighting device, and a lighting device that can be used.

  A pulse generation circuit according to a first aspect of the present invention includes a transformer in which a secondary winding is connected in series to a discharge lamp, and a pulse generated in the primary winding is boosted and output to the secondary winding; And a first capacitor connected in parallel with the series circuit of the secondary winding of the transformer; a second capacitor and a thyristor constituting a closed circuit with the primary winding of the transformer; and the second capacitor A resistor for supplying power; a control means for controlling the on-timing of the thyristor; a timer means for measuring a time during which a voltage is applied to the resistance; and connected in series to the resistor, and the timer means is not less than a predetermined time. And a blocking means for cutting off a charging current from the power source to the second capacitor when it is detected that a voltage is applied to the resistor.

  In the present invention, discharge lamps include HID lamps including mercury lamps, metal halide lamps, high pressure sodium lamps, and xenon lamps. The above matters also apply to the following inventions.

  According to the present invention, when the thyristor continues to be turned on without being turned off, a constant current flowing through the resistor flows. Therefore, the voltage generated in the resistor is detected, and the resistor detects the voltage from the resistor to the thyristor. The current that flows is cut off, the thyristor is turned off, and a high-pressure pulse can be generated again.

  According to a second aspect of the present invention, there is provided a pulse generation circuit comprising: a transformer having a secondary winding connected in series to a discharge lamp; a transformer for boosting and outputting a pulse generated in the primary winding to the secondary winding; And a first capacitor connected in parallel with the series circuit of the secondary winding of the transformer; a second capacitor and a thyristor constituting a closed circuit with the primary winding of the transformer; and the second capacitor A resistor for supplying power; a control means for controlling on-timing of the thyristor; a temperature detection unit for detecting a temperature of the resistor, and connected in series to the resistor, wherein the temperature of the resistor is equal to or higher than a predetermined value And a temperature-responsive switch element that cuts off a charging current from the power source to the second capacitor when it is detected.

  According to the present invention, when the thyristor continues to be turned on without being turned off, a constant current flowing through the resistor flows. Therefore, the temperature generated in the resistor is detected, and based on this temperature detection, the current flows from the resistor to the thyristor. The current is cut off, the thyristor is turned off, and a high voltage pulse can be generated again.

  A pulse generation circuit according to a third aspect of the present invention is the pulse generation circuit according to the second aspect, wherein the temperature-responsive switch element is a thermal protector.

  A discharge lamp lighting device according to a fourth aspect of the present invention is a DC voltage source that generates a DC voltage from an output of an AC power source; and is connected to the DC voltage source to generate AC power and maintain the lighting of the discharge lamp. An inverter circuit; and a pulse generation circuit according to any one of claims 1 to 3, which is incorporated in the inverter circuit and starts the discharge lamp with a boost pulse.

  According to the discharge lamp lighting device of the present invention, the thyristor can be surely turned off after the lamp is started, the resistance for supplying power is prevented from being heated and causing deterioration, and unnecessary power consumption is prevented from occurring. it can.

  According to a fifth aspect of the present invention, there is provided an illumination device comprising: the discharge lamp lighting device according to the fourth aspect; an HID lamp as a discharge lamp; and an appliance main body for holding the HID lamp.

  According to the lighting device of the present invention, the thyristor can be reliably turned off after the lamp is started, the resistance for supplying power can be prevented from being heated and causing deterioration, and wasteful power consumption can be prevented from occurring.

  According to the present invention, since the thyristor can be reliably turned off, the pulse is not stopped and the lamp can be reliably started. In addition, useless power consumption due to the resistance of the igniter after starting the lamp can be suppressed.

 Embodiments of the invention will be described with reference to the drawings.

1 is a circuit diagram showing a discharge lamp lighting device according to a first embodiment of the present invention.
In FIG. 1, a rectifier circuit 2 composed of a full-wave rectifier diode bridge is connected to both ends of an output end of a commercial AC power source 1 which is a low frequency (for example, 50 Hz) power source.

  A capacitor C5 is connected between the full-wave rectification output terminals of the rectifier circuit 2 as a high-frequency component passing filter accompanying high-frequency switching of an FET Q1, which is a switching element for high-frequency switching described later. Is connected to a step-up chopper circuit 3 that boosts the output voltage and outputs a stable DC voltage at a high power factor.

  The step-up chopper circuit 3 receives the full-wave rectified output from the rectifier circuit 2 under the control of the control circuit 7 and generates a stabilized DC voltage with a constant amplitude at a high power factor or a DC power source. It can be said. Note that an active filter circuit having only a part of the function of the step-up chopper circuit 3, that is, an input power factor improving function for matching the phase of the input AC current and the input AC power supply voltage, is provided between the full-wave rectification output terminals of the rectifier circuit 2. May be connected.

  The step-up chopper circuit 3 includes a coil L1 having one end connected to one output end (+ voltage output end in the figure) of the rectifier circuit 2, the other end of the coil L1, and the other output end of the rectifier circuit 2. FET Q1 as a high-frequency switching element having a drain / source connected between (the voltage output terminal in the figure), a commutation diode D5 having an anode connected to a connection point between the coil L1 and FET Q1, and the commutation diode And a series circuit of first and second smoothing capacitors C2 and C3 connected between the cathode of D5 and the negative voltage output terminal of the rectifier circuit 2.

  The control circuit 7 controls the ON period of the high-frequency switching FET Q1 according to the output voltage of the series circuit of the first and second smoothing capacitors C2 and C3 of the boost chopper circuit 3, so that the output voltage becomes a constant value. The feedback control is performed so that the amplitude level of the full-wave rectified voltage of the rectifier circuit 2 is monitored (voltage detection at the + voltage output terminal of the rectifier circuit 2) and the current level flowing through the coil L1 (coil L1) is controlled. The input power factor is improved to match the input AC current to the phase of the input AC voltage by controlling the ON period of the FET Q1 in accordance with the amplitude level of the full-wave rectified voltage. We are also controlling. Thereby, the boost chopper circuit 3 converts the full-wave rectified voltage into a stabilized DC voltage with a high power factor. Note that the switching frequency of the FET Q1 is several tens of kHz.

An inverter circuit 4 is connected to the subsequent stage of the boost chopper circuit 3.
The inverter circuit 4 is connected in parallel to both ends of a series circuit of smoothing capacitors C2 and C3 of the step-up chopper circuit 3, and FETQ2 as first and second switching elements that perform high-frequency (for example, several tens of kHz) switching operations. Connection point of the series circuit of Q3, the diodes D6 and D7 connected in parallel to the first and second FETs Q2 and Q3 in the direction opposite to the direction of the current of the FETs Q2 and Q3, and the series circuit of the FETs Q2 and Q3 And a coil L3 as an inductor, a starting step-up transformer T1 (secondary winding thereof), and an HID lamp 5 connected between the first and second smoothing capacitors C2 and C3. A series circuit including a series circuit, an igniter 6 connected to both ends of the primary winding of the transformer T1 to generate a high-voltage pulse for starting, and a secondary winding of the HID lamp 5 and the step-up transformer T1. On the other hand, a capacitor C4 for bypassing a high-frequency component due to high-frequency switching of the FETs Q2 and Q3 from a current flowing in the HID lamp 5 connected in parallel with the current detection value and voltage value of the HID lamp is superimposed. A series circuit of resistors R1, R2, and R3 for detecting a value (added value or integral value of both values), that is, an output of the lamp, and notifying the control circuit 7 of the detected value. When an FET is used as the switching element, a parasitic diode built in the FET is used for the reverse current conducting diodes D6 and D7, so that no special diode connection is required.

  The igniter 6 includes a transformer T1 in which a secondary winding is connected in series to the HID lamp 5, boosts and outputs a pulse generated on the primary winding side in the secondary winding, and a primary winding of the transformer T1. Capacitor C12 and thyristor D12 constituting a line and a closed circuit, diode D13, resistor R13 for supplying power to capacitor C12 for charging capacitor C12, and gate voltage to be applied to the gate of thyristor D12 are applied to determine the ON timing. Control means comprising resistors R11, R12, capacitor C11 and diac D11 for control, timer means (8-1, 8-2) for measuring the time during which voltage is applied to resistor R13, and resistor R13 When the timer means detects that a voltage is applied to the resistor R13 for a predetermined time or more, the charging current from the power source to the capacitor C12 is connected. A switch element SW11 as blocking means for disconnection, includes.

  The timer means includes a voltage detection unit 8-1 that detects the voltage across the resistor R13, and a control unit 8-2 that controls the switch element SW11 based on the detected voltage to shut off (turn off) the SW11. I have.

Next, the operation of the discharge lamp lighting device configured as described above will be described with reference to FIGS.
When the AC power supply is turned on in the discharge lamp lighting device of FIG. 1, a voltage obtained by dividing the rectified voltage by a resistance voltage dividing circuit (not shown) connected to both ends of the full-wave rectified output terminal of the rectifier circuit 2 is supplied to the control circuit 7. When the rectified voltage of the rectifier circuit 2 is supplied to the boost chopper circuit 3, the high frequency (several tens of kHz) switching operation of the FET Q1 of the boost chopper circuit 3 is started. At the same time when the start pulse is generated, the high frequency (several tens of kHz) on / off switching operation of the FETs Q2 and Q3 of the inverter circuit 4 is started. In the inverter circuit 4, a stabilized DC voltage is input from the boost chopper circuit 3, and first, the HID lamp 5 is started to break down with a high voltage pulse of the igniter 6, and the low voltage as shown in FIG. A high frequency alternating current is generated to turn on and maintain the HID lamp 5.

  In the step-up chopper circuit 3, energy is stored in the coil L1 when the FET Q1 is on, the diode D5 is conducted when the FET Q1 is off, and the energy stored in the coil L1 is converted into the first and second output capacitors. It discharges toward the series circuit of smoothing capacitors C2 and C3. At this time, since the voltage generated in the coil L1 is added in series to the input voltage, the output voltage is higher than the input voltage. When used as a high power factor chopper circuit, it is preferable to use in a current mode in which the energy stored in the coil L1 is completely discharged (that is, the current flowing through the coil L1 becomes zero).

  The control circuit 7 supplies a switching pulse to the gate of the FET Q1, which is a switching element. The ON period of the switching pulse is controlled according to the output voltages of the smoothing capacitors C2, C3, which are the output voltages of the boost chopper circuit 3. As a result, the on-time of the FET Q1 is PWM-controlled to control the output voltage of the output capacitors C2 and C3.

  In order to improve the input power factor, the on-time of the FET Q1 is controlled by the control circuit 7 detecting the amplitude level of the + full-wave rectified voltage of the rectifier circuit 2 and changing the on-time of the FET Q1 according to the amplitude level. Is also done. By controlling so that the on-time of the FET Q1 is shorter as the amplitude level of the rectified voltage is smaller and the on-time of the FET Q1 is longer as the amplitude level of the rectified voltage is larger, the waveform of the input AC current has a lower frequency (for example, 50 Hz). ) And is changed in synchronization with the waveform of the input AC voltage, and the input power factor is improved.

  When the step-up chopper circuit 3 starts operating as described above, power is supplied to the igniter 6 and at the same time, switching pulses are supplied to the FETs Q2 and Q3 which are the first and second switching elements. As a result, the igniter 6 generates a high-pressure pulse to place the HID lamp 5 in a discharged state (lighted state), and a high-frequency on / off switching pulse is applied to the FETs Q2 and Q3.

  2A shows the high frequency on / off operation of the FET Q2, and FIG. 2B shows the high frequency on / off operation of the FET Q3. FIG. 2C shows a low-frequency lamp current flowing through the HID lamp 5.

  At this time, the control circuit 7 controls the FETs Q2 and Q3 to alternately repeat the on / off operation of the respective high-frequency switching (for example, 50 kHz) at a constant frequency T of the low-frequency (for example, 100 Hz). Low-frequency AC power is supplied.

  The operation of the inverter circuit 4 will be described. First, the operation of turning on / off the FET Q2 during the period T will be described. When an ON pulse is applied to the gate of FETQ2 and FETQ2 is turned on, the charging voltage of the smoothing capacitor C2 is used as a power source, and current flows from C2 → Q2 → coil L3 → T1 → HID lamp 5 → R1 → C2 and FETQ2 is turned off. Then, the current stored in the coil L3 causes the current to flow through the coil L3 → T1 → HID lamp 5 → R1 → C3 → diode D7 → L3, so that the HID lamp 5 is always in the period T during which the FET Q2 is in a high frequency switching operation. Current flows in the direction of the coil L3 → HID lamp 5 → R1.

  In the next period T, the FET Q3 is turned on / off. When an ON pulse is applied to the gate of FET Q3 and FET Q3 is turned on, the current flows from C3 → R1 → HID lamp 5 → T1 → coil L3 → Q3 → C3 using the charging voltage of the smoothing capacitor C3 as a power supply, and when FET Q3 is turned off. By the current stored in the coil L3, the current flows through the coil L3 → diode D6 → C2 → R1 → HID lamp 5 → T1 → L3, so that the HID lamp is always in the next period T in which the FET Q3 is in a high frequency switching operation. 5, current flows in the direction of R1 → HID lamp 5 → coil L3. Accordingly, a low-frequency lamp current as shown in FIG. 2C flows through the HID lamp 5 while being driven at a high frequency.

  A high-frequency component is superimposed on the low-frequency lamp current shown in FIG. 2 (c) by the high-frequency switching operation of the FETs Q2 and Q3, but this high-frequency component is bypassed by the capacitor C4 as the first capacitor. The lamp current that actually flows through the HID lamp 5 contains almost no high-frequency component, and is lit with, for example, a low-frequency rectangular wave (indicated by a solid line) of 100 Hz (= period 2T).

Next, the operation of the igniter 6 will be described.
When a pulse is generated when the AC power is turned on, a voltage is applied to the timer means (8-1, 8-2) through the FETs Q2, L3 and the diode D14 based on the voltage charged in the smoothing capacitors C2, C3, and the resistor R13. A current flows through the series circuit of the switch element SW11 and charges the capacitor C12 as the second capacitor.

  At the same time, the output voltage of the smoothing capacitor output terminal of the step-up chopper circuit 3 is applied to both ends of a circuit in which a resistor R11 and a parallel circuit of the resistor R12 and the capacitor C11 are connected in series, and the voltage at the connection point (capacitor C11). ) Exceeds the breakover voltage of the diac D11, a voltage is applied to the gate of the thyristor D12 and the thyristor D12 is turned on.

  When the thyristor D12 is turned on by the ON timing control signal of the thyristor D12, the charge of the capacitor C12 is discharged through the primary winding of the transformer T1, and at this time, a pulse is generated based on the resonance of the primary windings of C12 and T1. . This pulse is boosted based on the winding ratio of the transformer T1, and a high voltage pulse is generated in the secondary winding of the transformer T1 connected in series with the discharge lamp 5.

FIG. 3 shows a waveform example of the capacitor C12 at the time of pulse generation, and FIG. 4 shows a waveform example of the resistor R13 at the time of pulse generation. Normally, a reverse voltage is applied to the thyristor D12 by a vibration waveform based on resonance between C12 and the primary winding of T1, so that the thyristor D12 is turned off. (That is, when the thyristor D12 is turned on, the energy of the capacitor C12 substantially becomes a vibration waveform by the resonance frequency of the capacitor capacity of the capacitor C12 and the inductance of the primary winding of the igniter transformer T1, and a reverse voltage is applied to the thyristor D12.)
However, the thyristor D12 has a temperature characteristic. When the temperature becomes high, the off-characteristic of the thyristor D12 deteriorates and it is difficult to turn off, or the primary inductance decreases due to the influence of the lamp current at the start of the lamp, and the thyristor D12 is turned off. There are cases where it is not possible. That is, at the time of starting the lamp, since a current flows to the secondary side of the transformer T1 of the igniter 6, the primary side inductance of the transformer T1 of the igniter 6 extremely decreases. Then, the vibration frequency when the thyristor D12 is turned on becomes higher than that before the start, and the vibration is immediately attenuated, so that the thyristor D12 tends not to be turned off.

  Here, the case where there is no timer means according to the present invention provided with the voltage detection unit 8-1 and the control unit 8-2 will be described. When the thyristor D12 cannot be turned off as described above, the current is passed through the diode D14. It continues to flow through R13 and thyristor D12 (more than the holding current), the pulse generation stops, and a loss at resistor R13 occurs. FIG. 5 shows the voltage waveform of the resistor R13 when there is no timer means and current continues to flow through the thyristor D12.

  Therefore, in the first embodiment of the present invention shown in FIG. 1, the voltage of the resistor R13 is detected, the time during which the voltage is continuously applied is measured by timer means, and the voltage is applied to the resistor R13 for a predetermined time or more. When it is detected that the thyristor D12 cannot be turned off, it is determined that the thyristor D12 cannot be turned off and continues to be turned on. The switch element SW11 is turned off to interrupt the current flowing through the resistor R13. Once interrupted, no current flows through the thyristor D12 (because it is below the holding current), so that the thyristor D12 is reliably turned off.

FIG. 6 is a circuit diagram showing an embodiment of the timer means (8-1, 8-2) shown in FIG.
In FIG. 6, based on the voltage charged to the smoothing capacitors C2 and C3, between the power supply line P to which the voltage is supplied through Q2 and L3 and the diode D14, and the positive voltage output terminal of the charging capacitor C12, A series circuit of a resistor R13 and a blocking switch element SW11 is connected. An N channel transistor is used as the switch element SW11. A voltage detector 8-1 for detecting that a voltage is generated in the resistor R13 is connected in parallel with the series circuit of the resistor R13 and the switch element SW11. Based on the detected voltage, the switch element SW11 is connected. A control unit 8-2 for shutting off (turning off) is connected.

  The voltage detector 8-1 has one end connected in series with a resistor R21 and a parallel circuit of the resistor R22 and the capacitor C21 between the power line P and the source of the switch element SW11 (that is, the + voltage output end of the capacitor C12). And a cathode of a Zener diode ZD1 is connected to a connection point between R21 and C21 (R22).

  The control unit 8-2 has a resistor R23 and a collector / emitter of the bipolar transistor Q4 between one end of the power supply line P and the source of the switch element SW11 (that is, the + voltage output terminal of the capacitor C12). A series circuit connected in series is connected, the collector of the transistor Q4 is connected to the gate of the switch element SW11, and a Zener diode ZD2 is connected between the collector and emitter of the transistor Q4 (that is, between the gate and source of the switch element SW11). Configured.

  Next, the operation of FIG. 6 will be described. Here, it is assumed that the HID lamp 5 is started by the pulse generation of the transformer T1, but the thyristor D12 is not turned off but remains turned on.

  In the timer means (8-1, 8-2) shown in FIG. 6, since the voltage of the power supply line P is applied to the gate of the switch element SW11 via the resistor R23, the switch element SW11 is initially turned on by the resistor R23. ing. While the voltage is applied to the resistor R13, a Zener voltage is generated in the Zener diode ZD2 by the resistor R23, and the gate-source voltage of the switch element SW11 is held at the Zener voltage of ZD2. While the voltage is applied to the resistor R13, in the voltage detector 8-1, the capacitor C21 is charged by the resistor R21. When the charging time exceeds a certain time, the charging voltage of C21 exceeds the Zener level of the Zener diode ZD1, so that ZD1 is turned on, a forward bias is applied to the base of the bipolar transistor Q4, and Q4 is turned on. As a result, the switch element SW11 is cut off (turned off) when the gate and source of the switch element SW11 have the same potential.

  According to the first embodiment of the present invention, when the thyristor D12 cannot be turned off and continues to be turned on, a constant current flowing through the resistor flows. Therefore, the voltage generated in the resistor R13 is detected, and this voltage detection is performed. Based on the above, the current flowing from the resistor R13 to the thyristor D12 is cut off to turn off the thyristor D12, and the high voltage pulse can be generated again.

  7 is a circuit diagram of a discharge lamp lighting device of Example 2 of the present invention. The discharge lamp lighting device 10A of the second embodiment is different from the discharge lamp lighting device 10 of the first embodiment in the configuration of the igniter in the inverter circuit. Other AC power supply 1, rectifier circuit 2, and boost chopper circuit 3 are the same as those in the first embodiment. The configuration of the inverter circuit portion excluding the igniter 6A is the same as that of the first embodiment.

  The igniter 6A includes a transformer T1 having a secondary winding connected in series to the HID lamp 5, boosting and outputting a pulse generated on the primary winding side in the secondary winding, and a primary winding of the transformer T1. A capacitor C12 and a thyristor D12 constituting a line and a closed circuit, a resistor R13 for supplying power to the capacitor C12 for charging the capacitor C12, and a gate voltage applied to the gate of the thyristor D12 to control the on-timing. A control means comprising resistors R11, R12, a capacitor C11 and a diac D11, a temperature detector 9 for detecting the temperature of the resistor R13, and a resistor R13 are connected in series, and the temperature detector 9 has a constant temperature of the resistor R13. The switch element SW12 is provided as a shut-off means for cutting off the charging current from the power source to the capacitor C12 when it is detected.

  FIG. 8 is a block diagram schematically showing an embodiment of a temperature-responsive switch element including the temperature detector 9 and the switch element SW12 shown in FIG.

  The temperature-responsive switch element shown in FIG. 8 is bonded to the body of a resistor R13, which is a subject, on the same base member, and directly detects the temperature of the resistor R13, and the temperature detector 9 The switch is a combination of a bimetallic mechanical switch element SW12 that is provided in the vicinity of the switch and that automatically contacts in response to temperature. Such a thermal switch is one of overheat protection means, and is called a thermal protector that automatically cuts off the contact and cuts off the current when the temperature of the resistor exceeds a certain temperature. is there.

  The temperature detector 9 can also be composed of a temperature detection circuit using a temperature sensor such as a thermistor (an element whose resistance value decreases or increases due to a temperature increase), and a semiconductor switch such as an FET is detected by the detection signal. It is also possible to turn off the switch element SW12 constituted by:

Next, the operation of the igniter 6A in FIG. 7 will be described.
When a pulse is generated when the AC power is turned on, if a voltage is applied through Q2 and L3 and the diode D14 based on the voltage charged in the smoothing capacitors C2 and C3, a current flows through the series circuit of the switch element SW12 and the resistor R13. The capacitor C12 as the second capacitor is charged. A thermal protector composed of a temperature-responsive switch element as shown in FIG. 8 is connected in series with the resistor R13.
When the thyristor D12 is turned on before the HID lamp 5 is started, the energy charged in the capacitor C12 is approximately a vibration waveform due to the resonance frequency of the capacitor capacity of the capacitor C12 and the inductance of the primary winding of the transformer T1 of the igniter 6A. A reverse voltage is applied to the thyristor D12.

  On the other hand, when the HID lamp 5 is started, since a current flows to the secondary side of the transformer T1 of the igniter 6A, the primary side inductance of the transformer T1 of the igniter 6A extremely decreases. Accordingly, the resonance frequency is higher than that before the start and the vibration is immediately attenuated, so that it is not possible to apply a reverse voltage having a sufficient time to turn off the thyristor D12.

  Here, it is assumed that the HID lamp 5 is started by the generation of a pulse in the primary winding of the transformer T1, but the thyristor D12 cannot be turned off and remains on for the reasons described above. If the thyristor D12 continues to be turned on, no current flows through the capacitor C12, and current continues to flow from the resistor R13 to the thyristor D12 via the primary winding of the transformer T1. At this time, the power consumption at the resistor R13 becomes larger than usual and the temperature rises. When this is detected by the thermal protector, the current flowing through the resistor R13 is cut off. Once interrupted, no current flows through the thyristor D12 (because it is below the holding current), and the thyristor D12 is turned off.

  According to the second embodiment of the present invention, when the thyristor D12 cannot be turned off and continues to be turned on, a constant current flowing through the resistor flows. Therefore, the temperature generated in the resistor R13 is detected, and this temperature detection is performed. Based on this, the current flowing from the resistor R13 to the thyristor D12 is cut off, the thyristor D12 is turned off, and a high voltage pulse can be generated again.

FIG. 9 is a cross-sectional view showing an embodiment of the illumination device of the present invention using the discharge lamp lighting device of FIG. 1 or FIG.
In FIG. 9, the code | symbol 11 is a lighting fixture main body, 12 is a reflector. The HID lamp 5 that is a discharge lamp is mounted and held at an appropriate position (for example, the center) of the reflector 12 of the luminaire body 11. In addition, a discharge lamp lighting device 10 or 10A having the configuration described with reference to FIG. 1 or FIG.

  As described above, according to the lighting device using the discharge lamp lighting device 10 or 10A of FIG. 1 or FIG. 7, the thyristor can be reliably turned off after the lamp is started, and the resistance for supplying the power is heated and causes deterioration. In addition, it is possible to prevent wasteful power consumption.

  INDUSTRIAL APPLICABILITY The present invention can be applied to prevent overheating of a resistor for supplying power to a charging capacitor in an igniter of a high pressure discharge lighting device including a HID lamp such as a mercury lamp, a metal halide lamp, a high pressure sodium lamp, and a xenon lamp. Is possible.

The circuit diagram which shows the discharge lamp lighting device of Example 1 of this invention. The timing chart which shows the 1st, 2nd high frequency switching operation | movement in an inverter circuit, and a lamp current waveform. The figure which shows the voltage waveform of the capacitor | condenser C12 at the time of a pulse generation. The figure which shows the voltage waveform of resistance R13 at the time of a pulse generation. The figure which shows the voltage waveform of resistance R13 at the time of a pulse stop. FIG. 2 is a circuit diagram showing a configuration example of timer means in the igniter of FIG. 1. The circuit diagram which shows the discharge lamp lighting device of Example 2 of this invention. The block diagram which shows typically one Example of the temperature response type | mold switch element of FIG. Sectional drawing which shows the Example of the illuminating device of this invention using the said discharge lamp lighting device of FIG. 1 or FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... AC power supply 2 ... Rectifier circuit 3 ... Boost chopper circuit (DC power supply)
4 ... Inverter circuit 5 ... HID lamp (discharge lamp)
10, 10A ... discharge lamp lighting device R1 ~ R3 ... resistance (for power supply when starting to igniter)
C2, C3 ... first and second smoothing capacitors Q2, Q3 ... FET (first and second switching elements)
L3 ... Coil (inductor)
C4 ... Capacitor (first capacitor)
D12 ... Thyristor C12 ... Capacitor (second capacitor)
SW11, SW12 ... switch element (blocking means)
R13 ... resistor (for power supply to capacitor)
8-1 Voltage detection unit 8-2 Control unit 9 Temperature detection unit
Agent Patent Attorney Susumu Ito

Claims (5)

A transformer in which a secondary winding is connected in series to a discharge lamp, and a pulse generated in the primary winding is boosted and output to the secondary winding;
A first capacitor connected in parallel with a series circuit of a discharge lamp and a secondary winding of the transformer;
A second capacitor and a thyristor constituting a closed circuit with the primary winding of the transformer;
A resistor for supplying power to the second capacitor;
Control means for controlling the on-timing of the thyristor;
Timer means for measuring the time during which voltage is applied to the resistor;
A shut-off means connected in series to the resistor, and shuts off a charging current from the power source to the second capacitor when the timer means detects that a voltage is applied to the resistor for a predetermined time or more;
A pulse generation circuit comprising: A transformer in which a secondary winding is connected in series to a discharge lamp, and a pulse generated in the primary winding is boosted and output to the secondary winding;
A first capacitor connected in parallel with a series circuit of a discharge lamp and a secondary winding of the transformer;
A second capacitor and a thyristor constituting a closed circuit with the primary winding of the transformer;
A resistor for supplying power to the second capacitor;
Control means for controlling the on-timing of the thyristor;
A temperature detection unit that detects the temperature of the resistor, and is connected in series to the resistor, and when it is detected that the temperature of the resistor is equal to or higher than a predetermined value, a charging current from the power source to the second capacitor A temperature-responsive switch element that shuts off
A pulse generation circuit comprising:   The pulse generation circuit according to claim 2, wherein the temperature-responsive switch element is a thermal protector. A DC voltage source for generating a DC voltage from the output of the AC power supply;
An inverter circuit connected to the DC voltage source for generating AC power and maintaining the discharge lamp on;
4. The pulse generation circuit according to claim 1, wherein the pulse generation circuit is incorporated in the inverter circuit and starts the discharge lamp with a boost pulse. 5.
A discharge lamp lighting device comprising: A discharge lamp lighting device according to claim 4;
An HID lamp as a discharge lamp;
An instrument body holding the HID lamp;
An illumination device comprising:

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