JP3571126B2 - Discharge lamp lighting device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lighting device for a high-intensity discharge lamp, in particular, a metal halide (hereinafter, referred to as HID) lamp, which improves the input power factor of the device and simplifies the circuit by using a piezoelectric transformer in a high-voltage generating circuit. It is measured.
[0002]
[Prior art]
The HID lamp has a ceramic or glass hollow sphere in which a halogen gas and a special evaporated metal are sealed and electrodes facing each other are mounted. In operation, a high voltage of several KV to several tens of KV is applied at the start of discharge to ionize the gas inside the sphere to facilitate the start of discharge. Next, when the discharge is started, the impedance inside the sphere drops rapidly, the terminal voltage drops to several hundred volts, and the discharge is maintained. The temperature inside the sphere is increased by the continuous discharge, and the evaporation of the metal is started to start emitting light.
[0003]
Therefore, in the lighting device of the HID lamp, a low-voltage power supply (several hundred volts) and a high-voltage power supply (several KV) are provided side by side, and the voltages of both power supplies are applied to the HID lamp during lighting. After lighting, high voltage is no longer needed, so it can be cut off.
[0004]
When used for lighting and projection projectors, the input power supply is a commercial power supply (50 or 60 HZ), and it is not possible to produce a compact, highly efficient high-intensity discharge lamp lighting device at such a low frequency. Therefore, normally, a DC is obtained from a commercial power supply by a converter, the DC is converted into an AC having a desired frequency by an inverter, and the HID lamp is turned on by the converted AC.
[0005]
In the lighting device using this inverter, the input circuit is generally configured as a capacitor input type, and the flow angle of the input current changes depending on the magnitude of the lamp current. However, the current flows over the entire flow angle (180 °). Instead, the current flows only at a narrow flow angle around the vicinity of 90 ° where the voltage is at a maximum, and the power supply voltage at that flow angle is distorted, generating harmonics and causing adverse effects on other devices. For this reason, it is usually necessary to provide a device for preventing unnecessary radiation of an input power source, that is, a device for suppressing noise interference of high-frequency switching.
[0006]
According to U.S. Pat. No. 4,424,0009, a method of obtaining an AC output through a transformer by a constant voltage output converter, obtaining a DC voltage of 3 to 4 times by using a rectifier, and adding these to a HID lamp. And has a complicated circuit configuration. In addition, the high voltage generating circuit is exemplified by an electronic circuit including a transformer, and it is described that the high voltage can be replaced by a high voltage generated by a piezoelectric element due to mechanical shock, but this is not a simple method.
[0007]
In general, HID lamps are generally placed farther than an object to be illuminated and used for illumination, and it is not always appropriate to add mechanical operation to remote control and generate an impact sound. As shown in FIG. 5, nine parts are used to generate a high voltage pulse between the terminals 16 and 18 and apply the pulse to the HID lamp.
[0008]
[Problems to be solved by the invention]
When a discharge lamp lighting device for lighting an HID lamp is used with an AC input, a large-capacity capacitor is placed in a rectifier circuit to store DC energy. Therefore, when supplying energy to the load, the input AC current becomes a pulse-shaped current having a narrow flow angle and charges the capacitor. Therefore, waveform distortion is given to the power supply.
[0009]
When starting the HID lamp, it was necessary to apply a high voltage of several tens of kilovolts to the HID lamp, and required a complicated circuit and many electronic components using a high-voltage generating converter, a spark gap or a semiconductor switch, and a high-voltage transformer. . There is also a method of obtaining a high voltage by applying a mechanical shock using a piezoelectric element.
In the method of supplying the energy for maintaining the lighting of the HID lamp by superimposing a high DC voltage and an AC voltage, the complexity of the circuit and the number of components pose problems.
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an HID lamp lighting device that easily lights an HID lamp by an electronic ballast and introduces a simple circuit configuration to achieve a stable brightness. Is to keep
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present invention provides a rectifier circuit for a commercial AC power supply, a converter circuit for boosting the output of the rectifier circuit, and chopping the output of the converter circuit. In a discharge lamp lighting device including an inverter circuit and a metal halide lamp driven by an output of the inverter circuit,
And has a high voltage generating circuit comprising a lighting starting at high-voltage pulse of the metal halide lamp from the piezoelectric transformer is supplied to the metal halide lamp, the high voltage generating circuit applies a pulse output of the converter circuit to the piezoelectric transformer the high pressure Has means to generate pulses,
It said converter circuit, there is the work in the piezoelectric transformer-specific unloaded resonant frequency and to improve the input power factor of the rectified pulsating AC input directly switching to,
The converter circuit and the high voltage generation circuit operate at the same frequency, the inverter circuit has means for changing a smoothed output of the converter circuit to low frequency AC, and means for supplying a discharge sustaining voltage to the metal halide lamp, A metal halide lamp lighting device characterized in that after the metal halide lamp is started to be turned on, it is turned on at the discharge maintaining voltage of the inverter circuit .
[0011]
The invention according to claim 2 of the present application, in addition to the invention of claim 1, a metal halide lamp which is characterized in that a high frequency noise removing means between the input end and the commercial AC power supply of said converter circuit A lighting device is provided.
[0012]
According to a third aspect of the present invention, in addition to the first aspect, the converter circuit has switch means for directly turning on and off a non-smoothed pulsating voltage at a high frequency, and an input power factor of the metal halide lamp lighting device. In addition, the output turned on and off at a high frequency has a means for supplying a pulse output to a high voltage generating circuit, and has a means for supplying a rectified and smoothed DC output to an inverter circuit. Provide equipment.
[0013]
According to a fourth aspect of the present invention, in addition to the first aspect, the circuit for driving the inverter has means for generating a low-frequency alternating current and supplying the low-frequency alternating current to the inverter circuit. Provided is a lamp lighting device .
[0014]
The invention described in claim 5 of the present application, in addition to the invention of claim 1, having means for generating said piezoelectric transformer no-load resonance frequency and the same frequency, the converter circuit as a pulse width control signal Provided is a metal halide lamp lighting device having a control circuit for outputting .
[0015]
The invention described in claim 6 of the present application, in addition to the invention of claim 1, wherein the detecting the current flowing to the inverter circuit, means for maintaining a constant current of the inverter circuit by controlling the on-off time of the pulse A metal halide lamp lighting device characterized by having:
According to a seventh aspect of the present invention, in addition to the third aspect, the converter circuit has means for boosting an input voltage to a sustaining voltage, and the converter circuit extends over the entire phase of the pulsating voltage of the AC circuit output. And a switch means for uniformly pulsing the input voltage so that the input current has the same phase as the input voltage.
According to an eighth aspect of the present invention, in addition to the first aspect, the high voltage generating circuit has means for applying a high voltage pulse generated by a piezoelectric transformer to a metal halide lamp via the transformer. A metal halide lamp lighting device is provided.
According to a ninth aspect of the present invention, in addition to the fifth aspect, the control circuit detects a current flowing in the inverter circuit, compares the detected current with a reference voltage in the control circuit, and turns on / off the converter circuit. A metal halide lamp lighting device having means for controlling time is provided.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 1 denotes an AC input circuit. The AC input to the AC input circuit 1 is rectified to DC, and the rectified DC is input to a converter circuit 2 having a power factor correction circuit. The converter circuit 2 is a boost chopper type sine wave converter circuit. The sine wave converter circuit 2 is connected to a full bridge type inverter circuit 3 as a load. Further, an HID lamp LI is connected as a load of the inverter circuit 3. 4 is a high-voltage generating circuit, a high voltage generated in the initialization of the HID lamp L I turned on to apply to the HID lamp LI. In the present invention, a main circuit is composed of the power factor improving converter circuit 2, the inverter circuit 3, the high voltage generating circuit 4, and the control circuit 5 described later, and in particular, the AC input power factor is improved to almost 100%. Further, the converter circuit 2 and the high voltage generation circuit 4 are characterized in that they operate at the same frequency. Next, the contents of the embodiment will be sequentially described.
[0017]
The boost chopper sine wave converter circuit will be briefly described. In order to make the input current the same as the waveform of the commercial AC power supply voltage, first, the waveform of the input voltage is detected. On the other hand, the current detecting means detects the current waveform flowing through the converter circuit 2, and the comparator compares the input voltage waveform with the current waveform to generate a PWM signal proportional to the difference, thereby enabling the switching element of the sine wave converter. Drive. As a result, the same current waveform as the waveform of the commercial AC power supply voltage is obtained, and the input power factor becomes substantially 1.
[0018]
Next, details of each circuit will be described. The AC input circuit 1 forms a high frequency noise filter including an inductor L and a capacitor C as shown in FIG. 2, and removes high frequency noise generated in the converter circuit 2 and the like. The inductor L is configured around a common mode coil, but a normal mode coil can be added if necessary. The rectification method uses a bridge rectifier RC01 to rectify an alternating current and output an unsmoothed pulsating flow.
[0019]
The converter circuit 2 constitutes a boost type chopper circuit known as a power factor correction circuit as shown in FIG. 3, and operates so as to obtain a switched current waveform having an envelope similar to the rectified voltage waveform as shown in FIG. Yes, the power factor approaches 100% without limit. Improve the input power factor of the conventional capacitor input type rectifier circuit. When the input voltage is high (280V system, 380V system), it can be easily replaced by a back type chopper circuit.
[0020]
The control circuit 5 includes a circuit using an operational amplifier and an integrated circuit IC01 typified by TL494 of TI, which is a switching power supply IC used for pulse width control in FIG. The operating frequency of the control circuit 5 is 69 to 71 KHZ, which is a no-load resonance frequency of the piezoelectric transformer described later.
[0021]
Op amp IC01 from the terminal 6 to the output voltage of the converter circuit 2, input via the error amplifier circuit 5B made of IC02 (see FIG. 1), the reference voltage generated inside the IC01 (the output of the reference voltage generating circuit 5A in FIG. 1 ), The difference voltage is increased by the converter drive pulse width control circuit 5C shown in FIG.
[0022]
The current flowing through the load of the HID lamp LI is detected by the voltage across the resistor RM. This voltage is detected by the load current detection circuit 5D of the control circuit 5, and this signal is input to the converter drive pulse width control circuit 5C as a negative feedback signal to control the load current of the HID lamp LI to be constant. The setting of the luminance of the HID lamp LI can be performed by the variable resistor VR on the IC02 output side shown in FIG. Usually fixed in illumination.
[0023]
The inverter circuit 3 has a full bridge configuration including four transistors Q02 to Q05 as shown in FIG. These transistors are MOSFETs, which are operated by an inverter driving circuit 6 shown in detail in FIG. 8. In FIG. 4, a line filter coil LL and a capacitor CL are connected to terminals 16 and 17 for supplying power to the HID lamp LI. The noise current generated from the LI is removed.
[0024]
As shown in FIG. 8, the inverter drive circuit 6 generates a low frequency (about 300 HZ) using the IC 04 as a self-excited oscillator and adjusts the waveform by the IC 05. The full-bridge high-side switch transistors Q02 and Q03 of the inverter circuit 3 are driven by the photocouplers IC06 and IC07 while maintaining insulation between the inverter drive circuit 6 and the high-side switch. The transistor for the low-voltage switch is directly driven by the terminals 13 and 14 without passing through the photocoupler because the source side is at the GND potential.
[0025]
The high-voltage generating circuit 4 has conventionally constituted a circuit using a transformer as shown in FIG. 5, but as shown in FIG. 6, the present invention has sufficient characteristics with two electronic components including a piezoelectric transformer T1 as shown in FIG. When the piezoelectric transformer T1 is driven at the no-load resonance frequency shown in FIG. 10, the step-up ratio becomes about 40 times when the lamp impedance before the HID lamp LI is turned on is extremely large, and if a 300 VDC input generates 6 KV to 12 KV, the HID lamp If added to the LI, it can be used for gas ionization inside the lamp and facilitates lighting.
After the HID lamp LI is turned on, no high voltage is required, but since the operating frequency is fixed, the impedance of the lamp is lowered and the resonance characteristic of FIG. descend. In this way, during lighting, the state in which the supplied energy is extremely small is maintained.
FIG. 10 is an example of resonance characteristics of a piezoelectric transformer having a shape of 47 × 7.6 × 2.0.
[0026]
The auxiliary power supply circuit 7 is a stabilized power supply for operating the control circuit 5 for controlling the converter circuit 2 and the inverter drive circuit 6, and has a circuit configuration as shown in FIG. I have.
The power for driving the HID lamp LI enters the high voltage generation circuit shown in FIG. 6 from the inverter output terminals 16 and 17 shown in FIG. 4 and is applied to the HID lamp LI connected between the terminals 17 and 18. This power is obtained by superimposing a high voltage pulse on a discharge sustaining voltage which is an inverter output.
[0027]
【The invention's effect】
The present invention has a high-voltage generating circuit composed of a piezoelectric transformer that supplies a high-voltage pulse to the metal halide lamp when the metal halide lamp is turned on, operates at a no-load resonance frequency unique to the piezoelectric transformer, and rectifies an AC input. Since the present invention has a converter circuit for directly switching the pulsating flow to improve the input power factor, according to the present invention, the input power factor is improved, and the power supply waveform distortion is reduced. Since the high-voltage generating circuit is simplified, expensive components used in the high-voltage circuit can be reduced, and the effect of cost reduction is great.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram showing one embodiment of a discharge lamp lighting device according to the present invention.
FIG. 2 is a circuit diagram of an AC input circuit.
FIG. 3 is a circuit diagram of a converter circuit.
FIG. 4 is a circuit diagram of an inverter circuit.
FIG. 5 is a circuit diagram of a conventional high voltage generation circuit.
FIG. 6 is a high voltage generation circuit diagram of the present invention.
FIG. 7 is a circuit diagram of a control circuit.
FIG. 8 is a circuit diagram of an inverter drive circuit.
FIG. 9 is a circuit diagram of an auxiliary power supply circuit.
FIG. 10 is a characteristic curve diagram of the piezoelectric transformer.
FIG. 11 is a characteristic curve diagram of an input voltage and an input current of the converter circuit.
[Explanation of symbols]
1 AC input circuit 2 Converter circuit 3 Inverter circuit 4 High voltage generation circuit 5 Control circuit 5A Reference voltage Generation circuit 5B Error amplification circuit 5C Converter drive pulse width control circuit 5D Load current detection circuit 6 Inverter drive circuit C Capacitor IC01 ... Integrated circuit IC02 ... Op amp IC03 ... Op amp IC04 ... Timer IC05 ... Buffer IC06 ... Photocoupler IC07 ... Photocoupler L ... ··· Inductor LI ······· HID lamp Q01 ·············································· Register RC01 · · · · bridge rectifier T1 · · · · · · piezoelectric transformer

Claims (9)

Discharge lamp lighting comprising a rectifier circuit of a commercial AC power supply, a converter circuit for boosting the output of the rectifier circuit, an inverter circuit for chopping the output of the converter circuit, and a metal halide lamp driven by the output of the inverter circuit. In the device,
And has a high voltage generating circuit comprising a lighting starting at high-voltage pulse of the metal halide lamp from the piezoelectric transformer is supplied to the metal halide lamp, the high voltage generating circuit applies a pulse output of the converter circuit to the piezoelectric transformer the high pressure Has means to generate pulses,
It said converter circuit, there is the work in the piezoelectric transformer-specific unloaded resonant frequency and to improve the input power factor of the rectified pulsating AC input directly switching to,
The converter circuit and the high voltage generation circuit operate at the same frequency, the inverter circuit has means for changing a smoothed output of the converter circuit to low frequency AC, and means for supplying a discharge sustaining voltage to the metal halide lamp, A lighting device for a metal halide lamp, wherein the lighting is performed at a discharge maintaining voltage of the inverter circuit after the lighting of the metal halide lamp is started . 2. The metal halide lamp lighting device according to claim 1, wherein a high frequency noise removing unit is provided between an input terminal of the converter circuit and a commercial AC power supply. The converter circuit has a switch means for directly turning on and off the unsmoothed pulsating voltage at a high frequency, improves the input power factor of the metal halide lamp lighting device, and outputs a pulse output to a high voltage generating circuit while the output turned on and off at a high frequency. 2. The metal halide lamp lighting device according to claim 1, further comprising means for supplying a rectified and smoothed DC output to an inverter circuit. 2. The metal halide lamp lighting device according to claim 1, wherein the circuit for driving the inverter has means for generating a low-frequency alternating current and supplying the low-frequency alternating current to the inverter circuit. 2. The metal halide lamp lighting device according to claim 1, further comprising a control circuit having means for generating the same frequency as the no-load resonance frequency of the piezoelectric transformer, and outputting the pulse width control signal to a converter circuit. Wherein detecting a current flowing through the inverter circuit, a metal halide lamp lighting device according to claim 1 which controls the on-off time of the pulse is characterized by having a means for a constant current of the inverter circuit. The converter circuit has a means for boosting an input voltage to a discharge sustaining voltage, and has a switch means for uniformly pulsing over the entire phase of the pulsating voltage of the output of the AC circuit to make an input current in phase with the input voltage. The metal halide lamp lighting device according to claim 3, wherein 2. The metal halide lamp lighting device according to claim 1, wherein the high voltage generating circuit has a unit for applying a high voltage pulse generated by a piezoelectric transformer to the metal halide lamp via the transformer. 6. The metal halide lamp lighting device according to claim 5 , wherein the control circuit has means for detecting a current flowing in the inverter circuit and comparing the reference voltage in the control circuit to control the on / off time of the converter circuit. .

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