JP2005190805A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device having high power precision. <P>SOLUTION: In this discharge lamp lighting device, including a power control circuit to control lamp power by detecting a lamp current and a lamp voltage, an ac conversion circuit to convert the output of the power control circuit to ac, and an ignitor circuit 26 for generating a high voltage to start a discharge lamp 13, a rectifying and smoothing circuit 40 is provided at the post-stage of the ac conversion circuit; and the output voltage of the ac conversion circuit is controlled, in terms of power by the output voltage rectified and smoothed by the rectifying and smoothing circuit 40 and the output current of the ac conversion circuit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a discharge lamp lighting device used for a projection display such as a liquid crystal projector, and more particularly to a discharge lamp lighting device with high power accuracy and / or high voltage voltage accuracy.

  As the light source of the projection display, a high-pressure discharge lamp such as a metal halide lamp or a high-pressure mercury lamp is used because it has a high conversion efficiency and is easily obtained as a point light source. For lighting the high-pressure discharge lamp, a dedicated discharge lamp lighting device that supplies a voltage and a current necessary for lighting is used.

  In a conventional discharge lamp lighting device, a power control circuit that detects lamp voltage and lamp current to control lamp power, an AC converter circuit (inverter circuit) that converts the output of the power control circuit into AC, and a discharge lamp Some have an igniter circuit that generates a high voltage to start up (see, for example, Patent Document 1 below).

The igniter circuit adds a voltage obtained by rectifying and smoothing the voltage boosted by the transformer to the series circuit of the primary coil of the second transformer and the spark gap, and a high voltage is applied to the secondary side of the second transformer by the conduction of the spark gap. Some have been generated (for example, see Patent Document 2 below).
JP-A-11-260576 JP-A-8-138874

  In the conventional discharge lamp lighting device, since the lamp voltage is detected before the inverter circuit, the voltage drop of the inverter circuit cannot be corrected, and the power accuracy is insufficient.

  In addition, in the conventional discharge lamp lighting device, the igniter circuit is configured by a two-stage transformer using a spark gap, so that the accuracy of the generated high voltage is insufficient due to variations in the discharge voltage of the spark gap. It has the disadvantage of being.

  A first object of the present invention is to provide a discharge lamp lighting device with high power accuracy that eliminates the drawbacks of the prior art.

  A second object of the present invention is to eliminate such drawbacks of the prior art and to provide a discharge lamp lighting device with high voltage voltage accuracy.

  The present invention generates a power control circuit that detects lamp voltage and lamp current to control lamp power, an AC conversion circuit that converts the output of the power control circuit into AC, and a high voltage for starting a discharge lamp And a discharge lamp lighting device including an igniter circuit.

  According to a first aspect of the present invention, in order to achieve the first object, a rectifying / smoothing circuit is provided at a subsequent stage of the AC converting circuit, and the output voltage of the AC converting circuit is rectified and smoothed by the rectifying / smoothing circuit. The power is controlled by the output voltage and the output current of the AC converter circuit.

  In order to achieve the second object, the second means of the present invention is characterized in that the igniter circuit is configured to boost the output voltage of the boost chopper circuit by a transformer.

  According to a third means of the present invention, in order to achieve the first and second objects, a rectifying / smoothing circuit is provided after the AC converting circuit, and the output voltage of the AC converting circuit is rectified by the rectifying / smoothing circuit. The power control is performed by the smoothed output voltage and the output current of the AC converter circuit, and the igniter circuit is configured to boost the output voltage of the boost chopper circuit by a transformer.

  In the discharge lamp lighting device according to the first aspect of the present invention, since the rectifying / smoothing circuit is provided at the subsequent stage of the inverter circuit and the voltage is detected at the subsequent stage of the inverter circuit, the voltage drop due to the inverter circuit is corrected, and as a result A discharge lamp lighting device with high power accuracy can be provided.

  In the discharge lamp lighting device according to the second aspect of the present invention, the igniter circuit is not provided with a spark gap, and a booster circuit using a single-stage transformer is provided after the boost chopper circuit. Can be provided.

  In the discharge lamp lighting device according to the third aspect of the present invention, since the rectifying / smoothing circuit is provided at the subsequent stage of the inverter circuit and the voltage is detected at the subsequent stage of the inverter circuit, the voltage drop due to the inverter circuit is corrected, Since the igniter circuit has a structure in which a booster circuit using a single-stage transformer is provided after the booster chopper circuit without using a spark gap, a discharge lamp lighting device with high power accuracy and high pressure accuracy can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 5 is a schematic configuration diagram of a projection display using a discharge lamp lighting device.

  As shown in the figure, the reflector 74 and the high-pressure discharge lamp 75 constitute a light source that emits light from the back surface of the image display device 73. The light transmitted through the image display device 73 is projected onto the screen 71 by the optical system 72. The image display device 73 is a liquid crystal display, for example, and is driven by the image display device drive circuit 76 to display an image, so that a large screen image is obtained on the screen 71. The discharge lamp lighting device 77 performs start-up and lighting control of the high-pressure discharge lamp 75.

  FIG. 1 is a block diagram of a discharge lamp lighting device according to an embodiment of the present invention. In the figure, reference numeral 1 is a first power input terminal, 2 is a MOS-FET, 3 is a diode, 4 is a choke coil, 5 is a capacitor, 8, 9, 10, and 11 are MOS-FETs, 12 is a resistor, 13 is a discharge lamp, 18 is a lamp-on signal input terminal, 19 is a second power input terminal, 21 is a drive circuit 1, 22 is a PWM control circuit, 23 is an overvoltage protection circuit (OVP circuit), 24 is a drive circuit 2, 25 Is an inverter oscillation circuit, 26 is an igniter circuit, 31 is a timer circuit, 32 is a switch circuit (SW circuit), 40 is a rectifying and smoothing circuit, 41 is an inverter output terminal 1, 42 is an inverter output terminal 2, and 43 is a voltage detection output terminal. , 52 are igniter circuit input terminals, and 53 is an igniter circuit output terminal.

  The MOS-FET 2, the diode 3, the choke coil 4, the capacitor 5, the resistor 12, the drive circuit 21, the PWM control circuit 22, and the rectifying / smoothing circuit 40 constitute a power control circuit, and PWM according to the voltage and current detection results. The control circuit 22 controls the output voltage and current. The MOS-FETs 8, 9, 10, and 11, the drive circuit 24, and the inverter oscillation circuit 25 constitute an AC conversion circuit. The igniter circuit 26 generates a high voltage pulse to start the high pressure discharge lamp 13.

  The overvoltage protection circuit (OVP circuit) 23 stops the operation of the power control circuit when an overvoltage occurs. The timer circuit 31 outputs a voltage for stopping the operation of the overvoltage protection circuit and stopping the oscillation of the oscillation circuit for DC driving. The switch circuit (SW circuit) 32 controls the power supply to the PWM control circuit 22 and the oscillation circuit 25 by the lamp-on signal input to the terminal 18.

  FIG. 2 is a diagram for explaining the basic operation of the discharge lamp lighting device shown in FIG. The operation of the discharge lamp lighting device will be described with reference to FIG.

  When a lamp-on signal is input at t0, the output voltage of the power control circuit is the maximum voltage V3 because the discharge lamp 13 is not lit. At this time, since the output of the timer circuit 31 is high, the overvoltage protection circuit (OVP circuit) 23 does not operate. A high voltage pulse from the igniter circuit 26 is superimposed on the voltage V3, the voltage V4 is applied to the discharge lamp 13, and the discharge lamp 13 is started. As a result, glow discharge of high voltage and small current starts at t1, and further, arc discharge of low voltage and large current starts at t2.

  The lamp voltage increases as the lamp temperature increases. At t3, the output of the timer circuit 31 falls to low, the AC converter circuit operates, and the high pressure discharge lamp 13 shifts to the AC lighting mode. Thereafter, when the steady voltage V1 is reached at time t4, the power control circuit supplies constant power to the high-pressure discharge lamp 13 by constant power control.

  FIG. 3 is a circuit diagram of the rectifying / smoothing circuit 40 shown in FIG. In the figure, 41 is an inverter output terminal 1, 42 is an inverter output terminal 2, 43 is a voltage detection output terminal, 44 and 45 are diodes, 46 is a capacitor, and 47 and 48 are resistors.

  Next, the operation of the rectifying / smoothing circuit 40 will be described. The voltages from the inverter output terminal 41 and the inverter output terminal 42 are rectified and smoothed by the diodes 44 and 45 and the capacitor 46, and the DC voltage is adjusted to an appropriate value by the resistors 47 and 48. It is output from the detection output terminal 43. As a result, a voltage drop due to the inverter oscillation circuit 25 is corrected, and a discharge lamp lighting device with high power accuracy can be obtained.

  FIG. 4 is a circuit diagram of the igniter circuit 26 shown in FIG. In the figure, 52 is an igniter circuit input terminal, 53 is an igniter circuit output terminal, 54 is a choke coil, 55 is an oscillation circuit, 56 is a MOS-FET, 57 is a diode, 58 and 59 are capacitors, and 60, 61 and 62 are A resistor, 63 is a thyristor, and 64 is a transformer.

  Next, the operation of the igniter circuit 26 will be described. The DC voltage input from the igniter circuit input terminal 52 is boosted to a voltage several times higher by a boost chopper circuit including a choke coil 54, an oscillation circuit 55, a MOS-FET 56, a diode 57, and a capacitor 58.

  The capacitor 59 is gradually charged by the resistor 60, but when the gate voltage of the thyristor 63 divided by the resistor 61 and the resistor 62 reaches a voltage for turning on the thyristor, the thyristor becomes conductive, and the primary side of the transformer 64 is connected. A large current flows and a high voltage is generated on the secondary side. As a result, since no spark gap is used, a discharge lamp lighting device with high pressure accuracy can be obtained.

  In the above embodiment, the case where the discharge lamp lighting device is used for a projection display has been described. However, the discharge lamp lighting device according to the present invention is not limited to this, and is a device for lighting a high-pressure discharge lamp for other uses. Is also applicable.

1 is a block diagram of a discharge lamp lighting device according to an embodiment of the present invention. It is a figure for demonstrating the basic operation | movement of the discharge lamp lighting device. It is a circuit diagram of the rectification smoothing circuit in the discharge lamp lighting device. It is a circuit diagram of the igniter circuit in the discharge lamp lighting device. It is a schematic block diagram of the projection type display which uses the discharge lamp lighting device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1st power input terminal, 2 ... MOS-FET, 3 ... Diode, 4 ... Choke coil, 5 ... Capacitor, 8, 9, 10, 11 ... MOS-FET, 12 ... Resistor, 13 ... Discharge lamp, DESCRIPTION OF SYMBOLS 18 ... Lamp-on signal input terminal, 19 ... 2nd power input terminal, 21 ... Drive circuit 1, 22 ... PWM control circuit, 23 ... Overvoltage protection circuit (OVP circuit), 24 ... Drive circuit 2, 25 ... Inverter oscillation circuit, 26 ... igniter circuit, 31 ... timer circuit, 32 ... SW circuit, 40 ... rectification smoothing circuit, 41 ... inverter output terminal 1, 42 ... inverter output terminal 2, 43 ... voltage detection output terminal, 44, 45 ... diode, 46 ... Capacitors 47, 48... Resistors 52. Igniter circuit input terminals 53. Igniter circuit output terminals 54. Choke coils 55 55 Oscillator circuits 5 ... MOS-FET, 57 ... Diode, 58, 59 ... Capacitor, 60, 61, 62 ... Resistor, 63 ... Thyristor, 64 ... Transformer, 71 ... Screen, 72 ... Optical system, 73 ... Image display device, 74 ... Reflection Mirror, 75 ... high pressure discharge lamp, 76 ... drive circuit, 77 ... lamp lighting device.

Claims (3)

A power control circuit that detects lamp voltage and lamp current and controls lamp power;
An AC conversion circuit that converts the output of the power control circuit into AC, and
In a discharge lamp lighting device including an igniter circuit for generating a high voltage for starting the discharge lamp,
Discharging characterized in that a rectifying / smoothing circuit is provided at a subsequent stage of the AC converting circuit, and the power is controlled by an output voltage obtained by rectifying and smoothing the output voltage of the AC converting circuit by the rectifying / smoothing circuit and an output current of the AC converting circuit. Lamp lighting device. A power control circuit that detects lamp voltage and lamp current and controls lamp power;
An AC conversion circuit that converts the output of the power control circuit into AC, and
In a discharge lamp lighting device including an igniter circuit for generating a high voltage for starting the discharge lamp,
A discharge lamp lighting device characterized in that the igniter circuit is configured to boost an output voltage of a boost chopper circuit by a transformer. A power control circuit that detects lamp voltage and lamp current and controls lamp power;
An AC conversion circuit that converts the output of the power control circuit into AC, and
In a discharge lamp lighting device including an igniter circuit for generating a high voltage for starting the discharge lamp,
A rectifying / smoothing circuit is provided at the subsequent stage of the AC conversion circuit, and the power is controlled by an output voltage obtained by rectifying and smoothing the output voltage of the AC conversion circuit by the rectification / smoothing circuit and an output current of the AC conversion circuit,
A discharge lamp lighting device characterized in that the igniter circuit is configured to boost an output voltage of a boost chopper circuit by a transformer.

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