JP2002367791A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device realizing both instantaneous breaking measures and size and weight saving of a device. SOLUTION: The discharge lamp lighting device for lighting a discharge lamp is equipped with a capacitor storing output from a power source, an instantaneous breaking detecting means detecting instantaneous breaking by a wave form of an output voltage of the power source, and a power control means controlling power to supply with the discharge lamp from the capacitor. The power control circuit controls supplying power to the discharge lamp from the capacitor within a given power less than the steady supplying power to the discharge lamp based on the instantaneous breaking detecting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device provided with an instantaneous interruption countermeasure.

[0002]

2. Description of the Related Art At present, discharge lamps are widely used in various fields, for example, as light sources for LCD projectors. As a power source for such an LCD projector, a commercial power source, that is, an AC power source is widely used.

By the way, when an AC power supply is used in an LCD projector and the power supply is cut off for some reason, that is, when an instantaneous interruption occurs, the discharge lamp goes out. In such a case, if the illumination flickers or the time of the instantaneous interruption is long, the discharge lamp is turned off, which greatly affects, for example, a presentation.

In order to deal with such a problem, the discharge lamp lighting device includes a capacitor having a predetermined capacity.
That is, when a momentary interruption occurs, power is supplied to the discharge lamp by the electric energy stored in this capacitor,
The lighting can be maintained without turning off the discharge lamp.

[0005]

However, in order to cope with a long interruption, a large amount of power is required to keep the discharge lamp from being turned off, and a large-capacity capacitor is required. In other words, a capacitor having a relatively large capacity is required in order to take a reliable instantaneous interruption countermeasure capable of coping with a long instantaneous interruption.

However, this leads to an increase in the size, weight, and cost of the capacitor, that is, an increase in the size, weight, and price of the LCD projector itself. This is contrary to the recent trend of reducing the size and weight of electronic devices and the like and reducing the price. In order to reduce the size and weight of the LCD projector and reduce the price, the capacitors must be as small and lightweight as possible. It is necessary to make it.

Accordingly, a discharge lamp lighting device which is capable of coping with a long-time interruption and has a reliable countermeasure against an interruption, and which has a reduced size and weight of the capacitor, that is, a reduced size and weight of the device, is still realized. It is not the fact.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and provides an inexpensive discharge lamp lighting device which achieves both a highly reliable instantaneous interruption countermeasure and a reduction in size and weight of the device. The purpose is to do.

[0009]

A discharge lamp lighting device according to the present invention for achieving the above object is a discharge lamp lighting device for lighting a discharge lamp, comprising: a capacitor for storing an output from a power supply; Instantaneous interruption detecting means for detecting an instantaneous interruption based on the waveform of the output voltage, and electric power control means for controlling electric power supplied from the capacitor to the discharge lamp. The power supplied from the capacitor to the discharge lamp is controlled to a predetermined power smaller than the steady supply power to the discharge lamp.

[0010] The discharge lamp lighting device configured as described above includes an instantaneous interruption detection means and a power control means.
By using these, power reduced to a predetermined level smaller than the steady supply power is supplied to the discharge lamp.

As a result, the power supplied to the discharge lamp at the momentary interruption is significantly reduced as compared with the case where the steady supply power is supplied. Then, from the moment when the instantaneous interruption occurs to the end of the instantaneous interruption, the power supply to the discharge lamp is performed by the capacitor, so that the used capacity of the capacitor during the instantaneous interruption is greatly reduced. As a result, the capacitor in the discharge lamp lighting device does not need to have a large capacity as in the related art.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of an example of a discharge lamp lighting device to which the present invention is applied.

In FIG. 1, 1 is an AC power supply, 2 is a power switch, 3 is a rectifying and smoothing circuit, 4 is a DC power supply, 5 is a capacitor, 6 is a power control circuit section, 7 is a down converter, 8
Is a PWM controller, 9 is a current detection circuit unit, 10 is a voltage detection circuit unit, 11 is an igniter, 12 is an instantaneous interruption detection unit,
13 is a one-shot multivibrator, and 14 is a discharge lamp.

Here, the AC power supply 1 is a power supply for the discharge lamp, and for example, an AC power supply of 100 V and 50 Hz can be used.

The power switch 2 is a start switch of the discharge lamp lighting device.

The rectifying and smoothing circuit 3 performs full-wave rectification on the output from the AC power supply and outputs the result. DC power supply 4
The output subjected to full-wave rectification by the rectifying / smoothing circuit 3 is input, and for example, 300 V to 40
It is configured to obtain a voltage of about 0V. Further, a capacitor 5 having a predetermined capacity is provided in the DC power supply 4, and is charged by an output from the rectifying / smoothing circuit 3.

The power control circuit 6 includes a voltage detection circuit 10
Is a power control means for controlling the power supplied to the discharge lamp 14 based on the detection result of the down converter 7 and the PWM.
A controller 8 is provided.

The current detecting circuit section 9 is a current detecting means for detecting a current flowing through the discharge lamp 14, and is branched from an output terminal of the down converter 7 and an input terminal of the igniter 11. The output terminal of the current detection circuit unit 9 is connected to the PWM controller 8 in the power control circuit unit 6.
Is connected to the input terminal of

The voltage detection circuit section 10 is voltage detection means for detecting a voltage applied to the discharge lamp 14, and is branched from an output terminal of the down converter 7 and an input terminal of the igniter 11. An output terminal of the voltage detection circuit unit 10 is connected to an input terminal of the PWM controller 8 in the power control circuit unit 6.

The igniter 11 serves as a start switch of the discharge lamp lighting device, generates a pulse of, for example, about 5 kV to 20 kV, and stops after the discharge lamp is turned on.

The instantaneous interruption detecting unit 12 detects the occurrence of an instantaneous interruption based on a change in the voltage waveform of the power supply, and includes a differentiating circuit.

The one-shot multivibrator 13
This is a means for controlling the execution time of the predetermined control in the power control circuit section 6, and outputs an output signal for a predetermined time based on the detection result of the instantaneous interruption detection section 12.

As shown in FIG. 2, the discharge lamp 14 includes a connector 21, a reflector 22, an electrode 23, and a heat-resistant glass 24 covering the electrode 23.
, An ignition voltage, a lamp current, and the like are supplied. Various gases are sealed in the heat-resistant glass 24, and the electrodes 23 are configured to discharge within the heat-resistant glass 24.

The discharge lamp to which the discharge lamp lighting device according to the present invention can be applied is not particularly limited, and the discharge lamp power can be changed, for example, a metal halide lamp, a high pressure mercury lamp, a xenon lamp, etc. Any discharge lamp can be used.

In this discharge lamp lighting device, the voltage supplied to the discharge lamp 14 is controlled by controlling the current flowing through the discharge lamp 14. The control of the current flowing through the discharge lamp 14 is performed by controlling the voltage applied to the discharge lamp 14. That is, in this discharge lamp lighting device, the power supplied to the discharge lamp 14 is controlled by changing and controlling the voltage applied to the discharge lamp 14.

In the discharge lighting device thus configured, the lighting operation is performed as follows. First, when the power switch 2 is turned on, the AC power is applied to the rectifying / smoothing circuit 3, converted into DC, and supplied to the DC power 4.
In the DC power supply 4, a DC voltage of, for example, about 300 V to 400 V is obtained from an output of an active filter or the like. Also,
The capacitor 5 provided in the DC power supply 4 is charged by the current supplied to the DC power supply 4. Then, DC power supply 4
Is supplied to the igniter 11 under the control of the power control circuit 6 so as to have an appropriate power, and the discharge lamp 14 is turned on by starting the igniter 11.

After the discharge lamp 14 is turned on, the current flowing through the discharge lamp 14 is detected by the current detection circuit 9. The detection result of the current detection circuit unit 9 is as follows:
The power is input to the PWM controller 8 of the power control circuit unit 6.

After the discharge lamp 14 is turned on, the voltage applied to the discharge lamp 14 is detected by the voltage detection circuit unit 10. The detection result of the voltage detection circuit unit 10 is input to the PWM controller 8 of the power control circuit unit 6.

The PWM controller 8 of the power control circuit 6 controls the voltage supplied to the discharge lamp 14 to a predetermined appropriate value.
Down converter 7 based on the detection result input from
Output a control signal to the Specifically, the ON / OFF duty ratio of a semiconductor switch provided in the PWM controller 8 is controlled in accordance with the detection result of the voltage detection circuit unit 10, and the controlled signal is input to the down converter 7. .

Then, the down converter 7 performs DC based on a control signal input from the PWM controller 8.
The DC current supplied from the power supply 4 is controlled to a predetermined power, and is output to the discharge lamp 14 via the igniter 11. Thereby, the lighting of the discharge lamp 14 is maintained.

In this discharge lamp lighting device, when an instantaneous interruption occurs in the AC power supply 1, electric power is supplied to the discharge lamp 14 by the electric energy stored in the capacitor 5, and the discharge lamp 14 is turned off. Lighting can be maintained without any change.

Here, in order to cope with a long momentary interruption, a large amount of power is required in order not to extinguish the discharge lamp 14, so that the capacitor 5 is required to have a large capacity. You. That is, in order to take a highly reliable instantaneous interruption countermeasure capable of coping with a long instantaneous interruption, the capacitor 5 needs to have a certain large capacity.

However, this leads to an increase in the size, weight and cost of the capacitor, that is, an increase in the size, weight and cost of the LCD projector itself. This is contrary to the recent trend of reducing the size and weight of electronic devices and the like and reducing the price. In order to reduce the size and weight and reduce the cost of LCD projectors, capacitors must be as small and lightweight as possible. It needs to be priced.

Therefore, in this discharge lamp lighting device, the provision of the instantaneous interruption detecting means and the power control means makes it possible to reduce the size and weight of the capacitor, thereby realizing a low cost. Hereinafter, the operation including the operation of the discharge lamp lighting device will be specifically described.

In this discharge lamp lighting device, in order to provide a highly reliable countermeasure against instantaneous interruption, and to reduce the size and weight of the capacitor and the discharge lamp lighting device itself and reduce the cost, the instantaneous interruption detection means and the power control means are used. In the event of an instantaneous interruption, the power supplied to the discharge lamp 14 is reduced to a predetermined level that is smaller than the power supplied to the discharge lamp 14 in a steady state (hereinafter, referred to as a steady supply power). Is what you do. In this discharge lamp lighting device, the occurrence of an instantaneous interruption is detected by a change in the voltage waveform of the power supply output, and the power supplied to the discharge lamp 14 is controlled based on the detection result.

FIG. 3 shows the waveform of the AC power supply in the normal state.
Shows a voltage waveform of the AC power supply when an instantaneous interruption occurs.
By comparing FIG. 3 with FIG. 4, it can be seen that the voltage waveform of the AC power supply changes when an instantaneous interruption occurs. Specifically, when an instantaneous interruption occurs, it is understood that the voltage waveform disappears while the instantaneous interruption continues.

Therefore, in this discharge lamp lighting device, such a change in the voltage waveform, specifically,
The instantaneous interruption is detected by detecting the “falling waveform”. The instantaneous interruption detecting unit 12 corresponds to the instantaneous interruption detecting means, and specifically, a differentiating circuit can be suitably used. The differentiating circuit has a very high response speed at the time of detection and is excellent in detecting the change in the voltage waveform, so that the occurrence of an instantaneous interruption can be detected very quickly. Therefore, by using a differentiating circuit for the instantaneous interruption detecting unit 12 as instantaneous interruption detecting means, it is possible to accurately and quickly detect instantaneous interruption. As a result, this discharge lamp lighting device
Since the instantaneous interruption countermeasure can be started upon occurrence of the instantaneous interruption, it is possible to reliably prevent the discharge lamp 14 from turning off, flickering, and extinguishing, and to implement a highly reliable instantaneous interruption countermeasure.

Here, the differentiating circuit of the instantaneous interruption detecting unit 12 may be configured as a simple circuit including resistors R ₁ and R ₂ , a capacitor C ₁ , and a diode D ₁ as shown in FIG. For example, when a voltage waveform as shown in FIG. 6 is input, a waveform as shown in FIG. 7 is output.
That is, in this discharge lamp lighting device, the differentiating circuit of the instantaneous interruption detecting unit 12 can be constituted by a simple circuit as shown in FIG. 5, so that it is excellent in reliability and can be manufactured at low cost. is there.

The object of detecting a change in the voltage waveform by the differentiating circuit of the instantaneous interruption detecting unit 12 is not limited to the output of the AC power supply. Or an output of a normal DC power supply. As an example, FIG. 8 shows the voltage waveform of the AC power supply output in FIG.
The voltage waveform of the output V ₀ which is full-wave rectified by the rectification smoothing circuit 3 shown in FIG. 8 and 9 that when an instantaneous interruption occurs, both the voltage waveform of the AC power supply output and the voltage waveform of the output obtained by full-wave rectification of the AC power supply by the rectifying and smoothing circuit 3 change. I understand. Specifically, when an instantaneous interruption occurs, it can be seen that the voltage waveform disappears while the instantaneous interruption continues.

When detecting the occurrence of an instantaneous interruption,
The output that is full-wave rectified by the rectifying and smoothing circuit 3 is more preferable than the AC power supply output because the waveform is simpler and the change in the voltage waveform, that is, the “falling waveform” is easier to detect.

The instantaneous interruption detecting section 12 outputs the detection of occurrence of an instantaneous interruption and inputs the detection to the one-shot multivibrator 13. The one-shot multivibrator 13 outputs a signal for a predetermined time using an input signal from the instantaneous interruption detecting unit 12 as a control signal. Then, the output from the one-shot multivibrator 13 is input to the PWM controller 8. The PWM controller 8 lowers the output from the down converter 7 to a predetermined level for a certain period of time from the one-shot multivibrator 13 in order to supply the discharge lamp 14 with a predetermined power lower than the steady supply power. Outputs control signal. Specifically, the PWM controller 8 controls an ON / OFF duty ratio of a semiconductor switch provided in the PWM controller 8 in accordance with an input from the one-shot multivibrator 13, and reduces the controlled signal. Input to converter 7.

Then, the down-converter 7 performs DC based on the control signal input from the PWM controller 8.
The output from the power supply 4 is controlled to a predetermined power lower than the steady supply power and output.

Then, the lighting of the discharge lamp 14 is maintained by the predetermined power output from the down converter 7.

Therefore, when a momentary interruption occurs, the supplied power is controlled to be less than the steady supply power, so that the illuminance of the discharge lamp 14 is lower than in the steady state, but the discharge lamp 14 goes out, flickers, and turns off. Lighting can be maintained without any need.

When a predetermined time has elapsed and the signal is no longer output from the one-shot multivibrator 13, that is, when the instantaneous interruption is completed, the output control in the power control circuit unit 6 is in a steady state. Return to As a result, the steady supply power is supplied to the discharge lamp 14, and the discharge lamp 14 is turned on with the same normal illuminance as before the momentary interruption occurs.

Therefore, by using the one-shot multivibrator 13, the time for controlling the output in the power control circuit section 6 can be controlled, and the output can be controlled for a desired time.

Here, it is preferable that the signal output time of the one-shot multivibrator 13 is usually set to a time of an instantaneous interruption that can occur in the AC power supply, for example, about 30 msec to 200 msec. Further, at this time, the reduced supply power output from the PWM controller 8 to the discharge lamp 14 can maintain the lighting of the discharge lamp 14 and return to the normal lighting state after the end of the momentary interruption. Set to the highest level of power possible. By setting the power supplied to the discharge lamp 14 at the momentary interruption to such a predetermined level,
The power supplied to the discharge lamp 14 can be greatly reduced as compared with the case where the steady power is supplied.

Here, from the moment when the instantaneous interruption occurs to the end of the instantaneous interruption, power is supplied to the discharge lamp 14 by the capacitor 5. For this reason, by setting the power supply to the discharge lamp 14 at the momentary interruption as described above, the capacity of the capacitor 5 at the momentary interruption can be significantly reduced. As a result, since the capacitor does not need to have a large capacity as in the related art, the capacitor and the discharge lamp lighting device itself can be reduced in size and weight, and the cost can be reduced.

Therefore, by providing the above-described configuration, this discharge lamp lighting device can implement a highly reliable countermeasure against instantaneous interruption, and can realize a reduction in size, weight, and cost of the discharge lamp lighting device.

Further, in the above, the execution time of the control for reducing the power supplied to the discharge lamp 14 from the steady supply power is set and controlled by the one-shot multivibrator 13, but it is not limited to this. In addition, various devices such as a general-purpose timer IC that can set and control a predetermined time can be used.

The present invention is not limited to the above description, and can be appropriately changed without departing from the gist of the present invention.

[0053]

The discharge lamp lighting device according to the present invention is a discharge lamp lighting device for lighting a discharge lamp, comprising: a capacitor for storing an output from a power supply; A power control circuit for controlling the power supplied from the capacitor to the discharge lamp, wherein the power control circuit discharges the power supplied from the capacitor to the discharge lamp based on the detection result of the instantaneous interruption detection means. The power is controlled to a predetermined power smaller than the steady power supplied to the electric lamp.

The discharge lamp lighting device configured as described above includes an instantaneous interruption detecting means and a power control means.
By using these, power reduced to a predetermined level smaller than the steady supply power is supplied from the capacitor to the discharge lamp.

As a result, since the capacitor does not need to have a large capacity as in the prior art, it is possible to reduce the size and weight of the capacitor and the discharge lamp lighting device itself, and to reduce the cost.

Therefore, according to the present invention, it is possible to provide a discharge lamp lighting device that is compatible with both measures against instantaneous interruption and reduction in size and weight of the device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an example of a discharge lamp lighting device to which the present invention is applied.

FIG. 2 is a schematic sectional view showing one configuration example of a discharge lamp.

FIG. 3 is a diagram showing a voltage waveform of an AC power supply in a normal state.

FIG. 4 is a diagram showing a voltage waveform of an AC power supply when an instantaneous interruption occurs.

FIG. 5 is a configuration diagram illustrating a configuration example of a differentiating circuit;

FIG. 6 is a diagram illustrating an example of a voltage waveform input to a differentiating circuit;

FIG. 7 is a diagram illustrating an example of a waveform output from a differentiating circuit.

FIG. 8 is a diagram showing a voltage waveform of an AC power supply output when an instantaneous interruption occurs.

FIG. 9 is a diagram illustrating a voltage waveform of an output that is full-wave rectified by a rectifying / smoothing circuit when an instantaneous interruption occurs.

[Explanation of symbols]

1 AC power supply, 2 power switch, 3 rectification smoothing circuit,
4 DC power supply, 5 capacitor, 6 current control circuit section,
7 Down converter, 8 PWM controller, 9
Current detection circuit section, 11 igniter, 12 instantaneous interruption detection section, 13 one-shot multivibrator, 14 discharge lamp, 21 connector, 22 reflector, 23 electrodes, 24 heat-resistant glass

Claims (3)

[Claims] 1. A discharge lamp lighting device for lighting a discharge lamp, comprising: a capacitor for storing an output from a power supply; an instantaneous interruption detection means for detecting an instantaneous interruption based on a waveform of an output voltage of the power supply; Power control means for controlling power supplied to the discharge lamp, wherein the power control circuit supplies power supplied from the capacitor to the discharge lamp based on a detection result of the instantaneous interruption detection means, A discharge lamp lighting device, wherein the predetermined power is controlled to be smaller than a steady supply power to the discharge lamp. 2. The discharge lamp lighting device according to claim 1, wherein said instantaneous interruption detecting means includes a differentiating circuit. 3. The apparatus according to claim 1, further comprising means for controlling a time during which the power control circuit controls power supplied from the capacitor to the discharge lamp to the predetermined power.
The discharge lamp lighting device as described in the above.