JPH07135085A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To provide a discharge lamp lighting device for which device protection can be performed against an input of an overvoltage by erroneous operation, or failure or malfunction of an input voltage changing part. CONSTITUTION:A device is provided with a rectifier means 11 for an inputted AC power supply voltage to output a DC voltage, a power supply means 12 to control the DC voltage outputted from the rectifier means 11 and output power to be supplied to a discharge lamp 14, and a detection means 22 to output a detection signal when the outputted DC voltage from the rectification means 11 exceeds a specified voltage. The device is composed in such a way that when the detection signal is outputted from this detection means 22, the power supply means 12 stops.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for high-intensity discharge lamps such as high-pressure mercury lamps and metal halide lamps, and more particularly to a lighting device which operates by receiving an AC power supply voltage from the outside.

[0002]

2. Description of the Related Art As a lighting device for high-intensity discharge lamps such as high-pressure mercury lamps and metal halide lamps, an AC power supply voltage such as a commercial power supply is supplied from the outside, the AC voltage is converted into a DC voltage, and then a desired voltage is restored. BACKGROUND ART A lighting device is known in which an electric power is supplied to a discharge lamp by converting into a frequency alternating current.

[0003]

In this type of lighting device, a power supply voltage much higher than the rated power supply voltage of the lighting device is input due to an erroneous operation or a malfunction when connecting to an external power source. Sometimes. For example, 10
If a 0V-only lighting device is accidentally connected to a 200V-system commercial power source, a 100V-based lighting device with a built-in manual input voltage switching unit is provided to support different power supply voltages (for example, 100V system and 200V system). If a 200V-system commercial power supply is accidentally connected while the power supply voltage is switched, the lighting device with a built-in automatic input-voltage switching unit may damage the 200V-system due to failure or malfunction of the input-voltage switching unit. 10 even though commercial power is connected
Such an inconvenience occurs when the power supply voltage of 0V system is switched to be input.

If a double overvoltage is erroneously applied,
If a component of the lighting device immediately breaks down, or if the margin on the lighting device side is large, the lamp will continue to light without noticing erroneous connection. Especially in the latter case,
Since a large amount of stress continues to be applied to each component, not only the durability of the components is significantly deteriorated, but also the entire lighting device may eventually fail.

As one circuit protection measure against such an overvoltage input, a fuse is inserted in series to the power input line and a varistor is connected in parallel between the power input terminals so that the varistor is input at the time of the overvoltage input. There is a method of turning on the fuse to let the current flow and blow the fuse. However, this method cannot be used for a lighting device that has a built-in input voltage switching unit and is capable of inputting different power supply voltages, and the varistor tends to deteriorate.

As another circuit protection measure against an overvoltage input, a fuse is inserted in series to the power supply input line, and when the rectified voltage becomes an overvoltage, the short circuit of the SCR is turned on to allow a current to flow. There is a method to blow the fuse. However, this method has a problem that a large capacity SCR is required. Further, in any of the above-mentioned methods, the fuse is blown, so that even if an error is immediately noticed, re-operation requires a great deal of trouble.

Therefore, the present invention provides a discharge lamp lighting device capable of protecting the device against an overvoltage input due to an erroneous operation or a failure or malfunction of the input voltage switching unit.

[0008]

DISCLOSURE OF THE INVENTION A discharge lamp lighting device of the present invention discharges by controlling a rectifying means for rectifying an input AC power supply voltage and outputting a DC voltage, and a DC voltage output from the rectifying means. The lamp is provided with a power supply unit that outputs power supplied to the lamp, and a detection unit that outputs a detection signal when the DC voltage output from the rectification unit exceeds a predetermined voltage. When output, the operation of the power supply means is stopped.

According to one embodiment of the present invention, the discharge lamp lighting device further comprises an auxiliary power supply circuit for generating a constant voltage for driving at least a control circuit element of the power supply means from the DC voltage output from the rectifying means. The detection signal from the detection means is applied to the auxiliary power supply circuit to stop the operation of the auxiliary power supply circuit, so that the power supply means stops operating.

According to one embodiment of the present invention, the detection signal from the detection means is applied to the power supply means as a stop signal so that the power supply means is deactivated.

The detecting means preferably includes a zener diode and a resistor connected in series between the output terminals of the rectifying means, and a transistor having a gate connected to a connection point of the zener diode and the resistor.

It is also preferable that a discharge lamp non-lighting signal is sent out when the detection signal is outputted from the detecting means.

[0013]

The rectifying means rectifies the input AC power supply voltage and outputs a DC voltage. The power supply means controls the DC voltage output from the rectifying means to output the power supplied to the discharge lamp. On the other hand, the detection means outputs a detection signal when the DC voltage output from the rectification means exceeds a predetermined voltage. When the detection signal is output from the detection means, the power supply means stops the power supply operation to the lamp directly or indirectly by stopping the operation of the auxiliary power supply circuit.

[0014]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram schematically showing the configuration of an embodiment of the discharge lamp lighting device of the present invention.

In the figure, reference numeral 10 is connected to an external AC power supply (not shown) such as a commercial power supply, and an input filter circuit for preventing noise from flowing out of the lighting device, 11 is the input filter. Reference numeral 12 is a rectifying and smoothing circuit connected to the circuit 10, and 12 is a chopper composed of a step-up or step-down DC-DC converter connected to the rectifying and smoothing circuit 11 (corresponding to the rectifying means of the present invention). It is a circuit (corresponding to the power supply means of the present invention). The chopper circuit 12 is configured such that the primary voltage is supplied before the lamp is lit and the output power (or output current) is variably controlled after the lamp is lit, and an inverter circuit 13 is connected to the output thereof. The inverter circuit 13 is configured to selectively generate a DC output or an AC output (for example, about 250 HZ), and its output has a high-intensity discharge lamp 1 such as a high-pressure mercury lamp or a metal halide lamp.
4 and the secondary winding of the trigger transformer 15 for generating a high voltage trigger are connected in series. Trigger transformer 15-1
A trigger circuit 16 for generating a trigger pulse in the secondary winding
Are connected.

The chopper circuit 12, the inverter circuit 13, and the trigger circuit 16 are connected to a control circuit 17 which is mainly composed of a microcomputer, and is configured to operate in accordance with an instruction from the control circuit 17. The control circuit 17 is further connected to a non-lighting signal transmission circuit 18, which is an interface circuit for outputting a non-lighting signal to an external display device or the like.

The rectifying and smoothing circuit 11 comprises, in this embodiment, four diodes or bridge diodes CR1 connected in a bridge and two smoothing capacitors C1 and C connected in series with each other on the output side of the bridge.
2 and a manual input voltage changeover switch S1 connected between the connection point of the capacitors C1 and C2 and the input side of the bridge. Full-wave rectification is performed when the switch S1 is off, and double voltage rectification is performed when the switch S1 is on.

An auxiliary power supply circuit 19 is connected to the output side of the rectifying and smoothing circuit 11. This auxiliary power circuit 19
Supplies a stable power supply voltage V _CC (for example, about 15 V) for driving the control circuit element to the chopper circuit 12, the inverter circuit 13, the trigger circuit 16, the control circuit 17, and the non-lighting signal transmission circuit 18. Small DC for
A DC converter. To the output of the chopper circuit 12, a dividing resistor 20 for detecting the output voltage of the chopper circuit 12 (corresponding to the lamp voltage) is connected in parallel. Further, a resistor 21 for detecting the output current (corresponding to the lamp current) of the chopper circuit 12 is connected in series between the chopper circuit 12 and the inverter circuit 13. One end of the resistor 20 and one end of the resistor 21 are connected to the control circuit 17, and the detected voltage signal and current signal are used in the control circuit 17 for lighting control.

The auxiliary power supply circuit 19 comprises a ringing choke converter type switching regulator in this embodiment, and its two input terminals are connected to the output terminals of the rectifying and smoothing circuit 11, respectively. The primary winding of the transformer L and the switching transistor Q2 are connected in series between the two input terminals. The output terminal of the auxiliary power supply circuit 19 is connected to the secondary winding of the transformer L via a rectifying / smoothing circuit. At the base of the switching transistor Q2,
An oscillating circuit including the feedback winding of the transformer L is connected, and the transistor Q2 is switching-driven by this. At the gate of the switching transistor Q2,
Further, the output terminal of the input voltage detection circuit 22 (corresponding to the detection means of the present invention) is connected.

The input voltage detection circuit 22 comprises a Zener diode CR3, a resistor R3 and a transistor Q1 which are connected in series. The connection point between one end of these Zener diodes CR3 and one end of the resistor R3 is
It is connected to the base of the transistor Q1. Resistance R3
Is connected to the ground side output terminal of the rectifying and smoothing circuit 11, and the other end of the Zener diode CR3 is connected to the resistor R.
1 and the Zener diode CR2, and is connected to the non-grounded output terminal of the rectification and smoothing circuit 11. The collector of the transistor Q1 is connected to the base of the switching transistor Q2 as the output of the input voltage detection circuit 22.

Next, the operation of this embodiment will be described in detail.

A case where the lighting device is connected to an external AC power source, for example, a commercial power source will be described. As described above, since the full-wave rectification is performed when the input voltage switching switch S1 is off and the double voltage rectification is performed when the input voltage switching switch S1 is on, in order to properly connect the power source of the lighting device, When the external power source is a lower voltage source (for example, 100V commercial power source), the power source is connected with the switch S1 turned on, and when it is a higher voltage source (for example, 200V commercial power source), the switch is connected. It is necessary to connect the power supply with S1 turned off.

If the switch S1 is connected to a power source of, for example, 200 V while the switch S1 is in the ON state due to an erroneous operation or a failure of the switch S1 itself, the output side of the rectification and smoothing circuit 11 is doubled in a steady state by double voltage rectification. A DC voltage of about 400V is generated. According to the conventional technique, since this is continuously applied to the chopper circuit 12 and the auxiliary power supply circuit 19, there is a possibility that these circuits including the smoothing capacitors C1 and C2, the inverter circuit 13 and the lamp 14 may be damaged. It was

However, according to this embodiment, when the output voltage of the rectifying and smoothing circuit 11 becomes abnormally high, the operation of the auxiliary power supply circuit 19 is stopped and the operation of the entire lighting device is stopped,
As a result, the discharge lamp 14 is controlled to be turned off.

That is, the output voltage of the rectifying and smoothing circuit 11 is applied to the input voltage detection circuit 22 via the Zener diode CR2 and the resistor R1, and this applied voltage is a predetermined value defined by the Zener diode CR3 and the resistor R3. After that, the transistor Q1 is turned on and its collector potential becomes the ground potential. As a result, the base of the switching transistor Q1 is also kept at the ground potential, the switching operation thereof is stopped, and the operation of the auxiliary power supply circuit 19 is stopped. When the operation of the auxiliary power supply circuit 19 is stopped, the power supply voltage V _CC becomes zero, the operation of the chopper circuit 12, the inverter circuit 13 and the control circuit 17 is also stopped, and the discharge lamp 14 is turned off because the power supply is stopped. Therefore, the circuits of the lighting device and the discharge lamp are protected. Further, when the power supply voltage V _CC becomes zero, the output of the non-lighting signal sending circuit 18 also becomes open, which means that the non-lighting signal is output to the external device.

The input voltage detection circuit 22 is connected to the commercial power supply of 100 V when the lighting device is properly connected to the power source and when the switch S1 is in the off state due to an incorrect operation or a failure of the switch S1 itself. When it is performed (in this case, full-wave rectification is performed, the output voltage of the rectification and smoothing circuit 11 is low and the lamp does not light), the applied voltage does not exceed the predetermined value, and therefore the switching operation of the switching transistor Q1 is performed. There is no such thing as stopping.

As described above, according to this embodiment, when the output voltage of the rectifying and smoothing circuit 11 exceeds the predetermined voltage, the detection signal is output from the input voltage detection circuit 22 and the operation of the auxiliary power supply circuit 19 is stopped. As a result, the power supply operation to the lamp 14 is also stopped. Therefore, each circuit of the lighting device and the discharge lamp can be protected against an erroneous operation or a failure of the input voltage switching switch S1. Moreover, since it can be achieved only by adding the simple input voltage detection circuit 22 including the Zener diode, the transistor, and the resistor, the circuit configuration does not become complicated and the cost does not increase. Furthermore, since the fuse is not blown, re-operation can be easily performed when an erroneous operation or a failure is immediately noticed.

In the above-mentioned embodiment, the input voltage switching switch S1 is a manual switch, but the present invention is similarly applied to the case where the switch S1 is an automatic type which is automatically turned on / off according to the input voltage. can do. That is, when the automatic switch is connected to a higher voltage source in the ON state due to malfunction or failure, the same operation as in the above-described embodiment is performed to protect the device and the lamp.

Further, even when the switch S1 is always in the ON state (when wiring is performed instead of the switch) and the voltage doubler rectification is always performed, the present invention is applied in exactly the same manner as described above. It is possible to obtain the same effect as the example.

FIG. 2 is a block diagram schematically showing the configuration of another embodiment of the discharge lamp lighting device of the present invention.

In the present embodiment, the rectifying and smoothing circuit 1
1 does not have a switch for changing the input voltage, and is configured to always perform full-wave rectification. The other constructions and effects of this embodiment are exactly the same as those of the embodiment of FIG. In other words, if the power supply voltage is much higher than the rated voltage by mistake, the voltage detection circuit 22 performs the same operation to stop the operation of the auxiliary power supply circuit 19, so that the device and the lamp are protected.

In the embodiment described above, the operation of the auxiliary power supply circuit 19 is stopped by the detection signal from the voltage detection circuit 22, but this detection signal is used as the chopper circuit 12.
Even if the chopper circuit 12 is configured to stop its operation by applying it as a stop signal, the same effect can be obtained.

The embodiments described above are merely illustrative and not limitative of the present invention, and the present invention can be implemented in various other modifications and alterations. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

[0035]

As described in detail above, according to the present invention,
The discharge lamp lighting device rectifies an input AC power supply voltage and outputs a DC voltage, and a power supply unit which controls the DC voltage output from the rectification unit and outputs electric power supplied to the discharge lamp. And a detection unit that outputs a detection signal when the DC voltage output from the rectification unit exceeds a predetermined voltage. When the detection signal is output from this detection unit, the operation of the power supply unit is stopped. Is configured to let. Therefore, each circuit of the lighting device and the discharge lamp can be protected against erroneous operation or failure of the input voltage switching unit. Moreover, since this can be achieved only by adding a simple detecting means, there is no fear that the circuit configuration will become complicated and the cost will increase. Furthermore, since the fuse is not blown, re-operation can be easily performed when an erroneous operation or a failure is immediately noticed.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing a configuration of an embodiment of a discharge lamp lighting device of the present invention.

FIG. 2 is a block diagram schematically showing the configuration of another embodiment of the discharge lamp lighting device of the present invention.

[Explanation of symbols]

 10 Input Filter Circuit 11 Rectification and Smoothing Circuit 12 Chopper Circuit 13 Inverter Circuit 14 Discharge Lamp 15 Trigger Transformer 16 Trigger Circuit 17 Control Circuit 18 Non-Lighting Signal Sending Circuit 19 Auxiliary Power Supply Circuit 22 Input Voltage Detection Circuit CR1 Diode CR2, CR3 Zener Diode Q1 , Q2 Transistor R1, R3 Resistor S1 Input voltage switching switch

Claims (5)

[Claims] 1. Rectifying means for rectifying an input AC power supply voltage to output a DC voltage, and power supply means for controlling a DC voltage output from the rectifying means to output electric power supplied to a discharge lamp. And a detection unit that outputs a detection signal when the DC voltage output from the rectification unit exceeds a predetermined voltage, and the operation of the power supply unit when the detection signal is output from the detection unit. Discharge lamp lighting device characterized in that it is configured to stop. 2. An auxiliary power supply circuit for generating a constant voltage for driving at least a control circuit element of the power supply means from a DC voltage output from the rectifying means,
2. The power supply unit is configured to stop operating when a detection signal from the detection unit is applied to the auxiliary power supply circuit to stop the operation of the auxiliary power supply circuit. The discharge lamp lighting device described. 3. The power supply means is configured to stop operating when a detection signal from the detection means is applied to the power supply means as a stop signal. Discharge lamp lighting device. 4. The detecting means includes a zener diode and a resistor connected in series between the output terminals of the rectifying means, and a transistor having a gate connected to a connection point of the zener diode and the resistor. The discharge lamp lighting device according to any one of claims 1 to 3, characterized in that: 5. The discharge lamp non-lighting signal is transmitted when a detection signal from the detection means is output, according to any one of claims 1 to 4. Discharge lamp lighting device.