JPH0589987A - Discharge lamp lighting device and illuminator - Google Patents

Abstract

PURPOSE:To prevent flickering of a discharge lamp through simple circuit constitution when source voltage is suddenly lowered. CONSTITUTION:A peak voltage detection circuit comprising a diode 50, a capacitor 46 and resistances 71, 72, 73, 74, 75 is provided between the collector and emitter of an oscillation transistor 53 and a constant voltage circuit 90 is attached to the peak voltage detection circuit. When source voltage is suddenly lowered and the voltage between the collector and emitter of the oscillation transistor 53 is dropped to below a withstand strength value, a fixed voltage of a Zener diode 92 is applied to the connecting point of the resistances 72, 73 and the resistivity of a MOSFET 59 is held constant and therefore the ON period of the transistor 52 is not changed while control of the output of a high frequency oscillating circuit is stopped. Flickering of a discharge lamp is thus prevented through simple circuit constitution.

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 and a lighting device provided with a safety circuit for preventing destruction of a high frequency oscillation circuit due to overvoltage, and more particularly to safety when the input voltage of the high frequency oscillation circuit fluctuates. The present invention relates to a discharge lamp lighting device and a lighting device capable of operating a circuit appropriately.

[0002]

2. Description of the Related Art Conventionally, fluorescent lamps, metal halide lamps, mercury lamps and high-pressure sodium lamps have been commercialized as discharge lamps. In the conventional discharge lamp lighting device for lighting such a discharge lamp, the voltage between the collector and the emitter of the oscillation transistor of the high-frequency oscillation circuit becomes constant in order to stabilize the illuminance of the discharge lamp against changes in the power supply voltage. Are controlled.

However, the power supply connected to such a conventional discharge lamp lighting device may have a sudden change in the power supply voltage when an addition such as an air conditioner or an elevator is connected which changes greatly with time. When the power supply voltage fluctuates rapidly, the voltage of the control circuit does not synchronize with the fluctuation of the power supply due to the problem of control response speed, and the voltage between the collector and emitter of the oscillation transistor of the high-frequency oscillator circuit is controlled stably. Difficult to do and causes flicker in the discharge lamp. A method of complicating the circuit to prevent such flicker of the discharge lamp can be considered, but this makes it vulnerable to an external surge.

[0004]

In the conventional discharge lamp lighting device described above, when the power supply voltage fluctuates rapidly, the voltage between the collector and the emitter of the oscillation transistor of the high frequency oscillation circuit is controlled stably. It is difficult to use and causes flicker in the discharge lamp.

Therefore, the present invention is capable of preventing the discharge lamp from flickering when the power supply voltage changes abruptly with a simple circuit structure and protecting the switching element against an excessive voltage. It is intended to be provided by.

[0006]

A discharge lamp lighting device according to the present invention according to claim 1 is a rectifying means for rectifying an AC voltage from a commercial AC power source to obtain a DC voltage, and the DC voltage from the rectifying means. A high-frequency oscillation circuit that outputs a high-frequency voltage by performing on / off control in a state in which the on-time can be adjusted by a switching element, a discharge lamp to which the output of this high-frequency oscillation circuit is supplied, and an input voltage from the rectifying means. When the detected voltage exceeds the set value, the on time of the switching element is reduced to control the output voltage of the high-frequency oscillator circuit to be constant, and the detected voltage is below the set value. In that case, an on-time control means for disabling the on-time control of the switching element is provided.

An illumination device according to the present invention as defined in claim 2 is
Rectifying means for rectifying an alternating voltage from a commercial alternating current power source to obtain a direct current voltage, and a high frequency for outputting a high frequency voltage by on / off controlling the direct current voltage from the rectifying means with a switching element in an adjustable on time. The oscillating circuit, the discharge lamp to which the output of the high-frequency oscillating circuit is supplied, and the voltage corresponding to the input voltage from the rectifying means are detected, and when the detected voltage exceeds a set value, the ON time of the switching element is detected. To control the output voltage of the high-frequency oscillator circuit to be constant, and when the detected voltage is less than or equal to a set value, the on-time control means for disabling the on-time control of the switching element, and the rectifier. Means, constant current generating means, high frequency oscillating circuit, and circuit means are housed inside, and a discharge lamp and a high frequency oscillating circuit are provided on the outside of the housing for mounting the discharge lamp. Characterized by comprising a socket for electrical connection.

[0008]

According to this structure, the on-time control means detects the voltage of the oscillating transistor and controls the on-time of the transistor to be constant when the detected voltage has a set value below. Therefore, the fluctuation of the control circuit disappears when the power supply voltage changes abruptly with a simple circuit configuration,
The flicker of the discharge lamp can be prevented.

[0009]

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

FIG. 1 is a circuit diagram showing an embodiment of a discharge lamp lighting device according to the present invention.

In FIG. 1, a high frequency removing capacitor 42 and a rectifying circuit 43 are connected between terminals of a commercial AC power source. The AC power supply voltage from the commercial AC power supply 41 is applied to the rectifier circuit 43 and the capacitor 4 forming the smoothing circuit.
4, 45, 46, coil 47, diodes 48, 49,
It is rectified and smoothed by 50. The high-frequency oscillation circuit is of the one-stone self-excited voltage resonance type.
A resonance capacitor 52 is connected in parallel to one primary winding 51a, and an oscillation transistor 53 is connected to one end of the primary winding 51a. The secondary winding 51b of the high frequency transformer 51 is
One end is connected to the electrode at one end of the discharge lamp 54, and the other end is connected to the electrode at the other end of the discharge lamp 54 through the primary winding of the positive feedback current transformer 55. A starting capacitor 56 is connected in parallel with the discharge lamp 54. One end of the secondary winding of the positive feedback current transformer 55 is connected to the base of the transistor 53. Between the other end of the secondary winding of the transformer 55 and the emitter of the transistor 53, capacitors 57 and 58 for controlling the on-time of the transistor 53, and MOSFE.
T59 is connected. The base of the transistor 53 is connected to the positive side of the rectifier circuit 43 via the resistor 60, and the diode 61 and the resistor 6 for controlling the on-time are also connected.
It is connected to the negative electrode side of the rectifier circuit 43 via 2, 63. M
The OSFET 59 functions as a variable resistor, and a driving voltage is supplied to its gate. MOSF
The resistance value of the ET59 can be controlled by its drive voltage.

A control circuit for controlling the oscillation voltage of the oscillation transistor 53 to be constant is provided at the collector of the oscillation transistor 53. That is, the oscillation transistor 5
A peak voltage detection circuit including a diode 50, a capacitor 46, and resistors 71, 72, 73, 74, and 75 is provided between the collector and emitter of the transistor 3, and the peak voltage value obtained at the connection point of the resistors 73 and 74 is a transistor. We are typing into the base of 76. The emitter of the transistor 76 is connected to the positive electrode side of the power supply rectifying circuit 43 via the resistors 77 and 78, the collector of the transistor 76 is connected to the negative electrode side of the power supply rectifying circuit 43 via the resistor 79, and the MOS
It is connected to the gate of the FET 59. On the other hand, the resistance 77,
The connection point of 78 is the rectifier circuit 43 via the capacitor 81.
It is connected to the negative electrode side of.

The peak voltage detection circuit has a resistor 7
A constant voltage circuit 90 is connected so that the peak voltage value obtained at the connection points of 3,74 does not drop below a predetermined value. The constant voltage circuit 90 includes zener diodes 91 and 92.
And a resistor 93 and transistors 94 and 95. The Zener diode 91 has a cathode connected to a connection point of the resistors 71 and 72 via a resistor 96 and an anode connected to a base of the transistor 94. The transistor 94 has a collector connected to the base of the transistor 95, is connected to the positive electrode side of the rectifier circuit 43 via resistors 93 and 78, and has an emitter connected to the positive electrode side of the rectifier circuit 43. The transistor 95 has a collector connected to the resistor 7 via the anode / cathode path of the Zener diode 92.
2, 73 connected to the emitter and the rectifier circuit 43
Is connected to the positive electrode side of.

On the other hand, the collector / emitter path of the transistor 96 is connected in parallel to the resistor 63 for controlling the on-time. The base of the transistor 96 has an anode / cathode path of a Zener diode 97 and resistors 98 and 78.
Is connected to the positive terminal of the rectifier circuit 43 via a series connection of, and when the voltage of the rectifier circuit 43 exceeds a predetermined dangerous value, the on time of the transistor 53 is reduced.

Although not shown, a circuit for generating a high voltage when starting the lamp is provided between the electrodes of the discharge lamp 54.

The operation of such an embodiment will be described below.

First, the reason why the voltage of the rectifier circuit 43 does not exceed the predetermined dangerous value will be described below.

When the voltage of the rectifying circuit 43 exceeds a predetermined dangerous value, the Zener diode 97 is turned on, the transistor 96 is turned on, and the on-time of the transistor 53 is reduced.

Next, the collector of the oscillation transistor 53
The operation due to the variation of the voltage between the emitters will be described.

When the collector-emitter voltage of the oscillation transistor 53 exceeds the withstand voltage value, that is, when the peak voltage value is larger than a predetermined value set by the constant voltage circuit 90, the constant voltage circuit 90 Turn off. This will be described in detail. When the Zener diode 91 is turned on and the transistor 94 is turned on, the base voltage of the transistor 95 becomes low level and the transistor 95 is turned off. As a result, the Zener diode 92
Therefore, no voltage is applied to the connection point of the resistors 73 and 74, and the peak voltage detection circuit inputs the peak voltage value obtained at the connection point of the resistors 73 and 74 to the base of the switching transistor 76 by the collector voltage of the oscillation transistor 53. To do.
As the peak voltage value increases, the collector voltage of the transistor 76 maintains a constant low level and the MOSFET 59
Of the transistor 53 is shortened, the ON period of the transistor 53 is shortened, and the output of the high frequency oscillation circuit is reduced. As a result, the high frequency oscillation circuit is controlled so that the oscillation output becomes constant.

When the collector-emitter voltage of the oscillation transistor 53 becomes equal to or lower than the withstand voltage value, that is, when the peak voltage value is equal to or lower than the predetermined value set by the constant voltage circuit 90, the constant voltage circuit 90 is turned on. To do. This will be described in detail. When the Zener diode 91 is turned off and the transistor 94 is turned off, the base voltage of the transistor 95 becomes high level and the transistor 95 is turned on. As a result, at the connection point of the resistors 72 and 73,
The constant voltage of the Zener diode 92 is applied, and the peak voltage detection circuit inputs the constant peak voltage value obtained at the connection point of the resistors 73 and 74 by the constant voltage of the Zener diode 92 to the base of the transistor 76. As a result, the collector voltage of the transistor 76 becomes a constant low level, the resistance value of the MOSFET 59 does not change from the state where the collector-emitter voltage of the oscillation transistor 53 is the withstand voltage value, and the ON period of the transistor 53 does not change. The output of the high-frequency oscillator circuit is not controlled.

According to this embodiment, when the collector-emitter voltage of the oscillating transistor 53 exceeds the specified value, the oscillating output of the high-frequency oscillating circuit is controlled to be constant, and the oscillating transistor 53 is controlled. When the voltage between the collector and the emitter becomes equal to or lower than the withstand voltage value, there is no danger of destroying the oscillation transistor 53, so the control of the output of the high frequency oscillation circuit is stopped. As a result, there is no excessive reaction of the control circuit of the oscillating transistor with respect to a sudden change in the power supply, so that the flicker of the light emission of the discharge lamp due to the fluctuation of the commercial AC voltage can be minimized with a simple circuit configuration.

FIG. 2 is a cross-sectional view of a lighting device when the discharge lamp lighting device of FIG. 1 is applied to a general domestic lighting device.

In FIG. 2, reference numeral 101 is a housing of the lighting device, and the upper surface of the housing 101 is attached to the ceiling 102. Inside the housing 101, a circuit 103 except the discharge lamp 54 of the discharge lamp lighting device of FIG. 1 is housed. On the lower surface of the housing 101, a pair of sockets 104, 1
04 is provided, the discharge lamp point 54 is attached between the sockets 104, 104, and the socket 10
The discharge lamp point 54 and the circuit 103 are electrically connected via 4, 104.

With such an illuminating device, the discharge lamp lighting device of FIG. 1 can be actually used.

[0026]

According to the present invention, it is possible to prevent the discharge lamp from flickering when the power supply voltage is drastically lowered with a simple circuit structure, and thus it is possible to provide a user with a discharge lamp lighting device and a lighting device of high quality.

[0027]

[Brief description of drawings]

[0028]

FIG. 1 is a circuit diagram showing an embodiment of a discharge lamp lighting device according to the present invention.

[0029]

FIG. 2 is a cross-sectional view of a lighting device to which the discharge lamp lighting device of FIG. 1 is applied.

[0030]

[Explanation of symbols]

 41 Commercial AC Power Supply 43 Rectifier Circuit 44 Smoothing Capacitor 51 High Frequency Transformer 53 Oscillation Transistor 54 Discharge Lamp 90 Constant Voltage Circuit

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[Procedure amendment]

[Submission date] October 21, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

Claims (2)

[Claims] 1. Rectifying means for rectifying an AC voltage from a commercial AC power source to obtain a DC voltage, and ON / OFF control of the DC voltage from the rectifying means by a switching element so that the ON time can be adjusted to a high frequency. A high frequency oscillating circuit that outputs a voltage, a discharge lamp to which the output of this high frequency oscillating circuit is supplied, detects a voltage corresponding to the input voltage from the rectifying means, and when the detected voltage exceeds a set value, An on-time control that reduces the on-time of the switching element to control the output voltage of the high-frequency oscillation circuit to be constant, and disables the on-time control of the switching element when the detection voltage is less than or equal to a set value. And a discharge lamp lighting device. 2. Rectifying means for rectifying an alternating voltage from a commercial alternating current power source to obtain a direct current voltage, and high frequency by controlling on / off of the direct current voltage from the rectifying means in a state where an on time can be adjusted by a switching element. A high frequency oscillating circuit that outputs a voltage, a discharge lamp to which the output of this high frequency oscillating circuit is supplied, detects a voltage corresponding to the input voltage from the rectifying means, and when the detected voltage exceeds a set value, An on-time control that reduces the on-time of the switching element to control the output voltage of the high-frequency oscillation circuit to be constant, and disables the on-time control of the switching element when the detection voltage is less than or equal to a set value. Means, a rectifying means, a constant current generating means, a high frequency oscillating circuit, and a circuit means, and a casing for accommodating the discharge lamp, the casing being provided outside the casing. An illumination apparatus being characterized in that includes a socket for electrically connecting the high-frequency oscillator.