JPS58164199A - Firing device for dimming discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lighting device for dimming a discharge lamp, which controls opening and closing of a lighting circuit of a discharge lamp to perform dimming.

Conventionally, in devices that constantly preheat and turn on fluorescent lamps for photocopiers and other discharge lamps, the inverter circuit for preheating and the inverter circuit for lighting are separate. In this case, supply the dimming shaping signal from the outside,
The input power of an inverter was used as the power source for the dimming control circuit, but using separate inverter circuits for preheating and lighting makes it difficult to miniaturize the device and reduce costs. Furthermore, if the lightning source of the dimming control circuit is shared with the inverter, there is a drawback that the noise generated by the inverter will adversely affect the lighting control circuit.

In view of the above-mentioned points, the present invention provides a discharge lamp control system in which a DC power supply for a dimming control circuit is provided insulated from an inverter circuit, thereby making the device compact and easily adjustable. A lighting device for light is provided. EMBODIMENT OF THE INVENTION Below, the structure of this invention is demonstrated by the Example of illustration. - In figure VfJ, A within the chain line frame indicates an orthogonal transformation device,
B is the lighting device, 0 is the dimming control device, D is the auxiliary DC power supply,
E indicates the opening/closing control device. The orthogonal conversion device 1A converts a DC power supply voltage V into an AC voltage using an inverter 1, and has a primary winding P of an inverter transformer T on its output side. The lighting device B lights up the discharge lamp by the output of the secondary winding S1 of the inverter transformer T, and the winding 411ils2, A wound around the iron core of the inverter transformer constantly preheats the discharge lamp.

- The light control device 0 includes a transistor Tr1 to which a blinking signal (Hl or L) is input to the pace, a pulse width conversion circuit 2 receiving the output of the transistor Trl, and a variable resistor VR connected to the circuit 2. have The auxiliary DC power source is composed of an 8th winding provided in the inverter transformer T of the orthogonal converter A, a diode for rectifying and smoothing the output, and a capacitor 0, and the output of the auxiliary DC power source is the same as the dimming. Supplied to control device 0-. The opening/closing control device I is
It has a transistor Tr2 which uses the output of the dimming control device wO as a pace input, and a diode bridge 3 connected to the transistor Tr2.
is composed of diodes D2, Ds, Da, and Ds, and is connected between both ends of the winding IN S+ of the lighting circuit B and the discharge lamp.

The device of the present invention having the configuration U as described above is the lighting device B.
The discharge lamp is always preheated by M s2 and Ss, and the output of 1 tls+ by the inverter instantly turns on the discharge lamp. In addition, when adjusting the light output of the discharge lamp, the lighting (
When the ON/OFF signal is input, the voltage inverted by the transistor Trl becomes an output pulse 2 suitable for the desired dimming amount by the pulse width conversion circuit 2, and is output to the switching control device E. The transistor Tr2 is turned on and off.This transistor T
When r2 is turned on, the diode bridge 3 short-circuits both ends of the discharge lamp, and when the transistor Tr2 is turned off, the short circuit is opened. As a result, the discharge lamp is dimmed, but at this time, the variable resistor vR of the dimming control device 0
By adjusting the pulse width conversion circuit 2, the output pulse 2 of the pulse width conversion circuit 2 becomes a pulse with a duty ratio that obtains the desired dimming amount, and the short-circuit opening/closing period at both ends of the discharge lamp by turning on and off the transistor Tr2 is adjusted to the desired value. , the light output of the discharge lamp can be adjusted to a desired amount of light.

Note that the transistor Tr in the dimming control circuit 0 described above
1 is for inverting the external signal and inputting it to the pulse width conversion circuit 2. Further, the pulse width conversion circuit 2 uses an appropriate circuit such as a monostable multivibrator, a pulse expansion circuit that integrates the pulse input signal and then shapes the waveform, and the variable resistor VR is used in the integration circuit. OR
This becomes the resistance R of the time constant circuit. In addition, the diode bridge 3 connected between both ends of the discharge lamp is a transistor T.
Q is used to open and close a short circuit between both ends of the discharge lamp, and instead of this diode bridge, an appropriate switching element may be used to open and close the short circuit, or a switching element may be provided in series on the discharge lamp. .

As described above, according to the present invention, the light output of the discharge lamp can be dimmed to a desired value by simply inputting a blinking signal to the dimming control device and adjusting the variable resistor. Moreover, the preheating voltage of the discharge lamp is constant regardless of the amount of dimming.

In addition, since the DC power supply for the dimming control device is isolated and provided on the output side of the DC converter by an auxiliary DC power supply, the output waveform of the dimming control device is not adversely affected by noise. It is not a cheap circuit9, and
This makes it possible to downsize the entire device.

[Brief explanation of drawings]

The drawing shows one embodiment of a circuit for a lighting device for controlling discharge lamp dimming according to the present invention. A: Orthogonal transformation device. B8 lighting device. 0: Light control device. D: Auxiliary DC power supply. E: Opening/closing control device. 1t inverter.

Claims (1)

[Scope of Claims] (]) A lighting device having an orthogonal conversion device that converts a direct-to-direct voltage into an alternating current voltage, a circuit for lighting a discharge lamp using the output of the orthogonal conversion device, and a discharge lamp preheating circuit, and the orthogonal conversion device. An auxiliary DC power supply is installed insulated on the output side of the device and outputs a DC voltage, and the auxiliary DC power supply receives power from the auxiliary DC power supply and receives a blinking signal from the outside.When it receives a lighting signal, it outputs a dimming signal with variable duty. A dimming control device that outputs an output, a switching control device that opens and closes the lighting circuit by the output of the dimming control device, and a discharge lamp that is energized by the output of the orthogonal conversion device via the switching control device. A lighting device for dimming a discharge lamp, characterized in that: (2) The switching control device is configured to short-circuit the lighting circuit according to the output signal of the dimming control device. (8) The discharge lamp dimming according to claim (1) or (2), wherein the auxiliary DC power source rectifies and smoothes the output of a winding provided in an inverter transformer of the orthogonal conversion device. lighting device.