JP2004350483A - Inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive inverter device where a plurality of dimming methods can be switched since an outer controller is not required. <P>SOLUTION: The device is provided with a pair of forward serial switching elements 21 and 22 which are alternately turned on/off, fly wheel diodes 41 and 42 which are connected in antiparallel to the switching elements 21 and 22, capacitors 30, 31 and 32 constituting the half bridge-type inverter circuit with above elements and a lighting circuit 50 having a discharge lamp 51 and a ballast inductor 52 which is serial to the lamp. The device is also provided with a control microcomputer 60 switching an oscillation frequency by inputting a pulse signal (PWM signal). The control microcomputer 60 can switch a plurality of the control methods by changing the frequency of the pulse signal (PWM signal). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inverter device for controlling dimming lighting of a discharge lamp.
[0002]
[Prior art]
In an inverter device that controls the dimming of the discharge lamp (51) by inputting a pulse signal (PWM signal), the oscillation frequency of the lighting circuit (50) is varied in response to a change in the pulse width, so that the ballast inductor is changed. The current flowing through the discharge lamp (51) is varied by changing the impedance of the current limiting element such as (52). In the conventional technology, only one type of control method can be mounted on one inverter device. In order to perform dimming control by switching a plurality of control methods, it is necessary to provide a separate external control device, which is expensive. Had become something.
[0003]
[Problems to be solved by the invention]
Since no external control device is required, an inexpensive inverter device capable of switching between a plurality of dimming control methods is obtained.
[0004]
[Means for Solving the Problems]
An inverter device comprising a capacitor (30, 31, 32) constituting a half-bridge type inverter circuit, and a lighting circuit (50) formed of a ballast inductor (52) in series with a discharge lamp (51). A control microcomputer (60) for switching an oscillation frequency by inputting a pulse signal (PWM signal) is provided. The control microcomputer (60) determines the frequency of the pulse signal and adjusts the frequency by a control method corresponding to the frequency. Program for light control. .
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an embodiment of the present invention. This circuit includes a capacitor (30, 31, 32) constituting a half-bridge type inverter circuit, and includes a discharge lamp (51) and a ballast inductor (52), and a lighting circuit (50) for receiving a high-frequency voltage of the inverter circuit. A discharge lamp (51) is connected to the ballast inductor (52), and a pair of switching elements (21 and 22) are connected in series in an alternately on and off manner, and are antiparallel to the switching elements (21 and 22). And flywheel diodes (41 and 42) connected to the power supply. The switching elements (21, 22) are connected to an oscillation IC (61), and are turned on and off alternately at a frequency generated by the oscillation IC (61). The oscillation frequency is determined by the capacitor (62) connected to the oscillation IC (61) and the resistors (63, 64, 65, 66). The resistors (64, 65, 66) are connected to a control microcomputer (60). When the pulse signal (PWM signal) is input to the photodiode on the input side of the photocoupler (67), the control microcomputer (60) determines the frequency and the duty ratio of the pulse signal (PWM signal). The control method is determined by the frequency, and the dimming degree is determined by the DUTY ratio. The control microcomputer (60) continuously changes the frequency with respect to the duty ratio by changing the combined resistance of the resistors connected to the oscillation IC (51). When the DUTY ratio is small, the combined resistance is controlled to be large, so that the current flowing through the discharge lamp (51) is large. Becomes smaller.
FIG. 2 shows the relationship between the duty ratio and the dimming degree. When the frequency of the pulse signal (PWM signal) is 1 KHZ, normal dimming is performed, and when the frequency is 0.5 KHz, constant illumination control is performed. As described above, the control method can be switched by changing the frequency of the pulse signal (PWM signal).
[0006]
【The invention's effect】
According to the present invention, it is possible to obtain an inexpensive inverter device capable of switching between a plurality of control methods without using an external control device.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of the device of the present invention.
FIGS. 2A and 2B show the operation of dimming control in the device of the present invention.
[Explanation of symbols]
21/22: Switching elements 30, 31/32: Capacitors 41/42: Flywheel diode 50: Lighting circuit 51: Discharge lamp 52: Ballast inductor 60: Control microcomputer 61: Oscillation IC
62: Capacitors 63, 64, 65, 66: Resistance 67: Photocoupler

Claims (1)

A pair of switching elements (21, 22) that are alternately turned on and off; a flywheel diode (41, 42) connected in anti-parallel with each of the switching elements (21, 22); A lighting circuit (50) including a discharge lamp (51) and a ballast inductor (52) in series with the discharge lamp (51) is provided with a capacitor (30, 31, 32) constituting a bridge type inverter circuit, and a pulse signal (PWM signal) is provided. And a control microcomputer (60) for switching the oscillation frequency by inputting a pulse signal (PWM signal). The control microcomputer (60) can switch a plurality of control methods by changing the frequency of the pulse signal (PWM signal). Features inverter device.
[0001]

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