JP2002190398A - Lighting device and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device where light control by a PWM control will not be accompanied by accidental extinguishing. SOLUTION: The CPU of a control circuit detects the frequency of a PWM signal supplied from the outside (step S2). The value of a detected frequency is compared with a preset reference value (step S3). If the detected frequency value is equal to the reference value (Y in step S3), a high-voltage discharge lamp is extinguished (step S4). If the detected frequency value is different from the reference value (N in step S3), the duty ratio of the PWM signal is detected (step S5). Dimming is performed, so that the output of a DC power source becomes the electric power value which corresponds to the duty ratio of the PWM signal (step S6).

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 driving a high pressure discharge lamp and a lighting device.

[0002]

2. Description of the Related Art In a conventional lighting device for a fluorescent lamp, for example, a DC control of, for example, 12 V is performed by PWM to perform dimming control from all light to turning off. This dimming control is performed by a volume or the like. For example, the duty ratio of the PWM control is varied from 0 to 100%, and the light output is varied from all light to off.

[0003]

However, when the above-described dimming control is performed, the dimming signal for instructing dimming and the extinguishing signal for instructing extinguishing are also based on the duty ratio of the PWM control. It is easy to accidentally turn off the light. Therefore, when the lamp to be turned on is a high-pressure discharge lamp, if the above-described dimming control is performed and the lamp is turned off by mistake, a long time is required for re-lighting and the turn-off time continues for a long time. There is a problem that.

An object of the present invention is to provide a lighting device that does not accidentally turn off the light even when dimming control is performed by PWM control.

[0005]

According to the first aspect of the present invention, there is provided a DC power supply; a step-down chopper for stepping down a DC output from the DC power supply; and an AC for lighting a high-pressure discharge lamp. An input means for receiving an input of a PWM signal from outside; a PWM detecting means for detecting a duty ratio of the inputted PWM signal; and a chopping of the step-down chopper based on the detected duty ratio. Dimming means for adjusting the power supplied to the high-pressure discharge lamp by controlling the switching element of the above; and frequency detecting means for detecting the frequency of the PWM signal input by the input means; When the set frequency reaches a preset value, a light-off means for controlling the switching element to turn off the high-pressure discharge lamp. ; It is to have the lighting device comprising a.

Therefore, the dimming signal for instructing dimming is P
Since the turn-off signal for turning off the light uses the duty ratio of the WM signal and uses the frequency of the PWM signal, it is possible to prevent the high-pressure discharge lamp from being turned off by mistake.

According to a second aspect of the present invention, there is provided a lighting device comprising: a lighting device main body; and the lighting device according to the first aspect provided in the lighting device main body.

Therefore, the same operation and effect as those of the first aspect can be obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.

A lighting device according to one embodiment of the present invention illuminates using a high-pressure discharge lamp, and a lighting device for driving the high-pressure discharge lamp is provided in the lighting device body.

FIG. 1 is a circuit diagram of the lighting device. As shown in FIG. 1, the lighting device 1 includes a DC power supply 2, a step-down chopper 3 connected to an output line of the DC power supply 2 to step down a DC output from the DC power supply 2, and an output side of the step-down chopper 3. And an inverter 5 for supplying the output of the step-down chopper 3 to a predetermined alternating current and supplying it to the high-pressure discharge lamp 4, and a starter 6 for starting the lighting of the high-pressure discharge lamp 4.
And

The inverter 5 comprises a full bridge circuit of four switching elements Q1 to Q4. By driving the inverter 5 in a known manner, a predetermined alternating current can be applied to the high-pressure discharge lamp 4.

The step-down chopper 3 includes a switching element Q5 for chopping the direct current output from the DC power supply 2, and a smoothing coil C for smoothing the output of the switching element Q5.

The control circuit 7 includes a microcomputer, receives a PWM signal from the outside, and switches the switching element Q5 through the drive circuit 8 based on the PWM signal.
Control.

Next, a specific processing procedure of the PWM control performed by the control circuit 7 will be described with reference to a flowchart of FIG.

As shown in FIG. 2, the CPU of the control circuit 7
Detects the input of a PWM signal from the outside (Y in step S1), detects the magnitude of the frequency of the PWM signal (step S2). Then, the detected frequency value is compared with a reference value preset in the ROM or the like of the control circuit 7 (step S3). If the detected frequency value is equal to the reference value (Y in step S3), the switching element Q5 is stopped via the drive circuit 8, and the high-pressure discharge lamp 4 is turned off (step S4).
The input means is realized by step S1, the frequency detection means is realized by step S2, and the light-off means is realized by steps S3 and S4.

If the detected frequency value is different from the reference value (N in step S3), the duty ratio of the PWM signal is detected (step S5). Then, the ON / OFF timing of the switching element Q5 is adjusted via the drive circuit 8, and the dimming control is performed so that the output of the DC power supply 2 has a power value corresponding to the duty ratio of the PWM signal ( Step S6). Step S5 implements a PWM detection unit, and step S6 implements a dimming unit.

A more specific example will be described.
If the reference value set in the OM or the like is 1 kHz, for example, and the frequency of the detected PWM signal is 1 kHz (Y in step S3), the high-pressure discharge lamp 4 is turned off (step S4) and, for example, the detected PWM When the frequency of the signal is 100 Hz (N in step S3), PW
The control is performed such that the dimming control is performed so that the power value corresponds to the magnitude of the duty ratio of the M signal (step S6).

The control circuit 7 has a system configuration that does not receive a PWM signal, which is a dimming signal, from the outside during the period from the start of lighting of the high-pressure discharge lamp 4 to the stable lighting (generally about 20 minutes). It is desirable to do. this is,
This is because the lamp voltage of the high-pressure discharge lamp 4 is not stable immediately after the start of lighting until stable lighting, and it is difficult to perform dimming. In addition, during the period from the start of lighting to the stable lighting, in order to enable the high-pressure discharge lamp 4 to shift to stable lighting at an early stage, high power is supplied to quickly raise the temperature of the arc tube. It is desirable.

According to the illumination device described above, the dimming signal for instructing dimming uses the duty ratio of the PWM signal, and the extinguishing signal for instructing extinguishing uses the frequency of the PWM signal. Turning off the lamp 4 can be prevented. This takes time to relight,
It is possible to prevent a problem that the light-off time of the high-pressure discharge lamp 4 continues for a long time.

[0021]

According to the first aspect of the present invention, the dimming signal for instructing dimming uses the duty ratio of the PWM signal, and the turn-off signal for instructing turning off uses the frequency of the PWM signal. Turning off the high-pressure discharge lamp can be prevented.

The invention described in claim 2 can provide the same operation and effect as the invention described in claim 1.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a lighting device used for a lighting device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a specific processing procedure of PWM control performed by a control circuit of the lighting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lighting device 2 DC power supply 3 Step-down chopper 4 High-pressure discharge lamp 5 Inverter S1 Input means S2 Frequency detection means S3 Light-off means S4 Light-off means S5 PWM detection means S6 Light control means

Claims (2)

[Claims] 1. A DC power supply; a step-down chopper for stepping down a DC output from the DC power supply; an inverter for converting the output of the step-down chopper into an AC for lighting a high-pressure discharge lamp; Input means for receiving the PWM signal; and PWM detection means for detecting the duty ratio of the inputted PWM signal; and controlling the chopping switching element of the step-down chopper based on the detected duty ratio to thereby provide the high-pressure discharge lamp. Dimming means for adjusting the power supplied to the power supply; frequency detecting means for detecting the frequency of the PWM signal input by the input means; when the detected frequency becomes a preset value A lighting device for controlling the switching element to turn off the high-pressure discharge lamp. 2. A lighting device comprising: a lighting device main body; and the lighting device according to claim 1 provided in the lighting device main body.