JP2687599B2 - Discharge lamp lighting device - Google Patents

Description

The present invention relates to a device for high-frequency lighting a discharge lamp using a high-frequency generator.

[Conventional technology]

As a lighting device capable of lighting a plurality of discharge lamps such as a fluorescent lamp and controlling the light, there is, for example, a conventional discharge lamp lighting device disclosed in JP-A-62-200685.

FIG. 7 is a circuit diagram of this conventional device. 1 is a DC power supply, 2 is a resistor, 3 is a capacitor, 4, 5 and 6 are diodes,
Reference numeral 7 is a trigger element, 8 and 9 are switching elements, which are composed of transistors here. 10,11 is resistance, 1
2 is a drive transformer, 13 and 15 are capacitors, 14 is an inductor, 16 and 17 are load discharge lamps, 18 is a preheating transformer, and 19 is a preheating switch.

In the device configured as described above, the trigger element 7
And the transistor 9 is turned on, the high frequency generator starts generating a high frequency voltage. And inductor 14
Since the capacitor 15 generates a resonant voltage, the discharge lamps 16 and 17 start discharging and light up.

In this device, since the discharge lamps 16 and 17 are connected in series, for example, when the operation of the transistors 8 and 9 of the high frequency generator is changed to perform dimming of the discharge lamps 16 and 17, both discharge lamps 16 and 17,
17 becomes equal dimming. Further, since the lights are serially lit, if one of the discharge lamps 16 is not lit, the other discharge lamp 17 is inevitably turned off.

[Problems to be solved by the invention]

Since the conventional discharge lamp lighting device is configured as described above, all the lights are dimmed or the lights are turned off. There was a problem of becoming.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a device capable of lighting a plurality of discharge lamps with a single high-frequency generator and performing individual blinking, dimming, and the like. To do.

[Means for solving the problem]

Therefore, the discharge lamp lighting device according to the present invention includes a high-frequency generator that generates high-frequency power by turning on and off direct-current power by a switching element driven by a signal from a control circuit, and the high-frequency generator in parallel with the high-frequency generator. A plurality of discharge lamps that are connected and are a load, a plurality of switch devices that are each connected in series to the discharge lamp, and a switch opening / closing control circuit that opens each of the switch devices in synchronization with a signal from the control circuit for a predetermined time. It is intended to achieve the above object by using a device having

[Action]

Each discharge lamp is turned on in full light by continuously closing each switch device connected in series with each discharge lamp via the switch opening / closing control circuit, and dimming state is set by repeatedly opening / closing these switch devices. Further, by continuing the open state, the light can be turned off.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

(Embodiment 1) FIG. 1 shows a circuit diagram of Embodiment 1 of the present invention, and the same (corresponding) components as those of the conventional example shown in FIG.

In the figure, 1 is a DC power supply, 4 and 5 are diodes, and 8 and 9 are switching elements. 13a and 13b are capacitors, 14a and 1
4b is an inductor, 15a and 15b are capacitors for resonance, and 20 is a switch device. Here, power MOS FETs 20a and 20b and diodes 21a and 21b built in (parasitic) to this element allow current to flow in an alternating current. it can. Reference numeral 22 is a control circuit that generates a signal that alternately opens and closes the switching elements 8 and 9 at a high frequency. In order to drive the oscillation circuit such as an unstable multivibrator and its oscillation stop circuit and the switching elements 8 and 9 on and off. Drive circuit and the like. twenty three
Is a switch opening / closing control circuit for controlling opening / closing of the switch device 20, and the switch opening / closing control circuit 23 is a power MOS.
It is assumed that the outputs are separated so that the FETs 20a and 20b can be opened and closed independently, and the signal generated by the control circuit 22 is
A synchronization signal is input from the input terminal 23a, and a delay circuit such as a monostable multivibrator that opens each switch device 20 in synchronization with this input signal with a predetermined time delay is provided.

The discharge lamp lighting device according to the first embodiment is provided with a high-frequency generator that alternately turns on and off direct-current power by switching elements 8 and 9 driven by a signal from the control circuit 22 to generate high-frequency power. As the load, the discharge lamp 16 and the switch device 20 connected in series thereto, and the discharge lamp 17 and the switch device 20 connected in series thereto are connected in parallel. Further, it is provided with a switch opening / closing control circuit 23 for opening / closing each of the switch devices 20 in synchronization with the signal of the control circuit 22 for a predetermined time.

The operation of the present apparatus configured as described above will be described below.

When the control circuit 22 alternately turns on and off the switching elements 8 and 9, if the switch device 20 is closed,
As is well known, the discharge lamps 16 and 17 are lit at a high frequency.

FIG. 2 is an operation explanatory diagram showing this state, in which the switching elements 8 and 9 are turned on and off by signals as shown in FIGS. 2 (A) and 2 (B), respectively. In addition, a current having a delayed phase flows through the inductors 14a and 14b, that is, the switch device 20, as shown in FIG.

Here, the power MOS FETs 20a, 20b of the switch device 20 are set to T ₁
When the switch opening / closing control circuit 23 is opened at a time such as (in synchronization with the signal (B)), the switch opening / closing control circuit 23 uses a delay circuit based on the signal (synchronized with the signal (B)) of its input terminal 23a. Since the power MOS FETs 20a, 20b of the switch device 20 are opened after a delay of time t in FIG. 2B, the switch device 20 actually opens at the time T ₂ , but the current flowing through the inductors 14a, 14b is At this time, since the current has shifted to the half cycle flowing through the diodes 21a and 21b, the current continues to flow for this half cycle, and then the discharge lamp is turned off.

In this way, no surge voltage is applied to the switch device 20 when it is opened. If the switch opening / closing control circuit 23 opens only the switch device 20 on either side of the discharge lamps 16 and 17, one lamp can be turned on and one can be turned off. FIG. 2 (C) shows the on / off states of the power MOS FETs 20a, 20b by lighting all lights.

Although the blinking is described above, the switch opening / closing control circuit 23 is repeated as shown in FIG.
If it is opened and closed (in synchronization of 10 ms or less), it can be used as a dimmed state for humans according to the period ratio of the opening and closing.
The predetermined delay time t may be set to be equal to or less than the ON period t ₀ of the switching elements 8 and 9 connected in parallel with the discharge lamps 16 and 17, but considering the phase delay of the current flowing through the switch device 20, 1 / It is optimal to set the time to 2t ₀ ≤t <t ₀ .

(Embodiment 2) FIG. 4 is a circuit diagram of Embodiment 2 of the present invention, and FIG. 5 is an operation explanatory diagram thereof. In the second embodiment, the high frequency generator is of a type using one switching element 9, and this element is turned on / off by a signal as shown in FIG. 5 (A) to generate a high frequency voltage. Here, not only can the blinking of the discharge lamps 16 and 17 be performed in the same manner as in the apparatus of FIG. 1, but dimming can be performed in the same manner as described above.

Similar to FIG. 1, in FIG. 4 as well, if the open / close period ratios of the two output signals of the switch open / close control circuit 23 are set independently, the dimming degrees of the two discharge lamps can be set separately.

(Embodiment 3) FIG. 6 is a circuit diagram showing Embodiment 3 of the present invention, and shows only a main part. In FIG. 6, capacitors 24a and 24b are connected in parallel to the switch device 20. This capacitor 2
The capacitors 4a and 24b are selected to have a capacitance less than that of the resonance capacitors 15a and 15b that perform series resonance with the inductors 14a and 14b and generate a high voltage at the time of starting.

Therefore, it is difficult to reliably start the discharge lamps 16 and 17 unless the switch device 20 is once closed, but once the discharge is started, a minute discharge current continues to flow even if the switch device 20 is opened. be able to. Therefore, the discharge is more stable even during dimming.

Although not shown in the above description, the DC power supply can be obtained by rectifying and smoothing a commercial AC power supply. Further, it goes without saying that a high-frequency generator other than the ones shown in the embodiments can be similarly used as the high-frequency generator.

Furthermore, as the switch device 20, a power MOS FET having a parasitic diode in antiparallel is most suitable, but other means such as a bipolar transistor and an antiparallel connection diode may be used.

Even if the load discharge lamps 16 and 17 are not two but three, the number of the switch devices 20 may be three, and two of the three lamps are connected in series and are lit in parallel with the other one. Etc. can be carried out in the same manner as in the embodiment.

When turning off all the discharge lamps 16 and 17, all the switch devices 20 may be opened, and in this case, it is suitable when the direct current power supply for the control circuit is generated by the high frequency generator itself. . However, it is of course possible that the operation of the high frequency generator is stopped by the control circuit 22.

Similarly, the switching elements 8 and 9 may be semiconductor elements other than bipolar transistors.

Further, the applied discharge lamps 16 and 17 can be applied to low-pressure discharge lamps in the same manner as in the embodiment other than fluorescent lamps.

(Effects of the Invention) As described above, in the device of the present invention, by opening / closing each switch device individually via the switch opening / closing control circuit, it is possible to generate a surge voltage at the time of opening the switch device even if not all of them are bundled together. Instead, there is an effect that each discharge lamp can be arbitrarily blinked or dimmed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of Embodiment 1 of the present invention, FIGS. 2 and 3 are operation explanatory diagrams of FIG. 1, FIG. 4 is a circuit diagram of Embodiment 2 of the present invention, and FIG. FIG. 6 is an operation explanatory view of the figure, FIG. 6 is a main part circuit diagram of a third embodiment of the present invention, and FIG. 7 is a circuit diagram of a conventional device. 1 is a DC power supply, 8 and 9 are switching elements, 13a and 13b are capacitors, 16 and 17 are discharge lamps, 20 is a switch device, 22 is a control circuit, and 23 is a switch opening / closing control circuit. In the drawings, the same reference numerals indicate the same (corresponding) components.

Claims (1)

(57) [Claims] 1. A high-frequency generator for generating high-frequency power by turning on and off direct-current power by a switching element driven by a signal from a control circuit, and a plurality of discharges connected in parallel to the high-frequency generator as loads. A discharge lamp lighting device comprising: an electric lamp; a plurality of switch devices each connected in series to the discharge lamp; and a switch opening / closing control circuit that opens each of the switch devices in synchronization with a signal from the control circuit for a predetermined time.