JPH0329297A - Lighting device of discharge lamp - Google Patents

Abstract

PURPOSE:To make each discharge lamp possible to optionally switch on-off or to dim the light without generation of any surge voltage when a switch device opens a switch on-off control circuit by individually switching each switch device through the circuit. CONSTITUTION:When a control circuit 22 switches switching elements 8, 9 on and off alternately, discharge lamps 16, 17 turn on the light by high frequency under closed condition of a switch device 20. And when it is trying to open Power MOSFETs 20a and 20b of the device 20 at the time T1, a switch on-off control circuit 23 opens the FETs 20a and 20b of the device 20 after a certain time-lag on a delay circuit complying with a signal from the input terminal 23a, and electric currents which flow through inductance 14a, 14b have shifted to diodes 21a, 21b where a half cycle flows. Thus, the discharge lamps go out after the electric currents continue to flow for the half cycle. Because of this, the surge voltage when the circuit is opened is not applied to the device 20. Putting one lamp on and the other lamp off is available when a switch opening/closing control circuit 23 opens either device 20 of the discharge lamps 16, 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for lighting a discharge lamp at high frequency using a high frequency generator.

[Conventional technology]

As a lighting device capable of lighting a plurality of discharge lamps such as fluorescent lamps and controlling the dimming, for example, Japanese Patent Laid-Open No. 62-2006
There is a conventional discharge lamp lighting device disclosed in Japanese Patent No. 85.

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, 5.6 is a diode,
7 is a trigger element, 8 and 9 are switching elements,
Here it is made up of transistors. 10.11 is a resistor, 12 is a drive transformer, 13.15 is a capacitor,
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, when the trigger element 7 becomes conductive and the transistor 9 is turned on, the high frequency generator starts generating a high frequency voltage. And inductor l4
Since a resonant voltage is generated by the capacitor 15, the discharge lamps 16 and 17 start discharging and are lit.

In this device, the discharge lamps 16 and 17 are connected in series, so 'for example, the transistors 8 and 9 of the high frequency generator
When the discharge lamps 16, 17 are dimmed by changing the operation of the discharge lamps 16, 17, both discharge lamps 16, 17 have the same dimming degree. Moreover, since they are lit in series, if one of the discharge lamps 16 goes off, the other discharge lamp 17 will inevitably go off as well.

[Problem to be solved by the invention]

Conventional discharge lamp lighting devices are configured as described above, so all the loads must be dimmed or turned off, and if even one lamp goes out due to its lifespan, all the lamps go out. There was a problem that it became.

The present invention was made in order to solve the above-mentioned RJ problem, and the purpose of the present invention is to provide a device that can light a plurality of discharge lamps with one high-frequency generator, and can perform individual blinking, dimming, etc. shall be.

[Means to solve 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 DC power using a switching element driven by a signal from a control circuit, and a high-frequency generator that generates high-frequency power in parallel with the high-frequency generator. A plurality of connected discharge lamps serving as loads, a plurality of switch devices each connected in series to the discharge lamps, and a switch opening/closing control circuit that synchronizes with a signal of the control circuit and opens each of the switch devices with a predetermined time delay. The purpose of the present invention is to achieve the above object by providing an apparatus having the following.

[Effect]

By successively closing each switch device connected in series with each discharge lamp via a switch opening/closing control circuit, each discharge lamp is brought into a fully lit state, and by repeatedly closing these switch devices, a dimming state is achieved. Furthermore, by continuing to keep the open state, the light can be turned off.

(Example) The present invention will be explained below using examples.

(Embodiment 1) FIG. 1 shows a circuit diagram of Embodiment 1 of the present invention, and the same (equivalent) #I components as in the conventional example shown in FIG. 7 are given the same reference numerals.

In the figure, 1 is a DC power supply, 4.5 is a diode, and 8.
9 is a switching element, 13a and 13b are capacitors, 14a and 14b are inductors, 15a and 15b are resonance capacitors, and 20 is a switching device, here power MOS FE720a and 20b and built-in (parasitic) With the diodes 21a and 2lb,
A current can be passed in an alternating current manner. 22 is a control circuit that generates a signal to alternately open and close the switching elements 8 and 9 at a high frequency, and includes an oscillation circuit such as an astable multivibrator, this oscillation stop circuit, and a control circuit for driving the switching elements 8 and 9 on and off. Consists of drive circuits, etc. 23
is a switch opening/closing control circuit that controls opening/closing of the switch device 20, and the output of this switch opening/closing control circuit 23 is separated so that the power MOS FETs 20a and 20b can be opened and closed independently.
The signal generated in step 2 is a synchronizing signal that is manually inputted from the human-powered terminal 23a, and is synchronized with this human-powered signal and opens each switch device 20 after a predetermined time delay. .

The discharge lamp lighting device shown in the first embodiment is provided with a high-frequency generator that generates high-frequency power by alternately turning on and off DC power by a switching element 8.9 driven by a signal from a control circuit 22. As loads, a discharge lamp 16 and a switch device 20 connected in series thereto, and a discharge lamp 17 and a switch device 20 connected in series thereto are connected in parallel. Further, a switch opening/closing control circuit 23 is provided which opens and closes each of the switch devices 20, respectively, in synchronization with the signal from the control circuit 22 and with a delay of a predetermined time.

The operation of this apparatus configured as described above will be described next.

The control circuit 22 turns on the switching elements 8.9 alternately.
When turned off, if the switch device 20 is in the closed state, the discharge lamps 16, 17 are lit at high frequency, as is well known.

FIG. 2 is an explanatory diagram showing this state of operation, in which the switching elements 8 and 9 are turned on and off by signals as shown in FIGS. 7JJ2 (A) and (B), respectively. Moreover, the inductor 14a,
14b, that is, the switch device 20, a current with a delayed phase flows as shown in FIG. 2(D), and the switch device 20 is turned on.

Here, the power MOSFET 20a of the switch device 20
, 20b at a time such as T (in synchronization with signal (B))
When an attempt is made to open the switch, the switch opening/closing control circuit 23 uses a delay circuit based on the signal from the human input terminal 23a (which is synchronized with the signal (B)), and then waits for a time t as shown in FIG. 2 (B). Power MOS FET 20a, 2 of switch device 20
0b is opened, the switch device 20 actually opens at time T2, but the inductors 14a, 14. At this time, the current flowing through diodes 21a and 2lb has shifted to a half cycle, so the current continues to flow during 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 open. If the switch opening/closing control circuit 23 opens only the switch device 20 on either side of the discharge lamps 16 or 17, one lamp will be lit. It is possible to turn off one light. Figure 2 (
C) is a power MOS FE720a with full lighting,
20b shows the on and off states.

In the above, blinking was explained, but if the switch opening/closing control circuit 23 is repeatedly opened and closed periodically (for example, with synchronization of 10 ms or less) as shown in Fig. 3 (A), it will be perceived by humans as corresponding to the period ratio of the opening/closing. It can be used in a dimmed state. The predetermined delay time t is the ON period t of the switching element 8.9 connected in parallel with the discharge lamp 16.17. If the phase delay of the current flowing through the switch device 20 is considered, %t0≦1<1. It is best to set the time to

(Embodiment 2) FIG. 4 is a circuit diagram of Embodiment 2 of the present invention, and FIG. 5 is an explanatory diagram of its operation. In Example 2, the number of high frequency generators is 1.
This type uses two switching elements 9, and these elements are turned on and off by a signal as shown in FIG. 5(A) to generate a high frequency voltage. Here too, not only can the discharge lamps 16, 17 be blinked in the same manner as in the apparatus of FIG. 1, but also dimming can be performed in the same manner as described above.

In FIG. 4, similarly to FIG. 1, if the switching period ratios of the two output signals of the switch switching 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, showing only the main parts. In FIG. 6, capacitors 24a and 24b are connected in parallel to the switch device 20. The capacitors 24a and 24b are selected to have a capacitance equal to or lower than that of the resonance capacitors 15a and 15b, which resonate in series with the inductors 14a and 14b and generate a high voltage at the time of starting.

For this reason, it is difficult to start the discharge lamp 16, 17 reliably unless the switch device 20 is once closed, but once discharge starts, a minute discharge current continues to flow even if the switch device 20 is opened. be able to. Therefore, the discharge becomes more stable even during dimming.

Although not shown in the above explanation, the DC'Ft source can be obtained by rectifying and smoothing a commercial AC power source.

Furthermore, it goes without saying that the present invention can be implemented in the same manner with high frequency generators other than those shown in the embodiments.

Furthermore, a power MOS FET having a parasitic diode in antiparallel is optimal as the switch device N20.
Other means, such as a bipolar transistor and an anti-parallel connected diode, may also be used.

If the load discharge lamps 16 and 17 are not 2 lamps, but 3 lamps, it is sufficient to use 3 switch devices 20, and 2 of the 3 lamps are connected in series and lit in parallel with one other lamp. The structure and the like can also be implemented 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. In this case, when the high frequency generator itself generates the DC power of the control circuit, .

However, it is of course possible to stop the operation of the high frequency generator using the control circuit 22.

Similarly, the switching elements 8.9 may be semiconductor elements other than bibolar transistors.

In addition, the commonly used discharge lamps 16 and 17 can be implemented as low-pressure discharge lamps in addition to fluorescent lamps in the same manner as in the embodiment.

〔Effect of the invention〕

As described above, in the device of the present invention, by individually opening and closing each switch device via the switch opening/closing control circuit,
Even if not all the lamps are used at once, each discharge lamp can be blinked or dimmed at will without generating a surge voltage when the switch device is open.

[Brief explanation of drawings]

1 is a circuit diagram of the first embodiment of the present invention, FIGS. 2 and 3 are operation explanatory diagrams of FIG. 1, FIG. 4 is a circuit diagram of the second embodiment of the present invention, and FIG. 5 is a circuit diagram of the fourth embodiment of the present invention. 6 is a circuit diagram of a main part 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, 8.9 is a switching element, 13a, 1
3b is a capacitor, 16.17 is a discharge lamp, 20 is a switch device, 22 is a control circuit, and 23 is a switch opening/closing control circuit. Note that in each figure, the same reference numerals indicate the same (equivalent) components.

Claims (1)

[Claims] A high-frequency generator that generates high-frequency power by turning on and off DC power using a switching element driven by a signal from a control circuit; a plurality of discharge lamps that are connected in parallel to the high-frequency generator and serve as loads; A discharge lamp lighting device comprising a plurality of switch devices connected in series to a 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 and with a predetermined time delay.