JPH0547479A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To reduce the size and the weight of a device, and to prevent deflection in emission distribution. CONSTITUTION:Filament electrodes 18a, 18b of a discharge lamp 18 are connected to a DC power source 11 through a power source switch, a current limiting impedance 13, and through switches 14-17, respectively. When the power source switch 12 is turned ON or OFF, the switches 14-17 are opened or closed at the time of ON operation. When the switches 14, 17 are closed, the switches 15, 16 are opened. When the switches 15, 16 are closed, the switches 14, 17 are opened. The direction of the lamp current running in the discharge lamp 18 is thus reversed each time the power source is input.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a discharge lamp lighting device.

[0002]

2. Description of the Related Art Conventionally, as a discharge lamp lighting device, as shown in FIG. 7, a primary winding 21 of a leakage transformer 2 is connected to an AC power source 1 and is magnetically coupled to the primary winding 21. It is known that the discharge lamp 3 is connected to the secondary winding 22. However, in this device, a large and heavy leakage transformer was used, and the device could not be made smaller and lighter. Therefore, as shown in FIG. 8, there is one in which a discharge lamp is lit by direct current. This is one in which a discharge lamp 3 is connected to a DC power source 4 via an impedance circuit 5 for current limiting. Since this device does not use a transformer, it can be made compact and lightweight.

[0003]

However, when the discharge lamp is operated by direct current, the lamp current in the discharge lamp 3 always flows in a fixed direction, and as a result, mercury vapor in the discharge lamp tube is biased. There was a problem that the light emission on the negative electrode side became weak and the light emission distribution became non-uniform. Therefore, the present invention is intended to provide a discharge lamp lighting device capable of reducing the size and weight of the device and preventing uneven distribution of light emission.

[0004]

The invention according to claim 1 is
DC power supply or pulsating current power supply, power switch for turning on and off this power supply, impedance circuit or element for current limiting,
Each of the filament electrodes is connected through four open / close switches that open / close in response to on / off operation of the power switch, a common current limiting impedance circuit or element for the power supply, and each open / close switch individually. The discharge lamp is provided, and each open / close switch is opened / closed so that the direction of the lamp current with respect to the discharge lamp is reversed every time the power switch is turned on.

According to the second aspect of the present invention, every time the power switch is turned on, all the open / close switches are once closed and then opened / closed so that the direction of the lamp current with respect to the discharge lamp is reversed. ..

[0006]

Each time the power switch is turned on, each open / close switch is opened / closed so that the direction of the lamp current with respect to the discharge lamp is reversed. Therefore, if the lamp current of the discharge lamp flows from one filament electrode to the other filament electrode when the power switch is turned on, then once the power switch is turned off and then the power switch is turned on, the lamp current of the discharge lamp is emitted from the other filament electrode. It flows to one filament electrode. Further, since each open / close switch once closes each time the power switch is turned on, each filament electrode of the discharge lamp is preheated, and smooth start-up lighting is performed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the positive terminal of the DC power source 11 is connected to the power switch 12 and the impedance circuit 13 for current limiting.
Through the first opening / closing switch 14 and the discharge lamp 1
8 is connected to one end of one filament electrode 18a, and the negative electrode terminal is connected to the other end of one filament electrode 18a of the discharge lamp 18 via the second opening / closing switch 15.

The positive terminal of the DC power source 11 is connected to the discharge lamp 1 via the power switch 12 and the impedance circuit 13 for current limiting, and further via the third opening / closing switch 16.
No. 8 is connected to one end of the other filament electrode 18b, and the negative electrode terminal is connected to the other end of the other filament electrode 18b of the discharge lamp 18 via the fourth opening / closing switch 17.

The power switch 12 and the open / close switches 14 to 17 are integrated into a rotary switch, for example, and when the operation knob is rotated, the open / close switches 14 to 17 are turned on and off. It will open and close in response. That is, when the operating knob is rotated at time t1, the power switch 12 is turned on as shown in FIG. At this time, at the same time, the first opening / closing switch 14 is switched from off to on as shown in FIG. 2 (b), and the fourth opening / closing switch 17 is shown as shown in FIG. 2 (e).
Switches from off to on. At this point, (c),
As shown in (d), the second and third open / close switches 15 and 16 are kept in the ON state. Then, at the time t2, when the mark of the operation knob comes to the power-on position, the second and third open / close switches 15 and 16 are switched from on to off as shown in FIGS. 2 (c) and 2 (d). After that, when the operation knob is rotated at time t3, the power switch 12 is turned off, but each open / close switch 1
The states of 4 to 17 do not change.

After that, when the operating knob is rotated at time t4, the power switch 12 is turned on as shown in FIG. At the same time, the second open / close switch 15 is switched from off to on as shown in FIG.
As shown in, the third open / close switch 16 is switched from off to on. At this point, the first and fourth opening / closing switches 14 and 17 are kept in the ON state as shown in FIGS. 2 (b) and 2 (e). Then, at the time t5, when the mark of the operation knob comes to the power-on position, as shown in (b) and (e) of FIG.
The open / close switches 14 and 17 are switched from on to off.

In the embodiment having such a structure, when the power switch 12 is turned on, for example, the first and fourth opening / closing switches 14 and 17 are turned on. At this point, the second and third open / close switches 15 and 16 are kept in the ON state. Therefore, a preheating current flows through each filament electrode 18a, 18b of the discharge lamp 18.

After that, the second and third open / close switches 15 and 16
Turns off. Then, the discharge lamp 18 is turned on and lit, and a lamp current flows from the filament electrode 18a on one side to the discharge electrode 18 on the other side, and is lit by direct current.

Thereafter, when the power switch 12 is turned off, the discharge lamp 18 is turned off. The OFF operation of the power switch 12 does not change the states of the open / close switches 14 to 17. After that, when the power switch 12 is turned on again, the second and third open / close switches 15 and 16 are turned on this time. At this point, the first and fourth open / close switches 14 and 17 are kept in the ON state. Therefore, a preheating current flows through each filament electrode 18a, 18b of the discharge lamp 18.

After that, the first and fourth opening / closing switches 14, 17
Turns off. Then, the discharge lamp 18 is started and lit, and a lamp current flows from the other filament electrode 18b to the one filament electrode 18a, and the discharge lamp 18 is lit by direct current.

As described above, each time the power switch 12 is turned on, the open / close switches 14 to 17 are switched, and the discharge lamp 1
Since the direction of the lamp current flowing in 8 is reversed, bias of mercury vapor in the discharge lamp is prevented and the light emission distribution of the discharge lamp 18 is made uniform.

Further, every time the power switch 12 is turned on, all the open / close switches 14 to 17 are turned on for a predetermined time, and a preheating current flows through the filament electrodes 18a and 18b of the discharge lamp 18, so that the discharge lamp 18 starts smoothly. Will be lit. Further, the discharge lamp 18 is subjected to current limiting control using the impedance circuit 13 and no leakage transformer or the like is used, so that the size and weight can be reduced. Next, another embodiment of the present invention will be described with reference to the drawings. The same parts as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The one shown in FIG. 3 uses an impedance circuit 23 composed of a forward converter. That is, the input terminal of the full-wave rectification circuit 22 is connected to the AC power supply 21 via the power switch 12, and the smoothing capacitor 24 is connected to the output terminal of the full-wave rectification circuit 22 to form a DC power supply. The impedance circuit 23 is connected to the smoothing capacitor 24, and the impedance circuit 2
The discharge lamp 18 is connected to the output terminal of No. 3 via the 1st-4th opening / closing switches 14-17.

The impedance circuit 23 has a field effect transistor 26 connected between both ends of a smoothing capacitor 24 through a primary winding 25p of a transformer 25, and a control circuit 27 supplies an oscillation signal to a gate terminal of the transistor 26. The switching operation is performed.

A rectifier circuit composed of diodes 28 and 29 is connected to the secondary winding 25s of the transformer 25, and a capacitor 31 and a diode 32 are connected in parallel via a first choke coil 30 to the output terminal of the rectifier circuit. The circuit is connected. Then, the open / close switches 14 to 17 and the discharge lamp 1 are connected to the parallel circuit via the second choke coil 34.
A circuit consisting of 8 is connected.

As described above, even when the impedance circuit 23 including the forward converter is used, the lamp current flowing in the discharge lamp 18 is inverted every time the power switch 12 is turned on, and when the power switch 12 is turned on, the lamp current is temporarily preheated. Since the current flows, the same effect as that of the above embodiment can be obtained.

The one shown in FIG. 4 uses a flyback converter utilizing the half-wave voltage resonance as the impedance circuit 33. That is, the input terminal of the full-wave rectifier circuit 22 is connected to the AC power source 21 via the power switch 12.
The impedance circuit 33 is connected to the output terminal of the full-wave rectifier circuit 22, and the discharge lamp 18 is connected to the output terminal of the impedance circuit 33 via the first to fourth opening / closing switches 14 to 17.

In the impedance circuit 33, a field effect transistor 36 is connected to the output terminal of the full-wave rectification circuit 22 via the primary winding 35p of the transformer 35, and the oscillation signal is output from the control circuit 37 to the gate terminal of the transistor 36. It is designed to be supplied for switching operation. A capacitor 38 is connected in parallel to the primary winding 35p of the transformer 35, and a diode 39 is connected in parallel to the transistor 36. 1 of the transformer 35
The secondary winding 35p and the capacitor 38 form a resonance circuit, and the transistor 36 is designed to perform a half-wave switching operation.

The secondary winding 35s of the transformer 35 is provided with a capacitor 41 and a diode 42 through a diode 40.
And a discharge lamp 1 connected to the parallel circuit via the choke coil 44.
A circuit consisting of 8 is connected.

As described above, even when the impedance circuit 33 including the flyback converter utilizing the half-wave voltage resonance is used, the lamp current flowing through the discharge lamp 18 is inverted every time the power switch 12 is turned on, and the power switch is turned on. Since the preheating current temporarily flows when 12 is turned on, the same effect as that of the above-described embodiment can be obtained.

In FIG. 5, the n DC-DC converters 451, 452, ... 45n are connected to the impedance circuit 4.
We use as 3. That is, the input terminal of the full-wave rectifier circuit 22 is connected to the AC power source 21 via the power switch 12, the impedance circuit 43 is connected to the output terminal of the full-wave rectifier circuit 22, and the output terminal of the impedance circuit 43 is connected to the first terminal. The discharge lamp 18 is connected via the 1st-4th opening / closing switches 14-17.

The impedance circuit 43 connects the input terminals of the converters 451 to 45n in series and the output terminals in series, and the series circuit of the input terminals is connected to the output terminal of the full-wave rectifier circuit 22. The discharge lamp 18 is connected to the series circuit of the output terminals via the first to fourth opening / closing switches 14 to 17.

Each of the DC-DC converters 451 to 45
n is a capacitor 4 between the input terminals a and b as shown in FIG.
6 is connected, and a parallel circuit of a constant voltage diode 48 and a capacitor 49 is connected to the capacitor 46 via a resistor 47. The control circuit 50 is connected to the capacitor 49.
Are connected.

Further, a field effect transistor 52 is connected to the capacitor 46 through a primary winding 51p of a transformer 51, and an oscillation signal is supplied from the control circuit 50 to the gate terminal of the transistor 52 so as to perform a switching operation. Is becoming

A capacitor 55 is connected to the secondary winding 51s of the transformer 51 through a rectifying circuit composed of diodes 53 and 54, and the capacitor 55 is connected to the output terminals c and d.
Connected to.

In this circuit, the output voltage from the full-wave rectifier circuit 22 is divided and input to the converters 451 to 45n. The output can be adjusted by changing the duty of the oscillation signal applied to the gate terminal of the transistor 52 in each of the converters 451 to 45n.

As described above, the plurality of DC-DC converters 4
Impedance circuit 4 consisting of 51, 452, ... 45n
Even if 3 is used, the lamp current flowing through the discharge lamp 18 is inverted every time the power switch 12 is turned on, and a preheating current flows temporarily when the power switch 12 is turned on.
The same effect as that of the above-mentioned embodiment can be obtained.

Although each of the embodiments described above uses the impedance circuit, the present invention is not limited to this, and an impedance element including only a resistor and a choke coil may be used. ..

[0034]

As described above in detail, according to the present invention, it is possible to provide a discharge lamp lighting device capable of reducing the size and weight of the device and preventing uneven distribution of light emission.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a timing diagram showing operation timings of a power switch and each open / close switch in the embodiment.

FIG. 3 is a circuit diagram showing another embodiment of the present invention.

FIG. 4 is a circuit diagram showing another embodiment of the present invention.

FIG. 5 is a circuit diagram showing another embodiment of the present invention.

FIG. 6 is a specific circuit diagram of the DC-DC converter in the embodiment.

FIG. 7 is a circuit diagram showing a conventional example.

FIG. 8 is a circuit diagram showing a conventional example.

[Explanation of symbols]

11 ... DC power supply, 12 ... Power switch, 13 ... Impedance circuit, 14-17 ... Open / close switch, 18 ... Discharge lamp.

Claims (2)

[Claims] 1. A direct current power supply or a pulsating current power supply, a power supply switch for turning on / off this power supply, an impedance circuit or element for current limiting, and four opening / closing operations for opening / closing in response to on / off operation of the power supply switch. A switch and a discharge lamp to which each end of each filament electrode is connected through the open / close switch individually through the current limiting impedance circuit or element commonly to the power source are provided, and the power switch is turned on. A discharge lamp lighting device, wherein each of the open / close switches is opened / closed so that the direction of the lamp current with respect to the discharge lamp is reversed. 2. A direct current power supply or a pulsating current power supply, a power supply switch for turning this power supply on and off, an impedance circuit or element for current limiting, and four opening / closing operations for opening / closing in response to the on / off operation of the power supply switch. A switch and a discharge lamp to which each end of each filament electrode is connected through the open / close switch individually through the current limiting impedance circuit or element commonly to the power source are provided, and the power switch is turned on. A discharge lamp lighting device, wherein each of the opening / closing switches is once closed and then opened / closed so that the direction of the lamp current with respect to the discharge lamp is reversed.