JPS5953677B2 - discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device that can dim a high-pressure discharge lamp or perform constant power control.

Input current phase control is generally used as a means for changing the power supplied to a discharge lamp, such as when dimming the discharge lamp.

When the power supplied to the discharge lamp is changed by this phase control, as is well known, a lamp current quiescent period occurs in each half wave of alternating current in accordance with the phase control angle. Here, in low-pressure discharge lamps such as fluorescent lamps, the gas pressure inside the tube is low, so
Since the ions in the tube were not completely extinguished even during the pause period of the lamp current, it was possible to dim the lamp using the phase control described above.
On the other hand, high-pressure discharge lamps such as mercury lamps, metal halide lamps, and high-pressure sodium lamps have high gas pressure inside the tube.
If a pause period occurs in the lamp current due to phase control, ions will disappear.

Therefore, the restriking voltage becomes extremely high, which is essentially the same as restarting the engine. As is well known, restarting a high pressure discharge lamp requires a long time or high pressure. For these reasons, when the input voltage of 50/60 (H2) is phase-controlled, problems such as the discharge disappearing, the flickering becomes severe, and the luminous efficiency decreases significantly, it is necessary to control the high-pressure discharge lamp by phase control. No lighting was done. For this reason, conventional high-pressure discharge lamps have been dimmed by changing the impedance of the ballast itself.

That is, the impedance of the ballast with respect to the high-pressure discharge lamp is changed by switching between a terminal derived from the midpoint of the ballast coil and a terminal derived from the end of the coil on the side opposite to the power source using a changeover switch. I was adjusting the light. However, such a configuration requires a large ballast with complicated wiring. Also, continuous dimming was not possible. Note that the low-pressure discharge lamp can be dimmed and lit by phase control as described above, but for this purpose it is necessary to constantly heat the filament.

Therefore, as a ballast, in addition to a leakage transformer for supplying phase-controlled power between the discharge electrodes, a separate transformer is required to constantly supply non-phase-controlled power to the filament, which is large and complicated. Requires a ballast for proper wiring. On the other hand, for dimming low-pressure discharge lamps, high-frequency generators, such as inverters, are used to generate output without any pauses without reducing the power factor, without increasing the complexity and size of the ballast described above. , a device was proposed that enabled dimming by phase control (Japanese Patent Application No. 125666/1989).
(Japanese Patent Publication No. 59-50093).

Here, the above inverter is a commercial 50/60 (Hz)
The DC voltage fed back from the inverter is added to a DC power supply that has been full-wave rectified from the AC input of the DC power supply, so that each pulsation of the full-wave rectified waveform of the DC power supply does not fall below a certain voltage. . The waveforms of each part of this inverter are
This will be explained using figures. FIG. 1a shows a phase-controlled commercial AC input waveform. The inverter's DC power circuit has
A full-wave rectified version of this AC input is supplied, and a DC voltage fed back from the power supply from the inverter is added. High-frequency output voltage V2 of the inverter that reversely converted this DC power supply. The waveform of is as shown in FIG. Of this waveform, VDC
is a high frequency output voltage based on the DC voltage fed back from the power source from the inverter described above. In addition, C in the same figure shows the load voltage V
, d shows the waveform of the load current 1L, respectively. Here, among the output voltages 20, the output voltage VDO based on the above-mentioned DC voltage is a voltage within a range that does not cause the discharge lamp to reach main discharge (arc discharge) and suppresses it to glow discharge.

When a low-pressure discharge lamp is lit by an inverter that generates such a high-frequency output voltage V2O, the main discharge starts at the indicated maximum value of the output voltage V2O, and then the voltage V
Continue until it drops to near DO. The above output voltage V. O
, the main discharge cannot be maintained, but the filament current continues. That is, the filament current can be maintained substantially constant regardless of the phase angle of the AC input. Therefore, dimming is possible with a relatively simple circuit. With an inverter having such characteristics, dimming and lighting of a low-pressure discharge lamp can be performed satisfactorily as described above, but when a high-pressure discharge lamp is turned on, the above-mentioned problems (turning off, discharge flickering, reduction in efficiency, etc.) occur.

This is the voltage out of the output voltage 20. This is because the main discharge does not occur in the section where it becomes o. That is, in a high-pressure discharge lamp, when the voltage VDC of the high-frequency output voltage V2O from the inverter falls below a certain value, the lamp impedance increases rapidly, the lamp current decreases rapidly, and the lamp goes out. Furthermore, unlike low-pressure discharge lamps, high-pressure discharge lamps do not require preheating of the filament, so there is no need to suppress the main discharge in order to keep the filament current constant. Therefore, it is also substantially difficult to light a high-pressure discharge lamp using a conversion device that has no restrictions on the voltage of the auxiliary power source. An object of the present invention is to convert a DC power source obtained by controlling the phase and rectifying an AC input using a conversion device, and to discharge a high-pressure discharge lamp with the output thereof. To provide a discharge lamp lighting device capable of lighting a high-pressure discharge lamp without turning it off even when phase control is performed on an AC input by applying a substantially constant DC voltage sufficient to maintain the lamp.

The present invention will be described below with reference to an embodiment shown in the drawings.

In FIG. 2, 11 is a commercial AC power source, which is connected to the input full-wave rectifier 14 of the converter 13 via a power regulator 12 that obtains a phase control output. And this full wave rectifier 14
At the same time, a phase-controlled rectified output is supplied to the conversion device 13. As the power adjustment device 12 using phase control, a bidirectional thyristor (hereinafter referred to as a triax) may be used. The conversion device 13 inversely converts the output rectified by the full-wave rectifier 14 into alternating current of a predetermined frequency, and may use, for example, an inverter device. This inverter device 13 has an output transformer 15 and semiconductor switching elements 16a, 16b which are push-pull connected to the ends of main windings 15a, 15b of the output transformer 15. As the semiconductor switching elements 16a and 16b, for example, NPN transistors are used as shown in the figure. The collector is connected to the main winding 15a of the output transformer 15,
15b, respectively. Further, each emitter is connected in common, and then connected to a negative side electric path N of a full-wave rectifier 14 having a constant current inductor 17. Furthermore, each base is connected to the positive side electric path P of the rectifier 14 via a starting resistor 18, and is also connected to the feedback winding 15C of the output transformer 15. Incidentally, the above-mentioned positive side electric circuit P is also connected to an intermediate point 15n between the main windings 15a and 15b of the output transformer 15. Furthermore, a resonant capacitor 2 is connected between both ends of the main windings 15a and 15b.
Connect 0. Here, the electric circuits P and N on the plus side and the minus side become input terminals of the inverter device 13. 22
is a high-pressure discharge lamp such as the aforementioned mercury lamp or metal halide lamp, and the main windings 15a, 1 are connected via an inductor 23.
5b, and lights up upon receiving the high frequency output generated by the inverter device 13.

Reference numeral 25 denotes an auxiliary power supply that supplies DC voltage to the input terminals P and N of the inverter device 13, and has a capacitor 26 whose one end is connected to the positive electric circuit P, a cathode connected to the other end of the capacitor 26, and an anode connected to the negative side. It consists of a diode 27 connected to the electric path N.

29 is a feedback circuit for feeding back a part of the output to the DC power supply via the capacitor 26, and the balance transformer 3
0, and its winding middle portion 30n is connected to the illustrated lower terminal of the capacitor 26.

Also, both ends of the winding of the balance transformer 30 are connected to a diode 3.
It is connected to the intermediate taps 15a1, 15b1 of the main windings 15a, 15b via 1a, 31b. In the above configuration, when a power switch (not shown) is turned on, AC input from the commercial AC power supply 11 is applied to the full-wave rectifier 14 after passing through the triax 12 .

The triax 12 controls the phase of the AC input to an arbitrary phase angle as shown in FIG. 1a by means of a trigger signal applied to its gate terminal. The AC input whose phase has been controlled in this way is full-wave rectified by the full-wave rectifier 14 and applied to the input terminals P and N of the inverter device 13. Therefore, one of the pair of transistors 16a, 16b is turned on via the starting resistor 18, becomes conductive, and the inverter device 13 starts operating. After that, the feedback winding 15
A pair of transistors 16 are feedback-controlled by the output of C.
A and 16b are alternately turned on and off. Therefore, a high frequency output is generated via the main windings 15a and 15b of the output transformer 15, and is supplied to the high pressure discharge lamp 22. Further, as the inverter device 13 operates, the capacitor 26 of the auxiliary power source 25 is also charged via the feedback circuit 29.

Since the charging voltage of the capacitor 26 is applied to the input terminals P and N of the inverter device 13, each pulsating current of the full-wave rectified waveform from the full-wave rectifier 14 does not fall below a certain value due to the charging voltage of the capacitor 26. Therefore, inverter device 1
The waveform of the high frequency output voltage 20 of No. 3 is as shown in FIG. 3a. Here, in the present invention, in the waveform of FIG. 3a.

o, that is, the output voltage based on the DC voltage applied from the DC voltage circuit 25 is set sufficiently large, and the high-pressure discharge lamp 22 maintains the main discharge (Arter discharge) also in the section A due to this output voltage VOO. For this purpose, the main windings 15a, 1
Either increase the ratio (n1/N) of the number of turns n1 of the intermediate taps 15a1 and 15b1 to the number N of turns of the intermediate tap 5b, or reduce the inductance of the balance transformer 30, and use a capacitor 26 with a sufficiently large capacity. .
In this way, the output voltage V. If O is set, a sufficient load current h flows in section A as shown in FIG. Incidentally, FIG. 3b shows the waveform of the load current VL. In this way, approximately 50% dimming is possible. However, in the above configuration, even if a sufficiently large feedback is applied by the feedback circuit 29, VOO in FIG. In this case, the VOO will also change significantly.

Therefore, in such a case, the embodiment shown in FIG. 4 may be used. In this embodiment, the feedback circuit 29 shown in FIG. 2 is not used, and instead, a power transformer 36 which receives AC power before phase control from the commercial AC power supply 11 is used.
Use.

The secondary output of the power transformer 36 is rectified by a rectifier 37 and then applied to the capacitor 26 to charge it. Here, the capacitor 26 has one end connected to the negative side electrical circuit N.
The other end is connected to the positive electric circuit P through a diode 27 in the forward direction, and serves as an auxiliary power source 25 for the input ends P and N of the inverter device 13. With this configuration, the charging voltage of the capacitor 26 serving as the auxiliary power source 25 is constant, so even if the AC input is largely phase-controlled, the voltage V in the output voltage 20 of the inverter device 13 remains the same.

O is kept constant. Therefore, by controlling the phase of the AC input, the high-pressure discharge lamp 22 will always produce a stable main discharge (arc discharge) even if the light is significantly dimmed, and the discharge will disappear or disappear.
No problems such as flickering occur. Furthermore, if it is desired to keep the voltage of the capacitor 26 constant, a voltage regulator 38 as shown in FIG. 5 may be used.

In this way, even if the load seen from the capacitor 26 changes, the voltage of the capacitor 26 can always be kept constant. A well-known constant voltage device 38 can be used as such a constant voltage device 38. Furthermore, an inverter (not shown) which receives the secondary side rectified output of the power transformer 36 as an input may be provided, and the capacitor 26 may be charged by the output of this inverter.
Further, when controlling the power of the high pressure discharge lamp 22 to be constant, it may be done as shown in FIG.

That is, for example, a detection device 40 for detecting the lamp current of the high-pressure discharge lamp 22 is provided on the secondary side of the inductor 23, and after rectifying and smoothing the signal of this detection device 40, the comparison device 4
This comparison device 4
The gate signal generation phase of the gate signal generation circuit 42 may be controlled by negative feedback based on the output of the gate signal generation circuit 42. In this way, the input can be controlled according to the half cycle of the AC power supply 11,
The high pressure discharge lamp 22 can be controlled with constant power. Comparison device 4 above
1. A well-known gate signal generation circuit 42 can be used. Further, the detection device may be one that detects the lamp voltage, light, etc. of the high-pressure discharge lamp 22. As described above, according to the present invention, by adding a DC voltage sufficient to maintain lighting of a high-pressure discharge lamp to a DC power supply with a full-wave rectified waveform, the output voltage of the inverter device based on the DC voltage can be changed to the DC power supply of the high-pressure discharge lamp. Since the main discharge is maintained, even if the input is phase controlled, there will be no problems such as the discharge disappearing or flickering as in conventional methods, and it can be used for dimming high pressure discharge lamps and constant power control. enable.

[Brief explanation of the drawing]

Figures 1A, b, c, and d are waveform diagrams when a low-pressure discharge lamp is lit using an inverter output whose input is phase-controlled.
The figure is a circuit diagram showing an embodiment of the discharge lamp lighting device according to the present invention, FIGS. 3A, b, and c are waveform diagrams when the high-pressure discharge lamp is lit by the circuit of FIG. 2, and FIGS. 4 and 5. , FIG. 6 is a circuit diagram showing another embodiment of the present invention. 1]... AC power supply, 12... Power adjustment device, 13... Conversion device, 22... High pressure discharge lamp, 25... Auxiliary power supply, 26...
・Capacitor, P, N... Input terminal.

Claims (1)

[Claims] 1. An AC power supply, a power adjustment device that obtains a phase-controlled rectified output from the output of the AC power supply, a conversion device that converts the output of the power adjustment device into a high frequency, and an output power source using the output of the conversion device. The converter is provided at the input section of the converter so that the converter generates an output equal to or higher than the discharge sustaining voltage of the high-pressure discharge lamp during a period when the voltage is higher than the phase control rectified output of the high-pressure discharge lamp to be energized. A discharge lamp lighting device characterized by comprising an auxiliary power source that supplies power to a conversion device. 2. A patent claim characterized in that the auxiliary power source includes a capacitor that is charged by a part of the output of the converter, and is configured to apply the charging voltage of the capacitor to the input terminal of the converter. The discharge lamp lighting device according to item 1. 3. The auxiliary power source according to claim 1, characterized in that the auxiliary power source includes a capacitor that is charged by an AC power source and is configured to apply the charging voltage of the capacitor to the input terminal of the converter. Discharge lamp lighting device.