JPS6036080B2 - discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device that lights a discharge lamp by converting rectified pulsating exposure pressure of AC voltage into high frequency.

Recently, electronic discharge lamp lighting devices using high-frequency inverters have been used instead of conventional ballasts.

Furthermore, as a discharge lamp lighting device of this kind, a device has been proposed in which the discharge lamp is lit by a pulsating current as shown in Fig. 1, and there is no lighting pause period (Japanese Patent Application No. 125664/1989).
No. 4,017,785). This circuit example will be schematically explained with reference to FIG.

In FIG. 4, reference numeral 11 denotes a high frequency generator, such as an inverter, which includes a pair of push-pull connected transistors 1.
2a, 12b and these transistors 12a, 12b
It has an output transformer 13 having a primary winding connected to both ends of the collector. Further, the positive side electric line P, from the DC power source E obtained by rectifying the AC power source e by the rectifier D, is connected to the intermediate part 13n of the primary winding of the output transformer 13, and the negative side electric line N, The outer emitters of the transistors 12a and 12b are commonly connected. Then, the transistors 12a and 12b are alternately turned on and off by a positive feedback circuit (not shown) or a base control circuit such as an oscillator connected to the bases of the transistors 2a and 12b to generate high frequency power. 14 is a discharge lamp,
It is connected to the secondary side of the output transformer 13 via the ballast 15.

A capacitor 8 of an auxiliary DC power supply 16 is provided between the electric circuits P, , N. This capacitor 18 is connected between the output terminals of the rectifier D via a diode 17 whose polarity is opposite to that of the DC power supply E.
The lower terminal shown in the figure is connected to the balance transformer 19 to divide it into two circuits, and the intermediate tap 1 of the primary winding of the output transformer 13 is
Connect to 3t,,13 goods. That is, the power source 21 for charging the capacitor 8 is constructed by using a part of the output of the high frequency generator 11. Then, the voltage Vc across the capacitor 18 causes a pulsating current as shown in FIG. 1, and the discharge lamp 14 is lit without a lighting pause period without reducing the power factor of the AC power supply e. However, in the lighting device described above, when the discharge lamp 14 is not connected or when the load is not operating, such as before starting, the capacitor 8 becomes unloaded and the terminal voltage increases, making it necessary to specially ground the device. Something happened.

That is, in FIG. 4, when the discharge lamp 14, which is the load, is in an unloaded state and is not operating, the capacitor 18 has no discharge path, so the voltage Vc is the output transformer 13.
Since the winding ratio is actually increased, the pulsating output rises to near the peak as shown in Fig. 2.

Therefore, if the peak value is 6ooV, the sardine voltage VL
The effective value of 'made tsuba = 424V. This no-load voltage VL
If an attempt is made to suppress the voltage to 300V, which is below the product standard, it may be difficult to start the discharge lighting, or the discharge may be unstable. In addition, since an excessive voltage is applied to the capacitor 18 at this time, a highly reliable and high-voltage capacitor is required, which is disadvantageous in that it is expensive and large. Therefore, the special request
-13640 (Tokukan Sho 55-1105996), a thyristor that conducts electricity only when the load is activated and a silicon symmetrical switch that becomes conductive when the difference in voltage between both terminals exceeds a predetermined value are used. When there is no load, charging to the capacitor is prohibited to keep the terminal voltage low, and when the load is activated, the capacitor is charged via the silister, and this charging voltage is transferred to the silicon symmetrical rectifier, which becomes conductive when the output voltage of the rectifier drops. A configuration has also been considered in which DC voltage is applied to the input terminal of the high frequency generator by discharging through a switch. However, in this configuration, when the silicon symmetrical switch is turned on during load operation, the voltage at the input terminal of the high-frequency generator rapidly rises to the output peak value of the rectifier, and therefore the high-frequency component is This increases conduction noise (radio noise). Furthermore, if a voltage that changes rapidly as described above is input to the high frequency generator, abnormal oscillation may occur. Furthermore, sudden changes in the input voltage are undesirable for discharge lamps as well, and there are disadvantages in that, for example, this may cause problems with conductive ballasts, and it also increases radiation noise from the discharge lamp. The present invention was created in view of the above problems, and prevents the generation of unnecessary high voltage during no-load conditions, and provides excellent safety.
In addition, the peak value of the low-frequency pulsating current is maintained as it is, and a high voltage is applied to the discharge lamp to speed up the startup, and conduction noise, abnormal oscillation of the high-frequency generator, generation of beat, and radiation noise are reduced. It is an object of the present invention to provide a discharge lamp lighting device that can prevent such problems.

The discharge lamp lighting device of the present invention includes a rectifier into which an alternating current voltage is input, a high frequency generator supplied with the output of the rectifier, a discharge lamp energized by the output of the high frequency generator, and a capacitor. and an auxiliary DC power supply including a series circuit of diodes, which is provided between the input terminals of the high-frequency generator and supplies the charge of the capacitor to the high-frequency generator while its own voltage value is higher than the output voltage of the rectifier. a charging power supply that outputs a voltage lower than the peak value of the output voltage of the rectifier to charge the capacitor of the auxiliary DC power supply during the non-discharging period of the capacitor; and a detection device that detects the operation of the discharge lamp. , a control device that responds to the output of the detection device and controls charging of the capacitor of the auxiliary DC power supply or controls power supply from the capacitor to the high frequency generator to suppress a rise in the terminal voltage of the capacitor when there is no load; It is characterized by having the following.

An embodiment of the present invention will be described below with reference to FIG.

Note that portions corresponding to those in FIG. 4 are designated by the same reference numerals and detailed explanations will be omitted. This device also includes a rectifier D to which an alternating current voltage is input, a high frequency generator 11 supplied with the output of the rectifier D, and a discharge lamp 14 energized by the output of the high frequency generator 11.

Further, an auxiliary DC power supply 16 including a series circuit of a capacitor 8 and diodes 17, 17 is provided between the input terminals of the high frequency generator 11, and this auxiliary DC power supply 16 has a voltage value that is equal to or higher than that of the rectifier. The electric charge of the capacitor 8 is supplied to the high frequency generator 11 while the voltage is higher than the output voltage of the capacitor D. Furthermore, a charging power source 21 is provided which rectifies and outputs a part of the output of the high frequency generator 11, and this charging power source 21 outputs a voltage lower than the peak value of the output voltage of the rectifying device D. This capacitor 8 replaces the capacitor 8 of the auxiliary DC power supply 16.
It is designed to charge during the non-discharge period. 25 is a control device, which is provided in the charging path between the electrical circuit P and the illustrated upper terminal of the capacitor 8 in the auxiliary DC power supply 16, and includes a switching element that suppresses the terminal voltage of the capacitor 8;
For example, it is formed by a silicon controlled rectifier (hereinafter referred to as SCR).

Trigger terminals a and b are provided at the gate and cathode of the SCR, and are connected to the output terminal of the detection device 27.
This detection device 27 detects the operation of the discharge lamp 14, that is, whether or not the discharge lamp 14 is lit, based on the lamp current, and utilizes a ballast 15 provided in the output circuit to the discharge lamp 14. .

That is, the detection winding 28 is wound around the ballast 15, and the end of the detection winding 28 is connected to the rectifier circuit 29, and the capacitor 31 and resistor 32 provided in the DC side electrical circuits P, N2 of the rectifier circuit 29 are connected to the rectifier circuit 29. , 33 to the trigger terminals a and b. Therefore, this detection device 2
7 detects the operation of the discharge lamp 14 by the electric power generated in the detection winding 28, rectifies this in the rectifier circuit 29, and then applies it as a trigger signal between the trigger terminals a and b of the SCR serving as the control device 29. In the above configuration, when the discharge lamp 14 is connected to the output transformer 13, the high frequency power generated in the output transformer 13 by the high frequency generator 11 is supplied to the discharge lamp 14 via the ballast 15, causing the discharge lamp 14 to be lit at high frequency. At this time, the detection device 27 detects the load operation by the detection winding 28 provided on the ballast 15, and uses the output thereof to provide a trigger signal to the SCR as the control device 25 to turn it on. Therefore, the capacitor 8 starts charging, and when the output voltage of the rectifier D becomes equal to or less than the predetermined value of the valley, it is discharged and the high frequency generator 1
1, and as a result, a pulsating lamp voltage as shown in FIG. On the other hand, the discharge lamp 14 is connected to the output transformer 13.
In a state where the SCR is not connected or in an unloaded state before starting, the ballast 15 is not energized even if the high frequency generator 11 operates, so the detection device 27 does not turn on the SCR.

In this way, the control device 25 responds to the output of the detection device 27 and suppresses the rise in the terminal voltage of the capacitor 18 of the auxiliary DC power supply 16 when there is no load.
is not charged, and the waveform of the no-load voltage VL in this case is the third
As shown in the figure, even if the peak value is 600V, the effective value of high frequency waves with low frequency pulsating current increases. =300V. In this way, since the no-load voltage VL can be lowered, there is almost no need to specially ground the device as in the conventional case.

Furthermore, since the withstand voltage of the capacitor 18 of the auxiliary DC power supply 16 can be lowered, there is no need to use a high withstand voltage, that is, a large and expensive capacitor, unlike the secondary capacitor, and the device can be made smaller and lower in cost. This further improves reliability. - In the above embodiment, the operation of the discharge lamp 14 is detected by the current flowing through the parallax 15, but of course it is not limited to this, and detection can also be made by the voltage of each circuit, the presence or absence of light output, heat, etc. It's okay.

Furthermore, in another embodiment shown in FIG.
and the balance transformer 19.

Even with this configuration, the detection device 27 detects that the discharge lamp 1
If the SCR as the control device 25 is turned on only when power is supplied to the controller 4, the same effect as the embodiment shown in FIG. 5 can be obtained. Furthermore, as shown in FIG. 7, the auxiliary DC power supply 16 includes a capacitor 18 that is charged with the rectified output of the AC power supply e by a rectifier 36 different from the rectifier D that supplies the output to the high frequency generator 11. You may also use

In this case, the voltage of the AC power source e is stepped down by the step-down transformer 37 and then rectified to charge the capacitor 8. However, since the charging voltage is set to be quite high considering the load condition, the terminal voltage of the capacitor 8 increases when there is no load. is about to rise, but
This can be prevented by using the SCR as the detection device 27 and the control device 25, as in the above embodiment. In addition, in each embodiment, the capacitor 8 is connected to the open circuit P,,N, via one or two diodes 17, so that when the load is operated, the terminal voltage of the capacitor 8 is the output of the rectifier ○. As soon as the voltage becomes even slightly higher than the voltage value, the capacitor 18 discharges and supplies the voltage to the high frequency generator 11. Therefore, the voltage supplied to the high frequency generator 11 is the first voltage.
As shown in the figure, the changes occur smoothly, and conduction noise and abnormal oscillation of the high-frequency generator do not occur, and the radiation noise of the discharge lamp does not increase.
It also prevents humming due to inductive ballast. Note that the present invention is not limited to the above-mentioned embodiments, and various modifications are possible.

For example, other well-known devices may be used as the high frequency generator 11. In addition, the control device 25 controls when the load is inactive (
It may also be possible to lower the charging voltage of the capacitor 8 (when there is no load). For example, in the embodiments shown in FIGS. 5 to 7, a variable impedance device may be inserted in the charging circuit, and the impedance of the impedance device may be made relatively large when there is no load. Alternatively, in the embodiment shown in Fig. 7, the step-down transformer 37 is provided with a switching tap, and the capacitor 8 is
You may also charge the battery. Furthermore, the power supply to the high frequency generator may be controlled during no load. For example, the terminal voltage of the capacitor 8 may be suppressed by providing a pseudo load to the capacitor 18. That is, Figures 5 to 7
In the illustrated embodiment, a series circuit of a switching device and a pseudo load may be provided between both terminals of the capacitor 8, and the switching device may be turned on when no load is applied.
Note that, in the present invention, the time when the load is not operating includes the time when the load is not operating normally.

As described above, the present invention compensates the low voltage portion of the rectified pulsating voltage of the AC voltage with the output voltage of the auxiliary DC power supply, and supplies a voltage with no rest period to the high frequency generator.
Since load operation is detected and the output voltage of the auxiliary DC power supply capacitor is suppressed when the load is not active, the no-load voltage can be kept low, providing excellent safety and suppressing the peak of low-frequency pulsating current. Since the value remains the same, it is possible to apply a high voltage to the discharge lamp, speeding up the start-up, and also to reduce the output voltage of the auxiliary DC power supply while the voltage value of the auxiliary DC power supply is higher than the output voltage value of the rectifier when the load is activated. Since the voltage is supplied to the high-frequency generator, the voltage supplied to the high-frequency generator changes smoothly, and conduction noise and abnormal oscillation of the high-frequency generator do not occur, and the radiation noise of the discharge lamp does not increase. Furthermore, even when an inductive ballast is used, it is possible to prevent humming. Furthermore, the withstand voltage of the capacitor of the auxiliary DC power supply can be lowered, and therefore an inexpensive and small capacitor can be used.

Furthermore, there is no need to ground the device, and the configuration can be simplified.

[Brief explanation of drawings]

Figures 1 and 2 are waveform diagrams showing the voltage waveforms under load and no load when the output of the auxiliary DC power supply is added.
The figure is a waveform diagram showing the no-load voltage waveform when the output of the auxiliary DC power supply is suppressed, FIG. 4 is a circuit diagram showing a subordinate device, and FIG. 5 is a circuit diagram showing an embodiment of the device of the present invention. , 6 and 7 are circuit diagrams showing other embodiments of the device of the present invention. D... Rectifier, 11... High frequency generator, I4... Discharge lamp, 16... Auxiliary DC power supply, 17... Diode, 18・・・・・・
Capacitor, 21... Charging power supply, . 25...
...SCR as a control device, 27...Detection device. Diagram *2 Diagram 3 Diagram 4*5 Diagram 6 Diagram

Claims (1)

[Claims] 1. A rectifier that inputs an alternating current voltage, a high-frequency generator that is supplied with the output of this rectifier,
A discharge lamp energized by the output of the high-frequency generator and an input terminal of the high-frequency generator including a series circuit of a capacitor and a diode, and the voltage of the high-frequency generator is higher than the output voltage of the rectifier. an auxiliary DC power supply that supplies the charge of the capacitor to the high-frequency generator; and a voltage lower than the peak value of the output voltage of the rectifier to charge the capacitor of the auxiliary DC power supply during the non-discharge period of the capacitor. A charging power supply, a detection device that detects the operation of the discharge lamp, and a device that responds to the output of this detection device to control the charging of the capacitor of the auxiliary DC power supply when there is no load, or to consume the power of the capacitor in a pseudo load. A discharge lamp lighting device comprising: a control device for suppressing a rise in terminal voltage of the capacitor. 2. The discharge lamp lighting device according to claim 1, wherein the charging power source rectifies and outputs a part of the output of the high frequency generator. 3. The discharge lamp lighting device according to claim 1 or 2, wherein the detection device detects a lamp current of the discharge lamp. 4. The discharge lamp lighting device according to any one of claims 1 to 3, wherein the control device is a switching element provided in a charging path of a capacitor of the auxiliary DC power supply.