JPS6145359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides that when a discharge lamp enters a half-wave discharge state,
The present invention relates to a discharge lamp lighting device that prevents inconveniences caused by a continuation of a half-wave discharge state by substantially extinguishing the discharge lamp.

The applicant first detected the half-wave discharge state of a discharge lamp by detecting peak-like abnormal voltage, and substantially disabled the transistor inverter that is the lighting circuit, so that the half-wave discharge state of the discharge lamp was detected. An application was filed for a device that substantially prevents the continuation of the discharge state (Japanese Patent Application No. 1984-94884). Although this method is sufficiently effective when a single discharge lamp is used, it has the following disadvantages when a plurality of discharge lamps are lit in parallel. In other words, when multiple discharge lamps are lit in parallel using a balancer, a number of different conditions may occur, such as no load, only one lamp installed, and multiple lamps installed. It has been difficult to determine which of the detected voltages in each of these cases is an abnormal voltage.

The present invention is intended to eliminate such inconveniences, and is capable of detecting when a plurality of discharge lamps are connected in parallel via a balancer when the discharge lamp enters a half-wave discharge state in any case. It is an object of the present invention to provide a discharge lamp lighting device that can reliably turn off each discharge lamp substantially and prevent inconveniences caused by a continuation of a half-wave discharge state.

The present invention is characterized in that abnormal voltage when the discharge lamp enters a half-wave discharge state is detected via a detection winding that is magnetically coupled to the balancer.

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Reference numeral 1 denotes a power supply, and in this embodiment, a DC power supply consisting of a commercial power supply 2 and a rectifier 3 is shown. Reference numeral 4 denotes a lighting circuit which includes, for example, a transistor inverter 5 into which the pulsating DC voltage of the power source 1 is input. Further, this lighting circuit 4 has a balancer 6 at the output end. The transistor inverter 5 mainly includes a pair of transistors 7 and 8, an inverter transformer 9, a constant current inductor 10 provided at the input end, and a resonance capacitor 11. Such a transistor inverter 5
is, for example, 20 to 20 due to the resonance effect between the resonance capacitor 11 and the inverter transformer 9
It oscillates at 40KHz. In addition, the transistors 7 and 8 have base resistances 12, 13, and 1 at the time of starting.
The base current is supplied from the power supply 1 through the inverter transformer 9 after starting.
The output of the feedback winding 9d provided in the rectifying and smoothing circuit 15
It is supplied via. The balancer 6
A discharge lamp such as a fluorescent lamp 16, 1 is installed at both ends of the
7 is provided and connected in parallel to the lighting circuit 4. Further, each electrode is heated by a winding provided in the inverter transformer 9. As is well known, the balancer 6 is used to maintain balance between the two discharge lamps 16 and 17 connected to each other and to stably light the discharge lamps 16 and 17. If both are not installed, no voltage will be generated between both ends of the balancer 6.

A detection device 18 has a detection winding 19 magnetically coupled to the balancer 6. Furthermore, this detection device 18 includes a capacitor 20 connected in series to the detection winding 19, a rectifier 21 whose input terminals are connected to both ends of the detection winding 19 via the capacitor 20, and a connection between the output terminals of the rectifier 21. It has an impedance element 22, output terminals A and B at both ends of this impedance element 22, and an inductor 23 and a resistor 2 as necessary.
4, 25, a diode 26, etc. This detection device 18 is connected to the discharge lamps 16 and 17.
When either one of them enters a half-wave discharge state, the peak voltage generated in the balancer 6 is detected via the detection winding 19, and a detection signal is output from the output terminal.

Reference numeral 27 denotes a control device that receives the detection signal from the detection device 18 and limits the power supplied to the discharge lamps 16 and 17 via the lighting control 4, thereby substantially controlling the discharge lamps 16 and 17. It turns off the lights. In this embodiment, the power supplied to the discharge lamps 16 and 17 is limited by reducing the base currents of the transistors 7 and 8 of the transistor inverter 5. That is, a three-terminal thyristor 28 is provided between the negative terminal of the base resistor 12 and the negative terminal of the power source 1, and a series circuit of a resistor 29 and a transistor 30 is provided between the anode and gate of the thyristor 28. ,
A resistor 31 provided between the gate and cathode of the thyristor 28, a capacitor 32 provided between the base of the transistor 30 and the cathode of the thyristor 28, and a resistor 33 provided between both ends of the capacitor 32. Detection device 1
It consists of input terminals C and D corresponding to output terminals A and B of 8. Such a control circuit 27
Since the transistor 30 is off when there is no detection signal from the detection device 18, the three-terminal thyristor 28 cannot be turned on, and the three-terminal thyristor 28 is turned on only when a detection signal is input from the detection device 18. . Therefore, at this time, the base current circuits of transistors 7 and 8 of transistor inverter 5 are short-circuited, the base currents of transistors 7 and 8 are reduced, and the transistors 7 and 8 become inactive and no longer output high frequency voltage.

Next, the effect will be explained. Now, discharge lamps 16, 17
Are both installed and lighting up properly?
Alternatively, when there is no load when both the discharge lamps 16 and 17 are not installed, the output of the detection winding 19 is as shown in Figure 2a.
becomes. This is due to the characteristics of the balancer 6 as described above. Therefore, since the detection device 18 does not detect abnormal voltage, it does not output a detection signal. Since the control device 27 does not operate unless there is a detection signal, the transistor inverter 5 operates normally and outputs a predetermined high frequency voltage.

Next, when only one of the discharge lamps 16 is attached, the balancer 6 is unbalanced and the voltage shown in FIG. voltage is input. However, if the discharge lamp 16 is lit normally, the voltage is close to a sine wave as shown in FIG. 2b, and does not include abnormal peak voltages. Therefore, the capacitor 20 connected in series to the detection winding 19 exhibits a relatively high impedance with respect to the peak voltage during half-wave discharge. Therefore, the detection device 18 will not output a detection signal indicating that the discharge lamp 16 is in a half-wave discharge state due to such an input.

Next, one or both discharge lamps 16, 17
is installed, and when one exceeds half-wave discharge (there is no practical need to consider that both exceed half-wave discharge at the same time), only half-wave lamp current flows through the discharge lamp, and the balancer 6 is in a biased magnetic state, so
The output of the sensing winding 19 is as shown in FIG. 2c. In FIG. 2c, a is the peak voltage due to half-wave discharge. Such a peak voltage includes a higher frequency component than a normal sine wave. (For example, the peak voltage was 150 KHz while the sine wave in FIG. A detection signal based on the detection signal is output from output terminals A and B. Therefore, when the control device 27 receives this detection signal, first the transistor 30 is turned on, and then the three-terminal thyristor 28 is turned on. As a result, the base current circuits of the transistors 7 and 8 of the transistor inverter 5 are short-circuited, and the transistor inverter 5 becomes unable to output a predetermined output.
is effectively turned off. In this embodiment, since the power supply 1 outputs a pulsating DC voltage, the three-terminal thyristor 28 is turned off every half cycle. Therefore, discharge lamps 16, 17
is supplied with power at the beginning of each half cycle, but the peak voltage due to half-wave discharge is detected and the light is immediately turned off, so it is virtually impossible to continue the half-wave discharge state, and there is an instantaneous power supply at the beginning. There is no problem with half-wave discharge. Further, it is also possible to easily maintain the control function of the control device 27 if necessary. That is, by providing appropriate capacitors at both ends of the three-terminal thyristor 28, it is possible to keep the thyristor 28 turned on. However, in view of the fact that when a discharge lamp in a half-wave discharge state is converted into a normal discharge lamp, the power must be turned off once, the above-mentioned embodiment is preferable.

Next, FIG. 3 shows the experimental results of this example. In FIG. 3, the horizontal axis represents the input voltage of the transistor inverter, expressed as a ratio to the rated voltage, and the vertical axis represents the voltage between the output terminals A and B of the detection device 18. In addition, in Fig. 3, curve A is when two lamps are installed and both are lighting normally, curve B is when there is no load, curve C is when only one lamp is installed and lighting is normal, and curve D is 1. In the case of half-wave discharge when the lamp is installed,
Curve E shows the case where two lamps are installed and one lamp is discharging in a half wave. As is clear from FIG. 3, half-wave discharge is clearly different from other cases and can be reliably detected under any conditions. Note that F is the detection level.

FIG. 4 shows another embodiment of the present invention. Only the main parts are shown, and the other parts are omitted because they are the same as in FIG. This limits the That is, a first three-terminal thyristor 41 provided in the forward direction at the input terminal of the transistor inverter 5, a first diode 42, a resistor 43, a second diode 44 and a gate circuit of a first three-terminal thyristor 41 consisting of a series circuit of a resistor 45;
a second three-terminal thyristor 46 provided between the anode of the diode 44 and the cathode of the first thyristor 41; a resistor 47 provided between the gate and cathode of this thyristor 46; It consists of input terminals C' and D' provided at the gate and cathode, and a capacitor 48 provided between the cathode of the first diode 42 and the cathode of the second three-terminal thyristor 46. Such a control device 40 controls ON/OFF of the first three-terminal thyristor 41 based on a detection signal from a detection device (not shown in FIG. 4). When there is no detection signal, the second three-terminal thyristor 45 is not turned on, and therefore the first three-terminal thyristor 45 is not turned on.
The three-terminal thyristor 41 is turned on at a predetermined phase by a gate circuit. On the contrary,
When the detection signal is input, the second three-terminal thyristor 46 turns on and short-circuits the gate and cathode of the first three-terminal thyristor 41, so the first three-terminal thyristor 41 can no longer turn on. . That is, the first three-terminal thyristor 41, which is once turned on, continues to be turned on during a half cycle of the pulsating voltage output from the power supply 1, but is not turned on after the next half cycle. Note that the capacitor 48 keeps the second three-terminal thyristor 46 turned on once turned on regardless of the pulsating voltage, and the second diode 44 keeps the second three-terminal thyristor 46 turned on in the forward direction. This is to compensate for voltage drops. As described above, in this embodiment, the power supplied to the discharge lamp is limited by cutting off the input to the transistor inverter 5, thereby turning off the discharge lamp. However, in this embodiment, when replacing the discharge lamp with a normal discharge lamp, it is necessary to temporarily turn off the power. The other functions are the same as those of the first illustrated embodiment, so their explanation will be omitted.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be modified in various ways. For example, the lighting circuit may have a transistor inverter and output a high frequency voltage, or it may be one that lights at a commercial frequency. Further, even if the device outputs a high frequency voltage, it is not limited to the above embodiment. In short, the sensing device may be any device as long as it has a sensing winding magnetically coupled to the balancer, and the rest may be configured in any manner. Furthermore, the control device can be freely designed by combining semiconductor switching elements and the like. This control device may be provided at any position as long as it can substantially turn off each discharge lamp when one discharge lamp enters a half-wave discharge state. In addition, the number of discharge lamps is not limited to two,
Even when connected as shown in FIGS. 5 and 6, the detection windings 51 and 61 may be provided in each balancer 50 and 60.

As described in detail above, the present invention detects abnormal voltage when a discharge lamp enters a half-wave discharge state through a detection winding that is magnetically coupled to a balancer. If only the
Even when multiple lamps are installed or under different conditions, such as when there is no load, abnormal voltage can be reliably detected by skillfully utilizing the characteristics of the balancer. It is possible to provide a discharge lamp lighting device that does not need to be left unattended and can prevent inconveniences such as damage to the circuit section due to abnormal heat generation and cracking of the wall of the discharge lamp tube.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention,
Figure 2 is a voltage waveform diagram for explaining the action, Figure 3 is a diagram showing the experimental results, Figure 4 is a circuit diagram showing the main parts of another embodiment, Figures 5 and 6 are FIG. 7 is a partial circuit diagram showing still another embodiment. 1... Power supply, 4... Lighting circuit, 5... Transistor inverter, 6, 50, 60... Balancer,
18...Detection device, 19,51,61...Detection winding, 27,40...Control device, 28,41,46
...Three terminal thyristor.

Claims (1)

[Claims] 1. A power source, a lighting circuit that is supplied with power from the power source and has a balancer at its output end, and a plurality of discharge lamps connected in parallel to the lighting circuit via the balancer. , a detection device having a detection winding magnetically coupled to the balancer and outputting a detection signal when one of the plurality of discharge lamps enters a half-wave discharge state; and a detection signal of the detection device. 1. A discharge lamp lighting device, comprising: a control device for controlling power supplied to each of the discharge lamps via the lighting circuit to substantially turn off each of the discharge lamps. 2. The discharge lamp lighting device according to claim 1, wherein the lighting circuit includes a transistor inverter and outputs high-frequency power. 3. The discharge lamp lighting device according to claim 1 or 2, wherein the detection device detects a peak voltage caused by half-wave discharge of the discharge lamp. 4. The discharge lamp lighting device according to claim 2, wherein the control device reduces or cuts off the base current of the transistor of the transistor inverter. 5. The discharge lamp lighting device according to claim 2, wherein the control device cuts off input to the transistor inverter. 6. The detection device includes a detection winding magnetically coupled to the balancer, a capacitor connected in series to the detection winding, and an input terminal connected between both terminals of the detection winding via the capacitor. A discharge lamp lighting device according to claim 3, characterized in that the discharge lamp lighting device comprises a rectifier, an impedance element connected between output terminals of the rectifier, and output terminals at both ends of the impedance element. .