JPS6168896A - Half-cycle lighting device for high-pressure steam discharge lamps - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field 1j of the Invention] The present invention relates to a half-cycle lighting device for lighting a high-pressure vapor discharge lamp having a lamp voltage approximately equal to the power supply voltage using a switching circuit. This invention relates to loss reduction in a lighting device in which a switching circuit is connected to the center tap of a choke coil used as a ballast.

[Background of the invention]

Aiming to make discharge lamp lighting devices smaller, lighter, and more energy efficient,
The alternate cycle lighting method is a method in which when the lamp voltage of the lamp being lit is close to the power supply voltage lζ, the lamp is lit using a choke coil and a switching circuit without boosting the voltage by the lζ transformer.

In this type of lighting device, the switching circuit is usually connected in parallel with the lamp, but since high voltage pulses are applied to the switching circuit when starting the lamp and during lighting, the switching circuit has a voltage of around 1,000 volts. Therefore, a single lighting device constructed using a high-voltage switch element becomes very expensive and becomes a product drawback.

As a conventional example for reducing the voltage applied to the switching circuit, there is a discharge lamp lighting device described in Japanese Patent Application Laid-Open No. 52-132566. The circuit configuration of this conventional example is shown in FIG. During the period, energy is stored in the winding 4 on the AC power supply 1 side from the intermediate tap of the inductance 2, and during the off period of the switch element 7, the stored energy is superimposed on the AC power supply 1 and applied to the discharge lamp 3. In this operation, the ignition pulse for starting and lighting the lamp 3 is generated across the choke coil 2, but this voltage is generated between the winding 4 and the winding. The voltage of the winding 4 is superimposed on the voltage of the AC power supply 1 between the switching circuit terminals A and B. Therefore, the voltage between the terminals A and B is the same as that of the lamp 3. It becomes lower than the voltage generated at both ends, and the voltage becomes lower as the ratio of the winding 4 is smaller.

By the way, in order to perform normal operation in the lighting circuit shown in FIG. Occurs when the time is detected. These methods have no problem when the lamp voltage is close to constant, such as in a fluorescent lamp. However, in the case of high-pressure vapor discharge lamps such as metal halide lamps and high-pressure sodium lamps, most of the lamps are short-circuited in the initial stage of lighting, which causes trouble in the circuit operation of the switching element 7.

FIG. 4 shows current and voltage waveforms at the initial stage of lighting of the high-pressure steam discharge lamp. This figure shows the operating waveforms with the switching circuit removed. As is clear from this figure, at time 12 when the input current voltage 1 is O (this time t2 coincides with the time when the lamp current becomes O), there is a voltage of v, 2 between terminals A and B of the switching circuit. This means that it is occurring.

On the other hand, a connection capacitance 13' 61 is connected between terminals A and B to stabilize distributed capacitance or switching characteristics, resulting in loss in the switching element 7, resulting in heat generation and
This may even cause destruction. In addition, the lamp electrician is
Since the phase at time t2 gradually changes as the lamp impedance increases, the same problem occurs when the switch element 7 is triggered by detecting the power supply voltage v1.

[Purpose of the invention]

Therefore, it is an object of the present invention to provide low cost and.

An object of the present invention is to provide a highly reliable kumite cycle lighting device for a high pressure steam discharge lamp.

[Summary of the invention]

In order to achieve the above object, in the present invention, in the lighting device having the above-described configuration, the switching circuit is turned on when the voltage across the switching circuit is approximately zero, and when the current flowing through the switching circuit reaches a predetermined value. A Kumite cycle lighting device for a voltage vapor discharge lamp is configured so as to be turned off. It becomes possible to eliminate inrush current from the parallel connection container to the switching circuit. As a result, the loss of the switching circuit is reduced and the configuration of the switching circuit is also simplified. In other words, the present invention makes it possible to provide a low-cost, highly reliable lighting device for high-pressure steam discharge lamps every half cycle.

[Embodiments of the invention]

The present invention will be explained in detail below using examples.

FIG. 2 shows a circuit configuration of a switching circuit portion of a half-cycle lighting device for a high-pressure steam discharge lamp according to the present invention. This switching circuit is used by connecting the C and D terminals to the C and D terminals in FIG. 1 in place of the transistor 7.

In the same figure, 7 is a switch element that uses a transistor, but the power MO8FET, gate turn-off SC
Other switching elements such as R may also be used. 11 is 888
A voltage sensitive switch such as
This is a switch element that turns on when a certain voltage is applied.

12 is an avalanche diode for preserving the transistor 7.

Next, the operation of this switching circuit is shown in Figure 5).
This will be explained with reference to the voltage and current waveforms shown in (0) and Fig. 6) and (0). When the AC power supply 1 shown in FIG. 1 is turned on, the voltage passes through the winding 4 of the choke coil 2, is full-wave rectified by the full-wave rectifier 6, and is generated between terminals C and D in FIG. At this point, the voltage sensitive switch 11 is in the off state, so the transistor 7 is turned on through the resistor 10, the C and D terminals are in the on state, and a gradually increasing current force S flows through the winding 4 of the choke coil 2. As a result, the voltage across the resistor 9 gradually increases, and the base terminal voltage S of the transistor 7 increases accordingly. When the current reaches a predetermined value, the voltage sensitive switch 11 is turned on, and the base current of the transistor 7 is no longer supplied. Therefore, the transistor 7 is turned off, and the terminals C and D are turned off. As a result, a pulse voltage is generated between the A and B terminals, and this voltage is boosted to a value determined by the turns ratio of the choke coil 2 and is applied to the lamp 3 to start it.

As a result, the impedance of the lamp 3 decreases, and a current having a value close to the short-circuit current across the lamp flows. The waveforms of each part in this state are shown in FIG.
denotes the input current, and the switching current IAB flowing between the A and B terminals, respectively. In this state, it is possible to continue lighting even if the switching circuit does not work, but the switching circuit continues to operate. That is, the voltage sensitive switch 11 continues to be in the on state after the previous cutoff operation. Then, at time t1, the voltage ■AB between the A and B terminals becomes 0, and the current flowing through the voltage sensitive switch 11 becomes less than the holding current value, so the voltage sensitive switch 11 is turned off.

As a result, the continuously applied voltage drives the transistor 7 through the resistor 10 and turns it on. The voltage between A and B terminals just before this time t1 ■J and B are almost O
Therefore, the discharge current of the connected capacitor 13' flows in the transistor (switch) 7 in a pulse-like manner.Then, between times t1 and t2, the switching current flows in a triangular waveform, but the input ' During this period, a reverse source current flows in the flow control 1, and the switching current ■AB is superimposed, resulting in a discontinuous waveform.Then, the pulse generated at time [2] is unnecessary. And time C3
At the input current, the equilibrium is reversed and the switching circuit operates from time 4 to time t5, and the above operation is repeated.
The arc temperature S of the lamp 3 gradually rises, and the voltage across it rises. In this state, the lamp current has a waveform obtained by removing the switching current component from the input terminal component, and remains constant throughout the entire period without any rest period.

Figures 6(a) and 6(0) show waveforms when the arc temperature of the lamp 3 rises and the emitted 1Jt voltage becomes high. The same figure (a) shows voltage #, voltage V1, and terminal A of the switching circuit.
.

The waveform of the voltage between B and vAB is shown. The figure (b) shows the current I flowing between the input current terminal and terminals A and B of the switching circuit.
Figure 8 shows the waveform. With the waveform of input current ■1, at time t, ~
t3, time t4~[2. The part marked with . . . becomes the flow of the lamp. Time t3-t4, time t6-t7.・・・・・・
Depending on the ratio of the number of turns of the winding 4.5, the voltage across the lamp 3 may rise above the discharge voltage even during the period .

In this case, the voltage between the A and B terminals □3 drops to nearly 0 at time t3 before the previous half cycle of discharge ends. As a result, the current of the voltage sensitive switch (SBS) 11 flowing through the resistor 10 decreases below the holding current, and the pressure sensitive switch 11 is turned off. Since the voltage of the power supply voltage 1 at this point is not O, the base of the transistor 7 is immediately driven through the resistor 10, and A, B
The terminals immediately enter the 1ζ on state. As a result, the switching circuit current IABb:1 flows as shown by the broken line during the period from time t3 to time t4. And switching electrician, LB
At time t4 when reaches a predetermined current value, the base end potential of the transistor 7 reaches the breakover voltage of the voltage sensitive switch 11, the voltage sensitive switch 11 turns on, the base current of the transistor 7 becomes 0, and the A and B terminals It is off during this time. Therefore.

At time t4, a high voltage pulse is generated, the lamp 3 is re-ignited, and the lamp 3 continues to receive input current from time t4 to [6]
The same current flows. Then, at time [6], the voltage between terminals A and B decreases, and the voltage sensitive switch 11 turns off, and as a result, A.

The terminal B is turned on, and the above operation is repeated again. By repeating this operation, steady lighting is performed.

In this operation, the discharge voltage of the lamp 3 becomes equal to the value of the power supply voltage v1, so the phase at time t (1-input current factor) has shifted to just before it becomes O, and the pulse generation phase is , reliably coincides with the reversal phase of the lamp discharge polarity,
The normal operation of lighting the kumite cycle will occur. Furthermore, in this case, A.

Since the transistor 7 is turned off when the voltage vAB between the B terminals is 0, a rush current due to discharge of the connection capacitor 1113' does not flow, and normal operation is performed.

Note that the transition process from the low impedance state of the lamp 3 in Figures 5(e) and (b) to the high impedance state of the lamp 3 in Figures 6(a) and (q) is an operation in which the input current 11 gradually shifts. Therefore, as the impedance of the lamp 3 increases, the cut-off time of the switching current switch All moves to a time after the current of the input gutter cycle ends, and this becomes the ignition pulse. Therefore, the lamp 3 will not go out during the transition to the steady state.

FIG. 3 shows the configuration of a switching circuit portion in another embodiment of the present invention. In this configuration, in order to make it possible to generate a voltage of several hundred to several thousand volts necessary for starting the lamp 3, a 5CR 72 is further connected in series with the transistor 71 as a switching element. Transistor 71, S
Of course, the C-type switch 72 may be any other switching element such as a power MO8FET. To ensure the operation of this switching circuit, a capacitor 13 is connected between A and B terminals.
connected. 121, 122 are transistors 71, SC
It is an avalanche diode for protecting R, 72, and includes a diode 14, a capacitor 15, and a diode 16.
．． The circuit consisting of the resistor 17 is provided to limit the DC cutoff operation to once in each half cycle.

Since the lighting operation of this switching circuit is almost the same as that shown in FIG. 2, only the main points will be described.

When the voltage between the A and B terminals approaches 0, the voltage sensitive switch 11
turns off, and the transistor 71.5CR72 continues
is triggered through resistors 101 and 102 to turn on, and the terminals A and B are in an on state. And switching electrician. When V reaches a predetermined value, voltage sensitive switch 11 is turned on and transistor 71 is turned off. Therefore, the switching current IAB is commutated to the capacitor 13, and this voltage gradually increases. During this time, the cathode current of 5CR72 becomes O, and the 5CR
A gate turn-off trigger current flows from the gate of 72 through the resistor 102 and the pressure sensitive switch 11. As a result, the 5CR 72 is turned off during the period from when the transistor 71 is turned off until the voltage across it reaches the avalanche voltage of the avalanche diode 121.

This completes the turn-off operation between the A and B terminals, but in order for the 8CR72 to turn off reliably, the 5C
'- between A and H terminals within the turn-off recovery time of R72.
It is necessary to set the capacitance value of the capacitor 13 so that the voltage value does not exceed the avalanche voltage of the avalanche diode 121.

In this case, the inrush current caused by the discharge of the capacitor 13 during turn-on becomes a particularly serious problem.

Usually, the pulse voltage iff generated by turn-off operation
When this backswing crosses the 0 point accompanied by vibration, the voltage sensitive switch 11 is turned off, and the A and B terminals are turned on again to perform a current interrupting operation. diode 1
4. A circuit consisting of a capacitor 15, a diode 16, and a resistor 17 is a circuit for preventing this re-operation. That is, the voltage generated by the resistor 9 just before the transistor 71 is turned off is passed through the diode 14 to the capacitor 15.
is charged to. And transistor 71.5CR72
After turning off, for a while, diode 16 and resistor 17
Through this, the discharge current of the capacitor 13 flows through the voltage sensitive switch 11, and even when the above-mentioned backswing occurs, the current of the voltage sensitive switch 11 is kept above the holding voltage #. This makes it possible to reliably prevent multiple RWtrm operations. Furthermore, by connecting the capacitor 5, the voltage generated in the resistor 9 when a rush current flows at turn-on is absorbed by the diode 14, and the voltage sensitive switch 11 is connected immediately after turn-on.
It is possible to reliably prevent a malfunction in which the A and B terminals are turned off due to the turn on of the terminal.

Note that the configuration of this circuit portion is also effective for general discharge lamps such as fluorescent lamps, and is similar to A in FIG.

It is clear from the above explanation of the operation that the same effect can be obtained even when the B terminal is connected to both ends of a general discharge lamp fS.

〔Effect of the invention〕

According to the present invention, in a kumite cycle lighting device for lighting a high-pressure vapor discharge lamp via a choke coil using an intermediate tap, a switching circuit connected between the intermediate tap and the non-choke coil side end of the AC power source is provided. By detecting the voltage across both ends of the reset-off and subsequent turn-on operations, the switching circuit can be turned on over a wide operating range, from the low impedance region when starting the lamp to the high impedance region during steady lighting. Since the inrush current due to the discharge of the parallel capacitor can be eliminated, a highly reliable switching current on the order of amperes is required, and the loss due to this operation is quite large. Therefore, it is particularly important from the viewpoint of reliability to prevent inrush current of the parallel capacitor and to keep the loss of the switching element small. Also, this configuration is very simple,
The disadvantage that discharge lamp lighting circuits using semiconductor circuits are more expensive than conventional leaky transformer type circuits can be solved at once.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of a conventional Kumite cycle lighting device for a discharge lamp, and FIGS. 2 and 3 are circuit configuration diagrams of a switching circuit portion of a half-cycle lighting device for a high-pressure steam discharge lamp according to the present invention, respectively. FIG. 4 is a voltage and current waveform diagram at the initial stage of lighting in the lighting device shown in FIG. 1, and FIGS. 6(A) and 6(O) are voltage and current waveform diagrams during steady lighting in the lighting device shown in FIG. 2, respectively. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Choke coil with intermediate tap consisting of windings 4 and 5, 3... High pressure steam discharge lamp, 6...
...Full wave rectifier, 7,71.72...Semiconductor switch element with control pole, 11...Voltage sensitive switch, 12゜1
21.122... Avalanche diode, 8°14
．． 16...Diode, 13.13', 15...
・Capacitor, 10, 101, 102, 9.17...
resistance. Agent Patent Attorney Katsutoshi Ogawa

Claims (1)

[Claims] 1. An AC power source, a choke coil, and a high-pressure steam discharge lamp having a discharge voltage value around the voltage value of the AC power source are connected in series, and an intermediate tap provided on the choke coil and a non-choke coil side end of the AC power source are connected in series. A switching circuit that performs an on/off operation once every half cycle of the lighting period is connected between the switching circuit and the switching circuit, which turns on when the voltage across the switching circuit is approximately zero, and A half-cycle lighting device for a high-pressure steam discharge lamp, characterized in that the switching circuit is configured to turn off when the current flowing through the circuit reaches a predetermined value.