JPS61142696A - High pressure vapor discharge lamp lighting circuit - 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 of Application of the Invention] The present invention relates to an improvement in a high-pressure steam discharge lamp lighting circuit, and in particular,
This invention relates to the prevention of flickering phenomenon that occurs during the luminous flux rising period after starting a high-pressure steam discharge lamp in a half-cycle lighting circuit aimed at reducing size and weight.

[Background of the invention]

As a means of saving power, making the discharge lamp lighting circuit smaller and lighter, when the power supply voltage and lamp voltage are approximately equal, a choke coil connected in series with the lamp is turned on and off once every repair cycle. There is a lighting circuit that can be lit without using a voltage step-up by a transformer, by using a lighting circuit consisting of a lamp and a switch connected in parallel. Figure 1 shows a conventional example of such a lighting circuit (for example, Japanese Patent Laid-Open No. 52-132
566), in which the choke 2# terminal of the switch 3 connected in parallel with the lamp 4 is connected to the intermediate tap of the chimney. A feature of the lighting circuit connected in this way is that, compared to the case where the switch 3 is connected to both ends of the lamp 4, the voltage applied to the lamp can be increased to a voltage determined by the power supply voltage and the turns ratio using a switch with the same blocking voltage resistance. . For example, if the voltage of AC power supply l is vl, (number of turns of coil 202/number of turns of coil 201) is n, and the blocking voltage of switch 3 is v8, then the pulse voltage vL that can be generated across the lamp 4 is expressed by the following formula: 6 represented, for example, n
= 1, V3 = 800V.

When V=100V, Vt becomes 1500V.

VL= (1+n)Vs-nVt (1)
On the other hand, in the lighting circuit shown in FIG.
(total number of turns of coil 201/number of turns of coil 201). Transistor.

For switching elements such as power MO5FET, the control current is I
Although it is possible to achieve close to OA, the blocking withstand voltage tends to be small, at most several hundred volts. Therefore, the circuit configuration shown in FIG. 1 is practical in a high-pressure steam discharge lamp that does not require an electrode preheating circuit.

The operation when the high pressure steam discharge lamp is turned on will be explained with reference to the waveform diagram in FIG. 2. Figure (a) shows the waveform during steady lighting. Here, Vl is a power supply voltage waveform, 11 is an input current waveform, and VL is a lamp voltage waveform.

VP is the restriking pulse voltage waveform. When the voltage across the switch 3 becomes 0 at time t1 when a half cycle of discharge ends with the switch 3 in the off state, the switch 3 is turned on. At this point, the lamp current, that is, the input current, has decreased to approximately O, but at the time of turn-on, the input current of the same polarity as that just before time t1 may flow through the switch 3.

Then, the switch current gradually increases, charging the choke coil 2 with electromagnetic energy, and reaches the cutoff current I cut at time t, and at time t, the switch 3 is turned off at time t.
1 to t2, the voltage of the AC power source 1 is applied to the winding 201, a voltage of twice the turns ratio is generated in the winding 202, and this voltage is applied to both ends of the lamp 4 with the same polarity as immediately before time lt. The Rukoto. If this voltage is higher than the discharge voltage, lamp current will flow even during this period. In FIG. 2(a), no current flows through the lamp 4 during the period from time t1 to time t2.

At time t2, switch 3 causes cutoff current I cut
When the lamp 4 is cut off, a high voltage pulse voltage VP is generated, and the lamp 4
The polarity will be reversed and it will fire again. Thereafter, the switch 3 remains off, and the electromagnetic energy charged in the choke coil 2 is superimposed on the voltage of the AC power supply 1, causing the lamp 4 to discharge for half a cycle, and the voltage across the switch 3 becomes 0. At time t4, the switch 3 is closed again, the polarity is reversed, and the same operation as at times t1 to t4 is repeated, and by continuing this operation, steady lighting is performed.

Immediately after the lamp starts, the impedance of a high-pressure steam discharge lamp is extremely low, and a current close to the short-circuit current flows. The operation at this time is different from that during lighting, and the waveform is as shown in Figure 2 (b).In other words, since the lamp voltage VL is significantly smaller than the voltage V of the power supply 1, the degree of delay in the input current 11 is At time t1, when the voltage across the switch 3 becomes 0, the input current has a large instantaneous value, and the switch 3 is turned on at this time. Then, at time t2 when the current flowing through the switch 3 reaches a predetermined value, the switch 3 is turned off, but the polarity of the current does not change even at this time. Then, at time t3, the input current, that is, the lamp current becomes 0, the polarity is reversed, and from then on at time 1. −
The lamp 4 is gradually warmed up by repeating the same operation as in step 13.

As the lamp warms up, the lamp voltage gradually increases and the current advances. Then, in a transient state in which the polarity is reversed when the current is cut off and re-ignition by a pulse is possible, the light emission of the lamp 4 exhibits extreme flickering. This flickering continues for ten to several tens of seconds, during which time the lamp 4 continues to warm up and the lamp voltage increases. Then, the flickering eventually stops, and the lamp voltage further increases until it reaches the rated lamp voltage, reaching a steady lighting state.

The waveform when the lamp 4 is flickering is as shown in FIG. 2(C).

That is, with only one polarity, the restignition (time ti+iy> occurs) due to the pulse, and with the other polarity, even after the pulse is generated (time t4), the polarity current before the switch 3 is turned on flows for a while (times t4 to t6). , then performs a natural restriking, so.

The pulsed restriking polarity has a large lamp discharge current, while the natural restriking polarity has a small lamp current, resulting in extreme flickering. During the half cycle due to pulse restriking, the current is large, and the phase delay in which the current reaches zero is large, so that each restriking tends to become a spontaneous restriking. During the half-cycle due to spontaneous restriking, the current is small, the point of end of flow is advanced, and the next restriking is likely to be a pulse restriking.

Therefore, the unbalance of the current waveform for each half cycle becomes large. This phenomenon occurs in a limited range where the voltage at the center of the half-cycle discharge of the lamp voltage diameter is 1, for example, at a power source of 100 V and a frequency of 50 Hz.

It was confirmed that when the impedance of the choke coil is about 50Ω, this occurs at around 50 to 60V.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a high-pressure steam discharge lamp lighting circuit using a choke coil with an intermediate tap, which can prevent the flickering phenomenon of lamp light emission that occurs during the warm-up period after starting the lamp. Our goal is to provide the following.

[Summary of the invention]

In order to achieve the above object, the present invention provides.

In the above-mentioned high-pressure steam discharge lamp lighting circuit, the voltage between the connection end of the choke coil and the high-pressure steam discharge lamp and the negative terminal of the DC output end of the full-wave rectifier connected to the input end of the switch circuit is controlled by a constant voltage element. The high-pressure steam discharge lamp lighting circuit is characterized in that the high-pressure steam discharge lamp lighting circuit is configured to control the on/off operation of the switch circuit based on the detection.

In other words, the above-mentioned flickering phenomenon occurs within a limited range of lamp discharge pressure, as described above.

Therefore, in the present invention, after the lamp is started, the current interrupting operation by the switch circuit is stopped until the lamp voltage reaches a voltage that does not cause flickering, or the circuit is configured so that the current is interrupted with a sufficiently low current. This is to prevent flickering.

[Embodiments of the invention]

The details of the present invention will be explained below based on examples.　　.

FIG. 3 shows one embodiment of a high pressure steam discharge lamp lighting circuit according to the present invention. Switch 3 is capacitor 5
and a full-wave rectifier 6 and a switch circuit connected to its DC output terminal AB. A circuit connected to the side end C of the choke coil 2 of the lamp 4 (constant voltage diode 19. diode 20. resistor 21. capacitor 22. resistor 23.
The diode 24) is a circuit configuration for preventing flickering according to the present invention. The switch circuit part includes a transistor 7, a 5CR8 having a gate turn-off characteristic in the current domain, a constant voltage diode 9゜10 for their protection, a current detection resistor 14, and the voltage across it is a constant voltage, for example 8■. A switch element (S
BS) Consists of 15. 5BSI'5 has a gate terminal to which the anti-flicker circuit described above is connected. In this case, it turns on when the voltage between the anode and cathode of (SBS) 15 exceeds the bias voltage applied to the gate.

Resistors 11 and 12 are the base and gate trigger resistors of the transistor 7.5CR8, and 13 is a diode for keeping the emitter potential of the transistor 7 higher than the base potential when the 5BS15 is in the on state. diode 16.1
7. The circuit consisting of the capacitor 18 and the resistor 25 is designed to prevent the interruption operation during no-load from occurring many times in a half cycle.

The operation of this lighting circuit during lighting will be described below with reference to FIG. 2(A) again. When the voltage across switch 3 becomes 0 near the end of a half-cycle discharge of lamp 4, SBS
15 turns off. The subsequent rising voltage across switch 3 triggers transistor 7.5CR8 through resistors 11, 12, turning switch 3 on.

Therefore, the lamp voltage becomes lower than the discharge holding voltage, the lamp current stops, and a gradually increasing current flows through the switch circuit.

Then, at time t2 when the current value reaches a predetermined value, SBS 15
reaches the breakover voltage due to the voltage drop across the resistor 14 and turns on. As a result, the base current of transistor 7 is no longer supplied, and transistor 7 is turned off.

As a result, the current flowing from the full-wave rectifier 6 through the A and B terminals is commutated to the capacitor 5, and this voltage increases. During that time, the cathode current of 5CR8 is O, and all the anode current flows as gate reverse current, and after a while, 5C
R8 is also turned off, and the switch 3 is turned off. During the period from time t2 to t4, the 5BS15 remains on, and the switch 3 remains off. At time t4, the switch 3 is turned off again.
The BS 15 turns off and repeats one or more operations to remain lit.

In the above operation description, the capacitor 22 is charged to a sufficiently high voltage, and the SBS 15 is charged to a constant voltage (for example, 8V).
) to cause a breakover. The circuit consisting of diodes 16, 17, a capacitor 18.degree. resistor 25 is for preventing the circuit from being cut off many times during a half cycle during no-load operation, which occurs when the lamp 4 goes out. That is, in this state, the Q value is high and a large oscillating voltage occurs after the pulse is generated. Diode 16.17. Without the circuit consisting of the capacitor 18 and the resistor 25, when this voltage becomes 0, the current of the 5BS15 becomes less than the holding current and turns off.

Then, due to the voltage that rises immediately after that, transistor 7.
5CR8 is turned on, and switch 3 performs the current cutting operation again. This operation is repeated until the end of the middle cycle, and the power consumption of the circuit of switch 3 becomes large, which may lead to breakdown. This circuit consisting of diodes 16 and 17, capacitor 18, and resistor 25 operates when the switch circuit is on.

The voltage generated in the resistor 14 is charged to the capacitor 18 through the diode 16, and after the 5BS15 is turned on, the voltage generated in the resistor 14 is charged to the capacitor 18 through the diode 17.
．． Depending on the time constant circuit of resistor 25, a certain time SBS l
5 is kept above the holding current.

Thereby, the shutoff operation can be performed reliably once every half cycle.

Next, the prevention of luminous flux flickering occurring during the luminous flux rising period, which is an object of the present invention, will be described. The flickering phenomenon occurs when the lamp voltage is within a certain value range (for example, when the power supply voltage is 100V, it is about 50 to 75V). Before and after the flickering, the voltage waveforms generated between one terminal B of the DC output of the full-wave rectifier 6 and the terminal C of the choke coil side of the lamp are as shown in Fig. 4 (a) and (b). ) is an example of a waveform when flickering occurs, and (b) in the same figure is an example of a waveform when flickering has ended. Constant voltage diode 19.
Diode 20. Resistance 21. Capacitor 22. resistance 23
．． The circuit connected between the C and B terminals of the diode 24 utilizes this difference in waveform to either stop the cutoff operation of the switch circuit immediately after starting the lamp 4 until the lamp voltage corresponding to the flickering state is reached, or This is to perform the cut-off operation at a small current value, thereby eliminating the flickering phenomenon caused by the switch operation.

The avalanche voltage of the constant voltage diode 19 is selected to be Vz in FIGS. 4(a) and 4(b). When the power supply 1 is turned on, the charging voltage of the capacitor 22 is O, and even with a small voltage, the gate trigger current of the SBS 15 is reduced to the diode 24.
through the capacitor 22, and the SBS 15 is turned on. Therefore, a small current flows through the transistor 7, SC:R8, and the transistor is turned off immediately after being turned on. Therefore, immediately after the power supply 1 is turned on, the switch 3 is equivalent to being in an off state. Therefore, a power supply voltage waveform appears at both ends of the lamp 4, which acts as a constant voltage diode.

Diode 20. The capacitor 22 is charged through the resistor 21, and the play-forever voltage Vz of the voltage regulator diode 19 is naturally lower than the peak value of the power supply voltage. Following the charging of capacitor 22, 5BS
The breakover voltage of No. 15 gradually increases, and the breaking current also gradually increases. Therefore, when the pulse voltage generated across the lamp 4 increases and exceeds the breakover voltage of the lamp 4, the lamp 4 starts. After the lamp 4 is started, the impedance of the lamp 4 is extremely reduced, the lamp voltage is reduced to about 30V or less, and the charge in the capacitor 22 is discharged through the resistor 23.

Again, the interrupting current is reduced to approximately 0.

Thereafter, the vapor pressure of the lamp 4 gradually increases, and the lamp voltage increases. And between the CB terminals (circuit element 19,
The voltage waveform applied to the circuit (composed of circuits 20, 21, 22, and 23) begins to exceed Vz in some parts, and the capacitor 22 is charged little by little and begins to perform the interrupting operation again. However, the voltage waveform applied to the circuit in series with the constant voltage diode 19 at the time when flickering occurs is as shown in FIG. 4 (A), and if Vz is selected as shown in the figure.

It is possible to suppress the cut-off current value below the value that causes flickering. Then, the CB at the point when the stable lighting condition is reached.
The voltage applied between the terminals is sufficiently higher than Vz as shown in Fig. 4 (b), and the charging voltage of the capacitor 22 is SBS.
The SBS 15 is charged above the breakover voltage when there is no gate circuit, and the SBS 15 operates in a state where it is disconnected by the gate circuit, and performs lighting operation in the rated state.

In addition, 26 is a fuse, which is a single circuit that is used to prevent secondary disasters such as burnout of the choke coil 2 when the full-wave rectifier 6 and the electronic circuit connected to it or the capacitor 5 are broken. If the switch circuit only interrupts the current and there is no need to flow the lamp electrode preheating current, the current value during steady operation will be around 1/10 or less than the short circuit current value due to switch 3 failure. Since it can be set, protection by fuses is possible.

〔Effect of the invention〕

As described above, the present invention provides a high-pressure vapor discharge lamp lighting circuit in which a switch circuit for cutting off current connected in parallel to the lamp is connected via the intermediate tap of the choke coil, and the connection end between the lamp and the choke coil. The voltage between the (-) side output terminal of the full-wave rectifier of the switch circuit is detected using a constant voltage diode, and the voltage is used to control the cut-off current value of the switch circuit. This makes it possible to effectively prevent the phenomenon of light flux flickering that occurs with a simple circuit.

[Brief explanation of the drawing]

Figure 1 is a basic circuit diagram of a conventional discharge lamp lighting circuit, and Figure 2 (
A) to (C) are operating waveform diagrams, FIG. 3 is a circuit diagram of an embodiment of the high-pressure steam discharge lamp lighting circuit according to the present invention, and FIG.
(b) is a detection waveform diagram. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Choke coil having windings 201 and 202, 3... Switch circuit, 4... High pressure steam discharge lamp, 5.18.22... Capacitor, 6...
...Full wave rectifier, 7...Transistor, 8...5C
R19, 10, 19... Constant voltage diode, 15...
・SBS. 13.16.17, 20.24...Diode, 11
．． 12, 14, 21, 23, 25...Resistance, 26...
・Fuyuse. VJ l Illustration fan 3 Low - ¥14 figure

Claims (1)

[Claims] 1. A series circuit consisting of an AC power supply, a choke coil having an intermediate tap, and a high pressure vapor discharge lamp having a lamp voltage approximately equal to the effective voltage value of the AC power supply, and a series circuit between the intermediate tap of the choke coil and the non-operating A high-pressure steam discharge lamp lighting circuit comprising: a switch circuit connected between the choke coil and the high-pressure steam discharge lamp, and a switch circuit that performs an on/off operation at the beginning of each half cycle of discharge; The on/off operation of the switch circuit is controlled by detecting the voltage between the connection end of the switch circuit and the negative terminal of the DC output end of the full-wave rectifier connected to the input end of the switch circuit using a constant voltage element. A high-pressure steam discharge lamp lighting circuit characterized in that it is configured to.