JPS63217139A - Igniter circuit - Google Patents

Abstract

PURPOSE:To prevent the shortage of the igniting force by providing a light emission diode for emitting light by a current flowing to diodes, a photodiode for receiving the light, and a second capacitor connected in parallel between the photodiode and the gate cathode of a thyristor. CONSTITUTION:In a cycle in which an AC power source 1 applies a positive voltage to a point (a) and a cycle in which the AC power source applies a negative voltage to a point (b), a capacitor 4 is charged with a voltage having a polarity reverse to the initial polarity, and a current flows through a closed circuit formed by capacitor 4, transformer 5, diode 10 and capacitor 4, in this sequence. By this current a voltage capable of sufficiently emitting light a light emission diode 9 connected in parallel to the diode 10 is generated. Accord ingly, a voltage is generated in a photodiode 8 by the light emission of the diode 9, and a charge is stored in a capacitor 13. When a power supply to the diode 10 is completed, the capacitor 13 discharges the charge, and a current flows to the gate of a thyristor 3. Then, the thyristor 3 is turned on again and a damping oscillation occurs and a discharge effect is produced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an igniter circuit.

[Conventional technology]

A conventional igniter circuit shown in FIG. 3 is known. In the figure, 1 is an AC power supply, 2 is a diode,
3 is a thyristor, 4 is a capacitor, 5 is a transformer, 6 is a resistor, 7 is a diode, and 20 is an ignition part connected to the double-digit side of the transformer 5. Next, the operation shown in FIG. 3 will be explained. When AC power supply 1 gives a positive voltage to point a, AC power supply 1 → Capacitor 4 → Transformer 5 → Diode 7 →
A current flows through the closed circuit of the AC power source 1, and charge is accumulated in the capacitor 4. Next, when applying a positive voltage to the voltage of the AC power supply 1, the thyristor 3 is turned on by passing a trigger current to the gate of the thyristor 3, and the capacitor 4
A current flows through the closed circuit of - + thyristor 3 -> transformer 5 - capacitor 4, the charge accumulated in the capacitor 4 is discharged, and the capacitor 4 is further charged with a voltage of opposite polarity to the initial voltage. Next, a current flows through the closed circuit of capacitor 4 -> transformer 5 -> diode 2 -> capacitor 4, and charge of the same polarity as the initial one is stored in capacitor 4 again.

[Problem that the invention seeks to solve]

In the conventional igniter circuit described above, if the turn-off time of the thyristor 3 is short, after the charge of the same polarity as the initial one is accumulated in the capacitor 4 again, there is no trigger pulse for the thyristor 3, so the thyristor 3 does not turn on and continues to vibrate. Since this does not occur, the energy induced on the secondary side of the lance 5 is small, resulting in a disadvantage that the ignition power is insufficient.

Regarding the above-mentioned conventional igniter circuit, the present invention generates a voltage using a photocoupler to turn on the thyristor again even when a thyristor with a short turn-off time is used.
Causes damped vibration to prevent insufficient ignition power.

[Means for solving problems]

The igniter circuit of the present invention provides a trigger pulse to the thyristor when the thyristor is reverse biased by an AC voltage applied to a series connection of a first capacitor and a transformer and a parallel connection of a diode and a thyristor in mutually opposite directions. The thyristor is configured to include a light emitting diode that emits light by a current flowing through the diode, a photodiode that receives light from the light emitting diode, and a second capacitor connected in parallel between the photodiode and the gate cathode of the thyristor. Ru.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention, in which 1 is an AC power supply, 2 is a diode, 3 is a thyristor, 4 is a capacitor, 5 is a transformer, 6 is a resistor, 7 is a diode, and 8 is a photodiode. , 9 is a light emitting diode, 10 is a diode, 11 is a resistor, and 20 is an ignition unit.

When AC power supply 1 gives a positive voltage to point a, AC power supply 1
- Current flows through the closed circuit of capacitor 4 → transformer 5 → diode 7 → AC power supply 1, and charge is accumulated in capacitor 4. Next, during a cycle in which the AC power supply 1 applies a positive voltage to the thyristor 3, when a trigger current flows to the gate of the thyristor 3, the thyristor 3 is turned on and the charge accumulated in the capacitor 4 is discharged, and the capacitor 4 → the thyristor Current flows through the closed circuit of 3 → transformer 5 → capacitor 4.

Further, the capacitor 4 is charged with a voltage of opposite polarity to that at the beginning, and current flows through the closed circuit of the capacitor 4 → l/lance 5 → diode 10 → capacitor 4. The current rating of the diode 10 for the current flowing in this closed circuit is:
It is usually a rated value of 1/10 to 1150. -For example,
If the peak value of the current flowing in Fig. 1 is 25 A, an IA rated diode is selected, and the forward current IP is determined from the I, -V, and characteristics of this IA rated diode shown in Fig. 4.
= 25 A, the forward voltage V is approximately 3 V, which is a voltage that allows the light emitting diode 9 connected in parallel to the diode 10 to emit sufficient light.

Therefore, due to the light emission from the light emitting diode 9, the photodiode 8
A voltage is generated and charge is accumulated in the capacitor 13.

When the diode 10 is no longer energized, the charge accumulated in the capacitor 13 is discharged, current flows to the gate of the thyristor 3, the thyristor 3 is turned on again, and damped oscillation occurs.
The energy induced in the secondary side of the transformer 5 causes a discharge effect.

The above operations are repeated until the damped oscillation current decreases, the forward voltage V of the diode 10 decreases, and the light emitting diode 9 stops emitting light.

FIG. 2 shows another embodiment of the invention. The operation is the same as the embodiment shown in FIG. 1, except that a light emitting diode 15 and a resistor 17 are connected in series and a diode 16 is connected to cause damped vibration.
was installed between transformer 5 and point C. A resistor 14 was provided to prevent the thyristor 3 from being turned on by the current flowing through the light emitting diode when a positive voltage is applied to point a. In addition, a trigger current flows through the thyristor 3 during a cycle in which a positive voltage is applied to the switch, the thyristor 3 turns on, and the charge accumulated in the capacitor 4 is discharged, and the capacitor 4 - thyristor 3→
Points C and 1- are connected so that current flows through the closed circuit of transformer 5-.
Connect the resistor 17 between the lance 5.

〔Effect of the invention〕

As explained above, in the present invention, by connecting a photocoupler in which a light emitting diode and a photodiode are paired, the cyrisk is turned on again in the cycle after the trigger pulse, causing damped oscillation, and increasing the ignition power. There is an effect that can be done.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is a circuit diagram of another embodiment of the present invention, FIG. 3 is a circuit diagram of a conventional igniter circuit, and FIG. 4 is shown in FIG. It is an I, -VF characteristic of an IA rated diode used as an example in an example. 1...AC power supply, 2,7,10,16.18...diode, 3...Sirisk, 4,13...capacitor, 5...transformer, 6,11,12,14.17
...Resistance, 8...Po1~Diode, 9.15...
・Light-emitting device Figure 4

Claims (1)

[Claims] In an igniter circuit in which an AC voltage applied to a series connection of a first capacitor and a transformer and a parallel connection of a diode and a thyristor in mutually opposite directions provides a trigger pulse to the thyristor when the thyristor is reverse biased, the current flowing through the diode An igniter circuit comprising: a light emitting diode that emits light; a photodiode that receives light from the light emitting diode; and a second capacitor connected in parallel between the photodiode and the gate cathode of the thyristor.