JPS59114796A - Flash discharger - 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 the Invention The present invention relates to a flash discharge device in which charge is stored in a capacitor and discharged in a flash discharge tube through a choke coil.

Configuration of the conventional example and its problems In the conventional flash discharge device, as shown in Fig. 1, the AC power source 1
．． Rectifier circuit 2. Smoothing capacitor 3. DC-AC converter 4. Choke coil s, N double voltage rectifier circuit 6. Capacitor 7 for flash discharge, voltage detection circuit 8. Charging completion reference voltage circuit9. Voltage comparator 10° trigger pulse generation circuit 11.
Flash discharge tube 12. Trigger electrode 13. Choke coil 14
It consists of The operation of the conventional example will be explained below.

The output of the AC power supply 1 is rectified by a rectifier circuit 2, and further smoothed by a smoothing capacitor 3 to become DC.

When DC power is applied to the D C-A C converter 4, it is converted to high-frequency AC and boosted by a switching operation, and is then passed through a choke coil 5 to an N doubler voltage rectifier circuit 6.
The voltage is boosted and rectified by the capacitor 7, and the charge is stored in the capacitor 7.

The operation of the N-double voltage rectifier circuit 6 will be explained. 1 when b is on the + side
．． The capacitor 16 is connected to DC-AC by the diode 19.
It is charged to the amplitude tcE of the output voltage of the converter. Next, when a becomes the ■ side, the voltage E of the capacitor 15 and ab
The sum 2E of the alternating current amplitudes E between them is charged to the capacitor 16 through the diode 2o. When b becomes side ■ again, diode 19 becomes forward direction, so f and q become the same potential,
Diode 20 becomes reverse biased. Therefore, the voltage 2E of the capacitor 16 charges the capacitor 17 to 2E through the diode 21. Then, when a becomes the ■ side again, the diode 2o becomes the forward direction, q and h are the potentials of 2E due to the capacitor 16, and i is the potential of the capacitor 16.
17, the potential becomes 4E. Therefore, the diode 21 becomes reverse biased and the diode 22 becomes forward biased. Therefore, there is a potential difference of 2E between ih and the capacitor 18 is charged to 2E due to the operation of 0 or more, and the flash discharge capacitor 7 is charged to four times the voltage. According to Satoshi's explanation, there are 4 diodes and 4 capacitors.
However, if N diodes and N capacitors are used, an N-double voltage rectifier circuit can be constructed.

During charging to accumulate charges, the voltage of the flash discharge capacitor 7 is detected by the voltage detection circuit 8. When the voltage of capacitor 7 reaches the set charging completion voltage, voltage detection circuit 8
The output voltage of the charging completion reference voltage circuit 9 becomes higher than that of the charging completion reference voltage circuit 9. At this time, the voltage comparator 10 operates and turns off the output signal.

When the output signal of the voltage comparator 10 turns OFF, the DC
- The AC converter 4 stops its switching operation. When the switching operation stops, the capacitor 7 is not charged, so the voltage of the capacitor 7 becomes the set charging completion voltage.

Next, when a trigger pulse generation command signal is applied to the trigger pulse generation circuit 11, the trigger electrode 1 of the flash discharge tube 12
Issue a trigger pulse at 3. When a trigger pulse is applied, the charge accumulated in the capacitor 7 is transferred to the choke coil 14.
and is discharged through the flash discharge tube 12.

Due to the discharge, the voltage of the flash discharge capacitor 7 decreases and the output voltage of the voltage detection circuit 8 becomes lower than the output voltage of the charging completion reference voltage circuit 9, so the output signal of the voltage comparator 10 turns ON. - The AC converter 4 can perform flash discharge intermittently by repeatedly performing 0 or more operations for starting a switching operation.

However, in the above-mentioned flash discharge device, when the electric charge accumulated in the capacitor 7 is discharged in the flash discharge tube 12 through the choke coil 14, a back electromotive force is generated in the choke coil 14, and the current ir flows in the opposite direction to that during discharge. flows. This electric charge is again stored in the capacitor 7, and a damped oscillating voltage is generated between c and d due to the coil and capacitor which are discharging. The O choke coil 14, which destroys the element when the instantaneous current due to the damped oscillating voltage exceeds the forward maximum rated current of the diodes 19, 20, 21.22 of the N doubler voltage rectifier circuit 6, can be replaced with a resistor. , the loss is greater than when using a choke coil. The choke coil 14 also has the effect of suppressing the steep rise of the discharge current, and there is no element that can replace the cheek coil.

Purpose of the Invention The present invention prevents instantaneous current exceeding the forward maximum rated current of an N-fold rectifier diode from flowing due to oscillating voltage generated by the choke coil and capacitor of a flash discharge device, and also prevents damage to semiconductor elements. The present invention provides a flash discharge device.

Structure of the Invention In order to achieve the above object, the present invention is characterized in that a resistor is installed in series with a rectifying diode in an N-times voltage rectifying circuit in a charging circuit for charging a capacitor.

This resistor reduces the instantaneous forward current flowing through the diode of the N-times voltage rectifier circuit in the charging circuit, thereby preventing damage to the device.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention is shown in FIG. 2, and its structure and operation will be described below. Components that are the same as those of the conventional example are designated with the same symbol, and their explanation will be omitted.

By applying a trigger pulse to the trigger electrode 13 of the flash discharge tube 12, the charge accumulated in the capacitor 7 passes through the choke coil 14 and is discharged in the flash discharge tube 12.

At this time, a back electromotive force is generated in the choke coil 14, and a current ir flows in the opposite direction to that during discharge. This charge is again stored in the capacitor 7, and a damped oscillating voltage is generated between the coil and the capacitor C9d, which discharges slowly. here,
When C is on the O side and d is on the ■ side, the current flows not only in the direction of the choke coil 14 but also into the N double voltage rectifier circuit 6.

This instantaneous current flows through the diode 19°2 of the N doubler voltage rectifier circuit 6.
When the forward maximum rated current of 0.21, 22 is exceeded, the diodes 19, 20, 21, 22 are destroyed. At this time, the element protection resistor 23A is connected to e, f in the N-fold voltage rectifier circuit 6.
By inserting the rectifier diode 19, 20 in the dark
, 21, 22 can be reduced.

Due to the discharge, the voltage of the flash discharge capacitor 7 decreases,
Since the output voltage of the voltage detection circuit 8 becomes lower than the output voltage of the charge completion reference voltage circuit 9, the output signal of the voltage comparator 10 is turned ON. Therefore, the DC-AC converter 4 starts a switching operation. By repeating the above operations, flash discharge can be performed intermittently.

One embodiment of the present invention has been described above, and the resistor c' shown in Fig. 2 is used to protect the rectifying diode.
, d, current always flows through the protective resistor 231 while the DC-to-C converter 4 performs switching operation and charges the capacitor T, resulting in power loss due to the resistor. . Therefore, '+' shown in Figure 3
By installing a protective resistor 23B in series with the diode 19, 20, 21 between q, g, h, or i, respectively, it has the effect of protecting the rectifying diode, and the protective resistor 23B can reduce power loss caused by

Furthermore, considering the operating principle of the N-double voltage rectifier circuit 6, a protective resistor 23C is connected in series with the diode 22 between i and 1 in FIG.
By providing this, it has the effect of protecting the rectifying diode, and the power loss due to the protective resistor can be minimized.

As described in detail, the present invention provides the following effects by installing a resistor in series with a rectifying diode in an N-times voltage rectifier circuit.

Choke coils are used to control the discharge current of flash discharge lamps.
Moreover, the instantaneous current of the oscillating voltage generated by the choke coil and the capacitor can be prevented from exceeding the forward maximum rated current of the N-fold rectifier diode, and damage to the semiconductor element can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a conventional circuit diagram, and FIGS. 2, 3, and 4 are circuit diagrams of embodiments of the present invention. 2... Rectifier circuit, 4... C connector to DC-, 6... Choke coil, 6...
...N double voltage rectifier circuit, 8...Voltage detection circuit,
9...Reference voltage circuit, 10...Voltage comparator, 11...Trigger pulse generation circuit, 12
...Flash discharge tube.

Claims (1)

[Claims] A flash discharge tube, a trigger pulse generation circuit for causing the flash discharge tube to emit light, a charging capacitor, a DC power supply,
A flash discharge device having a charging circuit for charging a capacitor with the output of a DC power source, and a choke coil between the flash discharge tube and the charging capacitor, wherein the charging circuit converts the DC output into high-frequency AC. -DC converter, choke coil, and choke coil-
A flash discharge characterized by comprising an N double voltage rectifier circuit connected to a high frequency output end of an AC converter, and further including a protective resistor in series with a rectifying diode in the N double voltage rectifier circuit. Device.