JPS6155898A - Power source for discharge lamp - 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 Industrial Application) The present invention relates to a power source for a discharge lamp, and particularly to a fixed @ mushroom mounting or exposure device using flash light such as a dry copying mark, a printer, and a facsimile. Suitable for use with discharge lamps! il
! It is related to.

(Prior Art) A conventional power source for a discharge lamp of this type will be explained with reference to FIG. now,
Changeover switches 4a, 4b, etc. for relays, etc.

4n are connected to the contact side, capacitors 5a, 5b, 5c, . . . , 5n are connected in parallel via diodes 5a, 5b, 5c, -, 5n, respectively. At this time, when the power switch 1 is turned on, the alternating current output from the power supply 2 is rectified by the rectifier circuit 3, and the capacitor 5a is rectified.

5b, 5c, ..., 5n are charged.

Next, capacitors 5a, 5b, 5c, -, 5
When discharging the voltage charged in n and causing the discharge lamp 7 to emit light, the changeover switches 4a, 4b, . . .

4n is switched to the contact a side. The changeover switch 4a,
4b, ..., 4n are switched to the contact a side, the capacitors 5a, 5b, 5c, ..., 5n are connected in series, and the total voltage is applied between the two electrodes of the discharge lamp 7. be done. As a result, the discharge lamp 7 starts discharging, and the discharge lamp 7 emits a flash of light.

When the capacitors 5a, 5b, 5c, -, 5n are discharged, the changeover switches 4a, 4b, . . . , 4
n is again switched to the b-side contact. As a result, the capacitors 5a, 5b, 5c, . . . , 5n are charged again.

By repeating the above operations, the discharge lamp 7 can be caused to emit light repeatedly.

In dry copying machines, printers, facsimile machines, etc., this discharge lamp is used as a fixing device or an exposure device.

(Problems to be Solved by the Invention) The above-described conventional techniques had the following problems.

(1) Capacitors 5a, 5b, 5c during charging
,-.

5n are connected in parallel, the capacitance (combined capacitance) of the capacitor increases, and when power switch 1 is turned on,
Excessive input rush current flows in the power supply circuit.

For example, as shown in FIG. 4, if the AC voltage output from the power supply 2 has a waveform of V1 shown in the figure, and if the power switch 1 is turned on at time 1=0, then the AC voltage An excessive input rush current ■1 flows during 1/4 period of V1.

When the input rush current 11 increases in this way, there is a problem in that the diodes 6a, 6b, . . . , 5n and the lead wires generate heat and are destroyed or disconnected.

The present invention has been made to solve the above-mentioned problems.

(Means and Effects for Solving the Problems) In order to solve the above problems, the present invention provides a plurality of discharge lamps connected in series to each other in a circuit from a power source to a discharge lamp via a rectifier. A switch or a switching element is connected to each discharging capacitor so that the discharging capacitors are charged in parallel one by one when charging and are connected in series when discharging. death,
The present invention is characterized in that the switch or switching element is controlled so that each discharging capacitor is charged at different times during charging.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention. Also, the second
The figure shows a time chart of control voltages applied to the gates of each current control element during charging and discharging.

In the circuit shown in FIG. 1, a power source 2 is connected to a rectifier circuit 3 via a choke coil 12. The output end of the rectifier circuit 3 is connected to the anode of the diode 10c, and the cathode of the diode 10c is connected to the diode 1.
The anode of the diode 10b is connected to the anode of the diode 10a, and the cathode of the diode 10a is connected to the capacitor 5a and the discharge lamp 7, respectively. Capacitors 5a, 5b, 5c, and 5d are connected in series, a thyristor 11a is connected between the connection point of capacitors 5a and 5b and the cathode of diode 10b, and a thyristor 11a is connected between the connection point of capacitors 5b and 50 and the cathode of diode 1.
A thyristor 11b is connected between the cathode of 0c,
A thyristor 11c is connected between the connection point of capacitors 5C and 5d and the anode of diode 10c.

The connection point between the capacitors 5a and 5b is roughly connected to the anode of a thyristor 11d, and thyristors 118 and 11'' are connected in series with the thyristor 11d.
A diode 10d is connected between the anode of the capacitor 5C and the anode of the thyristor 11f, and a diode 10e is connected between the connection point of the capacitors 5C and 5d and the anode of the thyristor 11f.

One side terminal of the discharge lamp 7 and the anode of the diode 10f are connected to one side terminal of the capacitor 5d.

A diode 10f and a cathode of a thyristor 11'' are connected to one side terminal of the rectifier circuit 3. A bias resistor is also connected as shown.

Next, the operation of one embodiment of the present invention having the above-described configuration will be explained with reference to the time chart of FIG.

It is now assumed that the power supply 2 is outputting an alternating current with a waveform as shown in FIG. 2(a).

When charging the capacitors 5a, 5b, 5c and 5d, first the thyristor 1 is charged as shown in FIG.
1d, 11e and 11f are turned on. As a result, current mainly flows through the following paths.

(+) end of rectifier circuit 3 → diode 10c → diode 10b → diode 10a → capacitor 5a → thyristor 11d → thyristor 11e → thyristor 11f → (-) end of rectifier circuit 3. Therefore, capacitor 5a is charged.

In the next half cycle, thyristor 11d is turned off,
Thyristors 11a, 11e and 1'1f are turned on. As a result, current mainly flows through the following path.

The (+) end of the rectifier circuit 3 → diode 10c → diode 10b → thyristor 11a → capacitor 5b → diode 10 (1 → thyristor 11e → thyristor 11) → (-) end of the rectifier circuit 3. Therefore, the capacitor 5b is charged. .

Furthermore, in the next half cycle, thyristors 11b and 11
Only f is turned on. Therefore, current mainly flows through the following path.

(+) end of rectifier circuit 3→diode 10c→thyristor 11b→capacitor 5C→diode 10e→thyristor 11→(−) end of rectifier circuit 3. As a result, capacitor 5C is charged.

Furthermore, in the next half cycle, only Cyrisk 11c is turned on. Therefore, current mainly flows through the following paths.

The (+) end of the rectifier circuit 3 → the thyristor 11c → the capacitor 5d → the diode 10f → the (-) end of the rectifier circuit 3. As a result, the capacitor 5d is charged.

By the above operation, capacitors 5a and 5b.

Charging of 5C and 5d is completed.

According to this embodiment, capacitors 5a and 5b.

5C and 5d are charged one each, and one
Since the individual capacitance is 1/4 of the combined capacitance of the conventional example, the input rush current can be reduced to 1/4 of that of the conventional example.

Next, when the capacitors 5a, 5b, 5c and 5d are discharged to emit a flash from the discharge lamp 7, the thyristor 1
Turn off all 1a to 11. Then, the next discharge circuit is formed, and when the voltage applied between both terminals of the discharge lamp 7 exceeds the discharge starting voltage, discharge starts and the discharge lamp 7 emits a flash of light.

Capacitor 5a → Discharge Tx *T 7 → Capacitor 5d →
Capacitor 5C → Capacitor 5d → Capacitor a In the above embodiment, the number of capacitors 5a is four, but the present invention is not limited to this, and it is of course possible to perform the same operation even if the number is changed. be.

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects are achieved.

(1) Since input rush current can be reduced, the amount of heat generated in circuit lead wires, semiconductor elements, etc. is small, and a highly reliable and safe discharge lamp lamp can be provided.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a time chart showing on/off of the thyristor in FIG. 1 and corresponding current waveforms flowing through each capacitor 5a, and FIG.
The figure is a circuit diagram of a conventional circuit, and FIG. 4 is a time chart showing the waveform of the current flowing through the circuit of FIG. 3 during charging. 2... Power supply, 3... Rectifier circuit, 5a to 5d... Capacitor, 7... Discharge lamp, 11a to 11 "... Thyristor representative patent attorney Michito Hiraki and 1 other person 23 Figure 24 t

Claims (1)

[Claims] (1) In the circuit from the power supply to the discharge lamp via the rectifier,
A plurality of discharge capacitors connected in series are arranged in parallel with the discharge lamp, and each of the discharge capacitors is connected in parallel so that the discharge capacitors are charged one by one in parallel when charging and are connected in series when discharging. A power source for a discharge lamp, characterized in that a switch or a switching element is connected to a discharge capacitor, and the switch or switching element is controlled so that each discharge capacitor is charged at different times during charging.