JPS59173994A - Power source for flash 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] The invention relates to a power supply device for a flash discharge lamp.

A flash discharge lamp is used, for example, as an exposure source or a heat source for fixing in a copying machine. As power supplies for lighting flash discharge lamps, power supplies using a single cage transformer, power supplies using a commercial transformer, etc. are conventionally known, but these power supplies are many times larger and larger. It has the disadvantage of being heavy. In particular, when using a flash discharge lamp as a heat source for fixing in a copying machine, the above-mentioned drawbacks are greatly exacerbated because copying machines have recently become much smaller and lighter.

For this reason, a flash discharge lamp power supply device using an impark having a semiconductor switching element has recently been developed, and this power supply device has the advantage of being small and small in size. .

FIG. 1 is an explanatory circuit diagram showing an example of the configuration of a power supply device for a flash discharge lamp. For this example? This is an inverter connected to a lVi DC power supply EK, and this inverter lid is connected to a transistor 1 which is a semiconductor switching element.
1 and 12 and a transformer 13. The collectors of transistors 11 and 12 are connected to one end and the other end of the primary coil of transformer 13, respectively, the emitters of transistors 11 and 12 are both connected to the negative side of DC power supply E, and the bases of transistors 11 and 12 are described later. It is connected to the drive circuit 5. The center tap of the transformer 13 is connected to the positive side of the DC power supply E.

2 is a bridge type rectifier circuit consisting of four diodes 21, 22, 23, and 24, and the input end of this rectifier circuit 2 is connected to the secondary filter of the transformer 13 in the inverter IKjd.

3 is a charging/discharging capacitor connected between the output terminals of the rectifier circuit 2, and when a pressure flash discharge lamp 6 is connected to both ends of this photodischarge capacitor 3, the flashlight discharge lamp is connected to the charging/discharging capacitor 3. 6 is supplied with the charge necessary for flash generation.

4 and 5 are a control circuit and a drive circuit,
The drive circuit 5 has its output side connected to the bases of the transistors 11 and 12 of the inverter 1, and alternately supplies rectangular waveform pulse currents to each of these bases to turn the transistors 11 and 12 on and off alternately. The control circuit 4 controls the drive circuit 52, detects the voltage across the charging/discharging capacitor 3, and compares this detected voltage with a preset voltage. A signal corresponding to the difference is supplied to the drive circuit 5, and the pulse width of the pulse current supplied from the drive circuit 5 to the bases of the p-transistors 11 and 12 is controlled. This is to control the voltage so that it does not exceed the set voltage required to generate a flash.

This is a trigger circuit for driving the trigger electrode 61i provided in the flash discharge lamp 6.

Depending on the power supply device with the above configuration, inverter 1? By turning the transistors 11 and 12 on and off alternately by the control circuit 4 and the drive circuit 5, the DC from the DC power supply E is once converted to AC, and then this AC is connected to the rectifier circuit at 2V? -, the DC current is converted back into direct current, and charges are accumulated in the charging/discharging capacitor 3 by this direct current. When the voltage across the charging/discharging capacitor 3 reaches the large Pg required to generate a flash, the control circuit 4 and drive circuit 5 control the pulse width of the pulse current supplied to the bases of the transistors 11 and 12. The voltage across the charging/discharging capacitor 30 is maintained at the set voltage by controlling the voltage to approximately zero. When the voltage across the charging/discharging capacitor 3 reaches the set voltage as described above, and a high voltage is applied to the trigger electrode 61 by the trigger circuit 7, dielectric breakdown occurs between the discharge electrodes of the flash discharge lamp 6. occurs, and at this instant, the charges accumulated in the charging/discharging capacitor 3 are supplied to the flash discharge lamp 6, producing a flash. This flash of light causes the charging/discharging
When the voltage across the capacitor 3 decreases, the control circuit 4
and drive circuit 5, transistors ll and 12
The pulse width of the pulse current supplied to each base is controlled to be large, and charge is again accumulated in the charging/discharging capacitor 3, and the flash is repeatedly generated in the same manner as described above. It will be done.

A flash of light is generated in the above manner, but when a flash of light occurs, the charge of the charging/discharging capacitor 3 is instantly released and the charge disappears, so the output side impedance of the inverter 1 becomes almost zero. After the flash disappears, charges are gradually accumulated in the charge/discharge capacitor 3 again, so the output impedance of the inverter 1 gradually increases (becomes), and when the voltage across the charge/discharge capacitor 3 reaches the set voltage, the inverter 1 The output impedance of the inverter l becomes almost infinite.As the flashes are generated repeatedly in a short period of time, the output impedance of the inverter l goes from zero to infinity. Since the transistors 11 and 1 change constantly and repeatedly,
In a state where the distortion of the collector current of 2 becomes large (as a result, the efficiency of the power supply device decreases, and the charge of the charging/discharging capacitor 3 is released, and the output 11f11invider/s of the converter becomes almost zero). As shown in Fig. 2, the collector currents of transistors 11 and 12 are slightly suppressed by the inductance of transformer 13 during the half cycle until the end, but at the end, transformer 13 saturates. Since the inductance becomes substantially zero, the current increases rapidly and exceeds the rated maximum peak current value, destroying the transistors 11 and 12.

The present invention has been developed based on the above-mentioned circumstances, and provides a power supply device for a flash discharge lamp which is highly efficient and prevents damage to the semiconductor switching element in the inverter. Its two purposes are as follows: an inverter having semiconductor switching elements, a waveform shaping circuit consisting of a coil and a capacitor connected to the output end of this inverter, and a subsequent stage of this waveform shaping circuit. It consists of a rectifier circuit connected to the rectifier circuit, and a charging/discharging capacitor connected to the output end of the rectifier circuit.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is an explanatory circuit diagram showing a second embodiment of the present invention,
Components that are the same as those shown in FIG. 1 are designated by the same reference numerals 7, and their explanations are omitted because they are the same. In this example, a waveform shaping circuit 8 comprising a coil 81 and a capacitor 82 is connected to the output end of the inverter 1, and a rectifier circuit 2 is connected to the downstream of the waveform shaping circuit 8. In the waveform shaping circuit 8, a coil 81 is connected between one end of the secondary coil of the transformer 13 and one input end of the rectifier circuit 2, and a capacitor 82 is connected between the other end of the secondary coil of the transformer 13 and one input end of the rectifier circuit 2. It is connected between the other input terminal of the circuit 2 and the other input terminal of the circuit 2.

According to the above embodiment, since eight waveform shaping circuits each consisting of a coil 81 and a capacitor 82 are provided between the inverter l and the U current circuit 2, these coils 81 and capacitor 82 are connected to the AC output from the inverter 1. Therefore, even when the charging/discharging capacitor 3 releases charge and becomes a short-circuit state, the output impedance of the inverter 1 does not become zero, but is caused by the coil 81 and the capacitor 82. A sound of a certain size? As a result, even if flashing occurs repeatedly, the change in the output impedance of the inverter 1 is suppressed to a small level, and as a result, the distortion of the collector currents of the transistors 11 and 12 becomes small, and the waveform of the collector current changes. The efficiency of the power supply device can be increased by flattening the surface. As shown in FIG. 4, even if the charging/discharging capacitor 3 is short-circuited, the collector currents of the transistors 11 and 12 change at the end of the half cycle. Even if the transformer I3 is saturated and its inductance becomes zero, the impedance of the coil 81 and capacitor 82 of the waveform shaping circuit 8 can suppress the sudden rise in collector current, so the maximum rated peak collector current value (, as a result, transistor 1
1 and 12 can be prevented.

Although one embodiment of the present invention has been described above, as shown in FIG.
Between one end of the next coil and one input end of the rectifier circuit 2,
The coil 81 and the capacitor 82 may be connected in series. In this case as well, the same effects as those of the previously described embodiments can be obtained.

The configurations of the inverter 1 and the rectifier circuit 2 are not limited to the above-mentioned example, and other known configurations may be adopted.

For example, when a voltage doubler type rectifier circuit is used as the rectifier circuit 2, the capacitor included in the voltage doubler type rectifier circuit can be shared as the capacitor of the waveform shaping circuit 8, so the capacitor 81'Y is omitted. Good too.

As described above, the present invention includes an inverter having a semiconductor switching edge, a waveform shaping circuit including a coil and a capacitor connected to the output end of the inverter,
This power supply device for flash discharge lamps is characterized by comprising a rectifier circuit connected to the latter stage of this waveform shaping circuit, and a charging/discharging capacitor connected to the output end of this rectifier circuit. In addition, damage to the semiconductor switching element in the inverter can be prevented.

[Brief explanation of drawings]

Figure 1 shows an example of a conventional flash discharge lamp power supply device.
2 is an explanatory diagram showing the waveform of the collector current of the transistor delivered to the device shown in FIG. 1, and FIG. 3 is an explanatory circuit diagram showing an example of the power supply device for a flash discharge lamp of the present invention. 4 is an explanatory diagram showing the waveform of the collector current of the transistor in the device shown in FIG. 3, and FIG. 5 is an example of the waveform shaping circuit 110. FIG. 1... Inverter E... DC power supply 11.12.
Transistor 13, transformer 2... rectifier circuit 21.22,
23, 24...Diode 3...Charging/discharging capacitor/suction 4...Conotro-1 circuit 5...Drive circuit 6...
Flash discharge lamp 61, trigger electrode 7, trigger circuit 8, waveform shaping circuit 8, coil 82
... Contencer Procedure Sleeve Book (Method) 11I'I July 1958 IJ 1] Commissioner of the Japan Patent Office Kazuo Wakasugi 1 Indication of Case 1982 Patent 1f'j' No. 47036
';2 Name of the invention N source device for flash discharge lamp 3
Relationship with the case of the person making the amendment Patent applicant 4, agent 1) Engraving of the specification (no change in content) 2) Engraving of drawings (no change in content) 3) Supplementing separate power of attorney. Procedural amendment (spontaneous) September 16, 1932 Director-General of the Patent Office Kazuo Wakasugi 1, Indication of the case 1982 Patent application No. 47036 q2,
Name of the invention: Power supply equipment for flash discharge lamps Name: Ushio Inc. 5 Date of amendment order I corrected myself by saying, "σ) The impedance further decreased."

Claims (1)

[Claims] 1) An inverter comprising a semiconductor switching element, a waveform shaping circuit comprising a coil and a capacitor connected to the output end of this inverter, a rectifier circuit connected after this waveform shaping circuit, and A power supply device for a flash discharge lamp, comprising a charging/discharging capacitor connected to an output end of a rectifier circuit.