JPH0799777A - High-voltage power circuit - Google Patents

Abstract

PURPOSE:To obtain a high-voltage power circuit which can control a minute current as well and is of high precision and low cost by a construction wherein a block controlling and outputting a high voltage and the minute current is mounted as a two-storied sub-board on a main board of a high-voltage power source part. CONSTITUTION:A boosting-rectifying circuit part comprising capacitors and diodes for boosting, load resistors for discharge, resistors for output, etc., is mounted on a sub-board 5, and the sub-board is disposed, with the component side down, above a main board 6 of a high-voltage power source part with conductive support members J1, J2, J3 and J4 interposed. By using printed circuit boards being relatively inexpensive and having low insulation resistances, according to this constitution, it is made possible to control a high-voltage output precisely by a minute current and, besides, to make a device small in size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage power supply circuit used in an electrostatic photography process of an image recording device such as a copying machine or a laser printer.

[0002]

2. Description of the Related Art Conventionally, a high voltage power supply used in this type of electrostatographic process requires a high voltage of about 10 KV to generate corona discharge, and a flyback transformer or the like is used to generate it. Then, the high-voltage output was directly applied to the high-voltage load from the terminal on the insulating case of the flyback transformer via the high-voltage wire.

[0003]

In recent years, the image recording apparatus using the electrostatographic process has been reduced in size and cost, as represented by a laser printer, and has a relatively low voltage (1 to 5 KV). The contact charging process, which requires only the application of electricity, is becoming mainstream.

However, these contact charging processes require a low current control of several μA, and the insulation resistance value of the printed circuit board, which is an insulator, cannot be neglected in the micro current control, and the insulation distance is increased. There is a problem that a printed circuit board material having a high insulation resistance must be used.

The present invention has been made in view of the above problems, and controls a high voltage output of this kind with a small current with high precision by using a relatively inexpensive printed circuit board material having a low insulation resistance value. It is also an object of the present invention to provide a means capable of increasing the insulation resistance at the output end of these high voltage / micro currents in a relatively small space.

[0006]

Therefore, in the present invention, a block for controlling and outputting a high voltage and a minute current is mounted as a two-story sub-board on the high-voltage power supply main board. It is intended to achieve the above object.

[0007]

With the above-described structure of the present invention, for example, a low-cost inverter transformer is used to boost the voltage to 5K
When outputting a high voltage of about V, the booster circuit unit is composed of a relatively low-cost printed circuit board such as paper phenol.
By constructing on a floor sub-board, it is possible to realize a high-accuracy, low-cost high-voltage power supply circuit capable of controlling even a minute current of several μA.

[0008]

EXAMPLES The present invention will be described below based on examples.
FIG. 1 shows an output partial view of a first embodiment of a high-voltage power supply circuit of this type according to the present invention, and FIG. 2 shows a mounting diagram of a two-story sub-board of this embodiment. In FIG. 1, 1 is an output control unit, 2 and 3 are voltage control units, and 4 is an equivalent high-voltage load in the electrostatographic process. Q1, Q2, Q3 and Q4 are transistors for controlling and driving the transformers T1 and T2, and C1, C2, C3, C4, C5 and D1,
D2, D3, D4 and D5 are boosting capacitors and diodes, respectively. R1 and R2 are load resistors for discharging, and R3 is an output resistor.

R7 is a detection resistor for detecting the current flowing through the GND via the high voltage load 4. J1, J2
Reference numerals J3 and J4 denote respective support members made of a conductive material for electrically connecting the booster circuit section formed on the two-story sub-board 5 shown in FIG. 2 and the high-voltage power supply main board 6. . Descriptions of other constituent elements not directly related to the description of the embodiments of the present invention will be omitted.

The transformers T1 and T2 are boosted, and a voltage is applied to the sub-board 5 which is a boosting rectifier circuit section through the respective supporting members J1, J2, J3, J4, and the output resistance R
A high voltage is applied to the high voltage load 4 via 3. The current flowing through the high-voltage load is connected to the detection resistor R7 via the GND line.
Flow into. Based on the voltage generated in the detection resistor R7, the voltage control units 2 and 3 control the voltage applied to the primary side of the transformers T1 and T2 to control the current flowing in the high voltage load.

FIG. 2 shows a mounting schematic diagram of the sub-board 5 which is a boost rectification circuit section. FIG. 2 (a) is a perspective view of the sub-board,
FIG. 6B is a mounting view in which it is reversed. Each component mounted on the sub-board 5 is not individually labeled, but the capacitors C1 and C in FIG.
2, C3, C4, C5; diodes D1, D2, D3
D4, D5: Respective elements corresponding to the resistors R1, R2, R3, etc. As shown in FIG. 7B, the sub-board 5 has the component surface facing down to the main board 6 of the high-voltage power supply unit via the supporting members J1, J2, J3, and J4. It is implemented.

Usually, a relatively inexpensive printed circuit board such as paper phenol has an insulation resistance value of about 10 ¹⁰ Ω under high temperature and high humidity. As is well known, this insulation resistance value becomes smaller as the area where each component contacts the substrate is larger and the distance between the component electrode portions is shorter. Since the detection unit of the current flowing through the high-voltage load has the GND pattern, when the boost rectification circuit unit that generates a high voltage is present on the high-voltage power supply main board 6, a large number of vertical and horizontal lines are provided on the high-voltage power supply main board 6. Since the GND pattern crawls around, it may cause erroneous detection. Therefore, it is desirable that the high-voltage generating unit reduces the contact area on the main substrate 6 where the GND pattern is present as much as possible. In particular, the greater the resistance value of the high voltage load 4, the lower the current control accuracy.

(Second Embodiment) FIG. 3 is a mounting view showing a second embodiment of the present invention, and the circuit configuration is the same as that in FIG.

A two-story sub-board 5 having a step-up rectification circuit section is formed on the main board 6 in the same manner as in FIG. 2B.
Mounted with the soldering side up. P1 is an electrode terminal soldered on the pattern. P1 is equivalent to the high-voltage output terminal via the output resistor R3 in FIG. 1, and directly applies a voltage to the high-voltage load 4 via the terminal 7 having a Koly spring shape. Since the high-voltage output portion is a solder-applied pattern and does not exist on the main board 6, an inexpensive output portion with a small leakage current can be formed.

(Third Embodiment) FIG. 4 is a mounting view of a third embodiment in which the second embodiment is made more practical,
(A) is an exploded perspective view, (b) is a mounting view. 5 is a two-story sub-board, 6 is a main board, 8 is an insulating case, 9
Are holding columns protruding from the insulating case 8. FIG. 6B is a diagram in which the high-voltage power supply unit is mounted on the insulating case 8. The main board 6 is provided with a cutout hole 10 as shown in FIG. In this state, the holding column 9 comes out of the cutout hole 10 and comes into contact with the sub-board 5. The sub-board 5 is composed of the support members J1, J2, J3, J4.
It is held in a two-story style for electrical continuity,
(B) As shown in the figure, since it is pushed by the mechanical stress f from the terminal 7 (not shown) (see FIG. 3), the holding column 9 acts to receive the force. Further, since the holding column 9 can minimize the contact with the main substrate 6 and is also an insulator, it has no influence on the electrical characteristics, particularly the leakage current.

[0016]

As described above, according to the present invention,
In this type of high-voltage power supply, a block for outputting a minute current at high voltage is constructed on a two-story sub-board, and a conductive support member is connected to the high-voltage power supply main board and the two-story sub-board. A high voltage power supply circuit including this supporting member is used, and a high voltage output terminal is provided on a two-story sub-board, so that a relatively inexpensive printed circuit board with low insulation resistance is used. It became possible to control the high voltage output with a small current with high precision. Further, it is possible to easily increase the insulation resistance at the output end of high voltage and minute current in a relatively small space, which can contribute to downsizing of the device.

[Brief description of drawings]

FIG. 1 is an output partial view of a first embodiment of a high voltage power supply circuit.

FIG. 2 is a mounting diagram of a two-story sub-board according to the first embodiment.

FIG. 3 is a mounting diagram of the second embodiment.

FIG. 4 is a mounting diagram of the third embodiment.

[Explanation of symbols]

 1 Output control part 2, 3 Voltage control part 4 High voltage load 5 Two-story sub board 6 High voltage power supply main board 8 Insulation case 9 Holding column J1, J2, J3, J4 Support member P1 Electrode terminal f Mechanical stress

Claims (5)

[Claims] 1. A high-voltage power supply used in an electrostatographic process, wherein a block for controlling and outputting a high voltage and a minute current is constructed as a two-story sub-board on the main board of the high-voltage power supply section. Power supply circuit. 2. The high-voltage power supply circuit according to claim 1, wherein a high-voltage output terminal for applying to the electrostatographic process section is provided on the two-story sub-board. 3. The high-voltage power supply circuit according to claim 1, wherein the high-voltage output terminals on the two-story sub-board are solder-coated on a printed pattern. 4. The supporting member for holding the two-story sub-board on the main board is an electrically conductive member that electrically connects the main board and the sub-board. 1. The high voltage power supply circuit according to 1. 5. An insulating case for holding the main board of the high-voltage power supply is provided, and holding support is provided to the insulating case for reducing mechanical stress applied on the two-story sub board. The high voltage power supply circuit according to claim 1.