JPS6097375A - High voltage power supply device of electronic copying machine - Google Patents

Abstract

PURPOSE:To detect and set a high-voltage output voltage to a corona discharger for electrostatic charge and transfer with one circuit of a high voltage power source by switching two output detecting circuits provided in one high voltage power source in accordance with electrostatic charge and transfer. CONSTITUTION:One circuit of a high voltage generating part in a high voltage power supply device is provided with output detecting parts which detect and set two output voltages. These two output detecting parts are switched and used through a mode switching part in accordance with the electrostatic charge mode and the transfer mode, and a high voltage which can be set independently in accordance with electrostatic charge and transfer is supplied to a corona discharger 4 for electrostatic charge and transfer for a photosensitive drum of one copy cycle per two rotations.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a high voltage power supply for an electronic copying machine.

[Prior art]

Conventionally, as a high-voltage power supply for a corona discharger of an electronic copying machine with a photosensitive drum 2 revolutions 1 copy cycle system, the power source shown in Fig. 1 or 8
There was something like the one shown in the figure. The method shown in FIG. 1 has two power supply circuits, whose output parts are connected in common, and each is turned on during charging and transfer, and operates as shown in FIG. 2.

This method is the same as having two high-voltage power supplies for one corona discharger, and it is necessary to prevent the two circuits from interfering with each other, so it is large, heavy, and expensive. This has hindered efforts to make copying machines smaller, lighter, and lower in cost. The method shown in FIG. 8 uses one power supply circuit to supply the same output to the corona discharger during charging and transfer, and operates according to the sequence shown in FIG. 4.

Although this system has the advantage of being small, compact, and inexpensive, it has been difficult to fully satisfy the charging and transfer characteristics.

[Purpose of the invention]

The present invention was made to eliminate the above-mentioned defects, and includes:
It is an object of the present invention to provide a high-voltage power supply device for an electronic copying machine in which each output voltage for charging and transfer is independently set by a high-voltage power supply of a circuit.

[Structure of the invention]

The present invention provides two systems of output voltage detection circuits in the high-voltage power supply, and outputs 14 voltage and 'II;
It is designed to switch between.

〔Example〕

The present invention will be explained in detail below based on examples.

FIG. 5 is a schematic side view of a photosensitive drum 2 rotation 1 copy cycle type copying machine, in which the copy start switch is turned on by the user and the photosensitive drum (1) begins to rotate in the counterclockwise direction as shown in the figure. At the same time (2), the document table (2) starts moving rightward (2). Then, the left tip of the document table (2) reaches the lens (2).
3) When it reaches the top, it turns around and starts moving to the left.

At the same time, the original image is transferred through the lens (3) to the photosensitive drum (1).
). At this time, the high-voltage power source is turned on in accordance with the timing when the image at the leading edge of the document begins to form a latent image on the photosensitive drum, and the photosensitive drum (1) is charged by the corona discharger (4).

As the document table (2) moves to the left, lj;
The draft image forms a latent image on the photosensitive drum (1), and the developing device (5)
is developed to form a toner image. When the photosensitive drum further rotates and the leading edge of the toner image reaches the corona charger (4), copy paper is fed from the paper feed tray (6) at the same timing and transfer begins. The transferred copy paper is peeled off from the photosensitive drum by a peeling means, passes through a conveyance means, is fixed by a fixing device (7), and is discharged to a paper discharge tray (8).

During this time, the exposure of the original image is completed, and the original table (2) returns to its original position. In other words, one corona discharge machine is used for charging when the document table is moving forward, and is used for transferring when it is moving backward.

FIG. 6 is a block diagram of a high-voltage power supply according to the present invention, which is the high-voltage power supply shown in FIG. 8 with two output detection sections and a mode switching section added, and its operation follows the sequence shown in FIG. be controlled. That is, when in charging mode, one output detection section is turned on by the control signal of the copying machine, and the output voltage is set and detected, and when in transfer mode, the other output detection section is turned on, and the output is small: 1
1 settings and detection.

Fig. 7 is a detailed circuit diagram of Fig. 6, in which the output detection section is connected to relay RLI in charging mode, and 1tL1/1
The contact closes, and the return flow of the high rhinoceros flows from the ground side line to the high pressure section via RLI/l, R8, R2, and R1. As for the output voltage, the potential of the upper side of R2 relative to the ground is fed back to the control section according to the resistance value of R2. In transfer mode, relay RL2 is turned on, RL2/l contact is closed, and high voltage return current is transferred from the ground side line to RL.
2/1. It flows to the high pressure section via R5, R4°R1.

The output voltage at this time is the same as when charging due to R4,
Settings can be controlled.

In this way, by alternately turning on RLI and RL2, separate output voltages for charging and transfer can be set and controlled.

Although the configuration of the output detection section shown in FIG. 7 is an example, various methods are generally known. The scheme according to the invention can be achieved. Furthermore, there are various methods of configuring the mode switching section, and the two output detection sections can be switched using these methods.

〔Effect of the invention〕

As explained above, according to the present invention, the output voltages for charging and transfer can be set independently with a single high-voltage power supply circuit, so compared to conventional switching systems, the present invention is smaller and lighter. This has the effect of providing an inexpensive copying machine with high image quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of a conventional high-voltage power supply device.
Fig. 2 is a sequence diagram of a weak sequence in which the output voltage of the high voltage power supply is changed for each charging and transfer of the circuit shown in Fig. 1, Fig. 3 is a block diagram of another embodiment of the conventional high voltage power supply, and Fig. 4 3 is a sequence diagram of the circuit shown in FIG. 3, FIG. 5 is a side view of a photosensitive drum and two-rotation, one-copy cycle copying machine to which the present invention is applied, and FIG. 6 is an embodiment of the high-voltage power supply device according to the present invention. FIG. 7 is a detailed circuit diagram of FIG. 6. (1)...Photosensitive drum (2)...l
j；ii１"１゛口台(4)・・・Corona discharger

Claims (1)

[Claims] In an electronic copying machine that uses a photosensitive drum for two rotations and one copy cycle, and uses one corona discharger for both charging and transfer, one high-voltage power supply is equipped with two output detection circuits, and the two output detection circuits are used to detect charges during charging and transfer. A high-voltage power supply device for an electronic copying machine, characterized in that a means for switching each circuit is provided.