JPH0244294Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a corona discharge device that includes a corona discharge device used for charging and neutralizing a photoreceptor in an electronic copying device, and a high-voltage power supply that supplies high voltage to the corona discharge device. In particular, by integrating the corona discharger and the high-voltage power supply, it is possible to omit the high-voltage supply wires used in conventional corona discharge devices, thereby making the installation less noisy, safe, and compact. The present invention aims to provide a corona discharge device that is not subject to space restrictions, and thereby promotes the realization of electronic copying devices that are compact and consume little power. Furthermore, the present invention supplies high voltage to the wire of the corona discharge from a high voltage power supply inside the corona discharger, so that when the corona discharger is removed from the electronic copying machine, the high voltage power supply is connected to the corona discharger. The present invention aims to realize an electronic copying apparatus that automatically stops output and has excellent safety and operability.

Conventional corona discharge equipment has the following problems: 1. When the discharge wire of the corona discharger comes into contact with the case etc. of the corona discharger due to breakage etc., a large current flows from the high voltage power supply to the case etc., and noise is generated from the high voltage supply wire, causing other problems. have a negative effect on the electrical circuits.

2. When alternating current is supplied from a high-voltage power supply to a corona discharger, a leakage current flows due to the distributed capacitance of the high-voltage supply wire, reducing the effective portion of the high-voltage power supply output for corona discharge, so a high-voltage power supply with a large output capacity is required.

3. Since the above leakage current varies greatly depending on the length of the high-voltage supply wire, the distance between the high-voltage supply wire and other parts, etc., there is a limit to the distance from the high-voltage power supply to the corona discharger. In addition, high-voltage supply wires and other parts,
In particular, it must be separated from parts that move near the high-voltage power supply line, which complicates the structure of electronic copying machines and the like.

4. A terminal is required to connect the corona discharger and the high-voltage supply wire, but this terminal is generally
Since the electronic copying device is attached to a housing, it must be insulated, making the structure complicated.
Further, if a developer or the like adheres to the insulating part of the terminal, the withstand voltage decreases and spark discharge occurs on the surface of the insulating part, causing breakdown of the insulating part and noise.
Furthermore, if the corona discharger is removed from the connection terminal while high voltage is being supplied to the corona discharger, the high voltage continues to be supplied to the connection terminal, so there is a risk of electric shock during maintenance and inspection.

There were other drawbacks.

Figure 1 shows a high-voltage power supply circuit for corona discharge using a switching method that has been commonly used in the past. By doing so, a pulse is applied to the primary winding 5 of the flyback transformer 4, a high alternating current voltage is obtained to the secondary winding 6, this is further rectified and smoothed, and the output terminal 7 receives the voltage necessary for corona discharge. It obtains a high voltage of 6000 to 7000V. High-voltage power supplies using this switching method are much smaller and lighter than the conventionally used ferro-resonant transformer-based high-voltage wires. There were restrictions on downsizing the secondary winding of the back transformer. This means that the voltage applied to the primary winding of the flyback transformer is 12
~40V, so 6000~ required for corona discharge
This is because in order to obtain 7000V, it is necessary to set the turns ratio N ₂ /N ₁ of the flyback transformer to about 250, and as a result, the number of turns of the secondary winding becomes 4000 to 5000 turns.

FIG. 2 is a schematic diagram of an electronic copying machine to which a corona discharge device according to the present invention is applied, in which a is a corona discharger, b is an exposure section, c is a developing section, d is a cleaning section, and e is a The transfer paper separation section m is a photoconductor, and as shown in the figure, the exposure section b to transfer paper separation section e are incorporated around the photoconductor m in which the corona discharger a is incorporated. , the space around corona discharger a is small. Therefore, when attempting to integrate a corona discharger and a high voltage power supply as in the present invention, it is necessary to
The high voltage power supply used as an embodiment of the present invention requires miniaturization, especially thinning, by connecting a multiplier rectifier circuit to the secondary winding of the flyback transformer, as will be described later. The winding of the secondary winding is reduced to about 1/5 of the conventional one, thereby reducing the thickness of the high-voltage power supply to about 20 mm, about 1/2 of the conventional thickness, making it possible to integrate the high-voltage power supply and the corona discharger. .

FIG. 3 is a diagram showing an example of a high-voltage power supply circuit used in implementing the present invention, and a driving DC voltage, for example, 24V, is applied to the input terminal 1. This causes the oscillator 11 in the IC 10 to start operating at approximately 20kHz, and then the pulse width modulation circuit (PWM) 12
The 20kHz signal from the oscillator 11 is compared with the signals from the output voltage control circuit 13 and the output current control circuit 14, a pulse signal corresponding to each signal is generated, and this pulse signal is passed through the dry circuit 15 to the switching transistor 3. Apply to the base and perform 20kHz switching. As a result, a pulse is applied to the primary winding 5 of the flyback transformer 4, and the
An AC voltage corresponding to the turns ratio between the primary winding 5 and the secondary winding 6 is obtained in the secondary winding 6, and this voltage is applied to the 5-times voltage doubler circuit 2.
In addition to 0, an output voltage of 6500V is obtained from output terminal 7. Further, the lamp 30 indicates that the corona discharger is discharging, and this lamp 30 indicates that the corona discharger is discharging.
It is configured to be turned on using the voltage generated in the next winding 31.

FIG. 4 is a diagram for explaining an embodiment in which the corona discharge device according to the present invention is incorporated into an electronic copying machine. DC voltage 24V passes through the power supply line 41 to the high voltage power supply section 42
Here, 20kHz switching is performed to obtain a high voltage output of 6500V. This high voltage output is applied to the discharge wire a ₁ of the corona discharger a, where it causes a corona discharge and charges the photoreceptor m.

FIG. 5 is a perspective view of a corona discharge device that integrates a corona discharge device and a high-voltage power supply according to the present invention. In the figure, 50 is a case of the corona discharge device, and in the corona discharge device section a, a discharge wire a ₁ is shielded. Further, 42 is a high-voltage power supply section, and by configuring the high-voltage power supply section 42 integrally on, for example, the corona discharger section a, it is possible to integrate the power input terminal 1 to the high-voltage power supply section with the corona discharge device, at the same time,
When the corona discharger is removed from the apparatus main body during corona discharge, the input terminal 1 is detached from the main body side terminal and the high voltage power supply automatically stops operating. 30 is a lamp that indicates that corona discharge is in progress, and this can be done by easily obtaining a low voltage by integrating the high voltage power supply with the corona discharger. By doing so, it can be seen at a glance that corona discharge is occurring, and dangers such as electric shock during maintenance and inspection can be avoided. 40 is a printed board incorporating the drive circuit, control circuit, etc. of the high-voltage power supply section;
20kHz switching is performed, a pulse is applied to the primary winding 5 of the flyback transformer 4, and a pulse is applied to the secondary winding 6 of the flyback transformer 4.
An alternating current high voltage is obtained from the circuit, and this is applied to the voltage doubler circuit 20 to obtain a high voltage output of 6500V, which is applied to the discharge wire _a1 to perform corona discharge. Note that an insulating plate 5 is provided between the printed board 40, the flyback transformer 4, the voltage doubler circuit 20, etc., and the case 50.
1 is provided, and the area around the flyback transformer 4 and voltage doubler circuit 20 is filled with an insulating resin such as silicone, although not shown.

As explained above, according to the present invention, since the corona discharger and the high-voltage power supply are integrated, high voltage can be directly supplied to the corona discharger from the high-voltage power supply without using a high-voltage supply wire, and Therefore, there is no leakage current during AC output, and harmful noise can be reduced. Since there is no need to separate the high-voltage power supply line from other parts, it is possible to simplify the structure of an electronic copying device, etc., and to make the installation location of the corona discharger more flexible. Further, since a connection terminal for receiving high voltage is not required, surface leakage at the terminal portion can be eliminated. Furthermore, when the corona discharger is removed from the electronic copying machine, the output of the high-voltage power supply is automatically stopped, making it very safe. Furthermore, it is possible to easily display information during corona discharge and to automatically stop corona discharge, making it possible to provide a small, safe, and low-cost corona discharge device, and making it possible to miniaturize and reduce costs in electronic copying machines, etc. It is possible to promote the realization of reduced power consumption.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a conventional high-voltage power supply circuit, FIG. 2 is a schematic configuration diagram of an electronic copying machine, and FIG.
The figure is a circuit diagram of a high-voltage power supply used in the corona discharge device according to the present invention, FIG. 4 is a schematic configuration diagram showing an example of the case where the corona discharge device according to the present invention is incorporated into an electronic copying machine, and FIG. FIG. 1 is a configuration diagram of a corona discharge device according to the present invention. 1...Input terminal, 4...Flyback transformer, 5...Primary winding, 6...Secondary winding, 7...Output terminal, 10...IC, 20...Voltage doubler circuit, 3
0... Lamp, 31... Tertiary winding, 40... Printed board, 42... High voltage power supply section, a... Corona discharger section, a... Corona discharge wire.

Claims (1)

[Scope of utility model registration request] It has a corona discharger section having a corona discharge wire, and a high voltage power supply section which is composed of an oscillation circuit, a transformer, a multiplier rectifier circuit, etc. and supplies a high voltage to the corona discharge wire. In a corona discharge device in an image forming apparatus that supplies high voltage to a discharge wire, the corona discharger section and the high voltage power supply section are integrally housed in a case, and the case includes a main body side of the image forming apparatus. an input terminal that is detachably connected to a terminal on the main body side connected to a low-voltage DC power source that drives the high-voltage power source, and that is connected to the high-voltage power source; A corona discharge device for an image forming apparatus, wherein the input terminal is detached from the main body side terminal when the apparatus is removed from the main body.