JP6788806B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

Since electrophotographic image forming devices such as printers and multifunction devices have built-in parts such as developing rollers that require high voltage, a predetermined high voltage is applied to such parts (for example). See Patent Document 1).

FIG. 2 is a block diagram showing an example of the electrophotographic image forming apparatus 110. As shown in FIG. 2, the electrophotographic image forming apparatus 110 includes a high-voltage substrate 101 and a control substrate 102, and a high voltage is applied to the developing apparatus 103 and the charging apparatus 104 for charging the photoconductor drum. There is.

The high-voltage power supply unit 111 in the high-voltage board 101 includes a booster circuit 112 that boosts the power supply voltage (for example, 24 volts) applied from the control board 102 to generate a high voltage, and a booster circuit according to a control signal supplied from the control board 102. A control circuit 113 for controlling 112 is provided. Further, the control board 102 includes a controller 121 that supplies the control signal. Further, as a cable for electrically connecting the high voltage board 101 and the control board 102, a control signal line CNT, a power supply line Vp, and a power ground line PG are provided.

As shown in FIG. 2, the power ground line PG is used as the ground (power ground) of the booster circuit 112, but is also used as the signal ground SG of the control circuit 113. Further, in the high-voltage board 101, the power ground is connected to the frame in the device (that is, the frame ground FG), and in the control board 102, the power ground is connected to the frame in the device (that is, the frame ground FG). It is connected.

JP-A-2017-32730

However, as described above, when the power ground is also used as the signal ground in the high-voltage substrate 101, when a ripple voltage is generated in the power ground due to the alternating current conducted to the developing device 103 or the like, the signal ground becomes the signal ground. The ripple voltage also propagates. Therefore, the ground level of the control circuit 113 fluctuates, and the output voltage of the booster circuit 112 is controlled with reference to the ground level. Therefore, the output voltage of the booster circuit 112 (that is, the high voltage voltage level) also fluctuates, resulting in development. A part such as the device 103 that requires a high voltage may not operate accurately.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain an image forming apparatus in which a portion requiring high pressure operates accurately.

The image forming apparatus according to the present invention includes a high-voltage substrate including a high-voltage power supply unit that boosts the power supply voltage to generate a high voltage and applies the high voltage to a predetermined portion used in an electrophotographic development process. A control board that applies the power supply voltage to the high-voltage board and supplies a control signal is electrically connected to the high-voltage board and the control board, and the control signal is transmitted from the control board to the high-voltage board. The control signal line, the high-voltage board, and the control board are electrically connected, and the signal ground line indicating the reference ground level of the control signal, and the high-voltage board and the control board are electrically connected. A power line that applies the power supply voltage from the control board to the high voltage board, and a power that electrically connects the high voltage board and the control board separately from the signal ground line and indicates a reference ground level of the power supply voltage. It has a ground line. In the high voltage substrate, the signal ground electrically connected to the signal ground line is not connected to the power ground electrically connected to the power ground line, and the signal ground of the high voltage substrate is the said. The first joint of the high-voltage substrate is electrically connected to the frame ground, and the power ground of the high-voltage substrate is electrically connected to the frame ground at the second junction of the high-voltage substrate, which is different from the first joint. Will be done. In the control board, the signal ground electrically connected to the signal ground line is connected to the power ground electrically connected to the power ground line, and the signal ground of the control board and the control board are connected to the power ground. At least one of the power grounds of the above is electrically connected to the frame ground.

According to the present invention, it is possible to obtain an image forming apparatus in which a portion requiring high pressure operates accurately.

The above or other object, feature and superiority of the present invention will be further clarified from the following detailed description with the accompanying drawings.

FIG. 1 is a block diagram showing a configuration of a high-voltage substrate 1 and a control substrate 2 in the image forming apparatus 10 according to the embodiment of the present invention. FIG. 2 is a block diagram showing an example of the electrophotographic image forming apparatus 110.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a high-voltage substrate 1 and a control substrate 2 in the image forming apparatus 10 according to the embodiment of the present invention.

The image forming apparatus 10 according to this embodiment is an electrophotographic image forming apparatus, and adheres toner to a photoconductor drum, a charging roller for charging the photoconductor drum, and an electrostatic latent image on the surface of the photoconductor drum. It is provided with a developing roller for making the toner image, a transfer roller for the primary transfer or the secondary transfer of the toner image, and the like.

High voltage is required to be applied independently to the parts such as the developing roller, the charging roller, and the transfer roller. Therefore, the image forming apparatus 10 according to this embodiment boosts the power supply voltage to generate a high voltage of a predetermined level at such a portion used in the electrophotographic development process, and generates a predetermined level of high voltage. A high-voltage substrate 1 to which a high voltage is applied and a control substrate 2 for controlling the high-voltage substrate 1 are provided.

The high-voltage substrate 1 includes one or a plurality of high-voltage power supply units 11 depending on the number of high-voltage voltage levels to be output.

The high-voltage power supply unit 11 includes a booster circuit 12 that boosts the power supply voltage (for example, 24 volts) to a high voltage of a predetermined level, and a control circuit 13 that controls the booster circuit 12. The control circuit 13 performs on / off control of the booster circuit 12, level control for maintaining the output voltage of the booster circuit 12 at a predetermined level, and the like. The control circuit 13 receives a control signal with the voltage level of the signal ground line as the reference ground level, controls the booster circuit 12 with the voltage level as the reference ground level, and maintains the output voltage of the booster circuit 12 at a predetermined level. ..

Further, the control board 2 supplies a control signal (a signal for instructing an operation, a clock signal, etc.) to the high-voltage board 1 and applies a power supply voltage to the high-voltage board 1. The control board 2 includes a controller 21 that generates the control signal, and a switching unit 22 that turns on / off the application of the power supply voltage. For example, when the interlock operates, the switching unit 22 cuts off the supply of power supply power to the high-voltage substrate 1.

Further, the image forming apparatus 10 includes a control signal line CNT, a signal ground line SG, a power supply line Vp, and a power ground line PG as cables for electrically connecting the high voltage board 1 and the control board 2 to each other.

The control signal line CNT transmits the above-mentioned control signal from the control board 2 to the high voltage board 1.

The signal ground line SG indicates the reference ground level of the above-mentioned control signal.

The power supply line Vp applies a power supply voltage (for example, 24 volts) from the control board 2 to the high voltage board 1.

The power ground line PG electrically connects the high voltage board 1 and the control board 2 separately from the signal ground line SG, and indicates a reference ground level of the power supply voltage.

In this embodiment, the control signal line CNT is detachable from the high pressure board 1 and the control board 2 at the connectors 14 and 23, and the signal ground line SG is attached to and detached from the high pressure board 1 at the connectors 15 and 24. The power supply line Vp is detachable from the high pressure board 1 and the control board 2 at the connectors 16 and 25, and the power ground line PG is detachable from the connector 17 by the connector 16 and 25. , 26 are removable from the high-pressure board 1 and the control board 2.

Further, the signal ground SG1 on the high-voltage board 1 is electrically connected to the signal ground line SG and the control circuit 13 as a wiring pattern, and the power ground PG1 on the high-voltage board 1 is a power ground line as a wiring pattern or the like. It is electrically connected to the PG and the booster circuit 12.

The signal ground SG1 and the power ground PG1 on the high-voltage substrate 1 are not directly connected on the high-voltage substrate 1.

On the other hand, the signal ground SG1 on the high-voltage substrate 1 is electrically connected to the frame ground FG at the junction 18 of the high-voltage substrate 1, and the power ground PG1 on the high-voltage substrate 1 is a junction of the high-voltage substrate 1 different from the junction 18. At 19, it is electrically connected to the frame ground FG.

For example, at the joints 18 and 19, the metal terminals exposed on the high-voltage substrate 1 can be attached and detached in contact with the metal frame (that is, the frame ground FG) (for example, by screwing). Is fixed. In that case, the signal ground SG1 is electrically connected to the metal terminal of the joint portion 18, and the power ground PG1 is electrically connected to the metal terminal of the joint portion 19.

As a result, the signal ground SG1 and the power ground PG1 are electrically connected, but resistance components such as the contact resistance of the joints 18 and 19 and the electrical resistance of the frame between the joints 18 and 19 are combined with the signal ground SG1. Since it is interposed between the power ground PG1 and the power ground PG1, the propagation of the above-mentioned ripple component is suppressed.

In this embodiment, as shown in FIG. 1, the joint portion 18 and the joint portion 19 have end portions facing each other in the high-voltage substrate 1 (here, the high-voltage substrate 1 has a substantially quadrangular shape. Both ends of one long side of the substantially quadrangular shape) are set for each.

Further, in this embodiment, the joint portion 18 and the joint portion 19 are end portions (high voltage substrates) to which predetermined portions (here, the developing device 3 and the charging device 4) to which a high voltage is applied are electrically connected. It is set at an end different from the end of 1).

Here, the high-voltage substrate 1 has a substantially quadrangular shape, and one of the two long sides of the substantially quadrangular shape is provided with a high-voltage output terminal for the developing device 3 and the charging device 4, and the two lengths thereof. A joint portion 18 and a joint portion 19 are provided at both ends of the other end of the side.

On the other hand, the signal ground SG2 on the control board 2 is electrically connected to the signal ground line SG and the controller 21 as a wiring pattern or the like, and the power ground PG2 on the control board 2 is electrically connected to the power ground line PG as a wiring pattern or the like. And is electrically connected to the switching unit 22.

The signal ground SG2 and the power ground PG2 on the control board 2 are directly connected on the control board 2 by a wiring pattern or the like. Further, at least one of the signal ground SG2 and the power ground PG2 on the control board 2 is electrically connected to the frame ground FG. In this embodiment, the signal ground SG2 is electrically connected to the frame ground FG at the joint 27 in the same manner as the joints 18 and 19.

Next, the operation of the image forming apparatus 10 will be described.

When the development process in the electrophotographic printing process is required, the controller 21 of the control board 2 transmits a control signal for operating the high-voltage board 1 via the control signal line CNT and the signal ground line SG to the high-voltage board 1. A power supply voltage is applied to the high voltage substrate 1 via the power supply line Vp and the power ground line PG.

In the high-voltage substrate 1, the control circuit 13 receives the control signal and controls the booster circuit 12 according to the control signal. The booster circuit 12 operates according to the control circuit 13, boosts the power supply voltage to generate a high voltage of a predetermined level, and applies it to the developing device 3, the charging device 4, and the like.

Then, the developing device 3, the charging device 4, and the like execute the developing process. That is, after the charging device 4 charges the photoconductor drum, an electrostatic latent image corresponding to the printed image is formed on the photoconductor drum by the exposure device, and the toner charged by the developing device 3 becomes the electrostatic latent image. It adheres and develops. The toner image obtained by the developing process is transferred to printing paper or the like and fixed by a fixing device.

As described above, according to the above embodiment, the control signal line CNT electrically connects the high voltage substrate 1 and the control substrate 2 and transmits the control signal from the control substrate 2 to the high voltage substrate 1. The signal ground line SG electrically connects the high voltage board 1 and the control board 2 and indicates a reference ground level of the control signal. The power supply line Vp electrically connects the high-voltage board 1 and the control board 2, and applies the power supply voltage from the control board 2 to the high-voltage board 1. The power ground line PG electrically connects the high voltage board 1 and the control board 2 separately from the signal ground line SG, and indicates a reference ground level of the power supply voltage. The signal ground SG1 of the high-voltage substrate 1 is not connected to the power ground PG1 of the high-voltage substrate 1, but is electrically connected to the frame ground FG at the joint 18 of the high-voltage substrate 1. The power ground PG1 of the high-voltage substrate 1 is electrically connected to the frame ground FG at a junction 19 of the high-voltage substrate 1 which is different from the junction 18. The signal ground SG2 of the control board 2 is connected to the power ground PG2, and at least one of the signal ground SG2 and the power ground PG2 of the control board 2 is electrically connected to the frame ground FG.

As a result, since the signal ground line SG and the power ground line PG are made independent, the influence of the ripple component propagation from the high voltage side to the low voltage side is suppressed.

Further, in the high-voltage substrate 1, the signal ground SG1 and the power ground PG1 are electrically connected to the frame ground FG at separate joints 18 and 19, respectively, and a contact failure may occur at the connectors 15 and 24 or the connector 15 may occur. , 24 Even if the signal ground line SG falls off from the high voltage board 1 or the control board 2 and is electrically cut off, the frame even though the signal ground line SG and the power ground line PG are made independent. Since the ground FG functions in place of the signal ground line SG, the reference ground level of the control signal does not become unstable.

It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without leaving the intent and scope of the subject and without diminishing the intended benefits. That is, it is intended that such changes and amendments are included in the claims.

The present invention is applicable to, for example, an electrophotographic image forming apparatus.

1 High-voltage substrate
2 Control board 10 Image forming device

Claims (3)

A high-voltage substrate including a high-voltage power supply unit that boosts the power supply voltage to generate a high voltage and applies the high voltage to a predetermined portion used in an electrophotographic development process.
A control board that applies the power supply voltage to the high-voltage board and supplies a control signal,
A control signal line that electrically connects the high-voltage board and the control board and transmits the control signal from the control board to the high-voltage board.
A signal ground line that electrically connects the high-voltage board and the control board and indicates a reference ground level of the control signal,
A power supply line that electrically connects the high-voltage board and the control board and applies the power supply voltage from the control board to the high-voltage board.
In addition to the signal ground line, the high voltage board and the control board are electrically connected to each other, and a power ground line indicating a reference ground level of the power supply voltage is provided.
In the high voltage substrate, the signal ground electrically connected to the signal ground line is not connected to the power ground electrically connected to the power ground line.
The signal ground of the high-voltage substrate is electrically connected to the frame ground at the first joint of the high-voltage substrate.
The power ground of the high-voltage substrate is electrically connected to the frame ground at a second junction of the high-voltage substrate different from the first junction.
In the control board, the signal ground electrically connected to the signal ground line is connected to the power ground electrically connected to the power ground line.
At least one of the signal ground of the control board and the power ground of the control board is electrically connected to the frame ground.
An image forming apparatus characterized by. The image forming apparatus according to claim 1, wherein the first joint portion and the second joint portion are set at respective ends of the high-voltage substrate facing each other. The image forming apparatus according to claim 2, wherein the first joint portion and the second joint portion are set at an end portion different from the end portion to which the predetermined portion is electrically connected.

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