JPH04289877A - Conductive brush charging device - Google Patents

Abstract

PURPOSE:To perform a stable charge over a long period without deteriorating charging ability, relating to a conductive brush charging device used for charging a recording material. CONSTITUTION:A moving means 7 for moving a conductive brush 2 in a circumferential direction and an adhesive toner removing means 1, placed on the halfway of moving so as to come into contact with a brush fiber 5, for removing toners adhering to the conductive brush 2 are provided and also providing a voltage applying means 20 for applying voltage of reverse polarity to charging polarity of the toner.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive brush charging device used for charging a recording medium in an electrophotographic copying machine, an electrophotographic printer, an electrostatic printer, or the like. 2. Description of the Related Art As copying machines and printers are required to be smaller, simpler, and lower in price, there is a need to develop a charging device that has a small and simple configuration and is capable of uniform and stable charging.

0002

2. Description of the Related Art Conventionally, a corona charging device shown in FIG. 6 has been widely used as a charging means for recording media in electrophotographic copying machines, electrophotographic printers, and the like. In FIG. 6, a wire 11 is provided in parallel along the surface of a drum-shaped recording medium 3, a shield case 12 is provided to house the wire 11, and a high voltage is applied to the wire 11 to uniformly spread the wire 11 over the recording medium 3. It is charged with electricity.

However, corona chargers are dangerous because they require a high voltage of several kilovolts to generate corona discharge, and ozone is generated which contaminates the atmosphere and equipment. In order to solve these problems, attempts have been made to use a brush charging method, as shown in FIG. 7, in which a voltage is applied to the conductive brush 2 and the brush 2 is brought into contact with the surface of the recording medium 3 to perform charging.

[0004] This method enables charging at a constant voltage of 500 V to 1.5 KV, is less affected by ozone, and allows the device to be made smaller, simpler, and lower in price. In addition, in FIG. 7, 13 is an exposure means, 14 is a developing device, 15 is a transfer device, and 16
1 is a recording paper, 17 is a static eliminator, 18 is a fixing device, and 19 is a cleaner.

[0005]

[Problems to be Solved by the Invention] Electrophotographic copying machines, electrophotographic printers, etc. perform printing by repeating a series of processes of charging, exposure, development, transfer, neutralization, cleaning, and fixing. The toner that has adhered to the recording medium 3 during the development process is transferred to the recording paper 16 during the transfer process, but it is difficult to transfer all of the toner that has adhered to the recording medium 3.
Toner remains on the recording medium 3.

Although this residual toner is removed by the cleaner 19, a small amount of toner remains on the recording medium 3 and is transferred to the charging process. In this device, since the conductive brush 2 is in contact with the surface of the recording medium 3, residual toner on the recording medium 3 adheres between the conductive fibers constituting the conductive brush 2, and the resistance value of the conductive brush 2 increases. There was a problem in that the chargeability increased, the charging ability decreased, and stable charging could not be performed for a long period of time.

The present invention has been made in view of these conventional problems, and provides a conductive brush charging device that can perform stable charging over a long period of time without reducing charging ability. It is intended to.

[0008]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. In FIG. 1, 2 is a conductive brush having brush fibers 5, 3 is a recording medium, 7 is a moving means for moving the conductive brush 2 in the circumferential direction, and 1 is in the middle of movement so as to come into contact with the brush fibers 5. Adhered toner removing means 20 is provided for removing toner adhering to the conductive brush 2, and voltage applying means 20 is provided for applying a voltage having a polarity opposite to the charged polarity of the toner.

[0009]

[Operation] In the present invention, since the conductive brush 2 is charged by bringing it into contact with the surface of the recording medium 3, the residual toner on the recording medium 3 may adhere between the brush fibers 5 constituting the conductive brush 2. By moving the conductive brush 2 in the circumferential direction, the brush fibers 5 of the conductive brush 2 come into contact with the adhering toner removing means 1 provided in the middle of the movement of the conductive brush 2, and the toner adhering to the brush fibers 5 is removed. , it is possible to prevent the charging ability from decreasing, and the recording medium 3 can be stably charged over a long period of time.

Since the voltage applying means 20 applies a voltage having a polarity opposite to the charged polarity of the toner, the attached toner can be removed more reliably.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. 2 to 4 are diagrams showing one embodiment of the present invention. In FIGS. 2 and 3, reference numeral 3 denotes a recording body for forming an image, and a conductive brush 2 is provided parallel to the recording body 3.

The conductive brush 2 uniformly charges the recording medium 3 and has a conductive base 6 and brush fibers 5 made of conductive rayon pile fabric attached to the base 6. Reference numeral 7 denotes a handle as a moving means for moving the conductive brush 2 in the circumferential direction, and the handle 7 is fixed to the base 6. A shaft 4 is provided to pass through the handle 7, and the shaft 4 is held by a frame 8.

A guide hole 9 is formed in the frame 8, into which the end 6A of the base 6 is movably inserted. Therefore, by moving the handle 7 in the direction shown by the arrow, the conductive brush 2 can be moved in the circumferential direction along the guide hole 9. Reference numeral 1 denotes an adhered toner removing rod 1 serving as an adhered toner removing means, and the adhered toner removing rod 1 is in the middle of moving the conductive brush 3, and the adhered toner removing rod 1 is attached to the brush fibers 5 of the conductive brush 2.
It is set up so that it comes into contact with.

The adhered toner removing rod 1 is made of a conductive material and is rotatably held by the frame 8 or fixed to the frame 8. Reference numeral 20 denotes a power source as a voltage applying means, and the power source 20 applies a voltage having a polarity opposite to the charged polarity of the toner to the adhered toner removing rod 1. Next, the effect will be explained.

The conductive brush 2 comes into contact with the surface of the recording medium 3,
When residual toner on the recording medium 3 adheres to the conductive brush 2 and the charging ability decreases (for example, after printing several thousand sheets), the handle 7 is manually moved as shown by the arrow. The guide hole 9 provided in the frame 8 and the adhered toner removal rod 1 are located on a circumference centered on the shaft 4, and the conductive brush 2 is moved along the guide hole 9 by moving the handle 7.

At this time, the brush fibers 5 slide on the adhering toner removing rod 1, and the toner adhering to the brush fibers 5 is separated by friction with the adhering toner removing rod 1 and falls onto the recording medium 3. As a result, the adhered toner is removed and the charging ability can be restored. In this embodiment, since the power supply 20 applies a voltage having a polarity opposite to the charged polarity of the toner to the adhered toner removing rod 1, the toner can be removed more reliably.

FIG. 4 shows the relationship between the voltage applied to the brush and the charging potential before and after removing the adhered toner. For example, after 30,000 sheets have been continuously recorded, the charging ability decreases due to the adhesion of residual toner, resulting in a graph before removing the adhering toner, as shown by the black circle in FIG. After removing the toner adhering to the conductive brush 2, the charging ability is recovered as shown in the graph indicated by the white circles in FIG. 4, and it can be seen that the charging potential is about 80 V higher even with the same brush applied voltage.

In this embodiment, the handle 7 was moved manually, but a drive system such as a motor is provided to move the conductive brush 2 periodically (for example, every several hundred sheets of printing).
It is possible to remove toner that has adhered to the surface. As a result, toner can be removed at a time when less toner adheres to the conductive brush 2, toner can be removed more effectively, and recovery of charging ability can be expected.

Next, FIG. 5 is a diagram showing another embodiment of the present invention. In FIG. 5, reference numeral 10 indicates a plurality of adhesion toner removal rods as adhesion toner removal means, and the adhesion toner removal rods 10 are arranged in a line so as to be in contact with the brush fibers 5 while the conductive brush 2 is moving. It is being Further, a voltage having a polarity opposite to the toner conductivity is applied to the adhered toner removing rod 10 by a power source 20.

As described above, by using a plurality of adhered toner removing rods 10 and applying a voltage having a polarity opposite to that of the toner, toner can be removed more efficiently. Note that the other configurations and effects are the same as those of the previous embodiment.

[0021]

[Effects of the Invention] As explained above, according to the present invention, it is possible to remove the toner adhering to the conductive brush, so it is possible to prevent the deterioration of the charging ability and to perform charging for a long period of time. be able to.

[Brief explanation of the drawing]

[Figure 1] Diagram explaining the principle of the present invention

[Fig. 2] Front view showing one embodiment of the present invention

[Fig. 3] Side view showing one embodiment of the present invention

[Figure 4] Relationship diagram between brush applied voltage and charging potential

FIG. 5 is a diagram showing another embodiment of the present invention.

[Fig. 6] Explanatory diagram of a conventional corona charging device

[Figure 7] Schematic diagram of a conventional electrophotographic device

[Explanation of symbols]

1, 10: Adhered toner removal rod (adhered toner removal means) 2
: Conductive brush 3: Recording body 4: Shaft 5: Brush fiber 6: Base 6A: End 7: Handle (moving means) 8: Frame 9: Guide hole 20: Power source (voltage application means)

Claims (2)

[Claims] 1. A conductive brush (2) having brush fibers (5).
) in a conductive brush charging device that charges a recording medium (3) by bringing it into contact with the surface of the recording medium (3), a moving means (7) for moving the conductive brush (2) in the circumferential direction, and a moving means (7) for moving the conductive brush (2) in the circumferential direction; (5) so as to make contact with the conductive brush (2).
) attached toner removing means (1) for removing toner attached to the
), and a voltage applying means (20) for applying a voltage having a polarity opposite to the charging polarity of the toner. 2. The conductive brush charging device according to claim 1, further comprising a plurality of adhering toner removing means (10) arranged side by side.