JPH07140763A - Image forming device - Google Patents

Abstract

PURPOSE:To properly set the rubbing speed of an electrostatic charging means to effectively remove a contaminant and to always stably and excellently electrostatically charge an electrostatic charging member by constituting so that a cleaning means may travel at relative speed to the electrostatic charging member. CONSTITUTION:The electrostatic charging roller 2 is movably fitted in a pair of holders 5 so that it can contact with/separate from an image carrier 1, and is rotated following the image carrier 1. A cleaning roller 3 is rotatably disposed in the holders 5, and a gear disposed at the end of the roller 3 is meshed with a driving gear provided at the end of the image carrier 1 through a gear train 4. In such a case, the gear train 4 is set so that the image carrier 1 and the roller 3 are rotated in the same direction, that is, they travel in an opposite direction each other at the abutting position of both of them. The cleaning roller 3 is press-contacted to the roller 2 by a specified entering amount. Since the roller 3 travels in the opposite direction to the roller 2 at a nip part, its foreign matter removing ability becomes excellent.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrostatic transfer process such as an electrostatic copying machine and a printer.

First, an image forming apparatus suitable for applying the present invention will be briefly described. FIG. 5 is a schematic side view showing a typical example of such a known image forming apparatus. It is assumed that the surface photosensitive layer of the image carrier 1 extending in the direction perpendicular to the paper surface and rotating in the direction of the arrow in the figure is uniformly charged by the primary charging roller 2.

The charging roller 2 is formed by forming an outer layer 2b made of an elastic material such as rubber around a conductive cored bar 2a arranged parallel to the axis of the image carrier 1 and using a suitable means such as a spring. It is assumed that the image carrier 1 is pressed into contact with the image carrier 1 and rotates in the case of the apparatus shown in FIG.

Reference numeral 11 in the figure denotes a power source for applying a charging bias, and the bias may be a DC drink, but it is preferable to apply an oscillating voltage in which an AC voltage is superposed on it.

An image signal is projected on the surface of the image carrier uniformly charged by the charging roller 2 to form an electrostatic latent image, and this latent image is developed by the developing device 15 as the image carrier rotates. When it reaches the developing portion arranged, the toner is supplied from now on and visualized to form a toner image.

Further, when the toner image reaches the transfer portion where the transfer roller 16 is arranged by the rotation of the image carrier, a transfer bias is applied to the transfer roller by the power source 17 and the transfer material P is applied to the transfer portion. Supplied.
Here, the toner image on the image carrier side is transferred to the transfer material by the action of the transfer bias, and the transfer material carrying the toner image is separated from the image carrier and advances to the left side in the drawing to reach a fixing portion (not shown). .

A part of the toner 12 which has not transferred to the transfer material at the transfer portion reaches the cleaning device as it is, and is removed by the cleaning blade 14 provided on the cleaning device, so that the image carrier is ready for the next image forming step. It is ready to enter.

In the image forming apparatus having such a structure, as the toner is used for a long period of time, toner that has slipped through the cleaning blade, toner floating in the main body of the apparatus, etc., gradually adheres to the charging roller 2 and contaminates it. There arises a problem that uneven charging, poor charging, etc. are caused to deteriorate image quality. Also, the cleaning blade 14 scrapes the photosensitive layer on the surface of the image carrier, though a small amount, and the scraped powder rides on the image carrier and reaches the charging roller 2 to contaminate it.

In the case of the apparatus shown in the figure as a means for removing dirt from these, a plate-shaped blade 13 made of sponge, fine fibers or the like is pressed against the charging roller 2 to scrape off and remove adhering substances.

On the other hand, such means cannot cope with a case where a large amount of contamination is suddenly generated, for example, when a jam occurs, and the contamination remains on the charging roller. This inevitably causes the image defects as described above.

Further, although the shavings of the image bearing member generated from the above-mentioned image bearing member cause a charging failure although they are in a small amount, they cannot be sufficiently captured by the plate blade as described above. Is known.

The present invention has been made to cope with such a situation, and contaminants are effectively removed by appropriately setting the rubbing speed of the charging means used in the image forming apparatus as described above. Another object of the present invention is to provide an image forming apparatus that can always stably and favorably charge a charging member such as a charging roller.

[0013]

[Constitution of the invention]

In order to achieve the above object, the present invention provides a charged member having a traveling charged surface and a contacting member for charging the charged surface. The charging member is provided with a moving charging member and a cleaning unit for contacting the charging member to remove foreign matter on the charging surface, and the cleaning unit is configured to move at a relative speed with the charging member, or In the image forming apparatus, the relative speed of the cleaning unit with respect to the charging member is configured to change according to the number of sheets passed through the image forming apparatus.

With this structure, the toner and other foreign matter adhered to the charging member can be effectively removed, and good charging can be performed, which contributes to the improvement of image quality.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS "FIG. 1" and "FIG. 2" are a perspective view and a partial side view showing an embodiment of the present invention, in which reference numeral 1 denotes an image carrier which is a member to be charged, In parallel with this, the charging roller 2 is in pressure contact.

The charging roller 2 has a structure in which a cored bar is covered with an outer layer made of an elastic material as in the case shown in FIG. 5, and both ends of the cored bar are projected outward. A pair of holders 5 whose parts are provided in proper positions on the device main body side
And is loosely fitted to the image carrier so as to be able to come into contact with and separate from the image carrier, and the projecting portion is pressed by a spring (not shown) to press the charging roller 2 against the image carrier at an appropriate pressure to follow the image carrier. It is designed to rotate.

A cleaning roller 3 having a cleaning material wound around the core metal 10 is rotatably disposed on the holder 5, and a gear disposed on at least one end of the cleaning roller 3 is provided. The gear train 4 meshes with a drive gear provided at the end of the image carrier 1. In this case, the gear train is set so that the image bearing member 1 and the cleaning roller 3 rotate in the same direction, that is, the rollers run in opposite directions at positions where they are in contact with each other.

The cleaning roller 3 is formed into a roller shape by winding a cleaning material such as a felt layer around a core metal having a diameter of 6 mm to a thickness of 3 mm. The cleaning roller 3 has a penetration amount of about 1 mm with respect to the charging roller. It should be pressed so that The faster the rubbing speed with the charging roller, the higher the cleaning ability. However, if the rubbing speed is too fast, heat may be generated and the existing toner may be fused to the cleaning roller. Therefore, the contact portion between the charging roller 2 and the cleaning roller 3 The relative speed at is preferably about 350 mm / sec.

The cleaning roller 3 is in a state of braking the rotation of the charging roller which is rotated by being pressed against the image carrier, and the nip width formed at the portion where the charging roller is pressed against the image carrier. However, according to the cleaning roller of the present invention, since the cleaning roller travels in the opposite direction to the charging roller at the nip portion, the foreign matter removing function is excellent and the cleaning roller strongly presses the charging roller. There is no need, and the above problems can be easily cleared.

FIG. 2 shows another embodiment of the present invention, in which only the charging roller 3 and the cleaning member abutting on the charging roller 3 are shown. This cleaning member has a cored bar 10 provided with a brush 9. Brush 9
Is a conductive acrylic resin and has a resistivity of 10 ² to 10 ⁵ Ωc
m, thickness 6.2 denier, length 5 mm fiber 3000
A roller-shaped member is used in which the core metal 10 is wound at a density of book / psi.

Such a cleaning member is brought into contact with the charging roller 2 with an invasion amount of about 1 to 3 mm to perform rubbing cleaning. The fibers forming the brush may be Tetron, polyester, rayon or the like other than the above.

When such a cleaning member is used, since the brush member is in contact with the charging roller in a bent state, it is possible to reduce the substantial contact pressure to the charging roller without lowering the cleaning ability. It has become possible.

Further, since the rubbing action including the bending action by the fibers has the action of removing the adhered substances, the phenomenon that the brush itself is not contaminated by the foreign matter removed from the charging roller is increased, and the life of the cleaning member is increased. be able to.

FIG. 3 is a perspective view of an essential part showing still another embodiment of the present invention. The drawing shows the side where the cleaning roller is driven from the image carrier through the gear train, and the portions corresponding to those shown in FIG. 1 are designated by the same reference numerals.

Intermediate gears 4a, 4b, 4c are meshed with a drive gear provided at the end of the image carrier 1, and a pulley 6 is formed in the gear 4c in the axial direction. A drive belt 7 is wound between the pulley 6 and the end of the core metal 10 protruding from one end of the cleaning roller 3 as shown in the drawing, and the belt 7 is attached to the pulley 6. It is fixed.

When the image carrier rotates during the copying operation, the pulley 6 rotates through the gears 4a, 4b and 4c, and the belt 7
However, the cleaning roller 3 is wound around this and travels in the direction opposite to the charging roller to perform rubbing cleaning.
When this apparatus is used in a cartridge type image forming apparatus, it is necessary to set such that the belt 7 is entirely wound around the pulley 6 when the image bearing member rotates so as to reach the life of the cartridge. To do.

With this configuration, the number of rotations of the cleaning roller 3 per rotation of the image carrier 1 is small at the beginning, and therefore, the charging roller 2 is also slowly rubbed and cleaned. As the number of durable sheets increases, the number of rotations of the cleaning roller 3 with respect to the charging roller 2 increases and the rubbing is performed at a higher speed, which is convenient because the cleaning ability of the cleaning roller increases as the contamination of the charging roller increases.

In the case of this device, an increase in the outer diameter of the belt 7 wound around the pulley 6 (or a decrease in the outer diameter of the belt 7 wound around the core metal 10 is detected by an appropriate means, Alternatively, if the increase or decrease in the outer diameter can be visually recognized from the outside, it is possible to predict the arrival of the cartridge replacement time.

When the charging roller is not so dirty, rubbing with the cleaning roller may cause uneven charging or damage the charging roller, but as the durability of the charging apparatus is increased, the charging roller may be damaged. By increasing the cleaning ability, it is possible to perform cleaning depending on the stain.

[0030]

As described above, according to the present invention,
In the case where the surface dirt of the charging member is rubbed and cleaned by the cleaning member, a large amount of dirt may be suddenly generated, or shavings generated from the photosensitive layer of the image carrier having a high affinity with the charging member may exist. In this case, since it is possible to sufficiently remove them, and it is possible to improve the cleaning ability as the durability advances and the contamination of the charging member progresses, there is a remarkable effect on the cleaning of the charging member. It greatly contributes to obtaining images.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a side view showing another configuration of the cleaning member.

FIG. 3 is a perspective view of an essential part showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing the configuration and operation of a known image forming apparatus.

[Explanation of symbols]

 1 Image Carrier 2 Charging Roller 3 Cleaning Roller 4 Gear Train 5 Holder 6 Pulley 7 Belt 10 Core Bar 11, 17 Power Supply 13 Blade 14 Cleaning Blade 15 Developer 16 Transfer Roller

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Nobuyuki Kume 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (6)

[Claims] 1. A charged member having a surface to be charged that runs,
The charging member includes a running charging member that contacts the surface to be charged to charge it, and a cleaning unit that contacts the charging member to remove foreign matter on the charging surface, and the cleaning unit is opposed to the charging member. An image forming apparatus characterized by traveling at a speed. 2. The image forming apparatus according to claim 1, wherein the cleaning means is a roller made of an elastic material. 3. The cleaning means uses fibers having a thickness of 50 to 500 denier and a length of 1 to 5 mm in a density of 100.
The image forming apparatus according to claim 1, wherein the image forming apparatus is a brush formed by implanting at 0 to 3000 brushes / inch. 4. The image forming apparatus according to claim 3, wherein the brush as a cleaning means is set to have a penetration amount of 0.5 to 5 mm with respect to the charging member. 5. The image forming apparatus according to claim 1, wherein the relative speed between the cleaning unit and the charging member is set to 0 to 300 mm / sec. 6. The image forming apparatus according to claim 1, wherein the relative speed of the cleaning unit with respect to the charging member changes in accordance with the number of sheets passed through the image forming apparatus.