JPH09185305A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove fixing oil transferred to the surface of an image carrier before the oil reaches a cleaning means in the case of forming a double-sided image and to prevent the fixing oil adhering to the surface of a material to be recorded from adhering to the cleaning means by providing a means for removing the residual oil on the surface of the image carrier between a transfer means and the cleaning means. SOLUTION: The oil removing means 6 is provided with an unwinding roll 25 round which an oil absorbing web W is wound, a take-up roller 26 taking up the web W unwound from the roll 25, a metallic bar 27 for pressing the web W to a photoreceptor drum 2, and a solenoid 28 for making the bar 27 abut on/separate from the drum 2. In the case of forming the double-sided image, a solenoid 28 is actuated after a transfer material is separated from a transfer drum so as to press the bar 27 to the drum 2, whereby the oil is removed from the image carrier by the web W. When the drum 2 is rotated once thereafter, the bar 27 is separated from the drum 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a printer or a copying machine, and in particular, it forms an image by transferring and fixing a developed image formed on an image carrier onto a transfer material. The present invention relates to a double-sided image forming apparatus that performs

[0002]

2. Description of the Related Art In a known image forming apparatus including a step of transferring a toner image electrostatically formed on the surface of an image carrier to a transfer material such as paper, all the toner is transferred to the image carrier during transfer. Since it is difficult to transfer the residual toner to the transfer material and it is inevitable that some toner remains on the image bearing member, it is necessary to sufficiently clean the residual toner each time the transfer is performed.

As a cleaning means for this purpose, various proposals have been made in the past, but a sharp edge formed on a cleaning blade made of an elastic material such as urethane rubber is pressed against the surface of the image bearing member to cause residual toner. It is well known that the device configured to scrape off is widely used since it has a simple structure, a small size, and is advantageous in terms of cost. In order for the cleaning blade to continue the cleaning function, it is necessary to prevent impurities other than toner from adhering to the blade tip. In addition, since the presence of impurities or scratches on the surface of the image carrier may affect the image, impurities do not adhere to the surface of the image carrier so that the initial state can be maintained on the surface of the image carrier as much as possible. Need to do so.

[0004]

However, when images are formed on both sides of the transfer material, the above-mentioned conventional example is
There were the following disadvantages. (1) In the case of double-sided image formation, the fixing oil adhered to the surface of the recording material during the surface image formation first adheres to the transfer material,
The fixing oil attached to the transfer material may be further transferred to the image carrier, and if the fixing oil adheres to the cleaning blade, it may be difficult to scrape off the residual toner on the image carrier. . (2) Similarly, in the case of double-sided image formation, if the image is formed with the fixing oil adhered on the surface of the image carrier,
There may be a problem in image formation.

Therefore, a first object of the present invention is to provide an image forming apparatus capable of preventing the fixing oil adhered to the surface of the recording material from adhering to the cleaning means during double-sided image formation.

A second object of the present invention is to provide an image forming apparatus capable of removing the fixing oil adhering to the surface of the image carrier during double-sided image formation.

[0007]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
An image carrier on which an electrostatic latent image is formed, a developing means for developing the electrostatic latent image, a transfer means for transferring the developed image to a recording material, and a transfer means for transferring the developed image to the recording material. A cleaning unit for removing the developer remaining on the image carrier, and a unit for removing residual oil on the surface of the image carrier between the transfer unit and the cleaning unit. The image forming apparatus.

The developing means forms a developed image of a plurality of colors on the image carrier by using a developer of a plurality of colors, and transfers the developed image to the recording material held by the transfer means a plurality of times. Therefore, it is preferable to form a multicolor image.

An image carrier on which an electrostatic latent image is formed, developing means for developing the electrostatic latent image formed on the image carrier, and transfer for transferring the developed image onto a recording material. A cleaning means for removing the developer remaining on the image carrier without being transferred by the transfer means,
A fixing unit for fixing the transfer image to a recording material,
An oil removing unit that removes oil adhering to the surface of the image carrier that runs between the transfer unit and the cleaning unit; a unit that holds the image-recorded recording material in the main body of the image forming apparatus; Means for making the back surface of the image-formed recording material held in the apparatus main body the image forming surface of the recording material, and performing the same operation as the image formation on the back surface of the image-formed recording material. Thus, there is provided an image forming apparatus having a means for forming an image on both sides of a recording material.

The oil removing means comes into contact with the image carrier only after double-sided image formation, and the oil adhered to the surface of the recording material by the fixing means is further adhered to the surface of the member of the transfer means. It is preferable to transfer the toner to the image carrier and operate so as not to adhere to the cleaning means. In the oil removing unit, the oil removing member is brought into contact with the image carrier only once when the recording material passes through the transfer unit and then the recording material is sent to the paper discharge unit during double-sided image formation. It is preferable.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

First Embodiment A first embodiment according to the present invention will be described with reference to FIGS. 1 and 2. In the full-color copying machine which is the full-color image forming apparatus shown in FIG. 1, a photosensitive drum 2 which is an image carrier is rotatably supported in the copying machine main body in the direction of the arrow, and an image described below is provided around the photosensitive drum 2. Forming means are arranged,
An image forming process is performed.

The photosensitive drum 2 is uniformly charged by the primary charger 3, and is irradiated with an optical image color-separated by an exposing means (not shown) such as a laser beam exposing device or the like, or an optical image corresponding thereto. An electrostatic latent image is formed on the peripheral surface of the photosensitive drum 2. A developing device 4 applies a developer (toner) to the electrostatic latent image to form a visible image, that is, a toner image.

The developing device 4 is equipped with four developing devices 4M, 4C, 4Y and 4Bk which respectively store four color toners of magenta, cyan, yellow and black. The developing device 4 develops the electrostatic latent image formed on the photosensitive drum 2 by bringing a desired developing device into contact with and away from the outer peripheral surface of the photosensitive drum 2. The toner image formed on the photosensitive drum 2 is transferred to a transfer material P, which is a recording material, which is carried by a transfer device 5 (hereinafter referred to as “transfer drum 5”) described later and conveyed in the arrow direction.

The toner remaining on the photosensitive drum 2 after image transfer is collected by the cleaning device 7 arranged on the downstream side in the drum rotation direction.

The transfer drum 5 has a transfer sheet 8 adhered to the outer peripheral surface thereof, and has a transfer material adsorbing means for adsorbingly holding the transfer material P on the transfer sheet 8 inside. The transfer material adsorbing means includes an adsorbing charger 9 for applying an electric charge having a characteristic opposite to that of the toner image on the photosensitive drum 2 to the opposite side of the transfer sheet 8, and a conductive roller 10 provided outside the transfer drum 5.
Having. The conductive roller 10 is grounded, serves as an opposite electrode of the attraction charger 9, and also serves to inject charges into the transfer material P and electrostatically attract the transfer material P to the transfer sheet 8.

Further, inside the transfer drum 5, a transfer charger 11 is provided at a position corresponding to a pressure contact position with the photosensitive drum 2 to apply a charge having a polarity opposite to that of the toner to the transfer sheet 8. Further, inside and outside the transfer drum 5, a pair of AC corona dischargers 12 and 13 facing each other with the transfer sheet 8 sandwiched therebetween are provided in order to weaken the adsorption force of the transfer material P after the image transfer to the transfer sheet 8. There is. Also AC corona discharger 1
A separating claw 14 is provided on the downstream side of the transfer drums 5 in the rotational direction of the transfer drum 5. Outer AC corona discharger 1
AC corona discharger 15 is provided adjacent to 3,
The AC corona discharger 15 is provided to prevent image disturbance due to peeling discharge that occurs when the transfer material and the transfer sheet 8 are separated.
Perform C corona discharge.

The transfer material P contained in the cassette 16 is fed one by one from the uppermost transfer material P by the pickup roller 17, and is synchronized with the toner image formed on the photosensitive drum 2 by the registration roller pair 18. Be transported. Then, when the transfer material P conveyed to the transfer drum 5 passes between the conductive roller 10 and the adsorption charger 9, the transfer material P is adsorbed and held on the transfer sheet 8 attached to the outer peripheral surface of the transfer drum 5 and conveyed. The toner image is transferred onto the transfer material P by the transfer charger 11 when the transfer drum 5 and the photosensitive drum 2 are pressed against each other. The transfer material P after the image transfer is conveyed while being carried on the transfer drum 5, and the adsorbing force is weakened when passing through the AC corona dischargers 12 and 13, and the separation claw 14 causes the transfer material P to be transferred from the transfer sheet 8 on the transfer drum 5. To be separated.

The transfer material P after separation is conveyed to the downstream side by the conveyor belt 19, and the toner image is heated and fixed when passing between the fixing roller 20 and the pressure roller 21. Then, at the time of single-sided image formation, the transfer material P after the image fixing is discharged to the discharge tray 23 outside the apparatus by the discharge roller pair 22.

During double-sided image formation, the transfer material P after image fixing is temporarily stored in the double-sided cassette 24 in the apparatus by the discharge roller pair 22 '. The transfer materials P temporarily stored in the double-sided cassette 24 are again fed one by one from the uppermost one by the double-sided cassette pickup roller,
The image forming operation as described above is repeated to form an image on the back surface.

During double-sided image formation in this embodiment,
After transfer to the back surface of the transfer material P, the transfer material P is transferred from the transfer drum 5.
When the fixing oil on the surface of the transfer material P adhering to the transfer drum 5 is transferred onto the photosensitive drum 2 after the separation, the oil removing means 6 removes the oil on the photosensitive drum 2 before it reaches the cleaning device 7. Remove the oil.

The oil removing means 6 is, as shown in FIG.
An unwinding roll 25 around which the oil-adsorbing web W is wound, a take-up roller 26 around which the web W unwound from the unwinding roll 25 is wound, a metal rod 27 for pressing the web W against the photosensitive drum 2, And a solenoid 28 for bringing the metal rod 27 into and out of contact with the photosensitive drum 2.

At the time of double-sided image formation, the toner image is transferred onto the transfer material P.
After the transfer material P is transferred to the back surface and the transfer material P is separated from the transfer drum 5, the solenoid 28 is operated to press the metal rod 27 against the photosensitive drum 2 and the web W removes oil from the image carrier. After that, when the photosensitive drum 2 makes one rotation, the metal rod 27 is separated from the photosensitive drum 2.

As described above, the oil adhering to the photosensitive drum can be removed during double-sided image formation.

Second Embodiment Next, a second embodiment of the oil removing means according to the present invention will be described with reference to FIG.

The oil removing means 60 of this embodiment includes an oil removing roller 31 in which an oil absorbing member 29 having an oil absorbing property is wound around a metal rod 30 which can be swung and rotated, and the oil removing roller 31 is close to the photosensitive drum 2. It is provided with a solenoid 32 for separating and an oil suction member 33 for sucking the oil that has soaked into the oil suction member 29.

During double-sided image formation, after the transfer material P is separated from the transfer drum 5 after the transfer to the back surface of the transfer material P, the solenoid 32 is operated to press the oil removing roller 31 against the photosensitive drum 2 and Remove the oil on top.
After that, when the photosensitive drum 2 makes one rotation, the oil removing roller 31 is separated from the photosensitive drum 2.

Next, the oil that has permeated the oil absorbing member 29 is sucked by the oil suction member 31, and the oil removing roller 31 is prepared for the next oil removing step.

As described above, by using the roller instead of the web of the first embodiment and further including the oil suction member, it is possible to obtain a long service life.

[0030]

As is apparent from the above description, according to the present invention, when a double-sided image is formed by providing a means for removing the residual oil on the surface of the image carrier between the transfer means and the cleaning means. Only, the fixing oil transferred to the surface of the image bearing member can be removed by the oil removing unit before the oil reaches the cleaning unit, and the fixing oil attached to the surface of the recording material can be cleaned. The fixing oil can be prevented from adhering to the means, and the fixing oil adhering to the surface of the image carrier can be removed. Therefore,
It is possible to maintain the cleaning performance of the surface of the image bearing member, prevent the image from being disturbed due to the transfer of the fixing oil to the surface of the image bearing member, and obtain a good image.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus in which the present invention is implemented.

FIG. 2 is an explanatory view showing Embodiment 1 of the oil removing means according to the present invention.

FIG. 3 is an explanatory diagram showing Embodiment 2 of the oil removing means according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color copying machine (image forming apparatus) 2 Photosensitive drum (image carrier) 4 Developing device (developing means) 5 Transfer device (transfer means) 6 Oil removing means 7 Cleaning means 20 Fixing roller (fixing means) P Transfer material (received material) Recording material)

Claims (5)

[Claims] 1. An image carrier on which an electrostatic latent image is formed, developing means for developing the electrostatic latent image, transfer means for transferring the developed image onto a recording material, and the transfer means. And a cleaning means for removing the developer remaining on the image carrier without being transferred by means of a cleaning means, and a means for removing the residual oil on the surface of the image carrier between the transfer means and the cleaning means. An image forming apparatus characterized by the above. 2. The developing means forms a developed image of a plurality of colors on the image bearing member by using a developer of a plurality of colors, and the developed image is rotated a plurality of times on the recording material held by the transfer means. The image forming apparatus according to claim 1, wherein a multicolor image is formed by copying. 3. An image bearing member on which an electrostatic latent image is formed, developing means for developing the electrostatic latent image formed on the image bearing member, and for transferring the developed image to a recording material. Transfer means, cleaning means for removing the developer remaining on the image carrier without being transferred by the transfer means, fixing means for fixing the transferred image to a recording material, and Means for removing the oil adhering to the surface of the image carrier running between the image forming means and the cleaning means, means for holding the image-formed recording material in the image forming apparatus body, and the image forming apparatus body Means for using the back surface of the image-formed recording material held therein as an image forming surface of the recording material, and performing a similar operation to the image formation on the back surface of the image-formed recording material. Form images on both sides of recording material An image forming apparatus having means. 4. The oil removing means contacts the image carrier only after double-sided image formation, and the oil adhered to the surface of the recording material by the fixing means further adheres to the member surface of the transfer means. The oil is transferred to the image carrier,
The image forming apparatus according to claim 3, wherein the image forming apparatus operates so as not to adhere to the cleaning unit. 5. The oil removing means applies oil to the image bearing member only once when the recording material passes through the transferring means and then the recording material is sent to a paper discharge portion during double-sided image formation. The image forming apparatus according to claim 3, wherein the removing member abuts.