JPH07281572A - Image forming device - Google Patents

Abstract

PURPOSE:To always stably perform excellent cleaning regardless of environment, image density or jamming after an initial use by changing an abutting angle of a cleaning blade to the image carrier. CONSTITUTION:Transfer material P is carried to a fixing part after it is separated from the image carrier 1 after transfer, and residual toner which is not transferred to the transfer material P at the time of the transfer and remains on the image carrier 1 is scraped at the time of reaching the position of the cleaning blade 9 attached to a cleaning device 9a and abutting, in a counter direction at the angle theta, on the surface of the image carrier 1 with the rotation of the carrier 1. The cleaning device 9a is operationally connected to the counter 10 counting the number of copied sheets of a device main body, and changes the abutting angle theta on the image carrier 1 of the cleaning blade 9 by a signal from the counter 10. Thus, the angle theta is maintained to be small in the beginning of the use start of the device main body, and the angle theta is successively changed to be large in accordance with the increase of the number of copied sheets.

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 utilizing an electrostatic transfer process such as an electrostatic copying machine and a dynamic printer.

[0002]

2. Description of the Related Art In a known image forming apparatus including a step of transferring a toner image formed on an image carrier as described above to a transfer material such as paper, the image carrier side is used for transfer. It is difficult to transfer all the toner of (1) to the transfer material, and it is inevitable that some of the toner remains on the image carrier as residual toner.

Therefore, a cleaning means for removing the residual toner on the image carrier is an essential requirement. As this kind of cleaning means, various things such as a fur brush, a cleaning web, and a cleaning blade have been proposed, but those using a cleaning blade are simple in structure, do not require a small space, and are advantageous in terms of cost,
It is well known that it is widely used because of its excellent toner removing action.

The cleaning blade as a cleaning means is arranged so that one sharp edge of the blade is opposed to the running direction of the image carrier with respect to the running direction of the image carrier which is usually formed in a rotating cylindrical shape. It is usually constructed such that the residual toner is removed by abutting (counter system).

In such a method, of course, the friction between the image carrier and the blade edge becomes large, and this tendency is particularly large immediately after the start of use of the apparatus. For this reason, when the device is started, lubricant is applied to the blade edge portion to start smoothly, but this uneven application of lubricant and peeling of the lubricant cause excessive friction. The blade may be turned over, which may cause toner to slip through or deteriorate image quality.

Further, after the start of use, the toner supplied at the developing portion remains in the blade edge portion in a small amount and acts as a lubricant to contribute to a smooth cleaning action. However, when continuously forming images with low toner consumption, the amount of toner staying at the blade edge may be insufficient, and the same situation as in the above case may occur.

The present invention has been made in view of the above circumstances, and in an image forming apparatus provided with a cleaning blade that abuts like an image carrier, the contact angle of the cleaning blade with respect to the image carrier is changed. Accordingly, it is an object of the present invention to provide an image forming apparatus that can always perform good cleaning while avoiding the problems described above.

[0008]

[Constitution of the invention]

In order to achieve the above object, the present invention provides an image forming apparatus having a cleaning blade that comes into contact with an image carrier, wherein the cleaning blade contacts the image carrier. In an image forming apparatus comprising a means for changing the contact angle of contact, or comprising a cleaning blade contacting the image carrier, the contact angle at which the cleaning blade contacts the image carrier is In the image forming apparatus, the cleaning blade is provided with a means for changing the image forming operation such that the image forming operation becomes larger as the image forming operation proceeds from the start of use, or the cleaning blade is in contact with the image carrier. The contact angle of contact with the image carrier is changed so that it becomes smaller when a jam occurs. Or an image forming apparatus having a cleaning blade that contacts the image carrier, the contact angle at which the cleaning blade contacts the image carrier is such that a predetermined number of low-density images are continuously formed. In an image forming apparatus having a cleaning blade that comes into contact with the image carrier, or a contact angle of the cleaning link that contacts the image carrier when formed, But,
The image forming apparatus is provided with a unit for changing the size to be small when a predetermined number of sheets are continuously formed in a high humidity environment.

With such a structure, good cleaning can always be stably performed from the beginning of use of the image forming apparatus, irrespective of the environment, image density, jam, and the like.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic side view of an image forming apparatus showing an embodiment of the present invention. A cylindrical image carrier 1 having an axis in the direction perpendicular to the plane of the drawing and running in the direction of reference numeral R1.
The surface photosensitive layer is uniformly charged by applying a charging bias from the charging power source 3 via the contactor 3a.

An image signal 5 is projected on the charging surface to form an electrostatic latent image, and when the latent image reaches a developing portion where a developing device 6 is provided opposite to the image carrier 1, the developing device 6 is formed. The latent image is visualized by the toner supplied from the toner to form a toner image.

Further, when the toner image reaches the transfer portion where the transfer roller 7 is provided opposite to the image carrier 1, the transfer material P reaches the transfer portion by this time, and the transfer bias is applied to the transfer roller. Is applied, and the toner image on the image carrier side is transferred to the transfer material P by the action of the electric field formed.

After the transfer, the transfer material P is assumed to be conveyed away from the image carrier to a fixing portion (not shown), and the residual toner remaining on the image carrier without being transferred to the transfer material at the time of transfer is not transferred to the image carrier. As it rotates, it is mounted on the cleaning device 9a,
The cleaning blade reaches the position of contact with the surface of the image carrier 1 at the angle θ in the counter direction, and is scraped off by this, and the image carrier is ready for the next image forming operation.

In such an image forming apparatus, in the apparatus shown in the figure, the cleaning apparatus 9a is constructed so as to be rotatable around an axis line in the direction perpendicular to the paper surface (not shown), and counts the number of copies of the apparatus main body. Counter 1
0 is operatively connected. Of course, it is possible to rotate only the cleaning blade 9 instead of the cleaning device itself. This makes counter 1
A contact angle θ of the cleaning blade 9 to the image carrier can be changed by a signal from 0.

With this configuration, the angle θ is kept small at the beginning of use of the apparatus main body, and the angle θ is gradually increased as the number of copies increases. In this way, at the beginning of use, the angle θ is reduced to increase the slip between the image carrier surface and the blade edge, and the blade is turned over while maintaining the cleaning function,
This prevents toner from slipping through and deterioration of image quality.

Further, as the number of copies progresses, the angle θ is successively increased until a certain number of copies is made, and good cleaning is performed by utilizing the lubricating action of the toner existing at the blade edge portion, and thereafter. A constant contact angle shall be maintained.

FIG. 2 shows the relationship between the number of copies and the contact angle θ of the cleaning blade with the image carrier in the above-mentioned image forming apparatus. The initial contact angle is 25 degrees. The case is shown in which the contact angle is set to 50 degrees when the number of copies is 100, and the contact angle is set to 50 degrees when the number of copies is 1000, and thereafter the angle is kept constant.

With such a structure, it is possible to preferably prevent the blade from turning over and the toner from slipping off without applying a lubricant to the blade edge at the beginning of use.

FIG. 3 is a schematic side view of an image forming apparatus showing another embodiment. Its basic name structure is the same as that shown in FIG. 1 and the same reference numerals are given to corresponding parts. They are attached and shown, and description thereof will be omitted.

A case will be described in which a large amount of toner arrives at the cleaning portion due to a jam and the toner slips by the apparatus shown in the figure. In the illustrated apparatus, the cleaning device 9a to the cleaning blade 9
Is rotatable and is linked to the jam detection device 11.

When a jam occurs, the detection device 11 detects it and sends a signal to the drive portion of the cleaning device,
Rotate the cleaning blade 9 in the direction of θ _{2 in} the drawing,
The contact angle of the blade 9 with the image carrier is increased to prevent the toner from slipping through. It should be noted that the above-mentioned change of the angle is carried out temporarily, and the cleaning blade is brought into contact with the cleaning blade in a timely manner such as temporarily stopping and restarting the apparatus main body for jam clearance, after a predetermined time set in consideration of these. It is preferable to restore the angle to the old position.

FIG. 4 is a schematic side view of an image forming apparatus showing still another embodiment. The basic construction is the same as that of each of the above-mentioned embodiments. It is assumed that the cleaning device 9a and the cleaning device 9a are interlocked with each other so that the cleaning device 9a is rotated by an output signal of the image density detection device 12 provided.

When low-concentration image formation with low toner consumption is continuously performed, the toner staying at the blade edge is insufficient, and the toner cannot be expected to have a lubricating action. I have already said a word about what happens.

The apparatus according to the present embodiment copes with such a situation. When a predetermined number of low-density images below a certain level are continuously formed, the density detecting device 12 detects this and the signal thereof is detected by the cleaning device. 9a, and the cleaning device is rotated in the θ ₁ direction in the figure to reduce the contact angle of the cleaning blade with the image carrier to prevent the blade from curling. Also in this case, it is preferable that the contact angle of the blade 9 is restored to the old position when the image density is restored.

FIG. 5 is a schematic side view of the image forming apparatus showing an embodiment suitable for a high humidity environment. Under a high-humidity environment, the cleaning blade absorbs moisture and tends to adhere to the image bearing member, so that the blade is likely to be turned over.

In order to cope with such a situation, in this device, the humidity detecting device 13 is replaced by the cleaning device device 9.
It is interlocked with a. When continuous copying is performed in a high humidity environment and the humidity is detected, the cleaning device 9 is rotated in the θ ₁ direction by this information to reduce the contact angle of the blade 9 with the image carrier, This shall prevent the blade from turning over.

As described above, the cases of initial operation, low density image formation, jam occurrence, and high humidity environment have been described. When two or more of these occur at the same time, the individual means described above are applied at the same time. It goes without saying that you can also do it.

[0029]

As described above, according to the present invention,
In an image forming apparatus equipped with a cleaning blade, by varying the contact angle of the cleaning blade to the image carrier, the blade can be turned up during initial operation, when a jam occurs, when forming a low-density image, or when the humidity is high. It is possible to effectively prevent the occurrence of toner, slipping of toner due to this, and deterioration of image quality, and it is possible to always perform stable and good cleaning of the image carrier from the beginning of operation, which greatly contributes to obtaining a high-quality image. Is.

[Brief description of drawings]

FIG. 1 is a schematic side view of an image forming apparatus showing an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the number of copies and the contact angle of the cleaning blade with the image carrier, as described above.

FIG. 3 is a schematic side view of an image forming apparatus showing another embodiment.

FIG. 4 is a schematic side view of an image forming apparatus showing another embodiment.

FIG. 5 is a schematic side view of an image forming apparatus according to another embodiment.

[Explanation of symbols]

 1 image carrier 2 charging roller 5 image signal 6 developing device 7 transfer roller 9 cleaning blade 10 copy counter 11 jam detection device 12 image density detection device 13 humidity detection device

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[Procedure amendment]

[Submission date] February 13, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

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

Claims (5)

[Claims] 1. An image forming apparatus comprising a cleaning blade that comes into contact with an image carrier, the image forming apparatus including means for changing a contact angle at which the cleaning blade comes into contact with the image carrier. 2. An image forming apparatus comprising a cleaning blade that comes into contact with an image carrier, wherein the contact angle at which the cleaning blade comes into contact with the image carrier is such that the image forming operation is performed from the start of use of the image forming apparatus. An image forming apparatus provided with a means for changing the size so that it becomes larger as the process proceeds. 3. An image forming apparatus comprising a cleaning blade that contacts an image carrier, wherein a contact angle at which the cleaning blade contacts the image carrier is changed to be small when a jam occurs. An image forming apparatus provided with a means for causing it. 4. An image forming apparatus comprising a cleaning blade that contacts an image carrier, wherein a contact angle at which the cleaning blade contacts the image carrier is such that when a predetermined number of low-density images are continuously formed. , An image forming apparatus having means for changing the size to be small. 5. An image forming apparatus comprising a cleaning blade which comes into contact with an image bearing member, wherein a contact angle of the cleaning link blade which comes into contact with the image bearing member is such that a predetermined number of sheets are continuously formed in a high humidity environment. , An image forming apparatus having means for changing the size to be small.