JPH0695448A - Image forming device - Google Patents

Abstract

PURPOSE:To facilitate blade replacement, to prevent, even after the replacement of the old blade with a new one, the curling up of the new blade, and to prevent failure of cleaning caused by the damage of the blade. CONSTITUTION:A blade replacement operation circuit 13a incorporated in a control means 13 carries out the rotation of a photosensitive drum when a support-shaft moving means 21 incorporated in a cleaning unit 11 reaches a blade replacing position a development unit, etc., is operated to replace the blade, and the toner is attached to the periphery of the photosensitive drum. At this time, a support-shaft rotating means 20 is driven to replace the old blade with the new one 18. Subsequently the support-shaft moving means 21 moves to a blade abutting position to press firmly the new blade 18 against the photosensitive drum. The photosensitive drum is redriven in this state, and toner is attached to the new blade 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which uses a blade to clean residual toner adhering to an image bearing member, and more particularly to a new blade after the replacement, to which toner is attached to cause friction resistance with the image bearing member. An image forming apparatus having a means for reducing

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copying machine, a toner image formed on the surface of a photosensitive drum is not completely transferred to a transfer paper, and untransferred toner remains. In order to continuously perform copying work, it is necessary to completely remove and clean this residual toner with a cleaning member. As the cleaning member, a blade made of an elastic material such as polyurethane is often used. This is a structure in which the edge of the blade is brought into contact with the photosensitive drum to scrape off the residual toner, but in order to prevent cleaning failure due to edge wear, it is necessary to periodically replace with a new blade.

In a conventional image forming apparatus, for example, a cleaning unit replaced by a new blade by an operator is set on a photosensitive drum at the time of maintenance for completing the copying of 150,000 copies. However, if the new blade and the cleaned photoconductor drum are directly contacted with each other, the frictional resistance may be too large and the blade may be damaged.Therefore, the operator may sprinkle the setting powder on the blade or even the photoconductor drum. Toner was attached to reduce mutual frictional resistance.

[0004]

However, exchanging the blades accompanying these additional operations is a complicated task because it is necessary to adjust the photosensitive drum, the developing unit, and the cleaning unit, respectively.

Further, if the replacement work is performed for each blade, the replacement cycle becomes too short. Therefore, the conventional image forming apparatus is disclosed in, for example, Japanese Patent Laid-Open Nos. 51-32335 and 5-5.
8-687776, JP-A-61-103180, JP-A-55-12241, JP-A-60-68.
A device having a plurality of blades as described in Japanese Patent No. 571, etc. has been proposed. These have adopted a configuration in which a blade support shaft for fixing a plurality of blades is rotated for a predetermined work or at a predetermined time and replaced with another blade.

However, if the blade is automatically replaced, the blade may be damaged due to the frictional resistance between the new blade and the photosensitive drum as described above.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which simplifies the blade replacement work and does not cause the blade to be turned over even if it is replaced with a new blade. There is.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a drive unit for rotating an image carrier, a developing unit for adhering toner to the image carrier, and a post-transfer device. A replaceable blade for scraping off the toner remaining on the peripheral surface of the image carrier, and a blade moving means capable of moving the blade between a blade contact position and a blade separated position with respect to the image carrier, In an image forming apparatus having a blade moving means, a drive means and a control means for controlling the operation of the developing unit, the control means, when replacing a used blade with a new blade at the blade separation position, While rotating the image carrier, the developing unit is operated to adhere the toner to the entire peripheral surface of the image carrier, and the blade moving means is operated to operate the new block. A blade replacement operation circuit that moves the blade to the blade contact position, slides the new blade on the toner adhering to the image carrier, and then moves the new blade to the blade separation position. It has a feature.

An image forming apparatus according to a second aspect is the image forming apparatus according to the first aspect, wherein the blade is a plurality of blades fixed to a rotatable blade support shaft, and the blade moving means is the blade. It is characterized by comprising a blade exchange mechanism for rotating the support shaft and exchanging the one blade abutting on the image carrier for another blade.

[0010]

According to the invention of claim 1, based on the blade replacement operation circuit of the control means, when the used blade is replaced with a new blade at the blade separating position, the developing unit is rotated while the image carrier is rotated by the driving means. The toner is attached to the entire peripheral surface of the image carrier by operating. On the other hand, actuating the blade moving means to move the new blade to the blade contact position,
The toner is brought into contact with the image carrier. In this state, the image carrier is rotated. Since the toner adheres to the new blade, the frictional resistance between the image carriers is reduced. After that, the new blade is moved to the blade separating position.

In the image forming apparatus according to the second aspect of the present invention, a plurality of blades fixed to the blade support shaft are rotated by a blade exchanging mechanism to exchange the blade contacting the image carrier with another blade. At this time, the developing unit adheres toner to the entire peripheral surface of the image bearing member, and the new blade rotated and replaced comes into contact with the toner and slides.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image forming apparatus of the present invention will be described below with reference to the accompanying drawings. 1 is a schematic configuration diagram of a copying machine as an image forming apparatus, FIG. 2 is a schematic configuration diagram of a transfer processing unit of the copying machine, FIG. 3 is a front sectional view of a cleaning unit, and FIG.
FIG. 4 is a sectional view showing a section taken along line IV-IV in FIG. 3.

The copying machine 101 has a main body 102 and a paper feed unit 103 connected to the main body 102, each of which is provided with a paper feed stage. Inside the paper feeding unit 103 and main body 1
A plurality of paper feed stages 104 are provided in the printer 02, and the transfer paper 105 is accommodated in each of them. Transfer paper 1 of each paper feed stage 104
Paper feed rollers 106 are arranged on the upper surface of 05, respectively, to transfer the transfer paper 105 intermittently. Each paper feed roller 106
The multi-feed preventing means 107 is also provided on the transfer paper 10
5 is sent to the next process one by one. Each paper feed stage 104
The transfer papers 105 sent out from the respective guide plates 10
The second sheet feeding section 1 which is guided to 8 and is built in the main body section 102.
It is delivered to 09. The second paper feeding unit 109 is arranged immediately before the transfer processing unit 1, and has a loop roller 110 and a registration roller 111.

On the other hand, in the photoconductor 2 which constitutes the transfer processing section 1, uniform charging is applied by the charging electrode 3 and the light source 1
Reflected light obtained by irradiating the original 114 on the original placing glass 113 by 12 irradiates the peripheral surface of the photoconductor 2 as an image bearing member via the mirror 115 and the lens mechanism 116 to form an electrostatic latent image. To form. This electrostatic latent image is developed by the developing unit 5 to form a toner image. The registration roller 111 is driven in synchronization with the rotation of the photoconductor 2 to send the transfer paper 105 to the transfer electrode 7 and the separation electrode 8 to transfer the toner image.
After that, the transfer paper 105 is separated from the photoconductor 2 by the separation claw 9, placed on the transport unit 117, and transported to the fixing unit 118 in the next step. A cleaning unit 11 is arranged around the photoconductor 2 on the downstream side of the separation claw 9.
After the transfer, the surface of the photoconductor 2 is cleaned and charged again by the charging electrode 3 for the next image formation.

The transfer paper 105 heated and pressurized in the fixing unit 118 fixes the toner image, and in the case of one-sided copying, it is sandwiched by the carrying roller 119 and sent to a paper discharge tray (not shown). When performing double-sided copy, the transfer roller 119 sends the copied transfer paper 105 to the saving transfer path 121 connected to the stacker 120 for temporarily saving the copy. The transfer paper 105 temporarily retracted into the stacker 120 is re-fed out and carried into the second paper feed unit 109 via the horizontal transport path 122.

Next, details of the transfer processing unit 1 will be described with reference to FIG. The transfer processing unit 1 of this copying machine includes a charging electrode 3 and a charging erasing unit (CE) around a photoconductor 2 which constitutes an image carrier.
L) 4, developing unit 5, pre-transfer exposure unit (PTL) 6,
Transfer electrode 7, separation electrode 8, separation claw 9, pre-cleaning static eliminator (PCC) 10, cleaning unit 11,
Then, the pre-charge exposure unit (PCL) 12 is arranged in order.
These are connected to the control means 13 built in the main body 102 of the copying machine 101 to control a series of operations to continuously perform the transfer process.

In the transfer processing section 1, a uniform + charge is applied to the surface of the photoconductor 2 by the action of the charging electrode 3, and then the reflected light obtained by illuminating the original by a light source (not shown) is reflected by the mirror 11.
The peripheral surface of the photoconductor 2 is irradiated with the light via the light source 5 or the like to remove the charge corresponding to the light and shade of the document to form an electrostatic latent image. The electrostatic latent image formed by the + charge is developed by the toner having the −charge in the developing unit 5, and a toner image is formed on the surface of the photoconductor 2. In order to prevent the toner from adhering to the non-image portion in this developing process, the charge erasing portion 4 arranged upstream of the developing unit 5 irradiates light according to the paper size to change the surface potential of the non-image portion of the photoconductor 2. It has been deleted in advance.

The pre-transfer exposure unit 6 irradiates the formed toner image with light to reduce the potential of the latent image and reduce the force with which the latent image attracts toner. When + charges are applied to the back surface of the transfer paper 105 fed along the guide plate 108 in synchronization with the rotation of the photoconductor 2 by the transfer electrode 7, the toner on the peripheral surface of the photoconductor 2 is transferred to the transfer paper 105. When the transfer paper 105 on which the toner image has been transferred is discharged by the discharge of the separation electrode 8, the attraction force with the photoconductor 2 decreases, and eventually it is naturally separated by its own weight and guided to the separation claw 9 to complete the separation. Then, it is sent to the fixing unit 118.

On the other hand, since the untransferred toner remains on the photoconductor 2 passing through the separation claw 9, the pre-cleaning charge eliminating section 10 discharges the residual toner in the same manner as the separation electrode 8, and the toner is removed. And, the electric charge of the photoconductor 2 is erased. The residual toner from which the electric charge has been erased is scraped off by the cleaning unit 11, and the cleaned photoconductor 2 receives uniform light at the pre-charging exposure unit 12 to erase / uniformize the residual potential,
Prepare for the next charge.

Next, the structure of the cleaning unit 11 will be described in detail with reference to FIGS. The cleaning unit 11 has a cleaning unit 15, a sponge roller 16, and a toner conveying unit 17 inside and outside the housing 14, and a blade 18 included in the cleaning unit 15 is pressed against the peripheral surface of the photoconductor 2 to remove residual toner. It is scraped off, placed on the sponge roller 16, and dropped onto the feed screw 17a of the toner conveying means 17. The feed screw 17a sends the toner to the developing unit 5 again via a path (not shown) or collects it in a collection box (not shown) and discards it.

The cleaning means 15 includes a blade support shaft 19 for fixing a plurality of blades 18, and a support shaft rotating means 20 for rotating the blade support shaft 19 in a predetermined direction.
The blade support shaft 19 has a support shaft moving unit 21 that contacts or separates from the photosensitive member 2.

The blade 18 is sandwiched and fixed by a blade holder 18a composed of two L-shaped cross-section metal fittings, and is rotatably attached to a blade support shaft 19 using a support pin 18b. In this embodiment, the two blades 18 are attached to the blade support shaft 19 at symmetrical positions, but the present invention is not limited to this.

The blade support shaft 19 is a support shaft moving means 21.
Of the two holder side plates 22 of the shaft holder 22 forming a part of
It is rotatably supported by a and 22a. Shaft holder 22
Has a holder top plate 22b and a holder back plate 22c which are continuous with the holder side plate 22a, and two pressure release shafts 23, 23 project from both sides of the holder top plate 22b. The pressure release shafts 23, 23 are provided on both side plates 14a of the housing 14,
It is rotatably supported by 14a. Also the holder back plate 2
The weight plate 24 is locked to the shaft 2c.
A rotation moment about the pressure release shaft 23 is applied to the blade 2 and the blade support shaft 19, and the tip of the blade 18 is adjusted so as to contact the surface of the photoconductor 2 with a certain pressure.

One end of the pressure release shaft 23 has a side plate 14a.
And is connected to a cam mechanism 25 forming a part of the support shaft moving means 21. The cam mechanism 25 includes an arm 26 fixed to the end of the pressure release shaft 23 and constituting a follower,
A cam 27 that moves the arm 26 up and down to rotate the crimp release shaft 23, a driven gear 28 that transmits a rotational force to the cam 27 via the shaft 27a, and a drive that connects to the driven gear 28 via an idle gear 29. It has a gear 30 and a drive motor 31 that transmits a rotational force in a predetermined direction to the drive gear 30. The drive motor 31 is a control means 13 built in the copying machine.
The support shaft moving means 21 is driven under the control of, and the support shaft moving means 21 and the blade 18 are selectively moved in three stages of a blade contact position, a cleaning release position, and a blade replacement position. There is.

Further, as shown in FIG. 2, the blade replacement operation circuit 13a built in the control means 13 has a drive source (not shown) for charging the photosensitive member 2 when the support shaft moving means 21 reaches the blade replacement position. Electrode 3, charge eraser (CEL)
4, developing unit 5, pre-transfer exposure unit (PTL) 6, cleaning unit 11, and pre-charge exposure unit (PCL)
Each 12 operates for blade replacement.

Next, the structure of the support shaft rotating means 20 for rotating the blade support shaft 19 in a predetermined direction to replace the blade will be described. A blade replacement spring 33 is wound around one end of the blade support shaft 19 protruding from the holder side plate 22a of the shaft holder 22 toward the inner surface of the side plate 14a of the housing 14, and the rotation of the blade support shaft 19 is controlled at its tip. The ratchet 34 is fixedly installed. The ratchet 34 has the same number of notches 32 as the number of blades 18,
In this embodiment, two notches 32 corresponding to the two blades 18 are provided. The holder side plate 22a is provided with a ratchet pawl 35 that fits into the notch 32. Due to the existence of the ratchet 34 and the ratchet pawl 35, it becomes possible to rotate the blade support shaft 19 only when the support shaft moving means 21 is in the blade separation position.

The blade replacement spring 33 constituting the support shaft rotating means 20 needs elasticity to rotate the blade support shaft 19 for fixing the two blades 18, but the elastic force is charged by an external force. To be done. For example, as in this embodiment, the wire 36 is attached to one end of the blade support shaft 19.
Etc. are wound and the wire 36 is pulled out to perform charging.

Next, the operation of the cleaning unit 11 will be described with reference to FIG. FIG. 5 is an explanatory diagram for explaining the operation of the shaft holder 22 and the blade support shaft 19 that rotate in conjunction with the cam mechanism 25. FIG. 5A shows the support shaft moving means 21.
Is in the blade contact position, FIG. 5 (b) is in the cleaning release position, and FIG. 5 (c) is in the blade replacement position.

When the power of the copying machine is turned on, the control means 1
3 operates to drive the drive motor 31 to bring the arm 26 and the cam 27 into a non-contact state, and the blade 18 is moved to the photoconductor 2
Crimp on. After the transfer process is completed and a predetermined time has passed,
The control means 13 rotates the cam 27 to bring it into contact with the arm 26 to rotate the pressure release shaft 23 and the shaft holder 22 connected thereto according to the rotation angle of the arm 26, and as shown in FIG. The blade 18 is separated from the photoconductor 2. In this embodiment, the rotation angle at the cleaning release position is about 7 degrees. At the cleaning release position, the toner, paper dust, etc. adhering to the blade 18 are shaken off.

Although the cleaning means 15 normally reciprocates between the cleaning release position and the blade contact position, when the blade 18 replacement time is reached, the control means 13 causes the cam 2 to move.
7 is further rotated to move to the blade replacement position. The rotation angle in this case is about 20 degrees (FIG. 5C).
At this blade replacement position, the support shaft rotating means 20 is operated to rotate the blade support shaft 19 in a predetermined direction, and the new blade 1
8, but at the same time the blade replacement operation circuit 13a
Is a drive source (not shown) for the photoconductor 2, a charging electrode 3, a charge erasing unit (CEL) 4, a developing unit 5, a pre-transfer exposure unit (PTL) 6, a cleaning unit 11, and a pre-charge exposure unit (PCL) 12. Operate for blade replacement.

These operations will be described based on the time chart shown in FIG. When the support shaft moving means 21 moves to the blade replacement position, the photoconductor 2 is rotated and the pre-charging exposure unit (PCL) 12 is turned on to erase / uniformize the residual potential, and then the charging electrode 3 is used to make it uniform. + Add charge. At the same time, the charge erasing unit (CEL) 4 irradiates light to erase the surface potential of the non-image portion of the photoconductor 2 in advance. Thereafter, on the peripheral surface of the photoconductor 2 to which the + charge is applied, the toner having the −charge is agitated in the driven developing unit 5 and is triboelectrically charged. At this time, the developing bias is also turned on to erase the background electric field. Then, the pre-transfer exposure unit (PTL) 6 irradiates light to lower the potential and reduce the adhesive force of the toner.

In this way, the toner is attached to the peripheral surface of the photoconductor 2, and the support shaft rotating means 20 is turned on to replace the new blade 18. Subsequently, the support shaft moving means 21 moves to the blade contacting position and presses the new blade 18 onto the photoreceptor 2. In this state, the photoconductor 2 is driven again to attach the toner to the new blade 18. After rotating the photoconductor 2 for one rotation or more, the support shaft moving means 21 is returned to the cleaning release position, and the blade replacement operation is completed.

In this embodiment, an example of an image forming apparatus in which a blade supporting shaft for fixing a plurality of blades is rotated and replaced with a new blade has been explained. The present invention is not limited to the above example as long as the toner is attached to the surface and the frictional resistance with a new blade is reduced, and a single blade for manual replacement may be used.

[0034]

As described above, according to the first aspect of the invention, the control means is provided with a blade replacement operation circuit for adhering toner to the entire peripheral surface of the image carrier and sliding a new blade on the toner. Therefore, it is possible to reduce the mutual frictional resistance without the need for the worker to sprinkle the setting powder on the blade or to attach the toner to the photosensitive drum each time the blade is replaced. Therefore, the blade replacement work can be simplified.

In the image forming apparatus according to the second aspect, even if the image forming apparatus automatically replaces a plurality of blades and replaces the blades with a new blade, the control means having the blade replacement operation circuit is provided. It is possible to provide an image forming apparatus in which the toner adhering work for reducing the frictional resistance can be automatically performed even if the blade is replaced with a new blade, and the new blade is not turned over, and therefore cleaning failure due to damage to the blade does not occur.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus.

FIG. 2 is a schematic configuration diagram of a transfer processing unit.

FIG. 3 is a front sectional view of a cleaning unit.

FIG. 4 is a sectional view showing a section taken along line IV-IV in FIG.

FIG. 5 is an explanatory view for explaining the action of a rotating blade support shaft and the like.

FIG. 6 is a time chart when a blade is replaced.

[Explanation of symbols]

 2 Photoreceptor 5 Developing Unit 11 Cleaning Unit 13 Control Means 13a Blade Replacement Operation Circuit 18 Blade 19 Blade Support Shaft 20 Support Shaft Rotating Means 21 Support Shaft Moving Means

Claims (2)

[Claims] 1. A drive unit for rotating an image carrier, a developing unit for adhering toner to the image carrier, and a replaceable blade for scraping off the toner remaining on the peripheral surface of the image carrier after transfer. A blade moving unit that can move the blade between a blade contact position and a blade separated position with respect to the image carrier; and a control unit that controls the operation of the blade moving unit, the driving unit, and the developing unit. In the image forming apparatus having the above, when the used blade is replaced with a new blade at the blade separation position, the control means operates the developing unit while rotating the image carrier to move the entire circumference of the image carrier. The toner is attached to the surface and the blade moving means is operated to move the new blade to the blade contact position, and the new blade is attached to the image carrier. An image forming apparatus comprising: a blade replacement operation circuit for moving the new blade to the blade separation position after sliding the new blade on the toner. 2. The image forming apparatus according to claim 1, wherein the blade is a plurality of blades fixed to a rotatable blade support shaft, and the blade moving means rotates the blade support shaft to carry out the image carrying operation. An image forming apparatus comprising a blade exchange mechanism for exchanging the one blade that comes into contact with a body with another blade.