JPH086441A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a machine body inside and a transfer member from getting dart and to prevent a cleaning member from turning by providing the partial forming means for forming developer image on the image carrier surface in the part excluding the part that the peeling member comes in contact with. CONSTITUTION:In order to prevent the cleaning blade 44a from turning, the belt-like toner image M formed on the surface of the photoreceptor drum 36, is formed in the part excluding the contact part C that the peeling pawl 42 comes in contact with, so as not to be formed on the contacting part C. Thus, the toner image M formed on the surface of the photoreceptor drum 36 is prevented from coming in contact with the peeling pawl 42 at the time of passing the peeling pawl 42, therefore prevented from being scraped off by the peeling pawl 42 and consequently prevented from soiling the body inside and the copying paper, and moreover the toner image M is sent corresponding to the rotation of the photoreceptor drum 36 and the toner is scraped off by the cleaning blade 44a. At this time, the toner forming the toner image M acts as lubricant for reducing the friction between the cleaning blade 44a and the photoreceptor drum surface, thus the cleaning blade 44a is prevented from turning.

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 such as a copying machine or a printer, and more particularly to an image forming apparatus provided with a cleaning member for cleaning the surface of an image bearing member and a peeling member for peeling a transfer material from the image bearing member. .

[0002]

2. Description of the Related Art An image forming apparatus, such as a copying machine, includes a photosensitive drum as an image carrier, and a charging charger, a developing device, a transfer charger, a peeling member, a cleaning device, and the like around the photosensitive drum. A static eliminator or the like is provided.

During image formation, the drum surface is uniformly charged by the charging charger, and an electrostatic latent image is formed on the drum surface by the exposure device. This electrostatic latent image is developed by a developing device using a developer, and the formed developer image is transferred to a copy sheet by a transfer charger. The copy sheet is peeled from the drum surface by a peeling claw serving as a peeling member that is in contact with the surface of the photoconductor drum, and then sent to the fixing device.

On the other hand, the cleaning device is equipped with a cleaning blade in contact with the surface of the photosensitive drum, and the developer remaining on the surface of the drum after transfer is scraped off from the surface of the drum by the cleaning blade.

When an image is formed again after a certain period of time has elapsed after the image forming operation is completed, the cleaning blade may turn up in the rotating direction of the drum due to friction with the surface of the photosensitive drum. If the cleaning blade is turned up in this way, the developer remaining on the surface of the photosensitive drum cannot be effectively removed, and it becomes difficult to form a clear image.

[0006]

Therefore, conventionally, before forming an image, a belt-shaped developer image extending in the axial direction of the drum is formed on the surface of the photosensitive drum, and the developer image is guided to the cleaning blade. By using the developer as a lubricant, the cleaning blade is prevented from being turned over.

However, in a device using a peeling claw that is in constant contact with the surface of the photosensitive drum as the peeling member,
The peeling claw is arranged between the transfer charger and the cleaning blade. Therefore, the strip-shaped developer image passes through the peeling claw before reaching the cleaning blade.

Therefore, when the strip-shaped developer image passes through the peeling claw, a part of the developer image is scraped off by the peeling claw, and is scattered on the inside of the apparatus and on the conveying path of the copy sheet. Therefore, there is a problem in that the inside of the machine body becomes dirty, and the copy paper becomes dirty due to the developer scattered on the transport path.

The present invention has been made in view of the above points, and an object thereof is to provide an image forming apparatus capable of preventing the cleaning member from being turned over without contaminating the inside of the machine body or the material to be transferred. .

[0010]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention comprises an image forming means for forming a developer image on an image bearing member, and the developer image as a transfer material. Transfer means for transferring and contacting the surface of the image carrier,
A peeling member for peeling the transfer material to which the developer image is transferred from the surface of the image carrier, and a cleaning blade in contact with the surface of the image carrier, and removes the developer remaining on the surface of the image carrier after transfer. The image forming means has a partial forming means for forming a developer image on a portion of the surface of the image carrier other than the portion in contact with the peeling member.

Further, according to the image forming apparatus of the second aspect, the image forming means for forming a developer image on the image carrier, the transfer means for transferring the developer image to the transfer material, and the image carrier. A peeling member that comes into contact with the surface of the body and peels the transferred material to which the developer image has been transferred from the surface of the image carrier, and a cleaning blade that contacts the surface of the image carrier, and the surface of the image carrier after transfer. And a cleaning unit for removing the developer remaining on the image carrier, wherein the image forming unit includes:
It has an exposing means for selectively exposing a portion other than the portion in contact with the peeling member, and a developing means for developing the exposed portion on the surface of the image carrier.

An image forming apparatus according to a fourth aspect of the present invention is an image forming means for forming a developer image on an image carrier, a transfer means for transferring the developer image onto a transfer material, and a surface of the image carrier. A peeling member that comes into contact with the transferred image-transferred agent to peel off the image-bearing member from the surface of the image bearing member, and a cleaning blade that contacts the surface of the image bearing member. A cleaning unit for removing the agent; the image forming unit is an exposure unit for irradiating the image bearing member surface with light to expose it; and a contact portion of the image bearing member surface where the peeling member comes into contact. And a shielding unit that selectively shields the exposure unit from the exposure unit.

[0013]

According to the image forming apparatus of the first aspect of the present invention configured as described above, in order to prevent the cleaning blade from being turned over, when the belt-shaped developer image is formed on the surface of the image bearing member, it is partially formed. The means forms a developer image on a portion of the surface of the image bearing member excluding a portion that is in contact with the peeling member.

According to the image forming apparatus of the second aspect, when the strip-shaped developer image is formed, the exposing means exposes a portion of the surface of the image bearing member excluding a portion in contact with the peeling member, The developing means develops the exposed portion of the surface of the image carrier.
As a result, a strip-shaped developer image is formed on the portion excluding the portion that contacts the peeling member.

According to the image forming apparatus of the fourth aspect, when the surface of the image bearing member is exposed by the image of the exposing unit to form the belt-shaped developer image, the shielding unit includes the above-mentioned portion of the surface of the image bearing member. The contact portion with which the peeling member contacts is selectively shielded from the exposure unit. Therefore, the contact portion is not exposed and the developer image is not formed.

Therefore, even when a strip-shaped developer image is formed to prevent the cleaning blade from being turned over, the developer image is scraped off by the peeling member and scattered on the inside of the machine or on the conveyance path of the material to be transferred. Is prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which an image forming apparatus according to the present invention is applied to a digital copying machine will be described in detail below with reference to the drawings. As shown in FIG. 1, the digital copying apparatus includes a housing 10, and in the housing 10, an image reading unit 4 and an image forming unit 6 are provided.

The image reading section 4 is an object to be read, that is, an original table 12 on which an original D is placed, and a size plate 12 which is arranged at one end of the original table 12 and indicates a position where the original D should be placed.
and a. An automatic document feeder 80 (to be referred to as an ADF hereinafter), which will be described later, is arranged on the upper surface of the housing 10. The ADF is arranged to feed a document onto the document table 12 and to be opened / closed with respect to the document table. It functions as a document holder that brings the document D placed on the document table into close contact with the document table 12.

The ADF 80 includes a document tray 82 on which the document D is placed and a transport belt 85 for transporting the document. The original placed on the original tray 82 is
It is guided to the original table 12 via the transport path 84 and positioned at a predetermined position by the transport belt 85. Then, after the reading of the original document, which will be described later, is completed, the original document D passes through the transport path 86 by the transport belt 85, and the original sheet discharge unit 8 on the upper surface of the ADF 80.
8 is discharged.

Further, the image reading section 4 has an illumination lamp 14 for illuminating the document D placed on the document table 12 and a first mirror 15 for changing the reflected light from the document D in a predetermined direction. The illumination lamp and the first mirror are attached to the first carriage 16 arranged below the document table 12 in the housing 10.

The first carriage 16 is movably arranged in parallel with the platen 12, and is moved in parallel along the platen by a pulse motor (not shown) via a toothed belt (not shown). Further, below the document table 12, a second carriage 18 which is movable in parallel with the document table is arranged.

On the second carriage 18, second and third mirrors 20 and 21 for sequentially deflecting the reflected light from the document D deflected by the first mirror 15 are mounted at right angles to each other. The second carriage 18 uses a toothed belt or the like that drives the first carriage 16 so that the first carriage 16
The carriage 16 is driven by the carriage 16 and is moved parallel to the first carriage along the document table 12 at a speed of 1/2.

Below the document table 12, an image forming lens 22 for focusing the reflected light from the third mirror 21 on the second carriage 18 and a reflected light focused by the image forming lens are received. And a CCD sensor 24 for photoelectric conversion. The imaging lens 22 is movably arranged in a plane including the optical axis of the light deflected by the third mirror 21 via a drive mechanism, and by moving itself, the reflected light is reflected at a desired magnification. Form an image. Then, the CCD sensor 24 photoelectrically converts the incident reflected light and outputs an output signal as an electric signal corresponding to the read document D to an image memory described later.

On the other hand, as shown in FIGS. 1 and 2, the image forming section 6 includes a laser exposure device 2 which functions as an exposure means.
6 is provided. The laser exposure device 26 has a semiconductor laser 27 as a light source and an optical device 28. The optical device 28 emits from the laser 27 in accordance with the image information of the document D read by the image reading section 4. The intensity of the laser light is changed, and the laser light is directed toward a photosensitive drum as an image carrier described later.

The optical device 28 gives a focusing property to the laser light from the laser 27 and converts it into a laser light having a substantially circular cross-sectional shape, and a laser light passing through the first lens, which is not shown. An optical deflecting device 30 for deflecting along the axial direction of the photoconductor drum, and a photoconductor according to the deflection angle of the laser beam in order to sequentially image the deflected laser light on a desired position on the photoconductor drum. Second and third lenses 31, 32 that adjust the distance from the optical axis on the drum to the position where the laser light is to be imaged, and the first and second lenses that turn the laser light back toward the photosensitive drum. Mirror 33,
34, and.

The image forming unit 6 has a rotatable photoconductor drum 36 disposed substantially in the center of the housing 10. The surface of the photoconductor drum is exposed by the laser light from the laser exposure device 26, and the desired photoconductor drum 36 is exposed. An electrostatic latent image (image) is formed.

Around the photosensitive drum 36, a charger 37 for charging the surface of the drum to a predetermined charge, and a toner as a developer are supplied to the electrostatic latent image formed on the surface of the photosensitive drum to develop the electrostatic latent image. A developing device 38 and a transfer material fed from a paper cassette described later, that is, a peeling charger 39 for separating the copy paper P from the photoconductor are integrally provided, and the toner image formed on the photoconductor drum is printed. A transfer charger 40 for transferring to P, a peeling claw 42 as a peeling member for peeling the copy sheet from the surface of the photosensitive drum, a cleaning device 44 as a cleaning unit for cleaning the toner remaining on the surface of the photosensitive drum, and the photosensitive drum. A static eliminator 45 for eliminating static electricity on the surface is arranged in order.

As can be seen from FIGS. 2 and 5, the peeling claw 42 has its tip on the surface of the photosensitive drum 32.
It is provided in contact with a portion of the drum substantially in the center in the axial direction. The peeling claw 42 is rotatably provided, and its base end is connected to a solenoid 47 via a rotating arm 46.

The cleaning device 44 is a cleaning blade 44.
This cleaning blade has a contact with the surface of the photoconductor drum at the downstream side of the peeling claw 42 with respect to the rotation direction of the photoconductor drum 36, and extends over substantially the entire length of the photoconductor drum in the axial direction. ing. Then, the toner remaining on the surface of the photoconductor drum 36 after the transfer step is scraped off from the drum surface by the cleaning blade 44a and sent to the waste toner container 44b.

As shown in FIG. 1, first and second sheet cassettes 48 and 50, each containing a large number of copy sheets P, are detachably attached to the lower portion of the side surface of the housing 1. Further, in the housing 1, there is a transport path 52 for transporting the sheets taken out from the first and second sheet cassettes 48 and 50 through a transfer section located between the photosensitive drum 36 and the transfer charger 40. The fixing device 53 is provided at the end of the transport path. A discharge port 54 is formed on a side wall of the housing 1 facing the fixing device 53, and a discharge tray 55 is attached to the discharge port.

First and second paper cassettes 48, 50
A pickup roller 56 and a paper feed roller pair 57 for taking out the paper from the paper cassette are provided in the vicinity of the above. The photoconductor drum 36 in the transport path 52
On the upstream side of the sheet P, the inclination of the sheet P taken out is corrected, and the front end of the toner image on the photosensitive drum 36 and the sheet P are corrected.
A registration roller pair 58 for aligning the leading end of the sheet P and feeding the sheet P at the same speed as the movement speed of the outer peripheral surface of the photosensitive drum is provided.

The sheets P picked up one by one from the first or second sheet cassette 48, 50 by the pickup roller 56 are sent to the registration roller pair 58 by the sheet feeding roller pair 57. Then, the leading edge of the sheet P is aligned by the registration roller pair 58, and then the sheet P is sent to the transfer section.
At the transfer portion, the developer image formed on the photosensitive drum 36, that is, the toner image is transferred onto the paper P by the transfer charger 40.

The sheet P on which the toner image has been transferred is separated from the surface of the photosensitive drum 36 by the action of the AC corona discharge from the separation charger 39 and the separation claw 42, and the conveyance path 5
The fixing device 5 via the conveyor belt 60 forming a part of
3 is transported. Then, after the developer image is melted and fixed on the copy paper P by the fixing device 53, the paper P is discharged from the paper discharge tray 5 by the paper feed roller pair 61 and the paper discharge roller pair 62.
5 is discharged.

Below the conveying path 52, the fixing device 5 is provided.
The sheet P that has passed through the sheet No. 3 is reversed and the registration roller 58 again.
A reversing mechanism 64 for feeding to Reversing mechanism 64
Is a temporary stacking unit 65 that temporarily stacks the paper P, an inversion path 66 that branches from the transport path 52 and that reverses the paper P that has passed through the fixing device 53 and leads to the temporary stacking unit 65, and a temporary stacking unit. A pickup roller 67 for taking out the accumulated sheets P one by one and a sheet feeding roller 69 for feeding the taken out sheets to the registration roller pair 58 through the conveyance path 68 are provided. Further, a distribution gate 70 for selectively distributing the paper P to the discharge port 54 or the reversing path 66 is provided at a branch portion between the transport path 52 and the reversing path 66.

When performing double-sided copying, the paper P that has passed through the fixing device 53 is fed to the reverse path 6 by the sorting gate 70.
The sheet is guided to the sheet No. 6 and is temporarily stacked in the inverted state in the stacking unit 65, and then is sent to the registration roller pair 58 through the transport path 68 by the pickup roller 67 and the paper feed roller pair 69. Then, the paper P is the registration roller 5
After being sorted by 8, the toner image is transferred to the transfer portion again and the toner image is transferred to the back surface of the paper P. After that, the paper P is discharged onto the discharge tray 55 via the transport path 52, the fixing device 53, and the discharge rollers 62.

FIG. 3 shows the configuration of the control system of the digital copying apparatus configured as described above. That is, the main controller 71 that controls the operations of the image reading unit 4 and the image forming unit 6.
Is a CPU 72 serving as a main controller, and an RO connected to the CPU and storing rules for operating the copying apparatus.
M74, a RAM 76 for storing numerical data such as the number of copies and copy magnification input from the operation panel 17 of the copying apparatus,
And the A / D output from the CCD sensor 24, which will be described later.
An image memory 78 for temporarily storing an image signal converted into a digital signal via the conversion circuit 92a is provided. The image data stored in the image memory 78 is converted into binary data by a signal conversion unit 92 described later.

The CPU 72 has a high-voltage transformer (not shown) for supplying a desired voltage to the charging charger 37 and the transfer charger 40, and a horizontal sync detector 97 provided in the laser exposure device 26 for detecting the horizontal sync of the laser light.
A laser driver 91 for driving the semiconductor laser 27 of the laser exposure device 26, a drive unit 80 for urging a mechanical unit such as a switch group and a solenoid for detecting the position of the paper P or the remaining amount in the paper cassette, First and second carriages 16, 18, photoconductor drum 36, developing device 3
8. A motor driver 82 for energizing a transport mechanism, a motor for driving the deflection device 30 of the laser exposure device 26, and the like, and a lamp control for turning on the illumination lamp 14, the heater lamp of the fixing device 53, and the like. The parts 84 and are connected. The main control unit 7 having the CPU 72
Reference numeral 1 constitutes a reducing means in the present invention, and also constitutes an image forming means and a partial forming means together with the laser exposure device 26 and the developing device 38 described above.

Further, the CPU 72 has an internal interface 90 for causing the CPU 72 to read the numerical data input from the operation panel 17, and the image data stored in the image memory 78 can be output by the image forming section 6.
An image signal different from the image signal from the image reading unit 4 and the signal converting unit 92 for converting the value data, for example, from an external device 95 such as a host computer or a word processor for using the image forming unit 6 as a printer device. An external interface 94 for inputting an image signal and transmitting image data read through the image reading unit 4 to an external device, and an encoding unit 96 for converting the image data into binary data that can be transmitted to the external device 95. A timer 98 that counts a time limit defined according to various inputs, for example, the timing of changing the output of the laser light or the input waiting time in a plurality of operation modes is connected.

The signal conversion unit 92 converts the analog image signal output from the CCD sensor 24 into a digital signal, and the image forming unit 6 converts the image data output from the CCD sensor 24 with a specific resolution. Resolution conversion circuit 92b, A /
A shading correction circuit for correcting the fluctuation of the threshold level with respect to the output signal from the CCD sensor 24, which is caused by the individual error of the CCD sensor 24 and the ambient temperature change, etc., of the signal converted into the digital signal through the D conversion circuit 92a. 92c, shading correction circuit 92
After the image data passing through c is separated into, for example, a luminance signal and a color difference signal, filtering, trimming,
In order to change the intensity of the laser beam emitted from the semiconductor laser 27 of the laser exposure device 30 based on the image quality improving circuit 92d for performing masking, edge enhancement, character identification, etc., and the image data output from the image quality improving circuit. A binarization circuit 92e for binarizing the image data is provided, and the image of the document D is converted into a binary print signal.

The coding unit 96 compresses the code conversion circuit 96a for converting the code of the binary data, and the band of the code-converted data (and, if the data is supplied from the external device 95, it has already been compressed). The image data stored in the image memory 78 is converted so as to be suitable for the external device 95.

According to the copying apparatus configured as described above, when the power of the apparatus is turned on, first, a predetermined initialization operation stored in the ROM 74 of the main control unit 71 is executed to execute the copying operation. It becomes feasible.

When the start key of the operation panel 17 is pressed while the document D is placed on the document table 12, the illumination lamp 14 is turned on and the first and second carriages 16 are driven via the motor driver 82. , 18 is the platen 12
Will be moved along. Thereby, the reflected light from the document D, that is, the image information is sequentially guided to the CCD sensor 24.

The reflected light received by the CCD sensor 24 is
After being converted into an analog signal, the analog signal is supplied to the signal conversion unit 92 and converted from an analog signal to a digital signal via the A / D conversion circuit 92a. Further, this signal sequentially passes through the resolution conversion circuit 92b and the shading correction circuit 92c, and is temporarily stored in the image memory 78 as image data.

Subsequently, the read image data of the document D is output from the image memory 78 to the image forming section 6 and image-formed according to the following copying process. In other words, the image data stored in the image memory 78 is converted into a binary print signal through the image quality improving circuit 92d and the binarizing circuit 92e, and then serialized through a parallel-serial converting circuit (not shown). The converted data is supplied to the laser exposure device 26 of the image forming unit 6 via the internal interface 90.

In the image forming section 6, the photosensitive drum 36 is rotated at a desired speed when the copying operation is started.
At the same time, by the charging charger 37, the photosensitive drum 36
Is uniformly charged with a desired electric charge.

A semiconductor laser 27 of the laser exposure device 26 emits a laser beam whose intensity is modulated according to a print signal, and the optical device 28 irradiates the surface of the photosensitive drum 36. As a result, an electrostatic latent image corresponding to the print signal (image data) is formed on the surface of the photosensitive drum 36. This electrostatic latent image is developed by the toner supplied from the developing device 38, and transferred as a toner image on the copy paper P by the transfer charger 40.

The copy paper P on which the toner image is transferred is peeled from the photosensitive drum 36 by the peeling charger 39 and the peeling claw 42, and then conveyed to the fixing device 53, where the toner image is fused and fixed on the paper P. To be done. Then, the paper P to which the toner image is fixed is discharged to the discharge tray 55. On the other hand, when the copying operation is performed again after a certain period of time has elapsed after the copying operation is completed, in order to prevent the cleaning blade 44a from being turned over, the copying operation is preceded by
A belt-shaped toner image is formed on the surface of the photosensitive drum 36.
In this case, as shown in FIG. 5, the belt-shaped toner image M is formed on the surface of the photoconductor drum 36 except for the contact portion C that contacts the peeling claw 42.

That is, when forming a belt-shaped toner image,
The CPU 72 of the main control unit 71 first sets the photosensitive drum 36.
Rotate the charger at the desired speed and charge the charger 3
7, the surface of the photosensitive drum 36 is uniformly charged with a desired electric charge. Further, the CPU 72 controls the laser exposure device 26.
Of the laser driver 9
The semiconductor laser 27 is excited via 1 to expose the surface of the photosensitive drum 36 with a predetermined output, that is, a laser beam of level H at which toner adheres to the exposed portion of the surface of the photosensitive drum 36.

At this time, the CPU 72, as shown in FIG. 4, receives a horizontal synchronizing signal from the horizontal synchronizing detector 97, and then a predetermined time T1 (the laser light reaches a position about 5 mm before the contact portion C). Time), the output of the laser beam is reduced to a level L at which toner does not adhere to the exposed portion of the surface of the photosensitive drum exposed by the laser beam,
Furthermore, for a certain period of time T2 (about 5 mm from the contact point C with laser light)
When the passing time) has elapsed, the output of the laser light is returned to the level H.

After the above exposure operation is repeated a plurality of times, the exposed portion on the surface of the photoconductor drum 36 is developed by the developing device 38, so that the peeling claw 42 is formed on the surface of the photoconductor drum as shown in FIG. A belt-shaped toner image M having a width of about 1 mm is formed except for the contact portion C and the area having a width of about 10 mm on both sides of the contact portion.

The belt-shaped toner image M is sent to the cleaning blade 44a via the transfer section and the peeling claw 42 as the photosensitive drum 36 rotates, and is scraped off from the surface of the photosensitive drum 36 by this cleaning blade.
At that time, the toner forming the toner image M acts as a lubricant that reduces friction between the cleaning blade 44a and the surface of the photosensitive drum. Therefore, the friction between the cleaning blade 44a and the surface of the photoconductor drum in the subsequent copying operation is reduced, and the cleaning blade is prevented from being turned over.

According to the digital copying apparatus configured as described above, the belt-shaped toner image formed on the surface of the photosensitive drum 36 in order to prevent the cleaning blade 44a from being turned over is separated from the surface of the photosensitive drum. The contact part C is formed in a part excluding the contact part C with which the claw 42 contacts.
Is not formed in. Therefore, when the toner image formed on the surface of the photoconductor drum passes through the peeling claw 42, the peeling claw 4 moves.
It does not come into contact with 2 and is not scraped off by the peeling claw.

Therefore, it is possible to prevent the toner forming the band-shaped toner image from falling and scattering in the body of the copying apparatus or on the conveying path, and it is possible to prevent the body and the copy sheet from being contaminated. As a result, the cleaning blade 44a is prevented from being turned over without contaminating the inside of the copying machine or the copy sheet.

Next explained is a digital copying machine according to the second embodiment of the invention. The same parts as those in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 6, according to the second embodiment, between the laser exposure device 26 and the photosensitive drum 36,
A shutter 98 as a shielding member and a solenoid 99 as a driving means for driving the shutter are provided, which constitutes the shielding means in the present invention.

The shutter 98 has a pivot 98a at its middle portion.
Is rotatably supported by a machine body (not shown) of the copying machine. Further, the shutter 98 is a contact portion C of the surface of the photosensitive drum 36 with which the peeling claw 42 comes into contact (see FIG. 5).
It is arranged to face. Then, the shutter 98
Around the pivot 98a, it is possible to move between a shielded position shown by a solid line and a retracted position shown by a broken line in FIG.

At the blocking position, the tip of the shutter 98 interferes with the laser beam emitted from the laser exposure device 26 and blocks the laser beam incident on the contact portion C on the surface of the photosensitive drum 36. Further, in the retracted position, the shutter 9
Reference numeral 8 is retracted from the optical axis of the laser light, and the laser light is entirely irradiated onto the surface of the photosensitive drum 36 without being shielded.

The base end of the shutter 98 is a solenoid 99.
Is connected to the plunger 99a. The shutter 98 is normally held in the retracted position, and when the solenoid 99 is excited, it is moved to the closed position by the plunger 99a. The solenoid 99 is connected to the main controller 71 (see FIG. 3) of the copying machine and controlled by the CPU 72.

The other structure is the same as that of the first embodiment described above, and the description thereof is omitted. In the digital copying apparatus according to the second embodiment, the cleaning blade 44a
When a belt-shaped toner image is formed on the surface of the photosensitive drum 36 in order to prevent curling, the laser exposure device 26, the charger and the photosensitive drum 36 are driven under the control of the main controller 71. At the same time, the solenoid 99 is excited and the shutter 98 is moved to the blocking position.

Therefore, the laser light emitted from the laser exposure device 26 is partially shielded by the shutter 98, the contact portion C on the surface of the photosensitive drum 36 is not exposed, and the portion other than the contact portion C is strip-shaped. Exposed. Then, the exposed portion on the surface of the photoconductor drum 36 is developed by a developing device to form a belt-shaped toner image M (see FIG. 5) on the surface of the photoconductor drum 36. This toner image is generated as the photoconductor drum 36 rotates. Are sent to the cleaning blade 44a.

According to the second embodiment constructed as described above, the belt-shaped toner image formed on the surface of the photosensitive drum 36 in order to prevent the cleaning blade 44a from being turned over is changed by the shutter 98 into a laser beam. By shielding a part of the surface, it is formed on the surface of the photosensitive drum except the contact portion C with which the peeling claw 42 comes into contact, and is not formed on this contact portion C. Therefore, as in the first embodiment described above, the toner image formed on the surface of the photosensitive drum is not scraped off by the peeling claw 42, and the inside of the copying machine or the copy paper is not contaminated due to the toner falling. Can be prevented. As a result, it is possible to prevent the cleaning blade 44a from being turned over without contaminating the inside of the copying machine or the copy sheet.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention.
For example, the peeling claw is not limited to one, and a plurality of peeling claws may be provided. The second embodiment using the shielding member can be applied not only to the digital type copying apparatus but also to the analog type copying apparatus.

[0063]

As described above in detail, according to the present invention, even when the developer image for lubricating the cleaning member is formed on the image carrier, the developer is prevented from falling and scattering by the peeling claw. As a result, it is possible to provide the image forming apparatus capable of preventing the cleaning member from being turned over without contaminating the inside of the machine body or the material to be transferred.

[Brief description of drawings]

FIG. 1 is a sectional view showing an entire digital copying apparatus according to a first embodiment of the present invention.

FIG. 2 is a side view showing an enlarged main part of the digital copying apparatus.

FIG. 3 is a block diagram showing a configuration of a control system of the digital copying apparatus.

FIG. 4 is a timing chart showing a relationship between a laser light output and a horizontal synchronizing signal.

FIG. 5 is a perspective view of a photosensitive drum on which a belt-shaped toner image is formed.

FIG. 6 is a side view schematically showing a main part of a digital copying apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

4 ... Image reading unit, 6 ... Image forming unit, 24 ... CCD sensor, 26 ... Laser exposure device, 27 ... Semiconductor laser, 36
... Photosensitive drum, 38 ... Developing device, 42 ... Separation claw, 44 ...
Cleaning device, 44a ... Cleaning blade, 70 ... Main control unit, 72 ... CPU, 91 ... Laser driver, 97 ... Horizontal sync detector, 98 ... Shutter, 99 ... Solenoid.

Claims (5)

[Claims] 1. An image forming means for forming a developer image on an image carrier, a transfer means for transferring the developer image onto a transfer material, and a surface of the image carrier for contacting the developer image. A peeling member for peeling the transferred material to be transferred from the surface of the image carrier, and a cleaning means having a cleaning blade in contact with the surface of the image carrier, for removing the developer remaining on the surface of the image carrier after transfer, The image forming apparatus is characterized in that the image forming means has a partial forming means for forming a developer image on a portion of the surface of the image carrier other than a portion contacting the peeling member. . 2. An image forming means for forming a developer image on an image carrier, a transfer means for transferring the developer image to a transfer material, and a surface of the image carrier for contacting the developer image. A peeling member for peeling the transferred material to be transferred from the surface of the image carrier, and a cleaning means having a cleaning blade in contact with the surface of the image carrier, for removing the developer remaining on the surface of the image carrier after transfer, The image forming means comprises an exposing means for selectively exposing a portion of the surface of the image bearing member excluding a portion in contact with the peeling member, and a developing means for developing an exposed portion of the surface of the image bearing member. An image forming apparatus comprising: 3. The laser exposure means for irradiating the surface of the image carrier with a laser beam having a predetermined output,
3. A means for reducing the output of laser light when exposing a portion of the surface of the image bearing member, which comes into contact with the peeling member, with the laser light.
The image forming apparatus according to item 1. 4. An image forming means for forming a developer image on an image carrier, a transfer means for transferring the developer image to a transfer material, and a surface of the image carrier for contacting the developer image. A peeling member for peeling the transferred material to be transferred from the surface of the image carrier, and a cleaning means having a cleaning blade in contact with the surface of the image carrier, for removing the developer remaining on the surface of the image carrier after transfer, The image forming means selects an exposing means for irradiating the surface of the image bearing member with light to expose it, and a contact portion of the surface of the image bearing member where the peeling member comes into contact with the exposing means. An image forming apparatus comprising: a shielding unit that physically shields. 5. The shielding means includes a shielding member movably provided between a shielding position for shielding light incident on the contact portion from the exposing means and a retracted position for retracting from the optical axis of the light. The image forming apparatus according to claim 4, further comprising: a driving unit that selectively moves the shielding member to a shielding position and a retracted position.