JPH10293512A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extremely prevent the edge of same-size paper from coming in contact with the same place of an image carrier for a long period, to restrain the occurrence and the growth of damage by the paper edge and to improve endurance image stability by moving the image carrier in a thrust direction when an image is not formed after the consecutive copying of the same size. SOLUTION: After finishing the rotating action of photoreceptor drums 1a to 1d, a moving motor is driven according to a moving signal from a control mechanism 70 so as to move the drums 1a to 1d to an inner side in the thrust direction through an attachable/detachable coupling gear 72. Cleaning blades in cleaning devices 4a to 4d are moved in the same direction at the same speed by the same amount interlocked with the drums 1a to 1d by a gear 73 coupled with the gear 72 arranged on the side surfaces of the drums 1a to 1d. Paper size, the number of consecutively copied sheets and the number of accumulated sheets are recorded and held in the mechanism 70 transmitting the moving signal, and a control signal is transmitted to the mechanism 70 through a sequence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as an electrostatic copying machine and an electrostatic printer using an electrostatic transfer process.

[0002]

2. Description of the Related Art Conventionally, when a large number of copies of the same small size and in the same transport direction are made in an image forming apparatus, sharp scratches are generated on an image carrier corresponding to a portion of the transfer material that hits the edge. It has been reported that when a large-sized transfer material is later fed, an image defect called edge flaw corresponding to a flaw on the image carrier significantly occurs on the image.
For this reason, high-hardness amorphous silicon drums and the like have been introduced as image carriers into monochrome copiers. However, this has led to a solution to the occurrence of edge memory in the transfer material and image defects due to the accumulation of paper dust from the edge. There is no present.

Further, with the rapid rise of color copying machines in recent years, photosensitive drums having excellent light sensitivity characteristics have been employed.

However, a photosensitive drum having excellent light sensitivity characteristics is remarkably softer in terms of surface hardness than the amorphous silicon drum. Products with streak image defects due to the above are scattered. For this reason, in recent years, attempts have been made to positively scrape paper flaws with a cleaning blade as a countermeasure, and a mechanism for reciprocating (reciprocating) the cleaning blade in the thrust direction on the image carrier has been proposed.

[0005] However, once a memory is generated, it is impossible to deal with it with a cleaning blade.
At present, the service life of the image carrier and the blade is unnecessarily reduced by increasing the pressure of the blade.

Therefore, a mechanism has been proposed in which a certain number of copies are counted and the image carrier is shifted in the thrust direction so as not to damage the image carrier. According to this mechanism, the paper edge does not pass to the same position, and the edge flaws and the memory do not grow. Therefore, it is considered that this mechanism has a considerable effect on image defects.

[0007]

However, when the image carrier is moved in the thrust direction when the cleaning member is in contact with the image carrier, the toner carrier is scratched by the waste toner accumulated on the blade edge. Or cause
In some cases, the blade edge may be damaged, and the durability life tends to be shortened as a whole.

Therefore, it has been proposed to move the carrier in the thrust direction after separating the cleaning member from the image carrier. However, in this method, waste toner staying in the cleaning member when the cleaning member is separated has been proposed. However, there is a problem that the inside of the apparatus is contaminated by dropping, and waste toner goes around to the contact portion, and the cleaning property of the cleaning member at the time of re-contact is hindered. For this reason, it has become necessary to move the image carrier in the thrust direction during non-image formation while the cleaning member is in contact with the image carrier.

Accordingly, it is an object of the first invention to provide an image forming apparatus capable of minimizing the occurrence and growth of paper edge flaws, preventing image defects from occurring, and improving durability image stability. I do.

Conventionally, when a halftone solid image is printed after continuous copying of an image of the same pattern with a transfer material of the same size in a high volume number in an image forming apparatus, the image density of a portion corresponding to the image portion is reduced. It may be lower than that of other portions, and may appear as an image defect of white and vertical streaks in the sub-scanning direction by visual evaluation.

[0011] The cause of the above-mentioned image defects is that a toner as an image forming material corresponding to an image is scraped off by a cleaning member in contact with the image carrier in a state where the toner is electrostatically attached to the image carrier. It is considered that the surface of the image carrier is scratched by an external additive such as an abrasive in the toner and scratches are generated. In particular, when a large number of continuous copies are made continuously, the scratch is naturally fixed at a specific location and grows in proportion to the number of copies. Then, the scratches on the image carrier, which has grown deeply and greatly, are covered with paper dust or a lubricant of a cleaning blade (to improve the slipperiness on the image carrier to prevent curling) or toner. Will be buried according to. The clogged foreign substances are exposed to ozone or the like when subjected to a static elimination action on the image carrier, generate nitrogen compounds and the like, and easily adsorb moisture in the apparatus. If the image carrier is left without improving this state, it leads to a decrease in the charging ability, a decrease in the developing ability, and the occurrence of image white streaks tends to occur.

On the other hand, a proposal has been made to set the pressure of the cleaning member high before the scratches on the image bearing member grow to scrape the scratches on the image bearing member. The life of the carrier and the cleaning member is reduced.

In view of the above, there has been proposed a method in which a large amount of an abrasive is contained in the toner itself to scrape the scratches on the image carrier.
Since the abrasive itself has a smaller particle size than the toner, cleaning failure and filming due to slip-through easily occur,
This is a factor that hinders image stability.

To solve these problems, the cleaning member is reciprocated in the thrust direction of the image carrier (reciprocating operation).
In recent years, proposals have been made to actively cut the flaws on the image carrier in a state where there is no toner by increasing the idle rotation time during the non-image forming period of the image carrier or performing an operation for preventing the generation and growth of the flaw.

However, when the cleaning member is reciprocated with respect to the image carrier, the growth speed of the flaw on the image carrier is reduced, but the flaw is easily spread in the lateral direction by the reciprocating stroke, and the area of the flaw is reduced. Some negative effects have been observed. For this reason, further improvement by improving the reciprocating mode of the cleaning member is required.

Increasing the idling time of the image carrier during the non-image forming period has a disadvantage that the life of the cleaning member is shortened and the copying operation sequence time is lengthened. For this reason, there is a demand for a method of scraping a flaw caused by an image on the image carrier while shortening the idle rotation time of the image carrier.

Accordingly, the second invention provides an image forming apparatus capable of efficiently scraping a flaw before the flaw on an image carrier grows, preventing image defects from occurring, and improving durable image stability. The purpose is to provide.

[0018]

In order to achieve the above object, the present invention is directed to an image carrier, a cleaning device for contacting the image carrier and cleaning residual toner on a surface thereof, and an image carrier. In an image forming apparatus having a mechanism for operating a carrier and a cleaning member of a cleaning device in a thrust direction of an image carrier, the operation in the thrust direction of the image carrier and the operation in the thrust direction of the cleaning member during non-image formation are the same. It is characterized by having done.

According to a second aspect of the present invention, in the first aspect, the operation of the image carrier in the thrust direction and the operation of the cleaning member in the thrust direction are reciprocating operations.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the image carrier is held during the operation of the image carrier in the thrust direction during the non-image forming period and during the operation of the cleaning member in the thrust direction. The body may or may not perform a circumferential rotation.

According to a fourth aspect of the present invention, there is provided an image carrier, a cleaning device for contacting the image carrier and cleaning residual toner on the surface thereof, and a cleaning member of the cleaning device which is disposed on the image carrier in a thrust direction. In an image forming apparatus having a mechanism for performing reciprocating operation, the peripheral speed of the image carrier during image formation is V1, the reciprocating cycle of the cleaning member is S1, the peripheral speed of the image carrier during non-image formation is V2, and the cleaning member is When the reciprocating cycle of S2 is S2, the relationship of V1 <V2 and S1 ≦ S2 is satisfied at the same time.

According to a fifth aspect of the present invention, in the fourth aspect, S1 = S2.

According to a sixth aspect of the present invention, in the fourth or fifth aspect of the present invention, the above relationship is satisfied only during non-image formation when a continuous image copying mode of the same transfer material size and the same image mode is set. And

Therefore, according to the first to third aspects of the present invention, by moving the image carrier in the thrust direction at the time of non-image formation after continuous copying of the same size, paper of the same size is formed. The edge can be prevented from coming into contact with the same place on the image carrier for a long time, and the occurrence and growth of the edge of the paper can be suppressed as much as possible, thereby preventing the occurrence of an image defect and improving the durability image stability.

Further, the invention according to claims 4 to 6 (second invention)
According to the method, by increasing the peripheral speed of the image carrier during non-image formation and the reciprocating cycle of the cleaning member as compared with those during image formation, the polishing ability of the scratches on the image carrier per unit time is increased, and The scratches can be efficiently scraped off before the growth to prevent the occurrence of image defects, and the durability of the durable image can be improved.

[0026]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First Embodiment FIG. 1 is a sectional view of an image forming unit of an image forming apparatus according to a first embodiment of the first invention, FIG. 2 is a plan view of a photosensitive drum portion of the image forming unit, FIG. 3 is a sectional view of the entire image forming apparatus.

The image forming apparatus according to this embodiment is similar to the image forming apparatus shown in FIG.
As shown in the figure, four image forming units Pa, Pb, P
c, Pd, each of which is a multicolor electrophotographic copying machine, wherein each of the image forming units Pa to Pd includes a photosensitive drum 1 as an image carrier.
a to 1d, and primary chargers 12a to 12d and pre-exposure light sources 13a to 13d around the respective photosensitive drums 1a to 1d.
13d, developing devices 2a to 2d, transfer chargers 3a to 3d, and cleaning devices 4a to 4d are arranged respectively.

An endless transfer belt 30 as a conveying means is disposed below the photosensitive drums 1a to 1d, and a transfer material P is applied between the transfer chargers 3a to 3d and the photosensitive drums 1a to 1d. It is supplied to the contact portion (transfer nip portion) at an appropriate timing.

Incidentally, as shown in detail in FIG. 1, each of the cleaning devices 4a to 4d is provided with a corresponding one of the photosensitive drums 1a to 1d.
It has a cleaning blade 43 and a squeeze sheet 41 that come into contact with the counter and the quiz, respectively. A rotating gear 42 for rotating a waste toner screw (not shown), which is long in a direction perpendicular to the paper surface of FIG. 1, is accommodated in the waste toner box 44 of each of the cleaning devices 4a to 4d.

In this embodiment, the photosensitive drum 1
As a to 1d, those having a diameter of φ60 mm are used, and these are rotationally driven in the direction of arrow A in FIG. 1 at a peripheral speed (process speed) of 130 mm / sec. Then, after the surface charges are removed by the pre-exposure light sources 13a to 13d during the rotation of the photosensitive drums 1a to 1d,
The surface is uniformly charged by the primary chargers 12a to 12d, and the laser beam exposure device 11 (see FIG. 3)
, An electrostatic latent image which is color-separated corresponding to the image exposure pattern is formed on the surface.

The developing devices 2a to 2d for the respective colors have negatively charged toners of the respective colors (yellow, magenta, cyan and black), and apply the respective toners to the respective developing sleeves 21 (see FIG. 1). A voltage (development bias) applied to each of the developing sleeves 21 is carried on the upper surface and conveyed to a developing area close to the photosensitive drums 1a to 1d.
The toner of each color is made to adhere to the electrostatic latent images on each of the photosensitive drums 1a to 1d by a developing electric field formed by the electric field and the surface potentials of the photosensitive drums 1a to 1d, and the electrostatic latent images are visualized as toner images.

On the other hand, the transfer material P is carried on the transfer belt 30 as described above, and the transfer chargers 3a to 3d and the photosensitive drum 1
The photosensitive drums 1a to 1d are supplied at appropriate timing to contact portions (transfer nip portions) with the photosensitive drums 1a to 1d.
The toner images on the transfer material P are sequentially transferred by the transfer chargers 3a to 3d, and a full-color image is formed on the transfer material P.
Then, the transfer material P carrying the unfixed full-color image
Is conveyed to the fixing device 5 by the conveying belt 62, and after the full-color image is fixed by heat and pressure while passing between the fixing roller 51 and the pressure roller 52 of the fixing device 5, the paper is discharged outside the machine. It is discharged onto the tray 63.

The untransferred toner remaining on the photosensitive drums 1a to 1d without being transferred onto the transfer material P in the transfer step is removed by the cleaning devices 4a to 4d, respectively, and the respective photosensitive drums from which the untransferred toner is removed are removed. 1a ~
1d is used for the next image formation.

In the multicolor electrophotographic copying machine according to the present embodiment, when the copying operation is started by pressing the image forming start button, the photosensitive drums 1a to 1d rotate four times before the image forming operation. After the pre-rotation, the image forming operation starts, and the rotation of the developing sleeve 21 starts.

Here, the small size B5R postcards are stacked on the manual feed tray 65, and 250 sheets are copied in the continuous mode for four cycles, and then the developing operation is terminated.
After the photosensitive drums 1a to 1d are idlely rotated by 10 rotations, these rotation operations are completed.

After the rotation of the photosensitive drums 1a to 1d is completed, the drive motor is driven by a movement signal from the control mechanism 70 shown in FIGS. The moving speed of the drums 1a to 1d in the thrust direction deep side (the opposite side of the door) is 0.1 mm / sec.
To move by 0.5 mm. At this time, the photosensitive drum 1
The cleaning blade 143 in the cleaning devices 4a to 4d moves by the same speed and the same amount in the same direction in conjunction with the photosensitive drums 1a to 1d by the gear 73 connected to the connecting gear 72 disposed on the side surface of the photosensitive drums 1a to 1d. The control mechanism 70 that transmits the movement signal records and holds the paper size, the continuous number, the cumulative number, and the like, and sends a control signal through a sequence.

As described above, even if the next copy of the same small-size paper is continued, the damaged portions on the photosensitive drums 1a to 1d that have been damaged by the edge movement are continuously moved to the same portion. Damage can be avoided, edge growth, growth of memory and the like can be suppressed, and overall image durability stability can be improved.

Second Embodiment Next, a second embodiment of the first invention will be described with reference to FIGS. FIG. 4 is a plan view of the photosensitive drum portion of the image forming unit according to the present embodiment.

The multicolor electrophotographic copying machine according to the present embodiment assumes a product specification having a higher copy volume than that of the first embodiment.
The movement amounts of the cleaning blades a to 1d and the cleaning blade 143 are increased, and a space-related constraint condition is generated.

Therefore, in the present embodiment, after copying 250 sheets of small-size B5R sheets for four cycles, and then completing the developing operation and the idling operation of the photosensitive drums 1a to 1d, the present embodiment differs from the first embodiment. Similarly, the photosensitive drums 1a to 1d and the cleaning blade 1 are located behind the photosensitive drums 1a to 1d.
43 was moved. Here, the total movement amount limit on the back side is 5
mm, and after the limit, the moving directions of the photosensitive drums 1a to 1d and the cleaning blade 143 are reversed to move them toward the opening / closing door. However, the amount of one movement was 0.3 mm so as not to overlap with the amount of movement in the depth direction.

As described above, the restriction of the movement amount due to the increase in the number of copies is cleared, and the movement amount of the forward movement and the backward movement is changed, thereby avoiding the overlap of the edge portions and eliminating the adverse effect. Image quality durability stability could be established.

<Third Embodiment> Next, a third embodiment of the first invention will be described with reference to FIGS.

In this embodiment, the photosensitive drums 1a to 1d and the cleaning blade 143 can be moved during the operation of the apparatus, so that the copying time can be shortened.

In the present embodiment, the copier enters the adjustment mode, for example, every 200 sheets during continuous copying, and a control sequence for interrupting the image forming operation and correcting the potential of the photosensitive drums 1a to 1d is input. I have. Therefore, during this period, the second embodiment is executed immediately before the start of the control operation.
The movement of the photosensitive drums 1a to 1d and the cleaning blade 143 in the thrust direction is performed in the same manner as described above. This allows
The movement of the photosensitive drums 1a to 1d and the cleaning blade 143 is performed during the operation of the apparatus, and it is possible to establish a mode that can sufficiently cope with a reduction in the operation time of the copying machine and an increase in the set number of continuous copies. [Second invention] An embodiment of the second invention will be described below with reference to the accompanying drawings. Note that the configuration of the multicolor electrophotographic copying machine according to the embodiment described below is the same as that shown in FIG. 3, and thus the description thereof will not be repeated.

Embodiment 1 Embodiment 1 of the second invention will be described below with reference to FIGS. FIG. 5 is a plan view of a photosensitive drum portion of the image forming unit according to the present embodiment.

In this embodiment, each developing device 2a
The toner having an average particle diameter of 8 .mu.m is used as the toner contained in .about.2d.

In the present embodiment, during image formation, the cleaning blade 143 in contact with the photosensitive drums 1a to 1d has a cycle of 2 Hz and a stroke length of ± 3 mm in the thrust direction of the photosensitive drums 1a to 1d. Reciprocating operation.

Then, in the state where the image formation is completed, the photosensitive drums 1a to 1d are continuously rotated afterwards. During the rotation, signals are transmitted from the control sequence devices 70 and 71 to drive the photosensitive drums 1a to 1d. And the rotation speed of 130 mm / sec during image formation on the photosensitive drums 1a to 1d is increased to 180 mm / sec.
rise to c. At the same time, cleaning blade 1
The reciprocating cycle of 43 is also changed from 2 Hz during image formation to 3 Hz.

As described above, the idle rotation speed of the photosensitive drums 1a to 1d and the cleaning blade 1 during the non-image forming period
By increasing the reciprocating speed at 43, a mode is established in which abrasion caused by toner on the photosensitive drums 1a to 1d generated during image formation is efficiently removed during non-image time, thereby preventing the appearance of white streaks, which are defective images. As a result, long-term image stability could be secured.

<Second Embodiment> Next, a second embodiment of the second invention will be described with reference to FIGS.

The copying machine according to the present embodiment has a product specification having a higher copy volume than that of the first embodiment, and the toner used is also reduced in particle size for higher image quality. A toner having an average particle size of 7 μm is used.

As described above, when the reciprocating cycle of the cleaning blade 143 on the photosensitive drums 1a to 1d is increased, the edge of the cleaning blade 143 is greatly worn, and there is a concern that the cleaning durability is reduced.

Therefore, in the present embodiment, the cycle of the cleaning blade 143 is fixed, and the photosensitive drums 1a to 1d are fixed.
By further increasing the rotation speed of the photosensitive drums, a decrease in the abrasion of scratches on the photosensitive drums 1a to 1d is compensated for.

That is, in this embodiment, the circumferential rotation speed (peripheral speed) of the photosensitive drums 1a to 1d during non-image formation is set to 200 mm / sec, and the cleaning blades during image formation and during non-image formation are set. 143, the reciprocating cycle is fixed at 2 kHz, and other conditions are the same as those in the first embodiment.
The same as above.

Third Embodiment Next, a third embodiment of the second invention will be described with reference to FIGS.

The copying machine according to the present embodiment is the same as that of the first embodiment.
It has a copy volume specification that is three times that of the original, and a copy speed that is twice as high.
For this reason, it is desired to avoid as much as possible direct damage to the life of the members such as an increase in the rotation speed of the photosensitive drums 1a to 1d and an increase in the reciprocating cycle of the cleaning blade 143.

Therefore, in the present embodiment, the polishing of the scratches on the photosensitive drums 1a to 1d and the high-speed image durability life can be achieved at the same time as efficiently as possible.

That is, assuming that the mode in which image white streaks are noticeably generated is when a large number of the same image of the same size are continuously copied, the photosensitive drums 1a to 1d immediately after the continuous 5000 copies are made. The mode of Embodiment 1 was performed during the idle rotation period. However, in this copying machine, the rotation speed of the photosensitive drums 1a to 1d is set to 250 mm / during the image forming period.
sec and 300 mm / sec during the non-image forming period.

[0059]

As is apparent from the above description, claim 1
According to the inventions (1) to (3), the image carrier is moved in the thrust direction at the time of non-image formation after continuous copying of the same size, so that the paper edge of the same size paper is moved to the same place on the image carrier. The effect of minimizing the contact with the paper for a long period of time, minimizing the occurrence and growth of paper edge flaws, preventing the occurrence of image defects, and improving the stability of durable images can be obtained.

Further, the invention according to claims 4 to 6 (second invention)
According to the method, by increasing the peripheral speed of the image carrier during non-image formation and the reciprocating cycle of the cleaning member as compared with those during image formation, the polishing ability of the scratches on the image carrier per unit time is increased, and Before the growth, the scratches can be efficiently scraped off to prevent the occurrence of image defects, and the effect of improving the stability of the durable image can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of an image forming unit of an image forming apparatus according to a first and a second embodiment of the present invention.

FIG. 2 is a plan view of a photosensitive drum portion of the image forming unit according to Embodiments 1 and 3 of the first invention.

FIG. 3 is a cross-sectional view of the entire image forming apparatus (multicolor electrophotographic copying machine) according to the first and second inventions.

FIG. 4 is a plan view of a photosensitive drum portion of an image forming unit according to Embodiment 3 of the first invention.

FIG. 5 is a plan view of a photosensitive drum portion of the image forming unit according to the embodiment of the second invention.

[Explanation of symbols]

1a to 1d Photosensitive drum (image carrier) 4a to 4d Cleaning device 70 Control mechanism (control sequence device) 71 Control sequence device 72 Connecting gear 73 Gear 143 Cleaning blade (cleaning member)

Claims (6)

[Claims] An image carrier, a cleaning device that contacts the image carrier and cleans residual toner on the surface thereof, and a mechanism that operates the image carrier and a cleaning member of the cleaning device in a thrust direction of the image carrier. Wherein the operation of the image carrier in the thrust direction and the operation of the cleaning member in the thrust direction during non-image formation are the same. 2. The image forming apparatus according to claim 1, wherein the operation of the image carrier in the thrust direction and the operation of the cleaning member in the thrust direction are reciprocating operations. 3. The image carrier rotates or does not rotate in the circumferential direction during the operation of the image carrier in the thrust direction during the non-image forming period and during the operation of the cleaning member in the thrust direction. The image forming apparatus according to claim 1. 4. An image carrier, a cleaning device that contacts the image carrier and cleans residual toner on the surface thereof, and a mechanism that causes a cleaning member of the cleaning device to reciprocate in the thrust direction on the image carrier. In the image forming apparatus, the peripheral speed of the image carrier during image formation is V1, the reciprocal cycle of the cleaning member is S1, the peripheral speed of the image carrier during non-image formation is V2, and the reciprocal cycle of the cleaning member is S.
2. The image forming apparatus according to claim 1, wherein the following relationship is satisfied: V1 <V2, S1 ≦ S2. 5. The image forming apparatus according to claim 4, wherein S1 = S2. 6. The image forming apparatus according to claim 4, wherein the relationship is satisfied only during non-image formation when a continuous image copy mode of the same transfer material size and the same image mode is set.