JP2000075567A - Image forming device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing the nonuniformity of an output image density caused by a partial change in the sensitivity of an image carrier. SOLUTION: In this image forming device, an electrifying roller (electrifying means) 2, a laser scanner (exposure means) 5, a developing unit (developing means) 6, a transfer part (transfer means) 7 and a cleaning means are disposed in order around the rotary photoreceptor drum (image carrier) 1. In this case, the cleaning means is composed of at least a waste-toner storage part 11, a cleaning blade (elastic blade) 3 disposed to be abutted on the surface of the photoreceptor drum 1 and a scooping member 10. When image forming operation is not carrier out, the photoreceptor drum 1 is intermittently rotated and the moving amount of the surface of the photoreceptor drum 1 at a time during the intermitted rotation of the photoreceptor drum 1 is at least equal to or larger than an interval between the cleaning blade 3 and scooping member 10.

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 printer, a copying machine, a facsimile or the like which employs an electrophotographic system, and a process cartridge used for the same.

[0002]

2. Description of the Related Art FIG. 12 shows an example of a conventional image forming apparatus for performing an image forming operation.

FIG. 11 is a schematic sectional view of a conventional image forming apparatus. A photosensitive drum 1 as an image carrier is rotatably mounted on the illustrated image forming apparatus. A charging roller 2 as a contact charging member and a cleaning blade 3 as a cleaning member are in contact with each other.

An oscillating voltage obtained by superimposing an AC voltage and a DC voltage is applied to the photosensitive drum 1 via a charging roller 2.
As a result, the peripheral surface of the photosensitive drum 1 is subjected to a contact charging process and given a predetermined charge.

Next, scanning exposure is performed on the charged surface of the photosensitive drum 1 by a laser beam emitted from a laser scanner 5 based on information from a control unit 4 which analyzes output information from an external device and develops the output data into output data. Then, an electrostatic latent image corresponding to the target image information is formed on the photosensitive drum 1. Then, the electrostatic latent image formed on the photosensitive drum 1 is developed by a developing device 6 arranged to face the photosensitive drum 1 and is visualized as a toner image.

On the other hand, the toner image formed on the photosensitive drum 1 is transferred to the recording paper 9 conveyed to the transfer unit 7 at an appropriate timing, and the recording paper 9 after the transfer of the toner image is transferred to the fixing unit 8. The sheet is conveyed and discharged outside the apparatus after the toner image is fixed in the fixing section 8.

The toner remaining on the photosensitive drum 1 at the time of transfer is scraped off by the cleaning blade 3 before the photosensitive drum 1 is charged again. The scraped toner is collected by the rake member 10 arranged in contact with the photosensitive drum 1 and accumulated in the waste toner storage unit 11. Here, the rake member 10 also serves to prevent leakage of toner from the waste toner container 11.

Incidentally, there is a place at both ends of the photosensitive drum 1 where neither the cleaning blade 3 nor the rake member 10 comes into contact. In order to prevent leakage of waste toner from a gap formed at this place, FIG. As described above, the toner leakage prevention member 12 formed of felt or the like is attached. In any of the image forming apparatuses, the space between the photosensitive drum 1 and the waste toner accommodating section 11 is tightly sealed in order to prevent leakage of waste toner from around the photosensitive drum 1.

[0009]

Here, the photosensitive drum 1
FIG. 13 shows a cross section of the photosensitive drum 1. As the photosensitive drum 1, a conductive drum 13 in which an undercoat layer 14, a charge generation layer 15, and a charge transport layer 16 are sequentially laminated is generally used.
This type of photosensitive drum 1 has photosensitivity, and is particularly called an organic photoreceptor because an organic substance is used as a material of the charge generation layer 15 and the charge transport layer 16.

Incidentally, it is known that various characteristics of the organic photoreceptor change depending on the ambient temperature and humidity.

FIGS. 14 and 15 show how the potential (VL) changes when the organic photosensitive member is charged to a certain potential and then exposed to a certain amount of light with temperature and humidity. It is.

The characteristics of the organic photoreceptor often change slowly but not instantaneously when the environment changes. This is affected by the incompatibility of the material used in the organic photoreceptor with the environment, and organic photosensitive materials having higher environmental adaptability are being actively studied.

In the conventional image forming apparatus shown in FIG. 11, the surface of the photosensitive drum 1 is exposed from the waste toner accommodating section 11 and the surface of the photosensitive drum 1 is exposed to the waste toner accommodating section 11 and the cleaning blade 3. Then, there is a portion facing the space closed by the rake member 10 and the toner leakage prevention member 12. When the temperature and humidity around the photosensitive drum 1 are changed and the photosensitive drum 1 is left in the environment for a certain period of time, the speed (aging speed) at which the photosensitive drum 1 adapts to the environment inside and outside the container differs. Happens. This is because the temperature and humidity changes in the closed space around the cleaning means and in the other open space are different from each other, and the potential (VL) on the circumference of the photosensitive drum 1 is different from that of other portions. Part can be.

When an image is formed on the photosensitive drum 1 in such a state, a portion having a different potential (VL) as shown in FIG.
(1), density unevenness on the image occurs, and the image quality is remarkably deteriorated. However, the potential (VL) difference generated over the entire circumference of the photosensitive drum 1 gradually decreases as the aging of the surface of the photosensitive drum 1 facing the space inside the cartridge container progresses as time passes to the environment.

The change in the potential (VL) of the photosensitive drum 1 due to the temperature and humidity is caused not only when the image forming apparatus is moved to a different environment but also when the image forming apparatus performs an image forming operation. This may also occur when the temperature and humidity inside the apparatus change when there is a standby time.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide an image forming apparatus capable of preventing uneven density of an output image due to a partial sensitivity change of an image carrier. It is to provide a device.

A second object of the present invention is to provide an image forming apparatus capable of preventing uneven image density due to different aging speeds of image carriers.

A third object of the present invention is to provide an image forming apparatus capable of switching from a low power consumption mode to a normal power consumption mode and preventing image density unevenness occurring when performing image formation. Is to do.

A fourth object of the present invention is to provide an image forming apparatus capable of prolonging the life of an image carrier by minimizing the number of rotations of the image carrier other than during image formation. .

A fifth object of the present invention is to provide a process cartridge capable of preventing image density unevenness and facilitating maintenance and replacement of consumable parts in an image forming apparatus.

[0021]

In order to achieve the above object, according to the first aspect of the present invention, a charging means, an exposing means, a developing means, a transferring means, and a cleaning means are sequentially arranged around a rotatable image carrier. In the image forming apparatus provided, the cleaning means comprises at least a waste toner container and an elastic blade and a rake member disposed in contact with the surface of the image carrier, and when the image forming operation is not performed, The image carrier is intermittently rotated, and the amount of one movement of the image carrier surface during the intermittent rotation of the image carrier is controlled to be at least equal to or more than the interval between the elastic blade and the rake member. It is characterized by the following.

According to a second aspect of the present invention, in the first aspect of the present invention, a cooling fan for controlling a temperature rise in the apparatus is provided, the image forming operation is not performed, and the cooling fan operates. In this case, the image carrier is controlled so as to perform intermittent rotation.

According to a third aspect of the present invention, in the first aspect of the present invention, first control means for analyzing output information from an external device and expanding the output information into output data, and an image forming operation based on the output data And a switching unit for switching a power consumption state of the second control unit between a normal power consumption mode and a low power consumption mode, wherein the image carrier is intermittently connected at least in the low power consumption mode. It is characterized in that it is controlled to perform a specific rotation.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a means for detecting the number of intermittent rotations of the image carrier or a process after the intermittent rotation of the image carrier is started. A means for detecting time is provided, and based on information obtained from the detecting means, control is performed such that intermittent rotation of the image carrier is stopped at a predetermined number of rotations or elapsed time.

According to a fifth aspect of the present invention, there is provided a process cartridge which is detachably attached to an image forming apparatus main body, and is constituted by integrating at least an image carrier and a cleaning means, wherein the cleaning means is at least a waste toner accommodating portion. And an elastic blade and a rake member disposed in contact with the surface of the image carrier, and when the image forming operation is not performed, the image carrier is intermittently rotated to intermittently rotate the image carrier. It is characterized in that the amount of one movement of the surface of the image carrier during a typical rotation is controlled to be at least equal to or more than the interval between the elastic blade and the rake member.

Therefore, according to the first aspect of the present invention, even when the image forming operation is not performed, the image carrier is closed by the surface of the image carrier, the waste toner container that covers the image carrier, the elastic blade, and the rake member. Since the surface of the specific image carrier does not stay for a long time in the space where the image is formed, even when the temperature and humidity around the image carrier change, partial potential fluctuation of the image carrier is less likely to occur, and image forming is performed. The density unevenness of an output image due to a change in temperature and humidity in the apparatus is prevented. In addition, since the image carrier surface is controlled so as to move by a necessary amount at a time with respect to a predetermined time, the rotation is continuously performed with a small movement amount so that the same movement amount can be secured within a predetermined time. The frequency of rotation can be reduced as compared with the case where the control is performed, the power consumption required for rotating the image carrier is reduced, and the operation noise of the apparatus is reduced.

According to the second aspect of the present invention, the air flow in the apparatus formed when the cooling fan provided in the image forming apparatus rotates can be blown only to the specific image carrier surface when the image carrier is stopped. Disappears, the surface of the image carrier, a waste toner container that covers the image carrier, an elastic blade,
The image density unevenness which occurs due to the difference in the aging speed of the image carrier between the space closed by the rake member and the other exposed portion can be prevented.

According to the third aspect of the present invention, even when the image forming apparatus does not form an image and is in a low power consumption mode in which the image carrier is not rotated, the surface of the image carrier and the image carrier can be used. The specific image carrier surface does not stay for a long time in the space closed by the waste toner container, the elastic blade, and the rake member that covers the waste toner container, and the temperature and humidity changes in the apparatus after the image forming operation. Thus, unevenness in image density due to a change in sensitivity of the image carrier in the space and other exposed portions can be prevented.

According to the fourth aspect of the present invention, the number of rotations of the image carrier is kept to a minimum even when the image forming apparatus is left for a long time in a standby state in which no image forming operation is performed. The wear of the image carrier due to rubbing with an elastic blade or the like abutting on the surface of the carrier is suppressed, and the life of the image carrier can be extended.

According to the fifth aspect of the invention, it is possible to prevent uneven image density caused by a partial change in the sensitivity of the image carrier, and to facilitate maintenance and replacement of consumable parts in the image forming apparatus. Can be achieved.

[0031]

<First Embodiment> FIG. 1 is a schematic sectional view of an image forming apparatus according to a first embodiment of the present invention.
In the image forming apparatus according to the present embodiment, when the image forming operation is not performed, the amount of movement of the surface of the photosensitive drum 1 in one rotation operation as a sequence for preventing image density unevenness is equal to or larger than the gap formed by the cleaning blade 3 and the rake member 10. As shown in FIG. 2, the photosensitive drum 1 is rotated every predetermined time (t ₀ ).

Thus, also in the image forming apparatus according to the present embodiment, the photosensitive drum 1 as an image carrier is rotatably mounted, and the photosensitive drum 1 has a charging roller 2 as a contact charging member. And a cleaning blade 3 as a cleaning member.

An oscillating voltage obtained by superimposing an AC voltage and a DC voltage is applied to the photosensitive drum 1 via a charging roller 2.
As a result, the peripheral surface of the photosensitive drum 1 is subjected to a contact charging process and given a predetermined charge.

Next, scanning exposure is performed on the charged surface of the photosensitive drum 1 by a laser beam emitted from a laser scanner 5 based on information from a control unit 4 which analyzes output information from an external device and develops it into output data. Then, an electrostatic latent image corresponding to the target image information is formed on the photosensitive drum 1. Then, the electrostatic latent image formed on the photosensitive drum 1 is developed by a developing device 6 arranged to face the photosensitive drum 1 and is visualized as a toner image.

On the other hand, the toner image formed on the photosensitive drum 1 is transferred to the recording paper 9 conveyed to the transfer unit 7 at an appropriate timing, and the recording paper 9 after the transfer of the toner image is transferred to the fixing unit 8. The sheet is conveyed and discharged outside the apparatus after the toner image is fixed in the fixing section 8.

The toner remaining on the photosensitive drum 1 at the time of transfer is scraped off by the cleaning blade 3 before the photosensitive drum 1 is charged again. The scraped toner is collected by the rake member 10 arranged in contact with the photosensitive drum 1 and accumulated in the waste toner storage unit 11. Here, the distance between the contact portion of the cleaning blade 3 on the photosensitive drum 1 and the contact portion of the rake member 10 was 10 mm in terms of the drum circumference.

Incidentally, there are places at both ends of the photosensitive drum 1 where neither the cleaning blade 3 nor the rake member 10 comes into contact. To prevent leakage of waste toner from gaps formed at these places, FIG. As described above, the toner leakage prevention member 12 formed of felt or the like is attached.

As shown in FIG. 4, a charge generating layer 1b made of a phthalocyanine compound having a thickness of 0.2 μm is formed on a metal core 1a made of aluminum having a diameter of 40 mm. A so-called organic photoreceptor obtained by forming a charge transport layer 1c in which a hydrazone compound is dispersed in a polycarbonate having a thickness of 20 μm as a binder was used as an upper layer.

In order to reduce the frictional resistance between the photosensitive drum 1 and the cleaning blade 3 during rotation of the photosensitive drum 1, the charge transport layer 1c is provided with a Teflon made of PTFE particles having a particle diameter of about 0.3 μm. A lubricating substance such as (trade name) may be dispersed.

On the other hand, as shown in FIG. 1, a cooling fan 17 is mounted on the image forming apparatus according to the present embodiment, so that outside air flows in through an air inlet 18 provided on a side surface of the image forming apparatus and is discharged. The fixing unit 8
The temperature in the apparatus is prevented from excessively rising due to the heat generated by the above.

Further, the power switch of the image forming apparatus is turned off.
Even if the power supply is turned off, the cooling fan 17 is controlled so as to continue to operate for 30 minutes immediately after the power switch is turned off, in order to suppress the temperature rise in the apparatus.

In the image forming apparatus according to the present embodiment, as a sequence for preventing image density unevenness, a single movement of the surface of the photosensitive drum 1 is at least equal to a gap formed by the cleaning blade 3 and the rake member 10. As described above, the amount of movement of the surface of the photosensitive drum 1
And rake member 10 with contact portion of cleaning blade 3
Is calculated from a value of 10 mm, which is converted into a drum circumferential length, and the photosensitive drum 1 is rotated at an angle of 30 ° every three minutes.

The execution of the image density unevenness prevention sequence and the determination of the stop are performed according to the flowchart shown in FIG. However, in the image forming apparatus according to the present embodiment, 1) the image forming apparatus does not perform an image forming operation and is in a standby state. 2) After the power of the image forming apparatus is turned off, the cooling fan 17 operates. If there is, it is determined that image formation is not being performed, and the above-described image density unevenness prevention sequence is executed.

Incidentally, in order to confirm the effect of controlling the density unevenness of the output image in the image forming apparatus according to the present embodiment, 10 ° C./10% (under a low temperature and low humidity environment) and 25 ° C./6
In the three environments of 0% (under normal temperature and normal humidity environment) and 35 ° C./90% (under high temperature and high humidity environment), ON / O of the above-described density unevenness prevention sequence is performed using the image forming apparatus according to the present embodiment.
After performing FF and forming an image of 50 sheets of A4 size, each was left for 30 minutes in a standby state. The results are shown in the table below.

In the following table, a halftone image is output after standing, and if density unevenness occurs in one cycle of the photosensitive drum on the halftone image, x indicates slight density unevenness. Is indicated as △, and 発 生 if not occurring is indicated as ○.

[0046] …: Not generated △: Slightly generated ×: Clearly generated As shown in the above table, when the image density unevenness prevention sequence was executed, no density unevenness was generated in the output image. If not performed, severe concentration unevenness occurs particularly in a low-temperature and low-humidity environment.

A similar experiment was conducted by extending the feed time of one rotation of the photosensitive drum during the density unevenness prevention sequence from 3 minutes to 5 minutes. In a low-temperature and low-humidity environment, as shown in FIG. Multiple density unevenness occurred. This is because the same surface of the photosensitive drum 1 is long in the space closed by the surface of the photosensitive drum 1, the waste toner accommodating section 11 covering the photosensitive drum 1, the cleaning blade 3, the rake member 10 and the toner leakage prevention member 12. Because they stayed too much,
This is because a partial change in the sensitivity of the photosensitive drum 1 occurred in response to a change in temperature and humidity in the image forming apparatus.

Therefore, the pause time of one rotation of the photosensitive drum in the density unevenness prevention sequence must be kept within a time period in which the sensitivity of the photosensitive drum 1 does not change for the above-described reason.

A similar experiment was performed with the rotation time of the photosensitive drum 1 once set to 15 ° while the feeding time of one rotation of the photosensitive drum during the density unevenness prevention sequence was 3 minutes. As shown in FIG. 7, horizontal band-shaped density unevenness having a width of about 50 mm occurred in the output image. this is,
Since the amount of one rotation of the photosensitive drum 1 is insufficient, the surface of the photosensitive drum 1 and the waste toner storage 11
This is because the surface of the photosensitive drum 1 that stays for a relatively long time in the space closed by the cleaning blade 3, the rake member 10, and the toner leakage prevention member 12 is formed.

Therefore, the amount of one rotation of the photosensitive drum in the density non-uniformity prevention sequence is determined by the previous movement of the photosensitive drum 1 and the waste toner container 1 covering the photosensitive drum 1.
And setting the cleaning blade 3 and the surface of the photosensitive drum 1 located in the space closed by the rake member 10 and the toner leakage prevention member 12 to be as large as possible within a range in which the surface of the photosensitive drum 1 is not located in the same space in the next movement. Is desirable.

In the image forming apparatus according to the present embodiment, when the image forming operation is not performed, the photosensitive drum 1 is intermittently rotated as a density unevenness preventing sequence to cover the surface of the photosensitive drum 1 and the photosensitive drum 1. A waste toner container 11,
A case where the surface of a specific photosensitive drum 1 does not stay for a long time in a space closed by the cleaning blade 3, the rake member 10 and the toner leakage preventing member 12, and the temperature and humidity around the photosensitive drum 1 change. However, it was possible to prevent the density unevenness of the output image from occurring.

Also, in order to control the amount of one movement of the surface of the photosensitive drum 1 during rotation to be equal to or longer than the interval between the cleaning blade 3 and the rake member 10, the photosensitive drum 1 is moved by the same amount within a predetermined time. The frequency of rotation could be reduced as compared with the case where the rotation control was continuously performed with a small moving amount. For this reason, the electric power required for rotating the photosensitive drum 1 was reduced, and the operation noise of the apparatus was reduced.

Second Embodiment Next, a second embodiment of the present invention will be described.

The image forming apparatus according to the second embodiment changes the power consumption state of the control means for performing an image forming operation to the image forming apparatus according to the first embodiment to a normal power consumption mode and a low power consumption mode. Switching means for switching is added, and the image density non-uniformity prevention sequence is set to 3 every 3 minutes except during the image forming operation including the low power consumption mode.
Control is performed so that the photosensitive drum 1 is rotated by 0 °.

In the image forming apparatus according to the present embodiment, 1) when the image forming apparatus does not perform the image forming operation and the standby state continues for 3 minutes 2) After the power of the image forming apparatus is turned off, the cooling fan 17 3) Control is performed so that the image density unevenness prevention sequence is executed only in the low power consumption mode.

The power consumption state is switched between the normal power consumption mode and the low power consumption mode by the switching means when the standby state after the end of the image forming operation continues for 15 minutes. Further, when the image forming command is issued again in the low power consumption mode, the mode is immediately switched from the low power consumption mode to the normal power consumption mode, and the image forming operation is started.

Further, the image forming apparatus according to the present embodiment includes means for detecting the number of rotations of the photosensitive drum 1 in the above-described image density unevenness prevention sequence, and performs the photosensitive drum intermittently at a predetermined number of rotations. Control is performed so as to stop the rotation of No. 1. For this reason, for example, the maximum number of rotations of the photosensitive drum 1 in the image density unevenness prevention sequence is set to 15 times in advance, and 15) from the standby state of 1) in 15 minutes.
When the state of the image forming apparatus changes to the low power consumption mode, the rotation of the photosensitive drum 1 is performed five times during the standby state of 1), and the remaining time remains after the transition to the low power consumption mode of 3). Is controlled to be performed ten times.

The rotation operation of the photosensitive drum 1 in the image density unevenness prevention sequence is performed continuously until the image forming operation of the image forming apparatus ends and, for example, the temperature and humidity changes in the apparatus settle down. It is important to set the maximum number of rotations.

In this embodiment, in order to determine the maximum number of rotations, 50 sheets of A4 size paper are continuously printed in a low-temperature and low-humidity environment where the density unevenness is most remarkable in the image forming apparatus according to the first embodiment. Of the photosensitive drum 1 and the waste toner container 11 covering the photosensitive drum 1
Then, changes in temperature and humidity in the space closed by the cleaning blade 3, the rake member 10 and the toner leakage prevention member 12, and the other areas near the photosensitive drum 1 were examined. Changes in temperature and humidity over time are shown in FIG. 8 and FIG.
Paying attention to the fact that the temperature and humidity in the image forming apparatus become constant within about a minute, the photosensitive drum 1
It was determined to operate 15 times at an angle of 30 ° with a pause time of one minute.

In order to examine the life extension effect of the photosensitive drum 1 in the image forming apparatus according to the present embodiment, the case where the maximum number of rotations of the photosensitive drum 1 is restricted during the image density unevenness prevention sequence and the case where it is not performed Comparative durability was performed. The endurance was performed in a high-temperature and high-humidity environment. After printing 50 sheets continuously in A4 size, the printer was left for 3 hours (15 minutes in a standby state and 2 hours and 45 minutes in a low power consumption mode) to make one cycle. The cycle was to be repeated.

As a result, when the maximum number of rotations of the photosensitive drum 1 was not regulated, black vertical stripes were generated in the output image after forming about 6,200 images. This is the photosensitive drum 1
Since a large number of scratches were formed on the surface of the image forming apparatus, the charging by the charging roller 2 was not sufficiently performed at this portion, and the image appeared as a defective image.

On the other hand, in the case where the maximum number of rotations of the photosensitive drum 1 was restricted, the same decrease in defectiveness occurred at about 7100, and it was determined that the life had been reached at this point.

As described above, in the image forming apparatus according to the present embodiment, by reducing the number of rotations of the photosensitive drum 1 in the density unevenness prevention sequence as much as possible, wear of the photosensitive drum 1 is suppressed and the life thereof is extended. I was able to.

By maintaining the necessary and sufficient amount of rotation of the drum as a density unevenness prevention sequence, even if the temperature and humidity around the photosensitive drum 1 change, the first embodiment can be used.
As in the case of the image forming apparatus according to (1), the density unevenness of the output image can be suppressed.

Further, in order to perform control so that the amount of one movement of the surface of the photosensitive drum 1 during rotation is equal to or longer than the interval between the cleaning blade 3 and the rake member 10, the photosensitive drum 1 is moved by the same amount within a predetermined time. The frequency of rotation could be reduced as compared with the case where the rotation control was continuously performed with a small moving amount. For this reason, the electric power required for rotating the photosensitive drum 1 was reduced, and the operation noise of the apparatus was reduced.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 10 is a sectional view of the process cartridge according to the present invention.

The image forming apparatus according to the present embodiment differs from the image forming apparatus according to Embodiment 1 in that, as shown in FIG. 10, the photosensitive drum 1, the charging roller 2, the cleaning blade 3, the rake member 10, the waste The image forming operation is performed by integrating the toner container 11 and the toner leakage preventing member 12 into a process cartridge 13 and mounting the process cartridge 13 in an image forming apparatus main body.

In the image forming apparatus and the process cartridge 13 according to this embodiment, when the image forming operation is not performed, the photosensitive drum 1 provided in the process cartridge 13 is intermittently rotated as an image density unevenness preventing sequence. As a result, the surface of the photosensitive drum 1 of the process cartridge 13 and the waste toner container 10
The surface of the specific photosensitive drum 1 is prevented from staying for a long time in the space closed by the cleaning blade 3, the rake member 10 and the toner leakage preventing member 12, and the temperature and humidity around the photosensitive drum 1 are changed. Even in such a case, density unevenness does not occur in the output image.

Further, in order to perform control so that the amount of one movement of the surface of the photosensitive drum 1 during rotation is equal to or longer than the interval between the cleaning blade 3 and the rake member 10, the photosensitive drum 1 is moved by the same amount within a predetermined time. The frequency of rotation could be reduced as compared with the case where the rotation control was continuously performed with a small moving amount. For this reason, the electric power required for rotating the photosensitive drum 1 was reduced, and the operation noise of the apparatus was reduced.

Further, by adopting the process cartridge system, it is possible to simplify procedures such as replacement of consumable parts such as the photosensitive drum 1 and processing of waste toner accumulated in the waste toner storage unit 11.

[0071]

As is apparent from the above description, claim 1
According to the described invention, even when the image forming operation is not performed,
Since the specific image carrier surface does not stay for a long time in the space closed by the image carrier surface, the waste toner container that covers the image carrier, the elastic blade, and the rake member, the image carrier Even when the temperature and humidity around the body change, partial potential change of the image carrier hardly occurs, and the density unevenness of the output image due to the change in temperature and humidity in the image forming apparatus is prevented. In addition, since the image carrier surface is controlled so as to move by a necessary amount at a time with respect to a predetermined time, the rotation is continuously performed with a small movement amount so that the same movement amount can be secured within a predetermined time. The frequency of rotation can be reduced as compared with the case where the control is performed, the power consumption required for rotating the image carrier is reduced, and the operation noise of the apparatus is reduced.

According to the second aspect of the present invention, when the cooling fan provided in the image forming apparatus rotates, the airflow in the apparatus can be blown only to the surface of the specific image carrier when the image carrier is stopped. Disappears, the surface of the image carrier, a waste toner container that covers the image carrier, an elastic blade,
The image density unevenness which occurs due to the difference in the aging speed of the image carrier between the space closed by the rake member and the other exposed portion can be prevented.

According to the third aspect of the present invention, even when the image forming apparatus is in a low power consumption mode in which the image forming apparatus does not form an image and the image carrier is not rotated, the surface of the image carrier and the image carrier are not affected. The specific image carrier surface does not stay for a long time in the space closed by the waste toner container, the elastic blade, and the rake member that covers the waste toner container, and the temperature and humidity changes in the apparatus after the image forming operation. Thus, unevenness in image density due to a change in sensitivity of the image carrier in the space and other exposed portions can be prevented.

According to the fourth aspect of the present invention, the number of rotations of the image carrier is kept to a minimum even when the image forming apparatus is left for a long time in a standby state in which no image forming operation is performed. The wear of the image carrier due to rubbing with an elastic blade or the like abutting on the surface of the carrier is suppressed, and the life of the image carrier can be extended.

According to the fifth aspect of the invention, it is possible to prevent uneven image density caused by a partial change in the sensitivity of the image carrier, and to facilitate maintenance and replacement of consumable parts in the image forming apparatus. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating timing of intermittent rotation of a photosensitive drum in the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 3 is a partial perspective view showing an arrangement of a toner leakage prevention member in the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 4 is a sectional view of a photosensitive drum used in the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 5 is a flowchart illustrating a procedure for determining whether to execute / stop intermittent rotation of the photosensitive drum in the image forming apparatus according to Embodiment 1 of the present invention;

FIG. 6 is a diagram illustrating a defective image obtained by an experiment performed using the image forming apparatus according to the first embodiment of the present invention;

FIG. 7 is a diagram illustrating a defective image obtained by an experiment performed using the image forming apparatus according to the first embodiment of the present invention;

FIG. 8 is a diagram illustrating a temperature transition inside the image forming apparatus under a low-temperature and low-humidity environment according to a second embodiment of the present invention;

FIG. 9 is a diagram showing a temperature transition inside the image forming apparatus in a low-temperature and low-humidity environment according to a second embodiment of the present invention;

FIG. 10 is a sectional view of a process cartridge according to the present invention.

FIG. 11 is a schematic sectional view of a conventional image forming apparatus.

FIG. 12 is a partial perspective view illustrating an arrangement of a toner leakage prevention member in a conventional image forming apparatus.

FIG. 13 is a sectional view of a photosensitive drum (organic photosensitive body) used in the image forming apparatus.

FIG. 14 is a diagram showing the temperature dependence of the potential (VL) of the organic photoconductor.

FIG. 15 is a diagram showing the humidity dependence of the potential (VL) of the organic photoconductor.

FIG. 16 is a diagram illustrating a defective image sample in a conventional image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum (image carrier) 2 charging roller (charging means) 3 cleaning blade (elastic blade) 4 control means 5 laser scanner (exposure means) 6 developing device (developing means) 7 transfer unit (transfer means) 10 rake member 11 Waste toner storage unit 12 Toner leakage prevention member 13 Process cartridge 17 Cooling fan

Claims (5)

[Claims] A charging means provided around a rotatable image carrier;
In an image forming apparatus in which an exposing unit, a developing unit, a transferring unit, and a cleaning unit are sequentially disposed, the cleaning unit includes at least a waste toner storage unit and an elastic blade and a rake member disposed in contact with the surface of the image carrier. When the image forming operation is not performed, the image carrier is intermittently rotated, and the amount of movement of the surface of the image carrier during one intermittent rotation of the image carrier is at least An image forming apparatus, wherein the distance between the elastic blade and the rake member is controlled to be equal to or greater than the distance between the elastic blade and the rake member. 2. A cooling fan for controlling a temperature rise in the apparatus, wherein an image forming operation is not performed, and the image carrier is intermittently rotated when the cooling fan is operating. 2. The image forming apparatus according to claim 1, wherein the control is performed in such a manner. 3. A first control means for analyzing output information from an external device and developing the output data into output data; a second control means for performing an image forming operation based on the output data;
Switching means for switching the power consumption state of the control means between the normal power consumption mode and the low power consumption mode, and performing control such that the image carrier is rotated intermittently at least in the low power consumption mode. The image forming apparatus according to claim 1. 4. A means for detecting the number of intermittent rotations of the image carrier or a means for detecting an elapsed time from the start of the intermittent rotation of the image carrier is provided. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled to stop the intermittent rotation of the image carrier by a predetermined number of rotations or an elapsed time based on the information. 5. The image forming apparatus is detachable from a main body of the image forming apparatus,
In a process cartridge configured to integrate at least an image carrier and a cleaning unit, the cleaning unit includes at least a waste toner storage unit and an elastic blade and a rake member disposed in contact with the surface of the image carrier. When the image forming operation is not performed, the image carrier is intermittently rotated, and the amount of one movement of the image carrier surface during the intermittent rotation of the image carrier is at least as large as the elastic blade. A process cartridge characterized in that it is controlled to be longer than an interval formed by a rake member.