JP2001075433A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent image abnormality while suppressing the increase of toner consumption and the decline of the service life of a photosensitive drum by changing the frequency of executing a removal operation for removing the case of generating the image abnormality based on the frequency of generating the image abnormality. SOLUTION: Based on the frequency of generating the image abnormality, the frequency of executing the removal operation for removing the cause of generating the image abnormality is changed. A third operation mode for executing the removal operation for removing the generation cause of image flowing is executed by allowing a user to perform input from an operation part 36. Then, in this image formation device, since the image abnormality is generated in the past when the execution record of the third operation mode is stored in a storage device 34, the number of times of executing the third operation mode is confirmed from the storage device 34 and the width (amount) of a black belt is decided based on the number of times of executing it. In this case, the width of the black belt is widened at the time of increasing the strength of the removal operation and the width of the black belt is narrowed at the time of decreasing the strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus for forming an image recorded on a document on a recording medium.

[0002]

2. Description of the Related Art Electrophotographic image forming apparatuses such as copiers and printers have been widely used. An example of a conventional image forming apparatus will be described with reference to FIG.

FIG. 8 is a schematic diagram showing an example of a conventional image forming apparatus. The image forming apparatus 10 includes a photosensitive drum 12 on which an electrostatic latent image is formed. This photosensitive drum 12
Is generally a drum or belt made of a material such as OPC, selenium, or silicon, and rotates at a predetermined process speed in the direction of arrow A.

[0004] Above the photosensitive drum 12, the secondary charging device 1
The primary charging device 16 is supplied with a high voltage from a high voltage power supply 24 so as to uniformly charge the photosensitive drum 12 to a predetermined potential. Primary charging device 1
The photosensitive drum 12 uniformly charged by 6 is irradiated with light for forming a margin (non-image area) of the recording paper by a blank exposure device 26 (hereinafter, referred to as “blank exposure”). In the portion where the blank exposure has been performed, the potential decreases and a non-image area is formed.

[0005] A developing device 14 is arranged on the upstream side in the rotation direction of the photosensitive drum 12 (on the right side of the photosensitive drum 12 in the plane of FIG. 8). The developing device 14 includes the charged photosensitive drum 1
2 is a device for supplying a toner to the toner image forming apparatus 2 to form a toner image. Further, below the photosensitive drum 12, the photosensitive drum 12
A transfer charger 18 that charges the recording paper in order to transfer the toner image formed on the recording paper to the recording paper is disposed.

On the downstream side in the rotation direction of the photosensitive drum 12, the toner remaining on the photosensitive drum 12 after the transfer is transferred to the photosensitive drum 1.
A cleaning device 20 for removing from the cleaning device 2 is provided. The cleaning device 20 includes a cleaning blade 22 that contacts the photosensitive drum 12, and the toner remaining on the photosensitive drum 12 is scraped off by the cleaning blade 22. The image forming apparatus 10 is also provided with an exhaust fan (not shown) for exhausting ozone generated from the primary charging device 16, and a driving device (not shown) for rotating the photosensitive drum 12 and the developing device 14. I have.

[0007] Such an image forming apparatus 10 is used under various conditions, such as an environment where the temperature and humidity are different, and the properties of the recording paper used are different.

[0008] When the image forming apparatus 10 is used in a high-humidity and high-temperature environment under such conditions, a part of the copy image appears to be washed away by water. May occur. "Image flow"
Generally, it occurs when acidic paper is used as recording paper.
The cause of this generation is that additives and paper dust contained in the acidic paper adhere to the surface of the photosensitive drum, and they react with ozone generated by the charging device and moisture in the surrounding air for a certain period of time, As a result, the resistance of the photosensitive drum surface is reduced.

[0009] The above-mentioned "image flow" is, for example, such that immediately after a continuous copy for continuously forming an image on a plurality of recording papers is completed, the power is turned off and left for several hours or more, and then the copy is restarted. Easy to occur in case. The reason is that while the image forming apparatus is performing the copying operation, the ozone generated around the charging device is exhausted by the exhaust fan, but when the power is turned off immediately after the continuous copying is completed, the exhaust fan is exhausted. Also, the ozone is not exhausted and the remaining ozone adheres to the photosensitive drum. Several techniques have been proposed as general measures for preventing "image deletion".

As one of such techniques, there is known a technique of sufficiently exhausting the inside of an image forming apparatus and quickly discharging ozone generated in a charging device.

As a countermeasure for preventing "image deletion", a heater is used to maintain the temperature around the photosensitive drum at a certain level or more, thereby promoting the decomposition of ozone by heat and reducing the amount of water vapor around the photosensitive drum. The technology is also known. However, in this technique, it is necessary to keep the heater energized even when the main body power is off. Therefore, several to several tens of watts of power are constantly consumed. Therefore, this technique has a problem that it is contrary to the demand for energy saving recently desired.

An organic photosensitive drum used as a photosensitive drum of a medium to low speed image forming apparatus generally undergoes a specific deterioration when left in a high temperature state. for that reason,
There is a limit to the time during which the temperature around the photosensitive drum is increased by using the heater, and the effect of countermeasures against "image deletion" may not be sufficiently exhibited. In addition, as another technique for countermeasures against "image deletion", the photosensitive drum was rotated during warm-up immediately after the power was turned on, and the photosensitive drum surface was slightly scraped off with a cleaning blade of a cleaning device, and adhered to the photosensitive drum surface. Techniques have also been adopted in which additives and paper dust are scraped off to return this surface to a normal state. However, in order to prevent “image deletion” during rotation during warm-up, it generally takes several tens of seconds to several minutes. However, in recent image forming apparatuses, the warm-up time is shortened to improve copy productivity. Therefore, the warm-up time is several tens of seconds to several seconds for a short one.
May not be sufficiently prevented. In this case, if the idle rotation is performed until the "image deletion" can be prevented, the "image deletion" can be prevented, but the copy productivity is reduced.

Therefore, a so-called "black belt mode" is sometimes used as a technique for preventing "image deletion" during idling of the photosensitive drum. The “black belt mode” is a technique in which toner is used as an abrasive when the surface of a photosensitive drum is shaved by a cleaning blade. In "Black Belt Mode"
At the beginning of idle rotation, a developed image is formed on the photosensitive drum with a small amount of toner, the photosensitive drum is rotated without transferring the developed image to recording paper, and the toner forming the developed image is removed by a cleaning blade. Is used as an abrasive, whereby the photosensitive drum is easily shaved.

The "black belt mode" will be described with reference to FIG.

FIG. 9 is a timing chart showing the sequence of the "black belt mode".

When the driving device is turned on, the photosensitive drum 12
(See FIG. 8) and the developing device 14 starts to rotate. Thereafter, electricity is supplied from the high-voltage power supply 24 to the primary charging device 16 for a fixed period of time to uniformly charge the photosensitive drum 12. The uniformly charged photosensitive drum 12 is exposed by a blank exposure unit 26. The exposed portion drops to almost zero potential, and becomes a non-image area where no image is formed. The non-image area is not formed by stopping the blank exposing device 26 for a fixed time, and the image potential portion where the toner adheres is changed to the photosensitive drum 12.
Formed over the entire surface of the substrate.

While the developing device 14 is not performing development, a back bias voltage for suppressing development is applied to the developing device 14. In the developing section 14a, which is a space between the developing device 14 and the photosensitive drum 12, when the image potential portion passes, toner is supplied from the developing device 14 to perform development. The back bias voltage applied to the developing device 14 is switched to the developing bias voltage at the timing when the image potential portion passes through the developing unit 14a. As a result, the toner is electrostatically attracted to the image potential portion of the photosensitive drum 12 to form a developed image. After the image potential portion has passed through the developing portion 14a, the developing bias voltage is returned to the back bias voltage.

Even if the developed image reaches above the transfer charger 18 with the rotation of the photosensitive drum 12, transfer to the recording paper is not performed. Therefore, no high voltage is applied to the transfer charger 18. Also, no recording paper is supplied. As a result, the toner of the developed image is carried to the cleaning blade 22 as the photosensitive drum 12 rotates, and is removed from the photosensitive drum 12 by the cleaning blade 22. A part of the removed toner is held as an abrasive by the cleaning blade 22 and scrapes the surface of the photosensitive drum 12. The above is one operation of the black belt mode.

FIG. 10 is a flowchart showing the black belt mode. When the black belt mode is started (S30), the operation of the black belt mode is executed as described above (S32).

Here, since the amount of toner supplied in one operation of the black band mode may be insufficient, the black band sequence can be set to be repeated a predetermined number of times. As a result, a necessary amount of toner can be supplied to the cleaning blade 22. When the black band sequence has been executed a predetermined number of times (S34), the black band mode ends (S36).

The various techniques described above are described as “image flow”
Are used singly or in combination to prevent the occurrence of phenomena.

[0022]

The above "black belt mode"
When the toner is used, the toner supplied to the cleaning blade 22 is held by the cleaning blade 22 and functions as an additive attached to the surface of the photosensitive drum or a polishing agent for paper powder, so that "image deletion" can be prevented. However, since the toner used as an abrasive is discarded as it is, there is a problem that the amount of consumed toner and the amount of discharged toner increase. Further, in the “black belt mode”, the photosensitive drum is also shaved when removing additives and paper dust attached to the surface of the photosensitive drum, so that there is a problem that the life of the photosensitive drum itself is shortened.

In order to increase the polishing ability of the toner itself without using the "black belt mode", a special toner in which the ratio of an abrasive added to the toner is increased may be used. In this case, as in the case of using the “black belt mode”, the life of the photosensitive drum is shortened, and the supply of general toner and the supply of special toner must be separated.

Further, as described above, "image deletion" tends to occur when acid paper is used. However, acidic paper is not so good in long-term preservability, so it is changing to neutral paper having excellent long-term preservability. At present, both acidic paper and neutral paper are in circulation. Specifically, the use rate of acidic paper has decreased considerably in Europe, the United States and Japan, but the use rate of acid paper is still high in Southeast Asia and the like.

As described above, the type of recording paper mainly used differs depending on the region, and the proportion of each type of recording paper also differs. Therefore, if the image forming apparatus of the common specification that has taken the above-mentioned "image deletion" measures in all regions is used, for users using neutral paper in which "image deletion" is unlikely to occur,
As described above, there is a problem that a disadvantageous state is imposed on the copy productivity, the toner consumption, and the life of the photosensitive drum. Also, even in areas where there is a lot of acidic paper distribution,
The same applies to users using neutral paper. On the other hand, if the image forming apparatuses are divided into those which have taken the "image deletion" countermeasure and those which have not taken the countermeasure according to the sales area, the problem of the regional difference can be solved. However, there is a new problem that mass productivity is reduced. In addition, users who use neutral paper in the area where the measures against "image deletion" are sold will be at a disadvantage in terms of copy productivity, toner consumption, and photosensitive drum life. The problem of forcing is not solved.

As described above, the problem of "image deletion" is related to the use environment and the properties of the paper to be used. is there.

The present invention has been made in view of the above circumstances, and has as its object to provide an image forming apparatus capable of preventing an image abnormality while suppressing an increase in toner consumption and a reduction in the life of a photosensitive drum.

[0028]

According to a first aspect of the present invention, there is provided an image forming apparatus for forming an image on a recording medium, comprising: (1) a frequency at which a predetermined image abnormality occurs; , The frequency of executing the removing operation for removing the cause of the occurrence of the predetermined image abnormality is changed.

According to a second aspect of the present invention, there is provided an image forming apparatus for forming an image on a recording medium, wherein (2) a history of occurrence of a predetermined image abnormality is provided. It is characterized in that the intensity of the removing operation for removing the cause of the occurrence of the predetermined image abnormality is changed.

A third image forming apparatus according to the present invention for achieving the above object is (3) executed when a predetermined image abnormality does not occur in an image forming apparatus for forming an image on a recording medium. A first operation mode for executing a normal image forming operation, a second operation mode for executing a first removing operation for removing a cause of the occurrence of the predetermined image abnormality and executing the normal image forming operation, and Controlling to selectively execute any one of a third operation mode for executing a selective second elimination operation for eliminating the cause of the occurrence of the predetermined image abnormality, and the third operation Control to execute the second operation mode after the mode is executed, and control to execute the first operation mode when the third operation mode is not executed. And location, (4) the first and the second
(5) The control device changes the intensity of the first removal operation based on the history stored in the storage unit. Things.

Here, (6) the control means may execute the first removal operation each time the number of times the second removal operation of the history stored in the storage means is executed exceeds a predetermined number. May be controlled so as to sequentially increase the intensity of the above.

A fourth image forming apparatus according to the present invention for achieving the above object is (7) executed when a predetermined image abnormality does not occur in an image forming apparatus for forming an image on a recording medium. A first operation mode for executing a normal image forming operation, a second operation mode for executing a first removing operation for removing a cause of the occurrence of the predetermined image abnormality and executing the normal image forming operation, and Controlling to selectively execute any one of a third operation mode for executing a selective second elimination operation for eliminating the cause of the occurrence of the predetermined image abnormality, and the third operation Control to execute the second operation mode after the mode is executed, and control to execute the first operation mode when the third operation mode is not executed. And (8) storage means for storing both the number of times the normal image forming operation has been performed and the number of times the second removal operation has been performed, and (9) the control device The intensity of the first removing operation is increased or decreased according to the ratio of the number of times the second removing operation is performed to the number of times the normal image forming operation is stored stored in the storage unit. It is characterized by being controlled.

(10) The image forming apparatus forms an electrostatic latent image on an image carrier, supplies a developer to the electrostatic latent image to form a developed image, and records the developed image. (11) The second removing operation includes applying the developer to the image carrier at a removing time other than a time during which the normal image forming operation is performed. Supply,
(12) The intensity of the second removing operation is determined according to the amount of the developer supplied to the image carrier during the removing time. It may be.

(13) The image forming apparatus forms an electrostatic latent image on an image carrier, supplies a developer to the electrostatic latent image to form a developed image, and stores the developed image in a recording medium. (14) The second removing operation includes supplying the developer to the image carrier during a removing time other than a time during which the normal image forming operation is performed. However, this operation removes the developer without transferring it to the recording medium.
(15) The intensity of the second removal operation may be determined according to the number of times of supplying a predetermined amount of developer to the image carrier during the removal time.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image forming apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of the image forming apparatus. FIG. 2 is a flowchart illustrating the operation of the image forming apparatus. The basic configuration of the image forming apparatus of the present invention is the same as that of the image forming apparatus shown in FIG.

As shown in FIG. 1, the control device 32 is connected to a storage device 34 and an operation unit 36. Further, the control device 32 is connected to the high-voltage power supply 38, the developing bias power supply 42, the driving device 44, and the blank power supply 46, and controls them.

The storage device 34 is for storing execution records of various predetermined functions. The storage device 34 includes a nonvolatile memory, and the stored information is retained even when the power of the image forming apparatus 30 is turned off.

The operation unit 36 allows the user to operate the image forming apparatus 3.
0 on / off, and the image forming apparatus 30
Is used to make various settings and perform input operations. When an image abnormality described later occurs, an instruction to execute an operation to cope with the image abnormality can also be input from the operation unit 36 to the control device 32.

The high-voltage power supply 38 controlled by the control device 32
Similar to the primary charging device 16 of the image forming apparatus 10 described with reference to FIG. 8, the power supply of the charging device uniformly charges the photosensitive drum 12 (see FIG. 8). Development bias power supply 42
Is a power supply for supplying electricity to the developing device 14 (see FIG. 8). The driving device 44 includes a photosensitive drum, a developing device,
And a fixing device (not shown) for fixing the image transferred to the recording medium to the recording medium, and the like. The blank power supply 46 is a power supply for supplying electricity required for blank exposure described with reference to FIG.

Hereinafter, a case of a so-called "image deletion" will be described as an example of an image abnormality. Here, the mode of the normal image forming operation executed by the image forming apparatus 30 when the image deletion does not occur is set as the first operation mode, and the removal operation for removing the cause of the image deletion is executed, and the normal image forming operation is performed. The mode in which the forming operation is executed is referred to as a second operation mode, and the mode in which the removing operation for removing the cause of the image deletion is executed is referred to as a third operation mode. The third operation mode is executed when the user performs an input from the operation unit 36. The execution procedures of the first to third operation modes are stored in the storage device 34. The number of executions of the first to third operation modes is accumulated and stored in the storage device 34. However, the photosensitive drum 12
Is replaced, the cumulative number of executions of the first to third operation modes is canceled to zero.

When the main body is turned on (turned on), (S1)
10), the flow of FIG. 2 is started, and the control device 32 reads the information stored in the storage device 34 and checks whether or not the third operation mode has been executed in the past (S112).
When the execution record of the third operation mode is not recorded in the storage device 34, since the image abnormality has not occurred in the past, the control device 32 performs the warm-up and the normal image forming operation according to the first operation mode. (S114).

On the other hand, when the execution record of the third operation mode is stored in the storage device 34, since the image abnormality has occurred in the past, the number of executions of the third operation mode is stored in the storage device 3.
4 (S116), and the width (amount) of the black band is determined based on the number of executions (S118). After that, various devices are controlled to perform warm-up and image forming operations according to the second operation mode (S120). here,
The black band refers to a toner image formed in a belt shape on the photosensitive drum 12 so as to extend in the rotation axis direction of the photosensitive drum 12 (see FIG. 8). The width of the black band refers to the width of the toner image formed in the band.

Here, examples of the width of the black band determined based on the number of executions of the third operation mode (the number of executions of the third operation mode) will be described with reference to Tables 1 to 3. The width of the black band is an example of the “strength of the removing operation” according to the present invention. When the intensity is increased, the width of the black band is increased, and when the intensity is reduced, the width of the black band is reduced. Further, the width of the black band is also an example of the “amount of the developer supplied to the image carrier during the removal time” according to the present invention. When the amount of the developer is small, the width of the black band becomes narrow. When the amount of the developer is large, the width of the black band becomes wide. Further, the removing operation according to the present invention refers to a series of operations from forming a black band on the photosensitive drum 12 to scraping the black band with the cleaning blade 22.

[0045]

[Table 1] In the example shown in Table 1, the number of executions of the third operation mode (the number of executions of the third mode) stored in the storage device 34 is one.
The width of the black band was 3 mm from the first to the third time, and the width of the black band was increased by 1 mm every three times when the number of times exceeded 3, and the maximum width of the black band was 15 mm. The number of times of execution of the third mode is an example of the “frequency of occurrence of a predetermined image abnormality” and the “history of occurrence of a predetermined image abnormality” in the present invention.

When the width of the black belt exceeds 15 mm, the polishing effect of polishing the surface of the photosensitive drum hardly improves.
When the width of the black band is less than 3 mm, the toner as the abrasive cannot be sufficiently supplied, and the polishing effect does not appear. For these reasons, the width of the black belt is set to 3 mm or more and 15 mm or less.

In the above example, the width of the black band is increased by 1 mm, but may be increased by 2 mm or 3 mm. Further, in the above example, when the number of times of execution of the third mode exceeds three, the width of the black band is increased every three times, but the number can be set freely. As a result, the width of the black belt and the number of times of polishing the photosensitive drum 12 (see FIG. 8) can be appropriately adjusted according to the frequency of occurrence of image abnormality, and the surface can be polished. These setting changes are made on the operation unit 36 (see FIG. 1).

[0048]

[Table 2] As described above, even if the width of the black band formed at one time exceeds 15 mm, the polishing effect of polishing the surface of the photosensitive drum hardly improves. Therefore, in the example shown in Table 2, the width of the black band is 15 m.
The number of black band formations was increased based on the number of executions after m. Here, after the width of the black band is set to 15 mm, the black band is formed 8 times in 2 seconds from 1 to 3 times, and 4 to 6 times.
The black belt was formed 11 times in 3 seconds. In this way, the number of black bands was increased, and after 16 times, 25 black bands were formed in 5 seconds. As a result, image abnormalities can be more reliably prevented. The number of times of forming the black band is an example of the “number of times of supplying a predetermined amount of the developer to the image carrier during the removal time” in the present invention.

[0049]

[Table 3] In the example shown in Table 3, based on the number of times of execution of the third mode stored in the storage device 34 (see FIG. 1), the second mode in FIG.
In the operation mode (S120), the number of times a black band is formed is changed. Here, every time the number of times of execution of the third mode stored in the storage device 34 exceeds three, the number of times of black belt formation executed in the second operation mode increases by three. in this case,
The width of the black belt was 5 mm. Further, the number of times the third mode is executed may be changed from two times to four times instead of three times.
These setting changes are performed on the operation unit 36 (see FIG. 1). As a result, the number of times the photosensitive drum 12 is polished can be appropriately adjusted according to the frequency of occurrence of image abnormality, and the surface thereof can be polished.

Next, the operation of the image forming apparatus 30 when the first operation mode is executed will be described with reference to FIG.

FIG. 3 is a flowchart of the first operation mode of the image forming apparatus.

The first operation mode is executed when the power of the image forming apparatus 30 is turned on. First, the halogen heater of the fixing device is turned on, and warm-up is started (S120). Thereafter, it is determined whether or not the fixing device (not shown) has reached a certain temperature. When the fixing device (not shown) has reached the certain temperature (S122), a normal pre-rotation mode is entered and the driving device 4
4, the photosensitive drum, the developing device, and the fixing device are rotated (S124). When the temperature of the fixing unit satisfies a predetermined warm-up condition (S126), the warm-up is terminated, the normal pre-rotation mode is terminated, and the image forming operation is started at any time (S128).

Thereafter, when the copy key is pressed after various settings relating to the image forming operation such as the number of copies and the magnification are made on the operation unit 36, the image forming operation (copy) is executed (S132), and the last recording paper is printed. After the is discharged, the image forming operation is stopped and returns to the standby state (S134), and this flow ends.

In the first operation mode, when the cumulative number of copies exceeds a predetermined number (for example, 50 or more), the control device 32 controls various devices to perform the following extended rotation mode after the copy operation is completed. I do. FIG. 4 is a flowchart showing the post-extension rotation mode.

As shown in FIG. 4, when the rotation mode after extension is started (S140), the driving device 44 is turned on (S1).
42), the fixing device and the photosensitive drum are rotated for a fixed time T3 (for example, 6.5 seconds) (S144). During this time, a cleaning blade similar to the cleaning blade 22 of the conventional cleaning device 20 described with reference to FIG. 8 contacts the photosensitive drum to remove paper dust, additives, etc. on the photosensitive drum, and simultaneously The exhaust fan discharges ozone generated from the charging device during the forming operation. In this way, the next image forming operation can be performed in a state where the cause of the occurrence of “image deletion” is reduced. After the elapse of the time T3, the driving device 44 stops (S146), the post-extension rotation mode ends, and the image forming operation is started at any time, and the flow ends. In the post-extension rotation mode, no electricity is supplied to the primary charging device 16 when the driving device 44 is turned on, so that a so-called “black belt” is not formed.

Next, the operation of the image forming apparatus 30 in the second operation mode will be described.

FIG. 5 is a flowchart showing a second operation mode of the image forming apparatus 30.

In the second operation mode, an operation for preventing "image deletion" is executed together with a normal image forming operation. That is, a removal operation for removing the cause of the image deletion is performed.

The second operation mode is executed when the power of the image forming apparatus 30 is turned on (S150). First, the halogen heater of the fixing device is turned on, and warm-up is started (S152). Thereafter, it is determined whether or not the fixing device has reached a certain temperature (S154). When the fixing device has reached the certain temperature, a normal pre-rotation mode is entered, the driving device 44 is turned on, and the photosensitive drum, the developing device, and the fixing device are fixed. The vessel is rotated (S156). When the normal pre-rotation ends, the process enters the pre-extension rotation mode (S158). This pre-extension rotation mode will be described later.

When the pre-extension rotation mode ends and the warm-up ends, the image forming apparatus enters a standby state in which the image forming operation can be started at any time (S160).

Thereafter, when the copy key is pressed after various settings relating to the image forming operation such as the number of copies and the magnification are made on the operation unit 36, the image forming operation is executed (S16).
2). As in the case of the first operation mode, when the accumulation of the number of copies by execution of the image forming operation exceeds a predetermined number, after the image forming operation is completed (S164), the rotation mode after extension is performed (S166). ).

In the case of this embodiment, if the predetermined number is set to 50, when the cumulative number of copies exceeds 50, after the copy operation is completed, the rotation mode is entered after the extension. Suitably, the duration T3 of the post-extension rotation mode is set to about 6.5 seconds. In the post-extension rotation mode, no “black band” is formed as in the post-extension rotation mode in the first operation mode. However, in the post-extension rotation mode in the second operation mode, it is preferable to form a “black band”.

When the post-extension rotation mode ends, the driving device 4
4 stops and enters a standby state in which the image forming operation can be started at any time (S168), and this flow ends.

The pre-extension rotation mode in the second operation mode will now be described with reference to FIG.

FIG. 6 is a flowchart of the pre-extension rotation mode in the second operation mode.

When entering the pre-extension rotation mode (S180), the driving device 44 is turned on, and the fixing device, the photosensitive drum, and the developing device are rotated (S182). Thereafter, in order to eliminate the cause of the "image deletion", the above-described "black belt mode" is executed (S184). After a certain period of time T2 (for example, 2 minutes) elapses after executing the “black belt mode” (S186), the driving device 44 is stopped (S188), and this flow ends.

In this embodiment, the black belt, that is, the toner image formed in a belt shape on the photosensitive drum has a width of 10 mm.
And the duration T2 is set to about 2 minutes. Even if the width of the black belt is increased to 10 mm or more, the polishing effect is hardly improved. On the other hand, if the width is less than 5 mm, the toner as the abrasive cannot be sufficiently supplied, and the polishing effect does not appear. When the width is between 5 and 10 mm, the polishing effect is improved as the width increases.

FIG. 7 is a flowchart showing a third operation mode of the image forming apparatus.

In the third operation mode, the user operates the operation unit 3
6 is a mode that is executed by making a selection, and is a mode in which a removing operation that removes the cause of the occurrence of image deletion is executed.

When the user selects the execution of the third operation mode with the operation unit 36 (S190), the driving device 44
(See FIG. 2) is turned on (S192), and the photosensitive drum 1
2 (see FIG. 8) and the developing device 14 are rotated. afterwards,
A predetermined number of “black belt mode” is executed (S194).

In this embodiment, the black band mode is set to be performed 18 times at intervals of 2 seconds. The reason is that the newer the toner held by the cleaning blade is, the higher the polishing effect of the toner becomes. This is for maintaining the polishing ability.

By rotating the photosensitive drum 12 for a fixed period of time (T4), additives and paper dust adhering to the photosensitive drum surface, which cause "image deletion", are scraped off, and the entire photosensitive drum surface is restored to normal. State. In the case of the present embodiment, the time T4 is set to about 2 minutes. Time T
After 4 has elapsed (S196), the driving of each device in the third mode stops (S198), and this flow ends.

When the third mode ends, the control unit 32
(See FIG. 2) puts the image forming apparatus 30 into the second operation mode. That is, the warm-up shown in FIG. 5 is completed (S160), and the image forming operation is set to a standby state where it can be started at any time.

At this time, control device 32 records in storage device 34 that the third operation mode has been executed. Since the memory device 34 can retain the memory even when the power of the image forming apparatus 30 is turned off, the execution record of the third operation mode remains when the power of the image forming apparatus 30 is turned on next time. Therefore, the control device 32 confirms the number of times the third operation mode has been executed in the past, and based on the number of executions, the image forming apparatus 30 executes the second operation mode as described above.

As described above, the user who uses the image forming apparatus in the environment where the “image deletion” occurs is the third user.
Since the width of the black band can be adjusted based on the number of times the operation mode is executed, "image deletion" can be efficiently recovered according to the use state of the user. Further, the number of times of executing the third operation mode can be reduced by efficiently recovering the “image flow”. As a result, copy productivity (the number of copies per unit time) is improved, the amount of toner used as an abrasive is reduced, and the life of the photosensitive drum is extended.

Tables 4 and 5 show other examples of the width of the black band or the number of black band formations determined based on the number of executions of the third operation mode (the number of executions of the third operation mode). It will be described with reference to FIG.

[0077]

[Table 4] In the example shown in Table 4, the black operation is performed based on the third operation mode execution number stored in the storage device 34 (see FIG. 1) and the normal image formation number performed during the execution of the third mode. Change the width of the band. Here, the ratio of the number of executions of the third operation mode to the number of times of normal image formation performed during the execution of the third mode (the number of executions / the number of copies) is set to the third number.
The width of the black band was changed based on the execution ratio of the operation mode. The execution ratio is a ratio of the number of times the second removal operation is performed to the number of times the normal image forming operation stored in the storage unit is performed according to the present invention.
This is an example.

When the execution ratio is 0.010 to 0.013, the width of the black band is 5 mm. When the execution ratio exceeds 0.013 to 0.017, the width of the black band is 7 mm. The width of the black belt is 10m up to 0.025 beyond 017
m, and the width of the black band was 11 mm until the execution ratio exceeded 0.025 to 0.10. The execution ratio is 0.10
, The width of the black belt was set to 15 mm. Thus, by changing the width of the black belt based on the execution ratio,
“Image deletion” can be efficiently restored in accordance with the usage state of the user. Further, the number of times of executing the third operation mode can be reduced by efficiently recovering the “image flow”. As a result, copy productivity (the number of copies per unit time) is improved, the amount of toner used as an abrasive is reduced, and the life of the photosensitive drum is extended.

[0079]

[Table 5] In the example shown in Table 5, based on the third operation mode execution number stored in the storage device 34 (see FIG. 1) and the normal image formation number performed during the execution of the third mode, Change the number of times a black band is formed. Here, the number of times the black band is formed is changed based on the execution ratio.

When the execution ratio is 0.010 to 0.013, a black band is formed about 5 times in 2 seconds.
From 13 to 0.017, a black band is formed about 7 times in 2 seconds. If the execution ratio exceeds 0.017 and up to 0.025, a black band is formed about 9 times in 2 seconds. 0.02
From 5 to 0.050, a black band was formed about 11 times in 2 seconds. If the execution ratio exceeds 0.05,
A black band was formed about 21 times in 2 seconds. As described above, by changing the number of times the black band is formed based on the execution ratio, “image deletion” can be efficiently recovered in accordance with the use state of the user. Further, the number of times of executing the third operation mode can be reduced by efficiently recovering the “image flow”. As a result, copy productivity (the number of copies per unit time) is improved, the amount of toner used as an abrasive is reduced, and the life of the photosensitive drum is extended.

[0081]

As described above, according to the first image forming apparatus of the present invention, the toner consumption may increase or the life of the photosensitive drum may decrease due to the removing operation. However, when the frequency of occurrence of an image abnormality is low, the frequency of executing the removing operation is also reduced, so that an increase in toner consumption and a decrease in the life of the photosensitive drum can be suppressed. Further, when the frequency of occurrence of the image abnormality is high, the frequency of executing the removing operation is also increased, so that the occurrence of the image abnormality can be reliably prevented.

Further, according to the second image forming apparatus of the present invention, the toner consumption may increase or the life of the photosensitive drum may decrease due to the removing operation. When the number of occurrences is small, the intensity of the removing operation is weakened so that an increase in toner consumption and a decrease in the life of the photosensitive drum can be suppressed. On the other hand, when the number of occurrences of the image abnormality is large, the intensity of the removing operation is increased to reliably prevent the occurrence of the image abnormality.

According to the third image forming apparatus of the present invention, the toner consumption may increase or the life of the photosensitive drum may decrease due to the first removing operation. When the number of occurrences of image abnormality is small, the intensity of the first removing operation is weakened so that an increase in toner consumption and a decrease in the life of the photosensitive drum can be suppressed. On the other hand, when the number of occurrences of the image abnormality is large, the intensity of the first removing operation is increased to surely prevent the occurrence of the image abnormality.

Here, the control means may control the intensity of the first removing operation every time the number of times of executing the second removing operation in the history stored in the storage means exceeds a predetermined number. Is controlled so as to sequentially increase the intensity of the first removing operation based on the number of times the second removing operation is executed. It is possible to reliably prevent the occurrence of image abnormalities while suppressing a reduction in the life of the drum.

Further, according to the fourth image forming apparatus of the present invention, the toner consumption increases and the life of the photosensitive drum decreases due to the first removing operation and the second removing operation. However, since the intensity of the first removal operation is increased or decreased based on the above ratio, an increase in toner consumption and a decrease in the life of the photosensitive drum can be suppressed.

Here, the above-mentioned image forming apparatus is an electrophotographic image forming apparatus, and the second removing operation is performed in a removing time other than the time when the normal image forming operation is performed. Supplying the developer to the body and removing the developer without transferring the developer to a recording medium; and the intensity of the second removal operation is controlled by the developing and supplying to the image carrier during the removal time. If it depends on the amount of the agent,
Since the reference of the intensity of the second removing operation can be determined according to the amount of the developer to be supplied to the image carrier, the control of the control device becomes easy.

Further, the image forming apparatus is an electrophotographic image forming apparatus, and the second removing operation is performed during a removing time other than the time when the normal image forming operation is performed. And removing the developer without transferring the developer to a recording medium. The intensity of the second removal operation is such that a predetermined amount of development is performed on the image carrier during the removal time. In the case where it is determined according to the number of times of supply of the developer, the reference of the intensity of the second removing operation can be determined according to the number of times of supplying the predetermined amount of the developer to the image carrier. Control becomes easy.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically illustrating an image forming apparatus according to the present invention.

FIG. 2 is a flowchart illustrating an operation of the image forming apparatus of FIG. 1;

FIG. 3 is a flowchart illustrating a first operation mode of the image forming apparatus.

FIG. 4 is a flowchart showing a rotation mode after extension.

FIG. 5 is a flowchart illustrating a second operation mode of the image forming apparatus.

FIG. 6 is a flowchart showing a rotation mode before extension.

FIG. 7 is a flowchart illustrating a third operation mode of the image forming apparatus.

FIG. 8 is a schematic diagram of a conventional image forming apparatus.

FIG. 9 is a timing chart of a black belt sequence.

FIG. 10 is a flowchart showing a black belt mode.

[Explanation of symbols]

 Reference Signs List 30 image forming device 32 control device 34 storage device 36 operation unit 38 high-voltage power supply 42 developing bias power supply 44 driving device 46 blank power supply

Claims (7)

[Claims] 1. An image forming apparatus for forming an image on a recording medium, wherein a frequency of executing a removing operation for removing a cause of the occurrence of the predetermined image abnormality is changed based on a frequency of occurrence of the predetermined image abnormality. An image forming apparatus comprising: 2. An image forming apparatus for forming an image on a recording medium, wherein an intensity of a removing operation for removing a cause of the occurrence of the predetermined image abnormality is changed based on a history of occurrence of the predetermined image abnormality. Image forming apparatus. 3. An image forming apparatus for forming an image on a recording medium, a first operation mode for executing a normal image forming operation executed when a predetermined image abnormality does not occur, wherein the first image abnormality occurs. A second operation mode in which the first image forming operation is performed while performing the first image removing operation for removing the cause of the image formation, and a selective second image removing operation for removing the cause of the predetermined image abnormality. Controlling to selectively execute any of the third operation modes to be executed, and controlling to execute the second operation mode after the third operation mode is executed; When the third operation mode is not executed, the first
And a storage unit for storing a history of the execution of the first and second removal operations. The control unit stores the history in the storage unit. The first based on the history
An image forming apparatus for changing the intensity of the removing operation. 4. The control unit sequentially increases the intensity of the first removal operation each time the number of times of executing the second removal operation in the history stored in the storage unit exceeds a predetermined number. The image forming apparatus according to claim 3, wherein the image forming apparatus controls the image forming apparatus so as to strengthen the image forming apparatus. 5. An image forming apparatus for forming an image on a recording medium, wherein: a first operation mode for executing a normal image forming operation which is executed when a predetermined image abnormality does not occur; A second operation mode in which the first image forming operation is performed while the first image removing operation is performed to remove the cause of the image forming operation, and a second selective operation is performed to remove the cause of the predetermined image abnormality. Controlling to selectively execute any of the third operation modes to be executed, and controlling to execute the second operation mode after the third operation mode is executed; When the third operation mode is not executed, the first
A control device for controlling the operation mode to be executed, the number of times the normal image forming operation is executed, and the second
Storage means for storing both the number of times the removal operation has been performed, and the control device further comprising: the second removal processing for the number of times the normal image forming operation stored in the storage means has been performed. An image forming apparatus, wherein the intensity of the first removing operation is controlled so as to increase or decrease according to the ratio of the number of times the operation is executed. 6. The image forming apparatus forms an electrostatic latent image on an image carrier, supplies a developer to the electrostatic latent image to form a developed image, and transfers the developed image to a recording medium. An electrophotographic image forming apparatus, wherein the second removing operation supplies the developer to the image carrier at a removing time other than the time when the normal image forming operation is performed, and removes the developer. An operation of removing the image without transferring it to a recording medium, wherein the intensity of the second removing operation is determined according to an amount of a developer supplied to the image carrier during the removing time. Claims 3, 4,
Or the image forming apparatus according to 5. 7. The image forming apparatus forms an electrostatic latent image on an image carrier, supplies a developer to the electrostatic latent image to form a developed image, and transfers the developed image to a recording medium. An electrophotographic image forming apparatus, wherein the second removing operation supplies the developer to the image carrier at a removing time other than the time when the normal image forming operation is performed, and removes the developer. The second removing operation is performed in such a manner that the intensity of the second removing operation is determined according to the number of times of supplying a predetermined amount of developer to the image carrier during the removing time. The image forming apparatus according to claim 3, 4 or 5, wherein