JPH04317077A - Image forming device - Google Patents

Abstract

PURPOSE:To attain the improvement and stabilization of image quality by sufficiently removing the foreign matter of paper powder, etc., sticking to the surface of a photosensitive body without using a specific device, for forming an image in an electrophotographic system utilizing a photosensitive body. CONSTITUTION:An electrostatic latent image for cleaning is formed on an image interval area between the first and next image forming areas on the photosensitive body, is developed with the developer of the polarity reverse to that of the developer for carrying out developing on the image forming area. Then, an sensible image formed in such a manner, is controlled so as to execute cleaning by the above-mentioned cleaning means, without being transferred.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus such as a copying machine, a facsimile machine, a laser beam printer, etc., which forms an image by an electrophotographic method using a photoreceptor. be.

0002

2. Description of the Related Art In this type of image forming apparatus, various photoreceptors are used, such as an organic photoreceptor, an inorganic photoreceptor, and a photoreceptor having a protective layer on its surface.

Although there are differences depending on the type of these photoreceptors, the charging characteristics and photosensitive characteristics of the surface deteriorate over time, and this deterioration of characteristics causes a decline in image quality.

For example, on the surface of the photoreceptor, paper dust from transfer paper, specifically paper fibers and talc, as well as foreign substances such as ozone and NOx generated under the influence of discharge from the charger, adhere to the surface of the photoreceptor. However, these foreign substances are not removed only by cleaning the surface of the photoreceptor after image transfer, which is usually performed in an image forming apparatus, but gradually accumulate.

[0005] This accumulated foreign matter absorbs moisture in a high temperature and high humidity environment, impairing the insulation properties of the photoreceptor surface. This causes the potential of the electrostatic latent image formed on the photoreceptor to be dissipated to the surroundings. As a result, even if the electrostatic latent image is developed and transferred, a so-called image deletion or image omission phenomenon occurs in which the image is partially scattered.

[0006] It has been confirmed that a thin layer of talc is attached to the area where such a phenomenon occurs.

Conventionally, in order to deal with the phenomenon of image blurring or image omission, cleaning methods have been used to take advantage of the soft surface of the photoreceptor, such as inorganic photoreceptors having a selenium layer or organic photoreceptors having an organic photoreceptor layer. During cleaning, the surface layer of the photoreceptor is slightly scraped off to remove foreign substances such as those mentioned above.

It is known that the residual toner that remains on the surface of the photoreceptor after transfer and is the object of the cleaning acts as an abrasive for such scraping. is convenient.

Further, in the case of a photoreceptor having a protective layer, the surface is hard to be scraped, so it has a long life, but the cleaning effect is low.

[0010] In order to strengthen the scraping effect, an abrasive material is also mixed into the developer. For the same purpose, as shown in the unfolded state in FIG. A line electrostatic latent image is formed and this is developed as a developed line image e, and the line image e for cleaning after this development is shown in FIG.
It is also used as an abrasive material by being cleaned by the cleaning means f shown in FIG.

[0011]

However, in the method of forming a line image e for cleaning in the inter-image area of the photoreceptor and using it for cleaning the surface of the photoreceptor, it is not possible to use that much toner for cleaning. Therefore, scraping of the photoreceptor surface cannot be sufficiently promoted. Therefore, a photoreceptor having a protective layer whose surface is likely to be insufficiently scraped is still insufficient.

Further, in this method, by increasing the width of the line image e, a large amount of developer can be used for the cleaning to compensate for the lack of scraping.
Since this method is normally developed, the amount of developer consumed increases significantly and costs increase, so this is not a practical countermeasure.

In the method of mixing an abrasive, only a very small amount of the developer remaining on the photoreceptor is used for the cleaning after the image normally formed on the photoreceptor is transferred, so this method also cleans the surface of the photoreceptor. It is not possible to sufficiently promote the scraping of.

Therefore, the present invention provides an image forming apparatus that can exhibit a sufficient surface scraping effect even on a photoreceptor having a protective layer without increasing the consumption of developer for normal development. The goal is to provide the following.

[0015]

[Means for Solving the Problems] The first invention of the present application includes a photoreceptor, a latent image forming means for forming an electrostatic latent image on the photoreceptor, and a toner developer for developing the electrostatic latent image on the photoreceptor. a developing means for developing a developed image using a photoreceptor; a transfer means for transferring a developed image on a photoreceptor onto a transfer sheet; a cleaning means for cleaning the surface of the photoreceptor after image transfer with a cleaning blade that presses against the surface of the photoreceptor; and a cleaning means for forming a latent image. In an image forming apparatus comprising a control means for controlling operations of a developing means, a developing means, and a transfer means, the control means performs cleaning on an inter-image area between a previous image forming area and a next image forming area on the photoreceptor. This electrostatic latent image is developed with a developer having a polarity opposite to that of the developer used for development in the image forming area, and the developed image thus formed is removed by the cleaning means. It is characterized in that it is controlled so as to be used for cleaning.

[0016] A second invention of the present application is based on the first invention, further providing that the development with the developer of opposite polarity operates the developing means for developing in the image forming area, and the development with the normal polarity for normal development is performed. This method is characterized in that it is carried out in such a way that the developer of opposite polarity mixed in the developer is consumed.

A third invention of the present application further provides an intermittent image forming mode in which a single image is formed intermittently in the first or second invention, and a continuous image forming mode in which a plurality of images are continuously formed. According to the size of the inter-image area, the area in which the electrostatic latent image for cleaning is formed is increased or decreased.

[0018] A fourth invention of the present application is characterized in that, in any one of the first to third inventions, the electrostatic latent image in the inter-image area is formed only by charging the photoreceptor. It is something.

A fifth invention of the present application is further characterized in that the developing means uses a one-component non-magnetic developer.

A sixth invention of the present application is characterized in that, in any one of the first to fifth inventions, the photoreceptor is further provided with a protective layer on its surface.

[0021]

[Operation] According to the above structure of the first invention of the present application, when an image is formed on the photoreceptor, the control means controls the distance between the previous image forming area and the next image forming area on the photoreceptor. An electrostatic latent image for cleaning is formed in the inter-image area, and this electrostatic latent image is developed with a developer of opposite polarity to the developer that normally develops the image in the image area.

[0022] Since the developer of opposite polarity which is developing the cleaning image in this inter-image area is not transferred and is directly used for cleaning the surface of the photoreceptor by the cleaning means, the cleaning image is All of the forming developer of opposite polarity acts as an abrasive during the cleaning, facilitating the scraping of the photoreceptor surface without consuming the developer that would normally develop the image in the imaging area. be able to.

According to the above configuration of the second invention of the present application, the first
Further, in the invention, the development in the inter-image area operates a developing means that performs development in the image forming area,
Because this process consumes the opposite polarity developer that is naturally mixed in the normal polarity developer for normal development, no special developing means is used, and the opposite polarity developer in the normal developer is used. Polar developer can be consumed to accomplish development of the cleaning electrostatic latent image in the interimage areas.

According to the above configuration of the third invention of the present application, the first
Or, in the second invention, the size of the inter-image area is different between an intermittent image forming mode in which a single image is formed intermittently and a continuous image forming mode in which a plurality of images are continuously formed. Accordingly, the area in which the electrostatic latent image for cleaning is formed is increased or decreased, so that the entire area between the images formed from time to time can be effectively utilized to form the image for cleaning.

According to the above configuration of the fourth invention of the present application, the first
Furthermore, in any of the third inventions, the electrostatic latent image for cleaning in the inter-image area is formed only by charging the photoreceptor, so it can be easily controlled without special image exposure. The electrostatic latent image for cleaning becomes a solid image, and this can be developed as it is, allowing a large amount of developer to be used for cleaning and effectively used as an abrasive material at that time. .

According to the above configuration of the fifth invention of the present application, the second
Further, in the invention, the developing means uses a one-component non-magnetic developer, and due to variations in charging characteristics, a large amount of developer of opposite polarity occurs in the developer used for normal development, which is The developing agent can be used as it is to develop an electrostatic latent image for cleaning in between, thereby ensuring image density by removing defective developer and achieving sufficient development.

According to the above structure of the sixth invention of the present application, the first
Furthermore, in any one of the ~fifth inventions, since the photoreceptor has a protective layer applied to its surface, both durability and image forming characteristics can be improved by facilitating scraping of the surface. .

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital electrophotographic copying machine as an embodiment of the present invention will be described below.

FIG. 1 schematically shows the image forming mechanism of the copying machine. This image forming mechanism uses a one-component developer, and a developer casing 2 and a waste toner casing 3 are arranged on both sides of a photosensitive drum 4.

The photosensitive drum 4 has a photoconductive layer made of an organic photoconductive material formed on the surface of a metal base such as aluminum, and the surface is uniformly charged by a charger 52 located at the top. Laser optics 24 as shown
image exposure from

If the photosensitive drum 4 has a relatively soft photoconductive layer such as the above-mentioned organic photoconductive material, a protective layer is formed on the surface thereof. However, in cases where such a protective layer is not necessary, a protective layer is generally not provided.

The laser optical system 24 receives an image signal scanned by the scanner 21 provided above, and performs the image exposure using a laser output modulated in accordance with this signal.

The scanner 21 includes an illumination light source 27 that illuminates the original on the platen glass 22, an image reader 28 using a CCD line sensor, and an imaging lens 29 that forms an image of light reflected from the original on the image reader 28. Equipped with
A microcomputer moves under the platen glass 22 in the direction of the arrow to scan the original placed on the platen glass 22, reads the original image by the image reader 28, and uses this as an image signal to control the operation of the copying machine. The light is outputted to the laser optical system 24 via 100.

By the image exposure, an electrostatic latent image corresponding to the image of the original is formed on the photosensitive drum 4. This electrostatic latent image is developed with a developer supplied from the developer casing 2, and becomes a developed image.

This developed image is transferred onto a transfer sheet 37 by a transfer charger 36 located below the photosensitive drum 4, and is fixed by a fixing device (not shown) to complete image formation.

A developing roller 11 for developing the electrostatic latent image formed on the photosensitive drum 4 is provided at the toner supply port 2a of the developer casing 2 facing the photosensitive drum 4.
It is pivotally supported by the side wall of the developer casing 2.

A development gap is provided between the development roller 11 and the photosensitive drum 4 for non-contact development using a one-component non-magnetic developer.

A developer supply paddle 15 is provided in the developer casing 2 to agitate the developer in the developer casing 2 while supplying it to the fur brush 13, and is provided with a stirring blade 17 for preventing toner from forming into blocks. is installed.

The fur brush 13 supplies the developer supplied by the developer supply paddle 15 to the peripheral surface of the developing roller 11 while conveying it to the developing roller 11 side.
The developer is triboelectrically charged during the supply process.

At the upper edge of the toner supply port 2a of the developer casing 2, an elastic blade 41 is provided which extends to the circumferential surface of the developing roller 11 and presses against it.

The elastic blade 41 forms a thin layer of a predetermined thickness of the developer supplied by the fur brush 13 onto the developing roller 11, and is made of rubber blades such as urethane rubber or silicone rubber, phosphor bronze for springs, or spring steel. A metal blade such as the following is suitable.

A seal piece 25 is provided at the lower edge of the toner supply port 2a of the developer casing 2, and the seal piece 25
It extends upward and is pressed into contact. This seal piece 25 is made of polyethylene terephthalate (PET) or the like, and allows residual toner carried on the developing roller 11 and subjected to development on the photosensitive drum 4 to pass through into the toner supply port 2a.
To prevent the developer from coming out from the toner supply port 2a.

A cleaning blade 7 extending from the upper edge 3b of the toner recovery port 3a is in pressure contact with the portion of the waste toner casing 3 of the photosensitive drum 4 that is opposed to the toner recovery port 3a. The residual toner scraped off from the surface of the photosensitive drum 4 after transfer by the cleaning blade 7 is collected into the waste toner casing 3.

For this collection, a paddle 8 is provided near the bottom of the waste toner casing 3 behind the photosensitive drum 4.
The toner scraped off from the photosensitive drum 4 is scraped into the waste toner casing 3.

After the surface of the photosensitive drum 4 has been cleaned, residual charges are removed by the eraser 5, so that charging by the charger 52 is uniformly performed.

A seal piece 26 is provided on the lower edge 3c of the collection port 3a of the waste toner casing 3, and its tip is pressed against the surface of the photosensitive drum 4.

This seal piece 26 is similar to the seal piece 25, and the residual toner on the photosensitive drum 4 is passed through the cleaning blade 7 without difficulty, but the residual toner that is scraped off by the cleaning blade 7 is removed. The toner is received and guided into the waste toner casing 3 to prevent it from slipping out below the waste toner casing 3.

In this embodiment, the surface potential VO of the photosensitive drum 4 is 930V, the bias voltage VB from the DC bias power supply 6 applied to the developing roller 11 is 800V, and the surface potential VL of the photosensitive drum 4 after exposure is 100V. The above-mentioned image formation is performed by setting as follows.

In this embodiment, the developing roller 11
The one-component developer supplied to the is made to be positively charged on the triboelectrostatic array, and the potential is set so that the one-component developer is positively charged by exposure to light.
Riding on the electric field from the developing roller 11 directed toward the latent image portion whose voltage has dropped to 00 V, it is attracted to and adheres to the electrostatic latent image formed on the photosensitive drum 4, and is developed.

Incidentally, on the surface of the photosensitive drum 4, paper dust from the transfer paper, specifically paper fibers and talc, as well as foreign substances such as ozone and NOx generated under the influence of discharge from the charger, adhere. These foreign substances are not removed only by cleaning the surface of the photosensitive drum 4 after image transfer using the cleaning blade 7, which is normally performed in an image forming apparatus, but gradually accumulates. If the photosensitive drum 4 has a protective layer as described above, it is difficult to remove the protective layer.

[0051] The deposited foreign matter absorbs moisture in a high temperature and high humidity environment and impairs the insulation of the surface of the photosensitive drum 4.
This causes the potential of the electrostatic latent image formed on the photosensitive drum 4 to be dissipated to the surroundings. As a result, even if the electrostatic latent image is developed and transferred, a so-called image deletion or image omission phenomenon occurs in which the image is partially scattered.

In order to solve this problem, in this embodiment, there is a gap between the image forming area E1 on the photosensitive drum 4 where the image will be formed first and the image forming area E2 where the image will be formed next. An electrostatic latent image for cleaning is formed in the inter-image area E3 (FIG. 3), and this is transferred to the image forming area E1,
In E2, the image is developed with a developer having a polarity opposite to that of the developer normally used to develop the image, and the developed image thus formed is directly subjected to cleaning by the cleaning blade 7 without being transferred. It is designed to be used as an abrasive.

[0053] As a result, more developer is supplied to the photosensitive drum 4 than when the residual developer exerts an abrasive effect during cleaning, so that the abrasive effect is greatly improved. Therefore, the foreign matter that causes the image omission can be sufficiently removed, and the image quality is improved.

According to the developing method using a one-component non-magnetic developer as in this embodiment, a relatively large amount of negatively charged developer exists in the developer casing 2 due to variations in charging characteristics.

According to experiments conducted by the present inventors, in a developing device capable of developing 4000 A4 size transfer sheets, approximately 40 g of oppositely charged developer is mixed into 200 g of developer. It also causes a decrease in image density.

When developing is performed using a developer containing a negatively charged developer of opposite polarity as described above, when the developing bias is turned off, the direction of the electric field generated between the photosensitive drum 4 and the developing roller 11 changes. is opposite to the above case, and by simply continuing the developing state, the negatively charged developer in the developer supplied from the developing roller 11 is reversed to the non-exposed area with a high potential. The electrostatic latent image for cleaning is developed and used for the cleaning. However, a similar potential difference may be obtained between the developing roller 11 and the photosensitive drum 4 using another method.

Furthermore, since the one-component non-magnetic developer is externally added with silica (SiO2), which is a glidant, and is effective as an abrasive, the above-mentioned cleaning effect becomes even higher.

Furthermore, as in this embodiment, the DC bias power supply 6
When using a developer, alumina is also externally added to the developer, which also helps in polishing the surface of the photosensitive drum 4, thereby improving the cleaning effect.

Furthermore, the developing method using the DC bias power supply 6 can be changed to an AC method. In this case, the developer used for development goes back and forth between the developing roller 11 and the photosensitive drum 4 several times, causing the developer to protrude from the area of the electrostatic latent image formed on the photosensitive drum 4. A so-called fog phenomenon in which developer is deposited tends to occur, and the cleaning effect is improved by the amount of excess developer deposited due to this fog.

[0060] In this case, the electrostatic latent image does not need to be formed as a specific image, since it is sufficient that the required amount of the developer, in other words, a sufficient amount of developer for cleaning, is attached to the electrostatic latent image. It suffices if it has enough charge to attract the negatively charged developer.

Therefore, in this embodiment, the inter-image area E3 is subjected to development while being uniformly charged by the charger 52.

Furthermore, when image formation is performed intermittently one sheet at a time, feeding of the transfer sheet is started at a predetermined timing each time the print key is turned on, so that the idling process of the photosensitive drum 4 after image formation is Image formation on the photosensitive drum 4 is performed in accordance with this paper feeding timing. Therefore, the inter-image area E3 between the image area E1 where an image is formed first and the image area E2 where an image is formed next on the photosensitive drum 4 tends to be large.

Therefore, in this embodiment, in the intermittent image forming mode, the area where the electrostatic latent image for cleaning is formed is set to be large so as to fully utilize the large inter-image area E3.

Furthermore, when making multiple copies of the same original, the multiple transfer sheets are moved as far as possible during the previous image forming operation to shorten the image forming interval. In this case, the inter-image area E3 becomes smaller than in the intermittent image forming mode. Therefore, in the case of the continuous image forming mode, a forming area of an electrostatic latent image for cleaning is set, making full use of the smaller inter-image area E3.

In the case of the above control, each time one image is formed, in the intermittent image forming mode, approximately 10 mg of the opposite polarity developer adheres to the 160 mm wide inter-image area E3, and in the continuous image forming mode, approximately 10 mg of the opposite polarity developer adheres to the 160 mm wide inter-image area E3. Approximately 3 mg of opposite polarity developer adheres to the width of the inter-image area E3.

In order to control the image forming operation as described above, a microcomputer 100 that controls the operation of the copying machine is used.
(Figure 2) is used. The input section of the microcomputer 100 receives a print signal 101 and a print number signal 10.
2. Other inputs are connected, and a main motor drive signal 103, a charging high voltage output signal 104, a laser output signal 105, a developing high voltage output signal 106, a transfer high voltage output signal 107 and other outputs are connected to the output section. .

The main routine for main control of image formation by the microcomputer 100 is shown in FIG.

To explain this, the control starts when the power is turned on, and first, in step #1, necessary initial settings and initial processing are performed, and then, in step #2, a routine timer that defines the time for one routine is started.

Next, the input/output processing subroutine (step #3), the mode processing subroutine (step #4), and the image forming processing subroutine (step #5) are sequentially called.

The input/output processing subroutine processes various inputs and outputs according to the inputs. The mode processing subroutine sets various operation modes such as intermittent image forming mode or continuous image forming mode depending on whether the set number of copies is single or multiple.

The image forming processing subroutine performs image formation including the cleaning according to the set mode.

After the other processing subroutines are finally called, wait for the routine timer to end and proceed to step #2.
Return to , and repeat the same operation.

FIG. 5 shows the mode processing subroutine. To explain this, it determines whether the set number of copies is multiple based on the presence of a print signal (
Step #11, 12).

[0074] If the set number of sheets is multiple, step #1
The continuous image forming mode flag A is set in step #3, and if it is 1, the intermittent image forming mode flag B is set in step #14.

Next, after performing other mode processing, if the image formation end flag C is set (step #15,
#16) In step #17, various flags A to C are reset, and the process returns to the main routine.

FIG. 6 shows the image forming processing subroutine. To explain this, first, when there is a print signal, the image forming mode is determined based on whether flag B is set (steps #21 and #2).
22).

If flag B is set in the intermittent image forming mode, after a predetermined period of time has elapsed after turning on the main motor, charging high voltage, laser power, developing high voltage, and transfer high voltage are sequentially activated at their respective required operation timings. It is turned on, and an image forming operation is performed according to the operation time chart shown in FIG. 7 (step #23).

After the image forming operation, the image forming counter is incremented by 1, and it is determined whether this result has reached the set number of sheets (steps #24 and #25).

If the setting is for a single sheet, the set number has been reached, so the image forming counter is reset to 0, the image forming end flag C is set, and the process returns to the main routine.

Here, T1 in FIG. 7 is a printing section schematically shown, and after this section, the charging high voltage remains on and the developing high pressure is turned off. In the section T2, the developer of the opposite polarity is This is an image forming section for cleaning that is deposited using the inter-image area.

In this case, section T2 is after normal image formation.
The time is set so as to fully utilize the interval between images until the next normal image is formed.

On the other hand, if the flag is not B in step #22,
When the number of sheets is set to multiple sheets, after the start of the image forming operation similar to the case of the single sheet setting, the image forming operation as shown in the operation time chart shown in FIG. This process is repeated until the value is one less (steps #31, #32, #24, #25).
).

When the count value becomes one less than the set number of sheets, the image forming operation shown in FIG. 7, which is the same as when setting a single sheet at step #23, is performed, and steps #25 to #27 are performed.
After the above processing, the process returns to the main routine and image formation is completed.

T3 in FIG. 8 is a period for developing an electrostatic latent image for cleaning with a developer of opposite polarity using the inter-image area, similar to T2 in FIG. 7, but it is shorter than in the case of a single sheet shown in FIG. The time is set. This corresponds to the fact that when a plurality of images are continuously formed, the area between images becomes smaller in order to streamline the image forming operation.

Although this embodiment has been described with respect to a copying machine, it can be similarly applied to all types of machines that form electrophotographic images using photoreceptors. Examples include facsimiles and laser beam printers. Furthermore, development is not limited to the one-component non-magnetic developer.

[0086]

According to the first aspect of the present invention, when an image is formed on the photoreceptor, the control means controls the image formation between the previous image forming area and the next image forming area on the photoreceptor. An electrostatic latent image for cleaning is formed in the area between the images, and this electrostatic latent image is developed with a developer of opposite polarity to the developer that normally develops the image in the image area. Since the opposite polarity developer forming the cleaning image is directly used for cleaning the photoreceptor surface by the cleaning means without being transferred, the opposite polarity developer forming the cleaning image is All of the agent acts as an abrasive during the cleaning, and can facilitate scraping of the photoreceptor surface without consuming the developer that normally develops the image in the image forming area. It is possible to effectively remove foreign matter adhering to the photoreceptor and improve image quality without the disadvantage of developer consumption.

According to the second invention of the present application, furthermore, in the first invention, the development in the inter-image area is performed by operating the developing means for developing in the image forming area, so that the normal polarity for normal development is maintained. Because this process consumes the opposite polarity developer that is naturally mixed in the developer, no special developing means is used, and the opposite polarity developer that is normally mixed in the developer is consumed. Development of an electrostatic latent image for cleaning in the inter-image area can be achieved, and the quality of the developer can be improved by consuming and removing the opposite polarity developer in the developer that is normally used for development. Further simplification of structure and control can be achieved.

According to the third invention of the present application, the first or second
Further, in the invention, in accordance with the difference in the size of the inter-image area between an intermittent image forming mode in which a single image is formed intermittently and a continuous image forming mode in which a plurality of images are continuously formed, Since the area where the electrostatic latent image for cleaning is formed is increased or decreased, the entire area between the images formed at any given time can be effectively used to form the cleaning image, which extends the operation time. A sufficient cleaning effect can be achieved without any problems.

According to the fourth invention of the present application, in any of the first to third inventions, the electrostatic latent image for cleaning in the inter-image area is formed only by charging the photoreceptor. , it can be formed by simple control without special image exposure, and the electrostatic latent image for cleaning becomes a solid image, which is developed as it is, and a lot of developer is used for cleaning. It can be effectively used as an abrasive, and it is possible to further simplify control and further improve the cleaning effect.

According to the fifth invention of the present application, furthermore, in the second invention, the developing means uses a one-component non-magnetic developer, and due to variations in charging characteristics, there is an adverse reaction in the developer used for normal development. A large amount of polar developer is generated, and this is used as it is to develop the electrostatic latent image for cleaning between the images, and the development is sufficiently achieved while ensuring image density by removing defective developer. This makes it possible to ensure improvement in image quality.

According to the sixth invention of the present application, in any one of the first to fifth inventions, since the photoreceptor is further provided with a protective layer on its surface, scraping of the surface of the photoreceptor is facilitated. Both durability and image forming characteristics can be improved.

[Brief explanation of drawings]

FIG. 1 is a side view showing a schematic configuration of an image forming mechanism of a digital copying machine to which the present invention is applied.

FIG. 2 is a block diagram of a control device of the copying machine shown in FIG. 1;

FIG. 3 is a developed explanatory diagram showing the relationship between image forming areas of images sequentially formed on a photosensitive drum and an inter-image area between these areas.

FIG. 4 is a flowchart of a main routine showing main control of the control device in FIG. 2;

FIG. 5 is a flowchart of the mode processing subroutine shown in FIG. 4;

FIG. 6 is a flowchart of the image creation processing subroutine shown in FIG. 4;

FIG. 7 is a time chart of main image forming operations in intermittent image forming mode.

FIG. 8 is a time chart of main image forming operations in continuous image forming mode.

FIG. 9 is a developed explanatory view of a photoreceptor showing a state in which a line image for cleaning is formed in a conventional image-to-image area.

10 is a side view of the cleaning section showing a state in which the line image of FIG. 9 is being cleaned; FIG.

[Explanation of symbols]

2. Developer casing 4 Photosensitive drum 7 Cleaning blade 11 Developing roller 24 Laser optical system 36 Transfer charger 52　Electrical charger 100 Microcomputer 101 Print signal 102 Print number signal 103 Main motor drive signal 104 Charged high voltage output signal 105 Laser output signal 106 Development high voltage output signal 107 Transfer high voltage output signal

Claims (6)

[Claims] 1. A photoreceptor, a latent image forming means for forming an electrostatic latent image on the photoreceptor, a developing means for developing the electrostatic latent image on the photoreceptor with toner, and a photoreceptor. A transfer means for transferring the above developed image onto a transfer sheet, a cleaning means for cleaning the surface of the photoreceptor after the image transfer with a cleaning blade that presses against the surface, a latent image forming means, a developing means, and a transfer means. In the image forming apparatus, the control means forms an electrostatic latent image for cleaning in an inter-image area between a previous image forming area and a next image forming area on the photoconductor, and The electrostatic latent image is developed with a developer having a polarity opposite to that of the developer used for development in the image forming area, and the developed image formed thereby is controlled so as to be subjected to cleaning by the cleaning means without being transferred. An image forming apparatus characterized by: 2. In the development using the developer of opposite polarity, a developing means for developing in the image forming area is operated, and the developer of opposite polarity mixed in the developer of normal polarity for normal development is consumed. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to perform image forming. 3. Although the size of the inter-image area is different between an intermittent image forming mode in which a single image is formed intermittently and a continuous image forming mode in which a plurality of images are continuously formed, 3. The image forming apparatus according to claim 1, wherein the area on which the electrostatic latent image for cleaning is formed is increased or decreased accordingly. 4. The image forming apparatus according to claim 1, wherein the electrostatic latent image in the inter-image area is formed only by charging the photoreceptor. 5. The image forming apparatus according to claim 2, wherein the developing means uses a one-component non-magnetic developer. 6. The image forming apparatus according to claim 1, wherein the photoreceptor has a protective layer formed on its surface.