JPH06167854A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent deterioration of image quality, which results from resticking of residual toner to an electrostatic latent image by, prior to the formation of an original electrostatic latent image, forming a latent image pattern for making toner, remaining on a photosensitive body at the time of separating a cleaning blade from the photosensitive body, and sticking to a sealing member at the time rotating the photosensitive body, electrostatically shift to the photosensitive body. CONSTITUTION:When the cleaning blade is separated from the surface of the photosensitive body 1 after an image forming operation, toner remains in line shape on the photosensitive body 1. Also, when an image forming operation is started and the photosensitive body 1 is rotated, the residual toner on the photosensitive body 1 stickes to the sealing member of a development device. Therefore, prior to the formation of the original latent image 7 on the surface of the photosensitive body 1, the latent image pattern 21 is formed upstream on the surface of the photosensitive body 1, thereby electrostatically shifting the toner sticking to the sealing member to the latent image pattern 21. As a matter of course, the toner sticking to the latent image pattern 21 is removed from the photosensitive body by a cleaning device without being transferred to transfer paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method in which a toner image is formed on a latent image carrier, the toner image is transferred to a transfer material, and then the toner remaining on the latent image carrier is cleaned. It relates to the device.

[0002]

2. Description of the Related Art The image forming apparatus having the above-described structure, which is configured as an analog or digital electronic copying machine, a printer, or the like, is well known in the art. FIG. 1 is a block diagram showing an image forming apparatus according to an embodiment of the present invention. Here, while explaining the basic structure and operation of the image forming apparatus shown in FIG. To do.

In FIG. 1, reference numeral 1 is a drum-shaped photosensitive member which is an example of a latent image carrier, and the photosensitive member 1 is rotationally driven in the direction of arrow A during an image forming operation. At this time, the surface of the photoconductor 1 is uniformly charged to a predetermined polarity by the corona discharge of the charger 2, and the charged surface of the photoconductor is image-exposed at the exposure unit 3, whereby the photoconductor 1 is exposed.
A predetermined electrostatic latent image is formed on the surface.

In the example shown in FIG. 1, the photoreceptor 1 is a charger 2
A laser beam 5 that is charged to a negative polarity and is optically modulated according to an image signal is emitted from the writing unit 4, and this exposes the photoreceptor 1 after being charged. FIG. 2 is an explanatory view showing the photoconductor 1 in a developed state. A predetermined region on the surface of the photoconductor 1, that is, an image region 6 is negatively charged by the charger 2 (FIG. 1) and the laser beam 5 is emitted. The irradiated portion becomes the electrostatic latent image 7, and the image area portion around it becomes the background portion 8.
Becomes Here, the surface potential Vd of the background portion 8 is -800.
V, the surface potential Va of the electrostatic latent image 7 irradiated with the laser beam 5
Is set to −100V.

As described above, in the image forming apparatus shown in FIG. 1, the charger 2 and the writing unit 4 are the same as the photoconductor 1.
A latent image forming means for forming an electrostatic latent image on the.

The electrostatic latent image 7 formed on the photoconductor 1 is visualized as a toner image by the developing device 9. The developing device 9 shown here has a developing case 10 containing the developer D and a developing roller 11 arranged in the case 10. The developing roller 11 is opposed to the photoconductor 1. An example of an electrode is configured.

During the developing operation, the developing roller 11 rotates counterclockwise in FIG. 1 and carries the developer while carrying the developer on its surface. As the developer, a two-component developer having a toner and a carrier, a one-component developer containing no carrier, or the like can be used. In the example of FIG. 1, the two-component developer is used and the toner The toner is negatively charged by the friction between the toner and the carrier.

The developer D is conveyed to the developing area between the photoconductor 1 and the developing roller 11, the toner in this area is transferred to the electrostatic latent image 7 (FIG. 2), and the latent image is formed. It is visualized as a toner image.

When the developing operation as described above is performed, a bias voltage having the same polarity as the charging polarity of the photoconductor 1 is applied to the developing roller 11 by a power source (not shown). Here, it is assumed that the bias voltage Vb is -600V. In this way, an electric field is formed between the developing roller 11 and the electrostatic latent image (surface potential Va is −100 V) 7 on the photoconductor 1, and the negatively charged toner is electrostatically applied to the electrostatic latent image 7. Move to. So-called reversal development is performed.

The developer D is placed in the developing case 10 of the developing device 9.
However, if the toner is scattered outside the developing case, the inside of the main body of the image forming apparatus such as the periphery of the developing device will be contaminated with the toner. In order to prevent such a problem, the base end side of the seal member 20 made of, for example, a flexible soft material is fixed to the developing case portion on the side where the photoconductor 1 enters, and the front end side of the seal member 20 is fixed. Are in contact with the surface of the photoconductor 1. By providing such a seal member 20, it is possible to prevent the toner inside the developing device from scattering to the outside.

On the other hand, a transfer paper 13, which is an example of a transfer material, is delivered from the paper supply unit 12, and the transfer paper 13 is delivered to the photoconductor 1 by a registration roller 14 at a predetermined timing. Then, the positive polarity corona discharge of the transfer device 15 is applied from behind the transfer paper 13, and the toner image on the photoconductor 1 is transferred onto the transfer paper 13. Thus, the transfer device 15
Is an example of a transfer unit that transfers the toner image on the photoconductor 1 onto the transfer paper 13.

The transfer paper 13 on which the toner image has been transferred is separated from the photoconductor 1 and passes through a fixing device (not shown), at which time the toner image is fixed on the transfer paper 13.

On the other hand, the toner remaining on the photoconductor 1 after the transfer of the toner image is cleaned by the cleaning device 16, and then the surface of the photoconductor is subjected to the charge removal action by the charge remover 17.

The cleaning device 16 has a cleaning blade 18 that is pressed against the surface of the photoconductor 1 to clean residual toner on the photoconductor 1. The cleaning device 16 shown in FIG. 1 also has a cleaning brush roller 19 that rotates while contacting the photoconductor 1.

The cleaning blade 18 is made of, for example, an elastic material such as rubber. If the blade 18 is constantly in pressure contact with the photoconductor 1 even during a non-image forming operation, the cleaning blade 18 deteriorates early. However, the cleaning function may deteriorate.

Therefore, the cleaning blade 18 can be brought into and out of contact with the photoconductor 1 so that when the residual toner on the photoconductor 1 is removed, the cleaning blade 18 comes into pressure contact with the surface of the photoconductor 1. ing. For example,
The cleaning blade 18 is separated from the photoconductor 1 at the same time when the image forming operation is finished and the photoconductor 1 is stopped, or after a lapse of a predetermined time. Further, in order to start the image forming operation, the cleaning blade 18 is pressed against the surface of the photoconductor 1 at the same time when the photoconductor 1 starts to rotate.

As described above, the cleaning blade 18 is brought into pressure contact with or separated from the photoconductor 1 at a predetermined timing, but the cleaning blade 18 is brought into pressure contact with the photoconductor 1 to perform the cleaning operation. While the cleaning blade 18 is separated from the photoconductor 1, the toner remains linearly on the photoconductor 1 when the cleaning blade 18 is separated from the photoconductor 1. In this state, again the cleaning blade 1
When the image forming operation is started by bringing 8 into pressure contact with the photoconductor 1 and rotating the photoconductor 1, the toner linearly remaining on the photoconductor 1 adheres to the seal member 20 of the developing device 9.

Here, in the conventional image forming apparatus,
As described above, the toner attached to the seal member 20 is electrostatically transferred to the tip of the electrostatic latent image formed on the photoconductor 1 and redeposited on the photoconductor 1 to be formed on the photoconductor 1. In addition, the image quality of the toner image may be deteriorated.

A plurality of developing devices 9 respectively containing toners of different colors are prepared, and these developing devices are selectively attached to the main body of the image forming apparatus for use to form an image of a desired color. In the image forming apparatus of the type, when the image forming operation is first performed after the developing device 9 is replaced, the toner of the image forming device before the replacement is replaced by the seal member 2
Since the toner adheres to No. 0, when the toner adheres to the photoreceptor 1 again, the adhered toner becomes very noticeable, and the image quality is particularly deteriorated. Since the color of the toner image formed by the developing device 9 after the replacement is different from the color of the toner redeposited from the seal member 20 on the photoconductor 1, the adhered toner is very noticeable.

In order to prevent the above-mentioned problems, at the start of the image forming operation, the photoconductor 1 is slightly reversed in the direction opposite to the direction of arrow A in FIG. 1 and remains linearly on the photoconductor 1. The toner is moved to the front side of the pressure contact portion of the cleaning blade 18, and then the cleaning blade 18 is pressed against the surface of the photoconductor 1 to rotate the photoconductor 1 in the direction of arrow A in the forward direction and linearly moved by the cleaning blade 18. Although a method of removing the residual toner has been proposed, if the photoconductor 1 is reversed in this way, the structure becomes complicated, and further, the photoconductor 1 is reversed, forwardly rotated, and the cleaning blade 18 is pressed and released. Inevitably, the timing control becomes complicated and the cost of the image forming apparatus increases.

[0021]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned conventional drawbacks and, with a simple structure, the toner adhering to the seal member of the developing device redeposits on the electrostatic latent image to form a toner image An object of the present invention is to provide an image forming apparatus capable of preventing a defect that deteriorates image quality.

[0022]

In order to achieve the above object, the present invention provides a latent image forming means for forming an electrostatic latent image on a latent image carrier and a visible image as the toner image. And a cleaning device for cleaning the toner remaining on the latent image carrier after the transfer, and the cleaning device is a latent image carrier. The developing device has a cleaning blade that can be brought into and out of contact with the latent image carrier when removing residual toner, In order to prevent that toner from scattering to the outside, it has a seal member that contacts the surface of the latent image carrier, and electrostatically removes the toner in the developing area between the counter electrode and the latent image carrier. An image forming apparatus for converting a latent image into a visible image by converting the latent image into a latent image The toner that remains on the carrier when the cleaning blade is separated from the latent image carrier and that adheres to the seal member as the latent image carrier rotates is electrostatically charged to the latent image carrier. There is proposed a structure of an image forming apparatus having a pattern forming means for forming a latent image pattern for shifting to the latent image carrier on the latent image carrier prior to forming the electrostatic latent image.

At this time, the absolute value of the difference between the surface potential of the latent image pattern and the surface potential of the background portion around it is calculated as the absolute value of the difference between the surface potential of the electrostatic latent image and the surface potential of the background portion around it. It is desirable to set it larger than the value.

Further, when the latent image pattern passes through the developing area facing the counter electrode, the absolute value of the difference between the surface potential of the pattern and the bias voltage applied to the counter electrode is the absolute value of the electrostatic latent image. It is also advantageous to set it to be smaller than the absolute value of the difference between the surface potential of the latent image and the bias voltage applied to the counter electrode when passing through the developing area facing the electrode.

Further, when the latent image pattern passes through the developing area facing the counter electrode, it is advantageous to prohibit the developer from being conveyed to the developing area.

Further, it is desirable to form the latent image pattern at the first image forming operation performed after the cleaning blade of the cleaning device is separated from the latent image carrier.

Further, a plurality of developing devices respectively accommodating toners of different colors can be selectively attached to the main body of the image forming apparatus, and the latent image is generated at the first image forming operation after replacing the developing devices. It can also be configured to form an image pattern.

Further, it is advantageous that the latent image forming means also serves as the pattern forming means.

[0029]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an image forming apparatus according to an embodiment of the present invention. Since the basic structure and operation of the image forming apparatus have been described above, the description thereof will be omitted here.

As described above, when the cleaning blade 18 is separated from the surface of the photoconductor 1 after the image forming operation is completed, linear toner remains on the photoconductor 1. Further, when the cleaning blade 18 is pressed against the surface of the photoconductor 1 to start the image forming operation and the photoconductor 1 is rotated in the direction of arrow A, the toner remaining on the photoconductor 1 is sealed by the developing device 9. Attach to the member 20. In the conventional image forming apparatus, the adhered toner is re-adhered to the electrostatic latent image on the photoconductor 1, but in the image forming apparatus of this example, the photoconductor 1 is used to eliminate this problem. Prior to forming the electrostatic latent image 7 (FIG. 2) on the latent image pattern 21, the latent image pattern 21 is formed on the photoconductor 1, and the toner adhering to the seal member 20 is electrostatically applied to the latent image pattern 21 as described above. It is configured to make a transition. With the start of image forming operation,
Before the electrostatic latent image 7 first formed on the photoconductor 1 passes through the seal member 20, the latent image pattern 21 is passed through the seal member 20 to remove the toner attached to the seal member 20. The seal member 20 is moved to the image pattern 21.
To clean.

In this way, even if the electrostatic latent image 7 passes through the seal member 20, the toner does not adhere to the latent image 7 from the seal member 20, and the latent image 7 is described above by the developing device 9. When it is developed as described above, it is possible to prevent the image quality of the toner image from deteriorating. Of course, the toner attached to the latent image pattern 21 is not transferred to the transfer paper 13 and is removed from the photoconductor 1 by the cleaning device 16. In this way, the image quality deterioration of the toner image can be prevented without reversing the photoconductor 1 at the start of the image forming operation.

A dedicated device may be used as the pattern forming means for forming the latent image pattern 21 on the photosensitive member 1.
In the embodiment shown in FIG. 1, the latent image forming means, that is, the charger 2 and the writing unit 4 also serve as the pattern forming means. This can simplify the configuration of the image forming apparatus.

FIG. 3 is a timing chart showing the sequence of the image forming operation. When a print switch (not shown) is pressed, the image forming operation, that is, the printing operation is started, and the photoconductor 1 rotates in the direction of arrow A in FIG. Is started ((a) in FIG. 3). At the same time the cleaning device 16
The cleaning blade 18 comes into pressure contact with the surface of the photoconductor 1 to start the cleaning operation ((f) in FIG. 3).

On the photoconductor 1, the toner remaining on the photoconductor 1 when the cleaning blade 18 is separated from the photoconductor 1 after the previous image forming operation is completed is linearly formed on the position of the cleaning blade 18. The photoconductor portion to which the residual toner has adhered passes through the charger 2 as the photoconductor 1 starts rotating, and then a high voltage is applied to the charger 2 to The charging device 2 performs corona discharge for the time period indicated by t in (b), and the photosensitive member 1 is charged with a negative polarity. The charging area at this time is shown by reference numeral 22 in FIG.

When the charging area 22 passes through the exposure section 3, a laser beam 5 is emitted from the writing unit 4 as shown by t ₁ in FIG. Becomes a low potential portion, and this becomes a latent image pattern 21. The photoconductor portion on the upstream side in the rotating direction of the photoconductor 1 becomes the image region 6 with respect to the charging region 22 in which the latent image pattern 21 is formed. As described above, the charging by the charger 2 and the laser beam 5 are performed here. The electrostatic latent image 7 is formed by the image exposure by. In this way, the latent image pattern 21 is formed prior to the formation of the electrostatic latent image 7.

On the other hand, with respect to the rotation direction of the photoconductor 1, the residual toner linearly attached to the photoconductor portion on the downstream side of the latent image pattern 21 is attached to the seal member 20,
When the latent image pattern 21 passes through the seal member 20, the toner attached to the seal member 20 is electrostatically redeposited on the photoconductor 1. FIG. 4 shows the state of the toner re-attached to the photoconductor 1 with diagonal lines, but as can be seen from this figure,
Toner mainly adheres to the edges of the latent image pattern 21.

Since the seal member 20 can be cleaned in this manner, the residual toner does not adhere to the electrostatic latent image 7. After that, the electrostatic latent image 7 is transferred to the developing device 9 as described above.
The toner image is visualized as a toner image by the image forming operation.

The latent image pattern 21 shown in FIG. 2 is formed in a linear or strip shape extending in the axial direction of the photoconductor 1 and has a length L equal to the width W of the image area 6 or longer than this width. Have As a result, it is possible to reliably prevent the residual toner attached to the seal member 20 from attaching to the electrostatic latent image 7 in the image area 6.

The surface potential of the latent image pattern 21 and the surface potential of the background portion 23 which is the charged area 22 around the latent image pattern 21 can be appropriately set, but the larger the difference between these surface potentials,
It is considered that the effect of removing the toner adhering to the seal member 20 can be enhanced. Therefore, in this example, the absolute value of the difference between the surface potential Va ′ of the latent image pattern 21 and the surface potential Vd ′ of the background portion 23 around it is calculated as the absolute value of the surface potential Va of the electrostatic latent image 7 and the background portion 8 around it. Is set to be larger than the absolute value of the difference between the surface potential Vd and the surface potential Vd, so that the toner attached to the seal member 20 can be effectively transferred to the latent image pattern 21.

As described above, in this example, the surface potential Va of the electrostatic latent image 7 is set to -100V, and the surface potential Vd of the background portion 8 around it is set to -800V. Therefore, the absolute value of the difference |
Va-Vd | is 700V. Therefore, the charging area 22 is charged to, for example, −950V by the charger 2, the surface potential Vd ′ of the background portion 23 is set to −950V, and the surface potential Va ′ of the latent image pattern 21 is set to −100V. The absolute value of the difference is set to 850V. The state of the surface potential at this time is shown in FIG.

Even if the number of linear or strip latent image patterns 21 as shown in FIGS. 2 and 4 is one, toner can be sucked from the seal member 20, but the number is large. As a result, the toner suction effect can be enhanced.

According to the experiment, the surface potential Va 'of the latent image pattern 21 is -100 V and the surface potential Vd' of the background portion 23 is-.
The effect of attracting toner from the seal member 20 was higher when one latent image pattern 21 having a width of 5 mm was formed than when one latent image pattern 21 having a width of 950 V and a width of 1 mm was formed. In addition, 3 latent image patterns 21 with a width of 1 mm
The toner suction effect increases as the number increases to 5,
The image quality of the toner image could be further improved. Further, the surface potential Va ′ of the latent image pattern is −100 V, the surface potential Vd ′ of the background portion 23 is −800 V, and the latent image pattern 21 is one with a width of 5 mm, one with a width of 1 mm, and five with a width of 1 mm. As a result of each experiment, the surface potential V of the background portion 23
It was possible to obtain the result that the toner suction effect is slightly lower than that when d'is set to -950V, and the toner suction effect is enhanced as the number of latent image patterns 21 is increased.

The shape of the latent image pattern 21 is shown in FIGS.
However, the latent image pattern may have a width W of the image region 6 in any case, for example, a dot-shaped pattern or a zigzag pattern may be used.
It is desirable to be formed entirely.

By the way, the latent image pattern 21 as described above is used.
When the pattern is formed on the photoconductor 1 and the pattern is passed through the developing device 9 as it is, the pattern 21 is developed and a large amount of toner adheres to the pattern 21. Such toner is
It can be removed by the cleaning device 16,
Originally, if a large amount of toner that is not necessary for image formation is cleaned by the cleaning device 16, the cleaning device 16 will be overloaded. In addition, the toner is wastefully consumed.

Therefore, in this example, when the latent image pattern 21 passes through the developing area facing the developing roller 11 which is the counter electrode, the surface potential Va ′ of the pattern 21 and the bias voltage applied to the developing roller 11. The absolute value | Va'-Vb | of the difference from Vb is the surface potential V of the latent image 7 when the electrostatic latent image 7 passes through the developing area facing the developing roller 11.
It is set to be smaller than the absolute value | Va−Vb | of the difference between a and the bias voltage Vb applied to the developing roller 11 (see (d) of FIG. 3).

In this example, the bias voltage Vb of the developing roller 11 when the electrostatic latent image is visualized is set to -6 as described above.
Since it is set to 00V, when the latent image pattern 21 passes the developing roller 11, the bias voltage Vb applied to the roller 11 is set to, for example, -400V. By doing so, the intensity of the electric field formed between the latent image pattern 21 and the developing roller 11 when passing through the developing roller 11 can be weakened, the latent image pattern 21 is developed, and a large amount of toner adheres to it. Can be prevented.

In order to achieve the same purpose, when the latent image pattern 21 passes through the developing area facing the developing roller 11, the developer D (FIG. 1) is prohibited from being conveyed to the developing area. You may. For example, latent image pattern 2
When 1 passes through the developing area, the rotation of the developing roller 11 is stopped so that the toner does not transfer to the latent image pattern 21 (see (e) in FIG. 3). After the latent image pattern 21 has finished passing through the developing area, the developing roller 11 is rotated,
The developer D is conveyed to the developing area to visualize the electrostatic latent image 7. Even with such a configuration, it is possible to prevent a large amount of toner from adhering to the latent image pattern 21, reduce the load on the cleaning device 16, and suppress wasteful consumption of toner.

When forming images continuously, electrostatic latent images 7 are sequentially formed on the photoconductor 1, and these are sequentially visualized as toner images, and the toner images are fed one by one. The transferred paper 13 is sequentially transferred. At that time, the latent image pattern 21 may be formed prior to the formation of each electrostatic latent image 7, but the first image formation performed after the cleaning blade 18 of the cleaning device 16 is separated from the photoconductor 1. If the latent image pattern 21 is formed during operation, even if the latent image pattern 21 is formed only once,
The toner attached to the seal member 20 can be removed, and the deterioration of the image quality of the toner image can be prevented. For example, a separation signal generated when the cleaning blade 18 is separated from the photoconductor 1 with the end of the image forming operation is stored, and when the next image forming operation is started, the separation signal is first formed. Prior to forming the electrostatic latent image
The image forming apparatus may be controlled so as to form the latent image pattern 21.

When a plurality of developing devices 9 respectively containing toners of different colors can be selectively attached to the main body of the image forming apparatus for use, after the developing devices 9 are replaced, the operation is performed. If the latent image pattern 21 is formed on the photoconductor 1 during the first image forming operation to remove the toner adhering to the seal member 20, the residual toner of different colors deteriorates the image quality of the toner image. Can be prevented.

Also in this case, for example, the formation of the latent image pattern as described above may be controlled by the exchange signal generated when the developing device 9 is exchanged.

As shown in FIG. 6, the image area 6 on the photoconductor 1 is charged to a predetermined polarity, for example, a positive polarity, and the portion not irradiated with light by image exposure becomes the electrostatic latent image 7.
In the image forming apparatus of the type in which the toner charged to the opposite polarity to this latent image is electrostatically transferred to form a toner image,
Each configuration described above can be applied as it is. In this case,
The latent image pattern 21 is charged with a polarity opposite to the charging polarity of the toner by the pattern forming means including a charger, and the background portion 23 around the latent image pattern 21 is not charged by the charger or once charged, and then exposed to light. It becomes a portion where the surface potential is dropped by being irradiated.

[0053]

According to the image forming apparatus of the first aspect of the present invention, the toner adhered to the seal member of the developing device is electrostatically charged on the latent image bearing member without reversing the latent image bearing member at the start of the image forming operation. It is possible to prevent the problem of reattachment to the latent image and deterioration of the image quality of the toner image.

According to the image forming apparatus of the second aspect,
The effect of attracting the toner adhering to the seal member to the latent image pattern side can be further enhanced.

According to the image forming apparatus of the third or fourth aspect, it is possible to prevent a large amount of toner from the developing device from adhering to the latent image pattern, prevent wasteful consumption of toner, and place an excessive burden on the cleaning device. You can prevent the trouble of applying.

According to the image forming apparatus of the fifth or sixth aspect, it is possible to effectively prevent the problem that the toner adhering to the seal member redeposits on the electrostatic latent image.

According to the image forming apparatus of claim 7,
It is not necessary to provide an independent pattern forming means, the structure of the image forming apparatus can be simplified, and the increase in cost can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing an unfolded photosensitive member for explaining an electrostatic latent image and a latent image pattern formed on the photosensitive member.

FIG. 3 is a timing chart showing an example of an image forming operation.

FIG. 4 is an explanatory view similar to FIG. 2, schematically showing toner attached to a latent image pattern.

FIG. 5 is an explanatory diagram showing surface potentials of an electrostatic latent image and a latent image pattern.

FIG. 6 is an explanatory view similar to FIG. 2, illustrating another method of forming an electrostatic latent image.

[Explanation of symbols]

 7 Electrostatic Latent Image 8 Background Part 9 Developing Device 16 Cleaning Device 18 Cleaning Blade 20 Sealing Member 21 Latent Image Pattern 23 Background Part D Developer

Claims (7)

[Claims] 1. A latent image forming unit that forms an electrostatic latent image on a latent image carrier, a developing device that visualizes the electrostatic latent image as a toner image, and the toner image is transferred onto a transfer material. Transfer means,
And a cleaning device for cleaning the toner remaining on the latent image carrier after the transfer.
The developing device has a cleaning blade that can be brought into and out of contact with the latent image carrier and is brought into pressure contact with the surface of the latent image carrier when removing the residual toner, and the developing device is opposed to the latent image carrier. It has an electrode and a seal member that contacts the surface of the latent image carrier to prevent the toner inside from scattering to the outside, and the toner in the developing area between the counter electrode and the latent image carrier is kept static. In an image forming apparatus for electrically converting the latent image into an electrostatic latent image to visualize the latent image, the cleaning blade remains on the latent image carrier when the cleaning blade is separated from the latent image carrier, and the latent image carrier is carried. Prior to forming the electrostatic latent image, a latent image pattern for electrostatically transferring the toner adhered to the seal member with the rotation of the body to the latent image carrier is formed on the latent image carrier. Image formation characterized by having pattern forming means for forming apparatus. 2. The absolute value of the difference between the surface potential of the latent image pattern and the surface potential of the background portion around it is the absolute value of the difference between the surface potential of the electrostatic latent image and the surface potential of the background portion around it. The image forming apparatus according to claim 1, wherein the image forming apparatus is set larger than the above. 3. The electrostatic latent image represents the absolute value of the difference between the surface potential of the latent image pattern and the bias voltage applied to the counter electrode when the latent image pattern passes through a developing region facing the counter electrode. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is set to be smaller than an absolute value of a difference between a surface potential of the latent image and a bias voltage applied to a counter electrode when passing through a developing area facing the counter electrode. 4. The image forming apparatus according to claim 1, wherein when the latent image pattern passes through a developing area facing the counter electrode, the conveyance of the developer to the developing area is prohibited. 5. The latent image pattern is formed during a first image forming operation performed after the cleaning blade of the cleaning device is separated from the latent image carrier.
5. The image forming apparatus according to any one of 4 to 4. 6. A plurality of developing devices respectively accommodating toners of different colors can be selectively attached to the main body of the image forming apparatus, and the latent image is formed during the first image forming operation performed after the developing devices are replaced. The image forming apparatus according to claim 1, which forms an image pattern. 7. The image forming apparatus according to claim 1, wherein the latent image forming unit also serves as a pattern forming unit.