JPH11249519A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently supply a cleaning assistant by the quantity to be consumed by being transferred on an image without being excessively accumulated by providing a cleaning assistant supply means in addition to a toner supply means. SOLUTION: This image forming device is provided with the cleaning assistant supply means 7 supplying the cleaning assistant having reverse polarity to toner to the toner of a developing unit 2. Then, the supply means 7 is actuated by a control means 22 according to an image forming condition. Besides, the device is provided with a recycling means 6 constituted so that the toner scraped and recovered from an image carrying surface 9a on which the image is transferred by using a cleaning blade 4a and the like by a cleaning means 4 is returned to the developing unit 2 and recycled. The supply means 7 is constituted so that the cleaning assistant can be supplied to the toner in the developing unit 2 by using the recycling and carrying path of the recycling means 6 in common. Thus, only the quantity of cleaning assistant corresponding to the actual consumption is efficiently supplied according to the image forming condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly, to developing an image with a developer and cleaning an image bearing surface after a developed image is transferred to another. And an image forming apparatus.

[0002]

2. Description of the Related Art There is an increasing demand for higher image quality, and further improvement in fluidity is required due to the need for high chargeability and stable supply of toner as a developer. A large amount of a small-diameter external additive is supplied for high fluidization.
On the other hand, the amount of such external additives accumulated at the edge portion of the cleaning blade changes depending on the supply amount, and when the amount of accumulation increases due to the large amount of supply, this enters the nip portion between the cleaning blade and the image bearing surface. As a result, black spots and filming are formed on the image bearing surface, causing image noise. To cope with this, fine particles having a relatively large diameter are added to the developer as a cleaning aid, and the amount of the external additive accumulated at the edge of the cleaning blade is controlled.

[0003] This is because the problem related to the cleaning described above generally occurs in the non-image portion of the image bearing surface. That is, if a sufficient amount of toner is supplied, it is possible to prevent substances such as external additives that contaminate the image bearing surface at the edge of the cleaning blade from entering the nip between the cleaning blade and the image bearing surface. However, the non-image area is susceptible to contaminants because there is not enough toner.

Conventionally, to solve such a problem,
As a cleaning aid, a material having a characteristic of producing a good stationary layer mainly at the tip of a cleaning blade corresponding to a non-image portion and exerting an action of scraping contaminants on the image bearing surface by appropriately passing through the nip is used. ing.
As such a cleaning aid, metal oxide fine particles such as strontium titanate, barium titanate and potassium titanate are used.

[0005] The patent publication published in Japanese Patent No.
An image forming apparatus using a plurality of developing devices, one developing device,
In particular, disclosed is a technique that can cope with a case where the use of a cleaning aid is inappropriate in a plurality of developing units by using a developer externally added with a cleaning aid only for a developing device using a black toner. .

[0006]

By the way, in many cases, a cleaning assistant having a polarity opposite to that of the toner is used, and the consumption ratio of the cleaning assistant to the toner is small. Therefore, as the number of times of development and the development time increase, the ratio of the cleaning aid to the toner increases. Further, when the toner removed from the image bearing surface by the cleaning unit by the cleaning blade is returned to the developing unit for recycling, the cleaning aid removed together with the toner by cleaning is also returned to the developing device and recycled. The accumulation ratio of the cleaning aid to the toner in the developing device increases.

When the accumulation ratio of the cleaning aid to the toner increases and the cleaning aid exceeds the amount consumed on the image together with the developer, the cleaning aid gradually accumulates in the developing device, and fog is caused by aggregation of the toner and poor charging. And image noise such as white spots occur. On the other hand, if the cleaning aid is less than the predetermined ratio with respect to the developer, the above-described problem of image noise due to the external additive occurs.

However, the one disclosed in the above-mentioned publication cannot solve such a problem, and an image forming apparatus that addresses this problem has not yet been provided.

An object of the present invention is to provide an image forming apparatus capable of preventing a cleaning aid from being excessively or deficiently and obtaining a high-quality image stably for a long period of time.

[0010]

In order to achieve the above object, an image forming apparatus of the present invention comprises a developing means for developing an image with a developer at the time of image formation, and a developing means for developing the image at the time of image formation. When cleaning the image bearing surface after transferring an image to another, a cleaning aid supply means for supplying a cleaning aid having a polarity opposite to that of the developer to the developer of the developing means; And a control means for causing the cleaning aid supply means to act accordingly.

In such a configuration, the image bearing surface carries a visible image developed with a developer, and transfers the image to another to form an image. However, the cleaning is performed when cleaning the image bearing surface after the transfer. A cleaning aid supply means is provided to use a developer having a polarity opposite to that of the developer, and the cleaning aid is supplied in accordance with image forming conditions, that is, the supply of the cleaning aid, that is, the supply timing and the supply amount at that time. By controlling image forming conditions, for example, when power is turned on for image formation, or conditions such as the number and time of image formation, the amount of developer replenishment, and the amount of developer recycled, Correspondingly, the cleaning aid can be supplied in an amount commensurate with the actual consumption, preventing the cleaning aid from becoming excessive or insufficient in the developing means, and obtaining a high-quality image stably for a long time. It is.

The image bearing surface of such an image forming apparatus develops a latent image carried at the time of image formation, carries a visible image, and transfers the latent image to a transfer material or an intermediate transfer member. This is an intermediate transfer member that transfers and carries a visible image and retransfers it to a transfer material or the like. The form of an image carrier such as a drum or a belt is not particularly limited. Further, the image forming apparatus includes a cleaning unit for the cleaning, and further includes a recycling unit that returns the developer removed from the image bearing surface by the cleaning unit to the developing unit so that the developer is recycled. You may.

When the recycling means is provided, the cleaning aid supply means is provided on the recycling conveyance path from the cleaning means portion of the recycling means to the developing means.
The cleaning aid is sent to the developing means by using the recycle transport path in common, and can be supplied to the developer.

The specific control of the cleaning aid supply means corresponding to the image forming conditions by the control means is to increase the supply amount of the cleaning aid at a high temperature. Further, when the developer is replenished at a high amount, the supply amount of the cleaning aid is increased.
When the amount of the recycled developer is large, the supply amount of the cleaning aid is reduced.

These features of the present invention can be applied individually to the extent possible or in combination with one another.
Further objects and features of the present invention will become apparent from the following detailed description and drawings.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, typical embodiments of the present invention will be described in detail with reference to the drawings.

This embodiment is an image forming apparatus used for a copying machine, a printer, and a facsimile, and as shown in FIG. 1, one developing unit 2 is provided around an image carrier 9 to form a monochromatic image. This is an example of an image forming mechanism. However, this image forming mechanism is arranged in tandem or a plurality of developing units are arranged around one image carrier 9 to form an image of a plurality of colors or an image obtained by combining a plurality of colors. The present invention also applies to the device.

The image carrier 9 of the present embodiment is used as a drum type as shown in the figure or as a belt type (not shown). However, the image carrier 9
There is no particular limitation on the form of the image and the image forming format for carrying a visible image using the form. The illustrated image carrier 9 is a variety of photoconductors, and is driven to rotate in the direction of the arrow shown in the figure, and has image information on the image carrier surface 9 a uniformly charged by the charger 1, that is, the surface. An image is sequentially exposed to light 10 to form an electrostatic latent image. This latent image is moved in the direction of the arrow along with the rotation of the image carrier 9 and is developed by a toner as a developer in a developing device 2 as a developing means to be visualized. Thereafter, the image carrier 9 carries a developed image by development.

When the image carrier 9 is an intermediate transfer member, a visible image formed by developing the latent image on the photoreceptor as described above is electrostatically transferred to the image carrier surface 9a. It carries a visible image.

The developing device 2 stores the toner in a storing portion 2a and supplies the toner to a developing roller 2b to perform various types of development such as a magnetic brush method and a cascade method. High fluidity is required for stable supply of toner regardless of whether it is a one-component developer or a two-component developer, and high fluidity is important for a two-component developer since charging is particularly performed by stirring. . For this reason, development is carried out by incorporating a relatively small percentage of external additives into the toner. The toner is replenished by the replenishing means 8 in accordance with the consumption.

The developed image after development is moved in the direction of the arrow as the image carrier 9 rotates. In accordance with this, the transfer material 1 sent out from a paper feed tray (not shown) or manually
1 is sent to the timing roller 14 along the transport path 13 in the direction of the arrow shown in FIG. Timing roller 14
Supplies the transfer material 11 at a timing synchronized with the visualized image on the image carrier 9. The transfer material 11 sent from the timing roller 14 advances to a transfer section. The image carrier 9 is provided in the transfer section.
Type transfer device 3 facing image carrying surface 9a
a, a separator 3b is provided, and the visible image on the image bearing surface 9a is electrostatically transferred by the transfer device 3a onto the transfer material 11 passing therethrough at a portion facing the transfer device 3a. Transfer material 11 after transfer
Is separated from the image bearing surface 9a by the separator 3b.

The separated transfer material 11 is conveyed to a fixing unit (not shown), subjected to a fixing process by heating and / or pressurization to complete image formation, and is discharged to a paper discharge tray (not shown) provided outside the apparatus. The transfer material 11 is a paper or a resin OHP sheet.

The method of transferring the visible image to the transfer material 11 and the method of separating the transferred transfer material 11 from the image bearing surface 9a are not particularly limited. Various schemes can be employed.

The image bearing surface 9a of the image carrier 9 after the transfer is cleaned by the cleaning blade 4a or the like by the cleaning means 4 and the residual charge is removed by the eraser lamp 12 or the like, so that the image is prepared for the next image formation. For this cleaning, the edge 4b1 at the tip of the cleaning blade 4a is pressed against the image bearing surface 9a by urging of a spring 4b or the like.
The cleaning means 4 may be a combination of a fur brush and the like.

When the image carrier 9 is an intermediate transfer member, the transfer and cleaning steps are not particularly changed. If the intermediate transfer member is to transfer a plurality of images formed by the photoreceptor, for example, images of different colors in a multiplex manner and collectively re-transfer these to the transfer material 11 to form a composite image, After the transfer of the number of images is completed, the carried visual image is retransferred to the transfer material.

As one embodiment, the image forming apparatus shown in FIG. 1 is a digital copying machine, and the image exposure is performed, for example, as follows. The original placed on the original glass is illuminated by an exposure lamp along with the movement of an image reader unit (not shown), and the reflected light at that time is imaged on a line sensor via a lens array of the image reader unit, and is optically converted as image data. It is transmitted to the scanning means.
The optical scanning means exposes the image carrier 9 with a light output 10 from an optical element such as a laser diode based on the image data, and forms an electrostatic latent image corresponding to the original image.

In the analog copying machine, the reflected light from the original is focused directly on the image bearing surface 9a of the image carrier 9 via a lens. In a printer, image data is provided to an optical element of a scanning optical unit from an image data source. There are various types of image data sources, such as those stored in an external recording medium or an internal storage means, those provided by communication, or those provided from an external device such as a personal computer or a digital camera.

By the way, in this embodiment, a cleaning aid is used, and the above-mentioned external additive is used as the cleaning blade 4.
By controlling the amount accumulated in the edge portion 4a1 of a,
Image noise due to black spots and filming of the external additive is not generated. The cleaning aid used has a polarity opposite to that of the toner. A cleaning aid having a polarity opposite to that of the toner has a different consumption rate from the toner, and excess or deficiency occurs in the developer depending on image forming conditions.

Therefore, in the present embodiment, a cleaning aid supply means 7 for supplying a cleaning aid having a polarity opposite to that of the toner to the toner in the developing device 2 is provided.
2, the cleaning aid supply means 7 is operated according to the conditions of image formation. In the embodiment shown in FIG. 1, there is provided a recycling unit 6 for returning the toner scraped and collected by the cleaning blade 4a or the like from the image bearing surface 9a after the transfer by the cleaning unit 4 to the developing unit 2 so as to be recycled. Therefore, the cleaning aid supply means 7 supplies the cleaning aid to the recycle transport path of the recycle means 6 so that the cleaning aid can be supplied to the toner in the developing device 2 using the recycle transport path.

The recycling means 6 transfers the collected toner collected in the toner collecting section 4c provided in the cleaning means 4 into the collected toner conveying pipe 6a by rotating the screw 5 shown in FIGS. Send to The collected toner transport pipe 6a also incorporates a screw (not shown), and conveys the collected toner that has been sent in, returns it to the replenishing means 8 provided in the developing device 2, and supplies the toner in the developing device 2 with the replenishing device 8. To be supplied. The cleaning aid supply means 7 may be provided at any part of the recycling conveyance path. In the embodiment shown in FIG. 1, the cleaning aid supply means 7 is provided in the middle of the collected toner conveyance pipe 6a.

In this manner, the cleaning aid supply means 7 is provided, and the cleaning aid is operated by the control means 22 in accordance with image forming conditions to control the supply of the cleaning aid, that is, the supply timing and the supply amount at that time. By doing so, the actual conditions for image formation, for example, when the power for image formation is turned on, or the number and time of image formation, the amount of toner replenishment, the amount of toner recycled, and the like, can be adjusted according to the actual conditions. The cleaning agent can be efficiently supplied in an amount corresponding to the consumption amount, and the developing device 2
This prevents the amount of the cleaning aid from becoming excessive or insufficient, and a high-quality image can be stably obtained for a long term. The cleaning aid is preferably a metal oxide fine particle, such as strontium titanate, barium titanate, and potassium titanate.

The recycling means 6 is not essential, and if it is not provided, the cleaning aid supplying means 7 is provided with the toner replenishing means 8
May be supplied directly to However, by providing the cleaning aid supply means 7 on the recycle transport path from the cleaning means 4 of the recycle means 6 to the developing device 2, the cleaning aid can be supplied using the recycle transport path in common. Further, when the supply of the cleaning aid is directly supplied to the storage section 2a of the developing device 2 without passing through the replenishing means 8, it becomes easy to supply the toner independently of the replenishment of the toner by the replenishing means 8. However, when the cleaning aid is supplied in proportion to the toner supply amount, such control can be easily achieved by always supplying a constant amount of the cleaning aid to the supply means 8.

The specific control of the cleaning aid supply means 7 by the control means 22 according to the image forming conditions is such that the supply amount of the cleaning aid is increased at a high temperature in the apparatus, and the cleaning aid is supplied to the image bearing surface 9a such as an external additive. Corresponds to easy adhesion. Also, when the toner supply amount is high, the supply amount of the cleaning aid is increased to avoid running out of the cleaning aid. When the amount of recycled toner is large, the supply amount of the cleaning aid is reduced to prevent the cleaning aid from becoming excessive. Any one of these is effective, but the larger the number of combinations to be executed, the more preferable it is because the supply amount of the cleaning aid can be more appropriately controlled. For such control, information relating to image forming conditions, such as temperature data detected by the temperature sensor S, a power-on signal for image formation, and a signal for image forming operation, is input to the control unit 22. From the information thus obtained, the number of image formation sheets is counted by a counter C, or the total time of image formation is measured by a timer T, and based on these, the judgment means J judges the timing and amount of supply of the cleaning aid. The control means 22 activates the cleaning aid supply means 7 based on the determination result.

When the cleaning aid supply means 7 is to supply the cleaning aid by a fixed amount at a time by rotating a screw or by another constant-rate feeding mechanism, the cleaning aid supply means 7 is driven for a certain time each time the cleaning aid supply means 7 is operated to supply the cleaning aid. Is easy to control. In some cases, the supply amount can be adjusted by changing the driving time or the driving speed according to the image forming conditions at that time.
When the supply of the cleaning aid is performed by a mechanism independent of the replenishing unit 8 and the supply amount matches the replenishment amount of the toner, a replenishment operation signal of the toner is input to the control unit 22.
The supply timing and supply amount may be controlled. Although the control unit 22 is dedicated to the cleaning aid supply unit 7, a microcomputer for controlling the operation of the image forming apparatus can be used in common. In addition, when there is another image forming condition that causes the excess or deficiency of the cleaning aid, it is preferable to control the supply of the cleaning aid even in response to such conditions.

[0035]

According to the image forming apparatus of the present invention, by providing the cleaning aid supply means separately from the toner supply means, excessive cleaning aid is not accumulated in the development means, and the image is formed on the image. Since the necessary amount can be always secured by efficiently supplying the amount by which the cleaning aid is consumed after being transferred, high image quality can be stably obtained over a long period of time.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing a toner collecting unit in a cleaning unit of the apparatus of FIG. 1 and a part of a recycling unit for recycling and using the collected toner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charger 2 Developing device 2a Storage part 2b Developing roller 3a Transfer device 4 Cleaning means 4a Cleaning blade 4c Toner collecting part 5 Screw 6 Recycling means 7 Cleaning aid supply means 8 Replenishment means 11 Transfer material 22 Control means S Temperature sensor C counter T timer J judgment means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Sakakibara 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Kenzo Toya Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Osaka Metropolitan Building Minolta Co., Ltd. (72) Inventor Hiroshi Fukao 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Co., Ltd.

Claims (9)

[Claims] A developing means for developing an image with a developer at the time of image formation, and a developing means for cleaning an image bearing surface after transferring a developed image carried by the development carried at the time of image formation to the other. An image forming apparatus comprising: a cleaning aid supply unit that supplies a cleaning aid having the cleaning aid to a developer of a developing unit; and a control unit that activates the cleaning aid supply unit according to image forming conditions. apparatus. 2. An image bearing member having an image bearing surface, cleaning means for cleaning the image bearing surface of the image bearing member, and a developer removed from the image bearing surface by cleaning returned to the developing means for recycling. The image forming apparatus according to claim 1, further comprising: a recycling unit configured to perform the operation. 3. The image forming apparatus according to claim 1, wherein the cleaning aid supply unit is provided on a recycling conveyance path from the cleaning unit to the developing unit. 4. The image forming apparatus according to claim 1, wherein the control unit includes at least one of a power-on state, an image forming number, and an image forming time as image forming conditions.
4. The image forming apparatus according to claim 1, wherein the cleaning aid supply unit operates to supply a predetermined amount of the cleaning aid at a timing based on the timing. 5. 5. The image forming apparatus according to claim 1, wherein the control unit controls the supply of the cleaning assistant in accordance with an internal temperature of the apparatus as an image forming condition. 6. The image forming apparatus according to claim 5, wherein the supply amount of the cleaning aid is increased at a high temperature. 7. The image forming apparatus according to claim 1, wherein the control unit controls the supply of the cleaning aid in accordance with a replenishing amount of the developer as an image forming condition. 8. The image forming apparatus according to claim 7, wherein the control unit increases the supply amount of the cleaning aid when the developer is replenished at a high amount. 9. The image forming apparatus according to claim 3, wherein the control means reduces the supply amount of the cleaning aid when the amount of the recycled developer is large.