JPH09127772A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device forming a stabilized image without having white void by reducing toner consumption by recycling toner. SOLUTION: Voltage having a reverse polarity to normal developing bias voltage is applied to the developing roller 14a of a developing device 14, so that toner agglomerate incorporated in the toner recycled by a toner recycling mechanism 20 and coarse particles are surely separated from the developing roller 14a. The toner agglomerate and the coarse particles increased in terms of acceleration with the increase of the number of times of image-forming are removed from the developing roller 14a as the time of making the voltage having the reverse polarity from the developing bias voltage applied to the developing device 14 is extended. Thus, the white void caused when an electrostatic latent image is repeatedly developed by recycling the toner by the toner recycling mechanism is prevented.

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 capable of providing an image without white spots by using toner recycled by a toner recycling mechanism.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic process, a predetermined potential is applied to a photoconductive photoconductor, and then light corresponding to image information is irradiated to attenuate the potential. By forming an electrostatic latent image and selectively supplying toner as a developer to the electrostatic latent image, a copy image of an object to be copied or an image to be printed is output.

Toner as a developer is electrostatically charged to each other via a carrier which is a magnetic material when a two-component developer is used and when toner is a one-component developer. The attracting force selectively adheres to the electrostatic latent image formed on the photoconductor to form a toner image corresponding to the image information.

The toner image formed on the photoconductor is transferred onto a transfer target, for example, recording paper, and is fixed on the recording paper via a fixing device. On the other hand, the untransferred toner remaining on the photoconductor is removed from the photoconductor via the cleaning device.

By the way, the toner (waste toner) removed from the photosensitive member by the cleaning device is collected in a predetermined collecting section and treated as waste. However, in recent years, a toner recycling mechanism has been proposed in which the collected waste toner is collected in a developing device or a toner hopper connected to the developing device and used again in the developing process.

According to the toner recycling mechanism, since the waste toner is not generated, the number of printable sheets is increased, and it is not necessary to discard the waste toner in the image forming apparatus, which is troublesome for the user. Will be reduced.

[0007]

However, when the toner collected by the cleaning device is returned to the developing device to form an image by using the toner recycling mechanism as described above, for example, a part of the image density of a solid image is reduced. However, there is a problem that white spots are reduced. Further, it is known that the number of areas where white spots occur (frequency of white spot occurrence) gradually increases as the number of copies, that is, the time during which the photoconductor and the developing device are rotated.

The factors that cause white spots are:
Waste toner returned to the developing device via the toner recycling mechanism is rubbed by an auger or a screw for conveying the toner while passing through the cleaning device and the toner recycling mechanism, while radiant heat from the fixing device It is conceivable that coarse particles of the toner aggregates generated by agglomeration of particles adhere to the photoconductor and remain on the photoconductor without being transferred by the transfer device, resulting in a defect in the image. An object of the present invention is to provide an image forming apparatus capable of forming a stable image without a blank image while reducing toner consumption by recycling toner.

[0009]

The present invention has been made on the basis of the above-mentioned problems, and is an image carrying area moving means for moving an image carrying area of an image carrying body at a predetermined speed, and an image of the image carrying body. Developing means for supplying a developer charged to a predetermined polarity to the electrostatic latent image formed on the carrying area by a developing bias voltage, and developing means for supplying the developer to the image carrier by the developing means. Transfer means for transferring the developer to the transfer material, and the developer supplied to the electrostatic latent image on the image bearing area of the image carrier by the developing means is not transferred to the transfer material by the transfer means. Developer recovery means for recovering the untransferred developer remaining from the image bearing area of the image carrier, a recycling mechanism for returning the developer recovered by the developer recovery means to the developing means, and the developing means,
The voltage applying means for applying a reverse voltage having a polarity different from that of the developing bias voltage, the counting means for counting the cumulative movement amount of the image bearing area of the image bearing member, and the cumulative movement amount counted by the counting means. An image forming apparatus having a voltage applying means control means for energizing the voltage applying means based on the above is provided.

Further, according to the present invention, a photosensitive region having a photosensitive region for holding a potential difference between a light irradiation portion and a non-light irradiation portion as an electrostatic latent image by being irradiated with light in a state where a predetermined electric potential is charged. A body, a motor for moving a photosensitive region of the photoconductor at a predetermined speed, and a toner carrying mechanism for carrying toner as a developer. The toner carrying mechanism is moved at a predetermined speed to A developing device for supplying the toner charged to a predetermined potential and polarity to the electrostatic latent image formed on the photosensitive area by a developing bias voltage to develop the developing device, and a developing device for supplying the toner to the photoreceptor. A transfer device for transferring the above-mentioned toner to a sheet, a developing bias power source for applying the developing bias voltage to the developing device and the toner contained in the developing device, and a toner carrying device for the developing device. A toner conveying mechanism driving device that moves the mechanism at a predetermined speed, and toner supplied to the photosensitive area of the photoconductor through the developing device is attached to the electrostatic latent image and then transferred by the transfer device to transfer the paper. To the developing device, and a cleaning device for recovering the untransferred toner left untransferred to the toner and the fog toner adhering to areas other than the photosensitive area where the electrostatic latent image is formed, and the toner recovered by the cleaning device to the developing device. A toner recycle device, a voltage applying unit that applies a reverse voltage having a polarity different from that of the developing bias voltage supplied to the developing device via the developing bias power source, and a photosensitive area of the photoconductor moves. A counter device for counting the accumulated accumulated movement amount,
Based on the accumulated movement amount counted by the counter device, the voltage applying means is energized to apply a reverse voltage having a polarity different from that of the developing bias voltage to the developing device, and the motor and the toner carrying mechanism. The present invention provides an image forming apparatus having a control means for operating a drive device for a predetermined time.

Further, according to the present invention, a photosensitive region having a photosensitive region for holding a potential difference between a light irradiation portion and a non-light irradiation portion as an electrostatic latent image by being irradiated with light in a state where a predetermined electric potential is charged. A body, a motor for moving a photosensitive region of the photoconductor at a predetermined speed, and a toner carrying mechanism for carrying toner as a developer. The toner carrying mechanism is moved at a predetermined speed to A developing device for supplying the toner charged to a predetermined potential and polarity to the electrostatic latent image formed on the photosensitive area by a developing bias voltage to develop the developing device, and a developing device for supplying the toner to the photoreceptor. A transfer device for transferring the generated toner to a sheet, a developing bias power source for applying the developing bias voltage to the developing device and the toner contained in the developing device, and a toner for the developing device A toner-conveying-mechanism driving device that moves the feeding mechanism at a predetermined speed, and the toner supplied to the photosensitive area of the photoconductor through the developing device is attached to the electrostatic latent image and then transferred by the transfer device. A cleaning device that collects the untransferred toner that remains untransferred to the paper and the fog toner that adheres to areas other than the photosensitive area where the electrostatic latent image is formed, and the toner that is collected by the cleaning device to the developing device. The toner recycle device, the voltage applying means for applying a reverse voltage having a polarity different from the developing bias voltage supplied via the developing bias power source to the developing device, and the photosensitive area of the photoconductor A counter device for counting the accumulated movement amount that has been moved,
Based on the accumulated movement amount counted by the counter device, the voltage applying means is energized to apply a reverse voltage having a polarity different from that of the developing bias voltage to the developing device, and the counter device counts. An image forming apparatus having a control means for operating the motor and the toner conveying mechanism driving device for a long time gradually as the cumulative movement amount increases. In addition,
The present invention relates to a photoconductor having a photosensitive region that holds an electric potential difference between a light irradiation part and a non-light irradiation part as an electrostatic latent image by irradiating light with a predetermined electric potential charged, and a photosensitive member. A motor for moving the photosensitive region of the body at a predetermined speed and a toner transport mechanism for transporting toner as a developer are included. The toner transport mechanism is moved at a predetermined speed to form the photosensitive region on the photosensitive body. A developing device for supplying toner charged to the electrostatic latent image to a predetermined potential and polarity to a region to be attached by a developing bias voltage to develop the toner, and the toner supplied to the photoconductor by the developing device. A transfer device for transferring to a sheet, a developing bias power source for applying the developing bias voltage to the developing device and the toner contained in the developing device, and a toner conveying mechanism of the developing device at a predetermined speed. Toner supplied to the photosensitive area of the photoconductor via the toner transport mechanism driving device to be moved and the developing device is adhered to the electrostatic latent image and then is not transferred to the sheet by the transfer by the transfer device. A cleaning device for collecting the untransferred toner and the fog toner attached to areas other than the photosensitive area where the electrostatic latent image is formed, and a toner recycling device for returning the toner collected by the cleaning device to the developing device, In the developing device,
Voltage applying means for applying reverse voltages having different polarities to the developing bias voltage supplied via the developing bias power source; and a counter device for counting an accumulated movement amount of the photosensitive area of the photosensitive body moved. The voltage applying means is energized based on the accumulated movement amount counted by the counter device to apply a reverse voltage having a polarity different from that of the developing bias voltage to the developing device, and the counter device counts the reverse voltage. Another object of the present invention is to provide an image forming apparatus having a control means for operating the motor and the toner transport mechanism driving device by gradually dividing the motor and the toner transporting mechanism driving for a predetermined time as the cumulative movement amount increases.

Still further, according to the present invention, an image carrying area moving means for moving the image carrying area of the image carrying body at a predetermined speed, and a predetermined polarity of the electrostatic latent image formed on the image carrying area of the image carrying body. Developing means for supplying the charged developer to the area to be attached by a developing bias voltage, transfer means for transferring the developer supplied to the image carrier by the developing means to a transfer material, and The developer supplied to the electrostatic latent image in the image bearing area of the image bearing member by the developing means is the untransferred developer remaining without being transferred to the transferred material by the transfer by the transferring means. A developer collecting means for collecting from the area, a recycling mechanism for returning the developer collected by the developer collecting means to the developing means, and a voltage for applying a reverse voltage having a polarity different from the developing bias voltage to the developing means. Application A step, a counting means for counting the cumulative movement amount of the image bearing area of the image bearing member, and a voltage applying means control means for activating the voltage applying means based on the cumulative movement amount counted by the counting means. And an image capturing device that captures agglomerates of the developer separated from the developing device and coarse particles that are aggregates thereof by energizing the voltage applying device under the control of the voltage application controlling device. A forming apparatus is provided.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. According to FIGS. 1 and 2, the image forming apparatus, that is, the laser exposure type copying apparatus 2 has a photosensitive drum 10 rotatably arranged at the center of the main body of the apparatus. The photosensitive drum 10 is rotated in the direction of arrow a by the main motor 120 shown in FIG.

An electrostatic latent image corresponding to image information to be recorded is formed on the surface of the photosensitive drum 10 by a laser beam from a laser exposure device described later. Around the photosensitive drum 10, along the rotation direction (arrow a),
Charging device 1 for charging photoconductor drum 10 to a predetermined potential
2. A developing device 14 that develops the electrostatic latent image by supplying toner to the electrostatic latent image formed on the photosensitive drum 10 by a laser exposure device described later, and a developing device 14 formed on the photosensitive drum 10 by the developing device 14. A transfer device 16 for transferring a toner image onto a sheet and a cleaning device 1 for scraping off toner remaining on the surface of the photosensitive drum 10, that is, untransferred toner.
8. A charge removing device 19 for removing charges remaining on the surface of the photosensitive drum 10 is arranged in order. The static eliminator 19
Are integrally arranged on the housing of the cleaning device 18.

The untransferred toner collected by the cleaning device 18 is returned to the developing device 14 or the toner hopper between the cleaning device 18 and the toner accommodating portion of the developing device 14 or the toner hopper integrated with the developing device 14. The toner recycling mechanism 20 is connected. Toner recycling mechanism 20 and cleaning device 18
Is provided with a slight space so that toner clogging does not easily occur.

The charging device 12 includes a corona wire 12a and a grid screen 12b, is connected to a high voltage generating circuit 102 and a grid bias voltage generating device 104 which will be described later with reference to FIG. Is charged to the surface potential of.

The developing device 14 holds the two-component developer D, in which the toner T, which is a non-magnetic member, and the carrier C, which is a magnetic member, are mixed at a predetermined ratio, and only the negatively charged toner is exposed while the outer peripheral portion is held. It has a developing roller 14a to be attached to the electrostatic latent image formed on the body drum 10. The two-component developer D and the developing roller 14a are housed in a housing 14b.

The carrier C and the toner T, that is, the developer D in the developing roller 14a and the developing device 14 are shown in FIG.
A predetermined developing bias voltage is applied by the developing bias voltage generating circuit 106, which will be described later. The developing roller 14a is fixed inside, and is arranged in the circumferential direction in the S pole and the N pole.
It is composed of a magnet medium in which a plurality of poles are arranged at a predetermined angle and a non-magnetic sleeve that rotates around the magnet medium in the direction of arrow b shown in FIG. As shown in FIG. 2, the sleeve, that is, the outer peripheral surface of the developing roller 14a has a developing motor 12 connected to the motor driving circuit 110.
Rotated by 2.

Hereinafter, when developing the electrostatic latent image formed on the surface of the photosensitive drum 10, the carrier formed on the sleeve along the magnetic lines of force generated from the main magnetic pole of the magnet medium of the developing roller 14a. The toner adhered to the ears of C by the image force is in the developing area where the photosensitive drum 10 and the developing roller 14a face each other, and
The toner is moved by an electric field formed by the potential of the electrostatic latent image of 0 and the developing bias voltage, and the electrostatic latent image is developed. Further, a toner supply roller 14c for supplying the toner contained in a toner hopper (not shown) toward the developing roller 14a is provided at a position on the outer peripheral surface of the developing roller 14a facing the side in contact with the photosensitive drum 10. It is arranged. The toner supply roller 14c rotates in the same direction as the developing roller 14a rotates, that is, the outer peripheral surfaces of the toner supply roller 14c and the developing roller 14a move in opposite directions at the contact position. To be done.

The transfer device 16 integrally includes a peeling device 17, and toner is supplied by the developing roller 14a of the developing device 14 via the high voltage generating circuit 102 and the separation voltage generating circuit 108 shown in FIG. The developed and developed toner image on the surface of the photosensitive drum 10 is electrostatically attracted to, for example, a recording sheet, and the recording sheet and the toner image are released from electrostatic attraction with the photosensitive drum 10.

The cleaning device 18 includes the photosensitive drum 1.
The blade 18a and the blade 1 are pressed against the surface of the photosensitive drum 10 to scrape off the untransferred toner remaining on the surface of the photosensitive drum 10.
8a removes the toner T scraped off by the photosensitive drum 10
The auger 18 b conveys the toner in the axial direction of the photosensitive drum 10, removes and collects the untransferred toner on the surface of the photosensitive drum 10, and collects the toner toward the toner recycling mechanism 20.

An image reading unit 30 for reading an image of a copy object, that is, an original D as light / dark information of light is arranged above the photosensitive drum 10, that is, above the main body of the apparatus.

The image reading section 30 collects the original glass 31 for holding the original D, the illumination lamp 32 for illuminating the original D placed on the original glass 31, and the illumination light emitted from the illumination lamp 32 on the original D. A reflecting plate 33 and a first mirror 34 that bends the reflected light from the original D, a second mirror 35 and a third mirror 36 that sequentially bend the reflected light from the original D that is bent through the first mirror 34, and the like. And transmits the image of the document D placed on the document glass 31 to the CCD sensor 38 shown below as light / dark information of light. In a plane including the optical axis of the light turned back by the third mirror 36, an image forming lens 37 for giving a converging property to the reflected light from the document D, and the reflected light condensed by the image forming lens 37 are photoelectrically converted. CCD sensor 3 that outputs an electric signal (an image of document D is converted) to an image memory (not shown)
8 are arranged.

The laser exposure device 40 imparts a focusing property to a laser beam generated from a semiconductor laser element (not shown) and converts it into a laser beam having a generally circular cross-sectional shape by a first lens (not shown) and a first lens (not shown). An optical deflecting device 42 for deflecting the laser beam converted into a laser beam having a cross-sectional shape in the axial direction of the photosensitive drum 10, and the laser beam deflected by the optical deflecting device 42 is sequentially connected to the exposure position c of the photosensitive drum 10. The angle at which the laser beam is deflected and the photoconductor drum 10 for imaging.
An imaging lens 44 that matches the distance between the optical axis above and the position where the laser beam is to be imaged, and guides the laser beam that has passed through the imaging lens 44 to the exposure position c of the photosensitive drum 10. The first to third mirrors 46a, 46b and 46c, the optical deflector 42, the imaging lens 44, and the first to third mirrors 46a, 46b and 46.
It has a dustproof glass 48 for dustproofing c.

On the right side of the photosensitive drum 10, the first and second detachable first and second slots 50a and 50b for supplying recording paper toward the photosensitive drum 10 are inserted. Two paper cassettes 52a
And 52b are arranged.

Paper feed rollers 54a and 54b, which are arranged between the photosensitive drum 10 and the paper cassettes 52a and 52b, corresponding to the respective cassettes, and draw the paper one by one from the cassettes 52a and 52b, and the paper feed rollers. It is possible to temporarily stop the conveyance rollers 56a and 56b for feeding the papers drawn out via 54a and 54b toward the photoconductor drum 10, and the papers from the conveyance rollers 56a and 56b toward the photoconductor drum 10, respectively. Therefore, the inclination of the paper with respect to the direction in which the paper is conveyed is corrected, and the movement speed at which the surface of the photoconductor drum 10 is moved by aligning the front end of the toner image on the photoconductor drum 10 with the front end of the paper. An aligning roller 58 that delivers the paper at the same speed is arranged.

In the vicinity of the aligning roller 58, in order to stop the sheet through the aligning roller 58,
An aligning switch 58a for detecting the leading edge of the sheet being conveyed is provided.

A toner image formed on the photosensitive drum 10 is transferred to a position corresponding to the downstream side in the rotation direction of the photosensitive drum 10, and the sheet is conveyed to convey the sheet with the toner electrostatically attached. The belt 60, the fixing device 62 that heats the toner transferred onto the paper and presses it onto the paper, and the paper ejection roller that ejects the paper on which the toner image is fixed to the paper ejection tray outside the copying apparatus 2. 64
Is arranged.

The fixing device 62 is provided near the paper discharge roller 64.
A paper discharge switch 64a for detecting whether or not a sheet exists between the paper discharge roller 64 and the paper discharge roller 64 is provided. Is completed.

Next, the printing operation of the laser exposure type copying machine according to the embodiment of the present invention will be described in detail. The photoconductor drum 10 has a motor control circuit 110 by the CPU 100.
Corresponding to the motor drive clock supplied to the motor control circuit 110, the motor 120 is rotated at a predetermined speed via the motor 120 driven by the motor drive pulse from the motor control circuit 110. At the same time, the surface of the photoconductor drum 10 is uniformly charged to the surface potential of a predetermined size by the supply of electric charge by the charging device 12.

In detail, the corona wire 1 of the charging device 12
The radiation amount of corona discharge from 2a to the photosensitive drum 10 is appropriately adjusted by the grid bias voltage applied to the grid screen 12b. For example, the grid bias voltage applied from the grid voltage generation circuit 104 to the grid screen 12b is approximately -650V, and the high voltage from the high voltage generation circuit 102 causes the corona wire 12 to rotate.
The initial surface potential supplied to the photosensitive drum 10 via a is set to about -600V.

Subsequently, by the laser exposure device 40,
A laser whose intensity is modulated on the surface of the photosensitive drum 10 according to an image to be copied or printed out, that is, image information corresponding to an image of the document D or a print signal corresponding to an image signal supplied from a host device (not shown). The beam is irradiated.

When a laser beam is emitted from the laser exposure device 40, a print signal is printed on the outer peripheral surface of the photosensitive drum 10.
An electrostatic latent image corresponding to (image data) is formed. The electrostatic latent image thus formed is developed by the developing bias generating circuit 106, for example, by the toner T supplied from the developing roller 14a of the developing device 14 to which the developing bias voltage of −400V is applied, Transfer device 16 to which predetermined transfer voltage and separation voltage are applied by high voltage generation circuit 102 and separation voltage generation circuit 108
And is transferred as a toner image onto the paper via the.

The toner image transferred onto the sheet is separated from the surface of the photoconductor drum 10 together with the sheet, and then conveyed to the fixing device 62 by the conveying belt 60, and the fixing device 62.
It is fixed on the paper through.

The sheet on which the toner image has been fixed is sequentially discharged via the sheet discharge roller 64 and stacked on a sheet discharge tray 66 arranged outside the apparatus 2 to be stacked. After the toner image has been transferred to the sheet, the photosensitive drum 10 continues to rotate, and after the residual toner is removed via the cleaning device 18, the charge is removed by the charge removing device 19, and subsequently used for the next image formation. You.

In this way, a series of image formation is repeated. Here, the toner recycling mechanism as the embodiment of the present invention will be described in detail.

The untransferred toner, that is, the recovered toner scraped off the surface of the photosensitive drum 10 via the blade 18a of the cleaning device 18, is the front direction of the cleaning device 18 by the rotation of the auger 18b (the device cross section shown in FIG. 1). , The front surface side in the direction orthogonal to the paper surface).

The moved collected toner is directly conveyed by the auger 20a of the toner recycling mechanism 20 to the toner storage portion of the developing device 14 or the toner hopper integrally arranged in the developing device 14.

By the way, as described above, in the collected toner (waste toner) returned from the cleaning device 18 to the developing device 14 via the toner recycling mechanism, the auger 18b (cleaning device 18) for conveying the toner and the A toner agglomerate in which the toner is aggregated into particles by externally applying a stress to the toner due to rubbing by the auger 20a (toner recycling mechanism 20) and the housing or radiant heat emitted from the fixing device 62. (Nucleus) and its coarse particles are generated.
The particle size of the coarse particles of the toner aggregate reaches several times to several tens of times the average particle size of the toner.
It may be several 100 μm or more.

The factors affecting the image by the toner aggregates and their coarse particles generated by toner recycling will be traced below based on the process shown in FIG. First, toner aggregates (cores) are generated in the collected toner returned from the cleaning device 18 to the developing device 14 due to the above-mentioned factors.

The generated toner aggregate (nucleus) is returned to the developing device 14 (or the toner hopper integrated with the developing device) by the toner recycling mechanism 20 and mixed with the toner (A).

The toner aggregates returned to the developing device 14 via the toner recycling mechanism 20 are again supplied to the electrostatic latent image on the photosensitive drum 10 via the developing roller 14a of the developing device 14. . Thereby, the photosensitive drum 10
A toner aggregate is supplied together with the toner to the toner image formed on the surface of the toner (B).

Subsequently, the transfer device 16 and the photosensitive drum 10
The toner image containing the toner agglomerates of the photoconductor drum 10 that has been conveyed to the transfer area close to the toner image on the surface of the sheet is transferred to the transfer material, that is, the sheet by the transfer device 16 (C).
.

However, when the toner image is transferred to the paper by the transfer device 16, the toner agglomerates are transferred to the paper by the mirror image force of the surface potential of the photosensitive drum 10 and the potential held by the toner agglomerates. Without the photoconductor drum 10
Remains on the surface of (D).

As a result, white spots in the image corresponding to the toner aggregates occur in the image transferred onto the sheet (E). On the other hand, the toner aggregate remaining on the photosensitive drum 10 without being transferred in the transfer step is exposed by the cleaning blade 18a of the cleaning device 18 together with the untransferred toner left untransferred to the sheet in the transfer step by the transfer device 16. It is scraped off the surface of the body drum 10 and collected by the cleaning device 18 (F).

The toner agglomerates generated by the above-mentioned factors are repeatedly moved between the photoconductor drum 10 and the developing device 14 by repeating the processes (A) to (D) and (F). To be done.

As a result, the toner agglomerates serve as nuclei to gradually increase the particle size, that is, the coarse particles of the toner agglomerates and the toner agglomerates newly generated as the number of times of image formation increases. The frequency of occurrence of white spots and the size of white spots per location are increased. It is noted that the amount of toner recycled by the cleaning device 18 and the toner recycling mechanism 20 is rapidly increased in proportion to the number of times of image formation. Therefore, when the number of times of image formation exceeds the predetermined number, the frequency of occurrence of white spots and the size of white spots per location are outside the allowable range.

FIGS. 4 (a) to 4 (d) respectively show the image density of an image obtained by repeating the printing operation by the image forming apparatus shown in FIG. 1, the background fog of the sheet on which the toner image is transferred, 6 is a graph showing fogging due to untransferred toner on the photoconductor drum 10 and the number of white spots seen in an image transferred onto a sheet, that is, the frequency of occurrence of white spots. In image formation, the longitudinal direction of an A4 size sheet is conveyed so as to be perpendicular to the direction in which the sheet is conveyed.

As shown in FIG. 4 (d), when the printing operation, that is, the image formation is repeated, the frequency of white spots becomes high after 10,000 sheets, and when the number of sheets exceeds 20,000, the white spots suddenly go back and forth. It has been confirmed that the allowable limit is exceeded and the allowable limit is exceeded.

From this, as already described with reference to FIG. 3, coarse particles of the toner aggregate whose particle size gradually increases as the number of times of image formation increases, and image formation is repeated by repeating image formation. It is recognized that the occurrence of white spots and the size of white spots per location are increased due to the toner aggregates generated.

As shown in FIGS. 4 (a) to 4 (c), the image density governed by the characteristics of the toner and the photosensitive member of the photosensitive drum, the background fog of paper and the fog on the drum are as follows. Both are within the allowable range.

Next, a method for suppressing the generation of coarse particles of toner aggregates or toner aggregates (nuclei), and removal of coarse particles of toner aggregates from the toner returned to the developing device 14 via the recycling mechanism 20. The method for doing so will be described.

As described above, the factors that cause toner aggregates due to toner recycling are the auger of the cleaning device 18 and the toner recycling mechanism 20, or the stress applied to the toner by the friction between the housing and the toner and the fixing device 62. Heat (radiant heat) and the like radiated inside the device 1 are known. As described above, the toner agglomerates are repeatedly moved between the photoconductor drum 10 and the developing device 14, so that the toner agglomerates are gradually increased in particle size with the toner agglomerates generated earlier as cores. Of coarse particles.

Therefore, the auger 18b of the cleaning device 18 and the auger 2 of the toner recycling mechanism 20 are provided.
An apparatus and a mechanism in which coarse particles of toner aggregates are less likely to be generated by changing the shape or material of 0a were examined, but no apparatus or mechanism capable of obtaining a significant improvement effect was found. Further, as factors that cause coarse particles of the toner aggregates, the cleaning device 18 and the toner recycling mechanism 20, which are represented by the composition of the toner itself, the melting point of the toner that affects the fixing rate, the environmental conditions in which the copying apparatus 1 is installed, and the like. Since there are other elements, it is substantially difficult to suppress the generation of coarse particles in the toner aggregate.

Next, the toner agglomerates returned to the developing device 14 and the coarse particles of the toner agglomerates are transferred to the photosensitive drum 10.
The toner aggregate capturing mechanism that prevents the electrostatic latent image from being used in the development will be described.

FIG. 5 shows an example of a toner agglomerate trapping mechanism arranged in the toner collecting portion in the developing device 14, that is, in a portion where the toner conveyed through the auger 20a of the toner recycling mechanism 20 is dropped into the developing device 14. FIG.

As shown in FIG. 5, the toner agglomerate capturing mechanism 14z is separated by this mesh from a mesh having a mesh size of, for example, about 100 μm, which is arranged at the collected toner dropping position of the developing device 14. In order to accommodate the coarse particles of the toner agglomerate, the toner agglomerate holding portion (not shown) formed in the housing 14b of the developing device 14 is used.

According to the toner agglomerate capturing mechanism shown in FIG. 5, the toner agglomerates and coarse particles are separated by the mesh and then accumulated in the toner agglomerate holding portion. As a result, the number of image formations is 20,000 when there are white spots in a solid image.
It has been confirmed that it rarely occurs up to (times) times.

However, the number of image formations is 30,000.
Toner recycling mechanism 20
The auger 20a is damaged, and the collected toner drops from the cleaning device 18. This means that the coarse particles of the toner agglomerates are clogged in the mesh of the toner agglomerate capturing mechanism, and as a result, the auger 20a is overloaded, the auger 20a is damaged, and the toner from the cleaning device 18a is damaged. It can be considered that a fall has occurred.

From this, for example, by vibrating the mesh of the toner agglomerate capturing mechanism, clogging can be prevented, but the structure becomes very complicated and the cost of the apparatus increases. Although various studies have been conducted on a method of capturing toner aggregates instead of the toner aggregate capturing mechanism shown in FIG. 5, a capture method that is simple in structure and does not increase the cost has not yet been found.

Next, a method of electrostatically separating the toner aggregates and the coarse particles thereof returned to the developing device 14 will be described. Toner recycling mechanism 20 auger 20a
The toner agglomerates and their coarse particles collected in the developing device 14 via the toner are caused by the rotation of the toner supply roller 14c and the developing roller 14a rotated by the developing motor 122 and the movement of the toner and the toner agglomerates in the housing 14b. At the position where the developing roller 14a and the toner supply roller 14c are in contact with each other, the toner is concentrated on the upstream side in the rotation direction of the toner supply roller 14c (point 14t in FIG. 1).

As a result, the toner aggregates guided to the outer peripheral surface of the developing roller 14a are collected and conveyed in a portion relatively close to the surface of the toner layer formed on the developing roller 14a.

The coarse particles of the toner agglomerates and the toner agglomerates are subjected to a centrifugal force due to the rotation of the developing roller 14a. Therefore, the coarser particles of the toner agglomerates having a larger particle size are closer to the surface of the toner layer of the developing roller 14a. Moved and separated. The coarse particles of the toner aggregate and the toner aggregate separated into the toner layer on the developing roller 14a are usually the sleeve of the developing roller 14a due to the developing bias voltage applied to the toner in the developing roller 14a and the housing 14b. Since it is electrostatically adsorbed on
The electrostatic latent image on the photosensitive drum 10 is remarkably attracted to a solid image having a large latent image potential.

This means that the coarse particles of the toner agglomerates and the toner agglomerates gathered on the surface of the toner layer on the developing roller 14a will be transferred to the developing roller 14a by the surface potential of the photosensitive drum 10 and the developing bias voltage. It shows that it can be recovered from.

Hereinafter, the surface potential Vsp supplied to the photosensitive drum 10 and the magnitude of the developing bias voltage Vbd applied to the developing roller 14a are changed, and the developing roller 14 is changed.
The behavior of the coarse particles of the toner aggregate and the toner aggregate aggregated in the toner layer on the surface of a will be described.

The surface potential Vsp of the photosensitive drum 10 is -6.
00V, developing bias Vbd applied to developing roller 14a
When the paper is supplied in the same manner as in a normal image forming step, most of the coarse particles of the toner agglomerates and the toner agglomerates adhere to the photoconductor drum 10 together with the background fog toner, and are transferred to the cleaning device 18. Be recovered. That is, it is recognized that the coarse particles of the toner agglomerates and the toner agglomerates can be attracted from the surface of the toner layer of the developing roller 14a to the photosensitive drum 10, but cannot be separated from the collected toner.

Whether the coarse particles of the toner aggregates and the toner aggregates contained in the toner layer on the surface of the developing roller 14a can be separated by increasing the time for rotating the developing roller 14a and the photosensitive drum 10 is determined. In order to investigate the above, the state in which the coarse particles of the toner aggregate and the toner aggregate are separated by the rotation in the initial operation immediately after the power of the device 1 is turned on is observed. The aggregate could be attracted to the photosensitive drum 10 from the surface of the toner layer of the developing roller 14a, but could not be separated from the recovered toner.

From this fact, in order to separate the coarse particles of the toner agglomerates and the toner agglomerates separated from the surface of the developing roller 14a without adhering to the photoconductor drum 10, the surface potential Vsp of the photoconductor drum 10 is set to 0V. It is recognized that it is good to set to. Incidentally, in practice, the photosensitive drum 1
Only by setting the surface potential Vsp of 0 to 0 V, the amounts of coarse particles and toner aggregates of the toner aggregates separated from the developing roller 14a are reduced. Therefore, the normal image formation is performed on the developing roller 14a. It was confirmed that by applying a voltage V ^- bd having a polarity opposite to that of the developing bias voltage Vbd used, it is possible to reliably separate coarse particles of toner aggregates and toner aggregates from the toner layer of the developing roller 14a. .

As described above, the surface potential Vsp of the photosensitive drum 10 is set to 0 V, and the voltage V ^-- bd having the opposite polarity to the developing bias voltage Vbd applied to the developing roller 14a is applied to the photosensitive drum 10 and the developing roller. 14a
The developing roller 1 is rotated by rotating in a predetermined direction.
The coarse particles of the toner aggregate and the toner aggregate separated from the surface of 4a by the centrifugal force do not adhere to the photoconductor drum 10 and are fixed at a predetermined position of the developing device 14, for example, the developing roller 14a. It is dropped into the housing 14b located below. The developing roller 14a
The magnitude of the reverse polarity voltage V ^- bd applied to the image forming apparatus (reverse development type) shown in FIG. 1 is preferably +3.
00V to + 50V, more preferably + 150V
Is set to

Next, the timing for executing the process for separating and recovering the coarse particles of the toner agglomerate and the toner agglomerate (hereinafter referred to as the agglomerate recovery process) and the operating time of the agglomerate recovery process will be described. . In addition,
In this aggregate collection process, main controller 100 is activated when a predetermined timing stored in advance in a non-volatile memory (not shown) has passed in a continuous image forming process.
Shall be repeated under the control of. Further, for the counting of the predetermined timing, the motor drive pulse is supplied from the main controller 100 to the output of the counter device 112 for counting the number of times of image formation shown in FIG. 2 or the motor drive circuit 110 shown in FIG. Controlled time by the main controller 10
It is assumed that the count result of the clock counter externally attached to 0 (or built in the main controller 100) is used.

FIG. 6 shows a case where the above-mentioned aggregate collecting process is repeated for 1 minute every time the number of times of image formation by the image forming apparatus 1 shown in FIG. 1 exceeds 10,000 (times) to continue the image formation. 3 is a graph showing the number of white spots included in the toner image transferred onto the paper. The image forming conditions are the same as those shown in FIG. 4, and the number of white spots that occur when a halftone image is copied is visually counted.

As shown in FIG. 6, the number of times of image formation is 4
The number of white spots contained in the toner image transferred to the sheet is suppressed to be within the allowable range (10) by repeating the aggregate collection process for 1 minute until the number of sheets reaches (10,000 times).

However, the number of image formations is 50,000
The number of white spots contained in the toner image transferred to the paper should exceed the permissible range (10) even if the aggregate collection process is executed before and after reaching the number of times. Is recognized. This is, as I already explained,
It can be inferred that the number of generated coarse particles in the toner aggregate rapidly increases due to the increase in the amount of collected toner due to the increase in the number of times of image formation.

From this, the number of image formations is 10,000
Each time the number of times exceeds the number of times, the above-described aggregate collection process is repeated for 1 minute to increase the time for repeating the aggregate collection process using the developing device 14 that has formed 60,000 (times) images. When it was observed whether or not the number of white spots contained in the toner image transferred to the toner could be reduced below the allowable range, 2 minutes was insufficient, but the number of white spots within 3 minutes was below the allowable range. It was recognized that Images are repeatedly formed under the same image forming conditions as shown in FIG. 6, and every time the number of image formations exceeds 10,000 (times), the aggregates are collected until the number of white spots falls below the allowable range. The time when the process was executed was calculated as follows: 10,000 sheets (times) for 1 minute, 20,000 sheets (times) for 1 minute, 30,000 sheets (times) for 1 minute, 40,000 sheets ( 2 times for 50,000 sheets, 2 minutes for 50,000 sheets, and 3 minutes for 60,000 sheets.

From this fact, depending on the number of times of image formation, for example, 10,000 sheets (times) for 1 minute, 20,000 sheets (times) for 1 minute, 30,000 sheets (times) for 2 minutes, 4 minutes For every 10,000 sheets (times), for 2 minutes, for 50,000 sheets (times), for 3 minutes, for 60,000 sheets (times), for 3 minutes However, it can be suppressed within the allowable range.

In the actual image forming process, there are various paper sizes (in the case of A3 paper, the image forming process is twice as large as the conveying condition of A4 paper shown in FIG. 4). From the motor drive circuit 11 shown in FIG.
By counting the time when the motor drive pulse is supplied to 0 from the main controller 100, the time when the image forming process is repeated can be more accurately counted. That is, by considering the time when the main motor 120 and the developing motor 122 are rotated as the number of times of image formation and correcting the actual number of times of image formation regardless of the size of the paper, the toner aggregates and the coarse particles thereof are removed. Undesirable increase can be prevented.

7 (a) to 7 (d), the agglomerate collection process described above is executed every 10,000 sheets (times), and the printing operation is repeated in the image forming apparatus shown in FIG. 7 is a graph showing the image density of the image obtained, the background fog of the paper, the fog caused by the untransferred toner on the photoconductor drum 10, and the frequency of occurrence of white spots in the image transferred to the paper. In image formation, the longitudinal direction of an A4 size sheet is conveyed so that it is perpendicular to the direction in which the sheet is conveyed.

As shown in FIGS. 7 (a) to 7 (c), the image density, the background fog on the sheet, and the fog on the drum are all within the allowable range. Also, FIG. 7 (d)
As shown in, although the frequency of white spots increases around the time when the number of image formations reaches 10,000 (times), the white spot occurrence frequency reaches the allowable limit due to the above-described aggregate collection process. It is prevented from crossing. As described above, in the image forming test shown in FIGS. 7 (a) to 7 (d), in the actual image forming process, there are various paper sizes (in the case of A3 paper, FIG. 2 times the image forming process compared to the A4 sheet conveyance condition shown in FIG. 2). Therefore, the motor drive circuit 110 shown in FIG.
The time when the motor drive pulse is supplied from the main controller 100 is counted, and the number of times of image formation is used as the A4 sheet transport condition and reference shown in FIG.

By the way, according to the agglomerate collecting process described above, the coarse particles and the toner agglomerates of the toner agglomerates guided to the outer peripheral surface of the toner layer of the developing roller 14a and attracted toward the photoconductor drum 10 are Photoconductor drum 1
It is separated without being electrostatically attracted to 0 and dropped to the lower part of the housing 14b of the developing device 14.

However, the total number of coarse particles and toner aggregates of the toner aggregates that can be held by the housing 14b necessarily has a limit, so that the coarse particles and toner aggregates of the separated toner aggregates are generated. It is necessary to prevent the paper or the paper from falling into the paper transport path.

FIGS. 8 and 9 are schematic views showing a toner aggregate capturing mechanism for capturing coarse particles of the toner aggregate and the toner aggregate collected by the aggregate collecting process. The toner aggregate capturing mechanism shown in FIG.
In a portion of the housing 14b corresponding to the lower portion of the developing roller 14a, a partition portion 114 having an elastic body 114a such as rubber is arranged. The partition 114 may be integrally formed with the housing 14b. Further, instead of the elastic body 114a, for example, a semi-solid resin having an adhesive property or a resin material such as vinyl chloride having a self-fusing property with respect to the composition of the toner may be used.

In the partition section 114 shown in FIG.
Since the total amount of coarse particles of toner agglomerates and toner agglomerates that can be held is relatively small, for example, when a toner replenishment mechanism is not provided and toner stored in advance is completely consumed It is preferably applied to an image forming apparatus in which a process unit including the apparatus is exchanged.

As shown in FIG. 9, the toner agglomerate capturing mechanism 214 is arranged between the photosensitive drum 10 and the developing roller 14a, and coarse particles and toner agglomerates of the toner agglomerates separated from the developing roller 14a. The seal member 214a has a recess 214b formed integrally with the housing 14b of the developing device 14. It goes without saying that the depth and shape of the recess 214b are arbitrarily defined according to the amount of coarse particles of toner aggregates and the amount of toner aggregates generated and the maximum allowable value for image formation in which continuous image formation is repeatable. Nor.

Next, the timing at which the aggregate collection process is executed and the length of execution of the aggregate collection process per time
Explain (time). According to the agglomerate collection process described above, the coarse particles of the toner agglomerates and the toner agglomerates contained in the recovered toner (waste toner) returned to the developing device via the recycle mechanism have an image forming count of 10,000 sheets.
It is collected every time (more than) times.

However, the normal image forming operation is interrupted while the aggregate collecting process is executed. In this case, if the number of image formations is 60,000 times,
The aggregate recovery process can take up to 3 minutes. This will require an undesired waiting time from the user if the aggregate collection process is carried out while continuous imaging is being performed.

From this, even when it is detected that the cumulative number of image formation times has reached the number of times the aggregate collection process should be executed, the current input sequence of image formation is completed. Between the main control unit 10 shown in FIG.
A value of 0 prevents the aggregate collection process from running.

For example, when the number of times of image formation reaches 50,000 times and 60,000 times, the subsequent image forming operation is interrupted for 3 minutes by the above-mentioned aggregate collecting process. If the time to execute is longer than 1 minute, for example, 25,000 times, 30,000 times,
Aggregate collection described above at 35,000, 40,000, 45,000, 48,000, 50,000, 55,000, 58,000 and 60,000 times, respectively The process for 1 minute each
It is preferable to execute in a divided manner. In addition, about 5 to 15 seconds at 45,000 times and 55,000 times, about 15 to 30 seconds at 48,000 times and 58,000 times, respectively, the time to execute the aggregate collection process. By increasing, the frequency of occurrence of white spots due to the coarse particles of the toner aggregates and the toner aggregates can be surely suppressed within the allowable range. Furthermore, the aggregate collection process is performed when a power switch (not shown) of the image forming apparatus 1 is turned on.
It may be executed for 1 minute when the device 1 is reset by removing a jammed paper due to a paper jam or supplying toner.

In the embodiment of the present invention,
The case where a negative charging characteristic is used for the photosensitive drum 10 is shown, but an organic photosensitive member having a positive charging characteristic (positive charging type OP
The same applies to C).

Further, in the above-described embodiment, the reversal development system for attenuating the surface potential of the portion corresponding to the image information has been described as an example. However, in the regular development system for attenuating the surface potential of the portion other than the image information. Can also be applied. In this case, the magnitude and polarity of the developing bias voltage may be changed according to the surface potential of the photoconductor and the polarity of the toner supplied by the developing device.

[0090]

As described above in detail, according to the image forming apparatus of the present invention, the toner aggregates and the coarse particles contained in the toner recycled by the toner recycling mechanism are used for the normal image formation on the developing roller. By applying a voltage having a polarity opposite to that of the developing bias voltage used, the developing roller is reliably separated. Further, the toner aggregates and the coarse particles thereof, which are acceleratedly increased with the increase in the number of times of image formation, are removed from the developing roller by increasing the time during which the voltage having the polarity opposite to the developing bias voltage is applied to the developing device. It Therefore, it is possible to prevent white spots that occur when the toner is recycled by the toner recycling mechanism to repeatedly develop the electrostatic latent image.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an image forming apparatus including a developing device to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing an outline of a photosensitive drum of the image forming apparatus shown in FIG. 1, peripheral portions of a developing device, and a control mechanism.

FIG. 3 is a schematic diagram illustrating a cause of white spots in a toner image transferred onto a sheet.

FIG. 4 shows the number of times an image is formed using a conventional developing device, the image density of the image, the background fog of the paper on which the toner image is transferred, the fog of untransferred toner on the photosensitive drum, and , A graph showing the frequency of occurrence of white spots in an image transferred to a sheet.

FIG. 5 is a schematic view showing an example of a separation mechanism that separates recycled toner and toner aggregates.

FIG. 6 shows a state of occurrence of white spots when an aggregate collection process for collecting coarse particles of toner aggregates and toner aggregates according to an embodiment of the present invention is repeated for 1 minute per 10,000 image formation times. The graph that shows.

FIG. 7 shows the number of image formations and the image density of an image when the aggregate collection process for collecting coarse particles of toner aggregates and toner aggregates according to the embodiment of the present invention is repeated according to the number of image formations. 6 is a graph showing the background fogging of the paper on which the toner image is transferred, the fog due to untransferred toner on the photoconductor drum, and the frequency of occurrence of white spots in the image transferred to the paper.

8 is a schematic diagram showing an example of a toner aggregate capturing mechanism arranged in the developing device of the image forming apparatus shown in FIG.

9 is a schematic view showing an example of a toner aggregate capturing mechanism arranged in the developing device of the image forming apparatus shown in FIG.

[Explanation of symbols]

2 ... Copying device (image forming device), 10 ... Photosensitive drum
(Image bearing member), 12 ... Charging device, 12a ... Corona wire, 12b ... Grid screen, 14 ... Developing device (developing means), 14a ... Developing roller, 14b ... Housing,
14c ... Toner supply roller, 16 ... Transfer device, 17 ... Peeling device, 18 ... Cleaning device, 18a ... Cleaning blade, 18b ... Auger, 19 ... Eliminating device, 20 ...
Toner recycling device, 20a ... Auger, 30 ... Original reading section, 31 ... Original glass, 32 ... Exposure lamp, 33 ... Reflector, 34 ... First mirror, 35 ... Second mirror, 36 ... Third mirror, 37 ... Connection Image lens, 38 ... CCD sensor, 4
0 ... Laser exposure device, 42 ... Optical deflection device, 44 ... Imaging lens, 46a, 46b, 46c ... Mirror, 48 ... Dust-proof glass, 50a, 50b ... Slot, 52a, 52b ... Paper cassette, 54a, 54b ... Paper feed Rollers, 56a, 5
6b ... conveying roller, 58 ... aligning roller, 58a
... Aligning sensor, 60 ... Conveying belt, 62 ... Fixing device, 64 ... Paper ejection roller, 64a ... Paper ejection sensor, 100
... main control device, 102 ... high voltage generation circuit, 104 ... grid voltage generation circuit, 106 ... development bias voltage generation circuit, 108 ... separation voltage generation circuit, 110 ... motor drive circuit, 112 ... counter device, 120 ... main motor, 122
… Development motor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 15/08 507 G03G 15/08 507E 21/10 21/00 326

Claims (7)

[Claims] 1. An image carrying area moving means for moving an image carrying area of an image carrying body at a predetermined speed, and a developing method in which an electrostatic latent image formed on the image carrying area of the image carrying body is charged to a predetermined polarity. Developing means for supplying the developer to an area to be attached by a developing bias voltage; transfer means for transferring the developer supplied to the image carrier by the developing means to a transfer material; and image carrying by the developing means. Development in which the developer supplied to the electrostatic latent image in the image carrying area of the body is recovered from the image carrying area of the image carrying body by the transfer means, and the untransferred developer remaining without being transferred to the transfer material is transferred. An agent collecting means, a recycling mechanism for returning the developer collected by the developer collecting means to the developing means, a voltage applying means for applying a reverse voltage having a polarity different from the developing bias voltage to the developing means, and an image Image of carrier Counting means for lifting area counts the cumulative amount of movement that has been moved, and a voltage application unit controlling means for biasing said voltage applying means on the basis of the cumulative amount of movement that has been counted by the counting means, the image forming apparatus having a. 2. A photosensitive member having a photosensitive area for holding a potential difference between a light-irradiating portion and a non-light-irradiating portion as an electrostatic latent image by irradiating light with a predetermined electric potential being charged, It includes a motor that moves the photosensitive area of the photoconductor at a predetermined speed and a toner transport mechanism that transports toner as a developer. The toner transport mechanism is moved at a predetermined speed to form on the photosensitive area of the photoconductor. A developing device for supplying the toner charged to a predetermined potential and polarity to the formed electrostatic latent image by a developing bias voltage to develop the toner, and the toner supplied to the photoconductor by the developing device. A transfer device for transferring the developing bias voltage to the developing device and the toner contained in the developing device; and a toner transport mechanism of the developing device. The toner feeding mechanism driving device for moving the toner by a certain degree, and the toner supplied to the photosensitive area of the photoconductor through the developing device is adhered to the electrostatic latent image and then is not transferred to the paper by the transfer by the transfer device. Cleaning device for recovering the untransferred toner remaining in the toner and the fog toner adhering to areas other than the photosensitive area where the electrostatic latent image is formed, and a toner recycling device for returning the toner recovered by the cleaning device to the developing device. A voltage applying means for applying to the developing device a reverse voltage having a polarity different from that of the developing bias voltage supplied via the developing bias power source; and a cumulative movement in which a photosensitive area of the photosensitive member is moved. A counter device that counts the amount, and energizes the voltage applying means based on the accumulated movement amount counted by the counter device to cause the developing device to operate. With applying different reverse voltages polarities with respect to the image bias voltage, an image forming apparatus and a control means for operating said motor and said toner conveying mechanism drive unit for a predetermined time. 3. A photoconductor having a photosensitive region for holding a potential difference between a light-irradiating portion and a non-light-irradiating portion as an electrostatic latent image by irradiating light with a predetermined electric potential being charged, It includes a motor that moves the photosensitive area of the photoconductor at a predetermined speed and a toner transport mechanism that transports toner as a developer. The toner transport mechanism is moved at a predetermined speed to form on the photosensitive area of the photoconductor. A developing device for supplying the toner charged to a predetermined potential and polarity to the formed electrostatic latent image by a developing bias voltage to develop the toner, and the toner supplied to the photoconductor by the developing device. A transfer device for transferring the developing bias voltage to the developing device and the toner contained in the developing device; and a toner transport mechanism of the developing device. The toner feeding mechanism driving device for moving the toner by a certain degree and the toner supplied to the photosensitive area of the photoconductor via the developing device are not transferred to the paper by the transfer by the transfer device after being adhered to the electrostatic latent image. Cleaning device for recovering the untransferred toner remaining in the toner and the fog toner adhering to areas other than the photosensitive area where the electrostatic latent image is formed, and a toner recycling device for returning the toner recovered by the cleaning device to the developing device. A voltage applying means for applying to the developing device a reverse voltage having a polarity different from that of the developing bias voltage supplied via the developing bias power source; and a cumulative movement in which a photosensitive area of the photosensitive member is moved. A counter device that counts the amount, and energizes the voltage applying means based on the accumulated movement amount counted by the counter device to cause the developing device to operate. Control means for applying reverse voltages having different polarities with respect to the image bias voltage and for operating the motor and the toner transport mechanism driving device for a long time gradually as the cumulative movement amount counted by the counter device increases. An image forming apparatus having. 4. A photosensitive member having a photosensitive area for holding a potential difference between a light-irradiating portion and a non-light-irradiating portion as an electrostatic latent image by irradiating light with a predetermined electric potential being charged, It includes a motor that moves the photosensitive area of the photoconductor at a predetermined speed and a toner transport mechanism that transports toner as a developer. The toner transport mechanism is moved at a predetermined speed to form on the photosensitive area of the photoconductor. A developing device for supplying the toner charged to a predetermined potential and polarity to the formed electrostatic latent image by a developing bias voltage to develop the toner, and the toner supplied to the photoconductor by the developing device. A transfer device for transferring the developing bias voltage to the developing device and the toner contained in the developing device; and a toner transport mechanism of the developing device. The toner feeding mechanism driving device for moving the toner by a certain degree, and the toner supplied to the photosensitive area of the photoconductor through the developing device is adhered to the electrostatic latent image and then is not transferred to the paper by the transfer by the transfer device. Cleaning device for recovering the untransferred toner remaining in the toner and the fog toner adhering to areas other than the photosensitive area where the electrostatic latent image is formed, and the toner recycling device for returning the toner recovered by the cleaning device to the developing device. A voltage applying means for applying to the developing device a reverse voltage having a polarity different from that of the developing bias voltage supplied via the developing bias power source; and a cumulative movement in which a photosensitive area of the photosensitive member is moved. A counter device that counts the amount, and energizes the voltage applying means based on the accumulated movement amount counted by the counter device to cause the developing device to operate. A reverse voltage having a polarity different from that of the image bias voltage is applied, and the motor and the toner conveying mechanism driving device are gradually divided into a long time and a predetermined time as the cumulative movement amount counted by the counter device is increased. An image forming apparatus having: 5. The image forming apparatus according to claim 2, 3 or 4, wherein the image forming apparatus has a trapping mechanism for trapping aggregated particles of toner separated from the developing unit and coarse particles which are aggregates thereof. The image forming apparatus according to any one of the above. 6. The image forming apparatus according to claim 5, wherein the capture mechanism is provided integrally with the developing device. 7. An image carrying area moving means for moving an image carrying area of an image carrying body at a predetermined speed, and a developing device charged to a predetermined polarity on an electrostatic latent image formed on the image carrying area of the image carrying body. Developing means for supplying the developer to an area to be attached by a developing bias voltage; transfer means for transferring the developer supplied to the image carrier by the developing means to a transfer material; and image carrying by the developing means. Development in which the developer supplied to the electrostatic latent image in the image carrying area of the body is recovered from the image carrying area of the image carrying body by the transfer means, and the untransferred developer remaining without being transferred to the transfer material is transferred. An agent collecting means, a recycling mechanism for returning the developer collected by the developer collecting means to the developing means, a voltage applying means for applying a reverse voltage having a polarity different from the developing bias voltage to the developing means, and an image Image of carrier A counting means for counting the cumulative movement amount of the holding area, a voltage applying means control means for activating the voltage applying means based on the cumulative movement amount counted by the counting means, and a voltage applying control means of the voltage applying control means. An image forming apparatus comprising: an agglomerate of developer separated from the developing means and a trapping means for trapping coarse particles as an aggregate thereof by energizing the voltage applying means by control.