JP2739985B2 - Image forming device - Google Patents

Description

Description: Object of the Invention (Industrial Application Field) The present invention relates to an image forming apparatus such as an electrophotographic laser printer and a copying machine, and more particularly, to a toner remaining on an image carrier after transfer. The present invention relates to an improvement in a cleaning means for cleaning a cleaning device.

(Prior Art) An image forming apparatus such as an electrophotographic laser printer includes a developing device that supplies toner to an electrostatic latent image formed on a cylindrical photoreceptor serving as an image carrier and visualizes the electrostatic latent image. And a transfer device for transferring an image formed on the photosensitive member with toner onto paper. Most of the toner on the photoconductor is transferred onto the paper by this transfer device, but a part of the toner remains on the photoconductor.

As shown in FIG. 11, there are various remaining states of the toner on the photosensitive member after the transfer. In the figure, A shows a case where normal transfer was performed. B is close to normal transfer but slightly excessive transfer, and the toner is positively charged to the opposite polarity by the transfer charger. This is likely to occur when solid black or the like is transferred. C is a case where the sheet remains in a lump due to insufficient transfer, and is likely to occur when the sheet floats from the transfer body during transfer due to carrier adhesion or paper wrinkling.
Further, the transfer residual toner in the unexposed portion is the surface potential Vo of the photoconductor.
Is lower than the developing bias Vb applied to the developing device, and is electrostatically attracted to the developing device. On the other hand, since the surface potential of the photoreceptor of the transfer residual toner in the exposed portion is increased by the exposure, the negatively charged toner does not return to the developing device but remains on the photoreceptor.

Of the transfer residual toner remaining on the photoconductor as described above, when the toner is uniformly scattered on the photoconductor as in the case of A and B, the light amount of the laser in the exposure process is sufficiently large,
Since the exposure area is sufficiently large relative to the size of the toner, even if toner adheres to the photoreceptor, it does not become a shadow of exposure, and the negative potential on the surface of the photoreceptor is attenuated to form a latent image. You. In addition, since the unexposed portion is reliably cleaned by the developing device as described above, no problem occurs in forming a latent image. However, when the toner remains in a lump as in the case of C, it is difficult to completely clean the toner by the developing device, and a positive memory is formed on a white background. If this portion corresponds to the next exposed portion, the light does not pass because the toner layer is thick and the diameter of the mass is large, and a negative memory is generated on a black background.

In order to remove the transfer residual toner as described above, a cleaner is conventionally provided between the transfer device on the outer periphery of the photoconductor and the pre-exposure device. Conventionally, this cleaner includes a blade that abuts on the surface of the photoreceptor to scrape off toner, and a collection box that collects the scraped toner.

(Problems to be Solved by the Invention) However, the conventional cleaner as described above has a structure in which the toner remaining on the photoreceptor is scraped into a collection box by a blade.
When copying about 1 to 3,000 sheets, the toner in the collection box becomes full and becomes unusable. For this reason, a complicated collecting mechanism and a collecting box must be provided, and the collecting box must be replaced each time to collect the toner, so that the structure is complicated and the user's hands and clothes become dirty and workability deteriorates. There was a problem. Also, depending on the type of equipment, the cleaner has to be discarded each time. Further, since the toner on the photoconductor is scraped off by the blade, the surface of the photoconductor may be damaged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a simple structure that eliminates the influence of residual toner on a photoconductor at the time of exposure, stabilizes image quality, prolongs the life of a photoconductor, and It is an object of the present invention to provide an image forming apparatus capable of improving performance.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, a first aspect of the present invention provides a charging device for charging a rotatable photoconductor to a predetermined potential, and a photoconductor charged by the charging device. Exposure means for forming an electrostatic latent image by irradiating light, and developing and supplying a developer to the electrostatic latent image formed on the photoreceptor by the exposure means, and developing an unexposed portion with residual Developing means for removing the developer, transfer means for electrostatically transferring the developer image formed by the developing means from the photoreceptor to a transfer material, provided downstream of the transfer means in the photoreceptor rotation direction. A sponge-like member for smoothing the residual developer, and a brush member provided downstream of the sponge-like member in the rotation direction of the photoconductor and upstream of the charging means, for disturbing the residual developer. It is characterized by the following.

According to a second aspect of the present invention, there is provided a charging unit for charging a rotatable photoconductor to a predetermined potential, and an exposure for forming an electrostatic latent image by irradiating the photoconductor charged by the charging unit with light. Means for developing the electrostatic latent image formed on the photoreceptor by the exposure means by supplying a developer, and removing residual developer in an unexposed portion; A transfer unit for electrostatically transferring the developed developer image from the photoconductor to the transfer material, and a first member provided downstream of the transfer unit in the photoconductor rotation direction to smooth the residual developer. A second member provided downstream of the first member in the rotation direction of the photoconductor and upstream of the charging means, for disturbing the residual developer, and wherein the first member and the second member are disturbed. And a member made of a different material.

(Function) According to the first and second inventions, after the transfer, the toner as the bulk developer remaining on the image carrier is smoothed by a sponge-like member (first member). The toner can be disturbed by the brush member (second member) and dispersed on the image carrier, and the occurrence of memory due to residual toner during exposure can be prevented. Therefore, a toner collection box is not required, and a small cartridge can be obtained by integrally attaching a cleaning unit including a sponge-like member (first member) and a brush member (second member) to a developing device as a developing unit. be able to. Further, by forming the sponge-like member (first member) and the brush member (second member) with soft members, the surface of the image carrier is not damaged and the life can be extended.

Further, the second invention is a first invention for smoothing a massive toner.
Since different members are used for the member and the second member that disturbs the smoothed mass toner, the dispersion is achieved by using a material that is suitable for the smoothing means and another material that is suitable for the disturbing means. Is further promoted.

Hereinafter, an embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings.

1 to 4 show one embodiment of the present invention. In FIGS. 1 and 2, one mag roller 131 and two stirring rollers are provided in a casing 133 of a developing device 104 as a developing means. 132a and 132b are provided in parallel with each other in the axial direction, and are rotationally driven in directions of arrows a, b and c by a driving source (not shown). The casing 133 is filled with a toner 134 as a developer. A drum-shaped photoconductor 101 is provided on the casing 133 in parallel with the rollers 131 and 132, and is driven to rotate in the direction of arrow R by a driving source (not shown). Further, a cleaning means 109 is provided on the casing 133 in parallel with the photoreceptor 101. As shown in FIG. 3, the cleaning means 109 has a sponge-like member formed of a conductive maltoprene or the like in a block shape.
135a (first member of the second invention), the electric resistance 10 ⁵ to 1
A brush 135b as a brush member formed of a conductive rayon of about ⁶ ohm cm (the second member of the second invention)
Are mounted in parallel on the upstream side and the downstream side, respectively. That is, the first member and the second member are made of different materials. The lower ends of the sponge-like member 135a and the brush 135b as a brush member are in contact with the outer periphery of the photoreceptor 101 in the width direction along the generatrix direction, and the width is wider than the maximum paper width and image area to be used. . Further, a positive voltage of about 300v to 400v is applied to the brush 135b.

Reference numeral 141 shown in FIG.
Reference numeral 142 denotes an incident position of light incident on the photoconductor 101, reference numeral 142 denotes an incident position of a laser beam incident on the photoconductor 101 from the electrostatic latent image forming unit 103 as an exposure unit, and reference numeral 136 shown in FIG. It is a handle provided in.

Next, a case where one embodiment of the present invention is applied to a laser printer will be described with reference to FIG.

FIG. 4 shows a schematic configuration of an electrophotographic monochromatic laser printer.

The laser printer is electrically connected to a computer or a host system (external device) such as a word processor via a transmission device (not shown).
By writing dot image data from an external device and modulating the laser beam light to write on the photosensitive member, the written dot image data is developed and transferred onto paper.

That is, 100 is an apparatus main body, and a drum-shaped photoconductor 101 is provided in the main body 100.
It is rotated in the direction of arrow R by a drive source (not shown).

A developing unit provided with a charging member 102 for charging as a charging unit of a charge control type, an electrostatic latent image forming unit 103 as an exposure unit, and the cleaning unit 109 around the photoreceptor 101 along the rotation direction. A developing device 104, a transfer charger 105 as a transfer unit, and a pre-exposure device 112 are sequentially arranged, and the photosensitive member 101 is integrally formed with the developing device 104.

A paper cassette 106 is provided in the main body 100, and a sheet as a transfer medium as a recording medium taken out from the paper cassette 106 by a paper feed roller 107 is transferred to a photoconductor 101.
The sheet is fed between the image transfer unit 105 and the transfer charger 105, passes through an image transfer unit 108 and a fixing unit 118, is guided to a sheet discharge roller 113, and is discharged to a sheet discharge unit 114.

An electrostatic latent image forming unit 103 as exposure means includes a semiconductor laser oscillator (not shown) that generates a laser beam light modulated in accordance with dot image data from an external device (not shown), and a laser diode (not shown). A lens system (not shown) such as a collimator lens for condensing the output laser beam light, for example, a four-sided rotating mirror (polygon mirror) 116 for scanning the laser beam light condensed by this lens system, A mirror motor 117 for rotating the mirror 116 at high speed, a lens 121 for correctly guiding the laser beam light scanned by the rotating mirror to the photoconductor, and reflection mirrors 119 and 1 for reflecting the laser beam light toward the photoconductor 101
20, a light beam detector (not shown) for detecting the laser beam light scanned by the rotating mirror 116, and the like.

In such a configuration, upon receiving a print start signal from an external device, the photoconductor 101 rotates, and the photoconductor 101 is uniformly charged by a charging charger 102 as a charging unit so as to have a surface potential of, for example, about 600 V. Is done.

Next, when receiving the dot image data from the external device, the electrostatic latent image forming unit 103 as an exposure unit outputs a laser beam light modulated according to the dot image data, and is charged by the laser beam light. Photoreceptor
By scanning and exposing the surface of the photoconductor 101, an electrostatic latent image is formed on the surface of the photoconductor 101.The electrostatic latent image formed on the photoconductor 101 is a developing device having a mag roller 131, stirring rollers 132a and 132b. The image is visualized by the reversal development by 104 and becomes a toner image as a developer. Then, the toner image on the photoconductor 101 is transferred to a paper feed cassette 106 in an image transfer unit 108.
Is transferred onto the paper conveyed from the printer.

The sheet on which the toner image has been transferred is conveyed to a fixing device 118, where the toner image is fixed, and then discharged to a paper discharge unit 114 by a paper discharge roller 113. After the toner image is transferred from the photoconductor 101 to the paper (not shown) by the transfer charger 105, the toner remaining on the photoconductor 101 is cleaned by a cleaning unit 109 by an operation described later, and then the red LED is used.
By the light emitted from the light source of the pre-exposure device 112, the surface of the photoconductor 101 is uniformly discharged.

Next, the operation of the cleaning means 109 will be described with reference to FIGS.

5 to 7 show the case of insufficient transfer toner, and FIGS. 8 to 10 show the case of excess transfer toner. When there is a toner mass 150 on the surface of the photoconductor 101 moving in the arrow X direction, as shown in FIG.
As it passes below 135a, the toner mass 150 is smoothed. Subsequently, when passing under the brush 135b, the smoothed toner mass 150 is disturbed by the brush 135b, dispersed and adheres to the surface of the photoconductor 101. At this time, the toner mass 150 having a negative charge of insufficient transfer is attracted to the brush 135b as shown in FIG. 6 because a positive voltage is applied to the brush 135b. When the photoconductor 101 further moves in the direction of arrow X, the toner mass 150 once sucked by the brush 135b becomes
Since the brush 135b has no toner holding ability, it naturally comes out behind the brush 135b as shown in FIG. That is,
The brush 135b sucks the insufficient transfer toner mass 150 by electrostatic force, but since the amount of toner that can be attached to the brush 135b is small,
Further, since the brush 135b is in contact with the photoconductor 101 in the width direction, the toner 150 once sucked is gradually
Adheres to other parts of the surface.

On the other hand, in the case of excessive transfer toner, as shown in FIG. 8, the toner 151 is uniformly scattered on the photoreceptor 101 and the polarity is inverted, and the toner 151 becomes positive with the same polarity as the sponge-like member 135a and the brush 135b. ing. Accordingly, the photosensitive member 101 advances in the direction of the arrow X, and as shown in FIG.
Even if it passes below 135b, it is adsorbed on the photoreceptor 101 without suction and proceeds. That is, as shown in FIG. 10, the toner 151 passes under the sponge-like member 135a and the brush 135b and is on the photosensitive member 101 at the same position as before the passage. At this time, since the sponge-like member 135a and the brush 135b are formed of a soft member and are in contact with the photoreceptor 101 in the withdrawal direction, that is, in a state of contact with the abdomen, and the contact pressure is extremely weak, the toner 151 is moved. There is no. Therefore, the toner 151 is scattered uniformly as in the initial state.

According to the present embodiment, the transfer residual toner 15 on the photoconductor 101
Each of the reference numerals 151 and 151 is uniformly scattered after passing under the cleaning means 109, so that the occurrence of memory due to residual toner at the time of exposure can be prevented. Therefore, a conventional toner collection box is not required, and the photosensitive member 101,
The developing device 104 and the cleaning means 109 can be integrated into a cartridge, and the device can be reduced in size and weight. Further, since the sponge-like member 135a and the brush 135b are formed of a soft member and are in contact with the photoconductor 101 in the width direction, the life of the photoconductor 101 can be prolonged and the image quality can be improved.

In the above-described embodiment, the case where the number of the sponge-like member 135a and the number of the brush 135b is one has been described. However, the number is not limited to one.

〔The invention's effect〕

As described above, in the first invention and the second invention, the toner as the bulk developer remaining on the image carrier after the transfer is smoothed by the sponge-like member (first member). It is possible to disperse the toner on the image carrier by being disturbed by the brush member (second member), thereby preventing the occurrence of memory due to residual toner during exposure. Therefore, a toner collection box is not required, and a small cartridge can be obtained by integrally attaching a cleaning unit including a sponge-like member (first member) and a brush member (second member) to a developing device as a developing unit. be able to. Further, by forming the sponge-like member (first member) and the brush member (second member) with soft members, the surface of the image carrier is not damaged and the life can be extended.

Further, the second invention is a first invention for smoothing a massive toner.
Since different members are used for the member and the second member that disturbs the smoothed mass toner, the dispersion is achieved by using a material that is suitable for the smoothing means and another material that is suitable for the disturbing means. Is further promoted.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view of FIG. 1, and FIG.
FIG. 4 is an exploded perspective view showing the cleaning means, FIG. 4 is a longitudinal sectional view showing a laser printer to which the cleaning means according to the present embodiment is applied, and FIGS. 5 to 10 are explanations for explaining the operation of the present embodiment. FIG. 11 is an explanatory view showing the toner remaining on the image carrier. R: photoconductor rotation direction, 101: photoconductor (image carrier), 102: charging means (charging electricity), 103: exposure means (latent image forming unit), 104: developing means (development) ), 105: transfer means (transfer charger), 134: developer (toner), 135a: sponge-like member, first member, 135b ... brush member, second member, 150, 151 ... Residual developer (residual toner).

Continued on the front page (72) Inventor Kenichi Ohno 70, Yanagicho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Yanagicho Plant Co., Ltd. (72) Inventor Yoshihiko Sugiyama 70, Yanagicho, Yuki-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Intelligent Technology Co., Ltd. (56) References JP-A-63-241587 (JP, A) JP-A-64-50090 (JP, A) JP-A-60-230171 (JP, A) JP-A-61-15169 (JP, A)

Claims (2)

(57) [Claims] A charging means for charging a rotatable photosensitive member to a predetermined potential; an exposure means for forming an electrostatic latent image by irradiating the photosensitive member charged by the charging means with light; Developing means for supplying a developer to develop the electrostatic latent image formed on the photoreceptor by the exposure means and removing residual developer in an unexposed portion; and developing the electrostatic latent image formed by the developing means. Transfer means for electrostatically transferring the agent image from the photoreceptor to a transfer material, provided downstream of the transfer means in the photoconductor rotation direction,
A sponge-like member for smoothing residual developer, and a brush member provided downstream of the sponge-like member in the rotation direction of the photoconductor and upstream of the charging means, for disturbing the residual developer. Characteristic image forming apparatus. 2. A charging means for charging a rotatable photoconductor to a predetermined potential; an exposure means for irradiating the photoconductor charged by the charging means with light to form an electrostatic latent image; Developing means for supplying a developer to develop the electrostatic latent image formed on the photoreceptor by the exposure means and removing residual developer in an unexposed portion; and developing the electrostatic latent image formed by the developing means. Transfer means for electrostatically transferring the agent image from the photoreceptor to a transfer material, provided downstream of the transfer means in the photoconductor rotation direction,
A first member for smoothing the residual developer, and a second member provided downstream of the first member in the rotation direction of the photoconductor and upstream of the charging means, for disturbing the residual developer.
An image forming apparatus comprising: the first member and the second member made of different materials.