JP3375207B2 - Electrophotographic equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus. 2. Description of the Related Art Some electrophotographic apparatuses used for facsimile machines and printers generally have the following construction. That is, a charging device for charging the surface of the photoreceptor around the endless photoreceptor, and an electrostatic latent image is formed on the surface of the photoreceptor at a position downstream of the photoreceptor in the rotation direction of the charging device. An exposure device, and a developing device that applies toner carried on a developing roller positioned downstream of the photoconductor in the rotation direction of the photoconductor to the surface of the photoconductor so that an electrostatic latent image is made visible to form a toner image A transfer device that is located downstream of the photoconductor with respect to the developing device in the rotation direction of the photoconductor and transfers the toner image of the photoconductor to recording paper that is a recording medium; And a cleaning device for removing the toner remaining on the surface of the photoconductor after transfer by bringing the blade into contact with the surface of the photoconductor. In an electrophotographic apparatus having this configuration, a photoconductor is rotated during image formation, the photoconductor is charged by a charging device in accordance with the rotation, an electrostatic latent image is formed by an exposure device, and then a developing device is used. A toner image is formed.
Next, the toner image on the photoconductor is transferred onto the recording paper by the transfer device, and the toner remaining on the photoconductor is removed by the cleaning device. The toner removed by the cleaning device is collected and discarded as waste toner. However, such an electrophotographic apparatus is large in size due to the provision of the cleaning device, and is uneconomical in that the cleaning device discards the collected toner. There is a problem that the maintenance management is complicated. [0005] To solve this problem, in recent years,
An electrophotographic apparatus disclosed in JP-A-59-133573 has been proposed. The electrophotographic apparatus has a function of simultaneously performing both operations of a developing process and a cleaning process. As shown in FIG.
A two-component reversal developing type developing device 2 including a hopper 3 containing toner T and two developing rollers 4 and 5 is provided. In the developing device 2, the toner T is
Is moved to the photosensitive member 1 for development, and the toner remaining on the surface of the photosensitive member 1 is sucked by the developing roller 5 to perform cleaning. Residual toner is in developing device 2
And used again for development. This electrophotographic apparatus is economical because the cleaning apparatus is omitted, the apparatus is reduced in size, and there is no need to discard the residual toner. However, this electrophotographic apparatus employs a two-component reversal developing method, and has a problem that the developing apparatus itself is large and it is difficult to reduce the size and cost. To solve this problem, an electrophotographic apparatus disclosed in Japanese Patent Application Laid-Open No. 62-203182 has been proposed. This electrophotographic apparatus employs a non-contact one-component reversal development system and performs both operations of a developing process and a cleaning process simultaneously. As shown in FIG. A developing device 12 employing a reversal developing method is provided. The developing device 12 has a hopper 13 in which a non-magnetic one-component toner T is stored and a developing roller 14 provided separately from the photoconductor 11. ing. In the developing device 12, the toner is
Is moved to the photoreceptor 11 for development, and
The toner remaining on the surface of the photoconductor 11 is sucked from the photoconductor 11 to the developing roller 14 to perform cleaning. This electrophotographic apparatus can reduce the size of the developing device 12 by employing a non-contact one-component reversal developing system. However, in this electrophotographic apparatus, since the photoconductor 11 and the developing roller 15 are separated from each other without contact, the toner remaining on the photoconductor 11 is
However, there is a problem that the collection efficiency is low. In order to solve this problem, an electrophotographic apparatus disclosed in Japanese Patent Application Laid-Open No. 3-4276 has been proposed. This electrophotographic apparatus employs a contact type one-component reversal developing system and performs both operations of a developing process and a cleaning process at the same time. As shown in FIG.
Developing device 2 employing contact one-component reversal developing method around
The developing device 22 includes a hopper 23 in which the one-component toner T is stored and a developing roller 24 that comes into contact with the photoconductor 21. In this developing device 22,
The toner moves from the developing roller 24 to the photoconductor 21 to perform development, and the toner remaining on the surface of the photoconductor 21 is sucked by the developing roller 24 to perform cleaning. The electrophotographic apparatus further includes a transfer roller as a transfer device, which comes into contact with the photosensitive member 21 and presses the recording paper P from the back side to contact the photosensitive member,
A contact-type transfer device 25 that transfers the toner image formed on the photoconductor 21 to the recording paper P is provided. In this electrophotographic apparatus, since the photosensitive member 21 and the developing roller 24 are in contact with each other, the efficiency with which the developing device 22 collects the toner remaining on the photosensitive member 11 is improved. However, in the electrophotographic apparatus of this system, when the negatively charged toner is used for the negatively charged photoconductor, when the photoconductor 21 contacts the recording paper P in the transfer device 25, the recording paper P The paper dust generated from the toner adheres to the photoconductor 21 together with the residual toner after the transfer process. Here, the talc contained in the component of the paper powder is easily charged negatively, that is, the partner material is easily charged positively. When this talc adheres to the photoreceptor and is carried to the developing device, and is collected in the hopper together with the residual toner by the developing device 22, the negative toner stored in the hopper is charged to the positive polarity. When development is performed using the positive polarity toner, there is a problem in that the toner adheres to the non-image area, that is, a so-called “fogging” stain is generated, thereby deteriorating the image quality of the image. In the case where the developing device frictionally charges the toner carried on the developing roller by the blade, paper dust is clogged between the developing roller and the blade, causing streaks in the image and causing image quality. May be reduced. In particular, in a system in which the transfer device brings the transfer roller into contact with the photosensitive member, the toner image on the photosensitive member is transferred onto the recording medium while moving the recording roller, which is a recording medium, between them. The amount of paper dust adhered to the photoreceptor is large, and the above-described problem of image deterioration is remarkable. As described above, in the electrophotographic layer of the system employing a combination of the one-component contact reversal development system, the residual toner recovery system using the developing device, and the contact transfer system, the recording is performed. There is a problem in that the image quality is degraded due to the generation of stains called "fog" due to the influence of paper dust. The present invention has been made on the basis of the above-mentioned circumstances, and in the one employing a combination of a one-component contact reversal development system, a residual toner recovery system using a developing device, and a contact transfer system, the influence of paper dust on the recording paper. An object of the present invention is to provide an electrophotographic apparatus in which image deterioration is prevented. According to the first aspect of the present invention, there is provided an electrophotographic apparatus, comprising: a photosensitive member which is formed of a positively charged photoconductive member, is endless and is rotated during image formation; A charging device that charges the surface of the body to a positive polarity, an exposure device that is positioned downstream of the charging device in the rotation direction of the photoconductor and forms an electrostatic latent image on the surface of the photoconductor, and the exposure device A developing roller, which is located on the downstream side in the rotation direction of the photoconductor and carries a toner having the same polarity as the charging potential, is brought into contact with the surface of the photoconductor so that the toner adheres to the photoconductor; A developing device that visualizes the image to form a toner image, and a voltage is applied to the developing device on the downstream side in the rotation direction of the photoconductor to apply a voltage to contact the photoconductor and press the recording paper from the back side. Transfer roller to be brought into contact with the photoconductor A transfer device for transferring a toner image formed on the photoconductor to recording paper, wherein the developing roller of the developing device removes the toner remaining on the surface of the photoconductor after passing through the transfer device. In the electrophotographic apparatus to be collected in the developing device, the brush surface is made of a material in which carbon is dispersed in rayon and has brush bristles planted at a density capable of removing paper powder, and the brush surface is on the surface of the photoreceptor. A brush in which the brush surface moves with the movement of the surface of the photoconductor in contact is provided between the transfer device and the charging device,
The brush bristles of the brush have characteristics ranging from conductive to medium resistance, and are characterized in that a voltage is applied. With the above arrangement, the brush surface of the brush provided between the transfer device and the charging device is brought into contact with the surface of the photosensitive member,
By moving the brush surface along with the movement of the surface of the photoconductor at the time of photo recording, paper dust of the recording paper adhered to the surface of the photoconductor after the transfer step is removed from the photoconductor. Then, the brush is formed of a material having a characteristic ranging from conductive to medium resistance, and by applying a voltage, the paper powder of the photoconductor can be more firmly removed. A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of the electrophotographic apparatus. In the drawing, reference numeral 31 denotes an endless, for example, drum-shaped, photoconductor, which is formed of a positively charged photoconductive member, for example, aluminum. The photoconductor 31 is rotatably supported by a member (not shown) and is rotated by a rotation driving mechanism (not shown). Around the photoconductor 31, a charging device 32, an exposure device 33, a developing device 34, and a transfer device 3
5 are arranged, and these devices 32 to 34 are supported by members (not shown). The charging device 32 charges the surface (outer peripheral surface) of the photoreceptor 31 to a positive polarity, and comprises a scorotron charger to which a voltage is applied from a DC power supply E1. The exposure device 33 forms an electrostatic latent image on the surface of the photoconductor 31, and is configured by, for example, a light emitting diode (LED) exposure device, and is located downstream of the charging device 32 in the rotation direction of the photoconductor 3. I have. The developing device 34 forms a toner image by making the electrostatic latent image on the surface of the photoreceptor 31 visible by employing a one-component contact reversal developing method. 31 is located on the downstream side in the rotation direction. The developing device 34 includes a toner hopper 36 containing a one-component toner T, a developing roller 37 disposed parallel to the photoconductor 31 and rotatably provided, and a surface of which is in contact with the surface of the photoconductor 31. A rotatable toner supply roller 38 disposed parallel to the developing roller 37; and a developing roller 3 provided stationary at a fixed position parallel to the developing roller 37.
And a blade 39 that comes into contact with the surface of the blade 7. The developing roller 37 and the supply roller 38 are rotated in a direction indicated by an arrow by a rotation driving device (not shown), and a voltage is applied by a DC power supply E2. The developing device 34 also has a function of performing a cleaning operation for collecting the toner T remaining on the surface of the photoreceptor 31 after fixing. The transfer device 35 has a transfer roller 40 that is located on the downstream side in the rotation direction of the photoconductor 31 and is in contact with the surface of the photoconductor 31. This transfer roller 4
Numeral 0 is rotated in a direction indicated by an arrow by a rotation driving device (not shown), and a voltage is applied by a DC power supply E3. A rotary brush 41 for removing paper dust adhering to the photoconductor 31 is provided between the transfer device 35 and the charging device 32 near the photoconductor 31. Is formed by arranging a large number of brush bristles 43 radially on a shaft 42 having the same length as the photoreceptor 31, for example, over the entire circumference thereof. This brush bristles 4
3 is preferably planted so as to be in contact with the entire surface of the photoconductor 31 in the axial direction, but may be partially planted with a predetermined width in the axial direction. The brush hairs 43 do not remove the toner T adhering to the surface of the photoreceptor 31,
It is made of a material that can remove paper dust satisfactorily. For example, it is formed by dispersing carbon in rayon. Brush hair 43
The density at which the paper is planted also takes into account that the paper dust can be removed well. The rotating brush 41 is disposed in parallel with the photosensitive member 31, and a shaft 42 is rotatably supported by a member (not shown). The tip of the brush bristles 43 is in contact with the surface of the photosensitive member 31.
The rotating brush 41 moves along with the movement of the surface of the photoconductor when the brush surface contacts the surface of the photoconductor.
The basic function is to remove the paper dust attached to the surface of No. 1. For this reason, the rotating brush 41 may be rotated following the rotation of the photoconductor 31. Further, the rotating brush 41 may be rotated in a forward or reverse direction with respect to the rotating direction of the photoconductor 31 by a rotation driving device (not shown). In this case, the shaft 42 is driven by the rotary drive.
To rotate. When the rotating brush 41 is rotated in the forward direction with respect to the rotating direction of the photosensitive member 31, the peripheral speed of both the rotating brush 41 and the photosensitive member 31 may be the same, and the peripheral speed between the rotating brush 41 and the photosensitive member 31 may be the same. A difference may be provided. In order to provide a peripheral speed difference between the two, the rotation speed of the rotating brush 41 is appropriately set.
Even when the rotating brush 41 is rotated in the opposite direction with respect to the photoconductor 31, the rotating speed of the rotating brush 41 is appropriately set.
A practical effect is obtained when the rotating brush 41 is rotated by the rotation driving device in a direction opposite to the rotation direction of the photoconductor 31, or is rotated with a peripheral speed difference in the forward direction. A case 44 receives the paper dust removed by the rotating brush 41. The operation of the thus configured electrophotographic apparatus will be described. The photoreceptor 31 is rotated in the direction of the arrow by the rotation drive mechanism. The operation described below is performed by the rotation of the photosensitive drum 31. First, the surface of the photoreceptor 31 has a predetermined positive potential, for example, 500 V to 800 V, by corona discharge of the device charger 32 composed of scorotron charging.
It is charged to a potential of about V. Next, an electrostatic image corresponding to the image information is formed on the surface of the photoconductor 31 by the exposure device 33. The exposure device 33 performs exposure by blinking an LED according to image information. The form of the latent image by this exposure is a negative latent image from which electric charges in the image portion have been removed. Next, a toner image corresponding to the electrostatic image is formed on the surface of the photoconductor 31 by the developing device 34. That is, the one-component toner T stored in the hopper 36 is supplied to the developing roller 37 by the rotating supply roller 38. The toner T is conveyed toward the photoconductor 31 by the rotating developing roller 37, contacts the blade 39 on the way, is charged, and is formed in a thin layer. The positively charged toner T adheres to the portion of the surface of the photoreceptor 31 from which the charge of the electrostatic latent image has been removed by the Coulomb force by the developing roller 37 to form a toner image (reversal development). Further, in the developing device 34, the toner T remaining on the surface of the photoreceptor 31 after fixing is sucked and collected by the developing roller 37 to perform a cleaning action. Then
In the transfer device 35, a recording paper P (not shown) is conveyed while being sandwiched between the transfer roller 41 and the photoconductor 31 that are rotated by the application of a voltage from the DC power supply E <b> 3, and the toner image on the photoconductor 31 is transferred to the recording paper P. . In this transfer step, about 10 to 25% of the toner T adhering to the surface of the photoconductor 31 remains without being transferred to the recording paper P. At the same time, paper dust S generated from the recording paper P adheres to the surface of the photoconductor 31. In particular, since the recording paper P is pressed against the surface of the photoconductor 31 by the transfer roller 40, a large amount of paper dust S adheres to the photoconductor 31. As shown in FIG. 3A, the toner T and the paper dust S existing on the surface of the photoreceptor 31 are used.
Is moved to the rotating brush 41 by the rotation of the photoconductor 31. Next, the paper dust S on the photoreceptor 31 is removed by the rotating brush 41 forcibly rotated in the direction indicated by the arrow.
As shown in FIGS. 3B and 3C, in the rotary brush 41, the rotation of the shaft 42 causes the brush bristles 43 to rotate, and continuously comes into sliding contact with the surface of the photoconductor 31, and adheres to the surface of the photoconductor 31. The paper dust S is removed from the surface of the photoconductor 31 by peeling. In particular, talc contained in the paper dust S of the recording paper P is peeled off from the surface of the photoconductor 31 and removed. At this time, the toner T remaining and adhering to the surface of the photoreceptor 31 is only disturbed by the rotating brush 41, and does not adhere again after the disturbance and is removed. This is because the paper dust S only adheres to the photoreceptor 31 with a very weak electrostatic force, but the toner T
Is strongly adhered by Coulomb force. Also,
This is because paper powder S, especially talc, has good slip properties. After the paper dust S is removed by the rotating brush 41, only the residual toner T moves to the charging step. The residual toner T is further charged to the positive electrode by the charging device 32, and is attracted to the developing roller 37 of the developing device 34 by a mirror image force in a developing process. The paper dust S remains on the surface of the photoreceptor 31 without being removed by the rotating brush 41. Even if the paper dust S enters the inside of the hopper 36 from the developing roller 37 and mixes with the toner T, the paper dust S and the toner T In the triboelectric charging, the toner T is charged to a positive polarity from the charging series, and stable development characteristics can be maintained. As described above, according to the present invention, in an electrophotographic apparatus employing a combination of a one-component contact reversal developing method, a residual toner collecting method using a developing device, and a contact transfer method, a rotating brush adheres to the surface of a photoreceptor after a transfer step. The paper dust from the recording paper is removed from the photoreceptor, so that the so-called "fogging" that toner adheres to the non-image area does not occur, and the paper dust is clogged between the developing roller and the blade, causing streaks in the image. Therefore, it is possible to prevent the deterioration of the image due to the influence of the paper dust of the recording paper, and to stably secure a high-quality image for a long period of time. Next, a second embodiment will be described with reference to FIG. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, the brush bristles 43 of the rotating brush 41 are formed of a material having a characteristic ranging from conductive to medium resistance. For example, the brush bristles 43 are formed by dispersing carbon in rayon and have an electric resistance value of 10%.
Formed at about ⁶ Ω · cm. A voltage is applied to the brush bristles 43 from the DC power supply E4. For this reason, the rotating brush 41
Is formed of a conductive material and is electrically connected to the DC power source E3. In this manner, the brush bristles 43 exert an electric attraction force on the paper dust S adhering to the surface of the photoreceptor 31, thereby strongly removing the powder S from the surface of the photoreceptor 31. Can be improved. The talc of the paper powder S is more negatively charged than the charging series. By applying a positive voltage to the brush bristles 43, the removal effect is further improved. In this case, the brush bristles 43 and the photoconductor 31 need to be in contact with each other with a certain width. By applying the voltage of the rotating brush 41 as described above, the paper powder of the photoconductor can be more firmly removed. The present invention is not limited to the above-described embodiment, but can be implemented with various modifications. For example, the photoconductor is not limited to a drum. The recording medium is not limited to recording paper. Further, the brush is not limited to the rotating direction and may be, for example, a belt type. As described above, according to the electrophotographic apparatus of the first aspect , carbon is dispersed in rayon.
A brush having brush bristles planted at a density capable of removing paper dust is provided between the transfer device and the charging device, and the brush surface of the brush is brought into contact with the surface of the photoreceptor;
By moving the brush surface along with the movement of the surface of the photoreceptor at the time of photo recording, the paper dust of the recording paper adhered to the surface of the photoreceptor after the transfer process can be removed from the surface of the photoreceptor. In a device employing a combination of a developing method, a residual toner collecting method by a developing device, and a contact transfer method, it is possible to prevent image deterioration due to the influence of paper dust of a recording paper and to stably secure a good image over a long period of time. . Further, by forming the bristles of the brush with a property having a property from conductivity to medium resistance and applying a voltage, paper powder can be more strongly removed from the photoconductor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing an electrophotographic apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram illustrating an electrophotographic apparatus according to a second embodiment. FIG. 3 is an explanatory view showing the operation of a brush. FIG. 4 is a schematic configuration diagram showing a first conventional electrophotographic apparatus. FIG. 5 is a schematic configuration diagram showing a second conventional electrophotographic apparatus. FIG. 6 is a schematic configuration diagram illustrating a third conventional electrophotographic apparatus. [Description of Signs] 31 photoconductor, 32 charging device, 33 exposure device, 34 developing device, 35 transfer device,
36: Hopper, 37: Developing device, 41: Rotating brush

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/08-13/095 G03G 15/08-15/095 G03G 21/10

Claims (1)

(57) [Claim 1] An endless photosensitive member formed of a positively charged photoconductive member and rotated during image formation, and a charging device for charging the surface of the photosensitive member to a positive polarity An exposure device that is located downstream of the charging device in the rotation direction of the photoconductor and forms an electrostatic latent image on the surface of the photoconductor, and that is downstream of the rotation of the photoconductor with respect to the exposure device. A developing roller that carries a toner having the same polarity as the charged potential is brought into contact with the surface of the photoreceptor so that the toner adheres to the photoreceptor and the electrostatic latent image is made visible to form a toner image. And a transfer roller that is located downstream of the photoconductor in the rotation direction of the photoconductor with respect to the developing device, applies a voltage to contact the photoconductor, and presses the recording paper from the back side to contact the photoconductor. The toner image formed on the photoconductor is recorded on a recording paper. ; And a transfer device for transferring the said developing roller of the developing device, in electrophotographic apparatus for recovering the toner remaining on the surface of the photosensitive member in the developing apparatus after passing through the transfer device, rayon The brush surface is made of carbon dispersed and has brush bristles planted at a density capable of removing paper dust. The brush surface comes into contact with the surface of the photoconductor, and the brush surface moves with the surface of the photoconductor. An electrophotograph, wherein a brush is provided between the transfer device and the charging device, and the brush bristles of the brush have characteristics between conductivity and medium resistance, and a voltage is applied. apparatus.