JPH0738095B2 - Electrophotographic device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic apparatus, and more particularly, to improvement of charge removal of a photoconductor and separation apparatus of transfer paper.

(B) Conventional technology Conventionally, a toner image is formed on the surface of a photosensitive drum, and the toner image is transferred onto a copy sheet by discharge of a transfer corona discharger, and then guided to a fixing device to fix the toner image. Copiers have been widely used. In such a copying machine, the separation method of the copy paper from the photoconductor drum includes an electrostatic separation method using a corona discharger for separation and a separation method. A mechanical separation method using a belt and separation claws is adopted.

However, in a device that employs a mechanical separation method,
At the time of transfer, the photoconductor part up to the outside of the front and rear edges of the transfer paper is charged in consideration of the response of the corona discharger, but the charged part is not discharged immediately after charging, and the toner adhered to the surface of the blade Toner or the like floating near the photosensitive drum is adsorbed to the charged portion of the photosensitive drum, which prevents normal formation of a new latent image on the photosensitive drum.

Therefore, in order to remove such unnecessary charges, it is proposed that the photosensitive drum is destaticized after the transfer paper is separated, and the destaticizing device is arranged at a position where it does not hinder the transfer paper transfer ( See, for example, JP-A-55-156978).

(C) Problems to be solved by the invention By the way, the static eliminator needs to be cleaned because it is contaminated by the toner floating in the vicinity of the photoconductor drum. However, the static eliminator arranged as described above needs to be cleaned at the time of cleaning. There is a problem that not only a mounting and demounting mechanism for mounting and demounting the static eliminator itself is required, but also a power supply connection mechanism to the static eliminator becomes complicated accordingly.

Furthermore, in the mechanical separation method described above, one end in the width direction of the transfer paper is forcibly separated, but the other part is separated from the photosensitive drum and the transfer paper by the force transmitted from the one end to the transfer paper itself. Since separation is performed against the electrostatic attraction between the transfer paper and the transfer paper having a weak stiffness or a wide transfer paper, the separability and the transportability are deteriorated.

In consideration of such circumstances, the present invention has been made by thoroughly examining the arrangement of the static eliminator, and it is not necessary to attach / detach the static eliminator at the time of cleaning, and the separability of transfer paper after transfer is good. The present invention provides an electrophotographic apparatus excellent in transportability.

(D) Means for Solving Problems The present invention is to transfer a toner image formed on a photoconductor to a transfer paper surface by a transfer device to separate the transfer paper from the photoconductor, and to transfer the photoconductor surface after the transfer. In an electrophotographic apparatus configured to remove the residual toner, the charge removal lamp is disposed adjacent to the transfer paper carry-out side of the transfer device and at a position where the transfer paper immediately after the transfer is irradiated from the back surface, and a photoreceptor surface. The transfer sheet separated from the transfer device in the conveying direction, and a transparent plate that covers the static elimination lamp, and a control device that activates the transfer device and turns on the static elimination lamp. A transfer period including a predetermined time before the leading edge of the transfer paper reaches the transfer device and a predetermined time after the rear end of the transfer paper passes through the transfer device, and the transfer device is operated at least during that period. Tomo Further, the present invention provides an electrophotographic apparatus, which is characterized in that a static elimination lamp is turned on so that at least the back surface of the transfer paper and the photosensitive member portion charged by the transfer device are irradiated through the transparent guide plate.

As the static elimination lamp, a neon lamp, a cold cathode tube, a fluorescent lamp or the like is used.

(E) Action When the transfer paper is fed corresponding to the developed image on the photoconductor, the transfer device starts to operate and the discharge lamp is turned on before the transfer paper reaches the transfer device. At the same time when the tip of the transfer paper reaches the transfer device, the transfer of the photoconductor image to the transfer paper is started,
When the transfer paper is transferred from the front end to the rear end, the charge is sequentially irradiated from the back surface of the transfer paper by a discharging lamp to remove a part of the residual charge on the transfer paper, and the electrostatic attraction force between the transfer paper and the photoconductor is increased. Will be reduced. At the same time, the transfer paper is separated from the photoconductor and conveyed. Even when the rear end of the transfer paper passes through the transfer device and the transfer is completed, the transfer device and the discharge lamp continue to operate.

Therefore, the transfer paper is completely transferred from the front end to the rear end, and the charged portion and the transfer paper formed on the photoconductor before and after the transfer paper arrives are discharged by the discharging lamp.

(F) Embodiment Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. The present invention is not limited to this.

FIG. 1 is an explanatory view of the structure of a copying machine to which an embodiment of the present invention is applied, wherein 1 is a photosensitive drum which rotates in the direction of arrow A during copying, 2 is a developing roller, and 3 is a transfer sheet feeding timing. A registration roller that rotates together to feed the transfer paper to the photosensitive drum 1, 4 is a corona discharger for transfer, 4a is its case,
4b is a discharge wire electrode, 5 is a transparent guide plate made of polycarbonate that is installed extending from the case 4a of the corona discharger 4 and supports the transfer paper from the back side and guides it in the transport direction. 6 is covered by the transparent guide plate 5. A charge removing lamp, 7 is a separation belt that separates one end of the transfer paper in the width direction from the photosensitive drum 1, and 8 is a separation belt that sandwiches the end of the transfer paper separated by the separation belt 7 from the photosensitive drum 1. Separation roller for separating, 9 for guiding transfer paper, 10 for guiding transfer paper, 11 for feeding roller, 12 for fixing roller, 13 for removing residual toner on surface of photosensitive drum 1 after transfer Blade, 14
Is a collection roller for collecting the removed toner in the tank 14a, 15 is a discharge lamp for uniformly discharging the surface of the photosensitive drum 1, 16 is a corona discharger for uniformly charging the surface of the photosensitive drum 1, and L Is the image light obtained by exposing the original.

FIG. 2 is a block diagram showing the main part of the control circuit of FIG. 1. Reference numeral 17 is a drive signal for the registration roller 3 output from the copying machine at the time of copying, and 18 is set by the registration roller drive signal 17 to keep time. A timer that starts and outputs and is reset by measuring the period until the rear end of the transfer sheet completely passes through the transparent guide plate 5, 19a is activated by the registration roller drive signal 17 and stopped by the output of the timer 18. The driver 19b of the corona discharger 4 is operated by the copy command 20, and the static elimination lamp 6 is continuously operated during the copying period.
Is the driver of.

In such a configuration, the photoconductor drum 1, the developing roller 2, the separation roller 8, the feeding roller 11, the fixing roller 12 and the collecting roller 14 are driven by the copy command 20, and the charge eliminating lamps 6 and 15 are turned on and the corona discharger is turned on. 16 is driven to start the copying operation. Then, an electrostatic latent image is formed on the surface of the photosensitive drum 1 by the image light (L) from the document, and the electrostatic latent image is developed by the developing roller 2. The registration roller 3 is driven and a transfer sheet (not shown) is fed at a preset time so that the developed image and the transfer sheet are exactly aligned on the photosensitive drum 1. The driver 19 is driven by the drive signal 17 of the registration roller 3 and the corona discharger 4 is driven. Therefore, at this point, a high voltage for transfer is applied to the surface of the photoconductor drum 1 by the corona discharger 4, and the charge formed on the surface of the photoconductor drum 1 by the corona discharger 4 is transferred from the static elimination lamp 6 to the transparent guide plate The light is radiated onto the photoconductor drum 1 via to remove the charge sequentially. In such a state, the transfer paper is placed in the corona discharger 4
When it reaches the upper part of the sheet, the end portion is separated from the photosensitive drum 1 by the separation belt 7 and the other portion is fed while being in contact with the photosensitive drum 1, and the image on the photosensitive drum 1 is transferred from the tip of the transfer paper. At the same time, the transferred transfer paper is guided by the transparent guide plate 5 while being illuminated by the static elimination lamp 6 from the back surface, and is sandwiched between the separation rollers 8.
It is separated from the photosensitive drum 1 and fed to the guide plate 10. Further, the transfer paper is fixed by the feeding roller 11 to the fixing roller.
It is fed to 12, fixed by a fixing roller and carried out to the outside. At this time, when the rear end of the transfer sheet completely passes through the transparent guide plate 5, the timer 18 outputs and stops the driver 19, so that the corona discharger 4 stops discharging.

In this way, the transfer paper is completely transferred to the last end thereof, and the charges on the surface of the photoconductor drum, which are excessively charged by the corona discharge, are generated by the light of the discharge lamp 6 radiated through the transparent guide plate 5. The electricity is removed.

Further, the static elimination lamp 6 irradiates the transfer paper immediately after the transfer to eliminate a part of the residual charges to reduce the electrostatic attraction force of the transfer paper to the photosensitive drum 1 and separate the transfer paper from the photosensitive drum 1. In addition to improving the transferability, the transferability of the transfer paper is improved in combination with the action of the transparent guide plate 5.

FIG. 3 is a side view showing the outline of the copying machine shown in FIG. 1. Since the electrophotographic copying machine performs maintenance such as paper jam of the transfer paper and cleaning of the inside, as shown in FIG. Generally, it is configured such that the upper part X and the lower part Y of the main body are separated and opened with the transfer paper transport path as a boundary. Therefore, even if the toner adheres to the transparent guide plate 5 that covers the static elimination lamp 6 as shown in FIG. 1, since the transparent guide plate 5 is exposed in the transfer paper transport path, it is necessary to remove it during cleaning. It can be easily cleaned without.

Further, since the guide plate is formed of a transparent material adjacent to the transfer corona discharger 4 and the discharging lamp is provided under the guide plate, the copying machine is compact.

Further, a plurality of protrusions arranged in the transfer paper conveyance direction may be provided on the transparent guide plate 5, and the transfer paper may be guided while being supported by the protrusions. As a result, the frictional resistance between the transfer paper and the transparent guide plate 5 is reduced, and the transfer paper transfer direction is adjusted to improve the transferability.

(G) Effect of the Invention According to the present invention, the image on the photoconductor is effectively transferred to the transfer paper, and unnecessary charges on the photoconductor are quickly removed by the charge eliminating lamp. Are prevented from adhering and the image forming function of the photoconductor is improved. Furthermore, a transparent plate that guides the transfer paper separated from the surface of the photoconductor in the conveying direction from the transfer device and covers the charge eliminating lamp is provided, and a transparent guide plate is provided for the back surface of the transfer paper and the photoconductor portion charged by the transfer device. Since the charge eliminating lamp is turned on so as to irradiate the toner through the sheet, it is possible to improve the transportability of the transfer sheet and prevent toner from adhering to the charge eliminating lamp. Further, the toner adhering to the transparent guide plate can be easily cleaned because the transparent guide plate is exposed in the transport path.

[Brief description of drawings]

FIG. 1 is an explanatory view of the construction of a copying machine to which an embodiment of the present invention is applied, FIG. 2 is a block diagram showing the main part of the control circuit of FIG. 1, and FIG. 3 is a schematic of the copying machine of FIG. FIG. 1 ... Photosensitive drum, 4 ... Transfer corona discharger, 5 ...
… Transparent guide plate, 6… Static elimination lamp.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhide Yamaguchi 1-2-2 Tamatsukuri, Higashi-ku, Osaka-shi, Osaka Mita Industry Co., Ltd. (56) Reference JP-A-55-156978 (JP, A) JP-A-61-221776 (JP, A) JP-A-55-115070 (JP, A) JP-A-49-8233 (JP, A) JP-A-48-47349 (JP, A) JP-A-56-92560 ( JP, A) JP-A-56-75679 (JP, A)

Claims (1)

[Claims] 1. A toner image formed on a photoconductor is transferred to the surface of a transfer paper by a transfer device to separate the transfer paper from the photoconductor, and the residual toner on the surface of the photoconductor is removed after the transfer. In an electrophotographic apparatus, a charge eliminating lamp is arranged adjacent to the transfer paper carry-out side of the transfer device and at a position where the transfer paper immediately after transfer is irradiated from the back surface, and a transfer paper separated from the surface of the photoconductor from the transfer device. A transparent plate that guides in the conveying direction and covers the charge eliminating lamp, and a control device that activates the transfer device and turns on the charge eliminating lamp are provided, and the control device is provided before the front end of the transfer paper reaches the transfer device. And a transfer period including a predetermined time after the trailing edge of the transfer paper has passed through the transfer device, the transfer device is operated at least during that time, and at least the rear surface of the transfer paper and the transfer device are operated. Electrophotographic apparatus characterized by turning on the charge removing lamp to illuminate through the transparent guide plate charged photoconductor moiety by.