JP2767992B2 - Electrophotographic process unit - Google Patents

Description

The present invention relates to an image forming apparatus such as a copying machine or a printer,
In particular, the present invention relates to an electrophotographic process unit for forming an image.

[Conventional technology]

FIG. 3 shows a vertical cross-sectional view of a conventional electrophotographic process unit, and includes a photoconductive image carrier 101, a charge charger 102, a developer container 104 including a developer carrier 105, The residual developer container 107 is provided integrally. 4 (a) to 4 (d) show the state of the electrophotographic process, in which the left side shows the image portion and the right side shows the non-image portion, respectively. When a negative electric field is uniformly applied by the charged charger 102, a negative charge is generated on the surface of the image carrier 101 (see FIG. 4A). Next, when the image carrier 101 is exposed to image information 103, the charge of the image carrier 101 disappears (see the left side of FIG. 4B). Further, the image carrier 101 in the non-image area where the exposure 103 is not performed
Does not change (see the right side of FIG. 4B). Subsequently, the developer 106 in the developer storage container 104 is negatively charged and adhered in a layer to the developer carrier 105 to form a developer layer. A negative electric field is supplied to cause the developer 106 to adhere to the image area where no negative charge exists on the surface of the image carrier 101 (see the left side of FIG. 4C). The image carrier is located in the non-image area.
Due to the repulsion between the negative charge on the surface of 101 and the negative charge of the developer 106, the developer 106 does not adhere (see the right side of FIG. 4 (c)). When a positive electric field is applied by the transfer charger 109, the developer 106 in the negatively charged image area is transferred to the recording medium 111. Further, when an AC electric field is applied by the separation charger 110, the recording medium 111 is applied to the image area. The developer 106 is separated from the image carrier 101 while holding the developer 106 (see the left side of FIG. 4D). Here, the developer 106 remaining on the image carrier 101 without being transferred to the recording medium 111 was collected in the residual developer accommodating container 107, and the charge of the image carrier 101 was eliminated by the static elimination 108.

[Problems to be solved by the invention]

In the above-described conventional electrophotographic process unit, since a developer accommodating container and a residual developer accommodating container are provided as means for accommodating the developer around the image carrier, the space required for the configuration becomes large, and the apparatus becomes large. It was difficult to reduce the size. Further, since all of the developer on the image carrier remains without being transferred to the recording medium and is partially collected in the residual developer storage container, it is possible to use all the developer in the developer storage container. There was a disadvantage that it could not be done.

[Means for solving the problem]

The electrophotographic process unit of the present invention includes: a developer carrier having photoconductive properties and holding a developer; a charging unit configured to charge the developer carrier and the developer; and a thin layer of the charged developer. Forming a thin layer on the developer carrier, exposing means for forming an electrostatic latent image on the developer carrier, and transferring means for transferring a developer corresponding to the electrostatic latent image. A developer container for supplying a developer to the developer carrier, and a developer container housed in the developer container, the tip of which is pressed against the developer carrier and inclined downward toward the inside of the developer container. And a plate-shaped removing member that removes the developer and returns the developer to the developer storage container. An area in which the removing member, the charging unit, and the thin layer forming unit are arranged in this order is the developer carrying member. It is arranged facing the transfer means with the body in between.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. In FIG. 1, a developer storage container 3 is provided with a removing member 4, a transporting member 5, a charging member 6, and a layer forming member 7, and is filled with a developer 8 inside the developer accommodating container 3. A developer carrier 1 having a drum shape and having photoconductivity and a charged charger 2 are provided outside the developer storage container 3. The charging charger 2 may have a detachable structure. The removing member 4 removes the developer 8 remaining on the developer carrier 1 without being transferred to the recording medium 11 and mixes the removed developer 8 with the developer 8 in the developer accommodating container 3. The conveying member 5 is a member that conveys the developer 8 to the charging member 6. In order to charge the developer 8, the charging member 6 is made of an insulating member capable of being triboelectrically charged, or a conductive member capable of injecting electric charge from the outside. Reference numeral 8 denotes a member for forming the developer 8 guided on the developer carrier 1 in a layer shape, and is attached so as to maintain a constant gap with the developer carrier 1. The removing member 4, the conveying member 5, and the layer forming member 7 may have the same charging function as the charging member 6 gives to the developer 8.

2 (a) to 2 (d) show the state of the electrophotographic process in the present embodiment, when the determination is made in a direction perpendicular to the center axis of the drum-shaped developer carrier 1. FIG. Is a cross-sectional view of each part, and the left side shows an image part and the right side shows a non-image part.

First, an electric field is applied to the developer carrier 1 by the charged charger 2 to uniformly negatively charge the surface of the developer carrier 1 (see FIG. 2A). Next, the developer 8 transported from the transport member 5 is positively charged by the charging member 6 and adheres to the developer carrier 1 by electrostatic force, and a uniform layer is formed by the layer forming member 7 (the first layer). (See FIG. 2 (b)). When the image information is exposed to light 9 from a layer of the developer 8 using a laser or a light source such as an LED, the negative charges on the surface of the developer carrier 1 disappear, and the positive charges of the layered developer 8 are removed. Remains (FIG. 2 (c)
See left). Further, in the non-image area where the exposure 9 is not performed, neither the charge of the developer carrier 1 nor the charge of the layered developer 8 changes (see the right side of FIG. 2C). Here, when a negative electric field is uniformly applied by the transfer charger 10 from above the recording medium 11, negative charges are generated on the surface of the recording medium 11 on the side of the transfer charger 10, and negative charges exist on the surface of the developer carrier 1. Only the developer 8 in the non-image area flies and is transferred to the recording medium 11 by electrostatic force with negative charges on the recording medium 11 (see the left side of FIG. 2D). Further, the developer 8 in the non-image area is the developer carrier 1
Due to the electrostatic force with the negative charge on the surface of the developer carrier 1, the toner remains on the surface of the developer carrier 1 and is not transferred (see the right side of FIG. 2 (d)). However, the electric field provided by the transfer charger 10 is such that the developer 8 in the non-image portion does not transfer to the recording medium 11 and only the developer 8 in the image portion having no charge on the surface of the developer carrier 1 transfers to the recording medium 11. Size. Then, the developer carrier 1 is subjected to static elimination 12 and the developer carrier 1 is removed.
Is removed. Finally, the developer 8 remaining on the developer carrier 1 is removed from the developer carrier 1 by the removing member 4, and is reused by being mixed with the developer 8 in the developer storage container 3.

〔The invention's effect〕

As described above, the present invention provides a developer carrier having photoconductivity, and after forming a developer layer on the developer carrier,
Exposure is performed to form an electrostatic latent image on the developer carrier, and the developer on the developer carrier corresponding to the electrostatic latent image, that is, only the developer in the image area is transferred to the recording medium, and the residual Since the developed developer is collected in the developer storage container, a residual developer storage container is not required, so that the space required for the configuration can be reduced, and the size of the apparatus can be reduced. In addition, all of the developer in the developer storage container can be used, and the running cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIGS. 2 (a) to 2 (d) are views showing a state of an electrophotographic process in the embodiment. 3 is a longitudinal sectional view showing a conventional example, and FIGS. 4 (a) to 4 (d) are views showing a state of a conventional electrophotographic process. 1 ... developer carrier, 2 ... charged charger, 3 ...
Developer storage container, 4... Removal member, 5... Stirring member, 6
... charging member, 7 ... layer forming member, 8 ... developer, 9 ...
Exposure, 10 Transfer charger, 11 Recording medium, 12
... static elimination, 101 ... image carrier, 102 ... charged charger, 10
3 Exposure, 104 developer storage container, 105 developer carrier, 106 developer, 107 residual developer storage container, 10
8: static elimination; 109: transfer charger; 110: separation charger; 111: recording medium.

Claims (1)

(57) [Claims] 1. A developer carrier having photoconductivity and holding a developer, charging means for applying a charge to the developer carrier and the developer, and a thin layer of the developer being charged by the developer Thin layer forming means for forming on a carrier, exposure means for forming an electrostatic latent image on the developer carrier, transfer means for transferring a developer corresponding to the electrostatic latent image, and the developer A developer accommodating container for supplying the developer to the carrier, and a developer accommodating container accommodated in the developer accommodating container, wherein a tip of the developer accommodating container is pressed down toward the developer accommodating container and is inclined downward toward the inside of the developer accommodating container. A plate-like removing member that removes a developer and returns the developer to the developer accommodating container. An area arranged in the order of the removing member, the charging unit, and the thin layer forming unit sandwiches the developer carrier. An electrophotographic printer, wherein the electrophotographic printer is disposed so as to face the transfer means. Processes unit.