JPS6051864A - Copying machine - Google Patents

Abstract

PURPOSE:To prevent toner sticking and obtain a sharp copy image for a long period by making the width of an effective development area equal to or larger than the width of an effective latent image transfer area and smaller than the width of an intermediate transfer body. CONSTITUTION:An electrostatic latent image transferred onto the dielectric belt 14 of the copying machine is made into a visible toner image by the developing roll 16 of a developing device 6, and this toner image is transferred and fixed on a transfer body 10 through the pressure application or heating operation of a backup roll 8 and a fixing roll 9. In this case, l1>l3>l2, where l1 is the width of the dielectric belt 14, l2 is the width of the effective latent image transfer area formed on the dielectric belt 14 by a transfer roll 15 or corona discharger 17 for transfer, and l3 is the width of the effective development area of the development roll 16. Consequently, toner sticking is prevented and a sharp copy image is obtained for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electrostatic latent image transfer type copying apparatus using an intermediate transfer member.

[Prior art]

A conventional electrostatic latent image transfer type copying apparatus will be described.

In FIG. 1, the photoreceptor 1 is rotatably provided, and as the photoreceptor 1 rotates clockwise.

First, a charger 2 uniformly charges the surface of the photoreceptor 1,
By the subsequent image exposure 3, an electrostatic latent image corresponding to the original is formed on the surface of the photoreceptor 1. This electrostatic latent image on the surface of the photoreceptor 1 is transferred by a transfer roll 5 onto a dielectric belt 4, which is an intermediate transfer member.

The dielectric belt 4 has an insulating layer on the side to which the electrostatic latent image is transferred from the photoreceptor 1, and a conductive layer on the back side thereof.

Next, the electrostatic latent image transferred onto the dielectric belt 4 is transferred to a developing device 6.
The image is visualized by the developing roll 7 to become a 1-ner image.

Subsequently, the toner image on the dielectric belt 4 comes into contact with the transfer body 10 fed by a feeding means (not shown), and is transferred onto the transfer body 10 by the pressure or heating action of the back unroll 8 and the fixing roll 9. The image is fixed and a copy image is formed.

The toner attached to the fixing roll 9 is removed from the cleaning roll 1.
1, and residual charges on the dielectric heald 4 after transfer are eliminated by a static eliminator 12.

FIG. 2 shows a case where a transfer corona discharger 13 is used in place of the transfer roll 5, which is the electrostatic latent image transfer means from the photoreceptor 1 to the dielectric belt 4 in FIG.

[Problems with conventional technology]

In the conventional electrostatic latent image transfer type copying apparatus, as shown in FIG. The widths of the areas 4J and 4J are also approximately the same. Therefore,
The charge is transferred to both ends of the dielectric heald 4 by the transfer roll 5, and a toner image is formed on the entire dielectric heald 4 by the development roll 7. During this development, the toner wraps around and adheres to the conductive layer on the back side of the dielectric belt 4, and when the dielectric belt 4 passes through the hack-up roll 8, this (=J attached toner) is fixed on the conductive layer. There is.First JIJJ
Even if there is a slight amount of toner adhesion, this does not pose a problem when copying an image, but if this phenomenon occurs repeatedly, the toner will stick to the entire conductive layer, making it impossible to maintain the initial resistance value of the conductive layer, which will cause problems in copying. This causes abnormal phenomena such as a decrease in density on the image.

Furthermore, since the width of the dielectric belt 4 is designed to be somewhat wider than the width of the transfer body 10, the toner image formed on the edge of the dielectric heald 4 remains untransferred on the transfer body 1o at the time of printing. A local load is applied to a cleaning section (not shown) for cleaning residual toner on the dielectric heald I-4, and the cleaning ability of the toner at the end of the dielectric heald I-4 is reduced. A fixed L-ner region is formed.

When the toner adhered to the end of the dielectric belt 4 comes into contact with the photoreceptor 1, it may damage the photoreceptor 1 or cause leakage between the toner and the photoreceptor 1.

[Purpose of the invention]

In view of the above-mentioned drawbacks of the conventional art, the present invention has been developed to provide a
- It is an object of the present invention to provide a copying apparatus that prevents the I-ner from getting around the inner heald and sticking to the end of the dielectric heald, and forming clear copied images over a long period of time.

[Key points of the invention]

In order to achieve the above object, the present invention transfers an electrostatic latent image formed on a photoreceptor to an intermediate transfer member, and develops the transferred electrostatic latent image into a visible image.

In a copying device that transfers the visible image to the final transfer member, the width of the effective development area is equal to or larger than the width of the effective latent image transfer area, and It is characterized by being smaller than the width.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 4 and 5 are block diagrams of a copying apparatus showing an embodiment of the present invention. Note that the same parts as in FIG. 1 are designated by the same reference numerals, and redundant explanation will be omitted.

As the photoreceptor 1 rotates clockwise, it is first uniformly charged by the charger 2, and then an electrostatic latent image corresponding to the document (not shown) is formed on the surface of the photoreceptor 1 by image exposure 3. The image is transferred onto a dielectric heald 14, which is an intermediate transfer member, by a transfer roll 15 shown in FIG. 4 or a transfer corona discharger 17 shown in FIG. The dielectric belt 14 has an insulating layer on the side on which the electrostatic latent image is transferred from the photoreceptor 1, and a conductive layer on the back side thereof. In addition, transfer roll 1
5 is a conductive roll, which is in a grounded state or a biased state with a polarity opposite to that of the electrostatic latent image on the photoreceptor 1; A discharge with a polarity opposite to that of the Vi image is generated.

The electrostatic latent image transferred onto the dielectric heald 14 becomes a toner image visualized by the developing roll 16 in the developing device 6, and this toner image is transformed by the pressure or heating action of the hack-up roll 8 and the fixing roll 9. The image is transferred and fixed onto the transfer member 10.

In this embodiment, the width of the dielectric belt 14 is 41, and the effective latent image transfer area ml on the dielectric heald 14 by the transfer roll 15 or the transfer corona discharger 17 is a2. If the width of the effective development area of the development roll I6 is p3 (6th
(see Figure and Figure 7), I! It is configured to satisfy the relationship 1>x3≧β2.

That is, by making the width 13 of the effective development area smaller than the width 11 of the dielectric heald 14, it is possible to prevent the end of the dielectric heald 14 from being developed, and when the image is formed, the end of the dielectric belt 14 is prevented from being developed. Toner rotates around dielectric heald 1
This prevents toner from sticking to the conductive layer on the back surface of the dielectric bell 4 or from sticking to the edge of the dielectric bell 1-14 as untransferred toner to the transfer body 10. However, as mentioned above, the width β3 of the effective development area is made smaller than the width x1 of the dielectric base ratio 14.
Also, the width 12 of the effective latent image transfer area is the width ρ3 of the effective development area.
If the area exceeds the effective development area, the toner is attracted by the transfer charge transferred to the area beyond the effective development area, and the effect of preventing the 1-toner from sticking to the end of the dielectric belt 14 described above is lost. be exposed.

Therefore, by making the width j22 of the effective latent image transfer area equal to or smaller than the width 7!3 of the effective development area, the latent image transfer area is limited so as not to exceed the development area. In other words, by setting the relationship ρ3≧12,
The latent image is transferred to an area beyond the effective development area of the dielectric belt 14, and the transferred charge attracts toner during development, causing the toner to land even in areas beyond the development area that originally do not need to be developed. prevent

In this way, if the relationship of ρ1>p3≧p2 is satisfied, development will be performed to the end of the dielectric heald 14, and an I. This prevents the toner from sticking to the back surface of the dielectric heald 14 or to the end of the dielectric heald 14, thereby forming a copied image with stable image density.

〔Effect of the invention〕

As described in detail above, according to the copying apparatus of the present invention, it is possible to prevent toner from running around to the back surface of the dielectric belt and from sticking to the ends of the dielectric belt.

It is possible to form stable clear copy images over a long period of time.

[Brief explanation of drawings]

1 to 3 are block diagrams of a conventional electrostatic latent image transfer type copying device, FIGS. 4 and 5 are block diagrams of a copying machine showing an embodiment of the present invention, and FIG. A perspective view of an embodiment of the invention;
FIG. 7 is a perspective view of the corona discharge device for transfer. ■...Photoreceptor, 2...Charger. 3... Image exposure, 4.14... 11 no 1 to dielectric,
5.15...Transfer roll. 6. ・Developer, 7.16...Developer roll, 8.
...Huck up roll. 9...Fixing roll, 10...Transfer body. 11... Cleaning roll, 12... Static eliminator, 13.17... Corona discharger for transfer Patent applicant: Casio Computer Co., Ltd. Same as above Yoshiyuki Osuga, agent of ID Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6M Figure 7

Claims (1)

[Claims] The electrostatic latent image formed on the photoreceptor is transferred to an intermediate transfer member,
In a copying device that develops the transferred electrostatic latent image into a visible image and transfers the visible image to a final transfer member, the width of the effective development area is set equal to the width of the effective latent image transfer area or A copying apparatus characterized in that the width is larger than the width of the latent image transfer area and smaller than the width of the intermediate transfer member.