JPS62235150A - Image forming device - Google Patents

Abstract

PURPOSE:To make it possible to obtain a stable registration and image transferability of an image transfer medium, in an image forming device using toner, by providing an air suction means for absorbing the image transfer medium onto a conveyer belt. CONSTITUTION:When a suction fan 87 driven, air A flowing into a suction means 71 from above a conveyer belt 61a causes an image transfer medium P to make in contact with the upper surface of the conveyer belt 61a, and the medium P, therefore, is fed into the area of transfer chargers 41, 42 without being affected by a paper feed roller 65. Further, during toner images are transferred from image forming stations I, II in a transfer area, charge having a polarity which is reverse to that of image transfer corona is applied from exposure drums 11, 12 onto the upper surface of the conveying belt 61, that is, electrostatic absorption is effected. Thus, the image transfer medium is efficiently absorbed onto the conveyer belt without receiving the influence of surroundings with no necessity of an absorbing charger, and therefore, it is possible to realize a stable registration and image transferability of the image transfer medium, thereby it is possible to obtain a high quality image with a simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION f1 The present invention relates to an image forming apparatus in which a transfer material faces an image carrier carrying a toner image, and a discharge for transfer, for example, a corona discharge, is applied from the back side to obtain a transferred image on the transfer material. In particular, it relates to an image forming apparatus that forms toner images at multiple image forming stations, conveys a transfer material to each image station using a conveyor belt device, and transfers each toner image onto the same transfer material in an overlapping manner. be.

In this specification, the term "image forming apparatus" includes various color printing apparatuses such as a color copying apparatus, a computer, and a color printer serving as an output section of a facsimile machine.

In recent years, electrophotographic copying devices, which are a type of image forming devices, have been
With the increasing use of its functions, it has become possible to make copies not only with black toner but also with multicolor toners such as red, blue, and green.

As shown in FIG. 3, the copying apparatus has a plurality of image forming stations, forms a toner image of a predetermined color, and conveys the transfer material to each image forming station by a conveyor belt device. However, there is a structure in which toner images of different colors formed at each image forming station are sequentially transferred onto the same transfer member in an overlapping manner.

Furthermore, to briefly explain this type of copying apparatus with reference to FIG. , ■, ■, and ■, toner images of cyan toner, magenta toner, yellow toner, and black toner are formed.

Image forming station 1. II, ■, ■ are photosensitive drums (
A latent image carrier) 11.12.13.14 is provided on its outer periphery with a primary corona charger 21.22.23.24, a developing device 31.32.33.34, and a transfer charger 41. 42
．． 43.44 and cleaning device 51.52.53.5
4 and 4 respectively.

These image forming stations ①, ②, ② are connected to the photosensitive drum 1 by the primary corona charger 21, 22, 23, 24.
After charging the surfaces of 1.12.13.14, beams I+, Iz, I1.
I4 is scanned over the photosensitive drums 11, 12, 13, and 14 to form an electrostatic latent image.

Each electrostatic latent image is developed by developing devices 31, 32, 33, and 34 containing cyan toner, magenta toner, yellow toner, and black toner, respectively, to form cyan, magenta, yellow, and black toner images. be done.

Each of these toner images is sequentially transferred to a transfer material P conveyed by a conveyor belt device 61 by transfer chargers 41, 42, 43, .
A color image is formed on the transfer material P by passing over the color image 44 and performing multiple transfers, and is fused and fixed in the fixing device 70.

In such a device, the conveyor belt device 61 has a thin
A conveyor belt 61a formed into an endless shape using an IE body sheet or a screen mesh is connected to a driving roller 63.
and a driven roller 64 to rotate in the direction of the arrow. Then, the transfer material P is electrostatically attracted onto the conveyor belt 61a by the attraction charger 62, and is conveyed in close contact with the belt h61a. Moreover, this conveyor belt device 61 is
In order to prevent image shift from occurring on the transfer material P, the conveyor belt 61a is accurately driven so as not to cause lateral shift, meandering, twisting, or the like.

However, in the image forming apparatus having the above configuration, if a thin dielectric sheet is used for the conveyor belt 61a, it may be excessively charged (charged up) due to corona charging by the transfer charger. If the dielectric constant of the dielectric sheet is lowered to avoid such charge-up, excessive charging as described above can be avoided, but the adsorption and transferability of the transfer material will be reduced. This problem has made it extremely difficult to select a material for the dielectric sheet.

On the other hand, when a mesh screen is used for the conveyor belt 61a, the above-mentioned problems such as charge-up of the conveyor belt and deterioration of transfer performance are reduced, but a problem arises in that the adsorption of the transfer material is decreased. . If the adsorption of the transfer material is insufficient, the transfer material will move on the conveyor belt during conveyance and transfer, resulting in unstable registration and transfer misalignment, that is, color misalignment, making it impossible to obtain a good quality image. There was a problem with it disappearing. Therefore, when such a conveyor belt is used, an electrostatic charger 62 for attracting the transfer material to the conveyor belt is essential.

However, in reality, even if an electrostatic adsorption charger is installed, the transfer material tends to be affected by the paper feed roller and have poor adhesion onto the conveyor belt until it reaches the first image forming station. be. Similarly, even just before leaving the final image forming station, the transfer material may be affected by the fixing device and may move on the conveyor belt, resulting in transfer misalignment.

Moreover, generally speaking, the electrostatic adsorption force using an adsorption charger tends to fluctuate in proportion to the environment, especially humidity.
Extremely unstable. Furthermore, the electrostatic adsorption method, which is declined, not only requires a high-voltage power source for the adsorption charger, but also generates ozone, which is not preferable from an environmental point of view.

Therefore, it is an object of the present invention to efficiently adsorb a transfer material onto a conveyor belt without using an adsorption charger and without being affected by the environment, thereby achieving stable registration and transfer of the transfer material. An object of the present invention is to provide an image forming apparatus that can realize high quality images and obtain high quality images.

Another object of the present invention is to provide an image forming apparatus that has a simple structure, does not generate odors, and is environmentally friendly.

. for the city The above object is achieved by an image forming apparatus according to the present invention.

In summary, the present invention provides an image forming apparatus in which toner images are formed at a plurality of image forming stations, a transfer material is conveyed to each image station by a conveying belt device, and the toner images are superimposed and transferred onto the same transfer material. , the conveyor belt device has an air-permeable conveyor belt that circulates endlessly in order to convey the transfer material, and the transfer belt is provided on the upstream side and/or the downstream side of the internal space defined by the conveyor belt. In a preferred embodiment of the present invention, the image forming apparatus is characterized in that an air suction means for adsorbing materials to the conveyor belt is provided. located at at least one of the last image stations. That is, the air suction means is disposed immediately before the first image forming station, or immediately after the last image forming station, or at least immediately before the first image forming station and immediately after the last image forming station. Also preferably, the conveyor belt is made of a dielectric mesh belt.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The image forming apparatus according to the present invention will be described in more detail below with reference to the drawings.

An embodiment of the present invention is illustrated in FIGS. 1 and 2. FIG.

In this embodiment, the present invention is embodied in the four-color electrophotographic copying apparatus described above in connection with FIG. 3, but FIGS. is illustrated.

Referring to FIG. 1, six images partially illustrate the first image forming station I, the second image forming station II, and the conveyor belt assembly 2t61 corresponding to each of these stations of the image forming apparatus according to the present invention. In the forming apparatus, the transfer material P is fed by a paper feed roller 65 to a conveyor bell 61a. The conveyor belt (61a) is air permeable to allow air flow across the belt, and is typically, but not limited to, a perforated belt with a large number of holes, preferably made of dielectric material. 1. For example, it is a screen-like mesh screen made of synthetic resin such as Tetron or fiber and having about 50 to 100 meshes.

The conveyor belt having the structure shown in FIG.

As can be seen from FIG. 3, the conveyor belt 61a is suspended around rollers 63 and 64 and endlessly circulated in the direction of the arrow at a predetermined speed. Further, the transfer material P supplied by the supply roller 65
The supply speed is adjusted to be the same as or slightly faster than the speed of the conveyor belt 61a.

According to the present invention, the driven roll 64 and the transfer charger 4 are located in the internal space defined by the conveyor belt 61a and located immediately before the image forming station T in this embodiment.
Air suction means 81 is provided in the space between 1 and 1.

The suction means 81 has a plurality of suction holes, and has a conveyor bell).
A support plate 83 that slidably supports the support plate 61a, and the support plate 8
Sirocco type fan (suction fan) installed below 3.
87.

In such a configuration, when the suction fan 87 is operated, the surrounding air (air) is removed from the conveyor bell as shown by arrow A.
The liquid flows from above 61a through the holes in the conveyor belt and into the suction means. Due to this air flow, the transfer material P on the conveyor belt is pressed onto the conveyor belt, and the transfer material P on the conveyor belt is
According to experiments conducted by the present inventors, the paper is conveyed to the transfer charger area in close contact with the paper feed roller 65 without being affected by the paper feed roller 65. It was found that the transfer material P was attracted to the conveyor belt 61a.

The transfer material P conveyed in close contact with the conveyor belt in this way is injected with an electric charge of the opposite polarity to the transfer corona from the photosensitive drum 1 when transferring the toner image of the image forming station E in the desired transfer area. and is electrostatically attracted to the upper surface of the conveyor bell) 61a.

Therefore, after the transfer material P reaches the image forming station I, it is not necessary to attract it to the conveyor belt using a suction means, but as mentioned above, the electrostatic attraction force is particularly affected by the amount of humidity. Therefore, in a humid environment, a suction means other than the suction means 81 can be additionally provided, for example, between the image forming stations, between the image forming stations, or between other image forming stations.

According to another aspect of the present invention, as shown in FIG. 44 and the conveyor belt drive roller 63. According to this configuration, the transfer material P at the position immediately before leaving the last image forming station (2) is transferred to the fixing device 7.
0 slows down or speeds up the movement of the transfer material, thereby avoiding any adverse effect on the transfer material P which is still undergoing transfer operation at the image forming station (2).

In this case, if the distance between the image forming station (2) and the fixing device 70 is longer than the length of the transfer material P, the suction means 81 can be omitted, but on the other hand, the image forming apparatus becomes larger. Therefore, as described above, by installing the suction means 81 according to the present invention, there is an advantage that the image forming apparatus can be made smaller.

In the above explanation, the suction fan of the suction means 81 is connected to the support plate 8.
3, the air suction means 81 is a suction fan 87.
Instead, a similar fan 87 is provided outside the conveyor belt 61a instead of in the internal space to generate air flow through an air duct (not shown) to move the transfer material P to the conveyor belt 61a.
It is also possible to adopt a structure in which the material is adsorbed onto a.

11 As described below, in the image forming apparatus according to the present invention, the conveyor belt device has an air-permeable conveyor belt that circulates endlessly in order to convey the transfer material, and the image forming apparatus is formed by the conveyor belt. An air suction means for adsorbing the transfer material onto the conveyor belt is provided in the internal space where the transfer material is placed onto the conveyor belt, and therefore the transfer material can be efficiently transferred onto the conveyor belt without the need for an adsorption charger and without being affected by the environment. It has the advantage of being able to absorb, achieve stable registration and transferability of the transfer material, obtain high-quality images, and further simplify and downsize the structure.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the main parts of the image forming apparatus according to the present invention, and particularly explains the action of the suction means installed upstream of the conveyor belt. FIG. 2 is a schematic cross-sectional view of the main parts of the image forming apparatus, similar to FIG. 1, and particularly explains the action of the suction means installed downstream of the conveyor belt. FIG. 3 is a schematic cross-sectional view of a conventional image forming apparatus. I: P & first image forming station ■: Last image forming station 61a: Conveyor belt 81. 82: Suction means) L 83: Multi◆ Support plate 87: Suction fan P: Transfer material Fig. 1 m 1

Claims (1)

[Scope of Claims] 1) An image forming apparatus that forms toner images at a plurality of image forming stations, transports a transfer material to each image station using a conveyor belt device, and transfers each of the toner images onto the same transfer material in an overlapping manner. In the above, the conveyor belt device has an air-permeable conveyor belt that circulates endlessly to convey the transfer material, and the above-mentioned conveyor belt is provided on the upstream side and/or the downstream side of the internal space defined by the conveyor belt. An image forming apparatus characterized in that an air suction means for attracting the transfer material to the conveyance belt is provided. 2) The apparatus according to claim 1, wherein the air suction means is arranged immediately before the first image forming station. 3) The apparatus according to claim 1 or 2, wherein the air suction means is arranged immediately after the last image forming station. 4) The apparatus according to any one of claims 1 to 3, wherein the conveyor belt is a dielectric mesh belt. 5) The device according to any one of claims 1 to 4, wherein the suction means includes a suction fan and a support plate with holes for supporting the conveyor belt.