JP2936812B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bias roller transfer type electrophotographic apparatus.

[0002]

2. Description of the Related Art Conventionally, electrophotographic apparatuses have been used in copiers, laser printers and the like.

Hereinafter, a conventional electrophotographic apparatus will be described. As shown in FIGS. 2 and 3, an organic optical semiconductor belt (hereinafter, referred to as an organic optical semiconductor) 1 is wound around an OPC driving roller 2 and is driven. Reference numeral 4 denotes a charger for uniformly charging the surface of the OPC belt 1 attached close to the OPC belt 1, and 7 denotes an OPC according to image information.
The laser irradiator irradiates the belt 1 with light. Developing device 8
A developing unit 8a for attaching black toner to the electrostatic latent image formed on the OPC belt 1 to visualize the toner; and attaching cyan toner to the electrostatic latent image formed on the OPC belt 1 for visualization. A developing device 8b for developing a visible image and a magenta toner
A developing device 8c for attaching and developing the electrostatic latent image formed on the PC belt 1 and a developing device for attaching yellow toner to the electrostatic latent image formed on the OPC belt 1 and developing the image; 8d. Belt-shaped intermediate transfer member 9
Is driven by being wound around an intermediate transfer belt driving roller 3. Reference numeral 11 denotes an intermediate transfer roller for transferring the toner adhered to the OPC belt 1 to the intermediate transfer member 9;
An OPC cleaning device for scraping off residual toner on the PC belt 1 for cleaning, and 6 is an OP after cleaning.
This is a static eliminator for eliminating charges on the C belt 1. The transfer roller 13 presses the transfer paper 12 conveyed by the conveyance roller 17 from the paper cassette 16 to the intermediate transfer body 9, applies a transfer voltage, and transfers the toner attached to the intermediate transfer body 9 to the transfer paper 12. Reference numeral 10 denotes a cleaning device for scraping off residual toner on the intermediate transfer member 9 after transfer, reference numeral 15 denotes a fixing device for fixing the toner transferred to the transfer paper 12, and reference numeral 14 denotes a meandering preventing member for the belt-like intermediate transfer member 9. .

The operation of the image forming apparatus configured as described above will be described below. First, the OPC belt 1 is rotated by the OPC drive roller 2 while the charger 4 is rotated.
When a voltage is applied to the surface of the OPC belt 1, when the laser irradiator 7 irradiates the surface of the OPC belt 1 with a laser beam that gives black image information, the irradiated portion of the surface of the OPC belt 1 loses its charge and forms an electrostatic latent image. Is done.

Next, the electrostatic latent image formed on the surface of the OPC belt 1 is visualized by black toner by a developing device 8a, and the black toner is transferred to the intermediate transfer roller 11 to which a transfer voltage is applied by a belt. -Shaped intermediate transfer body 9 by OPC
The image is transferred to the intermediate transfer member 9 by pressing the belt 1. The residual toner remaining on the surface of the OPC belt 1 is OPC
The residual toner that has been scraped off by the cleaning device 5 is collected inside the OPC cleaning device 5, and the OPC belt 1 from which the residual toner has been scraped is neutralized by the static eliminator 6. By the same operation as the black image information, the cyan image information is transferred so as to be superimposed on the black toner image of the intermediate transfer body 9 on which the toner image developed by the developing device 8b has been previously transferred. Similarly, a color toner image is temporarily stored on the intermediate transfer member 9 by a total of four color toners in the order of magenta and yellow. The transport roller 17 transports the transfer paper 12 between the intermediate transfer member 9 and the transfer roller 13 at the same transport speed as the intermediate transfer member 9 while aligning the transfer paper 12 with the toner image on the intermediate transfer member 9 from the paper cassette 16. Then, a voltage having a polarity opposite to the charging polarity of the toner particles constituting the toner image is applied to the transfer roller 13 from the back side of the transfer paper 12 as viewed from the toner image on the intermediate transfer member 9. By performing the roller transfer, the toner image on the intermediate transfer body 9 is transferred to the transfer paper 12. The residual toner remaining on the surface of the intermediate transfer member 9 is scraped off by the cleaning device 10, and the scraped residual toner is collected inside the cleaning device 10. The toner image transferred to the transfer paper 12 is fixed by the fixing device 15.

As shown in FIG. 3, instead of the transfer roller 13, a corona discharge device 18 applies a corona charge having an electrical polarity opposite to the charge polarity of the toner particles from the back side of the transfer paper 12 as viewed from the toner image. The conventional example in which the toner image is corona-transferred by giving the toner image No. 12 has a problem that the generation of ozone by corona discharge deteriorates the life of the photosensitive member due to deterioration of the electrical characteristics and adversely affects the use environment. Recently, the roller transfer system has been reviewed again.

[0007]

However, in the above-mentioned conventional configuration, there is a large margin for setting conditions such as the thickness of the transfer paper 12 and the way of guiding the paper entry into the transfer area. The contact mechanism and its timing, a cleaning mechanism for removing toner attached to the surface of the transfer roller 13, and the transfer roller 13 for increasing the transfer efficiency of the toner image to the transfer paper 12
Although a high voltage is applied, particularly at both ends of the transfer roller 13, a leak easily occurs between the transfer roller 13 and the intermediate transfer member 9 formed of a dielectric member having a medium electric resistance. The resulting high voltage has a voltage drop, and the toner image corresponding to the portion where the voltage has dropped is not transferred to the transfer paper 12, so that there is a problem that an image defect called transfer omission is likely to occur.

The present invention solves the above-mentioned conventional problems. Voltage leakage can be prevented, the transfer bias of the transfer roller does not drop, no image defects such as transfer omission occur, and fluctuations in toner transfer efficiency occur. It is an object of the present invention to provide a highly reliable electrophotographic apparatus having a low transfer rate and a high transfer rate.

[0009]

In order to achieve this object, an electrophotographic apparatus according to the present invention comprises a high-resistance insulating member which is covered on the surface of an intermediate transfer member corresponding to the positions of both ends of a transfer roller. Things.

[0010]

According to this structure, the electric field is concentrated most at both ends of the transfer roller, and leakage at a portion where voltage leakage is likely to occur can be prevented.

[0011]

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

The basic configuration and operation of an embodiment of the present invention are the same as those of the conventional example described with reference to FIG.

As shown in FIG. 1, the intermediate transfer member 9 is made of a material such as polycarbonate or polyethylene phthalate having a uniform and suitable electric resistance which is hardly affected by changes in the surrounding temperature and humidity and which is provided by dispersion of carbon black or the like. A high-resistance insulating member 14 is provided on the surface of the intermediate transfer member 9 corresponding to both end portions of the transfer roller 13.

As described above, according to the present embodiment, in the state where the transfer roller 13 to which the high voltage opposite to the charging electrode property of the toner particles is applied is brought into contact with the intermediate transfer member 9 via the transfer paper 12. Also, the surface of the intermediate transfer member 9 which directly contacts the both end portions of the transfer roller 13 is formed of an insulating member
Covering with 4 prevents a voltage leak from the transfer roller 13 and can provide a good image without transfer omission.

In the conventional corona transfer method or bias roller transfer method from the back side of the transfer paper 12, the transfer paper 12 absorbs moisture when the surrounding temperature and humidity increase, and the electrical resistance and dielectric constant of the transfer paper 12 are reduced. However, the transfer electric field also changed and the stable transfer efficiency of the toner could not be maintained due to the change of the transfer electric field. It is possible to achieve high image quality without deterioration of image quality such as color unevenness in an image or a color image.

[0016]

As is clear from the above description of the embodiment, the present invention has a structure in which a high-resistance insulating member is provided over the surface of the intermediate transfer member corresponding to the positions of both ends of the transfer roller. A voltage leak can be prevented, the transfer bias of the transfer roller is eliminated, no image defects such as transfer omissions occur, the toner transfer efficiency does not fluctuate, and an excellent electrophotographic device with high transfer efficiency and high reliability is realized. You can do it.

[Brief description of the drawings]

FIG. 1 is a front view showing the configuration of an intermediate transfer member and a transfer roller of an electrophotographic apparatus according to one embodiment of the present invention.

FIG. 2 is a side view showing the concept of the configuration of the electrophotographic apparatus of the present invention and a conventional example.

FIG. 3 is a front view showing a configuration of an intermediate transfer member and a transfer roller of a conventional electrophotographic apparatus.

FIG. 4 is a side view showing the concept of the configuration of another conventional electrophotographic apparatus.

[Explanation of symbols]

 Reference Signs List 3 drive roller 9 intermediate transfer member 11 intermediate transfer roller 12 transfer paper 13 transfer roller 14 insulating member

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/16

Claims (1)

(57) [Claims] 1. A transfer device according to claim 1, further comprising a transfer device for transferring a toner image on the latent image carrier and a toner image on the latent image carrier. An image forming apparatus that transfers a toner image to transfer paper by an applied transfer roller and then fixes the toner image,
An electrophotographic apparatus comprising: an insulating member that covers the surface of the intermediate transfer member that contacts both ends of the transfer roller.