JPH04360179A - Electrophotographic printer - Google Patents

Abstract

PURPOSE:To attain reduction in the driving source of an electrophotographic printer having a carrying belt for primarily transferring a toner image from a photosensitive body, and secondarily transferring the toner image on a form. CONSTITUTION:The electrophotographic printer has an image forming unit, forming a visual image on the image forming surface of a image carrier 4, a primary transfer unit 5 primarily transferring the visual image on the image carrier to an endless belt 6 having releasability with static electric force, and a secondary transferring/fixing roller 9 secondarily transferring and simultaneously, fixing an image formed on the endless belt to a recording form 11 in such a manner that the endless belt is brought into contact with the recording form on the above-mentioned image forming surface, pressurized and heated. A sprocket 12 as the carrying means of the endless belt 6 is formed on the circumference of the secondary transferring/fixing roller 9.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to electrophotographic printing apparatus.

0002

[Prior Art] Conventionally, an electrophotographic printing apparatus that transfers a toner image from an image bearing member (photosensitive drum) to a recording medium (paper) using an endless belt is known as an endless belt, as described in Japanese Patent Application No. 3-95929. To drive the belt, it had a conveyance means independent from the primary transfer device, secondary transfer fixing device, etc.

0003

The conventional electrophotographic printing apparatus described above has a conveying means for driving the endless belt in a portion independent of the primary transfer device and the secondary transfer fixing device. Therefore, extra space is required, making it impossible to make the device compact, and the number of parts increases.
This was a cause of increased costs.

[0004] Furthermore, since the load on the secondary transfer/fixing section is large, the belt tension fluctuates greatly, which may cause the belt to stretch or break, or cause belt feeding in the primary transfer section and the secondary transfer/fixing section. This caused the speed to fluctuate.

[0005]

[Means for Solving the Problems] The electrophotographic printing apparatus of the present invention includes an image forming device that forms an image on an image carrier, and a primary transfer that transfers the image on the image carrier to an endless belt using electrostatic force. and a secondary transfer fixing roller that simultaneously transfers and fixes the image formed on the endless belt onto a medium, and the endless belt is driven by a conveying means formed around the secondary transfer fixing roller. It is characterized by

[0006]

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

Referring to FIG. 1, the first embodiment of the present invention performs printing using a process similar to that of the electrophotographic printing apparatus described in the above-mentioned Japanese Patent Application No. 3-95925, but uses secondary transfer. A heat roller 9 is used as the fixing means, sprockets 12 are provided at both ends of the heat roller 9, and the endless belt 6 is driven by the driving force of the heat roller 9 via the sprocket.

That is, the charger 1 is connected to the photoconductor (OPC) 4.
The surface of the drum is uniformly charged by corona discharge, and then an electrostatic latent image is formed on the drum by the exposure device 2. The developing device 3 attaches negatively charged toner to the latent image formed on the drum of the photoreceptor (OPC) 4 to visualize it, and in the transfer section, the toner image on the drum is transferred to the electrostatic charge of the transfer device 5 using an elastic roller. The force transfers the image from the drum surface to the releasable endless belt 6. The endless belt 6 has its end engaged with a sprocket 12 formed around the end of the heat roller 9 which is rotationally driven by a motor 15.
It is driven by the rotation of the heat roller 9 and conveys the toner image 7 to the fixing section. In the fixing section, a recording paper 11 is passed between a heat roller 9 containing a halogen lamp 8 as a heat source and a pressure roller 10 for applying pressure, and the unfixed toner image 7 on the endless belt 6 is fixed by heat and pressure fixing. The images are transferred and fixed onto the recording paper 11 at the same time.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the second embodiment of the present invention, the tension of the belt 6 is adjusted by a belt tension adjustment mechanism using a roller 13 provided downstream of the heat roller 9. The other configurations are the same as in the first embodiment.

As described above, since the tension of the endless belt 6 is adjusted by the roller 13, which is a belt tension adjustment mechanism provided downstream of the belt conveyance means, the endless belt 6 is not slackened, and the primary transfer section, There is no fluctuation in belt feeding speed in the secondary transfer/fixing section. Also,
This eliminates the drawback that the feeding speed of the primary transfer section, the secondary transfer fixing section, or both belts fluctuates due to load fluctuations on the belt, which occurs when the belt adjustment mechanism is provided upstream of the belt conveying means.

0012

As explained above, in the present invention, since the endless belt is conveyed by the secondary transfer fixing roller, there is no need for any other dedicated conveyance means, and space-saving and
It is possible to reduce the number of parts and reduce costs. Also,
It is possible to reduce fluctuations in the tension of the endless belt caused by a large load on the secondary transfer fixing section.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of a first embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of a second embodiment of the present invention.

Claims (2)

[Claims] 1. An image forming device that forms a visible image on an image forming surface of an image carrier, and a primary transfer device that primarily transfers the visible image on the image carrier to an endless belt having a releasing property by electrostatic force. and a secondary device that simultaneously transfers and fixes the image formed on the endless belt onto the recording medium by bringing the endless belt into contact with the recording medium at the image forming surface and applying pressure and heat. 1. An electrophotographic printing apparatus comprising: a transfer fixing roller; and a conveying means for the endless belt is provided around the secondary transfer fixing roller. 2. The electrophotographic printing apparatus according to claim 1, wherein a tension adjustment mechanism for adjusting the tension of the endless belt is engaged on the downstream side of the transfer fixing roller of the endless belt.