JPH0264676A - Transfer device - Google Patents

Abstract

PURPOSE:To surely peel off transfer material from a photosensitive drum and to prevent a printing surface from being soiled by constituting the transfer device so that a tangent in contact with a transfer port roll and the photosensitive drum can form an angle on the upstream side of the rotating direction of the photosensitive drum with respect to a tangent in contact with the photosensitive drum and a fixing roll. CONSTITUTION:The transfer device is constituted in such a way that the tangent 113 in contact with the transfer port roll 112 and the photosensitive drum 100 can form an angle on the upstream side of the rotating direction of the photosensitive drum 100 with respect to the tangent 114 in contact with the photosensitive drum 100 and the fixing roll 104. As a result, the transfer material 116 is bent greatly and the force which arises by the stiffness of the transfer material 116, and peels off the transfer material 116 from the photosensitive drum 100 becomes greater. Consequently, the transfer material can be peeled off surely to prevent the printing surface from being soiled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a transfer device for an electrophotographic copying machine or printer using electrophotographic technology.

[Prior art 1] Generally, in copying machines and printers using electrophotographic technology, an electrostatic latent image is formed on a photosensitive drum by an exposure device.
The electrostatic latent image is made visible on the photosensitive drum by adhering toner with a developing device, and the toner image is further transferred by a transfer device onto a transfer material such as paper conveyed from the outside. The transfer material is sent to a fixing device, and the toner image on the transfer material is fixed. A typical transfer device includes a shield member having an opening facing the photosensitive drum, and 15! disposed inside the shield member. j. It is possible to provide a corona transfer device that electrostatically transfers a toner image on the photosensitive drum onto the transfer material by charging a transfer material conveyed closely to a photosensitive drum by a transfer corotron made of an electric wire. When transferring using a corona transfer device, the transfer material must be in close contact with the photosensitive drum before being charged by the transfer corotron. Otherwise, the toner on the photosensitive drum will move in the space formed between the photosensitive drum and the transfer material, and the toner image transferred onto the transfer material will lose its sharpness. Usually, a guide shoe of an appropriate shape is provided at an appropriate position to obtain the above-mentioned close contact. Furthermore, once the transfer is completed, the transfer material must be quickly peeled off from the photosensitive drum so that it does not come into contact with the photosensitive drum again. Otherwise, the untransferred toner remaining on the photosensitive drum will adhere to the transfer material, resulting in a printed image with overlap or staining the transfer material. After peeling off, the transfer surface of the transfer material must not come into contact with anything until it enters the fixing device. Furthermore, at the moment when the transfer material is sandwiched between the opposing fixing roller and pressure roller of the fixing device, the leading edge of the transfer material must be flat so that both ends of the transfer material are simultaneously caught by the fixing device. If the leading edge of the transfer material is not flat, wrinkles or jams may occur in the transfer material.

FIG. 5 shows a conventional corona transfer device in a printing apparatus in which the transfer material is conveyed in the horizontal direction. The transfer material 16 sent out from a feeding device (not shown) passes through the entry log guide 8 and reaches the registration rollers 5.

The transfer material 16 that has been temporarily stopped by the registration roller 5 is transferred to the transfer guide 9 at a certain timing according to the electrophotographic conditions inside the machine body.
, and eventually reaches the photosensitive drum O. At this time, the transfer guide shaft 9 is configured so that the tangent to the photosensitive drum 0 and the transfer material 16 form an appropriate angle at the contact point between the photosensitive drum O and the transfer material 16. Furthermore, transfer material 1
When the transfer material 6 is conveyed, the transfer material 16 is gradually bent about the transfer roller 12 arranged as a fulcrum so that the tangent line shared with the photosensitive drum 0 is almost parallel to the tangent line that contacts the photosensitive drum O and the fixing roller 4. The transfer material 16 is pressed against the photosensitive drum 0 by the reaction force caused by the straining of the transfer material 16, and when the transfer material 16 passes between the transfer corotron 7 and the photosensitive drum 0, the transfer material 16 and the photosensitive drum 0 are in complete contact with each other. .

At this time, the transfer material 16 is strongly pressed against the transfer roller 12, but by making the transfer roller 12 rotatable or driving it by another drive device, the transfer material 16 can be pressed against the transfer roller 12.
6, thereby preventing various problems caused by poor conveyance. When the leading edge of the transfer material 16 passes between the transfer corotron 7 and the photosensitive drum 0, the transfer material 16 is strained and gradually peeled off from the photosensitive drum O due to its own weight. The position at which the transfer material 16 peels off from the photosensitive drum 0 changes depending on various conditions. For example, when the transfer material 16 is soft or when printing a pattern with a small drawing area, when the transfer material 16 is hard or when printing a pattern with a large drawing area, The position where the transfer material 16 is peeled off from the photosensitive drum 0 is on the downstream side in the rotational direction of the photosensitive drum 0, compared to when printing. In addition, in order to ensure that the transfer material 16 is peeled off from the photosensitive drum O, the transfer material 16 is
A peeling unit 6 for removing electric charge from the photosensitive drum O is installed next to the transfer corotron and at the rear in the direction of movement of the transfer material 16, and a peeling claw 15 for mechanically peeling off the transfer material 16 adhering to the photosensitive drum O is attached to the photosensitive drum 0. Transfer onto photosensitive drum 0 It is installed between the photosensitive drum 0 of the corotron and the Kunona unit. The transfer material 16 peeled off from the photosensitive drum 0 is guided to the fixing device 4 by the fixing guide shutter 10, fixed, and discharged to the outside. In addition, in order to stabilize the behavior of the transfer material 16 on the fixing guide shoe 14, a transfer material adsorption device 17 using static electricity or vacuum adsorption is installed on the fixing guide shoe 1.
It is attached to the back of 4.

[Problem to be Solved by the Invention 1] However, in the above-mentioned transfer device, the peeling claw 15
This causes scratches on the photosensitive drum O, significantly shortening the life of the photosensitive drum O. In addition, the peeling device uses a static elimination brush and a static elimination needle that can be used for a wide variety of transfer materials and a wide range of environmental conditions. Electrical settings are extremely difficult and often cause transfer failures, short circuits with the transfer corotron, resulting in distorted printed images and sources of electrical noise.

Furthermore, since the transfer material 16 is lifted by the electrostatic force of the photosensitive drum O, it is necessary to ensure a large space between the fixing guide shutter 14 and the cleaner unit 3. Further, due to the balance between the upward force of the photosensitive drum 0 acting on the transfer material 16 and the downward force of the transfer material 16's own weight, the transfer material 16 swells up and down, causing the transfer corotron and the photosensitive drum 0 to undulate.
This disturbs the adhesion conditions of the transfer material 16 between the parts. In addition, since the leading edge of the transfer material 16 is only along the fixing guide shaft 14 due to its own weight, the leading edge of the transfer material 16 cannot be kept flat, which may cause the transfer material 16 to bend or wrinkle in the fixing device 4. .

[Means for Solving the Problems] In order to solve the above-mentioned problems of the prior art, the present invention comprises a shield member having an opening facing the photosensitive drum, and a discharge wire disposed inside the shield member. a transfer corotron, a guide chute that guides a transfer material between the transfer corotron and the photosensitive drum, and a rotatable guide chute that is pivoted in parallel to the rotation axis of the photosensitive drum at the leading end of the guide chute in the direction in which the transfer material advances. , or a transfer entrance roller driven by another device, in which a tangent line between the transfer entrance roller and the photosensitive drum is in a rotational direction of the photosensitive drum with respect to a tangent line between the photosensitive drum and the fixing roller. In the transfer device, the fixing roller is arranged so as to have an angle in the upstream direction.

[Example] FIG. 1 shows an example of the present invention. The example of Fig. 1 is shown in Fig. 5.
This will be explained in comparison with the conventional example shown in the figure. FIG. 1 shows the conventional example shown in FIG. 5, in which the entry log guide 8 registration roller 5 transfer guide shoot 9 transfer entry roller 12 transfer corotron 7 peeling unit 6 is placed on the upstream side in the rotational direction of the photosensitive drum 0 with the center of the photosensitive drum 0 as the center. A tangent line 113 that touches the transfer roller 112 and the photosensitive drum 100 and a tangent line 11 that touches the photosensitive drum 100 and the fixing roller 104
This is a transfer device configured such that 4 and 4 are at an angle of 20 degrees. By configuring the transfer device in this way, the transfer material 1
16 is bent to a greater extent, and the force generated by the straining of the transfer material 116 to separate it from the photosensitive drum 100 is increased, so that more reliable separation is realized compared to the conventional example. Further, the transfer material 116 that has completed the transfer is sent out downward from the tangent line 110 that contacts the photosensitive drum 100 and the fixing roller 104, and the traveling path of the transfer material 116 and the cleaner unit 103
Even if the peeling claw l5 shown in FIG. 5 is removed, the transfer surface of the transfer material 116 will not come into contact with the cleaner unit 103 and stain the printed surface. Furthermore, the transfer material 116 is moved to the fixing guide housing 11.
4, the transfer material 116 is fed in the direction in which it is strongly pressed against the fixing roller 104, so that the zigzag at the leading edge of the transfer material 116 can be corrected and flattened before being sent to the fixing roller 104. Transfer material 11
It is possible to suppress the occurrence of folding of the end portion of the transfer material 116 and wrinkles of the transfer material 116 caused by the zigzag of the tip of the transfer material 116. Furthermore, since a force is constantly acting on the transfer material 116 to press it against the fixing guide shaft 114, as in the conventional example, an upward pulling force due to the electrostatic force of the photosensitive drum 100 and a downward force due to the own weight of the transfer material 116 are applied. Stable fixing performance can be obtained without causing the transfer material 116 to undulate up and down due to a change in the magnitude of the force, thereby disturbing the conditions of close contact of the transfer material 116 between the photosensitive drum lOO and the transfer corotron 107.

FIG. 2 shows an example in which the present invention is implemented in a printing device in which a transfer material is conveyed from above to below. In a printing device in which the transfer materials 16, 116 are conveyed horizontally, as in the conventional example shown in FIG. 5 and the embodiment shown in FIG.
The transfer materials 16 and 116 were peeled off from the photosensitive drums 0 and 100 due to the restoring force caused by sawing and the weight of the transfer materials 16 and 116, but in this embodiment, the weight of the transfer material 216 is
16 toward the photosensitive drum 200. In this embodiment as well, the angle formed by the contact 213 between the transfer roller 212 and the photosensitive drum 200 and the tangent 2lO between the photosensitive drum 200 and the fixing roller 204 is defined as "the strain of the transfer material 216>the weight of the transfer material 216+the photosensitive drum 200".
By configuring the device so as to have an electrostatic adsorption force of 1, it is possible to obtain the same effect as the embodiment described using FIG. 1.

[Effects of the Invention] In the transfer device of the present invention, by configuring the tangent line between the transfer roller and the photosensitive drum to have an angle in the upstream direction of the rotational direction of the photosensitive drum with respect to the tangent line that contacts the photosensitive drum and the fixing roller, the transfer material This ensures that the transfer material is peeled off from the photosensitive drum, and the transfer surface of the transfer material can be transported to the fixing device without touching other parts of the printing device, reducing stains on the printing surface. By pressing the leading edge of the transfer material against the fixing guide shroud and keeping the leading edge of the transfer material flat while conveying it to the fixing device, it is possible to obtain printing without bending or wrinkles on the transfer material. Further, the structure of the printing device is simplified since the peeling claw and the transfer material suction device can be omitted.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an embodiment of a printing device in which a transfer material is conveyed horizontally. FIG. 2 is a diagram of an embodiment of a printing device in which a transfer material is conveyed from above to below. The third figure is a diagram of a conventional example of a printing device in which a transfer material is conveyed horizontally. 0°1. 3. 4. 6. 7. 10. 13. 14. 100, 200 101, 201 103, 203 104, 204 106, 206 107, 207 110.210 113, 213 114, 214 Photosensitive drum Exposure unit Cleaner unit Fuser Peeling unit Transfer Corotron Tangent Tangent Fixing Guide Above Figure 2

Claims (1)

[Claims] a transfer corotron consisting of a shield member opening facing the photosensitive drum and a discharge wire disposed inside the shield member; a guide chute for guiding a transfer material between the transfer corotron and the photosensitive drum; In a transfer device comprising a transfer entrance roller which is supported in parallel to the rotation axis of the photosensitive drum at the leading end of a guide chute in the direction in which the transfer material advances and is rotatably driven or driven by another drive device. , the fixing entrance roller is arranged such that a tangent line that contacts the transfer entrance roller and the photosensitive drum is at an angle in an upstream direction in a rotational direction of the photosensitive drum with respect to a tangent line that contacts the photosensitive drum and the fixing roller. transfer device.