JP2591613B2 - Transfer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for holding a transfer material, bringing the transfer material into contact with an image carrier, and forming a developed image (toner image) on the image carrier into the transfer material. More particularly, the present invention relates to a transfer device for transferring images to a plurality of transfer media, and more particularly to a grip device for gripping or releasing a transfer material, and a plurality of transfer devices formed on an image carrier by gripping and transferring the transfer material with the grip devices. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device which can be suitably used for a color image forming apparatus of a type in which a developed image of a color is superimposed and transferred on the same transfer material to obtain a color image.

2. Description of the Related Art Conventionally, various types of electrophotographic image forming apparatuses, particularly apparatuses for obtaining a color image by superimposing and transferring a plurality of developed images on the same transfer material, such as an electrophotographic color copying machine, have been proposed. A latent image is formed on a photosensitive drum for each color separation, and the latent image is formed into a developed image by a rotary developing device having a plurality of developing units, and the developed image is formed on a transfer material carried by a transfer device. There is a method of obtaining a multicolor image by sequentially transferring the images.

In order to obtain a high-quality color image by such a method, it is necessary to prevent the transfer material from being displaced when three to four types of developed images are sequentially transferred onto one transfer material. is there. Therefore, in the conventional color image forming apparatus described above, the transfer material must be repeatedly conveyed to the exact same position in synchronization with the rotation of the photosensitive drum until one color image forming process is completed. As a method for carrying out the synchronous transfer of the transfer material to the photosensitive drum, a transfer device provided with a transfer material support (transfer drum) usually formed in a cylindrical shape is used. In such a transfer apparatus using a transfer drum, a gripper for holding the leading end of the transfer material along the generatrix of the transfer drum is provided to wind and hold the transfer material around the transfer drum, and further controls opening and closing of the gripper. An actuating member, such as a cam, is movably disposed in an actuated position and a non-actuated position.

Also, in order to cooperate with the transfer device, a conveyance guide around the transfer drum, such as a conveyance guide for guiding the transfer material to the transfer drum, and a separation guide for separating the transfer material from the transfer drum and conveying the transfer material to the next step. The means is arranged to be selectively movable between an active position and an inactive position.

Each of the above members or means performs a series of operations in accordance with the movement of the transfer material. The operation will be briefly described as follows.

1) When the transfer material is fed, the transport guide moves, and the leading end of the transport guide approaches the vicinity of the transfer drum.

2) At the same time, the gripper opening / closing operation control member operates to open the gripper at the transfer material gripping position.

3) The leading end of the transfer material is gripped by the gripper, and the remaining portion of the transfer material is wound and held around the transfer drum.

4) Next, when the multiple transfer of the transfer material is completed and the transfer material is separated from the transfer drum, the separation guide operates and the leading end approaches the vicinity of the transfer drum.

5) At the same time, the gripper opening / closing operating member operates to open the gripper at the transfer material separating position.

6) The transfer material is separated from the transfer drum and transferred to the next step.

The series of operations 1) to 6) are performed for the transfer of the transfer material, and the operations of gripping and separating the transfer material are performed before the first transfer and after the last transfer in the multiple transfer.

Usually, a transfer device using such a transfer drum is
Detecting means for detecting that the transfer material is wound and held around the transfer drum is provided. this is,
For example, when the transfer material is not gripped by the transfer drum (hereinafter referred to as “grip jam”) due to a paper feed failure or a conveyance failure, the toner image on the photosensitive drum is transferred to the transfer drum, and the transfer drum becomes dirty. This is to prevent As a detecting means, an optical sensor 107 shown in FIG. 7 is generally used so as not to disturb the toner image transferred on the transfer material. Further, the conventional transfer drum 100 has a configuration in which a transparent or translucent sheet or a mesh-like sheet 105 is adhered to a frame 104 including a mounting portion of a gripper 103, and a transfer material P held on the sheet 105 is formed. Has determined whether or not the transfer material P is gripped by the transfer drum 100 by interrupting the optical path of the sensor 107.

(Problems to be Solved by the Invention) However, as in such a conventional example, it is determined whether or not a grip jam occurs based on the presence or absence of a transfer material on a sheet.
In the gripper portion that actually grips the transfer material, it is not possible to detect how the transfer material is gripped. That is, as shown in FIG. 5, the transfer material does not contact the gripper,
Even when the gripper is displaced from the regular gripping position by the distance a, it cannot be distinguished from the case where the normal gripper is performed. In such a case, since the gripping force of the gripper is small, the transfer material falls from the transfer drum during the transfer and the image formation is interrupted in the middle, or at the same time, the toner image is transferred to the transfer drum with the fall of the transfer material. Dirty transfer drum sheet,
Alternatively, when the transfer material after the transfer of the toner image is separated from the transfer drum due to the shift of the grip position, the transfer material may be caught by a member such as a separation guide, resulting in paper jam (hereinafter, referred to as separation jam). There is a problem that unfixed toner is scattered in the apparatus.

Therefore, the present invention has been made to solve the above-mentioned problems of the conventional example, and an object thereof is to detect whether or not a transfer material is gripped at a regular position on a transfer material support. To provide a transfer device capable of performing the transfer.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, there is provided a transfer material support for supporting and transporting a transfer material, wherein the transfer is performed from an image carrier to the transfer material support. A transfer material support for transferring an image to a supported transfer material, grip means provided on the transfer material support, and having a plurality of grip portions for gripping a front end of the transfer material; and a grip formed on the transfer material support. Detecting means for detecting the presence or absence of a transfer material on the transfer material support through an opening, wherein the opening is provided between the grip portions and the transfer in the opening is provided. It is configured such that the leading end position in the moving direction of the material support is matched with the leading end position of the transfer material abutted against the grip portion in a normal state.

(Operation) In the present invention having the above-described configuration, the presence or absence of the transfer material on the transfer material support is detected by the detection unit through the opening formed between the grip portions of the transfer material support. And, the leading end position in the moving direction of the transfer material support in the opening is set so as to coincide with the leading end position of the transfer material gripped by the grip means, and when the transfer material is gripped, the opening is covered by the transfer material. Thus, it is possible to detect whether or not the transfer material is gripped at a regular position on the transfer material support without affecting the grip state of the grip portion.

(Embodiment) The present invention will be described below based on the illustrated embodiment. FIG. 2 shows a multicolor image forming apparatus to which an embodiment of the present invention is applied, using an electrophotographic method. In FIG. 1, reference numeral 1 denotes a rotary developing device, which includes a yellow developing device 1Y, a magenta developing device 1M, a cyan developing device 1C, and a black developing device 1BK in a rotating body. Reference numeral 2 denotes an external developer (toner) supply device, 2Y denotes a yellow hopper, 2M denotes a magenta hopper, 2C denotes a cyan hopper, and 2BK denotes a black hopper.

First, the sequence of the entire color printer will be briefly described by taking the case of the full color mode as an example. Reference numeral 3 denotes a photosensitive (body) drum as an image carrier that rotates in the direction of the arrow shown in the figure. The photosensitive member on the drum is uniformly charged by the charger 4. Next, image exposure is performed by a laser beam E modulated by a yellow image signal of a document (not shown), an electrostatic latent image is formed on the photosensitive drum 3, and thereafter, the electrostatic latent image is previously set at a developing position. Development is performed by the yellow developing device 1Y.

On the other hand, the transfer (use) paper that has progressed via the paper feed guide 5a, the paper feed roller 6, and the paper feed guide 5b is held by a gripper 7 as a grip means in synchronization with a predetermined timing, and And the opposite electrode electrostatically winds it around a transfer drum 9 as a transfer material support. The transfer drum 9 rotates in the direction indicated by the arrow in synchronization with the photosensitive drum 3, and the developed image developed by the yellow developing device Y is transferred by the transfer charger 10 in the transfer section. The transfer drum 9 continues to rotate and prepares for the transfer of the next color, for example, magenta.

On the other hand, the photosensitive drum 3 is discharged by the charger 11, cleaned by the cleaning member 12, charged again by the charger 4, and receives the above exposure by the next magenta image signal. During this time, the developing device 1 rotates, and the magenta developing device 1M is fixed at a predetermined developing position and performs a predetermined magenta development. Subsequently, the above-described steps are performed on cyan and black, respectively.
When the transfer of the colors is completed, the four-color visual image on the transfer paper is discharged by the chargers 13 and 14 to release the gripper 7, and is separated from the transfer drum 9 by the separation claw 15 and fixed by the transport belt 16. The full-color print sequence is sent to the unit 17 and a required full-color print image is formed.

FIG. 1 is a perspective view showing a schematic configuration of a transfer device according to the present embodiment. In FIG. 1, reference numeral 9 denotes a cylindrical transfer drum as a transfer material support, which is in contact with a photosensitive drum 3 as an image carrier. And endlessly move to support and transfer the transfer material P. In this embodiment, the transfer drum 9 has a cylindrical shape. However, the transfer drum 9 may have a belt shape. A gripper 7 is provided on the transfer drum 9 in parallel with the axial direction of the photosensitive drum 3 and grips the transfer material P.

Reference numerals 91 and 92 denote frames of the transfer drum 9, 94 denotes a support member that supports the gripper 7 and connects the frames 91 and 92, 95 denotes a sheet that is stretched around the peripheral surface of the transfer drum 9 and supports the transfer material P,
96 is an opening formed in the support member 94 of the transfer drum 9,
The leading end position 96a in the rotation direction of the transfer drum 9 is set to be substantially equal to the leading end position of the transfer material P gripped by the gripper 7. An optical sensor 97 detects the presence or absence of the transfer material P on the transfer drum 9 through the opening 96.

In the above configuration, the transfer material P fed by a normal operation is gripped with its leading end abutting against the gripper 7 on the transfer drum 9 as shown in FIGS. At this time, since the transfer paper P covers the opening 96 of the support member 94 and cuts off the optical axis of the optical sensor 97, it is detected that the transfer material P is gripped at a regular position on the transfer drum 9. You. On the other hand, when the transfer material P is held at a position shifted by a from the normal position where it comes into contact with the gripper 7 as shown in FIG.
Is left uncovered by the transfer material P by the width a, so that the optical sensor 97 can detect transmitted light and detect that the transfer material P is not gripped normally. Can be stopped to prevent the transfer material P from dropping or the inside of the apparatus such as toner due to the occurrence of separation jam, and to reduce the load of the work of removing the transfer material P.

Further, as another operation, even when the transfer material P is skewed and hits the gripper 7 by gripping only one side of the transfer material P as shown in FIG. 6, a part of the opening 96 is covered by the transfer material P. Since the transfer material P is left untouched, it can be detected that the transfer material P is not gripped normally.

Also, in order to improve the transferability, even when a transparent transfer material having a narrow width guide paper stuck only at the leading end is used, the optical sensor 97 is used similarly to other opaque transfer materials. Grip jam can be detected, and there is no need to use special detection means to use a transparent transfer material.

Note that the detection means in the present invention is not limited to the above-described optical sensor, and detection means of another method such as a contact type or a magnetic sensor may be partially restricted depending on the material of the transfer material. Although there is, it can be fully utilized.

(Effect of the Invention) The transfer device according to the present invention has the above configuration and operation, and determines whether or not the transfer material is gripped at a regular position on the transfer material support, which affects the gripping state of the grip portion. Without causing a drop in the transfer material after gripping, resulting in contamination of the transfer material support, or prevention of toner scattering inside the machine due to separation jam. Play.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of a transfer device according to the present invention, FIG. 2 is a configuration diagram showing a multicolor image forming apparatus to which the embodiment is applied, and FIG. FIG. 4 is a cross-sectional view showing a detection position of a sensor in FIG. 3, and FIG. 5 is a main part plan view showing a state where the transfer material is gripped with a shift of a distance a. , FIG. 6 is a plan view of a main part showing a state of being skewed and gripped,
FIG. 7 is a sectional view showing a detection position of a conventional sensor. EXPLANATION OF SYMBOLS 3... Photosensitive drum (image carrier) 7... Gripper (grip means) 9... Transfer drum (transfer material support) 96. means)

Claims (1)

(57) [Claims] 1. A transfer material support for supporting and transporting a transfer material, wherein the transfer material support transfers an image from an image carrier to a transfer material supported by the transfer material support. Gripping means provided on the body, comprising a plurality of grip portions for gripping the leading end of the transfer material; detecting means for detecting the presence or absence of the transfer material on the transfer material support through an opening formed in the transfer material support; Wherein the opening is provided between the grip and the grip, and the leading end position of the transfer material support in the moving direction in the opening is abutted against the grip in a normal state. A transfer device characterized in that the transfer device coincides with a leading end position of a transfer material.