JP2003237982A - Electrophotographic unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an influence of deflection in a fixing plate caused by fastening in attaching, and an influence of vibration during printing. <P>SOLUTION: This electrophotographic unit has an arm having an arm ratio in a long hand and a short hand using a fulcrum as a boundary, and having a reflecting face in a long hand side, a roller shaft held by the arm and serving as a rotary shaft of a paper thickness roller, an arm shaft serving as a rotary shaft of the arm, a spring for pulling the arm, and a paper sheet thickness detector having an optical displacement sensor provided to be opposed to the reflecting face of the arm. In the unit, a driving roller is provided to be opposed to the paper thickness roller, and to be rotated while synchronized with conveyance of paper sheet. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus having a paper thickness detecting device.

[0002]

2. Description of the Related Art A general electrophotographic apparatus forms an electrostatic latent image on a uniformly charged photoconductor and develops the toner by a developing device to visualize the electrostatic latent image.

The toner image on the photoconductor is transferred onto a sheet by a transfer device and is fixed on the sheet by being heated and pressed by a fixing device. Further, the untransferred toner on the photoconductor is cleaned by a cleaning machine. Repeat the above process,
Print continuously.

In the above process, the sheet that has passed through the fixing device is curled to one side by being heated and pressed by the fixing device. A curl removing device called a decurler corrects and corrects this. Usually, the paper that needs to be decurled is limited to thin paper of less than 150 μm where the curl amount becomes remarkable, and the curl removal is not necessary for thick paper of 150 μm or more where the curl amount is small.

FIG. 2 is a diagram showing a conventional paper thickness detecting device. In FIG. 2, 1 is an arm, 1a is a reflecting surface, 2 is a paper thickness roller, 3 is a roller shaft, 4 is an arm shaft,
Reference numeral 5 is a spring, 6 is an optical displacement sensor, 7 is a pressure roller, 8 is a conveying roller, and 9 is a fixed plate. As shown in Figure 2,
When the fixing plate 9 is used at the portion facing the paper thickness roller 2, there is a problem that the detection cannot be performed correctly due to the influence of the bending of the fixing plate 9 due to the fastening at the time of attachment and the influence of vibration during printing.

Conventionally, in order to set whether or not to convey the paper to the curl removing device after printing, an operator arbitrarily selects ON / OFF by a button operation at a stage before printing, thereby issuing a command to the machine. Set to feed the paper to the curl removal device after feeding and fixing. In this case, if the operator forgets to press the button or makes a mistake, the thin paper that needs decurling will accumulate in the stacker without being decurled, or conversely, the thick paper that does not need decurling will curl. There is a problem in that it is conveyed to the removing device and causes troubles such as paper jam and curl to the opposite side.

In recent years, the types and sizes of paper used in printers have become widespread, and the curl amount of paper at the time of printing changes variously depending on the paper condition such as temperature and humidity. Therefore, the decurler ON / OF cannot be limited because it is not always necessary to remove the curl with a fixed thickness.
It is required that the thickness of the sheet for switching the F be adjusted for each customer.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent the influence of flexure of a fixing plate due to the fastening at the time of mounting and the influence of vibration during printing.

Further, according to the present invention, it is necessary to remove the curl.
An object is to automatically discriminate between a paper of less than 0 μm and a paper of 150 μm or more that does not require curl removal, and eliminate a setting operation for conveying the paper to the curl removing device after fixing by an operator.

Further, the present invention makes it possible to adjust the distance between the drive roller and the paper thickness roller so that the decurler can be turned ON / OF.
The purpose is to make the thickness of the paper for switching F variable.

[0011]

DISCLOSURE OF THE INVENTION The present invention has an arm ratio of a length and a width with a fulcrum as a boundary, and an arm having a reflecting surface at the length, and a paper rotatably held by the arm. A thick roller, a roller shaft that is held by the arm and serves as a rotation axis of the paper thickness roller, an arm shaft that serves as a rotation axis of the arm, a spring that pulls the arm, and a facing surface of the arm. In the electrophotographic apparatus having the sheet thickness detecting device having the optical displacement sensor described above, a drive roller facing the sheet thickness roller and rotating in synchronization with conveyance of the sheet is provided.

Further, a gap is provided between the drive roller and the paper thickness roller, and when a paper having a certain thickness or more comes into contact with the paper thickness roller, the arm is rotated and the reflecting surface of the arm is moved. It is characterized in that the thickness of the paper is discriminated by doing so.

Further, the distance between the drive roller and the paper thickness roller can be adjusted by moving the stopper screw.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a sheet thickness detecting device according to an embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 2 are designated by the same reference numerals. As shown in FIG. 1, a space t is provided between the paper thickness roller 2 and the drive roller 10 which is installed so as to face the paper thickness roller 2, and the drive roller 10 rotates in the direction in which the paper is conveyed. The paper is sent out in the carrying direction by the carrying roller 8 and the pressure roller 7 arranged at the front and rear. When the distance t between the paper thickness roller 2 and the drive roller 10 is less than 150 μm, the paper is the paper thickness roller 2
And passes through the interval t without contacting. But 150
When the paper is more than μm, the paper contacts the paper thickness roller 2,
The arm 1 rotates about the arm shaft 4. At the same time, the reflecting surface 1a on the arm 1 on the longitudinal side moves, and the optical displacement sensor 6 detects it to detect the paper thickness.

Further, by moving the stopper screw 11, the distance between the drive roller 10 and the paper thickness roller 2 can be adjusted, and the thickness of the paper for switching ON / OFF of the decurler can be freely changed.

[0016]

According to the present invention, a drive roller that rotates in synchronism with the conveyance of a sheet is provided in a portion facing the sheet thickness roller, so that the influence of the bending of the fixing plate due to the fastening at the time of mounting, The influence of vibration during printing can be prevented.

Further, according to the present invention, a sheet of less than 150 μm that needs decurling and a sheet of 150 that does not require decurling.
It is possible to automatically discriminate a sheet having a size of μm or more and eliminate the setting operation for conveying the sheet to the curl removing device after fixing by the operator.

Further, according to the present invention, by adjusting the distance between the drive roller and the paper thickness roller, the decurler O
The thickness of the paper for switching N / OFF can be made variable.

[Brief description of drawings]

FIG. 1 is a diagram showing a sheet thickness detection device according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a conventional paper thickness detection device.

[Explanation of symbols]

1 ... Arm, 1a ... Reflective surface, 2 ... Paper thickness roller, 3 ... Roller shaft, 4 ... Arm shaft, 5 ... Spring, 6 ... Optical displacement sensor, 7 ... Pressure roller, 8 ... Conveying roller, 9 ... Fixed plate 10 ... Drive roller, 11 ... Stopper screw.

Claims (3)

[Claims] 1. An arm having an arm ratio between a longitudinal direction and a lateral direction with a fulcrum as a boundary and having a reflecting surface at a longitudinal portion, a paper thickness roller rotatably held by the arm, and a paper thickness roller held by the arm. And a roller shaft that serves as the rotation axis of the paper thickness roller,
An electrophotographic apparatus having an arm shaft that is a rotation axis of the arm, a spring that pulls the arm, and a paper thickness detection device that has an optical displacement sensor that is provided so as to face the reflection surface of the arm. An electrophotographic apparatus comprising a sheet thickness detecting device having a drive roller facing the roller and rotating in synchronization with the conveyance of the sheet. 2. A space is provided between the drive roller and the paper thickness roller, and when a paper having a certain thickness or more comes into contact with the paper thickness roller, the arm is rotated and the reflecting surface of the arm moves. 2. The electrophotographic apparatus according to claim 1, further comprising a sheet thickness detection device that determines the thickness of the sheet by doing so. 3. The thickness of the paper for switching ON / OFF of the decurler is made variable by adjusting the distance between the drive roller and the paper thickness roller. Electrophotographic device.