JPH02226179A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent a pressure roll from slipping and a medium from wrinkling when passed by providing a coating part which improve the separation from toner at the center part of a heat roll and using a pressure roll which has a press-contacting part longer than the coating part. CONSTITUTION:The fixing device has a heat roll 1 which heats and fuses the toner image on the medium and the pressure roll which is pressed against the heat roll 1 by a compression coil spring 4 and the coating part which has a low friction coefficient and improves the separation is provided at the center part of the heat roll 1. The pressure roll is longer than the coating part 5 and pressed against the heat roll 1 by the compression coil spring 4. Therefore, when the fixing device is driven, the part of the heat roll 1 which has a large friction coefficient except the coating part 5 contacts the pressure roll 2, which has high follow-up performance. Consequently, the pressure roll is prevented from slipping and the medium is prevented from wrinkling, etc., in the case of passing.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to electrophotographic printers.

[Conventional technology]

Conventionally, this type of fixing device, as shown in FIG. 2, includes a heat roll 1 and a pressure roll 2 that heat and press the toner image, a compression coil spring 4 that presses the pressure roll 2 against the heat roll 1, and a compression coil spring 4 that presses the pressure roll 2 against the heat roll 1. A coating part 5 is provided in the center of the heat roll 1 to improve the releasability of the toner. It becomes.

The pressure roll was in contact with the inside of this coating section 5.

[Problem to be solved by the invention]

In the conventional fixing device described above, since the pressure roll 2 is in contact with the coating portion 5 provided on the heat roll 1, the followability of the pressure roll 2 with respect to the heat roll 1, which is the drive side of the fixing device, is poor. This has the disadvantage that the pressure roll 2 may slip and the medium may wrinkle when passed through the medium.

An object of the present invention is to provide a fixing device that solves the above problems.

[Means to solve the problem]

To achieve the above object, the present invention provides a fixing device having a heat roll that heats and melts a toner image on a medium and a pressure roll that simultaneously presses the toner melted by the heat rolls onto the medium. A pressure roll is used in which a coating part is provided on the part to improve the release property from the toner, and the pressure roll has a pressure contact part that is longer than the coating part.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, the present invention includes a heat roll 1 driven by a gear 3 to heat and melt the toner image on a medium, and a pressure roll 2 that is pressed against the heat roll 1 by a compression coil spring 4.

A coating part 5 with a low friction coefficient that improves mold release properties is provided at the center of the heat roll 1, and the pressure roll is longer than the coating part 5 and is pressed against the heat roll 1 by a compression coil spring 4. .

Therefore, when the fixing device is driven, the pressure roll 2 comes into contact with a portion of the heat roll 1 having a large friction coefficient other than the coating portion 5, and the pressure roll 2 has high followability.

〔Effect of the invention〕

As explained above, in the present invention, since the pressure roll has a contact portion with the heat roll that is longer than the coated portion of the heat roll, the pressure roll comes into contact with a portion of the heat roll other than the coated portion that has a large friction coefficient, and the pressure roll has a high followability and is effective in preventing slippage of the pressure roll and wrinkles of the medium when it is passed through the medium.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. 1...Heat roll 2...Pressure roll 5...Coating part of heat roll Patent applicant
Niigata NEC Co., Ltd.

Claims (1)

[Claims] (1) In a fixing device that has a heat roll that heats and melts the toner image on the medium and a pressure roll that simultaneously presses the toner melted by the heat roll onto the medium, there is a part in the center of the heat roll that separates the toner from the toner. A fixing device characterized in that a pressure roll is provided with a coating portion that improves shapeability and has a pressure contact portion that is longer than the coating portion.