JPH04195179A - Fixing device for electrophotographic copying device - Google Patents

Abstract

PURPOSE:To apply a pressure on a fixing roller only in the case of being needed and to prevent a paper and a fixing device from being pressurized more than needed by utilizing ultrasonic vibration in order to press fixing a powder image. CONSTITUTION:The above device is provided with the fixing roller 10, a pressing roller 20 which is arranged opposite to the fixing roller 10, a rotary driving mechanism 30 for rotating the fixing roller 10 and the pressing roller 20 and ultrasonic wave generators 40 and 41 which are fixed on the fixing roller 10. And the paper 50 on which the powder image is placed is transferred between the fixing roller 10 and the pressing roller 20, and then, the ultrasonic wave is generated by the ultrasonic wave generators 40 and 41 so as to fix the powder image on the paper 50. The generation and stop of the ultrasonic wave can be electrically controlled in the ultrasonic generators 40 and 41 in such a way, so that the ultrasonic wave can be generated in accordance with image information only in the case of being needed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device used in an electrophotographic apparatus such as an electrophotographic copying machine or an electrophotographic printer, and particularly relates to a fixing device that performs fixing by pressure. .

[Prior Art] This type of conventional constant W device presses a fixing roller and a pressure roller against each other with a constant pressure using a spring or the like.

[Problems to be Solved by the Invention] In the conventional fixing device described above, the fixing roller and the pressure roller are always pressed against each other with a constant pressure, so that the portion of the paper where there is no powder image to be fixed is Even when the fixing roller is applied, the pressing force is always applied (on both sides).In addition, this pressing force needs to be a large pressure, which has the disadvantage of increasing the size of the fixing device and increasing cost. However, applying a large amount of pressure promotes uneven pressure, which often causes wrinkles in the paper.

[Means for Solving the Problems] A fixed W device of the present invention includes a fixing roller, a pressure roller disposed opposite to the fixing roller, and a rotational drive mechanism that rotates the fixing roller and the pressure roller. , an ultrasonic generator fixed to either the fixing roller or the pressure roller.

A sheet of paper carrying a powder image is fed between a fixing roller and a pressure roller, and an ultrasonic generator generates ultrasonic waves to fix the powder image on the sheet. Since the ultrasonic generator can electrically control the generation and stop of ultrasonic waves, it is possible to generate ultrasonic waves only when necessary according to image information.

In this respect, the present invention is advantageous compared to the spring method, which always applies a constant large force to the fixing roller.

The purpose of the present invention can be achieved by fixing just one ultrasonic generator somewhere on the fixing roller or pressure roller, but if possible, it is preferable to fix one ultrasonic generator on each end of the roller. is preferred.

A frequency in the range of 50 kHz to 200 kHz is effective for fixing a powder image, and it is preferable that the ultrasonic generator of the present invention also generates a frequency within this range.

As the ultrasonic generator, various types of vibrators such as magnetostrictive vibrators and electrostrictive vibrators can be used.

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

The drawing is a perspective view of an embodiment of the invention. The main components of this fixing device are a fixing roller 10, a pressure roller 20 facing the fixing roller 10, a motor 30 that applies rotational force to the pressure roller 20, and two ultrasonic generators that apply ultrasonic vibrations to the fixing roller 10. 40.41.

The shaft 12 of the fuser roller 10 has two bearings 14.1.
5, it is rotatably supported. The bearing 14.15 is inserted and fixed into a bearing support 16.17.

The shaft 22 of the pressure roller 20 is rotatably attached to a side plate (not shown) of the fixing device. The surface of the pressure roller 20 is pressed against the surface of the fixing roller 10.

A gear 36 is fixed to the shaft 22 of the pressure roller 20, and this gear 36 meshes with the gear 34.

The gear 34 is fixed to the output shaft 32 of the motor 30.

In this embodiment, the "rotary drive mechanism" in the configuration of the present invention includes a motor 30, a gear 34 . It is composed of a gear 36.

Ultrasonic generator 40 includes a laminated actuator 42 . The laminated actuator 42 has a structure in which many thin plates are stacked, and an electromagnetic coil (not shown) is wound around this to form a magnetostrictive vibrator. An amplification horn 44 is fixed to the lower surface of the laminated actuator 42 . This amplification horn 44
has the shape of a stepped horn, and its lower surface is fixed to the bearing support 16. A damper 46 is fixed to the upper surface of the laminated actuator 42, and the upper surface of the damper 46 has a constant
! ! It is fixed to the frame of the device (not shown). Due to the function of this damper 46, the ultrasonic vibration of the laminated actuator 42 is hardly transmitted to the frame of the constant W device. On the other hand, due to the function of the amplification horn 44, the ultrasonic vibrations of the laminated actuator 42 are efficiently transmitted to the bearing support base 16.

The other ultrasonic generator 41 also has the same structure as the ultrasonic generator 40, including a laminated actuator 43 and an amplification horn 4.
5. It consists of a damper 47. Note that the laminated actuator 4
The electric circuit for driving the 2.43 is well known and is not shown here.

Next, the operation of this embodiment will be explained. The rotation of the mold 30 causes the pressure roller 20 to rotate in the direction of the arrow 24.

Since the fixing row 510 is pressed against the pressure roller 20, it rotates in the direction of the arrow 18 due to frictional force. Paper 50 carrying powder image 52 is fed in the direction of arrow 54 and inserted between fixing roller 10 and pressure roller 20 .

The drive circuits of the laminated actuators 42, 43 are energized according to the image information. Therefore, powder drawing on paper
52 reaches the fuser roller 10, the lamination actuators 42, 43 vibrate ultrasonically. This vibration is transmitted to the fixing roller 10 via the amplifying horn 44.45, the bearing supports 16, 17, and the bearings 14.15, and the fixing roller 10 vibrates in the direction of the arrow 48. Fixing roller 1
0 and the pressure roller 20, this vibrational energy is transmitted to the powder image 52 on the paper 50. This vibration energy becomes impact energy or *friction energy, and is finally converted into thermal energy, and the powder image 52 is transferred to the paper 5.
Fixed to 0.

When the area 56 where no powder image exists enters the fixing port 10, the drive circuits of the laminated actuators 42, 43 are not energized. However, even at this time, the fixing roller 510 and the pressure roller 20 are in a state where they are lightly pressed against each other, so there is no problem in feeding the paper 50.

As a means for recognizing when the powder image has entered the fixing roller, the position may be stored in memory at the time the powder image is developed on the paper, or it may be possible to recognize when the powder image has entered the fixing roller. A reflective optical sensor may be installed to detect the powder image.

[Effects of the Invention] As explained above, the present invention uses ultrasonic vibration to pressure-fix powder images, so pressure can be applied to the fixing roller only when necessary according to image information. This has the effect of not requiring excessive force to be applied to the paper or the fixing device.

[Brief explanation of the drawing]

The drawing is a perspective view of an embodiment of the invention. 10...Fixing roller 20... Pressure roller 30...Motor 40.41...Ultrasonic generator Patent applicant: NEC Corporation Nippon Electric Data Equipment Co., Ltd. Representative patent attorney Susumu Uchihara

Claims (1)

[Scope of Claims] A fixing roller; a pressure roller disposed opposite to the fixing roller; a rotational drive mechanism that rotates the fixing roller and the pressure roller; and a rotation drive mechanism fixed to either the fixing roller or the pressure roller. A fixing device for an electrophotographic apparatus, comprising: an ultrasonic generator;