JPS58126561A - Pressure fixing device - Google Patents

Abstract

PURPOSE:To develop the adjustable press contacting force that adapts itself to the varying sizes of a toner image carrying body with a simple device, by bringing a pair of rolls into press contact with each other with the specified force by a spring and the force adjustable with an electromagnetic plunger. CONSTITUTION:A toner image carrying body 16 is passed through between a pair of upper and lower rolls 2, 3 which are held in press contact with each other, whereby toner images are fixed thereon. The spring force of a spring 9 which is adjustable with a nut 11, and the electromagnetic force by an iron piece 12 and a coil 13 mounted to the extending part 4' of an upper housing 4 are exerted to the rolls 2, 3 fulcruming at a pivotal pin 1. On the basis of the specified force by the spring 9, the adjustable electromagnetic force is used as an adnusting component. Since these two forces are added and are applied upon both rolls 2, 3, the device is made smaller than the devices with which the entire force is made adjustable. According to the varying sizes in the width and thickness of the toner image carrying body, the press contact force of the rolls is freely adjustable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for fixing a toner image by passing a toner image carrier such as copy paper between a pair of rolls under pressure, that is, a pressure fixing apparatus. Since this pressure fixing device applies strong pressure to the toner on the toner image carrier and presses it onto the carrier, it must be able to apply a constant pressure to the toner.

By the way, a spring is usually used as a means for applying the pressure. This spring acts between each bearing of a pair of rolls,
Press both rolls together. Therefore, when the width of the toner image carrier passed between the rolls is wide, the pressure is lower than when it is narrow. Also.

Similar problems arise due to changes in the thickness of the toner image carrier. Furthermore, when a thick toner image carrier is passed through, a large roll driving force is required when the leading edge cuts between the two rolls, and when the trailing edge escapes from between the two rolls. Then, both rolls collide with dog energy.

Easy to damage its surface. These problems can be solved if the force applied between the two rolls can be appropriately controlled, but this cannot be done with a spring-based pressurizer.

The present invention is aimed at solving the above-mentioned problems, and is characterized in that in addition to the pressing force by the spring, electromagnetic force is applied and the force can be adjusted.

Next, the present invention will be explained by means of illustrated embodiments.

Reference numeral 2.3 denotes a pair of upper and lower rolls, which are rotatably supported by the upper roll housing 4 and the lower roll housing 5 via ball bearings 6.7, respectively. Both roll housings 4° 5Fi are pivotally supported to each other by a pivot pin 1.

On the opposite side of this pivot point, there is a bolt 8 that loosely passes through both roll housings 4.5, and a spring 9 is fitted into it. The spring 9 is compressed by providing a washer 10 between the upper surface of the upper roll housing 4 and a nut 11 screwed into the port 8, and tightening the nut 11. The upper roll housing 4 has an extension 4', at the tip of which an iron piece 12 of an electromagnetic plunger is attached to a pin 1.
4 is the pivot point. Reference numeral 16 denotes a coil of an electromagnetic plunger, which is fixed to a frame (not shown) together with the lower roll housing 5.

It is connected to the control power supply 17. In addition, if the above-mentioned structure is one-car roll 2. This is about one end of B, but the other end has a similar structure.

The amount of deflection of the spring 9 can be adjusted by adjusting the degree of tightening of the nut 11, and the two rolls 2 and 3 are brought into pressure contact with each other by the force awaited by the spring 9. In addition, iron piece 12
The adjustable electromagnetic force acting on the extension 4' is increased by the leverage of the extension 4'.

and added to the force exerted by the spring 9.

It acts between the cylindrical rolls 2 and 3. Therefore, the force by the spring 9 is used as a base, the electromagnetic force is used as an adjustment component, and the two forces are summed, and the adjustable force as a whole is generated by the tube roll 2,
It can be given for 3 hours.

As an example, if the minimum size of the paper 16 to be passed between the tube rolls 2 and 3 is an official postcard of 100 cm x 14 Btm and 220 μm thick, this is because the pressing force against it is the smallest.

This is provided only by the spring 9. That is, it does not pass through the coil 13 of the electromagnetic plunger. Ordinary plain paper is 70 to 95μ thick and 297μ wide, so it is about twice as large as a government postcard, and the pressure against it is,
It will be halved. Therefore, in response to a command from the copy size selection switch, the control power supply 17 is operated, and a corresponding current is caused to flow through the coil 13 of the magnetic plunger, thereby electromagnetically providing the above-mentioned insufficient force.

The above is an example of application in which the pressure is kept constant by controlling the pressing force according to the width of one sheet of paper 16, but the apparatus of the present invention can be used in other ways. For example, a sensor is provided to detect the position of the leading edge of the paper 16, and the electromagnetic force is not applied until the leading edge of the paper 16 is inserted between the rolls 2 and 3. As a result, 1 paper 16
Even if the roller has a small P value, its tip can easily cut between the two rolls 2.degree., and the driving force for one roll 2.degree. can be reduced. When the sensor detects that the paper 16 is inserted between the cylindrical rolls 2 and 3, electromagnetic force is applied from that stage to apply a predetermined pressing force to both rolls 2. Give to Party B. Further, when the rear end of one sheet 16 escapes from both rolls 2 and 3, the electromagnetic force is cut off immediately before that. As a result, the force with which the two rolls 2 and 3 collide can be reduced, and damage to the surface of the rolls can be prevented. By the way, the control as described in iiJ can also prevent the front and rear edges of the 91 paper 16 from becoming sharp due to excessive pressure.

FIG. 2 shows a second embodiment of the present invention. In this example, as an electromagnetic plunger.

A coil 16 wound around an iron core 12' is used.

A soft iron piece 4'' is fixed to the extension part 4' of the upper roll housing 4.The soft iron piece 4'' receives a suction force corresponding to the amount of passage through the coil 13, and the suction force is expanded by the lever action of the extension part 4'. This acts as an adjusting pressure force between the cylinder rolls 2 and 3.

As described above, the present invention provides a force for pressing a pair of rolls together by superimposing a constant force from a spring and an adjustable force from an electromagnetic plunger, so that the pressing force is applied. This solves the problems caused by the fact that the force is constant, and since the base force is applied by a spring, the entire force can be adjusted, and the device can be made smaller and simpler.

[Brief explanation of the drawing]

1 and 2 are side views of two embodiments of the present invention. 2...Top roll 6...Bottom 0-/l/4
″... Soft iron piece 9... Spring 12...
・Iron core 16...Electromagnetic plunger coil Applicant Ricoh Co., Ltd.

Claims (1)

[Claims] In order to press a pair of rolls together, there is a spring that applies a certain blade to their darkness, and their l'BlvC.
A pressure fixing device comprising an electromagnetic plunger that applies a freely adjustable force superimposed on the force.