JPH03107182A - Fixing device - Google Patents

Abstract

PURPOSE:To straighten out the falling bristles of a brush in fashion advantageous to space by switching the energizing force of a pressure roller to weaker energizing force tilting the bristles of the brush in a rotating direction and to powerful energizing force tilting the bristles in an opposite direction to the rotating direction. CONSTITUTION:Since the pressure roller 2 switched to the powerful energizing force rotates at a speed similar to the velocity of a heat roller 1, the bristles of the brush 22 fall in the opposite direction to the rotating direction of the pressure roller 2. In this state, a copy sheet 7 is fed between the rotating rollers 1 and 2, and held and carried, during which a toner image is heated, pressed and fixed onto the copy sheet 7. After a prescribed length of time has passed since the copy sheet 7 passed by a fixing device, a control part 43 drives a stepping motor 45 in a prescribed time. Consequently, a disk 48 turns half-way around, and a locking part 49 stops in the lower-most position, whereby the energizing force of a tension coil spring 36 weakens to switch the abutting pressure of the pressure roller 2 to a weaker one. Since the pressure roller 2 follows the heat roller 1 and makes a turn while slipping, the bristles of the brush 22 fall down in the rotating direction of the pressure roller 2 to straighten out the falling.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a fixing device used in a copying machine or the like, which grips and conveys copy paper on which a toner image has been formed from both sides of the copy paper, and fixes the toner image. The present invention relates to a fixing device that fixes images by applying heat and pressure.

[Prior Art] A conventional fixing device includes a heating roller having a heating means, a pressure roller having a brush that rotates as a result of the heating roller and has a large number of fibers protruding from the circumference, and a circumferential portion of the pressure roller. A rotary correcting member is known which is rotatably disposed facing the brush and raises the brush (Japanese Unexamined Patent Publication No. 63
-66584, etc.). This fixing device uses a pressure roller with a brush to enable fixing at ultra-low pressure and secure a wide nip width, and also uses a rotating correction member to correct the fall of the brush tip.

[Problems to be Solved by the Invention] In the above-mentioned fixing device, a rotating correction member is provided to correct the tip of the brush, which increases costs and requires securing space. .

SUMMARY OF THE INVENTION Accordingly, a technical object of the present invention is to provide a fixing device that can correct the fall of a brush tip in an advantageous manner in terms of cost and space.

[Means for Solving the Problems] The fixing device of the present invention includes a heating roller and a circumferential portion that grips and conveys a copy paper on which a toner image has been formed from both sides thereof, and heats and presses the toner image to fix it. A fixing device including a pressure roller configured with a brush from which a large number of fibers protrude and rotates driven by the heating roller, includes a biasing means for biasing the pressure roller against the heating roller; An ear tipping control means that switches the force between two types of urging force: a weak urging force that causes the brush ears to fall in the direction of rotation, and a strong urging force that causes the brush ears to fall in a direction opposite to the rotational direction. It is.

[Function] The fixing device of the present invention is based on the inventor's discovery that when the pressure roller follows the heating roller, the direction of the fall of the brush varies depending on the contact pressure of the brush. That is, when the urging force of the urging means is set to a strong side, the pressure roller rotates at approximately the same peripheral speed as the heating roller, so the brush ears fall in the opposite direction to the rotational direction of the pressure roller. When the biasing force of the biasing unit is switched to a weaker side by the ear inclination control unit, the pressure roller causes a slip phenomenon and rotates at a peripheral speed slower than the heating roller, so that the brush ear does not touch the pressure roller. falls in the same direction as the direction of rotation. This corrects the fall of the brush.

[Example] Hereinafter, an example of the fixing device of the present invention in an electronic copying machine will be described.

As shown in FIG. 1, the fixing device of this embodiment has a heating roller 1, a pressure roller 2, a biasing means 3, and an ear fall control means 4 as main components.

The heating roller 1 holds and conveys the copy paper on which the toner image has been formed together with the pressure roller 2 from both sides thereof, and heats and melts the toner image to fix it on the copy paper. The heating roller 1 includes a cylindrical core metal 11 made of aluminum, a Teflon layer 12 covering the outer circumference of the core metal 11, and a heater 13 disposed inside the core metal 11. The overall diameter is 35 mm and the length is 320 mm. The heating roller 1 is supported by support plates (not shown) provided at both ends.
A drive motor (not shown) is connected to the rotating shaft via a drive gear (not shown).

The pressure roller 2, together with the heating roller 1, holds and conveys the copy paper on which the toner image has been formed. This pressure roller 2 has a cylindrical core metal 21 made of aluminum.
and a brush 22 with a large number of fibers protruding from the circumference of a core bar 21, with an overall outer diameter of 3Q mm and a length of 32 mm.
It is formed with a size of 0 mm. The brush 22 is formed by electrostatic flocking using heat-resistant nylon fibers (Conex) with a thickness of 10 denier and a length of 2 mm at a density of 6000 pieces/cm2. Both ends of the support plate 31 are rotatably supported via bearings (not shown) in a pair of swing support plates 31 which are disposed in parallel with the support plate 1 and extend from the rear.

In this state (when paper is not passing), the tip of the brush 22 is in contact with the outer peripheral surface of the heating roller 1, and the contact pressure is 2 kQ/32
It is set to 0mm. As a result, the pressure roller 2 rotates as a result of the rotation of the heating roller 1.

The biasing means 3 biases the pressure roller 2 against the heating roller 1, and is composed of a pair of swing support plates 31 and a tension coil spring 35. The swing support plate 31 has a substantially rectangular shape having a concave bearing portion 32 at the center of its upper side, and both ends of the pressure roller 2 are supported by the bearing portions 32, respectively.

The swing support plate 31 is attached to the main body frame (not shown) of the copying machine.
One end of the tension coil spring 35 is supported by a swing shaft 33 provided at the spring 35, and a lower end of the tension coil spring 35 is locked by a locking portion 34 provided at the other end. This results in
The swing support plate 31 is swingable about the swing shaft 33 and is always urged upward by a tension coil spring 35, and the pressure roller 2, which is supported by the bearing portion 32, moves between the heating port and the roller. It is energized to 1. In addition, the tension coil spring 3
The upper end of 5 is locked to a locking portion 49 of a disc 48, which will be described later.

The ear inclination control means 4 corrects the inclination of the ear of the brush 22 by switching the urging force of the urging means 3 to a weaker urging force than usual. The ear fall control means 4 in this embodiment is as follows:
A sensor 41 that detects copy paper entering the fixing section, a switching section 42 that switches the urging force of the urging means 3, and a control section 43.
It is made up of. The sensor 41 is a light reflection type sensor, and is provided above the guide plate 50 that conveys the copy paper to the fixing section. This sensor 41 is connected to the control section 43 and detects when the leading edge of the copy paper being conveyed passes and sends a detection signal to the control section 43. As shown in FIG. 2, the biasing force switching unit 42 includes a stepping motor 45 and a rotating shaft 47 that rotates through gears 46a and 46b driven by the stepping motor 45.
and a pair of discs 48 coaxially fixed to both ends of a rotating shaft 47. Four locking portions are provided on the outer peripheral edge of each disc 48, and the upper end of the tension coil spring 35 is locked to the locking portions 49. Each disk 48 is
When the locking portion 49 is at the lowermost position, it is the stopping position when no paper is being passed. The control unit 43 is built into the microcomputer of the copying machine, and as shown in FIG.
The stepping motor 45 is driven for a predetermined period of time based on the detection signal. That is, the control unit 43 drives the stepping motor 45 so that each disc 48 makes a half turn, stops once, and then makes another half turn after a predetermined period of time has elapsed. As a result, the locking portion 49 provided on each disc 48 moves from the lowermost position to the uppermost position, once stops, and then moves to the lowermost position and stops again, thereby tightening the tension coil spring 35. It is now possible to switch forces.

The fixing device of this embodiment is constructed as described above, and its operation will be explained next.

When the electronic copying machine is switched on, when the heating roller 1 is rotated by the drive motor, the pressure roller 2 is driven to rotate accordingly. At this time, the contact pressure of the pressure roller 2 is set to 2 kcl/320 mm, which is a weak urging force, and the pressure roller 2 rotates at a peripheral speed lower than that of the heating roller 1 while causing a slip phenomenon. Therefore, the ears of the brush 22 fall in the same direction as the rotational direction of the pressure roller 2, as shown in FIG. In this state, the copy paper 7 onto which the toner image has been transferred in the previous process is guided by the guide plate 50 and conveyed. Then, as shown in FIG.
The sensor 41 detects that the leading edge of the copy paper 7 passes just before it reaches the fixing device, and sends the detection signal to the control unit 43.
When the signal is transmitted, the control unit 43 drives the stepping motor 45 for a predetermined period of time. As a result, the disc 48 is connected to the gear 46.
a1b and the rotating shaft 47, and stops with the locking part 49 at the uppermost position. Accordingly, the biasing force of the tension coil spring 35 becomes stronger, and the swing support plate 31 swings around the swing shaft 33. As a result, the swing support plate 3
The pressure roller 2 bearing the roller 1 is biased by the heating roller 1, and the pressure roller 2 is switched to the side where the biasing force is strong so that the contact pressure is 6 kg/320 mm. Then, the pressure roller 2 becomes the heating roller 1.
Since the brush 22 rotates at approximately the same circumferential speed as shown in FIG. In this state, the copy paper 7 is fed between the rotating rollers 1 and 2, held and conveyed, thereby heating and pressurizing the toner image and fixing it on the copy paper 7.

Then, after the copy paper 7 passes through the fixing device and a predetermined period of time has elapsed,
The control unit 43 drives the stepping motor 45 again for a predetermined period of time. As a result, the disc 48 rotates half a rotation and the locking portion 4
9 is stopped at the lowest position, the biasing force of the tension coil spring 35 is weakened, and the contact pressure of the pressure roller 2 is switched to the weaker biasing force side of 2 kC1/320 mm. In this state, since the pressure roller 2 rotates following the heating roller 1 while causing a slip phenomenon, the ears of the brush 22 fall in the direction of rotation of the pressure roller 2, and the fall of the ears is corrected.

Thereafter, when the copy paper 7 is conveyed to the fixing device, the same operation is repeated, and as shown in FIG.
/320mm. Therefore, the brush 22 that has fallen in the opposite direction to the p-turning direction of the pressure roller 2 during paper passing is corrected by falling in the same direction as the rotational direction of the pressure roller 2 when the paper is not passing V.

As described above, in the fixing device of this embodiment, since the tip of the brush 22 is corrected by changing the biasing force of the urging means 3 by the tip tip small control means 4, the rotating correction member is provided. It is advantageous in reducing cost and space compared to the conventional method. In addition, it is possible to prevent the nip from becoming narrow due to the tip of the brush 22 falling, thereby preventing the occurrence of fixing failure, and the life of the brush 22 can be extended.

In this embodiment, when the copy paper 7 is not passing through the fixing device, the biasing force can be reduced to the weak side and the brush 22
However, it is possible to press the fallen ears before or after the copying operation of the copying machine starts, or to set a ground for correcting the fallen ears and adjust the fallen ears as necessary. It is also possible to correct this.

[Effects of the Invention] The fixing device of the present invention includes a biasing means that biases the pressure roller against the heating roller, and a weak biasing force that causes the brush ears to fall in the direction of rotation, and a weak biasing force that causes the brush ears to fall in the rotating direction. Since the brush has an ear inclination control means that switches between two types of urging force, a strong urging force that causes the ear to fall in a direction opposite to the direction of rotation, it is possible to correct the inclination of the brush ear in an advantageous manner in terms of cost and space.

[Brief explanation of drawings]

1 to 7 relate to embodiments of the present invention, in which FIG. 1 is a side view of the fixing device, FIG. 2 is a perspective view of the ear fall control means, and FIG.
4 is a side view of the fixing device showing the state during paper feeding; FIGS. 5 and 6 are explanatory diagrams without showing the direction in which the brush tip falls; and FIG. is a diagram showing changes in biasing force. 1... Heating roller 2... Pressure roller 3...
Biasing means 4... Ear fall control means 22... Brush Fig. 3

Claims (1)

[Claims] (1) A heating roller that grips and conveys a copy paper on which a toner image has been formed from both sides thereof, heats and presses the toner image to fix it, and a brush that has many fibers protruding from its circumference. A fixing device including a pressure roller that is rotated by a roller, and a biasing unit that biases the pressure roller against the heating roller, and a weak biasing force that causes the brush ears to fall in the direction of rotation. A fixing device comprising: a brush tip fall control means that switches between two types of urging force: a strong force and a strong urging force that causes the brush ears to fall in a direction opposite to the direction of rotation.