JPS601626B2 - Fusing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device in an electrophotographic recording device or the like.

An electrostatic recording image created on a photoreceptor or a static latent image formed on electrostatic recording paper is developed with thermoplastic resin colored powder, etc., and when this is fixed directly or by transfer, a heated roller is pressed. At least melt the heat-fusible colored powder,
Methods for fusing and fixing to a support such as paper are well known. Recently, the above-mentioned electrophotographic method has been used to convert output information from electronic computers into visible images such as figures or characters.
2. Description of the Related Art Printer devices that print hard copies on continuous paper such as roll paper or folded paper are well known.

The present invention relates to a fixing device used in printer devices and the like to which such electrophotography is applied. Conventionally, various methods are known for fixing an unfixed powder image, that is, a toner image, in an electrophotographic recording apparatus.

Heating methods used to transfer thermal energy to the transfer material and the unfixed powder image formed on its surface can be broadly classified into infrared heating, hot plate heating, ribbon heater heating, etc. This is a heating method in which heat is supplied more or less through a poor heat conductor such as air between a heating element, a heating element, and a transfer material, resulting in very poor thermal efficiency and an increase in the size of the device. Therefore, in recent years, hot roller fixing, which has good thermal efficiency, high safety, and requires only four molds, has been frequently used.

In hot roller fixing, a pair of rollers are pressed against each other, and a support on which a powder image has been formed is passed between them, thereby permanently fixing the powder image on the support.

Heat roller fixing devices can be roughly divided into external heating methods that heat the fixing roller from the outside using heat conduction from a heating roller or heat radiation from a heater, and internal heating methods that heat the fixing roller by placing a heat source inside the fixing roller. It is well known that there are heating methods. In either case, when fixing a fixed powder image on continuous paper that has been continuously printed out, when it is passed between a pair of rollers in the same way as conventional cut paper, a control signal from the printer body is transmitted. Depending on how the instruction is issued, the fixing roller may stop while the fixed image is being held between the pair of rollers. If the fixing roller is attempted to be rotated again after stopping, the unfixed powder image will be disturbed by the rotation of the roller.

An object of the present invention is to prevent such image disturbance caused by the fixing roller.

The present invention has a continuous support on which a toner image is formed between a pair of fixing rollers, and fixes the continuous support from a state where the pair of fixing rollers is separated to a state where they are in pressure contact with each other. The fixing device is characterized in that it has means for moving the continuous support a predetermined length in a direction opposite to the advancing direction of the continuous support so that the part of the continuous support is located between the pair of fixing rollers.

The present invention will be explained below according to embodiments shown in the drawings.

FIG. 1 schematically explains an electrophotographic printer applied to the present invention, in which 1 is an electrophotographic photosensitive drum having a photoconductive insulating layer on its surface, 2 is a charger, and 3 is made of, for example, He-N
e-laser, 4 is a modulator that turns on and off the laser beam according to image signals, 5 is a rotating Mihoo (scanner) that scans by swinging the laser beam from side to side, and 6 is a lens that makes the spot a predetermined diameter. , 7 is a reflecting mirror, 8 is a developing device for developing the latent image expressed on the photosensitive drum with resin toner, -9
10 is a transfer device that transfers the developed image onto paper or the like; 10 is a cleaner that cleans the drum for reuse; 11
1 is a folded or roll-shaped continuous paper, 12 is a heat fixing unit that fuses the resin toner image to the paper, and 13 is a unit that sucks the image transferred to the continuous paper from the back side and attaches it to a flat plate, etc., and applies a brake to the paper. , a suction-type loading device that applies tension to the paper between it and the heat fixing unit 12; 14 is a suction floor that drives the loading device 13; and 11' is continuous paper that is discharged by a fake paper roller 21. FIG. 2 shows a heat fixing section 12, a load device 13,
This is a cross-sectional view showing the relationship of the paper ejection roller 21 in detail, when an external heating method is used.

In FIG. 2, a fixing roller 16 is connected to a drive source (not shown) and is disposed on the toner image side of the continuous paper 11. A heating roller 17 is provided with a heater 19 therein as a heat source, and is in constant contact with the fixing roller 16.

Reference numeral 18 denotes a pressure roller, and a heater 20 is disposed inside to promote heating of the fixing roller.

The pressure roller 18 moves to a position where it is pressed against the fixing roller 16 (shown by a broken line) and a position where it is separated from the fixing roller 16 (shown by a solid line). The continuous paper 11 is moved by the suction box 1 due to the tension T caused by the suction box 13 as a load device and the tension T2 (=T,) caused by the pseudo paper roller 21.
Appropriate tension is maintained between the sheet discharge roller 21 and the sheet discharge roller 21, and when no fixing is performed, the pressure bonding loft 18 and the like are in the state shown by the solid line in FIG. When fixing the toner image formed on the continuous paper 16, first stop the rotation of the fixing roller 16, and then press the pressure roller 18 against the fixing roller 161 to fix the continuous paper 11 located between the two rows. To fix the toner image by applying pressure, the fixing roller 16 is rotated to move the continuous paper forward. In addition, if you want to stop fixing after this, stop the rotation of the fixing roller 16, and
While being kept under pressure between the two rows 16 and 18, the pressure bonding rows 18 is separated from the fixing roller 16 to release the pressure and release the continuous paper 11.

If the fixing roller 16 is rotated after that, the fixing roller 16 will be rotated by the heating roller 17 during the waiting period.
The surface can be maintained at a uniform temperature. In other words, since the continuous paper is released after the fixing roller is stopped, the inertia of the paper may cause the unfixed portion to pass past the fixing roller and move forward, or the image may become blurred.
It is possible to prevent phenomena such as paper being ejected with the fixation intact.
Incidentally, instead of the heating roller 12, the outer periphery of the fixing loaf 12 may be heated by an ejaculatory lamp provided outside the fixing loaf 16. FIG. 3 shows an embodiment using an internal heating method, in which a heater 31 is installed as a heat source inside a fixing roller 30 connected to a drive source. The pressure roller 32 is movable between a position where the fixing roller 3 is compressed and a position separated from the fixing roller 30, and a heater may be provided inside to assist in heating the fixing roller. . The continuous paper 11 is given an appropriate tension between a suction box 13 and a paper discharge roller 21. When fixing the continuous paper 11, first press the pressure roller 32 with the continuous paper 11 in between.
is pressed against the fixing roller 30'. At this time, the fixing roller is stopped. When using internal heating,
It is no longer necessary to rotate the fixing roller 30 after releasing the pressure between the pair of rollers.

This is because an internally heated fixing roller always provides uniform heating. However, in any of the above embodiments, when starting fixing again after finishing fixing, the fixing rollers 16 and 30 and the pressure rollers 18 and 32
There may be unfixed images between them.

If the fixing roller is rotated in this state, the unfixed image will be disturbed by this rotation. Therefore, the fixing is completed and the fixed image is separated from the fixing roller and transferred to the pressure roller 1.
When the continuous paper is stopped in a state where it is located on the paper 8, if the tension T2 of the paper ejection roller is made relatively smaller among the tension T2 caused by the suction box 13 and the tension T2 caused by the gE paper roller 21, When pressing the pressure roller against the fixing roller for restarting, the continuous paper 11' is pulled back a little so that the fixed image area does not come into contact with the fixing roller, and the already fixed part of the continuous paper is pressed against both rollers 30,
It will be located between 32.

As a result, when fixing is performed again, it is possible to prevent the unfixed image portion from coming into contact with the fixing roller, and it is possible to prevent the image from being blurred by the fixing roller. That is,
In FIG. 3, the tension T caused by the suction box 13 that applies back tension to the continuous paper 11 and the tension T2 caused by the discharge roller 21 that discharges the continuous paper are set to be equal,
When fixing an unfixed image on the continuous paper 11 while moving the continuous paper 11 forward between the fixing roller 30 and the pressure roller 32 and stopping the rotation of the pair of rollers to stop the fixing, the fixing occurs. is being carried out.

After this, when the pressure roller 32 is separated from the fixing loaf 30 and the continuous paper 11 is released, the length a of the continuous paper between the suction box 13 and the paper scale roller 21, indicated by the broken line, and the length b of the continuous paper, indicated by the solid line. The continuous paper 11 is different, so the continuous paper sag between them, but the paper discharge roller 21, which constantly rotates and tries to eject the continuous paper 11 while slipping with an appropriate force between the continuous paper 11 and the continuous paper 11, After the continuous paper has advanced by a corresponding length and the slack has been removed, the forward motion is stopped by the suction box 13. As a result, an unfixed image portion on the continuous paper is located between the fixing roller 30 and the pressure roller 32. When fixing is performed again after this, the tension T2 is set to be relatively smaller than the tension T until the separated rollers 30 and 32 come into pressure contact, and the conveyor belt 35 is moved in the direction of the arrow. A pair of rollers 30 are driven in reverse and the part that has already been fixed is
, 32, the continuous paper 11 is moved in the direction opposite to the forward direction, and then both rollers are brought into pressure contact. When both rollers 30 and 32 are brought into pressure contact, the tension T and the tension L are set equal, and the driving of the belt 35 is stopped.

Note that the belt 35 surrounds the suction box 13 and has many holes provided on its surface. By operating in this way, the unfixed image area does not come into contact with the fixing rollers, so not only when the pressure roller is pressed against the stopped fixing roller, but even when the fixing roller is rotating, the pressure roller cannot be pressed. There is no fear that the image will be disturbed even if the image is pressed. In any case, in the present invention, the continuous support is moved in a predetermined direction opposite to the normal advancing direction so that an unfixed image does not exist between the fixing rollers before the fixing roller rotates in pressure contact with the continuous support. Since the length is moved, a stable image without image disturbance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an electrophotographic printer to which the present invention is applied, FIG. 2 is a sectional configuration diagram of a heat fixing section, and FIG. 3 is a sectional diagram showing another embodiment of the heat fixing section. 16...Fixed loaf, 17...Heating loaf, 18...Crimping loaf, 21...Mock paper loaf younger brother diagram chrysanthemum 2 figure 3

Claims (1)

[Scope of Claims] 1. In a fixing device that heats and fixes a toner image on a support by passing a continuous support on which a toner image has been formed between a pair of fixing rollers, the pair of fixing rollers are separated and the When the above-mentioned continuous support is between the rollers, the fixed portion of the continuous support is between the pair of fixing rollers between the pair of fixing rollers being separated and being pressed into contact with each other. A fixing device comprising means for moving the continuous support a predetermined length in a direction opposite to the advancing direction of the continuous support so as to move the continuous support by a predetermined length. 2. The moving means has a conveying means for conveying the continuous support to the pair of fixing rollers, and the conveying means is reversely driven to convey the continuous support in the opposite direction. Fixing device as described in section.