JPH0776857B2 - Electrophotographic printer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic printing apparatus, and more particularly to an electrophotographic printing apparatus having a heat roller type fixing device.

[Conventional technology]

Generally, a printing apparatus using an electrophotographic printing method transfers toner developed on the surface of a photosensitive drum onto printing paper and fixes the toner on the paper by heat and pressure of a heat roller.

If the data sent from the data output device is interrupted, the paper will stop temporarily, and the toner will remain on the heat roller at the moment the pressure contact between the heat roller and backup roller is released, and heat will start when the next printing starts. An offset may occur in which the residual toner on the roller adheres to the paper.
Therefore, the first cleaning roller is provided to remove the residual toner on the heat roller, and the second cleaning roller is provided to remove the toner attached to the first cleaning roller.

The speed control of the heat roller will be described with reference to FIG.

While printing is stopped, it rotates at a speed 0.4 times the constant speed during printing. At this time, the backup roller has been released and the paper has not been sent. During this time, the heat roller is 1
It rotates and is cleaned once by the first cleaning roller.

[Problems to be Solved by the Invention]

However, in the above-described conventional example, the heat roller that is stopped is cleaned only once, and the residual toner on the heat roller is not sufficiently removed. Therefore, when the next printing is started, the heat roller on the heat roller is not removed. There has been a problem that an offset occurs in which the residual toner adheres to the printing paper.

[Object of the Invention]

It is an object of the present invention to provide an electrophotographic printing apparatus which can improve the disadvantages of the conventional example and can sufficiently remove the residual toner on the heat roller.

[Means for Solving the Problems]

In the present invention, the heat roller for fixing the toner on the developed continuous paper, the backup roller arranged in parallel on one side through the heat roller to press the continuous paper against the heat roller, and the other through the heat roller A first cleaning roller for cleaning the heat roller, which is arranged in parallel with the heat roller, a second cleaning roller for cleaning the first cleaning roller, which is arranged in parallel with the heat roller via the first cleaning roller, and a heat roller. The roller and the control means for controlling the rotation speeds of the first and second cleaning rollers are provided, and the control means for controlling the rotation speed of the heat roller during printing stop to increase the number of cleanings is provided. This aims to achieve the above-mentioned object.

[Action]

The developed continuous paper is forcibly fed by being sandwiched between a heat roller and a backup roller. And at the same time,
The heat on the heat roller and the pressure on the backup roller fix the toner on the continuous paper.

When printing is stopped and the pressure contact between the heat roller and the backup roller is released, residual toner is generated on the heat roller at this time.

While printing is stopped, the heat roller is rotated, the first cleaning roller removes the residual toner on the heat roller, and the second cleaning roller removes the residual toner transferred to the first cleaning roller.

Example of Invention

An embodiment of the present invention will be described below with reference to FIGS.

Generally, in an electrophotographic printing apparatus, an electrophotographic section 1 and a tractor section 3 that feeds and ejects a continuous printing paper 2 to and from the electrophotographic section 1 and a transferred sheet ejected from the electrophotographic section 1 are received. It is composed of a fixing unit 4 for fixing and a stacker unit 5 for storing printed sheets on which fixing is completed.

The electrophotographic section 1 includes a charger 7, an exposure device 8, a developing device 9, a transfer device 10, and a cleaner 11 in order below the immediate vicinity of the photosensitive drum 6 along the rotation direction of the photosensitive drum 6. Equipped.

The tractor unit 3 faces the transfer device 10 of the electrophotographic unit 1, feeds the continuous printing paper 2 between the photosensitive drum 6 and the transfer device 10, and the transfer device 10 completes the transfer. It is arranged at a position where continuous paper can be discharged.

In the fixing unit 4, a heat roller 12 and a backup roller 13 are arranged in pressure contact with each other with the transferred continuous paper sandwiched therebetween. Also, a backup roller via the heat roller 12.
A first cleaning roller 14 is arranged in parallel with the heat roller 12 on the opposite side to the heat roller 12. Further, a second cleaning roller 15 is provided in parallel with the first cleaning roller 14 in contact with the first cleaning roller 14 on the side opposite to the heat roller 12.

In the stacker unit 5, two pairs of feed rollers 16 are separately arranged in upper and lower two stages, and a stacker cradle 17 is arranged below them.

The operation of the electrophotographic printing apparatus configured as described above will be described with reference to FIGS. 1 to 3.

The surface of the photosensitive drum 6 is uniformly charged by corona discharge of the charger 7, and a point image of light corresponding to input data is line-scanned and exposed by the laser by the laser. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 6.

Next, the charged toner is attached to the surface of the photosensitive drum 6 and developed. The continuous paper 2 fed from the tractor unit 3 is brought into contact with the surface of the photosensitive drum 6, and the continuous paper is sandwiched to charge the paper from the opposite side of the photosensitive drum 6 with a polarity opposite to the charging polarity of the toner. Transfer by attracting to paper.
The continuous paper on which the transfer is completed is sent to the fixing unit 4 by the tractor unit 3. The continuous paper sent is the heat roller 12
Then, the transferred toner is fixed by the pressure between the backup roller 13 and the heat from the heat roller 12. At the same time, the heat roller 12 comes into contact with the first cleaning roller 14 to clean the residual toner, and at the same time, the first cleaning roller 14 moves to the second cleaning roller 15 at the same time.
Cleaning is done in contact with.

An example of the rotating state of the heat roller 12 and the backup roller 13 at this time is shown in FIG. Further, FIG. 3 shows the state of the rotation speed of the heat roller 12. As shown in FIG. 3, while printing is stopped, control is performed so that the printing roller rotates at a speed 1.5 times the predetermined speed during printing. At this time, the first cleaning roller 14 is controlled so as to clean the heat roller 12 three times.

The continuous paper, on which the toner on the continuous paper is fixed by the fixing unit 4 and printing is completed, folds the continuous paper sent to the stacker unit 5 by the feed roller 16 and stores it on the stacker tray 17.

As described above, according to this embodiment, when the printing is temporarily stopped and the pressure of the backup roller 13 is released, the heat roller 12
The toner remaining on the first cleaning roller 14 and the second cleaning roller 14
It can be carefully removed by the cleaning roller 15, and the offset of the residual toner adhering to the printing paper can be effectively prevented.

〔The invention's effect〕

Since the rotation speed of the heat roller when printing is stopped is increased to about 1.5 times that during printing, the residual toner remaining on the heat roller when the pressure contact between the heat roller and the backup roller is released when printing is temporarily stopped It is possible to provide an electrophotographic printing apparatus that can be sufficiently cleaned and does not cause offset at the start of the next printing.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention, and FIG.
FIG. 3 is a time chart showing the relationship between the heat roller and backup roller of the embodiment shown in FIG.
FIG. 4 is a time chart showing the control of the rotation speed of the heat roller of the embodiment in the figure, and FIG. 4 is a time chart showing the control of the rotation speed of the heat roller in the conventional example. 1 ... Electrophotographic part, 2 ... paper, 4 ... fixing part, 6 ...
Photosensitive drum, 12 ... Heat roller, 13 ... Backup roller, 14 ... First cleaning roller, 15 ... Second cleaning roller.

Claims (1)

[Claims] 1. A heat roller for fixing toner on a developed continuous paper, a backup roller arranged in parallel on one side through the heat roller to press the continuous paper against the heat roller, and a heat roller. A first cleaning roller for cleaning the heat roller, which is arranged in parallel on the other side, and a second cleaning roller for cleaning the first cleaning roller, which is arranged in parallel on the opposite side of the heat roller via the first cleaning roller. And a control means for controlling the rotation speeds of the heat roller and the first and second cleaning rollers, in the electrophotographic printing apparatus, the rotation speed of the heat roller when printing is stopped is 1.
An electrophotographic printing apparatus characterized by the above-mentioned control means for controlling so as to increase it by about 5 times.