JPH04114175A - Image forming device - Google Patents

Abstract

PURPOSE:To maintain satisfactory cleaning performance with the lapse of time by forming a toner pattern having a certain length in the carrying direction and almost over the entire width of an image carrier at the time of copying of the nonpassing sheets. CONSTITUTION:The length of a belt-like photosensitive body 9 for use in a copying machine is slightly longer than the length of an A3-size sheet. The size of the photosensitive body 9 is such that three A3-size image formation areas 30 are arrayed in this length without riding on the joint 9a of the photosensitive body 9. At the time of copying of the nonpassing sheet, a toner attachment part 31 is formed in the area which is (l) in width from the front edge 30a of each image formation area 30. Charges remain in this toner attachment part 31 by turning off an eraser 13 during the passing of the part of the photoconductive body through the action area of an eraser 13. By carrying out development in a developing device 15, toner is attached to the part and the toner pattern is formed. Thus, since the charged amounts (Q/M) of the carrier and toner of the developer in a cleaner, and toner concentration (TC) are always constant, the satisfactory cleaning performance can be maintained over the lapse of time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus having a magnetic brush cleaning device.

Conventional technology In image forming apparatuses that use electrophotography, such as electrophotographic copying machines and electrostatic printers, toner images formed on an image carrier such as a photoreceptor through an electrophotographic process are fed to the image carrier from a paper feeding section. The image is transferred to the fed transfer paper, fixed, and recorded.

After the transfer, the toner remaining on the image carrier is cleaned by a cleaning device, and the image carrier is neutralized and prepared for the next image formation.

One type of this cleaning device is a magnetic brush cleaning device.

FIG. 1 is a diagram showing an overall schematic configuration of a copying machine as an example of an image forming apparatus having a magnetic brush cleaning device.

In the figure, 1.2.3 is a paper feed tray, 4 is a document tray, 5 is an automatic document feeder, 6 is a contact glass, 7 is an illumination lamp, and 8 is an imaging lens. Reference numeral 9 denotes a belt-shaped photoreceptor, and around it, in the order of circumferential movement indicated by the arrow, a charger 10, an exposure section 11, a surface electrometer 12, an eraser 13 . Filming removal means 14. A developing device 15, a transfer/separation charger 16, and a cleaning device 17 are arranged. 18 is a fixing device, and 19 is a paper discharge tray.

The document fed onto the contact glass 6 by the automatic document feeder 5 is illuminated all over at the same time by the illumination lamp 7, and the reflected light is focused by the imaging lens 8 onto the belt-shaped photoreceptor 9 at the exposure section 11. An electrostatic latent image is formed on the photoreceptor 9. The electrostatic latent image is developed into a toner image by the developing device 15, transferred to a transfer paper fed from one of the paper feed trays 1, 2, or 3 by the action of a transfer charger, and separated from the photoreceptor by a separation charger. The transferred transfer paper is fixed by the fixing device 18 and discharged onto the paper discharge tray 19.

On the other hand, the toner i remaining on the photoreceptor after transfer is cleaned by the cleaning device 17. This device employs a magnetic brush cleaning device as a cleaning device. This cleaning device will be explained with reference to FIG.

Since the toner remaining on the photoreceptor 9 has uneven polarity,
First, the pre-cleaning charger 24 makes the polarity of the toner constant, and the carrier ears formed around the magnetic brush roller 21 remove the toner on the photoreceptor.

Further, the toner transferred onto the magnetic brush roller is transferred onto the scavenge roller 22 and scraped off by the blade 23.
The toner is collected by the coil 26 into a waste toner bottle (not shown).

By the way, in an image forming apparatus using an electrophotographic method,
Checking after factory assembly, photoconductor inspection by service personnel,
In order to check, confirm, and change machine operations such as when replacing developer, an operation called non-paper-passing copying is performed, in which the process equipment operates in the same way as when copying without passing transfer paper. During paper copying, all the potential on the photoreceptor has been eliminated by the eraser (numeral 13 in FIG. 1), so even if the developing device 15 operates, toner does not adhere to the photoreceptor, and therefore the cleaning device 17 There is no input toner. If this state continues, the agent (carrier and toner) in the cleaning device will be removed as shown in Figure 3.
The charge amount (hereinafter referred to as Q/M) and the toner concentration (hereinafter referred to as TC) are reduced, resulting in toner scattering, poor cleaning, and reverse adhesion of toner.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the conventional image forming apparatus having a magnetic brush cleaning device, the present invention provides a system in which the Q/M and TC of the agent in the cleaning device are always stable even during non-sheet copying. An object of the present invention is to provide an image forming apparatus having a magnetic brush cleaning device that can maintain good cleaning properties over time.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention is characterized in that a toner pattern having a certain length in the conveying direction is formed over approximately the entire width of the image carrier during non-paper-passing copying.

Raw-1 As described above, in the present invention, a toner pattern having a certain length in the conveyance direction is formed over almost the entire width of the image carrier during non-paper-passing copying.

In paperless copying, the toner pattern is not transferred to the transfer paper, but is transported to a position in contact with the magnetic brush cleaning device, where it adheres to the ears of the carrier on the magnetic brush roller of the magnetic brush cleaning device and enters the cleaning device. The Q/M and TC of the input agent in the device can be maintained at appropriate values, and good leaning properties can be maintained over time.

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 4 is a diagram showing the arrangement of toner adhering portions formed on the photoreceptor during non-sheet copying when the present invention is applied to the copying machine shown in FIG. 1. As shown in FIG. The belt-shaped photoreceptor 9 used in this copying machine has a width slightly longer than the length of an A3 size sheet.

There are three A3 size image forming areas 3o so as not to overlap the seam 9a. During non-paper copying, each image forming area 30
The toner adhering portion 31 is located within a certain length ρ from the tip 30a of the
is formed.

The toner adhering portion 31 is a part of the photoconductor that is used by the eraser 13.
By turning off the eraser 13 while the toner passes through the action range, an electric charge remains in this portion, and by developing it with the developing device 15, toner adheres to that portion and is formed.

FIG. 5 is a flowchart showing the flow of operation in the non-paper-passing copy mode to which the present invention is applied.

When the print button is pressed, the transfer paper is not passed and the exposure lamp remains off (in case of paper non-passing copy mode), and the eraser is activated while the part corresponding to the toner adhesion area 31 passes as described above. Each image forming process unit performs the same operation as in the normal copy mode except that the lighting timing is changed so that it is turned off.

The paper non-passing mode is canceled by pressing the stop button.

Effects As described above, according to the present invention, toner is input to the cleaning device over almost the entire width of the photoconductor even during non-paper copying, the Q/M and TC of the agent in the cleaning device are always stable, and the toner is stable over time. It is possible to maintain good leaning properties over a period of time. In the present invention, the simple control of changing the lighting timing of the eraser is sufficient, so there is almost no increase in the size or cost of the device.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the general structure of an example of an electrophotographic copying machine having a magnetic brush cleaning device, FIG. 2 is a cross-sectional view showing the structure of the cleaning device, and FIG. 3 is a conventional non-sheet copying machine. FIG. 4 is a curve diagram showing changes in the charge amount of the agent in the magnetic brush cleaning device and the toner concentration with respect to the cumulative number of non-passing copies when one method is implemented. The layout diagram and FIG. 5 are flowcharts showing the flow of operations in the non-paper-passing copy mode according to the present invention. 9...Photoreceptor (image carrier) 13...Eraser 15...Developing device 17...Magnetic brush cleaning device 30...Image forming area 31...Toner adhesion section 2, 4' Agent Patent attorney Takehisa Ito, /+F;';,・＼ノに 1 i 3rd figure Kanotsu] 2nd Bee 111 (K Tomaritsu 4th figure)

Claims (1)

[Claims] In an image forming apparatus equipped with a magnetic brush cleaning device that removes toner remaining on the image carrier after transfer using a magnetic brush, during non-paper copying performed to check machine operation, etc., the image carrier is coated over approximately the entire width of the image carrier. An image forming apparatus characterized by forming a toner pattern having a certain length in a conveyance direction.