JPS62169188A - Method for cleaning photosensitive body of electrophotographic device using magnetic brush - Google Patents

Abstract

PURPOSE:To quickly execute sufficient cleaning, by providing a cleaning mode period before restarting operations after jammed paper is removed and reducing the running speed of a photosensitive body during this period. CONSTITUTION:When a paper jam takes place at some position of the passage of transfer paper 30 from a paper feeding section 26 to a carrying device 29, the jam is detected and informed to a CPU and this copying machine is stopped. When the jammed paper is removed and the copying machine is restarted thereafter, a cleaning mode is set prior to the normal operation and the running speed of a photosensitive body 6 and discharging current of a PCC are reduced. Then a cleaning device 8 rotates a sleeve at a normal speed and cleans the sleeve. The period of the cleaning mode is previously set so that all of the untransferred remaining toner can pass the cleaning device 8 by the end of the period. When the cleaning mode period terminates, the copying machine is again set to the copying mode and starts the next copying cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a magnetic brush type cleaning method for a photoreceptor of an electrophotographic apparatus such as an electrophotographic copying machine, facsimile machine, or printer.

(Prior Art) In an electrophotographic apparatus, an electrostatic latent image formed on a photoreceptor is developed with toner, and then transferred and fixed onto transfer paper to obtain a copy or recording paper. The transfer foil photoreceptor is used repeatedly after residual toner is removed. A cleaning device removes this residual toner, and one of them is a cleaning device using a magnetic brush, which is the object of the present invention.

This magnetic brush type cleaning device has a similar configuration to a magnetic brush type developing device, and while the former electrostatically attracts the 1-toner remaining on the photoreceptor using a magnetic carrier, In the latter method, toner electrostatically attracted to a magnetic carrier is electrostatically attracted to an electrostatic latent image on a photoreceptor. Therefore, in a magnetic brush type cleaning device, an erase lamp is irradiated onto the photoreceptor of the transfer foil to eliminate the static "?!J,'fJ image, and a pre-cleaning charger (hereinafter abbreviated as PCC) is activated. Then, charge the remaining 1-ner with a magnetic brush of opposite polarity.

By the way, when a jam occurs in the paper feeding section, the toner that should originally be transferred to the transfer paper reaches the cleaning section without being transferred.

The photoreceptor becomes insufficiently cleaned. In other words, 1. Normally, the transfer rate is 80 to 90%, so the amount of toner that needs to be cleaned is the remaining 10 to 20%, and the cleaning capacity is also adjusted accordingly, but paper feeding may not be performed due to a jam. .

Even if the paper feed position is shifted from the normal position,
There will be areas where 100% toner remains, and there will be 5 to 10 times more toner than usual. the result,
The resulting insufficient cleaning causes background stains and afterimages on the next toner image, reducing image quality.

Therefore, after a jam occurs as described above, it may be possible to idle the device for several cycles and perform only cleaning before the next operation, but this method requires a long waiting time.

Since the photoreceptor with toner attached thereto is run for several cycles, there is a drawback that the toner scatters inside the device.

(Purpose) The present invention solves the above-mentioned drawbacks, that is, after a jam is detected and the device automatically stops, if the jammed paper is removed, sufficient cleaning can be carried out immediately before the next cycle. The purpose of this is to enable the

(Structure) For the above-mentioned purpose, the present invention performs cleaning before restarting the operation of the apparatus after removing the jammed paper, but the traveling speed of the photoreceptor at that time is slower than normal. In this way, the ratio of the sliding speed of the magnetic brush to the sliding speed is increased, and the discharge current of the PCC (pre-cleaning charger) is reduced in accordance with the traveling speed of the photoreceptor. It is.

A detailed explanation will be given below based on an embodiment shown in one figure. FIG. 1 shows this as a flowchart 1-. When the occurrence of a jam is detected by the jam detector, this is transmitted to the CPU and the device is automatically stopped. Next, once the jammed paper has been processed, the photoreceptor is driven at a low speed,
Start the cleaning process after jam removal.

At this time, the discharge current of the FCC is reduced to a value adapted to the traveling speed of the photoreceptor, and the rotational speed of the sleeve of the magnetic brush cleaning device is kept at a normal value. This cleaning step is carried out for a certain period of time, and after the elapse of this period, the electrophotographic apparatus is returned to a reusable state.

FIG. 2 shows the relationship between the residual toner removal rate, that is, the cleaning rate, and the ratio of the linear velocity of the sleeve to the linear velocity of the photoreceptor, and shows that the cleaning rate increases as the ratio increases. In order to deal with residual toner that has increased due to the occurrence of jams, it is necessary to increase the cleaning rate, and it is effective to increase the sleeve linear speed or decrease the photoconductor linear speed, but the sleeve As the linear speed increases, the carrier and toner that bridge the magnetic brush become more likely to scatter, polluting the inside of the machine. On the other hand, in the present invention, such a drawback does not occur because the cleaning rate is improved by reducing the linear velocity of the photoreceptor. However, a mere decrease in the linear velocity of the photoreceptor causes the following side effects.

FIG. 3 shows the relationship between the pcc emission current and the photoreceptor surface potential. The surface potential of the photoreceptor increases in proportion to I) the CC discharge current, but its proportionality constant changes depending on the linear velocity of the photoreceptor;
It will be higher if That is, when cleaning is performed by applying an FCC discharge current while the photoreceptor is in normal operation at a linear velocity value of A, the photoreceptor surface potential becomes P, which allows a proper leaning effect to be obtained. At the photoreceptor linear velocity value B, S becomes higher than P. By the way, as is clear from the relationship with the PCCCC photoconductor potential carrier adhesion amount shown in FIG. 4, if the photoconductor surface potential after PCC becomes excessive, the amount of carrier adhesion to the photoconductor surface will increase. . This adhered carrier not only invades the primary charger and obstructs its normal operation, but also scatters inside the machine, causing stains and depleting the cleaning agent, resulting in a decrease in cleaning performance.

However, in the present invention, as the photoreceptor linear velocity is decreased from A to B, the FCC discharge current is decreased from R to Q, so the photoreceptor surface potential can be maintained at There is no side effect of adhesion of the carrier to.

FIG. 5 shows an example of an electrophotographic copying machine embodying the present invention. Reference numeral 1 denotes a contact glass, and the lower surface of the document placed on this glass is irradiated with lamps 2a and 2b through the contact glass 1. A projected image of the original is formed by a lens 3 and mirrors 4, 5 onto an endless bell-shaped photoreceptor 6. The photoreceptor 6 travels in the direction of the arrow on a travel path formed by the drive pulley 18 and driven pulleys 19, 20, and 21. Along this travel path, the image forming section, the transmission type optical sensor 24, the conductive brush 23a, the erase lamp 16.
A developing device 7, a transfer charger 13, a static elimination lamp 17 equipped with a light guide 25, a separation charger 14, a cleaning device 8, a conductive plate 7-23b, and a charging device [i''! 15a and 15b are backup rollers. 26 is a paper feed section, and three types of transfer paper 30 of different sizes are fed to the feed rollers 11a and llb, respectively.
, and lie at a predetermined timing, and is supplied by the registration roller 12 in synchronization with the 1 to ner images on the photoreceptor 6. When this transfer paper 30 overlaps the photoreceptor 6 and passes through the action area of the transfer charger 13, it receives the toner image from the photoreceptor 6, and is then separated from the photoreceptor 6 by the action of the separation charger 14 and transported. The image is sent to the fixing device 9 by the device 29 . The transfer paper 30 leaving the fixing device 9 is discharged onto the discharge tray 1o as a completed copy.

The photoconductor 6 that has been transferred is cleaned by the cleaning device 8
- After the toner is removed and uniformly charged with the charger 22,
An electrostatic latent image is formed by the projected image of the next document in the imaging section, and the above cycle is then repeated.

The cleaning device 8 is equipped with a PCC in its artificial part, and applies the charge necessary for cleaning to the residual toner on the photoreceptor G. The cleaning device 8 is equipped with a non-magnetic sleeve in which a permanent magnet is fixedly arranged, and a magnetic carrier is formed by a magnetic carrier adsorbed to the circumferential surface of the sleeve.By rotating the sleeve, the magnetic brush is attached to the photoreceptor. 6 to rub. The magnetic brush that rubs against the photoreceptor 6 electrostatically attracts the charged I-ner and removes it from the photoreceptor 6.

If a jam occurs at any position in the path of the transfer paper 30 from the paper feed section 2G to the conveyance device 29.

This is detected and reported to the CI'U, and the copying machine is brought to a halt state. Therefore, when the jammed paper is removed and restarted, prior to steady operation, the photoconductor 6 moves at a low speed and the FCC discharge current is reduced, and the cleaning device 8 rotates the sleeve at a steady speed to perform cleaning. Let's do it.

The period of this cleaning mode is set in accordance with the time when all of the untransferred residual toner portion will finish passing through the cleaning device 8.

Note that a residual toner detection means may be provided at the entrance of the cleaning device ii8, and the cleaning mode may be terminated based on the output thereof.

Once the cleaning mode period is completed, the copier again returns to copy mode 1 and begins the next copy cycle.

(Effects) As described above, the present invention provides a cleaning mode period before restarting operation after removing jammed paper, and reduces the traveling speed of the photoreceptor during this period, thereby temporarily improving the cleaning rate. The remaining untransferred toner can be reliably removed in one cleaning. Therefore, since the photoreceptor with residual toner attached thereto is not circulated, it is possible to prevent the toner from scattering into the machine, and the required time can also be shortened. Further, since the cleaning rate is improved without increasing the rotational speed of the sleeve, the accompanying scattering of carrier and toner can be prevented. Furthermore, I
') By suppressing the CC discharge current, the quality of the photoreceptor potential is suppressed, so adsorption of carriers to the photoreceptor can be prevented, and problems associated with this can be prevented.

[Brief explanation of drawings]

Fig. 1 is a flowchart of the present invention, Figs. 2 to 4 are graphs showing changes in cleaning rate, photoreceptor surface potential, and carrier adhesion amount, and Fig. 5 is a graph of a copying machine implementing the present invention. It is a front view showing an example. 6...Photoreceptor 8...Magnetic brush type cleaning device patent applicant
Ricoh Co., Ltd. - Figure 1

Claims (1)

[Claims] A cleaning mode period is provided prior to restarting operation after removing jammed paper, and during this period, the traveling speed of the photoconductor is reduced from the steady state value, thereby increasing the ratio of the sleeve linear speed to the photoconductor linear speed. At the same time, the discharge current of the pre-cleaning charger is changed according to the reduction in the traveling speed of the photoreceptor.
A method for cleaning a photoreceptor of an electrophotographic device using a magnetic brush, characterized in that the cleaning method reduces the value from a normal value.