JPS59178474A - Method for blade cleaning of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent damage of a photosensitive body due to blade pressure and dust-like staining of a copy with a toner by transferring the toner attached to the blade to the photosensitive body, destaticizing it, lowering the surface potential of the body, executing a cleaning operation in a developing section, and then, starting successive cycles of copying operations. CONSTITUTION:A part of a photosensitive body 1 electrostatically charged with a charging charger 8 passes through a developing section 7 and a toner attaches thereto. Therefore, destaticization with an AC separation charger 5 does not reach the surface of the body 1 to leave charge. The toner 3' attaches to this charged part, and it is charged again, passed through the developing section 7 and attaches to the first copy. This trouble is prevented by controlling a timing of destaticization with the AC separation charger 5, transfer charging the body 1 to the same polarity as that of the charging charger 8, shifting the toner at the top of the blade to the body 1 before the start of copying, destaticizing it to make it easily removable, and cleaning the body at the section 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a blade cleaning method for an electrophotographic copying machine.

(Prior art) A blade cleaning device that scrapes off toner adhering to the surface of the photoreceptor by pressing a blade against the surface of the photoreceptor, as shown in FIG. The toner 3 is blocked by the edge 2α at the tip of the blade 2, and is collected upstream of the edge 2α and deposited in a Δ shape. Next, when the blade 2 is off, the edge 2α of the blade 2 is slightly spaced apart from the surface of the photoreceptor 1, as shown in FIG. 2, and a portion of the deposited toner 3 flows around to the downstream side of the edge 2α.

Therefore, when the blade 2 is turned on again, a small amount of toner 8' is attached to the downstream side of the edge 2α of the blade 2, as shown in FIG. When copying is performed in this state, a small amount of the toner 3' adheres to the portion of the photoreceptor 1 where charging has started, resulting in dust-like toner adhesion on the first copy as shown in FIG. Charging on timing is 20 to 8 minutes before sub-image formation.
The dust-like dirt part starts with
) The position of the cabinet. Experimentally, it only appears on the first copy, and because the amount is small, it disappears on the second and subsequent copies.

In order to eliminate the above-mentioned drawbacks, as shown in Japanese Utility Model Application No. 57-1105'70, it may be possible to create a blade that does not release the pressing force of the blade that is in pressure contact with the photoreceptor even after copying is completed, but it seems that the copying is on all day and night. When the temperature of the photoreceptor exceeds a predetermined temperature under normal usage conditions, the blade pressure force causes scratches on the photoreceptor as shown in FIG. 4, and once this occurs, black streaks appear on the plate copy.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 54-151043, it is also possible to strengthen a part of the photoconductor and press the blade against the reinforced section when the copying machine is stopped to prevent scratches on the photoconductor. However, there were drawbacks in that timing control was difficult and the diameter of the photoreceptor could not be made smaller.

Also, the stop layer blade of the copying machine is about 0.1 mm from the surface of the photoreceptor.
It was considered that the blades should be spaced apart by about 0.5 gates, but there were drawbacks such as difficulty in adjusting the distance, vulnerability to temperature expansion, and poor blade compatibility.

(Purpose) The present invention prevents the formation of scratches on the photoreceptor due to the pressure applied by the blade, and makes delicate adjustments to separate the blade from the surface of the photoreceptor by a small amount. The purpose of this is to reliably prevent contamination.

(Configuration) Conventionally, when the print button is turned on, the blade 2, which was released first, is turned on, and at the same time, the photoreceptor 1 and the transfer charge 4 are turned on.
, the AC separation charge 5, the static elimination lamp 6, and the developing section 7 are operated. In this state, the photoreceptor 1 starts rotating, and after about 1 second, the charging charge 8 is turned on, and then the exposure lamp 9
starts to create a latent image, which is developed in the developing section 7, transferred to the transfer paper 11 fed by the registration rollers 10 by the transfer charge 4, neutralized by the separation charge 5, and sent to the fixing section. It will be done. Looking at this series of operations, blade 2
The potential of the photoreceptor 1 entering the photoreceptor 1 is close to zero for a while after the print button is turned on. This is because even if the transfer charge 4 charges, the AC separation charge 5 removes the charge at the same time. On the other hand, since the charged portion of the charging charge 8 has passed through the developing section 7, toner is attached thereto. For this reason, the charge removal by the AC separation charge 5 does not reach the surface of the photoreceptor 1, and charges remain. Charges are more likely to remain in some portions of the transfer paper 11. The toner 8' adheres to this charged portion. In particular, most of the toner 8' adheres to the first part. This is charged again, passes through the developing section 7, and adheres to the first copy.

The present invention controls the timing of charge removal by AC separation charge, transfers the toner at the tip of the blade to the photoreceptor before copying starts using a transfer charge of the same polarity as the charge charge, removes the charge, and makes it easier to remove. It's something you should clean.

FIG. 5 is a timing chart of the method of the present invention. That is, the surface of the photoreceptor to which only the transfer charge is applied is y+5~
The voltage becomes 600v, and toner adheres to the tip of the blade. The surface layer static elimination lamp lowers the surface potential to near zero. The film is allowed to enter the developing section as it is without being charged (this width may be several tens of tons or less). At this point, most of the toner adhering to the photoreceptor is removed by the developing brush. Charging starts from this surface layer and normal copying begins.

The addition of the above steps will delay the first copy by about 0.8 seconds, but this is not a problem.

The method of the present invention may be performed every time during the return of exposure (in this case, toner can be recycled by turning the blade on and off at the same time as the opening), or A.
Instead of the combination of C separation charge and transfer charge, a pre-cleaning charge may be used, and the toner adhering to the opposite side of the photoreceptor may be periodically cleaned by the method of the present invention, and the blade may be cleaned after copying is completed. Cleaning may be performed by the method of the present invention by turning the blade on and off one or more times, or even when the blade is not turned on and off, toner leaking onto the downstream side of the blade may be cleaned by the method of the present invention.

(Effects) According to the present invention, before an image is formed on the photoreceptor, the photoreceptor is charged, the toner that passes through the blade portion and adheres to the blade is attached to the photoreceptor, and then the charge is removed to reduce the surface potential of the photoreceptor. By performing a series of copying operations after cleaning in the lower developing section, it is possible to reliably prevent toner from adhering to the first copy when copying starts, and also to remove the blade from the surface of the photoreceptor. There is no need for delicate adjustments such as a slight separation.

[Brief explanation of the drawing]

Figure 1 is a front view of the blade tip when the blade is off, Figure 2
The figure is a front view of the blade tip when the blade is off in Figure 1,
Fig. 3 is a front view of the tip of the blade when the blade is turned on in Fig. 2, Fig. 4 is an explanatory plan view of a state where toner has adhered to the copy in the form of dust, Fig. 5 is a diagram of the arrangement of each device around the photoreceptor, 6th
The figure is a timing chart of each device shown in FIG. 4 in accordance with the method of the present invention. ■... Photoreceptor, 2... Blade, 4... Transfer charge, 5... AC separation charge, 6... Static elimination lamp, 7... Developing section, 8... Charging charge, 9 ...Henko. Patent applicant Ricoh Co., Ltd. - Figure 1 Figure 2 Figure 4 Figure 5 Figure 3)゛

Claims (1)

[Claims] ■ In an electrophotographic copying machine having a blade cleaning device, before an image is formed on the photoreceptor, the photoreceptor is charged and the toner that has passed through the blade and adhered to the blade is transferred to the photoreceptor. A blade cleaning method that performs a series of operations such as adhesion, then neutralization to lower the surface potential of the photoreceptor, cleaning in a developing section, and then copying. (2) A method for cleaning a blade of an electrophotographic copying machine according to claim 1, wherein the charging is performed by a transfer charge.