Mita Industrial Co., Ltd.

Akinori Nishida

Masanori Matsuda

Eiji Goto

Shoji Matsumoto

Teruaki Higashiguchi

Takeshi Hori

Eiji Gotoh

Masahiro Shirai

Isao Iwagawa

Hironaga Iida

A method of electrically charging a material to be charged by bringing a charging member impressed with a voltage into physical contact with the material to be charged, wherein the charging member is constituted by a flexible and electrically conducting endless sheet and a rotary insulating brush which supports the endless sheet at a position where the endless sheet and the material to be charged are in contact with each other and gives a pushing force to the endless sheet, and the endless sheet is driven actively or passively together with the insulating brush at a speed substantially in synchronism with the material to be charged while applying a charging voltage to the endless sheet. This method makes it possible to uniformly and stably charge the surface of the photosensitive material even when defects such as pinholes or the like exist in the surface of the photosensitive material, without causing the life of the photosensitive material to be shortened.

Electrically charging method and electrically charging device used

A charging method for charging a photosensitive material of, for example, the photosensitive drum of an electrophotographic copying apparatus is accomplished by bringing an endless electrically conducting flexible sheet containing a brush roller into physical contact with the surface of the photosensitive material and applying a voltage to the electrically conducting flexible sheet. The electrically conducting flexible sheet is a laminate of a first resistance layer positioned on the side of the brush roller and a second resistance layer positioned on the outer surface of the first resistance layer. The second resistance layer has an electric resistance greater than that of the first resistance layer. The method using the laminated flexible sheet makes it possible to uniformly and stably charge the surface of the photosensitive material without the life of the photosensitive material being deteriorated and without permitting the output of the power source to drop even when defects, such as pinholes, exist in the surface of the photosensitive material.

Method of contact-charging the surface of a photosensitive material

In an electrophotographic apparatus using a charging apparatus for contact charging, the charging apparatus includes a flexible and hollow electrically conducting roller, and an electrically conducting brush roller which is provided in the hollow roller in concentric therewith and to rotate relative thereto, wherein a charging voltage is applied to the hollow roller via the brush roller, and the photosensitive material is electrically charged by rotating the hollow roller by bringing it into physical contact with the photosensitive material, and the hollow roller is brought at its both end portions into press-contact with the end portions on the surface of the photosensitive material and is rotated by being driven by the photosensitive material. In this apparatus, the hollow roller that comes into contact with the surface of the photosensitive material is driven at substantially the same speed as the photosensitive material, whereby slipping and wear are effectively prevented from occurring on the surface of the photosensitive material, durability of the photosensitive material is not lost, the hollow roller that is subject to be easily deformed is effectively prevented from being twisted, enabling the electric charging to be carried out stably and uniformly For extended periods of time.

Electrophotographic apparatus utilizing a hollow roller changing

An electrifying method which uses a electrifying a material wherein the contact-type electrifying member comprises a flexible and electrically conducting endless sheet and a brush which supports said endless sheet and imparts a pressing force thereto at a position where said endless sheet is in contact with the material to be electrified, said endless sheet which is impressed with an electrification voltage is driven or is moved at a speed which is substantially in synchronism with the material to be electrified, and the brush and the endless sheet are maintained at dissimilar speeds. This method makes it possible that homogeneously and uniformly electrifying a material to be electrified such as a photosensitive material or a like material without causing it to be damaged or worn out, even when the material electrifying member is rugged or even when a foreign matter is adhered on the surface of the photosensitive material, and a toner filming is not formed on the surface of the photosensitive material, and maintaining a uniformly contacting state between the electrifying member and the photosensitive material even with a relatively small force, as a result, accomplishes homogeneous electrification while preventing the photosensitive material from being worn out.

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Osaka, Japan

Akinori Nishida