CLEANING APPARATUS FOR ELECTROPHOTOGRAPHY

CLEANING APPARATUS FOR
ELECTROPHOTOGRAPHY

This is a continuation, of application Ser. No. 120,256, filed Mar. 2, 1971 and now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a cleaning apparatus for electrophotography and, more particularly, to a cleaning apparatus for removing toners remaining on a photosensitive member after transferring the images in an electrophotographic reproduction device of imagetransferring type.

2. Description of the Prior Art Representative conventional cleaning apparatuses

are a web cleaning apparatus and a fur brush cleaning apparatus. With respect to the web cleaning apparatus, the material of web is limited and the running cost is expensive, and further, cleaning ability varies depending upon the humid state of the web. In addition, the web should be frequently exchanged, and when reproduction of high density is continuously carried out for a long time, the cleaning can not be satisfactorily effected. Referring to the fur brush cleaning apparatus, the apparatus is usually of a large scale since the fur brush should be rotated at high speed, and the life of fur brush is disadvantageous^ short. In addition, an apparatus for removing the scattered developer by suction is necessary. Further, when reproduction of high density is continued for a long time, the cleaning capacity is not sufficient.

SUMMARY OF THE INVENTION

According to the present invention, the cleaning apparatus for an electrophotographic apparatus of a developed image transferring type comprises an elastic cleaning blade arranged along a surface of a photosensitive member after transferring images and the elastic cleaning blade is supported by a holder. The holder disposes the elastic cleaning blade relative to the photosensitive member to engage a substantially upwardly moving surface portion of the photosensitive member. The elastic cleaning blade preferably contacts with the surface of the photosensitive member to be cleaned in such a way that an angle 0U at the pre-cleaning side, subtended by an axis of the portion of the blade contacting the photosensitive member and a tangent line to the surface of the photosensitive member at the contact point and an angle <j>u at the pre-cleaning side, subtended by an axis of the portion of the blade supported by the holder and the above-mentioned tangent line satisfy the following relation:

The relation will be more fully understood by referring to FIG. 10..

An object of this invention is to provide a novel cleaning apparatus solving the drawbacks of the abovementioned prior arts.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1, FIG. 2 and FIG. 3 show embodiments of cleaning apparatus for electrophotography according to this invention where a plurality of elastic blades are used as the cleaning member;

FIG. 4 and FIG. S show other embodiments of the blade according to this invention;

FIG. 6'and FIG. 7 show embodiments of this invention where an elastic cleaning blade and a cleaning roller are employed;

FIG. 8 is a conventional cleaning blade; 5 FIG. 9 and FIG. 10 show embodiments of this invention and are diagrammatical cross sectional views for explaining conditions of blade arrangement with respect to the photosensitive member;

FIG. 11 shows a cross sectional side view of an em10 bodiment of this invention;

FIG. 12 shows a state of exchanging the blade; and

FIG. 13 shows a diagrammatical cross sectional view of a modified embodiment of a blade according to this invention.

15 DESCRIPTION OF THE PREFERRED

EMBODIMENTS

Referring to FIG. 1, a drum photosensitive member

1 is cleaned by blades 2!-2„ fixed to holders 3. Blades 20 2i-2„ are made of elastic material such as elastic synthetic resins and rubbers. Toners scratched off from the photosensitive member 1 by blades are collected to a toner receiver 4. In FIG. 1, some of plural blades 2i-2„ are arranged under the axis line X—X of the photosen

25 sitive member 1 and the photosensitive member 1 is rotated counterclockwise and toner T remaining on the photosensitive member is scratched off by the first blade 2j and falls down to a toner receiver 4 over the surface of the blade 2t through the other end of the

30 blade 2X. On the other hand, the remaining toner T not removed by the first blade 2X is removed by the second blade 22 and in a similar way the cleaning is repeated subsequently. Referring to FIG. 2, the photosensitive member 1 is

35 rotated clockwise and the remaining Toner 2 is scratched off by a blade 2„ at the nth step and the toner thus scratched off falls down directly to the toner receiver 4 and therefore, the toner receiver 4 should be placed nearer to the photosensitive member 1 than

40 FIG. 1. In general, a remaining toner not removed by a blade 2„ at nth step is removed by a blade 2„_! at (n— l)th step (in FIG. 2, corresponding to the second step) and the toner thus removed once falls down to blade 2„ at the nth step and then to the toner receiver

45 4. In a similar way, the cleaning is repeated.

Referring to FIG. 3, all blades 2,-2„ are arranged above the axis line X—X and in a way similar to FIG.

2 the cleaning of the photosensitive member 1 is car■ ried out, but a sheet 5 is necessary for introducing toner

scratched off by the nth blade 2„ to a toner receiver 4. In this case, the sheet 5 contacts lightly with the photosensitive member 1, but does not scratch off the remaining toner on the photosensitive member. The sheet 5 prevents the toner scratched off by a blade 2„ from falling down outside of the cleaning box.

Referring to FIG. 4, there is shown an embodiment where another shape of blade is employed, that is, plural blades 6i-6„ have toner scratching portion 7 and

gQ toner receiving surface 8 and are fixed to a holder 3. Some blades are placed under the axis line X—X of the photosensitive member 1. When the photosensitive member 1 rotates clockwise, the remaining toner T is scratched off by a blade 6, with its scratching portion

65 7 and the toner thus scratch off directly falls down to a toner receiver 4. On the other hand, the remaining toner which is not removed by the scratching portion 7 of blade 6i is removed by a scratching portion 7 of a

blade 62 and the toner thus removed is introduced into a toner receiver 4 by way of a toner receiving surface 8 of a blade 6,. The cleaning of the photosensitive member 1 is subsequently repeated in a way as mentioned above.

Referring to FIG. 5, all blades are arranged above the axis line X—X of the photosensitive member 1 and the cleaning of the photosensitive member 1 is effected in a way similar to FIG. 4, but toner scratched off by the scratching portion 7 of a blade 6i is introduced to a toner receiver 4 using a sheet 5. In this case, the sheet 5 is arranged in a way similar to FIG. 3 and serves similarly.

In the above embodiments a plurality of blades for scratching off toner are arranged along the surface of the drum photosensitive member 1 after the transferring, and therefore, the cleaning of the photosensitive member 1 can be repeated at each blade to clean completely the photosensitive member. Since each blade is not necessary to have such a strong contacting pressure against the photosensitive member 1 as compared with a case where only one blade is used for cleaning and thereby the surface of photosensitive member 1 is not damaged. Each blade is so arranged that toner scratched off from the surface of photosensitive member 1 can be introduced into a toner receiver 4 by way of each blade and therefore, any particular sheet for guiding the toner is not necessary. Thus, the cleaning apparatus can be of a small type and inexpensive.

When an electroconductive blades are used and a bias voltage is applied thereto so as to absorbing and removing the remaining toner T, the cleaning of photosensitive member 1 can be conducted more completely.

Referring to FIG. 6 and FIG. 7, further embodiments according to this invention are illustrated. Blades 7 having holders 3 similar to FIG. 4 and FIG. 5 are fixed to a cleaning box 9 with holders. The cleaning blade may be made of synthetic resin such as Teflon (Trade name, supplied by E. I. duPont de Nemours & Co. Inc.), silicon rubber, polyester, and polyethylene, or rubbers. The surface of an elastic roller 10 is coated with a cleaning coating 11, e.g., cloth, suede, and jersey and the hardness of the coating is preferably about 20°. A thin synthetic resin (such as polyester) sheet 5 is provided to guide the toner scratched off from the surface of photosensitive member 1 to a toner receiver 4 provided removably at the bottom of the cleaning box 9.

When the photosensitive member 1 rotates to a direction as shown by the arrow, most of toner T remaining on the surface of the photosensitive member 1 are scratched off by a blade 7 and then falls down to a toner receiver 4 by way of a sheet 5 and further the toner T' not removed by blade 7 is removed by rubbing with an elastic roller 10 and falls down to a toner receiver 4 by way of a toner receiving surface 8 and thereby the photosensitive member 1 is completely cleaned.

In FIG. 6, a cleaning brush 12 rotating to a direction as shown by the arrow removes the toner on the cleaning coating 11 and the toner attached to the brush is removed by a bar 13. Scattered toners are taken out through a duct 14. In FIG. 7, the toner on the cleaning coating 11 is removed by a vacuum duct 15.

According to the above-mentioned embodiments, both a blade and an elastic roller which are different from each other in point of function are used and this

combination can compensate each drawback to result in a complete cleaning. When a blade alone is employed, some portions of the photosensitive member are not completely cleaned, but a part of toner still re

5 mains on the photosensitive member in a form of streak since a completely uniform contact between the blade and the longitudinal line on the surface of a drum photosensitive member is not easily obtained. On the contrary, when an elastic roller alone is used, the insuffi

10 cient cleaning appears as a whole surface smudge. In the above embodiments, these two cleaning means are combined to scratch off about 90 percent or more of the remaining toner by the blade and clean the still remaining toner in a form of streak by the elastic roller

15 uniformly contacting with the photosensitive member in a longitudinal direction. Since the toner in a form of streak is so little that the load to the roller is not heavy and neither the whole roller becomes dirty. Therefore, the cleaning roller is used only for finishing and further

20 the contacting force to the photosensitive member may be weak. And, therefore, the photosensitive member is not damaged.

In addition, blades and sheets are inexpensive and simple and the exchange thereof is easy.

25 It is very convenient that a part of the cleaning cloth around the roller is adhered by an adhesive for facilitating the exchange of the cleaning cloth.

Referring to FIG. 8, there have been used an elastic blade 16 contacting slantingly with the photosensitive

30 member 1 in conventional devices and the cleaning has been carried out at the acute angle side of angles made between the photosensitive member 1 and the blades. This structure is far better than a cleaning device utilizing a fur web, but the resultant force R of a vertical re

35 action force N which the blade 16 receives from the photosensitive member 1 and a friction force F between the photosensitive member 1 and the blade 16 is in a direction for leaving the blade 16 from the photosensitive member 1. Therefore, a force obstructing the

40 toner is so weak that toner particles often enters under the blade 16 and further when one particle enters under the blade, the entering of toner particles easily propagates itself over the whole length of the blade. As the result, the blade should be often dismantled to clean the top edge portion of the blade.

Referring to FIG. 9, the disadvantage as mentioned above is eliminated by effecting the cleaning at the obtuse angle side of angles made between the blade 16 and the photosensitive member 1. In this case, one part of the resultant force R is stored as an elastic strain of blade and all the other part of the resultant force works as a cleaning force. The blade 16 is pushed to the wedge-like space between the holder 17 and the photo

55 sensitive member 1, that is, a direction of the frictional force F, and thereby the toner-obstructing force is far larger than that in FIG. 8 and the entering of toner particles under the blade is almost completely obstructed. Referring to FIG. 10, assuming a tangent line Z—Z

60 passing the intersecting point P of an extension line of the axis Y—Y of the holder 17 and the photosensitive member 1, among the angles subtended by line Z—Z and line Y—Y, the angle at the pre-cleaning side and the angle at the post-cleaning side are designated as <£,

65 and $2, respectively. Among the angles subtended by the tangent line Z—Z and the axis line of the bending portion of the blade 16, the angle at the pre-cleaning side and the angle at the post-cleaning side are desig