US3927936A

US3927936A - Blade type cleaning device in an electrophotographic copying machine of the image transfer type

Info

Publication number: US3927936A
Application number: US375463A
Authority: US
Inventors: Shigehiro Komori; Hisashi Sakamaki; Hiroyuki Hattori; Toshihide Iida; Koichi Miyamoto; Kazumi Umezawa
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1972-07-18
Filing date: 1973-07-02
Publication date: 1975-12-23
Anticipated expiration: 1992-12-23
Also published as: CA982811A; AU5787673A; NL7309561A; DE2336613C2; FR2193217B1; DE2336613A1; JPS4930043A; FR2193217A1; GB1444952A

Abstract

A blade type cleaning device for use with an electrophotographic copying machine of the image transfer type includes a cleaning blade having an end edge urged into contact with the surface of a photosensitive drum to clean such surface. The blade of this invention is designed such that the line of contact of the end edge thereof with the surface of the photosensitive drum lies within a range from the top of the drum surface to a portion of the drum surface downwardly shifted from the top in the direction of rotation of the drum and that the angle of contact of the blade is within the range of 25* to 40* with respect to that portion of the tangential plane containing the line of contact which extends downstream of the line of contact with respect to the direction of drum rotation.

Description

United States Patent [191 Komori et a1.

[73] Assignee: Canon Kabushlki Kaisha, Tokyo,

Japan 22 Filed: July 2, 1973 21 Appl. No.:375,463

[30] Foreign Application Priority Data July 18. 1972 Japan 47-71860 [52] US. Cl 355/15; 15/2$6.51 [51] Int. CL 603G 21/00 [58] Field of 15/256.5l, 97 R, 1.5, 308; 355/15; 118/637, 261

[56] References Cited UNITED STATES PATENTS 1,415,859 5/1922 Bates 15/256.51 [594,284 7/1926 Vickery l5/256.51

[ Dec. 23, 1975 Primary Examiner-Edward L. Roberts Attorney, Agent, or Firm-Fitzpatrick, Cella, Harper & Scinto ABSTRACT A blade type cleaning device for use with an electrophotographic copying machine of the image transfer type includes a cleaning blade having an end edge urged into contact with the surface of a photosensitive drum to clean such surface. The blade of this invention is designed such that the line of contact of the end edge thereof with the surface of the photosensitive drum lies within a range from the top of the drum surface to a portion of the drum surface downwardly shifted from the top in the direction of rotation of the drum and that the angle of contact of the blade is within the range of 25 to 40 with respect to that portion of the tangential plane containing the line of contact which extends downstream of the line of contact with respect to the direction of drum rotation.

; 10 Claims, 6 Drawing Figures US. Patent Dec. 23, 1975 Sheet 1 of3 3,927,936

U.S. Patant Dec. 23, 1975 Sheet 2 of3 3,927,936

FIG. 5

US. Patent Dec. 23, 1975 Sheet 3 of 3 3,927,936

BLADE TYPE CLEANING DEVICE IN AN ELECTROPHOTOGRAPHIC COPYING MACHINE OF THE IMAGE TRANSFER TYPE BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to a blade type cleaning device in electrophotographic copying machines of the image known in the art. They include, for example, a system of the type whereby a rotating fur brush is brought into contact with the surface of the photosensitive medium to wipe off any residual developer therefrom, and a system of the type whereby a web of paper or cloth is urged into contact with the surface of the photosensitive medium to remove the residual developer therefrom. Any of these systems involves a complicated construction and the provision of a drive source therefor, which leads to economical disadvantages. Moreover, fur or web of paper or cloth is shorter in service life and cannot be reused. In addition, the use of fur or paper or cloth is disadvantageous in that fragments thereof tend to admix with the residual developer (toner) to make such developer unsuitable for further use because such fragments are hardly separable from the developer. Especially, where the cleaning device is directed to the removal of liquidous developer, the material used for the cleaning purpose is absorbent of liquid and accordingly becomes wet therewith, and the result is uneconomical consumption of the liquid as well as inefficient cleaning effect.

In view of these points, the blade type cleaning device would be the simplest and most reliable for use with the copying machines of the image transfer type and would be the most advantageous to improve the cleaning efficiency. Nevertheless, if the line of contact of the blade with the surface of the photosensitive medium were improperly positioned, the developer once wiped off by the blade could not positively be collected and thus would contaminate the interior of the machine. Also, the magnitude of the contact pressure of the blade depends on the angle of contact of the blade with the surface of the photosensitive medium and therefore, too low a contact pressure results in a poor cleaning efficiency and too high a contact pressure might not only cause rapid wear of the blade usually formed of rubber or synthetic resin, but also cause injuries or damages to be imparted to the surface of the photosensitive drum or to the blade itself even by a slightest amount of foreign materials which may be present in the developer, thus adversely affecting the resultant image and/or causing localized insufficient cleaning effects. Furthermore, during the cleaning, the intense pressure contact of the wear-resistant and resilient blade with the surface of the photosensitive drum could produce a play in the supporting portion for the blade to reduce the cleaning efficiency unless the mount structure for the blade is sufficiently rigid.

SUMMARY OF Ti -IE INVENTION It is therefore an object of the present invention to provide a blade type cleaning device which is very simple in construction and low in cost.

It is another object of the present invention to provide a blade type cleaning device which can positively and efficiently remove residual developer remaining on the surface of a photosensitive medium.

It is still another object of the present invention to provide a blade type cleaning device which permits fine adjustment of the pressure of a blade against the surface of the photosensitive medium.

It is yet another object of the present invention to provide a blade type cleaning device which prevents entry of dust or like foreign material into residual developer on the surface of the photosensitive medium.

It is a further object of the present invention to provide a blade type cleaning device which is rigid and durable to use.

It is a further object of the present invention to provide a blade type cleaning device which is usable in both the copying machines of the image transfer type utilizing liquid developer and those utilizing powder developer.

It is still a further object of the present invention to provide a blade type cleaning device which is simple and ready to mount.

According to the present invention, the line of contact of the end edge of the blade member with the surface of the photosensitive drum lies within a range from the top of the drum surface to a portion of the drum surface downwardly shifted from such top in the direction of rotation of the photosensitive drum, whereby any residual developer may readily be collected at the end edge of the blade and such residual developer may then be positively directed to collection passages provided on the photosensitive drum at the opposite ends thereof and leading to a developing device, and thus may be prevented from falling toward an image transfer station. Further, the angle of contact of the blade with the surface of the photosensitive drum is selected within a range of 25 to 40 with respect to that portion of the tangential plane containing the line of contact which extends downstream of the line of contact with respect to the direction of rotation of the photosensitive drum, and the blade mounting member is upwardly inclined at a predetermined angle with respect to the horizontal plane through the body of the copying machine containing the line of contact, whereby the pressure of the blade against the surface of the photosensitive drum may be minimized to achieve a positive and efficient cleaning effect. Furthermore, the vertical raising force imparted to the supporting portion of the blade having mounting and reception plates as the result of the friction force between the blade and the surface of the photosensitive drum may be received by the horizontal surface of the reception plate while the reaction force resulting from the pressure contact of the blade with the surface of the photosensitive drum may be received by the vertical surface of the reception plate, whereby the blade is made highly durable and rigid without any play produced in the blade supporting portion even during a long-time use. In addition, a skirt for removing rougher dust or unseparated transfer medium or the like from the surface of the photosensitive drum is added to the blade upstream thereof as viewed in the direction of rotation of the photosensitive drum.

3 The blade is also designed to permit fine adjustment thereof so that the end edge of the blade is urged into uniform contact with the surface of the photosensitive drum.

The invention will become more fully apparent from the following detailed description of an embodiment thereof taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing the blade type cleaning device according to the present invention.

FIG. 2 is a schematic sectional view showing the blade mounting portion.

FIG. 3 is a partly sectional view of the blade type cleaning device.

FIG. 4 is a partly sectional view of the blade type cleaning device and illustrating the position of the blade.

FIGS. 5 and 6 are an exploded perspective view and an enlarged, exploded perspective view of the blade type cleaning device, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 4, reference numeral 1 designates a photosensitive drum which is rotatable about its own axis in the direction of arrow and around which may be disposed a charging mechanism, an image exposure mechanism, a developing mechanism and a transfer mechanism, although these are not shown. A cleaning blade 2 is attached to a mounting plate 3 having two different planar portions which may not always be at right angles with each other, e.g. a horizontal portion 4 and vertical portion 5. The blade 2 is held between the outer surface of the horizontal portion 4 of the plate 3 and a pressure plate 7 and firmly secured to the mounting plate 3 by means of screws 26. As is shown in FIG. 2, the pressure plate 7 has a relieved portion e formed therein to protect the end edge A or B of the blade 2 against injury, these edges A and B of the blade 2 being selectively available for cleaning. Reference numeral 6 designates a retainer member for the blade 2, and reference numeral 8 denotes an auxiliary plate of boat-like cross section integrally attached to the two inner surfaces of the mounting plate 3. The auxiliary plate 8 may alternatively comprise an apertured or cut-out plate interposed be tween two plates so as to provide a clearance.

A member 9 is provided for restricting the effective length of the blade 2 and engages with the opposite ends of the photosensitive medium or with a groove which may be provided adjacent the opposite ends to prevent developer from being directed to the back face of the blade member along the end portion of the blade member, and to guide the developer to the groove. Means designated by 23 is for positively preventing any developer wiped off by the blade 2 from flowing along one side of the blade and onto the reverse side thereof. A support shaft 10 is rotatably mounted between the opposite side plates of a copying machine body not shown. The shaft 10 has a reception plate ll attached thereto and formed with reception surfaces substantially similar in configuration to those of the auxiliary plate 8. A screw I2 is provided to clamp the auxiliary plate 8 and the reception plate 11 together so that the inclined surfaces of these plates are secured to each other. Nuts 24 and bolts 25 are used to urge the blade 2 into contact with the surface of the photosensitive drum 1. The reception plate 11 is formed with two internally threaded holes for threadably receiving the respective bolts 25. By screwing the bolts 25 into these holes to press the auxiliary plate 8 at two points therein, the blade 2 may be uniformly urged into contact with the surface of the photosensitive drum I while the pressure contact of the blade with the drum may be finely adjusted. Reference numeral 13 designates a skirt for removing any rougher dust or unseparated transfer medium from the surface of the photosensitive drum 1, and it is urged into contact with the drum surface upstream of the cleaning blade 2 as viewed in the direction of drum rotation. The pressure force with which the skirt 13 contacts the surface of the photosensitive drum 1 may be approximately one-fifth of that with which the blade 2 contacts the drum surface. The skirt I3 is useful to remove any undesired dust or like foreign materials in advance, thus protecting the drum 1 against any damage or injury which would otherwise be imparted thereto.

Referring now to FIGS. 5 and 6, a skirt holder plate 14 may be secured to the blade mounting plate 3 by inserting a screw 15 into each of slots 22 formed through the holder plate 14, whereby the contact pressure of the skirt with respect to the surface of the photosensitive drum 1 may be adjusted, that is, the force of the pressure contact of the skirt member is adjusted by the slot 22, utilizing the resiliency of the skirt member per se. A lever 16 for urging the blade 2 into contact with the surface of the photosensitive drum 1 is secured at one end to the support shaft 10 and carries a lock pin 17 at the other end. A stop member 18 for engagement by the lock pin 17 may be secured to a member 19 by means of screws 20 received in slots 21 formed in the stop member, the member 19 being provided on the copying machine body. Thus, the stop member 18 may be vertically displaced with the aid of the slots 2[ therein so as to permit adjustment of the contact pressure of the blade 2 with respect to the surface of the photosensitive drum 1.

As described above, the blade mounting plate 3 and the reception plate II are joined together with the latter plate bearing against the two right-angled inner surfaces of the former plate, and thus, during the cleaning effected with the blade 2 urged into contact with the surface of the photosensitive drum 1, the vertical raising force exerted on the mounting portion of the blade 2 as the result of the friction force between the blade 2 and the surface of the drum 1 can be received by the horizontal surface of the reception plate ll via the horizontal surface 4 of the blade mounting plate 3 while the reaction force resulting from the pressure contact of the blade 2 with the surface of the drum I can be received by the vertical surface of the reception plate 11 via the vertical surface 5 of the blade mounting plate 3. This ensures a very rigid connection to be maintained between the blade 2 and its mounting plate 3 without any play being produced in the blade mounting portion even during a long-time use of the blade. The blade 2 has been shown to have two right-angled planes but it may have two otherwise-angled planes for engagement with the reception plate and for reception of the reaction forces exerted on the blade. Moreover,

the provision of a clearance d between the inclined surfaces of the auxiliary plate 8 of boat like cross sec tion or an auxiliary plate having an opening or a cut-out portion and the corresponding inclined surface of the reception plate 11 is useful to provide a better engagement between the horizontal and vertical portions of the two plates 8 and H and to provide a resilient joint between the respective inclined surfaces of these two plates, which in turn prevents the screws 12 from being loosened during a long-time use and thus ensures a more rigid connection between the parts.

The auxiliary plate 8 may be replaced by means such as a coil spring or a laminated spring.

As can be seen in FIG. 4, the present invention has a further feature in the position and angle of pressure contact of the blade 2 with the surface of the photosensitive drum 1. More specifically, the line of contact L of the blade 2 with the surface of the photosensitive drum 1, as seen in FIG. 4 as a point, lies at the top T of the drum 1 or at a position downwardly angularly spaced by B(B+ 29) from such top T as viewed in the direction of drum rotation indicated by arrow, whereby any residual developer collected by the end edge of the blade 2 may be positively directed into collection passages leading to a developing device (not shown) and provided on the photosensitive drum 1 at the opposite ends thereof while such residual developer may be prevented from falling into an image transfer station. Further, the angle of contact a of the blade 2 is selected within a range of 25 to 40 with respect to a plane Pl which is a downward extension of a tangential plane P passing through the line of contact L, and the mounting portion of the blade 2 is upwardly inclined by 6 (6 +4) with respect to the horizontal plane H through the machine body containing the line of contact L. The tests have shown that the angle of contact a of the blade 2 can minimize the pressure force of the blade 2 against the surface of the drum 1 to thereby minimize the wear of the blade 2 as well as to provide uniform cleaning of the photosensitive drum surface over the entire width thereof. Furthermore, the aforesaid upward inclination of the blade 2 is effective to prevent any amount of the residual developer once wiped off from flowing toward the blade mounting portion and falling into the machine interior to contaminate the same. Since the end edge of the skirt 13 also suffers from the problem of residual developer, the position of contact of the skirt with the drum surface is necessarily limited, preferably to an angle 'y(y+ l0") as shown in FIG. 4 that is, the skirt member 13 is disposed before the blade member to remove dust or the like prior to the cleaning action by the blade member, so that there exists a desirable condition of contact with the drum l, ie, to contact it at a position on the drum surface displaced from the highest portion of the drum by approximately 10. The angles a. B and y in the relations that B a (IT-40) and 'y 0. Where the skirt [3 is not in use, the angles a and B are in the relation that 0 a a (-4U).

We claim:

1. A blade type cleaning device in an electrophotographic copying machine of the image transfer type comprising:

a blade member having an end edge thereof making pressure-contact with the surface of a rotatable photosensitive medium to clean said surface;

blade mounting means;

support means for supporting said blade mounting means on the body of said copying machine;

said blade member being of high polymer material and having said pressure contact edge formed into Lil substantially a right angle and contacting the photosensitive medium at a position thereof lower than the highest portion of the photosensitive member by an angle within the range of 0 to 40 in the direction of movement of said photosensitive medium, the angle of contact of said blade member being within a range of 25 to 40 with respect to that portion of the tangential plane containing a line of contact between the end edge and the surface of the photosensitive member, which extends downstream of the line of contact with respect to the direction of movement of the photosensitive medium, and the surface of the photosensitive medium and an end surface of said blade member forming a V-shaped groove.

2. A blade type cleaning device according to claim 1, wherein said blade member is upwardly inclined with respect to the horizontal plane.

3. A blade type cleaning device according to claim 1, wherein said blade mounting means is designed such that two substantially orthogonally directed surfaces of said blade mounting means receive forces exerted on said blade.

4. A blade type cleaning device according to claim 3, wherein said blade member includes a skirt member for removing dust or unseparated transfer medium from the surface of said photosensitive medium, said skirt member being disposed between the highest portion of the photosensitive medium and said blade member.

5. A blade type cleaning device according to claim 4, wherein said skirt member includes means for adjusting the pressure force with which said skirt member contacts the surface of said photosensitive medium.

6. A blade type cleaning device according to claim 3, wherein said blade mounting means further includes means for effecting fine adjustment of the pressure force with which said blade member contacts the surface of said photosensitive medium.

7. A blade type cleaning device according to claim 3, wherein said blade mounting means includes a relieved portion for protecting another edge of said blade memher.

8. A blade type cleaning device according to claim 1, wherein said blade mounting means is fixed to said supporting means by using a resilient force by an auxiliary member of boat-like shape.

9. A blade type cleaning device according to claim 1, further comprising means for forcibly preventing developer removed by said blade member from being directed to the back face of the blade member.

10. A blade type cleaning device in an clectrophotographic copying machine of the image transfer type comprising:

a blade member including a blade urged into contact with the surface of a photosensitive medium to wipe off any residual developer therefrom, and a skirt disposed between the top of the photosensitive medium and the blade member for removing dust or unseparated transfer medium from the surface of said photosensitive medium;

means for urging an end edge of said blade member into contact with the surface of said photosensitive medium;

blade mounting means for mounting said blade thereon including means for effecting fine adjustment of the pressure force with which said blade member contacts the surface of said photosensitive medium, said blade mounting member having a relieved portion for preventing an unused edge of the blade member from contacting said blade mounting means to protect the unused edge of said blade member, and a reception member for supporting said blade mounting member, said reception member having a horizontal portion for receiving a vertical force exerted on said blade and a vertical portion for receiving a horizontal force exerted on said blade; and

the area of contact of the end edge of said blade with the surface of said photosensitive medium lying at a position downwardly shifted from the top of the line of contact.

Claims

1. A blade type cleaning device in an electrophotographic copying machine of the image transfer type comprising: a blade member having an end edge thereof making pressurecontact with the surface of a rotatable photosensitive medium to clean said surface; blade mounting means; support means for supporting said blade mounting means on the body of said copying machine; said blade member being of high polymer material and having said pressure contact edge formed into substantially a right angle and contacting the photosensitive medium at a position thereof lower than the highest portion of the photosensitive member by an angle within the range of 0* to 40* in the direction of movement of said photosensitive medium, the angle of contact of said blade member being within a range of 25* to 40* with respect to that portion of the tangential plane containing a line of contact between the end edge and the surface of the photosensitive member, which extends downstream of the line of contact with respect to the direction of movement of the photosensitive medium, and the surface of the photosensitive medium and an end surface of said blade member forming a Vshaped groove.

7. A blade type cleaning device according to claim 3, wherein said blade mounting means includes a relieved portion for protecting another edge of said blade member.

10. A blade type cleaning device in an electrophotographic copying machine of the image transfer type comprising: a blade member including a blade urged into contact with the surface of a photosensitive medium to wipe off any residual developer therefrom, and a skirt disposed between the top of the photosensitive medium and the blade member for removing dust or unseparated transfer medium from the surface of said photosensitive medium; means for urging an end edge of said blade member into contact with the surface of said photosensitive medium; blade mounting means for mounting said blade thereon including means for effecting fine adjustment of the pressure force with which said blade member contacts the surface of said photosensitive medium, said blade mounting member having a relieved portion for preventing an unused edge of the blade member from contacting said blade mounting means to protect the unused edge of said blade member, and a reception member for supporting said blade mounting member, said reception member having a horizontal portion for receiving a vertical force exerted on said blade and a vertical portion for receiving a horizontal force exerted on said blade; and support means for supporting said blade mounting means on the body of said copying machine; the area of contact of the end edge of said blade with the surface of said photosensitive medium lying at a position downwardly shifted from the top of the photosensitive medium surface in the direction of rotation thereof; the angle of contact of said blade being within a range of 25* to 40* with respect to that portion of the tangential plane containing said line of contact which extends downstream of said line of contact with respect to the direction of rotation of said photosensitive medium; said blade mounting member being upwardly inclined with respect to the horizontal plane through the body of said copying machine containing said line of contact.