US3685485A

US3685485A - Device for preventing scattering of developer

Info

Publication number: US3685485A
Application number: US79517A
Authority: US
Inventors: Noboru Kutsuwada; Katsumi Nagamatsu
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1969-10-15
Filing date: 1970-10-09
Publication date: 1972-08-22
Anticipated expiration: 1989-08-22
Also published as: DE2050789B2; DE2050789C3; DE2050789A1

Abstract

An improved device for preventing the scattering of developer applicable to a dry type electrophotographic copying apparatus, especially to portions thereof dealing with developer such as developing means, cleaning means, etc. The device includes a container for containing developing or cleaning mechanism and having an opening formed at a portion thereof, air communication ports disposed at the edge portions of the opening in the container so as to form an air flow for sucking any scattering developer, and filter means for catching and collecting the developer mixed with the air flow, thereby perfectly preventing the developer from scattering out of the developing or cleaning means.

Description

United States Patent Kutsuwada et al.

[ 1 Aug. 22, 1972 [54] DEVICE FOR PREVENTING SCATTERING OF DEVELOPER [72] Inventors: Noboru Kutsuwada; Katsumi Nagamatsu, both of Tokyo, Japan [73] Assignee: Canon Kabushiki Kaisha, Tokyo,

Japan [22] Filed: Oct. 9, 1970 [21] Appl. No.: 79,517

[30] Foreign Application Priority Data Oct. 15, 1969 Japan ..44/98143 Oct. 15, 1969 Japan ..44/98144 [52] US. Cl. 118/637, 117/175, 355/3 [51] Int. Cl. ..G03g 13/00 [58] Field of Search.....l 18/637; 117/17, 17.5; 355/3 [56] References Cited UNITED STATES PATENTS 3,357,403 12/1967 Donalies ..l18/637 3,585,060 6/1971 Gourdine et a1 ..118/638 2,876,737 3/1959 Carlson ..117/17.5 2,804,708 9/1957 Simjian ..1 18/637 3,332,328 7/1967 Roth, Jr ..95/l.7

Primary Examiner-Mervin Stein Assistant Examiner-Leo Millstein Att0rney-Watson, Leavenworth 8L Kelton [5 7 ABSTRACT An improved device for preventing the scattering of developer applicable to a dry type electrophotographic copying apparatus, especially to portions thereof dealing with developer such as developing means, cleaning means, etc. The device includes a container for containing developing or cleaning mechanism and having an opening formed at a portion thereof, air communication ports disposed at the edge portions of the opening in the container so as to form an air flow for sucking any scattering developer, and filter means for catching and collecting the developer mixed with the air flow, thereby perfectly preventing the developer from scattering out of the developing or cleaning means.

8 Claims, 5 Drawing Figures DEVICE FOR PREVENTING SCATTERING OF DEVELOPER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a device for preventing the scattering of developer in an electrophotographic copying apparatus, and more particularly to such a device which is applicable to a dry type developing or cleaning means to prevent developer from scattering therefrom toward other parts of the copying apparatus and thereby eliminate the occurrence of troubles in the various operating mechanisms of the copying apparatus or in the electrodes for electrically charging a photosensitive medium, thus ensuring satisfactory image reproduction and minimizing waste of developer.

2. Description of the Prior Art Various devices of the described type are known as applicable to developing means, cleaning means or the like in an electrophotographic copying machine. Among them, the best known type is that in which a fur brush or sponge-like member is provided along the edge of an opening formed in a container dealing with developer so as to block any scattering developer. However, if the fur brush or the sponge-like member is saturated with developer, it will no longer be able to effectively act as blocking means and the layers of developer built up on the brush or sponge will seriously stain the formed image.

SUMMARY OF THE INVENTION It is therefore one of the objects of the present invention to provide an improved device for handling and preventing the scattering of developer which is applicable to portions of a dry type electrophotographic copying apparatus dealing with developer such as the developing means, cleaning means and the like in order to prevent the developer from scattering out of these means. I

It is another object of the present invention to provide an improved device for preventing the scattering of developer which is applicable to various means dealing with developer so as to control the scattering of developer by a flow of air formed at the peripheral portion of an opening opposed to a photosensitive medium.

It is still another object of the present invention to provide an improved device for preventing the scattering of developer which is applicable to various means dealing with developer so as to absorb the developer scattered from such means by means of a filter.

To achieve these objects, the device of the present invention may comprise a container for containing therein a developing or cleaning mechanism and having an opening formed at a portion thereof, and air communication ports provided at the edge portion or margin of the opening in the container so as to form a flow of air in that opening to thereby suck or force back the developer tending to fly out of the container. Filter means is further provided to catch and collect the developer sucked with the air flow into the communication ports.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described below in greater detail with respect to some specific embodiments thereof as shown in the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a device according to an embodiment of the present invention as it is applied to the developing means;

FIG. 2 is a cross-sectional view showing another form of the present invention as applied to the developing means;

FIG. 3 is a cross-sectional view showing still another form of the present invention as applied to the cleaning means;

FIG. 4 is a sectional view of the filter means used with the devices of FIGS. 1 to 3; and

FIG. 5 is a front view of the same filter means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a photosensitive medium I having an electrostatic latent image formed thereon is disposed over a drum 2 formed of metal and rotated in the direction indicated by an arrow. Adjacent the drum 2 there is a developer container 3 containing therein an amount of developer 4 and a developing brush 5 such as a magnetic or fur brush rotated in the direction opposite to the direction of rotation of the drum 2. The developer container 3 has an opening formed in its walls at one comer portion thereof to allow contact between the brush 5 and the photosensitized medium 1 on the drum 2 An air outlet port 6 and an air inlet port 7 are disposed adjacent the opposite edge portions or margins of the opening in the container 3 as indicated at A and B, respectively. These edge portions A and B respectively provide an entrance and an exit of the developer container 3 with respect to the photosensitized medium 1. The air outlet and inlet ports 6 and 7 are in communication with each other through connecting

pipes

8 and 9, between which there are interposed a fan 10 and a detachable filter layer 11 forming a filter means 12. A developer separator 13 such as an inclined plate is provided upstream or in front of the filter means 12, and a developer collector means 14 is disposed right below the developer separator 13 so as to collect any developer separated thereby from the air flow.

With such arrangement, part of the developer 4 which tends to scatter from the rotating developing brush 5 into the exterior of the developer container 3 can be sucked with air through the air inlet port 7 onthe one hand, and can be forced back into the container 3 by the air blown thereinto through the air outlet port 6 on the other hand. Thus, the tendency of the developer to scatter beyond the developer container 3 can be obviated satisfactorily.

When the drum 2 and the developing brush 5 are rotating in opposite directions as shown, more of the developer tends to scatter in the entrance portion A of the developer container 3 than in the exit portion B, because in the entrance portion some of the developer which has been relatively firmly sticking to the developing brush 5 due to the electrostatic attraction is caused to transfer onto the photosensitive medium 1 because of the contact between the brush 5 and the medium 1 while some of the developer comes off the developing brush 5 due to the variation in the orientation thereof resulting from the shock imparted thereto by the rotating photosensitive medium 1 and scatters in the direction of rotation due to the centrifugal force of the brush. For this reason, the air outlet port 6 is disposed adjacent the entrance portion A while the air inlet port 7 is disposed adjacent the exit portion B, so that waste of the developer may be minimized.

The filter means 12 is directed to catch any developer contained in the air passing through the inlet port 7 and pipe 9, and the filter layer 11 thereof may preferably be an electrostatic filter layer comprising laminated layers of thin fiber such as polyvinyl chloride, polyester, polyacrylonitrile, polyethylene, polypropylene, rayon or the like, the laminated layers of fiber being bound together by needling them in such a manner that the thin fibers forming the layers are uniformly entangled together. Further, the density of the fiber may be progressively increased from upstream to downstream (right to left as viewed in FIG. 1) so as to increase the filtering effect. Also, the filter layer 11 of the filter means 12 may be formed into a removable structure so as to facilitate the replacement or cleaning thereof.

Referring now to FIG. 2, there is shown a further embodiment of the present invention. Similarly to the embodiment of FIG. 1, the photosensitive medium 1 on the drum 2 rotating in the direction indicated by an arrow is contacted by a developing brush 17 such as a magnetic or fur brush rotatably mounted in a developer container 15, which contains therein an amount of developer 16, and rotating in the direction opposite to the direction of rotation of the drum 2. Two suction pipes 18 for sucking scattered developer extend into the developer container adjacent the opposite edges 19 of the opening thereof. The portion of each of the suction pipes 18 which is disposed within the developer container 15 is formed with a number of suction ports 18' such as throughapertures or slits extending longitudinally of the pipes 18 for sucking therethrough the developer scattered in the container 15. Outwardly of the developer container 15, the suction pipes 18 are joined to transport pipes 20, which in turn join together at the other end to form an enlarged exhaust passage 1 ading to the atmosphere. In that exhaust passage t ere is disposed a developer separator 21 such as the inclined plate below which there is removably mounted a developer collector means 22. Downstream of the developer separator 21, a filter layer 23 and a suction fan 24 are disposed transversely of the exhaust passage.

With this arrangement, the scattered developer in the developer container may be sucked with air through the suction ports 18' of the suction pipes 18 and then passed through the transport pipes to strike the inclined plate 21, where most of the developer is caused to drop into the collector 22 while the remaining part of the developer is passed to and caught by the filter layer 23. Thus, air alone is discharged into the atmosphere.

According to the described system, the scattered developer which tends to go out of the developer container 15 is sucked into the suction pipes 18, whereby the other interior parts of the copying apparatus may be protected against such scattering developer. Furthermore, at the developer separator 21, most of the developer there is collected or retrieved by the collector 22 which, when filled with such developer, may be removed to return the collected developer into the developer container 15 and then may be put into its place again. Thus, unnecessary waste of developer is avoided. The filter layer 23 may also be removed for cleaning or for replacement.

According to the present embodiment, a pair of electrodes 25 may be provided within the developer container 15 in opposed relationship with the inner ends of the respective suction pipes 18, and connected with a bias voltage source 26 whose polarity is the same as that of the developer in use. When a bias voltage is applied thereto, such electrodes can serve to force the scattering developer toward the inner part of the container 15 and thereby minimize the scattering tendency of the developer.

Turning now to FIG. 3, there is shown an example of to cleaning device incorporating an anti-scattering device of the present invention. In this example, instead of using the suction pipes 18 as shown in FIG. 2, a double-walled container 27 is employed to provide a suction passage 28 defined by the inner and outer walls of the container. The photosensitive medium 1 on the drum 2 rotating in the direction of the arrow is contacted by a rotary cleaning brush 29 such as a magnetic or fur brush so as to remove any residual developer left on the surface of the photosensitized medium 1. The developer removed from the medium 1 by the cleaning brush 29, as shown at 26, tends to remain in suspension within the space defined by the inner wall of the cleaning box 27. However, such suspended developer is sucked with air through suction ports 28 of the suction passage 28 defined by the inner and outer walls of the container 27, and then passed through a pipe 30 to a developer separator (not shown) of the same construction as described withrespect to FIG. 1 or 2. Most of the developer passed to the developer separator is separated from the air by that separator and collected in a developer collector (not shown) which is also similar to that shown in FIG. 1 or 2. Any developer still left in the air is passed through unshown filter means and caught thereby in the manner as described with respect to FIGS. 1 and 2.

FIG. 4 and 5 show in greater detail theconstruction of the filter means used with the embodiments of FIGS. 1 to 3. The filter means may comprise a pair of filter frames 30 holding a filter layer 31 therebetween. As already noted above with respect to FIG. 1, the filter layer 31 (filter layer 11 or 23 of FIG. 1 or 2) may preferably be an electrostatic filter layer comprising laminated layers of thin fiber such as polyvinyl chloride, polyester, polyacrylonitrile, polyethylene, polypropylene, rayon or the like, the layers of fiber being bound together by needling them in such a manner that the thin fibers forming the layers are entangled together. The filter frames 30 are connected together at their top by engagement between a hooklike handle 32 pivotally mounted on one of the filter frames and a stud 33 formed on the other frame, while at the bottom the two filter frames 30 are hinged together at 34. Thus, by releasing the engagement between the handle 32 and the stud 33, the two filter frames 30 can be fully opened so as to enable the replacement or cleaning of the filter layer 31 as desired.

It will thus be appreciated that the various forms of the present invention as shown in FIGS. 1 to 3 may be interchangeably applied to the developing means and the cleaning means of a dry type electrophotographic copying machine, and they may further be applicable to any other portion of the copying machine which may suffer from scattered developer. It will be readily understood by those skilled in the art that the pressure of the air stream should be suitably varied depending on whether the present invention is applied to developing means or to cleaning means.

As has been disclosed hitherto, the device for preventing the scattering of developer according to the present invention is highly useful to prevent developer from scattering from any portion of a copying apparatus which deals with developer, such as developing means, cleaning means or the like, and thereby eliminates the occurrence of troubles which might otherwise arise in various operating mechanisms for those means or in electrodes for electrically charging the photosensitive medium. Also, the use of air flow for preventing the scattering of developer is advantageous in that no mechanical injury or damage is imparted to the surface of the photosensitive medium and accordingly to the image formed thereon.

What is claimed is:

1. A device for handling dry developer powder adjacent a photosensitive medium comprising in combination: a container for said powder having an opening in the walls thereof disposed in close opposition to a surface of said medium, means in said container for effecting transfer of said powder through said opening relative to said medium, air ports disposed adjacent the margins of said opening, means for impelling air having a suction inlet and a pressure outlet, an air passage interconnecting said suction inlet with said ports, and means disposed in said air passage for separating and retrieving said powder from a mixture of powder and air flowing through said passage.

2. A device according to claim 1, wherein said ports are divided into two parts respectively adjacent opposite margins of said opening, said air passage interconnects one of said port parts with said suction inlet, and a further air passage interconnects the other port part with said pressure outlet.

3. A device according to claim 1, wherein an electrode is mounted in said container adjacent an air port, and means are coupled to said electrode for supplying energy thereto for diverting said powder from said last mentioned air port.

4. A device according to claim 3, wherein said energy supplying means applies DC. voltage to said electrode having the same polarity as said powder.

5. A device for handling dry developer powder adjacent a photosensitive medium comprising in combination: a container for said powder having an opening in the walls thereof disposed in close opposition to a surface of said medium, means in said container for effecting transfer of said powder through said opening relative to said medium, air ports disposed adjacent opposite margins of said opening, means for impelling air, filtfi sllfi ififi, li22fiill$fl5 filif lli siig for separating said powder from a mixture of powder and air flowing through said passage, a pair of electrodes disposed respectively adjacent opposite air ports, and means coupled to said electrodes for supplying energy thereto for diverting said powder from the respectively adjacent air port.

6. A device according to claim 5, wherein said energy supplying means applies DC. voltage to said electrodes having the same polarity as said powder.

7. A device according to claim 5, wherein said means in said air passage for separating said powder includes means for retrieving the powder so separated.

' 8. A device for handling dry developer powder adjacent a photosensitive medium comprising in com bination: a container for said powder having an opening in the walls thereof disposed in close opposition to a surface of said medium, means in said container for effecting transfer of said powder through said opening relative to said medium, air ports disposed adjacent opposite margins of said opening, means for impelling air having a suction inlet and a pressure outlet, an air passage interconnecting said suction inlet with said air ports, means disposed in said air passage for separating said powder from a mixture of powder and air flowing through said passage, a pair of electrodes disposed respectively adjacent opposite air ports, and means coupled to said electrodes for supplying a DC. voltage thereto having the same polarity as said powder.

Claims

4. A device according to claim 3, wherein said energy supplying means applies D.C. voltage to said electrode having the same polarity as said powder.

5. A device for handling dry developer powder adjacent a photosensitive medium comprising in combination: a container for said powder having an opening in the walls thereof disposed in close opposition to a surface of said medium, means in said container for effecting transfer of said powder through said opening relative to said medium, air ports disposed adjacent opposite margins of said opening, means for impelling air, an air passage interconnecting said air impelling means with said air ports, means disposed in said air passage for separating said powder from a mixture of powder and air flowing through said passage, a pair of electrodes disposed respectively adjacent opposite air ports, and means coupled to said electrodes for supplying energy thereto for diverting said powder from the respectively adjacent air port.

6. A device according to claim 5, wherein said energy supplying means applies D.C. voltage to said electrodes having the same polarity as said powder.

8. A device for handling dry developer powder adjacent a photosensitive medium comprising in combination: a container for said powder having an opening in the walls thereof disposed in close opposition to a surface of said medium, means in said container for effecting transfer of said powder through said opening relative to said medium, air ports disposed adjacent opposite margins of said opening, means for impelling air having a suction inlet and a pressure outlet, an air passage interconnecting said suction inlet with said air ports, means disposed in said air passage for separating said powder from a mixture of powder and air flowing through said passage, a pair of electrodes disposed respectively adjacent opposite air ports, and means coupled to said electrodes for supplying a D.C. voltage thereto having the same polarity as said powder.