Abstract:
The invention relates to a mechanism whereby individual sheets are fed from a cassette that carries a pile of paper sheets. The mechanism comprises a paper feed member which is mounted over the front portion of a feed bed whereon a cassette is removably installed and which is movable orbitally to feed sheets forward, and a retarding member engaged under upward bias against the feed member to prevent forward feed of sheets below one that is directly engaged with the feed member. The retarding member is so arranged as to be in its operative position when a cassette is fully installed on the feed bed but to move rearwardly and away from the feed member as the cassette is rearwardly removed from the feed bed, to thus release unfed but jammed sheets for removal with the cassette.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a paper feeding mechanism to be used with an electrophotographic copying apparatus or the like and, more particularly, to a paper feeding mechanism which includes a paper feed member for conveying copy paper and a retarding member adapted to be brought into abutting contact with the paper feed member. 
     2. Description of the Prior Art 
     In electrophotographic copying apparatus or the like, as is well known in the art, there has been used especially as a high speed paper feeding device a paper feeding mechanism of the type in which a paper feed member such as a paper feed roller is positioned in the vicinity of a paper feed bed on which is mounted a copy paper cassette that carries copy paper, and in which a retarding member is adapted to be brought into abutting contact with the surface of that paper feed member. In a paper feeding mechanism of this type, more specifically, plural sheets of copy paper are lifted off from the copy paper cassette by the paper feeding motions of the paper feed member, but only the uppermost sheet of the copy paper is fed past the retarding member, which holds back the sheets that are below the topmost one. According to the construction thus far described, however, plural sheets of copy paper are held jammed between the paper feed member and the retarding member even when the paper feeding mechanism is feeding no copy paper. As a result, in case the copy paper cassette is to be removed out of the paper feed bed, there is a tendency for the jammed copy paper to be left in the paper feeding mechanism. Upon replacement or the like of the copy paper cassette, therefore, there arises the inconvenience that each of the sheets left on the paper feed bed has to be manually cleared. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a mechanism for feeding sheets of copy paper one at a time out of a copy paper cassette that is removably supported on a paper feed member, said mechanism being of the type comprising a paper feed bed and a retarding member that is normally engaged under upward bias against the paper feed member, said mechanism being so arranged that the retarding member is spaced from the paper feed member whenever the paper feed bed does not have a copy paper cassette fully loaded onto it, so that sheets jammed between the paper feed member and the retarding member are released for removal with a copy paper cassette that is being taken off of the paper feed bed, and said mechanism being further so arranged that the retarding member is brought back into operative engagement with the paper feed member by proper loading of a copy paper cassette onto the paper feed bed. 
     Thus it is also an object of the present invention to provide a paper feeding mechanism of the character described wherein, when a copy paper cassette is being removed from the paper feed bed, all of the unfed sheets from that cassette that had been jammed between the paper feed member and the retarding member are automatically released from between those members for removal with that cassette. 
     Other objects and features of the present invention will be made apparent from the following description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view showing a paper feeding mechanism according to the first embodiment of the present invention; 
     FIG. 2 is a sectional view taken along line II--II of FIG. 1; 
     FIG. 3 is an explanatory view illustrating the operations of the same paper feeding mechanism; 
     FIG. 4 is a sectional view showing a paper feeding mechanism according to a second embodiment of the present invention; 
     FIG. 5 is a sectional view showing a paper feeding mechanism according to a third embodiment of the present invention; 
     FIG. 6 is an explanatory view illustrating the operations of the same paper feeding mechanism; 
     FIG. 7 is an exploded perspective view showing an essential portion of a copy paper cassette; 
     FIG. 8 is a sectional view showing a paper feeding mechanism according to a fourth embodiment of the present invention; 
     FIG. 9 is an explanatory view illustrating the operations of the same paper feeding mechanism; and 
     FIG. 10 is similar to FIG. 8 but shows a paper feeding mechanism according to a fifth embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 to 3 show a first embodiment of the present invention, in which a paper feed bed 2 of an electrophotographic copying apparatus generally indicated at reference numeral 1 is loaded with a copy paper cassette 3 carrying plural sheets of copy paper X. The copy paper cassette 3 is equipped with a bottom plate 4 for supporting the plural sheets of copy paper X thereon in a piled state. That bottom plate 4 is so constructed that it may be lifted, as shown in FIG. 1, by the action of a not-shown lifting member when the cassette 3 is completely loaded onto the paper feed bed 2. 
     Above the inner end portion 2a of the aforementioned paper feed bed 2, there is disposed a paper feed member which is exemplified by an endless belt 5. Specifically, this belt 5 is made to run on drive and driven pulleys 6 and 7, which are juxtaposed in a horizontal direction to each other, so that it is driven by the pulleys 6 and 7 in the direction of arrow A. 
     To the inner end portion 2a of the aforementioned paper feed bed 2, moreover, there is fixed a mounting plate 8 having a pivot pin 9, on which a retarding member 10 is supported in a rocking manner. To the head 10a of that retarding member 10, there is fixed a friction member 11 which is made of a material having a high friction resistance. This friction member 11 is adapted to be brought into abutting contact with the surface of the endless belt 5, as will be described hereinafter. Between the aforementioned mounting plate 8 and the ear 10b of the peeling member 10, there is interposed a tension spring 12, by which the peeling member 10 is biased in the direction of arrow B. 
     On the bottom wall 8a of the mounting plate 8, as shown in FIG. 2, there is anchored a pivot pin 13, on which an actuating member for sensing the presence of the copy paper cassette 3, i.e., an actuating lever 14, is supported. This actuating lever 14 has a follower portion 14a, which is so positioned within the moving range of the copy paper cassette 3 that it can be engaged by the front wall 3a of the same cassette, and it has an actuating portion 14b which is so positioned in the vicinity of the engaging portion 10c of the aforementioned retarding member 10 as to bring the friction member 11 into abutting contact with the surface of the endless belt 5 when the follower portion 14a is advanced by the front wall 3a of the copy paper cassette 3. 
     Since the paper feeding mechanism according to the foregoing embodiment has the construction thus far described, the retarding member 10 is rocked by the force of the tension spring 12, as shown in FIG. 3, in case the paper feed bed 2 not loaded with a copy paper cassette 3, so that it is spaced from the endless belt 5. As a result, when the copy paper cassette 3 is introduced onto the paper feed bed 2, the actuating lever 14 is turned on the pivot pin 13 by the front wall 3a of the same cassette 3 so that the retarding member 10 is rocked to the position shown in FIG. 1 by the actuation portion 14b of the actuating lever 14 until the friction member 11 comes into abutting contact with the surface of the endless belt 5. By the drive of this endless belt 5, therefore, plural sheets of copy paper X are partway lifted from the copy paper cassette 3 but only the uppermost sheet of copy paper X is fed out, the rest being held back by the retarding member 10. 
     As the copy paper cassette 3 is removed from the paper feed bed 2, moreover, the retarding member 10 is rocked by the force of the tension spring 12 in accordance with the withdrawal of the copy paper cassette 3, thereby to separate the friction member 11 from the endless belt 5 so that the copy paper clamped inbetween is discharged along with its cassette 3 to the outside of the copying apparatus. 
     FIG. 4 shows a paper feeding mechanism according to a second embodiment of the present invention, in which like constructional parts similar to those of the first embodiment shown in FIGS. 1 to 3 are indicated at like reference characters. The feature of the embodiment of FIG. 4 resides in the point that the aforementioned friction member 11 is replaced by a friction roller 17 which is supported on a center shaft 16 of the retarding member 10 through a one-way clutch 15. With this construction, specifically, the friction roller 17 can be readily rotated in the direction of arrow C so that the copy paper clamped between the friction roller 17 and the endless belt 5 can be discharged without any resistance when the copy paper cassette 3 is removed from the paper feed bed 2. 
     As has already been apparent from the description thus far made, according to the foregoing embodiment of the present invention, the retarding member is brought into abutting contact with the paper feed member in response to the introduction and extraction of the copy paper cassette so that all the sheets of copy paper can be recovered without fail. Moreover, the paper feeding mechanism of the present invention can enjoy the excellent advantages that its production cost is low and that it has few troubles because its construction is simple. 
     FIG. 5 shows a third embodiment of the present invention, in which the aforementioned copy paper cassette 3 is formed at its front portion, i.e., at its portion close to the inner end portion 2a of the paper feed bed 2 with a mounting bed 18 supporting thereon a retarding member 19 in a manner to be extendable and retractable. This retarding member 19 is constructed, as better seen from FIG. 7, to include a stem 19a, which is made slidable in the hole 20 of the mounting bed 18 but is blocked from coming out of the hole 20 by the action of a stopper 21 projected radially of that stem 19a. The retarding member 19 further includes a head 19b having an arcuate sliding surface 22, and a friction member 23 made of a material having a high friction resistance is embedded in a groove 22a which is formed in that head 19b. On the stem 19a of the aforementioned retarding member 19, there is mounted a compression spring 24 which has its one end seated upon the aforementioned mounting bed 18. As a result, the aforementioned retarding member 19 is biased to protrude by the force of the compression spring 24 thereby to bring its sliding surface 22 into abutting contact with the middle portion 5a of the endless belt 5 at all times. 
     Since the paper feeding mechanism according to the aforementioned embodiment has the construction thus far described, the retarding member 19 is brought into abutting contact with the middle portion 5a of the endless belt 5 by the force of the compression spring 24 when the paper feed bed 2 is loaded with the copy paper cassette 3. As a result, the sheets of copy paper X in their cassette 3 are partway lifted off in the direction of the arrow A by the movement of the endless belt 5 in the direction A but the retarding member 19 allows only the uppermost sheet of copy paper X to be fed. 
     When the copy paper cassette 3 is withdrawn from the paper feed bed 2 in the direction of arrow D of FIG. 6, the retarding member 19 moves, while being held in abutting contact with the surface of the endless belt 5, so that the copy paper X clamped between the endless belt 5 and the retarding member 19 moves along with its cassette 3. This keeps the paper feeding mechanism clear of any of the copy paper X when the copy paper cassette 3 is extracted. 
     As has already been apparent from the description thus far made, according to the present invention, no copy paper is left in the paper feeding mechanism when the copy paper cassette 3 is removed from the paper feed bed 2. In addition, since the friction member 23, which is liable to be heavily worn, is attached to each copy paper cassette 3, the frequency of its replacement is reduced, and the replacement itself can be conducted outside of the paper feeding mechanism, thus making it possible to enjoy an advantage that the replacing work is simplified. 
     FIGS. 8 and 9 show a fourth embodiment of the present invention, in which a reduced end 29a of a retarding member 29 having an egg-shaped section is supported in a rocking manner on the pivot pin 9 of the mounting plate 8. To the other or enlarged end 29b of the aforementioned retarding member 29, there is fixed a friction member 30 which is made of a material having a high friction resistance and which is adapted to come into abutting contact with the midway portion 5a of the endless belt 5. Between the retarding member 29 and the mounting plate 8, moreover, there is mounted a tension spring 31, by which the aforementioned friction member 30 is brought into abutting contact with the midway portion 5a of the endless belt 5. 
     According to the present embodiment, on the other hand, a permanent magnet 32 is fixed to that side of the retarding member 29, which is located to face the aforementioned copy paper cassette 3, and an iron member 33 is correspondingly fixed to the front wall 3a of the copy paper cassette 3. 
     Since the present embodiment has the construction thus far described, the sheets of copy paper X are extracted from their cassette 3 by the drive of the endless belt 5 and the uppermost one is fed by the existence of the friction member 30. When the copy paper cassette 3 is extracted from the paper feed bed 2 in the direction of arrow D of FIG. 9, moreover, the retarding member 29 is rocked in the direction of the arrow B against the force of the tension spring 31 by the attraction which is established between the permanent magnet 32 and the iron member 33. As a result, the friction member 30 is separated from the surface of the midway portion 5a of the endless belt 5 so that the copy paper X clamped inbetween is released from its restriction and can be extracted together with its cassette 3 to the outside of the copying apparatus. If the copy paper cassette 3 is continuously pulled, incidentally, the force of the tension spring 31 overcomes the attraction of the permanent magnet 32 so that the retarding member 29 restores its position shown in FIG. 8. 
     FIG. 10 shows a fifth embodiment of the present invention, in which like constructional parts similar to those of FIG. 8 are indicated at like reference characters. The feature of the embodiment of FIG. 10 resides in a point that the aforementioned combination of the permanent magnet 32 and the iron member 33 is replaced by the combination of a hook 35, which is hinged to the retarding member 29 by means of a pivot pin 34, and a retaining pin 36 which is so anchored at the copy paper cassette 3 that it can engage with the aforementioned hook 35. With the construction thus far described, therefore, the friction member 30 of the retarding member 29 is separated temporarily upon the extraction of the copy paper cassette 3 from the surface of the endless belt 5 so that the operational effect similar to that described with reference to FIG. 9 can be attained. 
     Here, the present invention should not be limited to the constructions of the embodiments thus far described but can be modified such that a surface fastener is provided between the copy paper cassette 3 and the retarding member 29. 
     As has already been apparent from the description thus far made, according to the present invention, the retarding member is separated temporarily upon the extraction of the copy paper cassette from the paper feed member so that the copy paper X clamped inbetween is removed to the outside of the copying apparatus while being carried on its cassette. As a result, it is possible to spare the time for removal of the residual copy paper, if any, and to prevent in advance the trouble which is caused by the existence of that residual copy paper. 
     Since the present invention has a simple construction, moreover, it can enjoy an advantage that its production cost will not be high.