DELIVERY UNIT ATTACHING STRUCTURE

Abstract: The housing (1) of a delivery unit (A) is en­ gaged with a predetermined part of the body (B) of an image forming apparatus, the housing (1) being remova­ ble from the body (B). An endless belt (2) mounted on the housing (1) is wound on a pair of pulleys (4), (6). One of the pulleys (4),(6) has a first shaft (5) secured to the housing (1), while the other pulley (4) has a second shaft (3) diametrically movable with re­ spect to the housing (1). The second shaft (3) is at­ tached to the body (B) with the endless belt (2) stretched to restrain the housing (1) from being re­ moved from the body (B). The second shaft (3) is re­ movable from the body (B). The delivery unit (A) is attached without use of screws. Accordingly, the deli­ very unit (A) may be readily attached to the body (B) with no possibility of the photoreceptor being dam­ aged. In an image forming apparatus having electric component elements disposed under the delivery unit (A), the maintenance of the elements can be facili­ tated.

Description: BACKGROUND OF THE INVENTION The present invention relates to a delivery unit attaching structure for attaching, to the body of an image forming apparatus, a delivery unit having endless belts for deliverying transfer paper from the photoreceptor to the fixing device. To make efficient use of an office space, it has been recently desired to make, in a smaller size, the body of an image forming apparatus such as an electrophotographic copying apparatus, with the functions thereof yet remaining intact. In an electrophotographic copying apparatus for example, in order to reduce the body thereof in depth, it is proposed to dispose, in the space under the delivery device which is relatively wide, the electric component elements such as the power transformer, the power board and the like which have been conventionally attached to the rear plate of the body of the copying apparatus. In this case, each time the electric component elements are to be maintained, it is required to remove the delivery device from the body of the copying apparatus. In a conventional delivery device using endless belts, a drive shaft and a follower shaft respectively rotatable integrally with a pair of rollers on which the endless belts are wound, are supported, through bearings, by shaft supporting members attached to the lateral plates of the body of the copying apparatus. Accordingly, when maintaining the electric component elements in this delivery device, it is required to remove the endless belts, the drive shaft, the follower shaft and the like from the lateral plates of the apparatus body. Thus, the delivery unit presents a serious inconvenience to frequent maintenances. There is also known another delivery device in which the main portions thereof are previously assembled, as a delivery unit, in the housing, which is then screwed to the body of the copying apparatus when the same is entirely assembled. In this delivery device, the manhour required for maintaining the electric component elements, is slightly reduced. However, it is still required to carry out a screw-driving operation in a limited space in the body of the copying apparatus. This is troublesome and involves the likelihood that the photoreceptor is damaged by a screwdriver during the screw-driving operation. SUMMARY OF THE INVENTION It is an object of the present invention to provide a delivery unit attaching structure which facilitates the removal and attachment of a delivery unit and prevents the photoreceptor from being damaged when removing or attaching the delivery unit. The object above-mentioned may be achieved by providing the following delivery unit attaching structure as defined in claim 1. The delivery unit attaching structure for attaching, to the body of an image forming apparatus, a delivery unit having an endless belt for deliverying paper, comprises: a delivery unit housing removably engaged with a predetermined part of said body; and a pair of pulleys on which the endless belt is wound, one of the pulleys having a first shaft which is supported by the housing and of which diametrical movement is restrained by the housing, the other pulley having a second shaft diametrically movable with respect to the housing, the second shaft attached to the body of the image forming apparatus so that the diametrical movement of the second shaft is restrained, the second shaft being removable from the apparatus body, and the second shaft being adapted to apply tension to the endless belt to restrain the housing from being removed from the apparatus body. According to the delivery unit attaching structure having the arrangement above-mentioned, the delivery unit may be readily attached to the body of the image forming apparatus by engaging the housing with a predetermined part of the apparatus body with the diametrically movable second shaft attached to the apparatus body to apply tension to the endless belt. The tension applied to the endless belt prevents the housing from being removed from the body of the image forming apparatus. The housing may be removed from the apparatus body by removing the second shaft from the apparatus body or by stretching the endless belt thereby to disengage the housing from the predetermined part of the apparatus body. Preferably, either the first shaft or the second shaft may be a drive shaft for driving the endless belt. In this case, drive tension may be applied to the endless belt while the endless belt being driven. This further prevents the housing from being removed from the apparatus body. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side view of a delivery unit attached to the lateral plates of the body of an image forming apparatus; Figure 2 is a view illustrating in detail an engagement projecting piece and a pawl engaged therewith; Figure 3 is an exploded perspective view of the delivery unit; Figure 4 is a schematic perspective view of the delivery unit which is about to be attached; and Figure 5 is a schematic view of another example of the delivery unit. DESCRIPTION OF THE PREFERRED EMBODIMENT The following description will discuss in detail an embodiment of the present invention with reference to the attached drawings. In Fig. 1, a delivery unit A is attached to the body B of an electrophotographic copying apparatus. With such attachment, the removal of the delivery unit A from the body B is restrained by tension of endless belts 2. As shown in Fig. 3, the delivery unit A includes a housing 1 having an upper housing 11 and a lower housing 12, a plurality of endless belts 2, pulleys 4 and 6 on which the endless belts 2 are wound, a drive shaft 3 on which the pulleys 4 are put, and a follower shaft 5 on which the pulleys 6 are put. The upper housing 11 has a longitudinal section in a substantially reversed U-shape. The upper housing 11 is provided in the top surface 13 thereof with slits 14 through which the endless belts 2 are respectively exposed. The upper housing 11 is provided at each end 11a thereof with a pair of horizontal engagement projecting pieces 15. Each of the engagement projecting pieces 15 is engaged with each of pawls 21 formed on each lateral plate 20 of the body B of the electrophotographic copying apparatus. A pair of insertion holes 18 are formed in the top surface 13 of the upper housing 11. The lower housing 12 is made in the form of a container having an opening at its upper portion, which may be assembled with the upper housing 11. The lower housing 12 is provided on the bottom 16 thereof with a pair of supporting ribs 17 to which bearings 9 are respectively attached. The supporting ribs 17 support the ends 51, 52 of the follower shaft 5 together with the bearings 9. The lower housing 12 has a peripheral side wall 19 which is broken around the drive shaft 3. This per mits the drive shaft 3 to be diametrically moved together with the pulleys 4 on which the endless belts 2 are wound. Both ends 31, 32 of the drive shaft 3 project outside of the housing 1. The lower housing 12 has a pair of finger hanging projections 30 which upwardly project through a pair of insertion holes 18 of the upper housing 11 when the lower housing 12 and the upper housing 11 are assembled with each other. The housing 1 is assembled with the lower housing 12 resiliently held by the upper housing 11. This facilitates the assembling of the housing 1. Alternatively, the upper housing 11 and the lower housing 12 may be assembled with each other with screws or rivets. The lateral plates 20 stand from the bottom of the body B of the copying apparatus. A pair of pawls 21 above-mentioned are vertically extended from the top of each lateral plate 20. In Fig. 2, each pawl 21 is provided at the right hand thereof with a projecting portion 22. Between the projecting portion 22 and the top surface 20a of each lateral plate 20, there is formed a gap 26 in which each engagement projecting piece 15 is held. Each projecting portion 22 is provided on the upper end thereof with a guide surface 22a which is inclined such that the height thereof is lowered in the rightward direction. This enables the engagement projecting pieces 15 to be readily engaged with the pawls 21 by downwardly moving the engagement projecting pieces 15 along the inclined guide surfaces 22a. Gaps 25 are formed for machining the engagement projecting pieces 15. One of the lateral plates 20 has an insertion hole 23 for fixing one end 31 of the drive shaft 3 together with a bearing 7. The other lateral plate 20 has a groove 24 for fixing the other end 32 of the drive shaft 3 together with another bearing 7, the groove 24 being inclined in the leftward direction in Fig. 1. The width of the groove 24 at the inlet side is so narrowed as to prevent the movement of the bearing 9 (See Fig. 3). In this embodiment, one end 31 of the drive shaft 3 is first inserted in and fixed to the bearing 7 fitted in the insertion hole 23 in one lateral plate 20, and the other end 32 of the drive shaft 3 is then inserted into the groove 24. With such a state, the bearing 7 is inserted into the groove 24 while the bearing 7 is fitted to the other end 32 of the drive shaft 3, so that the other end 32 is fixed. Gears 8 for drive transmission to a drive device (not shown) are attached to one end 31 of the drive shaft 3. As shown in Fig. 4, the follower shaft 5 is downwardly rotated around the center of the drive shaft 3 of the delivery unit A, so that the engagement projecting pieces 15 of the upper housing 11 are respectively engaged with the pawls 21 of the lateral plates 20. Thus, the delivery unit A may be readily attached to the body B of the electrophotographic copying apparatus. At this time, by merely pushing down the upper housing 11, the engagement projecting pieces 15 are moved along the inclined guide surfaces 22a, enabling the endless belts 2 to be once stretched. Accordingly, the engagement of the engagement projecting pieces 15 with the pawls 21 may be readily made with a single operation. With such an engagement, tension is applied to the endless belts 2 so that the engagement above-mentioned is securely maintained. This securely prevents the housing 1 from being removed from the body B of the copying apparatus. Further, while the endless belts 2 are being driven, drive tension is applied to the endless belts 2. This further prevents the housing 1 from being removed from the copying apparatus body B. For removing the delivery unit A from the copying apparatus body B, the housing 1 may be pulled in such a direction as to be separated away from the drive shaft 3 with a pair of projections 30 caught by the fingers. This causes the endless belts 2 to be once stretched to disengage the engagement projecting pieces 15 from the pawls 21. Thus, the delivery unit A may be readily removed from the copying apparatus body B. Since the delivery unit A is attached to the copying apparatus body without use of screws, the present invention may overcome the defect of a conventional arrangement in which the delivery unit is screwed, i.e., the defect that the photoreceptor may be damaged by a screwdriver. Also, in an electrophotographic copying apparatus having electric component elements, such as the power transformer and the like, disposed under the delivery unit in order to make the apparatus body in a small size, the maintenance of the electric component elements may be facilitated since the delivery unit may be readily attached and removed. Accordingly, the delivery unit attaching structure of the present invention is suitable to make the copying apparatus body in a small size. The delivery unit attaching structure in accordance with the present invention should not be limited to the embodiment above-mentioned, but a variety of modifications of the invention may be made without departing from the scope thereof as defined in the claims. For example, the lower housing 12 may be engaged with the bottom of the copying apparatus body B, a groove identical with the groove 24 may be used instead of the insertion hole 23, and the drive shaft 3 is secured to the housing 1 while the follower shaft 5 is so arranged as to be diametrically rotatable and attached to the lateral plates 20. Further, to apply tension to the endless belts 2, a tension roller may be disposed between the drive shaft 3 and the follower shaft 5. Such an arrangement further increases the tension applied to the endless belts 2, thereby to further prevent the housing 1 from being removed. Further, between the drive shaft 3 and the follower shaft 5, a pushing-up roller 70 may be disposed for pushing up the inner peripheral surfaces 2b of the endless belts 2 to make the delivery surfaces 2a of the endless belts 2 in the form of a mountain. According to such an arrangement, hard and short copying paper P may be smoothly introduced between a fixing roller 71 and a pressing roller 72. More specifically, the copying paper P is introduced along the front lowered portions 2c of the delivery surfaces 2a with the rear end Pb of the paper P pushed up, i.e., with a small introducing angle ϑ of the copying paper P with respect to the fixing roller 71. Further, the endless belts may be toothed, and the pulleys may be grooved. According to the delivery unit attaching structure of the present invention, the delivery unit may be readily attached and removed by engaging or disengaging the housing with or from the body of an image forming apparatus, and there is no possibility of the photoreceptor being dmaged by a screwdriver as done in the arrangement in which the housing is screwed to the body of an image forming apparatus. A first shaft supporting one pulley out of a pair of pulleys on which the endless belt is wound, is fixed to the housing, while a second shaft supporting the other pulley is diametrically movable with respect to the housing. The second shaft is attached to the body of the image forming apparatus with tension applied to the endless belt. This assures the characteristic effect that the tension applied to the endless belt securely prevents the housing from being removed.

Claims: A delivery unit attaching structure for attaching, to the body (B) of an image forming apparatus, a delivery unit (A) having an endless belt (2) for deliverying paper, comprising: a delivery unit housing (1) removably engaged with a predetermined part of said body (B); and a pair of pulleys (4), (6) on which the endless belt (2) is wound, one of the pulleys (4), (6) having a first shaft (5) which is supported by said housing (1) and of which diametrical movement is restrained by said housing (1), the other pulley (4) having a second shaft (3) diametrically movable with respect to said housing (1), when said housing is removed from said body said second shaft (3) attached to said predetermined part of said body (B) so that the diametrical movement of said second shaft (3) is restrained, said second shaft (3) being removable from said body (B), and said second shaft (3) being adapted to apply tension to said endless belt (2), thereby to restrain said housing (1) from being removed from said predetermined part of said body (B). A delivery unit attaching structure as set forth in Claim 1, wherein either one of the first and second shafts (5), (3) is a drive shaft for driving the endless belt (2). A delivery unit attaching structure as set forth in Claim 1, wherein the housing (1) includes an upper housing (11) and a lower housing (12) assembled with said upper housing (11). A delivery unit attaching structure as set forth in Claim 3, wherein a pair of engagement projecting pieces (15) formed at each of both ends of the upper housing (11) are respectively engaged with pawls (21) formed on each of the upper end surfaces (20a) of a pair of lateral plates (20) of the predetermined part of said body (B) of an image forming apparatus. A delivery unit attaching structure as set forth in Claim 4, wherein the pawls (21) have inclined guide surfaces (22a) for guiding the engagement projecting pieces (15) to said pawls (21). A delivery unit attaching structure as set forth in Claim 1, wherein one end (32) of the second shaft (3) is engaged with a groove (24) formed in a lateral plate (20) of the predetermined part of said body (B) of an image forming apparatus and said second shaft (3) is removable from said groove (24). A delivery unit attaching structure as set forth in Claim 1, wherein a tension roller for applying tension to the endless belt (2) is disposed between the first and second shafts (5), (3). A delivery unit attaching structure as set forth in Claim 1, wherein a pushing-up roller (70) is disposed between the first and second shafts (5), (3), said roller (70) being adapted to push up the inner peripheral surface (2b) of the endless belt (2), thereby to make the delivery surface (2a) of said endless belt (2) in the form of a mountain. An image forming apparatus having electric component elements disposed under a delivery unit attaching structure (A) as defined in Claim 1.

Inventors: WATASHI, MASAHIRO
Applicants: MITA INDUSTRIAL CO. LTD.
Application year: 1990
Main classification: G03G15
IPC codes: G03G15, B65H29