Automatic sheet feeding device

Abstract: An automatic sheet feeding device includes a driving roller (13) and a pressing roller (15)pressing a printed sheet against the driving roller (13). The printed sheet is guided between the driving roller (13) and the pressing roller (15) by a sheet guide fixed to the automatic sheet feeding device or a leaf spring (14) for supporting the pressing roller (15).

Description: The present invention relates to an automatic sheet feeding device capable of feeding a printing sheet to a printer and collecting and stacking the sheet printed by the printer. The automatic sheet feeding device has conventionally been employed to continuously feed a plurality of cut printing sheet to the printer. Such prior art automatic sheet feeding device is generally composed of four elements, namely, a hopper portion for storing the printing paper, a sheet feeding portion for feeding the printing sheet one by one to the printer, a sheet collecting portion for collecting the sheet printed and discharged by the printer and a stacking portion for stacking the collected sheet. The sheet collecting portion is composed of a driving roller for rotating synchronously with a sheet feed mechanism of the printer, a pressing roller for rotatably bringing into contact with the driving roller, and a sheet guide for guiding the printed sheet discharged from the printer between the driving roller and the pressing roller. In the sheet collecting portion, the pressing roller is pressed against the driving roller by a pressing means having resilience such as a leaf spring. Hence, even if a fixing position or an outer diameter of the driving roller is inappropriate or varied, the pressing roller is always kept in pressing against the driving roller. It is the same when the driving roller is abraded or worn. Although the pressing roller moves accompanied by the movement of the driving roller, the guide for guiding the sheet between the driving roller and the pressing roller does not move. Hence, the sheet guide can not function properly. As a result, the sheet is not entered into and guided by the driving roller and the pressing roller but liable to be bent just before entering between the driving roller and the pressing roller. The present invention has been made in view of the drawbacks of the prior art automatic sheet feeding device set forth above. Accordingly, it is an object of the present invention to provide an automatic sheet feeding device capable of guiding the printed sheet between the driving roller and the pressing roller without bending the printed sheet even if the fixing position or the diameter of the driving roller is different from the designed value thereof or varied. The above object is achieved by the features included in the characterizing portion of claim 1. The pending claims 2-4 respectively characterize advantageous developments thereof. According to the main aspect of the invention, the printed sheet is guided between the driving roller and the pressing roller by the sheet guide or by the leaf spring, wherein the printed sheet is guided by that leaf spring only when the leaf spring is flexed to a certain degree such that the angle of impact between the printed sheet and the pressing roller is kept small. The above and other objects, features and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings. Fig. 1 is a perspective view showing an automatic sheet feeding device; Fig. 2 is a perspective view of assistance in explaining a state where the automatic sheet feeding device of Fig. 1 is mounted on a printer; Fig. 3 is a schematic perspective view of assistance in explaining a sheet collecting portion of the automatic sheet feeding device of Fig. 1; Fig. 4 is a schematic perspective view of assistance in explaining a portion adjacent to a driving roller of the sheet collecting portion of Fig. 3; Fig. 5 is a side sectional view of assistance in explaining the sheet collecting portion of Fig. 3 wherein a sheet is guided by a guide rib; and Fig. 6 is a side sectional view of assistance in explaining the sheet collecting portion of Fig. 3 wherein a sheet is guided by a leaf spring. An automatic sheet feeding device according to a preferred embodiment of the present invention will be described with reference to Figs. 1 through 6. In Figs. 1 and 2, the automatic sheet feeding device to be mounted on a printer 9 comprises a hopper 1 for storing a cut printing sheet, a hopping roller 2 positioned in front of the hopper 1 for feeding the printing sheet stored in the hopper 1 to the printer 9, a motor 3 positioned at the side of a frame of the automatic sheet feeding device for driving the hopping roller 2, a stacker 4 positioned in front of the hopping roller 2 for stacking the sheet printed by the printer 9, a sheet collector 5 positioned in front of the stacker 4 for feeding the sheet printed by the printer 9 to the stacker 4, a driven gear 6 for transmitting the driving force to the sheet collector 5, an idle gear 7 meshing the driven gear 6, and a plate 8 engaged with the printer 9, a driving gear 11 rotatable integrally with a platen 10 of the printer 9 and meshing with the idle gear 7, a shaft 12 rotatable integrally with the driven gear 6, a driving roller 13 rotatable integrally with the shaft 12, a leaf spring 14, a pressing roller 15 rotatably supported by the leaf spring 14, a motor 16 for rotating the platen 10, and a bail roller 17 for pressing against and contacting the platen 10. A printed sheet is discharged from the printer 9 and passed the sheet collector 5 and fed to the stacker 4 where the printed sheet is stacked. With the arrangement of the automatic sheet feeding device, when the hopping roller 2 is rotated by the motor 3 the printing sheet is fed from the hopper 1 toward the platen 10. When the platen 10 is rotated by the motor 16 the printing sheet moves along the platen 10 while the printing sheet is printed. The printed sheet is pressed by the bail roller 17 against the platen 10 and enters into the sheet collector 5 and thereafter clamped by the driving roller 13 and the pressing roller 15. The driving roller 13 engages with the platen 10 via the shaft 12, the driven gear 6, the idle gear 7 and the driving gear 11. The driving roller 13 is rotated in synchronism with the platen 10 at substantially the same peripheral speed as that of the platen 10. The printed sheet is fed to the stacker 4 by the driving roller 13 and stacked therein. The sheet collector 5 is schematically illustrated in Fig. 3. In the same figure, the sheet collector 5 comprises the sheet guide 18 integrally formed with the sheet collector 5 and a guide rib 19 integrally formed with the sheet guide 18. The sheet guide 18 and the guide rib 19 respectively guide the sheet between the driving roller 13 and the pressing roller 15. The portion adjacent to the driving roller 13 is schematically illustrated in Fig. 4. The sheet guide 18 is integrated with a cylindrical projection 20 and the leaf spring 14 is integrated with teeth 21. The teeth 21 are arranged annularly and define a circular hole at the central portion thereof. The circular hole has a diameter less than that of the cylindrical projection 20. Hence, the teeth 21 engage with the projection 20 for keeping the engagement between the leaf spring 14 and the sheet guide 18. The leaf spring 14 has a sheet guide portion 14a and a folded portion 14b having an acute angle relative to an end thereof fixed to the sheet guide 18. The leaf spring 14 is bent between the folded portion 14b and the free end thereof in the direction toward the driving roller 13. The sheet guide portion 14a is formed on the folded portion and capable of guiding the sheet between the driving roller 13 and the pressing roller 15 accompanied by the variation of the fixing position of the pressing roller and the diameter of the pressing roller 15. A printed sheet 22 is guided by the guide rib 19 as illustrated in Fig. 5. In the same figure, when a tip end 22a of the printed sheet 22 reaches the pressing roller 15 an incident angle of ϑ₁ is generated between the tip end 22a and the surface of the pressing roller 15. The incident angle of ϑ₁ is equal to an angle between a lower surface 19a of the guide rib 19 and the surface of the pressing roller 15. The incident angle ϑ₁ is set to be such a small value that the printed sheet is not prevented from being smoothly guided between the driving roller 13 and the presing roller 15. When the driving roller 13 is deviated to the direction of the arrow A in Fig. 6, the pressing roller 15 is moved toward the arrow B. At that time, the tip end 22a of the printed sheet 22 is guided by the sheet guide portion 14a between the driving roller 13 and the pressing roller 15. At this time, the incident angle becomes ϑ₂ which is substantially same as the incident angle of ϑ₁ in Fig. 5. Accordingly, the printed sheet 22 is smoothly guided between the driving roller 13 and the pressing roller 15 irrespective of an incident angle ϑ₃ between the lower surface 19a of the guide rib 19 and the surface of the pressing roller 15 which is greater than the incident angle ϑ₁ in Fig. 5. Although the invention has been described in its preferred form with a certain degree of particularity, it is to be understood that many variations and changes are possible in the invention without departing from the scope thereof.

Claims: An automatic sheet feeding device adapted to be mounted on a printer comprising: a stacker (4) for stacking a sheet printed by the printer; a driving roller (13) for feeding the printed sheet to the stacker (4); a pressing roller (15) for pressing the printed sheet against the driving roller (13); a sheet guide (18) fixed to the automatic sheet feeding device and positioned under the driving roller (13) for guiding the printed paper between the driving roller (13) and the pressing roller (15); a leaf spring (14) having one end fixed to the sheet guide (18) by a projection (20) of the sheet guide (18) and another end for rotatably supporting and urging the pressing roller (15) against the driving roller (13), said leaf spring (14) having a folded portion (14b) which is folded in acute angle relative to the end of the leaf spring (14) which is fixed to the sheet guide (18), wherein the pressing roller (15) is held between the folded portion (14b) and the driving roller (13) through the leaf spring (14), characterized in that the printed sheet is guided between the driving roller (13) and the pressing roller (15) by the sheet guide (18) or by said leaf spring (14), wherein the printed sheet is guided by said leaf spring (14) only when the leaf spring (14) is flexed to a certain degree such that the angle of impact between the printed sheet and the pressing roller (15) is kept small. An automatic sheet feeding device according to Claim 1, wherein the driving roller (13) is rotated in synchronism with the movement of the sheet feeding mechanism of the printer. An automatic sheet feeding device according to Claim 2, wherein the sheet guide (18) is provided with a guide rib (19) for guiding the printed sheet between the driving roller (13) and the pressing roller (15). An automatic sheet feeding device according to Claim 3, wherein the leaf spring (14) has two divided portions which support both ends of the pressing roller (15).

Inventors: MIZUTANI MINORU C O OKI ELECTR, SAITO TOSHIAKI C O TOHOKU OKI, WATANABE SHYOICHI C O OKI ELEC, MIZUTANI, MINORU C/O OKI ELECTRIC IND. CO., LTD., SAITO, TOSHIAKI C/O TOHOKU OKI ELECTRIC CO., LTD., WATANABE, SHYOICHI C/O OKI ELECTRIC IND. CO., LTD.
Applicants: OKI ELECTRIC IND CO LTD, OKI ELECTRIC INDUSTRY CO., LTD.
Application year: 1989
Main classification: B41J13
IPC codes: B41J13, B65H5, B65H29