JP3358673B2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a printer, a copier,
The present invention relates to a sheet feeding device used for a sheet using device such as a facsimile machine and a printing machine. Specifically, paper is inserted into a paper cassette, stacked on a bottom plate, the bottom plate is rotated to lift the leading edge of the stacked paper, and the paper is sequentially fed one by one from the top by rotation of a paper feed roller. It relates to a paper device.

[0002]

2. Description of the Related Art Conventionally, this type of paper feeder balances the number (weight) of sheets stacked on a bottom plate of a paper feed cassette with a pushing force for pushing up the bottom plate, thereby providing a top sheet of paper. Has been devised such that the paper feed pressure for pressing the paper to the paper feed roller is substantially constant.

[0003]

However, there is no problem when only one type of paper is used, but when there are various sizes of paper to be used, the weight applied to the bottom plate changes according to each size, and the bottom plate is pushed up. The paper feed pressure changes due to the influence of the push-up force. For example, when 250 sheets of large size paper such as A3 size are stacked,
The sheet feeding pressure changes greatly when 250 sheets of a small size such as the size are stacked. If the feeding pressure of small-sized paper such as B5 size or A4 size is set to be substantially constant, there is a problem that the feeding pressure becomes insufficient in the case of a large size, causing non-feeding. Conversely, if the feeding pressure of a large size such as A3 size is set to be substantially constant, there is a problem that the feeding pressure is too large in the case of a small size and double feeding occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper feeding apparatus that keeps the paper feeding pressure constant regardless of the size of the paper used.

[0005]

For this purpose, the present invention has the following features.
The paper S is inserted into the paper cassette 20 and stacked on the bottom plate 35, the bottom plate 35 is rotated to lift the leading end of the stacked paper S, and the stacked paper S is sequentially rotated from above by the rotation of the paper feed roller 19. In the sheet feeding device 18 that feeds out one sheet at a time, the bottom plate extending / contracting means 33 that allows the bottom plate 35 to extend and contract to a length substantially equal to the stacking paper S, and the intermediate position of the length extended and contracted by the bottom plate extending / contracting means 33 as a fulcrum A bottom plate supporting means 29 for supporting the bottom plate 35 so as to be rotatable up and down; an interlocking means 47 for moving the fulcrum to the intermediate position in conjunction with an extension / contraction operation by the bottom plate extension / contraction means 33; And a bottom plate urging means 39 for moving the front end side with a substantially constant urging force.

[0006]

According to the present invention, when the sheet S is set in the sheet feeding cassette 20, the bottom plate 35 is extended and contracted by the bottom plate extending / contracting means 33 to a length substantially equal to the set sheet S, and the bottom plate is linked with the extension / contraction operation. The fulcrum is moved to an intermediate position with a length of 35. Then, the set sheet S is stacked on the bottom plate 35, and the bottom plate 35 supported by the bottom plate support means 29 is rotated by the bottom plate urging means 39 to lift the leading end side of the stack paper S, and By rotation, the stacked sheets S are sequentially sent out one by one from the top.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 shows a schematic configuration of an entire internal mechanism of a laser printer having a paper feeding device according to an embodiment of the present invention.

The reference numeral 10 in the drawing denotes a printer main body. The printer body 10 includes an upper body 10a and a lower body 1
0b, and the upper body 10a can be freely opened and closed about the rotation fulcrum 11 on the lower body 10b.

In the printer body 10, a belt-shaped photosensitive member 12 is provided substantially at the center. Around the photoreceptor 12, the charger 13 and the developing device 1 are driven in the driving directions indicated by arrows in the drawing.
4. The transfer device 15 and the cleaning device 16 are arranged. An optical writer 17 is disposed above the charger 13 and the cleaning device 16. On the other hand, the transfer device 15
Below the cleaning device 16 is provided a sheet feeding device 18 according to the present invention.

When recording is performed using the illustrated laser printer, the paper S loaded in the paper cassette 20 by rotating the paper feed roller 19 in the paper feed device 18 is indicated by an arrow A. The sheet is sent out in the sheet feeding direction, and is conveyed by the respective conveying roller pairs 21 and 22 to be transferred to the registration roller pair 23.
Stop in the middle. Then, the registration roller pair 23
The sheet is conveyed to the lower side of the photoreceptor 12 in a timely manner.

The photosensitive member 12 is driven in a clockwise direction as indicated by an arrow. At this time, the surface of the photosensitive member 12 is uniformly charged by a charger 13 and irradiated with a laser beam from an optical writer 17.
2 to form an electrostatic latent image. Then, when passing through the position of the developing device 14, the electrostatic latent image is visualized by toner, and the visible image is transferred by the transfer device 15 to the upper surface of the sheet conveyed below the photoconductor 12.

After the image transfer, the sheet is conveyed to a fixing device 24, where the transferred image on the sheet is fixed.
The sheet exiting the fixing device 24 is discharged in the direction of arrow B in FIG.

On the other hand, the photoreceptor 12 after the image transfer is cleaned by a cleaning device 16 to remove residual toner, and thereafter, is discharged by a discharger.

In the sheet feeding device 18 of the present invention, the sheet feeding cassette 20 is detachably provided from a mounting opening (not shown) of the lower main body 10b which is opened on the near side in the drawing.

The sheet cassette 20 has a direction C shown in FIG. 4 as a sheet feeding direction and an arrow D direction in the drawing as a detaching direction. The cassette case 20A has a rectangular frame shape slightly longer in the sheet feeding direction. Form. The side plates 20a on both sides in the sheet feeding direction of the cassette case 20A include:
As shown in FIGS. 1 and 2, a slide rail 20 b provided on the bottom plate support means 29 is provided. The slide rail 20b is provided at an intermediate portion of the length of the side plate 20a so as to protrude inward from the inner surface. Also, the slide rail 20
At the rear of b, a locking projection 20c is provided to protrude inward from the inner surface of the side plate 20a, and at the front, another locking protruding portion 20e is provided to protrude inward from the inner surface of the front plate 20d.

Sliders 30 and 31 are movably provided on the slide rails 20b on both sides. The sliders 30 and 31 are long in the sheet feeding direction and formed in a U-shape in vertical section. As shown in FIG. 1, one slider 30 is provided with a shaft 30a protruding downward at one front end in the longitudinal direction, and another shaft 30b is provided protruding inward, and is further provided with a front end from the front end face. Is provided with a locking projection 30c. The pulley 3 is connected to the shaft 30a.
2 is rotatably supported. The other slider 31
As shown in FIG. 2, a shaft hole 31a is formed in the inner surface of the front end portion, and a shaft 31b is provided in a substantially middle portion so as to protrude inward from the inner surface.

A bottom plate 35 is provided between the sliders 30 and 31 on both sides as shown in FIG. The bottom plate 35
The lower bottom plate 36, the middle bottom plate 37, and the upper bottom plate 38 having a flat plate shape and substantially the same length.

The lower bottom plate 36 has engaging pieces 36 on both sides of the rear end.
a is bent downward and a positioning piece 36b is cut and raised substantially at the middle of the rear end. On both sides of the lower bottom plate 36, two long holes 36c which are long in the sheet feeding direction are provided in parallel.

Next, the midsole plate 37 is provided with a notch 37a substantially at the middle of the rear end, and a guide piece 37b is provided inwardly protruding from both open edges of the notch 37a. One of the guide pieces 37b is bent into a U-shape when viewed from the sheet feeding direction, and the other is bent into an L-shape. Further, two long holes 37c long in the sheet feeding direction are provided in parallel on both sides of the midsole plate 37. Further, on both side edges of the midsole plate 37, a support piece 37d is provided at a substantially middle position by being bent downward at a right angle. One of the support pieces 37d is provided with a shaft hole 37e, and the other is provided with a shaft 37f protruding outward. The shaft 37f is shaped like a letter D in vertical section and only the tip is circular in vertical section.

Finally, the upper bottom plate 38 is provided with guide pieces 38a protruding rearward on both sides of the rear end. Guide piece 38a
One is bent into a U-shape similarly to the guide piece 37b, and the other is bent into an L-shape.

Then, the middle bottom plate 37 is placed on the lower bottom plate 36, the positioning piece 36b is inserted into the notch 37a, and the guide piece 37b is inserted into the long hole 36c, and the lower bottom plate 36 and the middle bottom plate 37 are inserted into the long hole 36c. It is provided to extend and contract along. Further, the upper bottom plate 38 is placed on the middle bottom plate 37,
The guide piece 38a is inserted into 7c, and the middle bottom plate 37 and the upper bottom plate 38 are provided so as to be extendable and contractable along the long hole 37c. The elongated holes 36c and 37c and the guide pieces 37b and 3
8a, a bottom plate expansion / contraction means 33 is formed, and the bottom plate expansion / contraction means 33 causes the lower bottom plate 36, the middle bottom plate 37, and the upper bottom plate 38 to expand / contract with each other, thereby expanding / contracting the bottom plate 35 to a length substantially equal to the loaded paper S. Make it possible.

The support piece 37d of the midsole plate 37
The shaft 30 of the slider 30 on the one side is
Insert b. On the other hand, the shaft 37f provided on the support piece 37d of the middle bottom plate 37 is connected to the pulley 4 of the bottom plate urging means 39 shown in FIG.
After being inserted into the 0 shaft hole 40a, the tip is inserted into the shaft hole 31a of the slider 31 on the other side. And the shaft 30b
The bottom plate 35 is rotatably supported up and down in a seesaw manner with 37f as a fulcrum.

The bottom plate biasing means 39 for rotating the bottom plate 35 to lift the distal end side with a substantially constant biasing force is provided in FIG.
As shown in the figure, the pulley 40 is provided supported by the D-shaped shaft 37f, and a reel 41 is provided alongside the pulley 40. The reel 41 is supported by a shaft 31b provided on the slider 31. And the reel 41
, One end of the constant load spring 42 is wound and fixed. The constant load spring 42 is formed by turning an elongated thin plate having a curvature upside down and winding the other end side around the pulley 40 to be fixed. Then, the pulley 40 is rotated by the rewinding force of the constant load spring 42 to rotate the bottom plate 35.

Then, as shown in FIGS. 1 and 2,
One end of the spring 45 is hooked on the locking projections 30c and 31c of the sliders 30 and 31, respectively, and the other end is hooked on the locking projection 20e. Further, as shown in FIG. 3, one end of the wire 46 is locked to the locking projection 20c. After the wire 46 is wound around the pulley 32, the other end is engaged with the engagement piece 36 a of the lower bottom plate 36. Thus, an interlocking means 47 for moving the fulcrum of the bottom plate 35 to an intermediate position in conjunction with the expansion and contraction operation of the bottom plate expansion and contraction means 33 is formed.

Incidentally, as shown in FIG.
Is provided with a lever 50 that maintains the expanded and contracted state. The lever 50 has an elongated plate-shaped tip bent upward to provide an engaging portion (not shown), and a rear end bent upward to provide finger hooks 50a. Install in the direction. And the lower bottom plate 3
The lever 50 is rotatably provided to support the shaft portion 50b between the support portion 36d cut and raised in the positioning piece 36b of No. 6 and another support portion 51 fixed to the positioning piece 36b. The lever 50 is rotated and urged in a counterclockwise direction by an urging member (not shown) so that the lower bottom plate 36, the middle bottom plate 37, and the upper bottom plate 38 are urged.
The engaging portion at the leading end is engaged with an engaging hole (not shown) formed corresponding to the paper size.

From the above, the paper feeding device 18 of the present invention
Is a bottom plate expansion / contraction means 33 capable of extending / contracting the bottom plate 35 to a length substantially equal to the length of the stacking paper S, and the bottom plate 35
Plate supporting means 29 for rotatably supporting the bottom plate 3 vertically, interlocking means 47 for moving the fulcrum to the intermediate position in conjunction with expansion and contraction by the bottom plate expansion and contraction means 33, and the bottom plate 3
And a bottom plate urging means 39 for rotating the front end 5 with a substantially constant urging force by rotating the sheet feeding cassette 5.

After the sheets S are stored in the sheet cassette 20 shown in FIG. 4, the sheet cassette 20 is inserted from the mounting opening and attached to the apparatus main body 10. At this time, the locked state of the bottom plate 35 is released by lock release means (not shown) in the apparatus main body 10. Then, the pulley 40 is rotated by being pulled by the constant load spring 42. And the shafts 30b and 37f
The bottom plate 35 is rotated by using the fulcrum as a fulcrum to lift the distal end side to a predetermined position. Then, at the time of sheet feeding, the stacked sheets S are sequentially sent out one by one from above by the rotation of the sheet feeding roller 19. Thus, the constant load spring 42 is used as the number of sheets S decreases.
And the bottom plate 35 is largely rotated.

To set a larger sheet, for example, instead of the sheet S in the sheet cassette 20, first put a finger on the finger holder 50a and rotate the lever 50 to lock the sheet. Is removed from the locking hole of the bottom plate 35. Then, the lower bottom plate 36 is pulled out while holding the upper bottom plate 38, and the bottom plate 35 is extended to a length substantially equal to the new sheet S.
Then, the wire 46 is pulled in conjunction with the expansion / contraction operation, and the sliders 30 and 31 are moved via the pulley 32 in the pulling-out direction of the lower bottom plate 36. Then, the sliders 30 and 31 are moved by half the moving distance of the lower bottom plate 36 to move the fulcrum to an intermediate position of the length of the bottom plate 35. Then, a new sheet S is inserted and stacked on the bottom plate 35. Then use as described above.

[0029]

Therefore, according to the present invention, when sheets are set in the sheet feeding cassette, the bottom plate is extended and contracted by the bottom plate extending / contracting means to a length substantially equal to the set sheet, and the length of the bottom plate is extended in conjunction with the extension / contraction operation. Since the fulcrum is moved to the intermediate position, the weight is balanced between the leading end and the trailing end of the set sheet, and the size of the set sheet does not affect the urging force of the bottom plate. Then, since the bottom plate urging means always lifts the leading end side of the bottom plate with a substantially constant urging force, the paper can always be sent out at a substantially constant paper feed pressure regardless of the size of the paper to be used. Therefore, by appropriately setting the urging force of the bottom plate urging means, it is possible to reliably prevent double feeding or non-feeding of sheets.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a sheet feeding device according to an embodiment of the present invention, as viewed from one side of a sheet feeding cassette.

FIG. 2 is an exploded perspective view of a part of the sheet cassette viewed from the other side.

FIG. 3 is an explanatory diagram of an interlocking means of the sheet cassette.

FIG. 4 is an overall plan view of the sheet cassette.

FIG. 5 is an overall schematic configuration diagram of an internal mechanism of a laser printer including a paper feeding device using the paper feeding cassette.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 18 Paper feeder 19 Paper feed roller 20 Paper feed cassette 29 Bottom plate support means 33 Bottom plate expansion / contraction means 35 Bottom plate 39 Bottom plate urging means 47 Interlocking means S Paper

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B65H 1/08 B65H 1/24 G03G 15/00 516

Claims (1)

(57) [Claims] 1. A sheet is inserted into a sheet cassette and stacked on a bottom plate. The bottom plate is rotated to lift the leading end of the stacked sheet. In the sheet feeding device that feeds out the paper one by one, a bottom plate expanding / contracting device that allows the bottom plate to expand / contract to a length substantially equal to the loading paper, and the bottom plate is turned up and down around a middle position of the length expanded / contracted by the bottom plate expanding / contracting device. Bottom plate supporting means for freely supporting, interlocking means for moving the fulcrum to the intermediate position in conjunction with expansion and contraction operation by the bottom plate expansion and contraction means, and turning the bottom plate with a substantially constant urging force on the distal end side A sheet feeding device comprising: a bottom plate urging means for lifting the sheet feeding cassette.