JP2981308B2 - Paper feeder for sheet recording device - 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 can be applied to a sheet recording apparatus that prints, transfers, copies, and records on sheets such as paper, OHP paper, and envelopes such as facsimile machines. More specifically, the present invention relates to a sheet feeding apparatus that feeds sheets set in a sheet feeding cassette one by one in such a sheet recording apparatus.

[0002]

2. Description of the Related Art Conventionally, in this type of paper feeder, a paper feed cassette is attached to the main body of the apparatus, and a bottom plate in the paper feed cassette is urged upward by a constant urging force of an urging spring. Is pressed against a paper feed roller of the apparatus main body, and the sheet is fed by rotation of the paper feed roller.

[0003]

However, the conventional paper feeder has the following problems. A. Since the bottom plate in the paper cassette is urged upward and the sheet on the bottom plate is pressed against the paper feed roller of the apparatus main body, it becomes an obstacle to the removal of the paper cassette when the paper cassette is removed. B. FIG. 9 shows the relationship among the number of stacked sheets, the sheet feeding pressure, and the stacked sheets on the bottom plate. As can be seen from this relationship diagram, for example, a certain type of A6 size sheet is
When the sheets were set, the sheet feeding pressure at that time (the pressing force of the sheet against the sheet feeding roller) was 700 gf. However, when 250 sheets of the same type of A4 size sheets are set in the horizontal direction, the sheet feeding pressure at that time is 400 gf. As described above, the sheet feeding pressure greatly differs depending on the sheet size and the stacking direction. Therefore, if the size of the sheets on the bottom plate or the stacking direction of the sheets is changed, the sheet feeding pressure is greatly changed, and double feed or non-feed of the sheets may occur.

Accordingly, a first object of the present invention is to prevent a sheet from hitting a sheet feeding roller when the sheet feeding cassette is detached and hindering the removal. A second object is to prevent occurrence of double feeding or non-feeding of sheets due to stacked sheets.

[0005]

Therefore, in order to achieve the first object, the invention according to claim 1 is applied to an apparatus body 10 as shown in, for example, the following embodiments shown in FIGS. The paper feed cassette 18 is mounted on the paper feed cassette 18, and the bottom plate 49 in the paper feed cassette 18 is urged upward to press the sheet 21 on the bottom plate 49 against the paper feed roller 20 of the apparatus main body 10. In the sheet feeding device of the sheet recording device that sends out the sheet 21 by the rotation of
6 to be rotatable, a lever 34 that rotates integrally with the rotation bracket 33, and a force that rotates the lever 34 and the rotation bracket 33 downward to push the pressing roller 36. An urging spring 32 for urging downward is provided on the apparatus main body 10, and the distal end side of the lever 34 is directly or indirectly contacted based on the urging force of the urging spring 32, and The lever 34 is turned to remove the turning bracket 3
The paper feed cassette 18 is characterized in that a cam surface 44b is provided on the paper feed cassette 18 by rotating the unit 3 integrally and urging the pressing roller 36 downward to push down the bottom plate 49.

[0006] The invention described in claim 2 is the invention according to claim 1.
In the invention described in (1), for example, as shown in the following embodiments shown in FIGS.
When the paper cassette 18 is depressed, an engagement piece 46 that engages with and engages with the bottom plate 49 is provided on the paper cassette 18, and when the paper cassette 18 is attached, the engagement piece 46 is pressed against the engagement piece 46 to bias it. The apparatus main body 10 is characterized in that a stopper 48 is provided in the apparatus main body 10 to move in the retreating direction against the retracting direction and release the engagement between the engagement piece 46 and the bottom plate 49.

On the other hand, in order to achieve the second object,
The invention described in claim 3 is, for example, shown in FIGS.
As shown in the embodiment shown in FIG. 1, the paper feed cassette 18 is attached to the apparatus main body 10, and the bottom plate 49 in the paper feed cassette 18 is urged upward to feed the sheet 21 on the bottom plate 49 to the apparatus main body 10. Roller 20
In a sheet feeding device of a sheet recording apparatus for feeding the sheet 21 by rotation of 0, a rotation bracket 33 for rotatably holding a pressing roller 36, a lever 34 that rotates integrally with the rotation bracket 33, and a lever 34 And an urging spring 32 that urges the rotating bracket 33 downward and urges the pressing roller 36 downward, and provides the urging force of the urging spring 32 with the urging force. A side fence 55 for controlling the downward rotation of the lever 34 when the sheet 21 is positioned in the width direction and the width of the sheet 21 is equal to or greater than a predetermined value, while being smaller than the urging force for urging the bottom plate 49 upward. Is movably provided in the paper feed cassette 18.

[0008] The invention described in claim 4 is the invention according to claim 3.
When the sheet size in the width direction is equal to or smaller than a predetermined value, as shown in the following embodiments shown in FIGS. The lever 34 based on the urging force
A cam surface 44b for directly or indirectly contacting the distal end of the pressing roller 36 and retracting the pressing roller 36 is provided at a position where it does not hinder the removal.

[0009]

According to the first aspect of the present invention, when removing the sheet cassette 18 from the apparatus main body 10, when the sheet cassette 18 is pulled out, the lever 34 is rotated by the biasing spring 32 according to the cam surface 44b. , The turning bracket 33 turns integrally therewith. Then, the bottom plate 49 is pressed down by the pressing roller 36 against the urging force urged upward.

According to the second aspect of the present invention, when the bottom plate 49 is pressed down by the pressing roller 36, the bottom plate 49 is
Stop at 6.

According to the third aspect of the present invention, when the sheet size in the width direction is equal to or less than a predetermined value, the lever 34 is rotated downward by the urging force of the urging spring 32, and the bottom plate 49 is urged upward. The pressing roller 36 is pressed against the sheet 21 on the bottom plate 49 against the force. On the other hand, when the sheet size in the width direction is equal to or larger than a certain value, the side fence 55 regulates the downward rotation of the lever 34.

According to the fourth aspect of the present invention, when the sheet cassette 18 is pulled out when the sheet cassette 18 is removed from the apparatus main body 10 when the sheet size in the width direction is equal to or less than a predetermined value, the lever 34 is moved to the cam surface 44b. The pressing roller 36 is retracted to a position where the pressing roller 36 does not hinder the disassembly of the pressing roller.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 8 is a schematic view showing the overall structure of an internal mechanism of a laser printer provided with a paper feeding device according to the present invention. What is indicated by reference numeral 10 in the drawing is the apparatus main body. The apparatus main body 10 includes an upper structure 10a and a lower structure 10b, and the upper structure 10a is attached to the lower structure 10b by a shaft 11 so as to be freely opened and closed. In the apparatus main body 10, a belt-shaped photoconductor 12 is provided substantially at the center.

Around the photosensitive member 12, a charging device 13, a developing device 14, a transfer device 15, and a cleaning device 16 are arranged in this order in a driving direction indicated by an arrow in the drawing. An optical writer 17 is disposed above the charger 13 and the cleaning device 16, and a paper cassette 18 and the like are disposed below the transfer device 15 to constitute a paper feeding device 19.

The sheet 21 fed from the sheet cassette 18 by the sheet feed roller 20 in the direction of arrow A
Is conveyed to the lower side of the photoconductor 12 at a time by the registration roller pair 22. The photoconductor 12 is driven in a clockwise direction as indicated by an arrow. At this time, the surface is uniformly charged by the charger 13, and the photoreceptor 12 is irradiated with the laser beam L from the optical writer 17 to be statically placed on the photoconductor 12. An electrostatic latent image is formed. This latent image is visualized by the toner when passing through the developing device 14. Then, the visible image is transferred by the transfer device 15 to the upper surface of the sheet 21 conveyed below the photoconductor 12. The transferred sheet 21 is guided by a conveyance guide 23, passes between a heating roller 25 and a pressure roller 26 of a fixing device 24, and fixes a visible image. Then, the sheet 21 that has exited from the fixing device 24 is further conveyed by a paper discharge roller 27 and discharged in the direction of arrow B or C. On the other hand, the photoreceptor 12 after the transfer of the visible image removes the residual toner with the cleaning device 16 and then removes the charge with the charge remover 28.

The apparatus main body 10 is provided with a mounting opening 30 on the right side of the lower structure 10b in the drawing as shown in the figure, and can be detachably attached to the sheet feeding cassette 18 of the sheet feeding apparatus 19 of the present invention in the left-right direction as indicated by the arrow. Provided.

In order to achieve the first object, according to the present invention, the sheet feeding device 19 is configured as shown in FIG. 1, for example. That is, the fixing bracket 30 is provided on the lower structure 10b of the apparatus main body 10. The fixed bracket 30
As shown in FIG. 2, the bent portion 30a is long in the sheet width direction, and bent portions 30a are provided at both ends so as to face downward, and a shaft hole 30b is provided therein. From one of the shaft holes 30b, the shaft 3
1 through an urging spring 32 and a rotating bracket 33 to be described later.
Through the shaft hole 33a, the meniscus shaft hole 34a of the lever 34, and the other one of the shaft holes 30b, and the shaft 3 between the bent portions 30a.
1 is supported rotatably. At the center 31a of the shaft 31, a screw 3
5 and fixedly provided. The rotating bracket 33 has a pressing roller 36 provided on the distal end side so as to be rotatable about a shaft 37. The urging spring 32 is provided between the rotating bracket 33 and the bent portion 30a on the right side of the fixed bracket 30 in the drawing. The urging spring 32 has one end hooked on the bent portion 30a and the other end hooked on the turning bracket 33 to urge the turning bracket 33 counterclockwise in the drawing. Further, a shaft portion 31b having a half-moon cross section at one end of the shaft 31 includes:
The base end side of the lever 34 is fixed with a screw. A roller 38 is provided at the distal end of the lever 34 so as to be rotatable about a shaft 39.

On the other hand, the paper feed cassette 18 has a box shape as shown in FIG. 1, and has a side wall 44 standing on the outer periphery of a bottom wall 43 and a handle 45 provided on the right side in the figure. One side wall 44a of the side wall facing the sheet width direction end side has an upper end as a cam surface 44b, and a concave portion 44c is provided in a part thereof. A window hole 43a is opened in the bottom wall 43 of the sheet cassette 18. In the window hole 43a, an engagement piece 46 is appropriately supported by the bottom wall 43 and provided so as to be movable in the left-right direction in the figure. The engagement piece 46 has a columnar shape and has a locking portion 46a at an upper end, and protrudes into the sheet cassette 18 through the window hole 43a. One end of a coil spring 47 is pressed against the lower end of the engagement piece 46 projecting from the lower surface of the bottom wall 43. The coil spring 47 presses the other end to an appropriate position on the bottom wall 43 and urges the engagement piece 46 to the engagement position. The engagement piece 46
On the side opposite to the coil spring 47 with the stopper 4
8 is provided. The stopper 48 is connected to the lower structure 11b.
And the engaging piece 46 is moved to the retracted position against the urging force of the coil spring 47. A bottom plate 49 is provided in the sheet cassette 18 around a fulcrum (not shown).
Are provided so as to be vertically rotatable. The bottom plate 49 is provided with a window hole 49a. At the bottom right of the bottom plate 49 in the figure, a bamboo shoot spring 50 is provided.
Press one end of The bamboo child spring 50 urges the bottom plate 49 upward by pressing the other end against the bottom wall 43. Then, the sheet 21 is pressed against the paper feed roller 20 by the bamboo spring 50 with a constant pressing force.

When the sheet cassette 18 is mounted in the apparatus main body 10 as shown in FIG. 1, the rollers 38 are engaged with the cam surface of the sheet cassette 18. Therefore, when the sheet cassette 18 is removed, when the sheet cassette 18 is slightly pulled out in the direction of the arrow, the coil spring 47 operates to move the engagement piece 46 to the engagement position. At the same time as the paper feed cassette 18 is slightly pulled out,
2, the roller 38 enters the concave portion 46c according to the cam surface 44b, and the lever 34 rotates counterclockwise about the shaft 31. Then, the rotation bracket 33 rotates integrally with the lever 34, and the pressing roller 36 pushes down the sheet 21 and the bottom plate 49 together. Then, the bottom plate 49 is rotated clockwise about a fulcrum (not shown), and the lower side of the window edge of the window hole 49a is the locking portion 46.
hits a. Therefore, the engagement piece 46 moves in the retracting direction by the urging force of the urging spring 32, and
a leaves the window edge. When the bottom plate 49 is brought into the engagement position, the engagement piece 46 is again moved to the engagement position by the coil spring 47, and the engagement portion 46a is engaged with the upper side of the window edge of the window hole 49a, and Hang the bottom plate 49. Thus, since the sheet 21 is separated from the sheet feeding roller, the sheet feeding cassette 18 can be removed smoothly.

Next, in order to achieve the second object, according to the present invention, the sheet feeding device 19 is configured as shown in FIG. 4, for example. That is, the fixing bracket 30 and the urging spring 32 are provided in the same manner as described with reference to FIGS. 1 and 2, but the urging force of the urging spring 32 is smaller than the urging force for urging the bottom plate 49 upward. Provided. Also, two rotating brackets 33 are arranged on the left and right.

On the other hand, the paper feed cassette 18 has the same configuration as the paper feed cassette 18 shown in FIG. And sheet 2
The first side fence 55 for positioning in the width direction has the same height as the side wall 44a having the cam surface 44b, and is movable in the width direction of the sheet size.

When the sheet size in the width direction is equal to or smaller than a predetermined value, the urging spring 32 acts as shown in FIG. 5 so that the roller 38 enters the concave portion 46a according to the cam surface 44b, and 34 and the rotating bracket 33 are integrally rotated counterclockwise. Then, the pressing roller 36 presses the sheet 21 against the urging force for urging the bottom plate 49 upward. Therefore, the urging force for urging the bottom plate 49 upward is weakened, and the pressing force of the sheet 21 against the paper feed roller 20 is reduced.

On the other hand, when the sheet size in the width direction is equal to or larger than a certain value, a part of the lever 34 is appropriately engaged with the side fence 55 moved to the side wall 44a side as shown in FIG. Regulates downward rotation of.
Therefore, the pressing force of the sheet 21 against the paper feed roller 20 does not change.

FIG. 7 shows the relationship among the number of stacked sheets, the sheet feeding pressure, and the stacked sheets on the bottom plate in the sheet feeding device shown in FIGS. As can be seen from this relationship diagram, for example, the paper feeding pressure when 250 sheets of A6 size are set in the vertical direction can be reduced from the conventional 700 gf shown in FIG. 9 to 450 gf. Further, the paper feeding pressure when 250 A5-size sheets are set in the vertical direction can be reduced from the conventional 650 gf to almost 400 gf. Then, regardless of the sheet size and the stacking direction thereof, it is possible to reduce the difference in the sheet feeding pressure with respect to the sheet feeding roller based on the sheet stacking amount.

When the sheet size in the width direction is equal to or smaller than a predetermined value as shown in FIG.
As shown in FIG. At this time, the lever 34 rotates clockwise against the biasing spring 32, and the rotating bracket 33 rotates integrally therewith. Then, the pressing roller 36 is retracted to a position where it does not hinder the removal of the sheet feeding cassette 18.

[0027]

According to the first aspect of the present invention, when the paper cassette is pulled out of the apparatus main body when the paper cassette is pulled out, the lever is rotated according to the cam surface by the biasing spring, and the lever is rotated. The rotation bracket rotates integrally. Then, since the bottom plate is pressed down by the pressing roller against the urging force of urging upward, the sheet is separated from the sheet feeding roller and the sheet feeding cassette can be smoothly removed.

According to the second aspect of the present invention, the bottom plate 49 is provided.
Is hooked by the engagement piece 46, so that when the sheet cassette once removed is attached again, the sheet cassette can be smoothly attached without coming into contact with the sheet feeding roller.

According to the third aspect of the present invention, when the sheet size in the width direction is equal to or less than a predetermined value, the urging force of the urging spring causes the lever to rotate downward, thereby urging the bottom plate upward. While pressing the pressing roller against the sheet on the bottom plate against the counter, while the sheet size in the width direction is more than a certain,
Since the downward rotation of the lever is regulated by the side fence, the difference in the sheet feeding pressure with respect to the sheet feeding roller based on the sheet stacking amount can be reduced regardless of the sheet size and the stacking direction. Therefore, the sheet feeding pressure against the sheet feeding roller is stabilized, and occurrence of double feeding or non-feeding of sheets can be prevented.

According to the fourth aspect of the present invention, when the sheet size in the width direction is equal to or smaller than a predetermined value, when the sheet cassette is pulled out when the sheet cassette is removed from the apparatus main body,
The pressing roller retracts to a position where the lever rotates according to the cam surface and does not interfere with removal, so that the sheet cassette can be removed without interfering with the pressing roller.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a sheet feeding device according to an embodiment which achieves a first object of the present invention.

FIG. 2 is an exploded perspective view of a part thereof.

FIG. 3 is a state diagram when the sheet cassette is slightly pulled out.

FIG. 4 is an exploded perspective view of a part of a sheet feeding device according to an embodiment which achieves a second object of the present invention.

FIG. 5 is a state diagram when a sheet size in the sheet feeding device is equal to or smaller than a certain value.

FIG. 6 is a state diagram when a sheet size in the sheet feeding device is equal to or larger than a certain value.

FIG. 7 is a relationship diagram showing the relationship among the number of stacked sheets, the sheet feeding pressure, and the stacked sheets on the bottom plate in the sheet feeding device shown in FIGS. 4 to 6;

FIG. 8 is a schematic view of the overall configuration of an internal mechanism of a laser printer including a paper feeding device according to the present invention.

FIG. 9 is a relationship diagram showing the relationship among the number of stacked sheets, the sheet feeding pressure, and the stacked sheets on the bottom plate in the conventional sheet feeding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Apparatus main body 18 Paper feed cassette 20 Paper feed roller 21 Sheet 32 Urging spring 33 Rotating bracket 34 Lever 36 Press roller 44b Cam surface 46 Engagement piece 48 Stopper 49 Bottom plate 55 Side fence

Claims (4)

(57) [Claims] A paper cassette is attached to an apparatus main body, a bottom plate in the paper cassette is urged upward, and a sheet on the bottom plate is pressed against a paper feed roller of the apparatus main body. In a sheet feeding device of a sheet recording device that sends out the sheet by rotation, a rotating bracket for rotatably providing a pressing roller, a lever that rotates integrally with the rotating bracket, and the lever and the rotating bracket are directed downward. An urging spring for urging the pressing roller downward by rotating and urging the urging spring downward, and directly or indirectly contacting the distal end side of the lever based on the urging force of the urging spring. When the paper cassette is removed, the lever is pivoted to pivot the pivot bracket integrally, and the cam surface that urges the pressing roller downward to push down the bottom plate is moved to the paper cassette. A sheet feeding device of a sheet recording device provided in a set. 2. The paper feed cassette is provided with an engagement piece for urging to the engagement position and engaging with the bottom plate when the bottom plate is pushed down and latching the bottom plate. 2. The apparatus main body according to claim 1, wherein a stopper is provided on the apparatus main body, the stopper being adapted to move against the engagement piece in a retreating direction against the urging force and release the engagement between the engagement piece and the bottom plate. Paper feeder for sheet recording device. 3. A paper feed cassette is attached to the apparatus main body, and a bottom plate in the paper feed cassette is urged upward to press a sheet on the bottom plate against a paper feed roller of the apparatus main body. In a sheet feeding device of a sheet recording device that sends out the sheet by rotation, a rotating bracket for rotatably providing a pressing roller, a lever that rotates integrally with the rotating bracket, and the lever and the rotating bracket are directed downward. A biasing spring for rotating and biasing the pressing roller downward is provided in the apparatus main body, and the biasing force of the biasing spring is made smaller than the biasing force for biasing the bottom plate upward. A side fence for positioning the sheet in the width direction and restricting the downward rotation of the lever when the sheet size in the width direction is equal to or more than a predetermined value is movably provided in the sheet cassette. Becomes, the sheet feeding device of the sheet printing device. 4. When the sheet size in the width direction is equal to or smaller than a predetermined value, when the sheet feeding cassette is detached, the leading end side of the lever comes into direct or indirect contact with the urging force of the urging spring to remove the sheet feeding cassette. 4. The sheet feeding device for a sheet recording apparatus according to claim 3, wherein a cam surface for retracting the pressing roller is provided at a position where the pressing roller is not obstructed.