JP3087583B2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a sheet feeding device in an image forming apparatus such as a copying machine, a laser printer, a facsimile, and the like.

[0002]

2. Description of the Related Art In a paper feeding device of an image forming apparatus such as a printer, for example, as disclosed in Japanese Patent Publication No. 62-54730, the paper feeding device is disposed in a cassette box in an inclined manner so that the tip is upward. An upward biasing spring is interposed between a receiving plate arranged vertically and rotatable and a bottom plate of the cassette box, and sheets are stacked on the receiving plate. There is known a configuration in which a paper feed roller having a substantially D-shape in side view is configured to be pressed, and paper is fed one by one toward a printing unit by rotation of the paper feed roller.

[0003]

However, in the above-described conventional configuration, the point of action of the urging spring supporting the receiving plate is constant, so that even if the size of the paper to be fed is different, When the number of sheets to be stacked on the receiving plate is small, the upward biasing force by the biasing spring does not vary much, but when the number of stacked sheets is large, the weight of the stacked sheets increases in proportion to the size. And the downward weight acting on the biasing spring against this load varies greatly. Therefore, if an urging spring having a large spring coefficient and an appropriate pressing force in the direction of the paper feed roller is adopted so as to correspond to a large size paper, when the small size paper is stacked on the receiving plate, Pressing force becomes too strong, and the phenomenon of double feed of paper occurs. Conversely, if an urging spring with a small spring coefficient is used that has a suitable pressing force in the direction of the paper feed roller so as to correspond to the small size paper, when the large size paper is stacked on the receiving plate, There has been a problem that the pressing force in the direction becomes too weak, the feeding of the paper becomes uncertain, and if it is severe, the paper cannot be fed.

In order to solve this inconvenience, the positions of the urging springs are changed one by one so as to change the points of action of the urging springs arranged on the cassette box on the lower surface of the receiving plate according to the paper size. Alternatively, a plurality of biasing springs having different spring coefficients must be prepared and replaced, and the replacement must be performed.

The present invention has been made to solve these problems, and an object of the present invention is to provide a sheet feeding device capable of easily adjusting an urging force (pressing force).

[0006]

According to a first aspect of the present invention, there is provided an image forming apparatus in which a surface of a sheet stacked on a cassette box is pressed against a sheet feeding roller of a sheet feeding section in an image forming apparatus. In the paper feeding device configured to feed paper, a receiving plate that supports at least a front end side of the stacked sheets, a free end side is supported on a lower surface of the receiving plate, and a base end is provided in the cassette box. The cassette box includes a lever for load support pivotally supported in a vertically rotatable manner, and an urging spring,
One end of the biasing spring is supported on the cassette box, and the mounting body to which the other end of the biasing spring is attached is attached to the lever with respect to the lever.
Attached slidably from the edge part to the free edge part
At the same time, the mounting position of the attachment body is selectively set to a plurality of positions of a position near the base end and a position near the free end of the lever.
It is configured to be changeable .

According to a second aspect of the present invention, in the paper feeder according to the first aspect, the other end of the urging spring is attached along a downwardly convex curved guide formed on the lever. The body is configured to be slidably mounted so as to be selectively rearranged at a plurality of positions near a base end portion and a free end portion of the lever.

[0008]

Next, an embodiment of the present invention will be described. 1 is a side view of the printer 1, FIG. 2 is a schematic perspective view of a cassette box 2 having an open top, and FIG.
Are respectively shown in plan views. In the lower part of the main body 1a of the printer 1, a first cassette storage part 4a and a second cassette storage part 4b which are opened forward are formed up and down, and the cassette storage parts 4a and 4b have a cassette box 2, 2 are detachably mounted. In each cassette box 2 formed in the same shape, the base end (rear end) of the receiving plate 5 for stacking and placing the sheets P is placed in the cassette box 2 as described later in detail. A load supporting lever lever 6 rotatably mounted near the bottom, supporting the free end side on the lower surface of the receiving plate 5, and pivotally supporting the base end of the cassette box 2 in a vertically rotatable manner; , A biasing spring 7, one end of which is attached to the cassette box 2 and to which the other end of the biasing spring 7 is attached. And a biasing force adjusting means configured to be mounted so that the position can be selectively changed with respect to the position.

The paper P in the lower cassette box 2 pulled out by the substantially D-shaped paper feed roller 3 provided in the lower second cassette storage section 4b is placed at the front of the upper cassette box 2. It is guided to the guide passage 10 through the paper passage groove 9 formed so as to penetrate up and down, and is drawn out by the paper feed roller 3 provided in the upper first cassette storage portion 4a. The paper P remains in the guide path 1
It is led to 0. Paper P reaching image forming unit 11 including a toner cartridge, a charging device, and the like (not shown)
Is a fixing unit including a heating roller 14 and a pressing roller 15 after the toner image is transferred between the photosensitive drum 12 and the transfer roller 13 pressing against the circumferential surface of the image forming unit 11 to transfer the toner image. The paper P on which the toner image has been fixed at the position 16 is conveyed to the paper discharge tray 18 via the discharge passage 17.

The paper feed roller 3, which is substantially D-shaped in side view, has a circumferential contact portion that comes into contact with the surface of the paper P stacked in each of the cassette boxes 2, and a non-contacting paper that does not come into contact with the paper. A contact portion, and at least the contact portion is made of rubber or the like having a large friction coefficient. During the standby for paper feeding, the paper feeding roller 3 stops at the transfer where the non-contact portion faces the surface of the paper P,
In accordance with the paper feed command, the paper feed roller 3 stops after one rotation.

Next, the structure of the cassette box 2 and the means for adjusting the pressing force of the sheet P will be described with reference to FIGS. The cassette box 2 includes a bottom plate 2a having a substantially rectangular shape in plan view.
And a front frame 2b provided with the paper passage groove 9 provided at the front thereof, and left and right side plate portions 2c, 2c. As shown in FIG. 5, support holes 21 and 21 are provided for supporting the support base pieces 5a and 5a projecting outward from the right and left rear portions of the receiving plate 5 in a vertically rotatable manner.

Further, the paper P is selected according to the size of the paper P.
The rear regulating body 22 abutting on the rear end edge of the rear regulating body 22 is mounted so as to be able to move back and forth along a longitudinal guide hole 23 formed in the bottom plate 2a. A side regulating body 25 abutting on one side edge of the sheet P is movably mounted in a lateral guide hole 24 formed in the side surface of the sheet P. The cam group 29 for detecting the paper size is configured to rotate via the gear group 28, and the contact type sensors (which are disposed in the first cassette storage section 4a and the second cassette storage section 4b of the printer 1, respectively) The cam group 2 is not shown).
9 appropriately comes into contact with each other so that the size of the paper P stored in each cassette box 2 can be automatically detected.

The pressing force adjusting means for urging the front end of the lower surface of the receiving plate 5 in which a number of the sheets P are stacked upward is shown in FIGS.
As shown in FIG. 9, a load supporting lever 6 having a free end side supported on the lower surface of the receiving plate 5 and a base end pivotally supported on the cassette box 2 so as to be vertically rotatable, and a helical spring-shaped Biasing spring 7
And a mounting body 8 at the other end of the biasing spring 7 with respect to the lever 6
The lever 6 has a narrow width at the base end and a wide width at the free end, and is a substantially fan-shaped injection molded product made of synthetic resin. Pivot holes 30 on both sides of the base end of lever lever 6
Is pivotally supported by a pivot pin 31 of the front frame 2b so as to be vertically rotatable. The free end of the lever 6 extends upward behind the cassette box 2, and is mounted on one or both sides of the free end. A pin 32 is slidably fitted in a longitudinally extending guide groove 34 of a bracket 33 cut and raised in the receiving plate 5 downward.

A pair of window holes 36, 36 each having a substantially rectangular shape in a plan view and capable of being fitted and movable with a pair of left and right arms 35, 35 of the mounting body 8 are formed in an intermediate portion of the lever 6 in the front-rear direction. A pivot pin 4 laterally protruding from brackets 41 erected from the side edges of the left and right window holes 36, 36.
2 and 42, a pair of left and right arms 3 of the mounting body 8 are provided.
The pivot holes 43, 43 formed in the holes 5, 35 are rotatably fitted, while the lower surfaces around the window holes 36, 36 are shown in FIG.
As shown in FIG. 8, a center line is formed on a downwardly convex curved guide portion 37 such as a substantially semi-circular arc surface shape substantially coincident with the axis of the pivot pin 42. The upper surface of the support piece 38 can slide along the guide portion 37 from the base end portion of the lever 6 to the free end side.

A rib 39 as a reinforcing portion is connected between the pair of left and right window holes 36, 36, and the lower surface of the rib 39 has a downwardly convex shape such as a substantially semicircular arc surface as described above. It is formed on a curved guide portion 37. The guide portion 37 has an engagement claw (not shown) projecting from an upper surface of a support piece portion 38 of the attachment body 8 selectively moved to a base end portion or a free end portion of the lever 6. The recesses 40, 40 into which the brackets (1) and (2) can be fitted may be formed.

On the other hand, as shown in FIGS. 5 and 9, a pair of left and right helical spring-shaped biasing springs 7,
Locking portions 44, 44 for locking the other ends 7b, 7b of 7 and retaining pieces 45, 45 for preventing the other ends 7b, 7b from coming off the locking portions 44, 44 are provided. further,
A knob 47 is integrally protruded from the lower surface of the support piece 38 so that an operator can easily move the mounting body 8 by gripping the knob 47 with a finger.

One end (upper end) 7a of each biasing spring 7
Are locked by locking portions 46 of the front frame 2b of the cassette box 2. Further, the angle at which the free end side of the lever 6 is turned upward, and the tip of the receiving plate 5 is
The guide groove 34 formed in the bracket 33 of the receiving plate 5 regulates the uppermost position to stop at a position close to the lower surface of the support plate 5.
May be achieved by abutment of the mounting pin 32 on the upper end side of the lever 6 with the end of the lever 6, or the upper surface of the middle of the lever 6 may be formed on the upper edge of the insertion hole 50 formed in the front frame 2 b. It may be achieved by contact.

With this configuration, the left and right arms 35, 3 of the mounting body 8 are inserted through the window holes 36, 36 in the lever 6 as described above.
5 and insert the pivot holes 43, 4 into both pivot pins 42, 42.
While the fitting 3 is fitted, the urging springs 7, 7 are mounted and connected to the locking portions 46 on the cassette box 2 side and the locking portions 44, 44 on the mounting body 8 side. The upper surface of the support piece 38 is pressed against the semicircular guides 37, 37, 37 around the window holes 36, 36 and the lower surface of the rib 39. Then, as shown in FIG. 4, when the operator presses the knob 47 of the mounting body 8 with a finger through an operation hole 48 formed in the front part of the bottom plate 2a of the cassette box 2, the mounting body 8 is moved to the guide section. The lever can be selectively slidably moved along the base 37 to the base end portion or the free end portion of the lever 6.

In this case, as shown in FIG.
A free end of a cantilever (lever lever 6) having a pivot 1 as a fulcrum supports a downward load W from the receiving plate 5, and the lever 6 is biased by an urging spring 7 via the mounting body 8. Because of the upward bias, the balance of the force (moment of force) is adjusted by the principle of leverage to the downward load W at the free end of the lever 6 from the point of application of the load to the distance L from the load application point to the pivot pin 31.
The value obtained by multiplying 1 (= W × L1) and the value obtained by multiplying the upward urging force F by the urging spring 7 by the distance L2 between the pivot point 31 and the point of action (= F × L2) are obtained. Achieved by being equal.

As shown by the solid line in FIG. 4, the urging spring 7 in a state where the mounting body 8 is moved to the base end portion of the lever 6 is pulled from the point of action of pulling the lever 6 upward. The distance L2 to the pivot pin 31 which is the pivot point of the lever 6 is determined by moving the mounting body 8 to the free end side portion of the lever 6 as shown by a two-dot chain line in FIG. Distance L from the point of action of spring 7 to pivot pin 31
2 ′.

Accordingly, when the lever 6 is urged upward by the urging spring 7 via the mounting body 8 moved to the base end portion of the lever 6, the receiving plate 5 at the free end is directed upward. The urging force (the force in the direction opposite to the load W) is generated when the lever 6 is urged upward by the urging spring 7 via the mounting body 8 moved to the free end side portion of the lever 6. It is smaller than the force for urging the receiving plate 5 upward at the free end.

If this principle is used, the postcard size and B5
When the sheets P having a small size, such as the sheet P, are stacked on the receiving plate 5, the downward load W
Is small, the sheet P can be applied to the paper feed roller 3 with an appropriate upward biasing force by holding the attachment body 8 in a state moved to the base end side portion of the lever 6. Conversely, when the large-sized paper P such as A4 size or LG (legal) size is laminated on the receiving plate 5, the downward load W due to the lamination of these papers P becomes large. If the lever is moved to the free end portion of the lever 6, the distance from the point of application of the upward biasing force by the biasing spring 7 to the pivot pin 31 is increased, and an appropriate resistance is provided against the load. The paper P can be applied to the paper feed roller 3 by an upward urging force.

In the above-described embodiment, the guide portion 37 having a substantially semicircular arc shape is substantially the same height as the pivot pin 31 on the base end side of the lever 6, and moves toward the free end side of the lever 6. Since the pivot pin 31 is formed at a position higher than the height position, the free end of the lever 6 is held when the mounting body 8 is moved to the free end side portion of the lever 6. At positions where the side is substantially parallel to the bottom plate 2a of the cassette box 2 (a state in which the amount of stacked sheets P is large), the locking portions 46, 44
In the position where the extension displacement of the biasing spring 7 between the levers 6 is large and the free end side of the lever 6 is largely turned upward (in a state where the amount of stacked paper P is reduced), the position between the locking portions 46 and 44 is reduced. The amount of extension displacement of the urging spring 7 is small, so that the fluctuation range of the urging force can be made large in accordance with the amount of stacking of the large-sized paper P.

On the other hand, when the mounting body 8 is held in a state of being moved to the base end portion of the lever 6, the free end side of the lever 6 is substantially parallel to the bottom plate 2 a of the cassette box 2 (paper sheet). Locking portions 46, 44 in a state where the amount of P stacked is large)
Between the extension displacement amount of the biasing spring 7 and the extension displacement amount of the biasing spring 7 at a position where the free end side of the lever 6 is largely turned upward (in a state where the amount of stacked paper P is reduced). Therefore, the variation width of the urging force can be reduced in accordance with the amount of stacking of the small-sized paper P, and the variation width of the pressing force of the paper P against the paper feed roller 3 can be reduced. Also play.

Further, as shown in the above-mentioned embodiment, when the mounting body 8 is held in a state of being moved to the base end portion of the lever 6, the urging spring 7 has an axis line as shown in FIG. When the mounting body 8 approaches the pivot pin 31 side with respect to the axis of the pivot pin 42 with respect to the body 8 (in the direction perpendicular to the paper surface) and moves the mounting body 8 to the free end side portion of the lever 6, the urging spring 7 is moved. Is moved beyond the axis of the pivot pin 42 to the free end side portion of the lever 6 and is stabilized, that is, the rotation operation beyond the fulcrum can be realized. There is an effect that the lever 6 can be stably held in a state of being moved to the base end portion or the free end portion.

It is to be noted that three or more places for holding the position after moving the mounting body 8 along the downwardly convex guide portion 37 of the lever 6 may be provided.

[0027]

As described above, according to the first aspect of the present invention,
The described invention is a paper feeder configured to press and feed the surface of sheets stacked on a cassette box to a paper feed roller of a paper feed unit in an image forming apparatus. A receiving plate that supports at least the leading end side of the stacked sheets, a load supporting lever that supports the free end side on the lower surface of the receiving plate, and pivotally supports the base end of the stacked sheet so as to be vertically rotatable with respect to the cassette box; , A biasing spring, one end of the biasing spring is supported by the cassette box, and the other end of the biasing spring is attached to the mounting body at a position closer to the base end of the lever with respect to the lever.
Slidably attached to the part near the free end from
The mounting position of the mounting body can be selectively changed to a plurality of positions of a part near the base end and a part near the free end of the lever.
It is a thing.

Therefore, by holding the point of action of the biasing spring on the lever that can move up and down around the base end at a position close to the base end by the principle of leverage, small-sized sheets can be stacked on the receiving plate. Then, the leading end surface of the sheet can be pressed against the sheet feeding roller with an appropriate pressing force to exert a reliable sheet feeding action, while the point of action of the biasing spring is adjusted by the lever lever. By holding the sheet near the free end, even when a large number of large sheets are stacked on the receiving plate, the front end surface of the sheet is pressed with an appropriate pressing force against the paper feed roller to ensure reliable operation. There is an effect that the sheet feeding action can be exerted.

Then, in order to apply the appropriate pressing force, the mounting body to which the other end of the urging spring is mounted is connected to the lever.
Slidable from the position near the base end of the lever to the position near the free end
And the mounting position of the mounting body can be realized by a simple operation of selectively moving the mounting position to either the base end side or the free end side of the lever. According to a second aspect of the present invention, in the paper feeder according to the first aspect, an attachment body to which the other end of the urging spring is attached is provided along a downwardly convex curved guide formed on the lever. The lever is slidably mounted at a plurality of positions near a base end portion and a free end portion of the lever so as to be selectively rearranged.

Therefore, in addition to the functions and effects of the first aspect of the present invention, in order to apply the appropriate pressing force, the mounting body to which the other end of the biasing spring is mounted is formed by a downwardly projecting lever lever. This also has the effect that it can be realized with a simple operation of moving along the curved guide portion. Further, there is a remarkable effect that the position of the mounting body, which is moved to the base end side or the free end side of the lever in the downward convex curved guide portion, is stabilized.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view of a printer.

FIG. 2 is a perspective view of a cassette box.

FIG. 3 is a plan view of the cassette box.

FIG. 4 is a sectional side view of a main part of the pressing force adjusting means.

FIG. 5 is a cross-sectional view showing attachment of the attachment body to the lever shown in FIG.

FIG. 6 is a bottom view of the lever.

FIG. 7 is a side view of the lever shown in FIG. 6 taken along line VII-VII.

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a perspective view of a main part of the lever and a mounting body.

[Explanation of symbols]

 Reference Signs List 2 cassette box 2a bottom plate 2b front frame 3 paper feed roller 5 receiving plate 6 lever 7 urging spring 8 mounting body 31 pivot pin 35 arm 36 window hole 37 guide part 38 support piece part 44, 46 locking part 47 Pick

Claims (2)

(57) [Claims] In a paper feeder configured to press a surface of paper stacked on a cassette box against a paper feed roller of a paper feed unit in an image forming apparatus to feed the paper, the cassette box contains: A receiving plate that supports at least the leading end side of the stacked sheets, a load supporting lever that supports the free end side on the lower surface of the receiving plate, and pivotally supports the base end of the stacked sheet so as to be vertically rotatable with respect to the cassette box; , A biasing spring, one end of the biasing spring is supported by the cassette box, and the other end of the biasing spring is attached to the mounting body at a position closer to the base end of the lever with respect to the lever.
Slidably attached to the part near the free end from
The mounting position of the mounting body can be selectively changed to a plurality of positions of a part near the base end and a part near the free end of the lever.
A sheet feeding device. 2. A along the guide portion of the downwardly convex curved shape formed on the lever lever, the other end of the biasing spring mounting member rather attached, the proximal end side portion and a free end portion close leverage lever The paper feeder according to claim 1, wherein the paper feeder is slidably mounted at a plurality of positions so as to be selectively rearranged.