JP2004059245A - Paper feed cassette - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To balance paper feed operation by a paper feed roller at the right and left sides of a paper sheet, by providing an energizing means for pushing up the center of the paper sheet relative to a bottom plate of a paper feed cassette. <P>SOLUTION: An energizing member 36, which is a leaf spring having a footing 37 attached to a sole plate 30, is provided under the bottom plate 31 of the paper feed cassette 3, and a hemispherical operating part 38 projecting upward is provided at its tip part. A pressure applying point 39, which is a point of the operating part 38, pushes up the bottom plate 31. By setting the pressure applying point 39 at the center of the width direction of the paper, the paper feed operation is balanced at the right and left sides of the paper sheet. That can prevent the paper sheet from being fed obliquely when the paper feed roller 4 feeds the paper sheet. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an urging means for urging a bottom plate of a paper feed cassette in an ascending direction, and more particularly to an apparatus for supporting a paper sheet in such a manner that an urging force in a width direction of a sheet is not biased.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or a facsimile machine, a paper feed cassette for storing paper of an arbitrary size is arranged in a paper feed unit. A plurality of sheets are stacked and stored in the sheet cassette, the bottom plate on which the sheets are placed is raised, and a predetermined pressing force is applied to the sheet rollers against the sheet feeding roller of the sheet feeding unit of the image forming apparatus. To separate the sheets one by one using a sheet separating means such as a separation claw, and feed the sheets toward the image recording unit. A regulating member such as a side guide or an end guide is provided in the sheet accommodating portion of the sheet cassette to regulate a rear end portion and a side surface in a sheet feeding direction, and sheets are set in the sheet cassette. Later, the regulating member is fixed to the regulating position to regulate the paper so as not to be displaced. In the paper feed cassette, a bottom plate that supports the paper, raises the leading end of the paper in the paper feeding direction, and applies a predetermined pressing force to the paper feed roller has a hinge at an intermediate portion or a rear portion of the housing. , And is urged to lift the sheet by an elastic member such as a coil spring provided at a lower portion on the leading end side. Side guides are disposed on both sides of the paper supported by the bottom plate in the paper feeding direction to regulate both sides of the paper, but the side guides have corners in the paper feeding direction. A separation claw is provided for locking the unit and performing a sheet separating operation.
[0003]
[Problems to be solved by the invention]
However, two springs are arranged at the lower portion on both sides of the bottom plate and push up the paper upward, corresponding to both sides of the paper. However, the characteristics of the spring may not be constant. A state in which the biasing forces are not balanced tends to occur. When the paper feed roller arranged at a position corresponding to the spring is rotated while pressing the paper, the frictional force between the paper feed roller on both sides and the paper is not constant, and the paper is sent out. The sheet is in a skewed state, and the sheet conveyed in the skewed state may be caught in a gap or the like on a side portion of the sheet conveyance path, which may cause a jam.
[0004]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper feed cassette that uses a leaf spring member that can perform a lifting action at a central point of a bottom plate and that prevents imbalance in the pressing force of paper on a paper feed roller. And
[0005]
[Means for Solving the Problems]
The present invention provides a paper feeder comprising: a bottom plate on which a paper is placed; and a biasing unit configured to raise a leading end of the bottom plate on a paper feed side and bias the paper toward a paper feed roller. Regarding cassettes. In the present invention, the urging means arranged on the lower surface of the bottom plate is constituted by a leaf spring, and the leaf spring has one end fixed to the cassette bottom plate and the other end projected upward. A semi-spherical contact portion is formed, and the contact portion is in contact with the lower surface of the bottom plate at the center in the width direction.
[0006]
With the configuration described above, even if the number of sheets supported by the bottom plate increases or decreases, the push-up force from the leaf spring always acts on the center in the width direction. Can be. Then, the paper feed roller that comes into contact with the paper at the time of paper feeding does not become deviated in the width direction, and it is possible to prevent skew and the occurrence of jam due to skew.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The configuration of the sheet cassette of the present invention and the image forming apparatus will be described with reference to the illustrated example. The example shown in FIGS. 1 and 2 shows the structure of a paper feed cassette. The paper feed cassette 3 is provided inside an apparatus frame 3a similarly to the case of a conventionally known paper feed cassette. A bottom plate 31 on which a sheet is placed is provided. The bottom plate 31 is supported on the apparatus frame so as to be swingable about a hinge 32, and separation claws 35 are provided on both sides of the leading end in the sheet feeding direction. A paper feed roller 4 provided in the main body of the image forming apparatus is located above the paper feed cassette. One sheet is fed by the feeding force of the paper feed roller 4 and the locking action of the separation claw 35. Separate each paper feed.
[0008]
Further, in order to regulate the paper placed on the bottom plate 31, the sides of the paper are pressed along the guide members provided on the bottom plate 30 of the paper feed cassette 3 on both sides in the width direction of the paper. The two side guides 34, 34 are provided with movable side guides 34, 34 and an end guide 33 for regulating the rear end of the sheet in the paper feeding direction. The side guides are provided so that they can be separated from each other, and by moving one side guide, the other side guide is moved in conjunction with the other side guide, so that the sheet can be pressed from both sides and regulated. The separation claw 35 is supported by the side guide, and the corner of the leading end of the paper placed on the bottom plate 31 on the paper feed side is locked by the separation claw 35 by moving the side guide 34. To do.
[0009]
In the paper feed cassette 3, a biasing member 36 made of a leaf spring is provided as shown in the figure to bias the bottom plate 31 on which the paper is placed in the ascending direction. The urging member 36 is formed by using a leaf spring member. The base member 37 is fixedly attached to the cassette bottom plate 30, and an upwardly-facing hemispherical action portion 38 is provided at a distal end portion. One point 38 is a pressing point 39, and a lifting force is applied to the bottom plate 31. Further, the pressing action point 39 as a portion that comes into contact with the bottom plate 31 is provided so as to be in contact with the lower surface of the bottom plate 31 at the center in the width direction. When two paper feed rollers 4, 4 are arranged, the push-up action is exerted at the center of the two paper feed rollers 4, 4.
[0010]
If the urging force of the urging member 36 is set to be substantially the same as the urging force of a conventional apparatus using two coil springs, an effect of pressing the paper toward the paper feed roller can be exerted. In the urging member 36, conditions such as the thickness of the spring plate, the size of the action portion 38 at the distal end, and the length of the spring plate are not particularly limited as long as the sheet feeding operation can be performed well. is not. Further, as means for fixing the urging member 36 to the cassette bottom plate 30, any fixing means such as screwing can be used. Alternatively, a means for inserting the base of the spring plate into the bottom plate may be provided, and the base of the biasing member 36 may be inserted and locked, and then fixed and held using one set screw or the like. . Therefore, by arranging the urging member 36 as described above at the leading end of the bottom plate corresponding to the central portion in the width direction of the sheet, the urging means 36 in the width direction of the sheet fed by the paper feed roller is provided. It is possible to support the biasing action so that no bias occurs.
[0011]
The paper feed cassette 3 having the above-described configuration can be used by being mounted on the image recording apparatus 1 as shown in FIG. The image recording apparatus 1 shown in FIG. 3 is configured as a small-sized apparatus, and a paper feeding unit 2 provided at a lower portion of the apparatus main body is provided with a paper feeding cassette 3 capable of storing paper of an arbitrary size. Then, the paper is taken out one by one by the paper feed roller 4 and fed to the paper transport path 5. In the paper transport path 5, transport roller devices 5a and 5b are arranged at a predetermined interval, and the paper transported in the paper transport path 5 is transferred with a toner image when passing through the recording unit 7. The recording paper is fixed by the fixing device 8, and is discharged to the discharge tray 9 a by the discharge roller device 9. In addition to the paper feed system from the paper feed cassette 3, a manual tray 6 that can be opened and closed is arranged on the side of the apparatus. To feed paper toward the paper transport path 5 by the paper feed roller 6a.
[0012]
In the image recording apparatus 1, the recording unit 7 includes a photosensitive unit 10 provided with a photosensitive drum 12 and a developing unit 20 for supplying toner to the photosensitive drum 12. The two units 10 and 20 are combined and mounted on the recording unit 7 of the apparatus main body as illustrated. In the photoreceptor unit 10, a charging member 15 and a memory removing member 14 are disposed on a photoreceptor drum 12 supported on a unit frame 11 via a shaft 13. A writing unit 16 is disposed at a position corresponding to an upper portion of the photosensitive drum 12, and a transfer member 17 is disposed at a lower portion. The developing roller 25 of the developing unit 20 is located on the downstream side.
[0013]
In the photoreceptor unit 10, a predetermined voltage is applied to the photoreceptor drum by a charging roller 15 as a charging unit, and a writing unit 16 including an LED or the like is irradiated with light of an image to form an electrostatic latent image. Form an image. Then, toner is supplied from the developing roller 25 to the electrostatic latent image on the photosensitive drum 12 to form a toner image, and a toner image is formed between the transfer roller 17 and the photosensitive drum 12 and conveyed. On the other hand, a predetermined potential is supplied to the transfer roller 17 to transfer the toner image to a sheet. The sheet on which the toner image has been transferred is conveyed to the fixing device 8, is fixed, and is discharged as a recording sheet. Further, after the toner image is transferred onto the paper, the remaining toner and the like adhering to the photosensitive drum are disturbed by a brush as a memory removing member, and the adhesion is weakened and uniformly dispersed. Later, the toner is charged to a predetermined potential by the charging roller 15.
[0014]
In order to supply toner to the photosensitive drum 12, in a developing unit 20 in which a developing roller is provided corresponding to the photosensitive drum, the toner contained in the toner hopper 22 is separated by a paddle 23. It is sent out toward the supply roller 24 while stirring. Then, while rubbing the toner between the supply roller 24 and the developing roller 25, a predetermined potential is applied to charge the toner, adhere to the surface of the developing roller 25, and form a thin layer by the blade 31 member. I do. The toner carried on the developing roller 25 is supplied toward the electrostatic latent image on the photosensitive drum 12, and the toner remaining on the surface of the developing roller after that is newly supplied to the supply roller 24. The toner is mixed with the supplied toner, applied with a charging effect again, and supplied toward the developing area.
[0015]
In the image recording apparatus, an example is described in which a single paper cassette is provided and paper is supplied. However, an arbitrary number of paper cassettes may be provided in a paper supply unit of the image recording apparatus. It is possible to equip. Providing a biasing member by a leaf spring for pushing up the bottom plate is a technical means applicable to a conventionally known paper feed tray, and the amount of paper that can be accommodated in the paper feed tray or the like. The strength of the leaf spring can be appropriately set in accordance with the above. For example, if the number of sheets supported by the bottom plate is large, two leaf springs are provided in an overlapping manner corresponding to the weight of the sheet, or a sheet having a large spring strength is used. Is possible.
[0016]
【The invention's effect】
With the configuration described above, even if the number of sheets supported by the bottom plate increases or decreases, the pushing force from the leaf spring always acts on the central portion in the width direction. Can be. In addition, the paper feed roller that comes into contact with the paper at the time of paper feeding does not become deviated in the width direction, and it is possible to prevent skew and the occurrence of jam due to skew.
[Brief description of the drawings]
FIG. 1 is a plan view illustrating a configuration of a paper feed cassette.
FIG. 2 is a side view of the sheet cassette.
FIG. 3 is an explanatory diagram illustrating a configuration of an image recording apparatus.
[Explanation of symbols]
1 image recording device, 2 paper feed section, 3 paper feed tray,
4 paper feed roller, 5 paper transport path, 5a / 5b transport roller device,
6 manual feed tray, 7 recording unit, 8 fixing device,
9 discharge roller device, 10 photoconductor unit,
11 unit frame, 12 photoconductor drum, 13 drum shaft,
14 memory removing member, 15 charging member, 16 writing member,
17 transfer roller, 20 developing unit,
21 unit frame, 22 toner hopper, 23 paddle,
24 supply roller, 25 developing roller, 30 bottom plate,
31 bottom plate, 32 hinge, 33 end guide,
34 side guide, 35 separation claw, 36 urging member,
37 base member, 38 action part, 39 pressing action point.

Claims (1)

A sheet feeding cassette comprising: a bottom plate on which sheets are placed; and a biasing unit configured to raise a leading end of the bottom plate on a sheet feeding side and to bias the sheet toward a sheet feeding roller.
The biasing means disposed on the lower surface of the bottom plate is configured by a leaf spring,
The leaf spring has one end fixed to the cassette bottom plate, and the other end formed with a hemispherical abutting portion that is convex upward.
A sheet cassette, wherein the contact portion is in contact with a lower surface of a central portion in a width direction of a bottom plate.

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