JP2002240966A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder capable of optimizing a paper feed pressure according to the size of a recording sheet by a simple operation. SOLUTION: A female screw shape is formed in the inner diameter part of a pinion gear 3 formed integrally with a pedestal 6, and rotated about a rotating shaft 7 of male screw shape provided in the bottom surface of a paper feed tray 1 by rack gears 4 provided on a side fence 5. When the side fences 5 are narrowed mostly, the pinion gear 3 lowers mostly to lower the paper feed pressure and, when they are spread mostly, the pinion gear 3 rises mostly to raise the paper feed pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder mounted on an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art In a paper feeder of an image forming apparatus, a pressure (paper feed pressure) for pressing a recording paper against a paper feed roller when paper is fed from a paper feed tray into a main body is provided inside the paper feed tray. It depends on the elastic force of the push-up spring. 2. Description of the Related Art A universal tray having a configuration in which recording sheets of different sizes can be accommodated by one sheet feeding device has been conventionally known. The universal tray has a pair of side fences for regulating the width direction of the recording paper, and the amount of mutual movement is linked by a rack gear provided on the side fence and a pinion gear located at the center of each other. . When recording paper of different sizes is accommodated in this universal tray, the weight of the recording paper bundle fluctuates according to the size. It is necessary to adjust according to the situation. That is, if the pressing force of the push-up spring against the bottom plate is constant irrespective of a change in the size of the recording paper to be stacked, the pressing force of the push-up spring is insufficient due to the large weight of large-size recording paper. As a result, the paper feed pressure by the paper feed roller becomes small, causing non-feeding. Conversely, in the case of small-size recording paper, the pressing force is too strong, the paper feeding pressure becomes excessive, and the double feed is likely to occur. Is generated. Therefore, when trying to feed recording papers of different sizes from the same paper feed tray, it is generally necessary to change the elasticity of the push-up spring. Each time, a dedicated paper tray had to be prepared. However, there is a problem that the push-up spring is not easy to replace because it is inside the paper feed tray, and it is expensive to prepare a paper feed tray for each size of recording paper.

In Japanese Patent Application Laid-Open No. 05-058472, an arm provided outside the paper feed tray presses a recording paper against a paper feed roller by pulling a push-up spring attached to a recording paper loading plate. In a paper feeding device, a paper feeding device that changes a paper feeding pressure by changing a hole for attaching a push-up spring has been proposed. In this paper feeding device, the paper feeding pressure can be arbitrarily changed depending on the position of the spring mounting hole. However, since the standard for changing the paper feeding pressure such as paper size and paper type is left to the user, it is not reliable. I can not say.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, according to the present invention, in a paper feeder having a configuration in which recording papers of different sizes can be accommodated by a single paper feeder, recording is performed without trouble. It is an object of the present invention to provide a sheet feeding device capable of optimizing a sheet feeding pressure according to a sheet size.

[0005]

According to a first aspect of the present invention, there is provided a recording sheet stacking plate having one end pivotally supported by a bottom surface of a sheet feeding tray for stacking recording sheets. A push-up spring that elastically urges the recording paper stacking plate upward from the bottom of the paper feed tray; a paper feed roller that feeds the recording paper in contact with the upper surface of the recording paper on the recording paper stacking plate; Equipped with a friction pad that presses against one side of the recording paper fed by rollers to separate the recording paper, a pair of side fences that regulate the width direction of the recording paper, and a pinion gear that interlocks the operation of the pair of side fences A sheet feeding apparatus characterized in that the sheet feeding apparatus further comprises means for changing a force for elastically urging the recording sheet stacking plate upward by a side fence that operates according to the width of the recording sheet. According to a second aspect of the present invention, in the paper feeding device of the first aspect, a receiving member for the push-up spring, which moves up and down along a screw-shaped groove provided on the bottom surface of the paper feeding tray, is provided. And a paper feeder characterized by the following. The present invention described in claim 3 provides the invention according to claim 2
The pinion gear moves up and down in synchronization with the operation of the side fence due to the engagement between the receiving member having a pinion gear shape on the outer peripheral portion and a side fence provided with a rack gear in the operation direction. Paper feeder. According to a fourth aspect of the present invention, in the paper feeder according to the second or third aspect, the receiving member having the pinion gear shape is a pinion gear for interlocking the pair of side fences with each other in a direction perpendicular to each other. And a sheet feeding device characterized in that: According to a fifth aspect of the present invention, in the paper feeder of the first aspect, as the distance between the side fences is reduced, the force for elastically urging the recording paper stacking plate upward is reduced. And

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a paper feed tray. The paper feed tray (1) includes a recording paper stacking plate (2), a pair of side fences (5) provided with a rack gear (4) for regulating the width direction of the recording paper, and a mutual side fence (5). ) Are composed of a pinion gear (3) for transmitting and regulating the movement in the orthogonal direction and a rotating shaft of the pinion gear (3). FIG. 2 is a schematic diagram showing the shapes of the pinion gear (3) and the rotating shaft. Pinion gear (3)
Is integrated with a pedestal for receiving the push-up spring, is provided with a female screw shape on the inner diameter portion, and has a male screw-shaped rotary shaft (7) provided on the bottom surface of the paper feed tray (1) as an axis. Rotate. By integrating the pinion gear and pedestal,
There is no need to dispose a pinion gear for receiving a new push-up spring, so that the component configuration can be simplified and the cost can be reduced.

FIG. 3 is a perspective view showing the pinion gear (3) and the side fence (5). When the side fence (5) is moved in the orthogonal direction, the pinion gear (3) is rotated by a rack gear (4) provided on the side fence (5). At this time, the pinion gear (3) itself moves in the vertical direction by the screw grooves provided in the pinion gear (3) and the rotating shaft (7). FIG. 4 shows the lowered state of the pinion gear (3), and FIG. 5 shows the raised state. By this operation, the pedestal (6) integrally formed with the pinion gear (3) moves up and down in accordance with the movement of the side fence (5), so that the distance between the recording paper loading plate (2) and the pedestal (6) is reduced. It shrinks and spreads in conjunction with the movement of the side fence (5).

FIG. 6 is a side view showing the movement of FIG. 4 and FIG. FIG. 6A shows the state where the side fence (5) is in the narrowest state, that is, the size of the stacked recording paper is the smallest, and the pinion gear (3) is lowered most. FIG. 6B shows a state in which the side fence (5) is in the widest state, that is, the size of the loaded recording paper is the largest, and the pinion gear (3) is the highest. If the width of the loaded recording paper is small,
As the distance between the recording paper loading plate (2) and the pedestal (6) increases, the elastic force of the push-up spring (8) decreases, and when the width of the loaded recording paper is large, the recording paper loading plate (2) The elastic force of the push-up spring (8) is increased by reducing the distance between the push-up spring (8) and the pedestal (6). Therefore, since the elastic force of the push-up spring can be changed in conjunction with the movement of the side fence, it is necessary to always maintain an appropriate value with respect to the change in the sheet feeding pressure caused by the difference in the size of the recording sheet. Can be.

[0009]

As described above, according to the present invention, by changing the pressure of the push-up spring in conjunction with the operation of the side fence, it is possible to always obtain the optimum sheet feeding pressure regardless of the sheet size. Therefore, it is possible to provide a sheet feeding device that suppresses occurrence of sheet feeding troubles such as non-feeding and double feeding. Further, since the side fence width regulating operation is changed to the vertical movement of the pinion gear, the spring pressure for pushing up can be changed only by the operation of the side fence, which is favorable without adding parts to the conventional configuration. A sheet feeding device having a sheet feeding pressure can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a paper feed tray.

FIG. 2 is a schematic diagram showing the shapes of a pinion gear and a rotating shaft.

FIG. 3 is a perspective view showing a pinion gear and a side fence.

FIG. 4 is a schematic diagram showing a lowered state of a pinion gear.

FIG. 5 is a schematic diagram showing a rising state of a pinion gear.

FIG. 6 is a side view showing when the pinion gear is lowered and when it is raised.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 paper feed tray 2 recording paper loading plate 3 pinion gear 4 rack gear 5 side fence 6 pedestal 7 rotating shaft 8 push-up spring 9 paper feed roller

Claims (5)

[Claims] 1. A recording paper loading plate, one end of which is pivotally supported by a paper feeding tray bottom surface for loading recording paper, a push-up spring for elastically urging the recording paper loading plate upward from the paper feeding tray bottom surface. A paper feed roller that feeds the recording paper in contact with the upper surface of the recording paper on the recording paper loading plate; a friction pad that presses against one side of the recording paper fed by the paper feed roller to separate the recording paper; In a paper feeder equipped with a pair of side fences that regulate the width direction of the recording paper and a pinion gear that interlocks the operation of the pair of side fences, the recording paper stacking plate is moved by the side fences that move according to the width of the recording paper. A sheet feeding device comprising: means for changing a force for elastically urging upward. 2. The sheet feeding device according to claim 1, further comprising a receiving member for the push-up spring, which moves up and down along a screw-shaped groove provided on a bottom surface of the sheet feeding tray.
A sheet feeding device, characterized in that: 3. The sheet feeding device according to claim 2, wherein the receiving member having a pinion gear shape on an outer peripheral portion thereof meshes with a side fence provided with a rack gear in an operation direction to synchronize with the operation of the side fence. Wherein the pinion gear moves up and down. 4. The sheet feeding device according to claim 2, wherein the receiving member having a pinion gear shape is the pinion gear for interlocking the pair of side fences in a direction perpendicular to each other. Characteristic paper feeder. 5. The paper feeder according to claim 1, wherein the force for elastically urging the recording paper stacking plate upward decreases as the distance between the side fences decreases.