JPH0940191A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeding device to vary the push-up force of a tray by an energizing means according to the size and the weight of a paper sheet and pressing a take-out roller against the paper sheet by a proper press force. SOLUTION: An image forming device comprises a containing cassette 1 to contain paper sheets P...; a take-out roller 4 to take out the paper sheets P in the containing cassette 17 a tray 2 which is arranged in the containing cassette 1 and on which the paper sheets P... are placed; energizing means 3 and 7 to energize the tray 2 and force the paper sheets P... against the take- out roller 4; a lever 6 to vary the energizing forced of the energizing means 3 and 7 according to the size of the paper sheet P; and a cam groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus applied as, for example, an electronic copying apparatus.

[0002]

2. Description of the Related Art An image forming apparatus of this type is provided with a paper feed cassette in its main body, and paper is stored in the paper feed cassette. The paper in the paper feed cassette is taken out by the rotation of the take-out roller in the main body of the apparatus. The sheet thus taken out is sent to a registration roller to be aligned, and then sent to an image transfer section between the photosensitive drum and the transfer charger to transfer an image.

In the case of a relatively small-capacity paper feed cassette having a storage capacity of about 500, a tray for loading paper is provided in the paper feed cassette, and the leading end of the tray in the paper feed direction is moved upward by a compression spring. The paper is pressed against the take-out roller by being urged to. When the pressure contact force of the paper with respect to the take-out roller is constant at all times, stable paper feeding performance can be obtained.

By the way, in the case of the paper feed cassette having such a structure, the pressure contact force of the paper with respect to the take-out roller is constant regardless of the size and type of the paper when the number of paper is small. However, when there are 500 sheets (full state),
Since the paper size, for example, A3 size paper and A4 size paper, has different weights, the pressing force on the take-out roller will change unless the spring for lifting the tray is changed.

[0005]

However, in the prior art, for example, the pushing force of the compression spring was set in accordance with the heaviest large-sized paper, so that when the light-sized paper is set, the pressing force is increased. There are inconveniences that the force is too strong and stack feeding occurs, and that the registration roller cannot pull the paper completely and a paper feed failure occurs.

When the pressing force of the compression spring is set according to the small size paper, if the large size paper is set on the tray, it cannot be lifted and the paper cannot be pressed against the take-out roller. There was an inconvenience that a paper feed failure occurred.

Therefore, according to the present invention, the image forming apparatus is configured so that the pushing-up force of the tray by the biasing means can be varied according to the size and weight of the paper so that the paper can be pressed against the take-out roller with an appropriate pressing force. The purpose is to provide.

[0008]

In order to solve the above-mentioned problems, the present invention provides a device body fixedly provided with a take-out roller, and a device provided in the device body and taken out by the take-out roller. An accommodating cassette for accommodating a sheet to be accommodated, a mounting member provided in the accommodating cassette for accommodating the sheet, and an energizing means for energizing the placing member and pressing the sheet against the take-out roller, The changing means changes the urging force of the urging means according to the size of the sheet.

According to a second aspect of the present invention, the apparatus main body is provided with a take-out roller in a fixed manner, a storage cassette provided in the apparatus main body for storing sheets taken out by the take-out roller, and provided in the storage cassette. A placing member that places the sheet, an urging unit that urges the placing member to press the sheet against the take-out roller, and an urging force of the urging unit when the sheet is large in size. If the size of the sheet is small, the changing means for decreasing the urging force of the urging means is provided.

According to a third aspect of the present invention, the apparatus main body is provided with a take-out roller in a fixed manner, a storage cassette provided in the main body of the apparatus for storing sheets taken out by the take-out roller, and provided in the storage cassette. A placing member for placing the sheet and a movably provided in a direction orthogonal to the take-out direction of the sheet placed on the placing member, and a side surface portion thereof is guided along the take-out direction when the sheet is taken out. A guide member, a biasing unit that biases the placing member to press the sheet against the take-out roller, and a changing unit that changes the biasing force of the biasing unit according to the position of the guide member. It becomes.

According to a fourth aspect of the present invention, there is provided an apparatus main body which is fixedly provided with a take-out roller, a storage cassette which is provided in the apparatus main body and which stores sheets taken out by the take-out roller, and a storage cassette which is provided in the storage cassette. When a size of the sheet is determined, a placing member configured to place the sheet, an urging unit configured to urge the placing member, and first and second urging members that press the sheet against the take-out roller. A changing means for changing the urging force by urging by the first and second urging members when the size is large and by the first urging member when the size of the sheet is small. It becomes.

According to a fifth aspect of the present invention, there is provided an apparatus main body which is fixedly provided with a take-out roller, a storage cassette which is provided in the main body of the apparatus and which stores sheets taken out by the take-out roller, and a storage cassette which is provided in the storage cassette. A placing member for placing the sheet, an urging unit including first and second urging members for urging the placing member to press the sheet against the take-out roller, and a weight of the sheet If larger,
When the weight of the sheet is small, the first and second urging members urge the first urging member to change the urging force to change the urging force.

According to a sixth aspect of the present invention, there is provided an apparatus main body which is fixedly provided with a take-out roller, an accommodating cassette which is provided in the apparatus main body and accommodates sheets taken out by the take-out roller, and is provided in the accommodating cassette. A placing member for placing the sheet and a movably provided in a direction orthogonal to the take-out direction of the sheet placed on the placing member, and a side surface portion thereof is guided along the take-out direction when the sheet is taken out. The guide member and the biasing means including the first and second biasing members for biasing the placement member to press the sheet against the take-out roller, and the first member depending on the position of the guide member. Both the urging member and the second urging member or only the first urging member, and changing means for changing the urging force.

According to a seventh aspect of the present invention, there is provided an apparatus main body which is fixedly provided with a take-out roller, a storage cassette which is provided in the apparatus main body and which stores paper taken out by the take-out roller, and a storage cassette which is provided in the storage cassette. A placing member for placing the sheet and a movably provided in a direction orthogonal to the take-out direction of the sheet placed on the placing member, and a side surface portion thereof is guided along the take-out direction when the sheet is taken out. The guide member, the first urging member that urges the placing member to press the sheet against the take-out roller, the turning lever provided on the guide member, and one end of the turning lever. A second urging member for urging and pushing up the mounting member, and a second urging member provided on the inner bottom surface of the storage cassette for guiding the other end of the rotating lever when the guide member moves to move the guide member. Formed by and a cam groove to release the push-up before placing member by the pivoting lever from the middle is pivoted against the biasing force of the second urging member.

According to the first aspect of the present invention, the urging force of the urging means for pressing the sheet against the take-out roller is changed according to the size of the sheet, so that the take-out roller can be provided with a constant width for the sheet of various sizes. Be able to press.

According to a second aspect of the present invention, when the size of the paper is large, the biasing force of the biasing means is large, and when the size of the paper is small, the biasing force of the biasing means is small.
It is possible to press the eject roller with a constant width against various sizes of paper.

According to the third aspect of the present invention, the urging force of the urging means is changed according to the position of the guide member for guiding the take-out of the paper, so that the paper of various sizes is pressed against the take-out roller with a constant width. To be able to

According to a fourth aspect of the present invention, when the size of the paper is large, the first and second biasing members are used, and when the size of the paper is small, the first biasing member is used. By changing the urging force by pressing, the paper can be pressed against the take-out roller with a constant width for various sizes of paper.

According to a fifth aspect of the present invention, when the weight of the paper is large, the first and second biasing members are used, and when the weight of the paper is small, the first biasing member is used to bias the paper. By changing the urging force by pressing, the paper can be pressed against the take-out roller with a constant width for various sizes of paper.

According to a sixth aspect of the present invention, both the first urging member and the second urging member, or only the first urging member is urged to urge the urging force according to the position of the guide member. By changing the size, it is possible to press against the take-out roller with a constant width for various sizes of paper.

According to a seventh aspect of the present invention, the other end of the turning lever provided on the inner bottom surface of the storage cassette is guided when the guide member moves, and the turning lever is urged to the second bias from the middle of the movement of the guide member. By rotating the mounting member against the biasing force of the member and releasing the lifting of the mounting member, the biasing force can be changed according to the size of the paper, and it is pressed against the take-out roller with a constant width for various sizes of paper. To be able to.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 2 shows a sheet feeding device provided in the apparatus main body 10 of the electrophotographic apparatus, in which 1 is a sheet feeding cassette. A tray 2 as a mounting member is provided in the paper feed cassette 1. One end of the tray 2 is rotatably supported by the support shaft 2a, and the sheets P are stacked on the tray 2. A compression spring 3 as a first biasing member is provided between the inner bottom of the paper feed cassette 1 and the other end of the tray 2, and the compression spring 3
Thus, the tray 2 is biased upward. A pickup roller 4 is fixedly provided on the upper portion of the paper feed cassette body 1 as a pickup roller.
The sheet P is pressed by the urging force of the compression spring 3.

In the paper feed cassette 1, as shown in FIG.
A pair of side guides 5 (only one is shown) are provided as guide members along the take-out direction of the paper P, and the side is guided by the pair of side guides 5 and 5 when the paper P is taken out. ing. The pair of side guides 5 and 5 are slidably provided in a direction orthogonal to the take-out direction of the paper P, and are opposite to each other when moving, that is,
It is designed to move in the direction of contact and separation.

A lever 6 is rotatably attached to the side surface portions of the side guides 5 and 5 via a support shaft 6A. One end 6A of the lever 6 is biased upward by a tension spring 7 as a second biasing member attached to the side guide 5 so that the tray 2 can be lifted.

On the other hand, a cam groove 8 is formed on the inner bottom of the paper feed cassette 1 along the moving direction of the side guides 5, 5.
The other end 6b of the lever 6 is slidably engaged with the cam groove 8. The lever 6 moves along the inner side surface of the cam groove 8 when the side guides 5 and 5 move, and when it moves a predetermined distance, the other end 6b rides on the inclined surface 8a of the cam groove 8 and resists the biasing force of the tension spring 7. When the lever 6 is rotated, the one end 6a of the lever 6 is separated from the tray 2 and the bias is released.

Next, the operation of the above embodiment will be described. First, when feeding a small size sheet, the side guides 5 and 5 are moved in the directions in which they approach each other. By the movement of the side guides 5 and 5, the other end portion 6b of the lever 6 slides along the cam groove 8 and the inclined surface 8 of the cam groove 8 is formed.
By riding on a, the support shaft 6A is rotated in the direction of the arrow a as shown in FIG. 4 against the biasing force of the tension spring 7 to separate one end 6a thereof from the tray 2. As a result, the tray 2 is pushed up only by the compression spring 3 and the paper P comes into pressure contact with the pickup roller 4.

Further, when feeding a large size paper, the side guides 5 and 5 are moved in the directions away from each other. As a result, the lever 6 is moved to the free position below the cam surface 8a, and is urged upward by the urging force of the tension spring 7 as shown in FIG. This allows
The tray 2 is lifted by being biased by both the compression spring 3 and the tension spring 7, and the paper P comes into pressure contact with the pickup roller 4.

The lever 6 does not have to be continuously operated until the number of sheets P is reduced from the full 500 sheets to 0 sheets.
When the amount of the paper P is reduced to some extent, the weight of the large size paper and the size of the small size paper do not change so much. Therefore, when the amount of the paper P is small, the difference in weight due to the size difference can be ignored.

Therefore, when it reaches a certain height, the tension spring 7 for lifting the lever 6 is brought into close contact, and
As shown in, the structure is such that the lever 6 is not further lifted.

By doing so, the pressing force applied to the pickup roller 4 can be kept constant for all paper sizes with a certain width. The pressing force on the pickup roller 4 has conventionally been set with the compression spring 3 according to the heavy paper, but the pickup force is larger than the pulling force of the registration roller, which causes the double feeding of the light paper. Since the pressing force of the roller 4 was too strong, the registration roller was unable to pull the paper, resulting in a jam.

However, the compression spring 3 is set so that the normal pressing force is adjusted to a relatively light paper, and the compression spring 3 lifts the compression spring 3 with the tension spring 7 for a heavy paper size where the pressing force is insufficient. The pressing force can be kept constant for all paper sizes, and the paper feeding performance can be stabilized.

FIG. 6 shows changes in the urging force of the compression spring 3 and the tension spring 7 with respect to the tray 2. The stack thickness of the paper P on the tray 2 is 45 mm (500
The tray 2 is lifted by the compression spring 3 and the tension spring 7 from the full thickness (sheets, full state) to 18.3 mm, and when the stack thickness of the paper P becomes less than 18.3 mm, the compression spring 3 Only lifted by.

The load differences S1, S2, S3 in FIG. 6 become the pressing force of the paper P against the pickup roller 4. FIG. 7 shows the change in the pushing force of the compression spring 3 depending on the stacking height of the sheets P on the tray 2.

[0034]

As described above, the present invention has the following features.
In the one described, since the urging force of the urging means for pressing the paper against the take-out roller is changed according to the size of the paper, the paper can be pressed against the take-out roller with a constant width against various sizes of paper, which is stable. Feeding becomes possible.

Since the urging force of the urging means is large when the size of the paper is large, and the urging force of the urging means is small when the size of the paper is small, various sizes can be used. The paper can be pressed against the take-out roller with a constant width, and stable paper feeding becomes possible.

According to the third aspect of the present invention, the urging force of the urging means is changed depending on the position of the guide member that guides the take-out of the paper, so that the paper can be pressed against the take-out roller with a constant width for the paper of various sizes. Therefore, stable feeding is possible, and the sliding operation of the guide member and the urging force changing operation of the urging means can be performed at the same time, which is excellent in operability.

According to a fourth aspect of the present invention, when the size of the paper is large, the first and second biasing members are used, and when the size of the paper is small, the first biasing member is used. Since the urging force is changed by pressing, the paper can be pressed against the take-out roller with a constant width for various sizes of paper, and stable paper feeding becomes possible.

According to a fifth aspect of the present invention, when the weight of the paper is large, the first and second urging members are used, and when the weight of the paper is small, the first urging member is used. Since the urging force is changed by pressing, the paper can be pressed against the take-out roller with a constant width for various sizes of paper, and stable paper feeding becomes possible.

According to a sixth aspect of the present invention, both the first biasing member and the second biasing member, or only the first biasing member is biased in accordance with the position of the guide member to apply the biasing force. Since it is changed, it can be pressed against the take-out roller with a constant width for various sizes of paper, and stable paper feeding becomes possible.

According to a seventh aspect of the present invention, the other end of the turning lever provided on the inner bottom surface of the storage cassette is guided when the guide member is moved, and the turning lever is urged to the second bias from the middle of the movement of the guide member. Since the pushing force of the placing member is released by rotating it against the biasing force of the member, the biasing force can be changed according to the size of the paper, and it can be pressed against the take-out roller with a constant width for various sizes of paper. And stable feeding is possible.

[Brief description of drawings]

FIG. 1 is a perspective view showing a tray biasing mechanism according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a paper feed cassette including the tray biasing mechanism of FIG.

FIG. 3 is a view showing a state in which the tray is pushed up by a compression spring and a tension spring which form the biasing mechanism of FIG.

FIG. 4 is a view showing a state in which the tray is pushed up only by the compression spring of the biasing mechanism of FIG.

FIG. 5 is a diagram showing a state in which the amount of paper is running low, the tension by the tension spring is released, and the tray is pushed up only by the compression spring.

FIG. 6 is a graph showing a change in biasing force of a compression spring and a tension spring according to a change in stacking height of sheets on a tray.

FIG. 7 is a graph showing a change in biasing force of a compression spring according to a change in stacking height of sheets on a tray.

[Explanation of symbols]

 P ... Paper 1 ... Storage cassette 2 ... Tray (placement member) 3 ... Compression spring (biasing means) 4 ... Pickup roller (takeout roller) 7 ... Tension spring (biasing means) 8 ... Cam groove (changing means) 6 … Lever (change means)

Claims (7)

[Claims] 1. An apparatus main body which is fixedly provided with a take-out roller, a storage cassette which is provided in the main body of the apparatus and stores paper taken out by the take-out roller, and the paper which is provided in the storage cassette and is placed thereon. A placing member, an urging unit that urges the placing member to press the sheet against the take-out roller, and a changing unit that changes the urging force of the urging unit according to the size of the sheet. An image forming apparatus comprising: 2. An apparatus main body which is fixedly provided with a take-out roller, a storage cassette which is provided in the main body of the apparatus and stores paper taken out by the take-out roller, and the paper which is provided in the storage cassette and is placed. A placing member, an urging unit that urges the placing member to press the sheet against the take-out roller, and when the size of the sheet is large, the urging force of the urging unit is large. And a changing means for reducing the urging force of the urging means when the value is small, the image forming apparatus. 3. An apparatus main body which is fixedly provided with a take-out roller, a storage cassette which is provided in the main body of the apparatus and stores paper taken out by the take-out roller, and the paper which is provided in the storage cassette and is placed. A placing member, a guide member that is movably provided in a direction orthogonal to a take-out direction of a sheet placed on the placing member, and guides a side surface of the sheet along a take-out direction when the sheet is taken out; An urging unit that urges the placing member to press the sheet against the take-out roller, and a changing unit that changes the urging force of the urging unit according to the position of the guide member. Image forming apparatus. 4. An apparatus main body which is fixedly provided with a take-out roller, a storage cassette which is provided in the apparatus main body and stores paper taken out by the take-out roller, and the paper which is provided in the storage cassette and is placed. A placing member, an urging means including first and second urging members for urging the placing member to press the sheet against the take-out roller, and when the size of the sheet is large, When the size of the sheet is small by the first and second urging members, a changing unit that urges the first urging member to change the urging force is provided. Image forming apparatus. 5. An apparatus body fixedly provided with a take-out roller, a storage cassette provided in the apparatus body for storing sheets taken out by the take-out roller, and a sheet provided in the storage cassette for placing the sheet. A placing member, an urging means comprising first and second urging members for urging the placing member to press the sheet against the take-out roller, and when the sheet has a large weight, First and second
When the weight of the paper is small, the urging member of
An image forming apparatus comprising: a changing unit that changes the urging force by urging the first urging member. 6. An apparatus main body which is fixedly provided with a take-out roller, a storage cassette which is provided in the main body of the apparatus and stores paper taken out by the take-out roller, and the paper which is provided in the storage cassette and is placed. A placing member, a guide member that is movably provided in a direction orthogonal to a take-out direction of a sheet placed on the placing member, and guides a side surface of the sheet along a take-out direction when the sheet is taken out; An urging means including first and second urging members for urging the placing member to press the sheet against the take-out roller; and the first urging member and the first urging member depending on the position of the guide member. An image forming apparatus comprising: both of the urging members, or a changing unit that urges only the first urging member to change the urging force. 7. An apparatus main body which is fixedly provided with a take-out roller, a storage cassette which is provided in the main body of the apparatus and stores paper taken out by the take-out roller, and the paper which is provided in the storage cassette and is placed. A placing member, a guide member that is movably provided in a direction orthogonal to a take-out direction of a sheet placed on the placing member, and guides a side surface of the sheet along a take-out direction when the sheet is taken out; A first urging member that urges the placing member to press the sheet against the take-out roller, a rotating lever provided on the guide member, and one end portion of the rotating lever to urge the rotating member. A second urging member that pushes up the placing member and a second urging member that is provided on the inner bottom surface of the storage cassette and guides the other end of the turning lever when the guide member is moved, and the turning is performed during the movement of the guide member. An image forming apparatus characterized by being provided with the cam groove, the releasing the push-up before placing member is rotated against the bar to the urging force of the second urging member.