JPH08277039A - Paper feeder and picture image forming device provided therewith - Google Patents

Abstract

PURPOSE: To provide a paper supply device which can detect the height position of the uppermost sheet material accurately even if the uppermost sheet material causes a loop and can provide excellent paper supply performance. CONSTITUTION: Since a roller member 4 of a paper surface sensor is pressed against a sheet material S by a coil spring 3 and the roller member 4 presses a part where the sheet material S causes a loop 10 down on a top face of the sheet material which is below the part and does not cause a loop even if the sheet material S put on a loading base causes the loop 10 upward, a photointerrupter 2 of the paper surface sensor detects the height of paper surface of the uppermost sheet material S accurately. The roller member 4 comes into rolling-contact with the top face of the sheet material S to feed the sheet material S smoothly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loading table elevating type large-capacity sheet feeder used in an image forming apparatus such as a facsimile, a printer, a copying machine, and an image forming apparatus equipped with the sheet feeder. is there.

[0002]

2. Description of the Related Art As a paper feeding option of an image forming apparatus,
The high-capacity paper feeder that is installed below the main body of the image forming apparatus is a high-capacity paper feeder that keeps the height of the top surface of the sheet material stacked on the stacker constant with respect to the paper feed slot. A paper surface sensor for detecting the height of the uppermost surface of the sheet material is provided for the purpose of maintaining the paper feeding operation of the paper feeding device. Further, when an image is formed on a sheet material fed from the paper feeding device into the main body of the image forming apparatus, the image forming apparatus provided with such a large-capacity paper feeding device has an accuracy of image forming (for example, printing accuracy). It has been devised to provide a means for urging the sheet material on the stack with respect to the paper feed standard of the stack in order to assure the following.

A method of urging the sheet material will be described below.

The sheet urging plate for urging the sheet material toward the sheet position reference plate serving as a sheet feeding reference is incorporated in a sheet width regulating plate arranged so as to face the sheet position reference plate, and is arranged in the sheet width direction. (Direction of sheet material conveyance direction)
It is constructed so that it can slide freely, and is further urged toward the seat position reference plate by a spring.

The stroke between the seat position reference plate and the seat urging plate is set to be slightly narrower than the seat width. Then, the sheet material stacked on the stacking table is fed and conveyed while being always moved to the sheet position reference plate side. Therefore, the sheet material supplied from the sheet feeding device to the main body of the image forming apparatus is kept constant in position and posture in the width direction (direction orthogonal to the sheet material conveying direction). The printing accuracy in the main body of the image forming apparatus is guaranteed.

[0006]

However, in the above-mentioned conventional sheet feeding device, as shown in FIG. 8, a few sheets above the sheet material S stacked on the stacking table, or a sheet at the time of small loading. The entire material S may be bent by the spring force of the sheet urging plate to form the loop 10 above. In the unlikely event that the loop 10 occurs at the positions of the sheet sensors 1 and 2, the sheet surface detection lever 1 detects the upper surface of the loop 10 at a position higher than the original sheet stacking surface, so that the sheet material S
There is a possibility that an error may occur in the detection result of the highest paper surface height of.

The position and size of the loop 10 depend on the stiffness (rigidity) and size of the sheet material S, or the spring pressure of the sheet urging plate. Generally, if the spring pressure of the sheet urging plate is set to be low, the occurrence of the loop 10 can be prevented, but since the urging force of the sheet material S is weakened, the printing accuracy is deteriorated. Therefore, the setting of the spring pressure of the seat biasing plate becomes complicated. Further, the paper surface sensors 1 and 2 cannot avoid the influence of the loop 10 on all paper types (types of the sheet material S) and sizes even if their arrangement is devised.
In FIG. 8, reference numeral 15 is a CPU as a control means, and the CPU 15 outputs a control signal based on the detection signals from the paper surface sensors 1 and 2.

As a result, it is difficult for the conventional sheet feeding device and the image forming apparatus equipped with the sheet feeding device to guarantee the printing accuracy while maintaining the sheet feeding performance.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a sheet feeding device having excellent sheet feeding performance and an image forming apparatus having excellent printing accuracy.

[0010]

SUMMARY OF THE INVENTION A sheet feeding device of the present invention comprises a stacking base for stacking sheet materials, a driving means for moving the stacking base up and down, and a topmost position on the stacking base which is raised by the driving means. Of the sheet material on the stacking table, the detection means for contacting the sheet material of No. 1 and detecting the position of the uppermost sheet material, the control means for controlling the operation of the driving means based on the detection signal from the detection means, A sheet feeding device comprising a reference plate serving as a positioning reference in the width direction and an urging means for urging the sheet material on the stacking table toward the reference plate, wherein The present invention is characterized in that a contact member that rolls on the upper sheet material is attached, and a spring member that presses the contact element against the uppermost sheet material is attached.

Further, in the paper feeding device of the present invention, the contactor is
It is characterized in that the roller member is rotatable in the sheet feeding direction.

Further, in the paper feeding device of the present invention, the contact is
It is characterized in that it is a substantially spherical roller member rotatable in any direction.

Further, the image forming apparatus of the present invention is characterized by including the above-mentioned paper feeding device and an image forming means for forming a desired image on a sheet material fed from the paper feeding device. There is.

[0014]

According to the present invention, even if the sheet material stacked on the stacking table causes an upward loop, the contact of the detecting means is pressed against the sheet material by the spring member, and the contact causes the loop of the sheet material. Since the above portion is pressed against the upper surface of the sheet material which does not form a loop therebelow, the detection means accurately detects the paper surface height of the uppermost sheet material.

Further, in the present invention, since the contactor constituting the detecting means is adapted to be in rolling contact with the sheet surface of the sheet material, a large frictional resistance is generated between the sheet material sent from the stacking table and the contactor. And the sheet material is smoothly fed.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. (First Embodiment) FIGS. 1 and 2 are views showing a sheet surface sensor (detection means) of a sheet feeding device A according to a first embodiment of the present invention. 3 and 4 are sectional views of the sheet feeding device A.

In these figures, the paper surface detection lever 1
Is rotatably attached to the frame of the sheet feeding device A,
A paper surface sensor (detection means) is configured with the photo interrupter 2. The paper surface detection lever 1 is urged downward in FIG. 1 by a coil spring 3, and a roller member 4 as a contactor is rotatably attached to the tip of the paper surface detection lever 1. The roller member 4 can freely rotate in the conveying direction of the sheet material S.

Next, the raising operation of the stacking table and the sheet urging operation will be described with reference to FIGS.

The loading table 5 on which the sheet materials S are loaded can be lifted by a driving means composed of a motor 30 and a wire 32 wound up by the motor 30 via a pulley 31. Paper feed position where the paper surface detection lever 1 blocks the photo interrupt 2 (Fig. 4)
Be raised to. The sheet feeding position of the stacking table 5 is preset to a height at which the sheet material S can be fed by the sheet feeding roller 9.

The sheet urging plate 7 for constantly urging the sheet material S toward the sheet reference plate 6 is slidably assembled to the sheet width regulating plate 11 arranged so as to face the sheet reference plate 6. . Then, the sheet reference plate 6 and the sheet urging plate 7
The stroke between and is set to be slightly narrower than the width of the sheet material S, and as described above, the sheet material S is always biased by the sheet biasing plate 7 in the direction of the sheet reference plate 6. It has become. Therefore, the sheet material S is brought closer to the sheet reference plate 6 as it rises in FIGS. 3 and 4.

The spring member 8 for pressing the sheet urging plate 7 is set so that the sheet member S can be sufficiently pressed even when the sheet members S are fully loaded on the loading table 5. Therefore, when the sheet material S is slightly loaded on the stacking table 5, or when the sheet material S having extremely low rigidity (rigidity) is stacked on the stacking table 5, when the stacking table 5 rises, The upper several sheets of the sheet material S stacked on the upper side may lose the spring pressure of the sheet urging plate 7 and rise upward to form a loop 10.

Next, regarding the operation of the paper surface detection lever 1,
This will be described with reference to FIGS. 1 and 2.

When the loop 10 occurs at the position of the paper surface detection lever 1, the upper surface of the loop 10 contacts the roller member 4 of the paper surface detection lever, and the loop 10 tries to push up the paper surface detection lever 1. However, since the paper surface detection lever 1 is biased by the coil spring 3 toward the stacking table 5 (downward in FIG. 1), the loop 10 can be pushed back to the original sheet stacking surface. As a result, the paper surface detection lever 1 can always detect the original height of the stacking surface of the sheet material S. Therefore, the paper feeding device A can always perform the optimum paper surface height control of the sheet material S.

On the other hand, when the sheet material S is fed and conveyed, the sheet feeding device A urges the sheet material S to the sheet reference plate 6 side by the sheet urging plate 7, and moves the sheet material S to the sheet reference plate 6. The sheet material S is conveyed along and is supplied into the main body of the image forming apparatus.
At this time, the roller member 4 at the lower end of the paper surface detection lever 1 rotates with the progress (movement) of the sheet material S. Therefore, even if the paper surface detection lever 1 is constantly urged toward the stacking table 5 by the spring force of the coil spring 3 sufficient to push back the loop 10, the paper surface detection lever 1 is conveyed to the contact portion between the paper surface detection lever 1 and the sheet material S. Does not cause resistance. (Second Embodiment) FIG. 5 is a diagram showing a paper surface sensor of a sheet feeding device A according to a second embodiment of the present invention. In this embodiment, the same members as those in the first embodiment are designated by the same reference numerals in FIG. 5, and the duplicated description is omitted for the components that are functionally the same as those in the first embodiment. Will be described in detail.

The difference between this embodiment and the first embodiment is that a substantially spherical roller 4 is attached to the lower end of the paper surface detection lever 1. Since the spherical roller 4 is rotatable not only in the sheet material feeding direction but also in the sheet material width direction, the sheet material is urged by the sheet urging plate 7 so that the sheet reference plate 6 (feeding reference). The conveyance resistance is further reduced as compared with the first embodiment because it does not hinder the operation of being moved to. (Image Forming Apparatus) FIGS. 6 and 7 show an image forming apparatus 101 provided with the sheet feeding device A of each of the above embodiments.
In these drawings, the sheet S fed from the sheet feeding device A is conveyed to the image forming unit 103 by the feeding unit 102, a desired image is formed on the image forming unit 103, and then on the discharge tray 104. Is discharged to. As shown in FIG. 7, the sheet feeding device A can be put in and taken out of the image forming apparatus 101 along a guide rail 21. Further, in these drawings, the same components as those of the sheet feeding device A in each of the above-described embodiments are designated by the same reference numerals, and the duplicated description thereof will be omitted.

[0026]

As described above, according to the present invention, even if the sheet material loaded on the loading table is pressed by the urging means to cause an upward loop, the contact of the detecting means is a spring member. Since the contact is pressed by the material and the portion of the sheet material that causes the loop is pressed against the upper surface of the sheet material that does not have the loop below it, it is not affected by the loop of the sheet material. , The detection means can accurately detect the paper surface height of the uppermost sheet material, and can control the height of the upper surface of the sheet material to be constant.
Can be significantly improved.

Further, according to the present invention, since the contactor which constitutes the detecting means is adapted to be in rolling contact with the paper surface of the sheet material, a large frictional resistance is generated between the contactor and the sheet material delivered from the stacking table. And the sheet material is smoothly fed.

Further, the image forming apparatus of the present invention is provided with the above-described sheet feeding device which is excellent in sheet feeding accuracy and can smoothly feed the sheet. As a result, the image forming precision (for example, printing precision) is significantly improved. Can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a paper surface sensor of a paper feeding device according to a first embodiment of the present invention.

FIG. 2 is an operation state diagram of a paper surface sensor of the paper feeding device according to the first embodiment of the present invention.

FIG. 3 is a sectional view of the sheet feeding device according to the first embodiment of the present invention.

FIG. 4 is an operation state diagram of the sheet feeding device according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram of a paper surface sensor of a paper feeding device according to a second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of an image forming apparatus including the paper feeding device of the present invention.

FIG. 7 is an external perspective view of the image forming apparatus showing the relationship between the image forming apparatus and the sheet feeding apparatus.

FIG. 8 is a configuration diagram of a paper surface sensor of a conventional paper feeding device.

[Explanation of symbols]

 1 paper surface detection lever (paper surface sensor, detection means) 2 photo interrupter (paper surface sensor, detection means) 3 coil spring (spring member) 4 roller member (contactor) 5 stacking table 6 sheet reference plate (reference plate) 7 sheet bias plate (Biasing Means) 15 CPU (Control Means) 30 Motor (Drive Means) 31 Pulley (Drive Means) 32 Wire (Drive Means) 101 Image Forming Device 103 Image Forming Means A Paper Feeding Device S Sheet Material

Claims (4)

[Claims] 1. A stacking platform for stacking sheet materials, a driving means for moving the stacking platform up and down, and a top sheet material on the stacking platform which is raised by the driving means and is in contact with the top sheet material. Detecting means for detecting the position of the sheet, control means for controlling the operation of the driving means based on a detection signal from the detecting means, a reference plate serving as a positioning reference in the width direction of the sheet material on the stacking table, A sheet feeding device comprising: a biasing unit that biases the sheet material on the stacking table toward a reference plate; and a contactor that rolls into contact with the uppermost sheet material in the detection unit, and A sheet feeding device, wherein a spring member for pressing the contactor against the uppermost sheet material is attached. 2. The sheet feeding device according to claim 1, wherein the contact is a roller member rotatable in a sheet feeding direction of the sheet material. 3. The contact member is a substantially spherical roller member rotatable in any direction.
The paper feeder described. 4. The method according to any one of claims 1 to 3.
An image forming apparatus, comprising: the sheet feeding device according to the above item 1; and an image forming unit that forms a desired image on a sheet material fed from the sheet feeding device.