JP2002128304A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder which can automatically surely convey paper of different coefficient of friction with no necessity for operation by a user, even in case of conveying a plurality of kinds of papers. SOLUTION: This paper feeder comprises a paper loading plate 6, a paper feed roller 2 arranged upward the paper loading plate 6, a first pressing means 8 for pressing the paper loading plate 6 to a side of the paper feed roller 2, a separating roller 1 arranged in the downstream in a paper conveying direction from the paper feed roller 2, a holder 3 which can turn in a manner capable of rolling contact with the separating roller 1 to be provided with a plurality of friction plates 4, 11 having a different coefficient of friction in a contact surface with the separating roller 1, and a second pressing means 12 for pressing the holder 3 to a side of the separating roller 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder,
In particular, the present invention relates to a paper feeder attached to a printer or the like and capable of automatically transporting a plurality of types of paper having different friction coefficients, such as plain paper and OHP sheets, without causing a double feed phenomenon.

[0002]

2. Description of the Related Art A printer or the like is provided with a sheet feeding device for feeding sheets stacked in a sheet feeding cassette to a developing mechanism. This paper feeder is generally provided with a mechanism that prevents a double feed phenomenon in which two or more stacked sheets are sent out at the same time at the same time.

FIG. 3 shows an example of a conventional double feed prevention mechanism, in which a separation roller 1 and a paper feed roller 2 are rotatably held on a printer main body (not shown) via a separation roller shaft 13 and a paper feed roller shaft 14. It is rotated in the direction of the arrow by a driving source such as a motor (not shown).

[0004] A friction plate 24 is attached to a holder 23, and the holder 23 is arranged in a sheet cassette so that the friction plate 24 faces the separation roller 1. Further, the friction plate 24 is pressed against the separation roller 1 via the holder 23 by a holder spring 25 between the holder 23 and the sheet feeding cassette.

[0005] The paper 9 is loaded on the paper loading plate 6 in the base cassette 7 and is pressed by the paper feed roller 2 via the paper loading plate 6 by the lift spring 8 so that even if the loading amount of the paper 9 changes. The pressing force on the paper feed roller 2 is substantially constant.

When the paper feed roller 2 is rotated by the driving source, the uppermost sheet 9 on the sheet stacking plate 6 is sent downstream. At this time, even when the paper 9 to be fed is multi-fed, the friction coefficient between the separation roller 1 and the friction plate 24 with respect to the paper 9 is larger than the friction coefficient between the papers 9. When passing through the contact portion, the second and subsequent sheets 9 are prevented from passing by the frictional load given by the friction plate 24, so that the sheets 9 can be sent out one by one while being separated.

Here, since the type of paper used in a printer or the like is usually plain paper, the above-mentioned conventional paper feeder uses the separation roller 1 and the paper 9 to transport the plain paper. When the friction coefficient between the friction plates 24 and the paper 9 is μ2, and the friction coefficient between the papers 9 is μ3, μ1>μ2> μ3 is set.

However, when the paper 9 is an OHP sheet or the like, the above-mentioned relationship between the friction coefficients is broken, and the difference between μ1 and μ2 is smaller than that of plain paper, so that the conveyance may not be possible. Conversely, the friction plate 24 corresponding to the OHP sheet
, This time, when transporting plain paper, μ2
And μ3 becomes small, and the friction plate 24 cannot separate the sheets sufficiently, so that double feeding occurs.

In order to solve the above problems, Japanese Patent Publication No. Hei 8-25
The paper feeder described in Japanese Patent Application Publication No. 655-255 uses two types of friction plates and manually switches the type of friction plates to support two types of paper.

[0010]

However, the above-mentioned Tokuhei 8
In the paper feeding device described in Japanese Patent No. 25655, the user must manually change the friction plate, and thus there is a problem that an operation error may be caused.

Therefore, the present invention has been made in view of the above-described problems in the conventional paper feeding apparatus, and does not require user operation even when a plurality of types of paper are conveyed, and automatically performs the operation. It is another object of the present invention to provide a sheet feeding device capable of surely conveying sheets having different friction coefficients.

[0012]

According to a first aspect of the present invention, there is provided a sheet feeding device, comprising: a sheet stacking plate; and a sheet feeding roller disposed above the sheet stacking plate. A first step of pressing the sheet stacking plate toward the sheet feeding roller;
Pressing means, a separation roller arranged downstream of the paper feed roller in the sheet conveyance direction, and a rotatable rolling contact with the separation roller, wherein a different friction coefficient is applied to a contact surface with the separation roller. A holder provided with a plurality of provided friction plates; and second pressing means for pressing the holder toward the separation roller.

According to the first aspect of the present invention, the type of the friction plate that contacts the sheet via the second pressing means is switched according to the friction force generated between the sheet and the sheet that has contacted the separation roller. Therefore, it is possible to automatically select a friction plate according to the properties of the sheet. by this,
A plurality of types of paper having different friction coefficients can be automatically conveyed without causing a double feed phenomenon.

[0014]

Next, a specific example of an embodiment of a sheet feeding device according to the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a sheet feeding device according to the present invention. The sheet feeding device includes a sheet stacking plate 6, a sheet feeding roller 2 disposed above the sheet stacking plate 6, Loading plate 6
Spring 8 serving as first pressing means for pressing the paper roller 2 toward the paper feed roller 2, the separation roller 1 disposed downstream of the paper feed roller 2 in the paper conveyance direction, and rotating to be in rolling contact with the separation roller 1. A holder (first holder) 3 having a plurality of friction plates 4 and 11 having different friction coefficients on a contact surface with the separation roller 1, and pressing the friction plates 4 and 11 toward the separation roller 1. And a second holder spring 12 as a second pressing means. 1 and 2, the same components as those of the conventional sheet feeding device shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The separation roller 1 and the paper feed roller 2 are rotatably held by a printer body frame (not shown) via a separation roller shaft 13 and a paper feed roller shaft 14, and are driven by a driving source such as a motor (not shown) by arrows. Rotate in the direction.

The first holder 3 is formed in a fan shape, and is rotatably held by the second holder 10. On the circumference of the first holder 3, two types of first friction plates 4 and second friction plates 11 having different friction coefficients are adhered, and are arranged to face the separation roller 1.

The first friction plate 4 is separated from the separation roller by a second holder spring 12 disposed between the second holder 10 and a sheet cassette (not shown) via the first holder 3 and the second holder 10. 1 is pressed. Further, the second holder spring 12 is disposed between the first holder 3 and the second holder 10, and suppresses the rotation of the first holder 3.

The paper 9 is loaded on the paper loading plate 6 in the base cassette 7, and is pressed against the paper feed roller 2 via the paper loading plate 6 by the lift spring 8.

Next, a mechanism for setting the friction plate in contact with the separation roller 1 as the second friction plate 11 when the paper 9 is an OHP sheet will be described.

As described above, the first holder 3 is provided with the second holder spring 12 between the first holder 3 and the second holder 10 to suppress rotation. When conveying plain paper, the separation roller 1 is driven by the first friction plate 4 via the plain paper.
A force F1 (not shown) that causes the second holder spring 12 to contract is generated by this force F1 so that the second holder spring 12 does not contract. It remains at 4.

On the other hand, when the OHP sheet is conveyed, a force F2 for rotating the first friction plate 4 to the downstream side of the sheet by the separation roller 1 through the OHP sheet in FIG.
(> F1, not shown), and the second holder spring 12 is set to be contracted by this force.
As the holder 3 rotates, the friction plate that comes into contact with the separation roller 1 as shown in FIG.

Next, the operation of the sheet feeding device having the above configuration will be described.

In FIG. 1, when the separation roller 1 and the paper feed roller 2 start to rotate in the direction of the arrow by a drive source such as a motor (not shown), the paper 9 loaded on the paper The movement starts, and the sheet 9 is transported to the contact portion between the separation roller 1 and the first friction plate 4.

At this time, when the paper 9 is plain paper, the friction coefficient between the separation roller 1 and the paper 9 is μ1, the friction coefficient between the first friction plate 4 and the paper 9 is μ2, Assuming that the friction coefficient between them is μ3, μ1>μ2> μ3, so that μ1> μ2 when only one sheet of plain paper is conveyed, and the paper 9 is conveyed by the separation roller 1. The applied force is larger than the frictional load generated between the paper 9 and the first friction plate 4, and the paper 9 is conveyed downstream from the contact portion.

Further, even when the paper 9 to be sent out is multi-fed, since the relation of μ1>μ2> μ3 is satisfied, the force of the separation roller 1 for transporting the paper 9 is larger than the frictional load generated between the papers 9 and 2 Since the subsequent sheets 9 are prevented from passing by the frictional load given by the first friction plate 4,
Only the uppermost sheet 9 can be transported downstream from the contact portion while being separated one by one.

Next, when the paper 9 is an OHP sheet,
Since the relationship between the friction coefficients is μ1 ≧ μ2> μ3, the force for conveying the sheet 9 by the separation roller 1 is a frictional load generated between the sheet 9 and the first friction plate 4 and is clearly different from that of plain paper. May not be able to be transported.

However, if a material having a friction coefficient μ4 with respect to the OHP sheet that satisfies μ1>μ4> μ3 is used as the second friction plate 11, the relationship between the separation roller 1 and the second friction plate 11 with respect to the OHP sheet becomes Since the relationship between the separation roller 1 and the first friction plate 4 with respect to plain paper is equal,
When the OHP sheet is transported, if the second friction plate 11 comes into contact with the separation roller 1, the paper 9 can be transported one by one while being separated.

In the above embodiment, two types of friction plates are attached to the first holder 3. However, the number of types of friction plates is three or more, and the elasticity of the second holder spring 12 By setting the coefficient, more types of paper 9 can be fed.

[0030]

As described above, according to the present invention,
Even when a plurality of types of sheets are conveyed, it is possible to provide a sheet feeding device capable of automatically and reliably conveying sheets having different friction coefficients without requiring an operation by a user.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing one embodiment of a sheet feeding device according to the present invention, showing a state in which a first friction plate is used.

FIG. 2 is a schematic side view showing one embodiment of the sheet feeding device according to the present invention, and shows a state in which a second friction plate is used.

FIG. 3 is a side view showing an example of a conventional sheet feeding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Separation roller 2 Feed roller 3 1st holder 4 1st friction plate 5 1st holder spring 6 Paper loading plate 7 Base cassette 8 Lift spring 9 Paper 10 2nd holder 11 2nd friction plate 12 2nd holder spring 13 Separation roller Shaft 14 Paper feed roller shaft

Claims (1)

[Claims] 1. A sheet loading plate, a paper feed roller disposed above the sheet loading plate, first pressing means for pressing the sheet loading plate toward the paper feed roller, A holder provided with a separation roller disposed on the downstream side in the sheet conveyance direction, and a plurality of friction plates rotatable so as to be in rolling contact with the separation roller and having different friction coefficients on contact surfaces with the separation roller; And a second pressing means for pressing the holder toward the separation roller.