JP3734005B2 - Sheet feeding device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet feeding apparatus that feeds stacked sheets one by one.
[0002]
[Prior art]
A configuration of a conventional sheet feeding apparatus will be described with reference to FIGS. 6 and 7. In FIG. 6, S is a sheet that is stacked one by one, 20 is a pick roller that forms a feeding means that applies a feeding force to the first sheet of the stacked sheets, and 24 is a sheet S that is fed from the pick roller 20. Reference numerals 21 and 22 denote a pair of separation rollers that form separation means for applying resistance to the sheet fed while being guided by the resistance application member 24.
[0003]
In the above configuration, when only one sheet is fed by the pick roller 20, the sheet is fed between the separation roller 21 and the separation roller 22 while being guided along the upper surface of the resistance applying member 24. It is fed by the rotational drive. Further, when two sheets are fed, for example, by the feeding force of the pick roller 20, conveyance of the lower sheet is blocked by the resistance applying member 24 in the process of being guided along the upper surface of the resistance applying member 24. Only the upper sheet is fed between the separation roller 21 and the separation roller 22 and fed by the rotational drive of the separation roller 21.
[0004]
[Problems to be solved by the invention]
By the way, in the conventional configuration, as shown in FIG. 7, the resistance applying member 24 includes an elastic blade 24b made of, for example, urethane rubber and a holding member 24a that holds the elastic blade 24b. The lower end portion of the elastic blade 24b bent in the direction is fixed to the holding member 24a, and the holding member 24a is fixed to the frame (not shown) of the sheet feeding apparatus by screws.
[0005]
When the sheet feeding is performed using the resistance applying member 24 having the above-described configuration, as shown in FIG. 6, when the leading end of the sheet is curled downward and the angle θ between the lower surface of the sheet and the upper surface of the elastic blade 24b is large, The sheet feeding is hindered by the friction of the elastic blade 24b, causing a problem that the sheet is deformed or a sheet feeding failure occurs.
[0006]
Further, since the elastic blade 24b is worn by friction with the sheet, it is a part to be replaced together with the resistance imparting member 24 depending on the worn state. However, in the conventional configuration, the replacement work is performed by screwing as described above. There was a drawback that it was bothersome.
[0007]
A first object of the present invention is to provide a sheet feeding apparatus capable of accurately feeding a curled sheet from a feeding unit to a separating unit.
[0008]
A second object of the present invention is to provide a sheet feeding apparatus capable of easily exchanging the resistance applying means with one touch.
[0009]
[Means for Solving the Problems]
In order to achieve the above object , the present invention includes a feeding unit that applies a feeding force to the first sheet of the stacked sheets, a resistance applying unit that provides resistance to the sheet fed by the feeding unit, in the sheet feeding apparatus having a separating means for providing a resistance to the sheet being fed is guided by the resistance applying means, said resistance applying means includes a holding member with respect to said separating means is disposed in the upstream side in the sheet feeding , is held at one end to said holding member, a blade member disposed toward the separating means and the other end has a coefficient of friction smaller than the coefficient of friction of the blade member, which is feeding by said feeding means Prevents the leading edge of the sheet from coming into contact with the upper surface of the blade member when the sheet is fed while the angle between the lower surface of the sheet and the upper surface of the blade member exceeds an allowable range. It said blade member top saw including a cover member formed over the predetermined area of As, the integrally formed with the holding member and the cover member, the holding member is elastically deformable hook portion in the width direction at both ends The sheet feeding apparatus main body has a notch portion that forms a holding member mounting portion, and the hook portion is detachable from the notch portion .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a schematic side view showing an embodiment of a sheet feeding apparatus to which the present invention is applied, FIG. 2 is a perspective view of the sheet feeding apparatus viewed from the feeding means side, and FIG. 3 is a sectional side view of a resistance applying member. FIG. 4 is an overall perspective view of the resistance applying member, and FIG. 5 is an overall configuration diagram showing an example of a laser printer to which the sheet feeding apparatus of the present invention is applied.
[0012]
1 and 2, S is a sheet stacked one by one, 20 is a pick roller that forms a feeding means for applying a feeding force to the first sheet of the stacked sheets, and 24 is fed from the pick roller 20. Reference numerals 21 and 22 denote a pair of separation rollers which form separation means for applying resistance to the sheet fed while being guided by the resistance application member 24.
[0013]
An upper roller 21 that forms a pair of separation rollers with the pick roller 20 is pivotally supported by a base member 25, and the rotation of the pick roller 20 is transmitted via gears 26, 27, and 28 when the upper roller 21 is driven. Has been rotated. The lower roller 22 forming the pair of separation rollers is provided in pressure contact with the upper roller 21 with a constant pressure by a spring (not shown).
[0014]
When the upper roller 21 is driven, the driving force is transmitted to the pick roller 20 as described above, and the sheet is fed out to the separation roller pair 21 and 22 side by the rotation of the pick roller 20. The fed sheet comes into contact with the resistance applying member 24 before the pair of separation rollers 21 and 22. For example, when a plurality of sheets are overlapped and fed from the pick roller 20, the resistance is applied by the frictional force of the resistance applying member 24. Resistance is applied or stopped on the lower sheet in contact with the applying member 24, and the uppermost sheet is conveyed toward the pair of separation rollers 21 and 22.
[0015]
If a plurality of sheets are overlapped even in the state of passing through the resistance applying member 24, the lower roller 22 out of the sheets sent to the right side in the figure by the frictional force between the upper roller 21 and the lower roller 22 The abutting ones are stopped, and only the uppermost sheet that touches the pick roller 20 and the upper roller 21 is conveyed toward the conveying roller pair 23. As a result, the stacked sheets are separated one by one, sandwiched between the conveying roller pair 23, and sent to the subsequent stage.
[0016]
Here, the upper roller 21 rotates counterclockwise in FIG. 1, but the lower roller that presses against the upper roller is stopped or provided so as to be able to reversely rotate, and the sheets that enter the sheet are moved one by one. Try to separate. Reference numeral 29 denotes a base member that supports the lower roller 22, and the base member 29 is provided with a notch 29 a that engages with a hook member (details will be described later) provided on the resistance applying member 24.
[0017]
Next, the configuration of the resistance applying member 24 will be described with reference to FIGS. In the figure, reference numeral 24b denotes a blade member made of an elastic body such as urethane rubber. The blade member 24b has a generally bent shape. A support plate 30 is fixed to the back surface of the blade member 24b, and the blade member 24b is attached to the holding member 24a by fixing the support plate 30 to the holding member 24a. Further, on the upper surface side of the blade member 24b, a cover member 24c made of a material having a friction coefficient smaller than that of the blade member 24b and covering a predetermined region of the blade member is provided.
[0018]
Further, hook portions 24d are provided at both ends in the width direction of the holding member 24a as shown in FIG. The hook portion 24d is formed so as to be elastically deformable, and is provided so as to be detachable from the cutout portion 29a of the base member 29 shown in FIG.
[0019]
Regarding the arrangement of the resistance applying member 24 having the above-described configuration, the holding member 24a is arranged on the upstream side in the sheet feeding direction with respect to the lower roller 22 forming the pair of separation rollers, and the tip of the blade member 24b held by the holding member 24a is separated. The rollers 21 and 22 are arranged so as to face the vicinity of the pressure contact portions (in this embodiment, the tip of the blade member 24b is in contact with the upper roller 21).
[0020]
The blade region covered by the cover member 24c may be set as appropriate based on the continuous amount and curl amount of the sheet, the arrangement relationship between the pick roller, the separation roller pair, and the resistance applying member. In short, as shown in FIG. When the sheet fed from the pick roller 20 is fed in a state where the angle θ formed between the lower surface of the sheet and the upper surface of the blade member exceeds the allowable range, the sheet tip is prevented from coming into contact with the rubber surface forming the blade member. What is necessary is just to select so that the front-end | tip of a sheet | seat can be slid well to the roller pair 21 and 22 side.
[0021]
According to the above configuration, even when the leading edge of the sheet S is curled downward, the fed sheet leading edge does not contact the rubber surface forming the blade member, and collides with the cover member 24c made of plastic, for example. The leading edge of the sheet slides along the surface of the cover member 24c and is conveyed toward the blade member 24b exposed from the upper part of the cover member 24c. At the position where the blade member 24b and the front end of the sheet come into contact with each other through the surface of the cover member 24c, the angle θ formed between the lower surface of the sheet and the upper surface of the blade member is also small, so that feeding failure due to friction of the blade member does not occur.
[0022]
In the configuration of the resistance applying member 24, the holding member 24a and the cover member 24c may be independent members or may be provided integrally. Of the upper roller 21 and the lower roller 22 forming the separation roller pair, the lower roller is not necessarily a roller, and may be a fixed pad member that is in contact with the upper roller 21.
[0023]
An example in which the sheet feeding apparatus described above is applied to a laser printer will be described with reference to FIG. In FIG. 5, reference numerals 1a, 1b, and 1c denote sheet feeding units that store sheets as sheets. A photosensitive drum 2 starts rotating based on a signal from a controller (not shown). When the photosensitive drum 2 starts rotating, the surface of the photosensitive drum 2 is uniformly charged by the corona charger 3. An electrostatic latent image is formed on the charged photosensitive drum 2 by a scanning beam from the exposure device 4. When the electrostatic latent image reaches the position of the developing device 5, the electrostatic latent image is developed with toner and visualized as a toner image on the photosensitive drum 2.
[0024]
On the other hand, the sheet feeding units 1 a, 1 b, and 1 c are each equipped with a sheet feeding device according to the present invention, and the toner image formed on the photosensitive drum 2 and the sheet face each other at the position of the transfer unit 6. The selected paper is sent out from the paper supply unit 1a, 1b or 1c at such timing, and the toner image is transferred to the paper. A fixing device 7 fixes the toner image transferred to the paper. 8 is a flap which controls the direction of the conveyed paper. Reference numeral 9 denotes a paper discharge tray serving as a paper discharge unit, which stacks and stores sheets on which image formation has been completed.
[0025]
10 is a paper feed section 1a, 1b, 1c-image forming means 2,3,4,5,6,7-a paper feed path that communicates with the paper discharge tray 9, and 11 is a pull-in path. The sheet is branched from the sheet feeding path 10 on the downstream side in the conveyance direction, and the sheet fed from the fixing device 7 is selectively drawn by switching control of the flap 8. Reference numeral 12 denotes a return path, which branches from the middle of the drawing-in path 11, and has its end joined to the sheet feeding path 10 upstream in the sheet conveying direction with respect to the image forming unit.
[0026]
Therefore, when printing on both sides of the paper, the paper sent out from the fixing device 7 is drawn into the drawing path 11, and the drawn paper is sent out to the return path 12, whereby the one-side recorded paper is formed again. In this way, double-sided printing is executed. In FIG. 5, reference numerals 13 and 14 denote a pair of conveyance rollers provided before and after the flap 8, reference numerals 15 and 16 denote a conveyance roller pair provided on the drawing path 11 and which can be switched between forward and reverse rotations, and 17 denotes a drawing path 11. This is a flap for switching whether the drawn paper is sent out to the return path 12 or returned to the paper feed path 10 side and discharged to the paper discharge tray 9.
[0027]
【The invention's effect】
As described above, according to the sheet feeding apparatus of the present invention, it is possible to accurately feed a curled sheet from the feeding means to the separating means. In addition, the resistance applying means can be easily replaced with a single touch, and the troublesome replacement work can be eliminated.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing an embodiment of a sheet feeding apparatus to which the present invention is applied.
FIG. 2 is a perspective view of a sheet feeding device viewed from a feeding unit side.
FIG. 3 is a cross-sectional side view of a resistance applying member.
FIG. 4 is an overall perspective view of a resistance applying member.
FIG. 5 is an overall configuration diagram illustrating an example of a laser printer to which a sheet feeding apparatus of the present invention is applied.
FIG. 6 is a schematic side view showing the prior art.
FIG. 7 is an overall perspective view of a resistance applying member used in a conventional sheet feeding apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 ... Pick roller, 21 ... Upper roller, 22 ... Lower roller, 23 ... Conveying roller pair, 24 ... Resistance imparting member, 24a ... Holding member, 24b ... Blade member, 24c ... Cover member, 24d ... Hook part, 25, 29 ... base member, 26, 27, 28 ... gear, S ... sheet.

Claims (2)

A feeding means for applying a feeding force to the first sheet of the stacked sheets;
Resistance imparting means for imparting resistance to the sheet fed by the feeding means;
In the sheet feeding apparatus having a separating means for providing a resistance to the sheet being fed is guided by the resistance applying means,
The resistance applying unit includes a holding member disposed on the upstream side in the sheet feeding direction with respect to the separating unit;
One end is held by the holding member, and the other end is disposed toward the separating means, a blade member,
When the have a coefficient of friction smaller than the coefficient of friction of the blade member, feeding sheets underside and the blade member top surface and the angle formed by the sheet is fed in a state exceeding the allowable range by said feeding means and a cover member leading end of the sheet is over the predetermined area of the blade member upper surface to prevent the contact with the blade member upper surface seen including,
The holding member and the cover member are integrally formed,
The holding member has hook portions that are elastically deformable at both ends in the width direction, and the sheet feeding apparatus main body has a notch portion that forms a holding member mounting portion, and the hook portion is the notch portion. A sheet feeding apparatus characterized by being detachable from the sheet. A pick roller that applies a feeding force to the first sheet of the stacked sheets;
A resistance imparting member for imparting resistance to the sheet fed by the pick roller;
Consists upper roller and a lower roller which is in pressure contact with each other, in the sheet feeding apparatus having a pair of separation rollers, which provide resistance to the sheet being fed is guided by the resistance applying means,
The resistance applying means is a holding member disposed on the upstream side in the sheet feeding direction with respect to the lower roller forming the pair of separation rollers,
An elastic blade formed in a generally U-shape so that one end is held by the holding member and the other end faces the vicinity of the pressure contact portion of the separation roller pair;
Has a coefficient of friction smaller than the friction coefficient of the elastic blade, the sheet lower surface and the angle and forms elastic blade upper surface of the sheets and feeding by said pick roller is fed in a state of exceeding the permissible range A cover member that covers a predetermined area of the upper surface of the elastic blade so as to prevent the front end of the sheet from coming into contact with the upper surface of the elastic blade .
The holding member and the cover member are integrally formed,
The holding member has hook portions that are elastically deformable at both ends in the width direction, and the sheet feeding apparatus main body has a notch portion that forms a holding member mounting portion, and the hook portion is the notch portion. A sheet feeding apparatus characterized by being detachable from the sheet.

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