JP2004137013A - Sheet material feeding apparatus and image forming apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To feed many kinds of sheet materials without non-feed or double feed even at a lapse of time. <P>SOLUTION: Extension sections 3b, 3b are extended to both the ends of an inclined member 3 that is pressure-welded to a feeder roller 1 at a nip formation section N by a spring 2. Rising sections 3c, 3c are provided at end sections that are wider than the width of the sheet materials that can be fed, and elliptical support holes 3d, 3d are formed at the upper portion. Support pins 3e, 3e are implanted at the lower portion and are slidably fitted to the guide section of an apparatus body. A center shaft 1a in the feed roller 1 is inserted into the support holes 3d, 3d rotatably and slidably. The direction of the long axis of the support hole 3d is allowed to agree with the traveling direction of the inclined member 3, thus always constantly maintaining an angle between a tangential line in the nip formation section N in the feed member 1 and an inclination surface 3f in the inclined member 3 even if the pressure welding surface of the inclined member is worn out. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet material feeding apparatus for separating and feeding sheet materials stacked on a sheet material stacking member one by one from a top sheet material, and an image forming apparatus such as a facsimile, a printer, a copying machine, etc. Equipment related.
[0002]
[Prior art]
Conventionally, as a sheet material feeding device of this type, a feeding member that presses against the uppermost sheet material and feeds the sheet material to a separation unit, and a front end portion that presses against the feeding member and feeds the sheet material in the feeding direction. There is known a sheet feeding device having a gate member (corresponding to an “inclined member” of the present invention) having an inclined surface which is located on the side and abuts on the front end in the sheet feeding direction (for example, see Patent Document 1). .
[0003]
However, in the above-mentioned Patent Document 1, the upper edge portion of the gate member that is in sliding contact with the feeding member is flat, the nip forming portion is wide, and the inclined surface is inclined at a predetermined angle due to variations in the member. It was difficult to maintain the angle. Such a gate member has a complicated shape and is usually formed of a synthetic resin. However, when the number of passed sheets increases, abrasion occurs due to friction with the sheet material, and the angle of the inclined surface is reduced by the abrasion. As a result, the predetermined angle cannot be maintained, and there is a possibility that an unpredictable transport load occurs to cause a transport failure.
[0004]
Further, when the uppermost sheet material is being conveyed in the image forming unit, the feeding member is shut off from driving, but while the preceding sheet material is nipped between the feeding member and the gate member, the feeding is stopped. When the trailing end of the preceding sheet material passes through the nip forming portion, the leading end of the next sheet material is fed to the gate member by the accompanying rotation of the feeding member. Can be
At this time, the friction coefficient between the sheet materials is high or large, and the friction coefficient between the next sheet material and the next sheet material is larger than the friction coefficient between the preceding sheet material and the next sheet material. When the sheet material is low, the next sheet material may get over the gate member, and there is a possibility that the sheet material may be multi-fed.
[0005]
In view of such a point, the present applicant previously formed the contact surface with the feeding member on a ridge along the axis of the feeding member so that the nip forming portion with the feeding member was made as short as possible. And applied for the application (Japanese Patent Application No. 2002-56456).
FIG. 10 is an exploded perspective view showing an example of the mounting configuration of the inclined member. In FIG. 10, the inclined member 103 is pressed by a feeding roller 101 as a sheet material feeding member by the urging force of a spring 102. This inclined member 103 is slidably mounted on upper guide rails 104a, 104a formed on a sheet feeding cassette 104 (or the apparatus main body), the upper supporting portions 103a, 103a constituting a sheet material stacking member structure. The direction of movement is regulated. Although not shown, the lower support portion of the inclined member 103 is in sliding contact with a lower guide portion (not shown) provided in the paper feed cassette 104 (or the apparatus main body), and the inclined member 103 is driven by a force applied when the sheet material is conveyed. It plays the role of receiving the turning force.
[0006]
FIG. 11 is a cross-sectional view showing another example of the conventional mounting structure of the inclined member. In FIG. 11, the inclined member 203 is pressed against the feed roller 201 by the urging force of a spring (not shown). The tilting member 203 slides with its upper supporting portion 203a being regulated by the upper guide portion 204a formed in the paper feed cassette 204 (or the apparatus main body) and the lower supporting portion 203b being restricted in the moving direction by the lower guide portion 204b. At the same time, it has a function of locking the inclined member 203 from rotating clockwise due to the force acting in the direction of arrow T when the sheet material is conveyed.
[0007]
[Patent Document 1]
JP-A-8-91612 (page 3, FIG. 1)
[0008]
[Problems to be solved by the invention]
However, in such a conventional sheet feeding apparatus, the inclined member is attached to the apparatus main body in the same manner as the sheet feeding tray or the feeding member. From the center) to the mounting position of the inclined member, a plurality of members are interposed. In addition, there is a sheet feeding tray in which a feeding member is attached together with an inclined member. Even in this case, the feeding / inclined ends such as the feeding member, its bearing, the inclined member mounting portion of the sheet feeding tray, and the inclined member. At least two members are interposed between the portions.
Therefore, there is a problem that the configuration of the sheet material feeding device is complicated, high accuracy of each component is required, assembly workability is reduced, and production cost is increased.
Further, with this, the angle θ _p2 formed between the nip forming portion N of the feeding roller 201 and the inclined surface of the inclined member 203 shown in FIG. 11 fluctuates due to the accumulated error of each component. It is a well-known fact that if the angle θ _p2 deviates from a predetermined value, non-feeding or double feeding of the sheet material is likely to occur.
The present invention has been made in view of the above points, and includes a sheet feeding apparatus capable of suppressing the variation in the angle θ _p2 by reducing the number of components as much as possible, and a sheet feeding apparatus. It is an object to provide an image forming apparatus.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a feeding member that feeds the sheet material to a separation unit by rotating while pressing against the sheet material stacked on the sheet material stacking member, and An inclined member having an inclined surface against which an abutting surface formed of a ridge extending along an axial direction abuts against a leading end of the sheet material in a feeding direction, wherein the inclined member is provided with the inclined member. An object of the present invention is to provide a sheet material feeding device mounted on a feeding member so as to be relatively displaceable in a direction orthogonal to the axis thereof.
The direction orthogonal to the axis may be parallel to the moving direction of the inclined member, and is orthogonal to the axis of the feeding member and a line at which the contact surface and the inclined surface intersect with each other. It may be made parallel to the line.
[0010]
Further, in the above-described sheet material feeding device, the inclined member is provided at a pair of extension arms extending at both ends of a contact surface with the feeding member, and provided at an end of each extension arm, and a gap between the extension arms is provided. Has a pair of rising portions wider than the width of the sheet material that can be conveyed, and a pair of oblong support holes formed in each rising portion, and the central axis of the feeding member rotates in the pair of support holes. In addition, it is preferable that the sheet is slidably inserted, and it is more preferable that the extension arm is provided with a guide surface for guiding the sheet material separated at the contact surface to the transport unit.
The present invention also provides an image forming unit including the above-described sheet material feeding device and an image forming unit for forming an image on a sheet material fed from the sheet material feeding device.
[0011]
The sheet feeding device according to the present invention and the image forming apparatus including the same are configured as described above, and the inclined member is directly mounted on the central axis of the sheet feeding member so as to be relatively displaceable with a simple configuration. Therefore, unlike a conventional configuration in which a plurality of members are interposed between the inclined member and the sheet material feeding member, there is no possibility that the relative positions vary due to the accumulated error between the two members, and various types of sheet materials can be used. Sheets can be separated and fed one by one without causing feeding or double feeding, and image formation can be performed reliably.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a sectional view showing a main part of a sheet feeding apparatus according to a first embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is a configuration diagram schematically showing the entire configuration thereof. First, an overall configuration of the sheet feeding apparatus will be schematically described with reference to FIG. A bottom plate 11a, which is a sheet material stacking member capable of stacking a plurality of sheet materials 12, is swingably supported at one end by a support shaft 11b in a sheet cassette 11 which is detachable from the apparatus main body 10 of the image forming apparatus. The free end is constantly urged upward by a sheet feeding pressure P (see FIG. 1) by a sheet feeding spring 13 engaged with the sheet feeding cassette 11.
On the other hand, the apparatus main body 10 is provided with a feeding roller 1 which is a feeding member for the sheet material 12 so as to be able to press against the leading end of the uppermost sheet material 12a of the sheet material 12 stacked on the bottom plate 11a. The contact surface 3a of the inclined member 3 having the inclined surface 3f is pressed against the feeding roller 1 by the separating pressure Q (see FIG. 1) by the spring 2, and these constitute a separating portion for the sheet material 12. I have. The uppermost sheet material 12a separated by the separation unit is fed on a conveyance guide portion 11c provided on both side sheet cassettes 11 of the inclined member 3, and then fed by a pair of conveyance rollers 4 to an image forming unit (not shown). Conveyed. The guide 11c may be provided on the apparatus main body 10 side.
[0013]
Next, with reference to FIGS. 1 and 2, extension arms 3 b, 3 b are provided on both ends of the contact surface 3 a of the inclined member 3 with the feed roller 1 and outside the contact surface in the longitudinal direction, A pair of rising portions 3c, 3c are provided at both ends which are wider than the width of the sheet material that can be fed, and oval support holes 3d, 3d are integrally formed at the upper portions thereof, and support pins 3e are formed at the lower portions thereof. , 3e are slidably mounted on a guide unit (not shown) provided in the apparatus main body or the paper feed cassette so as to be movable in the operation direction of the paper feed pressure Q. Then, the center shaft 1a of the feed roller 1 whose both ends are rotatably supported by the apparatus main body or the paper feed cassette is rotatably and slidably inserted into the support holes 3d, 3d, as shown in FIG. The inclined member 3 can move forward and backward while maintaining a parallel state with respect to one axis 1A.
[0014]
According to such a configuration, the inclined member 3 can be directly mounted on the center shaft 1a, which is the reference position of the feeding roller 1, and it is possible to design, form and assemble parts using a plurality of conventional intermediate members. It is possible to converge the above-described variation in the angle θ _p2 due to the accumulated error, and to stabilize the sheet conveyance quality.
In addition, when the inclined member having a complicated shape is formed of a resin material, even if a large amount of sheet material is fed to cause abrasion on the contact surface with the feeding roller, the abrasion direction of the inclined member is changed. Since the direction is the same as the direction of the parallel movement, it is possible to maintain the angle θ _p2 even with the elapse of time, and it is possible to stabilize the sheet feeding / transport quality.
[0015]
Hereinafter, the principle of operation of the sheet feeding apparatus according to the present invention will be described theoretically.
FIG. 4 is an explanatory view showing the separation section in an enlarged manner, and the sheet material 12 is kept horizontal. When the sheet feeding angle of the sheet material is horizontal as described above, the lowest point of the feeding roller 1 is the point of application of the sheet feeding pressure P. When this point X is the origin, the feeding roller 1 and the inclined member The tangent to the inclined surface 3f of 3 becomes the nip forming portion N.
In such a configuration, r: radius of the feeding roller P: paper feeding pressure Q: separating pressure θ ₁ : angle (°) between the pressing direction of the separating pressure and the feeding direction of the sheet material
θ ₂ : Angle (°) between the inclined surface of the inclined member and the feeding direction of the sheet material
θ _p2 : Angle (°) between the tangent line of the nip forming portion of the feed roller and the inclined surface of the inclined member
N: Nip forming part μ ₁ : Coefficient of friction μ between the feeding roller and the sheet material μ ₂ : Coefficient of friction μ between the inclined surface of the inclined member and the tip of the sheet material _{p p12} : First and second sheets of the sheet material Coefficient of friction between eyes _Δp : Difference in coefficient of friction between sheet materials.
[0016]
Here, θ _p2 = θ ₁ + θ ₂ −90 (1)
When the point X is set as the origin, the coordinates ( _Nx , _Ny ) of the nip forming portion N are as follows.
N _x = r · cos (−θ ₁ ) (2.1)
N _y = r + r · sin (−θ ₁ ) (2.2)
Now, as an example, if r = 16, θ ₁ = 76 °, θ ₂ = 60 °, N (3.871, 0.475) is obtained.
Next, an inequality is created based on the relationship between the forces acting on the sheet material 12. In the present invention, the area until the leading end of the sheet material 12 reaches the nip forming portion N and the nip entry process in which the nip forming portion N is sandwiched. The following two cases will be described with reference to FIGS. 5 and 6 (a) and (b).
[0017]
Referring to FIG. 5, immediately before the nip, the front end of the sheet material 12 is subjected to a normal reaction _Rf from the inclined surface 3 _f of the inclined member 3. In order for the leading end of the sheet material 12 to reach the nip forming portion N, bending deformation is required. At this time, the force acting on the leading end of the sheet material differs depending on the type of the sheet material.
Now, assuming that the leading end of the sheet material is in the same direction as the tangent line of the outer periphery of the feeding roller at the nip forming portion N, and the leading end of the sheet material does not come into contact with other members except at the position where the feeding pressure acts. Since the conveying force of the uppermost sheet material 12a is (μ ₁ −μ _p12 ) · P and the double feeding force of the multi-feed paper is Δμ _p · P, in order to prevent non-feed NF,
(Μ ₁ −μ _p12 ) · P> R _f · A
∴P> R _f · A / (μ ₁ −μ _p12 ) (3)
To prevent double feed MF,
Δμ _p · P <R _f · A
∴P <R _f · A / Δμ _p (4)
A = sin θ _p2 + μ ₂ · cos θ _p2 (5)
[0018]
Next, a process in which the leading end of the sheet material enters the nip forming portion will be described with reference to FIGS. At this time, the sheet material leading end is subjected to normal force Q _n and its frictional force mu ₂ · Q _n from the inclined surface of the inclined member. It is from the feed roller to reverse by the force caused by the sheet leading end is pinched subjected to frictional forces mu ₁ · F _n between normal force F _n to the conveying direction. Therefore, the separation pressure Q is
F _n + R _f · B = Q (6)
_{Q n · B = Q (7} )
B = cos θ _p2 -μ ₂ · sin θ _p2 (8)
Further, as the conditions for preventing the non-feed in the longitudinal direction of the sheet material, from the above equations (6) and (7), (μ ₁ −μ _p12 ) · P + μ ₁ · F _n > Q _n · A
∴P> ｛(A / B) -μ ₁ ｝ Q / (μ ₁ -μ _p12 )
+ Μ ₁ · R _f · B / (μ ₁ -μ _p12 ) (9)
[0019]
Conditions to prevent double feed include:
Δμ _P · P + μ _p12 · F _n <Q _n · A
By substituting equations (6) and (7) into this, P <｛(A / B) −μ _p12 ｝ Q / Δμ _p
+ Μ _p12 · R _f · B / Δμ _p (10)
Summarizing the coefficients of equations (9) and (10) collectively:
P> CQ + D (11)
P <G · Q + H (12)
C = {(A / B) -μ 1} / (μ 1 -μ p12) (13)
_{D = μ 1 · R f ·} B / (μ 1 -μ p12) (14)
G = {(A / B) -μ _p12 } / Δμ _p (15)
H = μ _p12 · R _f · B / Δμ _p (16)
[0020]
Next, FIG. 7 is a cross-sectional view showing a main part of Embodiment 2 of the present invention, and its exploded perspective view is the same as FIG. 2 of Embodiment 1 except that the major axis direction of the support hole 3d is slightly different. Since they are present, their illustration is omitted. 7 are the same as those in FIG. 1 and their detailed description is omitted.
The configuration of the second embodiment is the same as that of the first embodiment shown in FIG. 1, but differs from the first embodiment in that the longitudinal direction of the support hole 3 d provided above the rising portion of the inclined member 3 is supplied. The line 1n connecting the axis 1A of the feed roller 1 and the nip forming portion N of the feed roller 1 is set to the same direction, and the moving direction of the support pin 3e shown in FIG. Other configurations are the same as those of the first embodiment.
Also in the second embodiment, when the sheet material is conveyed, the contact surface 3a of the inclined member 3 with the feed roller 1 is worn following the outer peripheral surface of the feed roller 1. The position of the ridge portion (nip forming portion N) of the contact surface 3a with the feeding roller 1 can always be kept constant without displacement.
[0021]
FIG. 8 is an exploded perspective view showing a main part of Embodiment 3 of the present invention. In the third embodiment as well, the constituent members are the same as those in the first and second embodiments.
In the third embodiment, the extension members 3b, 3b formed on both sides of the inclined member 3 are supplied with the sheet material of the inclined member 3 from a position slightly lower than both end surfaces of the contact surface 3a with the feeding roller 1. It is formed so as to connect the downstream portion 3g in the feeding direction, and other configurations are the same as those of the first and second embodiments.
According to the configuration of the third embodiment, the sheet material conveyance guides 11c (FIG. 2) located at both ends of the inclined member 3 conventionally provided in the large-sized sheet cassette (or the apparatus main body) are deleted. Since it can be formed on a small inclined member, the formability can be improved, and at the same time, the position of the transport guide can be set with high accuracy.
[0022]
Next, FIG. 9 is a configuration diagram of a copying machine which is an example of an image forming apparatus provided with the above-described sheet feeding device.
In the copying machine 20, an optical writing system 23 forms a latent image on a photoconductor 25 provided in an image forming system 24 based on image data read by an optical reading system 22 provided in a copying machine body 21. Then, the developing device 26 of the image forming system 24 converts the latent image into a visible image using toner.
The lower portion of the copying machine main body 21 is provided with the above-described sheet material feeding device P, and the sheet materials 12 stacked from the sheet material feeding device P are fed one by one by the feeding roller 1, The pair 4 is transported to the image forming system 24 through the transport path 27, and the visible image on the photoconductor 25 is transferred to the sheet material 12.
[0023]
When the transfer is completed, the sheet material 12 is conveyed to a fixing device 28, where the visible image is fixed, and then discharged to an external discharge tray 30 by a discharge roller pair 29. Further, at the time of double-sided image formation, the sheet material 12 is conveyed from the reversing conveyance path 31 to the double-sided device 32 by a paper ejection branching pawl (not shown), and once stored in the double-sided tray 33, the traveling direction is reversed. The image is again fed from 34 to the image forming system 24 to form an image on the back surface, and is discharged onto the sheet discharge tray 30 through the fixing device 28.
Although only one sheet material feeding device P is shown in FIG. 9 for simplification of the drawing, a plurality of sheets having different sizes can be provided as needed. The image forming apparatus having the apparatus is not limited to a copying machine, and can be applied to a facsimile, a printer, and the like without any trouble.
[0024]
【The invention's effect】
As described above, according to the sheet material feeding apparatus of the present invention, an extremely simple and low-cost configuration reduces accumulated errors in designing, forming parts, and assembling. The transport quality can be stabilized.
Further, according to the image forming apparatus provided with the above-mentioned sheet material feeding device, it is possible to reliably separate and feed out various kinds of sheet materials one by one without non-feeding or double feeding to the image forming unit. Image formation without selecting.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a main part of a first embodiment of the present invention.
FIG. 2 is an exploded perspective view of the same.
FIG. 3 is a configuration diagram schematically showing the overall configuration.
FIG. 4 is an explanatory view showing an enlarged view of the separation portion.
FIG. 5 is an explanatory view showing a force relationship acting on the front end of the sheet material immediately before the nip.
FIG. 6 is an explanatory diagram showing a force relationship acting on the leading end of the sheet material when the nip enters.
FIG. 7 is a sectional view showing a main part of a second embodiment of the present invention.
FIG. 8 is an exploded perspective view showing a main part of a third embodiment of the present invention.
FIG. 9 is a configuration diagram illustrating an example of an image forming apparatus including the sheet material feeding device.
FIG. 10 is an exploded perspective view showing an example of a conventional sheet material feeding device.
FIG. 11 is a cross-sectional view showing another example of a conventional sheet material feeding device.
[Explanation of symbols]
1: feed roller 2: spring 3: inclined member 4: transport roller pair 10: main body 11: paper feed cassette 12: sheet material 20: copying machine

Claims (6)

A feeding member that feeds the sheet material to the separation unit by rotating by pressing against the sheet material stacked on the sheet material stacking member, and an abutting surface formed by a ridge along the axis of the feeding member are pressed against the feeding member. A sheet member feeding device having an inclined member having an inclined surface against which a leading end of the sheet member in the feeding direction abuts.
A sheet feeding device, wherein the inclined member is mounted on the feeding member so as to be relatively displaceable in a direction perpendicular to an axis thereof. The sheet feeding device according to claim 1, wherein a direction orthogonal to the axis is parallel to a moving direction of the inclined member. The direction orthogonal to the axis is parallel to a line orthogonal to an axis of the feeding member and a line intersecting the contact surface and the inclined surface of the inclined member. Sheet material feeding device. The inclined member is provided at a pair of extension arms extending to both ends in the longitudinal direction of a contact surface with the feeding member, and provided at an end of each extension arm, and a gap between the extension arms is a width of a conveyable sheet material. It has a wider pair of rising portions and a pair of oblong supporting holes formed in each rising portion, and the central axis of the feeding member is inserted through the pair of supporting holes so as to rotate and slide freely. The sheet feeding device according to any one of claims 1 to 3, wherein: An extension arm extending on both ends in the longitudinal direction of a contact surface of the inclined member with the feeding member is provided with a guide surface for guiding a sheet material separated by the contact surface to a conveyance unit. The sheet material feeding device according to any one of claims 1 to 4, wherein An image forming apparatus comprising: the sheet material feeding device according to claim 1; and an image forming unit that forms an image on the sheet material fed from the sheet material feeding device.

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