JP2004091184A - Sheet feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeder satisfying both the feedability and separability of sheets by means of an inexpensive arrangement. <P>SOLUTION: The sheet feeder includes a tray 1 on which a plurality of sheets are placed; a separation means 3 for separating the plurality of sheets form one another when feeding the sheets; a pre-separation feeding means 20 for feeding the plurality of sheets from the tray to the separation means 3; and a pre-separation feed guide 40 for guiding the sheets fed by the pre-separation feed means 20. The ends of the sheets fed from the tray 1 collide against the pre-separation feed guide 40. The pre-separation feed guide 40 has different friction coefficients from its downstream to upstream portions in the direction in which the sheets are fed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet conveying apparatus that separates and conveys sheets one by one from a plurality of sheets, and more particularly, to a technique that achieves both sheet conveyance and sheet separation.
[0002]
[Prior art]
[Patent Document 1] JP-A-2002-3001 [Patent Document 2] JP-A-2001-302004
2. Description of the Related Art As a device that separates and conveys sheets one by one from a plurality of sheets, a device in which a position of a sheet tray is movable and a position of a sheet upper surface (a sheet conveyance start position) is always constant is known. In such a sheet conveying apparatus, since the sheet tray is movable, the configuration tends to be complicated and expensive. On the other hand, in an inexpensive sheet conveyance device, the position of the sheet tray is fixed, and friction between the sheets, friction between the feed roll and the sheet, and Utilizing the relationship with the friction between the sheets, the sheets are separated and conveyed one by one from a plurality of sheets.
[0004]
However, it is difficult for the sheet conveyance device having such a configuration to achieve both the sheet conveyance property and the sheet separation property. That is, in such a sheet conveying apparatus, the conveying path is provided with an inclination in a portion of the sheet conveying path immediately before the separating means so as to loosen the leading ends of the plurality of sheets in a wedge shape. When the coefficient of friction of the inclined portion is high (although it is advantageous for separation), the sheet may be caught on the inclined portion and a conveyance failure may occur. On the other hand, if the coefficient of friction of the inclined portion is low (it is advantageous for conveyance), the sheet cannot be sufficiently separated in a wedge shape, and double feeding may occur.
[0005]
As a prior art of the sheet conveying apparatus, for example, Japanese Patent Application Laid-Open No. 2002-3001 discloses a technique in which the friction coefficient at the center in the width direction of the conveying path is higher than the friction coefficient at the end. Patent Document 2 (Japanese Patent Application Laid-Open No. 2001-302004) discloses a technique in which the friction coefficient in the upstream region of the separation member in the transport direction is higher than the friction coefficient in the downstream region. Neither of them exerts a sufficient effect on compatibility between sheet transportability and sheet separation.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of such a technical problem, and an object of the present invention is to provide a sheet conveying apparatus that achieves both sheet conveying properties and sheet separating properties with an inexpensive configuration.
[0007]
[Means for Solving the Problems]
That is, the present invention provides a loading tray on which a plurality of sheets are placed, separating means for separating and transporting the plurality of sheets one by one, and a plurality of sheets from the loading tray to the separating means. And a pre-separation conveyance guide that guides the sheet conveyed by the pre-separation conveyance unit, the leading edge of the sheet conveyed from the loading tray is set to the pre-separation conveyance guide. And the transport guide before separation has a different coefficient of friction from the upstream side to the downstream side in the sheet transport direction.
[0008]
Further, the present invention also provides a loading tray on which a plurality of sheets are placed, separating means for separating and transporting the plurality of sheets one by one, and a plurality of sheets from the loading tray to the separating means. And a pre-separation conveyance guide that guides the sheet conveyed by the pre-separation conveyance means, the mounting tray and the pre-separation conveyance guide are formed at an angle θ (° ], And the pre-separation conveyance guide has a different friction coefficient from the upstream side to the downstream side in the sheet conveyance direction.
[0009]
Further, the present invention also provides a loading tray on which a plurality of sheets are placed, separating means for separating and transporting the plurality of sheets one by one, and a plurality of sheets from the loading tray to the separating means. And a pre-separation conveyance guide that guides the sheet conveyed by the pre-separation conveyance means, the mounting tray is inclined vertically downward, and the pre-separation conveyance is performed. The guide is inclined vertically upward, and the pre-separation conveyance guide is configured to have a different coefficient of friction from upstream to downstream in the sheet conveyance direction.
[0010]
Here, the angle θ [°] can be set to 150 <θ <170 °, and more preferably, 155 <θ <165 °. Here, if the angle θ [°] is less than 150 [°], the conveyance resistance of the sheet becomes excessive, and if it is more than 170 [°], the pre-separating action of the sheet is not sufficiently exhibited, and double feeding may occur. Because there is.
[0011]
In addition, the pre-separation conveyance guide can be a sheet conveyance device in which the downstream portion has a higher coefficient of friction than the upstream portion in the conveyance direction. Here, the friction coefficient μ (upstream portion) of the upstream portion can be set to 0 <μ (upstream portion) <0.3, and the friction coefficient μ (downstream portion) of the downstream portion is 0.6 < μ (downstream portion) <0.9. The difference between the two friction coefficients is preferably 0.3 <μ (downstream portion) −μ (upstream portion) <0.9, and 0.3 <μ (downstream portion) −μ (upstream portion). More preferably, it is set to <0.6.
[0012]
Further, the sheet conveying device may be configured such that an upstream portion of the pre-separation conveyance guide in the conveyance direction is formed of a low friction member having a relatively low friction coefficient, and a downstream portion is formed of a high friction member having a relatively high friction coefficient. .
[0013]
The pre-separation conveyance guide is formed of the same member having a certain coefficient of friction, and a downstream portion of the pre-separation conveyance guide in the conveyance direction is coated with a paint having a higher friction coefficient than the member. It can also be a device. Conversely, the pre-separation conveyance guide is formed of the same member having a certain coefficient of friction, and a sheet formed by applying a paint having a lower coefficient of friction than the member to an upstream portion of the pre-separation conveyance guide in the conveyance direction. It can also be a transfer device.
[0014]
Further, a downstream portion of the pre-separation conveyance guide in the conveyance direction may be a sheet conveyance device configured by a part of a separation unit. More specifically, for example, the separating unit includes a feed roll that is driven to rotate, and a retard roll that is driven and rotated with a torque limiter (in contact with the feed roll). The downstream portion in the transport direction may be a sheet transport device configured by a portion immediately before the nip of the retard roll.
[0015]
Further, the present invention can also be considered as various devices provided with these sheet conveying devices. That is, an automatic document feeder that conveys a plurality of documents one by one by these sheet conveying devices can be used, and an automatic document that optically reads a document conveyed by the automatic document feeder and obtains image data can be used. The image forming apparatus may be an image forming apparatus that forms an image on a recording sheet based on image data obtained by the automatic document reading apparatus (for example, by an electrophotographic process). Further, a recording sheet conveying apparatus that conveys a plurality of recording sheets one by one by these sheet conveying apparatuses may be used, and an image forming apparatus that forms an image on a recording sheet conveyed by the recording sheet conveying apparatus It can also be.
[0016]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiment FIG. 1 is a perspective view illustrating a copying machine (image forming apparatus) 100 according to an embodiment of the present invention. The copying machine 100 includes an automatic document reading device 110 and an image output device 120. The image output device 120 includes a manual feed tray 121, a paper feed tray 122, and a paper discharge tray 123. In this copier, an original is optically read by an automatic original reading device 110, and based on the obtained image data, an image output device 120 forms a toner image on copy paper of a predetermined size by an electrophotographic process, and discharges the toner image. It is discharged from the tray 123.
[0017]
FIG. 2 is a partial cross-sectional view illustrating the configuration of the automatic document reading apparatus 110. First, a basic configuration of the automatic document reading apparatus 110 will be described.
[0018]
The automatic document feeder 110 includes a nudger roll (pre-separation transfer means) 20 along document transfer paths 4 and 50 formed from the document set tray (loading tray) 1 to the document discharge tray 6. A feed roll (separating means 3) 31 and a retard roll (separating means 3: active retard roll) 32, a takeaway roll pair 21, a resist roll pair 22, an out roll pair 23, and a discharge roll pair 24 are provided. Here, the document set tray 1 is formed to be slightly inclined so that the transport direction is not horizontal but obliquely downward. The nager roll 20 is configured to be swingable in a direction indicated by an arrow in the figure, and is configured to contact and separate a document (sheet) placed on the document set tray 1. I have. Further, a torque limiter (not shown) is attached to the rotation shaft of the retard roll 32, and the retard roll 32 does not rotate unless a predetermined or more rotational torque is applied.
[0019]
An unseparated document guide (pre-separation conveyance guide) 40 described below is provided between the nudger roll 20 and the feed roll 31 and the retard roll 32. A document gate 51 is provided between the pre-separation document guide 40 and the document set tray 1, and defines the leading end position in the transport direction of the document placed on the document set tray 1. A part of the transport path between the pair of resist rolls 22 and the pair of out rolls 23 faces the transparent platen glass 7, and a document is detected by a CCD sensor (not shown) at a thick arrow in the drawing. To optically read the image data to generate image data. A switching gate 52 is provided on the post-separation conveyance guide 50 between the out-roll pair 23 and the discharge roll pair 24, and switches the conveyance path of the document in conjunction with the rotation direction of the discharge roll pair 24. .
[0020]
Next, a basic operation of the automatic document reading apparatus 110 will be described. A plurality of documents D (1) to (n) (D (1), D (2),..., D (n)) are placed on the document set tray 1 in order from the upper side. At this time, the positions of the ends of the originals D (1) to (n) in the transport direction are regulated by the original gate 51. When the user presses the start button of the copying machine 100, the nudger roll 20 is pressed against the document D (1) and starts rotating. Then, in addition to the gravity caused by the inclination of the document set tray 1, the document D (1) has a frictional force with the nudger roll 20, and the other documents D (2) to D (n) have a frictional force between the documents. As a result, the document gate 51 is pushed up and reaches the document guide 40 before separation, the feed roll 31 and the nudger roll 32.
[0021]
Here, even if a plurality of, for example, two originals D (1) and D (2) are transported to the nip portion between the feed rolls 31 and 32, the feed roll 31 and the originals D (1) and D (1) Due to the frictional relationship between (1) and the original D (2), and between the original D (2) and the retard roll 32, only the upper original D (1) is separated and conveyed. Thereafter, the document D (1) is transported by the take-away roll pair 21 and the registration roll pair 22, and is optically read by the CCD sensor when passing through the reading position indicated by the thick arrow, thereby generating image data.
[0022]
When reading only one side of the document, the document D (1) is subsequently discharged to the discharge tray 6 by the discharge roll pair 24. On the other hand, when reading both sides of the document, the switching gate 52 operates at the time when the rear end of the document D (1) in the transport direction passes through the switching gate 52, and secures the both-side transport path 53 and discharge rolls. By reversing the rotation direction of the pair 24, the conveyance direction of the document D (1) is reversed, and the document D (1) is conveyed to the (normal) separated document guide 50 via the double-sided conveyance guide 53, At the reading position again, the surface of the document D (1) opposite to the leading end is optically read, and image data is similarly generated. Then, the document D (1) is discharged to the discharge tray 6 by the discharge roll pair 24.
[0023]
Such an operation is performed for each of the originals D (1) to (n), and a plurality of originals D (1) to (n) are automatically read.
[0024]
By the way, in such an automatic document feeder 110, the present inventor has made the following contrivance in order to achieve both the document transportability and the separability. In the following, aspects of the device will be described as examples.
[0025]
Embodiment FIG. 3 is a perspective view of the vicinity of the retard roll 32 of the automatic document feeder 110 according to the present embodiment. FIG. 4 is a cross-sectional view around the retard roll 32 of the automatic document feeder 110 according to the present embodiment. As shown in these figures, the leading edge of the document conveyed from the document tray 1 is configured to collide with the document guide 40 before separation. That is, the document tray 1 and the pre-separation document guide 40 form an angle θ [°] = 155 [°], and the document conveyance direction of both the document tray 1 and the post-separation document guide 50 is vertically downward (see FIG. 4, the original document guide 40 before separation is inclined vertically upward (Y direction in FIG. 4).
[0026]
As shown in FIG. 4, a part of the retard roll 32 protrudes on the transport path from the nip area N between the feed roll 31 and the retard roll 32 in the area 4 immediately before the nip in the document transport direction. A part of the retard roll 32 together with the pre-separation original guide 40 forms the pre-separation conveyance guide 4. In this embodiment, notched portions 50a and 50b are provided in a part of the separated document guide 50 facing the roll main bodies 32a and 32b of the retard roll 32, respectively. Notch portions 40a, b may be provided not only in the post-separation document guide 50 but also in a part of the pre-separation document guide 40 facing the roll main bodies 32a, b as shown in FIG. Modification 1).
[0027]
FIG. 6A illustrates the configuration of the pre-separation document guide 40 of the automatic document feeder 110 according to the present embodiment. The pre-separation document guide 40 is divided into an upstream side and a downstream side in the document conveyance direction, and the upstream side portion is a low friction member having a relatively low friction coefficient (friction coefficient: μ (41)). 41, a downstream portion thereof is constituted by a high friction member 42 having a relatively high friction coefficient (friction coefficient: μ (42)). Here, assuming that the friction coefficient of the retard roll 32 is μ (32), there is a relationship of μ (41) <μ (42) <μ (32) between the values of these friction coefficients. That is, a part of the retard roll 32 (the portion immediately before the nip) forms the region 4 immediately before the nip in the document conveying direction.
[0028]
It should be noted that other configurations can be adopted as the configuration of the pre-separation document guide 40. For example, as shown in FIG. 6B, a paint 43 having a relatively high friction coefficient (friction coefficient: μ (43)) is applied to a downstream portion of the surface of the base material constituted by the low friction member 41 in the transport direction. (Modification 2). Here, the values of these friction coefficients have a relationship of μ (41) <μ (43) <μ (32). Further, as shown in FIG. 6C, a paint 44 having a relatively low friction coefficient (friction coefficient: μ (44)) is applied to the upstream portion of the surface of the base material constituted by the high friction member 42 in the transport direction. (Modification 3). Here, the values of these friction coefficients have a relationship of μ (44) <μ (42) <μ (32).
[0029]
As shown in FIG. 7A, the surface of the paint 43 having a high friction coefficient gradually increases over the entire surface of the original guide 40 before separation (Modification 4), or only the downstream region of the original guide 40 before separation. With regard to (5), the area of the paint 43 having a high friction coefficient may gradually increase (Modification 5). Further, as shown in FIG. 7C, a single member 45 having a certain friction coefficient (friction coefficient: μ (45)) may be used. Here, the values of these friction coefficients have a relationship of μ (45) <μ (32).
[0030]
In these examples and modifications, the low friction member 41 is made of a resin such as plastic, and the high friction member 42 is made of a rubber material such as urethane or silicon. The paint 43 having a high friction coefficient includes urethane (urethane coat), and the paint 44 having a low friction coefficient may be a resin film material, nickel plating, or the like.
[0031]
FIG. 8 illustrates a state around the document guide 40 before separation during document conveyance. FIG. 8A shows a state where a plurality of documents D (1) to D (n) are set on the document tray 1. In this state, the leading ends of the originals D (1) to D (n) in the transport direction are blocked by an original gate 51 (not shown) and aligned at a fixed position. When the conveyance of the documents (1) to (n) is started, as shown in FIG. (High-friction region of the part) and is preliminarily loosened. The originals above the originals D (1) to (n) collide with the surface of the retard roll 32 having higher frictional resistance and are preliminarily loosened.
[0032]
When the originals D (1) to (n) are further conveyed, they are separated one by one in a nip area N between the feed roll 31 and the retard roll 32, as shown in FIG. Here, when two originals D (1) and (2) exist in the nip area N, the retard roll 32 does not rotate, only the feed roll 31 rotates, and only the upper original D (1) is rotated. Is transported. At this time, since the retard roll 32 is not rotating, a large transport resistance is caused for the document transport, but the transport failure does not occur because the remaining document D (2) already exists in the nip area N. On the other hand, when only one document D (1) exists in the nip area N, both the feed roll 31 and the retard roll 32 rotate to convey the document D (1). At this time, since the retard roll 32 is rotating (the retard roll 32 itself has a large coefficient of friction), it does not become a conveyance resistance for document conveyance, and the next document D (2) is smoothly conveyed to the nip area N. can do.
[0033]
As described above, in the automatic document reading apparatus 110 according to the present embodiment, it is possible to achieve both the document conveying property and the document separating property with a low-cost configuration.
[0034]
In each of the embodiments, the present invention is applied to the automatic document reading apparatus 110, more specifically, the paper conveying apparatus (sheet conveying apparatus) of the automatic document reading apparatus 110. However, the present invention is not limited to this. The present invention can also be applied to a paper conveying device of the manual feed tray 121 or the paper feed tray 122.
[0035]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a sheet conveying apparatus that achieves both sheet conveying properties and sheet separating properties with an inexpensive configuration.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a copying machine (image forming apparatus) according to an embodiment of the present invention.
FIG. 2 is a partial cross-sectional view illustrating a configuration of an automatic document reading apparatus.
FIG. 3 is a perspective view of the vicinity of a retard roll of the automatic document feeder according to the embodiment.
FIG. 4 is a sectional view of the vicinity of a retard roll of the automatic document feeder according to the embodiment.
FIG. 5 is a cross-sectional view around a retard roll of an automatic document feeder according to a modification.
FIG. 6 illustrates a configuration of a document guide before separation of the automatic document feeder according to the embodiment and the modification.
FIG. 7 illustrates a configuration of a document guide before separation of an automatic document feeder according to a modified example.
FIG. 8 is a diagram illustrating a document conveying operation of the automatic document conveying apparatus according to the embodiment.
[Explanation of symbols]
Reference Signs List 100: Copier (image forming apparatus), 110: Automatic document reading apparatus, 1: Document set tray (placement tray), 20: Nager roll (conveyance means before separation), 31: Feed roll (separation means), 32 ... Retard roll (separating means, conveyance guide before separation), 40: original guide before separation (conveyance guide before separation), 41: low friction member, 42: high friction member, 44: low friction paint, 43: high friction paint

Claims (6)

A loading tray on which a plurality of sheets are placed, separating means for separating and transporting the plurality of sheets one by one, and before separation for transporting a plurality of sheets from the loading tray to the separating means In a sheet conveying apparatus including a conveying unit and a pre-separation conveyance guide that guides a sheet conveyed by the pre-separation conveyance unit,
While the leading edge of the sheet conveyed from the mounting tray collides with the pre-separation conveyance guide,
The sheet conveyance device, wherein the pre-separation conveyance guide has a different friction coefficient from an upstream side to a downstream side in a sheet conveyance direction. The sheet conveying device according to claim 1, wherein the pre-separation conveyance guide has a higher coefficient of friction at a downstream portion than at a portion upstream of the conveyance direction. 3. The sheet conveyance according to claim 1, wherein an upstream portion of the pre-separation conveyance guide in the conveyance direction is formed of a low friction member having a relatively low friction coefficient, and a downstream portion is formed of a high friction member having a relatively high friction coefficient. apparatus. The pre-separation conveyance guide is formed of the same member having a certain friction coefficient, and a coating material having a higher friction coefficient than the pre-separation conveyance guide is applied to a downstream portion of the pre-separation conveyance guide in the conveyance direction. Item 3. The sheet conveying device according to item 1 or 2. The sheet conveying apparatus according to claim 1, wherein a downstream portion in the conveying direction of the pre-separation conveying guide is configured by a part of a separating unit. The separation unit has a feed roll that is driven to rotate, and a retard roll that is driven and rotated with a torque limiter,
The sheet conveying device according to claim 1, wherein a downstream portion of the pre-separation conveyance guide in a conveyance direction is configured to be a portion immediately before a nip of a retard roll.

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