Sheet conveying device

This application claims priority from Japanese Patent Application No. 2012-048126, filed on Mar. 5, 2012, the entire disclosure of which is incorporated herein by reference.

1. Field of the Invention

The present invention relates to a sheet conveying device.

2. Description of Related Art

A known sheet conveying device is configured to convey sheets from a tray while separating the sheets one by one, and comprises a convey roller, a separation pad disposed opposite to the convey roller, and a sheet pressing member, such as a leaf spring, configured to press the sheet against the convey roller.

In such a sheet conveying device, it is preferable to periodically clean a friction surface of the separation pad so that the sheet conveying device can perform stable sheet conveyance. The friction surface of the separation pad is brought into contact with a sheet so as to apply conveyance resistance to the sheet.

Therefore, a need has arisen for a sheet conveying device that provides an improved workability of cleaning a separation pad.

According to an embodiment of the invention, a sheet conveying device comprises a roller configured to convey sheets in a sheet conveying direction, a separation pad disposed opposite to the roller and configured to separate the sheets one by one, a pressing mechanism disposed on an opposite side of the separation pad from the roller and configured to press the separation pad against the roller, a roller pressing member comprising a roller contacting portion configured to contact and press the roller, and a holding member which holds the separation pad and the roller pressing member. The holding member is configured to move relative to the roller between a distant position and a close position in which the holding member is closer to the roller than in the distant position. The pressing mechanism is configured to press the separation pad against the roller when the holding member is in the close position. The roller pressing member is configured such that when the holding member is in the distant position, at least the roller contacting portion of the roller pressing member is retracted from a first surface of the separation pad in a direction away from the roller. The first surface of the separation pad faces the roller.

Other objects, features, and advantages will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawings.

For a more complete understanding of the invention, the needs satisfied thereby, and the features and technical advantages thereof, reference now is made to the following descriptions taken in connection with the accompanying drawings.

FIG. 1 is a perspective view of a multi-function device comprising a sheet conveying device, according to a first embodiment of the invention.

FIG. 2 is a center cross-sectional view of the multi-function device of FIG. 1 .

FIG. 3 is a perspective view of the multi-function device of FIG. 1 .

FIGS. 4A and 4B are schematic diagrams showing the structure of the sheet conveying device according to the first embodiment of the invention.

FIGS. 5A and 5B are schematic diagrams showing the structure of the sheet conveying device according to the first embodiment of the invention.

FIG. 6 is a view of a holding member and a pressing mechanism according to the first embodiment of the invention.

FIGS. 7A and 7B are schematic diagrams showing the structure of a sheet conveying device according to a second embodiment of the invention.

Embodiments of the invention and their features and technical advantages may be understood by referring to FIGS. 1-7B , like numerals being used for like corresponding parts in the various drawings.

According to a first embodiment of the invention, a sheet conveying device is applied to a multi-function device having a facsimile function, a copying function, and a printing function.

As shown in FIG. 1 , a multi-function device 1 according to the embodiment includes an operation panel 3 C on an inclined surface 3 provided on the upper face of the multi-function device 1 . The operation panel 3 C includes an operation unit 3 A and a display 3 B. The operation unit 3 A is a portion to be operated by a user for utilizing the facsimile and copying functions. The display 3 B serves to notify various types of information to the user.

Referring to FIG. 2 , a scanning unit 5 that reads information, such as characters and images, on a document sheet is provided below the operation panel 3 C. The scanning unit 5 is activated when the facsimile function or the copying function is performed. In this embodiment, the sheet conveying device is applied to an automatic document feeder 7 that feeds document sheets to the scanning unit 5 .

An image forming unit 9 that forms an image on a sheet, e.g., a recording sheet, is provided below the scanning unit 5 and the automatic document feeder 7 , with a clearance therebetween. The image forming unit 9 prints facsimile data received through a telephone line, or print data transmitted from a computer or the like, on the sheet.

In this embodiment, the image forming unit 9 is an electrophotographic image forming unit configured to form an image on the sheet by transferring a developing agent onto the sheet. To be more specific, the image forming unit 9 includes a developing unit 9 B having a photosensitive drum 9 A, an exposure unit 9 C that exposes the photosensitive drum 9 A to light, a transfer member 9 D that transfers a developer image carried by the photosensitive drum 9 A to the sheet, and a fixing unit 9 E that heats the developing agent to thereby fix the transferred developer image onto the sheet.

In this embodiment, as shown in FIG. 2 , a sheet, e.g., a document sheet is conveyed from a document tray 11 provided on the rear side of the multi-function device 1 toward an output tray 13 provided on the front side of the multi-function device 1 . The automatic document feeder 7 is located upstream of the scanning unit 5 in the sheet conveying direction.

The automatic document feeder 7 separates, one by one, a plurality of document sheets stacked on the document tray 11 and feeds each of the document sheets to the scanning unit 5 . The scanning unit 5 reads information, such as characters, on the document sheet conveyed by the automatic document feeder 7 toward the output tray 13 . The document sheet that has been read is sequentially stacked on the output tray 13 .

The scanning unit 5 includes a platen 5 A, an image sensor 5 B, a document presser 5 C, and a pair of convey rollers 5 D. The platen 5 A is a transparent member that supports the document sheet from below. The image sensor 5 B is, for example, a contact image sensor (CIS) that converts light reflected by the document sheet into an electrical signal. The document presser 5 C presses the conveyed document sheet against the platen 5 A. The pair of convey rollers 5 D is located upstream of the platen 5 A in the sheet conveying direction and is configured to convey the document sheet.

A conveying path Lo for the document sheet is defined by a base member 15 and a holding member 17 , provided on one side of the conveying path Lo and on the other side thereof, respectively. In other words, the base member 15 and the holding member 17 are disposed opposite to each other in a direction perpendicular to the sheet surface, thereby forming the conveying path Lo.

The base member 15 is fixed to the image forming unit 9 via a joint portion 15 A. The holding member 17 is swingably attached to the base member 15 so as to move closer to and away from the base member 15 .

To be more specific, the holding member 17 is configured to swing between a close position shown in FIG. 2 in which the holding member 17 is close to the base member 15 and covering the conveying path Lo and a distant position shown in FIG. 3 in which the holding member 17 is distant from the base member 15 and opening the conveying path Lo.

Here, FIG. 3 illustrates a state where the document tray 11 is accommodated inside the multi-function device 1 and the output tray 13 is removed from the multi-function device 1 . In contrast, FIG. 2 illustrates a state where the document tray 11 extended outwardly from the multi-function device 1 and the output tray 13 is attached to the multi-function device 1 .

The platen 5 A, the image sensor 5 B, and one of the pair of convey rollers 5 D are supported by the base member 15 . The document presser 5 C and the other of the pair of convey rollers 5 D are supported by the holding member 17 . Accordingly, the conveying path Lo is opened by moving the holding member 17 into the distant position, and therefore the document sheet jammed in the conveying path Lo can be easily removed.

As shown in FIG. 2 , a surface of the document tray 11 is inclined with respect to the horizontal direction. Document sheets to be fed to the scanning unit 5 are stacked on the document tray 11 in the top-bottom direction. Accordingly, the sheets placed on the document tray 11 are caused to move to the lower end of the document tray 11 by the gravity exerted on the document sheets.

A separation roller 71 is provided at the lower end of the document tray 11 and on the lower side in the stacking direction of the document sheets. The separation roller 71 rotates in contact with one or more document sheets and applies conveying force to the document sheets. The separation roller 71 is assembled into the base member 15 and driven to rotate by an electric motor, which is not shown in FIG. 2 .

In addition, a separation pad 72 is provided on the upper side in the stacking direction of the document sheets. The separation pad 72 makes contact with one or more documents sheets to apply conveyance resistance thereto. The separation pad 72 makes contact with the document sheets at the position opposite to the separation roller 71 . The separation pad 72 is made of an elastically deformable material, such as silicone rubber or urethane rubber, having a relatively high friction coefficient against a document sheet made of paper or the like.

The separation pad 72 is formed in a strip shape extending from the contact portion with the document sheets to the upstream side in the conveying direction, and the upstream end portion of the separation pad 72 in the conveying direction is fixed to the holding member 17 . The downstream end portion of the separation pad 72 in the conveying direction is moved closer to and away from the separation roller 71 , and is brought into contact with the document sheets while absorbing the variation in thickness of the document sheets.

In addition, a pressing member 73 that is movable relative to the separation roller 71 is disposed on an opposite side of the separation pad 72 from the separation roller 71 . As shown in FIGS. 5A and 5B , the pressing member 73 is pivotably held by the holding member 17 via a shaft 73 A.

As shown in FIGS. 4A and 4B , the pressing member 73 includes a main body 73 B extending from the shaft 73 A to the downstream side in the sheet conveying direction, and a pair of pressing arms 73 C each extending from the shaft 73 A toward a corresponding one of a pair of sheet pressing members 75 . The axial direction of the shaft 73 A and the rotational axis of the separation roller 71 are parallel to each other. Hereinafter, the direction parallel to the rotational axis of the separation roller 71 will also be referred to as a width direction.

The sheet pressing members 75 are provided on respective sides of the separation pad 72 in the width direction as shown in FIG. 6 . Each of the sheet pressing members 75 includes a leaf spring portion 75 A and an extending portion 75 C as shown in FIGS. 4A and 4B . The leaf spring portion 75 A is fixed, on the upstream side thereof in the sheet conveying direction, to the holding member 17 , and extends from the fixed upstream side to the downstream side such that the end in the extending direction reaches the separation roller 71 . The sheet pressing member 75 is an example of a roller pressing member and is configured to, when the holding member 17 is in the close position, contact and press the document sheet conveyed from the document tray 11 against the separation roller 71 or to contact and press the separation roller 71 when no document sheet is placed on the document tray 11 .

A contact portion 75 B for pressing the document sheet against the separation roller 71 is provided at the end of the leaf spring portion 75 A in the extending direction. The extending portion 75 C is formed so as to extend from the contact portion 75 B in the direction intersecting the extending direction of the leaf spring portion 75 A, away from the separation roller 71 . In this embodiment, the sheet pressing members 75 are bent in a substantially L-shape when viewed in the width direction.

The main body 73 B includes a first contact portion 73 D formed on an end portion thereof in the extending direction and configured to contact, a second surface, e.g., a back surface of the separation pad 72 . The first contact portion 73 D is formed at the protruding end of a protrusion protruding from toward the separation pad 72 and formed along the width direction of the main body 73 B. Here, the back surface of the separation pad 72 is opposite from a first surface, e.g., a main surface of the separation pad 72 . The main surface of the separation pad 72 faces the separation roller 71 , and the back surface of the separation pad 72 faces away from the separation roller 71 .

A second contact portion 73 E is formed on an extending end of each pressing arm 73 C and is configured to contact a corresponding one of the leaf spring portions 75 A. In other words, the pressing arm 73 C extends from the shaft 73 A toward the corresponding leaf spring portion 75 A, and the extending end of the pressing arm 73 C serves as the second contact portion 73 E.

Here, the pressing arms 73 C are provided on respective sides of the separation pad 72 in the width direction. The pressing arms 75 are also provided near the shaft 73 A, on respective sides of the main body 73 B in the width direction.

As shown in FIG. 6 , a central portion of the main body 73 B in the width direction, which is provided on the side opposite from the first contact portion 73 D, is in contact with one end of an elastic member 74 , such as a coil spring, in the deforming direction. The elastic member 74 is located between the main body 73 B and the holding member 17 , to thereby press the first contact portion 73 D against the separation pad 72 . The other end of the elastic member 74 in the compressing direction is in contact with the central portion of the holding member 17 in the width direction. The pressing member 73 and the elastic member 74 are an example of a pressing mechanism.

As shown in FIGS. 2 , 3 , 5 A and 5 B, the holding member 17 , which holds the pressing member 73 , the separation pad 72 , and the sheet pressing member 75 , is configured to move relative to the separation roller 71 between the close position and the distant position. The holding member 75 in the close position shown in FIGS. 2 and 5A is closer to the separation roller 71 than the holding member 75 in the distant position shown in FIGS. 3 and 5B is to the holding member 75 .

As shown in FIG. 5A , when the holding member 17 moves from the distant position to the close position, the pressing member 73 moves toward the separation roller 71 such that the separation roller 71 presses the pressing member 73 via the separation pad 72 .

Accordingly, when the holding member 17 moves from the distant position to the close position, i.e., when the holding member 17 rotates clockwise in FIG. 5B , the pressing member 73 rotates counterclockwise about the shaft 73 A, relative to the holding member 17 .

Therefore the pressing arm 73 C also rotates counterclockwise about the shaft 73 A relative to the holding member 17 , and the second contact portion 73 E projects toward the leaf spring portion 75 A so as to press the leaf spring portion 75 A against the separation roller 71 . At the same time, the elastic member 74 is compressed so as to exert a pressing force onto the separation pad 72 .

On the other hand, when the holding member 17 moves from the close position to the distant position, i.e., when the holding member 17 rotates counterclockwise in FIG. 5A , the separation pad 72 moves away from the separation roller 71 and hence the elastic member 74 is decompressed. At the same time, the pressing member 73 rotates clockwise relative to the holding member 17 .

Accordingly, the pressing arm 73 C also rotates clockwise about the shaft 73 A, and therefore the second contact portion 73 E refracts relative to the separation roller 71 in a direction away from the separation roller 71 thereby to reduce the pressing force imposed on the leaf spring portion 75 A. The leaf spring portion 75 A is restored such that at least the contact portion 75 B of the leaf spring portion 75 A retracts from the main surface of the separation pad 72 in a direction away from the separation roller 71 .

In short, in this embodiment, when the holding member 17 is in the distant position and the pressing force imposed on the leaf spring portion 75 A is reduced or eliminated, at least a portion of the sheet pressing member 75 , i.e., the contact portion 75 B of the leaf spring portion 75 A configured to make contact with the document sheet, is refracted from the main surface of the separation pad 72 toward the back surface thereof. In other words, when the holding member 17 moves from the close position to the distant position relative to the separation roller 71 , the sheet pressing member 75 and the separation pad 72 pivot in opposite directions relative to the holding member.

Then when the holding member 17 is in the close position, the second contact portion 73 E presses the leaf spring portion 75 A toward the separation roller 7 such that the sheet pressing member 75 exerts a pressing force onto the document sheet.

In this embodiment, as shown in FIG. 4A , when the holding member 17 is in the close position, the pressing member 73 is formed such that a first imaginary line L 1 and a second imaginary line L 2 is substantially perpendicular to each other.

Here, the first imaginary line L 1 passes through a contact point between the second contact portion 73 E and the sheet pressing member 75 , and through an axial center of the shaft 73 A. The second imaginary line L 2 passes through the contact point between the second contact portion 73 E and the sheet pressing member 75 , and through a point which corresponds to a contact point between the sheet pressing member 75 and the separation roller 71 and lies on a back surface of the sheet pressing member 75 . The back surface of the sheet pressing member 75 faces away from the separation roller 71 .

In addition, as shown in FIG. 6 , the holding member 17 includes a pair of wall-shaped ribs 17 A formed on respective sides of the sheet pressing member 75 in the width direction, so as to project toward the separation roller 71 . As shown in FIG. 5B , when the holding member 17 is in the distant position, the ends 17 B of the ribs 17 A on the side of the separation roller 71 are located closer to the separation roller 71 than the sheet pressing members 75 are to the separation roller 71 .

As shown in FIG. 5A , when the holding member 17 is in the close position, the lower end 17 B of each rib 17 A is substantially parallel to the leaf spring portion 75 A. Accordingly, when the holding member 17 is in the close position, the pair of ribs 17 A serve as a guide to guide the document sheet placed on the document tray 11 to the contact point between the separation roller 71 and the separation pad 72 .

In the above-described embodiment, at least a portion of the sheet pressing member 75 configured to make contact with the document sheet, i.e., the contact portion 75 B of the leaf spring portion 75 A, is retracted from the main surface of the separation pad 72 toward the back surface side thereof when the holding member 17 is in the distant position, thereby to allow cleaning of the separation pad 72 . Such a configuration prevents interference between a cleaning cloth or the like and the sheet pressing member 75 during the cleaning work, thus improving the efficiency of the cleaning work.

In addition, in the above-described embodiment, the first imaginary line L 1 and the second imaginary line L 2 are substantially perpendicular to each other when the holding member 17 is in the close position. Accordingly, the rotational axis of the pressing member 73 intersects with the line of action of the pressing force F of the second contact portion 73 E imposed on the leaf spring portion 75 A, and hence the pressing member 73 is exempted from being subjected to a rotative force, such as a bending moment. This allows the pressing member 73 , i.e., the second contact portion 73 E to efficiently press the sheet pressing member 75 .

The pressing force F generated when the holding member 17 is in the close position, i.e., the force with which the sheet pressing member 75 presses the document sheet, originates from the configuration that the distance between the second contact portion 73 E and the shaft 73 A is larger than the distance between the leaf spring portion 75 A and the shaft 73 A. Accordingly, the force necessary for maintaining the holding member 17 in the close position is the sum of the pressing force F and the elastic force of the compressed elastic member 74 .

In the above-described embodiment, the holding member 17 includes the pair of wall-shaped ribs 17 A formed on both sides of the sheet pressing member 75 in the width direction, so as to project toward the separation roller 71 . The ends of the ribs 17 A on the side of the separation roller 71 are located closer to the separation roller 71 than the sheet pressing members 75 are to the separation roller 71 , at least when the holding member 17 is in the distant position.

Accordingly, when the holding member 17 is in the distant position, the pair of ribs 17 A serve as walls enclosing the sheet pressing members 75 therebetween in the width direction. Such a configuration reliably prevents interference between a cleaning cloth or the like and the sheet pressing members 75 during the cleaning work, thus improving the efficiency of the cleaning work.

In the sheet pressing member 75 according to the first embodiment, the leaf spring portion 75 A and the pressing arm 73 C of the pressing member 73 are substantially perpendicular to each other. Alternatively, in a second embodiment, as shown in FIGS. 7A and 7B , a pressing arm 73 C extends from a shaft 73 A to the upstream side in the sheet conveying direction. Thus, in this embodiment the first imaginary line L 1 and the second imaginary line L 2 are not perpendicular to each other when a pressing member 73 is viewed in the width direction.

In the foregoing embodiments, the sheet pressing member 75 is configured such that the leaf spring portion 75 A is refracted from the main surface of the separation pad 72 toward the back surface thereof when the holding member 17 is in the distant position and the pressing force imposed on the leaf spring portion 75 A is reduced or eliminated. However, different configurations may be adopted.

For example, a stopper that delimits the extent of restoration of the sheet pressing member 75 may be provided, so that at least a portion of the sheet pressing member 75 configured to make contact with the document sheet is set by the stopper at a position retracted from the back surface of the separation pad 72 toward the back side thereof, when the holding member 17 is in the distant position.

Although, in the foregoing embodiments, the sheet conveying device according to an embodiment of the invention is applied to the automatic document feeder 7 , the sheet conveying device may be applied to different devices, such as a sheet feeding device.

Although the sheet pressing member 75 includes the leaf spring portion 75 A and the extending portion 75 C in the forgoing embodiments, different configurations may be adopted. For example, the extending portion 75 C may be excluded.

Although the ribs 17 A are provided on the both sides of the sheet pressing member 75 in the width direction in the foregoing embodiments, the ribs 17 A may be excluded.

In addition, although the second contact portion 73 E is provided at the extending end of the pressing arm 73 C in the foregoing embodiments, different configurations may be adopted. For example, the second contact portion 73 E may be formed on a protruding end of a protrusion formed in the main body 73 B, like the first contact portion 73 D.

In the foregoing embodiments, the pressing member 73 and the elastic member 74 of the pressing mechanism are placed to oppose the separation roller 71 with the separation pad 72 interposed therebetween, and are configured to press the separation pad 72 against the separation roller 71 . However, different configurations may be adopted.

Although the separation pad 72 is fixed to the holding member 17 in the foregoing embodiments, different configurations may be adopted. For example, the separation pad 72 may be fixed to the pressing member 73 swingably attached to the holding member 17 .

While the invention has been described in connection with embodiments of the invention, it will be understood by those skilled in the art that variations and modifications of the embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples are considered merely as exemplary of the invention, with the true scope of the invention being defined by the following claims.