Sheet feed device and image formation device

A sheet feed device has a sheet supply tray in which sheets to be fed are stored, a roller mechanism which ejects each printed sheet on to a sheet holding part, and a cover member which is placed between a sheet supply side on which each sheet is fed before printing and a sheet ejection side on which each sheet is fed after printing. In the sheet feed device, each sheet supplied from the sheet supply tray changes its sheet feed direction approximately 180 degrees before being ejected to the sheet holding part. Part of the cover member on the sheet holding part's side is provided with a first projecting part which lets the ejected sheets be held in the sheet holding part while being bent substantially in an S-shape.

INCORPORATION BY REFERENCE

This application claims priority from Japanese Patent Application No. 2004-248494, filed on Aug. 27, 2004, the entire subject matter of which is incorporated herein by reference thereto.

BACKGROUND OF THE INVENTION

Aspects of the present invention relate to a sheet feed device employed for facsimile machines, copiers, printers, etc. for feeding sheets (e.g., paper, OHP sheets, labels, etc.), and in particular, to a sheet feed device in which each sheet supplied from a sheet supply tray changes its sheet feed direction approximately 180 degrees before being ejected to a sheet holding part.

Sheet feed devices for feeding sheets (e.g., paper, OHP sheets, labels, etc.) are widely employed for facsimile machines, copiers, printers, etc. In sheet feed devices in which each sheet supplied from a sheet supply tray changes its sheet feed direction approximately 180 degrees before being ejected to a sheet holding part, the sheet supply tray and the sheet holding part are generally separated from each other by a sheet feed cover. An example of such a configuration is disclosed in Japanese Patent Provisional Publication No. HEI 10-194552.

However, even in sheet feed devices having such a sheet feed cover for separating the sheet supply tray and the sheet holding part from each other, the separation is not perfect and there is a high probability that an upper part of a sheet set in the sheet supply tray will make contact with an upper part of a sheet held in the sheet holding part.

Therefore, when the sheet set in the sheet supply tray is fed to a position between a printing head and a platen, the upper part of a stack of sheets held in the sheet holding part can be pulled downward together with the sheet in the sheet supply tray (due to friction between the contacting parts of the sheets) and the stack of sheets held in the sheet holding part can curve downward to cover a sheet ejecting part and flop toward an operation panel.

It is possible to resolve the problem by sufficiently enlarging the sheet feed cover and perfectly separating the sheets set in the sheet supply tray from the sheets held in the sheet holding part. However, such an approach causes an increase in the size of the sheet feed device and the facsimile machine, etc.

SUMMARY

Aspects of the present invention, which have been made in consideration of at least one of the above problems, are advantageous in that a sheet feed device capable of preventing the sheets held in the sheet holding part from curving downward and flopping can be provided while realizing downsizing of the device.

DETAILED DESCRIPTION

General Overview

In accordance with an aspect of the present invention, there is provided a sheet feed device comprising a sheet supply tray in which sheets to be fed are stored, a roller mechanism which ejects each sheet after being printed on to a sheet holding part, and a cover member which is placed between a sheet supply side on which each sheet is fed before printing and a sheet ejection side on which each sheet is fed after printing. In the sheet feed device, each sheet supplied from the sheet supply tray changes its sheet feed direction approximately 180 degrees before being ejected to the sheet holding part. Part of the cover member on the sheet holding part's side is provided with a first projecting part which lets the ejected sheets be held in the sheet holding part while being bent substantially in an S-shape.

By the above configuration, the ejected sheets are held in the sheet holding part while being bent substantially in an S-shape. Therefore, even when downward force is applied to the upper part of a stack of sheets held in the sheet holding part, the stack of sheets is not deformed like an arch as in ordinary buckling and only the part already bent in the S-shape is deformed to bend further.

Also in the sheet feed device according to aspects of the present invention, the upper part of the stack of sheets held in the sheet holding part can be pulled downward together with a sheet set in the sheet supply tray (due to friction between contacting parts of the sheets) when the sheet in the sheet supply tray is fed downward. However, since only the part of the stack of sheets (held in the sheet holding part) already bent in the S-shape is deformed to bend further in such cases as mentioned above, the stack of sheets in the sheet holding part is prevented from curving downward like an arch and flopping even when the sheet feed cover is downsized.

Incidentally, in sheet feed devices in which each sheet supplied from the sheet supply tray changes its sheet feed direction approximately 180 degrees before being ejected to the sheet holding part, after being printed on each sheet tends to curl when, the sheet is ejected from the ejecting part of the roller mechanism. In such sheet feed devices, the curl in the sheet is removed generally by causing a reverse curl in the sheet by letting the sheet (being ejected from the ejecting part) collides with the cover member.

In order to remove the curl sufficiently, it is desirable to sufficiently enlarge the cover member so that a reverse curl can be continuously caused in the sheet during a period between the collision of the front end of the sheet with the cover member and the completion of the sheet ejection.

Therefore, downsizing the cover member generally makes it difficult to remove the curl in the sheet sufficiently (since it becomes impossible to continuously cause the reverse curl in the sheet during the period between the collision of the front end of the sheet with the cover member and the completion of the sheet ejection).

However, in the present invention, a sufficient reverse curl can be caused in the sheet (differently from cases where no first projecting part is provided) since the reverse curl is caused in the sheet not only by the cover member but also by the first projecting part. Therefore, it becomes possible to remove the curl in the sheet securely while downsizing the cover member.

As above, by the sheet feed device in accordance with aspects of the present invention, the curl in each sheet ejected from the roller mechanism can be eliminated and the sheets held in the sheet holding part can be prevented from curving downward like an arch and flopping, while realizing the downsizing of the sheet feed device.

Further, the whole sheet feed device including the cover member can be designed with high flexibility since the first projecting part is provided to part of the cover member.

By providing the first projecting part to part of the cover member as above, larger internal space of the sheet holding part can be secured compared to other cases (e.g. where the whole cover member is raised for implementing an equivalent of the first projecting part). Therefore, even when a sheet gets jammed in the sheet holding part, the user can easily remove the jammed sheet by reaching a hand into the sheet holding part, by which high maintainability is realized.

By the way, when a sheet set in the sheet supply tray is fed, the stack of already-ejected sheets held in the sheet holding part can be dragged downward by the fed sheet and thereby bend like an arch making contact with an opposing surface facing the first projecting part as mentioned above.

Meanwhile, a sheet being ejected from the roller mechanism has to pass between the stack of already-ejected sheets held in the sheet holding part and the opposing surface facing the first projecting part. However, when the stack of already-ejected sheets bending like an arch is pressing against the opposing surface as above, a strong frictional drag hampers the sheet from being ejected between the stack of arched sheets and the opposing surface, by which the sheet can get stuck in the sheet holding part (paper jam).

To avoid the problem, in an illustrative embodiment, part of an opposing part opposite to (facing) the first projecting part is provided with a second projecting part projecting toward the cover member, and an apex of the second projecting part is placed above the ejecting part (defined as a point of contact of the sheet with the roller mechanism that is the most downstream in the sheet feed direction) and below an apex of the first projecting part.

By the above configuration, even when the stack of already-ejected sheets held in the sheet holding part bends as above, the stack bends without contacting the whole opposing part but contacting the apex of the second projecting part. Therefore, the sheet being ejected from the roller mechanism is ejected through a gap formed between the stack of already-ejected sheets held in the sheet holding part and the opposing part having the second projecting part.

Since the second projecting part is provided to part of the opposing part, the frictional drag during the ejection of each sheet to the sheet holding part gets smaller compared to the case where the stack of arched sheets presses against the whole opposing part, by which each sheet can be ejected to the sheet holding part smoothly.

The second projecting part may be placed at a position shifted from the roller mechanism substantially in an axial direction of the roller mechanism when seen from the apex of the first projecting part in the sheet feed direction.

By the above configuration, the roller mechanism has no obstacle (applying a frictional drag or feeding resistance to the sheet being ejected) in the direction of the feeding force applied to the sheet (i.e. on a line directly extending from the roller mechanism in the sheet feed direction). Therefore, the feeding force of the roller mechanism is utilized efficiently and the sheet can be ejected securely.

The second projecting parts may be placed on both sides of the roller mechanism in the axial direction of the roller mechanism when seen from the apex of the first projecting part in the sheet feed direction.

By the above configuration, a rotation moment occurring at a contacting part of one second projecting part on one side of the roller mechanism due to feeding resistance can be canceled by a rotation moment occurring at a contacting part of another second projecting part on the other side of the roller mechanism due to feeding resistance. Therefore, the sheet being ejected from the roller mechanism is prevented from being ejected obliquely (deviating from the line directly extending from the roller mechanism in the sheet feed direction).

The second projecting part may be placed on a downstream side of the roller mechanism in the sheet feed direction and on an upstream side of the first projecting part in the sheet feed direction.

Incidentally, if the stack of sheets held in the sheet holding part bends, the surface of the stack of sheets facing the ejecting part might become substantially orthogonal to the direction of sheet ejection from the ejecting part. In such cases, the sheet being ejected from the ejecting part is likely to head for a base part of the sheet holding part and result in a paper jam.

To avoid the problem, in an illustrative embodiment, the base part of the sheet holding part is placed below the ejecting part, and the basal part of the sheet holding part is provided with a holding position adjusting member which adjusts the position of the stack of sheets held in the sheet holding part so that each sheet ejected from the ejecting part and colliding with the stack of sheets will head upward.

By the above configuration, the sheet ejected from the ejecting part and colliding against the surface of the stack of sheets (held in the sheet holding part) facing the ejecting part can securely be guided upward inside the sheet holding part, by which the sheet ejected from the ejecting part is securely prevented from heading for the base part of the sheet holding part and resulting in a paper jam.

In the above configuration, the holding position adjusting member may adjust the position of the stack of sheets held in the sheet holding part so that each sheet ejected from the ejecting part and colliding against the stack of sheets will head upward, by adjusting the position of the bottom of the stack of sheets held on the base part of the sheet holding part toward the ejecting part.

The holding position adjusting member may be implemented by a third projecting part protruding from part of the base part of the sheet holding part.

By the above configuration, the holding position adjusting member can be provided to the base part of the sheet holding part with ease, while increasing the flexibility of design of the whole device.

Further, since the holding position adjusting member is implemented by the third projecting part protruding from part of the base part of the sheet holding part, larger internal space of the sheet holding part can be secured compared to other cases (e.g. where the holding position adjusting member is formed by raising the whole base part of the sheet holding part). Therefore, a paper jam in the sheet holding part can be prevented without requiring excessive maintenance, allowing the user to easily remove a jammed sheet by reaching a hand into the sheet holding part even in case of a paper jam.

According to some aspects of the invention, the roller mechanism may include an ejection roller which is placed to make contact with the sheet and thereby apply feeding force to the sheet and a pinch guide member which is placed to oppose the ejection roller via the sheet. A circumferential exterior surface of the ejection roller for making contact with the sheet is provided with projecting parts (surrounding the whole circumference of the ejection roller) at both ends of the ejection roller in its axial direction.

By the above configuration, the sheet ejected from the roller mechanism is curved in a “V” or “U” like shape when seen in the sheet feed direction, by which stiffness of the sheet against force (terrestrial gravitation) bending the sheet around the axial direction of the roller mechanism is increased. By increasing the stiffness, the sheet being ejected from the roller mechanism is prevented from bending downward, by which the sheet is securely guided and fed upward in the sheet holding part and the paper jam can be prevented from occurring.

The pinch guide member may be implemented, for example, by a sheet ejection pinch roller which is placed to press against the ejection roller.

In accordance with another aspect of the present invention, there is provided a sheet feed device including a sheet supply tray in which sheets to be fed are stored, a roller mechanism which ejects each sheet after being printed on to a sheet holding part, and a cover member which is placed between a sheet supply side on which each sheet is fed before printing and a sheet ejection side on which each sheet is fed after printing. In the sheet feed device, each sheet supplied from the sheet supply tray changes its sheet feed direction approximately 180 degrees before being ejected to the sheet holding part. A face of the cover member on the sheet holding part's side is provided with a first projecting part which lets the ejected sheets be held in the sheet holding part while being bent substantially in an S-shape. Part of an opposing part opposite to (facing) the first projecting part is provided with a second projecting part projecting toward the cover member. An apex of the second projecting part is placed above an ejecting part, defined as a point of contact of the sheet with the roller mechanism that is the most downstream in the sheet feed direction, and below an apex of the first projecting part.

By the above configuration, the curl in each sheet ejected from the roller mechanism can be eliminated, the sheets held in the sheet holding part can be prevented from curving downward like an arch and flopping, and each sheet can be ejected to the sheet holding part smoothly, while realizing the downsizing of the sheet feed device.

Incidentally, while the first projecting part in the above configuration may be provided only to part of the face of the cover member on the sheet holding part's side (e.g. by letting part of the face protrude therefrom), the first projecting part may also be formed as a projecting surface by letting substantially all the face (of the cover member on the sheet holding part's side) project, for example.

In accordance with another aspect of the present invention, there is provided a sheet feed device including a sheet supply tray in which sheets to be fed are stored, a roller mechanism which ejects each sheet after a prescribed process to a sheet holding part, and a cover member which is placed between a sheet supply side on which each sheet is fed before the prescribed process and a sheet ejection side on which each sheet is fed after the prescribed process. In the sheet feed device, each sheet supplied from the sheet supply tray changes its sheet feed direction approximately 180 degrees before being ejected to the sheet holding part. Part of the cover member on the sheet holding part's side is provided with a first projecting part which lets the ejected sheets be held in the sheet holding part while being bent substantially in an S-shape.

In accordance with another aspect of the present invention, there is provided an image formation device including a sheet feed device including a sheet supply tray in which sheets to be fed are stored, a roller mechanism which ejects each sheet after image formation to a sheet holding part, and a cover member which is placed between a sheet supply side on which each sheet is fed before image formation and a sheet ejection side on which each sheet is fed after image formation. In the image formation device, each sheet supplied from the sheet supply tray changes its sheet feed direction approximately 180 degrees before being ejected to the sheet holding part. Part of the cover member on the sheet holding part's side is provided with a first projecting part which lets the ejected sheets be held in the sheet holding part while being bent substantially in an S-shape.

In the image formation device, part of an opposing part opposite to (facing) the first projecting part may be provided with a second projecting part projecting toward the cover member, and an apex of the second projecting part is placed above the ejecting part (defined as a point of contact of the sheet with the roller mechanism that is the most downstream in the sheet feed direction) and below an apex of the first projecting part.

The base part of the sheet holding part may be placed below the ejecting part, and the base part of the sheet holding part is provided with a holding position adjusting member which adjusts the position of the stack of sheets held in the sheet holding part so that each sheet ejected from the ejecting part and colliding against the stack of sheets will head upward.

In an illustrative embodiment, the image formation device is implemented as a facsimile machine, and a document tray for holding a document to be transmitted is provided to a face of the opposing part opposite to (facing) the second projecting part.

By the above configuration, a facsimile machine of beautiful design can be realized while reducing its size.

ILLUSTRATIVE EMBODIMENTS

Referring now to the drawings, a description will be given in detail of illustrative embodiments in accordance with the present invention.

FIG. 1is a top view of a facsimile machine1employing a sheet feed device in accordance with an illustrative embodiment of the present invention.FIG. 2is a perspective view seeing the facsimile machine1from the rear and above.FIG. 3is a sectional side view showing the overall composition of the facsimile machine1.FIG. 4is a sectional side view showing the detailed composition of the facsimile machine1.FIGS. 5A and 5Bare enlarged views showing a roller mechanism of the facsimile machine1which will be described later.

First, the overall composition of the facsimile machine1will be explained below. Referring toFIG. 4, the facsimile machine1of this illustrative embodiment has an upper cover2and a lower cover4. InFIG. 4, the front of the facsimile machine1is shown on the right-hand side and the rear is shown on the left-hand side. A sheet supply tray6is provided to an upper-rear part of the upper cover2, and a stack of sheets3as print media are set and stored in the sheet supply tray6.

Each sheet3is fed along a sheet feed path17(indicated by a chain line arrow inFIG. 4) by rollers, etc. which will be explained later. The sheets3are not restricted to paper but can be various print media such as OHP sheets.

The upper cover2and the lower cover4are linked with a cover rotation shaft8(at the rear ends of the covers2and4) to be rotatable around the cover rotation shaft8. When a user of the facsimile machine1opens the upper cover2by operating a lever (not shown), the upper cover2rotates counterclockwise inFIG. 4around the cover rotation shaft8.

When the upper cover2is opened as above, various components mounted on the upper part of the facsimile machine1(the sheet supply tray6, a sheet feed roller5, a platen7, a sheet ejection roller15, an ADF (Automatic Document Feeder) roller21, an LF (Line Feed) roller23, a keyboard (operation panel)22, etc.) also rotate around the cover rotation shaft8together with the upper cover2.

The sheet feed roller5, driven and rotated by a drive motor (not shown) and gears (not shown), feeds the sheets3set in the sheet supply tray6one by one along the sheet feed path17in cooperation with a regulating member10.

On the downstream side of the sheet feed roller5in the sheet feed path17, the platen7is placed. The platen7is also driven and rotated by the drive motor (not shown) and gears.

Under the platen7, a printing head9, for forming an image on the sheet3by transferring ink from a ribbon11to the sheet3, is placed to face the platen7. In this illustrative embodiment, a so-called line thermal head (including heating elements arranged in a line) is employed as the printing head9, by which the entire printable range of the sheet3is covered by the printing head9.

Incidentally, the printing head9is mounted and fixed on the lower part of the facsimile machine1(inside the lower cover4) together with a ribbon supply part4a, a ribbon roll-up part4b, a CIS (Contact Image Sensor)25, a document ejection pinch roller24, a ribbon sensor31, etc. which will be explained later. Therefore, when the upper cover2is opened, the printing head9stands still while the platen7separates from the printing head9.

On the downstream side of the platen7in the sheet feed path17, the sheet ejection roller15is provided. The sheet ejection roller15makes contact with the sheet3(after the printing of an image thereon) so as to apply feeding force thereto, by which the sheet3is ejected from the facsimile machine1to be held in a sheet holding part62. A sheet ejection pinch roller16is placed over the sheet ejection roller15to press against the sheet ejection roller15so that the sheet3passing between the sheet ejection roller15and the sheet ejection pinch roller16will be sandwiched between the rollers15and16.

As shown inFIG. 5A, the circumferential exterior surface of the sheet ejection roller15for making contact with the sheet3is provided with two projecting parts (flanges)15a(surrounding the whole circumference of the roller15) at both ends of the roller15in its axial direction. The sheet ejection pinch roller16, pressing against part of the circumferential exterior surface of the sheet ejection roller15between the two projecting parts15a, cooperates with the sheet ejection roller15to eject the sheet3to the sheet holding part62.

In this illustrative embodiment, the sheet ejection roller15and the sheet ejection pinch roller16will be collectively referred to as a “roller mechanism15,16”.

The sheet ejection roller15is also driven and rotated by the drive motor (not shown) and gears.

Between the sheets3set in the sheet supply tray6and the sheets (3a) held in the sheet holding part62, a sheet feed cover61is provided to prevent the sheets (3,3a) in the two parts6and62from making contact with each other across a wide area.

In this illustrative embodiment, a part of the upper cover2(surrounded by a chain line inFIG. 4) covering the top of the sheet feed roller5forms a cover member which is placed between a sheet supply side (on which each sheet3is fed before printing) and a sheet ejection side (on which each sheet3is fed after printing).

On the sheet holding part62side of the cover member (the part of the upper cover2covering the top of the sheet feed roller5), first (two in this illustrative embodiment) projecting parts (first ribs)2aare formed in order to let the sheets3abe held in the sheet holding part62in a bent shape (substantially in an S-shape). In this illustrative embodiment, the first projecting parts2aare formed integrally with the upper cover2(made of resin such as polystyrene) by injection molding.

In this illustrative embodiment, each first projecting part2ais formed substantially in a triangular shape (when seen in an axial direction of the sheet feed roller5orthogonal toFIG. 4) to have a round apex P1. As shown inFIG. 1, the first projecting parts2aare formed on the downstream side of the sheet ejection roller15in the sheet feed direction, at separate positions in the axial direction of the sheet ejection roller15or the sheet ejection pinch roller16.

When seen in the direction of an arrow A inFIG. 4(i.e. when seen in the sheet feed direction from the downstream side), the first projecting parts2aare formed at positions shifted from the sheet ejection roller15in the axial direction of the sheet ejection roller15or the sheet ejection pinch roller16(substantially orthogonal to the sheet feed direction).

As shown inFIG. 4, an opposing part26afacing (opposite to) the first projecting parts2ais provided with second projecting parts (second ribs)2bprojecting toward the upper cover2. The second projecting parts2bare formed letting their apexes P2be placed above an ejecting part P3of the roller mechanism15,16and below the apexes P1of the first projecting parts2a, while letting the apexes P2be situated on the downstream side of the ejecting part P3and on the upstream side of the apexes P1in the sheet feed direction.

When seen in the direction of the arrow A inFIG. 4(i.e. when seen in the sheet feed direction from the downstream side), the second projecting parts2bare formed at positions shifted from the roller mechanism15,16in the axial direction of the roller mechanism15,16(orthogonal toFIG. 4) to be situated on both sides of the roller mechanism15,16in the axial direction as shown inFIG. 1.

The apexes P1of the first projecting parts2amean portions of the first projecting parts2amaking contact with a stack of sheets3aheld in the sheet holding part62. The apexes P2of the second projecting parts2bmean portions of the second projecting parts2bmaking contact with the stack of sheets3aheld in the sheet holding part62. The ejecting part P3of the roller mechanism15,16means a point of contact of the roller mechanism15,16with the sheet3that is the most downstream in the sheet feed direction.

While the point of contact of the sheet ejection roller15with the sheet3is identical with the point of contact of the sheet ejection pinch roller16with the sheet3in the roller mechanism15,16of this illustrative embodiment except that the contacting points are on different sides of the sheet3, in cases where the sheet ejection roller15and the sheet ejection pinch roller16are shifted from each other in the sheet feed direction, the ejecting part P3of the roller mechanism15,16is defined as the point of contact of the sheet3with one of the rollers15and16that is on the downstream side in the sheet feed direction (the sheet ejection pinch roller16, for example).

Further, a base part62aof the sheet holding part62(surrounded by a two-dot chain line inFIG. 4), situated on the downstream side of the ejecting part P3, is provided with third projecting parts (third ribs)2cprotruding from the base part62a. By the third projecting parts2c, the position of the stack of sheets3aheld in the sheet holding part62is adjusted so that the sheet3ejected from the ejecting part P3and colliding with the stack of sheets3a(held in the sheet holding part62) will head in an upward direction. In this illustrative embodiment in which the direction of sheet ejection from the ejecting part P3is horizontal as shown inFIG. 4, the position of the stack of sheets3aheld in the sheet holding part62is adjusted by the third projecting parts2cso that a normal line B (seeFIG. 4) to the surface3bof a part of the stack of sheets3afacing the ejecting part P3will point in a direction more upward than the horizontal direction.

Specifically, by letting part of the base part62aof the sheet holding part62project toward the ejecting part P3as above, the position of the bottom of the stack of sheets3a(held on the base part62aof the sheet holding part62) is adjusted toward the ejecting part P3.

The other side of the opposing part26ais provided with a document tray26. When a document to be transmitted by the facsimile machine1is set in the document tray26, the document is fed along a document feed path29by the ADF roller21and the LF roller23.

Specifically, the document set in the document tray26is first fed by the ADF roller21. Over the ADF roller21, a separating member27is placed. The separating member27prevents multiple documents from being fed by the ADF roller21, by successively letting a lowermost one (fed by the ADF roller21) of a stack of sheets of the document separate from the rest of the document. Therefore, the document set in the document tray26is fed sheet by sheet along the document feed path29by the ADF roller21in cooperation with the separating member27.

On the downstream side of the ADF roller21in the document feed path29, the CIS25is placed. Over the CIS25, a document holder28is provided so as to press against the top face of the CIS25. The CIS25successively reads an image on each sheet of the document while the sheet fed along the document feed path29passes between the CIS25and the document holder28.

On the downstream side of the CIS25, the LF roller23and the document ejection pinch roller24(under the LF roller23) are rotatably placed to press against each other. The LF roller23and the document ejection pinch roller24eject the document (after the image reading by the CIS25) from the facsimile machine1.

The aforementioned keyboard22, having numeric keys and various function keys, is provided on a top panel20of the facsimile machine1. The user can instruct the facsimile machine1to perform various operations by pressing the keys on the keyboard22. The top panel20is also provided with a display unit20a(seeFIG. 1) for displaying the operating status of the facsimile machine1to the user.

On the lower cover4, the ribbon supply part4ais formed below the sheet feed roller5while the ribbon roll-up part4bis formed below the ADF roller21. The ribbon supply part4astores the ribbon11which has been rolled up around a ribbon supply spool12.

The ribbon11is pulled out from the ribbon supply part4a, passes between the printing head9and the platen7, and is rolled up by a ribbon roll-up spool13of the ribbon roll-up part4b.

Incidentally, both the ribbon supply spool12and the ribbon roll-up spool13in this illustrative embodiment are attached to a cassette frame (not shown) to form one ribbon cassette, and the ribbon cassette is configured to be attachable and detachable to/from the lower cover4.

However, such a configuration as a ribbon cassette is only an example, and thus the ribbon supply spool12and the ribbon roll-up spool13may also be configured to be independently attached and detached to/from the lower cover4.

The ribbon11is made wide enough to cover a printable range of the heating elements of the printing head9configured as a line thermal head. The ribbon roll-up spool13, driven and rotated by the drive motor (not shown) and gears, rolls up the ribbon11which has been used for the image formation on the sheet3.

In the following, the operation of the facsimile machine1for feeding the sheet3and the characteristics of the facsimile machine1of this illustrative embodiment will be described in detail.

Each sheet3set in the sheet supply tray6is fed by the sheet feed roller5to the position between the printing head9and the platen7, at which an image is printed on the sheet3(being fed by the platen7) by the printing head9by transferring the ink on the ribbon11into the sheet3.

Meanwhile, the ribbon supply spool12and the ribbon roll-up spool13are driven and rotated in sync with the rotation of the platen7, by which the ribbon11which has been rolled up around the ribbon supply spool12is pulled out and rolled up by the ribbon roll-up spool13.

The sheet3, on which the image has been printed by the printing head9as above, is guided by feed guide walls4cand4d(seeFIG. 4) to change its feed direction by approximately 180 degrees. Thereafter, the sheet3is fed by the sheet ejection roller15to be ejected toward the upper left ofFIG. 4, letting its front end make contact with the upper cover2and the first projecting parts2a.

In this operation, also in the facsimile machine1(sheet feed device) of this illustrative embodiment, an upper part of the stack of sheets3aheld in the sheet holding part62can be pulled downward together with a sheet3set in the sheet supply tray6(due to friction between contacting parts of the sheets3and3a) when the sheet3is fed by the sheet feed roller5to the position between the printing head9and the platen7. However, since the stack of sheets3ain the sheet holding part62is held in the bent shape (S-shape) in this illustrative embodiment, only the part bent in the S-shape is deformed to bend further.

Therefore, the sheets3ain the sheet holding part62are prevented from curving downward like an arch and flopping to cover the ejecting part P3even when the sheet feed cover61is downsized, such that downsizing of the facsimile machine1can be realized.

Incidentally, if the size of the upper cover2is reduced without providing the first projecting parts2ato the upper cover2, removal of a curl in the sheet can become insufficient since it is impossible as shown inFIG. 6to continuously cause a reverse curl in the sheet during a period between the collision of the front end of the sheet against the upper cover2and the completion of the sheet ejection.

On the other hand, in this illustrative embodiment, a sufficient reverse curl can be caused with the sheet3abeing ejected to the sheet holding part62(differently from cases where no first projecting part2ais provided) since the reverse curl is caused in the sheet3anot only by the upper cover2but also by the first projecting parts2aas shown inFIG. 3. Therefore, it becomes possible to remove the curl in the sheet3asecurely while downsizing the upper cover2.

As described above, by the facsimile machine1in accordance with the illustrative embodiment of the present invention, the curl in each sheet ejected from the roller mechanism15,16can be eliminated and the sheets3aheld in the sheet holding part62can be prevented from curving downward like an arch and flopping, while realizing the downsizing of the sheet feed device and the facsimile machine1.

The first projecting parts2ain the above illustrative embodiment are formed by letting parts of the upper cover2protrude therefrom; therefore, the entire facsimile machine1including the upper cover2can be designed with high flexibility.

Further, since the first projecting parts2aare formed by letting parts of the upper cover2protrude as above, larger internal space of the sheet holding part62can be secured compared to other cases (e.g. where the whole upper cover2is raised for implementing an equivalent of the first projecting parts2a). Therefore, even when a sheet gets jammed in the sheet holding part62, the user can easily remove the jammed sheet by reaching a hand into the sheet holding part62, by which high maintainability is realized.

Incidentally, when a sheet3set in the sheet supply tray6is fed by the sheet feed roller5, the stack of already-ejected sheets3aheld in the sheet holding part62can be dragged downward by the sheet3and thereby bend like an arch making contact with an opposing surface facing the first projecting parts2aas shown inFIG. 7.

Meanwhile, a sheet3being ejected from the roller mechanism15,16has to pass between the stack of already-ejected sheets3aheld in the sheet holding part62and the opposing surface facing the first projecting parts2a. However, when the stack of already-ejected sheets3abending like an arch is pressing against the opposing surface as above, a strong frictional drag hampers the sheet3(a thick chain line inFIG. 7) from being ejected between the stack of arched sheets3aand the opposing surface, by which the sheet3can get stuck in the sheet holding part62(paper jam).

On the other hand, in the above illustrative embodiment, the opposing part26afacing the first projecting parts2ais provided with the second projecting parts2bprojecting toward the upper cover2as shown inFIGS. 3 and 4. Therefore, even when the stack of already-ejected sheets3aheld in the sheet holding part62bends, the stack bends without contacting the whole opposing part26abut contacting the apexes P2of the second projecting parts2b.

Therefore, the sheet3being ejected from the roller mechanism15,16is ejected through a gap formed between the stack of already-ejected sheets3aheld in the sheet holding part62and the opposing part26ahaving the second projecting parts2b. Since the second projecting parts2bare formed to protrude from limited area of the opposing part26a, the frictional drag during the ejection of the sheet3gets smaller compared to the case where the stack of arched sheets3apresses against the whole opposing part26a, by which the sheet3can be ejected smoothly.

Further, since the second projecting parts2bare placed at positions shifted from the roller mechanism15,16substantially in the axial direction of the roller mechanism15,16when seen in the sheet feed direction from the downstream side of the apexes P1of the first projecting parts2a, the roller mechanism15,16has no obstacle (applying a frictional drag or feeding resistance to the sheet3being ejected) in the direction of the feeding force applied to the sheet3(i.e. on a line directly extending from the roller mechanism15,16in the sheet feed direction). Therefore, the feeding force of the roller mechanism15,16can be utilized efficiently and the sheet3can be ejected securely.

Furthermore, since the second projecting parts2bare placed on both sides of the roller mechanism15,16(in its axial direction) when seen in the sheet feed direction from the downstream side of the apexes P1of the first projecting parts2a, a rotation moment occurring at a contacting part of one second projecting part2bon one side of the roller mechanism15,16due to feeding resistance can be canceled by a rotation moment occurring at a contacting part of the other second projecting part2bon the other side of the roller mechanism15,16due to feeding resistance. Therefore, the sheet3being ejected from the roller mechanism15,16is prevented from being ejected obliquely (deviating from the line directly extending from the roller mechanism15,16in the sheet feed direction).

In addition, by providing the document tray26to the other side of the opposing part26a(opposite to the second projecting parts2b), a facsimile machine1of beautiful design can be realized while reducing its size.

Incidentally, if the surface3bof the stack of sheets3a(held in the sheet holding part62) facing the ejecting part P3becomes substantially orthogonal to the direction of sheet ejection from the ejecting part P3as shown inFIG. 8due to the bending of the stack of sheets3a, the sheet3being ejected from the ejecting part P3is likely to head for the base part62aof the sheet holding part62(downward inFIG. 8) and result in a paper jam.

On the other hand, in the above illustrative embodiment, the base part62aof the sheet holding part62is provided with the third projecting parts2cwhich adjusts the position of the stack of sheets3aheld in the sheet holding part62so that the sheet3ejected from the ejecting part P3and colliding with the stack of sheets3awill head in an upward direction (e.g. so that the normal line B to the surface3bof the stack of sheets3afacing the ejecting part P3will point in a direction more upward than the horizontal direction in the case where the direction of sheet ejection from the ejecting part P3is horizontal) as shown inFIG. 4. Therefore, the sheet3ejected from the ejecting part P3and colliding with the surface3bfacing the ejecting part P3can securely be guided upward inside the sheet holding part62, by which the sheet3can be securely prevented from heading for the base part62aof the sheet holding part62and resulting in a paper jam.

In the above illustrative embodiment, the position of the stack of sheets3aheld in the sheet holding part62is adjusted (so as to prevent the paper jam) by the third projecting parts2cformed to protrude from limited parts of the sheet holding part62, by which larger internal space of the sheet holding part62can be secured compared to other cases (e.g. where the whole base part62aof the sheet holding part62is raised for realizing the adjustment of the position of the stack of sheets3a). Therefore, the paper jam in the sheet holding part62can be prevented without requiring excessive maintenance, allowing the user to easily remove a jammed sheet by reaching a hand into the sheet holding part62even in case of a paper jam.

The sheet3being ejected from the roller mechanism15,16has a tendency to bend downward due to terrestrial gravitation, and the tendency is enhanced as the sheet3gets thinner or softer. The downward bending of the sheet3ejected from the roller mechanism15,16causes the sheet feeding to the base part62aof the sheet holding part62and results in a paper jam.

On the other hand, in the above illustrative embodiment, since the circumferential exterior surface of the sheet ejection roller15for making contact with the sheet3is provided with the two projecting parts15a(surrounding the whole circumference of the roller15) at both ends of the roller15in its axial direction, the sheet3ejected from the roller mechanism15,16is curved in a shape like “V” or “U” when seen in the sheet feed direction as shown inFIGS. 9A and 9B, by which stiffness of the sheet3against the force (terrestrial gravitation) bending the sheet around the axial direction of the roller mechanism15,16is increased.

By the increase of the stiffness, the sheet3being ejected from the roller mechanism15,16is prevented from bending downward, by which the sheet3is securely guided and fed upward in the sheet holding part62and the paper jam can be prevented from occurring.

While a description has been given above of an illustrative embodiment in accordance with the present invention, the present invention is not to be restricted by the particular illustrative embodiment and a variety of modifications, design changes, etc. are possible without departing from the scope and spirit of the present invention described in the appended claims.

For example, while the first projecting parts2ain the above illustrative embodiment are implemented by ribs protruding from limited areas of the aforementioned cover member (the part of the upper cover2covering the top of the sheet feed roller5), it is also possible, for example, to form one first projecting part2a(as a projecting surface) by letting substantially the whole surface of the cover member on the sheet holding part62side project into the sheet holding part62.

While the third projecting parts2cin the above illustrative embodiment are implemented by ribs protruding from limited areas of the base part62aof the sheet holding part62, it is also possible, for example, to form one third projecting part2c(as a projecting surface) by letting substantially the whole surface of the base part62aproject into the sheet holding part62.

While the first projecting parts2a, the second projecting parts2band the third projecting parts2cin the above illustrative embodiment are implemented by ribs formed integrally with the upper cover2, etc., it is also possible, for example, to manufacture the projecting parts2a,2band2cseparately from the upper cover2, etc. and thereafter fix the projecting parts2a,2band2con the upper cover2, etc. with adhesives, screws, etc.

While the second projecting parts2bin the above illustrative embodiment are placed on both sides of the roller mechanism15,16(in its axial direction) when seen in the sheet feed direction from the downstream side of the apexes P1of the first projecting parts2a, the arrangement of second projecting parts2bis not restricted to that in the above illustrative embodiment, as long as one or more second projecting parts2bare placed at positions shifted from the roller mechanism15,16in the axial direction of the roller mechanism15,16when seen in the sheet feed direction from the downstream side of the apexes P1of the first projecting parts2a.

While only one sheet ejection roller15is employed in the above illustrative embodiment, two more sheet ejection rollers15may be employed in the facsimile machine1or the sheet feed device.

While the sheet ejection pinch roller16substantially in a cylindrical shape is employed as a member pressing against the sheet ejection roller15for pinching and guiding the sheet3, the sheet ejection pinch roller16may be replaced with wall-like ribs for regulating the feed direction of the sheet3.

While the sheet feed device in accordance with the present invention is applied to a facsimile machine in the above illustrative embodiment, the present invention is applicable not only to facsimile machines but also various types of image formation devices (printers, copiers, etc.) and various other devices executing a prescribed process by feeding sheets.