Patent Grant
8442421
This application is based upon and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-153170, filed Jun. 29, 2009.
This invention relates to a conveying path switching structure and an image forming apparatus using the conveying path switching structure.
According to an aspect of the invention, a conveying path switching structure includes a cover unit and a conveying path switch unit. The cover unit is attached to an image forming apparatus main body so as to be movable between a close state and an open state in which a fixing unit is exposed. The conveying path switch unit is rotatably attached to the cover unit and that switches a conveying path of a record medium between a discharge conveying path and a double-side conveying path in the close state. The discharge conveying path is a path where the record medium is conveyed from a discharge part of the fixing unit to a discharge unit that discharges the record medium to outside of the image forming apparatus main body in a close state. The double-side conveying path is a path where the record medium is conveyed again to an image forming unit of the image forming apparatus main body from the discharge unit in a state where the record medium are inverted.
Exemplary embodiments of the invention will be described in detail based on the following figures, wherein:
An exemplary embodiment of the invention will be discussed below with reference to the accompanying drawings.
Exemplary Embodiment 1
In
The record sheet 7 is fed from a sheet feed tray 8 as sheet feed means placed on a bottom of the image forming apparatus main body 1 in a state in which the sheets are separated one sheet at a time by a sheet feed roll 9 and a separation roll 10. The record sheet arrives at a registration roll 11 and is conveyed to a transfer position where the photoconductive drum 2 and the transfer roll 6 abut each other in a synchronized state with the toner image on the photoconductive drum 2 by the registration roll 11.
The record sheet 7 to which the toner image has been transferred from the photoconductive drum 2 as described above is conveyed to a fixing unit 12 as fixing means by a conveying force of the photoconductive drum 2 and the transfer roll 6 and is heated and pressed by a heating roller 13 and a pressing roller 14 of the fixing unit 12, and an unfixed toner image is fixed on the record sheet 7. The record sheet 7 with the toner image fixed thereon is conveyed to a discharge conveying path 16 through a switch gate 15 as a conveying path switch unit and is discharged onto a folding discharge tray 18 provided in an upper part of the image forming apparatus main body 1 by a discharge roll 17 as discharge unit provided in the discharge conveying path 16.
A discharge part of the fixing unit 12 is provided with the discharge conveying path 16 for conveying the record sheet from the discharge part of the fixing unit 12 to the discharge roll 17 and is also provided with the switch gate 15 for rotation on a support shaft 43. The position of center of gravity of the switch gate 15 is set so that the switch gate 15 stops at a first position closing the discharge conveying path 16 under the tare weight (rotation moment) of the switch gate 15 as shown in
The discharge roll 17 is configured so that the rotation direction can be switched between a forward direction for discharging the record sheet 7 onto the discharge tray 18 and an inversion direction for conveying the record sheet 7 in the opposite direction to the discharge direction.
Further, a double-side conveying path 19 is provided above the switch gate 15. The double-side conveying path 19 is placed in an open state by the switch gate 15 restored to the first position after the trailing end of the record sheet 7 conveyed from the discharge part of the fixing unit 12 to the discharge roll 17 and discharged onto the discharge tray 18 by the discharge roll 17 passes through the switch gate 15. The double-side conveying path 19 again conveys the record sheet 7 to the image forming unit at the double-side image forming time. The double-side conveying path 19 is formed so as to communicate with a double-side conveying path 20 extending downward along a side face of the image forming apparatus main body 1 after passing through above the switch gate 15. A conveying roll 21 for conveying the record sheet 7 to the registration roll 11 is provided in the double-side conveying path 20 extending downward.
At the double-side image forming time of forming an image on both one face and reverse face of the record sheet 7, as shown in
Then, the rotation direction of the discharge roll 17 is switched so that the conveying direction of the record sheet 7 becomes the opposite direction at the timing just after the trailing end of the record sheet 7 in the conveying direction thereof passes through the switch gate 15, and the record sheet 7 is conveyed to the double-side conveying path 20 through the double-side conveying path 19 formed above the switch gate 15 by the conveying force of the discharge roll 17. The record sheet 7 conveyed to the double-side conveying path 20 is conveyed along the double-side conveying path 20 by a conveying roll 21 provided in the double-side conveying path and is again conveyed to the registration roll 11 in a state in which the one face and the reverse face are inverted.
The record sheet 7 is conveyed to the transfer position where the photoconductive drum 2 and the transfer roll 6 abut each other in a synchronized state with the toner image on the photoconductive drum 2 by the registration roll 11 so that the side where no image is formed is positioned on the side of the photoconductive drum 2.
In
The fixing unit 12 includes the heating roller 13 containing a heating source 25 and the pressing roller 14 brought into press-contact with the heating roller 13, as shown in
A sensor 31 as detection means for detecting the rotation position (second position) of the switch gate 15 is disposed on the side face of the housing 27 of the fixing unit 12 on the double-side conveying path 20 side, as shown in
By the way, in the exemplary embodiment, as shown in
The switch gate 15 provided at a position corresponding to the discharge part of the fixing unit 12 in the close state is attached to the cover unit 50 for rotation as shown in
The switch gate 15 is integrally formed of a molded article of synthetic resin, etc., roughly like L-shape in side faces made up of a switch part 41 for switching the discharge conveying path 16 and the double-side conveying path 19 and an operating arm part 42 provided so as to cross one end part of the switch part 41, as shown in
In the image forming apparatus main body 1, a positioning concave part 52 into which the tip of the support shaft 43 of the switch gate 15 is fitted for positioning and a housing part 53 where the support shaft 43 is housed when the cover unit 50 is closed are provided in both end parts 51 in the length direction of the fixing unit 12, as shown in
In the exemplary embodiment, the switch gate 15 is attached to the cover unit 50 side rather than the image forming apparatus main body 1 side; the cover unit 50 is attached to the image forming apparatus main body 1 so that it can be opened and closed with the supporting point 57 as the center, as shown in
Thus, an error of the attachment position of the switch gate 15 to the image forming apparatus main body 1 becomes superposition of an attachment error of the cover unit 50 to the image forming apparatus main body 1 and an attachment error of the switch gate 15 to the cover unit 50 and it is feared that the switch gate 15 may be unable to be attached to a predetermined position of the image forming apparatus main body 1 with good accuracy.
Then, in the exemplary embodiment, the positioning concave part 52 into which the tip of the support shaft 43 of the switch gate 15 is fitted for positioning and the housing part 53 where the shaft support part 43 is housed when the cover unit 50 is closed are provided in both end parts 51 in the length direction of the fixing unit 12 and the support shaft 43 of the switch gate 15 is positioned directly in the positioning concave part 52 on the image forming apparatus main body 1 side, as shown in
As shown in
The switch part 41 of the switch gate 15 is formed as a plurality of switch plates 45 each formed like a flat plate are integrally joined with a predetermined spacing by a joint plate 46 formed like a bend shape on side faces, as shown in
On the other hand, the operating arm part 42 of the switch gate 15 is made of flat plates 55 provided corresponding to the same positions as the switch plates 45 except the center part and placed crossing the switch plates 45 so as to form a predetermined angle, as shown in
The switch part 41 and the operating arm part 42 of the switch gate 15 are formed as the same shape so as to prevent skew or curled selvage called dog-ear from occurring on the record sheet 7 as contact resistance with the record sheet 7 varies along the direction crossing the conveying direction of the record sheet 7 according to the width of the record sheet 7 and are placed in bilateral symmetry with the center part as the reference along the direction crossing the conveying direction of the record sheet 7. Of the operating arm part 42, the flat plate 55 for operating the sensor 31 is only the flat plate 55 positioned on one side of the center part, for example.
In the exemplary embodiment, as shown in
As shown in
In
Further, the exemplary embodiment is configured so as to prevent the gate member 15 attached to the cover unit 50 from interfering with a member on the image forming apparatus main body 1 side when the cover unit 50 is opened or closed.
That is, in the exemplary embodiment, in the operation state with the cover unit 50 closed, the gate member 15 needs to be disposed for rotation at a predetermined position in the discharge part of the fixing unit 12 in the image forming apparatus main body 1, as shown in
Then, in the exemplary embodiment, as shown in
When the cover unit 50 is opened, as shown in
Further, when the cover unit 50 is closed, the switch gate 15 is restricted at the position shown in
In the exemplary embodiment, the opening guide part 49 of the switch gate 15 and the discharge guide part 47 of the switch gate 15 guide the switch gate 15 when the cover unit 50 is opened or closed, but a separate guide member for guiding the switch gate 15 may be provided in the shaft support part, etc., of the switch gate 15 or the shape of some of the switch parts 41 of the switch gate 15 may be made different from the shape of any other switch part for use only for guiding the switch gate 15.
However, if a separate guide member for guiding the switch gate 15 is provided in the shaft support part, etc., of the switch gate 15, the number of components increases and the configuration becomes complicated; if the shape of some of the switch parts 41 of the switch gate 15 is made different from the shape of any other switch part for use only for guiding the switch gate 15, it is feared that the switch part 41 used only for guiding may interfere with the record sheet 7. Thus, it is desirable that the apparatus should be configured as described above.
In the configuration described above, in the image forming apparatus according to the exemplary embodiment, if a conveying failure of a record medium occurs in the discharge part of the fixing means, the record medium where the conveying failure occurs can be removed easily as follows.
In the image forming apparatus, as shown in
At the time, as shown in
Thus, if a paper jam of the record sheet 7 occurs ahead of the switch gate 15 in the discharge part of the fixing unit 12, the switch gate 15 is not rotated clockwise in the figure and the sensor 31 does not detect the record sheet 7 passing through and the control circuit 23 detects occurrence of the jam.
If a jam occurs ahead of the discharge roll 17 after the record sheet 7 passes through the switch gate 15, the switch gate 15 remains rotated clockwise in the figure and when the estimated passage time of the record sheet 7 through the switch gate 15 has elapsed, the sensor 31 does not detect the record sheet 7 passing through and occurrence of the jam is detected.
To form an image on both sides of the record sheet 7, when the record sheet 7 with an image fixed on one side by the fixing unit 12 is discharged by the discharge roll 17, as shown in
At the time, as shown in
Thus, when the record sheet 7 is conveyed to the double-side conveying path 20 through the double-side conveying path 19, if a paper jam of the record sheet 7 occurs ahead of the double-side conveying path 20, the switch gate 15 is not rotated clockwise and the sensor 31 does not detect the record sheet 7 passing through and occurrence of the jam is detected.
If a jam occurs at a midpoint in the double-side conveying path 20 after the record sheet 7 passes through the double-side conveying path 19, the switch gate 15 remains rotated clockwise and when the estimated passage time of the record sheet 7 through the switch gate 15 has elapsed, the sensor 31 does not detect the record sheet 7 passing through and occurrence of the jam is detected.
Thus, when a jam of the record sheet 7 is detected according to the switch gate 15, a message indicating occurrence of the jam is displayed on a control panel, etc., (not shown) and the user opens the cover unit 50 of the image forming apparatus and removes the record sheet 7 where the jam occurs.
To opens the cover unit 50, the user releases the fixing lever 63 of the cover unit 50 and rotates the cover unit 50 clockwise. Then, as shown in
When the cover unit 50 is opened to a position shown in
Thus, the user is enabled to easily remove the record sheet 7 jammed in the discharge part of the fixing unit 12, the double-side conveying path 19, 20, etc., as shown in
When the user closes the cover unit 50 from the completely open state reversing the opening operation described above, the discharge guide part 47 of the switch gate 15 abuts the curved face 70 of the housing 67 of the fixing unit 12 as shown in
The foregoing description of the exemplary embodiment of the present invention has been provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and various will be apparent to practitioners skilled in the art. The exemplary embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling other skilled in the art to understand the invention for various exemplary embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-153170 | Jun 2009 | JP | national |
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| Number | Date | Country |
|---|---|---|
| 2005-60058 | Mar 2005 | JP |
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| Number | Date | Country | |
|---|---|---|---|
| 20100329761 A1 | Dec 2010 | US |
