1. Field of the Invention
The present invention relates to an image forming apparatus and, more particularly, relates to an image forming apparatus in which a sheet conveying path on which a sheet passes is provided above a sheet storage portion attached to an apparatus body.
2. Description of the Related Art
Conventionally, there are image forming apparatuses which form images on a sheet using an electrophotograhic image forming system, and these image forming apparatuses include, for example, copying machines, laser beam printers, LED printers, facsimile apparatuses and word processors. Generally, in such a conventional image forming apparatus, standard size sheets of a high use frequency are stacked in a sheet feeding cassette in which a predetermined number of sheets can be stacked and are fed, and special sheets other than standard size sheets of a low use frequency such as cardboards and standard size sheets such as elongated sheets are manually fed.
Further, to feed a cardboard and a special sheet, one or a plurality of sheets is manually set in a manual feed tray, and is fed toward an image forming portion by a guiding portion of a sheet conveying path. Meanwhile, in such an image forming apparatus, the guiding portion of the sheet conveying path is arranged above the sheet feeding cassette.
Further, some conventional image forming apparatuses have re-feeding/conveying portion which feeds again a sheet for forming an image on a back surface after an image is formed on one surface, to an image forming portion. Furthermore, also in the re-feeding/conveying portion of such an image forming apparatus, a guiding portion which guides to the image forming portion a sheet on one surface of which an image is formed is arranged above the sheet feeding cassette (see Japanese Patent Laid-Open No. 2006-69732).
Incidentally, in such a conventional image forming apparatus, a gap is provided between a guiding portion and a sheet feeding cassette such that, when the sheet feeding cassette is attached and detached to and from the image forming apparatus body, the guiding portion of the sheet conveying path and the sheet feeding cassette do not interfere with each other.
Meanwhile, a plurality of conveying rollers which forms pairs of conveying rollers is attached to the guiding portion, and therefore a reaction force is applied from the conveying rollers when a sheet is conveyed. Further, when the reaction force of the conveying rollers is applied in this way, the gap is formed between the conveying rollers and the sheet feeding cassette, and therefore there is a concern that the conveyance guiding portion deflects downward and deforms. Furthermore, even when, for example, an image forming apparatus is left in high-temperature environment after product shipping, a gap is formed between a sheet feeding cassette and a conveyance guiding portion, and therefore there is a concern that the conveyance guiding portion deflects downward and deforms.
Meanwhile, when the feeding guiding portion deforms downward in this way, for example, a sheet nipping pressure of pairs of conveying rollers decreases and a conveying force decreases. In addition, to prevent deformation of the conveyance guiding portion, there is a countermeasure of sufficiently securing the thickness of the conveyance guiding portion and improving rigidity of the conveyance guiding portion or reinforcing the conveyance guiding portion using, for example, a sheet metal.
However, when the thickness of the conveyance guiding portion is sufficiently secured or the conveyance guiding portion is reinforced using, for example, a metal sheet, the image forming apparatus not only becomes heavy and large but also causes an increase in cost. That is, the above countermeasure cannot sufficiently meet requests of reducing cost, reducing the weight and reducing the size of the image forming apparatus.
The present invention is made in light of this situation, and it is desirable to provide an image forming apparatus which is low-cost, small and light, and which can stably convey a sheet.
The present invention has in an image forming apparatus a sheet storage portion which is detachably attached to an apparatus body, a guiding member which is positioned above the sheet storage portion attached to the apparatus body and which forms a sheet conveying path which guides a sheet, and a regulating portion which is provided in the sheet storage portion, and which regulates a position of the sheet in a width direction orthogonal to a sheet feeding direction, and abuts on the guiding member and regulates downward deformation of the guiding member.
According to the present invention, there is provided an image forming apparatus including a regulating portion which regulates a position of a sheet in a width direction and regulates downward deformation of a guiding member which forms a sheet conveying path on which the sheet passes. Consequently, a low-cost, small and light image forming apparatus can stably convey the sheet.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
An embodiment for implementing the present invention will be described in detail below with reference to the drawings.
The image forming portion 102 includes process cartridges 4 (4a to 4d) which are four image forming units of four colors of magenta (M), yellow (Y), cyanogen (C) and black (Bk) provided in parallel. Further, the image forming portion 102 includes, for example, a scanner portion 3 and an intermediate transfer belt 33 which is an endless intermediate transfer member. In addition, each process cartridge 4 includes a photosensitive drum 5 (5a to 5d) which is arranged to rotate counterclockwise, and an electrostatic latent image is formed on a surface of this photosensitive drum 5 by exposure by the scanner portion 3.
Meanwhile, the intermediate transfer belt 33 contacts each photosensitive drum 5 of the process cartridge 4 linearly arranged above, and is stretched by a driving roller 31 and a counter roller 32 and rotates in a clockwise direction upon formation of a color image. Further, primary transfer rollers 34 are in contact with this intermediate transfer belt 33 upon image formation, and, when the intermediate transfer belt 33 rotates, these primary transfer rollers 34 sequentially transfer each color toner image formed on the photosensitive drum 5, on the intermediate transfer belt 33. Furthermore, each color toner image transferred on this intermediate transfer belt 33 is transferred to a sheet when a secondary transferring portion formed by a secondary transfer roller 62 and the counter roller 32 nips and conveys the sheet.
The sheet feeding portion 103 includes a sheet feeding cassette 70 which is a sheet storage portion which is detachably attached to a printer body 101 which is an image forming apparatus body, and a sheet feeding roller 76 which feeds a sheet P stored in the sheet feeding cassette 70. In addition, this sheet feeding cassette 70 is provided with a sheet supporting plate 70a which supports the stored sheet P and presses the sheet P against the sheet feeding roller 76. Further, this sheet feeding cassette 70 is provided with side regulating members 71 which are regulating members which regulate the position of the stored sheet P in a width direction orthogonal to a sheet feeding direction and which can move in the width direction.
In addition,
Next, an image forming operation of the color laser beam printer 100 formed in this way will be described. To form a color image on a sheet, the photosensitive drum 5 is first electrically charged, and then the photosensitive drum 5 is exposed by the scanner portion 3 based on an image signal of each color component transmitted from a controller which is not illustrated. By this means, an electrostatic latent image is formed on the surface of the photosensitive drum.
Next, this electrostatic latent image is developed by each color toner of magenta, yellow, cyanogen and black to form a toner image on the photosensitive drum. Subsequently, when the toner image comes to a transfer site at which the photosensitive drum 5 and the intermediate transfer belt 33 abut on each other following rotation of the photosensitive drum 5, the primary transfer rollers 34 apply primary transfer biases. By this means, the toner image on the photosensitive drum is primarily transferred to the intermediate transfer belt 33 which is rotating in the clockwise direction. In addition, this toner image is transferred on the intermediate transfer belt sequentially in order of magenta, yellow, cyanogen and black following rotation of the intermediate transfer belt 33, and thereby a color toner image is formed on the intermediate transfer belt.
Meanwhile, the sheet P is fed from the sheet feeding cassette 70 by the sheet feeding roller 76 according to a predetermined sequence control timing in parallel to this color toner image forming operation. Further, the fed sheet P is conveyed to the registration roller 63 which is stopping, and skewing feeding of the sheet P is corrected by this registration roller 63. Then, the registration roller 63 starts rotating at a timing when the color toner image formed on the intermediate transfer belt and the front end of the sheet P align.
By this means, the sheet P which stops once is conveyed to the secondary transferring portion formed by the secondary transfer roller 62 and the counter roller 32, and a color toner image is transferred to the sheet P by a transfer bias applied to the secondary transfer roller 62. Further, after the color toner image is transferred, the sheet P is conveyed to a fixing portion 61 from the secondary transferring portion, the sheet P is heated and pressured by this fixing portion 61 and a color toner image is fixed on the sheet. Furthermore, the sheet P on which the color toner image is fixed is then discharged to a discharge tray 104 provided on an upper surface of the printer body by a pair of discharge rollers 60.
Meanwhile, to manually feed a sheet, the manually fed sheet P1 is inserted in the opening portion 105 provided on one side surface of the printer body 101. By this means, the sheet P1 passes the sheet conveying path R while being guided by the conveyance guiding member 50 and reaches the registration roller 63, and then skew feeding of the sheet P1 is corrected by the registration roller 63 similar to the sheet P stacked in the sheet feeding cassette 70. Subsequently, similar to the sheet P stacked in the sheet feeding cassette 70, a color toner image is transferred and fixed on the sheet P1 and the sheet P1 is discharged to the discharge tray 104.
Meanwhile, as illustrated
Furthermore, as illustrated in
Further, when the sheet feeding cassette 70 is attached to the printer body 101 in this way, it is possible to prevent deformation of the conveyance guiding member 50 by supporting the conveyance guiding member 50 by means of the side regulating members 71. That is, in the present embodiment, the side regulating members 71 and the supporting portions 71a of the side regulating members 71 form a regulating portion 71A which regulates the position of the sheet in the width direction, and abuts on the conveyance guiding member 50 and regulates downward deformation of the conveyance guiding member 50.
Meanwhile, in the present embodiment, the abutting portion 50a of the conveyance guiding member 50 is formed in an entire movable range of the side regulating members 71 in the width direction as illustrated in
In addition, when the sheet feeding cassette 70 is detached from the printer body 101, and the sheet feeding cassette 70 is drawn a predetermined distance, the conveyance guiding member 50 and the side regulating members 71 do not contact each other. Therefore, it is possible to reduce a load upon removal of the sheet feeding cassette 70. Further, when the sheet feeding cassette 70 is attached to the printer body 101, the conveyance guiding member 50 and the side regulating members 71 do not contact each other until the sheet feeding cassette 70 is pushed in a predetermined distance. Therefore, it is possible to reduce a load upon attachment of the sheet feeding cassette 70.
As described above, as in the present embodiment, when the sheet feeding cassette 70 is attached to the printer body 101, the conveyance guiding member 50 is supported by the side regulating members 71. Therefore, it is possible to prevent deformation of the conveyance guiding member 50. As a result, it is possible to stably convey a sheet without reinforcing the conveyance guiding member 50.
In addition, in the present embodiment, when the sheet feeding cassette 70 is attached, the side regulating members 71 abut on the conveyance guiding member 50 to have the side regulating members 71 support the conveyance guiding member 50. However, the side regulating members 71 may not abut on the conveyance guiding member 50 when the sheet feeding cassette is attached, and, when the conveyance guiding member 50 deflects downward in an elastic range, that is, when the conveyance guiding member 50 deforms downward a predetermined amount, the conveyance guiding member 50 may abut on the side regulating members 71. In case of this configuration, it is possible to further reduce a load upon attachment and detachment of the sheet feeding cassette 70. Further, the conveyance guiding member 50 can be supported in this case without providing the supporting portions 71a to project from the side regulating members 71.
Incidentally, although, as described above, the abutting portion 50a of the conveyance guiding member 50 is provided over the entire movable range of the side regulating members 71 in the conveyance guiding member 50 as illustrated in
Further, by moving the side regulating members 71 toward the center of the width direction as illustrated in
Next, a second embodiment of the present invention will be described.
In
Thus, when the sheet feeding cassette 70 is attached to the printer body 101, it is possible to prevent skew feeding of a sheet caused by unintentional movement of the side regulating members 71 upon feeding of a sheet by regulating movement of the side regulating members 71. By this means, it is possible to prevent deformation of the conveyance guiding member 50, and more stably convey the sheet.
In addition, although an example has been described with the present embodiment where the present invention is applied to a conveying guide which guides a manually fed sheet arranged above the sheet feeding cassette 70, the present invention is by no means limited to this. The present invention is also applicable to a configuration in which a re-conveying path which conveys a sheet on one surface of which an image is formed to an image forming portion again is arranged above the sheet feeding cassette to form an image on both surfaces of the sheet.
Further, although, in the present embodiment, a movement regulating portion 80 which regulates movement of the side regulating members 71 in the width direction when the sheet feeding cassette 70 is attached is formed with the position regulating portions 50b which have tooth shapes and the target position regulating portions 71b, the present invention is not limited to this.
For example, at least one side of the position regulating portions 50b and the target position regulating portions 71b may be formed by a friction member. In addition,
Further, although a configuration has been described with the present embodiment where a manually fed sheet P1 is inserted one by one in an opening portion 105 provided on one side surface of the printer body 101, the present invention is by no means limited to this. For example, a configuration may be employed where a manual feed tray and a separating/feeding mechanism are provided on one side surface of the printer body 101, a user loads a plurality of sheets to the manual feed tray and the separating/feeding mechanism separates a sheet from the top of the tray and feeds the sheet.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2012-037543, filed Feb. 23, 2012, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2012-037543 | Feb 2012 | JP | national |
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Number | Date | Country |
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2006-069732 | Mar 2006 | JP |
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Number | Date | Country | |
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20130221612 A1 | Aug 2013 | US |