Patent Application
20070290434
Each of
An example of the embodiment of the invention will be explained as follows, referring to the drawings. Incidentally, the description in the present column does not limit the technical scope and meanings of terminologies in the claims. Further, with respect to directions of X, Y and Z illustrated in
Image forming section 10Y that forms an image in a yellow color has therein charger 2Y arranged around photoconductor drum 1Y representing the first image carrier, exposing unit 3Y, developing unit 4Y, primary transfer roller 5Y representing the first transfer unit and cleaning unit 6Y. Further, image forming section 10M that forms an image in a magenta color has therein photoconductor drum 1M representing the first image carrier, charger 2M, exposing unit 3M, developing unit 4M, primary transfer roller 5M representing the first transfer unit and cleaning unit 6M. Furthermore, image forming section 10C that forms an image in a cyanic color has therein photoconductor drum 1C representing the first image carrier, charger 2C, exposing unit 3C, developing unit 4C, primary transfer roller 5C representing the first transfer unit and cleaning unit 6C. Furthermore, image forming section 10K that forms an image in a black color has therein photoconductor drum 1K representing the first image carrier, charger 2K, exposing unit 3K, developing unit 4K, primary transfer roller 5K representing the first transfer unit and cleaning unit 6K.
Intermediate transfer unit 7 has intermediate transfer member 70 representing a semi-conductive endless-belt-shaped second image carrier that is trained about plural rollers to be supported rotatably.
Images each having a different color formed respectively by image forming sections 10Y, 10M, 10C and 10K are transferred in order on rotating intermediate transfer member 70 by primary transfer rollers 5Y, 5M, 5C and 5K, whereby, a composite color image is formed. Sheet S placed on any one of sheet-feeding cassette 20 representing a sheet placing unit, manual sheet-feeding tray C and large capacity sheet storing device LCT is fed one by one by sheet-feeding roller 106 representing a sheet feeding member and by separation upper roller 107b, and the leading edge of the sheet S hits registration roller 23 representing a second registration member, through preliminary registration roller 109 representing a first registration member and through plural intermediate rollers 22A, 22B, 22C and 22D representing a sheet feeding and conveying member.
After that, a rotation of registration roller 23 is started in synchronization with image forming in image forming sections 10Y, 10M, 10C and 10K and intermediate transfer unit 7, whereby, the sheet S is conveyed to secondary transfer roller 5A representing a transfer unit, thus color images are transferred collectively on the sheet S. The sheet S on which the color images have been transferred is subjected to fixing processing by fixing unit 24, and is interposed between sheet-ejection rollers 25 to be placed on sheet-ejection tray 26 located outside the apparatus.
On the other hand, after the color images have been transferred onto the sheet S by the secondary transfer member 5A, the intermediate transfer member 70 from which the sheet S has been curvature-separated is cleaned by cleaning unit 6A to be free from residual toner. The residual toner is collected in a box by an unillustrated device.
In the course of image forming processing, primary transfer roller 5K is in pressure contact with photoconductor drum 1K constantly through intermediate transfer member 70. Other primary transfer rollers 5Y, 5M and 5C come in pressure contact respectively with corresponding photoconductor drums 1Y, 1M and 1C only in the course of color image forming only, through the intermediate transfer member 70. Secondary transfer unit 5A is brought into pressure contact with the intermediate transfer member 70, only when the sheet S passes through the secondary transfer unit and secondary transfer is carried out.
Next, details of a sheet conveyance unit used in the image forming apparatus shown in
In
When the sheet-feeding roller 106 is driven by an unillustrated driving member to rotate in the direction of arrow “a”, the uppermost sheet S advances in the direction of arrow “b” to touch separation lower roller 107a representing a sheet separating member that lies adjacent to the exit side of the sheet-feeding roller 106. When double feeding is caused, separation lower roller 107a that is driven by an unillustrated driving member to rotate in the direction identical to that of arrow a pushes back the second sheet immediately below the uppermost sheet and thereafter, and the uppermost one sheet only is conveyed by separation upper roller 107b that is driven by an unillustrated driving member to rotate in the direction of an arrow. Incidentally, separation roller 107 is constituted by a pair of separation lower roller 107a and separation upper roller 107b.
A leading edge of the sheet S conveyed by the separation upper roller 107b hits preliminary registration roller 109. The preliminary registration roller 109 is composed of a pair of rollers facing each other, and is provided on a conveyance path for sheet S in a way that the rollers may be rotated by an unillustrated driving member in the direction indicated by an arrow. The sheet S which has hit the preliminary registration roller 109 once is conveyed to image forming apparatus main body GH by the preliminary registration roller 109 that rotates in synchronization with sheet-feeding timing.
Side regulating member adjusting unit 100 will be explained here. The side regulating member adjusting unit 100 is provided with side adjusting plate 117 that is fixed by screws, on side surface 116 of a casing for large capacity sheet storing device LCT and with side regulating member 104.
The side adjusting plate 117 that is fixed on side surface 116 of a casing for large capacity sheet storing device LCT is provided with elongated hole 117a and a scale that is located in the vicinity of the elongated hole and indicates a sheet size, and the side adjusting plate can be fixed by screws in accordance with a sheet size. Further, the side adjusting plate 117 is arranged so that side regulating member 104 capable of swiveling around fulcrum 118 may be mounted thereon. Meanwhile, in the present example, fulcrum pivot 118a is provided on fulcrum 118 so that the fulcrum pivot may extend to the bottom plate of large capacity sheet storing device LCT, for supporting the side regulating member 104. However, a fulcrum that is split into an upper portion and a lower portion can also be used. Further, on the upper portion at the downstream side in the direction for feeding out the sheet, there is provided urging member 103 composed of a compression spring and others, so that both sides of a sheet may be urged constantly by the side regulating member 104. Specifically, the urging member 103 is provided at the position that is about 30 mm downward from the upper end portion of the side regulating member 104 and is about 50 mm from the tip portion of the downstream side in the direction of feeding out a sheet, and it urges with a force of about 100 N-200 N.
Each of
By providing the side regulating member adjusting unit 100 having the side regulating member 104 of this kind, the present structure has made it possible to adjust to ±0.1 mm from the conventional errors of ±0.5 mm in the sheet width direction (Z direction) for the design standard.
Since an image forming apparatus equipped with large capacity sheet storing device LCT is generally voluminous and massive, flatness and strength of a floor face are greatly influential. For example, if the flatness of the floor is poor (odd-shaped), a frame of the main body of the apparatus follows the poor-flatness and is distorted. Though a height adjusting member is attached on the main body of the apparatus as measures for this distortion, sheet conveyance accuracy is badly affected even when a distortion of a large capacity sheet storing device is small. Therefore, large capacity sheet storing device LCT of the invention is characterized to be capable of adjusting, so that an error of sheet width direction (Z direction) for the design standard may be within ±0.1 mm, by using again adjusting jig SJ after installing the apparatus and fixing it with a height adjusting member. Incidentally, the adjusting jig SJ may either be furnished to the apparatus, or be carried by a serviceman. Further, although the present example is structured so that the upstream side in the direction to feed out a sheet is fulcrum 118, and the downstream side is rotatable, it is also possible to structure to be opposite to the foregoing.
As a sheet separator, small-sized fan 120 is provided on the large capacity sheet storing device LCT, in a way to feed out air to air-blowing outlet 122 (see
When the fan 120 rotates, air is forwarded from the air-blowing outlet 122 to blow against several sheets located at the upper portion of stacked sheets S. Air flows through gaps between several sheets positioned at the upper portion of sheets S from one side thereof. Owing to this, adhesion strength between sheets is reduced, and upper several sheets in sheets S are separated into pieces. An uppermost sheet among sheets S thus separated is taken out by the sheet-feeding roller 106 to be fed into the image forming section.
Constructions and functions of the sheet-feeding roller 106 that feeds a sheet loaded on cassette 20 provided on image forming apparatus main body GH or on manual sheet-feeding tray C, separation roller 107 and preliminary registration roller 109 are the same as those of the members which are given the same symbols as in the large capacity sheet storing device LCT. However, one-sided sheet sensor 115 is not provided, and corrections for skewing and one-sided sheet S for positions of image forming by the image forming unit are carried out by unillustrated positioning members.
That is, an image on the sheet that is fed from LCT can respond to a high image quality mode in which an image is printed more accurately at the fixed position from an edge of the sheet, while, an image on the sheet that is fed from cassette 20 or from manual sheet-feeding tray C is for an ordinary image mode that is slightly inferior to LCT in terms of accuracy of a position from an edge of the sheet.
In the invention, side regulating member adjusting unit 100 is provided on large capacity sheet storing device LCT and side regulating member 104 capable of rotating is further provided as explained above, whereby, an angle in the sheet width direction can be adjusted at the location nearest to sheet-feeding roller 106, thus, an image printed by an image forming apparatus on a sheet fed and conveyed is free from displacement, resulting in preparation of booklets which have been bound to be of high quality.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2006-168450 | Jun 2006 | JP | national |
