Typewriting machines – Sheet or web – Including friction-feed means
Reexamination Certificate
2001-04-04
2003-06-24
Colilla, Daniel J. (Department: 2854)
Typewriting machines
Sheet or web
Including friction-feed means
C400S642000, C400S645000
Reexamination Certificate
active
06582140
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a recording media discharging device for use in a paper discharging portion of an ink-jet printer, for example, as well as relating to an ink-jet printer with the discharging device. In particular, the present invention is directed to preventing damage to recording media in a discharging device using a star roller for ejecting recording media.
(2) Description of the Prior Art
Generally, in an ink-jet type image forming apparatus (referred to hereinbelow as an ink-jet printer), ink drops are ejected sequentially on the upper surface of recording paper being continuously fed to perform image forming. The recording paper with images formed thereon is discharged and stacked one after another onto the paper output tray by a discharging device.
For example, Japanese Patent Application Laid-Open Hei 6 No. 115195 discloses a discharging device which is comprised of a rubber roller in contact with the undersurface of a recording paper and a star roller in contact with the upper surface (image forming face) of the recording paper. The recording paper is held between and conveyed by these two rollers, whereby the recording paper is discharged to the paper output tray. This rubber roller is a drive roller which is turned by a drive force transmitted from a motor. The star roller is an follower roller, which is turned along with the conveyance of the recording paper. This star roller is formed with discrete projections radially arranged on the peripheral surface thereof parallel to its axis. Formed on the peripheral surface between these projections are recessed portions, which are recesses between the projections. Therefore, only the projections come in contact with the upper surface of the recording paper so as to reduce the contact area of the roller with the upper surface of the recording paper, whereby ink smudges on the recording paper will not occur.
However, when such a star roller is used, there occurs the problem as follows. That is, when the leading part of a recording paper ‘a’ (the portion on the downstream side with respect to the paper feed direction) is held and conveyed by the discharging device as shown in
FIG. 1A
, and when the center portion of recording paper ‘a’ is held and conveyed by the discharging device as shown in
FIG. 1B
, a high enough conveying force is given to recording paper ‘a’. When, however, the rear end part of recording paper ‘a’ (the portion on the upstream side with respect to the sheet feed direction) is held and conveyed as shown in
FIG. 1C
, the leading edge of recording paper ‘a’ comes into contact with a paper output tray ‘b’, so that the frictional force between this recording paper ‘a’ and output tray ‘b’ acts as a resistance against conveyance, so that a sufficient enough conveying force cannot be given to recording paper ‘a’. When the holding of recording paper ‘a’ between rubber roller ‘c’ and star roller ‘d’ is released from this state, as shown in
FIG. 1D
, the rear edge of recording paper ‘a’ may abide near the contact point between rubber roller ‘c’ and star roller ‘d’ due to insufficiency of the conveying force. Once this situation occurs, there is a risk of the rear edge of recording paper ‘a’ (the upstream edge with respect to the feed direction) dropping into the recessed portion ‘e’ on the peripheral side of the star roller, as shown in FIG.
2
A. In detail, since paper output tray ‘b’ is generally located below the exit port of recording paper ‘a’ in order to allow for beneficial sheet discharge operation. Therefore, in the state that the front end part of recording paper ‘a’ is put in contact with paper output tray ‘b’ as shown in
FIG. 1D
, the rear part of recording paper ‘a’ springs upwards, which further promotes the fitting of the rear edge into the recessed portion ‘e’.
Star roller ‘d’ further rotates from this condition where the rear edge of recording paper ‘a’ has dropped into recessed portion ‘e’, the rear edge of recording paper ‘a’ may get nipped between the edge, designated at ‘f’ of the exit port (one of the printer casing members) and the projection ‘g’ on the star roller peripheral side as shown in FIG.
2
B and recording paper ‘a’ may be damaged. In general, star roller ‘d’ is composed of a multiple number of roller elements arranged along the direction perpendicular to the feed direction of recording paper ‘a’ (perpendicular to the document surface of FIGS.
2
A and
2
B), so recording paper ‘a’ is damaged at multiple sites along its rear edge, thus making it impossible to provide a beneficial printout. In this way, the discharging device of the conventional ink-jet printers has not yet provided sufficiently reliable paper discharge performance.
SUMMARY OF THE INVENTION
The present invention has been devised in view of what has been discussed above, it is therefore an object of the present invention to provide a discharging device using a star roller, which can realize a beneficial discharge operation by avoiding recording paper being damaged by the rear edge of recording paper dropping into the recessed portions on the peripheral side of the star roller.
In order to achieve the above object, the present invention prevents the rear edge from dropping into recessed portions of the star roller by guiding the rear edge of the recording medium in the discharge direction when the recording medium passes the star roller.
Specifically, the present invention is featured as follows:
In accordance with the first aspect of the present invention, a recording media discharging device using a star roller for conveying recording media with images formed thereon in the discharge direction, includes: guide means for guiding the upstream edge of a recording medium with respect to the feed direction so that the edge will not drop into the recessed portions on the peripheral side of the star roller when the edge passes the star roller.
In accordance with the second aspect of the present invention, the recording media discharging device having the above first feature is characterized in that the star roller is comprised of multiple elements arranged at separate positions on the rotary shaft that is extended perpendicularly to the feed direction of recording media, and as the guide means a pair of guide elements are arranged close to each star roller element and on both sides thereof with respect to the extended direction of the rotary shaft.
In accordance with the third aspect of the present invention, the recording media discharging device having the above first feature is characterized in that the guide means has a guide surface for guiding the upstream edge of a recording medium with respect to the feed direction, and this guide surface is provided with a slant which is inclined gradually up in the paper discharge direction, thereby prevents the edge of the recording medium from dropping into the recessed portions of the star roller while permitting the edge of the recording medium to jump upwards.
In accordance with the fourth aspect of the present invention, the recording media discharging device having the above second feature is characterized in that the guide means has a guide surface for guiding the upstream edge of a recording medium with respect to the feed direction, and this guide surface is provided with a slant which is inclined gradually up in the paper discharge direction, thereby prevents the edge of the recording medium from dropping into the recessed portions of the star roller while permitting the edge of the recording medium to jump upwards.
In accordance with the fifth aspect of the present invention, the recording media discharging device having the above first feature further includes: a conveying roller for holding and conveying recording media between itself and the star roller and is characterized in that the level distance between the outer peripheral surface of the conveying roller and the bottom of the guide means is set to be equal to or shorter than the interval between adjacent projections formed on the per
Hayashiyama Shunichi
Kimura Masaharu
Ogawa Tatsuya
Ohkawa Yasunobu
Yoshida Shigeru
Colilla Daniel J.
Renner Otto Boisselle & Sklar
Sharp Kabushiki Kaisha
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