Claims
- 1. A sheet feeder for use in a printer having a main unit including a printing section said sheet feeder having a platen disposed at a location opposite said printing section and adapted to be rotatively driven, comprising at least one feed roller and means for rotatably supporting the feed roller on the printer, coupling means for operatively coupling said at least one feed roller to said platen for drivingly rotating said feed roller positioned in a working location in response to rotation of the platen,
- said at least one feed roller at said working location being spaced out of contact from said platen so as to avoid pinching the sheet between said at least one feed roller and said platen; and
- at least one urging means for engaging a printing sheet with said at least one feed roller in the working location, said at least one urging means comprising a pair of urging portions respectively disposed at opposite sides of a corresponding one of said at least one feed roller in an axially spaced direction of said corresponding one feed roller, and overlapping with said corresponding one feed roller in a direction radially thereof for urging the printing sheet so as to engage the printing sheet with said corresponding at least one feed roller each of said urging portions comprising a ramp-like static guide means;
- whereby the printing sheet is smoothly settable on the platen;
- said supporting means being operable to move said at least one feed roller between said working location and an inoperative location on said printer, further comprising said supporting means being operable to release the drive coupling between said at least one feed roller and said platen through said coupling means in the inoperative location,
- a removably mounted tractor unit including means for detachably mounting said tractor unit on said main unit, the detachable mounting means including an engaging portion,
- wherein said at least one feed roller in said inoperative location enables said tractor unit to be mounted on said main unit of said printed by allowing the engaging portion to detachably engage said main unit for feeding a printing sheet of continuous form to said tractor unit.
- 2. A sheet feeder according to claim 1, wherein said platen has an axis, a plurality of said feed rollers being disposed at spaced intervals along and in parallel with the axis of said platen.
- 3. A sheet feeder according to claim 1, further comprising: at least one friction roller disposed in a sheet feed path of said sheet feeder upstream from said printing section in a selectively rotatable manner with said platen,
- wherein said at least one feed roller is disposed in the sheet feed path downstream from said printing section.
- 4. A sheet feeder according to claim 1, wherein said supporting means includes a cover adapted to be disconnectably fitted into a cover receiving portion formed in an outer wall of said main unit of said printer, said at least one feed roller being fastened to a roller shaft for rotation therewith, said roller shaft being rotatably supported by said cover at an end portion thereof facing said platen, said platen including a platen shaft extending axially of said platen, said coupling means including said platen shaft, said roller shaft, a first gear fastened to said roller shaft for rotation therewith, and a second gear fastened to said platen shaft for rotation therewith and in mesh with said first gear, said cover being engageable with a part of said engaging portion formed on an outer wall of said tractor unit upon mounting said tractor unit on said main unit so that said cover and said feed roller held at the inoperative location wherein engagement between said first gear and said second gear is released, said cover and feed roller assuming said working location where said first gear and said second gear are engaged with each other upon disconnecting said tractor unit from said main unit.
- 5. A sheet feeder according to claim 1, further comprising: at least one friction roller disposed in selective urged contact with said platen, and a roller release lever operatively coupled to said at least one friction roller and operable to disconnect said friction roller from said platen.
- 6. A sheet feeder for use in a printer having a main unit including a printing section said sheet feeder having a platen disposed at a location opposite said printing section and adapted to be rotatively driven, comprising at least one feed roller and means for rotatably supporting the feed roller on the printer, coupling means for operatively coupling said at least one feed roller to said platen for drivingly rotating said feed roller positioned in a working location in response to rotation of the platen,
- said at least one feed roller at said working location being spaced out of contact from said platen so as to avoid pinching the sheet between said at least one feed roller and said platen; and
- at least one urging means for engaging a printing sheet with said at least one feed roller in the working location, said at least one urging means comprising a pair of urging portions respectively disposed at opposite sides of a corresponding one of said at least one feed roller in an axially spaced direction of said corresponding one feed roller, and overlapping with said corresponding one feed roller in a direction radially thereof for urging the printing sheet so as to engage the printing sheet with said corresponding at least one feed roller each of said urging portions comprising a ramp-like static guide means;
- whereby the printing sheet is smoothly settable on the platen;
- said supporting means being operable to move said at least one feed roller between said working location and an inoperative location on said printer wherein said main unit has an outer wall thereof formed with a cover receiving portion, said supporting means includes a cover member being disengageably connected into said cover receiving portion, said at least one feed roller being rotatably supported by said cover member, said urging portions being formed on the outer wall of said main unit of said printer at a location facing said platen.
- 7. A sheet feeder according to claim 6, wherein said cover member is formed with guide means for guiding the printing sheet toward said urging portions, the urging portions being of unitary construction with the outer wall.
- 8. A sheet feeder according to claim 6, wherein said platen has a platen shaft extending axially thereof, said at least one feed roller having a roller shaft extending axially thereof and rotatable in unison therewith, said coupling means including said platen shaft, said roller shaft, a first gear fastened to said roller shaft and rotatable in unison therewith, a second gear being fastened to said platen shaft in a manner rotatable in unison therewith and in mesh with said first gear.
Priority Claims (2)
| Number |
Date |
Country |
Kind |
| 60-180058 |
Aug 1985 |
JPX |
|
| 60-196876 |
Sep 1985 |
JPX |
|
BACKGROUND OF THE INVENTION
This application is a continuation of application Ser. No. 894,883, filed 8/8/86, now abandoned.
The present invention relates to a printer and more particularly to a sheet feeder for use in printers, which is simple in operation for setting a printing sheet.
Printers of the type having a platen disposed at a location opposite a printing head, and frictional rollers disposed in urged contact with the platen at the upstream side in a sheet feed path of the printer with respect to the printing head are known. In these conventional printers. It is also known to provide therein a bail roller mechanism including bail rollers fastened to a shaft which is rotatably supported at its opposite ends by levers pivotally supported in a direction toward and away from the platen. The bail rollers are adapted to be in urged contact with the platen at the downstream side in the street feed path with respect to the printing head, so that a sheet is frictionally engaged between the platen and the friction rollers and between the platen and the bail rollers, to be fed along the sheet feed path by rotation of the platen. These bail rollers. located at the downstream side make it possible to continue the sheet feeding operation of the sheet even when and after the sheet has reached a location in the sheet feeding path where the trailing end thereof assumes a position downstream of the friction rollers at which the trailing end is disengaged from the platen, so that printing onto the sheet can be positively effected over the entire length of the sheet up to the trailing end thereof. In a printer of this kind, however, to set the sheet around the platen, it is necessary to displace the bail rollers in the direction away from the platen so as to release the urged contact with the platen. In case that the printer is so designed that the displacement of the bail rollers must be effected manually, a complicated operation therefor by the user is required, resulting in inconvenience to the user, whereas, if the printer is so arranged as to automatically displace the rollers by the use of a solenoid mechanism, etc., the printer becomes high in cost.
Further, in order to selectively use both of a cut form sheet and a continuous form sheet, it has been conventionally known to employ printers of the type having two kinds of upper covers each adapted to be detachably mounted on the main unit of the printer, where either one of them is selectively employed in dependence on the type of sheet to be used. Namely, an upper cover of the kind having the above-mentioned bail roller mechanism is mounted on the printer unit when the cut form sheet is to be fed, whereas another kind of upper cover having a tractor unit is mounted for feeding the continuous form sheet. In this manner, the conventional printers require plural covers having different arrangements from each other for feeding operation of both the types of sheet. This makes the printer costly, and makes the sheet setting operation of the printer complicated since the cover must be replaced each time the printing sheet is changed from the cut-form type to the continuous form type and vice versa.
It is an object of the invention to provide a sheet feeder for use in printers, which is simple in operation in setting a printing sheet and low in cost.
It is another object of the present invention to provide a sheet feeder in printers, which is capable of positively delivering a printing sheet even in a condition that the trailing end of the printing sheet has reached a sheet feeding position in the vicinity of a location opposite a printing section of the printer, so that a printing operation onto the printing sheet can be positively effected over the entire length of the sheet up to the trailing end thereof.
It is a further object of the present invention is to provide a sheet feeder capable of delivering a printing sheet of both of cut form and continuous form, without the need to replace component parts of the feeder depending on the type of printing sheet.
It is a still further object of the present invention is to provide a sheet feeder capable of suppressing noise generated upon printing.
According to the present invention, there is provided a sheet feeder for use in printers having a printing section. The sheet feeder comprises a platen disposed at a location opposite the printing section and adapted to be rotatively driven. At least one feed roller, which is rotatably supported and operatively connected to the platen through coupling means for rotation with rotation of the platen, is disposed at a location separate from the platen. Further, at least one urging means is provided for bringing a printing sheet into urged contact with the at least one feed roller. Since the feed roller is separated from the platen, the printing sheet is smoothly settable, without being blocked by the feed roller. The feed roller is caused to rotate with rotation of the platen, and the printing sheet brought into urged contact with the roller by the urging means is delivered with rotation of the feed roller.
US Referenced Citations (4)
Foreign Referenced Citations (1)
| Number |
Date |
Country |
| 73980 |
Apr 1984 |
JPX |
Continuations (1)
|
Number |
Date |
Country |
| Parent |
894883 |
Aug 1986 |
|
Patent Grant
4787764
