Device and method for feeding a sheet
AssigneeDainippon Screen Mfg. Co., Ltd.
InventorTakaharu Yamamoto
Life of this patent
Estimating the term…
Abstract
The axial length of a center roller (subroller) (30) is made shorter than the axial length of a main roller (28), and the center roller (30) is placed so that an axis of the center roller (30) is parallel to an axis of the main roller (28) in a base position and so that a nipping pressure is generated in the center position in the axial direction of the main roller (28). A film (sheet) (20) is thereby subjected to a tension in the center portion thereof due to the pulling force of the center roller (30), and the feeding amounts of the film (20) at the left and right portions therefore vary relative to each other. The film (20) thus displaces in the axial direction of the main roller (28) around the center roller (30).
Claims10
A device for preventing sideways motion of a long sheet of film during feeding thereof from a roll of film, comprising:
- a controllably driven main roller rotatably mounted for feeding the long sheet in a direction substantially perpendicular to a rotational axis of the main roller;
- a subroller rotatably mounted so that a rotational axis of the subroller is substantially parallel to the rotational axis of the main roller to define a nip with the main roller so that the sheet is gripped in the nip between the subroller and the main roller at a predetermined pressure and positioned relative to a direction of feed of the long sheet from the roll for applying a force on the sheet to wrap the sheet arcuately around a portion of the surface of the subroller, the roller and subroller together solely drawing the sheet from the roll;
- a tension means mounted for applying a tension to the sheet as the sheet is fed through the nip between the main roller and the subroller in a direction opposite to the feeding direction,
- wherein the subroller has an axial length substantially shorter than the axial length of the main roller and also substantially shorter than a width of the film, and is located relative to a central portion of the main roller so that a nipping pressure is applied by the subroller at said central portion of the main roller, and
- whereby the sheet nipped between the main roller and the subroller is drawn from the roll of film by rotation of the main roller and against the applied tension without sideways drift and is fed in a direction selected to cause the sheet to make surface-to-surface curved peripheral contact with an outer surface of the subroller as the sheet is fed from the roll of film between the main roller and the subroller.
A method for preventing sideways motion of a long sheet of film during continuous feeding thereof from a roll of film, comprising the steps of:
- a) applying a back tension to the sheet;
- b) feeding the sheet against the back tension in a direction substantially perpendicular to an axial direction of a controllably driven main roller while holding the sheet in a nip formed between the main roller and a subroller which is disposed so that an axis of the subroller is substantially parallel to an axis of the main roller;
- and
- c) applying a nipping pressure to the sheet by pressing the sheet against the main roller with the subroller, the subroller having an axial length substantially shorter than an axial length of the main roller and also substantially shorter than a width of the sheet, with the subroller disposed at a central portion of the relatively longer main roller and cooperating therewith so as to prevent sideways motion of the sheet relative to the main roller and the subroller;
- whereby the sheet is fed from the roll of film solely by the main roller cooperating with the subroller in a direction such that the sheet makes surface-to-surface curved peripheral contact with an outer surface of the subroller as the sheet is fed from the roll of film between the main roller and the subroller.
Dependencies are inferred from the claim text.