Typewriting machines – Sheet or web – With holder for single sheet
Patent
1998-05-13
2000-05-09
Bennett, Christopher A.
Typewriting machines
Sheet or web
With holder for single sheet
400521, 400536, B41J 1322
Patent
active
060594713
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for transporting a sheet to be printed in a printer, with a carriage which is designed for receiving the sheet and which can be displaced on a fixed stand perpendicularly to the line direction between a starting position for inserting and removing the sheet and an end position moved into the printer, with a drive device for the carriage and with a releasable clamping device for clamping the sheet, which clamping device is arranged on the carriage and is provided with means for its own release which are actuated by actuating means coming into engagement with the carriage in the starting position of the latter.
2. Description of the Related Art
Such a device is known from European Patent Document EP 0,080,723 B1. Racks, which engage with toothed segments that can be pivoted using a motor, are provided on the carriage. Provided as a clamping device is a leaf spring, one end of which is fastened to the carriage and the free end of which bears under pre-stress on the carriage. Arranged on the leaf spring is a lift-off pin which projects through a bore, running from the rear side of the rack in the region of the toothing of the latter, into a tooth space and, in the position corresponding to the starting position of the carriage, is displaced by a tooth of the toothed segment with the desired effect of lifting off the leaf spring.
In order to ensure that the clamping device is closed before the carriage is moved into the printer, the pivoting shaft carrying the toothed quadrants is longitudinally displaceable. Before the transport movement of the carriage commences, the pivoting shaft is pushed so far to the side by a cam disk that the lift-off pin is released. The shaft is pushed into its original position again only when the toothed quadrant no longer comes into engagement with the tooth space containing the lift-off pin.
The known device is highly complicated in terms of construction, since several movable control elements have to interact at various points in the device.
SUMMARY OF THE INVENTION
An object of the invention is, therefore, to provide a device of this type, whose device is simple to control.
This and other objects are achieved by (insert claim 1).
The invention proceeds from the notion that it is perfectly possible for the carriage to be moved, with a sheet to be printed and with the clamping device released, when it is transported only in the direction of ejection. The device according to the invention makes use of this knowledge, in that, to close the clamping device, the carriage is moved first in the direction opposite to the end position and thereafter only in the direction of the end position moved into the printer. Since the sheet, due to its weight, rests snugly with its lower edge on the bearing surface, it cannot lift off from the latter during the upward movement and, finally, is grasped in the exact position by the clamping device.
For this purpose, the clamping device comprises a bearing surface for the sheet and a clamping lever which is spring-loaded in the clamping direction and on which an actuating cam is mounted. Furthermore, there is provided on the stand a control bar, on which the actuating cam is guided during the displacement of the carriage, in such a way that, in the starting position of the carriage, the actuating cam bears on a predetermined portion of one side of the control bar, with the result that the clamping device is released. After the starting position has been passed in the direction opposite to the end position, the actuating cam passes the upper edge of the control bar, with the result that the clamping device is closed. During the movement of the carriage in the direction of the end position, the actuating cam slides along on the other side of the control bar as far as the lower end of the latter, after passing the end is shifted in the direction of the one side of the control bar and, during the subsequent movement of the carriage, slides along on said con
REFERENCES:
patent: 4812064 (1989-03-01), Hatakeyama et al.
patent: 5468079 (1995-11-01), Murakoshi et al.
Baitz Gunter
Dobring Wilfried
Bennett Christopher A.
Siemens Nixdorf Informationssysteme AG
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