Browse Prior Art Database

Frame Stiffness and Form Thickness Compensation Mechanism

IP.com Disclosure Number: IPCOM000118822D
Original Publication Date: 1997-Jul-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 138K

Publishing Venue

IBM

Related People

Harris, RH: AUTHOR [+2]

Abstract

Slip printers are required to print on forms of different thickness. Impact technology is generally used for printing on forms with multiple copies. The gap between the paper and printhead needs to be controlled within several thousandths of an inch. Therefore, the gap must increase in accordance to the paper thickness. The invention disclosed here provides a method of adjusting the gap for forms thickness with an adjustment to account for the tolerances and inherent flexibility of the mechanism itself.

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This is the abbreviated version, containing approximately 52% of the total text.

Frame Stiffness and Form Thickness Compensation Mechanism

      Slip printers are required to print on forms of different
thickness.  Impact technology is generally used for printing on forms
with multiple copies.  The gap between the paper and printhead needs
to be controlled within several thousandths of an inch.  Therefore,
the gap must increase in accordance to the paper thickness.  The
invention disclosed here provides a method of adjusting the gap for
forms thickness  with an adjustment to account for the tolerances and
inherent flexibility  of the mechanism itself.

      The mechanism is shown in part in Fig. 1.  A one-piece steel
frame, Q, supports the feedroll, A, and the backup shaft, B.  The
platen, C, is mounted on a pivot shaft, D, that is held in the frame
by spring clips, E.  The backup shaft, B, is positioned in the frame
by the right bearing, HR, and the left bearing, HL.  The back up
roller, T, is attached to the back up shaft through a pinned joint,
R.  This joint allows the roller to remain parallel to the feedroll,
A, even when  the feedroll and the backup shaft are not parallel.
The feedroll, A, is  positioned by the right bearing, GR, and the
left bearing, GL.  The left  side can move front to rear allowing the
feedroll to pivot about the right side as shown by arrow, S.
Printhead, F, shown with dotted lines,  is mounted on guide shafts,
R1, in the frame.

      Fig. 2 shows the left side view of the mechanism.  The backup
shaft left end is supported by an eccentric bushing, I, that is
mounted in a bearing, HL.  The left end of the feedroll is mounted in
a bearing,  GL.  A torsion spring, J, forces the platen against the
left feedroll bushing, GL, which is then forced against a stop on the
frame.  In this  initial position, the clearance, K, between the
frame stop and the bearing is zero.  The platen gap in this position
is L.

      In an ideal case, a form would be inserted between the feedroll
and the pressure roll.  This would force the feedroll shaft back
causing the left bearing to move back.  The bearing pushes on the
platen causing  the platen to rotate about the platen pivot shaft, D.
The amount the platen moves back should strictly...