Browse Prior Art Database

Hold-Down Spring Orienting Device for Dot Matrix Printhead

IP.com Disclosure Number: IPCOM000099907D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 112K

Publishing Venue

IBM

Related People

Barenboim, M: AUTHOR

Abstract

This article describes a device to accurately orient a hold-down spring which spring-loads print wires in a dot matrix printhead by sensing a tiny notch on the spring rim with a linear variable differential transformer and rotating the spring to the proper location.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Hold-Down Spring Orienting Device for Dot Matrix Printhead

       This article describes a device to accurately orient a
hold-down spring which spring-loads print wires in a dot matrix
printhead by sensing a tiny notch on the spring rim with a linear
variable differential transformer and rotating the spring to the
proper location.

      Fig. 1 is an exploded perspective view of a dot matrix
printhead showing the hold-down spring which holds armature arms
against the magnet sub-assembly.  The armature arms are spring-loaded
by the hold- down spring within the printhead. The hold-down spring
has two features, slot A and hole B, which are designed for proper
alignment of the spring. These two features (slot A and hole B) must
not be mixed in the printhead assembly process; if this happens, the
printhead will malfunction.  The proper orientation of the hold-down
spring within the printhead is therefore critical.

      Hold-down springs are manually loaded into totes (not shown) at
a distribution center and via a tote conveyor are transferred to the
assembly line.  Due to the spring's symmetry, they are often loaded
into the tote the wrong way (hole is presented for pick-up instead of
slot).  In order to check, verify, and correct the position of the
spring, prior to its assembly into the printhead, the
spring-orienting device disclosed herein was designed.

      The hold-down spring-orienting device disclosed herein is shown
in Fig. 2.  It consists of two major components: the
holding/correcting and the checking mechanisms.  The assembly robot
first picks up the spring from the tote and places it onto the
holding/correcting mechanism.  The spring is then clamped by two
half-circle shaped jaws 1, activated by an air-cylinder 2.  In order
to facilitate the flatness of the spring's rim, the jaws 1 are
prov...