Browse Prior Art Database

Software Interface for a Paper Measuring and Print Gap Setting System

IP.com Disclosure Number: IPCOM000110786D
Original Publication Date: 1994-Jan-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 6 page(s) / 149K

Publishing Venue

IBM

Related People

Brown, MJ: AUTHOR [+2]

Abstract

Disclosed is a software interface for an integrated paper-thickness-measuring and print-head-gap setting system. The design encapsulates the measuring and gap setting functions and provides a simple, easy to use interface. The encapsulated functions allow for major changes to occur in one function without impacting the others.

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This is the abbreviated version, containing approximately 34% of the total text.

Software Interface for a Paper Measuring and Print Gap Setting System

      Disclosed is a software interface for an integrated
paper-thickness-measuring and print-head-gap setting system.  The
design encapsulates the measuring and gap setting functions and
provides a simple, easy to use interface.  The encapsulated functions
allow for major changes to occur in one function without impacting
the others.

      The interface would typically operate on a printer card that
has a MASTER/SLAVE microprocessor system.  However, the architecture
can still be used in a single processor system.

      Fig. 1 shows the two microprocessors used.  The MASTER
processor controls the overall printer and knows when the paper
thickness needs to be measured.  In addition, the MASTER sets the
print head gap when needed.  As shown, the two processors communicate
through a byte wide, bidirectional interface.  The slave paces the
data from the master by responding to each byte sent.  The master
cannot send the next byte until a response is received to the
previous byte.

      The SLAVE microprocessor directly controls the Paper Thickness
and Print Gap Setting Mechanism which consists of a stepper motor,
home sensor, print head and mechanical gearing/actuation (Fig. 2).

      The interface contains a MOVE command that allows the master to
set the appropriate print head gap.  Measuring of the paper thickness
involves a multi-step process.  The MEASURE PAPER, MEASURE PLATEN AND
QUERY commands combine to provide the paper thickness measurement.

A typical use of the interface by the MASTER follows:

1.  Without paper in the machine, the master sends the PLATEN MEASURE
    command to measure the distance between the print head and the
    platen starting at the HOME sensor.  The measurement includes any
    mechanical give in the system.  The value obtained from the
    measure is called the PLATEN FLEX distance.

2.  The query measurement commands are sent (low and high byte) to
    retrieve the platen flex measurement and is saved in memory for
    later use.

3.  With paper in the machine, the master sends the PAPER MEASURE
    command to measure the distance between the print head and paper
    starting at the HOME sensor.  The measurement includes the
    mechanical give in the system and is called the PAPER FLEX
    distance.

         NOTE:  The paper and platen measurement commands are
    different
         because their measurement algorithms are different.

4.  The query measurement commands are sent (low and high byte) to
    retrieve the paper flex distance.

5.  The paper flex distance subtracted from the platen flex distance
    yields the paper thickness.

6.  Set the proper print head gap (based on the paper thickness) with
    the MOVE command.

         NOTE:  The absolute distance between the print head and
    platen from
         the HOME...