Browse Prior Art Database

Work-Around for Epson GQ-3500 Printer Vertical Spacing Support

IP.com Disclosure Number: IPCOM000101817D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 103K

Publishing Venue

IBM

Related People

Carter, KE: AUTHOR [+2]

Abstract

The GQ 3500 printer could not be supported by DisplayWrite* due to a printer spacing problem encountered when using the printer's Vertical Line Spacing command.

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

Work-Around for Epson GQ-3500 Printer Vertical Spacing Support

       The GQ 3500 printer could not be supported by
DisplayWrite* due to a printer spacing problem encountered when using
the printer's Vertical Line Spacing command.

      A printer may support a Vertical Line Spacing (VLS), a Set 6
Lines Per Inch (LPI), and/or a Set 8 LPI line spacing command.  These
commands allow an application to vertically position printed data on
the paper.  Specifically, a VLS command allows an application to
specify a value, in printer units, that causes the printer to move
down the paper by the specified printer units.  An application can
specify any value supported by the printer's VLS command.

      The generic print support in DisplayWrite (DW) products has
always used a printer's line spacing commands to position the paper
as close as possible to the line spacing specified in a DW document
and to position the printer as close as possible to the first writing
line of each page in a document.  DW uses the most effective
combination of line spacing commands and values supported by a
printer to accurately position the paper.  If a vertical distance
exceeds the maximum value of a printer's VLS command, DW will output
multiple VLS commands to move the distance.

      This method assumes that all printers which support line
spacing commands can support multiple combinations of the commands,
independent of the order of data, other controls, or other vertical
spacing commands.  This assumption was correct, until support for the
Epson GQ 3500 printer was initiated.

      The Epson GQ 3500 printer does not operate correctly when
processing consecutive VLS commands of different line spacing values.
Rather, the printer requires the application to send a blank line
between VLS commands with different values.  For example, multiple
lines can be printed at 6 lines per inch, or at 8 lines per inch
using VLS commands with different line spacing values.  However, when
changing between 6 and 8 lines per inch, there must be at least one
blank line between VLS commands.

      This meant that the printer did not operate correctly when DW
positioned to the first line of a page or whenever the line spacing
changed between consecutive lines of text in a document.  This was
not acceptable.  Sending a blank line between VLS commands with
different values was also not acceptable since doing so produced
unwanted blank lines in the user's output and required special DW
code to implement.

      In order to explain the solution, the concept of a Printer
Function Table (PFT) Variable control needs to be defin...