Browse Prior Art Database

Position Coding for a Pen-On-Paper Device

IP.com Disclosure Number: IPCOM000119891D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 8 page(s) / 249K

Publishing Venue

IBM

Related People

Miessler, MH: AUTHOR [+2]

Abstract

Described is an extension to the Pen-on-Paper Input technology of the preceding article that will enable the pen position within the drawing area to be derived during pen movement. The effective length of basic pen codes is increased from two to three bits. Positional information is encoded into the pattern surface to generate position-dependent code sequences.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 28% of the total text.

Position Coding for a Pen-On-Paper Device

      Described is an extension to the Pen-on-Paper Input
technology of the preceding article that will enable the pen position
within the drawing area to be derived during pen movement.  The
effective length of basic pen codes is increased from two to three
bits.  Positional information is encoded into the pattern surface to
generate position-dependent code sequences.

      The basic technology senses a single pattern that has alternate
reflective and non-reflective stripes of equal width.  The stripe
width is sufficient to enable both sensors on the arm of a fibre
array orthogonal to the stripe to set or reset when the array is
positioned centrally over a stripe.  The arm of the array generates a
Gray code pattern when passed over the drawing surface.  The cyclic
code for left- to-right movement is as follows:
start 00 ___> 01 ___> 11 ___> 10 ___> 00 stop.

      The code cycle comprises four steps.  Each step changes a
single bit in the code, and thus each change in the code represents a
unit of movement.  Each change in code value can also be directly
interpreted to give the direction of movement.  For the basic pen
input device the code is repeated as a two-dimensional pattern over
the whole of the sensing surface, and because of this uniformity no
absolute measure of position is available.  Relative positioning is
available by the accumulation of code transitions to obtain total
movement.  Positioning information requirements vary. Where the pen
input device is to be used as a mouse replacement, the basic pen (see
preceding article) capability is adequate.  Where data is to be
entered into specific regions of the input area, such as in a
form-filling application, then the positional information fed to the
application must indicate which box or rectangle of the form is
currently being filled, 8 'X' and 8 'Y' position codes would be
adequate for most forms.  Free Form input, such as letter writing,
may be seen as an extended example of form filling or more like
interactive graphics which requires more accurate positional
information.  The code patterns proposed here extend the simple
cyclic code to enable positional information to be encoded within the
pattern. The proposed extended codes contain movement direction and
position information within the code.

      A set of code types is proposed that can be used in
combinations that enable positional information to be encoded into
the sense pattern.  When these codes are used, then the decoder must
be enhanced to separate and extract the individual channels of data
that are generated as the pen moves.  As with the basic pattern, each
code change represents a unit of movement and can be interpreted to
give the direction of movement.  The codes described also contain
position information that can be extracted by the decoder.

      The pen (Fig. 1) is similar to the basic pen input device shown
in the previous ar...