Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Capacitive Tablet with Coded Drivers to Eliminate Triangular Plates

IP.com Disclosure Number: IPCOM000052240D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Dym, H: AUTHOR [+2]

Abstract

A digitizing capacitive tablet has groups of wires in the x dimension and in the y dimension, as in U. S. Patent 3,999,012. The location of a pen (or stylus or cursor) on the tablet is defined for each dimension by the identifying number of the group of wires and by the identifying number of an adjacent wire within the group. As in the tablet of the patent, a set of driver transistors each drive one wire in each group of wires and the location of the pen within a group can be found by shifting the pattern of activation of the wires until the wires to one side of the pen are activated and wires to the other side are not activated.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Capacitive Tablet with Coded Drivers to Eliminate Triangular Plates

A digitizing capacitive tablet has groups of wires in the x dimension and in the y dimension, as in U. S. Patent 3,999,012. The location of a pen (or stylus or cursor) on the tablet is defined for each dimension by the identifying number of the group of wires and by the identifying number of an adjacent wire within the group. As in the tablet of the patent, a set of driver transistors each drive one wire in each group of wires and the location of the pen within a group can be found by shifting the pattern of activation of the wires until the wires to one side of the pen are activated and wires to the other side are not activated. In the tablet of this article, the connection from each wire of a group to one of the driver transistors is arranged in a pattern that varies from group to group and permits the group location to be identified by a sequence for activating the wires. The tablet avoids the need for the triangular plates that are used in the patent to identify the group. Tablet Group Coding One assignment of wires to groups is illustrated by the following table: wire 1 2 3 4....2i-1 2i...24 24 group 0 A1 B1 A2 B2...Ai Bi...A12 B12 group 1 A1 B2 A2 B3...Ai Bi+1.A12 B1 group N A1 B1+N A2 B2+N.Ai Bi+N.A12 BN

The top row, labeled "wire," identifies the 24 wires of each group in their ordinary sequence, as in the patent. The left-hand column identifies the groups of 24 wires. The 24 driver transistors are each identified by a letter, A or B, and a number 1 through 12.

An entry such as A1 identifies the particular one of the 24 driver transistors that is connected to the wire of the column heading in the group of the row heading. In the pattern of the table, driver A1 is connected to the first wire of each group. Similarly, driver transistor A2 is connected to each wire 3, A3 is connected to each wire 5, and so on as indicated by the connection of the generalized d...