Browse Prior Art Database

Touch Board

IP.com Disclosure Number: IPCOM000091559D
Original Publication Date: 1968-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

French, WK: AUTHOR [+3]

Abstract

The device indicates the position of a point touched by a probe on a two-dimensional tablet. A resistive voltage divider network consisting of a series of equal-valued resistors is placed on the two-dimensional board in a sinuous configuration. The resistive network is shown as an integrated circuit consisting of conductive metal deposited on the substrate. The narrow portions have higher resistivity and serve as the resistance elements. The wider area portions 12 are low resistance connections.

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Touch Board

The device indicates the position of a point touched by a probe on a two- dimensional tablet. A resistive voltage divider network consisting of a series of equal-valued resistors is placed on the two-dimensional board in a sinuous configuration. The resistive network is shown as an integrated circuit consisting of conductive metal deposited on the substrate. The narrow portions have higher resistivity and serve as the resistance elements. The wider area portions 12 are low resistance connections.

When a voltage is applied at any point between two resistor elements by probe 14 and signal source 16, the voltage divides and voltages V1 and V2 appear at both ends of the circuit. The relative values of V1 and V2 indicate the position of probe 14 on the tablet in terms of X-Y coordinates. This is because a unique amplitude relation of V1 and V2 is produced for each position of probe 14. The device is not limited to the use of a sinuous configuration. Spirals and other geometries can be employed as long as the X-Y coordinates of areas 12 are established. Probe 14 can inject the signal by either resistance or capacitive coupling. If a capacitance coupling is employed, the capacitance and the related impedance can vary due to the fact that the probe is hand-held. To minimize the impedance variation effect, V1 and V2 can be applied to a summing and dividing network which divides one signal by the sum of the two signals.

An advantage of the circuit, in addition...