Browse Prior Art Database

TRIANGULATION SCAN FOR INTERACTIVE DIGIT

IP.com Disclosure Number: IPCOM000046072D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 44K

Publishing Venue

IBM

Related People

Criscimagna, TN: AUTHOR [+2]

Abstract

In plasma display systems, one desirable enhancement is a low cost data tablet which utilizes a finger as a stylus for entering or identifying information on the display. One of the methods for identifying the coordinate location of a finger placed on a data tablet associated with a plasma display device is shown in the IBM Technical Disclosure Bul -letin 23, 7B, 3287-88 (December 1980). An alternative solution using a triangulation identification system including a microprocessor and a detection algorithm is described below.

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TRIANGULATION SCAN FOR INTERACTIVE DIGIT

In plasma display systems, one desirable enhancement is a low cost data tablet which utilizes a finger as a stylus for entering or identifying information on the display. One of the methods for identifying the coordinate location of a finger placed on a data tablet associated with a plasma display device is shown in the IBM Technical Disclosure Bul -letin 23, 7B, 3287-88 (December 1980). An alternative solution using a triangulation identification system including a microprocessor and a detection algorithm is described below.

Fig. 1 illustrates a top view of a data tablet including four sensors labeled A, B, C and D. A series of illuminated cells or groups of cells in a plasma panel may be sequentially turned ON one cell/group at a time, and then erased, thereby forming a vertical scan of light on both sides of the panel, as shown in Fig. 1. Two vertically oriented lens prism frames 3, 5 are aligned with the vertical borders of the panel beyond the panel viewing area. The frames 3, 5 function to redirect the cell/group light scan to the opposite side of the panel, slightly above the horizontal plane of the panel to the four photosensors located as shown in Fig. 1. The panel is thus divided into four quadrants labeled AB, BC, CD and AD, whereby every area of the panel has two associated sensors required for triangulation.

A front view of the panel with its associated prism lenses 3, 5 and sensors A, B, C, D and exemplary light rays to the sensors is illustrated in Fig. 2. When a finger or any pencil-like pointer is placed on the face of the gas panel, it will block the light from one or both of the scanning cells/groups. By knowing which cell/group light output was blocked, a line or an angle can be established between the associated cell/group and the sensors. If this is done by two separate scans, one on each side of the panel, then two lines or angles can be established and, by triangulation, the loca...