Browse Prior Art Database

Pressure-Sensitive Cursor Control Keypads

IP.com Disclosure Number: IPCOM000035024D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 3 page(s) / 68K

Publishing Venue

IBM

Related People

Denoix, B: AUTHOR [+4]

Abstract

A technique is described whereby cursor control positioning keys or other keys, as used on a keyboard, can provide analog control signals using several different methods. Discussed are several approaches used in pressure-sensitive cursor controls: Two-Sponge Piezoelectric Key, Surface Acoustic Wave Key, Surface Acoustic Wave Cross Key, Two-Layer Device; and Capacitance/Sponge. Two-Sponge Piezoelectric Key The implementation of the two-sponge piezoelectric key assembly consists of key 10, as shown in the figure, keystem molded unit 11, soft sponge material 12, hard sponge material 13, piezoelectric sensor 14, and holder 15. Holder 15 contains the electrodes for the sensor and attaches to keyboard 16 so that the keys can make contact with circuit 17.

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Pressure-Sensitive Cursor Control Keypads

A technique is described whereby cursor control positioning keys or other keys, as used on a keyboard, can provide analog control signals using several different methods. Discussed are several approaches used in pressure-sensitive cursor controls: Two-Sponge Piezoelectric Key, Surface Acoustic Wave Key, Surface Acoustic Wave Cross Key, Two-Layer Device; and Capacitance/Sponge. Two- Sponge Piezoelectric Key The implementation of the two-sponge piezoelectric key assembly consists of key 10, as shown in the figure, keystem molded unit 11, soft sponge material 12, hard sponge material 13, piezoelectric sensor 14, and holder 15. Holder 15 contains the electrodes for the sensor and attaches to keyboard 16 so that the keys can make contact with circuit 17. A spline (not shown) prevents the key from rotating by matching longitudinal concavity and convexity along two sliding cylinders. Typically, the spline can be a strip of plastic projecting from the inner cylinder and a corresponding linear cut-out in the outer cylinder. When key 10 is depressed, soft sponge material 12 is compressed first. Typically, the sponge can be air-pocketed cleaning-type sponge material, or a polyurethane. In place of sponge material, standard metal springs, or metal saddle-shaped spring washers could be used. In any event, it is important that applied pressure feedback be provided to the user. As sponge material 12 is depressed, key 10 continues down and hard sponge 13 is depressed. A change in relative pressure is sensed by the user so as to give a positive tactile feedback and a feel to the keys that provides a sensory indication of when the key has been turned to an "ON" operation. During normal operation, the user would press the key until the hard sponge is encountered. This would equate to a single standard key press. However, in this concept, the user can elect to press the key against hard sponge material 13 in a controllable analog manner, so as to produce an output at the analog-to- digital converter (ADC) located in circuit 17. The ADC output is then used to control software. When circuit 17 receives the appropriate keystroke, it is in the form of a standard keyboard matrix, such that a key-sensing capability, by means of piezoelectric sensor 14, determines which key has been pressed. The key sense operates when a small signal, equivalent to the output between the soft and hard material movement, is recognized. The key sense sends this standard information to the computer. In addition, the key sense allows the ADC to see the analog level of the voltage. This gives the ADC a reading of how hard the key has been pressed. The voltage is then converted to a six-bit binary number for input to the software controlled systems. In prior art, key technologies were generally binary, either on or off. Typical implementations involved the use of resistive contacts, capacitive, light emitting/detecting diodes, or magnetic...