Browse Prior Art Database

Digital Tactile Sensor

IP.com Disclosure Number: IPCOM000043599D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Hendriks, F: AUTHOR

Abstract

A digital tactile sensor consists of a piezoelectric transducer that utilizes the resonant frequency to measure the load applied to the system. As shown in Fig. 1, the sensor 10 consists of a piezoelectric bilayered structure 12 which flexes in response to an applied AC voltage (not shown) having a typical frequency of the order of 20 kHz when its length is 1 cm. A block 14 of rigid material is glued to the piezoelectric structure 12 so that the block makes a vibrating motion relative to the surface 16 of the substrate 18, as shown in Fig. 2. Both the block 14 and the surface 16 must have a flatness in which the roughness is less than 1 m inch.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 97% of the total text.

Page 1 of 2

Digital Tactile Sensor

A digital tactile sensor consists of a piezoelectric transducer that utilizes the resonant frequency to measure the load applied to the system. As shown in Fig. 1, the sensor 10 consists of a piezoelectric bilayered structure 12 which flexes in response to an applied AC voltage (not shown) having a typical frequency of the order of 20 kHz when its length is 1 cm. A block 14 of rigid material is glued to the piezoelectric structure 12 so that the block makes a vibrating motion relative to the surface 16 of the substrate 18, as shown in Fig. 2. Both the block 14 and the surface 16 must have a flatness in which the roughness is less than 1 m inch. Whenever the AC drive is on and the block 14 with piezoelectric structure 12 is lightly pressed against the surface 16, a so-called squeeze bearing is established which causes super ambient air pressure in the narrow gap between block 14 and surface 16. Since the spring stiffness of the squeeze bearing is non-linear,
i.e., it becomes stiffer when the gap is decreased, the resonant frequency of the system comprised of the piezoelectric structure 12 and block 14 depends on the load L applied to them. If, by using a feedback technique, the AC voltage driver tracks the resonant frequency of the slider, then the frequency is a measure of the load applied to the system. This feedback principle is particularly simple and inexpensive to implement with piezoelectric transducers.

1

Page 2 of 2

2

[This page con...