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Thin Film Piezoelectric Vibrator Panel

IP.com Disclosure Number: IPCOM000121246D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 126K

Publishing Venue

IBM

Related People

Dana, SS: AUTHOR [+5]

Abstract

Disclosed is a method whereby a panel which vibrates in a two-dimensional plane can transmit the outlines of a picture to a blind person or the representation of sound to a deaf person.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 47% of the total text.

Thin Film Piezoelectric Vibrator Panel

      Disclosed is a method whereby a panel which vibrates in a
two-dimensional plane can transmit the outlines of a picture to a
blind person or the representation of sound to a deaf person.

      Programs exist to translate character strings in a computer to
spoken words.  However, blind people cannot "see" pictures on a TV
screen or computer output screen.

      Spoken language can be translated to written forms using
various computer speech recognition algorithms. However, there is
some delay, and a deaf person needs to read the lips of the speaker
and cannot take his eyes off the lips to read a computer terminal.

      The blind person could follow the outlines on a computer screen
with his fingers, and the deaf person could wear a planar transducer,
for example, on his back.  The computer-generated output, translated
into a suitable form, would be a great aid to the lip-reading person.

      Recent research in large-scale amorphous silicon display panels
makes it possible to put many transistors on a flat panel combined
with recent advances in piezoelectric thin film deposition, makes the
construction of such panels feasible.  Each point on the amorphous
silicon is addressed by a "word" line and "bit" line combination, and
can be programmed to provide an oscillating voltage to a
piezoelectric film for a determined time.  The response of humans to
vibration is maximum for a frequency of 250 Hz, which is near to the
ordinary TV refresh rate of 30 Hz. Local oscillators could be turned
on and off by the two-dimensional array of transistors.

      The sensitivity for an average person at 250 Hz is 10E-7 watts
at the receptor.  In terms of ductile sensitivity, this corresponds
to 0.1 um displacement for a tip 6 mm in diameter.  The threshold is
3 dB (dB = 20 * log (Amplitude output / Amplitude input)).

      The amplitude of vibration is independent of the film
thickness:  The relative displacement in the vertical direction (33,
i.e., perpendicular to the film surface) is given by:
   (D1)/1 = d33 * E Since E = V/1, the displacement is D1 = d33
* V. The order of magnitude of the amplitude versus voltage is 10 o
per volt.

      Low-cost active matrix addressing has been used for several
years to fabricate thin film transistor liquid crystal displays
(TFT/LCDs).  In this approach each element of the two-dimensional
array consists of an access transistor and a storage capacitor.
Horizontal lines are used to bias all of the transistors along that
row "On," vertical lines are used to supply different data voltages
to each element along the row, this voltage is stored across the
storage capacitor at that element.  The array is refreshed one row at
a time, the rows that are not being written hold the voltage that was
written across the storage capacitor until they are refreshed.

      Active matrix addressing works well with transducers that
respond to cha...