Education and demonstration – Means for demonstrating apparatus – product – or surface... – Chalkboard or equivalent means having easily erasable surface
Patent
1988-09-01
1990-06-05
Coven, Edward M.
Education and demonstration
Means for demonstrating apparatus, product, or surface...
Chalkboard or equivalent means having easily erasable surface
340712, 310311, B43L 100
Patent
active
049310194
ABSTRACT:
An electrostatic image display apparatus which uses piezoelectric film to enable a user to form images on a screen. The apparatus is contained within a housing. Supported within the housing is a common electrode. A layer of piezoelectric film is separated a distance from the common electrode by a suspension medium. The suspension medium contains electrially charged pigmented particles, the color of which contrasts with the color of the suspension medium. The housing has an opening for applying localized pressure to one surface of the piezoelectric film. In addition, the apparatus has a source for energizing the common electrode to a preselected electric potential. By applying a force or infrared energy to an area of the piezoelectric film a charge accumules on the inner surface of the film, directly under the point of application of the force. This charge attracts the electrically charged pigmented particles in the suspension medium which are visible through the film and create an image display.
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Coven Edward M.
Pennwalt Corporation
Szczepanik Valerie
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