US 8,139,039 B2Granted

Selectively erasable electronic writing tablet

AssigneeKent Displays Incorporated

InventorsTod L. Schneider, Erica Montbach, J. William Doane

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Abstract

An electronic writing tablet is composed of one or more layers on which an image is formed and can be selectively erased. One aspect of the invention is a bistable cholesteric writing tablet on which an image is formed while applying writing pressure. The image can be fully erased and new images written on the tablet. In addition, one can selectively erase any or all portions of the written image to restore the original background color. Another aspect of the invention is a multi-color stacked writing tablet in which a color of an image is selected (usually by applying a suitable voltage) while applying writing pressure using an instrument such as an untethered stylus on the surface of the tablet. The writing tablet includes at least two or three stacked layers of bistable cholesteric liquid crystal material. Selected colors can be additively mixed to achieve intermediate colors as desired. The image can be fully erased and new images written on the tablet. In addition, one can selectively erase any or all portions of the written image to restore the original background color.

Claims24

Dependent claims

A selectively erasable electronic writing tablet comprising:

a transparent, flexible writing surface;
electrically conductive layers below said writing surface, adjacent said conductive layers being spaced apart by a gap;
a layer of cholesteric liquid crystal material disposed in said gap, wherein pressure applied to said writing surface decreases said gap;
circuitry including:
a) a full erase function adapted to apply a full erase voltage to said conductive layers placing said liquid crystal layer in an initial planar or focal conic texture that is stable in an absence of an electric field,
b) a write function adapted to form a written portion on said writing tablet during writing conditions, including applying said pressure to said writing surface, wherein said written portion includes a changed focal conic or planar texture different from said initial texture without affecting a texture outside of said written portion;
c) a select erase function adapted to selectively erase said written portion during select erasing conditions, including applying said pressure to an erasing region of said writing surface overlying said written portion, wherein said selectively erasing returns said changed texture to said initial texture without affecting a texture outside of said erasing region;
and
a black or color light absorbing layer located so as to absorb light passing through said liquid crystal layer.

6 more elements

A method of selectively erasing an electronic writing tablet comprising:

providing said writing tablet comprising a transparent, flexible writing surface, electrically conductive layers below said writing surface, adjacent said conductive layers being spaced apart by a gap, and a layer of cholesteric liquid crystal material disposed in said gap, said liquid crystal being in an initial planar or focal conic texture that is stable in an absence of an electric field, wherein pressure applied to said writing surface decreases said gap, and a black or color light absorbing layer located so as to absorb light passing through said liquid crystal layer;
forming a written portion having a texture that is different than said initial texture;
and
selectively erasing said written portion during select erasing conditions, including applying said pressure to an erasing region of said writing surface overlying said written portion, wherein said selectively erasing returns said written portion texture to said initial texture without affecting a texture outside of said erasing region.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 12/220,805Filed 29 Jul 2008 · continuation in part
Priority: 31 Jul 2007
Published: US 2009/0033811 A116 Apr 2009
Granted: 20 Mar 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G02F 1/13718
Characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction…
B43L 1/00
Repeatedly-usable boards or tablets for writing or drawing
G02F 1/13338
Constructional arrangements; Manufacturing methods: input devices, e.g. touch panels
G02F 1/13475
Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two…

Family

Application60/962,625Us provisional application · filed 31 Jul 2007
Application12/152,729Parent of this continuation-in-part · filed 16 May 2008
US 2009/0096942 A1Pre-grant publication · published 16 Apr 2009
US 2009/0033811 A1Published application
US 8,228,301 B2Related patent
US 8,139,039 B2This patent

From the US filing history. Foreign family members aren’t listed.