US4630040A — Variable color electrooptic display

Claim 1

Independent Claim 149 words

A method for creating selectable indicia of a first color and a second background color comprising the steps of: polarizing light emitted from a light source by means of a first polarizer; phase retarding selected portions of the polarized light exiting the first polarizer by applying a transverse electric field to selected areas on a substantially transparent uniaxial ferroelectric ceramic plate disposed in optical series with the first polarizer, said selected areas defining said indicia; polarizing the light which exits from the ferroelectric ceramic plate by means of a second polarizer; and providing additional phase retardation to light which exits from the first polarizer before said light strikes the second polarizer to provide a color bias, the additional phase retardation controlling the background color of the display and the combination of said additional phase retardation and the selected phase retarded portions of light controlling the color of the indicia.

Claim 2

Independent Claim 149 words

A method for creating selectable indicia of a first color and a second background color comprising the steps of: polarizing light emitted from a light source by means of a first polarizer; phase retarding selected portions of the polarized light exiting the first polarizer by applying a transverse electric field to selected areas on a substantially transparent uniaxial ferroelectric ceramic plate disposed in optical series with the first polarizer, said selected areas defining said indicia; polarizing the light which exits from the ferroelectric ceramic plate by means of a second polarizer; and providing additional phase retardation to light which exits from the first polarizer before said light strikes the second polarizer to provide a color bias, the additional phase retardation controlling the background color of the display and the combination of said additional phase retardation and the selected phase retarded portions of light controlling the color of the indicia.

Claim 3

Dependent Claim 51 words

The method according to claim 1 further comprising the step of selectively varying said additional phase retardation by controlling an electric field induced in a second ferroelectric ceramic plate disposed in optical series between the first and second polarizers, varying said additional phase retardation causing corresponding variations of the background color.

Claim 4

Dependent Claim 34 words

The method according to claim 1 wherein the polarization provided by the second polarizer further comprises the step of cross polarizing light striking the second polarizer relative to the polarization of the first polarizer.

Claim 5

Dependent Claim 25 words

The method according to claim 1 wherein the polarization provided by the second polarizer has the same polarization orientation as that of the first polarizer.

Claim 6

Dependent Claim 14 words

The method according to claim 1 wherein said second background color is not black.

Claim 7

Dependent Claim 14 words

The method according to claim 3 wherein said second background color is not black.

Claim 8

Dependent Claim 23 words

The method according to claim 1 wherein said second background color is not the color of the light emitted from said light source.

Claim 9

Dependent Claim 23 words

The method according to claim 4 wherein said second background color is not the color of the light emitted from said light source.

Claim 10

Dependent Claim 29 words

The method according to claim 1 wherein said step of providing additional phase retardation comprises providing additional phase retardation to all light traveling between said first and second polarizers.

Claim 11

Dependent Claim 166 words

An electrooptic display having selectable indicia of a first color and a background of a second color different from the first color comprising: a first and second polarizer; a substantially transparent uniaxial ferroelectric ceramic element having a first and second surface, and disposed between said first and second polarizers; means in addition to said element disposed between said first and second polarizers for providing spectrally selective phase retardation; and means for selectively inducing an electrical field at selectable areas on at least one of the first and second surfaces of said element, said electric field being transverse to the optical axis of the display and having a magnitude sufficient to cause spectrally selective phase retardation, said areas defining the indicia to be displayed, the phase retardation provided by said means for providing spectrally selective phase retardation defines said second background color, the cumulative phase retardation due to said induced field and said means for providing spectrally selective phase retardation defining said first color of the indicia.

Claim 12

Dependent Claim 166 words

An electrooptic display having selectable indicia of a first color and a background of a second color different from the first color comprising: a first and second polarizer; a substantially transparent uniaxial ferroelectric ceramic element having a first and second surface, and disposed between said first and second polarizers; means in addition to said element disposed between said first and second polarizers for providing spectrally selective phase retardation; and means for selectively inducing an electrical field at selectable areas on at least one of the first and second surfaces of said element, said electric field being transverse to the optical axis of the display and having a magnitude sufficient to cause spectrally selective phase retardation, said areas defining the indicia to be displayed, the phase retardation provided by said means for providing spectrally selective phase retardation defines said second background color, the cumulative phase retardation due to said induced field and said means for providing spectrally selective phase retardation defining said first color of the indicia.

Claim 13

Dependent Claim 13 words

The display according to claim 10 wherein said ceramic element consists of PLZT.

Claim 14

Dependent Claim 20 words

The display according to claim 11 wherein said PLZT ceramic element is a non-memory type and has large grain size.

Claim 15

Dependent Claim 19 words

The display according to claim 10 wherein said means for providing spectrally selective phase retardation comprises a wave plate.

Claim 16

Dependent Claim 35 words

The display according to claim 10 wherein said means for providing spectrally selective phase retardation comprises means for continuously varying the wavelength at which the phase retardation occurs to produce a continuously variable background color.

Claim 17

Dependent Claim 60 words

The display according to claim 14 wherein said varying means comprises another substantially transparent uniaxial ferroelectric ceramic element and means for inducing a variable electric field transverse to the optical axis of the display, the wavelength of the phase retardation caused by the eletric field induced in said another ceramic element varying with the magitude of the induced electric field.

Claim 18

Dependent Claim 46 words

The display according to claim 10 wherein said inducing means comprises a first and second set of electrodes disposed on said first and second surface of said ceramic element, respectively, and means for applying voltage to certain electrodes in said first and second sets of electrodes.

Claim 19

Dependent Claim 110 words

The display according to claim 16 wherein said first set of electrodes are perpendicular to said second set of electrodes so that said first set of electrodes induces an electric field that is perpendicular to the electric field induced by said second set of electrodes, the electric field induced by said first set of electrodes producing a first phase retardation which results in one color of indicia and the electric field induced by said second set of electrodes producing a second phase retardation which results in another color of indicia different from said one color whereby said first color of the indicia is selectable between said one and another color.

Claim 20

Dependent Claim 34 words

The color display according to claim 16 wherein said first polarizer has a first polarization vector and said second polarizer has a second polarization vector which is substantially 90° relative to said first vector.

Claim 21

Dependent Claim 29 words

The display according to claim 10 where said first and second polarizers have first and second polarization vectors respectively, said first vector being substantially parallel to said second vector.

Claim 22

Dependent Claim 18 words

The color display according to claim 16 wherein said first and second set of electrodes are substantially transparent.

Claim 23

Dependent Claim 36 words

The color display according to claim 10 further comprising a third polarizer in optical series with said second polarizer, and another phase retardation means disposed between said second and third polarizers for providing additional phase retardation.

Claim 24

Dependent Claim 52 words

The color display according to claim 21 wherein said third polarizer has a third polarization vector which is oriented substantially 90° relative to the second polarization vector of said second polarizer, whereby said second and third polarizers and said retardation means defines an integral light modulator in optical series with said element.

Claim 25

Dependent Claim 25 words

The color display according to claim 10 further comprising a source of substantially polychromatic light disposed adjacent said first polarizer thereby defining a transmissive-type display.

Claim 26

Dependent Claim 54 words

The color display according to claim 23 further comprising a half-silvered plate disposed between said light source and said first polarizer for permitting a portion of light from said light source to pass therethrough and for reflecting a portion of ambient light entering the front of the display thereby defining a transflective-type of display.

Claim 27

Dependent Claim 26 words

The color display according to claim 10 further comprising a reflection plate disposed adjacent said first polarizer for reflecting light which passes through said first polarizer.

Claim 28

Dependent Claim 43 words

The color display according to claim 10 further comprising a source of light disposed to illuminate the surface of said first polarizer opposite said element, a viewing screen, and a lens means for directing light exiting said second polarizer onto said viewing screen.

Claim 29

Dependent Claim 20 words

The color display according to claim 26 wherein said viewing screen comprises a substantially transparent plate of ferroelectric ceramic material.

Claim 30

Dependent Claim 18 words

The color display according to claim 27 wherein said plate has an index of refraction greater than two.

Claim 31

Dependent Claim 16 words

The color display according to claim 28 wherein said plate is made of a PLZT material.

Claim 32

Dependent Claim 13 words

The display according to claim 10 wherein said second color is not black.

Claim 33

Dependent Claim 13 words

The display according to claim 18 wherein said second color is not black.

Claim 34

Dependent Claim 18 words

The display according to claim 23 wherein said second color is not the color of said polychromatic light.

Claim 35

Dependent Claim 23 words

The display according to claim 10 wherein said providing means provides phase retardation to all light traveling between said first and second polarizers.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-12-15	1990-06-16	1990-12-16	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-12-15	1994-06-16	1994-12-16	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-12-15	1998-06-16	1998-12-16	$7700.00	Window Closed / Lapsed

Variable color electrooptic display

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