US5594568A — LCD with a pair of retardation films on one side …

Claim 1

Independent Claim 161 words

A normally white liquid crystal display comprising: a rear, light-entrance polarizer having a transmission axis oriented in a first direction; a front, light-exit polarizer having a transmission axis oriented in a second direction with respect to said first direction so as to define a normally white display; first and second positively birefringent uniaxial retardation films both disposed between a twisted nematic liquid crystal layer and one of: (i) said rear, light-entrance polarizer; and (ii) said front, light-exit polarizer; wherein said liquid crystal layer in the off state twists at least one normally incident visible wavelength of light less than about 110° as it passes therethrough, and said first and second uniaxial retardation films each have retardation values of from about 80-200 nm; and wherein the transmission axes of said polarizers and optical axes of said retardation films are so arranged each with respect to the others so as to achieve high contrast ratios over a large range of predetermined viewing angles.

Claim 2

Dependent Claim 161 words

A normally white liquid crystal display comprising: a rear, light-entrance polarizer having a transmission axis oriented in a first direction; a front, light-exit polarizer having a transmission axis oriented in a second direction with respect to said first direction so as to define a normally white display; first and second positively birefringent uniaxial retardation films both disposed between a twisted nematic liquid crystal layer and one of: (i) said rear, light-entrance polarizer; and (ii) said front, light-exit polarizer; wherein said liquid crystal layer in the off state twists at least one normally incident visible wavelength of light less than about 110° as it passes therethrough, and said first and second uniaxial retardation films each have retardation values of from about 80-200 nm; and wherein the transmission axes of said polarizers and optical axes of said retardation films are so arranged each with respect to the others so as to achieve high contrast ratios over a large range of predetermined viewing angles.

Claim 3

Dependent Claim 21 words

The display of claim 1, wherein said first and second retardation films each have retardation values of from about 100-170 nm.

Claim 4

Dependent Claim 21 words

The display of claim 2, wherein said first and second retardation films each have retardation values of from about 120-160 nm.

Claim 5

Dependent Claim 26 words

The display of claim 2, wherein said liquid crystal layer is from about 4.8-6.5 μm thick with a birefringence of from about 0.075-0.095 at room temperature.

Claim 6

Dependent Claim 67 words

The display of claim 4, wherein said liquid crystal layer is sandwiched between rear and front orientation means for aligning molecules of said liquid crystal material, said rear orientation means having a buffing or orientation direction substantially parallel to the transmission axis of said rear polarizer, and said front orientation means having a buffing or orientation direction substantially parallel to the transmission axis of said front polarizer.

Claim 7

Dependent Claim 38 words

The display of claim 4, wherein said display has a white light contrast ratio of at least about 10:1 when about a 6 volt driving voltage is applied thereto at viewing angles of about 0° vertical, ±50° horizontal.

Claim 8

Dependent Claim 61 words

The display of claim 4, wherein certain contrast ratio contours of said display extend further in one horizontal direction than the other such that said display has about a 10:1 contrast ratio when about a 6 volt driving voltage is applied thereto at a viewing angle of one of about: (i) 0° vertical, 55° horizontal; and (ii) 0° vertical, -55° horizontal.

Claim 9

Dependent Claim 26 words

The display of claim 4, wherein an angle of from about 80°-100° is defined between the respective optical axes of said first and second retardation films.

Claim 10

Dependent Claim 66 words

The display of claim 8, wherein an angle of from about 85°-95° is defined between said optical axes of said first and second retardation films such that said optical axis of said first retardation film is substantially parallel to the transmission axis of said front polarizer and said optical axis of said second retardation film is substantially parallel to the transmission axis of said rear polarizer.

Claim 11

Dependent Claim 165 words

A normally white liquid crystal display comprising: a rear, light-entrance polarizer having a transmission axis oriented in a first direction; a front, light-exit polarizer having a transmission axis oriented in a second direction wherein said first and second directions are oriented so as to define a normally white display; first and second biaxial retardation films both disposed between a twisted nematic liquid crystal layer and one of said rear and front polarizers, wherein said liquid crystal layer in the off state twists at least one wavelength of normally incident visible light at least about 85° as it passes therethrough; and wherein said first and second biaxial retardation films each have the following retardation values: d·Δn.sub.ZX =from about -100 to -200 nm d·Δn.sub.ZY =from about -10 to -100 nm wherein n X >n Y >n Z and "d" is the thickness of the film such that the viewing zone of said display has high contrast ratios and reduced inversion throughout an enlarged range of viewing angles.

Claim 12

Dependent Claim 165 words

A normally white liquid crystal display comprising: a rear, light-entrance polarizer having a transmission axis oriented in a first direction; a front, light-exit polarizer having a transmission axis oriented in a second direction wherein said first and second directions are oriented so as to define a normally white display; first and second biaxial retardation films both disposed between a twisted nematic liquid crystal layer and one of said rear and front polarizers, wherein said liquid crystal layer in the off state twists at least one wavelength of normally incident visible light at least about 85° as it passes therethrough; and wherein said first and second biaxial retardation films each have the following retardation values: d·Δn.sub.ZX =from about -100 to -200 nm d·Δn.sub.ZY =from about -10 to -100 nm wherein n X >n Y >n Z and "d" is the thickness of the film such that the viewing zone of said display has high contrast ratios and reduced inversion throughout an enlarged range of viewing angles.

Claim 13

Dependent Claim 62 words

The display of claim 10, wherein the optical axis having the largest index of refraction n X of the biaxial retardation film disposed closest to said liquid crystal layer is aligned substantially parallel to the buffing or orientation direction of an adjacent orientation film, said orientation film being disposed between said liquid crystal layer and said first and second biaxial retardation films.

Claim 14

Dependent Claim 29 words

The display of claim 11, wherein said buffing or orientation direction is substantially parallel to the polarizer transmission axis disposed on the same side of said liquid crystal layer.

Claim 15

Dependent Claim 24 words

The display of claim 11, wherein said first and second retardation films have retardation values d·Δn ZX of from about -140 to -180 nm.

Claim 16

Dependent Claim 33 words

The display of claim 10, wherein said first and second retardation films each have the following retardation values: d·Δn.sub.ZX =from about -120 to -180 nm d·Δn.sub.ZY =from about -40 to -80 nm. 15.

Claim 17

Dependent Claim 179 words

A normally white twisted nematic liquid crystal display comprising: a plurality of pixels, each said pixel including electrode means and a twisted nematic liquid crystal layer for twisting at least one normally incident visible wavelength of light passing therethrough from about 80° to 100° when the liquid crystal layer is in the off state; a rear light-entrance polarizer having a transmission axis oriented in a first direction; a front, light-exit polarizer or analyzer having a transmission axis oriented in a second direction with respect to said first direction thereby defining a twisted nematic normally white display; a first retardation film; a second retardation film; and wherein the transmission axes of said rear and front polarizers and the optical axes of said first and second retardation films are so arranged with respect to the others so as to achieve a white light contrast ratio of at least about 10:1 over a horizontal angular span, at a predetermined vertical angle, of at least about 120° and over a vertical angular span of greater than about 50° at a predetermined horizontal angle.

Claim 18

Dependent Claim 179 words

A normally white twisted nematic liquid crystal display comprising: a plurality of pixels, each said pixel including electrode means and a twisted nematic liquid crystal layer for twisting at least one normally incident visible wavelength of light passing therethrough from about 80° to 100° when the liquid crystal layer is in the off state; a rear light-entrance polarizer having a transmission axis oriented in a first direction; a front, light-exit polarizer or analyzer having a transmission axis oriented in a second direction with respect to said first direction thereby defining a twisted nematic normally white display; a first retardation film; a second retardation film; and wherein the transmission axes of said rear and front polarizers and the optical axes of said first and second retardation films are so arranged with respect to the others so as to achieve a white light contrast ratio of at least about 10:1 over a horizontal angular span, at a predetermined vertical angle, of at least about 120° and over a vertical angular span of greater than about 50° at a predetermined horizontal angle.

Claim 19

Dependent Claim 47 words

The display of claim 15, wherein said display has a contrast ratio of at least about 10:1 over a horizontal angular span of at least about 120° and over a vertical angular span of greater than about 60° when about 6.0 volts is applied to said display.

Claim 20

Dependent Claim 38 words

The display of claim 16, wherein said display has a contrast ratio of at least about 30:1 over a horizontal angular span of at least about 80° and over a vertical angular span of greater than about 30°.

Claim 21

Dependent Claim 23 words

The display of claim 15, wherein said first and second retardation films have retardation values, positive or negative, of from about 80-200 nm.

Claim 22

Dependent Claim 22 words

The display of claim 15, wherein said first and second retardation films are on the same side of said liquid crystal layer.

Claim 23

Dependent Claim 128 words

A normally white twisted nematic liquid crystal display comprising: a twisted nematic liquid crystal layer which twists at least one normally incident visible wavelength of light from about 80°-100° as it passes therethrough when the liquid crystal is in the off state; electrode means for applying voltage to said liquid crystal layer so as to selectively display image data to a viewer; a first negative retardation film having a retardation value of from about -80 to -200 nm; a second negative retardation film having a retardation value of from about -80 to -200 nm; and wherein the optical axes of said first and second negative retardation films are oriented relative to one another so as to achieve a high contrast ratio over a predetermined range of viewing angles.

Claim 24

Dependent Claim 128 words

A normally white twisted nematic liquid crystal display comprising: a twisted nematic liquid crystal layer which twists at least one normally incident visible wavelength of light from about 80°-100° as it passes therethrough when the liquid crystal is in the off state; electrode means for applying voltage to said liquid crystal layer so as to selectively display image data to a viewer; a first negative retardation film having a retardation value of from about -80 to -200 nm; a second negative retardation film having a retardation value of from about -80 to -200 nm; and wherein the optical axes of said first and second negative retardation films are oriented relative to one another so as to achieve a high contrast ratio over a predetermined range of viewing angles.

Claim 25

Dependent Claim 26 words

The display of claim 20, wherein the optical axes of each of said first and second retardation films are substantially parallel to the normal viewing axis.

Claim 26

Dependent Claim 46 words

The display of claim 20, wherein the display has a contrast ratio of at least about 10:1 over a horizontal angular span of at least about 120° and a vertical angular span of greater than about 60° when about 6.0 volts is applied to the display.

Claim 27

Dependent Claim 31 words

The display of claim 20, wherein the indices of refraction of each of said first and second negative retarders are characterized by the equations: d·.sup.Δ n.sub.ZX =d·.sup.Δ n.sub.ZY and n.sub.X >n.sub.Z.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-01-14	2000-07-15	2001-01-14	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-01-14	2004-07-15	2005-01-14	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-01-14	2008-07-15	2009-01-14	$7700.00	Window Closed / Lapsed

LCD with a pair of retardation films on one side of normally white liquid crystal layer

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