Negative optical compensator tilted in respect to liquid crystal cell for liquid crystal display

• US 5,986,733 A
• Filed: 04/30/1993
• Issued: 11/16/1999
• Est. Priority Date: 04/30/1993
• Status: Expired due to Term

• Current Assignee: Teledyne Scientific & Imaging, LLC (Teledyne Technologies Incorporated)
• Original Assignee: Rockwell International Corporation
• Inventors: Taber, Donald B., Gunning, William J. III, Winker, Bruce K.
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US08/056,265
• Time in Patent Office: 2,391 Days
• Field of Search: 359/73, 349/119, 349/121, 349/120, 349/84, 349/118, 349/117
• US Class Current: 349/120
• CPC Class Codes: G02F 1/133632 with refractive index ellipsoid inclined relative to the LC-layer surface
• CPC Class Codes: G02F 1/1396 the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell G02F1/141 takes precedence
• CPC Class Codes: G02F 1/1397 the twist being substantially higher than 90°, e.g. STN-, SBE-, OMI-LC cells
• CPC Class Codes: G02F 2413/14 Negative birefingence

Abstract

A normally white liquid crystal display includes polarizer and analyzer layers having perpendicular absorbing axes. A liquid crystal layer is disposed between the polarizer layer and the analyzer layer, with its director exhibiting an azimuthal twist through the layer. First and second electrodes are proximate to first and second major surfaces of the liquid crystal layer. A first negatively birefringent compensator layer, oriented with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state, is disposed between the polarizer layer and the liquid crystal layer. A second negatively birefringent compensator layer, with a birefringence substantially the same as the birefringence of the first compensator layer and oriented with its optical axis substantially parallel to the optical axis of the first compensator layer, is disposed between the analyzer layer and the liquid crystal layer.

Claims

1. A normally white liquid crystal display, comprising:

a polarizer layer having an absorbing axis;

an analyzer layer having an absorbing axis substantially perpendicular to the absorbing axis of the polarizer layer;

a liquid crystal layer disposed between the polarizer layer and the analyzer layer and having a director exhibiting an azimuthal twist through the layer;

a first electrode proximate to a first major surface of the liquid crystal layer;

a second electrode proximate to a second major surface of the liquid crystal layer, the first and second electrodes being adapted to apply a voltage across the liquid crystal layer when the electrodes are connected to a source of electrical potential; and

a first negatively birefringent compensator layer, oriented with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state, disposed between the polarizer layer and the analyzer layer,

the liquid crystal layer being tilted with respect to the first compensator layer, the polarizer layer, and the analyzer layer.

2. A normally white liquid crystal display, comprising:

a polarizer layer having an absorbing axis;

an analyzer layer having an absorbing axis substantially perpendicular to the absorbing axis of the polarizer layer;

a liquid crystal layer disposed between the polarizer layer and the analyzer layer and having a director exhibiting an azimuthal twist through the layer;

a first electrode proximate to a first major surface of the liquid crystal layer;

a second electrode proximate to a second major surface of the liquid crystal layer, the first and second electrodes being adapted to apply a voltage across the liquid crystal layer when the electrodes are connected to a source of electrical potential; and

a first negatively birefringent compensator layer, oriented with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state, disposed between the polarizer layer and the analyzer layer,

the first compensator layer being tilted with respect to the polarizer, analyzer, and liquid crystal layers.

3. A normally white liquid crystal display, comprising:

a polarizer layer having an absorbing axis;

an analyzer layer having an absorbing axis substantially perpendicular to the absorbing axis of the polarizer layer;

a liquid crystal layer disposed between the polarizer layer and the analyzer layer and having a director exhibiting an azimuthal twist through the layer;

a first electrode proximate to a first major surface of the liquid crystal layer;

a second electrode proximate to a second major surface of the liquid crystal layer, the first and second electrodes being adapted to apply a voltage across the liquid crystal layer when the electrodes are connected to a source of electrical potential; and

a first negatively birefringent compensator layer disposed between the polarizer layer and the analyzer layer, oriented with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state, disposed between the polarizer layer and the analyzer layer;

a second negatively birefringent compensator layer, with a birefringence substantially the same as the birefringence of the first compensator layer and oriented with its optical axis substantially parallel to the optical axis of the first compensator layer, disposed between the analyzer layer and the liquid crystal layer,

the liquid crystal layer being tilted with respect to the first and second compensator layers, the polarizer layer, and the analyzer layer.

4. A normally white liquid crystal display, comprising:

a polarizer layer having an absorbing axis;

an analyzer layer having an absorbing axis substantially perpendicular to the absorbing axis of the polarizer layer;

a liquid crystal layer disposed between the polarizer layer and the analyzer layer and having a director exhibiting an azimuthal twist through the layer;

a first electrode proximate to a first major surface of the liquid crystal layer;

a second electrode proximate to a second major surface of the liquid crystal layer, the first and second electrodes being adapted to apply a voltage across the liquid crystal layer when the electrodes are connected to a source of electrical potential; and

a first negatively birefringent compensator layer disposed between the polarizer layer and the analyzer layer, oriented with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state, disposed between the polarizer layer and the analyzer layer;

a second negatively birefringent compensator layer, with a birefringence substantially the same as the birefringence of the first compensator layer and oriented with its optical axis substantially parallel to the optical axis of the first compensator layer, disposed between the analyzer layer and the liquid crystal layer,

the first and second compensator layers being tilted with respect to the polarizer, analyzer, and liquid crystal layers.

5. A method of compensating for phase retardation in a normally white liquid crystal display of the type including a polarizer layer having an absorbing axis, an analyzer layer having an absorbing axis substantially erpendicular to the absorbing axis of the polarizer layer, a liquid crystal layer disposed between the polarizer layer and the analyzer layer and having a director exhibiting an azimuthal twist through the layer, a first electrode proximate to a first major surface of the liquid crystal layer, and a second electrode proximate to a second major surface of the liquid crystal layer, the first and second electrodes being adapted to apply a voltage across the liquid crystal layer when the electrodes are connected to a source of electrical potential, the method comprising the steps of:

placing a first negatively birefringent compensator layer between the polarizer layer and the analyzer layer;

orienting the first compensator layer with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state; and

tilting the liquid crystal layer with respect to the first compensator layer, the polarizer layer, and the analyzer layer.

6. A method of compensating for phase retardation in a normally white liquid crystal display of the type including a polarizer layer having an absorbing axis, an analyzer layer having an absorbing axis substantially perpendicular to the absorbing axis of the polarizer layer, a liquid crystal layer disposed between the polarizer layer and the analyzer layer and having a director exhibiting an azimuthal twist through the layer, a first electrode proximate to a first major surface of the liquid crystal layer, and a second electrode proximate to a second major surface of the liquid crystal layer, the first and second electrodes being adapted to apply a voltage across the liquid crystal layer when the electrodes are connected to a source of electrical potential, the method comprising the steps of:

placing a first negatively birefringent compensator layer between the polarizer layer and the analyzer layer;

orienting the first compensator layer with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state; and

tilting the first compensator layer with respect to the polarizer, analyzer, and liquid crystal layers.

7. A method of compensating for phase retardation in a normally white liquid crystal display of the type including a polarizer layer having an absorbing axis, an analyzer layer having an absorbing axis substantially perpendicular to the absorbing axis of the polarizer layer, a liquid crystal layer disposed between the polarizer layer and the analyzer layer and having a director exhibiting an azimuthal twist through the layer, a first electrode proximate to a first major surface of the liquid crystal layer, and a second electrode proximate to a second major surface of the liquid crystal layer, the first and second electrodes being adapted to apply a voltage across the liquid crystal layer when the electrodes are connected to a source of electrical potential, the method comprising the steps of:

placing a first negatively birefringent compensator layer between the polarizer layer and the liquid crystal layer;

orienting the first compensator layer with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state;

placing a second negatively birefringent compensator layer, with a birefringence substantially the same as the birefringence of the first compensator layer, between the analyzer layer and the liquid crystal layer;

orienting the second compensator layer with its optical axis substantially parallel to the optical axis of the first compensator layer; and

tilting the liquid crystal layer with respect to the first and second compensator layers, the polarizer layer, and the analyzer layer.

8. A method of compensating for phase retardation in a normally white liquid crystal display of the type including a polarizer layer having an absorbing axis, an analyzer layer having an absorbing axis substantially perpendicular to the absorbing axis of the polarizer layer, a liquid crystal layer disposed between the polarizer layer and the analyzer layer and having a director exhibiting an azimuthal twist through the layer, a first electrode proximate to a first major surface of the liquid crystal layer, and a second electrode proximate to a second major surface of the liquid crystal layer, the first and second electrodes being adapted to apply a voltage across the liquid crystal layer when the electrodes are connected to a source of electrical potential, the method comprising the steps of:

placing a first negatively birefringent compensator layer between the polarizer layer and the liquid crystal layer;

orienting the first compensator layer with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state;

placing a second negatively birefringent compensator layer, with a birefringence substantially the same as the birefringence of the first compensator layer, between the analyzer layer and the liquid crystal layer;

orienting the second compensator layer with its optical axis substantially parallel to the optical axis of the first compensator layer; and

tilting the first and second compensator layers with respect to the polarizer, analyzer, and liquid crystal layers.