GB2139778A — Color display system

Claim 1

Independent Claim 175 words

Afield sequential color display system, comprising: a light source that emits light rays of a plurality of wavelengths, a light polarizing system including a color selective polarizing filter and a linear polarizing filter in optical communication with the light source, the color selective polarizing filter having first and second substantially orthogonally oriented absorption axes, the first absorption axis passing linearly polarized light of a first color 35 and the second absorption axis passing linearly polarized light of a second color, variable optical retarding means disposed between the color selective polarizing filter and the linear polarizing filter, and switching means in communication with the variable optical retarding means to provide first and second switching states, the first switching state providing a first amount of retardation of light passing through the 40 variable optical retarding means to allow the transmission of light of one of the first and second colors through the polarizing system and the second switching state providing a second amount of retardation to allow transmission of light of the other colorthrough the polarizing system.

Claim 2

Dependent Claim 175 words

Afield sequential color display system, comprising: a light source that emits light rays of a plurality of wavelengths, a light polarizing system including a color selective polarizing filter and a linear polarizing filter in optical communication with the light source, the color selective polarizing filter having first and second substantially orthogonally oriented absorption axes, the first absorption axis passing linearly polarized light of a first color 35 and the second absorption axis passing linearly polarized light of a second color, variable optical retarding means disposed between the color selective polarizing filter and the linear polarizing filter, and switching means in communication with the variable optical retarding means to provide first and second switching states, the first switching state providing a first amount of retardation of light passing through the 40 variable optical retarding means to allow the transmission of light of one of the first and second colors through the polarizing system and the second switching state providing a second amount of retardation to allow transmission of light of the other colorthrough the polarizing system.

Claim 3

Dependent Claim 64 words

The sequential color display system of claim 1 in which the color sensitive polarizing filter includes first and second pleochroic linear polarizers, the first pleochroic polarizer having an absorption axis which 45 comprises the first absorption axis of the color sensitive polarizing filter and the second pleochroic polarizer having an absorption axis which comprises the second absorption axis of the color sensitive polarizing filter.

Claim 4

Dependent Claim 34 words

The sequential color display system of claim 1 in which the light emitted from the source of light is modulated in synchronism with the switching means to produce an image having a multicolored appearance.

Claim 5

Dependent Claim 127 words

The display system of claim 1 in which the variable optical retarding means comprises a liquid crystal cell having liquid crystal material with alignment directors, the liquid crystal cell being responsive to electric fields of different intensities introduced within the cell by the first and second switching states of the switching means, the first switching state providing a higher intensity electric field to cause the directors to align substantially end-to-end in a direction parallel to the flux lines of the electric field and the second switching state providing a lower intensity electric field to cause the directors to recede from the end-to-end alignmentto an alignment in which a component of each one of a substantial number of the directors is projected on the surfaces of the cell.

Claim 6

Dependent Claim 150 words

The display system of claim 1 in which the variable optical retarding means comprises a liquid crystal cell having a mixture of liquid crystal material with alignment directors and a variable dielectric anisotropy 60 which is frequency dependent, the liquid crystal cell being responsive to signals of different frequencies applied to the cell by the first and second switching states of the switching means, the first switching state providing a lower frequency signal which introduces a first alternating electric field within the cell to cause the directors to align in a direction parallel to the flux lines of the first electric field and the second switching 65,ptate providing a higher frequency signal which introduces a second alternating electric field within the cell 65 8 GB 2 139 778 A 8 io cause the directors to align in a direction not parallel to the flux lines of the second electric field.

Claim 7

Dependent Claim 252 words

In a method for using a liquid crystal cell as a relatively high-speed variable retardation device to vary the retardation of light transmitted therethrough from an external source, the liquid crystal cell comprising liquid crystal material which has directors and is contained between a pair of opposed, spaced-apart optically transparent electrode structures, each electrode structure including a layer of optically transparent 5 and electrically conductive material and the inner surface of each electrode structure having been conditioned so thatthe directors of the liquid crystal material in contact therewith become substantially uniformly aligned to form tilt bias angles with the conditioned surfaces, the tilt bias angles of the directors in contact with one conditioned surface being defined in a rotational sense opposite to the tilt bias angles of the directors in contact with the other conditioned surface, the steps comprising: applying a first signal to the conductive layers of the cell to produce an electriefield to cause alignment of at least some of the surface noncontacting directors in a first configuration to provide a first amount of optical retardation through the cell of light incident to one of the surfaces of the electrode structures; and applying a second signal to the conductive layers of the cell to change the electric field to cause alignment of at least some of the surface noncontacting directors in a second configuration to provide in a relatively 15 short time a second amount of optical retardation of light incident to one of the surfaces of the electrode structures.

Claim 8

Dependent Claim 252 words

In a method for using a liquid crystal cell as a relatively high-speed variable retardation device to vary the retardation of light transmitted therethrough from an external source, the liquid crystal cell comprising liquid crystal material which has directors and is contained between a pair of opposed, spaced-apart optically transparent electrode structures, each electrode structure including a layer of optically transparent 5 and electrically conductive material and the inner surface of each electrode structure having been conditioned so thatthe directors of the liquid crystal material in contact therewith become substantially uniformly aligned to form tilt bias angles with the conditioned surfaces, the tilt bias angles of the directors in contact with one conditioned surface being defined in a rotational sense opposite to the tilt bias angles of the directors in contact with the other conditioned surface, the steps comprising: applying a first signal to the conductive layers of the cell to produce an electriefield to cause alignment of at least some of the surface noncontacting directors in a first configuration to provide a first amount of optical retardation through the cell of light incident to one of the surfaces of the electrode structures; and applying a second signal to the conductive layers of the cell to change the electric field to cause alignment of at least some of the surface noncontacting directors in a second configuration to provide in a relatively 15 short time a second amount of optical retardation of light incident to one of the surfaces of the electrode structures.

Claim 9

Dependent Claim 262 words

In a method for using a liquid crystal cell as a relatively high-speed variable retardation device to vary the retardation of light transmitted therethrough from an external source, the liquid crystal cell comprising liquid crystal material which has directors and is contained between a pair of opposed, spaced-apart 20 optically transparent electrode structures, each electrode structure including a layer of optically transparent and electrically conductive material and the inner surface of each electrode structure having been conditioned so that the directors of the liquid crystal material in contact therewith become substantially uniformly aligned to form tilt bias angles with the conditioned surfaces, the tilt bias angles of the directors in contact with one conditioned surface being defined in a rotational sense opposite to the tilt bias angles of the 25 directors in contact with the other conditioned surface, the steps comprising applying a first signal to the conductive layers of the cell to produce an electric field to cause a substantial number of the surface noncontacting directors to align essentially end-to-end in a direction normal to the conditioned surfaces to provide substantially reduced optical retardation through the cell of light incident to one of the surfaces of the electrode structures; and applying a second signal to the conductive layers of the cell to change the electric field to cause at least some of the surface noncontacting directors within the interior of the cell to recede from the end-to-end alignment to provide in a relatively short time essentially half-wave optical retardation of light incident to one of the surfaces of the electrode structures.

Claim 10

Dependent Claim 262 words

In a method for using a liquid crystal cell as a relatively high-speed variable retardation device to vary the retardation of light transmitted therethrough from an external source, the liquid crystal cell comprising liquid crystal material which has directors and is contained between a pair of opposed, spaced-apart 20 optically transparent electrode structures, each electrode structure including a layer of optically transparent and electrically conductive material and the inner surface of each electrode structure having been conditioned so that the directors of the liquid crystal material in contact therewith become substantially uniformly aligned to form tilt bias angles with the conditioned surfaces, the tilt bias angles of the directors in contact with one conditioned surface being defined in a rotational sense opposite to the tilt bias angles of the 25 directors in contact with the other conditioned surface, the steps comprising applying a first signal to the conductive layers of the cell to produce an electric field to cause a substantial number of the surface noncontacting directors to align essentially end-to-end in a direction normal to the conditioned surfaces to provide substantially reduced optical retardation through the cell of light incident to one of the surfaces of the electrode structures; and applying a second signal to the conductive layers of the cell to change the electric field to cause at least some of the surface noncontacting directors within the interior of the cell to recede from the end-to-end alignment to provide in a relatively short time essentially half-wave optical retardation of light incident to one of the surfaces of the electrode structures.

Claim 11

Dependent Claim 275 words

In a method for using a liquid crystal cell as a relatively high-speed variable retardation device to 35 modulate light transmitted therethrough from an external source, the liquid crystal cell comprising liquid crystal material which has directors and is contained between a pair of opposed, spaced-apart optically transparent electrode structures, each electrode structure including a layer of optically transparent and electrically conductive material and the inner surface of each electrode structure having been conditioned so thatthe directors of the liquid crystal material in contact therewith become substantially uniformly aligned to 40 form tilt bias angles with the conditioned surfaces, the tilt bias angles of the directors in contact with one conditioned surface being defined in a rotational sense opposite to the tilt bias angles of the directors in contact with the other conditioned surface, the steps comprising: applying a first signal to the conductive layers of the cell to produce an electricfield to cause a substantial number of the surface noncontacting directors to align essentially end-to- end in a direction normal to the 45 conditioned surfaces to provide substantially reduced optical retardation through the cell for light incident to one of the electrode surfaces; and applying a second signal to the conductive layers of the cell to change the electric field and cause rotational realignment of the surface noncontacting directors to provide essentially half-wave optical retardation for light incident to one of the electrode surfaces, the rotational realignment of the surface noncontacting directors characterized in that such rotation causes a unidirectional flow of liquid crystal material within the cell to eliminate optical retardation bounce during realignment, therebyto decrease the optical response time of the cell.

Claim 12

Dependent Claim 275 words

In a method for using a liquid crystal cell as a relatively high-speed variable retardation device to 35 modulate light transmitted therethrough from an external source, the liquid crystal cell comprising liquid crystal material which has directors and is contained between a pair of opposed, spaced-apart optically transparent electrode structures, each electrode structure including a layer of optically transparent and electrically conductive material and the inner surface of each electrode structure having been conditioned so thatthe directors of the liquid crystal material in contact therewith become substantially uniformly aligned to 40 form tilt bias angles with the conditioned surfaces, the tilt bias angles of the directors in contact with one conditioned surface being defined in a rotational sense opposite to the tilt bias angles of the directors in contact with the other conditioned surface, the steps comprising: applying a first signal to the conductive layers of the cell to produce an electricfield to cause a substantial number of the surface noncontacting directors to align essentially end-to- end in a direction normal to the 45 conditioned surfaces to provide substantially reduced optical retardation through the cell for light incident to one of the electrode surfaces; and applying a second signal to the conductive layers of the cell to change the electric field and cause rotational realignment of the surface noncontacting directors to provide essentially half-wave optical retardation for light incident to one of the electrode surfaces, the rotational realignment of the surface noncontacting directors characterized in that such rotation causes a unidirectional flow of liquid crystal material within the cell to eliminate optical retardation bounce during realignment, therebyto decrease the optical response time of the cell.

Claim 13

Dependent Claim 246 words

A liquid crystal variable optical retarder having a relatively short relaxation time, comprising: a liquid crystal cell which includes liquid crystal material which has directors and is contained between a 55 pair of opposed, spaced-apart optically transparent electrode structures, each electrode structure having a conductive layer applied thereto and having a conditioned inner surface which has been conditioned so that the directors of the liquid crystal material in contact therewith become substantially uniformly aligned to form tilt bias angles with the conditioned surface, the tilt bias angles of the directors in contact with the conditioned surface of one electrode structure being defined in a rotational sense opposite to the tilt bias 60 angles of the directors in contact with the conditioned surface of the other electrode structure; and field means for applying an electric field to the cell to cause a substantial number of the surface noncontacting directors to align in substantially end-to-end relation in a direction normal to the conditioned surfaces to provide substantially reduced optical retardation through the cell of light incident to one of the surfaces of the electrode structures, and for changing the electric field to cause at least some of the surface 65 il 1 W. z 9 GB 2 139 778 A 9 noncontacting directors within the interior of the cell to recede from the end-to-end alignment to provide in a relatively short time essentially half-wave optical retardation of light incident to one of the surfaces of the electrode structures.

Claim 14

Dependent Claim 246 words

A liquid crystal variable optical retarder having a relatively short relaxation time, comprising: a liquid crystal cell which includes liquid crystal material which has directors and is contained between a 55 pair of opposed, spaced-apart optically transparent electrode structures, each electrode structure having a conductive layer applied thereto and having a conditioned inner surface which has been conditioned so that the directors of the liquid crystal material in contact therewith become substantially uniformly aligned to form tilt bias angles with the conditioned surface, the tilt bias angles of the directors in contact with the conditioned surface of one electrode structure being defined in a rotational sense opposite to the tilt bias 60 angles of the directors in contact with the conditioned surface of the other electrode structure; and field means for applying an electric field to the cell to cause a substantial number of the surface noncontacting directors to align in substantially end-to-end relation in a direction normal to the conditioned surfaces to provide substantially reduced optical retardation through the cell of light incident to one of the surfaces of the electrode structures, and for changing the electric field to cause at least some of the surface 65 il 1 W. z 9 GB 2 139 778 A 9 noncontacting directors within the interior of the cell to recede from the end-to-end alignment to provide in a relatively short time essentially half-wave optical retardation of light incident to one of the surfaces of the electrode structures.

Claim 15

Independent Claim 308 words

A method for providing a liquid crystal cell having nonuniform director alignment which can be used as a variable retardation device to accomplish with relatively short relaxation time the modulation of light 5 transmitted therethrough from an external source, the steps comprising: applying an electrically conductive layerto one surface of each of two optically transparent dielectric members to form a pair of transparent electrode structures; conditioning one surface of each of the pair of electrode structures so that the directors of a liquid crystal material placed thereon will align in a predetermined direction; positioning each electrode structure of the pair so that the conditioned surfaces thereof are in spaced-apart and opposed face-to-face relation; introducing a liquid crystal material between the electrode structures to form an anisotropic cell; orienting the electrode structures so that the directors of the liquid crystal material in contact with the conditioned surfaces align substantially uniformly to form tilt bias angles with the conditioned surfaces, the 15 tilt bias angles of the directors in contact with one conditioned surface being defined in a rotational sense opposite to the tilt bias angles of the directors in contact with the other conditioned surface; and applying alternately to the cell a first signal to provide an electric field to cause a substantial number of the surface noncontacting directors to align in essentially end-to-end relation in a direction normal to the conditioned surfaces to provide substantially reduced optical retardation through the cell of light incident to 20 one of the surfaces of the electrode structures, and a second signal to change the electric field to cause at least some of the surface noncontacting directors within the interior of the cell to recede from the end-to-end alignment to provide in a relatively short time essentially half-wave optical retardation of light incident to one of the surfaces of the electrode structures.

Claim 16

Independent Claim 308 words

A method for providing a liquid crystal cell having nonuniform director alignment which can be used as a variable retardation device to accomplish with relatively short relaxation time the modulation of light 5 transmitted therethrough from an external source, the steps comprising: applying an electrically conductive layerto one surface of each of two optically transparent dielectric members to form a pair of transparent electrode structures; conditioning one surface of each of the pair of electrode structures so that the directors of a liquid crystal material placed thereon will align in a predetermined direction; positioning each electrode structure of the pair so that the conditioned surfaces thereof are in spaced-apart and opposed face-to-face relation; introducing a liquid crystal material between the electrode structures to form an anisotropic cell; orienting the electrode structures so that the directors of the liquid crystal material in contact with the conditioned surfaces align substantially uniformly to form tilt bias angles with the conditioned surfaces, the 15 tilt bias angles of the directors in contact with one conditioned surface being defined in a rotational sense opposite to the tilt bias angles of the directors in contact with the other conditioned surface; and applying alternately to the cell a first signal to provide an electric field to cause a substantial number of the surface noncontacting directors to align in essentially end-to-end relation in a direction normal to the conditioned surfaces to provide substantially reduced optical retardation through the cell of light incident to 20 one of the surfaces of the electrode structures, and a second signal to change the electric field to cause at least some of the surface noncontacting directors within the interior of the cell to recede from the end-to-end alignment to provide in a relatively short time essentially half-wave optical retardation of light incident to one of the surfaces of the electrode structures.

Claim 17

Dependent Claim 34 words

The method of claim 10 which further comprises the step of introducing liquid crystal material of a 25 different thickness into the cell to provide essentially half-wave retardation of light of a different wavelength.

Claim 18

Dependent Claim 123 words

A highspeed color switch that receives light of a plurality of wavelengths emitted from alight source, comprising: first and second light polarizing means in optical communication with the light source, the first light polarizing means including a color selective polarizing filter, variable optical retarding means disposed between the first and second light polarizing means, and switching means in communication with the variable optical retarding means for selectably producing two different amounts of retardation to transmit a light output of one of two colours, one of the two amounts being substantially zero retardation of light of all colors. Printed in the UK for HMSO, D8818935, 9184, 7102. Published by The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.

Claim 19

Dependent Claim 123 words

A highspeed color switch that receives light of a plurality of wavelengths emitted from alight source, comprising: first and second light polarizing means in optical communication with the light source, the first light polarizing means including a color selective polarizing filter, variable optical retarding means disposed between the first and second light polarizing means, and switching means in communication with the variable optical retarding means for selectably producing two different amounts of retardation to transmit a light output of one of two colours, one of the two amounts being substantially zero retardation of light of all colors. Printed in the UK for HMSO, D8818935, 9184, 7102. Published by The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.

Color display system

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