Additive color tristate light valve twisting ball display

• US 5,737,115 A
• Filed: 12/15/1995
• Issued: 04/07/1998
• Est. Priority Date: 12/15/1995
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Mackinlay, Jock D., Stone, Maureen C.
• Primary Examiner(s): Ben, Loha
• Application Number:
  US08/573,922
• Time in Patent Office: 844 Days
• Field of Search: 359/296, 359/298, 345/111, 345/107, 345/108, 364/4, 364/5, 364/7, 364/8, 364/15, 427/214, 427/282, 349/112, 349/142, 349/87, 349/94, 349/117, 349/188
• US Class Current: 359/296
• CPC Class Codes: G02B 26/026 based on the rotation of particles under the influence of an external field, e.g. gyricons, twisting ball displays based on orientable dipolar particles G02F1/172; based on electrophoresis G02F1/167
• CPC Class Codes: G09F 9/372 the positions of the elements being controlled by the application of an electric field

Abstract

A tristate light valve ball for an electrical twisting ball device composed of spheroidal balls rotatably disposed in an elastomer substrate. The ball is composed of segments arrayed substantially parallel to one another, each segment being adjacent to at least one other segment and to no more than two other segments. Adjacent segments are adjoined to one another at substantially planar interfaces. The segments include: a first, interior, nontransparent segment having a first optical modulation characteristic; a second exterior, transparent segment, adjacent to the first segment and having a second optical modulation characteristic; a third, interior, nontransparent segment having a third optical modulation characteristic; and a fourth, exterior, transparent segment adjacent to the third segment. For example, the ball can be made with a black first segment adjacent to a white third segment, surrounded on either side by clear second and fourth exterior segments. The ball has an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the ball electrically responsive such that when the ball is rotatably disposed in a nonoscillating electric field while the electrical dipole moment of the ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field. Also disclosed are: a material made up of a substrate layer in which are disposed the aforementioned balls, with a colored backing joined to a rear surface of the layer; and a method for using a device incorporating the balls.

Claims

1. A spheroidal ball comprising a plurality of segments arrayed substantially parallel to one another, each segment being adjacent to at least one other segment and to no more than two other segments, each segment adjacent to exactly one other segment being an exterior segment and each segment adjacent to exactly two other segments being an interior segment, adjacent segments being adjoined to one another at substantially planar interfaces, the segments including

a first segment, the first segment being an interior segment having a first optical modulation characteristic, the first optical modulation characteristic being such that the first segment is nontransparent,

a second segment, the second segment being an exterior segment adjacent to the first segment, the second segment having a second optical modulation characteristic, the second optical modulation characteristic being such that the second segment is transparent,

a third segment, the third segment being an interior segment having a third optical modulation characteristic, the third optical modulation characteristic being such that the third segment is nontransparent, and

a fourth segment, the fourth segment being an exterior segment adjacent to the third segment, the fourth segment having an optical modulation characteristic such that the fourth segment is transparent,

the ball having an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the ball electrically responsive such that when the ball is rotatably disposed in a nonoscillating electric field while the electrical dipole moment of the ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field.

2. The ball of claim 1 wherein the first segment is adjacent to the third segment, each of the first and third segments is opaque, the first segment is black, the third segment is white, and the second and fourth segments are clear.

3. The ball of claim 1 wherein

the second segment is associated with a first zeta potential, and

the third segment is associated with a second zeta potential,

the first and second zeta potentials arising when the ball is disposed in a dielectric fluid, the first and second zeta potentials contributing to the electrical dipole moment.

4. An optical modulation device comprising the ball of claim 1 rotatably disposed in a containing structure.

5. An optical modulation device having at least three operational states, each state being associated with an optical modulation characteristic, the device comprising:

a first optical modulation means comprising a spheroidal ball having at least two component regions including a component region having a first optical modulation characteristic and a component region having a second optical modulation characteristic, the first optical modulation characteristic being such that the component region having the first optical modulation characteristic is nontransparent, the second optical modulation characteristic being such that the component region having the second optical modulation characteristic is transparent, the ball having an anisotropy for providing an electrical dipole moment rendering the ball electrically responsive such that when the ball is rotatably disposed in an electric field while the electrical dipole moment of the ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field;

a second optical modulation means comprising a spheroidal ball having at least two component regions including a component region having the second optical modulation characteristic and a component region having a third optical modulation characteristic, the third optical modulation characteristic being such that the component region having the third optical modulation characteristic is nontransparent, the component region having the second optical modulation characteristic being transparent, the ball having an anisotropy for providing an electrical dipole moment rendering the ball electrically responsive such that when the ball is rotatably disposed in an electric field while the electrical dipole moment of the ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field;

means for disposing the spheroidal ball of the first optical modulation means in a light path so as to interact with light in the light path; and

means for disposing the spheroidal ball of the second optical modulation means in said light path so as to interact with light in said light path.

6. The device of claim 5 wherein the spheroidal ball of the first optical modulation means is the same ball as the spheroidal ball of the second optical modulation means and has three component regions, including

a first component region having the first optical modulation characteristic,

a second component region having a second optical modulation characteristic, and

a third component region having the third optical modulation characteristic.

7. Light valve apparatus comprising

a device as recited in claim 5, wherein

the means for disposing the spheroidal ball of the first optical modulation means in the light path comprises means for rotatably disposing the spheroidal ball of the first optical modulation means in the light path, and

the means for disposing the spheroidal ball of the second optical modulation means in the light path comprises means for rotatably disposing the spheroidal ball of the second optical modulation means in the light path;

and further comprising;

means for facilitating a rotation of the spheroidal ball of the first optical modulation means; and

means for facilitating a rotation of the spheroidal ball of the second optical modulation means.

8. A material comprising:

a substrate comprising a layer having front and rear surfaces;

a plurality of light-modulating elements disposed in the substrate between the front and rear surfaces of the layer,

each element comprising at least one spheroidal ball disposed in the substrate,

each ball of each element comprising at least two component regions, the component regions including

a first component region having a first optical modulation characteristic such that the first component region is transparent and does not have a chromatic color, and

a second component region having a second optical modulation characteristic such that the second component region is nontransparent and does not have a chromatic color,

each ball of each element having an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the ball electrically responsive such that when the ball is rotatably disposed in a nonoscillating electric field while the electrical dipole moment of the ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field,

each element having at least two operational states including

a first, transmissive state admitting a passage of light through the element and thereby through the layer, and

a second, nontransmissive state obstructing a passage of light through the element and through the layer;

and

a backing joined to the rear surface of the layer, at least a portion of the backing having a chromatic color, the portion having the chromatic color being disposed such that, to an observer favorably situated to observe the front surface of the substrate layer, the chromatic color is observable through at least one light-modulating element when said element is in the first, transmissive state.

9. The material of claim 8 wherein:

for each ball of each element,

the first optical modulation characteristic is such that the first component region is clear, and

the second optical modulation characteristic is such that the second component region has an achromatic color; and

for an element disposed between the observer and the portion of the backing having the chromatic color,

the observer observes the chromatic color when the element thus disposed is in the first, transmissive state, and

the observer observes the achromatic color when the element thus disposed is in the second, nontransmissive state.

10. The material of claim 8 wherein:

each ball of each element further comprises a third component region having a third optical modulation characteristic such that the third component region is nontransparent and does not have a chromatic color; and

each element further has a third, nontransmissive state obstructing a passage of light through the element and through the layer.

11. The material of claim 8 wherein:

the backing comprises a substantially regular geometric pattern of areas each having a color, adjacent areas of the pattern having different colors, the pattern having at least three different chromatic colors including red, green, and blue;

each area of the pattern has an optical modulation characteristic selected from the group consisting of transparent, reflective, and opaque; and

said portion of the backing having the chromatic color is identified with any one of the areas of the pattern.

12. Apparatus comprising:

a piece of the material of claim 8; and

means for facilitating a change in the state of at least one light-modulating element of the plurality by producing an electric field to facilitate a rotation of a ball of the element, the ball being rotatably disposed in the substrate.

13. The apparatus of claim 12 wherein the backing has a plurality of colored areas, including

an area of a first chromatic color,

an area of a second chromatic color, and

an area of a third chromatic color,

and wherein the facilitating means comprises:

means for selecting a preferred chromatic color, the preferred chromatic color being any one of the first, second, and third chromatic colors;

means for selecting a preferred region of the backing, the preferred backing region having the preferred chromatic color; and

means for facilitating a change in the state of a light-modulating element disposed between the selected preferred region and the observer.

14. A method comprising the steps of:

producing a light having a chromatic color;

providing the colored light thus produced incident on a device comprising a plurality of light-modulating elements disposed in a substrate having first and second surfaces,

each element comprising at least one spheroidal ball disposed in the substrate,

each ball of each element comprising at least two component regions, the component regions including

a first component region having a first optical modulation characteristic such that the first component region is transparent and does not have a chromatic color, and

a second component region having a second optical modulation characteristic such that the second component region is nontransparent and does not have a chromatic color,

each ball of each element having an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the ball electrically responsive such that when the ball is rotatably disposed in a nonoscillating electric field while the electrical dipole moment of the ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field,

each element having at least two operational states including

a transmissive state admitting a passage of light through the element and thereby through the substrate from the first surface to the second surface, and

a nontransmissive state obstructing a passage of light through the element and through the substrate;

admitting a portion of the colored light incident on the modulating device through a light-modulating element in the transmissive state, thereby allowing the colored light thus admitted to pass through the substrate from the first surface to the second surface;

obstructing a portion of the colored light incident on the modulating device with a light-modulating element in the nontransmissive state, thereby preventing the colored light thus obstructed from passing through the substrate from the first surface to the second surface; and

applying an electric field in a vicinity of a light-modulating element to facilitate a rotation of a spheroidal ball of said element, the ball being rotatably disposed in the substrate, thereby facilitating a change in the state of said element from a first operational state to a second operational state.

15. The method of claim 14 wherein the light-modulating device further comprises a backing material joined to the first surface of the substrate, and wherein:

the step of producing colored light comprises

providing light from a light source incident on the second surface of the substrate in a vicinity of said light-modulating element in the transmissive state, light from the light source passing through the substrate from the second surface to the first surface and thence to the backing material, and

reflecting a part of the light thus passed from a light-reflecting portion of the backing material, the light-reflecting portion having an optical modulation characteristic such that the light-reflecting portion preferentially reflects light having a preferred chromatic color and preferentially absorbs other light; and

the step of admitting a portion of the colored light so as to allow light to pass through the substrate from the first to the second surface comprises admitting light thus preferentially reflected from the light-reflecting portion back through the light-modulating element in the transmissive state so as to re-emerge from the substrate at the second surface.

16. A method comprising the steps of:

providing light from a light source incident on a modulating device comprising a array of individually addressable elements, the elements being disposed in a substrate having a front surface on which light from the light source is incident and a rear surface joined to a backing material,

each element being a basic constituent unit of the array, such that

no element comprises any separately addressable components other than itself, and

no component portion of an element is addressable independently of the entire element,

each element having an observable area, the observable area being observable by an observer situated favorably to observe the front surface;

selecting a preferred element of the array, the preferred element having a plurality of operational states including

a first state in which a predominant portion of the observable area of the selected element appears black to the observer,

a second state in which, to the observer, the observable area of the selected element appears to comprise a combination of black and a chromatic color,

a third state in which a predominant portion of the observable area of the selected element appears to the observer to have the chromatic color,

a fourth state in which, to the observer, the observable area of the selected element appears to comprise a combination of white and the chromatic color, and

a fifth state in which a predominant portion of the observable area of the selected element appears white to the observer;

selecting from among the operational states of the plurality a preferred operational state for the preferred element;

establishing the preferred operational state as the operational state of the preferred element; and

with the preferred element in the preferred operational state, modulating with the preferred element of the modulating device at least a portion of the light incident thereon,

light incident on the preferred element being predominantly absorbed by a black nontransmissive component of the preferred element if the preferred element is in the first state,

light incident on the preferred element being partly absorbed by a black nontransmissive component of the preferred element and partly admitted through a transmissive component of the preferred element if the preferred operational state is the second state,

light incident on the preferred element being predominantly admitted through a transmissive component of the preferred element if the preferred operational state is the third state,

light incident on the preferred element being partly reflected by a white nontransmissive component of the preferred element and partly admitted through a transmissive component of the preferred element if the preferred operational state is the fourth state,

light incident on the preferred element being predominantly reflected by a white nontransmissive component of the preferred element if the preferred element is in the fifth state,

light admitted through a transmissive component of the preferred element in any of the second, third, and fourth states passing thereby through the substrate from the front surface to the rear surface and thence to a portion of the backing material having an optical modulation characteristic such that said portion of the backing material preferentially reflects light having the chromatic color,

light preferentially reflected by said portion of the backing material passing back through the transmissive component of the preferred element and thereby through the substrate from the rear surface to the front surface and thence out of the substrate, thus providing light of the chromatic color observable to the observer and so contributing to the appearance of the observable area of the preferred element in the second, third, and fourth states.

17. The method of claim 16 wherein:

the step of selecting a preferred operational state for the preferred element comprises

selecting an achromatic color from among black and white if the preferred operational state is other than the third state, and

selecting a preferred proportion of the chromatic color for inclusion in a proportional combination of the chromatic color with any achromatic color thus selected, the preferred proportion being adjustable over a range from a minimum value to a maximum value, the minimum value corresponding to a proportional combination substantially lacking in chromatic color, the maximum value corresponding to a proportional combination substantially lacking in achromatic color,

the preferred operational state being the first state when an achromatic color of black is selected and the preferred proportion of the chromatic color is the minimum value,

the preferred operational state being the second state when an achromatic color of black is selected and the preferred proportion of the chromatic color is a value between the minimum and maximum values,

the preferred operational state being the third state when the preferred proportion of the chromatic color is the maximum value,

the preferred operational state being the fourth state when an achromatic color of white is selected and the preferred proportion of the chromatic color is a value between the minimum and maximum values,

the preferred operational state being the fifth state when an achromatic color of white is selected and the preferred proportion of the chromatic color is the minimum value; and

the step of establishing the preferred operational state comprises establishing a configuration of transmissive and nontransmissive components of the preferred element such that a proportional combination of the chromatic color and any selected achromatic color is presented to the observer, the proportional combination thus presented having the selected preferred proportion of the chromatic color.

18. The method of claim 16 wherein the preferred element comprises at least one spheroidal ball rotatably disposed in the substrate in a vicinity of the preferred element,

each ball of the preferred element comprising at least three component regions, the component regions including

a first component region having a first optical modulation characteristic such that the first component region is transparent,

a second component region having a second optical modulation characteristic such that the second component region is black, and

a third component region having a third optical modulation characteristic such that the third component region is white,

each ball of the preferred element having an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the ball electrically responsive such that when the ball thus rotatably disposed in the substrate is subjected to an electric field while the electrical dipole moment of the ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field,

and wherein:

the step of selecting a preferred operational state for the preferred element comprises selecting a preferred direction of orientation for spheroidal balls of the preferred element, a correspondence existing between the operational state of the preferred element and the direction of orientation of balls in the preferred element, the preferred direction of orientation forming an angle with a vector normal to a planar portion of the substrate surface in a vicinity of the preferred substrate region, the angle being adjustable over a continuous range of angles from 0 degree to 180 degrees; and

the establishing step comprises aligning balls of the preferred element with the preferred direction of orientation by applying in the vicinity of the preferred element an electric field having an electric field vector oriented parallel to the selected preferred direction, thereby influencing balls of the preferred element to rotate so as to align with the preferred direction of orientation.

19. A device comprising:

a substrate having a surface; and

an array of individually addressable image elements disposed in the substrate,

each image element being a basic constituent unit of the array, such that

no element comprises any separately addressable components other than itself, and

no component portion of an element is addressable independently of the entire element,

each element having an observable area, the observable area being observable by an observer situated favorably to observe the substrate surface,

each element having a plurality of operational states each associated with an appearance of the observable area of the element to the observer, any one of the operational states being establishable as a current state of an addressed element, the operational states including

a first state associated with a first appearance of the observable area of the element, the first appearance providing a first achromatic color observable throughout a predominant portion of the observable area,

a second state associated with a second appearance of the observable area of the element, the second appearance providing a second achromatic color observable throughout a predominant portion of the observable area,

a third state associated with a third appearance of the observable area of the element, the third appearance providing a chromatic color observable throughout a predominant portion of the observable area,

a fourth state associated with a fourth appearance of the observable area of the element, the fourth appearance providing an observable combination of the first achromatic color and the chromatic color, the combination thus provided being observable in the observable area, and

a fifth state associated with a fifth appearance of the observable area of the element, the fifth appearance providing an observable combination of the second achromatic color and the chromatic color, the combination thus provided being observable in the observable area.

20. The device of claim 19 wherein each image element comprises a light valve and a color source, the light valve providing the first and second achromatic colors for the first and second states of the element, the color source providing the chromatic color for the third state of the element, the light valve and the color source cooperating to provide the combinations of colors of the fourth and fifth states of the element.