Subtractive color twisting ball display

• US 5,767,826 A
• Filed: 12/15/1995
• Issued: 06/16/1998
• 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: Robertson, George G., Sheridon, Nicholas K.
• Primary Examiner(s): Bayerl, Raymond J.
• Assistant Examiner(s): SURACI, JOHN F
• Application Number:
  US08/572,780
• Time in Patent Office: 914 Days
• Field of Search: 345/84, 345/85, 345/107, 345/108, 345/4, 345/6, 345/87, 359/296, 349/80
• US Class Current: 345/84
• 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 multilayer substrate material for a subtractive-color electrical twisting ball display. The material is composed of a layered substrate including first, second, and third layers, each layer of the substrate being a nearest neighboring layer with respect to at least one other layer and no more than two other layers. Spheroidal balls are disposed in each of the first, second, and third layers. In the first layer, each ball has at least two component regions including a component region having a first chromatic color, such as transparent cyan. In the second layer, each ball has at least two component regions including a component region having a second chromatic color, such as transparent magenta. In the third layer, each ball has at least two component regions including a component region having a third chromatic color, such as transparent yellow. Optionally, the substrate can further include a fourth layer in which are disposed spheroidal balls, each having at least two component regions including a black component region. Each ball in each layer 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 twisting-ball apparatus made with the material, and a method for using this apparatus.

Claims

1. A material comprising:

a substrate comprising a plurality of layers, each layer being a nearest neighboring layer with respect to at least one other layer of the plurality and no more than two other layers of the plurality, the layers including first, second, and third layers;

a first plurality of spheroidal balls disposed in the first layer, each ball of the first plurality having at least two component regions including a component region having an achromatic color and a component region having a first chromatic color;

a second plurality of spheroidal balls disposed in the second layer, each ball of the second plurality having at least two component regions including a component region having an achromatic color and a component region having a second chromatic color;

a third plurality of spheroidal balls being disposed in the third layer, each ball of the third plurality having at least two component regions including a component region having an achromatic color and a component region having a third chromatic color;

each ball of each of the first, second, and third pluralities 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 material of claim 1 wherein:

the achromatic color of each ball of each of the first, second, and third pluralities is clear; and

each of the first, second, and third chromatic colors is a transparent color selected from the group consisting of cyan, magenta, and yellow.

3. The material of claim 1 wherein the plurality of substrate layers further comprises a fourth layer, and further comprising:

a fourth plurality of spheroidal balls disposed in the fourth layer, each ball of the fourth plurality having at least two component regions including a black component region and a component region having a color other than black,

each ball of the fourth plurality 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 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.

4. The material of claim 1 wherein at least one layer of the substrate has a surface identified with a surface of the substrate, and further comprising:

a backing material joined to the surface, the backing material having a optical modulation characteristic such that the backing material tends to reflect light leaving the substrate through the surface of the substrate.

5. The material of claim 4 wherein the backing material is white.

6. The material of claim 1 wherein each spheroidal ball of each of the first, second, and third pluralities is a spheroidal ball having a center point and comprising three (3) 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 three segments including

a first segment identified with the component region having the chromatic color, the first segment being an interior segment including the center point, the first segment having a first optical modulation characteristic, the first optical modulation characteristic being such that the first segment has a transparent color selected from the group consisting of cyan, magenta, and yellow,

a second segment identified with the component region having the achromatic color, 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 clear, and

a third segment, the third segment being an exterior segment adjacent to the first segment and situated opposite the second segment with respect to the first segment, the third segment having the second optical modulation characteristic.

7. Apparatus comprising:

a piece of the material recited in claim 1; and

means for producing an electric field to facilitate a rotation of at least one ball, each ball for which a rotation is facilitated being a ball one of the first, second, and third pluralities and being rotatably disposed in the substrate of the piece of material.

8. The apparatus of claim 7 wherein the field-producing means comprises a plurality of electrodes each disposed between two nearest neighboring layers of the substrate, and includes

means for applying the electric field to a portion of the first substrate layer substantially without applying the electric field to any portion of any other substrate layer,

means for applying the electric field to a portion of the second substrate layer substantially without applying the electric field to any portion of any other substrate layer, and

means for applying the electric field to a portion of the third substrate layer substantially without applying the electric field to any portion of any other substrate layer.

9. The apparatus of claim 7 wherein:

for each ball rotatably disposed in the first substrate layer, a rotation of the ball is facilitated when the ball thus rotatably disposed is subjected to a nonoscillating electric field having an electric field strength exceeding a first threshold;

for each ball rotatably disposed in the second substrate layer, a rotation of the ball is facilitated when the ball thus rotatably disposed is subjected to a nonoscillating electric field having an electric field strength exceeding a second threshold;

for each ball rotatably disposed in the third substrate layer, a rotation of the ball is facilitated when the ball thus rotatably disposed is subjected to a nonoscillating electric field having an electricfield strength exceeding a third threshold;

and wherein the field-producing means comprises an electrode assembly disposed outside the layers of the substrate, and includes

means for applying the electric field to all layers of the substrate at a first electric field strength so as to facilitate a rotation of each ball in a first set of balls, the first set comprising at least one ball and including at least one ball of the first layer, each ball of the first set being disposed in any of the first, second, and third substrate layers,

means for applying the electric field to all layers of the substrate at a second electric field strength so as to facilitate a rotation of each ball in a second set of balls, the second set comprising at least one ball and including at least one ball of the second layer, each ball of the second set being disposed in one of the second and third substrate layers, and

means for applying the electric field to all layers of the substrate at a third electric field strength so as to facilitate a rotation of each ball in a third set of balls, the third set comprising at least one ball, each ball of the third set being disposed in the third substrate layer only.

10. The apparatus of claim 7 wherein the field-producing 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 substrate layer corresponding to the selected preferred chromatic color, the selected preferred layer being one of the first, second, and third substrate layers, each ball of the selected preferred layer having a component region of the selected preferred chromatic color;

means for selecting a preferred region of the substrate, the preferred region being a region within the selected preferred substrate layer;

means for selecting a preferred degree of color saturation for the preferred chromatic color in the preferred region, the preferred degree of color saturation being selectable from among a range of degrees of color saturation; and

means for establishing the preferred degree of color saturation for the preferred chromatic color in the preferred region within the preferred substrate layer by applying an electric field in a vicinity of the preferred region to facilitate a rotation of at least one ball in the preferred region, each ball for which a rotation is facilitated having a component region of the preferred chromatic color.

11. The apparatus of claim 10 wherein the establishing means is selected from the group consisting of canted-field electrode means and multithreshold electrode means.

12. A method comprising the steps of:

providing light from a light source incident on an optical modulation apparatus comprising a plurality of layers including first and second layers, each layer having a plurality of spheroidal balls rotatably disposed therein,

each ball of each layer being associated with an optical modulation property,

each ball of the first layer being associated with a first optical modulation property,

each ball of the second layer being associated with a second optical modulation property,

each ball of each layer having at least two component regions, including

a first component region having the optical modulation property with which the ball is associated, and

a second, transparent component,

each ball of each layer 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 layer is subjected to a nonoscillating electric field while the electrical dipole moment of said ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field;

applying an electric field in a vicinity of a spheroidal ball of one of the first and second layers to facilitate a rotation of said ball; and

modulating with the optical modulation apparatus at least a portion of the light incident thereon, the light thus modulated being modulated at least in part by the ball for which the rotation is facilitated.

13. The method of claim 12 wherein

the plurality of layers of the apparatus further includes a third layer, each ball of the third layer being associated with a third optical modulation property;

the first optical modulation property is such that the first component region of each ball of the first layer has a first transparent chromatic color;

the second optical modulation property is such that the first component region of each ball of the second layer has a second transparent chromatic color;

the third optical modulation property is such that the first component region of each ball of the third layer has a third transparent chromatic color; and

the second optical modulation property of each ball of the each of the first, second, and third layers is such that the second component region of each ball of the first, second, and third layers is clear;

and wherein;

the modulating step comprises modulating white light incident on the apparatus to produce modulated light having a preferred color, the preferred color being any color obtainable as a result of a color subtraction involving at least one of the first, second, and third chromatic colors.

14. The method of claim 13 wherein

each of the first, second, and third chromatic colors is selected from the group consisting of cyan, magenta, and yellow, and

and the plurality of layers of the apparatus further includes a fourth layer, each ball of the fourth layer being associated with a fourth optical modulation property, the fourth optical modulation property being such that the first component region of each ball of the fourth layer is black,

and wherein:

the modulating step comprises modulating white light incident on the apparatus to produce modulated light having a preferred color, the preferred color being any color obtainable as a result of a color subtraction involving at least one of the first, second, and third chromatic colors and black.

15. The method of claim 13 wherein the step of applying an electric field comprises:

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

selecting a preferred layer corresponding to the selected preferred color, the selected preferred layer being one of the first, second, and third substrate layers,

each ball of the selected preferred layer having a component region of the selected preferred chromatic color;

selecting a preferred region of the substrate, the preferred region being a region within the selected preferred substrate layer;

selecting a preferred degree of color saturation for the preferred chromatic color in the preferred region, the preferred degree of color saturation being selectable from among a range of degrees of color saturation; and

establishing the preferred degree of color saturation for the preferred chromatic color in the preferred region within the preferred substrate layer by applying an electric field in a vicinity of the preferred region to facilitate a rotation of at least one ball in the preferred region, each ball for which a rotation is facilitated having a component region of the preferred chromatic color.

16. The method of claim 12 wherein

the apparatus comprises a multilayered substrate having front and rear surfaces, the substrate including a plurality of layers identified with the layers of the apparatus;

and wherein;

the providing step comprises providing light incident on the front surface of the substrate; and

the modulating step comprises selectively transmitting the incident light through the layers of the plurality towards the rear surface ofthe substrate.

17. The method of claim 16 wherein

the apparatus further includes an electrode assembly disposed outside the layers of the substrate;

the plurality of substrate layers identified with layers of the apparatus further includes a third layer, each ball of the third layer being associated with a third optical modulation property; and

each ball of each of the first, second, and third layers has a rotational orientation, the rotational orientation of each ball being defined with respect to a planar portion of the front surface of the substrate proximate to the ball;

and wherein the step of applying the electric field comprises;

selecting a preferred region of the substrate, the preferred region including a first set of balls rotatably disposed in the first substrate layer, a second set of balls rotatably disposed in the second substrate layer, and a third set of balls rotatably disposed in the third substrate layer, each of the first, second, and third sets comprising at least one ball,

a rotation of each ball of the first set being facilitated when the ball thus rotatably disposed in the first substrate layer is subjected to a nonoscillating electric field having an electric field strength exceeding a first threshold,

a rotation of each ball of the second set being facilitated when the ball thus rotatably disposed in the second substrate layer is subjected to a nonoscillating electric field having an electric field strength exceeding a second threshold, the second threshold being less than the first threshold, and

a rotation of each ball of the third set being facilitated when the ball thus rotatably disposed in the third substrate layer is subjected to a nonoscillating electric field having an electric field strength exceeding a third threshold, the third threshold being less than the second threshold;

determining a first preferred rotational orientation for balls of the first set;

determining a second preferred rotational orientation for balls of the second set;

determining a third preferred rotational orientation for balls of the third set; and

applying a series of electric fields with the electrode assembly, each field of the series being applied in a vicinity of the preferred region to all layers of the substrate simultaneously, the applying of the entire series of fields serving to facilitate a disposition of the balls in each of the first, second, and third sets in their respective preferred rotational orientations, the series of fields including

a first electric field having an electric field strength exceeding the first threshold, the first electric field facilitating rotations of balls in each of the first, second, and third sets so as to achieve the preferred rotational orientation of balls in the first set while possibly affecting the rotational orientations of balls of the second and third sets, the first electric field being applied first in the series if the balls of the first set are not already in the first preferred orientation when the step of applying the series of electric fields begins and optionally being applied first in the series if the balls of the first set are already in the first preferred orientation when the step of applying the series of electric fields begins,

a second electric field having an electric field strength between the first and second thresholds, the second electric field facilitating rotations of balls in each of the second and third sets so as to achieve the preferred rotational orientation of balls in the second set while possibly affecting the rotational orientation of balls of the third set but without affecting the rotational orientations of balls of the first set, the second electric field being applied second in the series if the balls of the second set are not already in the second preferred orientation after the application, if any, of the first electric field and optionally being applied second in the series if the balls of the second set are already in the second preferred orientation after the application, if any, of the first electric field, and

a third electric field having an electric field strength between the second and third thresholds, the third electric field facilitating rotations of balls in the third set only so as to achieve the preferred rotational orientation of balls in the third set without affecting the rotational orientations of balls of the first and second sets, the third electric field being applied third in the series if the balls of the third set are not already in the third preferred orientation after the application, if any, of the first electric field and the application, if any, of the second electric field and optionally being applied third in the series if the balls of the third set are already in the third preferred orientation after the application, if any, of the first electric field and the application, if any, of the second electric field.

18. The method of claim 17 wherein:

the step of determining the first preferred rotational orientation comprises selecting a first preferred angle, the first preferred angle being adjustable over a continuous range of angles, the range including angles from 0 degrees to at least 90 degrees;

the step of determining the second preferred rotational orientation comprises selecting a second preferred angle, the second preferred angle being adjustable over the continuous range of angles;

the step of determining the third preferred rotational orientation comprises selecting a third preferred angle, the third preferred angle being adjustable over the continuous range of angles; and

the step of applying the series of electric fields comprises

applying the first field of the series, if at all, by applying an electric field having an electric field vector oriented at the first preferred angle with respect to a reference vector, the reference vector being a vector normal to a planar portion of the substrate front surface in a vicinity of the preferred region, the applied first field influencing balls of the first, second, and third sets to rotate,

applying the second field of the series, if at all, by applying an electric field having an electric field vector oriented at the second preferred angle with respect to the reference vector, the applied second field influencing balls of the second and third sets only to rotate, and

applying the third field of the series, if at all, by applying an electric field having an electric field vector oriented at the third preferred angle with respect to the reference vector, the applied third field influencing balls of the third set only to rotate.

19. The method of claim 17 wherein

the first set of balls includes a plurality of balls each associated with a threshold of a first plurality of thresholds, each threshold of the first plurality being less than or equal to the first threshold and greater than the second threshold, the first plurality including at least two different thresholds, a rotation of each ball of the first set being facilitated when the ball thus rotatably disposed in the first substrate layer is subjected to a nonoscillating electric field having an electric field strength exceeding the threshold with which the ball is associated,

the second set of balls includes a plurality of balls each associated with a threshold of a second plurality of thresholds, each threshold of the second plurality being less than or equal to the second threshold and greater than the third threshold, the second plurality including at least two different thresholds, a rotation of each ball of the second set being facilitated when the ball thus rotatably disposed in the second substrate layer is subjected to a nonoscillating electric field having an electric field strength exceeding the threshold with which the ball is associated, and

the third set of balls includes a plurality of balls each associated with a threshold of a third plurality of thresholds, each threshold of the third plurality being less than or equal to the third threshold, the third plurality including at least two different thresholds, a rotation of each ball of the third set being facilitated when the ball thus rotatably disposed in the third substrate layer is subjected to a nonoscillating electric field having an electric field strength exceeding the threshold with which the ball is associated;

and wherein;

the step of determining the first preferred rotational orientation comprises

selecting a first intermediate threshold less than or equal to the first threshold and greater than the second threshold so as to determine a first preferred subset of balls, the first preferred subset comprising any balls of the first set having associated thresholds less than or equal to the selected first intermediate threshold,

determining as the first preferred rotational orientation a rotational orientation for any balls of the first set not in the first preferred subset, and

determining a preferred rotational orientation for balls of the first preferred subset;

the step of determining the second preferred rotational orientation comprises

selecting a second intermediate threshold less than or equal to the second threshold and greater than the third threshold so as to determine a second preferred subset of balls, the second preferred subset comprising any balls of the second set having associated thresholds less than or equal to the selected second intermediate threshold,

determining as the second preferred rotational orientation a rotational orientation for any balls of the second set not in the second preferred subset, and

determining a preferred rotational orientation for balls of the second preferred subset;

the step of determining the third preferred rotational orientation comprises

selecting a third intermediate threshold less than or equal to the third threshold so as to determine a third preferred subset of balls, the third preferred subset comprising any balls of the third set having associated thresholds less than or equal to the selected third intermediate threshold,

determining as the third preferred rotational orientation a rotational orientation for any balls of the third set not in the third preferred subset, and

determining a preferred rotational orientation for balls of the third preferred subset; and

the step of applying the series of electric fields comprises applying each of the first, second, and third electric fields of the series, and the series further includes

a first additional electric field having an electric field strength between the first and first intermediate thresholds, the first additional electric field facilitating rotations of balls in the first preferred subset and in the second and third sets so as to achieve the preferred rotational orientation of balls in the first preferred subset while possibly affecting the rotational orientations of balls of the second and third sets but without affecting the rotational orientations of balls of the first set not in the first preferred subset, the first additional electric field being applied between the first and second electric fields of the series if the preferred orientation of balls of the first preferred subset is different from the first preferred rotational orientation and the first preferred subset includes at least one ball of the first set and does not include all the balls of the first set,

a second additional electric field having an electric field strength between the second and second intermediate thresholds, the second additional electric field facilitating rotations of balls in the second preferred subset and in the third set so as to achieve the preferred rotational orientation of balls in the second preferred subset while possibly affecting the rotational orientation of balls of the third set but without affecting the rotational orientations of balls of the first set and balls of the second set not in the second preferred subset, the second additional electric field being applied between the second and third electric fields of the series if the preferred orientation of balls of the second preferred subset is different from the second preferred rotational orientation and the second preferred subset includes at least one ball of the second set and does not include all the balls of the second set, and

a third additional electric field having an electric field strength between the third and third intermediate thresholds, the third additional electric field facilitating rotations of balls in the third preferred subset only so as to achieve the preferred rotational orientation of balls in the third preferred subset without affecting the rotational orientations of balls of the first and second sets and balls of the third set not in the third preferred subset, the third additional electric field being applied after the third electric field of the series if the preferred orientation of balls of the third preferred subset is different from the third preferred rotational orientation and the third preferred subset includes at least one ball of the third set and does not include all the balls of the third set.

20. A method of using an optical modulation device, the device comprising first, second, and third pluralities of electrically and optically anisotropic spheroidal balls rotatably disposed in a substrate having a surface, each ball of the first plurality including a component region of a first chromatic color, each ball of the second plurality including a component region of a second chromatic color, each ball of the third plurality including a component region of a third chromatic color, the method comprising the steps of:

establishing a first array of addressable image elements for the device by bringing the device into a first operative coupling with an addressing electrode assembly, the assembly defining an addressing origin, a point on the substrate surface being aligned with the addressing origin when the device is in the first operative coupling;

with the addressing electrode assembly, addressing at least one image element of the first array to facilitate a rotation of at least one spheroidal ball of the device in a vicinity of the addressed image element of the first array;

removing the device from the first operative coupling with the addressing electrode assembly;

establishing a second array of addressable image elements for the device by bringing the device into a second operative coupling with the addressing electrode assembly, the point on the substrate surface being displaced through a directed distance with respect to the addressing origin when the device is in the second operative coupling, the directed distance having a magnitude greater than zero; and

with the addressing electrode assembly, addressing at least one image element of the second array to facilitate a rotation of at least one spheroidal ball of the device in a vicinity of the addressed image element of the second array.

21. The method of claim 20 wherein:

the step of addressing at least one image element of the first array comprises addressing a first set of image elements in the first array so as to produce a color image with the device, the color image having the first, second, and third chromatic colors; and

the step of addressing at least one image element of the second array comprises addressing a second set of image elements in the second array, the elements of the second set corresponding one-to-one with the elements of the first set, so as to produce with the device a displaced version of the image, the displaced version being obtained by translating the color image through a displacement across the substrate surface, the displacement having a magnitude equal to said directed distance.

22. 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 comprising a plurality of spheroidal balls disposed in the substrate,

each ball comprising a plurality of component regions including

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

a second component region having a second optical modulation characteristic,

at least one component region of each ball being transparent, each 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,

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 chromatic 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 chromatic color observable throughout a predominant portion of the observable area, and

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

23. The device of claim 22 wherein each element has a plurality of additional operational states, each additional state comprising a combination of at least two of the first, second, and third operational states, each additional state being associated with an appearance providing a superposition of the colors provided by each of the operational states constituting the combination, the superposition of colors thus being a superposition of at least two of the first, second, and third chromatic colors, the superposition of colors being observable throughout a predominant portion of the observable area.

24. A material comprising:

a substrate having a surface and comprising a plurality of layers including first and second layers, the first layer including a first region, the first region being observable by an observer situated favorably to observe the substrate surface, the second layer including a second region, the second region being disposed behind the first region with respect to the observer;

a first plurality of optically anisotropic spheroidal balls disposed in the first layer, the first plurality including a ball disposed in the first region of the first layer and having a transparent portion, the transparent portion of said ball being disposable between the observer and the second region of the second layer by orienting said ball in a preferred rotational orientation with respect to the observer, thereby facilitating observation by the observer of light emerging from the second region of the second layer in a vicinity of said ball and passing through the transparent portion of said ball and thence towards the substrate surface; and

a second plurality of optically anisotropic spheroidal balls disposed in the second layer;

each ball of each of the first and second pluralities 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 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.