WO1995029555B1 - Lighting-independent color video display - Google Patents

Abstract

An electrostatically actuated color video display is disclosed which can be illuminated by backlighting transmitted through the display and by reflected ambient light to have good visibility in both bright daylight and in subdued or dim light. To display full-color dynamically changing images from an electronic video signal the functions of creating the image and of generating color light rays for use in the image are separated. A preferred embodiment employs a pixellated color screen having rectangular cells of alternate red, green, blue and a somewhat opaque white color and a shuttering mask comprising an array of selectively actuatable light-modulating capacitors with black movable electrodes that when retracted are in registration with and present an open light path to individual color screen cells and when extended, present a continuous black screen appearance.

Claims

AMENDED CLAIMS

[received by the International Bureau on 11 December 1995 (11.12.95);

original claims 1, 2, 4, 14-16, 18 and 19 amended; new claims 21 and 22 added;

remaining claims unchanged (7 pages)]

Claim 1. A flat-panel video display having a layered matrix structure and employing light-modulating capacitor pixels, said layered matrix structure comprising:

i) a movable electrode layer having a composite array of movable electrodes disposed toward a viewer, said movable electrodes having an open, retracted position providing a clear light path past said movable electrode and a second, extended position in which said light path is occluded by said movable electrode;

ii) a dielectric layer having a transparent sheet- like dielectric member in capacitive contact with said movable electrodes in said extended position of said movable electrodes; iii) a control electrode layer having an array of translucent control electrodes contacting and in electrostatic engagement with a second surface of said dielectric member to control said movable electrodes, said movable electrodes, said dielectric member and said control, electrodes providing an array of light- modulating capacitors;

iv) drive circuitry to apply drive voltages

selectively between said fixed electrodes and said movable electrodes to effect movement of selected movable electrodes; and

v) a color screen layer disposed adjacent to said array of light-modulating capacitors and on an opposite side thereof with respect to said viewer;

whereby movement of an individual movable electrode into a retracted, open position displays one of said segments of said colored screen layer to a viewer and multiple said movable electrodes can be actuated to display an image area composed of multiple said colored screen segments to said viewer; characterised in that to provide a display viewable by either transmitted or reflected light the color screen layer is composed of colored screen segments comprising a translucent material having a colorant dispersed

therethrough and individual said colored screen segments display a similar hue-modulating appearance by either transmitted or reflected light.

Claim 2. A flat-panel video display according to Claim 1 characterised by comprising selective control means to control the extent of excursion of individual electrodes and control of pixel intensity and characterised in that each said movable elpctrodc; has a conductive electrode surface to contact said dielectric member, Claim 3. A flat-panel vidoo display according to Claim 2 characterized by furthor comprising a source of

illumination behind said colored screen, with respect to said viewer, whereby said screen pixels are back lighted. Claim 4. A flat-panel video display according to Claim 2 characterised in that said colored screen is segmented into a mosaic of colored cells and wherein adjacent, colored cells have different visual appearances and are aligned with said movable electrodes whereby adjacent electrodes can be operated to present said different.

visual appearances of said colored cells, in a selective manner.

Claim S. A flat-panel video display according to Claim 4 characterized in that each said color screen cell has a shape corresponding with the shape of a movable

electrode, and is optically in registration with said movable electrodes, whereby actuation of an individual movable electrode can move it to display the visual appearance of a single color screen cell. Claim 6. A flat-panel video display according to Claim 4 characterized in that said electrodes and said color screen cells each have a shape selected from the group consisting of rectangular, triangular and hexagonal. Claim 7. A flat-panel video display according to Claim 4. characterized in that said cells are arranged in adjacent groups of four cells having the appearance of three primary colors and white. Claim 8. A flat-panel video display according to Claim 7 characterized in that said three primary colors are red, green and blue.

Claim 9. A flat-panel video display according to Claim 4 characterized in that said colored screen is composed of multiple layers of colorant-loaded transparent material arranged in patterns to give said individual cells desired visual characteristics. claim 10. A flat-panel video display according to Claim 9 characterised in that said multiple layers of plastic comprise four layers having respectively a red, a green, a blue and a white appearance, said four layers each being patterned to provide desired individual cell characteristics.

Claim 11. A flat-panel video display according to Claim 10 characterized in that said plastic layers of said colored screen are comprised of a polyester plastic and said patterns are formed by laser ablation.

Claim 12. A flat-panel video display according to claim 2 characterized in that said colored screen is manufactured by imprinting colored inks on to a substrate, claim 13. A fl at-panel video di splay according to Claim 4 characterized in that said cells and said movable electrodes have corresponding and similar rectangular sisee and shapes and said colored cells are arranged in repeating groups of four, each said group of lour cells comprising a red cell, a green cell, a blue cell and a white cell.

Claim 14. A flat-panel video display according to Claim 2 characterized in that said movable electrodes arc electrically connected in rows and said fixed control electrodes are electrically connected in columns wherein said drive circuitry includes row-and-column diode decoding means to provide selective actuation of qroups of individual movable electrodes. Claim 15. A flat-panel video display according to claim 2 characterized in that said movable electrodes present a black appearance to said viewer in said extended position and are configured and disposed ior said composites array of movable electrodes; to provide the appearance of a substantially continuous black screen at an intended viewing distance when said electrodes are all in said extended positions.

Claim 16. A flat-panel video display according to Claim 2 characterized in that said movable electrodes have an extent of movement which extent is in the range of about 0.01 inches to 1 inch.

Claim 17. A flat-panel video display according to Claim 16 characterized in that said video display is generally rectangular and comprises an array of from 200 to 2,000 pixels by from 200 to 2,000 pixels.

Claim 18. A flat-panel video display having a layered matrix structure employing light-modulating capacitor pixels and being characterized by comprising: i) a movable electrode layer having a composite array of movable electrodes disposed toward a viewer, said movables electrodes each having a conductive layer and being movable between an open, retracted position providing a clear light path past said movable electrode and a second, extended position in which said light path is occluded by said movable electrode and said movable electrodes present a black appearance to said viewer, said movable electrodes bαing configured and disposed for said composite array of movable electrodes to provide the appearance of a substantially continuous black screen at an intended viewing distance when said electrodes are all in said extended positions said movable electrodes having a controllable extent of excursion to permit continuous variation of each pixel's color intensity under electrical control;

ii) a dielectric layer having a transparent sheet- like dielectric member in capacitive contact with said movable olectrodes, said movable electrode conductive layer being in electrical contact with said dielectric layer in said extended position of said movable electrodes; iii) a control electrode layer having an array of translucent control electrodes contacting and in electrostatic engagement with a second surface of said dielectric member to control said movable electrodes, said movable

electrodes, said dielectric member and said control electrodes providing an array of light- modulating capacitors;

iv) drive circuitry to apply drive voltages

selectively between said fixed electrodes and said movable electrodes to effect movement of selected movable electrodes; v) a translucent color screen disposed adjacent to said array of light-modulating capacitors and on an opposite side thereof with respect to said viewer, said color screen being segmented into a mosaic of colored cells, said colored cells each having a shape corresponding with that of a movable electrode, and being in optical registration with said movable electrodes, said color screen cells being arranged in adjacent groups of four cells each having the appearance of one of three primary colors and white, said colored screen displaying similar colorant-modulated appearances by both transmitted and reflected light, said color screen cells and said light- modulating capacitors being cooperative to provide said light-modulating capacitor pixels said color screen being composed of colored screen segments comprising a translucent material having a colorant dispersed therethrough and said colored screen segments displaying a similar hue-modulated appearance by either transmitted or reflected light; and vi) a source of illumination behind said colored screen, with respect to said viewer to back light said screen pixels;

whereby movement of an individual movable electrode into a retracted, open position displays one of said color screen cells to a viewer, adjacent electrodes can be operated to present said different visual appearances of said colored cells in a selective manner and whereby multiple said movable electrodes can be actuated to display a composed image area of said colored screen segments to said viewer. Claim 19. A multicolor reflective video display for displaying electronically genrrated dynamically changing multicolor images to a viewer at a designated viewing distance, said video display comprising light modulating capacitor pixels each having a capacitively movable electrode to modulate light and being characterized by comprising:

i) a passive color screen segmented into a mosaic of reflective colored cells fixedly arranged in similar groups of adjacent colored cells said adjacent cells of a group having different visual appearances, said different visual appearances being optically miκable at said designated viewing distance;

ii) a dynamic image-composition mask positioned between said passive color screen and said viewer and having imago composition means for selectively filtering and masking modulated light received from said color screen to create a desired, colored video image.

Claim 20. A multicolor video display according to claim 19 characterized in that said dynamic image-composition mask has an array of individually controllable openable shutters registering optically with cells in the color screen so that an opened shutter displays a singlo color screen cell.

Claim 21, A multicolor video display according to claim 19 characterized by comprising selective control means to control the extent of excursion of individual electrodes and control of pixel intensity and characterized in that each said movable electrode has a conductive electrode surface to contact said dielectric member.

Claim 22. A flat-panel video display according to claim 19, 20 or 21 characterised in that said colored screen is manufactured by imprinting colored inks on to a

substrate, STATEMENT UNDER ARTICLE 19

Claim 1 has been amended to further acknowledge the prior literature, for example as constituted by Bozler, by referencing a composite color screen, clause (v). With regard to claims 1-18, only one reference, that to Bozler, lies in the particular field of display devices having light-modulating eapaeilive pixel elements, in which field applicant has considerable experience, as may be seen from the references to some of his prior patents in the specification of this application.

Applicant's invention as now claimed, for the first time provides a full-color video display having the benefits of low-power, low-cost eapaeilive pixels which can be viewed by cither transmitted or reflected light so that, for example a computer or television screen may be used both indoors and outdoors in blight sunlight. In addition to providing a unique capability, applicant's light capacitor based technology is admirably suited to providing flat panel video displays because it requires little energy to run and has low manufacturing costs.

Claim 1 has been amended to incorporate the subject matter of old claim 2 and to be directed to a video display that is viewable by both transmitted and reflected light, unlike Bozler.

Bozler does not disclose a color video display viewable by both reflected and transmitted light nor does the disclose applicant's claimed video display having colored screen segments which display a similar colorant-modulated appearance by both transmitted and reflected light.

Bozler states at column 8 lines 57 that "Light may pass through the display in either direction". However this description applies to the structure of Figures 1 to 5 before the color screen constituted by filters 72, 74 and 76, or by fillers 84, 86 and 88 (Figure 7), is added. With regard to his color display made using color fillers, as shown in Figure 6 (column 8, lines 58 to 59) Bossier states that "light is passed in the direction of the arrows." (line 65).

Thus Bozler does not disclose a color video display through which light can pass in "both directions" and in which the display is viewable by either reflected or transmitted light..

Nor does Bozler disclose color screen segments which display similar

colotant-modulated appearances by either transmitted or reflected light, as now required by applicant's amended claim 1. Bozler merely offers an unqualified suggestion of the use of a layer of juxtaposed color filters. A color filter may not necessarily have a similar appearance by reflected light to its transmitted light appearance. To take a simple example, color film transparencies present a clear image when viewed by transmitted light but tend to be dark and unrecognizable by reflected fight. Clearly such a filter material would not be useful for a video display that could be used both indoors and outdoors.

Claim 2 has been amended to recite a display having pixels providing continuously variable color intensity control, whereas Bozler's pixels are bistable, having either an open or closed state. Accordingly, Bozler's device cannot provide continuous color intensity variation and is not suitable for present-day mass-market electronic video screens which require a substantial color range. New claim 2 further distinguishes from Bozler by including language reciting that the movable electrode has a conductive electrode surface to contacting the dielectric member. This feature avoids potential difficulties with triboeleetric charges that may cause the movable electrode to stick to the dielectric.

Claims 4, 14 and 15-16 have been amended to depend from claim 2 rather than claim 1. Claim 12 has been amended to depend from claim 2 and to recite that the colored screen is manufactured by imprinting colored inks on to a substrate.

Claim 19 has been amended to relate to a reflective video display having reflective colored cells comprising a segmented colored screen, which cells arefixedly arranged and to specify that the display comprises light-modulating capacitor pixels, thereby clearly distinguishing from Takimoto.

The simple elegance of applicant's reflective multicolor video display as now claimed in claim 19 is not suggested by Bozler who uses an unduly complex ("advanced") structure for a reflective display, Fig. 10, col. 9, lines 22-28.

New claims 21 and 22 depend from claim 19 and set forth the features of claims 2 and 12 respectively, further distinguishing from Bozler.