FreshPatents.com Logo
stats FreshPatents Stats
n/a views for this patent on FreshPatents.com
Updated: August 24 2014
newTOP 200 Companies filing patents this week


    Free Services  

  • MONITOR KEYWORDS
  • Enter keywords & we'll notify you when a new patent matches your request (weekly update).

  • ORGANIZER
  • Save & organize patents so you can view them later.

  • RSS rss
  • Create custom RSS feeds. Track keywords without receiving email.

  • ARCHIVE
  • View the last few months of your Keyword emails.

  • COMPANY DIRECTORY
  • Patents sorted by company.

Follow us on Twitter
twitter icon@FreshPatents

Bistable electrowetting picture element

last patentdownload pdfdownload imgimage previewnext patent


20140016178 patent thumbnailZoom

Bistable electrowetting picture element


A bistable electrowetting picture element that has both stable “On” and “Off” states in which no power is consumed, and a switching voltage threshold is disclosed. Displays using such picture elements may be either passive or active matrix addressed. A picture element contains two immiscible, fluids within a space between two surfaces. One of the fluids is an electro-conductive, polar liquid, such as to water. The other fluid is a non-polar liquid such as silicone oil. The picture element is electrically switchable between two states, both of which are maintained without a voltage being applied. In one state the light absorbing, non-polar liquid adjoins a region of one of the surfaces, while in the second state it adjoins another region on the other surface. The region adjoined to in the second state differs in area from the region adjoined to in the first state, thereby providing “On” and “Off” states.
Related Terms: Silicon Joins Matrix Polar

USPTO Applicaton #: #20140016178 - Class: 359290 (USPTO) -


Inventors: Roy Rosser

view organizer monitor keywords


The Patent Description & Claims data below is from USPTO Patent Application 20140016178, Bistable electrowetting picture element.

last patentpdficondownload pdfimage previewnext patent

CLAIM OF PRIORITY

This application is a continuation of and claims priority to U.S. Ser. No. 12/045,315 filed Mar. 10, 2008, the contents of which are fully incorporated herein by reference.

This application is further related to, and claims priority from, U.S. Provisional Patent application No. 60/893,669 filed on Mar. 8, 2007 by R. Rosser, the contents of which are hereby incorporated by reference. This application is also related to U.S. Provisional Patent applications No. 60/894,210 filed on Mar. 10, 2007, No. 60/908,103 filed on Mar. 26, 2007, No. 60/939,061 filed on May 19, 2007, No. 60/943,752 filed on Jun. 13, 2007 and No. 61/016,750 filed on Dec. 26, 2007, the contents of all of which are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to the field of electrowetting displays. More specifically, the present invention relates to a method, apparatus, and system for bistable, electrowetting picture elements and displays.

BACKGROUND OF THE INVENTION

In the $20 billion mobile display market, the dominant display technology is liquid crystal (LCD) technology. This dominance may be measured by the fact that in 2006, of the 1 billion plus displays that were shipped for mobile devices, such as cellular phones, over 95% used LCD technology.

Despite their present dominance, LCD displays have the drawback of requiring back-lighting that can be very power consuming. This is of particular concern in battery operated, mobile devices such as cellular phones. In a typical cellular phone, back-lighting consumes about 80% of the battery power required to operate the phone.

Because of this drawback, there is considerable interest in alternative display technologies, particularly reflective display technologies that make use of ambient light rather than requiring backlighting. One alternative, reflective display technology that has received considerable attention is electrowetting display technology.

Electrowetting display technology uses the well-known electrowetting effect, in which the wetting properties of a surface can be altered by applying a voltage, to manipulate a colored oil from covering an entire picture element to beading up to cover only a small fraction of the picture element. When the oil covers the entire picture element, all the light is absorbed by the dye coloring the oil and the picture element is in an “Off” state. When the oil covers only a portion of the picture element, light can be transmitted—or reflected—by the picture element and it is in an “On” state. Reflective electrowetting displays may be made in which no light is reflected in the “Off” state and about 65% of the incident light is reflected in the “On” state. This compares to paper in which white paper reflects about 70% of the incident light, while black ink reflects almost none.

Electrowetting display technology has been described in detail in, for instance, US Patent publications no. 20050270672 by Feenstra et al. (Dec. 8, 2005), no. 20050213014 by Feenstra et al. (Sep. 29, 2005), no. 20050104804 by Feenstra et al. (May 19, 2005) no. 20060132404 by Hayes et al. (Jun. 22, 2006), no. 20050123243 Steckl et al. (Jun. 9, 2005) no. 20070031097 by Heikenfeld et al. (Feb. 8, 2007) the contents of all of which are hereby incorporated by reference.

FIGS. 1A and 1B show various components of an exemplary embodiment of prior art electrowetting display technology. A prior art, electrowetting picture element 10 typically has two immiscible fluids contained between an upper, hydrophilic surface 16 and a lower, hydrophobic surface 18. The immiscible fluids are typically a non-polar liquid 12, such as oil, and a polar liquid 14, such as water. The non-polar liquid 12 typically has added dyes or pigments to facilitate absorbing some, or all, of the incident light.

In an “Off” state, shown in FIG. 1A, the non-polar liquid 12 completely covers the hydrophobic surface 18 of the electrowetting picture element 10. In this “Off” state, incident light 22 is absorbed by the non-polar liquid 12 and any added dyes or pigments it may contain.

An “On” state of the prior art, electrowetting picture element 10 is achieved by applying a suitable voltage 24 between a transparent electrode 20 and the polar liquid 14. The transparent electrode 20 is electrically isolated from the polar liquid 14 by the hydrophobic surface 18 that is also a dielectric. The polar liquid 14 may have additives such as, but not limited to, acids, alkalis or salts or a combination thereof, to make the polar liquid 14 more conductive to electricity. The application of a suitable voltage 24 to such an arrangement results in the well-know electrowetting phenomenon in which the surface 18 becomes less hydrophobic. As surface 18 becomes less hydrophobic, the non-polar liquid 12 beads up, allowing the polar liquid 14 to come into contact with surface 18. As a result, some of the incident light 22 is no longer blocked by the non-polar liquid 12 and now emerges from the prior art, electrowetting picture element 10 as emergent light 26.

A significant draw back of the prior art, electrowetting picture element elements 10 are that they require a small, but continuous, voltage to be applied to maintain an “On” state. This means that when they are displaying an image, they are consuming power.

For many applications, including e-books, e-signage and mobile device displays, it is desirable to have both an “On” state as well as an “Off” state that require no power. Such a display element is typically termed a “bistable” display element.

SUMMARY

OF THE INVENTION

The present invention relates to a bistable electrowetting picture element that may be suitable for use in a display. The bistable, electrowetting picture element of this invention has both a stable “On” state and a stable “Off” state in which no power is consumed. In addition, the bistable, electrowetting picture element of this invention has a switching voltage threshold. As a result a display made of the electrowetting picture elements of this invention may be operated using either passive matrix addressing or active matrix addressing.

In a preferred embodiment, the bistable, electrowetting picture element contains two fluids that are immiscible with each other. The immiscible fluids are contained within a space between two surfaces that confront each other. One of the fluids is an electro-conductive or polar liquid such as, but not limited, to water. The other fluid is a non-polar liquid such as, but not limited to, oil or silicone oil that may also contain light absorbing dyes and pigments.

The picture element is electrically switchable between two states, both of which are maintainable without a voltage being applied. In one state the fluid that is a non-polar liquid adjoins a region of one of the surfaces, while in the second state, the fluid that is a non-polar liquid adjoins another region on the other surface. The region adjoined to in the second state differs in area from the region adjoined to in the first state. The amount of light absorbed by the picture element is proportional to the size of the region to which the light absorbing, non-polar liquid is adjoined. If, in the first state, the region corresponds to the entire area of the picture element, no light will be transmitted and the picture element will be in an “Off” state. If in the second state the region corresponds to some fraction of the area of the picture element, some light will be transmitted and the picture element will be in an “On” state.

These and other features of the invention will be more fully understood by references to the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A is a schematic cross-section of an exemplary embodiment of a prior art electrowetting picture element in an “Off” state.

FIG. 1B is a schematic cross-section of an exemplary embodiment of a prior art electrowetting picture element in an “On” state.

FIG. 2A is a schematic cross-section of an exemplary transmission mode bistable, electrowetting picture element of the present invention in an “Off” state.

FIG. 2B is a schematic cross-section of an exemplary transmission mode bistable, electrowetting picture element of the present invention in an “On” state.

FIG. 3 is a schematic cross-sectional view of an exemplary reflection mode, bistable, electrowetting picture element transitioning from an “Off” state to an “On” state and back again.

FIG. 4 is a schematic plan view of an exemplary bistable, electrowetting picture element transitioning from an “Off” state to an “On” state and back again.

FIG. 5 is a schematic cross-section of a further exemplary bistable, electrowetting picture element of the present invention in an “Off” state.

FIG. 6 is a schematic cross-section of a further exemplary bistable, electrowetting picture element of the present invention in an “On” state.

FIG. 7A shows a hydrophilic picture element defining barrier defining a single square picture element.

FIG. 7B shows a square picture element subdivided into four equal sub-picture regions.

FIG. 7C shows a square picture element subdivided into nine equal sub-picture regions.

FIG. 7D shows a square picture element subdivided into five equal sub-picture regions.

FIG. 8A shows a schematic plan view of a picture element that has four sub-picture regions in an “On” state.

FIG. 8B shows a schematic plan view of a picture element that has five sub-picture regions in an “On” state.

FIG. 8C shows a schematic plan view of a picture element that has nine sub-picture regions in an “On” state.

FIG. 9A shows a plan view of an exemplary picture element 60 divided into three regions of unequal area.

FIG. 9B shows a plan view of an exemplary structure of a lower electrode configured to drive the picture element of FIG. 9A.

FIG. 10 shows a schematic plan view of a multi-region structure.

FIG. 11 shows a schematic cross-sectional view of the multi-region structure of FIG. 10.

FIG. 12 shows a schematic cross-sectional view of the multi-region structure loaded with non-polar liquid.

FIG. 13 shows a schematic cross-sectional view of an exemplary configuration for loading a multi-region structure with non-polar liquid.

FIG. 14 shows a schematic cross-sectional view of a further exemplary configuration for loading a multi-region structure with non-polar liquid.

FIG. 15 shows a schematic cross-sectional view of an exemplary configuration for loading a roll of multi-region structure with non-polar liquid.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is innovative over the prior art in providing a simple but novel, bistable electrowetting display technology. To understand the inventive concepts of the present invention it is useful to consider the accompanying drawings in which, as far as possible, like numbers represent like elements.

Although every reasonable attempt is made in the accompanying drawings to represent the various elements of the embodiments in relative scale, it is not always possible to do so with the limitations of two-dimensional paper. Accordingly, in order to properly represent the relationships of various features among each other in the depicted embodiments and to properly demonstrate the invention in a reasonably simplified fashion, it is necessary at times to deviate from absolute scale in the attached drawings. However, one of ordinary skill in the art would fully appreciate and acknowledge any such scale deviations as not limiting the enablement of the disclosed embodiments.

FIGS. 2A and 2B shows various components of an exemplary bistable, electrowetting display picture element 30 that can be utilized to implement the inventive concepts described herein. The bistable, electrowetting display picture element 30 includes two immiscible fluids contained between an upper, hydrophilic surface 16 and a lower, hydrophobic surface 18. In addition, the bistable, electrowetting display picture element 30 includes a second, hydrophobic region 28 that may cover part of the hydrophilic surface 16. The immiscible fluids may, for instance be a non-polar liquid 12, such as oil, and a polar liquid 14 such as water. The non-polar liquid 12 may contain dyes or pigments to facilitate light absorption. The polar liquid 14 may contain salts, acids or alkalis to enhance the electrical conductivity of the liquid. The polar liquid 14 may also, or instead, contain additives such as, but not limited to, glycerol or alcohol, or some combination thereof, to allow the device to operate over more extended temperature ranges.

In an “Off” state of the bistable, electrowetting display picture element 30, shown in FIG. 2A, the non-polar liquid 12 is in contact with the lower hydrophobic surface 18 and covers the entire lower surface 18. In the “Off” state, incident light 22 is absorbed by the non-polar liquid 12 over the entire bistable, electrowetting display picture element 30.



Download full PDF for full patent description/claims.

Advertise on FreshPatents.com - Rates & Info


You can also Monitor Keywords and Search for tracking patents relating to this Bistable electrowetting picture element patent application.
###
monitor keywords



Keyword Monitor How KEYWORD MONITOR works... a FREE service from FreshPatents
1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored.
3. Each week you receive an email with patent applications related to your keywords.  
Start now! - Receive info on patent apps like Bistable electrowetting picture element or other areas of interest.
###


Previous Patent Application:
Electrochromic nickel oxide simultaneously doped with lithium and a metal dopant
Next Patent Application:
Cell driven by electric field and operation method thereof
Industry Class:
Optical: systems and elements
Thank you for viewing the Bistable electrowetting picture element patent info.
- - - Apple patents, Boeing patents, Google patents, IBM patents, Jabil patents, Coca Cola patents, Motorola patents

Results in 1.03908 seconds


Other interesting Freshpatents.com categories:
Electronics: Semiconductor Audio Illumination Connectors Crypto

###

Data source: patent applications published in the public domain by the United States Patent and Trademark Office (USPTO). Information published here is for research/educational purposes only. FreshPatents is not affiliated with the USPTO, assignee companies, inventors, law firms or other assignees. Patent applications, documents and images may contain trademarks of the respective companies/authors. FreshPatents is not responsible for the accuracy, validity or otherwise contents of these public document patent application filings. When possible a complete PDF is provided, however, in some cases the presented document/images is an abstract or sampling of the full patent application for display purposes. FreshPatents.com Terms/Support
-g2--0.415
     SHARE
  
           

FreshNews promo


stats Patent Info
Application #
US 20140016178 A1
Publish Date
01/16/2014
Document #
14028529
File Date
09/16/2013
USPTO Class
359290
Other USPTO Classes
International Class
02B26/00
Drawings
8


Silicon
Joins
Matrix
Polar


Follow us on Twitter
twitter icon@FreshPatents