Electrowetting elements and optical display devices

• US 8,199,409 B2
• Filed: 11/20/2009
• Issued: 06/12/2012
• Est. Priority Date: 05/23/2007
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Samsung LCD Netherlands R&D Center, BV (Amazon.com, Inc.)
• Inventors: Hayes, Robert, Massard, Romaric, Van De Weijer-Wagemans, Melanie Maria Hubertina
• Primary Examiner(s): Jones, James
• Application Number:
  US12/622,957
• Publication Number:
  US 20100220380A1
• Time in Patent Office: 935 Days
• Field of Search: 359/290, 359/291, 359665-666
• US Class Current: 359/665
• CPC Class Codes: G02B 26/005 based on electrowetting

Abstract

The present invention relates to reducing backflow in an electrowetting element for modifying a radiation beam characteristic. The electrowetting element comprises a first and a second fluid which are immiscible with each other and are switchable between a first configuration and a second configuration by application of a voltage across at least one of the first and second fluids. There is a tendency for backflow of the second fluid from the first configuration to the second configuration when the second fluid is switched to be provided in the first configuration. The electrowetting element comprises a backflow reducer arranged for reducing the backflow of the second fluid from the first configuration to the second configuration when the second fluid is switched to be provided in the first configuration.

Claims

1. A method of reducing backflow in an electrowetting element, said electrowetting element being arranged for modifying a radiation beam characteristic and comprising a first and a second fluid which are immiscible with each other and are switchable between a first configuration and a second configuration by application of a voltage across at least one of the first and second fluids, there being a tendency for backflow of the second fluid from the first configuration to the second configuration when the second fluid is switched to be provided in the first configuration,

wherein the method includes reducing the backflow of the second fluid from the first configuration to the second configuration when the second fluid is switched to be provided in the first configuration, by providing the electrowetting element with a backflow reducer.

22. A method according to claim 1, wherein the first configuration is adopted when the voltage is applied and the second configuration is adopted without the voltage applied, and the tendency for backflow of the second fluid from the first configuration to the second configuration occurs when the voltage is applied.

2. A use of a backflow reducer to reduce backflow in an electrowetting element, said electrowetting element being arranged for modifying a radiation beam characteristic and comprising a first and a second fluid which are immiscible with each other and are switchable between a first configuration and a second configuration by application of a voltage across at least one of the first and second fluids, there being a tendency for backflow of the second fluid from the first configuration to the second configuration when the second fluid is switched to be provided in the first configuration,

wherein the electrowetting element comprises the backflow reducer, the backflow reducer being arranged for reducing the backflow of the second fluid from the first configuration to the second configuration when the second fluid is switched to be provided in the first configuration.

23. A use of the backflow reducer according to claim 2, wherein the first configuration is adopted when the voltage is applied and the second configuration is adopted without the voltage applied, and the tendency for backflow of the second fluid from the first configuration to the second configuration occurs when the voltage is applied.

3. An electrowetting element for modifying a radiation beam characteristic, said electrowetting element comprising a first and a second fluid which are immiscible with each other and are switchable between a first configuration and a second configuration by application of a voltage across at least one of the first and second fluids, there being a tendency for backflow of the second fluid from the first configuration to the second configuration when the second fluid is switched to be provided in the first configuration,

wherein the electrowetting element comprises a backflow reducer arranged for reducing the backflow of the second fluid from the first configuration to the second configuration when the second fluid is switched to be provided in the first configuration.

4. An electrowetting element according to claim 3, wherein the backflow reducer is arranged outside of the first and second fluids.

5. An electrowetting element according to claim 3, wherein at least one of the first and second fluids includes the backflow reducer.

6. An electrowetting element according to claim 3, wherein said backflow reducer is arranged to reduce said backflow when, by continuous application of a voltage across at least one of said first and second fluids, the second fluid is switched to be provided in the first configuration.

7. An electrowetting element according to claim 3, wherein said backflow reducer is arranged to modify interfacial tension properties of an interface between said first and second fluids.

8. An electrowetting element according to claim 3, wherein said backflow reducer is arranged to modify surface tension properties and/or electrical properties of at least one of said first and second fluids.

9. An electrowetting element according to claim 3, wherein said backflow reducer is arranged to modify electrical properties of at least one of said first and said second fluids at an interface between said first and second fluids.

10. An electrowetting element according to claim 3, wherein said backflow reducer includes a compound with a polarity and/or a stereochemistry arranged to reduce backflow.

11. An electrowetting element according to claim 5, wherein said backflow reducer includes a dye.

12. An electrowetting element according to claim 11, wherein said dye includes an anthraquinone dye having the general formula:

13. An electrowetting element according to claim 12, wherein any of S, V, W, Z is an alkyl amine having the general formula:

—

NH—

(CH₂)_n2—

CH₃,

wherein n2=1 to 20, and optionally said anthraquinone dye has a formula selected from the group consisting of;

14. An electrowetting element according to claim 11, wherein said dye includes an azo dye having the general formula:

15. An electrowetting element according to claim 11, wherein said dye includes a Foron dye,

wherein optionally said Foron dye has a formula selected from the group consisting of:

16. An electrowetting element according to claim 5, wherein at least one of said first and second fluids includes an electrolyte arranged to reduce backflow,

wherein said electrolyte optionally includes an alkali metal halide, wherein said alkali metal is selected from the group comprising:

Li, Na and K, and said halide is selected from the group comprising;

Cl, Br and I,

wherein said electrolyte optionally includes a diol having the general formula

HO—

(CH₂)_n5—

0H, or a triol having the general formula HO—

(CH₂)_n6—

COH—

(CH₂)_n7—

OH, wherein any of n5, n6 and n7=1 to 20, and

wherein said diol optionally includes ethane-1,2-diol and said triol includes propane-1,2,3-triol.

17. An electrowetting element according to claim 5, wherein said backflow reducer includes a surfactant which is optionally an anionic surfactant which is optionally sodium dodecyl sulphate or an alkyl benzene sulphonate, or the surfactant is optionally a cationic surfactant which optionally has the following general formula:

18. An electrowetting element according to claim 3, wherein said first fluid includes water.

19. An electrowetting element according to claim 3, wherein said second fluid includes at least one compound selected from the following group:

an alkane, silicone oil and a bicyclo alkane.

20. An electrowetting element according to claim 19, wherein said alkane is decane or hexadecane, and said bicyclo alkane is bicyclo-4.4.0-decane.

21. An optical display device for providing an image, wherein said optical display device includes at least one electrowetting element in accordance with claim 3.

24. An electrowetting element according to claim 3, wherein the first configuration is adopted when the voltage is applied and the second configuration is adopted without the voltage applied, and the tendency for backflow of the second fluid from the first configuration to the second configuration occurs when the voltage is applied.