Methods for producing droplets for use in capsule-based electrophoretic displays

• US 6,377,387 B1
• Filed: 04/06/2000
• Issued: 04/23/2002
• Est. Priority Date: 04/06/1999
• Status: Expired due to Term

• Current Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Original Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Inventors: Loxley, Andrew L., Duthaler, Gregg M.
• Primary Examiner(s): Ben, Loha
• Application Number:
  US09/543,639
• Time in Patent Office: 747 Days
• Field of Search: 359/296, 359/452, 264/4, 264/4.1, 264/4.3, 264/8, 264/15, 345/108, 345/107, 345/105, 424/450, 424/1.21, 424/9.52
• US Class Current: 359/296
• CPC Class Codes: B01F 23/4111 using vibrations
• CPC Class Codes: B01F 25/313 wherein additional components are introduced in the centre of the conduit
• CPC Class Codes: B01F 31/85 with a vibrating element inside the receptacle
• CPC Class Codes: B01F 35/71791 using ink jet heads or cartridges, e.g. of the thermal bubble jet or piezoelectric type
• CPC Class Codes: B01J 13/02 Making microcapsules or microballoons for medical preparations A61K9/50

Abstract

Methods are provided for forming a dispersion of substantially uniform droplets. An internal phase that includes a plurality of particles suspended in a first fluid is provided and an external phase including a second fluid is provided. The internal phase is vibrated and the internal phase is applied to the external phase. Either the internal phase or a combination of the internal and external phases form a series of droplets or complex droplets of substantially uniform size.

Claims

1. A method for forming substantiall3y uniform droplets, the method comprising the steps of:

(a) providing a non-aqueous internal phase comprising a plurality of particles suspended in a first fluid;

(b) providing an external phase comprising a second fluid;

(c) vibrating the internal phase; and

(c) applying the internal phase to the external phase, wherein a series of droplets of substantially uniform size is formed.

2. The method of claim 1 wherein the first fluid comprises an oil.

3. The method of claim 1 wherein the second fluid comprises an aqueous solution.

4. The method of claim 1 wherein the step of applying the internal phase to the external phase comprises containing the internal phase in a structure and pressurizing the internal phase, thereby to cause the internal phase to issue from the structure into the external phase.

5. The method of claim 4 wherein the internal phase issues through at least one aperture.

6. The method of claim 4 wherein the internal phase issues in at least one train of droplets.

7. The method of claim 4 wherein the internal phase is applied to the external phase at a plurality of locations.

8. The method of claim 1 wherein a droplet has a diameter of about 20 μ

m to about 300 μ

m and has a substantially uniform size relative to other droplets in the series of droplets.

9. The method of claim 1 wherein the step of vibrating the internal phase comprises vibrating the internal phase with a vibrating member.

10. The method of claim 9 wherein the vibrating member comprises a piezoelectric transducer.

11. The method of claim 1 wherein the step of vibrating the internal phase comprises vibrating a conduit containing the internal phase.

12. The method of claim 11 wherein the internal phase issues from the conduit in two trains of droplets.

13. The method of claim 11 wherein a tip of the conduit, through which the internal phase issues into the external phase, is in communication with the external phase.

14. The method of claim 1 wherein the step of applying the internal phase to the external phase comprises simultaneously issuing the internal phase and the external phase through two adjacent channels.

15. The method of claim 14 wherein the two channels terminate at two concentric nozzles.

16. The method of claim 1 further comprising the step of mixing the particles with the first fluid.

17. The method of claim 16 wherein the step of mixing comprises inducing a flow within the internal phase.

18. The method of claim 1 wherein the droplets comprise the internal phase.

19. The method of claim 1 wherein the droplets comprise the internal and external phases.

20. A method for forming substantially uniform droplets, the method comprising the steps of:

(a) providing a non-aqueous internal phase comprising a plurality of particles suspended in a first fluid;

(b) providing an external phase comprising a second fluid; and

(c) applying the internal phase to the external phase through an aperture in a container, wherein the internal phase is moved relative to the external phase such that as the internal phase contacts the external phase a droplet separates from a remainder of the internal phase and such that a series of droplets of substantially uniform size is formed.

21. The method of claim 20 further comprising the step of vibrating the internal phase.

22. A method for forming substantially uniform droplets, the method comprising the steps of:

(a) providing a non-aqueous internal phase comprising a plurality of particles suspended in a first fluid;

(b) providing an aqueous external phase comprising a second fluid; and

(c) applying the internal phase to the external phase, wherein the internal phase is pressurized and pulsed through a valve such that the internal phase forms a series of droplets of substantially uniform size.