Liquid crystal display element having a precisely controlled cell gap and method of making same

• US 6,307,612 B1
• Filed: 06/08/2000
• Issued: 10/23/2001
• Est. Priority Date: 06/08/2000
• Status: Expired due to Fees

• Current Assignee: Brillian Corporation (Syntax-Brillian Corporation)
• Original Assignee: Three-Five Systems, Inc.
• Inventors: Thomson, James, Stauss, Henning C., Tack, Barnaby, Smith, Peter A.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US09/589,952
• Time in Patent Office: 502 Days
• Field of Search: 349/155, 349/157, 349/187
• US Class Current: 349/157
• CPC Class Codes: G02F 1/13392 spacers dispersed on the cell substrate, e.g. spherical particles, microfibres

Abstract

A liquid crystal display cell having improved cell gap uniformity is made by depositing a plurality of spacer particles on the cell substrate then subjecting the substrate to an external energy source to selectively dislodge and remove the larger particles, such as by immersing the substrate in and ultrasonic bath. Because the larger particles will inherently have a lesser attraction to the substrate relative to their mass, subjecting the entire substrate to the ultrasonic bath will inherently preferentially remove the larger particles, resulting in a distribution having a smaller standard deviation than the initial mixture of particles deposited on the substrate as well as an asymmetric reduction in the number of gap-dominating large particles.

Claims

1. A method of assembling a light influencing display device comprising:

providing a first substrate, said first substrate comprising a major surface having disposed thereon a first plurality of display electrodes;

depositing a plurality of spacer members on said first substrate, said plurality of spacer members comprising a distribution of particles having a mean particle size and a plurality of smaller and larger particles relative to the mean particle size;

subjecting said substrate to an external energy source to preferentially remove a group of said plurality of particles, the majority of particles in said removed group being larger than the mean particle size;

attaching a second substrate having a major surface to said first substrate such that the major surface of said second substrate faces the major surface of said first substrate and said major surface of said first substrate cooperates with said major surface of said second substrate to contact and retain at least some of said plurality of spacer members therebetween, said at least some of said plurality of spacer members supporting said major surface of said first substrate and said major surface of said second substrate in a spaced apart configuration with a uniform gap therebetween; and

injecting a light influencing fluid material into said gap.

2. The method of claim 1, wherein:

said plurality of spacer members is deposited on said first substrate by dusting.

3. The method of claim 1, wherein:

said plurality of spacer members is deposited on said first substrate by spinning.

4. The method of claim 1, wherein:

said plurality of particles is held to said first substrate by electrostatic attraction.

5. The method of claim 4, further comprising:

cleaning said major surface of said first substrate with a surfactant, the surfactant acting to decrease the electrostatic attraction between said first substrate and said plurality of spacer members.

6. The method of claim 1, wherein:

said plurality of particles is held to said first substrate by steric forces.

7. The method of claim 1, wherein:

said plurality of particles is held to said first substrate by a electrostatic attraction and steric forces.

8. The method of claim 1, wherein:

said external energy source is ultrasound.

9. The method of claim 8, wherein:

the step of subjecting said substrate to an external energy source is carried out with said first substrate in an inverted orientation.

10. The method of claim 1, wherein:

the step of subjecting said substrate to an external energy source comprises immersing said first substrate in an ultrasonic bath in an inverted orientation such that the major surface of said first substrate and said plurality of particles are facing downward.

11. A liquid crystal display comprising:

a first substrate, said first substrate comprising a major surface having disposed thereon a first plurality of display electrodes;

a plurality of spacer members on said first substrate, said plurality of spacer members comprising a distribution of particles having a mean particle size and a plurality of smaller and larger particles relative to the mean particle sizes,

wherein said substrate is subjected to an external energy source to preferentially remove a group of said plurality of particles, the majority of particles in said removed group being larger than the mean particle size;

a second substrate having a major surface to said first substrate such that the major surface of said first substrate faces the major surface of said second substrate and said major surface of said first substrate cooperates with said major surface of said second substrate to contact and retain at least some of said plurality of spacer members therebetween, said at least some of said plurality of spacer members supporting said major surface of said first substrate and said major surface of said second substrate in a spaced apart configuration with a uniform gap therebetween; and

a light influencing fluid material in said gap.

12. The liquid crystal display of claim 11, wherein:

said plurality of spacer members is deposited on said first substrate by dusting.

13. The liquid crystal display of claim 11, wherein:

said plurality of spacer members is deposited on said first substrate by spinning.

14. The liquid crystal display of claim 11, wherein:

said plurality of particles is held to said first substrate by electrostatic attraction.

15. The liquid crystal display of claim 11, wherein:

said plurality of particles is held to said first substrate by steric forces.

16. The liquid crystal display of claim 11, wherein:

said plurality of particles is held to said first substrate by a electrostatic attraction and steric forces.

17. The liquid crystal display of claim 11, wherein:

said major surface of said first substrate is cleaned with a surfactant, the surfactant acting to decrease the electrostatic attraction between said first substrate and said plurality of spacer members.

18. The liquid crystal display of claim 11, wherein:

said external energy source is ultrasound.

19. The liquid crystal display of claim 11, wherein:

said first substrate is immersed in an ultrasonic bath in an inverted orientation such that the major surface of said first substrate and said plurality of particles are facing downward.

20. A light valve cell comprising:

a first substrate comprising a major surface having disposed thereon a first plurality of display electrodes;

a plurality of spacer members disposed on said first substrate, said plurality of spacer members comprising a group consisting of a plurality of particles having a nominal particle size and a plurality of larger and smaller particles relative to said nominal particle size, said group of particles comprising a non-gaussian distribution having a standard deviation above said nominal particle size that is less than the standard deviation below the nominal particle size;

a second substrate having a major surface, said major surface having at least one display electrode disposed thereon, said second substrate being attached to said first substrate such that the major surface of said first substrate and the major surface of said second substrate contact and retain at least some of said plurality of spacer members therebetween, said at least some of said plurality of spacer members supporting said major surface of said first substrate away from said major surface of said second substrate in a spaced apart configuration with a uniform gap therebetween; and

a liquid crystal material disposed in said gap.