Low-reflection liquid-crystal display

• US 4,521,079 A
• Filed: 09/08/1982
• Issued: 06/04/1985
• Est. Priority Date: 09/21/1981
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Kruger, Hans, Leenhouts, Frans
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/416,059
• Time in Patent Office: 1,000 Days
• Field of Search: 350/338, 350/339 R, 350/166
• US Class Current: 349/137
• CPC Class Codes: G02F 1/133502 Antiglare, refractive index matching layers

Abstract

A liquid crystal display enclosing between two parallel plates a liquid crystal layer which can be switched between two optically different states. The plate surfaces facing each other each carry a matching layer on top of which are the electrodes. On top of the electrode is a first layer system with a dielectric layer and a topmost orientation layer. The refraction index n_u of the substrata is smaller than the index n_e of the electrode. The index of the matching layer has the following relationship: ##EQU1## The matching layer has a thickness d_a, according to: ##EQU2## wherein λ=550 nm, m=natural integer >0, and nm=nanometer, The electrode has a thickness d_e, according to: d_e ≦30 nm or ##EQU3##

Claims

1. A liquid-crystal display with

(1) two mutually parallel, spaced-apart support plates which

(2) enclose between them a liquid-crystal layer which can be switched between two optically different states, and

(3) carry, on the surfaces of the two plates facing each other, electrically conductive coatings as electrodes, with at least one of the two support plates designated to be a first support plate

(4) carrying several separately addressable electrodes, and

(5) a continuous dielectric layer designated to be a matching layer under the electrodes, and

(6) a first layer system disposed on top of the electrodes which system contains at least one continuous dielectric layer and a topmost layer designated to be an orientation layer which aligns the liquid-crystal layer,

the combination therewith wherein at least in the first support plate

(7) the matching layer rests on a substrate, and the refraction index n_u of the latter is smaller than the refraction index n_e of the electrode,

(8) the matching layer has an index of refraction n_a, which has at least approximately, the following relationship to the refraction indices of the electrode and substrate:

##EQU7## and wherein n_a is between 1.65 and 1.75, (9) the matching layer has a thickness d_a, according to ##EQU8## (λ

=550 nm, m=natural integer>

0), and nm is nanometer, (10) the layers of the first layer system have indices of refraction between 1.60 and 1.70 and a total thickness between 20 nm and 70 nm

(11) the first layer system rests on another layer system which consists of a single continuous dielectric layer, and

(12) the protective layer of said another layer system has a refraction index between 1.40 and 1.50 and a total thickness which is in the range between 20 nm and 50 nm.

2. A liquid-crystal display according to claim 1, wherein the layers of the first layer system have indices of refraction and the thicknesses have ranges of 1.45≦

n_u ≦

1.50;

1.65≦

n_a ≦

1.75;

100 nm≦

d_a ≦

125 nm;

1.95≦

n_e ≦

2.05 and 20 nm≦

d_e ≦

30 nm, and wherein the first layer system contains, in addition to he orientation layer, at most one further layer;

the orientation layer having a thickness of 25 nm to 45 nm thick; and

, the additional layer having a thickness <

45 nm.

3. A liquid-crystal display according to claim 1, wherein the support plate consists of glass, the matching layer of SiO₂ SnO₂, the electrode of In₂ O₃ SnO₂ and the orientation layer of a polyimide layer rubbed at its surface.

4. A liquid-crystal display according to claim 3, wherein the first layer system rests on another layer system which consists of a single SiO₂ layer.

5. A liquid-crystal display according to claim 1, wherein another electrically conductive layer is disposed in the electrode region between the first layer system and the another layer system.

6. A liquid-crystal display according to claim 1 or claim 4, wherein the support plate and its dielectric layers are chosen so that the reflection factor at the boundary surface between the support plate and its layers outside the segment electrodes is less than 1%.

7. A liquid-crystal display according to claim 1, wherein the electrode has a thickness d_e in which d_e ≦

30 nm.

8. A liquid-crystal display according to claim 1, wherein the electrode has a thickness d_e within the range according to ##EQU9##

9. A liquid-crystal display with

(1) two mutually parallel, spaced-apart support plates which

(2) enclose between them a liquid-crystal layer which can be switched between two optically different states, and

(3) carry, on the surfaces of the two plates facing each other, electrically conductive coatings as electrodes, with at least one of the two support plates designated to be a first support plate

(4) carrying several separately addressable electrodes, and

(5) a continuous dielectric layer designated to be a matching layer under the electrodes, and

(6) a first layer system disposed on top of the electrodes which system contains at least one continuous dielectric layer and a topmost layer designated to be an orientation layer which aligns the liquid-crystal layer, the combination therewith wherein at least in the first support plate

(7) the matching layer rests on a substrate, and the refraction index n_u of the latter is smaller than the refraction index n_e of the electrode,

(8) the matching layer has an index of refraction n_a, which has at least approximately, the following relationship to the refraction indices of the electrode and substrate:

##EQU10## and wherein n_a is between 1.65 and 1.75, (9) the matching layer has a thickness d_a, according to ##EQU11## (λ

=550 nm, m=natural integer>

0), and nm is nanometer, (10) the layers of the first layer system have indices of refraction between 1.60 and 1.70 and a total thickness between 20 nm and 70 nm

(11) the first layer system rests on another layer system which consists of a single continuous dielectric layer, and

(12) the protective layer of said another layer system has a refraction index between 1.40 and 1.50 and a total thickness which is in the range between (m300-20)nm and (m300+20)nm.