Metal mesh touch sensor with low birefringence substrate and ultraviolet cut

• US 9,465,472 B1
• Filed: 12/09/2014
• Issued: 10/11/2016
• Est. Priority Date: 08/29/2014
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Heng, Heang, Marimuthu, Thiagarajan, Yadav, Krishan, Yang, Jianjun, Almanza-Workman, Angeles Marcia, Rathnam, Lakshman
• Primary Examiner(s): Cheng, Joe H
• Application Number:
  US14/565,187
• Time in Patent Office: 672 Days
• US Class Current: 1/1
• CPC Class Codes: G02B 1/10 Optical coatings produced by application to, or surface treatment of, optical elements G02B1/08 takes precedence
• CPC Class Codes: G02B 1/11 Anti-reflection coatings
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 5/208 for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04112 Electrode mesh in capacitive digitiser: electrode for touch sensing is formed of a mesh of very fine, normally metallic, interconnected lines that are almost invisible to see. This provides a quite large but transparent electrode surface, without need for ITO or similar transparent conductive material
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A touch-sensitive display for an electronic device may include a touch sensor comprising a low birefringence substrate, ultraviolet (UV) stabilizers, and a metal mesh disposed on at least a portion of the low birefringence substrate. The low birefringence characteristic of the touch sensor substrate causes the touch sensor to exhibit low haze, high transmittance, and substantially no color, which provides improved optical properties over conventional touch sensor substrate materials used with metal mesh film. In some embodiments, the retardation value of the touch sensor substrate may be no greater than about 15 nanometers (nm). Additionally, the UV stabilizers prevent the substrate from yellowing and becoming brittle from exposure to UV radiation.

Claims

1. An apparatus comprising:

a touch sensor comprising;

a substrate having a retardation value that is no greater than about 15 nanometers (nm) and having a front surface and a back surface;

a first plurality of metal lines disposed on the front surface of the substrate in a first pattern;

a second plurality of metal lines disposed on the back surface of the substrate in a second pattern; and

ultraviolet (UV) stabilizers, the UV stabilizers being disposed in the substrate, on at least a portion of the front surface or the back surface of the substrate, or on at least a portion of the first and the second plurality of metal lines,

the first plurality of metal lines and the second plurality of metal lines being configured to operate as transmitter and receiver electrodes of the touch sensor, the touch sensor being configured to detect a change in a capacitive coupling between the transmitter electrode and the receiver electrode;

a first optically clear adhesive (OCA) layer disposed atop the touch sensor;

a cover lens disposed atop the first OCA layer;

a second OCA layer disposed under the touch sensor; and

a display module disposed under the second OCA layer.

2. The apparatus of claim 1, wherein the UV stabilizers are at least one of:

(i) embedded within the substrate, or (ii) formed as a first layer disposed on the front surface and a second layer disposed on the back surface of the substrate.

3. The apparatus of claim 1, wherein the substrate is comprised of at least one of:

a cyclo olefin polymer (COP) or a cyclic olefin copolymer (COC).

4. An apparatus comprising:

a touch sensor comprising;

a substrate having a front surface and a back surface;

a metal mesh disposed on a portion of the front surface of the substrate or on a portion of the back surface of the substrate; and

ultraviolet (UV) stabilizers, the UV stabilizers being disposed in the substrate, on at least a portion of the front surface or the back surface of the substrate, or on at least a portion of the metal mesh;

an optically clear adhesive (OCA) layer disposed atop the touch sensor; and

a cover lens disposed atop the OCA layer.

5. The apparatus of claim 4, wherein the substrate has a retardation value that is no greater than about 15 nanometers (nm).

6. The apparatus of claim 4, wherein the substrate is comprised of at least one of:

a cyclo olefin polymer (COP) or a cyclic olefin copolymer (COC).

7. The apparatus of claim 4, wherein the substrate has a haze value that is no greater than about 0.5%.

8. The apparatus of claim 4, wherein the substrate has a transmittance value that is at least about 90%.

9. The apparatus of claim 4, wherein the substrate has a glass transition temperature that is at least about 120°

Celsius (C).

10. The apparatus of claim 4, wherein the OCA layer is a first OCA layer, the apparatus further comprising:

a second OCA layer disposed under the touch sensor; and

a display module disposed under the second OCA layer.

11. The apparatus of claim 4, wherein the UV stabilizers are embedded within the substrate.

12. The apparatus of claim 4, wherein the UV stabilizers are formed as a first layer disposed on the front surface and a second layer disposed on the back surface of the substrate.

13. The apparatus of claim 4, further comprising a passivation coating disposed on at least a portion of the metal mesh, the passivation coating having a surface energy of at least about 40 dynes per centimeter (cm).

14. The apparatus of claim 13, wherein the UV stabilizers are included in the passivation coating.

15. The apparatus of claim 13, further comprising a rear cover disposed under the touch sensor and adhered to the passivation coating at the back surface of the substrate.

16. The apparatus of claim 4, wherein the OCA layer is a first OCA layer, the apparatus further comprising:

a second OCA layer disposed under the touch sensor;

a film having an anti-reflective coating disposed under the second OCA layer to seal the second OCA layer;

a rear cover disposed under the film and adhered to the film; and

a display module disposed atop the rear cover and under the film to allow for an air gap to exist between the display module and the film.

17. The apparatus of claim 4, wherein the substrate has a thickness in a range of about 20 micrometers to about 100 micrometers.

18. The apparatus of claim 4, wherein the metal mesh has a pitch in a range of about 160 micrometers to about 300 micrometers.

19. The apparatus of claim 4, wherein the OCA layer is of a thickness in a range of about 100 micrometers to about 200 micrometers.

20. A method of manufacturing at least part of a touch screen of an electronic device, the method comprising:

forming a substrate comprising ultraviolet (UV) stabilizers;

applying a first portion of a metal mesh to a front surface of the substrate;

applying a second portion of the metal mesh to a back surface of the substrate;

providing a first optically clear adhesive (OCA) layer atop the first portion of the metal mesh;

providing a cover lens atop the OCA layer;

providing a second OCA layer disposed over the second portion of the metal mesh;

providing a display module under the second OCA layer; and

providing a rear cover under the display module and adhering the rear cover to the back surface of the substrate.

21. The method of claim 20, wherein the forming the substrate comprises mixing the UV stabilizers within a resin to embed the UV stabilizers within the substrate.

22. The method of claim 21, wherein the resin comprises at least one of:

a cyclo olefin polymer (COP) or a cyclic olefin copolymer (COC).

23. The method of claim 20, wherein forming the substrate comprises forming a first layer including the UV stabilizers on the front surface of the substrate and a second layer including the UV stabilizers on the back surface of the substrate, wherein the first portion of the metal mesh is disposed over the first layer and the second portion of the metal mesh is disposed over the second layer.

24. The method of claim 20, further comprising forming a passivation layer, the passivation layer disposed on at least a portion of the metal mesh.

25. The method of claim 20, further comprising forming a first layer having a material having lower reflectivity than a reflectivity of the metal mesh, the first layer being disposed on at least one of the first portion or the second portion of the metal mesh.

26. The method of claim 20, further comprising forming a first layer disposed on the first and the second portions of the metal mesh, the first layer acting as a passivation layer and being configured to block ultraviolet (UV) radiation.

27. The method of claim 26, further comprising removing at least a portion of the first layer to allow for an electrical connection to be made to a portion of the metal mesh.