REINFORCEMENT PANEL FOR FINGERPRINT SENSOR COVER

• US 20170372112A1
• Filed: 06/20/2017
• Published: 12/28/2017
• Est. Priority Date: 06/24/2016
• Status: Active Grant

• Current Assignee: IDEX Biometrics ASA
• Original Assignee: Idex ASA
• Inventors: BAKER, DAVID RODNEY, LIGHT, DAVID N.
• Granted Patent: US 10,387,707 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: G06V 40/1329 Protecting the fingerprint sensor against damage caused by the finger
• CPC Class Codes: G06V 40/1359 Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop
• CPC Class Codes: G06V 40/1365 Matching; Classification

Abstract

A fingerprint sensor assembly includes a capacitive fingerprint sensor disposed beneath a thin layer of glass and a reinforcement layer of a material of relatively high dielectric constant bonded to the glass between the glass layer and the sensor.

Claims

1. A fingerprint sensor assembly comprising:

a capacitive fingerprint sensor;

a cover layer disposed above the fingerprint sensor, the cover layer having a dielectric constant of less than 10 and a thickness of less than 300 μ

m; and

a reinforcement layer between the fingerprint sensor and the cover layer and bonded or molded to the cover layer, the reinforcement layer comprising a material having a dielectric constant of at least 20 and having a thickness of 10% to 200% of the thickness of the cover layer.

2. The fingerprint sensor assembly of claim 1, wherein the reinforcement layer comprises a material selected from the group consisting of:

titanium dioxide (TiO₂), barium strontium titanate, zirconia, and barium titanate+epoxy based systems.

3. The fingerprint sensor assembly of claim 1, wherein the reinforcement layer comprises a reinforcement panel bonded to the cover layer by an adhesive, and wherein the adhesive comprises one or more materials selected from the group consisting of:

pressure sensitive adhesive, B-staged sheet adhesive, bond ply adhesive, acrylic-based thermoset adhesives, high modulus of elasticity/highly cross-linked, epoxy-type thermoset adhesives, adhesive with particle fillers to increase the modulus of elasticity of the adhesive, and adhesives with filler materials having high dielectric constants.

4. The fingerprint sensor assembly of claim 1, wherein the reinforcement layer is bonded to the fingerprint sensor, and wherein the adhesive comprises one or more materials selected from the group consisting of:

pressure sensitive adhesive, B-staged sheet adhesive, bond ply adhesive, acrylic-based thermoset adhesives, high modulus of elasticity/highly cross-linked, epoxy-type thermoset adhesives, adhesive with particle fillers to increase the modulus of elasticity of the adhesive, and adhesives with filler materials having high dielectric constants.

5. The fingerprint sensor assembly of claim 1, wherein the cover layer comprises a glass cover.

6. The fingerprint sensor assembly of claim 1, wherein the cover layer comprises a thinned region of a cover glass screen of a mobile electronic device.

7. The fingerprint sensor assembly of claim 1, wherein the cover layer thickness is less than or equal to 200 μ

m and the reinforcement layer thickness is at least 50 μ

m.

8. The fingerprint sensor assembly of claim 1, wherein the reinforcement layer comprises a material having flexural strength of at least 400 to 1500 Mpa.

9. The fingerprint sensor assembly of claim 8, wherein the reinforcement layer comprises a material having flexural strength greater than 1500 Mpa.

10. The fingerprint sensor assembly of claim 1, wherein the reinforcement layer comprises a material having a fracture toughness of 3.5 to 15 MPam^1/2.

11. The fingerprint sensor assembly of claim 1, wherein the reinforcement layer and the cover layer comprise materials having substantially the same coefficient of thermal expansion.

12. The fingerprint sensor assembly of claim 3, wherein the reinforcement layer is bonded to the fingerprint sensor, and wherein the adhesive comprises one or more materials selected from the group consisting of:

pressure sensitive adhesive, B-staged sheet adhesive, bond ply adhesive, acrylic-based thermoset adhesives, high modulus of elasticity/highly cross-linked, epoxy-type thermoset adhesives, adhesive with particle fillers to increase the modulus of elasticity of the adhesive, and adhesives with filler materials having high dielectric constants.

13. The fingerprint sensor assembly of claim 12, wherein the cover layer comprises a glass cover.

14. The fingerprint sensor assembly of claim 2, wherein the cover layer thickness is less than or equal to 200 μ

m and the reinforcement layer thickness is at least 50 μ

m.

15. The fingerprint sensor assembly of claim 7, wherein the reinforcement layer comprises a material having flexural strength of at least 400 to 1500 Mpa.

16. The fingerprint sensor assembly of claim 8, wherein the reinforcement layer comprises a material having a fracture toughness of 3.5 to 15 MPam^1/2.

17. The fingerprint sensor assembly of claim 5, wherein the reinforcement layer and the cover layer comprise materials having substantially the same coefficient of thermal expansion.

18. The fingerprint sensor assembly of claim 2, wherein the reinforcement layer comprises a reinforcement panel bonded to the cover layer by an adhesive, and wherein the adhesive comprises one or more materials selected from the group consisting of:

pressure sensitive adhesive, B-staged sheet adhesive, bond ply adhesive, acrylic-based thermoset adhesives, high modulus of elasticity/highly cross-linked, epoxy-type thermoset adhesives, adhesive with particle fillers to increase the modulus of elasticity of the adhesive, and adhesives with filler materials having high dielectric constants.

19. The fingerprint sensor assembly of claim 18, wherein the reinforcement layer is bonded to the fingerprint sensor, and wherein the adhesive comprises one or more materials selected from the group consisting of:

pressure sensitive adhesive, B-staged sheet adhesive, bond ply adhesive, acrylic-based thermoset adhesives, high modulus of elasticity/highly cross-linked, epoxy-type thermoset adhesives, adhesive with particle fillers to increase the modulus of elasticity of the adhesive, and adhesives with filler materials having high dielectric constants.

20. The fingerprint sensor assembly of claim 5, wherein the cover layer thickness is less than or equal to 200 μ

m and the reinforcement layer thickness is at least 50 μ

m.