Optical sensor for integration in a display

• US 10,176,355 B2
• Filed: 03/31/2016
• Issued: 01/08/2019
• Est. Priority Date: 12/03/2015
• Status: Active Grant

• Current Assignee: Fingerprint Cards IP AB
• Original Assignee: Synaptics Incorporated
• Inventors: Smith, Patrick, Fomani, Arash Akhavan, Mienko, Marek, Wickboldt, Paul
• Primary Examiner(s): Tucker, Westley J
• Application Number:
  US15/087,955
• Publication Number:
  US 20170161543A1
• Time in Patent Office: 1,013 Days
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G06V 40/1341 Sensing with light passing through the finger
• CPC Class Codes: G06V 40/1359 Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop

Abstract

Systems and methods for optical imaging are disclosed. An optical sensor for imaging a biometric input object on a sensing region includes a transparent layer having a first side and a second side opposite the first side; a first set of apertures disposed above the first side of the transparent layer; a reflective layer disposed below the second side of transparent layer configured to receive light transmitted through the first set of apertures and to reflect the received light; and a plurality of detector elements positioned to detect the reflected light.

Claims

1. An optical sensor for imaging a biometric input object on a sensing region, comprising:

a transparent layer having a first side and a second side opposite the first side;

a first set of apertures disposed above the first side of the transparent layer;

a reflective layer disposed below the second side of the transparent layer configured to receive light transmitted through the first set of apertures and to reflect the received light; and

a plurality of detector elements positioned to detect the reflected light, wherein the plurality of detector elements have a top side facing the sensing region and an underside opposite to the sensing region, wherein the plurality of detector elements are configured to detect the reflected light from the underside opposite to the sensing region.

2. The optical sensor of claim 1, wherein the plurality of detector elements are positioned above the transparent layer.

3. The optical sensor of claim 1, wherein the first set of apertures are defined by openings in a blocking layer configured to occlude light in areas proximate to the openings.

4. The optical sensor of claim 3, wherein the blocking layer comprises a light absorbing material.

5. The optical sensor of claim 1, wherein the reflective layer comprises a set of mirrored surfaces, each of the mirrored surfaces being surrounded by a light absorbing material.

6. The optical sensor of claim 5, wherein the mirrored surfaces are recessed relative to a surface of the light absorbing material.

7. The optical sensor of claim 6, wherein the reflective layer comprises a second transparent layer, wherein the mirrored surfaces are positioned on a first side of the second transparent layer and the light absorbing material is positioned on a second side of the second transparent layer opposite the first side.

8. The optical sensor of claim 1, further comprising:

a second set of apertures disposed above the first side of the transparent layer and positioned between the plurality of detector elements and the reflective layer.

9. The optical sensor of claim 1, wherein the first set of apertures is disposed between the plurality of detector elements and the sensing region.

10. The optical sensor of claim 1, further comprising:

a liquid crystal display (LCD) backlight which forms a light source configured to provide the light detected by the plurality of detector elements; and

a light shielding layer disposed between the backlight and the plurality of detector elements, wherein the light shielding layer blocks a portion of the light provided by the LCD backlight.

11. The optical sensor of claim 1, further comprising a light shield layer above the plurality of detector elements.

12. A display for imaging a biometric input object, comprising:

a set of display pixels;

a light blocking layer having a first set of apertures;

a transparent layer positioned below the display pixels and the first set of apertures;

a reflective layer positioned below the transparent layer configured to receive light transmitted through the first set of apertures and to reflect the received light; and

a set of detector elements positioned to detect the reflected light.

13. The display of claim 12, wherein the display comprises an organic light-emitting diode (OLED) display and one or more of display pixels form a light source configured to provide the light detected by the set of detector elements.

14. The display of claim 12, wherein the display comprises a liquid crystal display (LCD) backlight forming a light source configured to provide the light detected by the set of detector elements.

15. The display of claim 14, wherein first portions of the reflective layer are transparent to permit transmission of light from the backlight and second portions of the reflective layer are configured to block the transmission of light from the backlight.

16. The display of claim 12, further comprising:

a second set of apertures disposed between the set of detector elements and the reflective layer.

17. The display of claim 12, wherein the reflective layer comprises a set of mirrored surfaces, each of the mirrored surfaces being surrounded by light absorbing material.

18. The display of claim 12, further comprising a light shield layer above the set of detector elements.

19. A method for making an optical fingerprint sensor, comprising:

forming a light blocking layer above a first side of a first transparent layer, the light blocking layer having a first set of apertures configured to permit transmission of light therethrough;

forming a reflective layer below a second side of the first transparent layer opposite to the first side of the first transparent layer, the reflective layer positioned to reflect the light transmitted through the first set of apertures; and

forming a detector layer having a plurality of detector elements positioned to receive the light transmitted through the first set of apertures and reflected from the reflective layer,

wherein forming the reflective layer comprises forming a set of discrete mirrored surfaces and a light absorbing material in areas between the discrete mirrored surfaces, wherein each of the discrete mirrored surfaces is positioned to receive light transmitted through a corresponding aperture in the first set of apertures.

20. The method of claim 19, wherein forming the reflective layer comprises:

patterning a reflective material to form a the set of discrete mirrored surfaces positioned to receive the light transmitted through the first set of apertures.

21. The method of claim 19, wherein forming the reflective layer comprises:

depositing a continuous reflective material; and

after depositing the continuous reflective material, depositing a light absorbing material over selected portions of the continuous reflective material to form the set of discrete mirrored surfaces exposed through the light absorbing material, wherein the set of discrete mirrored surfaces are positioned to receive the light transmitted through the first set of apertures.

22. The method of claim 19, wherein the first transparent layer is a first substrate having a first side and a second side opposite to the first side, and wherein the detector layer is formed directly on the first side of the first substrate.

23. The method of claim 19, further comprising:

forming the first transparent layer by applying a transparent material to a first side of a first substrate.