Display system with finger sensing

Patent metadata

Field	Value
Publication number	US-11960683-B2
Application number	US-202117996583-A
Country	US
Kind code	B2
Filing date	May 4, 2021
Priority date	May 8, 2020
Publication date	Apr 16, 2024
Grant date	Apr 16, 2024

Abstract

A display system for sensing a finger of a user applied to the display system includes a display panel; a sensor for sensing the finger; a sensing light source configured to emit a first light having a first wavelength W 1 ; and a reflective polarizer disposed between the display panel and the sensor. For a substantially normally incident light, an optical transmittance of the reflective polarizer versus wavelength for a first polarization state has a band edge such that for a first wavelength range extending from a smaller wavelength L 1 to a greater wavelength L 2 and including W 1 , where 30 nm≤L 2 −L 1 ≤50 nm and L 1 is greater than and within about 20 nm of a wavelength L 3 corresponding to an optical transmittance of about 50% along the band edge, the optical transmittance has an average of greater than about 75%.

First claim

What is claimed is:

1. A display system for sensing a finger of a user applied to the display system, the display system comprising:
a display panel configured to generate an image for viewing by the user;
a sensor for sensing the finger of the user disposed proximate the display panel;
a sensing light source configured to emit a first light having a first wavelength W 1 toward the finger of the user, the sensor configured to receive and detect at least a portion of the first light reflected by the finger; and
a reflective polarizer disposed between the display panel and the sensor and comprising a plurality of polymeric layers numbering at least 50 in total, such that for a substantially normally incident light, an optical transmittance of the reflective polarizer versus wavelength for a first polarization state comprises a band edge, wherein:
a best linear fit to the band edge correlating the optical transmittance to the wavelength at least across a wavelength range where the optical transmittance along the band edge increases from about 10% to at least about 70% has a slope of greater than about 2.5%/nm; and
for a first wavelength range extending from a smaller wavelength L 1 to a greater wavelength L 2 and comprising W 1 , 30 nm≤L 2 −L 1 ≤50 nm, L 1 greater than and within about 20 nm of a wavelength L 3 corresponding to an optical transmittance of about 50% along the band edge, the optical transmittance has an average of greater than about 75%,
wherein for the substantially normally incident light and a predetermined wavelength range, the reflective polarizer has an average optical reflectance of at least 70% for the first polarization state and an average optical transmittance of at least 40% for an orthogonal second polarization state.

2. The display system of claim 1 , wherein the first wavelength W 1 is about 850 nm or about 940 nm.

3. The display system of claim 1 , wherein the wavelength L 3 is between about 800 nm and about 1100 nm.

4. The display system of claim 1 , wherein for the second polarization state and the predetermined wavelength range, the reflective polarizer has a greater average optical transmittance for light incident at a smaller incident angle and a smaller average optical transmittance for light incident at a greater incident angle.

5. The display system of claim 1 , wherein the predetermined wavelength range extends at least from about 450 nm to about 650 nm.

6. The display system of claim 1 , wherein the plurality of polymeric layers comprises a plurality of first polymeric layers arranged along at least a portion of a thickness of the reflective polarizer and sequentially numbered from 1 to N, N an integer greater than about 150, the plurality of first polymeric layers comprising a polymeric end layer at each end thereof, the polymeric end layers and each layer therebetween having an average thickness less than about 350 nm, a plot of an average layer thickness versus a layer number of the plurality of first polymeric layers comprising a knee region separating a left region comprising at least Q 1 sequentially arranged first polymeric layers, Q 1 an integer greater than about 100, where the first polymeric layers have lower layer numbers, from a right region comprising at least Q 2 sequentially arranged first polymeric layers, Q 2 an integer of at least 10, where the first polymeric layers have higher layer numbers, such that a linear fit to the at least Q 1 sequentially arranged first polymeric layers in the left region has a positive linear slope having a magnitude of greater than about 0.04 nm per layer number with an r-squared value of greater than about 0.8, and a linear fit to the at least Q 2 sequentially arranged first polymeric layers in the right region has a negative linear slope having a magnitude of greater than about 0.1 nm per layer number with an r-squared value of greater than about 0.8.

7. The display system of claim 6 , wherein the plurality of polymeric layers further comprises a plurality of second polymeric layers spaced apart along a thickness direction of the reflective polarizer from the plurality of first polymeric layers by one or more middle layers, each of the pluralities of first and second polymeric layers numbering at least 200 in total, each of the first and second polymeric layers having an average thickness of less than about 300 nm, each of the one or more middle layers having an average thickness of greater than about 500 nm.

8. The display system of claim 1 , wherein a second order polynomial fit to the optical transmittance across a wavelength range at least 200 nm wide between the band edge and about 1300 nm has an r-squared value of greater than about 0.6 and a minimum optical transmittance of less than about 80%.

9. The display system of claim 8 , wherein the second order polynomial fit has a positive second order coefficient and a negative first order coefficient.

10. The display system of claim 1 , wherein the reflective polarizer further comprises:
a first outer layer co-extruded with the plurality of polymeric layers;
a plurality of first particles having an average size of from about 7 to about 9 microns and partially protruding from a first major surface of the first outer layer to form a first structured major surface; and
a first optically diffusive layer conformably disposed on the first structured major surface so that opposing first and second major surfaces of the first optically diffusive layer substantially conform to the first structured major surface, the first optically diffusive layer comprising a plurality of nanoparticles dispersed therein, the nanoparticles defining a plurality of voids therebetween.

11. The display system of claim 10 , wherein the reflective polarizer further comprises:
a second outer layer opposite the first outer layer, the second outer layer co-extruded with the plurality of polymeric layers and the first outer layer; and
a plurality of second particles partially protruding from a second major surface of the second outer layer to form a second structured major surface.

12. The display system of claim 1 , further comprising an optically diffusive film disposed between the reflective polarizer and the sensor, the optically diffusive film comprising:
an optical substrate layer;
a second optically diffusive layer disposed on the optical substrate layer and facing the reflective polarizer and comprising a plurality of nanoparticles dispersed therein, wherein for a substantially normally incident light and a visible wavelength range from about 450 nm to about 650 nm and an infrared wavelength range from about 930 nm to about 970 nm, the second optically diffusive layer has an average specular transmittance Vs in the visible wavelength range and an average specular transmittance Is in the infrared wavelength range, Is/Vs>2.5; and
a structured optical layer disposed on the optical substrate layer and facing away from the reflective polarizer and comprising a structured major surface facing away from the optical substrate layer and comprising a plurality of spaced apart elongated structures elongated along a same first direction and arranged at a substantially uniform density across the structured major surface of the structured optical layer.

13. The display system of claim 12 further comprising a lightguide for providing illumination to the display panel, the lightguide disposed between the reflective polarizer and the sensor.

14. The display system of claim 13 further comprising a structured mirror disposed between the lightguide and the sensor and comprising an optical mirror, and an array of discrete spaced

Assignees

• 3M Innovative Properties Company

Inventors

• Acharya Bharat R
• Taylor Robert D
• Attard Joseph P
• Forsythe Benjamin J
• Yust David T
• Sousa Matthew E
• Petaja Jason S
• Renstrom Anthony M
• Kolb William Blake
• Cole Matthew S
• Stay Matthew S
• Smith Matthew R D
• Swanson Jeremy O
• Pham Tri D
• Rosen David A
• Chen Qunyi
• Denicola Lisa A
• Sanford Quinn D
• Stover Carl A
• Zhao Lin
• Benoit Gilles J

Classifications

• G06F3/0421 Primary

  by interrupting or reflecting a light beam, e.g. optical touch-screen · CPC title

• G02B5/0226

  having particles on the surface · CPC title

• G02B5/305

  including organic materials, e.g. polymeric layers · CPC title

• G02B6/0051

  Diffusing sheet or layer · CPC title

• G06F2203/04103

  Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices · CPC title