Patent ID: 11880104
Assignee: 3M INNOVATIVE PROPERTIES COMPANY
Field: Computer technology (Electrical engineering)
Classification: CPC G  A | IPC G

Claim 6:
7. 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;
an infrared light source configured to emit an infrared light having a wavelength W1<975 nm toward the finger of the user, the sensor configured to receive and detect at least a portion of the infrared light reflected by the finger; and
a reflective polarizer disposed between the display panel and the sensor such that for substantially normally incident light:
for a first polarization state, an optical transmittance of the reflective polarizer comprises a first band edge separating first and second wavelength ranges, the first wavelength range extending at least from about 450 nm to about 900 nm, the second wavelength range extending at least from about 1100 nm to about 1300 nm, the reflective polarizer having an average optical transmittance in the first wavelength range of less than about 10% and an average optical transmittance in the second wavelength range of greater than about 80%; and
for a second polarization state orthogonal to the first polarization state, the reflective polarizer has an average optical transmittance in the first wavelength range of greater than about 40% and an average optical transmittance in the second wavelength range of greater than about 80%,, wherein the reflective polarizer is configured such that for substantially white incident light and for the second polarization state, a maximum difference in color between light transmitted through the reflective polarizer and the incident light as an angle of incidence of the incident light varies from zero to about 60 degrees in each of a plane of incidence parallel to the second polarization state and a plane of incidence orthogonal to the second polarization state is no more than about 0.07 on a CIE 1931 xy color space.