Optical system

Patent metadata

Field	Value
Publication number	US-12287481-B2
Application number	US-202017639953-A
Country	US
Kind code	B2
Filing date	Sep 9, 2020
Priority date	Sep 13, 2019
Publication date	Apr 29, 2025
Grant date	Apr 29, 2025

Abstract

An optical system for displaying first and second images to a viewer is provided. A reflective polarizer is disposed between the second display and the viewer and is oriented obliquely relative to the first display. An optical stack including a partial reflector and a retarder layer is disposed between the reflective polarizer and the second display. The reflective polarizer reflects at least 70% of the incident light having a first polarization state and transmits at least 60% of the incident light having an orthogonal second polarization state. The partial reflector reflects at least 70% of the incident light for each of the polarization states. For each of the first and second polarization states and for each of a blue-green wavelength and a green-red wavelength the reflective polarizer transmits at east 70% of the incident light and the partial reflector transmits at least 60% of the incident light.

First claim

The invention claimed is:

1. An optical system for displaying first and second images to a viewer, comprising:
different first and second displays, the first display configured to produce a polarized image;
a reflective polarizer disposed between the second display and the viewer and oriented obliquely relative to the first display, the reflective polarizer comprising substantially distinct blue, green and red reflection bands;
an absorbing polarizer disposed between the first display and the reflective polarizer; and
an optical stack disposed between the reflective polarizer and the second display and comprising:
a partial reflector disposed between the reflective polarizer and the second display; and
a retarder layer disposed between the reflective polarizer and the partial reflector, such that for substantially normally incident light and for each of a blue wavelength, a green wavelength, and a red wavelength in a predetermined wavelength range extending from about 400 nm to about 700 nm:
the reflective polarizer reflects at least 70% of the incident light having a first polarization state and transmits at least 60% of the incident light having an orthogonal second polarization state; and
the partial reflector reflects at least 70% of the incident light for each of the first and second polarization states;
wherein the retarder layer is substantially a quarter wave retarder at at least one of the blue, green and red wavelengths for at least one of the first and second polarization states; and
for each of the first and second polarization states and for each of a blue-green wavelength between the blue and green wavelengths and a green-red wavelength between the green and red wavelengths:
the reflective polarizer transmits at least 70% of the incident light; and
the partial reflector transmits at least 60% of the incident light.

2. The optical system of claim 1 , wherein the first display is an electronic display, and the second display is a real-world object in a real-world scene.

3. The optical system of claim 2 , wherein first display comprises one or more of a liquid crystal display (LCD), and an organic light emitting diode (OLED) display.

4. The optical system of claim 1 , wherein the optical stack is curved.

5. The optical system of claim 1 , wherein at least one of the partial reflector and the retarder layer is curved.

6. The optical system of claim 1 , wherein the reflective polarizer comprises one or more of a wire grid reflective polarizer, and a multilayer polymeric reflective polarizer.

7. The optical system of claim 1 , wherein the reflective polarizer makes an angle between about 30 degrees to about 60 degrees with the first display.

8. The optical system of claim 1 , wherein the reflective polarizer makes an angle of about 45 degrees with the first display.

9. The optical system of claim 1 , wherein for substantially normally incident light and for each of the blue, green and red wavelengths, the absorbing polarizer transmits at least 70% of the incident light having the first polarization state and absorbs at least 70% of the incident light having the second polarization state.

10. The optical system of claim 1 , wherein the optical stack further comprises an adhesive layer bonding the partial reflector to the retarder layer.

11. The optical system of claim 1 , wherein for substantially normally incident light and for each of the blue, green and red wavelengths:
the reflective polarizer reflects at least 80% of the incident light having the first polarization state and transmits at least 70% of the incident light having the second polarization state; and
the partial reflector reflects at least 80% of the incident light for each of the first and second polarization states.

12. The optical system of claim 1 , wherein for substantially normally incident light and for each of the first and second polarization states and for each of the blue-green and green-red wavelengths:
the reflective polarizer transmits at least 80% of the incident light; and
the partial reflector transmits at least 70% of the incident light.

13. The optical system of claim 1 , wherein the blue wavelength is in a range from about 425 nm to about 475 nm, the green wavelength is in a range from about 525 nm to about 575 nm, and the red wavelength is in a range from about 625 nm to about 700 nm.

14. The optical system of claim 1 , wherein the partial reflector comprises a plurality of polymeric layers numbering greater than about 50 in total.

Assignees

• 3M Innovative Properties Company

Inventors

• Le John D
• Wong Timothy L
• Nevitt Timothy J
• Yun Zhisheng

Classifications

• G02B2027/0118

  comprising devices for improving the contrast of the display / brillance control visibility · CPC title

• G02B2027/0112

  comprising device for genereting colour display · CPC title

• G02B5/3083

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title

• G02B5/3025

  Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state (G02B5/3008, G02B5/3016 take precedence) · CPC title

• G02B27/283

  used for beam splitting or combining · CPC title