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EP-3948411-B1 - MULTIVIEW DISPLAY ALIGNMENT METHOD AND SYSTEM

EP3948411B1EP 3948411 B1EP3948411 B1EP 3948411B1EP-3948411-B1

Inventors

  • HOEKMAN, Thomas
  • FATTAL, DAVID A.

Dates

Publication Date
20260506
Application Date
20200402

Claims (12)

  1. A method (100) of aligning a multiview backlight (234) with a light valve array (232) of a multiview display (230), wherein the multiview backlight (234) emits light as directional light beams having directions corresponding to different view directions (16) to illuminate the light valve array (232) and wherein the light valve array (232) comprises a plurality of light valves (30) modulating the emitted light (18) to provide a multiview image, the method comprising: establishing (110) on the light valve array an alignment pattern (200) having unit cells (210) spaced apart from one another, each unit cell of the alignment pattern comprising a plurality of view blocks (212) having different view directions corresponding to different views of the multiview display, wherein a view block (212) is a subset of light valves (30) of the light valve array (232), and wherein a unit cell (210) of the alignment pattern (200) is defined as a collection, a group, or a plurality of view blocks (212), where each view (14) of the multiview display (230) is represented by a different one of the view blocks (212) of the unit cell (210) such that a unit cell (210) comprises a view block (212) corresponding to each view (14) of the multiview display (230); illuminating (120) the light valve array using the multiview backlight to display the alignment pattern; and adjusting (130) a relative position of the multiview backlight and the light valve array to minimize an error measure of the unit cells within the displayed alignment pattern, wherein the error measure comprises one or both of a relative luminance difference between each of the unit cells (210) of the alignment pattern (200) and a location displacement of unit cell luminance centroids (214) in the displayed alignment pattern (200) relative to target locations (216) of the unit cells (210), wherein an arrangement of view blocks within each unit cell corresponds to an arrangement of the views of the multiview display.
  2. The method of aligning a multiview backlight of Claim 1, wherein the arrangement of views of the multiview display comprises a one-dimensional array of sequentially arranged views, each unit cell of the alignment pattern having a corresponding one-dimensional array of sequentially arranged view blocks.
  3. The method of aligning a multiview backlight of Claim 1, wherein the arrangement of views of the multiview display comprises a two-dimensional array of views, each unit cell of the alignment pattern having a corresponding two-dimensional array of view blocks.
  4. The method of aligning a multiview backlight of Claim 3, wherein the two-dimensional array of views is a two-by-two array of four views arranged in two rows and two columns.
  5. The method of aligning a multiview backlight of Claim 1, wherein the multiview backlight comprises: a light guide configured to guide light as guided light; and an array of multibeam elements spaced apart from one another across the light guide, each multibeam element of the multibeam element array being configured to scatter out a portion of the guided light from the light guide as a plurality of directional light beams having directions corresponding to the different view directions to illuminate the light valve array, wherein a size of each multibeam element is between one quarter and two times a size of a light valve of the light valve array.
  6. The method of aligning a multiview backlight of Claim 5, wherein multibeam elements of the multibeam element array comprise one or more of a diffraction grating configured to diffractively scatter out the guided light, a micro-reflective element configured to reflectively scatter out the guided light, and a micro-refractive element configured to refractively scatter out the guided light.
  7. The method of aligning a multiview backlight of Claim 1, wherein adjusting a relative position comprises one or both of rotating the multiview backlight relative to the light valve array and translating the multiview backlight relative to the light valve array.
  8. The method of aligning a multiview backlight of Claim 1, wherein the relative luminance difference comprises a difference in luminance between corresponding view blocks of each of the unit cells of the alignment pattern.
  9. The method of aligning a multiview backlight of Claim 1, wherein minimizing a location displacement of the unit cell luminance centroids comprises minimizing a sum of a squared difference between observed locations of individual unit cell luminance centroids in the displayed alignment pattern and corresponding target locations of the individual unit cells.
  10. A multiview display backlight alignment system configured to align a multiview display (230) having a light valve array (232) and a multiview backlight (234), wherein the multiview backlight (234) is configured to emit light as directional light beams having directions corresponding to different view directions (16) to illuminate the light valve array (232) and wherein the light valve array (232) comprises a plurality of light valves (30) configured to modulate the emitted light (18) to provide a multiview image, the light valve array being configured to provide a displayed alignment pattern (200) comprising a plurality of unit cells (210) when illuminated by the multiview backlight; and the alignment system comprising: a positioning stage (320, 420) configured to adjust a relative position of the light valve array and multiview backlight to minimize an error measure of the unit cells within the displayed alignment pattern, wherein the error measure comprises one or both of a relative luminance difference between each of the unit cells (210) of the alignment pattern (200) and a location displacement of unit cell luminance centroids (214) in the displayed alignment pattern (200) relative to target locations (216) of the unit cells (210), wherein unit cells of the unit cell plurality are spaced apart from one another, each unit cell comprising a plurality of view blocks (212) having different view directions corresponding to different views of the multiview display and having an arrangement corresponding to an arrangement of the different views, wherein a view block (212) is a subset of light valves (30) of the light valve array (232), and wherein a unit cell (210) of the alignment pattern (200) is defined as a collection, a group, or a plurality of view blocks (212), where each view (14) of the multiview display (230) is represented by a different one of the view blocks (212) of the unit cell (210) such that a unit cell (210) comprises a view block (212) corresponding to each view (14) of the multiview display (230).
  11. The multiview display backlight alignment system of Claim 10, further comprising a camera configured to capture an image of the displayed alignment pattern provided on the multiview display, the error measure being determined from the captured image of the displayed alignment pattern.
  12. The multiview display backlight alignment system of Claim 10, wherein the positioning stage comprises a motorized stage configured to provide one or both of a relative rotation and a relative translation of the multiview backlight and the light valve array.

Description

BACKGROUND Electronic displays are a nearly ubiquitous medium for communicating information to users of a wide variety of devices and products. Most commonly employed electronic displays include the cathode ray tube (CRT), plasma display panels (PDP), liquid crystal displays (LCD), electroluminescent displays (EL), organic light emitting diode (OLED) and active matrix OLEDs (AMOLED) displays, electrophoretic displays (EP) and various displays that employ electromechanical or electrofluidic light modulation (e.g., digital micromirror devices, electrowetting displays, etc.). Generally, electronic displays may be categorized as either active displays (i.e., displays that emit light) or passive displays (i.e., displays that modulate light provided by another source). Among the most obvious examples of active displays are CRTs, PDPs and OLEDs/AMOLEDs. Displays that are typically classified as passive when considering emitted light are LCDs and EP displays. Passive displays, while often exhibiting attractive performance characteristics including, but not limited to, inherently low power consumption, may find somewhat limited use in many practical applications given the lack of an ability to emit light. Present techniques for aligning components of such displays during manufacture often involve utilizing a microscope to align marks on a light producing portion (e.g., backlight, film, etc.) with marks on the display panel to properly align the components during assembly. Drawbacks of such techniques, however, include the requirement of a very high degree of precision in tooling (e.g., given sizes of the microscope stage, tightness of the mechanical tolerances on telecentric lenses, etc.), the limitation of the alignment operation to the field of view of the microscope, and the inability to detect certain misalignment such as inter-mark local distortions. US 2019/025494 A1 relates to a multiview backlight and a multiview display that employ multibeam elements configured to provide a plurality of light beams having different principal angular directions corresponding to different view directions of the multiview display. The display includes multiview pixels that include sub-pixels. US 2012/256890 A1 relates to a method of aligning a display panel with a backlight unit using alignment marks. BRIEF DESCRIPTION OF THE DRAWINGS Various features of examples and embodiments in accordance with the principles described herein may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings, where like reference numerals designate like structural elements, and in which: Figure 1A illustrates a perspective view of a multiview display in an example, according to an embodiment consistent with the principles described herein.Figure 1B illustrates a graphical representation of the angular components of a light beam having a particular principal angular direction in an example, according to an embodiment consistent with the principles described herein.Figure 1C illustrates a perspective view of a multiview display in an example, according to an embodiment consistent with the principles described herein.Figure 2 illustrates a flow chart of a method of aligning a multiview backlight with a light valve array of a multiview display in an example, according to an embodiment consistent with the principles described herein.Figure 3A illustrates a plan view of an alignment pattern in an example, according to an embodiment consistent with the principles described herein.Figure 3B illustrates a plan view of an alignment pattern in an example, according to another embodiment consistent with the principles described herein.Figure 3C a plan view of an alignment pattern in an example, according to another embodiment consistent with the principles described herein.Figure 4A illustrates a perspective view of a portion of a multiview display in an example, according to an embodiment consistent with the principles described herein.Figure 4B illustrates a cross sectional view of the multiview display portion of Figure 4A in an example, according to an embodiment consistent with the principles described herein.Figure 5A illustrates a plan view of an alignment pattern of an illuminated light valve array prior to adjusting a relative position of the multiview backlight and the light valve array to minimize an error measure in an example, according to an embodiment consistent with the principles described herein.Figure 5B illustrates a plan view of the alignment pattern of Figure 5A following adjusting a relative position of the multiview backlight and the light valve array to minimize an error measure in an example, according to an embodiment consistent with the principles described herein.Figure 6 illustrates a graphical representation of unit cell luminance centroids in an example, according to an embodiment consistent with the principles described herein.Figure 7 illustrates a bl