Augmented reality system with fail-safe direct view mode

1 . A head mounted display configured to provide an image for viewing by a user wearing said head mounted display, said head mounted display comprising:

a frame configured to be worn by said user;

a display supported by said frame, said display configured to output light to form images;

a beam combiner that is partially reflective and partially transmissive;

an electrically switchable shutter having a closed state that blocks light;

an outward facing imaging sensor facing an area forward of said shutter to capture images of said area forward of said shutter for presentation of said images on said display for viewing by an eye of said user;

a display imaging sensor configured to capture images of most of the display; and

circuitry configured to control said shutter,

wherein said electrically switchable shutter is disposed in an optical path between said beam combiner and said area forward of said shutter,

wherein said beam combiner is positioned (i) in an optical path of said light output by said display such that at least a portion of said light from said display propagates to said beam combiner and then to said eye of the user to form images produced by said display that are viewable by said eye and (ii) in an optical path of light from said area forward of the shutter such that at least a portion of said light from said area forward of said shutter propagates to said beam combiner and then to said eye when said shutter is open,

wherein said circuitry is configured to detect degradation or disruption in capturing images of said area forward of said shutter and/or display of said captured images of said area forward of said shutter and to cause the shutter to be open in response to said degradation or disruption being detected,

wherein when power is no longer applied to said shutter, said shutter opens such that the user can view said area forward of said shutter through said shutter; and

wherein said circuitry is configured to open said shutter when images of said display captured by said display imaging sensor indicate said display has ceased rendering new images such that the user can view said area forward of said shutter through said open shutter.

2 . The head mounted display of claim 1 , wherein said circuitry is configured to monitor change or lack thereof in images captured by said display imaging sensor and to cause said shutter to open if such change in said images is not detected.

3 . The head mounted display of claim 1 , further comprising detector array electronics in electrical communication with an optical detector array of said outward facing imaging sensor, said detector array electronics configured to output at least one electrical signal indicative of whether said optical detector array is capturing images, said circuitry configured to open said shutter when said detector array electronics indicates said outward facing imaging sensor has ceased capturing images such that the user can view said area forward of said shutter through said open shutter.

4 . The head mounted display of claim 1 , further comprising outward facing imaging sensor electronics in electrical communication with said outward facing imaging sensor, said outward facing imaging sensor electronics configured to output at least one electrical signal indicative of whether a change in images captured by said outward facing imaging sensor has occurred, said circuitry configured to open said shutter when said outward facing imaging sensor electronics indicates no change in the images captured by said outward facing imaging sensor such that the user can view said area forward of said shutter through said open shutter.

5 . The head mounted display of claim 1 , further comprising display electronics in electrical communication with said display, said display electronics configured to output at least one electrical diagnostic signal indicative of whether said display is functioning, said circuitry configured to open said shutter when said display electronics indicates said display is not functioning such that the user can view said area forward of said shutter through said open shutter.

6 . The head mounted display of claim 1 , further comprising display electronics in electrical communication with said display, said display electronics configured to output at least one electrical diagnostic signal indicative of whether a change in images displayed by said display has occurred, said circuitry configured to open said shutter when said display electronics indicates said display has ceased displaying new images such that the user can view said area forward of said shutter through said open shutter.

7 . The head mounted display of claim 1 , wherein said shutter is partitioned into less than ten separately switchable regions.

8 . The head mounted display of claim 1 , wherein said shutter comprises no more than a single switching element.

9 . The head mounted display of claim 1 , wherein said shutter is closed on average for sufficient periods of time such that the user does not perceive the area forward of the shutter by sensing light transmitted through the shutter.

10 . The head mounted display of claim 1 , wherein said shutter is configured to remain closed most of the time.

11 . The head mounted display of claim 1 , wherein said head mounted display includes a first shutter state wherein said shutter is open and transparent and a second shutter state wherein said shutter is closed and opaque and said head mounted display does not have a state between said first and second shutter states wherein said shutter is less optically transmissive than said first open and transparent shutter state and more optically transmissive than said second closed and opaque shutter state.

12 . The head mounted display of claim 1 , wherein said head mounted display satisfies MIL-SPEC standards.

13 . A head mounted display configured to provide an image for viewing by a user wearing said head mounted display, said head mounted display comprising:

a frame configured to be worn by said user;

a display supported by said frame, said display configured to output light to form images;

a beam combiner that is partially reflective and partially transmissive;

an electrically switchable shutter having a closed state that blocks light;

an outward facing imaging sensor facing an area forward of said shutter to capture images of said area forward of said shutter for presentation of said images on said display for viewing by an eye of said user;

a display sensor comprising an optical detector in front of, on or over and facing one or more pixels of said display to receive light from at least a portion of said display and output at least one electrical signal,

circuitry configured to control said shutter,

wherein said electrically switchable shutter is disposed in an optical path between said beam combiner and said area forward of said shutter,

wherein said beam combiner is positioned (i) in an optical path of said light output by said display such that at least a portion of said light from said display propagates to said beam combiner and then to said eye of the user to form images produced by said display that are viewable by said eye and (ii) in an optical path of light from said area forward of the shutter such that at least a portion of said light from said area forward of said shutter propagates to said beam combiner and then to said eye when said shutter is open,

wherein said circuitry is configured to detect degradation or disruption in capturing images of said area forward of said shutter and/or display of said captured images of said area forward of said shutter and to cause the shutter to be open in response to said degradation or disruption being detected,

wherein when power is no longer applied to said shutter, said shutter opens such that the user can view said area forward of said shutter through said shutter; and

wherein said circuitry is configured to open said shutter based on electrical output or lack thereof from said optical detector of said display sensor that indicates said display has ceased rendering new images such that the user can view said area forward of said shutter through said open shutter.

14 . A head mounted display configured to provide an image for viewing by a user wearing said head mounted display, said head mounted display comprising:

a frame configured to be worn by said user;

a display supported by said frame, said display configured to output light to render images;

a beam combiner that is partially reflective and partially transmissive;

an electrically switchable shutter having a first closed state that blocks light;

an outward facing imaging sensor facing an area forward of said shutter to capture images of said area forward of said shutter and to present said images on said display for viewing by an eye of said user; and

electronics configured to control said shutter,

wherein said electrically switchable shutter is disposed in an optical path between said beam combiner and said area forward of said shutter,

wherein said beam combiner is positioned (i) in an optical path of said light output by said display such that at least a portion of said light from said display propagates to said beam combiner and then to said eye of the user to form images produced by said display that are viewable by said eye and (ii) in an optical path of light from said area forward of the shutter such that at least a portion of said light from said area forward of said shutter propagates to said beam combiner and then to said eye when said shutter is open,

wherein said electronics is configured to monitor light levels of the area forward of the shutter for an increase beyond a threshold amount, said electronics configured to close said shutter in 200 milliseconds to 0.1 milliseconds if said increase beyond a threshold amount is detected.

15 . The head mounted display of claim 14 , wherein said electronics is configured to monitor images captured by said outward facing imaging sensor for an increase in light level beyond a threshold amount, said electronics configured to close said shutter if said increase in light level beyond a threshold amount is detected.

16 . The head mounted display of claim 14 , further comprising a light sensor, wherein said electronics is configured to monitor output of said light sensor for an increase in light level beyond a threshold amount, said electronics configured to close said shutter if said increase in light level beyond a threshold amount is detected.

17 . The head mounted display of claim 14 , wherein said increase in light level comprises an increase above a threshold set by the user.

18 . The head mounted display of claim 14 , wherein said increase in light level comprises an increase of a certain amount above the ambient light level.