Image display systems for eyebox expansion and methods of making the same
Disclosed are systems and methods for expanding eyebox for a viewer, such as for the near eye display applying retinal projecting technologies from a head wearable device such as smart glasses. The system includes at least one image projector and at least one optical duplicator, where the optical duplicator is used to perform a light split to generate multiple instances of an incident light signal to achieve eyebox expansion for the viewer. An alternative system includes at least one image projector and at least one optical reflector, where the optical reflector is moved to perform a time split to redirect multiple light signals at different angles of incidence to achieve eyebox expansion for the viewer.
1. An image display system for eyebox expansion, comprising:
a first image projector generating multiple light signals for a first image;
a first optical duplicator comprising at least one optical element arranged to receive a first light signal corresponding to a pixel of the first image and generated by the first image projector, duplicate the first light signal into N nonparallel instances, and redirect respective ones of N instances of the light signal towards a first combiner, wherein N is an integer greater than 1;
a second image projector generating multiple light signals for a second image;
a second optical duplicator comprising at least one optical element arranged to receive a second light signal corresponding to a pixel of the second image and generated by the second image projector, duplicate the second light signal into M nonparallel instances, and redirect respective ones of M instances of the light signal towards a second combiner, wherein M is an integer greater than 1;
wherein, the first combiner positioned between the first optical duplicator and an eye of the viewer, and arranged to receive and converge each one of the N nonparallel instances of the light signal respectively to N view points within an eyebox of the viewer's eye, the second combiner positioned between the second optical duplicator and the other eye of the viewer, and arranged to receive and redirect each one of the M nonparallel instances of the light signal respectively to M view points within an eyebox of the viewer's other eye,
wherein a light signal redirected from the second combiner is a first redirected right light signal, a corresponding light signal redirected from the first combiner is a first redirected left light signal, and the first redirected right light signal and the first redirected left light signal are perceived by the viewer to display a first virtual binocular pixel of an object with a first depth where both eyes of the viewer fixate,
wherein extension of light paths of the N nonparallel instances of the first light signal of the first image redirected from the first combiner and extension of light paths of the M nonparallel instances of the second light signal of the second image redirected from the second combiner virtually converge on a same converging point.
2. The image display system of claim 1 , wherein the N nonparallel instances of the light signal from the first optical duplicator physically converges on the first combiner or the light path extension of the N nonparallel instances of the light signal redirected from the first combiner virtually converge on a converging plane behind the first combiner further away from the viewer's eye.
3. The image display system of claim 1 , wherein the first optical duplicator comprises one or more of beam splitters, polarizing splitters, half-silvered mirrors, partial reflective mirrors, dichroic mirrored prisms, dichroic optical coatings and dielectric optical coatings, or a combination thereof.
4. The image display system of claim 1 , wherein N equals to 3 and the optical duplicator is a beam splitter comprising two partial reflectors and one complete reflector to split the light signal into three instances.
5. The image display system of claim 1 , wherein the first image projector is a laser beam scanning (LBS) projector or a digital light processing (DLP) projector.
6. The image display system of claim 1 , wherein the first combiner is not a holographic combiner.
7. The image display system of claim 1 , further comprising a first collimator positioned between the first image projector and the first optical duplicator to cause the motion directions of the light signals to become more aligned in a specific direction.
8. The image display system for eyebox expansion, comprising:
a first image projector generating multiple light signals for a first image;
a second image projector generating multiple light signals for a second image;
a first optical reflector comprising at least one optical element arranged to receive a first light signal of the multiple light signals corresponding to a pixel of the first image and generated by the first image projector, and redirect the first light signal of the multiple light signals towards a first combiner at a different angle of incidence caused by moving of the first optical reflector;
a second optical reflector comprising at least one optical element arranged to receive a second light signal of the multiple light signal corresponding to a pixel of the second image and generated by the second image projector, and redirect the second light signal of the multiple light signals towards a second combiner at a different angle of incidence caused by moving of the second optical reflector;
the first combiner positioned between the first optical reflector and an eye of the viewer, and arranged to receive and converge the multiple light signals to a first view area of the viewer's eye to expand an eyebox of the viewer's eye;
the second combiner positioned between the second optical reflector and the other eye of the viewer, and arranged to receive and converge the multiple light signals to a second view area of the other eye of the viewer to expand an eyebox of the other eye of the viewer; and
wherein a moving frequency of the first optical reflector is adjusted based on a projecting frequency of the first image projector so that the multiple light signals of the first image are projected to the view area of the viewer's eye within the time period of persistence of vision, a moving frequency of the second optical reflector is adjusted based on a projecting frequency of the second image projector so that the multiple light signals of the second image are projected to a second view area of the other eye of the viewer within the time period of persistence of vision,
wherein a light signal converged from the second combiner is a first redirected right light signal, a corresponding light signal converged from the first combiner is a first redirected left light signal, and the first redirected right light signal and the first redirected left light signal are perceived by the viewer to display a first virtual binocular pixel of an object with a first depth where both eyes of the viewer fixate,
wherein the first optical reflector moves back and forth between N positions to cause the first light signal of the multiple light signals to be projected to N view points within the first view area of the viewer's eye through the first combiner to create N instances of the first light signal, and N is an integer greater than 1, the first light signal is projected to a specific view point when the first optical reflector is at a corresponding position,
wherein the second optical reflector moves back and forth between M positions to cause the second light signal of the multiple light signals corresponding to the first light signal to be projected respectively to M view points within the second view area of the viewer's eye through the second combiner to create M instances of the second light signal, and M is an integer greater than 1, the another one of the multiple light signals is projected to a specific view point when the second optical reflector is at a corresponding position,
wherein light path extension of the N instances of the first light signal of the first image redirected from the first combiner and the M instances of the second light signal of the second image redirected from the second combiner virtually converge on a same converging point.
9. The image display system of claim 8 , wherein the first image is projected to a specific view point when the first optical reflector is at a corresponding position.
10. The image display system of claim 8 , wherein the first optical reflector continuously moves in a predetermined pattern to redirect the multiple light signals towards a first combiner at a different angle of incidence caused by continuously moving of the first optical reflector.
11. The image display system of claim 8 , wherein the first optical reflector is a one dimensional MEMS mirror, a two dimensional MEMS mirror, a polygon cylinder reflector, or a circular cylinder reflector.
12. The image display system of claim 8 , wherein a light source of the first image projector is one laser, light emitting diode (LED), organic light emitting diode (OLED), superluminescent diode (SLD), liquid crystal on silicon (LCoS), or liquid crystal display (LCD), or any combination thereof.
13. The image display system of claim 8 , wherein the first image projector is a laser beam scanning (LBS) projector or a digital light processing (DLP) projector.
14. The image display system of claim 8 , further comprising a first collimator positioned between the first image projector and the first optical reflector to cause the motion directions of the light signals to become more aligned in a specific direction.
15. The image display system of claim 8 , further comprising:
a support structure wearable on a head of the viewer;
wherein the first image projector, the second image projector, the first optical reflector and the second optical reflector are carried by the support structure; and
wherein the first combiner and the second combiner are carried by the support structure and positioned within a field of view of the viewer, wherein the pair of glasses has a prescription lens which carries the first combiner or the second combiner.