See-through type display apparatus and electronic device including the same
View Patent ↗A see-through type display apparatus includes an image projector configured to output image light, a waveguide configured to receive the image light output from the image projector and transmit the image light to a user's view, and a first lens having a negative refractive power and a second lens having a positive refractive power, which are arranged on both surfaces of the waveguide. Each of the first lens and the second lens includes one or more meta lenses and is configured to operate as a lens with almost no chromatic aberration, thereby implementing a thin optical system having good image quality.
1 . A see-through type display apparatus comprising:
an image projector configured to output image light;
a waveguide configured to receive the image light output from the image projector and transmit the image light to a user's view, the waveguide comprising a first surface through which the image light is output and a second surface opposite the first surface;
a first lens disposed on the first surface of the waveguide, the first lens having a negative refractive power, and comprising one or more meta lenses; and
a second lens disposed on the second surface of the waveguide, and the second lens having a positive refractive power,
the first lens including a first meta lens disposed on the first surface of the waveguide, the first meta lens having a first refractive power; and
a second meta lens disposed on the first surface and spaced apart from the first meta lens by a first distance, the second meta lens having a second refractive power opposite to the first refractive power.
2 . The see-through type display apparatus of claim 1 , wherein the first meta lens has a negative refractive power; and
the second meta lens has a positive refractive power; and
the first lens further includes:
a third meta lens spaced apart from the second meta lens by a second distance, the third meta lens having a negative refractive power.
3 . The see-through type display apparatus of claim 2 , wherein the first lens further comprises:
a first spacer disposed between the first meta lens and the second meta lens, the first spacer having a thickness corresponding to the first distance; and
a second spacer disposed between the second meta lens and the third meta lens, the second spacer having a thickness corresponding to the second distance.
4 . The see-through type display apparatus of claim 3 , wherein the first spacer and the second spacer have a same refractive index and a same thickness.
5 . The see-through type display apparatus of claim 1 , wherein the first meta lens has a positive refractive power; and
the second meta lens has a negative refractive power; and
the first lens further includes:
a third meta lens spaced apart from the second meta lens by a second distance, the third meta lens having a positive refractive power.
6 . The see-through type display apparatus of claim 1 , wherein one surface of the second lens is a convex refractive lens.
7 . The see-through type display apparatus of claim 1 , wherein the second lens comprises one or more meta lenses.
8 . The see-through type display apparatus of claim 7 , wherein the second lens comprises:
a first meta lens having a positive refractive power;
a second meta lens spaced apart from the first meta lens by a first distance, the second meta lens having a negative refractive power; and
a third meta lens spaced apart from the second meta lens by a second distance, the third meta lens having a positive refractive power.
9 . The see-through type display apparatus of claim 8 , wherein the second lens further comprises:
a first spacer disposed between the first meta lens and the second meta lens, the first spacer having a thickness corresponding to the first distance; and
a second spacer disposed between the second meta lens and the third meta lens, the second spacer having a thickness corresponding to the second distance.
10 . The see-through type display apparatus of claim 9 , wherein the first spacer and the second spacer have a same refractive index and a same thickness.
11 . The see-through type display apparatus of claim 10 , wherein the first distance and the second distance are d min or more, d min being represented by the equation below, where f is a focal length of the second lens, D is an effective diameter of the second lens, n g is a refractive index of the first spacer and the second spacer, and θ max is a maximum deflection angle of incident light by the first meta lens:
d
min
=
f
2
+
D
2
4
-
f
2
n
g
cos
θ
max
1
-
cos
θ
max
.
12 . The see-through type display apparatus of claim 10 , wherein the second lens further comprises a blocking member configured to block light incident on the second lens from passing through a center of the second meta lens.
13 . The see-through type display apparatus of claim 12 , wherein the blocking member is disposed in a central portion of the first meta lens.
14 . The see-through type display apparatus of claim 12 , wherein the blocking member is disposed in a central portion of the second meta lens.
15 . The see-through type display apparatus of claim 14 , wherein the blocking member has a diameter of Do min or more, DO min being represented by the equation below, where f is a focal length of the second lens, D is an effective diameter of the second lens, n g is a refractive index of the first spacer and the second spacer, and θ max is a maximum deflection angle of incident light by the first meta lens:
D
o
min
=
f
2
+
D
2
4
-
f
n
g
sin
θ
max
1
-
cos
θ
max
=
f
2
+
D
2
4
-
f
n
g
cot
θ
max
2
.
16 . The see-through type display apparatus of claim 1 , wherein an absolute value of the negative refractive power of the first lens is different from an absolute value of the positive refractive power of the second lens.
17 . The see-through type display apparatus of claim 1 , further comprising a vision correction lens detachably disposed adjacent to the first lens.
18 . The see-through type display apparatus of claim 17 , wherein the vision correction lens comprises a meta lens.
19 . An electronic device comprising:
a see-through type display apparatus; and
a processor configured to control the see-through type display apparatus to output an additional image that a user views,
wherein the see-through type display apparatus comprises:
an image projector configured to output image light;
a waveguide configured to receive the image light output from the image projector and transmit the image light to a user's view, the waveguide comprising a first surface through which the image light is output and a second surface opposite the first surface;
a first lens disposed on the first surface of the waveguide, the first lens having a negative refractive power and comprising one or more meta lenses; and
a second lens disposed on the second surface of the waveguide, the second lens and having a positive refractive power,
the first lens including:
a first meta lens disposed on the first surface of the waveguide, the first meta lens having a first refractive power; and
a second meta lens disposed on the first surface and spaced apart from the first meta lens by a first distance, the second meta lens having a refractive power opposite to the first meta lens.
20 . The electronic device of claim 19 , wherein the see-through type display apparatus comprises an eye-wearable device.