Display device, a vehicle with a display device and display virtual image method
A display apparatus ( 500 ) for displaying a virtual image (VIMG 1 ) comprises: an optical engine (ENG 1 ) to form input light (IN 1 ), which represents an input image (IMG 0 ), an expander device (EPE 1 ) to form light beams (B 3 P0,R ,B 3 P1,R ) of output light (OUT 1 ) by expanding light beams (B 0 P0,R ,B 0 P1,R ) of the input light (IN 1 ), the expander device (EPE 1 ) comprising: a waveguide plate (SUB 1 ), a diffractive in-coupling element (DOE 1 ) to form first guided light (B 1 a ) and second guided light (B 1 b ) by coupling input light (IN 1 ) into the waveguide plate (SUB 1 ), wherein the display apparatus ( 500 ) comprises a base (BASE 1 ) and an actuating mechanism (MOTOR 1 ) to cause rotary motion of the expander device ( 500 ) with respect to the base (BASE 1 ), wherein an angle (γ 1 ) between an optical axis (AX 0 ) of the optical engine (ENG 1 ) and the axis (AX 1 ) of rotation of the expander device ( 500 ) is in the range of 10° to 45°.
1. A display apparatus ( 500 ) for displaying a virtual image (VIMG 1 ), the display apparatus ( 500 ) comprising:
an optical engine (ENG 1 ) to form input light (IN 1 ), which represents an input image (IMG 0 ),
an expander device (EPE 1 ) to form light beams (B 3 P0,R ,B 3 P1,R ) of output light (OUT 1 ) by expanding light beams (B 0 P0,R ,B 0 P1,R ) of the input light (IN 1 ),
the expander device (EPE 1 ) comprising:
a waveguide plate (SUB 1 ),
a diffractive in-coupling element (DOE 1 ) to form first guided light (B 1 a ) and second guided light (B 1 b ) by coupling the input light (IN 1 ) into the waveguide plate (SUB 1 ),
a first out-coupling element (DOE 3 a ) to form output light (OUT 1 ) by coupling the first guided light (B 1 a ) out of the waveguide plate (SUB 1 ), and
a second out-coupling element (DOE 3 b ) to form output light (OUT 1 ) by coupling the second guided light (B 1 b ) out of the waveguide plate (SUB 1 ),
wherein the display apparatus ( 500 ) comprises a base (BASE 1 ) and an actuating mechanism (MOTOR 1 ) to cause rotary motion of the expander device (EPE 1 ) with respect to the base (BASE 1 ),
wherein an angle (γ 1 ) between an optical axis (AX 0 ) of the optical engine (ENG 1 ) and the axis (AX 1 ) of rotation of the expander device (EPE 1 ) is in the range of 10° to 45°.
2. The display apparatus ( 500 ) of claim 1 , wherein the optical axis (AX 0 ) of the optical engine (ENG 1 ) is parallel with an axial light beam (B 3 P0,R ) of the input light (IN 1 ), wherein said axial light beam (B 3 P0,R ) corresponds to a center point (P 0 ) of the input image (IMG 0 ).
3. The display apparatus ( 500 ) of claim 1 , wherein the diffractive in-coupling element (DOE 1 ) comprises a surface relief diffraction grating (G 1 ).
4. The display apparatus ( 500 ) of claim 1 ,
wherein the in-coupling element (DOE 1 ) has a first input grating vector (V 1a ) and a second opposite input grating vector (V 1b ),
wherein the first out-coupling element (DOE 3 a ) has a first output grating vector (V 3a ),
wherein the second out-coupling element (DOE 3 b ) has a second output grating vector (V 3b ),
wherein the sum of the first input grating vector (V 1a ) and the first output grating vector (V 3a ) is equal to zero,
wherein the sum of the second input grating vector (V 1b ) and the second output grating vector (V 3b ) is equal to zero.
5. The display apparatus ( 500 ) of claim 1 , wherein the optical engine (ENG 1 ) is arranged to form the input image (IMG 0 ) and to convert the input image (IMG 0 ) into a plurality of input light beams (B 0 P0,R , B 0 P1,R ) of the input light (IN 1 ), wherein the expander device (EPE 1 ) is arranged to form light beams (B 3 P0,R , B 3 P1,R ) of output light (OUT 1 ) by expanding the input light beams (B 0 P0,R ,B 0 P1,R ) of the input light (IN 1 ).
6. A vehicle ( 1000 ), comprising the display apparatus ( 500 ) of claim 1 .
7. A method for displaying a virtual image (VIMG 1 ), the method comprising:
providing a plurality of input light beams (B 0 P0,R ,B 0 P1,R ) by using an optical engine (ENG 1 ) such that the input light beams (B 0 P0,R ,B 0 P1,R ) correspond to image points (P 0 , P 1 ) of an input image (IMG 0 ),
forming output light beams (B 3 P0,R , B 3 P1,R ) of output light (OUT 1 ) by using an expander device (EPE 1 ) to expand the input light beams (B 0 P0,R , B 0 P1,R ) of the input light (IN 1 ), and
causing a rotary motion of the expander device (EPE 1 ), the expander device (EPE 1 ) comprising:
a waveguide plate (SUB 1 ),
an in-coupling element (DOE 1 ) to form first guided light (B 1 a ) and second guided light (B 1 b ) by coupling input light (IN 1 ) into the waveguide plate (SUB 1 ),
a first out-coupling element (DOE 3 a ) to form output light (OUT 1 ) by coupling the first guided light (B 1 a ) out of the waveguide plate (SUB 1 ), and
a second out-coupling element (DOE 3 b ) to form output light (OUT 1 ) by coupling the second guided light (B 1 b ) out of the waveguide plate (SUB 1 ), wherein an angle (γ 1 ) between an optical axis (AX 0 ) of the optical engine (ENG 1 ) and the axis (AX 1 ) of rotation of the expander device ( 500 ) is in the range of 10° to 45°.