Display module and display device
A display module includes an image light generation device, a light-guiding member, a first reflection surface configured to reflect the imaging light incident via the light-guiding member, a first diffraction element configured to diffract the imaging light, and a second diffraction element configured to diffract the image light and form an exit pupil. The image light is sequentially incident on a first deflection surface, a second deflection surface, a second reflection surface, a third reflection surface, a fourth reflection surface, and a third deflection surface inside the light-guiding member, and a distance from a reference position where an optical axis of the exit pupil and an emission surface intersect to the second deflection surface is longer than a distance from the reference position to the first deflection surface and longer than a distance from the reference position to the second reflection surface.
1. A display module ( 10 , 10 a , 10 b ) comprising:
an image light generation device ( 20 ) configured to generate image light;
a light-guiding member ( 30 ) configured to guide the image light emitted from the image light generation device ( 20 );
a first reflection surface ( 31 ) configured to reflect the image light that is emitted from the image light generation device ( 20 ), passes through the light-guiding member ( 30 ), and is incident;
a first diffraction element ( 50 ) including a first incident surface ( 50 a ) and configured to diffract and deflect the image light that is emitted from the image light generation device ( 20 ), passes through the light-guiding member ( 30 ), and enters through the first incident surface ( 50 a ); and
a second diffraction element ( 70 ) including a second incident surface ( 70 f ) and configured to diffract and deflect the image light that is emitted from the first diffraction element ( 50 ), passes through the light-guiding member ( 30 ), and enters through the second incident surface ( 70 f ), and to emit the image light from the light-guiding member ( 30 ), thereby forming an exit pupil (G), wherein
the light-guiding member ( 30 ) includes a first deflection surface ( 30 b ), a second deflection surface ( 30 c ), a second reflection surface ( 30 d ), a third reflection surface ( 30 e ), a fourth reflection surface ( 30 f ), a third deflection surface ( 30 g ), and an emission surface ( 30 h ),
the image light emitted from the image light generation device ( 20 ) is sequentially incident on the first deflection surface ( 30 b ), the second deflection surface ( 30 c ), the second reflection surface ( 30 d ), the third reflection surface ( 30 e ), the fourth reflection surface ( 30 f ), and the third deflection surface ( 30 g ) inside the light-guiding member ( 30 ),
the first reflection surface ( 31 ) is provided at one of the first deflection surface ( 30 b ) and the second deflection surface ( 30 c ),
the first diffraction element ( 50 ) is provided at the other of the first deflection surface ( 30 b ) and the second deflection surface ( 30 c ),
the second diffraction element ( 70 ) is provided at the third deflection surface ( 30 g ), and
a distance (S 1 ) from a reference position (P) where an optical axis (Ga) of the image light deflected by the second diffraction element ( 70 ) and the emission surface ( 30 h ) intersect to the second deflection surface ( 30 c ) is longer than a distance (S 2 ) from the reference position (P) to the first deflection surface ( 30 b ) and longer than a distance (S 3 ) from the reference position (P) to the second reflection surface ( 30 d ),
wherein the first incident surface ( 50 a ) has a shape in which a central portion is recessed and curved relative to a peripheral portion in the incident direction of the image light (L 0 ),
wherein the first diffraction element includes a reflection-type volume hologram.
2. The display module according to claim 1 , wherein
the first diffraction element ( 50 ) is configured to diffract the image light at a diffraction efficiency highest in a first direction (k 11 ) when the image light is incident from a normal line direction (k 10 ) of the first incident surface ( 50 a ),
the second diffraction element ( 70 ) is configured to diffract the image light at a diffraction efficiency highest in a second direction (k 22 ) when the image light is incident from a normal line direction (k 20 ) of the second incident surface ( 70 f ), and
the first diffraction element ( 50 ) and the second diffraction element ( 70 ) are disposed so that
when a sum of a number of times the image light is reflected and a number of times an intermediate image (z, z 1 , z 2 ) is generated between the first diffraction element ( 50 ) and the second diffraction element ( 70 ) is an even number, an orientation of the first direction (k 11 ) relative to the normal line direction (k 10 ) of the first incident surface ( 50 a ) and an orientation of the second direction (k 22 ) relative to the normal line direction (k 20 ) of the second incident surface ( 70 f ) are in a same direction as viewed from a direction orthogonal to a virtual plane including a normal line (v 2 ) of the first incident surface ( 50 a ) and a normal line (v 4 ) of the second incident surface ( 70 f ) and
when the sum is an odd number, the orientation of the first direction (k 11 ) relative to the normal line direction (k 10 ) of the first incident surface ( 50 a ) and the orientation of the second direction (k 22 ) relative to the normal line direction (k 20 ) of the second incident surface ( 70 f ) are in different directions as viewed from a normal line direction of the virtual plane.
3. The display module according to claim 1 , wherein
a thickness of a portion of the light-guiding member ( 30 ) provided with the first deflection surface ( 30 b ) and the second deflection surface ( 30 c ) is thicker than a thickness of a portion of the light-guiding member ( 30 ) provided with the third deflection surface ( 30 g ).
4. The display module according to claim 1 , wherein
a first intermediate image (Z 1 ) of the image light is formed between the image light generation device ( 20 ) and the first deflection surface ( 30 b ) in an optical path of the image light and
a second intermediate image (Z 2 ) of the image light is formed between the first diffraction element ( 50 ) and the second diffraction element ( 70 ).
5. The display module according to claim 4 , wherein
the image light generation device ( 20 ) is disposed at a position where the first intermediate image (Z 1 ) is formed in the optical path of the image light.
6. The display module according to claim 1 , wherein
a first intermediate image (Z 1 ) of the image light is formed between the first diffraction element ( 50 ) and the second diffraction element ( 70 ) in an optical path of the image light and
the image light generation device ( 20 ) is disposed at a position where a distance between the image light generation device ( 20 ) and the second diffraction element ( 70 ) is shorter than a distance between the second deflection surface ( 30 c ) and the second diffraction element ( 70 ).
7. The display module according to claim 1 , further comprising:
a correction member provided facing a surface different from the second incident surface ( 70 f ) of the second diffraction element ( 70 ), and constituting a parallel plate together with the light-guiding member ( 30 ).
8. A display device comprising:
the display module ( 10 , 10 a , 10 b ) according to claim 1 and
a housing ( 90 ) configured to accommodate the display module ( 10 , 10 a , 10 b ).