Head mounted display
A head mounted display has a display unit to generate a displayed image, an illumination unit to emit illumination light to the display unit, a projection unit to project image light from the display unit, and a light guide unit to transmit image light from the projection unit to pupils of a user. Here, the illumination unit has light source units, a microlens array that is illuminated by light emitted from the light source units and becomes a virtual secondary light source, a condensing optical member to focus light from the microlens array on the display unit, and a diffusion plate to diffuse light from the microlens array, and the diffusion plate is arranged closer to the condensing optical member than to the microlens array. As a result, a conjugate image is inhibited from being generated with the adoption of a microlens array.
1. A head mounted display that is mounted on the head of a user and displays an image in a visual field, comprising:
a display unit to generate a displayed image;
an illumination unit to emit illumination light to the display unit;
a projection unit to project image light from the display unit; and
a light guide unit to transmit image light from the projection unit to pupils of the user,
wherein the illumination unit has:
a light source unit to emit light;
a microlens array that is illuminated by light emitted from the light source unit and becomes a virtual secondary light source;
a condensing optical member to focus light from the microlens array on the display unit; and
a diffusion plate to diffuse light from the microlens array, and
the diffusion plate is arranged closer to the condensing optical member than to the microlens array.
2. The head mounted display according to claim 1 ,
wherein the condensing optical member is a single condensing lens, and
a first distance from the microlens array to the condensing lens and a second distance from the condensing lens to the display unit are substantially equal.
3. The head mounted display according to claim 1 ,
wherein the condensing optical member includes two condensing lenses,
a first condensing lens arranged on the side close to the microlens array is a meniscus lens,
a second condensing lens arranged on the side close to the display unit is a biconvex lens, and
the diffusion plate is arranged closer to the second condensing lens than to the first condensing lens.
4. The head mounted display according to claim 1 , wherein the condensing optical member is a concave mirror.
5. The head mounted display according to claim 4 ,
wherein the concave mirror and the display unit are arranged so as to face each other with a polarization splitter interposed,
the microlens array and the display unit are arranged in a substantially orthogonal geometric relationship, and
the diffusion plate and a quarter wave plate are arranged between the polarization splitter and the concave mirror.
6. The head mounted display according to claim 4 , wherein the concave mirror is an aspheric concave mirror or a plano-convex aspheric lens to the convex aspheric surface of which reflective coating is applied.
7. The head mounted display according to claim 1 , wherein a focal length of the condensing optical member is in the range of 8 to 14 mm.
8. The head mounted display according to claim 1 ,
wherein a polarization filter to be permeated only by linearly polarized light in a predetermined direction is stuck and integrated to the diffusion plate, and
the diffusion plate and the polarization filter that are integrated are arranged so that the diffusion plate may be located on the side of the microlens array and the polarization filter may be located on the side of the display unit.
9. The head mounted display according to claim 1 , wherein the diffusion plate is integrated into the condensing optical member by making the surface of the condensing optical member a sandy surface.
10. The head mounted display according to claim 1 ,
wherein the illumination unit has:
a bending mirror for bending a light path; and
a polarization splitter for guiding image light after the image light is reflected at the display unit to the projection unit,
the bending mirror and the polarization splitter are arranged so as to bend light in a short direction of a display region of the display unit, and
the bending mirror and the polarization splitter are substantially parallel.
11. The head mounted display according to claim 1 ,
wherein the light guide unit has an incident surface which receives image light and substantially parallel first and second internal reflective surfaces which propagate incident image light through total reflection, and
a plurality of substantially parallel partially reflective surface arrays for projecting image light are installed in the interior of the light guide unit.
12. The head mounted display according to claim 1 , wherein the illumination unit is arranged above the projection unit from the perspective of the user.
13. The head mounted display according to claim 1 , comprising a polarization splitter to form a light path to guide illumination light to the display unit and a light path to guide reflected light from the display unit to the projection unit,
wherein the polarization splitter is formed by sticking a wire grid film to a transparent substrate.
14. The head mounted display according to claim 1 further comprising:
an imaging unit to shoot an image in a direction of a visual field of the user;
a power supply unit to supply electric power;
a storage unit to store information;
a sensing unit to detect a position and a posture of the user;
a communication unit to communicate with an external device;
a voice processing unit to input or output a voice signal; and
a control unit to control an entire device.