1. A head-mounted display device, comprising:
a first casing which incorporates therein at least a display element, and has a light projection window for projecting image light from the display element;
a second casing which incorporates therein an eyepiece optical system with a refractive power, and has a light receiving window for receiving the incident image light projected through the light projection window and an eyepiece window for emitting the image light that has passed through the eyepiece optical system; and
a coupling portion for coupling the second casing to the first casing so as to make adjustable a length of an optical path between the light projection window and the light receiving window.
2. The head-mounted display device according to claim 1,
wherein the first casing is held, when in use, on the side of the head of a user so that the light projection window opens to the same side as the face of the user is directed; and
wherein the second casing is arranged, when in use, so that the light receiving window and the eyepiece window open to the face side of the user.
3. The head-mounted display device according to claim 1,
wherein the first casing has a guide outside a side surface of the first casing; and
wherein the coupling portion has a slide member which is provided to the second casing and to be guided along the guide so as to be slidably coupled to the first casing.
4. The head-mounted display device according to claim 3,
wherein the first casing and the second casing each have a light shielding member so as to shield external light entering the optical path between the light projection window and the light receiving window, across a slide range of the slide member.
5. The head-mounted display device according to claim 4,
wherein the slide member also serves as the light shielding member of the second casing.
6. The head-mounted display device according to claim 3,
wherein the slide member is provided so as to enclose the optical path between the light projection window and the light receiving window.
7. The head-mounted display device according to claim 4,
wherein the slide member is detachably attached to the first casing.
8. The head-mounted display device according to claim 1, further comprising a window member transparent with respect to image light from the display element, the window member being provided so as to cover in at least one of the light projection window and the light receiving window.
9. The head-mounted display device according to claim 1,
wherein the first casing is held, when in use, on the side of the head of the user so that the light projection window opens inward along the lateral direction with respect to the face of the user; and
wherein the second casing is arranged, when in use, so that the light receiving window opens outward along the lateral direction with respect to the face of the user and the eyepiece window opens to the face side of the user within a view field of an eyeball in the vicinity of the first casing, in front of the face of the user.
10. The head-mounted display device according to claim 1,
wherein the first casing is held, when in use, on the side of the head of the user so that the light projection window opens inward along the lateral direction with respect to the face of the user;
wherein the second casing is arranged, when in use, so that the light receiving window opens outward along the lateral direction with respect to the face of the user and the eyepiece window opens to the face side of the user; and
wherein the coupling portion couples the second casing to the first casing in such a manner that the second casing is slidable in the lateral direction with respect to the user.
11. The head-mounted display device according to claim 1,
wherein the eyepiece optical system has a positive refractive power and receives the image light incident from the display element, guides the image light to the front of an eyeball of a wearer, and emits the image light toward the eyeball, so as to make observable a virtual image formed by the image light;
wherein the head-mounted display device includes a slide operation portion which is provided so as to be slidable, with respect to the first casing, in an anteroposterior direction of the head of the wearer; and
wherein the slide operation portion is coupled to at least either the display element or an optical element in the eyepiece optical system in such a manner that the length of the optical path between the display element and the optical element is increased when the slide operation portion is slid in the anterior direction of the wearer.
12. The head-mounted display device according to claim 11,
wherein the display element is fixed to the first casing;
wherein the optical element is fixed to the second casing; and
wherein the slide operation portion is slidably provided to the first casing and coupled to the second casing so as to be attached to the optical element via the second casing.
13. The head-mounted display device according to claim 12,
wherein the slide operation portion is provided so as to be slidable across an outside surface of the first casing.
14. The head-mounted display device according to claim 13,
wherein the slide operation portion is provided so as to be slidable with respect to the first casing so that a virtual image can be observed in the line of sight that slopes downward within a view field of the wearer.
15. A head-mounted display device, comprising:
a display element;
a casing accommodating the display element;
an eyepiece optical system with a positive refractive power, which receives image light incident from the display element, guides the image light to the front of an eyeball of the wearer, and emits the image light toward the eyeball, so as to make observable a virtual image formed by the image light; and
a slide operation portion which is provided so as to be slidable, with respect to the casing, in the anteroposterior direction of the head of the wearer,
wherein the slide operation portion is coupled to at least either the display element or an optical element in the eyepiece optical system in such a manner that a length of an optical path between the display element and the optical element is increased when the slide operation portion is slid in the anterior direction of the wearer.
16. The head-mounted display device according to claim 15,
wherein the display element is fixed to the casing; and
wherein the optical element is coupled to the slide operation portion.
17. The head-mounted display device according to claim 16,
wherein the optical element includes a light guide member that has an incident plane for receiving the image light incident from the display element and an emitting plane for emitting the image light toward the eyeball of the wearer, the incident plane and the emitting plane being located on the near side in relation to the wearer.
18. The head-mounted display device according to claim 16,
wherein the casing has a first casing and a second casing;
wherein the display element is fixed to the first casing;
wherein the optical element is fixed to the second casing; and
wherein the slide operation portion is slidably provided to the first casing and coupled to the second casing so as to be attached to the optical element via the second casing.
19. The head-mounted display device according to claim 18, wherein the slide operation portion is provided so as to be slidable across an outside surface of the first casing.
20. The head-mounted display device according to claim 19, wherein the slide operation portion is provided so as to be slidable with respect to the first casing so that a virtual image can be observed in the line of sight that slopes downward within a view field of the wearer.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A method of manufacturing a ceramic sintered body having a different thickness along a predetermined axial direction, comprising the steps of:
providing a ceramic formed body having a dome shape including a projected upper surface and a concaved lower surface, and having a varying thickness along the predetermined axial direction;
accommodating the ceramic formed body in a hot press apparatus;
setting an upper forming mold and a lower forming mold each having a forming surface corresponding to an upper surface and a lower surface of the ceramic formed body;
applying a pressure along the predetermined axial direction of the ceramic formed body via the upper forming mold and the lower forming mold while heating the ceramic formed body to perform a hot press sintering thereof to thus form a ceramic sintered body; and
controlling a thickness of the ceramic sintered body in such a manner that a maximum thickness in the predetermined direction is not two times or more larger than a minimum thickness in the predetermined direction.
2. The method of manufacturing a ceramic sintered body according to claim 1, wherein a thickness of the ceramic sintered body is continuously varied from the maximum thickness to the minimum thickness.
3. The method of manufacturing a ceramic sintered body according to claim 1, wherein the hot press sintering is performed after a metal member is embedded in the ceramic formed body to be sintered.
4. The method of manufacturing ceramic sintered bodies according to claim 3, wherein the metal member is preliminarily formed corresponding to the forming surface of the upper forming mold or the lower forming mold, and then the thus formed metal member is embedded in the ceramic formed body to be sintered.
5. The method of manufacturing a ceramic sintered body according to claim 1, wherein the ceramic sintered body is symmetric with respect to said predetermined axial direction.
6. The method of manufacturing a ceramic sintered body according to claim 1, wherein the ceramic sintered body comprises aluminum nitide.