# US 8,570,244 B2 · Image display apparatus and head mounted display > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,244 B2 - Document ID: US8570244B2 - Status: Granted - Kind: B2 - Application number: 12/805,637 - Filed: 2010-08-11 - Published: 2011-03-03 - Granted: 2013-10-29 - Earliest claimed: 2009-08-31 - Assignees: Sony Corporation - Applicants: Hiroshi Mukawa - Inventors: Hiroshi Mukawa - Web page: https://patentgrep.com/patent/US8570244B2 ## CPC - G02B 27/0176: {characterised by mechanical features} - G02B 6/0018: {Redirecting means on the surface of the light guide} - G02B 6/0035: {provided on the surface of the light guide or in the bulk of it} - G02B 27/017: {Head mounted} - G02B 27/0172: {characterised by optical features} - G02B 6/00: Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings - G02B 2027/0123: {comprising devices increasing the field of view} - G02B 2027/0125: {Field-of-view increase by wavefront division} - G02B 2027/0154: {with movable elements} - G02B 2027/0159: {with mechanical means other than scaning means for positioning the whole image} - G02B 2027/0161: {characterised by the relative positioning of the constitutive elements} - G02B 2027/0178: {Eyeglass type (eyeglass details G02C)} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An image display apparatus includes: an image forming device; an optical system converting light emitted from the image forming device into parallel light; and an optical device to which the light beams converted into the parallel light by the optical system enter, in which the light beams are guided, and from which the light beams are emitted, wherein a central light beam emitted from the center of the image forming device, passing through the nodal point of the optical system and entering the optical device at an optical device center point intersects an XY plane defined by an X axis that passes through the optical device center point, and is parallel to the axis direction of the optical device and a Y axis that passes through the optical device center point, and coincides with the normal axis of the optical device at angles other than 0 degree. ## Claims ### Claim 1 A head mounted display comprising: (a) a frame shaped like glasses to be worn on the head of an observer; and (b) an image display apparatus attached to the frame, the image display apparatus including (A) an image forming device; (B) an optical system that converts light emitted from the image forming device into parallel light; and (C) an optical device to which the light beams converted into the parallel light by the optical system enter, in which the light beams are guided, and from which the light beams are emitted, wherein when a point where a central light beam that is emitted from the center of the image forming device and passes through the nodal point of the optical system on the side of the image forming device enters the optical device is defined as an optical device center point, an axis that passes through the optical device center point, and is parallel to the axis direction of the optical device is defined as an X-axis, and an axis that passes through the optical device center point, and coincides with the normal axis of the optical device is defined as a Y-axis, the central light beam intersects the XY plane at angles other than 0 degree. ### Claim 2 (depends on 1) The head mounted display according to claim 1, wherein the image display apparatus is pivotally attached to the frame, with a virtual straight line connecting the centers of two eyeballs of the observer who observes the image display apparatus as a pivot axis. ### Claim 3 (depends on 2) The head mounted-display according to claim 2, wherein at least one of the image forming device, the optical system, and the optical device is pivotally attached to the frame. ### Claim 4 (depends on 1) The head mounted display according to claim 1, wherein the central light beam is included in the YZ plane. ### Claim 5 (depends on 1, 4) The head mounted display according to claim 1 or 4, wherein the optical axis of the optical system is included in the YZ plane and intersects the XY plane at angles other than 0 degree. ### Claim 6 (depends on 1, 4) The head mounted display according to claim 1 or 4, wherein the optical axis of the optical system is parallel to the YZ plane, is parallel to the XY plane, and passes through a position shifted from the center of the image forming device. ### Claim 7 (depends on 1) The head mounted display according to claim 1, wherein assuming that the XY plane coincides with the horizontal plane, the angle θ at which the central light beam intersects the XY plane is an elevation angle. ### Claim 8 (depends on 7) The head mounted display according to claim 7, wherein the XY plane intersects the vertical plane at angles other than 0 degree. ### Claim 9 (depends on 8) The head mounted display according to claim 8, wherein the XY plane intersects the vertical plane at an angle θ. ### Claim 10 (depends on 7, 8, 9) The head mounted display according to any one claims 7 to 9, wherein the maximum value of θ is 5 degrees. ### Claim 11 (depends on 1) The head mounted display according to claim 1, wherein when an observer views a horizontally located object, a central light beam that is emitted from the optical device and enters the eyes of the observer forms a depression angle. ### Claim 12 (depends on 1) The head mounted display according to claim 1, wherein the frame is formed by a front portion arranged at the front of an observer, and two temple portions pivotally attached to both ends of the front portion via hinges. ### Claim 13 A head mounted display comprising: (a) a frame shaped like glasses to be worn on the head of an observer; and an image display apparatus attached to the frame, the image display apparatus including (A) an image forming device; (B) an optical system that converts light emitted from the image forming device into parallel light; and (C) an optical device to which the light beams converted into the parallel light by the optical system enter, in which the light beams are guided, and from which the light beams are emitted, wherein the image display apparatus is pivotally attached to the frame, with a virtual straight line connecting the centers of two eyeballs of the observer who observes the image display apparatus as a pivot axis. ### Claim 14 (depends on 13) The head mounted display according to claim 13, wherein at least one of the image forming device, the optical system, and the optical device is pivotally attached to the frame. ### Claim 15 (depends on 13) The head mounted display according to claim 13, wherein when an observer views a horizontally located object, a central light beam that is emitted from the optical device and enters the eyes of the observer forms a depression angle. ### Claim 16 An image display apparatus comprising: (A) an image forming device; (B) an optical system that converts light emitted from the image forming device into parallel light; and (C) an optical device to which the light beams converted into the parallel light by the optical system enter, in which the light beams are guided, and from which the light beams are emitted, wherein when a point where a central light beam that is emitted from the center of the image forming device and passes through the nodal point of the optical system on the side of the image forming device enters the optical device is defined as an optical device center point, an axis that passes through the optical device center point, and is parallel to the axis direction of the optical device is defined as an X-axis, and an axis that passes through the optical device center point, and coincides with the normal axis of the optical device is defined as a Y-axis, the central light beam intersects the XY plane at angles other than 0 degree. ### Claim 17 (depends on 16) The image display apparatus according to claim 16, wherein the central light beam is included in the YZ plane. ### Claim 18 (depends on 2, 16) The image display apparatus according to claim 16 or 2, wherein the optical axis of the optical system is included in the YZ plane and intersects the XY plane at angles other than 0 degree. ### Claim 19 (depends on 2, 16) The image display apparatus according to claim 16 or 2, wherein the optical axis of the optical system is parallel to the YZ plane, is parallel to the XY plane, and passes through a position shifted from the center of the image forming device. ### Claim 20 (depends on 16) The image display apparatus according to claim 16, wherein the optical device includes: (a) a light guide plate from which incident light is emitted after the light propagates in the light guide plate by total reflection; (b) a first deflecting means for deflecting the light incident on the light guide plate so that the light incident on the light guide plate is totally reflected in the light guide plate; and (c) a second deflecting means for deflecting the light, which propagates in the light guide plate by total reflection, multiple times so as to emit the light, which propagates in the light guide plate by total reflection, from the light guide plate, and wherein the central point of the first deflecting means is the optical device center point.