Abstract: A head-up display is configured to project an image on a transparent reflection member to cause an observer to visually recognize a virtual image, and includes a display device configured to display the image, and a projection optical system configured to project the image displayed by the display device as the virtual image for the observer. The projection optical system is configured to form the image as an intermediate image, and includes a first optical element configured to condense light, a first lens configured to condense light, and a second optical element configured to diffuse light. The first optical element, the first lens, and the second optical element are disposed in this order along an optical path from the display device.

Abstract: In a display device, an opening portion includes a first edge portion on a forward side and a second edge portion on a backward side of the opening portion in a traveling direction of a mobile object. When the display device is mounted on the mobile object, a line connecting an upper end of the first edge portion and a lower end of the second edge portion is taken as a reference line, and outside light that passes along the reference line and enters a light-transmissive member is taken as reference outside light, the reference outside light for the case where the opening portion is in a first position arrives at a lower position, at least partially in an optical path after the reference outside light is reflected at the light-transmissive member, than the reference outside light for the case where the opening portion is in the second position.

Abstract: The present disclosure is directed to an optical system having a reduction conjugate point on a reduction side and a magnification conjugate point on a magnification side, and internally having an intermediate imaging position having a conjugate relationship with each of the reduction conjugate point and the magnification conjugate point, the optical system including: a prism provided on the magnification side, the prism formed of a transparent medium; and a sub-optical system provided between the reduction conjugate point and the prism, the sub-optical system, wherein the prism includes a first transmission surface positioned on the reduction side, a second transmission surface positioned on the magnification side, and at least one reflection surface positioned therebetween, wherein the following Expression is satisfied: 0.40<(TN?((NI?1)/8))/PN2<0.64.

Abstract: A head-up display is configured to project an image on a transparent reflection member to cause an observer to visually recognize a virtual image, and includes a display device configured to display the image, and a projection optical system configured to project the image displayed by the display device as the virtual image for the observer. The projection optical system is configured to form the image as an intermediate image, and includes a first optical element configured to condense light, a first lens configured to condense light, and a second optical element configured to diffuse light. The first optical element, the first lens, and the second optical element are disposed in this order along an optical path from the display device.

Abstract: The optical system includes a light guide guiding an image light ray including a first light ray with a first wavelength range and a second light ray with a second wavelength range having wavelengths shorter than wavelengths in the first wavelength range, to a field of view region as a virtual image. The light guide includes a first dividing region including first dividing points dividing the incident first light ray and a second dividing region including second dividing points dividing the incident second light ray. The first dividing points include first and second points respectively corresponding to first and second peripheral regions of the field of view region. The second dividing points include third and fourth points respectively corresponding to the first and second peripheral regions. Dividing efficiencies E1 to E4 at the first to fourth points satisfy the following formula (1). ( E ? 2 E ? 1 ) ÷ ( E ? 4 E ? 3 ) × ( E ? 3 E ? 1 ) 2 < 0.

Abstract: The present disclosure provides an optical system that includes a prism having an incident surface, an exit surface, and one or more reflecting surfaces. The optical system includes a first scanning element configured to scan a light that enters and has a plurality of wavelengths in a first direction, and reflect the light in a direction of the incident surface of the prism. The optical system includes a second scanning element configured to scan in a second direction the light that exits from the exit surface of the prism, the second direction being orthogonal to the first direction. The incident surface of the prism has a concave shape with respect to the first scanning element.

Abstract: An optical system includes a display that emits a light flux visually recognized by an observer as an image, and a light guide body that replicates the light flux. The light flux is emitted from the emission surface after being expanded by being replicated in a first direction corresponding to a horizontal direction of the image visually recognized by the observer due to diffraction by a diffraction structure of an expansion region in the light guide body, a second direction corresponding to a vertical direction of the image, or both the directions. A coherence length of the light flux diffracted and emitted in the expansion region in the light guide body is smaller than twice a shorter interval between the diffraction structure and each of a front surface and a back surface of the light guide body.

Abstract: A light flux incident on the light guide body is replicated in a first direction or a second direction by a diffraction structure of an expansion region. When a normal direction with respect to the light guide body of the expansion region is defined as a Z-axis direction, and a tangential plane is defined as an XY plane, the diffraction structure of the expansion region is configured such that a light flux duplicated when the light flux incident on the expansion region is transmitted through the XY plane of the expansion region from a positive direction of the Z axis and a light flux duplicated when the light flux is transmitted through the XY plane of the expansion region from a negative direction of the Z axis are accommodated within a viewing angle at which the image is visually recognizable.

Abstract: An image display device includes a display, a light guide body, a controller, and a sensor. The light guide body includes an incident surface on which the light flux from the display is incident and an emission surface from which the light flux is emitted from the light guide body. The light flux incident on the incident surface of the light guide body is changed in a traveling direction in the light guide body, and is emitted from the emission surface so as to expand a visual field area by being replicated in a horizontal direction and a vertical direction of the virtual image visually recognized by the observer. The sensor that detects a physical quantity used to obtain a wavelength of the light flux. The controller controls a position and a shape of the image displayed by the display based on the physical quantity detected by the sensor.

Abstract: An optical system includes a light guide for guiding an image light ray output from a display element to a field of view region as a virtual image. The light guide includes a periodic structure formed in the body having a plate shape. The periodic structure has periodicity in three predetermined directions intersecting each other within a predetermined plane perpendicular to a thickness direction of the body. The periodic structure includes an in-coupling region dividing the image light ray into a plurality of image light rays and allowing the plurality of image light rays to propagate within the body in a plurality of branch directions including branch directions respectively parallel to the predetermined directions, and an exit region allowing the plurality of image light rays propagating in the plurality of branch directions within the body to emerge from the body toward the field of view region.

Abstract: An optical system includes a light guide for guiding an image light ray which is output from a display element and forms an image, to a field of view region of a user as a virtual image. The light guide includes a body having a plate shape, and an in-coupling region and an exit region which are formed in the body. The in-coupling region allows the image light ray incident from the display element to propagate within the body. The exit region allows the image light ray propagating within the body to emerge from the body toward the field of view region. The in-coupling region includes a periodic structure constituted by recessed or protruded parts in relation to a thickness direction of the body which are arranged to have periodicity in three predetermined directions intersecting each other within a predetermined plane perpendicular to the thickness direction of the body.

Abstract: A head-up display is configured to project an image on a transparent reflection member to cause an observer to visually recognize a virtual image, and includes a display device configured to display the image, and a projection optical system configured to project the image displayed by the display device as the virtual image for the observer. The projection optical system is configured to form an image as an intermediate image, and includes a first lens configured to condense light, and a first optical element configured to diffuse light. The first lens and the first optical element are disposed in this order along an optical path from the display device. The first lens is inclined with respect to a reference beam which is defined as a beam reaching a center of a viewpoint region of the observer and corresponding to a center of the virtual image.

Abstract: A light guide plate includes a hologram element that is a first hologram element including two or more diffraction cells, and a hologram element that is a second hologram element including a single diffraction cell.

Abstract: A head-up display is configured to project an image on a transparent reflection member to cause an observer to visually recognize a virtual image, and includes a display device configured to display the image, and a projection optical system configured to project the image displayed by the display device as the virtual image for the observer. The projection optical system is configured to form an image as an intermediate image, and includes a first lens configured to condense light, and a first optical element configured to diffuse light. The first lens and the first optical element are disposed in this order along an optical path from the display device. The first lens is inclined with respect to a reference beam which is defined as a beam reaching a center of a viewpoint region of the observer and corresponding to a center of the virtual image.

Abstract: An optical system includes: a projection optical system for projecting an image light ray output from a display element and forming an image; and a light guide including an in-coupling region for guiding the ray to an inside of the guide and allowing it to travel in a first axis direction within the guide, and a propagation region for allowing the ray from the in-coupling region to propagate in the direction of the first axis, and allowing part of the ray to travel in a predetermined direction including a directional component of a second axis perpendicular to the first axis. In an optical path of the ray, a distance from the projection optical system to an entrance pupil of the projection optical system relative to the element in a plane perpendicular to the first axis is longer than a distance from the projection optical system to the in-coupling region.

Abstract: A head-up display system includes a display that emits a light flux visually recognized by an observer as the virtual image, and a light guide body that guides the light flux to the light-transmitting member. The light guide body includes an incident surface on which the light flux from the display is incident and an emission surface from which the light flux is emitted from the light guide body. The light flux incident on the incident surface of the light guide body is changed in a traveling direction in the light guide body, the light flux is replicated into a plurality of light fluxes in a direction perpendicular to a horizontal direction of the virtual image visually recognized by the observer to be emitted from the emission surface so as to expand a visual recognition region.

Abstract: A head-up display system includes a display that emits a light flux and a light guide body that guides the light flux to the light-transmitting member. A light beam at a center of the light flux emitted from the display is incident while being inclined with respect to a normal direction of the incident surface of the light guide body. The light flux incident on the incident surface of the light guide body is changed in a traveling direction in the light guide body, the light flux is replicated into a plurality of light fluxes in a horizontal direction of the virtual image, and then the replicated light fluxes are further replicated in a vertical direction of the virtual image to be emitted from the emission surface so as to expand the visual recognition region. A light beam at a center of the light fluxes emitted from the light guide body is emitted toward the light-transmitting member while being inclined with respect to a normal direction of the emission surface of the light guide body.

Abstract: A head-up display of the present disclosure projects a display image on a transparent reflecting member. The head-up display includes: a display device that displays the display image; and a projection optical system that projects the display image displayed on the display device. On an assumption that light reaching a center of a viewpoint region of the observer and corresponding to a center of the virtual image is reference light, the projection optical system includes a prism element that has an incident surface, a reflection surface, and an emitting surface different from the incident surface sequentially in an optical path from the display device. The emitting surface is inclined to the reference light. An inclination amount ?2 of the reference light emitted from the emitting surface with respect to the emitting surface lies in a range of 15°<|?2|<45° in the optical path from the display device.

Abstract: The optical system includes a first sub-optical system including an aperture stop and a second sub-optical system including a prism. The prism has a first transmission surface located on a reduction side, a second transmission surface located on a magnification side, and at least one reflection surface between the first transmission surface and the second transmission surface. The first sub-optical system includes a plurality of rotationally symmetric lens elements.

Abstract: A head-up display includes a display device and a projection optical system; the projection optical system includes first and second optical elements arranged in order of an optical path from the image; and when optical paths corresponding to an upper end and a lower end of the virtual image are defined as an upper ray and a lower ray, respectively, and a diverging effect and a converging effect are defined as being negative and positive, respectively, the first and the second optical elements satisfy conditional expressions P_u1?P_l1<0 and P_u2?P_l2>0 (where P_u1 denotes a local power of the first optical element acting on the upper ray, P_l1 denotes a local power of the first optical element acting on the lower ray, P_u2 denotes a local power of the second optical element acting on the upper ray, P_l2 denotes a local power of the second optical element acting on the lower ray).