Abstract: A prism (1) comprises a first inner surface (114A) that performs total reflection of all rays (20) entering from the exterior and allows ON light (21) to pass therethrough; a second inner surface (122) that allows the rays (20) and the ON light (21) to pass therethrough and performs total reflection of OFF light (22); and a third inner surface (134) that allows the ON light (21) to pass therethrough. A first end (1E1) of the first inner surface (114A) is located in proximity to and above a predetermined point (P) in the second inner surface (122). The prism (1) is regarded as a plane parallel plate having a second outer surface (121) and a third outer surface (133).

Abstract: There is provided an optical device comprising an illuminant for emitting light; light condensing means composed of a reflecting mirror whose shape of reflecting plane is of rotational secondary curved surface and a condenser lens for converging approximately parallel fluxes; a mixing rod whose section is quadrangle, first lens means composed of at least one lens; and a reflecting optical element which is disposed in the vicinity of the position where a plurality of tertiary illuminants are formed and which reflects light in a desired direction. This optical device allows a distribution of illuminance whose intensity is excellently uniformed to be obtained even when a light flux is inputted from a direction inclined from the normal direction of the plane-to-be-illuminated by illuminating the optical device disposed out of an optical axis of the illuminator.

Abstract: A retrofocus lens system has a negative first, a positive second and a positive third lens group. The first lens group includes an aspheric first lens, a negative meniscus second and third lenses that are convex on the large conjugate side, and a negative meniscus fourth lens being convex on the small conjugate side. The second lens group includes a positive fifth lens and a sixth lens joined to the fifth lens. The third lens group includes a positive meniscus seventh lens being convex on the small conjugate side, a biconcave eighth lens, a positive ninth lens joined to the eighth lens, a biconvex tenth and eleventh lenses, and an aspheric twelfth lens. The system satisfies 0.8<f2/f3<1.5, 1.6<|f1|/f<2.

Abstract: A refracting optical lens 15 is provided to project light from transmitting means onto a convex mirror 16 to correct for pincushion distortion of the convex mirror 16.

Abstract: A display device scans a phosphor screen with three independently modulated ultraviolet beams. The screen is coated with three types of light-emitting phosphor dots, each emitting a different color of visible light when illuminated by ultraviolet light. A color separator such as an aperture mask or lens array directs each ultraviolet beam onto phosphor dots of one of these three types. Two or more of these display devices can be combined to obtain a larger screen size.

Abstract: There is provided an optical device comprising an illuminant for emitting light; light condensing means composed of a reflecting mirror whose shape of reflecting plane is of rotational secondary curved surface and a condenser lens for converging approximately parallel fluxes; a mixing rod whose section is quadrangle, first lens means composed of at least one lens; and a reflecting optical element which is disposed in the vicinity of the position where a plurality of tertiary illuminants are formed and which reflects light in a desired direction. This optical device allows a distribution of illuminance whose intensity is excellently uniformed to be obtained even when a light flux is inputted from a direction inclined from the normal direction of the plane-to-be-illuminated by illuminating the optical device disposed out of an optical axis of the illuminator.

Abstract: In a signal processing circuit used for displaying an image on a two-dimensional display element, an inverse-distorted image creator is provided which previously distorts the image to be displayed on the two dimensional display element so as to have a characteristic inverse to the distortion generated in the eyepiece optical system. The inverse-distortion correction is made for each of the image signals of the three primary colors R, G and B.

Abstract: A light source device or a projection type display apparatus has a pillar optical element; a condenser means; and a first lens effective to focus the image of the emitting end face of the pillar optical element at a surface to be irradiated; wherein the pillar optical element includes a tapered portion on a side of the incident end face and a non-tapered pillar portion on a side of the emitting end face, a cross-sectional area of the tapered portion continuously increasing from the incident end face toward the emitting end face and a cross-sectional area of the non-tapered pillar portion being constant.

Abstract: A projection display device comprises: a diaphragm for the illuminating system disposed in the vicinity of a focal point of the light collected by the concave mirror; a collimation lens for rendering parallel the light passing through the aperture of the first diaphragm; a scattering-type liquid crystal light valve for forming forming image on its displaying surface; a field lens for converging the light rendered parallel by the collimation lens; a projection lens having an entrance pupil disposed in the vicinity of a focal point of the light converged by the field lens; and a second diaphragm having an aperture and provided in the projection lens. An aperture varying section of the first diaphragm varies the aperture diameter of the diaphragm of the illuminating system, and the other aperture varying section varies the aperture diameter of the diaphragm of the projection lens, thereby varying the diameter of an entrance pupil.

Abstract: An eyepiece optical system for projecting a plane image on a two-dimensional display element onto an eyeball as an extended virtual image, comprises a first group of lenses G1 including a positive meniscus lens L1 having a concave face toward the eyeball, a both-face aspeherical lens L2 and a both-face aspherical lens L3 having both convex faces in the vicinity of center and positive paraxial refractive power; and a second group of lenses G2 including a both-face aspherical lens L4 having both concave faces in the vicinity of center and negative paraxial refractive power, the first and second groups of lenses being arranged in order from the side of the eyeball. An eyepiece image display device uses such an eyepiece optical system.

Abstract: A stereoscopic image projector has a light valve controlled by two image signals. The light valve produces a polarized raster image in which some rasters are modulated by the first image signal and other rasters by the second image signal. A polarization switch changes the polarization of rasters modulated by the second image signal, thereby creating a stereoscopic image, which is projected through a projection lens onto a screen, and viewed through polarizing eyeglasses. A color stereoscopic image is obtained by using three light valves and three polarization switches, one for each of the three primary colors, and combining their images for projection through a single projection lens. The projection lens is preferably a telecentric zoom lens consisting of three lens groups.

Abstract: A retrofocus projection lens system comprising, in order from a large conjugate side a first lens group having a negative refracting power and including a plurality of lenses, a second lens group having a positive refracting power, and a third lens group having a positive refracting power and including a plurality of lenses. The lens of the first lens group which is nearest to the large conjugate side is an aspherical lens, and the lens of the third lens group which is nearest to a small conjugate side is an aspherical lens. The retrofocus projection lens system desirable satisfy the following conditional expressions (1) to (3):1.8<D.sub.1 /f<3.0 (1)1.1<f.sub.2 /f.sub.3 <1.6 (2)1.5<.vertline.f.sub.1 .vertline./f<2.3 (3)where a symbol f.sub.1 designates a focal length of the first lens group, a symbol f.sub.2 designates a focal length of the second lens group, a symbol f.sub.

Abstract: A projection type display apparatus including a heater for heating the liquid crystal light valve. The heater includes a transparent electrically conductive film formed on a transparent substrate and is supplied with electric power therethrough to generate heat. The supplied electric power is controlled in accordance with the temperature of the liquid crystal light valve so that the liquid crystal layer in the liquid crystal light valve is in its optimum operating temperature range. The heater may include a filter through which the illumination luminous flux is incident upon the liquid crystal light valve. The filter passes only visible light when inclined within a certain range of angle with the luminous flux, and passes a progressively large amount of heat rays with increasing deviation of the angle from the certain range. A cold mirror and reflecting mirror may be used in place of the filter.

Abstract: An ocular optical system to be placed in front of a human eye forms a magnified virtual image of an original image displayed on a two-dimensional display element. The system has, in order from the eye: a positive first lens group including, in order from the eye, a meniscus first lens which has a concave surface directed toward the eye and a positive meniscus second lens which has a concave surface. A convex surface of the first lens directed toward the second lens and the concave surface of the second lens have the same radius of curvature and are bonded to each other. The system also has a second lens group including an aspherical third lens which has aspherical surfaces on both sides and has a negative on-axis refracting power; a third lens group including an aspherical fourth lens which has aspherical surfaces on both sides and has a positive on-axis refracting power; and a positive fourth lens group including, in order from the eye, a positive biconvex fifth lens and a negative biconcave sixth lens.

Abstract: A light source device including a light emitting element emits a luminous flux, which is converged by a reflecting mirror. A conical light-refracting element receives the luminous flux converged by the reflecting mirror and changes the cone angle of the luminous flux. The luminous flux exiting the conical light-refracting element is diffused by a holographic diffuser and is then converged by at least one lens. The reflecting mirror may have an elliptic curvature or a parabolic curvature. The light source device is also used to form a projector for a projection type display apparatus. In the projector, the luminous flux emitted from the light source device may be separated by color separators into a plurality of colors of light. Then, each color of light is directed to the corresponding one of a plurality of light valves. Then, a color synthesizer synthesizes the colors of light emitted from the light valves into a composite image which in turn is projected onto a screen.

Abstract: In a light source apparatus for use with a projection type display, at least one light source is provided for emitting light. A reflector is provided correspondingly to the light source in order to gather the light emitted from the light source into a small area to form a converged luminous flux. A light guide has at least one light input section into which the luminous flux is coupled. The light input section is provided correspondingly to the light source. The light guide combines the luminous flux received through the light input sections into a single beam of luminous flux. The light-guide has at least one light output section from which said luminous flux is output. The light source apparatus may also include light-refracting element provided between the reflector and the light-guide. The light-refracting element receives the converged luminous flux from the reflector to refract the converged luminous flux so as to couple the converged luminous flux, as a uniform luminous flux, into the light-guide.

Abstract: A projection display device comprises: a diaphragm for the illuminating system disposed in the vicinity of a focal point of the light collected by the concave mirror; a collimation lens for rendering parallel the light passing through the aperture of the first diaphragm; a scattering-type liquid crystal light valve for forming forming image on its displaying surface; a field lens for converging the light rendered parallel by the collimation lens; a projection lens having an entrance pupil disposed in the vicinity of a focal point of the light converged by the field lens; and a second diaphragm having an aperture and provided in the projection lens. An aperture varying section of the first diaphragm varies the aperture diameter of the diaphragm of the illuminating system, and the other aperture varying section varies the aperture diameter of the diaphragm of the projection lens, thereby varying the diameter of an entrance pupil.

Abstract: A retrofocus lens system comprises, in order from a large conjugate side: a first lens group having a negative refracting power and including a plurality of lens elements; a second lens group having a positive refracting power; and a third lens group having a positive refracting power. Each of the lens elements of the first lens group has a negative refracting power. Following conditional expressions (1) to (3) are satisfied:1.3<D.sub.1 /f<1.8 (1)0.7 <f.sub.2 /f.sub.3 <1.1 (2)1.1 <.vertline.f.sub.1 .vertline./f<1.6 (3)where D.sub.1 is air gap between the first lens group and the second lens group, f.sub.1 is a focal length of the first lens group, f.sub.2 is a focal length of the second lens group, f.sub.3 is a focal length of the third lens group, and f is a focal length of whole lens system including the first to third lens groups.

Abstract: A projection type display apparatus includes a light source, color separator, half-wave plate, a plurality of light valves, color synthesizer, and projection lens. The light source emits a substantially parallel illumination flux. The color separator separates the light emitted from the light source into light of three colors including red, green, and blue. The light of the respective color passes through the corresponding half-wave plate which is placed in the light path of the light and causes the plane of vibration of the light to rotate through a predetermined angle. Then, the light of each color exiting the half-wave plate passe through the corresponding light valve, being modulated into a color image. The color synthesizer synthesizes the color images into a single full-color image and the projection lens enlarges and projects the single full-color image formed.

Abstract: A projection-type display apparatus comprising a lamp, an ellipsoidal mirror, a diaphragm disposed in the vicinity of a secondary focus of the ellipsoidal mirror, a first color separating dichroic mirror for separating the light into a blue color beam and a beam having a wavelength outside the blue wavelength region, a second color separating dichroic mirror for separating the beam having the wavelength outside the blue wavelength region into a red color beam and a green color beam, light valves for displaying images respectively corresponding to the red, green and blue color beams, first lens for making the red, green and blue color beams respectively advancing toward the respective light valves into parallel or convergent beams, color synthesizing dichroic mirrors for synthesizing the red, green and blue color beams which have been transmitted through the respective light valves, and a projection lens for enlarging and projecting a synthesized beam onto a screen.