Abstract: A method for easily performing of centering operation is provided. A lens holder includes a lens barrel and an optical lens. Plural recessed portions are formed in the outer circumference of the lens barrel at regular intervals circumferentially. The recessed portions are recessed toward an inner circumference having a diameter greater than the outside diameter of the optical lens. When a centering operation is performed, the optical lens is mounted into the lens barrel, and then heated adjusting elements are inserted into the recessed portions from the outer circumference of the lens barrel. Thin-walled portions between the bottom surfaces of the recessed portions and the inner circumference are thermally deformed toward the optical lens and thus pushed against the lens. The amounts of insertion of the adjusting elements are adjusted separately, thus centering the optical lens.

Abstract: A polarization conversion device comprises a prismatic beam splitting assembly for separating p- and s- polarized polarized light orthogonal in the direction of polarization from a light source and a single sheet half-wave (?/2) plate attached to an exit surface of the prismatic beam splitting assembly for changing one of the p- and s-polarized light 90° in the direction of polarization. The single sheet half-wave (?/2) plate has a number of apertures arranged in a checked pattern and is prepared by die-cutting a single optical sheet using a pressing machine and adhered to the exit surface of the beam splitting assembly.

Abstract: A lens assembly includes plural lens components. A first lens element of the first lens component is aspherical and plastic, disposed on a side of a screen surface, for adjusting focus in image projection to the screen surface. A first lens barrel holds the first lens component. A second lens barrel holds a second lens component. A stationary barrel movably contains the second lens barrel. The second lens barrel is rotated helically relative to the stationary barrel, to adjust the focus for the plural lens components. Thereafter the first lens barrel is rotated helically relative to the second lens barrel, to correct image distortion for the plural lens components, and also to adjust a rotational position of the first lens element. So a gate mark on an edge portion of the first lens element is offset from an effective projecting region of the image projection.

Abstract: A projector includes a projection lens having a first lens. The first lens is a plastic lens made by injection molding using a single gate, and has a gate mark on its outer edge. The first lens also has a weld line at the opposite side to the gate mark, which extends from the outer edge. The first lens is positioned such that the gate mark faces a long side of a rectangular pattern of image light on the lens surface, and the weld line becomes disposed outside the rectangular pattern.

Abstract: An illumination apparatus is provided with an LED array including a plurality of LEDs and a second lens array including a plurality of lenses. The LEDs and the lenses are arranged in lengthwise and crosswise directions and aligned such that a relationship between a number of the LEDs and a number of the lenses are mutually prime with each other in both lengthwise and crosswise directions. Primary illumination light from the LED array is split into a plurality of pieces of secondary illumination light by the lenses and thereafter superposed to irradiate. All of pieces of the secondary illumination light are provided with different strength peak positions of the illumination light and therefore, light having a uniform intensity can be irradiated to an irradiated region.

Abstract: A reflective optical system for projectors comprises a single integral piece of transparent optical molding having at least an incident surface, an exit surface, and two or more internal reflection surfaces between the incident surface and the exit surface, each reflection power having a power, positive or negative. The reflective optical system is provided with grooves, desirably blackened grooves, formed between the internal reflection surfaces so as to block out undesirable light proceeding therein. The internal reflection surfaces are formed by coating an aluminum film on an outer wall of the transparent optical molding. The reflective optical system reflects incoming image bearing light through the incident surface on the internal reflection surfaces in turn and projects the image bearing light through the exit surface so as thereby to project an image on a remote screen.

Abstract: A projector is equipped with: a light emitting diode for emitting light; an image display element to which the light emitted from the light emitting diode is incident and which modulates the incident light and emits the light as image light; and an ultraviolet light incidence preventing member disposed between the light emitting diode and the image display element for preventing ultraviolet light from being incident to the image display element.

Abstract: A liquid crystal projector for full-color image projection has three LCD panels as light valve device, associated with respectively primary colors, for displaying an image in a color-separated manner. An ultra high pressure mercury lamp illuminates the LCD panels through three illuminating light paths associated with respectively the primary colors. A combining prism combines image light of the primary colors from the three LCD panels, to obtain full-color image light. A laser diode emanates auxiliary illuminating light of a red color among the primary colors according to laser emission, to compensate for shortage in light intensity in the red color. A ferroelectric shaking or vibrating device vibrates the laser diode, to keep visual noise inconspicuous in the auxiliary illuminating light.

Abstract: An R-light optical system 14, a G-light optical system 15, and a B-light optical system 16 are disposed correspondingly to an R-light LED chip 11, a G-light LED chip 12, and a B-light LED chip 13, which emit an red light (R light), a green light (G light), and a blue light (B light), respectively. The R-light optical system 14, the G-light optical system 15, and the B-light optical system 16 are formed by combining a reflecting plate, a refractive lens, and a diffraction grating appropriately. The R-light optical system 14, the G-light optical system 15, and the B-light optical system 16 distribute all of the R light, the G light, and the B light, which are diffused widely, toward a cross dichroic prism 17.

Abstract: A positioning structure having a positioning projection on attaching surface is provided. The attaching surface is inclined within an acute angle with respect to a direction orthogonal to an opening and closing direction of a mold for forming the surface. The positioning projection formed on the attaching surface is molded simultaneously by the metallic molding into a truncated right circular conical shape with a tapered trapezoid section that has a tapered surface inclined within an acute angle with respect to a direction perpendicular to the attaching surface on the outer circumference, and has a tapered front end extending in the perpendicular direction. When the angle of inclination of the attaching surface with respect to the direction orthogonal to the opening and closing direction of the mold is defined as “?”, and the angle of inclination of the tapered surface with respect to the direction perpendicular to the attaching surface is defined as “?”, ???>0 is satisfied.

Abstract: A lens assembly includes plural lens components. A first lens element of the first lens component is aspherical and plastic, disposed on a side of a screen surface, for adjusting focus in image projection to the screen surface. A first lens barrel holds the first lens component. A second lens barrel holds a second lens component. A stationary barrel movably contains the second lens barrel. The second lens barrel is rotated helically relative to the stationary barrel, to adjust the focus for the plural lens components. Thereafter the first lens barrel is rotated helically relative to the second lens barrel, to correct image distortion for the plural lens components, and also to adjust a rotational position of the first lens element. So a gate mark on an edge portion of the first lens element is offset from an effective projecting region of the image projection.

Abstract: A projector includes a projection lens having a first lens. The first lens is a plastic lens made by injection molding using a single gate, and has a gate mark on its outer edge. The first lens also has a weld line at the opposite side to the gate mark, which extends from the outer edge. The first lens is positioned such that the gate mark faces a long side of a rectangular pattern of image light on the lens surface, and the weld line becomes disposed outside the rectangular pattern.

Abstract: A method for easily performing of centering operation is provided. A lens holder includes a lens barrel and an optical lens. Plural recessed portions are formed in the outer circumference of the lens barrel at regular intervals circumferentially. The recessed portions are recessed toward an inner circumference having a diameter greater than the outside diameter of the optical lens. When a centering operation is performed, the optical lens is mounted into the lens barrel, and then heated adjusting elements are inserted into the recessed portions from the outer circumference of the lens barrel. Thin-walled portions between the bottom surfaces of the recessed portions and the inner circumference are thermally deformed toward the optical lens and thus pushed against the lens. The amounts of insertion of the adjusting elements are adjusted separately, thus centering the optical lens.

Abstract: A positioning structure having a positioning projection on attaching surface is provided. The attaching surface is inclined within an acute angle with respect to a direction orthogonal to an opening and closing direction of a mold for forming the surface. The positioning projection formed on the attaching surface is molded simultaneously by the metallic molding into a truncated right circular conical shape with a tapered trapezoid section that has a tapered surface inclined within an acute angle with respect to a direction perpendicular to the attaching surface on the outer circumference, and has a tapered front end extending in the perpendicular direction. When the angle of inclination of the attaching surface with respect to the direction orthogonal to the opening and closing direction of the mold is defined as “?”, and the angle of inclination of the tapered surface with respect to the direction perpendicular to the attaching surface is defined as “?”, ???>0 is satisfied.

Abstract: An polarization conversion device comprises a prismatic beam splitting assembly for separating p- and s-polarized polarized light orthogonal in the direction of polarization from a light source and a single sheet half-wave (?/2) plate attached to an exit surface of the prismatic beam splitting assembly for changing one of the p- and s-polarized light 90° in the direction of polarization. The single sheet half-wave (?/2) plate has a number of apertures arranged in a checked pattern and is prepared by die-cutting a single optical sheet using a pressing machine and adhered to the exit surface of the beam splitting assembly.

Abstract: A simple and compact illumination source device capable of efficiently cooling an LED comprises a mounting base board having a heat conductivity higher than 50 W/m·K for mounting an LED element thereon through heat transfer member, a metal supporting structure for supporting the mounting base board and a collimation lens held by the metal support structure. Heat generated by the LED element is transferred partly to the metal support structure and partly to the base mounting board and then released into the air through the metal support structure and partly to the base mounting board. The illumination source device is suitably used for projection image display devices.

Abstract: A zoom lens includes a movable barrel mounting a lens holder barrel having a focusing lens element for rotational and axial movement therein and a cam barrel mounting the movable barrel for rectilinear axial movement therein. The movable barrel is axially moved for zooming through slide engagement between zooming cam slots of the cam barrel and rectilinear axial guide slots of a stationary barrel when the cam barrel rotates and allows the lens holder barrel to axially moves through helicoids coupling. The movable barrel is provided with a moving range restrictive structure having a plurality of screw holes and a single screw pin selectively screwed in one of the screw holes for focus adjustment. The screw pin is exposed to the outside of the zoom lens all at once when the cam barrel is in a telephoto or wide-angle position or one by one during rotation of the can barrel.

Abstract: In a reflective liquid crystal projector, illumination light is separated into blue, green and red illumination light bundles. The three color illumination light bundles are respectively modulated through three reflective liquid crystal elements into blue, green and red color optical images. A first polarizing beam splitter prism directs the blue optical image to a first incident surface of a recombination prism, whereas a second polarizing beam splitter prism directs the red and green optical images to a second incident surface of the recombination prism. The three color optical images are recombined through the recombination prism into a full-color image, and the full-color image is projected through a projection lens onto a screen. The first and the second polarizing beam splitter prisms and the recombination prim are fixed merely at their bottom surfaces to a prism base plate.

Abstract: Green, red and blue S-polarized light beams are incident into respective green, red and blue liquid crystal light valves. In the green liquid crystal light valve, the green P-polarized light beams exit from pixels for performing the white dot display, and the green S-polarized light beam exits from pixels for performing the black dot display. In red and blue liquid crystal light valves, the red and blue S-polarized light beams exits from the pixels for performing the white dot display, and the red and blue P-polarized light beams exit from the pixels for performing the black dot display. The red and blue S-polarized light beams reflect on, and the green P-polarized light beam transmits through the cross-dichroic prism, to produce a full-color image. The full-color image is projected through a projecting lens on a screen.

Abstract: A zoom lens includes a movable barrel mounting a lens holder barrel having a focusing lens element for rotational and axial movement therein and a cam barrel mounting the movable barrel for rectilinear axial movement therein. The movable barrel is axially moved for zooming through slide engagement between zooming cam slots of the cam barrel and rectilinear axial guide slots of a stationary barrel when the cam barrel rotates and allows the lens holder barrel to axially moves through helicoids coupling. The movable barrel is provided with a moving range restrictive structure having a plurality of screw holes and a single screw pin selectively screwed in one of the screw holes for focus adjustment. The screw pin is exposed to the outside of the zoom lens all at once when the cam barrel is in a telephoto or wide-angle position or one by one during rotation of the can barrel.