Abstract: An optical image lens assembly includes, from an object side to an image side, at least one optical lens element. The optical lens element is made of plastic material and includes a long wavelength light absorbing agent. The long wavelength light absorbing agent is uniformly mixed with the plastic material, wherein the optical lens element has refractive power, and at least one of the object-side surface and the image-side surface thereof is aspheric.

Abstract: A portable screen shade for a camera display includes a pre-cut, foldable cardstock sheet with four adjacent panels. Each panel has an irregular hexagonal configuration, with a larger base end tapering to a narrower viewing end. The base ends of the panels are interconnected along fold lines, with the end edges of the bases extending along a common plane. Each narrow end is spaced apart from an adjacent panel, with the narrow end edges also extending along a common plane. The sheet can be folded into a four-sided partial pyramidal frustum configuration, with an enlarged end configured to be located against the camera screen, and a narrower viewing end, with the sides of adjacent panels connected by an adhesive strip or tab-in-slot. Flap tabs springs extend across fold lines on pairs of the panels to maintain the screen shade in an expanded configuration, and enable it to be folded flat.

Abstract: An object of the present invention is to provide an I/O device, an I/O program, and an I/O method which enable easy manipulation. Another object of the present invention is to provide an I/O device, an I/O program, and an I/O method which enable easy manipulation on the basis of ergonomics. The I/O device includes a display device that can generate a stereoscopic image, a depth level sensor that measures a distance to an object, and a control unit that performs display on the display device in accordance with the depth level sensor. A detection region of the depth level sensor has a width in the depth level direction of the depth level sensor, and is composed of a curved measurement region, such that the radius of curvature on the far side in the depth level direction of the depth level sensor is different from the radius of curvature on the near side in the depth level direction of the depth level sensor.

Abstract: An alignment system uses a self-referencing interferometer that incorporates an objective lens system having a plurality of lens element groups. In an embodiment, the objective is configured and arranged to provide a large numerical aperture, long working distance, and low wavefront error.

Abstract: In one embodiment, a self-interference incoherent digital holography system including a light sensor and a diffractive filter configured to receive light from an object to be holographically imaged and generate holographic interference patterns on the light sensor. A self-interference incoherent digital holography system comprising: a light sensor; and a diffractive filter configured to receive light from an object to be holographically imaged and generate holographic interference patterns on the sensor.

Abstract: A projection-type optical module is provided. More particularly, the projection-type optical module is configured to have a plurality of reflective mirrors and disposed inside a vehicle or a pillar of the vehicle so as to display an image projected from an image module on a wide screen. The projection-type optical module can be disposed in a confined space of the interior of the vehicle, so that the interior space of the vehicle can be efficiently used. Furthermore, the projection-type optical module is configured such that an image refracted in a confined space is prevented from blurring, thus making it possible to display a clear projection image on the screen module.

Abstract: The projector system of the present disclosure has a projector, a mirror, an angle detector, and a calculator. The projector projects an image. The mirror tilts each of on intersecting two axes as an axis of rotation and reflects the image projected from the projector. The angle detector detects an inclination angle of the mirror. Based on the inclination angle, the calculator calculates a reflection-possible range of the mirror, a projection-possible range of the projector that corresponds to the reflection-possible range, and an image range so that the image is arranged within the projection-possible range.

Abstract: The lens arrangement has at least two lenses, wherein a first lens may be used for autofocus and optical image stabilization. The first lens is tilted to compensate for the shaking movement of the hand-held device and to stabilize the image to be captured on the image plane. The tilt action may occur in two degrees of freedom, wherein an actuator causes the first lens to tilt around a pivot. A second lens is a field flattener lens that compensates for the error caused by the difference between the image plane and the focus plane. The field flattener lens causes the focal plane of the first lens to lie in the image plane when the first lens is in a tilted position.

Abstract: An image projection apparatus includes a light source for emitting a light bundle, a display element forming an image by using the light bundle, and a projection system having: a lens unit refracting the light bundle so as to magnify and project the image and including first and second aspheric lenses, which are spaced from each other and change the refraction of the light bundle, and at least one spherical lens disposed between the first and second aspheric lenses; and a mirror for reflecting, toward the outside, the light bundle delivered by the lens unit.

Abstract: Laser projection system suitable for commercial motion picture theaters and other large screen venues, including home theater, uses optical fibers to project modulated laser beams for simultaneously raster scanning multiple lines on screen. Emitting ends of optical fibers are arranged in an array such that red, green and blue spots are simultaneously scanned onto the screen in multiple lines spaced one or more scan lines apart. Use of optical fibers enables scanning of small, high resolution spots on screen, and permits convenient packaging and replacement, upgrading or modification of system components. Simultaneous raster scanning of multiple lines enables higher resolution, brightness, and frame rates with available economical components. Fiber-based beam coupling may be used to greatly enhance the flexibility of the system.

Abstract: A lightweight, compact image projection module, especially for mounting in a housing having a light-transmissive window, is operative for sweeping a composite laser beam as a pattern of linear scan lines on a planar projection surface and for causing selected pixels arranged along each linear scan line to be illuminated to produce an image of high quality and in color.

Abstract: System and method for synchronizing the low speed mirror movement of a mirror display system with incoming frame or video signals, and synchronizing buffered lines of video data to the independently oscillating scanning mirror. According to one embodiment of the invention, the peak portions of the low speed cyclic drive signal are synchronized with the incoming frames of video by compressing or expanding the peak portion or turn around portion so that each video frame begins at the same location on the display screen. The actual position of the high frequency mirror is determined by sensors and a “trigger” signal is generated to distribute the signals for each scan line such that the scan lines are properly positioned on the display.

Abstract: An image display apparatus 100 that displays an image using a light modulated according to an image signal includes a projection optical system 90 that includes a projection lens 20, a first mirror 30 that reflects a light from the projection lens 20, and a second mirror 40 that widens an angle of a light from the first mirror 30 by reflecting the light, and projects the light modulated according to the image signal from an optical engine unit 10; a third mirror 50 that reflects a light from the projection optical system 90; and a screen 50 that transmits a light from the third mirror 50. The projection lens 20 and the second mirror 40 are arranged in such a manner that an optical axis of the projection lens 20 substantially matches an optical axis of the second mirror 40, and shift the light from the optical engine unit 10 to a specific side from the optical axis of the projection lens 20.

Abstract: Embodiments for lighted see-through displays include a plurality of light elements positioned thereon at select points arranged to convey information. The light elements may be selectively lit to provide fixed or moving information, or may even be programmed to change or even display like a marquee or even a television. Particular embodiments of the invention employ a lightweight, flexible substrate to support the light elements. Other embodiments employ one or more comparatively rigid substrates supporting rows of light elements. Particular applications for the lighted sign embodiments include display in vehicle windows such as police vehicle windows, construction and utility vehicle windows, and school bus and public transportation windows. Global Positioning System and radio signal receiver components allow for regional display of pertinent information in particular embodiments of the invention.

Abstract: A thin projection type image display device with a low chin height includes a cabinet, a screen, a projection optical system, an optical path changing unit, and a reflecting unit. The screen is disposed on a front side of the cabinet. The projection optical system enlarges and projects an image formed by a display element, and the optical path changing unit is disposed on the bottom of the cabinet to reflect the image enlarged and projected by the projection optical system. The reflection unit is disposed obliquely to the screen and below the screen to reflect the image reflected by the optical path changing unit toward the screen. The projection optical system is disposed in a space above a horizontal plane perpendicular to the screen, behind the front side of the cabinet, and below an optical path of light incident on a bottom of the screen.

Abstract: An image processing apparatus including a displaying part, a light source generating light and a display driving part displaying an image on the displaying part by controlling the intensity of the light generated by the light source on the basis of one of a plurality of image signals. A light shutting part passes or shuts out the light generated by the light source; and a controlling part controls the light shutting part to shut the light generated by the light source while the image signal which has been displayed on the displaying part is being changed into other one of the plurality of image signals. Thus, the present invention provides an image processing apparatus and an image processing method to prevent a transitional phenomenon from occurring when an image is changed.

Abstract: A display system has a device for projecting a light beam and a display. The light beam includes encoded data. The display includes light sources selectively activated according to the encoded data received from the device.

Abstract: System and method for synchronizing the low speed mirror movement of a mirror display system with incoming frame or video signals, and synchronizing buffered lines of video data to the independently oscillating scanning mirror. According to one embodiment of the invention, the peak portions of the low speed cyclic drive signal are synchronized with the incoming frames of video by compressing or expanding the peak portion or turn around portion so that each video frame begins at the same location on the display screen. The actual position of the high frequency mirror is determined by sensors and a “trigger” signal is generated to distribute the signals for each scan line such that the scan lines are properly positioned on the display.

Abstract: An imaging system includes a wavelength dependent aperture stop, which transmits light with different ranges of wavelengths through apertures of different diameters. Thus, different colored light will have different F-stops, which can be selected based on the power transfer and image quality requirements for the different colored light. For example, a smaller F-stop may be used with a weaker light source to produce a higher throughput for a specific range of wavelengths. Accordingly, the optical system's design and optimization is wavelength and F-stop dependent.

Abstract: Provided are a projection optical system, a projection television, and a method of manufacturing a lens included in the projection optical system. The projection optical system includes lenses for projecting color beams onto a screen. A color filter layer, absorbing at least one of the color beams, is coated on the surface of at least one of the lenses.

Abstract: The present invention relates to a display configured to display images that includes multiple display elements capable of controlling light within a visible-light spectrum. The display elements are arranged over a display surface of the display. The display also includes one or more receivers arranged with the display elements over the display surface of the display. The receivers are coupled with the display elements and receive transmitted image information. The receivers activate the display elements in response to, and in correspondence with, the image information.

Abstract: Methods for illuminating the display area of a liquid crystal panel (13) are provided. Illumination light (17) is compressed into a stripe which is scanned across the display area in synchronization with the display's refresh cycle. In particular, the scanning is performed so that for each row of the display, the majority of the illumination light which impinges on the row as a result of the scan is in the last half of the cycle fresh period for the row. In this way, the ability to display moving objects is improved.

Abstract: In a projection cathode ray tube device in which a projection cathode ray tube and a projection lens assembly are coupled and held by a coupler, superior focus characteristics and high resolution are realized by eliminating the deviation between the center of the phosphor screen of the cathode ray tube and the center of the lens assembly. In the cathode ray tube, each of the outside and inside surfaces of a faceplate is formed as a spherical convex surface which is curved toward an electron gun.

Abstract: A projection lens regulator for a projection television includes a base, a barrel and an immobilizing hoop. The base has an annular wall, a slope guide slot at the annular wall, and a resilient flexible sheet defined by a pair of incisions at an upper side of the annular wall. The barrel is fitted inside the annular wall of the base and has an annular wall and a slope guide rib at an outer surface of the annular wall of the barrel. The slope guide rib is movably received in the slope guide slot of the base. The immobilizing hoop has an annular wall fitted on the base, and an arched convexity, which is formed at an inner surface of the annular wall thereof, corresponding in position to the flexible sheet of the base.

Abstract: Laser projection system suitable for commercial motion picture theaters and other large screen venues, including home theater, uses optical fibers to project modulated laser beams for simultaneously raster scanning multiple lines on screen. Emitting ends of optical fibers are arranged in an array such that red, green and blue spots are simultaneously scanned onto the screen in multiple lines spaced one or more scan lines apart. Use of optical fibers enables scanning of small, high resolution spots on screen, and permits convenient packaging and replacement, upgrading or modification of system components. Simultaneous raster scanning of multiple lines enables higher resolution, brightness, and frame rates with available economical components. Fiber-based beam coupling may be used to greatly enhance the flexibility of the system.

Abstract: Projection lens systems for use with cathode ray tube (CRT) projection televisions are provided which have positive first lens units (U1) and negative second lens units (U2) where the negative second lens units are customized in terms of at least one optical property for at least two of the colors of light produced by the CRTs with which the units are used. The at least one optical property is not spectral transmission, although the second lens units can also be customized for spectral transmission. As illustrated in FIGS. 1B–1F and FIGS. 8B–8F, such customization of a non-transmissive property provides an effective and cost effective approach for improving the color performance of CRT projection lens systems. Constructions for the positive first lens unit which improve image contrast and reduce manufacturing costs are also provided.

Abstract: A full color video projector system using a light source and a single light valve. The output of the light source passes through a condenser lens. The lens is directed toward a splayed array of red, green, and blue dichroic reflector color filters. The reflected three primary color beams first pass through a lenticular lens array, comprised of a plurality of elongated cylinder lenses, arranged in parallel, co-planar relation. The lenticular array produces color stripe illumination pattern, which is redirected and focused by a relay optic upon a reflective micro-mirror light valve. The light valve includes three sub-pixels for every full-color screen pixel. The pixels are arranged in parallel stripes which correspond to the size and configuration of the color strip illumination pattern outputted by the lenticular array. Light valve address circuitry actuates appropriate sub-pixels to reflect incident light energy, in accordance with corresponding video image information.

Abstract: Projection lens systems for use with cathode ray tube (CRT) projection televisions are provided which have positive first lens units (U1) and negative second lens units (U2) where the negative second lens units are customized in terms of at least one optical property for at least two of the colors of light produced by the CRTs with which the units are used. The at least one optical property is not spectral transmission, although the second lens units can also be customized for spectral transmission. As illustrated in FIGS. 1B–1F and FIGS. 8B–8F, such customization of a non-transmissive property provides an effective and cost effective approach for improving the color performance of CRT projection lens systems. Constructions for the positive first lens unit which improve image contrast and reduce manufacturing costs are also provided.

Abstract: An image display technique which projects R, G, and B light rays on a display device to form an image with an increased utilization ratio of light and an increased screen brightness. R, G, and B light rays as a result of color separation are reflected by plural reflective surfaces on the inner side, etc. of a rotary polyhedral reflector, so that, as the reflector rotates around a central axis and its reflection plane sequentially changes from one reflective surface to a next one, the reflected light rays are projected on a display device surface in different positions and scroll in a prescribed direction.

Abstract: An optical apparatus for irradiating light emitted from a light source onto a predetermined object, comprising a polarized light separating optical element for passing a first of two linearly polarized light beams polarized in directions perpendicular to each other and reflecting a second of said two linearly polarized light beams of light emitted from said light source; a phase shifter for converting said first linearly polarized light beams passed from said polarized light separating optical element into substantially circularly polarized light; and a reflecting mirror for reflecting said substantially circularly polarized light passed from said phase shifter back toward and through said phase shifter so that said circulatory polarized light is converted into a third linearly polarized light beam, wherein light emitted from said polarized light separating element, passed through said phase shifter, reflected by said reflecting mirror, and passed back through said phase shifter is irradiated on said predeter

Abstract: A projection type image display apparatus comprises a light source unit; an integrator unit for mixing luminous fluxes emitted from the light source unit so as to homogenize their light quantity distribution; a curved mirror for bending the optical path of luminous fluxes, which are turned into uniform light by the integrator unit, toward a projection unit; and the projection unit for causing the luminous fluxes to carry image information and projecting these luminous fluxes onto a screen.

Abstract: Projection lens systems for use with cathode ray tube (CRT) projection televisions are provided which have positive first lens units (U1) and negative second lens units (U2) where the negative second lens units are customized in terms of at least one optical property for at least two of the colors of light produced by the CRTs with which the units are used. The at least one optical property is not spectral transmission, although the second lens units can also be customized for spectral transmission. As illustrated in FIGS. 1B-1F and FIGS. 8B-8F, such customization of a non-transmissive property provides an effective and cost effective approach for improving the color performance of CRT projection lens systems. Constructions for the positive first lens unit which improve image contrast and reduce manufacturing costs are also provided.

Abstract: An arrangement in which the light emitted by a source of light (44) is directed by means of illumination optics (12) onto a surface (25) by which an image can be generated that can be projected by means of projection optics (4), onto a screen, wherein the illumination optics (12) have an optical device (28) arranged following the source of light and a prism (10) positioned between the surface (25) and the optical device (28), and the light coming from the optical device (28) is deflected without reflection by means of the prism (10) herein the optical device (28) has a first optical axis (29), and wherein said projection optics comprises a first and a second partial optics (22, 24) having a shared second optical axis (20) and in that the surface (25) is reflective, whereby the first optical axis (29), together with the second optical axis (20), includes an angle that is smaller than 90°, and whereby the optical device (28) lies outside of an area that is traversed from the second partial optics (24) to th

Abstract: A rear-projection television set includes a television screen, an image projector, first and second imaging lens units, and first and second reflecting mirror sets. The television screen has an optical axis and first and second image rendering portions disposed on opposite sides of the optical axis. The image projector is disposed rearwardly of the television screen and is aligned with the optical axis. The first and second imaging lens units cooperate to separate the image output of the image projector into first and second image portions. Each of the first and second reflecting mirror sets receives a respective one of the first and second image portions from the first and second imaging lens units, and projects the respective one of the first and second image portions to a respective one of the first and second image rendering portions of the television screen.

Abstract: A projection lens system for an image projection apparatus that enhances the image aberration correction rate to achieve high resolution and luminance. The lens system includes a first lens group having first and second spherical lenses of positive refraction power movable along an optical axis, a second lens group having a third doublet lens formed with a lens of positive refraction power and a lens of negative refraction power in junction to correct chromatic aberration, and a fourth spherical lens to correct spherical aberration, a third lens group having lenses of positive refraction power, and a fourth lens group for correcting distortions having a seventh spherical lens being concave on both surfaces thereof, an eighth spherical lens of negative refraction power having a concave surface on one side and a convex surface on the other side, and a ninth lens of negative refraction power having an aspheric surface.

Abstract: A color video projection display system having an improved contrast ratio is disclosed. At least one reflective or transmissive panel, e.g., a liquid crystal on silicon (LCoS) panel, is arranged within the system to receive incident light of one or more designated colors via an input optical path. The reflective or transmissive panel modulates the incident light in accordance with corresponding applied signals, and the resulting modulated light is further processed via an output optical path to generate a viewable display. At least one low-retardance film is arranged within one of (i) the input optical path of the system between an input optical path polarizer and the panel, and (ii) the output optical path of the system between the panel and an output optical path polarizer, so as to increase a contrast ratio of the viewable display. The invention can be implemented in single-panel or multi-panel configurations.

Abstract: A short throw projection system and method for displaying a corrected optical image on a projection screen based on input image data that includes an electronic correction unit, an image projector and a reflection assembly. The electronic correction unit receives the input image data and generates pre-distorted image data. The image projector receives the pre-distorted image data from the electronic correction unit and projects a pre-distorted optical image that corresponds to the pre-distorted image data or a pre-distorted image compensated by the projection optic distortion. The optical reflection assembly is positioned in the optical path of the pre-distorted optical image to project an optical image on the projection screen. The reflection assembly can consist of various combinations of curved and planar mirrors as desired.

Abstract: A projection television has a screen with a three dimensional hologram on a film substrate for collecting light over a range of incident angles and redirecting the light more nearly forward. Vertical and horizontal holograms can have varying gain across a horizontal viewing span of ±40° and a vertical viewing span of ±20° can be stacked. Image projection tubes project an image onto at least one mirror that reflects the image along an optical path that converges at an angle of projection, &phgr;, between about 0° and 30° relative to an axis orthogonal to the screen. Each tube can have a separate mirror. The hologram redirects the images reflected to an angle of display relative to the orthogonal axis of the screen of from 0 to 5°.

Abstract: A high-brightness projection television is provided which includes a screen having a first lens for refracting an incident beam into a convergent beam, a second lens for refracting the beam refracted by the first lens into a divergent beam, and a protection plate for protecting at least the second lens, wherein an optical emission material is included in at least one of the above elements to convert invisible lights included in the incident beam into visible lights. Alternatively, the projection television may include an optical emission layer having the optical emission material between a light source and an image generator such as a liquid crystal display (LCD). Accordingly, vertical and horizontal angles of view are increased and overall brightness of the image is improved.

Abstract: A projection lens unit of a projection television (TV) includes a first lens group for focusing an image incident from an image generating source, a reflection mirror for reflecting the image projected from the first lens group, and a second lens group having the same optical axis as the optical axis of the first lens group for magnifying and projecting the image reflected from the reflection mirror to a screen. The first and second lens groups are installed in first and second single bodies, which are coupled to a third single body having the reflection mirror to reflect the image incident from the first single body to the second single body. By this arrangement, the focus of the projection lens unit is easily adjusted and the lens groups are conveniently coupled to each other. In addition, a defocused state of the projection lens unit can be easily minimized.

Abstract: An “extra-folded” projection display system includes a selectively reflective material (e.g., a linear reflecting polarizer) placed immediately behind the system's imaging screen. The display system includes an image projector that projects an image beam containing light of a predetermined linear polarization toward the imaging screen. The linear reflecting polarizer reflects the light in the image beam away from the screen. The reflected image beam then encounters a ¼-wavelength achromatic retarder which converts the linear polarization to circular polarization. The image beam next hits a mirror that reflects the light back through the ¼-wavelength achromatic retarder, which converts the circular polarization back to linear polarization, with the polarization director rotated 90° from the original polarization director. The linear reflecting polarizer then allows the light to pass through to the image screen.

Abstract: In a projection device with a matrix (50) located in an image plane for generating a video image, with optics (9) for projection of this video image on a screen and with a light source (3, 30) for illuminating the matrix (50), there is an arrangement by which the video image can be uniformly illuminated.

Abstract: A projector of the type which uses an optical modulator that modulates light by controlling the emitting direction of light applied to a light illumination surface in accordance with image information is provided with a reduction in size. In the projector a prism has a selective reflection/transmission surface which reflects illumination light emitted from an illumination optical system and impinging thereupon, and causes the illumination light to impinge upon the light illumination surface of an optical modulator at a predetermined angle. The prism allows the modulated light emitted from the optical modulator to be transmitted therethrough and emits the light to the projection optical system.

Abstract: Projection lens systems for use with cathode ray tube (CRT) projection televisions are provided which have positive first lens units (U1) and negative second lens units (U2) where the negative second lens units are customized in terms of at least one optical property for at least two of the colors of light produced by the CRTs with which the units are used. The at least one optical property is not spectral transmission, although the second lens units can also be customized for spectral transmission. As illustrated in FIGS. 1B-1F and FIGS. 8B-8F, such customization of a non-transmissive property provides an effective and cost effective approach for improving the color performance of CRT projection lens systems. Constructions for the positive first lens unit which improve image contrast and reduce manufacturing costs are also provided.

Abstract: Projection lens systems for use in CRT projection televisions are provided. The lens systems include a negative lens unit (U4) which is associated with the CRT during use of the lens system and four lens elements (L1, L2, L3, CR) on the image side of the negative lens unit (U4). Three of those lens elements (L1, L2, L3) are arranged as follows from the long conjugate to the short conjugate of the lens system: a first lens element (L1) which has a weak optical power and at least one aspherical surface; a second lens element (L2) which has a positive focal length and provides most of the optical power of the lens system; and a third lens element (L3) which has a positive focal length and at least one aspherical surface. The last lens element of the system is a corrector lens element (CR) which is located adjacent to the second lens element (L2) and has a weak optical power, at least one aspherical surface, and is substantially flat.

Abstract: An optical system in a projection television receiver includes: a screen for simultaneously displaying R (Red), G (Green) and B (Blue) images thereon; and a light source part comprising R, G and B cathode ray tubes. The R and B cathode ray tubes project the R and B images on the screen via a reflecting mirror, whereas the G cathode ray tube is set together with the R and B cathode ray tubes in a delta type array and projects the G image directly on the screen.

Abstract: In an image display apparatus having a light source having a plurality of light emitting devices, and making lights from the light source scan in a main scanning direction and in a subscanning direction to display on a screen an image having a predetermined number of pixels, scanning lines in the main scanning direction formed by the lights emitted from each of the light emitting devices are controlled to be superposed one on another on the screen. The plurality of light emitting devices in the light source may be separated into a certain number of light emitting device groups respectively outputting lights with which different image areas on the screen are irradiated. The light emitting device groups may be arranged in a direction corresponding to subscanning or in a direction corresponding to main scanning while being spaced apart from each other by a distance determined on the basis of a pixel pitch in the main scanning direction or the subscanning direction.

Abstract: A method for correcting for keystone distortion and reducing aliasing defects in a digital image for use by a digital image projector, includes the steps of receiving an original digital image; lowpass filtering the original digital image to provide a lowpass filtered digital image having reduced high frequency spatial components which contribute to aliasing defects introduced by digital keystone correction; processing the lowpass filtered digital image to provide for digital keystone correction; and sharpening the keystone corrected digital image.

Abstract: Disclosed is a focus control apparatus for a display. The focus control apparatus comprises an optical engine assembly including a lens, a connection tube, and an optical engine, a tube coupler connected to the connection tube, a tube adjusting bracket for guiding the movement of the tube coupler, and a focusing handle combined with one end of the connection tube so as to adjust the position of the connection tube. The focus control apparatus adjusts the focus of the lens by a simple manipulation using an adjusting knob. The focus control apparatus adjusts the focus of the lens not by the protrusion and the intrusion of the lens but by the backward and forward movement of the connection tube, thereby simplifying the structure, improving the productivity, and reducing the production cost.

Abstract: An optical system for a rear projection picture display has reduced size while maintaining screen size. Two plane mirrors are provided along a light path between a picture display unit and a screen. The first plane mirror at a projection lens side is made of a reflecting polarizer and is located along a light path between the second plane mirror and the screen. The two plane mirrors are set in a relative angle so that the incident angle of the light traveling from the projection lens to the first plane mirror is large as compared with the incident angle of the light traveling from the second plane mirror to the first plane mirror. A polarizing plate is attached at the rear side of the screen.