Abstract: There is disclosed a liquid-crystal projection apparatus having a lamp device which has such a sealed or closed construction that a sound, produced upon bursting of a light-emitting tube, is suppressed and that the scattering of glass pieces is prevented. In this liquid-crystal projection apparatus, a lamp is sealed by a support member, supporting a concave mirror having two notches and an outer casing and a flat glass panel and an air passage is formed in the support member. The lamp is releasably attached to a lamp fixing member and two open portions are formed in this lamp fixing member and a cooling fan is fixedly connected to one of the two open portions.

Abstract: An overhead projector includes a housing including a stage which is formed in its top wall and on which a transparency bearing an image to be projected is placed and an air outlet formed in one of its two side walls, an exhaust fan incorporated in the housing for exhausting air in the housing through the air outlet of the housing, a projection light source such as a high illuminance halogen lamp disposed in the housing for illuminating the transparency on the stage from inside the housing, a projection head mounted for projecting a magnified image from the transparency on a screen and including a focusing lens and a reflecting mirror, a column mounted on the housing to hold the projection head over the stage, a Fresnel lens disposed inside the stage to converge light from the light source on the focusing lens of the projection head, a cooling fan, and air guides for guiding air delivered from the cooling fan so that the air flows along a surface of the stage.

Abstract: A liquid crystal display panel projector including a housing having a thermally isolated hot compartment which has an illumination source and a cold compartment which retains liquid crystal display panel. The housing includes individual cooling fluid paths for the hot and cold compartments. The display panel is disposed in the cold compartment where it is isolated from the thermal energy of the illumination source to provide a substantially stable thermal environment.

Abstract: It is an object of the invention to provide a video projector which can be driven by a battery and can be reduced in both size and weight. A packing case for a video projector is composed of a cabinet, which is divided into two upper and lower parts, and a cover disposed behind the cabinet. The cover is disposed removably with respect to the cabinet. By opening the cover situated behind the projector light source, a lamp forming the projector light source can be replaced easily. Also, the cover includes on the back surface thereof a battery mounting portion for mounting a battery used to drive the projector, so that the battery can be mounted to the outer back surface of the cover.

Abstract: Disclosed is a liquid crystal display unit comprising liquid twisted nematic liquid crystal material sandwiched between two polarizers. Transparent electrodes are provided on each side of the layer of liquid crystal for locally energizing liquid crystal material in the vicinity of two energized transparent electrodes. Polarized light passing through one polarizer is twisted or not twisted depending upon the energization state of the liquid crystal material and depending upon the second polarizer orientation does or does not pass therethrough. Accordingly, depending upon energization locations, images are formed which can be projected upon a screen. In preferred embodiments the liquid crystal display unit is used in conjunction with a cabinet to provide a low stress work station. A further embodiment includes a folded optical path in combination with the liquid crystal display so as to provide a compact projector.

Abstract: A video projection system having a liquid crystal panel with a video image, a projection lamp with ON/OFF control, a zoom lens with a zoom control mechanism, a focusing lens with a focusing control mechanism, an audio system with a volume control, a projection-lamp light detector, a heat sensor, a variable-speed cooling fan, a control module having a microprocessor and a digital-to-analog converter, a display, a keypad, an alarm/annunciator, a power supply with ON/OFF control, and an infrared based remote control system able to control power ON/OFF, zoom, focus, picture, and sound volume.

Abstract: An overhead projector comprises a hollow base comprising a writing plate and a reflective Fresnel lens below the writing plate and an air space below the Fresnel lens. A hollow support arm projecting up from one side of the base carries a projection head having an objective lens and deflection mirror. A lamp mounted in the transition between the support arm and the projection head directs light on the writing plate. The hollow support arm is in communication with the interior of the base to provide a cooling air flow path between openings in the base at the side opposite the support arm and openings in the support arm adjacent the projection head, behind which latter openings a blower is mounted. Ribs in the hollow base define air flow distributors for effectively cooling the Fresnel lens and electronic circuit components mounted in the hollow base.

Abstract: A projection display apparatus includes a light source unit for generating light for image formation, an electro-optical display device for displaying an optical image by utilizing the light emitted from the light source unit, and an enlarging/projection lens. The light source unit, the display device, and the projection lens are accommodated in a housing with vent openings. The housing also includes a fan for cooling the interior of the housing with cool air and a cooler for maintaining a display panel within a predetermined temperature range. The light source unit includes a lamp and a reflector and is designed not to cause image deformation and formation of a shadow of a discharge portion. In order to display a television image on the display device, all television image display circuit units excluding an antenna are accommodated in the housing. The enlarging/projection lens can control a magnification and a focal point of the image projected on the screen.

Abstract: An overhead projector comprises a housing having an upwardly facing writing plate and a Fresnel lens below the writing plate. A hollow support arm extending up from one side of the housing supports a projection head comprising a lamp directing light down onto the writing plate, a variable objective lens receiving an image from the writing plate and a deflection mirror for directing the image onto a projection screen. A power supply in the support arm supplies power for the projector including the lamp and a blower in the support arm for cooling the power supply and lamp. A microprocessor in the support arm has inputs receiving signals from sensors for sensing the distance from the projector to the screen, ambient brightness, brightness contrast in the projected image on the screen and the temperature of the power supply and the microprocessor. The microprocessor has outputs for regulating the focus of the objective lens, the speed of the blower, the brightness of the lamp and the voltage of the power supply.

Abstract: A reflection-type overhead projector for projecting large transparencies onto a remote screen. The overhead projector has a base with a Fresnel mirror that serves as a stage on which a transparency to be projected is placed, and a lamp housing for a projection lens with an associated mirror which is supported on a pivotable arm above the base. The lamp housing is formed with an opening for allowing the passage of light to illuminate the transparency on the stage. This opening is fitted with a protective screen for guarding the fingers from the heated illumination lamp.

Abstract: A projection display apparatus includes a light source unit for generating light for image formation, an electro-optical display device for displaying an optical image by utilizing the light emitted from the light source unit, and an enlarging/projection lens. The light source unit, the display device, and the projection lens are accommodated in a housing with vent openings. The housing also includes a fan for cooling the interior of the housing with cool air and a cooler for maintaining a display panel within a predetermined temperature range. The light source unit includes a lamp and a reflector and is designed not to cause image deformation and formation of a shadow of a discharge portion. In order to display a television image on the display device, all television image display circuit units excluding an antenna are accommodated in the housing. The enlarging/projection lens can control a magnification and a focal point of the image projected on the screen.

Abstract: An image projector has a pulsed or similar light source of high intensity and high heat emission housed in an opaque box having a light-diffusing glass panel in its forward side which is spaced behind a vacuum film-holding plate having a glass center. Between the box light and the film-holding plate is a compartment which is open on the front and back and is sandwiched between the light diffusing glass panel of the box light and the film-holding plate such that no light escapes into the room. Said compartment thus comprises an isolation chamber which passes light to the film but not heat. The box light and the isolation chamber each has its own blower system and independent, specially baffled vents such that air between the two does not intermix. The vents are so designed as to permit discharge of the air but inhibit the egress of light therethrough.

Abstract: A film transparency projector including a housing, a source of illumination for projecting light through a film transparency, a lens for focusing the image on a desired surface, an infrared filter for resisting passage of infrared radiation from the source of illumination to the film transparency, an ultraviolet filter for resisting passage of ultraviolet radiation from the source of illumination to the film transparency the ultraviolet filter including a filter member composed of an acrylic material having an ultraviolet absorbing additive and a vent for exhausting air from the housing. The infrared filter may consist of two angularly disposed spaced infrared filters. The ultraviolet absorbing material may be selected from the group consisting of benzophenones, benzotriazoles, substituted acrylonitriles and phenol-nickel complexes. The acrylic material may include methyl methacrylate.

Abstract: A control circuit is provided in projection apparatus to control the operating characteristics of the projection lamp. The projection lamp control circuit maintains a constant illumination output and color temperature of the projection lamp to provide improved operation and increased lamp operating life. The desired operating point of the projection lamp is accurately maintained by sensing the operating point of the projection lamp and utilizing the sensed deviation from the desired operating point to vary the output of a blower that provides cooling of the lamp. Thus, the operating point and color temperature of the projection lamp is accurately maintained in a closed loop arrangement by sensing the operating point of the lamp and controlling the blower output.

Abstract: A housing has a front with a window therein. A shock mounting device in the housing is affixed to the bottom thereof. A projector support device extends from the shock mounting device. A securing device releasably secures the slide projector to the projector support device in a manner whereby the slide projector is selectively adjustable in position relative to the bottom of the housing and light transmitted from the slide projector is transmitted through the window. Electrical conductors extend through the housing and are electrically connected to the slide projector for supplying electrical energy for energizing the projector. A screen spaced from the front of the housing receives light transmitted from the slide projector and presents an enlarged reproduction of an image on a slide in the slide tray of the slide projector.

Abstract: Disclosed is a blower assembly for use in dispersing heat from an image projector with minimum air flow noise by interposing a constant torque clutch formed of a dual wound spring between the blower and a motor output drive to permit the rate of rotation of the blower to vary in response to variations in air weight due to changes in temperature, atmospheric pressure, and moisture content.