Abstract: A stereo slide mount intended to facilitate the mounting operation of a slide film and to improve the accuracy of the operation. A stereo slide mount 1 constructs its system of a plurality of kinds of stereo slide mounts 1 (#-E, - - - , and #E) in which the left and right apertures have an equal width W and an equal pitch PW and in which film positioning pines 6L and 6R formed on a base frame 2 and positioning pins 7L and 7R formed in a cover frame 3 have a pitch P.sub.P changed stepwise. The base frame 2 and the cover frame 3 are united by bringing the perforations of the film on the positioning pins 6L and 6R of the base frame 2 and by fitting the positioning pins in the pin holes 7L and 7R of the cover frame 3. The individual stereo slide mounts have different film offsets so that the parallax can be corrected to reproduce an accurate stereoscopic image by mounting the film on the mount having a numerals of the offset which is decided by a masking extent guide device.

Abstract: A transparency assembly including two generally transparent sheets, a transparent imageable sheet and a transparent protective sheet. The imageable sheet has a first major surface, a second major surface, and a plurality of side edges. The protective sheet is hingedly coupled to the imageable sheet by a full rotation hinge. The protective sheet has a first folded position where the protective sheet overlays at least a portion of the first major surface of the imageable sheet and a second folded position where the protective sheet overlays at least a portion of the second major surface of the imageable sheet. One or more flaps hingedly couple to one of the transparent sheets. The flap has a folded position and an unfolded position. In the folded position, the flap overlays at least a portion of the imageable sheet. In the unfolded position, the flap extends generally coplanarly alongside the imageable sheet.

Abstract: The present invention comprises a shielding member located proximate to an overhead projector for reducing unwanted reflection from a writing surface of the overhead projector directed toward a user of the overhead projector. Angled support braces support the shielding member, and attach to the shielding member such that the shielding member tilts at an angle to better intercept the unwanted reflection.

Abstract: An envelope includes a transparent sleeve for holding an overhead projector transparency. The envelope further includes at least one transparent flap which is hingedly connected to the sleeve along a long edge thereof. The flap defines a pocket, and a transparent supplemental information sheet or an opaque blocking sheet is inserted into the pocket of the flap for selectively juxtaposing the sheet with the transparency, thereby altering the display.

Abstract: A stereo slide mount is divided into a base frame 21 and a cover frame 22 in order to facilitate the operation for mounting the stereo slide and to improve correctness. The size of the windows of the base frame is equal to the size of the pictures of the films, and pins 25 are provided at four corners of the windows to engage with perforations of the film. The cover frame 22 has holes 26 that correspond to the pins 25 and can be fitted to the base frame. The cover frames 22 are prepared in plural kinds (#0, #1, --) in which the width C.sub.1 between the windows is equal to the width between the windows in the base frame, and the width W of the windows decreases stepwisely. Plural kinds of masking-amount guide devices 31 having the same size of windows as that of the cover frames and having a collimation pattern at the same position on the right and left windows, are successively and temporarily fitted to the base frame 21, and the image of the stereo slide films is observed using a stereo slide viewer.

Abstract: A transportable image display system having direct and projection viewing modes of operation. The image display system comprises a spatial light modulation structure for spatially modulating the intensity of light produced from a light source, and light diffusing panel of electro-optical construction having a light scattering state in which light being transmitted therethrough is scattered in a diffusive manner, and a light transmission state in which light being transmitted therethrough is transmitted without substantial scattering. In the illustrative embodiments, the spatial light modulation structure can be an electrically-addressable LCD panel, or slide-film structures to be viewed. During the direct viewing mode, light produced from the light source is scattered by the light diffusing panel and spatial intensity modulated by the spatial light modulation structure to form a first image for direct viewing.

Abstract: A ring binder holder for transparency sheets comprises an elongated, rectangular ring-engagable strip of sheet material such as plastic or heavy paper having two parallel longitudinal edges. A line of ring-engagable openings in the strip is parallel and adjacent to one of the edges. Along the other edge is a line of adhesive on the strip that is adapted to adhere and attach the strip to an edge of a plastic transparency sheet. An elongated opaque flap is hingedly attached to the strip along a line that extends the entire length of the strip between and parallel to the line of ring-engagable openings and the line of adhesive. The flap is hingedly movable between a closed position covering the adhesive line and an open position covering the ring-engagable openings and the adjacent edge of the strip.

Abstract: It is one object of the present invention to provide a portable information processing apparatus that can be employed with an overhead projector (OHP).A portable information processing apparatus according to the present invention comprises: a main body having a keyboard on an upper face; a lid having an internally mounted liquid crystal display panel and being hinged rotatably with the main body at the rear edge of the main body; and a tilting mechanism for positioning the front edge of the main body higher than its rear edge.

Abstract: An improved envelope for transparencies for overhead projectors comprising a substantially rectangular pocket made of a transparent sheet material, the pocket having two longitudinal side edges connected by shorter side edges, and being open at least along one side edge for insertion of a transparency, at least one opaque flap attached in a foldable manner along one of the side edges by means of a flexible adhesive tape, the tape comprising a flexible polyester backing having a thickness of from about 5 to about 15 micrometers, and coated on one surface of the backing is an adhesive layer, wherein the tape has a flexibility measurement of about 1.8 grams, and the flap is capable of remaining in the unfolded position on an overhead projector stage with minimal adhesive transfer at the operating temperature of the overhead projector.

Abstract: A manually-operated tray assembly for facilitating the handling of transparencies on an overhead projector. The tray assembly comprises a dispensing tray for holding a stack of transparencies prior to projection, and a receiving tray for accepting the transparencies following projection. The transparencies are slid one-at-a-time from the dispensing tray to the platen of the projector, and following projection, from the platen to the receiving tray by a stroke of the user's hand. The `used` transparencies accumulate in the receiving tray in a neat orderly stack. The dispensing tray is preferably arranged at a sloping angle relative to the platen of the projector so that only one transparency at a time is transferred to the platen. The receiving tray is also preferably arranged at a sloping angle relative to the platen to facilitate the transfer of transparencies from the platen to the receiving tray.

Abstract: A material selective device for projectors has a frame including a transparent top member and spaced opposed opaque side members that rests on the projector. A pair of opaque masking members slide in opposite sets of grooves in the inner faces of the side members to display only selected parts or all of material written on the top member or on a transparency supported by the device placed between the masking members or placed on the projector surface according to the selected positions of the masking members.

Abstract: An original conveying apparatus includes an original stacker, a separator for separating the stacked originals from an upper side and for supplying the separated originals, a conveyor for conveying the separated originals to pass them through a reading portion and holding the originals in page sequence, a driver for rotating the conveyor normally or reversely, a discharger for returning the original to the original stacker and a controller for controlling the driver, the discharger and the separator so that an original is selected and set on the reading portion.

Abstract: A system for the display of transparencies including a first transparency receiving tray, a second transparency receiving tray, and a staging system connected at one end to the first transparency receiving tray and at the other end to the second transparency receiving tray. This staging system includes a transfer belt extending across a staging area so as to move a transparency across the staging area, a motor drivingly connected to the transfer belt so as to selectively rotate the transfer belt in various directions, and an actuating guide positioned adjacent to the first transparency receiving tray so as to direct the transparency from the first tray to the transfer belt. A controller is connected to the motor so as to actuate the motor for moving a transparency across the staging area in a desired direction. A lift plate is mounted in the receiving trays so as to support a plurality of transparencies thereon.

Abstract: A new and improved device for supporting and transporting overhead transparencies which simplifies the usage of such transparencies comprising: a pair of essentially rigid planar primary lateral wall of an enlarged height and width positionable parallel with each other during the closed orientation, the planar primary panels having short lateral walls extending perpendicularly from the side edges and having short spine wall extending perpendicularly from the lower edge to form a partial box-like configuration, the lateral walls and spine walls providing bearing faces therebetween when in the closed orientation; a hinge coupling the outside extension of the spine walls of the two primary lateral walls allow the pivoting of each primary lateral walls away from other lateral wall; and two secondary lateral walls of an essentially rigid material having a short height and having a width essentially equal to the width of the primary panels, with hinges to couple the upper edge of each primary panel to the lower edg

Abstract: An apparatus for use in projecting a picture image onto a remote surface includes a frame assembly, a stage assembly, and a support assembly. The frame assembly receives a light source and a light pipe through which light from the light source is transmitted and cooled, the stage assembly supports a plurality of discrete transparencies, and the support assembly supports a projecting lens and a reflecting mirror. The stage assembly includes a stage glass for supporting discrete transparencies. The stage glass is rectilinearly displaceable so as to permit any discrete point of the stage glass to be positioned above a light source.

Abstract: An improved envelope for transparencies for overhead projectors comprising a substantially rectangular pocket made of a transparent sheet material, the pocket having two longitudinal side edges connected by shorter side edges, and being open at least along one side edge for insertion of a transparency, at least one opaque flap attached in a foldable manner along one of the side edges by means of a flexible adhesive tape, the tape comprising a flexible polyester backing having a thickness of from about 5 to about 15 micrometers, and coated on one surface of the backing is an adhesive layer, wherein the tape has a flexibility measurement of about 1.8 grams, and the flap is capable of remaining in the unfolded position on an overhead projector stage with minimal adhesive transfer at the operating temperature of the overhead projector.

Abstract: A system for facilitating the handling of overhead projector transparencies on an overhead projector of the type including an upwardly facing projector platen. The system includes a frame assembly to provide a support surface adjacent the projector platen. A transparency storage cassette is supported on the support surface in alignment with the projector platen and generally includes a housing defining a closed chamber. An upwardly biased follower plate is mounted within the chamber to support a stack of transparencies. An access door allows loading of the transparencies into the chamber. Between the door and the follower plate is a cam arrangement to move the follower plate downwardly against the bias when the door is moved to an open position to thereby facilitate the loading of the transparencies into the chamber.

Abstract: A notebook computer set for cooperating with projectors. The notebook computer set has a notebook computer pivotally connected with a liquid crystal display (LCD) pivotally connected with a cover. The notebook computer set also has a bracket attached to the housings of the projectors for carrying the notebook computer so that the LCD is sited on the panels of the projectors.

Abstract: A flat panel display that is convertible between direct and projection display applications is incorporated in an information processing device of a unitary construction. In preferred embodiment, the information processing device is selectively configurable as a laptop-style personal computer and a projection display panel. The device includes a base section that contains computer circuitry, supports data input keys, and is pivotally coupled to a display panel section having an addressable flat panel display and an opaque backing member in opposed face-to-face relation thereto. The display panel section is selectively positionable between a first position in which the flat panel display is directly observable by a user, a second position in which the backing member covers the flat panel display and the data input keys for storage purposes, and a third position in which the display panel section is generally nonoverlapping and co-planar with the base section.

Abstract: A transparency holder for use in a navigation device is disclosed. The transparency holder is positioned between a lens and a compass, and is adapted to receive a map transparency in one correct orientation only. The one orientation only feature is achieved by providing certain asymmetric features, such as off-center notches which engage complementary features in the navigation device. In the preferred embodiment, the transparency holder has integral upper and lower halves hinged together by a living hinge and sandwiching the map transparency therebetween.

Abstract: An overhead projector for projecting images contained on media. The projector includes a housing having first and second image media storage cassettes and a platen which moves between those cassettes. A lifter is mounted between the cassettes for lifting the media from the first or second cassette onto the platen for projection. The lifter includes a lifting drive and a media gripping device. An image projector is movably mounted to the housing and positionable over the first or second cassette to project an image from media positioned on the platen to a view area. The projector includes a movable arm containing an illumination source, mirror and lens. Image media contained in a cassette can be sequenced from that cassette to the other by lifting onto the platen, from the cassette, projected and deposited in the other cassette either manually, remotely, automatically, or semiautomatically.

Abstract: Apparatus for converting an overhead projector to use photographic slides includes a fresnel disk that shortens the illumination convergence point to match the focal length of a typical slide projector. The apparatus includes a base that covers the platen of the overhead projector to prevent illumination spillover, and supports projection optics over an aperture that admits illumination for projecting magnified images of slides onto a vertical viewing surface.

Abstract: A protector adapted to accommodate a transparency inserted therein in a moist state, the transparency drying out while in the protector and being thereafter maintained in clean, dust-free and dry condition so that it is useable with an overhead optical projector which casts the image carried by the transparency onto a viewing screen. The protector is constituted by an open-ended, rectangular sleeve formed of moisture-impermeable transparent synthetic plastic film material of high strength having front and rear panels between which the inserted transparency is sandwiched, and a sheet of hygroscopic transparent acetate film which is interposed between the moist transparency and the front panel. The sheet act to absorb moisture from the transparency and to dissipate it, thereby drying out the transparency.

Abstract: A liquid crystal display (LCD) panel employs a cholesteric polarizer which passes light of a first circular polarization, but reflects light of a second circular polarization. The LCD panel may be monochrome or color; in the color embodiments, several different color filters are used, each having one or more cholesteric polarizers tuned to a specific bandwidth in the visible spectrum. These polarizers replace dyed (neutral or dichroic) polarizers of prior art LCD panels, and provide improved color purity. The invention may be enhanced by providing a light recycling scheme whereby the handedness of the circularly polarized light reflected by the polarizers is changed and redirected back to the polarizers. This recycling scheme may also be adapted to provide an overhead projector having a high output polarized light source, particularly useful in conjunction with an LCD panel.

Abstract: Folder apparatus for holding and positioning a plurality of transparencies for projection by an overhead projector includes a base panel element with two wing panels extending outwardly and in opposite directions from and secured to the base element. The transparencies are disposed against one wing panel and are movable from the position against the one panel to a position on the base panel for projection, and are movable from the projection position on the base panel to a storage position against the second panel. Transparencies include hook elements which move in slots or tracks secured to the base panel.

Abstract: An improved envelope for transparencies for overhead projectors comprising a substantially rectangular pocket made of a transparent sheet material, the pocket having two longitudinal side edges connected by shorter side edges, and being open at least along one side edge for insertion of a transparency, at least one opaque flap attached in a foldable manner along one of the side edges by means of a flexible adhesive tape, the tape comprising a flexible polyolefin backing having a thickness of from about 30 micrometers or less, and coated on one surface of the backing is an adhesive layer, wherein the tape has a flexibility measurement of about 2.5 grams, and the flap is capable of remaining in the unfolded position on an overhead projector stage with minimal adhesive transfer at the operating temperature of the overhead projector.

Abstract: An improved envelope for transparencies for overhead projectors comprising a substantially rectangular pocket made of a transparent sheet material, the pocket having two longitudinal side edges connected by shorter side edges, and being open at least along one side edge for insertion of a transparency, at least one opaque flap attached in a foldable manner along one of the side edges by means of a flexible adhesive tape, the tape comprising a flexible polyester backing having a thickness of from about 5 to about 15 micrometers, and coated on one surface of the backing is an adhesive layer, wherein the tape has a flexibility measurement of about 1.8 grams, and the flap is capable of remaining in the unfolded position on an overhead projector stage with minimal adhesive transfer at the operating temperature of the overhead projector.

Abstract: A shading device of LCD projecting plate has a pair of shading board being capable of being adjusted to shade the rest projecting areas which are uncovered by the plate and to project the drawing or letters on the optical glass to a wall or a screen clearly whenever used with any projectors.

Abstract: A dash mounted microfiche reader and support is provided for attaching a portable microfiche reader to the dashboard of a vehicle. The reader includes an adjustable miniature lens assembly and a mirror unit that swings open for operation. A slide out housing for the reader is pivotally mounted on a leveling tray that is detachably mounted to the dashboard of the vehicle. A microfiche index is used to support the fiche during use.

Abstract: A system for facilitating the handling of overhead projector transparencies on an overhead projector of the type including an upwardly facing projector platen. The system includes a frame assembly to provide a support surface adjacent the projector platen. A transparency storage cassette is supported on the support surface in alignment with the projector platen and generally includes a housing defining a closed chamber. An upwardly biased follower plate is mounted within the chamber to support a stack of transparencies. A door allows loading of the transparencies into the chamber. Between the door and the follower plate is a cam arrangement to move the follower plate downwardly against the bias when the door is moved to an open position to thereby facilitate the loading of the transparencies into the chamber.

Abstract: A transparency changer attachment for an overhead projector includes hinged horizontal and vertical portions that are located over the projector cover glass and down the projector side, respectively. Transparencies are automatically sequentially fed by pick and retard rollers from a single cassette-loaded transparency stack in the vertical portion to belts and rollers located marginally of a viewing area defined in the horizontal portion, to bring them into registration with the cover glass for projection, and then return them to the single stack. A microprocessor circuit controls the stack side from which the next transparency is picked and to which it is returned, according to selection made by the user. The cassette is keyed to assure correct transparency orientation at loading. A sensor reads individual transparency identifying information to initiate rapid cycling to a particular next desired transparency.

Abstract: A calculator (20) or other computing device uses a remote display (22) set upon an elevated platform (26) above the base (12) of an overhead projector (10). Light through the base lens (14) is passed through the display (22) and is enlarged by lens (30).

Abstract: The invention relates to an overhead projector for projecting images, said projector including a liquid crystal display panel arranged in the imaging plane, an optical imaging unit and a lamp and reflector arrangement accommodated in a housing as well as a scanning means for stored data. Adjacent to the platen (18) covering the liquid crystal display panel (17), a data strip scanning means (20) is provided which is accessible from outside. A transparency (23) which shows pictures, diagrams or the like and can be placed on platen (18) comprises a data strip (25) for selective and/or joint projection with the liquid crystal images, said data strip extending into the area of the scanning means (20) when the transparency (23) is placed on platen (18).

Abstract: A module interposed between a slide tray and a projector provides a user selected random presentation of sequentially ordered slides. The module bottom simulates the tray bottom to align gates of the module and projector. The module top simulates the tray bottom to align gates of the tray and module. A microcontroller controls a lifter foot to keep unwanted slides from dropping into the module gate until the tray had been rotated by a hub assembly to the next desired slide position. The lifter foot then acts to lower a slide through the module to the lifter foot and projector, and return it after projection.

Abstract: A device for selectively masking portions of transparent visual material to be projected by an overhead projector onto a screen including an opaque flexible sheet attached at one side to the overhead projector and at the other to a rod portion of a spool. When not in use the opaque flexible sheet is wound onto the spool. A portion, or all, of the transparent material may be blocked from projection by rolling the spool over the transparent material so that the opaque flexible sheet covers the undesired material.

Abstract: The invention relates to a device for projecting television pictures, provided with three LCD channels, the LCDs mounted to a common support member, relative to which one of the LCDs occupies a fixed position, whereas the two other LCDs are each connected to the support member by means of three adjustment members. Each adjustment member is so designed that a movement parallel to the direction of movement of the light through the relevant LCD as well as a movement perpendicular to this direction can be achieved by means of the adjustment member at its coupling point.

Abstract: The present invention concerns a projection pad using a liquid crystal panel in which a transmission type liquid crystal panel is placed between a light source and a screen, and an image displace on the surface of the liquid crystal panel is displayed on a screen. In this type of the projection pad, energy of light projected from the light source is partially converted into heat energy at the inside of the projection pad, which increases the temperature of the projection pad thereby causing disadvantage such as liquefication of liquid crystals, abnormal operation of the panel controlling circuit, etc. It is, accordingly, necessary to provide an appropriate cooling mechanism to the inside of the projection pad. In the present invention, the structure of the cooling mechanism is adapted such that sufficient cooling effect can be obtained by an axial flow blower small in the size and reduced in the thickness thereby enabling to reduce the size and decrease the thickness of the projection pad itself.

Abstract: An overhead projector for transparencies is provided, and includes a conventional top glass or other transparent plate. The overhead projector also includes a conventional optical system including a projection light path. An additional glass or the like plate is supported above the top conventional glass plate and supports a transparency for projection. A masking member is provided either above or below the transparency. The masking member is movable to cover portions of the transparency while uncovering other portions thereof to project selected portions of the transparency at any given time. In addition an arrow or other message carrying unit is provided which may be above or below the transparency, and which is movable to direct attention to a particular area of the transparency.

Abstract: A device of the invention is associated with a projector including a horizontal platform on which document sheets are placed one after the other in order to project images thereof on a screen. The device includes two removable cassettes each fitted with levers carried by respective shafts actuated by respective electromagnets. Above the leading edge of each cassette there are two transverse shafts carrying return pulleys over which belts pass for driving the top document from a stack of documents in the cassette. The device includes a horizontal plate which is positioned in alignment with the platform of the projector. An application lies in projecting images during a lecture.

Abstract: A copy viewer having a support stand for holding material to be copied in a viewing position and a "see-through" display device for displaying copied material directly over the material to be copied.

Abstract: A laptop computer includes a display unit having a hollow display casing with a pair of window openings, a transparent LCD monitor display provided inside the display casing between the window openings, and a cover piece detachably mounted to the display casing at one of the window openings and having a mirror surface disposed adjacent to one side of the monitor display. The display casing has a lower hinge side detachably hinged to a rear hinge side of a main computer body. An extension cable is used to electrically connect the display unit and the main computer body when the display unit is detached from the main computer body. The cover piece is detachable from the display casing to permit the use of the display unit as a slide for an overhead projector, so that characters, graphs, etc. generated on the monitor display are projected onto a screen for viewing.

Abstract: A hand-held calculator has a transparent window carrying a liquid crystal display as well as transparent number and function key locations such that when placed on an overhead projector, the calculator can be used to demonstrate to a classroom of students all operations performed in a sequence of mathematical operations. The plastic casing of the calculator has one or more small holes passing through the casing at corners. Another feature of the calculator is an improved keyboard of relatively small domain size for each key, with a spacer grid on the back surface of the keyboard membrane panel overlay element, effective to provide pressure isolation of an active key from adjacent keys and also to prevent other pressures on the keyboard from causing mistaken entries. A further feature of the calculator is a protrusion or foot at each corner of the back of the calculator casing.

Abstract: A highlighting device and method of use for focusing audience attention on an overhead projection is disclosed whereby a generally flat color tinted and light transmissive body having upper and lower surfaces with an optional handle and feet is employed as a register/highlighter for aligning and emphasizing an information transparency sheet.

Abstract: An overhead type file sheet projector including a projector body with a cover provided at an upper face opening thereof, a light source and a projecting condenser lens placed in the projector body. A support arm extends from one side of the projector body to above the projecting condenser lens with a reflecting mirror and a projecting lens system held by the support arm. A stage movably is fitted to guide rails provided at opposite sides of an upper portion of the projector body, and guide members are provided on the stage. The guide members allow movement of the file sheet in a direction orthogonal to the guide rails. A file sheet and a jacket holder for use in the overhead type file sheet projector include pitch movement cuts formed at at least one edge of the file sheet body or the jacket holder body. The pitch movement cuts are formed such that the pitch movement cuts may be engaged with a file sheet movement fitting member formed on a stage movably placed on an upper portion of the projector body.

Abstract: A slide projector has a light table oriented at 60.degree. to a generally horizontal base and connected thereto by a detachable connector. The light table has a tray mounted thereon for movement into mutually orthogonal directions parallel to the plane of the light table and supported by a counterweight, the tray receiving a planar slide holder whose slides and windows are alignable with a window in the light table. A projection lamp is located at the front side of the window while the projection optics are located at the rear side of the window.

Abstract: An interactive image projection apparatus for the projection of computer generated images on a projection surface in cooperation with a light source and projection optics for projecting a beam of light from the light source onto the projection surface. The apparatus includes a substantially transparent image display device disposed in the beam of light and including means for receiving image-defining signals from a computer and producing an image based on the image-defining signals that is projected onto the projection surface in the beam of light. A touch screen, at least a portion of which is substantially transparent, is disposed in the beam of light between the image display device and the projection surface and includes means for generating a signal when touched for use as input information at the computer. Preferably, the touch screen is supported directly over the image display device.

Abstract: A presentation device for an overhead projector of this invention includes a frame-shaped casing, a transmissive-type liquid crystal panel fixed in the casing, first and second protective covers mounted on the casing to have predetermined gaps from the liquid crystal panel and to cover both surfaces of the liquid crystal panel, and exhaust fans disposed in the casing. In order to detachably mount the first and second protective covers to the casing, locking pawls and locking pieces which can be elastically deformed are formed on the outer edges of the first and second protective covers, and the notches and fitting holes to which the locking pawls and the locking pieces can be respectively fitted are formed in the casing.

Abstract: A cassette web transport mechanism is placed upon an overhead image projector. Multiple overhead projector slides are conveniently secured in a roll of the web. The web is moved in forward or reverse direction by remote control in order to display the desired slide through the projector.

Abstract: A display including a liquid crystal cell. The cell includes a liquid crystal material, a plurality of electrodes, and first and second polarizers. The first polarizer is located at a viewing side of the cell such that the vibration direction of light polarized thereby is non-parallel to the optic axis of the liquid crystal material as its front boundary layer. The second polarizer is located on a side of the cell remote from the first polarizer wherein the vibration direrction of light polarized thereby forms an angle with respect to the vibration direction of light polarized by the first polarizer. The liquid crystal is responsive to different magnitudes of the electric field for the display of perceived color differences.

Abstract: An automatic overlay feed apparatus (10) for feeding projectable overlays to the object area (16) of an overhead projector (12). The apparatus (10) comprises a frame (20) for being supported on an overhead projector (12) and scrolling means, including a first winding shaft (36) and a second winding shaft (38) for moving an overlay scroll (24) defining a plurality of sequentially arranged projectable overlay sheets (42) across the object area (16) of the projector (12) to allow selective positioning of such projectable overlay sheets (42) on the object area (16). The apparatus (10) also includes motor means for selectively rotating at least one of the winding shafts (36, 38), and remote control means for controlling the operation of the motor means from a position remote from the projector (12).