Abstract: A projecting head mechanism of a projecting machine adapted to project an image generated by a non-reflective document is disclosed. A thermo-conducting metal piece is installed in the projecting head mechanism and the internal surface area of a projecting mirror is coated with silicon compound for evenly and repidly distributing the heat generated by the light beam received by the projecting mirror over the surface area of the projecting mirror, so that the heat will not be concentrated on a spot to damage the projecting machine.

Abstract: An improved overhead projector head is provided that reduces the vibration that can occur in an overhead projector head that is used to project images from an LCD panel placed on the stage of the projector. The improvements comprise adding a mounting plate between the support arm and the head bracket. The mounting plate is cantilevered from the support arm, and the head bracket is supported by spacers placed near the end of the mounting plate that is remote from the support arm. In alternative embodiments, the head bracket may be divided into two pieces separated by foam or other vibration damping material, or a conterweight may be added to the head assembly behind the support arm.

Abstract: An automatic latching mechanism for the post of an overhead projector includes a spring-biased collar slidably disposed on the post and a cam which lifts the collar as the post is raised and releases the collar to engage a retaining tang when the post reaches a position necessary for projection.

Abstract: An adjustment mechanism for use with an overhead projector having a post extending upwardly to support a projection head attached to the attachment mechanism incudes a wear pad partially surrounding the post, a friction pad disposed opposite the wear pad with respect to the post and a spring for urging the friction pad into the post.

Abstract: An attachment device for overhead projectors which permits blocking of the image display by changing the position of an opaque panel wherein the device is frictionally attached to the projection head. The opaque panel of heat transmitting foil is hingedly attached to a hood. The sides of the hood extend downwardly and are biased inwardly to engage the projection head.

Abstract: A four-element inverted telephoto projection lens assembly for use in conventional overhead projectors is disclosed. The lens assembly features a reduced projection distance from the lens assembly to the projection screen while retaining the same back focus as conventional two-element projection lenses for overhead projectors.

Abstract: A overhead projector including a projection lens and a deflection mirror for directing the light projected from the lens toward a screen, both the lens and the mirror being individually pivotally movable about horizontal axes parallel to each other and to the original support surface of a stage. The lens is pivotally movable in accordance with variations in the angle of inclination of the mirror and is also pivotally movable with the focusing operation of the lens by an interlocking mechanism. The lens is brought to a proper pivotally moved position by the mechanism according to the angle of elevation and to the focusing operation to project images free of trapezoidal distortion and less of focus.

Abstract: A portable overhead projector has a top surface which slopes downwardly from the rear wall to the front wall and includes stops on the top surface adjacent to the front wall for preventing a transparency from sliding off the top surface during use and to preset the distance of the leading edge of the transparency from the bottom edge of the protecting wall.

Abstract: An overhead projector includes a projection head which contains a pivoting mirror and a pivoting projection lens interconnected by a linkage. Rotation of the mirror causes rotation and translation of the projection lens and automatically corrects for Scheimpflug distortion and loss of overall focus of the projected image.

Abstract: An over head projector has a standard projection lens for projecting the whole view of an original image and a partial projection lens for projecting a part of the original image in enlarged scale. One of the projection lenses is selectively brought to a projection position for projecting the original image onto a projection screen. A stage for supporting the original image is vertically movable and is moved up and down when the projection lens is changed. The selection of the projection lens and the vertical movement of the stage are associated with each other so that the original image is always at a proper position with respect to the focal length of the selected projection lens.

Abstract: A retrofit assembly for replacing a lens-containing lamp in an overhead projector. The assembly comprises a quartz-halogen lamp, having an internal reflector and an enlarged base removably mounted in the projector, and a lens holding bracket removably mounted in the projector in alignment with the lamp. The bracket is resiliently pivoted toward the lamp and has a tab for striking the lamp base to retain the lens at a predetermined distance from the lamp.