Abstract: An advance mechanism for perforated materials for advancing the material through a path of light. The mechanism includes a support structure adapted to be in line with a source of light so that light passes through an aperture in the support. The perforated material is supported and advanced along a pathway into and out of alignment with the aperture. A pawl mechanism including a spring is on the support adjacent to the aperture and normally positioned in a normally retracted position in alignment with a slot adjacent to the aperture in the support. Drive structure biases the spring and directs the pawl through the slot into engagement with a perforation in the material and then along the slot a predetermined distance to advance the material and then release the pawl permitting the spring to return the pawl to the retracted position out of the slot. The pawl is then returned to the normally retracted position. The movement of the pawl along the length of the slot is restricted.

Abstract: Apparatus for the tachistoscopic projection of an image of projectable material. The apparatus includes a supporting structure and a light source. A lens mechanism is on the supporting structure optically aligned with the light source. The supporting structure is adapted to support the projectable material between the light source and the lens structure. The apparatus is designed for effecting relative displacement of the lens structure and the support holding the projectable material so as to bring the projected image into focus for a controlled viewing time and then out of focus while the material to be projected is retained stationary in projection position. A cam arrangement is employed which includes a cam surface and a cam follower. A manual actuator is on the lens structure to rotate the lens structure for relative movement between the cam follower and the cam surface and to bring the projected image into and out of focus.

Abstract: An advance mechanism for perforated materials such as film strips. The mechanism advances the material through a path of light and includes a support structure adapted to be aligned with a source of light so that the light passes through a rotating aperture in the support and scans line of print. The structure is provided for directing the perforated material along a pathway into and out of vertical alignment with the aperture. A pawl mechanism including a spring on a support adjacent to the aperture and is in a normally retracted position in alignment with a slot adjacent to the aperture in the support. Drive structure is provided for cooperating with a biasing spring and directing the pawl mechanism through the slot into engagement with a perforation in the material and then along the slot a predetermined distance to advance the material. Thereafter the pawl mechanism is released by the drive structure to permit the spring to return the pawl to the retracted position out of the slot.