Apparatus for printing alphanumeric information on photographic slide mounts, the apparatus comprising:
- (a) a generally horizontal slide track along which the photographic slide mounts are advanced, the slide track having an entrance end and an exit end and including a film insertion station proximate the entrance end and a printing station between the film insertion station and the exit end;
- (b) film insertion means for causing a photographic film transparency to be at least partially inserted into the slide mount at the film insertion station;
- (c) mount indexing means for causing the slide mount to be indexed from station-to-station along the slide track;
- (d) a frame positioned generally below the slide track which includes first and second side supports and a top platform having a printing aperture therein at the printing station of the slide track;
- (e) guide means cooperating with the platform for defining the slide track from the film insertion station to the printing station;
- (f) a plurality of horizontal guides supported by the frame and defining a carriage track, the horizontal guides and carriage track both being positioned below the slide track and carriage track being aligned in a plane parallel to a plane defined by the slide track and running in a generally transverse direction to the slide track;
- (g) a carriage movable on the carriage track below the slide track;
- (h) a print head carried by the carriage below the slide track for printing alphanumeric characters through the printing aperture of the top platform of the frame onto a bottom surface of a slide mount when the slide mount is positioned at the printing station of the slide track;
- (i) carriage drive means for moving the carriage on the carriage track;
- and
- (j) control means for controlling the print head and the carriage drive means to print selected alphanumeric information on the slide mount positioned at the printing station, the control means including:
- (1) means for storing data representative of the alphanumeric information to be printed on the slide mount;
- (2) means for providing a carriage drive control signal to the carriage drive means to move the carriage in a selected direction on the carriage track;
- (3) means for providing signal pulses representative of the incremental motion of the carriage on the carriage track, the means for providing signal pulses including:
- (A) a linear optical encoder having a first end portion, a second end portion and an intermediate portion, with a plurality of lines spaced at predetermined incremental distances being carried on the intermediate portion of the linear optical encoder;
- (B) optical sensor means for optically sensing the lines of the linear optical encoder and producing signal pulses as the linear optical encoder moves relative to the optical sensor means as a result of movement of the carriage on the carriage track;
- (C) aperture plate means having an aperture which defines a window portion of travel of the carriage on the carriage track during which actuation of the print head is permitted;
- and
- (D) window sensor means for optically sensing the aperture and producing a signal as relative movement of the aperture occurs as a result of movement of the carriage on the carriage track;
- and
- (4) means for controlling the print head as a function of the stored data and the signal pulses, the means for controlling the print head initiating operation of the print head after a first predetermined number of signal pulses have been provided and being responsive to the signal from the window sensor means to disable the print head when the carriage is outside of the window portion of travel.