Abstract: A paper feed system for a photographic printer which includes a motor driven takeup spool which pulls paper from a supply reel across a paper deck to the takeup spool. An encoder is turned by the paper, and provides encoder pulses which indicate incremental rotation of the encoder, and thus incremental movement of the paper. Prior to each paper feed cycle, a slow-down count is subtracted from a total feed length count to provide a high speed count. The motor is initially operated at high speed until the encoder has produced pulses equal to the high speed count. The motor is then switched to the low speed for the remaining portion of the paper feed corresponding to the slow-down count. During each paper feed cycle, the encoder pulses during the high speed portion of the paper feed are monitored to provide an indication of the average velocity of the paper during the high speed feed. The slow-down count for each paper feed cycle is a function of the average velocity from the previous paper feed cycle.

Abstract: A photographic printer includes a splice detector for detecting the presence of a splice in a photographic paper web. The splice detector is positioned upstream of the printing aperture of the printer, and provides a signal indicative of the presence of a paper splice prior to the time that the splice reaches the printing aperture. Following detection of the splice, the paper feed control of the printer advances the web a number of additional feeds sufficient to advance the splice past the printing aperture. As a result, recording of a photographic image on the portion of the print paper web containing the splice is avoided.

Abstract: A photographic printer includes large area transmission density (LATD) sensors and a digital processor, such as a microprocessor, which calculates red, green and blue exposure times based upon the LATD sensor values. Prior to an exposure cycle, the LATD sensors are initialized, and LATD sensor readings are taken. From these initial sensor readings red, green, and blue initial exposure times are calculated, and an exposure cycle is initiated based upon these initial exposure times. During the exposure cycle, additional sensor readings continue to be taken on an asynchronous basis, and red, green, and blue exposure times are recalculated each time a reading is taken. The exposure times used during the exposure cycle are continuously modified and updated as a function of the recalculated exposure times. A running average of the sensor readings is maintained, and the modified exposure times are based upon a weighted average of the most recent sensor reading and the running average.

Abstract: A system for providing digital data representative of a selected analog signal on the data lines of a programmable controller using a central processing unit. The system employs a conversion circuit which converts the input analog signal to digital data on output data terminals upon receipt of a conversion signal simultaneously with an analog signal and which creates a completion signal when the conversion is completed. The system can use at least two analog inputs that receive at least two analog conditions and convert a selected one of the analog conditions to an analog signal. Upon actuation of one of the input modules, the selected analog signal of the selected module is directed to the conversion circuit. After conversion, the conversion completion signal of a conversion circuit then deactivates the actuated input module for the next conversion cycle.