Eastman-Kodak Company

Michael Newman

James T Samuels

A temperature control system (10) of an automatic film processor (12) includes developer and fixer recirculation paths (30, 40) having thermowell heaters (34, 44) and thermistors (35, 45), and a cooling heat exchanger (37) in the developer path (30) which passes in heat exchange relationship with water in a wash tank (23). The system (10) also has a blower (48), heater (49) and thermistor (52) in an air path of a dryer (24). Heater (34, 44, 49) and cooling heat exchanger (37) operation is normally controlled on a closed loop, feedback mode basis by comparing measured current temperatures in real time with preestablished setpoint temperatures. When system errors cause an absence of current valid measured temperature data, shutdown or lockout can be overridden, and temperature control continued on an open loop basis using stored historical measurement data and on-off duty cycle profiles.

Control of temperature in film processor in absence of valid feedback

A temperature control system (10) of an automatic film processor (12) includes developer and fixer recirculation paths (30, 40) having thermowell heaters (34, 44) and thermistors (35, 45), and a cooling loop (37) in the developer path (30) which passes in heat exchange relationship with water in a wash tank (23). The system (10) also has a blower (48), heater (49) and thermistor (52) in an air path of a dryer (24). Actual heating and cooling rates of heating and cooling cycles are determined based on temperature measurements by the thermistors (35, 45, 52). Heater (34, 44, 49) and cooling loop (37) operation is controlled by comparing measured temperatures with preestablished setpoint temperatures. Malfunctions of system (10) are identified by comparing actual rates with rates characteristic of normal operations. Measured temperature data is validated based on comparing measured temperature with temperature predictions calculated based on heat gain or loss relationships associated with particular heating or cooling cycles. Randomly occurring invalid data is disregarded for control and error diagnosis purposes.

Method for detecting non-valid states in film processor temperature

A temperature control system (10) of an automatic film processor (12) includes developer and fixer recirculation paths (30, 40) having thermowell heaters (34, 44) and thermistors (35, 45), and a cooling loop (37) in the developer path (30) which passes in heat exchange relationship with water in a wash tank (23). The system (10) also has a blower (48), heater (49) and thermistor (52) in an air path of a dryer (24). Actual heating and cooling rates of heating and cooling cycles are determined based on temperature measurements by the thermistors (35, 45, 52). Heater (34, 44, 49) and cooling loop (37) malfunctions are identified by comparing actual rates with rates characteristic of normal operations. Periodic readings of a precision resistor (89) are made to check for failures in analog-to-digital (87), multiplexing (86) and thermistor (35, 45, 52) circuits. An error-responsive fresh film inhibit feature, with user selectable override, is provided.

Method and apparatus for out-of-rate error detection in film processor

A temperature control system (10) of an automatic film processor (12) includes developer and fixer recirculation paths (30, 40) having thermowell heaters (34, 44) and thermistors (35, 45). The heating rate of a heating cycle is determined based on temperature measurements by the thermistor (35). The duty cycle of heater (34) is controlled in proportion to the difference between measured actual temperature and a preestablished setpoint temperature. When replenishment occurs, until the cooler slug of replenishment becomes mixed, heater duty cycle is chosen based on prereplenishment temperature as well as measured temperature. In a modified embodiment, until the slug is mixed, a single predefined heater duty cycle is set.

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Pittsford, NY, United States of America

Michael Newman