Method and apparatus for out-of-rate error detection in film processor temperature control system
US5235370A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 31, 1991 |
| Grant date | Aug 10, 1993 |
| Priority date | — |
| Expiry date | Jul 31, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03D13/007
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.