Modification of film processor chemistry proportional heating during replenishment
US5235371A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 13, 1991 |
| Grant date | Aug 10, 1993 |
| Priority date | — |
| Expiry date | Sep 13, 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). 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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.