Claims
- 1. A method of calculating the fractional exposure of developed black and white photographic material, the developed material being processed in a processing system having a fixing stage and an in-line silver recovery unit associated with the fixing stage, comprising the steps of:
(a) determining the mass of silver recovered by the in-line silver recovery unit during a period of operation of the method; (b) calculating a first estimate for the fractional exposure of the photographic material in dependence on the determined mass of silver; and (c) using said first estimate as an input to an iterative process, to calculate a subsequent estimate for the fractional exposure (θ) of the photographic material.
- 2. A method according to claim 1, in which the iterative process is employed at least once and comprises the steps of:
(d) calculating an estimate for the silver leaving the fixing stage in processing fluid during said period of operation in dependence on the last calculated estimate for the fractional exposure; and, (e) calculating a subsequent estimate for the fractional exposure of the photographic material using the estimate for the silver leaving the fixing stage in processing fluid obtained in step (d).
- 3. A method according to claim 1, in which the first estimate for the fractional exposure of the photographic material is obtained by using the following equation:
- 4. A method according to claim 2, in which the subsequent estimate for the fractional exposure of the photographic material is obtained by using the following equation:
- 5. A method according to claim 4, in which the value of silver concentration during the period of operation is modelled after said period of operation to obtain an estimate for the value of AgEFF.
- 6. A method according to claim 5, in which a cumulative value of AgEFF is used to determine the fractional exposure of the photographic material, the cumulative value being determined as a sum of the values of AgEFF for each piece of photographic material processed during said period of operation.
- 7. A method according to claim 1, in which the silver recovery unit is electrolytic and in which the value of the silver concentration in the fixing stage during the period of operation is modelled to obtain a relationship between one or more of the operating parameter of the silver recovery unit and the silver concentration in the fixing stage, the relationship being used to determine the silver concentration in the fixing stage during a subsequent period of operation, the silver concentration being used to determine the fractional exposure during said subsequent period of operation.
- 8. A method according to claims 2, in which the silver recovery unit is electrolytic and in which the value of the silver concentration in the fixing stage during the period of operation is modelled to obtain a relationship between one or more of the operating parameter of the silver recovery unit and the silver concentration in the fixing stage, the relationship being used to determine the silver concentration in the fixing stage during a subsequent period of operation, the silver concentration being used to determine the fractional exposure during said subsequent period of operation.
- 9. A method according to claim 3, in which the silver recovery unit is electrolytic and in which the value of the silver concentration in the fixing stage during the period of operation is modelled to obtain a relationship between one or more of the operating parameter of the silver recovery unit and the silver concentration in the fixing stage, the relationship being used to determine the silver concentration in the fixing stage during a subsequent period of operation, the silver concentration being used to determine the fractional exposure during said subsequent period of operation.
- 10. A method according to claim 4, in which the silver recovery unit is electrolytic and in which the value of the silver concentration in the fixing stage during the period of operation is modelled to obtain a relationship between one or more of the operating parameter of the silver recovery unit and the silver concentration in the fixing stage, the relationship being used to determine the silver concentration in the fixing stage during a subsequent period of operation, the silver concentration being used to determine the fractional exposure during said subsequent period of operation.
- 11. A method according to claim 7, in which during said subsequent period of operation the value of the silver concentration in the fixing stage is modelled to update the relationship between the one or more operating parameters and the silver concentration of the fixing stage.
- 12. A method according to claim 7, in which the fractional exposure (θ) is calculated in dependence on the following equation:
- 13. A method according to claim 11, in which the fractional exposure (θ) is calculated in dependence on the following equation:
- 14. A method of control for use in a photographic processing system having processing stages including a developing stage, a fixing stage and an in-line silver recovery unit associated with the fixing stage, comprising the steps of:
calculating the fractional exposure of the photographic material in accordance with the method of claim 1; and using an exposure-dependent algorithm to determine an appropriate replenishment rate for at least one of the processing stages in dependence on the calculated fractional exposure.
- 15. A photographic processing system, comprising:
a fixing stage to receive and fix developed black and white photographic material; an in-line silver recovery unit associated with the fixing stage to recover silver from processing solution in the fixing stage; and control means to determine the mass of silver recovered by the in-line silver recovery unit and calculate the fractional exposure of the processed photographic material, in which the control means is arranged to iteratively calculate the fractional exposure of the photographic material in dependence on the determined mass of silver.
- 16. A system according to claim 15, further comprising a developing stage to develop photographic material and provide developed photographic material to said fixing stage and a washing stage to receive and wash photographic material from said fixing stage.
- 17. A system according to claim 15, in which the control means is arranged to calculate a first estimate for the fractional exposure of the photographic material in dependence on the determined mass of silver;
calculate a corresponding estimate for the mass of silver leaving the fixing stage in processing fluid during a period of operation thereof in dependence on the first estimate for the fractional exposure; and calculate a subsequent estimate for the fractional exposure of the photographic material using the estimate calculated for the silver leaving the fixing stage in processing fluid.
- 18. A system according to claim 15, in which the control means comprises a processing unit to receive at least one of a current and voltage signal from the in-line silver recovery unit and an input indicative of the silver content of the photographic material being processed and generate a control signal to control at least one of a developer, fixer or wash replenishment rate in dependence thereon.
- 19. A system according to claim 18, in which the processing unit is arranged to receive at least one operating parameter of the silver recovery unit in addition to the at least one of the current and voltage signal to generate the control signal.
- 20. A system according to claim 15, in which the control means includes a weighing device to weigh the in-line silver recovery unit and thereby determine the mass of silver recovered.
Priority Claims (1)
Number |
Date |
Country |
Kind |
0112108.6 |
May 2001 |
GB |
|
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to commonly assigned, co-pending U.S. patent application Ser. No. [Attorney Docket No. 82,453/MSS] entitled A METHOD AND SYSTEM FOR PROCESSING OF PHOTOGRAPHIC MATERIALS by Christopher B. Rider et al., filed concurrently herewith.