Patent ID: 6385284
Filing Date: 2002-05-07
Classification: A24C,G01N

Abstract:
Dual calibration apparatus (1) for â€œon-lineâ€  or continuous monitoring of a physical property of a material, such as the specific gravity of a processed meat product or the density, and hence weight, of tobacco in a cigarette rod, the apparatus comprising:(a) means (19) arranged to direct radiation into a material having a physical property to be monitored, (b) first sensing means (23) arranged to sense levels of residual measurement radiation passing from the irradiated material and to provide respective measurement signals representative of said sensed levels of residual measurement radiation; (c) reference means (18) which is arranged to be located in the path of the radiation, optionally adjacent or within the material whose physical property is to be monitored, and which has radiation absorption characteristics corresponding to predetermined low and high radiation absorption characteristics of the material whose physical property is to be monitored: (d) second sensing means (22) arranged to sense levels of residual reference radiation passing from said irradiated reference means and to provide reference signals representative of said sensed levels of residual reference radiation; (e) means arranged to process the measurement and reference signals, to provide interpolated measurement signals; and characterised in that, said reference means (18) comprises a pair of spaced reference standards, a tow radiation absorption characteristic standard whose absorption characteristic corresponds to a minimum level of the physical property to be monitored and a high radiation absorption characteristic standard whose absorption characteristic corresponds to a maximum level of the physical property to be monitored, the interpolated results being corrected to take into account any variable operating parameters of the apparatus (1) and being representative of the actual monitored physical property.