GB1178321A - Information Retrieval System and Information Carrier therefor. - Google Patents

Abstract

1,178,321. Information retrieval systems. AMERICAN CYANAMID CO. 30 Jan., 1967 [9 Feb., 1966 (2)], No. 4504/67. Heading G4M. An information retrieval system utilizes coded symbols of at least two components formed on a substrate from inks having respectively differing characteristic absorption responses to plural radiation wavelengths. The components may comprise complex ions (e.g. chelates) of rare earth metals having atomic number in excess of 57, fluorescent in narrow bands. Excitation may be effected by narrow band gamma radiation from elemental nuclei in different solid, e.g. crystal environments producing characteristic radiations according, to the Mossbauer effect which when they impinge on nuclei and environments of a coding component having the same resonant frequency are absorbed and re-emitted in random directions. For detection readout, a gamma-ray beam containing the characteristic frequencies of the components of a coded ink system is absorbed and re-radiated at random by impingement on a symbol containing that component, but traverses unaltered a symbol devoid of the same; radiation detectors sensitive to specific re-radiation frequencies being placed outside the beam to respond to such re-radiation and operate conventional read-out circuitry. The detectors are sensitive either to the narrow band of gamma re-radiation of a specific component, or are non-selectively sensitive to the gamma re-radiations of all components, and their outputs are applied to a pulse height determining circuit in a conventional multichannel analyser, sensitive to responses in a particular range of pulse height; or the detector outputs may be scanned by a sweep circuit actuating in time sequency a desired readout device, e.g. a synchronized C.R.O. or multichannel recorder. Alternatively a single gamma-ray source and detector may be provided to examine a coding symbol, and the source is oscillated at discrete velocities causing Doppler displacement in the frequency or wavelength of radiation; the discrete velocities being synchronized with detector circuits to produce sequential signals wherein the presence of a particular component is denoted by absorption. Coding components may alternatively be distinguished by sharp infra-red absorption bands introduced by optically transparent organic plastic materials on an infra-red transparent substrate under infra-red illumination, the emanent radiation being received by a series of light pipes each containing specific narrow band filter corresponding to the absorption band of a particular component and a radiation detector. Thermocouples or thermosistors followed by amplifiers may also be used. In Fig. 1 a gamma-ray source 7 has the same number of nuclei and environments as the components of coded ink used; e.g. Fe 57 in stainless steel; garnet; dicyclo pentadyenyl iron; FeSn 2 , FeTi 2 O 5 , and ferrous oxalate, so that the emergent beam impinges on a coded symbol 8, the gamma frequencies not corresponding to a nucleus present in the symbol passing unchanged while the radiation at corresponding frequencies is scattered and detected by six gamma-ray detectors, e.g. 1 and 4, each provided with a filter, e.g. 11, 14, containing all the nuclei except that to which they are intended to respond. The resultant electrical outputs are read-out by conventional electronics to reproduce symbols corresponding to the presence and absence of particular components. The output of an unfiltered detector may electronically be analysed for pulse height responses. In Fig. 2 utilizing Mossbauer effect a movable gamma-ray source 9 is cyclically moved through different discrete velocities by a source driver 10 according to a predetermined cycle (Fig. 3, not shown), to produce different frequencies of radiation which traverse a coded element 8 to a detector 20 whose output energizes a multichannel analyser 21 synchronized with source driver 10 to switch in channel 1 during radiation corresponding to velocity V 1 , and so on in sequence. The resultant effect (Fig. 4, not shown) corresponding to a symbol containing all six components contains a sharp minimum signal for each of velocities V 1 to V 6 respectively on six channels of the analyser. Absence of a particular component causes maximum signals to appear on corresponding channels, and the analyser output is conventionally translatable into code signals. The moving source is, e.g. Fe57, in stainless steel, and the coding components may be six different iron compounds each having different resonant frequencies for Fe57; the resonance frequencies corresponding to that produced by the six source velocities. In Fig. 5 a conventional IR lamp 61 illuminates a substrate 62 of, e.g., polythene transparent to infra-red, on which symbols A, B, C, D are printed with distinctive components and the emanent radiation is lens focused on four light pipes transmitting to sharp cutting filters 5A, 5B, 5C, 5D passing only the wave-range corresponding to the absorption band of a specific component and thence to radiation detectors 6A, 6B, 6C, 6D, which may be, e.g. photo-multiplier tubes, to produce radiation signals if its particular component is absent, and no signal if it is present; the signals being read out by conventional circuitry 67, e.g. a multi-channel analyser, or a timed oscillascope. Solid state infra-red detector transistors may be used arranged in a mosaic receiving the infra-red image.