Method and device for analysis with color identification test paper
First Claim
1. A method for analyzing concentration of substance under analysis in an electronic analytical instrument having a light source, which method determines the concentration by measuring, at at least one wavelength of interest, light reflected from a test piece of paper bearing the substance and light reflected from a standard having a known reflectivity, and by forming a ratio of these measurements, which ratio is corrected for light source intensity variations and for inner stray rays, said ratio being termed the relative reflectivity of the test piece, said method comprising the steps of:
- determining a constant of the instrument useful in correcting the instrument for the effects of light source intensity variations and inner stray rays;
storing said constant electronically;
using the stored constant to determine a value proportional to the detected inner stray rays; and
using said value to determine the relative reflectivity of the test piece.
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Abstract
A method and apparatus are disclosed for an analyzer which measures concentration of a liquid specimen by monitoring the coloration of test paper which is either dipped into the specimen or is otherwise painted with it. In the method, inner stray rays produced by a light source which do not reach the test paper are experimentally monitored, so that the effect of such inner stray rays upon the accuracy of the test paper analysis is eliminated. Additionally, a method of relating relative reflectivity of the test paper to the concentration of the specimen is disclosed, in which method the calibration curve is modeled as a section of a hyperbola. In the apparatus, a microcomputer performs the evaluation and the detection of the coloration of the test paper and the compensation for various sources of instrumental error takes place electronically.
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Citations
16 Claims
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1. A method for analyzing concentration of substance under analysis in an electronic analytical instrument having a light source, which method determines the concentration by measuring, at at least one wavelength of interest, light reflected from a test piece of paper bearing the substance and light reflected from a standard having a known reflectivity, and by forming a ratio of these measurements, which ratio is corrected for light source intensity variations and for inner stray rays, said ratio being termed the relative reflectivity of the test piece, said method comprising the steps of:
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determining a constant of the instrument useful in correcting the instrument for the effects of light source intensity variations and inner stray rays; storing said constant electronically; using the stored constant to determine a value proportional to the detected inner stray rays; and using said value to determine the relative reflectivity of the test piece. - View Dependent Claims (2, 3, 4, 5)
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6. An electronic apparatus for analyzing concentration of a substance under analysis and which measures the concentration by measuring light reflected from a test piece of paper bearing the substance and light reflected from a standard having a known reflectivity by forming a ratio which is corrected for light source intensity variations and inner stray rays, said ratio being termed the relative reflectivity of the test piece, said apparatus comprising:
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optical means for irradiating an object with light of a predetermined wavelength; a second means for producing a constant signal which corresponds to a constant of the instrument useful in determining inner stray rays present during irradiation of the object; means for electronically storing the constant signal; means for detecting light reflected from the object during irradiation and for producing a first signal and a second signal which correspond, respectively, to light reflected off the test piece and light reflected off the standard; means for deriving from the stored constant signal a correction signal representing inner stray rays present during irradiation of the object; and a fourth means for determining the relative reflectivity of the test piece in response to the correction signal, the first signal and the second signal, in a manner such that the relative reflectivity of the test piece is corrected for effects of light source intensity variations and inner stray rays. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification