Indicator circuit for a concentration measuring apparatus

An indicator circuit in an apparatus for measuring the concentration of a selected component in a test sample, which apparatus includes means for generating a test voltage that represents the concentration of the component in the test sample, said circuit comprising:

• means for generating a series of range voltages, each of which represents a respective one of a continuous series of potential concentration ranges of said component in said test sample;
• incremental voltage divider means;
• switching means for selecting an adjacent pair of said range voltages, one of which is below and the other of which is at least as great as said test voltage, and applying said selected range voltages across said incremental voltage divider means such that the voltage difference of said selected range voltages is divided into a series of incremental voltages, each of which represents a respective one of a series of potential incremental concentration levels of said component within each said concentration range;
• incremental computation means for comparing said test voltage with each of said incremental concentration voltages and determining the actual incremental concentration level of said component in said test sample;
• and
• a group of incremental indicator elements, each of which represents a respective incremental concentration level in each of said concentration ranges, said incremental indicator elements being responsive to said incremental computation means for indicating the determined incremental concentration level of said component in said test sample.

A photometer for measuring the concentration of a selected component in a sample medium comprising:

• a selectively actuatable light source;
• means for alternately holding in the optical path of said light source a reference sample that represents a known concentration of said component in said medium and a test sample that represents the concentration to be measured;
• detector means for sensing the intensity of light transmitted through said reference sample and said test sample in a selected wavelength region and generating an output voltage representative of said sensed intensity;
• first means for actuating said light source to transmit light through said reference sample and means, responsive to said first means for actuating, for generating and storing a reference voltage that corresponds to said intensity sensed by said detector means when light is transmitted through said reference sample;
• second means for actuating said light source to transmit light through said test sample such that said output voltage comprises a test voltage;
• range voltage divider means for dividing said reference voltage into a plurality of range voltages, each of which is a function of said reference voltage and represents one of a continuous series of potential concentration ranges of said component in said test sample;
• range computation means for comparing said test voltage with each of said range voltages and determining the actual concentration range of said component in said test sample;
• range indicator means, responsive to said range computation means, for indicating the determined concentration range of said component;
• incremental voltage divider means;
• switching means for selecting an adjacent pair of said range voltages, one of which is below and the other of which is at least as great as said test voltage, and applying said selected range voltages across said second voltage divider such that the voltage difference of said selected range voltages is divided into a series of incremental voltages, each of which represents a respective one of a series of potential incremental concentration levels of said component within each said concentration range;
• incremental computation means for comparing said test voltage with each of said incremental concentration levels and determining the actual incremental concentration level of said constituent in said test sample;
• and
• a group of incremental indicator elements, each of which represents a respective incremental concentration level within each said concentration range, said incremental indicator elements being responsive to said incremental computation means for indicating the determined incremental concentration level of said component in said test sample.