Patent ID: 8628720

Claim:
An automatic analyzer comprising: a photomultiplier tube as a detector; a high-voltage generator for generating an applied voltage for driving the photomultiplier tube; a control circuit for controlling output of the high-voltage generator; a logarithmic converter for converting the applied voltage to the photomultiplier tube and a measured value of the photomultiplier tube; an arithmetic unit for determining, from an execution result on the logarithmic conversion of the applied voltage and the measured value, a desired voltage for obtaining a desired sensitivity of the photomultiplier tube, wherein the arithmetic unit includes: a storage means for storing measured values under a plurality of applied voltages, with respect to a reagent for assessing sensitivity of the photomultiplier tube; a determination means for determining a value of a voltage to be applied to the photomultiplier tube, from relationships between the applied voltages and the measured values, the applied voltages and the measured values being each stored in the storage means; and a mechanism that feeds back the determined applied voltage to the control circuit; a calculator for calculating a rate of change of the measured value to each of the applied voltages as a gain; a comparison means for comparing threshold levels with the gain calculated by the calculator; and warning means for displaying a warning if the gain is determined to lie outside a range of the threshold levels by the comparing means.