Chemical analyzer with automatic calibration

Improved calibration apparatus for use in an automatic analyzer of the type which measures a characteristic of a plurality of samples and includes sample changer means adapted to advance said samples in sequential fashion into position for analysis, the sample changer means further adapted to intermittently position for analysis calibration standards having a known predetermined value of said characteristic, the improved calibration apparatus comprising:

• measuring means for measuring said characteristic of said calibration standards and generating electrical signals indicative thereof,
• conversion means responsive to each measurement of a calibration standard for generating a conversion factor which converts each electrical signal to said predetermined value of said calibration standards,
• storage means for storing said conversion factor,
• verification means for verifying the calibration of said analyzer upon each analysis of a calibration standard including means for comparing the conversion factor generated for the calibrated standard being measured with the stored conversion factor for the previously analyzed calibration standard and for generating a control signal if the compared conversion factors differ by more than a predetermined amount,
• sample changer control means responsive to said control signal for halting advancement of the sample changer means to maintain the calibration standard being measured in position for remeasurement, and
• means for energizing said measuring means to remeasure the calibration