| 摘要 |
In an automatic analyzer using a plurality of probes detecting liquid levels based on a capacitance detection method, erroneous detection of liquid levels due to interference caused by the frequency difference of oscillators are reduced, so that an automatic analyzer with high accuracy at a high speed can be realized. Although frequencies f1 and f2 of detector oscillators 307 and 201 are originally equal to each other, if they are different by approximately several Hz from each other due to a manufacturing variation, oscillation waveforms are added to liquid level detection voltages, and it may be determined that the probes have contacted the liquid surfaces at inappropriate times before appropriate times when the probes have contacted the liquid surfaces. The present invention intentionally makes the difference between the frequencies f1 and f2 of the detector oscillators 307 and 201 be several kHz. In this case, as well as an actual change in capacitance due to the contact with the liquid surfaces, an oscillation waveform corresponding to the difference between the frequencies f1 and f2 is added to detection voltages, but amplitude values of high-frequency components can be attenuated by high-frequency attenuators 208, thereby suppressing a reduction in the liquid level detection accuracy due to simultaneous use of the plurality of probes. |
