| 摘要 |
PURPOSE:To prevent a malfunction by disposing a conductor in the vicinity of a sample liquid, applying an AC signal between a pipet and the conductor, and detecting variation in the impedance between them when the forward end of the pipet touches the surface of a sample liquid. CONSTITUTION:A pipet 1a is set above a sample case 5a. A pulse signal from a basic signal generating circuit is passed through a frequency multiplier to produce an AC signal which is then applied between the pipet 1a and a supporting base 11a. Consequently, the pipet 1a descends in the direction of arrow B and when the forward end of the pipet la touches the surface 10a of a sample liquid, the capacitance between the pipet 1a and the supporting base 11a increases thus decreasing the amplitude of AC signal. When the output signal exceeds a predetermined level, the forward end of the pipet 1a descends into a sample liquid 6a by a predetermined distance based on the output signal from a comparison circuit. When a syringe 8a is driven to suck the sample liquid 6a, a driving section 4a elevates the pipet 1a and rotates a shaft 3a to transfer the pipet 1a above a case 7a for dispensation. |
