Ultrasonic sensor and pipetting apparatus using same

An ultrasonic sensor for measuring a distance to an object by transmitting waves to the object, receiving waves returning upon reflection at the object and measuring time from emission of the transmitted waves to receiving of the waves to determine the distance based on a resulting time measurement, the ultrasonic sensor comprising:

• detecting means for detecting a plurality of peaks appearing in each of waveforms of the transmitted waves and the received waves and for detecting a waveform reference point as a vertex of a phantom envelope connecting peak points of each waveform, the vertex being a point where a time-base coordinate is a minimum on the phantom envelop,
• first calculating means for calculating elapsed time from the waveform reference point of the transmitted waves to the waveform reference point of the received waves, and
• second calculating means for calculating the distance to the object based on a time value calculated by the first calculating means.

A pipetting apparatus having a pipette head attached to an output portion of a head drive mechanism, a pipette directed downward and projecting from the pipette head for drawing in and discharging a liquid, and an ultrasonic sensor provided at one side of the pipette head and directed downward for measuring a distance to an object by transmitting waves to the object, receiving waves returning upon reflection at the object and measuring time from emission of the transmitted waves to receiving of the waves to determine the distance based on a resulting time measurement, the pipetting apparatus being characterized in that the ultrasonic sensor comprising:

• first detecting means for detecting time of rise of a first of the transmitted waves,
• second detecting means for detecting a plurality of peak points appearing in a waveform of the received waves and for detecting a waveform reference point as a vertex of a phantom envelope connecting the peak points, the vertex being a point where a time-base coordinate is a minimum on the phantom envelope, and
• calculating means for calculating the distance to the object based on the time of rise of the first of the transmitted waves detected by the first detecting means, the time of the waveform reference point of the received waves detected by the second detecting means and a predetermined period of offset time.

A pipetting apparatus having a pipette head attached to an output portion of a head drive mechanism, a pipette directed downward and projecting from the pipette head for drawing in and discharging a liquid, and an ultrasonic sensor provided at one side of the pipette head and directed downward for measuring a distance to an object by transmitting waves to the object, receiving waves returning upon reflection at the object and measuring time, from emission of the transmitted waves to receiving of the received waves to determine the distance based on a resulting time measurement, the pipetting apparatus being characterized in that the ultrasonic sensor comprising:

• detecting means for detecting a plurality of peaks appearing in each of waveforms of the transmitted waves and the received waves and for detecting a waveform reference point as a vertex of a phantom envelope connecting the peak points of each waveform, the vertex being a point where a time-base coordinate is a minimum on the phantom envelope,
• first calculating means for calculating elapsed time from the waveform reference point of the transmitted waves to the waveform reference point of the received waves, and
• second calculating means for calculating the distance to the object based on a time value calculated by the first calculating means.