초록 ▼

A quantitative dispenser for a liquid includes a pipette having a downwardly directed nozzle which serves to pick up and deliver a predetermined quantity of a liquid and a mechanism for moving the pipette downwardly to dip the lower end of the pipette into the liquid supply. A detector is provided f

A quantitative dispenser for a liquid includes a pipette having a downwardly directed nozzle which serves to pick up and deliver a predetermined quantity of a liquid and a mechanism for moving the pipette downwardly to dip the lower end of the pipette into the liquid supply. A detector is provided for detecting reflection of light which is projected downwardly to the surface of the liquid while the pipette is moved downwardly to approach the surface. A control circuit is connected to the detector to determine the stop point for the downwardly moving pipette with the aid of information received from the detector. The detector is provided with a spot type reflection sensor having a light convergent optical element having a focal point at a certain distance below the detector whereby the stop point of the downwardly moving pipette is determined so as to correspond to a point of maximum intensity of the incoming reflected light.

대표청구항 ▼

A quantitative dispenser for a liquid, comprising; pipette means having a downwardly directed nozzle adapted to pick up and deliver a predetermined quantity of a liquid, drive means for moving said pipette means downwardly to immerse the lower end of said nozzle in a liquid supply, and liquid supply

A quantitative dispenser for a liquid, comprising; pipette means having a downwardly directed nozzle adapted to pick up and deliver a predetermined quantity of a liquid, drive means for moving said pipette means downwardly to immerse the lower end of said nozzle in a liquid supply, and liquid supply level sensing means for determining the stopping point for the downward movement of said pipette means, said liquid supply level sensing means being comprised of housing means, lens means mounted in said housing means and having a focal point outside of said housing means, light source means mounted in said housing means for directing a beam of light through said lens means onto the surface of said liquid supply, photosensor means mounted in said housing means for receiving light reflected from said surface of said liquid supply through said lens means, and control means operatively connected to said photosensor means and said drive means for controlling the operation of said drive means so as to stop the downward movement of said pipette means when the maximum intensity of reflected light is detected by said photosensor means, wherein said lens means comprises two convex lens portions so that said beam of light from said light source means is directed through a first one of said two convex lens portions and said light reflected from said surface passes through a second one of said two convex lens portions which has a focal point on said photosensor means whereby the maximum intensity of reflected light occurs when the surface coincides with the focal point of the first lens portion.