Semi-automatic electro-mechanical pipette with controlled tip remover

• US 4,399,712 A
• Filed: 03/30/1981
• Issued: 08/23/1983
• Est. Priority Date: 02/09/1981
• Status: Expired due to Term

• Current Assignee: Nichiryo Co., Ltd.
• Original Assignee: Nichiryo Co., Ltd.
• Inventors: Oshikubo, Yuji, Tanabe, Sadakazu
• Primary Examiner(s): Kazenske, E. R.
• Assistant Examiner(s): NOLAND, THOMAS
• Application Number:
  US06/249,094
• Time in Patent Office: 876 Days
• Field of Search: 73/864.16, 73/864.13, 73/864.01, 128/218 A, 128/DIG. 1, 128/236, 128/214 F, 128/655, 422/100, 604/155, 604/154, 604/152, 604/67
• US Class Current: 73/864.16
• CPC Class Codes: B01L 3/0206 of the plunger pump type
• CPC Class Codes: B01L 3/0227 Details of motor drive means B01L3/0231, B01L3/0234 take precedence
• CPC Class Codes: G01F 11/021 of the piston type G01F11/04 takes precedence
• CPC Class Codes: G01F 11/029 provided with electric controlling means G01F11/022 and G01F11/024 take precedence

Abstract

A pipette device adapted to removably mount a tip at its lower end and having a housing in which there are provided a cylinder chamber communicating with the interior of the mounted tip, a plunger adapted to operate in the cylinder chamber for sucking a liquid and then discharging the same, a direct current motor coupled to the plunger through a plunger driving mechanism, and a potentiometer for producing a voltage signal representing the position of the plunger, so that sucking and discharging of the liquid can be effected by detecting the voltage signal produced by the potentiometer and controlling the direction and amount of the rotation of the motor by the utilization of such detected voltage signal. Also disclosed is a control device for use with the pipette device including a servo system for receiving the voltage signal produced by the potentiometer as a feedback signal and a sequence circuit adapted to change the balance-point of the servo system in a preselected sequence.

Claims

1. A pipette device capable of automatically sucking and discharging liquid and also capable of automatically removing a tip comprising:

housing means, a tip frictionally fitted on a lower end of said housing means, a cylinder chamber defined in said housing means and communicating with an interior of said tip, plunging means slidably received in the cylinder chamber, a potentiometer for producing a signal representing the position of said plunger means with respect to said cylinder chamber, plunger driving means including an electric motor and operably coupled with said plunger means for moving the same between at least three predetermined positions in accordance with said signal, said predetermined positions including a terminal sucking position, a terminal discharging position and a tip removing position, and a tip removing mechanism including a lower cylindrical member slidably mounted on the lower end of said housing means with a lower end of said cylindrical member being normally located against an upper end of said tip which is mounted on the lower end of said housing means and at least two rod members extending vertically in said housing means and being slidable relative thereto with said rod members having lower ends engaging with an upper end of said cylindrical member, and upper ends of said rod members being actuated by said plunger driving means when said plunger means moves from said terminal discharging position to said tip removing position, whereby the mounted tip is pressed downward by said lower cylindrical member and is removed from the pipette device.

2. A pipette device according to claim 1, further comprising a spring biasing the lower cylindrical member upwards with respect to the housing means.

3. A pipette device according to claim 2, wherein said lower cylindrical member has a radial flange in an upper end thereof, said housing means includes a cap encircling an upper end portion thereof, and said spring acts between a bottom wall of a cup-like member extending upwardly from below an intermediate portion of said lower end of said housing means and the radial flange of the lower cylindrical member.

4. A pipette device capable of automatically sucking and discharging liquid and also capable of automatically removing a tip comprising:

plunger means slidably received in a cylinder chamber communicating with an interior of said tip fitted on said pipette device;

a potentiometer for producing a variable signal representing the position of said plunger means with respect to said cylinder chamber;

plunger driving means including an electric motor and operably coupled with said plunger means for moving the same between at least three predetermined positions in accordance with said variable signal, said predetermined positions including a terminal sucking position, a terminal discharging position and a tip removing position; and

control means including;

a servo system receiving said variable signal from said potentiometer and supplying an output drive signal to said motor, said servo system being operative to reach a designated one of several balance-points corresponding respectively to said predetermined positions, a balance-power detecting means connected to said servo system for generating a balance-point detection signal whenever said servo system has reached one of said balance-points, and a sequence circuit responsive to said balance-point detection signal or to actuation of a start switch for supplying to said servo system an output signal designating the next one of said balance-points in a predetermined sequence.

5. A pipette device according to claim 4, wherein said sequence circuit is responsive to the first actuation of said start switch for producing a first output signal designating a first one of said balance-points corresponding to said terminal sucking position, to the second actuation of said start switch for producing a second output signal designating a second one of said balance-points corresponding to said terminal discharge position, and to the third actuation of said start switch for producing a third output signal designating a third one of said balance-points corresponding to said third tip removing position.

6. A pipette device according to claim 4, wherein said sequence circuit includes;

a counter unit adapted to be incremented by said balance-point detection signal or upon the actuation of said start switch for generating a stepping signal, and

a logic circuit connected to the output of said counter unit and responsive to said stepping signal for generating a set of logic signals as said designation output signal.