Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
1999-03-08
2001-07-03
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C422S091000, C436S179000, C436S180000, C073S864010, C073S864130, C073S864160, C073S864180
Reexamination Certificate
active
06254832
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to pipettes and more particularly to a battery powered microprocessor controlled hand portable electronic pipette which is light in weight and easily operated by a user over extended periods of time.
BACKGROUND
Since the first commercial introduction of a battery powered microprocessor controlled hand-holdable and easily transportable electronic pipettes by the Rainin Instrument Co., Inc., assignee of the present invention, it has been and continues to be the desire of all electronic pipette manufacturers to provide electronic pipettes which have the functional feel and operational capabilities of manual pipettes such as the world famous PIPETMAN pipette sold exclusively in the United States by the Rainin Instrument Co. for more than 25 years. Specifically in this regard, it continues to be the goal of all electronic pipette manufacturers to develop and produce electronic pipettes that are light in weight, easily holdable and transportable by a user and operational in several modes of operation over extended periods of time without creating physical stress and strain of the hands and forearms of the pipette user. The EDP electronic pipette of the Rainin Instrument Co. introduced in 1984 and its successor models addressed each of the foregoing design criteria. Following Rainin, other companies developing and manufacturing electronic pipettes have also addressed the same criteria and over the years electronic pipettes have become somewhat lighter in weight and more user friendly. However, the desire for an electronic pipette which closely approximates in feel and operational features those of the manual pipette have never been completely achieved. Accordingly, there continues to be a need for such an electronic pipette which is satisfied by the present invention.
SUMMARY OF THE INVENTION
Basically, the present invention satisfies the foregoing needs by providing an electronic pipette which is light in weight, comfortably holdable in either the right or left hand of a user and which is easily operated by the user to direct microprocessor controlled operation of the pipette through different user selected modes of operation for different user selected sample volume and speeds of operation. In providing such a user friendly electronic pipette, the present invention comprises a bilaterally symmetrical design described in detail in the concurrently filed U.S. patent application Ser. No. 09.263,131 which is incorporated herein by this reference. Basically, the design includes an axially elongated hollow housing having a vertically extending longitudinal axis and vertically extending and substantially coaxial upper and lower portions. The upper portion of the housing includes a forward compartment containing a forwardly facing alpha-numeric display adjacent a top of the housing. Thus located, the display is readily viewable by a user during all modes of operation of the pipette be the user right handed or left handed. In addition to the display, the forward compartment contains a plurality of columns of forwardly facing control keys as well as a plurality of forwardly facing trigger switches below the columns of control keys. The display, columns of control keys and trigger switches are bilaterally symmetrical relative to the longitudinal axis of the housing. In addition, the upper portion of the housing includes a rear compartment which contains a replaceable rechargeable battery for powering a microprocessor and linear actuator contained within the housing. The lower portion of the housing comprises a vertically elongated handle which is coaxial with the longitudinal axis of the housing. The handle has contiguous bilaterally symmetrical and vertically extending forward and rear portions for either right or left hand gripping by a user of the pipette. The forward portion of the handle extends forward of the upper portion of the housing and extends vertically downward to a lower end of the housing and in one embodiment internally contains and shields an upper portion of a pipette tip ejector. In the preferred embodiment of the design, the pipette tip ejector has a thumb actuated push button located at a top of the forward portion of the handle and a vertically moveable tip ejector arm extending below the housing and vertically along a pipette tip mounting shaft to encircle the shaft adjacent a lower end thereof. Thus configured, the pipette tip ejector is designed to eject a pipette tip from a lower end of the mounting shaft upon downward movement of the tip ejector arm. Such downward movement is in response to a downward thumb force exerted by the pipette user on the push button while the user is gripping the handle of the pipette. The rear portion of the handle extends rearward from the forward portion and has a hook extending rearward from a back of an upper end of the handle. The hook includes a downwardly curved lower surface for engaging an upper side of an index finger (or middle finger, if desired) of the user while the user is gripping the handle with the thumb of the user free to actuate any of the bilaterally symmetrical control keys, trigger switches and push button in any sequence desired. All this the user is free to do while clearly viewing the alpha numeric display as it responds to the actuation of the control keys and trigger switches. In this regard, the hook, forward and rear portion of the handle and pipette tip ejector including push button and ejector arm are all bilaterally symmetrical relative to the longitudinal axis of the housing. Thus arranged, the pipette of the present invention is easily and comfortably gripped by the user in either his or her left or right hand with the user's index finger under the hook at the rear of the handle. This leaves the user's thumb free to actuate as desired any of the control keys or trigger switches which regulate the various modes of operation of the electronic pipette as well as the volumes of liquid aspirated and dispensed thereby during the several modes of operation of the pipette. All this is accomplished comfortably by the user while exerting minimal thumb forces on the control keys, trigger switches and push button. Thus, the electronic pipette of the present invention is useable by the user over extended periods of time without unduly stressing the user's thumb, hand or forearm enabling accurate and repeatable operation of the pipette in all operational modes of pipette under control of the user.
The electronic pipette of the present invention also preferably incorporates a relatively simple electronic control circuit which enables the software controlled microprocessor to function as a microcontroller generating pulse width modulated (PWM) drive signals for the windings of a stepper motor included in the linear actuator. The PWM signals are generated in synchronism with clock pulses defining the stepping rate of the motor. This allows the PWM signals to be generated by the microcontroller without the control circuit requiring the use of conventional current sensing or feedback circuitry.
The electronic control circuit also minimizes the power requirements of the stepper motor thereby reducing power drain on the battery which powers the pipette. This, in turn, extends the operating life of the pipette between required recharging of the battery.
The electronic control circuit also compliments the user friendly control of the pipette enabling the user to easily switch between the various operating modes of the pipette and in each mode to select between a variety of operating speeds and operating features including cycle counting. When the cycle counting feature is selected by the pipette user, the user is continuously advised of the operational cycle of the pipette. This enables the user to interrupt a sequence of pipette operations without losing tract of the particular cycle of operation of the pipette.
Further, the electronic control circuit of the pipette of the present invention provides for a sequential recharging of a number of pipettes from
Homberg William D.
Kelly Christopher
Magnujssen, Jr. Haakon T.
Rainin Kenneth
Bex Kathryn
Meads Robert R.
Rainin Instrument Co. Inc.
Warden Jill
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