MXPA00010801A - Improved battery powered microprocessor controlled hand portable electronic pipette - Google Patents

Abstract

A battery powered, microprocessor controlled portable electronic pipette (10), comprising a hand holdable housing supporting a battery (16), a linear actuator (40) for driving a plungner (90) lengthwise in a cylinder to aspirate and dispense fluid into and from a pipette tip (60) extending from the housing and a control circuit for the linear actuator. The linear actuator is powered by the battery and comprises a stepper motor (40) with current receiving windings for electromagnetically driving a rotor to impart the lengthwise movement to the plunger (90).

Description

PORTABLE ELECTRONIC HAND PIPE CONTROLLED BY AN IMPROVED BATTERY ENERGIZED MICROPROCESSOR Related Request This is a continuation in part of the US patent application filed on March 5, 1999, with Serial No. 09 / 263,132.

Field of the Invention The present invention relates to pipettes and more particularly to a portable hand-held electronic pipette controlled by a battery-powered microprocessor that is light in weight and easily operated by a user for long periods.

- Background From the first commercial introduction of electronic pipettes controlled by a microprocessor powered by a battery that are manual and easily transportable by Rainin Instrument Co. , Inc., which is the assignee of the present invention, has been and continues to be the desire of all electronic pipette manufacturers to provide electronic pipettes that have a functional sensation and the operational capabilities of manual pipettes such as the world famous one. PIPETMAN pipette sold exclusively in the United States by Rainin Instrument Co. for more than 25 years. Specifically in this regard, it remains the goal of all electronic pipette manufacturers to develop and produce electronic pipettes that are light in weight, easily clamped and transportable by the user and operating in various modes of operation for extended periods of time without creating physical effort and tension of the hands and forearms of the user of the pipette. The electronic pipette EDP from Rainin Instrument Co. introduced in 1984, and its successor models address each of the previous design criteria. Following Rainin, other companies that develop and manufacture electronic pipettes have only 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 approaching the sensation and operating characteristics of manual pipettes has never been fully achieved. Correspondingly, there continues to be a need for an electronic pipette that is satisfied by the present invention.

SUMMARY OF THE INVENTION Basically, the present invention meets the foregoing needs by providing an electronic pipette that is light in weight, that is held comfortably in both the right and left hand of a user and that is easily operated by the user to direct the operation controlled by the microprocessor of the pipette through the different operating modes selected by the user for a different volume of samples selected by the user and with different operating speeds. By providing the different operating modes selected by the user for different sample volume selected by the user and with different operating speeds. By providing this user-friendly electronic pipette, the present invention comprises a bilaterally symmetrical design described in detail in the co-pending US patent application Serial No. 09 / 263,131, which is incorporated herein by reference .

Basically, the design includes an axially elongated hollow box having a vertically extending longitudinal axis and substantially coaxial upper and lower portions that extend vertically. The upper portion of the box includes a front compartment containing an alphanumeric front facing screen adjacent to the top of the box. Located in this way, the screen is visible without problems by the user during all modes of operation of the pipette, regardless of whether the user is right-handed or left-handed. In addition to the screen, the front compartment contains a plurality of columns of control keys that are facing forward as well as a plurality of trip switches that are facing forward under the columns of the control keys. The screen, the columns of the control keys and the trip switches are bilaterally symmetrical with respect to the longitudinal axis of the box. Additionally, the upper portion ~ of the box includes a rear compartment containing a replaceable rechargeable battery for energizing a microprocessor and a linear actuator contained within the box. The lower portion of the box comprises a vertically elongated handle which is coaxial with the longitudinal axis of the box. The handle has contiguous front and rear portions that are bilaterally symmetrical and that extend vertically either to grip with the right hand or the left hand of the user of the pipette. The front portion of the handle extends forwardly of the upper portion of the box and extends vertically downward toward a lower end of the box and in one embodiment internally contains and shields an upper portion of an ejector from the tip of the box. pipette. In the preferred embodiment of the design, the pipette tip ejector has a thumb-operated push button located on the top of the front potion of the handle and a vertically movable tip ejector arm that extends below the box and vertically along the axis of the tip mount of the pipette to encircle, the axis adjacent to a lower end thereof. Configured in this manner, the tip ejector of the pipette is designed to eject a tip of the pipette from a lower end of the mount shaft before a downward movement of the tip ejector arm. This downward movement is in response to a downward thumb force exerted by the user of the pipette on the push button while the user holds the pipette handle. The rear portion of the handle extends rearwardly from the front portion and has a hook extending rearwardly from a rear end of an upper end of the handle. The hook includes a lower surface curved downward to engage the upper side of an index finger (or middle finger, if desired) of the user while the user holds the handle leaving the user's thumb free to operate any of the control keys symmetrically bilaterally, the trigger switches and the pressure button in any desired sequence. The user is free to do all this while clearly viewing the alphanumeric screen while responding to the activation of the control keys and trip switches. In this regard, the hook, the front portion and the rear portion of the handle and the ejector of the pipette tip including the push button and the ejector arm are all bilaterally symmetrical with respect to the longitudinal axis of the box. Arranged in this way, the pipette of the present invention is easily and conveniently held by the user either with his right hand or his left hand leaving the index finger under the hook at the back of the handle. This leaves the user's thumb free to operate as desired any of the control keys or trip switches that regulate the various modes of operation of the electronic pipette at the same time as the volumes of liquid aspirated and dispensed through it during various modes of operation of the pipette. All this is comfortably achieved by the user while exerting minimal thumb forces on the control keys, the trigger switches and the push button. In this way, the electronic pipette of the present invention is used by the user for prolonged periods of time without unduly straining the user's thumb, hand or forearm allowing precise and repeatable operation of the pipette in all modes of operation of the pipette. the pipette under user control. The electronic pipette of the present invention also incorporates preferably a simple electronic control circuit that allows the software controlled microprocessor to function as a microcontroller that generates pulsed pulse width modulated signals for the winding of a stepped motor included in the linear actuator. The PWM signals are generated in synchronization with the pulse clock by defining the stepped motor speed. This allows PWM signals to be generated by the microcontroller without the control circuit requiring the use of conventional current sensors or back-up circuits. The electronic control circuit also minimizes the power requirements of the stepped motor thus reducing the drain of energy in the battery that energizes the pipette. This, in return, prolongs the life of the pipette's operation between the required recharges of the battery. The electronic control circuit also complements the user friendly control of the pipette allowing the user to easily switch between the various modes of operation of the pipette and in each of the modes select from a variety of operating speeds and operating characteristics including the cycle count. When the cycle count feature is selected by the use of the pipette, the user is continuously notified of the pipette's operating cycle. This allows the user to interrupt a sequence of pipette operations without losing track of the particular cycle. of the operation of the pipette. In addition, the electronic control circuit of the pipette of the present invention provides a sequential recharge of a number of pipettes from a single source.

Brief Description of the Drawings Figure 1 is a perspective view of a preferred embodiment of the electronic pipette of the present invention. Figure 2 is a sectional sectional side view of the pipette of Figure 1 showing the internal construction of the pipette and the parts that make up the same. Figure 3 is comprised of Figures 3A-3E combined to illustrate the electronic circuit of the pipette of the present invention. Figure 4 is a time diagram of the PWM pulse signals applied to the gate of the field effect transistors ("FETs") that drive the coils of the stepped motor in the preferred form of the electronic pipette of the present invention. Figure 4a is a time diagram illustrating a one-pulse width modulation period of motor impulse signals to the two-H motor control gates in the impulse circuits for the motor. Figure 4b is comprised of Figures 4b-1 and 4b-2 which is a numerical table illustrating four different ranges for the pulse width modulation signals of the motor pulse as a function of the position of the motor micropass. Figure 5 is a table illustrating the pulses of the width modulation of the repetition pattern of the motor impulse signal of each of the microspasses for each of the 10 operating speeds of the pipette. Figure 6 is a graph illustrating engine speed as a time function of pipette ramps from zero to speed 10. Figure 7 comprises Figures 7a to 7b which is a table representing the numerical values of the pattern repetition of the pulse width modulation of the motor impulse micropass for the acceleration / velocity ramp from zero to the speed 10 which is plotted in Figure 6 and Figure 8. Figure 8 is a graph illustrating the acceleration of the motor as a function of time while the pipette rises from zero to speed 10. Figure 9 is a graph illustrating a typical response of the pipette before and after it is corrected through the application of the correction factors for the air pressure and the effects of the tension of the liquid surface and the similar one stored in the memory and the selected microprocessor in response to each of the different volume settings for the pipette. Figure 9 through 9F illustrate a table of 200 typical correction values described by the graph illustrated in Figure 9 for each of the volume settings in a pipette with a range of 100 microliters that is used in the graph illustrated in Figure 9. Figure 10 comprises Figures 10A and 10B comprising a software flow chart illustrating the manual mode of operation of the electronic pipette of the present invention. Figure 11 comprises Figures HA and 11B comprising a software flow diagram illustrating the mode of operation of the pipette of the present invention. Figure 12 is a software flow diagram illustrating the routine of the mode keys included in the operation of the pipette in the manual modes, pipette and multiple modes of operation of the pipette of the present invention. Figure 13 is a software flow diagram illustrating the reset key routine included in the operation of the manual sludge pipette, pipette and multiple modes of operation of the pipette of the present invention. Figure 14 is a software flow diagram illustrating the routine of arrow keys included in the operation of the pipette in the manual mode, pipette and multiple modes of operation of the present invention. Figure 15 is a software flow chart illustrating the mixed key routine included in the operation of the pipette in pipette operation mode of the pipette of the present invention. Figure 16 is comprised of Figures 16 a and 16 B comprising a software flow diagram illustrating the multiple mode of operation of the pipette of the present invention.

Figure 17 is a graph of the voltage, as a function of time, of a power source that is used to charge the battery that energizes the microprocessor and the stepped motor included in the electronic pipette of the present invention. Figure 18 is a graph of current, as a function of time, from the energy source used to charge a battery that energizes the microprocessor and stepped motor included in the electronic pipette of the present invention. Figure 19 is a table illustrating the time of service cycles of the pulse width modulation for the various load levels used to charge the battery energizing the microprocessor and the stepped motor included in the electronic pipette preferably of the present invention. Figure 20 is a graph illustrating charging speed, battery voltage of the open circuit, and charging capacity as a function of time for a battery that is charged through the preferred method of the pipette of the present invention .

Figure 21 is comprised of Figures 21a to 21c comprising a software flow diagram illustrating the portion of the battery charge of the energy management operation of the pipette of the present invention. Figure 22 is a block diagram showing two pipettes of the present invention connected to two power sources for sequential charging of the batteries there in accordance with the charging routine of the battery of the present invention.

Detailed Description of the Invention The pipette 10 illustrated in Figures 1 and 2 of the drawings comprises an electronic pipette controlled by a microprocessor energized by a hand-held battery of light weight symmetrically bilaterally. As illustrated, the pipette 10 includes an axially elongated hollow box 12 having a vertically extending longitudinal axis 14. The box includes an upper portion and a vertically extending and substantially coaxial lower portion 16 and 18. The upper portion 16 of the box includes a front compartment 20. The compartment 20 contains and supports an alphanumeric screen that faces the front 22 adjacent to the top of the box. The screen is a conventionally designed LCD screen. Additionally, the front compartment 20 contains and supports a plurality of columns (for example two) of the front facing control keys located below the screen and a plurality of trip switches that are forward facing one located immediately below each of the columns of control keys. In the illustrated embodiment of the present invention, the vertically spaced upper control key 26a and the lower control key 26b comprises a first column of control keys spaced to the right of the longitudinal axis 14 of the box 12. Similarly , the vertically spaced upper control key 28a and the lower control key 28b comprises a second column of control keys to the right of the longitudinal axis 14 at a distance substantially equal to that of the spacing of the control keys 26a, 26b, of the axis. A trigger switch 30 is also supported within the compartment 20 to the left of the shaft 14 below the column of the control keys 26a, 236b while a trip switch 32 is supported within the compartment 20 to the right of the shaft 14 under the the second column of the control keys 28a, 28b. In fact, in the illustrated embodiment, the right side of the trigger switch 30 and the left side of the trigger switch 32 lie substantially on a vertical plane that includes the longitudinal axis 14. On this aspect, it is an important feature of the present invention that the screen 22, the columns of the control keys 26a, 26b, and 28a, 28b and the trip switches 30 and 32 are bilaterally symmetrical with respect to the longitudinal axis 14 of the case 12 and as will be described hereinafter in the present in close proximity to the user's thumb pipette while the user holds the pipette 10 in his right hand or in his left hand and observes the screen 22. In addition to the front compartment , the upper portion 16 of the case 12 includes a rear compartment 34. As illustrated, the rear compartment 34 contains and supports a replaceable battery 36 for energizing a microprocessor 38 and a stepped motor 40 included in a linear actuator 41 supported within the box 12. The lower portion 18 of the box 12, on the other hand, comprises a vertically elongated handle 42 coaxial with the longitudinal axis 14 of the box. The handle 42 comprises contiguously a bilaterally extending and vertically extending front portion and rear portion 44 and 46 for hand holding by a user of the pipette 10. As illustrated, the front portion 44 of the handle 12 extends forward of the upper portion 16 of the box 12. It also extends vertically downwards toward a lower end 48 of the box 12 to internally contain and shield an upper portion of a tip ejector from the pipette 50 having a pressure button operated by the thumb 52 located in an upper portion 54 of the front portion. Additionally, the tip ejector of the pipette 50 includes a vertically movable tip ejector arm 56 that extends below the case 12 and vertically along the mount axis of the pipette 58 to encircle an axis adjacent a bottom end. 59. The ejector of the tip of the pipette 50 may be of conventional design as that which is included in the well-known PIPETMAN pipette or may have the form illustrated and described in U.S. Patent 5,614,153 issued on 25 March 1997, assigned to the assignee of the present invention and incorporated herein by this reference. As fully described in the patent and well known, with respect to the PIPETMAN pipette, this is a function of the tip ejector of the pipette 50 to eject a tip of the pipette, such as tip 60, from the saddle shaft 58 , in response to a downward thumb force exerted by the user on the push button 52. As illustrated, the rear portion 46 of the handle 42 extends rearwardly from the front portion 44 and includes a hook 62 extending toward back from the rear 64 of an upper end 66 of the handle. The hook preferably has a bottom curved bottom surface 68 for engaging an upper side of the index finger or the middle finger of the user of the pipette while the user holds the handle both in his right hand and in his left hand. This leaves the user's thumb free to operate any of the bilaterally spaced and closely spaced control keys (26a, 26b; 28a, 28b), the trip switches (30, 32) and the push button (52) in any sequence desired while closely watching the alphanumeric display 22 while responding to activation of the control keys and trip switches. In this respect, the hook 62, the front portion and the rear portion of the handle 42 and the ejector of the pipette point 50 includes the pressure button 52 and the ejector arm 54 are all symmetrically bilateral with respect to the longitudinal axis 14 of the box. Furthermore, it can be noted that the uppermost portion 70 of the lower surface of the hook 62 lies in the same horizontal plane as the upper part 72 of the pressing button 52. This further improves the positioning of the user's hand by holding the handle 42 so that the freedom of movement of the user's thumb can be obtained to operate various closely spaced control keys and trigger switches as well as the push button when it is desired to eject a tip of the pipette from the mount shaft of the pipette. In this regard, the control key 26a within the left-hand column preferably comprises a pipette mode of the operation control key while the control key 26b in the same column is designed to reset or modify the operation of the pipette of all forms described in the present below. further, as illustrated, in the right-hand column of the control keys, the control keys 28a and 28b control the numerical value displayed by the display 22 as also described in detail hereinafter. For example, actuation of the control key 28a may increase the volume adjustment or the operation speed setting for the pipette 10 as indicated on the display 22. On the other hand, the operation of the control key 28b may decrease the volume adjustment or the operation speed setting for the pipette 10 as indicated on the screen 22. Finally, as will be described hereinafter, in a "manual mode" of operation of the pipette, one of the first trigger switches pressed by the user 30, 32 may comprise a suction drive or a lift trigger switch while the other of the trip switches may comprise the drive trigger switch of the dispenser. In all other modes of operation of the pipette, the actuation of any of the trip switches 30 0 32 can trigger the next programmed step in the selected operating mode of the pipette user. More particularly, in the preferred embodiment of the pipette of the present invention, the internal structure of the pipette provides a pipette having a center of gravity inside the handle 42. This provides a balanced pipette that is neither heavy in the top or bottom and is free of unwanted slips when the user releases his grip on the handle and depends on the hook 42 for the support of the pipette. This balanced structure is represented more closely in Figure 2 which illustrates in a sectional section the internal structure of the electronic pipette. In this regard, it should be noted that the screen 22 is secured through conventional elements such as a detent plate directly behind and inside the upper window 74 in a bevel 76 comprising a front face of the upper portion 16 of the case of the pipette 12. The screen is electrically connected to a printed circuit board 78 mounted vertically within the upper portion of the case 12 to define the front compartment 20 to contain the display 22, the control keys (26a, 26b); 28a, 28b) and the trip switches 30 and 32 as illustrated. The control keys (26a, 26b; 28a, 28b) are of conventional design and each is supported by a horizontal tube 80 within an opening in a window 84 in the bevel 76 directly below the upper window 74 that contains the screen 22. The tubes 80 'move axially so that the thumb of the user under pressure on the exposed front end of a tube will move a trailing end of the tube and a conductive element driven therefrom against the printed circuit board 78 to drive the microprocessor 38 housed in the printed circuit board 78 to (i) change or reset the operation mode of the pipette or (ii) change the volumes of liquid to be handled and / p the operating speed of the pipette according to the modes selected by the user and (ii) change the corresponding alphanumeric screens on the screen 22. in particular, the volumetric settings and the suction speed and the indications of the Dispenser exhibited by the screen 22 is controlled by the keys 28a and 28b and reflected in the modifications of the operation of the pipette in the various modes selected by the operation of the control key 26a, the control key 26b is a key of "reset". The trip switches 30, 32 on the other hand are located in the circuit with the microprocessor and as described in the concurrently filed patent application, are soiled or otherwise connected to the bezel 76 so that a thumb drive of one of the switches will operate the pipette operation, such as aspiration, while the thumb drive of the other trip switches 30, 32 will trigger a different operation of the pipette such as dispensing a liquid through the pipette. Also, as illustrated, the battery 36 contained in the rear compartment 34 between the printed circuit board 78 and a removable door 85 included in the upper portion 16 of the box. The battery 36 energizes the microprocessor 38 and the motor by electrical connections through an energy splice connected to the printed circuit board 78. The motor 40 is located on the handle 42 of the pipette 10 below the printed circuit board 78 and it is secured vertically by a support rib 86 on a spinal support 88 inside the box. The motor 40 may be of conventional design and preferably be a stepped motor energized by the battery 36 and controlled by the microprocessor 38 in a manner described in detail later herein. As illustrated, an output shaft 89 extends vertically from the stepped motor 40 and is connected in a conventional manner to a piston 90 so that the rotation of a rotor within the motor produces an axial movement of the output shaft 89 and corresponding to the axial movement of the piston 90 within the mounting axis of the tip of the pipette 56. The mounting axis of the tip of the pipette 58, in turn, is secured by a threaded nut 91 to a threaded collar 92 which extends axially from the lower end of the handle 42. The piston 90 passes through a piston seal 93 which is secured in place around the piston by a spring loaded seal retainer 94 (the spring is removed for clarity of the illustration ). The return spring on the ejector of the tip of the pipette 50 shown in Figure 2 is also removed for clarity from the illustration. The return spring extends around a rod 96 between the push button 52 and the ejector arm. 54 secured at the opposite ends of the rod. The downward movement of the pressure knob 52 is opposed by the return spring and at the moment of release of the pressure knob, the return spring returns the pressure knob and the rod 96 to its highest position. In the operation of the pipette 10, the axial movement of the output shaft 89 of the motor 40 causes a controlled axial movement of the piston 90 in the mounting axis of the tip of the pipette 56 to withdraw or dispense the liquid within or from the tip of the pipette 60 secured to a lower end of the shaft. In all operations of the pipette 10, the user of the pipette holds the handle 42 in his right hand or his left hand with his index finger or middle finger under the hook 62. This leaves the user's thumb free to operate the button 52, the trigger switches 30, 32 and / or the control keys 26 a, 26 b or 28 a, 28 b in any desired sequence while clearly observing the screen 22. The trigger switches and the control keys that they are bilaterally symmetrical with respect to the longitudinal axis 14 of the pipette are more easily driven by the thumb of the user without exerting forces that lead to an effort or tension of the thumb, hand or forearm of the user. This allows the electronic pipette of the present invention to be operated in laboratories by technicians for long periods without resulting in fatigue or undesired stress in the thumb or hand of the user. As illustrated in Figures 3A, 3B, 3C, 3D, and 3E, which combine to form Figure 3, the electronic control circuit for the pipette of the present invention is generally described by the number 100 and basically comprises the microprocessor 38 (Figure 3D) with the internal circuits 102 and the external support circuits including the power supply of the wall (external power source), the circuits 104 (Figure 3A), the recharging and power management circuits of the battery 106 (Figures 3A, 3B and 3D) external reset circuits 108 (Figure 3C), EEPROM memory circuit 110 (Figure 3B), reference voltage circuit 112 (Figure 3B), external analog-to-digital converter circuits (A to D) 114 (Figures 3A, 3B and 3D), the LCD screen 22 (Figure 3D), polarization circuit 116 (Figure 3D) and motor impulse circuit 118 (Figures 3C and 3E). As previously indicated, the control circuit 11D derives energy from the battery 36 or an external power source 37 (Figure 22) to energize the microprocessor 38 which in turn controls the operation of the display 22 and the stepped motor 40 included in the linear actuator 41. This control is in response to the actuation by the user of the control key 26a, 26b; 28a, 28b (indicated in Figure 3A as "Switches of Function SW1, SW2, SW3, and SW4 respectively) and trip switches 30 and 32 (indicated as SW5 and SW6 respectively in Figure 3B), function switches and trip switches define a keyboard 120 for pipette 10 as it will be described subsequently. This control of the microprocessor of the screen 22 and the stepped motor 40 is also based on the data tables programmed and stored in the memory inside the microprocessor 38 as are the data described in Figures 4b-1, 4b-2, 5, 6 , 7a-7f, 8, and 19 and / or the data tables programmed and stored in the circuits of the EEPROM memory 116 described in Figure 3D as are the data described in Figures 9 and 9a-9f. The operation of the microprocessor 38 in various modes of operation of the pipette are also programmed through the routines and software subroutines described in Figures 10A-16B and 21a-c. In this respect, the stepped motor 40 includes the windings receiving Coroxent A and B described in Figures 3C and 3E respectively to receive the pulse signals from the microprocessor 38 and the motor pulse circuits 118 to electromagnetically drive an engine rotor. to impart the length movements previously described to a plunger comprising the piston 90 in the cylinder 92 (Figure 2) to aspirate or dispense fluid into and from the tip of the pipette 60 (Figure 1). Further in this respect, as will be described in greater detail with respect to Figures 4, 4a, 4b-1, 4b-2, 5-7f and 17-21c, under control of the software programs within the microprocessor 38, the movement longitudinal of plunger 28 is at speeds controlled by the user through a series of micropasses. Specifically, the microprocessor 38 is programmed to generate the stepped motor pulse signals which are pulse width modulated (PWM) signals having service cycles corresponding to different micro-step positions for the stepped motor derived by the microprocessor from a first table of data stored in the internal memory included in the microprocessor and having a repetition pattern derived through a microprocessor from a second data table stored in the memory to determine the speed of the motor movement. In this respect, the microprocessor 38 is furthermore programmed so that the PWM pulse signals have non-overlapping phases where there is overlap of the PWM pulse signal applied to the windings receiving current A and B of the stepped motor 40.

Microprocessor By way of example only, the microprocessor 38 may comprise a microcontroller or a single-chip microprocessor, such as the 4-bit microprocessor μPD753036 with a single chip manufactured by NEC. Electronics Inc., Santa Clara CA designated as Ul in Figure 3D. The processor can operate from voltages as low as 1.8 V and as high as 5.5 V and can be characterized by a ROM or an internal PROM of 16,384 by 8 bits, an internal RAM of 768 by 4 bits, a standby current of less of 100 μA and an operative current of 6.00 Mhz of less than 4.0 ma. Also the microprocessor has a large number of input and output pins that are arranged within the groups called ports. Many of the functions of the electronic pipette 10 are handled through the card or internal circuits 102 of the microprocessor 38. The most important internal circuits with respect to the operation of the electronic pipette 10 are discussed below.

Circuits and Internal Ports The microprocessor 38 is equipped with an internal reset circuit. When the external reset circuit 108 (Figure 3C) forces the RESET pin (reset) of the microprocessor low, or when a stopwatch signals the end, a reset sequence is initiated, This reset sequence triggers a delay. At 6.00 MHz the delay is 21.8 msec. This delay starts when the reset external line is released and is brought up to Vcc. This microprocessor also has two conventional oscillator circuits 120 and 122 called "Main System Clock" and "Subsystem Clock". The "Main System Clock" 120 is a fast oscillator circuit that operates in a megahertz frequency range. The oscillator 120 can be stopped under the control of the microprocessor to conserve energy. When the power is turned on or when the main clock is reset after it has been stopped by the processor, there is a delay of 5.46 msec. for oscillator 120 before it is guaranteed that the frequency will be stable and the processor actually starts executing the instructions. Instruction execution times depend on the ratio of the division chosen by the program to the microprocessor, and can be in the range from 0.67 μsec to 10.7 μsec. The "Subsystem Clock" 122 is a slow-speed clock that is intended to be used for energy conservation and for time-keeping purposes. The crystal for this watch is 32,769 Hz. This clock is always active but uses very little current (4 μA).

In addition to the crystal, two small capacitors C2, C3 and C4, C5 (22pF) are necessary for the operation of each of the oscillators. In addition, a resistor R13 of 300 K is required for the operation of the Subsystem Clock 122. Several of the ports have important characteristics for the electronic pipette 10. Ports 6 (P60-P63) and 7 (P70-P73) contain tensile resistors. controllable by software that are used to automatically polarize the circuits for the control keys and the trip switches 26a, 26b; 28a, 28b; 30 and 32 (SW1 - SW6). The activation that shortens the associated input of the microprocessor associated with the ground. Additionally, bolts 60 and 61 of Port 6 energize the voltage reference described later. Port 5 (p50 - P53) is an open drain outlet that has the capacity to withstand voltages up to 13V. this is helpful when dealing with the presence of a voltage that is higher than Vcc and as will be described later, it greatly simplifies the control of a P-channel MOSFET switch in a conventional Double Complementary MOSFET designated as U7 that regulates the power of the charge of the battery. Port S (S12-S31) provides multiple pulse levels for the LCD segments of screen 22. The AN port (AN0-AN7) is an analog input to an internal Analog to Digital converter (A to D) included in the microprocessor. The converter A to D is preferably an 8-bit successive approximation converter equipped with an internal sample and a containment circuit. At 6.00 Mhz each of the conversions will be taken at least 29 μsec. The conversions are made with respect to the reference voltage that appears in the Avref port. This voltage reference is supplied by a voltage reference of 3 micro-energy low drop terminals set at 2.5 volts and designated as U2. The U2 could be the MAX 6125 available from Maxim Integrated Products. The internal converter A to D serves two functions, measuring the voltage of the Node Vcc and measuring the voltage of the Wall Node (Figure 3A). in both cases the voltage input to the internal converter A to D is reduced to 0.41 times the actual value of the action of the voltage dividers formed by R3 - R5 and R4 - R6 in the external circuit A to D 114. At a frequency of 6.00 MHz clock, a conversion to 28 μsec will be carried out. Because the input of the internal converter A to D is sampled and retained, the signal does not have to be stable during the entire conversion period. however, the Avref entry must be stable for the entire conversion. C8 decouples the peaks generated by the screen 22 of the LCD polarization circuit 116. The SPI (Serial (P00-P03) port is used to program and read a serial EEPROM memory designated as U8.) It can also serve as a communications port for the microcontroller 38 if the "DO Pad", "Di PAD" and "CLK PAD" inputs are used on the printed circuit board of the electronic pipette This serial link provides high-speed bidirectional communication to and from the processor. LCD port (S12-S31 and COMO - C0M3) of the microprocessor 38 is a semi-autonomous peripheral circuit that transfers the segment of data stored in the memory to the LCD segments of the screen 22. It automatically outputs the multiple voltages needed to control a multiplexed screen There are 20 segment lines and 4 common lines available Through multiplexing, the four common lines (COM0-COM3) can control up to 80 individual LCD segments All real multiplexed circuits are contained in the microprocessor 38. To activate an LCD segment on a screen, a bit is written into the memory. After choosing a mode of operation, the microprocessor handles all screen functions in a conventional manner. The polarization voltages of the LCD screen are input to a VLC port (VLC0-VLC2) by dividing the reference voltage of 2.5 that is used for the internal A to D converter. The Voltage reference U2 used for the Vref of the internal A to D converter is also used as a source of the polarization voltage of the LCD screen. The VLC 0 receives the full reference signal of 2.50 volts. This level is further divided into Rll and RIO to provide a second voltage level, 1.25 V for VLC1 and VLC2.

Screen The screen 22 is preferably of the type that does not have rear ignition, of liquid crystal that includes a total of 57 advertisements, or segments interchangeable individually.

The announcements describe the state of the unit at any given time as follows: "8.8.8.8" Volume digits with individually steerable segments that indicate volume, these are large and prominent advertisers in relation to the other advertisers. It also displays "FULL" "Full" when the battery is fully charged as well as other messages. "μl" Indicates the volume units and is located immediately to the right of the fourth digit of the volume screen. "88X" Aliquot number. two digits of individually steerable segments followed by a "X2. Used to indicate the number of aliquots that can be dispensed when in multiple dispenser mode.It is located on the left or on the digits of the volume so that the screen can be read for example: lOx 20 uL. they are used to indicate the cycle count. "PICKUP" Indicates that the unit is in the "Home" position and is ready to aspirate some liquid, or is in the process of doing this. "DISPATCH" Indicates that the unit is ready to dispense some liquid, or is in the process of doing so. "PIPET" Indicates that the pipette is in pipette mode (default) "MULTI" Located to the left of "dispatch", this annunciator indicates that the unit is in the multiple dispenser mode, and as a consequence, when it is ready to dispense the screen, "Multi dispenser" is read "& MIX "To the right of" Pipette "this annunciator indicates that the unit has activated the" MIX "option (MIX)" MANUAL "Indicates that the unit is in the Manual mode of the operation." RESET "Blinks in the mode of the dispenser Multiple when the unit has finished dispensing all its aliquots and the user is required to discard or return the residual volume. The reset annunciator is turned on (stable) while the reset function is performed (ie dispatch, burst, and return to the home position). "SPEED" Indicates the current speed setting when the Speed option is selected. "Icon 'low bat'" Indicates a low level of battery charge. It appears when the battery needs charging. Icon "Illumination Bolt Indicates that the unit is connected to a charging source, and the indicator flashes when the pipette's battery is receiving charge.

External Reset Circuit (Reset) The reset of microcontroller 38 is controlled by the reset circuit 108 illustrated in FIG. 3C and may comprise a MAX821RUS (U)) available from Maxim Integrated Products. When the energy is first applied to the U9 unit, the circuit maintains the reset low (to ground) for 100 msec after the energy has reached a voltage threshold of 2.63 V. It will also be taken under reset (to ground) if the power drops below 2.63 V for a certain time. The time required to initiate the reset depends both on the amplitude of the fall below the 2.63 level, and how long it stays below that level. The supply current is 2.5 μA. It is guaranteed that the reset remains low for voltages as low as 1.0V.

EEPROM Memory Circuit 110 The EEPP.OM memory designated as U8 and illustrated in Figure 3B is an electrically non-volatile erasable memory, programmable as 93LC56ASN. It stores 256 words of 8 bits each, has timed write and erase cycles automatically and can operate at a low of 2.0 V. In addition, it can pass 1,000,000 write erase cycles. The current during the operation is 1 Ma while the standby current is 5 μA. The data is transferred to and from the EEPROM 110 through the SPI 3-wire serial link. Additionally a bolt is provided that is active in HIGH (High). During the normal operation of the electronic pipette, when the programming of EEPROM is not required, the U8 is not energized. This is achieved by taking the GND terminal, the Vss pin, to the voltage of the Vcc node. During normal operation when the information is not written to or read from U8, the MOSFET of channel N of U7 is not enabled, the bit of port P81 of the microprocessor is low. This action denies a return path of energy for U8. Also note that the P03, = P02 and P01 lines of the SPI port must also be kept at HIGH in order to bring all the U8 lines to the same voltage level. The P80 Port bit should also be kept high during normal operation. This can be achieved through one of the three methods. The most preferred is to put the line in a three-state (floating) condition and let Rl of the EEPROM circuit 110 pull the line up from the voltage of the Vcc node. Alternatively, the P80 port bit can be converted into an input and passively lifted up through the actions of an internal traction resistor enabled by software. Or finally, the P80 line could be actively propelled towards the high state, although this is the least desirable of the three options. When it becomes necessary to read or write the EEPROM, the bit of port P81 goes high. This action drives the MOSFET of Channel N in U7 and provides a trajectory for GND for the Vss pin in U8. If P80 is in a three state condition, then this action will also pull the low CS line through the action of Rl. If P80 is actively driven then it must be adjusted to the low state immediately after or immediately before the bolt Vss is taken to GND. if P80 is passively pulled by the action of the internal pull resistor, then an output must be made immediately, and driven low. The CS pin of U8 is a high active input and while it is high, the chip will be enabled. Once the U8 chip is energized and is in a stable empty current state, the CS, Data Input, Data Output and Clock lines can be used in a normal way to read from and write to the chip. these lines follow the SPI protocol of the industry standard for data transmission. The ideal sequence to lower the energization of U8 is to put P80 in a three-state condition. It must be kept in a low state through the action of Rl. P02 and P01 must be set high. Finally, P81 must be taken actively. While draining the MOSFET from Channel N to U7 raises the voltage, Rl must pull the CS line upwards with the rest of the lines on the chip. In this way, the CS line never rises more quickly than the other lines and therefore the EEPROM will never be enabled. The following parameters are for storing inside the U8 EEPROM memory through a connection to the personal computer or a workstation through a J3 battery connector in the Figure 3A in a conventional manner. to. Version number of the EEPROM data set. b. Full-scale volume range of the pipette (2, 10, 20, 100, 200, 1000 and 2000 μL) c. Compensation table (same table that will be used in all modes). ~ Uses around 230 bits of EEPROM memory. Each of the bits corresponds to a volume adjustment of the pipette and allows _ + 254 compensating micropasses in each of the volumes. d. Residual value of the multiple dispenser e. Value of exceeding the firing of the multiple dispatch f. Duration of the pause to exceed the trigger of the multiple dispenser g. Speed limit for Pipette and Multiple Dispenser modes. h. Hysteresis manually (for kickback) that is added to the movement of the engine when changing travel directions. i. Maximum delay time of the double-click trigger j. Minimum pressure of large key. This parameter is used to determine if the Mode or Reset key has been pressed long enough for a "long press." k Default speed settings (adjusted to increase energy) for each of the modes.

Motor Boost Circuit 118 Motor booster consists of four Complementary Double MOSFETS MMDF2C01HD (U3-U6) in packs 4 SOIC of 8 bolts. Each of the packets contains both a P-channel MOSFET and a N-channel MOSFET. Each FET node can handle 2 Amps up to 12 V. Power dissipation for the pack is 2 Wats. The drain to the source resistance (Rds) for Channel N is 0.045 ohms and for channel O it is 0.18 ohms. The MOSFETs are arranged in a classic H-Bridge configuration. Each of the FET is controlled individually by the microprocessor. In order to avoid accidental driving during resetting, energizing or parking conditions, each of the FETs of the P channel is pulled to the voltage of the Vcc node through a pull resistor 51KO. All 8 bits of ports 2 (P20 -P23) and 3 (P30-P33) of microprocessor 38 are connected directly to the gates of complementary FET pairs U3-U6. U3-U6 form two complete H-bridge impellers to drive the two windings A and B of the stepped motor as shown in Figures 3C and 3E. The circuit is a simple classic circuit without current detection or feedback from the motor. this simple circuit is usually associated with the normal full pitch or with the half-step pulse to a stepped motor. This is not associated with a micro-staggering because it lacks the sense of traditional motor winding current with feedback to the comparator and associated circuits that form a pulse width modulation (PWM) pulse forcing the motor current to track the signals of the motor. control from a micropass controller. In a traditional micro-step pulse circuit, the frequency or period of the PWM signal is asynchronous from the step speed of the motor from the micropass controller. The micro-step control of a stepped motor is desirably over full or half-simple steps because it gives finer control of motor positioning while allowing the motor to run more efficiently at high speeds (i.e., more power output from the motor). the motor for an energy input determined to the motor.) These two characteristics are important in a battery-powered electronic pipette. The micro-step control of the motor is achieved with the simple circuit shown in Figure 3 if the PWM period is synchronized with the speed of the steps. this is achieved by having a microcontroller 38 that generates the PWM signals to the two bridges H, and that causes each of the micropasses to correspond to an integer number of the PWM periods. At the highest motor speed, each of the PWM periods will correspond to a new micropass. Figure 4 shows the impulse signals of the gate that goes from an electrical position of 45 degrees to 135 degrees at full speed. The service cycles to each of the motor windings correspond to a function of sine and cosine that are advanced in increments of 5,625 degrees. Period 1 corresponds to 45 degrees of electrical rotation where the two windings of the motor receive an equal current. The winding A, cosine function, is driven from Port 2 (P20 to P23) and winding B, sine function, is driven from Port 3 (P30 to P33). Both ports have a service cycle equal to 45 and 135 degrees. The seventeenth period (micropass) corresponds to an electrical position of 135 degrees. The PWM period is equal to approximately 188 microseconds corresponding to a PWM pulse frequency of approximately 5.32 kHz for each of the motor windings. At full speed, where one of the PWM period corresponds to a micropass, the step speed is 332 complete steps per second (5.32 kHz divided into 16 periods per full step). The FET of the P channel is usually maintained by keeping the gate impulse low (P21, P23, P31, and P33). The only time the P-channel FET goes off (the gate goes high) is when the FET of the corresponding N channel is activated (the gate is driven up through P20, P22, P30, and P32). The FETs used have a low threshold, the high-speed FETs so that a small guardband is added to each of the change edges of the P-channel FETs to ensure that they are deactivated before a N-channel FET is active This prevents current peaks from flowing through a pair of complementary FETs during the exchange transitions. The guard bands can be easily seen in Figure 4a which illustrates only the first period of Figure 4. At the beginning of period i, P21 goes high first by turning the FET of the P channel to deactivate it. Approximately one machine cycle later in the microcontroller (2.67 microseconds) P20 goes high by turning the FET of 4 channel N to activated. About 77 microseconds later P20 goes low by turning the FET of the N channel to off 2.7 microseconds before P21 activates again the FET of the P channel. The other side of the coil A is to keep connected to the supply rail through the FET of the P channel driven by P23. During the remaining period 1 both sides of winding A are kept tight towards the supply rail allowing the channel in the winding to circulate with minimal external losses. Winding B is driven through Port 3 in a manner similar to winding A except that the "on" portion is at the end of the first period instead of the beginning as would be expected from previous technology PWM circuits . The advantage of driving the two windings at different ends of the PWM period is that it is possible to avoid having both windings at the same time considering that the peak of the PWM service cycle of the sinus function does not exceed approximately 70% so that in the point of 45 degrees the cycles of service PWM of the sine and the cosine do not exceed 50% each. Allowing guard bands of the P-channel and processing of the microcontroller for practical peak service cycle times are closer to 60% (instead of 70%) resulting in a duty cycle of approximately 42% in the points of 45 degrees for each of the windings. A peak PWM service cycle of less than 60% ensures that the two windings will never be activated at the same time. The advantage of not having both windings at the same time is that it significantly reduces the variations of current (fluctuation) from the supply, thus reducing the voltage fluctuation of the supply. The current jitter reduction allows the use of a shunt capacitor with a smaller value on the supply rail (Cl and C6) to keep the voltage fluctuation within acceptable limits. Likewise, an even more serious restriction is caused by the fact that the wall power supply 37 (Figure 22) used to energize the unit and charge the battery has a hard and fast current limiting action on the battery's rate. of 2.6 C (1.04 Amperes). If the motor treats and pulls more than 1.04 amps of torque supply the supply voltage will drop rapidly since only the shunt capacitors (Cl and C6) supply the current in excess of the limit point of the supply. current. This potential problem is easily avoided by not allowing the two windings to be performed at the same time. It is an important feature of the preferred embodiment of the present invention that the motor can operate at slower speeds by having a PWM period that repeats the same service cycle that is through the control of the pulse service cycle microcontroller of successive impulses. If each of the service cycles of the micropass was used for the two PWM periods then the motor speed would be one-half the maximum speed (ie, with a 2: 1 correspondence between the PWM period and the micropass). If each of the steps were used for the three PWM periods (ratio 3: 1) then the engine speed would be one third of the full speed and so would follow. For the finest control of speed it is not necessary that each one of the microchips repeat the same amount. For example, if each 16th micropass. it was repeated once and another 15 were not repeated then it would result in the speed being 94.12% of the maximum speed (16/17); similarly, if each eighth micropass was repeated once the speed 5 resulting would be 88.89% of full speed (8/9). The speeds closest to the maximum speed can also be obtained by repeating a micro-step less frequently than once every sixteenth step. The ten different speeds of the pipette basically use a correct repeated pattern to give the motor the desired speed. The table of Figure 5 illustrates the feature of the present invention with a corresponding table of data that is stored in the microprocessor memory. When accelerating from a total stop to the specified pipetting speed, an acceleration table is used, similar to that shown in Figures 7a-7b, which defines the pattern in which the micropath cycle service cycles are repeated over a period of time. PWM so that the speed approaches asymptotically at the specified operating speed. Figure 6 and Figure 8 are graphs that describe the data. The acceleration ramp (which also works in reverse to decelerate) defines and limits acceleration. Acceleration is reduced as the engine speed approaches its maximum speed by making finer speed changes successively. A corresponding table of data is stored in the microprocessor to allow the microcontroller to provide control over the operation of the stepped motor. The resulting current from the motor from the simplified control circuit of the micropass and the method described above is not independent of the supply voltage as it is in a traditional PWM pulse circuit of the prior art. Instead, it is dependent on the supply voltage. The battery voltage of the Li-ion battery 36 used in the present invention ranges from 3.2 volts, when the battery is nearly depleted, to 4.1 volts when charged to full capacity. In this same amplitude, (ie peak service cycle) the sine / cosine tables are used across this voltage range, the energy to the motor will vary by the square of the voltage ratio between the voltage range (ie, 64% more energy at 4.1 volts than at 3.2 volts). When the pipette is used while energized from a wall supply, the supply voltage is typically 5.3 volts causing almost three times as much power as the motor is driven compared to 3.2 volts if the same tables were used. The microcontroller used has the ability to measure the supply voltage with the analog to digital converter of the microprocessor as described above. The above disadvantage can be significantly reduced by dividing the supply voltage into different ranges and using a different sine / cosine amplitude table for each of the ranges; this makes it possible for the motor current to normalize for the different ranges. The microprocessor of the present invention is programmed to divide the supply voltage into four ranges and has four different sine / cosine amplitude tables that normalizes the motor current between the different ranges. This is described in the tables of Figure 4b - 1 and Figure 4b - 2 and has the effect of reducing the motor current and therefore the energy variations to a much smaller value over the total supply of the voltage range . The ranges used are: 3,200 to 3,476, 3,476 to 3,775, 3,775 to 4.1, and 5.0 to 5.6. For the battery voltage range this reduces the energy variation of 64%, if only one range is used, less than 18% with the use of the three ranges, the fourth range is used for the wall current. Using different energy ranges as a function of the supply voltage has the effect of reducing unnecessary draining of the battery and thus significantly increasing battery life. This also eliminates the possibility of exceeding the motor's power rate when operating outside of a wall supply.

Pipette Operating Modes In the illustrated embodiment of the present invention, and as previously described, the control key 26 comprises a "mode" control key on a keyboard for the pipette. The "mode" key is held or rotated through three regular operating modes of the pipette. The software routine of the microprocessor 38 for the Mode key is described in Figure 12 ("Mode Key Routine"). As illustrated, the entry of the Mode Key Routine starts on the internal timer inside the microprocessor. The timer has stored a pre-set duration in the EEPROM memory 110. If the mode key is pressed for a period equal to or greater than the preset duration, a "long press" of the Reset key will occur that activates the Options menu for any of the determined modes and the additional presses of the Mode key rotates through the options available for the determined mode; Another long pressure will deactivate the Options menu allowing additional pressures to select the modes. Modes: 1. Pipette 2. Manual 3. Multiple Dispenser The "up" and down "arrow" keys 28a and 28b are used to edit or change any of the selected parameters such as volume and speed settings according to the routine of the microprocessor software described in Figure 14. The fourth key 26b, "Reset" (Reset) has two primary functions depending on whether the unit is in the home position or not. If the pipette is not in the Home position (that is, ready to dispense has finished dispensing all its aliquots in the Multiple Dispenser mode) pressing the Reset key will cause the pipette to dispense, blow or return to the Initial position according to the routine of the microprocessor software described in Figure 13. When the device is in the Initial position, ready to pick up, the Reset key 26b is used to toggle or rotate through the various parameters that they can be edited in the selected mode. For example, in the Multiple Dispenser mode it is used to toggle between the number of aliquots and to dispense the volume so that any of these can be edited. In each of the following modes of operation for the pipette 10, this comprises the motor 40 with windings A and B to receive current to electromagnetically drive a rotor in order to impart a longitudinal movement to the piston 90 in the cylinder 92 and a circuit control 110 including the microprocessor 38 programmed to generate the impulse signals for the motor. In each of the operation modes, the control circuit 110 comprises the screen 22; the control keys operable by the user 26a, 26b, 28a. 28b electrically connected to the microprocessor to generate in the microprocessor the operation mode of the pipette, volume to collect liquid, dispense liquid, pipette operating speed and pipette reset signals to control the operation of the pipette and the screens alphanumeric readable by the user on the screen; a memory that has data tables stored and that are accessible and can be used by the microprocessor to control the operations of the pipette; and at least one of the switches operable by the user 30, 32 to trigger the pipette operations selected by the activation of the user of the control keys. In each of these operating modes, the microprocessor is additionally programmed to sequentially enter the successive operating modes selected by the user in response to the successive activation of the user of a first control key defining a key - "mode" and in each of the modes selected to control the operation of the pipette so that: (a) a second activation of the mode key or another of the control keys defines an option key that causes the microprocessor to control the display to display a first option of operation only for the selected mode, (b) a second control key defines an "up" key, the activation of this cause that the microprocessor controls the screen to indicate an activation or deactivation of the operative option or an increased value of an associated numerical display with the operative option, and (c) a third control key defines a "down" key, which when activated causes the microprocessor to control the screen to indicate an activation or deactivation of the operative option or a decreasing value for the numerical display, and (d) subsequent activations of the trip switch user activate the motor to drive the plunger in the selected mode augmented by the operating option in an upward direction to collect the liquid at the tip and then in one direction down to dispense the liquid from the tip. Also, the microprocessor is further programmed such that in each of the successive activations by the user of the selected mode of the option key the microprocessor is caused to control the screen to sequentially display the successive operating options only for the selected mode, each controllable according to (b) and (c) above. Still further, the microprocessor 38 is preferably programmed so that the functions of the mode keys as well as the option key pass between the successive operating options in response to an initial sustained pressure of the mode key for a period greater than that of a momentary pressure of the mode key followed by the successive momentary pressures of the mode key. Also, the microprocessor 38 is preferably additionally programmed to control the screen to cause the screen to exit the operational options while remaining in the selected mode in response to the user activation of a fourth control key that defines the key. "reset" (reset) and / or a subsequent sustained pressure of the mode key. Still further, the microprocessor 38 is preferably additionally programmed so that the reset key forces a display parameter to be displayed to read zero in response to an initial sustained pressure of the reset key for a period no greater than of the momentary pressure of the reset key and is also programmed to enter a "blow" operation in response to a momentary activation of the reset key to drive the plunger in the cylinder to blow fluid from the tip of the pipette . Also, the microprocessor 38 is preferably further programmed so that each momentary successive activation of the user of the reset key causes the microprocessor to control the display 22 to sequentially display an operating parameter different from a "plurality of successive operating parameters to be edited by the activation. of the user of the keys to go up or down and is also programmed to count and to control the screen to distinctly display the pipette screen as for the different pipette screens for the successive cycles of pipette operation in the selected mode of the operation of the pipette allowing the user to determine the cycle of operation of the pipette during any period of operation thereof As will be described later herein, one of the modes of operation of the pipette 10 is the manual mode. In that mode, the pipette uses two actionable switches s by the user (30, 32) to trigger the selected pipette operations through user operation of the control keys. In manual mode, the microprocessor 38 is also programmed to enter the manual mode of operation selected by the user activation of the mode key and in the manual mode to control the operation of the pipette so that (a) a first switch of User-triggered trigger defines a trigger to "raise" that causes the microprocessor to control the motor to drive the plunger in an upward direction to pick up the liquid inside the tip, and (b) a second trigger switch triggered by the user defines a trigger to "lower" which causes the microprocessor to control the motor to drive the plunger in a downward direction to dispense the liquid from the tip and to control the screen in order to indicate the volume of liquid at the tip. Furthermore, in the manual mode, the microprocessor 38 is also programmed to control the operation of the pipette so that while it is in the initial position with the plunger in a location ready to start the aspiration or collect the liquid the screen will display the maximum volume that can be collected, and, (a) the activation of the "up" key causes the microprocessor to control the screen to indicate an increase in the value of a selected maximum volume of liquid that will be collected by the tip while the "up" key is operated by the user, and (b) a "down" key operation causes the microprocessor to control the screen to indicate a decrease in the value of the selected maximum volume of liquid to be collected by the tip. Furthermore, in the manual mode, the microprocessor 38 is also programmed to increase the speed to collect and dispense the liquid while the user activates the trigger to raise and the trigger to lower respectively. As will be described later, in manual mode, one of the data tables stored in the memory accessible through the microprocessor 38 comprises correction factors for a maximum volume to be collected associated with the tip of the pipette to reduce the errors of liquid volume associated with collecting and dispensing liquids by the pipette and the correction factors are added to the movements of the motor to pick up and dispense in order to correct the volume errors. In addition, in manual mode, the microprocessor is also programmed to count and control the screen so that it displays distinctly different screens for the user of the pipette regarding the successive cycles of pipette operation in the manual mode of the operation. of the same allowing the user to determine the operating cycle of the pipette for any period of operation of the pipette. In the same way, it will be described in greater detail later in the document, in a pipette operation mode for the pipette 10, the microprocessor 38 is additionally programmed to control the operation of the pipette so that (a) the activation of the "up" key "cause the microprocessor to control the screen to indicate an increase in the value of a selected volume of liquid to be collected by the tip, and (b) activation of the" lower "key causes the microprocessor to control the screen to indicate a decrease in 'the value of the selected volume of liquid to be collected by the tip, and (c) the first user activation of any of the trip switches will drive the motor to drive the plunger in an upward direction to pick up the volume selected liquid at the tip and (d) the second user action of any of the trip switches will activate the motor to drive the plunger in a downward direction to dispense the selected volume of liquid from the tip. In addition, in the pipette mode, one of the data tables stored in the memory comprises instructions for controlling the impulse signals applied to the linear actuator in order to control the speed of operation of the motor according to the speed settings. selected by means of user activation of the control keys and another of the data tables stored in the memory comprises the correction factors for the various liquid collection volume settings selected by the activation of the user of the control keys. control to control and eliminate fluid volume errors associated with collecting and dispensing liquids through the pipette. Like the manual mode, in the pipette mode, the microprocessor 38 is programmed to count and control the screen to distinctly display to the user of the pipette the different screens for the successive cycles of operation of the pipette in the pipette mode of operation thus allowing the user to that determines the cycle of operation of the pipette during any period of operation of the same. Unlike the pipette mode, the microprocessor 38 is further programmed to (1) collect a second selected volume of liquid when the plunger reaches the start position in response to the user actuation of one of the trip switches while the plunger approaches the initial position to dispense the selected volume of liquid and (ii) dispense and mix the second selected volume of liquid with the selected volume of liquid. As will be described later in greater detail, in a multiple dispenser operation mode, the microprocessor 38 is also programmed for the control operation of the pipette so that (a) the activation of the up key causes the microprocessor to control the screen to indicate an increase in the value of a selected volume of liquid to be dispensed by the tip and (b) activation of the lower key causes the microprocessor to control the screen to indicate a decrease in the value of the selected volume of liquid that will be dispensed by the tip, and (c) the third control key defines a "reset" key, the activation of this cause the microprocessor controls the screen to indicate a number corresponding to the number of liquid aliquots of the volume selected that the pipette can dispense which is adjusted through the activation of the "up" and "down" keys and (d) the first actuates by the user of any of the trip switches drives the motor to drive the plunger in an upward direction to pick up within the tip a volume of liquid corresponding to the volume of the full scale of liquid for the pipette, and (e) the second activation by the user of any of the trip switches actuates the motor to drive the plunger in a downward direction to dispense the selected volume of a liquid from the tip which is repeated for each of the second activations of either the trip switches until the number of aliquots is finished dispensing through the pipette. As in the manual mode and in the pipette mode, in the multiple dispenser mode, one of the data tables stored in the memory comprises the instructions for controlling the impulse signals applied to the linear actuator in order to control the speed of the operation of the motor according to the settings of the operating speed selected through the activation by the user of the control keys and other of the data tables stored in the memory comprise correction factors for various volume adjustments of liquid selected through user activation of the control keys to control and eliminate the volume errors associated with collecting and dispensing liquids by the pipette. Further in the multiple mode, the microprocessor 38 is further programmed to control the motor to enter a "blow" mode where the motor drives the plunger past the initial position for the plunger to blow the remaining liquid on the tip after that the plunger reaches the initial position. Pipette Mode The pipette mode is described by the software flow chart of Figures HA and 11B and is indicated by the "Pipette" annunciator on screen 22. The up and down arrow keys 28a and 28b are used to change the volume. The arrow keys are only active when the pipette is in the initial position indicated by the "pickup" annunciator activated. When either of triggers 30 or 32 are pressed, the pipette aspirates the indicated volume at the motor speed corresponding to the speed setting. As indicated in the flow diagram of the di HA software, when the pipette is in its pipette mode, each collection of liquid volume selected by the user through activation of the trigger switch (30, 32) adds compensation to the steps of the movement of the motor to correct the effects of fluid that could otherwise result in the aspirated volume being less than the selected volume. These errors are described by the lower curve in Figure 9 while the correction factors for each of the selected volumes are described in the upper curve of Figure 9. Figures 9a-9f describe in the graphic format a table of these correction factors for the various volumes selected or "adjusted" by the user for the pipette 10. A table of these data is stored in the EEPROM memory U8 and accessed through the microprocessor 38 to add pulses as the microsteps for the train of pulses comprising the impulse signal to the winding A and the winding B of the motor 40. This is the result of adding the compensations to the longitudinal movement of the piston 90 in the cylinder to drag within the tip 60 the selected volumes of liquid. Upon completion of the aspiration, the dispenser annunciator is activated at the same time that the collection annunciator is deactivated. When any of the triggers is pressed, the pipette dispenses its entire volume at a speed according to the speed settings, passes through the blow step to the bottom of the blow, pauses for a second there, and returns to the position Of start. The pipette will pause before entering the blowing step for a period determined by the speed setting (usually higher at slower speeds). If the trigger is pressed when the pipette reaches the bottom of the blow, it remains at the bottom of the blow until the trigger is released. Pipette Mode Options: As described in Figure 12, if the Mode key is pressed for a longer duration (more than 1 second) the Options menu for Pipette mode will be activated. The first item displayed will be the last item displayed from the previous access of the Options menu. (Speed is the default option after initialization). The following normal pressures of the Mode key will alternate through the options available for the Pipette mode listed below: a. Speed b. and Mix c. Cycle Counter When Speed is selected, the "Speed" annunciator will turn on and the Speed setting will blink on the first digit of the volume display. The up / down arrow keys can be used to change the speed setting. The speed setting is unique for each of the modes. The default setting that is selected when the initial power is activated is determined by what is programmed into the EEPROM U8; this will typically be the fastest speed available for the Pipette and the Multiple Dispenser modes and an average speed for the Manual mode. The selectable speeds are listed from 1 to 10. The following tables indicate the times that were carried out through the speed setting for each mode of operation. Pipette Mode (ms) (ms) (ms) (ms) Move Scale Adjust Pause Standby Full Speed at Start Blown at the end 706 0 126 1090 9 1010 420 215 958 8 1470 585 300 1060 7 1940 805 375 1050 6 2410 860 500 980 5 2800 1080 320 1040 4 3190 1460 580 1050 3 9820 1730 690 1060 2 4460 1900 800 1060 1 5280 2540 1040 920 Manual mode : (ms) Adjustment of Move Speed Full Scale 10 2.2 9 3.0 8 4.2 7 5.8 6 8.1 5 11.2 4 15.5 3 21.5 2 29.7 1 41 Pressing any of the triggers will collect the volume in pipette mode at the selected speed and exit the menu of Options. A long press of the Mode key or a press of the Reset key will cause it to exit the Options menu. A normal pressure of the Mode key will cause it to alternate with the Mixing Option. As described for the software flow diagram in Figure 15, when the Mix option is selected in the Option menu the "& Mix" annunciator will light up and the volume digit screens will read: "DISABLED" (Off) "ON" (On). The up / down arrow keys can be used to adjust the Mix option for any of the states. When the Mix option is left on the "& Mix" annunciator it is also left on when you exit the Options menu. Operation with the Mix option enabled is similar to when it is disabled except that mixing can be performed at the end of the dispenser cycle. The mixing will occur as follows: 1. A mixing cycle (mixed volume aspirated from the starting position and will return to the starting position) will be performed if the trigger is pressed when the piston approaches the starting position (home) 2. Additional mixing cycles will be presented until the piston approaches the start position (home) and the trigger is not pressed. 3. Raising and re-pressing the trigger in the middle step will have no effect while the trigger is pressed when approaching the start position. 4. If at the time of approaching the start position (either after a pipetting step or a mixing cycle) and the trigger is not pressed, the pipette will pause, a blow step will be performed, the pipette will pause at the bottom of the blow, and will return to the start position (end of cycle). Therefore, the mix can be skipped while operating in the mix option at the user's desire. 5. LCD "pick up" and "dispense" annunciators will be activated during each of the corresponding parts of the Mix cycle. (That is, collection during aspiration and dispensing during dispenser operation). The mixing volume (volume aspirated and volume dispensed during the mixing cycle) for E3 will always be the same as the volume set for pipetting. The speed of the mix will be the same as the motor speed as programmed in the speed setting mode. When the Cycle Counter is selected from the Options menu in the Pipette mode, the displayed digits will be read. "CC OFF" or "CC ON" _ The up / down arrow keys can be used to toggle between the two states. When you exit the Options menu with the Cycle Counter activated, the two digits to the left of the volume screen will indicate the cycle count. Initially, 00 will be read. Each time the pipette cycle is finished, the counter will increment one. When it reaches 99 it will return to 00. When the cycle counter is active, pressing the Reset key while it is at startup will alternately select the cycle counter count or the collection volume. The up / down arrow keys can edit the selected parameters for any adjustment. A pressure with a long duration of the Reset key is a quick way to reset the counter. The following is a summary of the actions when pressing the key in the Pipette mode: In the Start position (Home) "Arrows" Adjusts the collection volume or cycle counter count, what is selected. "Reset" The normal duration pressure selects the collection volume or the cycle counter count, if it is activated, otherwise it does nothing. The pressure with long duration sets the cycle counter to zero, if it is activated, otherwise it will not do anything. "Mode" The pressure with normal duration alternates to the following mode. Long-term pressure activates (or deactivates) the Options menu screen. After a Pickup: "Arrow" Does nothing "Reset" The pressure with normal duration dispatches, blows, pauses and returns to the start position. The long-term pressure will do nothing. "Mode" It does nothing. Manual Mode The flow chart of the microprocessor software 38 for the manual operation mode is described in Figures 10A and 10B. In manual mode the displayed volume is the default installed volume (full scale) unless a smaller volume ("collection limit") is adjusted. This determines the maximum volume of liquid that can be collected. The first pressed trigger (30 or 32) when entering the Manual mode becomes the "raise" trigger and the other becomes the "Download" trigger by default. Pressing the "raise" trigger causes the display to stop the display of the maximum collection limit and begins to collect the liquid, slowly at first, then at a faster and faster rate. The screen indicates the amount of fluid collected so far. The maximum speed is controlled by the selected speed setting through the use of the Speed option as previously described according to the routines set forth in Figures 13 and 14. By leaving the trigger "up" for the engine up. If that same trigger is pressed again, the collection continues; slowly at the beginning and then with a faster speed each time as mentioned above. Thus, by quickly pressing and releasing the trigger before the ramp rises to high speed, very fine control of the liquid collection (or dispense) can be achieved. The screen continues to show the total liquid collected from the start position. If the reset button is pressed with a long duration, the screen resets to zeroes and the screen will then indicate the volume picked up, or dispatched (depending on the trigger that is pressed immediately), then the screen is set. If the reset button is pressed with a normal duration, the unit will dispense, pass through "blown", pause at the bottom of the blow, and return to the start position and the displayed volume will revert to the collected limit that was the last adjustment- Pressing the "lower" trigger causes the liquid to be dispensed, slowly at the beginning and then at a faster speed each time as indicated above. When a change occurs from pick up to dispense (or vice versa), the compensation steps are added so that the movement of the motor compensates the fluid and the effects of mechanical kickback. The number of compensation steps depends on the volume range of the instrument and is stored as data accessible to the microprocessor in the EEPROM memory U8. These are additional data to the correction factor of the referred table, in relation to the correction of the fluid effects for the Pipette Operating Mode. While dispensing, the display decreases to indicate the amount of liquid at the tip (collected from the start position) unless the screen is reset. This allows you to overdisplay and then return to the desired amount. If the screen has been reset (by pressing the reset button with a long duration) the screen then indicates in positive numbers the amount of liquid collected from that point or with a negative number the quantity dispatched from that point. The transverse bar at the center of the aliquot on the far right forms the "minus" symbol. As noted above, with any change in the direction of the motor, the correct amount of the compensated steps are added for that volume range. The continuous pressure of the trigger to dispense will cause the liquid to be dispensed until it reaches the "Home" position. at that point the engine will stop. This prevents the user from accidentally blowing, and better emulates a manual pipette (the user can mix manually, etc.). In the "initial" position (home) a "double click" of the dispensing trigger causes the unit to blow and return to the initial position. Manual Mode Options: When activating the Options menu with a long press of the Mode key, the following options can be selected, with pressures of normal duration of the Mode key: a. Speed b. Cycle Counter These Options can be edited as described under the Pipette Operating Mode. The following is a summary of the actions when pressing the key in Manual mode: In the Start position: "Arrows" Adjust the collection volume or cycle counter count, whichever is selected. "Reset" The normal duration pressure selects the collection volume or the cycle counter count, if activated, otherwise it does nothing. The long-term pressure puts the cycle counter in zeroes, if it is activated, otherwise it does nothing.

"Mode" The pressure with normal duration alternates to the next mode. Pressure with long duration activates (or deactivates) the Options menu screen. After a Collection: "Arrows" Do not do anything "Reset" The pressure with normal duration dispatches, blows, pauses, and returns to the start position. Long-term pressure puts the volume screen at zero. "Mode" It does nothing.

Multiple Dispenser Mode The flow diagram of the microprocessor 38 software for the Multiple Dispenser Mode of the pipettor operation is described in Figures 16A and 16B. When you are switching to this mode when you activate the Mode key, the volume of the dispenser is activated and can be edited with the arrow keys 28a, 28b. The delivered volume can be changed when the unit is in the "Start" position just as long as the unit is waiting to dispense. When the volume of the dispenser is changed, the number of aliquots is recalculated and displayed on the screen 22 in the two small dedicated digits adjacent to the "X" symbol. If the pipette is in the "Start" position, the number of aliquots is calculated to be as large as possible and still have sufficient residual volume (ie, a full scale collection). The residual volume can be easily changed since it is stored in U8 EEPROM memory. If the value of the dispatched volume is changed while it is being dispatched, then the number of aliquots, "X", is recalculated to represent the remaining aliquots at the tip (assuming that the dispatched volume remains unchanged for the remaining aliquots). The volume can be changed in each and every one of the pause points while the dispense phase (within the limits of the remaining volume left in the tip). After each volume dispensed the number of aliquots decrease by one so that the screen always shows how many aliquots remain at the tip.

When "X" reaches zero, the screen flashes the "reset" symbol to remind the user to press the "reset" key. If the user does not wish to aspirate a full scale load at the tip, then I could decrease the calculated number of aliquots still in "Start" before harvesting. To do this, the user presses the "Reset" key that activates the number of the aliquot field to edit. The number of digits of the aliquots and the "X" symbol blinks indicating that the arrow keys will change the number of aliquots. The number of the aliquot field remains activated until the "Reset" key is pressed again, or a trigger is pressed, in any case the volume of the dispenser is activated (but, if the trigger is pushed, liquid is also aspirated) . As long as you are in the "Home" position when you press the "Reset" key, the dispatch volume and the aliquot field number are activated alternately. If the value "X" has been reduced from the default calculation, then it will remain unchanged until the user changes it again or changes the volume dispatched; when changing the mode (or pressing reset) the settings will not be changed. When the volume dispensed in the Multiple Dispenser Mode is changed, then a new full-scale "X" value will automatically be calculated. As described in Figure 16A, when the pipette has been preset by activation of the arrows and reset keys as indicated above and using the routines of the Arrow Keys and the Reset Key, the user will activate one of the trip switches (30, 32). While the previous settings are stored, the microprocessor 38 controls the motor 40 to pick up within the tip 60 a volume of liquid in excess of the volume equal to the volume of the aliquot by the numbers of aliquots. (total volume selected). The motor runs in reverse to dispense some of the liquid leaving at the tip the correct total volume selected and a residual volume of the liquid. at that point, the arrow keys are activated to modify the aliquot volume if desired accompanied by any new calculation necessary of the number of aliquots in the microprocessor. Activation of the Reset key 26b will then cause the pipette to dispense all the liquid at the tip bypassing the multi-mode operation of the pipette. In response to the activation of one of the trip switches, however, the inverse pipettor to the microprocessor the routine of the controlled dispenser described in Figure 16B, with the microprocessor entering the compensation corrections according to the data stored in the memory U8. EEPROM as the correction data similar to the correction curve and to the tables of Figures 9 and 9a-9f as described for the Pipette Mode of the pipette operations. This operation is repeated for each subsequent activation of a trip switch until all aliquots are cleared. At that point, activation of the Reset Key or a double click on the trigger switch will cause the microprocessor to drive the motor into a blow routine in which the plunger 90 is driven to the "start" position for blow all the residual liquid from the tip and the plunger is returned to "start" and the presets are stored again leaving the pipette ready for a second operation of the multiple dispenser. In the Multiple Dispenser mode, the only option in the Option menu is to adjust the speed that operates in the manner previously described. Therefore, to summarize: In the start position "Arrows" Adjusts the volume or aliquot number, whichever is selected "Reset" The pressure with normal duration selects the volume of the dispenser or the aliquot number. Long-term pressure does nothing. "Mode" The pressure with normal duration alternates to the following mode. The long-term pressure activates (or deactivates) the Options menu screen allowing the velocity values to be adjusted. After a Collection: "Arrows" Adjust the volume and the remaining aliquots "Reset" The pressure with normal duration dispatches, blows, pauses, and returns to the start position. "Mode" It does nothing.

When the last aliquot has been dispatched (and the user is asked to reset :) "Arrows" Perform reset as follows: "Reset" Normal duration pressure dispatches, blows, pauses, and returns to the position of start. (the volume adjustment and the aliquot number returns to the values that were set last by the arrows by the user in the multi-dispatch start position) "Mode" performs the reset, as indicated above, and then alternates to next displayed mode to indicate that the pipette is in any of the three low states of the battery. It does not sparkle, as this would be potentially confusing given that the lighting bolt flashes when the pipette is charging.

Battery Power Management and Recharge Circuit 106 The battery 36 included with the pipette 10 is a lithium-ion battery that has a rating of 400 ma-hour. This is how the average current charge to the battery should be limited to a maximum of 400 ma (ie a rate of 1C) to avoid potential damage to the battery. The motor 40 carries a maximum current of more than 800 ma during the operation. Since it is desirable that the pipette 10 be able to operate from a wall power supply 37, (Figure 22) without a battery installed in the device, the power supply of the wall must have the capacity to supply more than 800 ma without fluctuation occurs due to excess voltage. It is also desirable that the same wall power supply be used to charge a battery, installed in the pipette 10 when the power supply of the wall is connected to the pipette. In addition, as described in Figure 22, it is desirable that the same wall power supply 37 be used to energize an additional charging station (not shown) that can be used to store two "or three pipettes (10, 10 ') and automatically load any of the pipettes that are placed in the charging station with a battery that needs to be charged.The small space available in the pipette does not allow any significant heat dissipation to be carried out in the pipette other than the motor It will dissipate during pipette operation.The current available from the wall power supply is considerably higher than the maximum allowable battery current.A traditional method that can be used to limit the load current is to place a Linear current source between the wall power supply and the battery to limit the current at a rate of 1C (400 ma) while charging the battery. However, this circuit will not need to be located on the pipette so you can be sure that it only limits the current when a battery is charged and does not limit the current when the motor is being used without a battery. Typically, this circuit has a 2 to 3 volt drop across it, and, with 400 ma flowing through it, approximately 1 watt of energy dissipation will occur. To dissipate 1 watt of heat in the pipette electronics, while the battery is charged for up to one hour, a larger heat sink than the space available in a compact pipette with the dimensions of the pipette electronics is required. Additionally, the heat can raise the temperature of the pipette body and the battery to an undesired level. However, in the pipette 10 of the present invention, an exchange circuit is used to overcome the problem of heat dissipation associated with a linear current limiting circuit as described above. The exchange circuit comprises the FET of channel P in U7 (Figure 3A) controlled in a time "on" (on) against the base of the time "off" (off) by a control signal of the pulse width modulation switch (PWM) from the P50 port of the microprocessor in the pipette . The current limit from the wall power supply 37 multiplied by the service cycle of the PWM signal represents the average of the changing current of the battery. if the frequency of the control signal from the PWM switch to the battery. if the frequency of the control signal of the PWM switch is sufficiently high, then the pulse of current "activated" from the wall power supply to the battery will be of a short duration so that the magnitude of the peak will not be important as the average of the "on" time and the "off" time that is average for the battery. The lithium-ion battery 36 used in the pipette of the present invention has an integrated protection circuit that opens (disconnects) the battery in case of an accidental overload. The protection circuit integrated in the battery is standard for lithium-ion batteries and is a fairly sophisticated circuit that protects against over voltage and current loading as well as excessive current loads under sub-voltage conditions. the current peak inside or outside the battery used in the pipette 10 can not exceed the order of 2 amps without the integrated protection of the circuit trip. The power supply to the wall must have a current limit that is fast enough that when the wall supply FET (FET channel P in U7) is activated, the current is immediately limited to this rated value (ie, 1.04 amps). ) resulting in an immediate voltage drop from the wall supply so that the battery is not exposed to large current peaks. Commercially available wall limiting power supplies do not limit their output current fast enough. Most shelf power supplies have relatively large output filter capacitors in their circuits that produce large current peaks when a load (battery) is suddenly connected through the supply outlet. The large current peak can not fall to the current limit value for up to one millisecond. These power supplies are not acceptable for use with a PWM controlled switch to charge the battery. Correspondingly, the power supply 37 used with the pipette 10 is designed to limit the current rapidly to 1.04 amps nominally and to cancel the current overshoot when the battery is charged with a PWM controlled switch with a rate of 1 kHz (PWM switch) comprising the FET of the P channel in U7 (Figure 3A). When charging at an IC rate the PWM duty cycle is adjusted to approximately 36% "on" time (260 μs activated 640 μs off) so that the battery sees an average load current only below 400 mA. The voltage of the regulated wall power supply is nominally 5.6 volts. The no-load battery voltage is less than or equal to 4.1 volts. Therefore, when the PWM switch is activated the voltage of the wall power supply (measured at the wall node) will fall to the battery voltage plus the drop through the PWM switch and the diode, DI, like the Voltage drop through the internal resistance of the battery due to the charging current. all together, the wall power supply voltage measured at the wall node in Figure 3A and the input to the microprocessor 38 at Port AN2 is typically in the order of 0.4 to 0.5 volts above the no-load battery voltage when the PWM switch is activated. As illustrated in Figures 3A, 3B and 3D, the measured battery voltage is the input to the microprocessor at Port ANO. The power supply voltage immediately returns to 5.6 volts regulated when the PWM switch is deactivated. The voltage at the wall node (Port AN2) will look like the one illustrated in Figure 17 when the battery is charged at a rate of IC. PH is the regulated voltage (typically 5.6 volts) and PL will typically be between 3.4 and 4.6 volts when a battery is being charged which corresponds to an uncharged battery voltage of 3.0 to 4.1 volts. Manufacturers of rechargeable lithium-ion batteries generally recommend charging a single 4.1-volt cell battery that is below 3.0 volts with a pre-charged current at a C / 10 rate. Above 3.0 volts but below 4.1 volts the battery can be charged with a current not exceeding an IC rate. At 4.1 volts (measured with a load current), the current must be gradually reduced so that the voltage does not exceed 4.1 volts. This is known as constant charge voltage phase. If this voltage limit exceeds the integrated protection circuit of the battery by a certain amount, the protection circuit will open the battery circuit. The constant voltage charging phase must continue until the charge rate falls below a rate of C / 10 to C / 20 or after 4 hours of charging, whichever comes first. The imit of final charge voltage (4.1 volts) need to be determined with about 1 percent accuracy. The regulation of the wall power supply voltage at this voltage and accuracy will not add unnecessary expense. As described above, the microcontroller 38 in the pipette 10 has an integrated A to D converter that uses U2 as a precision voltage reference with the 1 percent accuracy required. by using a converter card from A to D, the wall power supply 37 can supply a voltage higher than that required to charge the battery and the 4.1 volt load limit can be monitored and controlled by the microcontroller and its A-D converter. In particular, the microcontroller 38 is programmed to simulate an analogous constant voltage charging phase by using the multiple voltage thresholds to determine when to switch to a smaller load current. The microcontroller 38 thus measures the battery (Port ANO) and the wall power supply voltage (Port AN2) with the converter A to D once per second in a power management routine when the engine is not running . The energy management routine programmed in the microprocessor 38 described in Figures 21a, b, and c. As illustrated, measurements are taken while the PWM (wall supply FET) switch is turned off so that the battery voltage is representative of the no-load battery voltage and that the power supply voltage is its regulated value assuming that other pipettes are not connected to it and are being charged. The average increase (due to the internal impedance of the battery) in the battery voltage while charging to IC is approximately 0.15 volts. Thus, the voltage of the first threshold is adjusted to 3.95 volts. when the open circuit voltage is measured at 3.95 volts the average voltage in the battery while charging at the 1C rate is 4.1 volts. at this point the load current decreases when the PWM duty cycle decreases to approximately 20% (this represents the start of the constant charge voltage phase). The charge pulse in time is left constant at 0.36 milliseconds while the period is adjusted to 1.75 milliseconds by changing the deactivation time. To approximate a constant voltage analog charge circuit, which counts for the average in the increase in voltage in the battery due to the average load current, several threshold levels are required. A graph of the battery charge levels for "activation and deactivation" times, in particular, periods of service cycles, currents, charge rates and voltage thresholds are set forth in Figure 19.

The typical charging characteristics for battery 36 over time are described in Figure 20 for each of the 5 levels. As indicated, the threshold for the first change (PWM service cycle level 0 to level 1, ie a period of 1 ms to 1.75 ms) is set at 3,950 volts. The load of level 1 is continued to 4.025 volts before switching to the load of level 2 (3.2 ms period). The load of level 2 continues at 4,075 volts before changing to level 3 (approximately a period of 6 ms) and the load of level 3 and above is of 4,100 volts for changes in the remaining level. These multiple voltage threshold levels prevent the integrated protection circuit of the battery from firing as it approaches the constant voltage charging phase. Level 5 is the smallest and last load level and has a PWM duty cycle of the order of 1.5% (a period of 24 ms). In each of the level changes, a minimum charge time of 2 minutes is used before recreating the duty cycle for voltages of 4,100 volts or less. At and below 4,100 volts there is no basic load time limit in any of the service cycles except for the general load time limit of 240 minutes measured from the start of the rapid charge. If the measurement of the filtered battery voltage goes higher than 4,125 volts then the load service cycle increases one level within 5 seconds, instead of the minimum 2 minute delay that is used as the transition voltages more low (4,025 to 4,100 volts.) If the voltage remains at 4,125 volts or higher after reducing the duty cycle then the service cycle must be reduced again and again (with less than 5 seconds of charging time in each of the service cycles) until the voltage drops again until it is down to 4,125 volts or the loads are completely deactivated (after level 5). Charging continues until either of the following conditions is met, and then it is terminated: • The charge service cycle has been reduced to 1.5% (level 5), and the battery voltage reaches 4.1 VDC. • The time since the start of Quick Charge has reached 240 minutes ("Time - exhausted") • It is detected that another unit in the loading station is charging. The battery will not be charged again until it is discharged to 3.95 VDC or automatically downloaded to this level. The energy management routine described in Figures 21a-c takes the voltage measurements once per second when the engine is not running and the PWM (Wall Supply FET) switch is deactivated. The battery voltage is measured at least 16 times and the calculated average is stored in a location of the "BA" memory in the microprocessor 38. Twenty consecutive measurements are taken, every second, in the wall power supply voltage . A sample and wait circuit in the microcontroller samples and stops the voltage at the beginning of each measurement. Each measurement is taken at 250 microseconds, so 20 consecutive measurements take about 5 milliseconds to complete. The highest of the 20 measurements is stored in the memory and is called "PH" and the lowest reading is stored and called "PL". When a pipette 10 that is charging its battery, is in a shared charging station (not shown) with a shared wall power supply as in Figure 22, then it is guaranteed that the P will be measured every second to be less to 4.6 volts by any other pipette (eg 10 ') in the shared load position considering that the pipette being charged has not progressed beyond level 2 in its constant charge voltage phase. Since the load of level 3 has a charging period of 6 milliseconds, it is possible that PL will not measure less than 4.6 volts in any of the measurement periods of 5 milliseconds. If two or more pipettes are placed in a shared load station, and each one has a battery that needs to be charged, the microprogramming in each of the pipettes together with their PH and PL measurements, will normally allow only one pipette to charge its battery at the same time. The first pipette that is placed in a shared station will begin to charge its battery first. A second pipette and a third pipette (eg 10 ') placed in the station will detect that a unit is already charging due to the fact that it measures a PL value at or below 4.6 volts (and a PH value above 4.9 volts, indicating that the wall power supply is certainly connected). The microprogram is coded so that a pipette does not charge its own batteries if it detects a PL at or below 4.6 volts. When a pipette measures a PL above 4.6 volts it assumes that it is permissible to start charging its battery. After it starts charging, the power management routine will cause you to briefly pause the charge once per second to see the P, PH, and BA again to see if any other unit is charging. If it detects that another unit is charging, it stops charging and waits until PL goes above 4.6 volts before finishing charging. Units review once per second based on the setting of an internal interrupt timer to interrupt once per second. The unit that first determines that it is OK to start charging, will start charging your battery while the other units in the same position will automatically lock to load because it will detect that a unit is charging at the station. It is very unlikely that interruption timers in two separate pipettes in one post will be interrupted at the same time (in a span of 0.25 milliseconds between one and the other). If this is the case, then both units can start charging at the same time.

The unit with the lowest battery voltage will take most of the current from the wall unit until the load reaches a voltage equal to the load of the second unit. While the two battery voltages begin to equalize each other, the current will be divided between the two batteries taking about twice as long to charge as would be the case when only one unit was charging. For this condition to occur, two separate chronometers with separate clocks need to be synchronized in their state and remain synchronized for a longer period, which would be very unlikely (perhaps less than 1 in 10,000); But, it will not cause any harm if this happens. Normally, the shared algorithm described above could be represented in the polite way in which pipettes take turns charging up to a full charge and only loading one at a time. A standby pipette would usually start charging and thus complete the first pipette charge cycle when the first pipette is at level 3 of its constant voltage phase. At this point, the battery of the first pipette is almost fully charged (more than 90% and probably around 95% full charge). if the detection parameters for another load unit were made to be sensitive in order to allow a first unit to finish through level 5 of its constant voltage phase (allowing a 100% full load) the waiting pipette will have to wait for another 30 minutes more. The detection parameters (P and the 5 milliseconds of sampling time) were chosen as a compromise between obtaining a full battery charge and the total time for all the pipettes that are placed in the shared load station to be charged and are ready for use again. A pipette battery that is completely discharged can charge up to more than 90% of its full capacity in about an hour while the last 10% can take another hour. Although the particular preferred embodiments of the present invention have been described in detail herein, it is appreciated that changes and modifications may be made to the illustrated embodiment if departing from the spirit of the invention. Correspondingly, the invention is limited in scope only by the terms in the following claims

Claims (38)

1. CLAIMS 1. An electronic pipette comprising: a linear actuator for driving a plunger lengthwise in a cylinder for sucking and dispensing fluid into and from a pipette tip, where the linear actuator comprises a motor with coils that receive current to electromagnetically drive a rotor for imparting movement along a plunger; and a pipette control circuit that includes a user-controllable microprocessor programmed to generate pulse signals for a motor, the control circuit further comprises a screen electrically connected to the microprocessor, user-operated control keys electrically connected to the microprocessor to generate signals within the microprocessor for the operation mode of the pipette, liquid collection volume, liquid dispensing, pipette operating speed and pipette reset to control the operation of the pipette and the readable alphanumeric screens of the pipette. user on the screen, a memory that has data tables stored there and that are accessible and usable by the microprocessor to control the operations of the pipette, at least one switch operable by the user to trigger the selected pipette operations through of user activation of the control keys, the microprocessor is also programmed to sequentially enter the successive modes selected by the user of the first of the control keys that define a key- "mode" and in each selected mode to control the operation of the pipette so that ( a) a second activation of the mode key or other of the control keys that define an option key that causes the microprocessor to control the screen to display a first operational option for the selected mode only, (b) the second of the control keys defines the "up" key, the activation of this cause that the microprocessor controls the screen to indicate an activation or deactivation of the operative option or an increase in the value of a numerical display associated with the operative option. (c) the third of the control keys defines a key to "lower", whose activation causes the microprocessor to control the screen to indicate an activation or deactivation of the operative option or the decrease of a value for the numeric screen, and ( d) Subsequent activations by the user of a trigger switch drives the motor to drive the plunger in the selected mode augmented by the operating option in an upward direction to pick up liquid at the tip and then in the downward direction to dispense liquid from tip.
2. 2. The pipet of Claim 1 wherein the microprocessor is further programmed so that each of the activations by the user of successive selected modes of the option key causes the microprocessor to control the screen and sequentially display the successive operating options only for the selected mode, each controllable according to letter (b) and (c) of Claim 1.
3. 3. The pipette of Claim 1 wherein the microprocessor is programmed so that the mode key functions as the option key for staggering between successive operating options in response to a sustained initial pressure of the mode key for a period of time greater than a momentary pressure of the mode key followed by successive momentary pressures of the mode key.
4. 4. The pipet of Claim 1 wherein the microprocessor is additionally programmed to control the screen to exit the operating options screen while remaining in the selected mode in response to user activation of the fourth of the control keys by defining a key. of "reset" and / or a subsequent sustained pressure of the mode.
5. 5. The pipet of Claim 1 wherein the microprocessor is programmed so that the fourth of the user-activated control keys defines a key - "reset" (reset).
6. 6. The pipet of Claim 5 wherein the microprocessor is further programmed so that the reset key forces a parameter displayed on the screen to read at zero in response to a sustained initial pressure of the reset key for a longer period of time. time that the momentary pressure of the reset key.
7. 7. The pipet of Claim 5 wherein the microprocessor is further programmed to enter a "blow" operation in response to a momentary activation by the user of the reset key to push the plunger into the cylinder to blow the fluid from the tip of the pipette.
8. The pipet of Claim 5 wherein the microprocessor is further programmed so that each of the successive momentary activations of the user on the reset key causes the microprocessor to control the display to sequentially display a different parameter of a plurality of successive operating parameters. to be edited through user activation of the up or down keys.
9. 9. The pipet of Claim 1 wherein the microprocessor is additionally programmed to count and control the screen to distinctly display the pipette user different screens for successive pipetting cycles of the pipette in a selected mode of pipette operation allowing This way the user to determine the cycle of operation of the pipette for any period of the operation of the pipette.
10. 10. The pipette of Claim 1 with two or more switches operable by the user to trigger the selected operations of the pipette by the activation of the user of the control keys, where the microprocessor is also programmed to enter a selected manual operation mode through user activation of the mode key in a manual mode for (i) control of pipette operation so that (a) the first user-triggered trigger switch defines an "up" trigger activation which causes the microprocessor to control the motor to drive the plunger in an upward direction to pick up the liquid at the tip, and (b) a second trigger switch operated through the user defines a trigger activation "down" which causes the microprocessor to control the motor to drive the plunger in a downward direction to dispense the liquid from the tip, and (ii) the control of the screen to indicate the volume of liquid in the tip.
11. 11. The pipet of Claim 10 wherein the microprocessor is also programmed in a manual mode to, (i) control the operation of the pipette so that while it is in the home position with the plunger in a location ready for start the aspiration or to collect the liquid, the screen shows the maximum volume that can be collected, and (a) the activation of the "raise" key causes the microprocessor to control the screen to indicate a value that increases for a selected maximum volume of liquid to be collected by the tip at the time the "raise" key is activated by the user, and. (b) an activation of the "lower" key causes the microprocessor to control the display to indicate a decrease in the value for the selected maximum volume of the liquid collected by the tip.
12. 12. The pipet of Claim 10 wherein the microprocessor is further programmed to increase the speed to collect and dispense liquid while activating the trigger to raise and the trigger to lower respectively.
13. 13. The pipet of Claim 10 wherein one of the data tables stored in the memory comprises correction factors for a maximum collection volume associated with the tip of the pipette to reduce the liquid volume errors associated with collecting and dispensing liquids by the pipette and where the correction factors are added to the movements to collect and dispense the engine to correct the volume errors.
14. 14. The pipet of Claim 10 wherein the microprocessor is further programmed to count and to control the screen to display distinctly to the user of the pipette the screens for the successive cycles of operation of the pipette in the manual operation mode of the pipette thus allowing the user to determine the cycle of operation of the pipette during any period of operation of the pipette.
15. 15. The pipet of Claim 10 wherein the microprocessor is further programmed to control the motor to enter "blow" where the motor drives the plunger past a starting position to blow out the remaining liquid at the tip after which the plunger reaches the start position
16. 16. The pipet of Claim 15 where the microprocessor is programmed to enter "blown" in response to user activation of one of the control keys or multiple activation of the dispensing trigger.
17. 17. The pipet of Claim 16 where the. The microprocessor is programmed to enter a "blow" operation in response to a momentary user activation of the fourth of the control keys that defines a "reset" key.
18. 18. The Pipet of Claim 17 wherein the microprocessor is further programmed for the reset key to force the volume so that the display reads zero in response to a sustained initial pressure of the reset key for a longer period of time at the of the momentary pressure of the mode when the pipette is not in its initial position, where in addition the upward movement of the plunger "from the position where the screen is at zeroes increases the volume reading and also the downward movement of the plunger from the position in zeros it causes a negative volume to be displayed
19. 19. The pipet of Claim 1 where the microprocessor is also programmed to enter a selected pipette operation mode through user activation of the mode key and mode of pipette to (i) control the operation of the pipette so that (a) the activation of the "up" key causes the microprocessor to r control the screen to indicate an increase in the value for a volume of liquid to be collected by the tip, and (b) the activation of the "lower" key causes the microprocessor to control the screen to indicate a decrease in value for the volume selected from the liquid to be collected by the tip, and (c) the first activation of the user of any of the trigger switches activates the motor to drive the plunger in an upward direction to pick up the selected volume of liquid within the tip, and (d) the second action of the user of any of the trigger switches drives the motor to drive the plunger in the downward direction to dispense the selected volume of liquid from the tip.
20. 20. The pipet of Claim 19 wherein one of the data tables stored in the memory comprises instructions for controlling the pulse signals applied to the linear actuator to control the speed of operation of the motor according to the operating speed settings selected by the motor. the activation of the user of the control keys.
21. 21. The pipet of Claim 19 where another of the data tables stored in the memory comprises the correction factors for the various settings for the selected liquid collection volume. through the activation by the user of the control keys to control and eliminate liquid volume errors associated with collecting and dispensing liquids by the pipette.
22. 22. The pipettor of Claim 19 wherein the microprocessor is programmed to count and to control the screen to distinctly display to the user of the pipette different screens for successive cycles of operation of the pipette in pipette operation mode thereby allowing the user to determine the cycle of operation of the pipette for any period of operation of the pipette.
23. 23. The pipet of Claim 19 wherein the microprocessor is further programmed to (i) pick up the second volume of liquid selected when the plunger reaches the start position in response to activation by the user of one of the trigger switches while the plunger approaches the initial position to dispense the selected volume of liquid and (ii) dispenses and mixes the second selected volume of liquid with a selected volume of liquid.
24. 24. The pipet of Claim 23 wherein the microprocessor is further programmed to repeat (i) and (ii) until none of the trigger switches is activated when the plunger is near the initial position and to propel the motor from there to extend the plunger beyond the initial position to blow out the liquid from the tip.
25. 25. The pipet of Claim 1 wherein the microprocessor is additionally programmed to enter a multiple operation mode selected through user activation of the mode key and in the multiple mode to (i) control the operation of the pipette for that (a) the activation of the up key causes the microprocessor to control the screen to indicate the increase in value for the selected volume of liquid that will be dispensed by the tip, and (b) the activation of the down key causes the microprocessor to control the screen to indicate a decrease in value for the volume of liquid selected to be dispensed by the tip, and (c) a third control key that defines a key. "reset", where the action of this causes the microprocessor to control the screen to indicate a number corresponding to the number of liquid aliquots of the selected volume that the pipette can dispense, where this number is adjustable through the activation of the keys "raise" and "lower" and (d) the first activation of the user of any of the trigger switches drives the motor to drive the plunger in an upward direction to pick up at the tip a volume of liquid corresponding to the liquid volume of the full scale for the pipette, and (e) a second user activation of any of the trigger switches triggers the motor to drive The plunger is in a downward position to dispense the selected volume of liquid from the tip in which it is repeated for each of the second activations of any of the trigger switches until the number of aliquots is dispensed through the pipette.
26. 26. The pipet of Claim 25 wherein one of the data tables stored in the memory comprises instructions for controlling the pulse signals applied to the linear actuator to control the speed of the motor operation in accordance with the selected operating speed settings. through the activation by the user of the control keys.
27. 27. The pipet of Claim 25 wherein another of the data tables stored in the memory comprises the correction factors for the various liquid volume settings selected by the activation of the user of the control keys to control and eliminate the errors of liquid volume associated with collecting and dispensing liquids by the pipette.
28. 28. The pipettor of Claim 25 wherein the microprocessor is further programmed to control the motor to enter a "blow" mode, where the motor drives the plunger past the start position for the plunger to blow out the remaining liquid at the tip, then the plunger reaches the starting position.
29. 29. A manual portable electronic microprocessor-controlled pipette comprising: a hand-held box supporting a linear actuator for driving a plunger lengthwise into a cylinder to aspirate and dispense fluid into and from a tip of the pipette that is extends from the box; the linear actuator is energized by a battery contained in the box or an external power source and comprising a stepped motor with coils that receive current to receive the signals to electromagnetically drive a rotor to impart movement along the piston at speeds controlled through a series of micropasses; and a control circuit for the pipette that includes a user-controllable microprocessor powered by the battery or an external power source and programmed to generate the pulse signals for the stepped motor which are pulse width modulated (PWM) signals having service cycles corresponding to different microstep positions for the stepped motor derived by the microprocessor from a first table of data stored in a memory included in the control circuit and having a repetition pattern derived by the microprocessor from a second table of data stored in the memory to determine the speed of movement of the motor, the control circuit further comprises a screen supported by the box and electrically connected to the microprocessor, control keys operable by the user supported by the box and electrically connected to the microprocessor for generate signals inside the microprocessor for the operation mode of the pipette, the volume for collecting liquid, dispensing liquid, the pipette operating speed and resetting the pipette to control the operation of the pipette and alphanumeric screens readable by the user on the screen, the memory it has data tables that include the first table and the second table stored there and accessible and usable by the microprocessor to control pipette operations, and a user-operated switch supported by the box to trigger selected pipette operations through of the activation by the user of the control roofs.
30. 30. The pipet of Claim 29 wherein the microprocessor is programmed so that the PWM pulse signals have non-overlapping phases where the PWM pulse signals applied to the windings receiving the stepped motor current do not overlap.
31. 31. The pipet of Claim 29 wherein the battery in the external power source develops a supply voltage, and the microprocessor is programmed to respond to the supply voltage in its selection over which of the data tables stored in the memory derives the service cycles of PWM pulse signals.
32. 32. A battery-powered microprocessor-controlled manual portable electronic pipette, comprising: a hand-held case supporting a battery and a linear actuator for driving a plunger lengthwise in a cylinder to aspirate or dispense fluid into and out of a tip of the pipette that extends from the box; the linear actuator is energized by the battery and comprises a motor with windings that receive current to receive impulse signals to electromagnetically drive a rotor to impart movement along the plunger; and a control circuit for the pipette that includes a user-controllable microprocessor energized by the battery and programmed to generate the impulse signals for the motor, the microprocessor is also programmed to (i) enter a power management routine in a periodic basis in order to check the status of the battery charge and a power source to charge the battery that has a current limit equal to or greater than the maximum charging current for the battery, and (ii) open and close a switch between the power source and the battery, the closed switch passes current from the power source and the current limit to the battery to charge the battery while a voltage generated by the power source is below a regulated value, and the microprocessor is programmed to measure the voltage of the power source and determine its highest value (PH) and its lowest value (PL) during a defined time interval while the switch is opened.
33. 33. The pipettor of Claim 32 wherein the microprocessor is further programmed to generate a signal controlled by a pulse width modulation switch to open and close the switch so that the battery is charged with an average current equal to the cycle of service of the pulse width modulation control signal by the current limit of the power source.
34. 34. The pipet of Claim 33 wherein the microprocessor is further programmed to control the service cycle of the control signal of the pulse width modulation switch to a value determined by the state of charge of the battery.
35. 35. The pipet of Claim 32 defining a first pipette in combination with a second pipette as defined by Claim 32 connected to the power source where each of the pipettes while in their energy management routine compares their values measured from PL and PH with the threshold values stored in the microprocessor to determine if they can charge their battery from the power source.
36. 36. The pipet of Claim 35 where the charge to the battery can not be carried out unless PH and PL are greater than the respective threshold values.
37. 37. The pipet of Claim 36 where the battery is a lithium ion battery and the thresholds for PH and PL are greater than 4.6 and 4.9 volts respectively to allow the charging of the battery.
38. 38. The pipet of Claim 37 wherein the time interval for determining PH and P is greater than 1 ms but less than 100 ms.