Automatic Test Tube Transporter And Sample Dispenser Having Solid State Controls

Abstract

An automatically controlled test tube transporter apparatus which advances a test tube rack containing two rows of receptacles for test tubes under a vertically movable aspirating and dispensing tip or nozzle which is adapted to move down into adjacent tubes and aspirate or discharge depending on the test to be performed. The tip is operationally in communication with a twin pipette metering and dispensing apparatus which includes a linearly adjustable eccentric mechanism which drives the pipette pistons with a motion of adjustable sinusoidal amplitude. The apparatus includes a solid state control circuit which includes a binary shift register. The pipettes may be adjusted to either work in parallel or alternating strokes. An automatic tip wiping mechanism, controlled by the operation of the tip, is provided to insure precision in the processing. The apparatus is adapted to be set for continuous operation or for individual test tube processing cycle operation. Empty racks can be advanced without engaging the tip and pump apparatus. The pipetting mechanism may be operated separately without the operation of the transporting mechanism. A malfunction and alarm logic circuit gives a warning in case of certain malfunctions and stops the apparatus.

Description

DESCRIPTION OF THE INVENTION

This invention is directed to an automatically controlled transporter apparatus for sequentially performing aspirating and/or dispensing functions on a plurality of test tube pairs containing liquid samples and reagents. It entails drawing off, through a conduit, a volumetrically metered, freely adjustable, quantity of liquid and for performing further functions on this metered quantity through another conduit.

A major problem in the past in analytical testing of large numbers of sample liquids, such as blood, has been the large amount of time consumed in individually processing each sample-containing tube. For instance, where a tube having a sample liquid therein has to have reagent added thereto in order for certain tests to be performed and analytical conclusions drawn, there are the problems of adding exactly the right amount of reagent, handling the sample tube so as not to spill or splash any sample liquid and the placing of the sample tube in upright position in a rack. In addition, the time consumed by such individual handling results in a serious time delay in hospitals and private analytical laboratories in getting the analysis results back to the physicians or, in the case of non-medical testing, the party requesting the analysis.

Thee same problems occur in performing other types of laboratory analysis. While metering and dispensing apparatus to perform this function are known, they are mainly used in test laboratories, e.g., biochemical and clinical laboratories, and are intended either to deliver a predetermined volume of a liquid to be analyzed (i.e., operating as a metering apparatus), or to deliver successively several metered quantities, all of identical volume, of the same liquid (i.e., operating as a dispensing apparatus), or else to deliver simultaneously both a volumetrically predetermined metered quantity of a liquid to be analyzed and a metered quantity, also volumetrically predetermined but not necessarily of same volume as the liquid to be analyzed, of a diluting liquid or of a reagent (i.e., operating as a diluting apparatus). The use of these apparatuses is becoming widespread as the demand for large volume testing increases. However, the known apparatuses are often of low accuracy, inasmuch as the volumetric quantities they meter lack accuracy and are not readily reproducible, particularly when these volumetric quantities are small.

This defect in the known devices is largely due to the fact that, in these known forms of apparatus, adjustment of the metered quantity is not "digitalized." I.e., adjustment is continuous and such adjustment is often affected by errors in the reading of scales, these being human errors attributable to distraction, inattention or tiredness on the part of the operators. Moreover, the known forms of metering apparatus operate in a rather brutal way. First, an abrupt suction action occurs, then an abrupt stoppage of the suction action and finally an abrupt discharge of the metered quantity of liquid that has been sucked in. This often results in cavitation or breaks in the columns of liquid (hydraulic hammering effects) or in the formation of drops, both being a source of material errors also occurring in manual handling of the samples. The only way known to reduce the extent of the errors with these known forms of metering and dispensing apparatus is by having them handle relatively large quantities of liquid. This, of course, is a major drawback when it is required to carry out a large number of different tests on a liquid from one source since, in order to do this, a corresponding number of samples is usually required of the liquid and this means that quite a sizable starting quantity will be needed. The only way in which this need for sizable starting quantity of the liquid can be avoided is to reduce to the greatest possible extent the volume of each sample.

Another problem in analysis has been the handling, of the sample after it has been added to a reagent and before a separate function is to be performed. I.e., the devices available have not been sophisticated or flexible enough to coordinate several analytical steps on the sample or sample and reagent.

Therefore, it is desirable to minimize all possible causes for inaccuracy in metering. This is particularly important in haematology where it is often desired to carry out a large number of tests without having to draw off large quantities of blood from the patients. One of the most relevant examples is in pediatric haemotology.

According to the present invention, there is provided a solid state controlled apparatus which includes an advancement mechanism which moves the racks under a movable tip or nozzle which is actuated by a grooved cam arrangement which lowers it into first one tube and then the adjacent tube. After aspirating or dispensing the tip is withdrawn and simultaneously wiped clean by a wiper mechanism controlled by the tip. An ejector mechanism which ejects the processed racks is also part of the apparatus.

The apparatus includes a pipette unit having a pair of pumps, each with a suction and forcing piston, pumpable during a suction stroke to draw off a predetermined volume and a switching valve associated with said pump and able cyclically to pass from one condition in which it causes said pump to communicate with one conduit to a second condition in which it causes the pump to communicate with another conduit. The pipette unit also includes a drive mechanism able to cause said valve to pass from one condition to the other and able cyclically to actuate said pump by imparting to the reciprocating movement of the piston a substantially sinusoidal action, said mechanism being adapted so that the suction strokes of the pump occur when the valve is in said one condition and that the forcing strokes of the pump occur when the valve is in said other condition and so that each suction and forcing stroke may be followed by an idling pause during which the valve passes from one condition to another. Also featured is an adjustment means for selectively adjusting the volume of said metered quantity of varying the length of the stroke of the pump piston and display means for displaying to the outside a number indicative of said volume.

The apparatus also has a novel cam and toggle arrangement for controlling the movement of the tip in a vertical direction in and out of adjacent tubes in a test tube rack. The distance the tip moves into each tube is controlled by the duration of the drive motor for the tip. A second and/or third fixed tips may also be used in conjunction with a movable tip to discharge reagents into the back tube in a test tube rack. Also, an auxiliary pipette unit may also be used in conjunction with the pipette unit furnished with the transporter. The auxiliary pipette discharges through one or two fixed tips. The apparatus is designed to be connected to a flame photometer or other auxiliary equipment for direct analysis of the diluted or reacted sample in the rear test tube.

A novel wiper mechanism is provided for wiping the tip as it moves upwardly out of the tube after having either dispensed or aspirated within the tube. A pair of reels, one a supply reel for a wiping tape and the other a take-up reel, are mounted on a slidable tray or drawer which may be pulled out from the apparatus to replace the tape supply and/or take-up reel.

Accordingly, it is an object of this invention to provide an improved sample moving and testing apparatus for use in analyzing sample liquids carried by test tubes mounted in a rack.

It is a further object of this invention to provide an improved dispensing and aspirating tip advance and retraction mechanism.

It is a further object of this invention to provide a novel test tube transporter and sample aspirator and dispensing mechanism for use in conjunction with various tests run on the samples contained in the test tubes.

It is a still further object of this invention to provide an improved tip wiper mechanism for use in a test tube transporter and sample dispensing apparatus.

Another object of this invention is to provide an automatic test tube transporter and sample dispenser apparatus having a novel solid state control system which minimizes operator involvement and maximizes flexibility of the apparatus in performing various analytical functions upon samples carried in test tubes.

Another object of the invention is to provide a novel test tube transporter and sample dispenser apparatus which may operate continuously upon a plurality of test tube samples in parallel rows within a single test tube rack or in a pair of test tube racks or may be manually operated upon each tube or pair of tubes.

It is a further object of this invention to provide a novel test tube sample transporter and dispensing apparatus which may be used in conjunction with auxiliary pipettes or external control units.

It is a still further object of this invention to provide a novel test tube transporter and sample dispenser apparatus having a solid state control system which includes a binary shift register.

These and other objects of this invention will become apparent when reference is had to the following specification and the accompanying drawings in which:

FIG. 1 is a perspective view of the transporter showing the working surface, the control and pipette modules and the movable tip module;

FIG. 2 is a side view of the tip module, partially in section, showing the various interrelationships between the tip moving mechanism and the tip wiper mechanism;

FIGS. 3 and 4 are front views of the tip module with the case removed, showing the tip guide mechanism when the tip is in retracted and down positions, respectively;

FIG. 5 is an exploded view of the cam and cam clutch driving assembly for the tip wiper mechanism;

FIG. 6 is a partial front view of the wiper cam assembly showing the interrelationship between the cam, the cam clutch, the wiper toggle mechanism and the follower;

FIG. 7 is a top view with parts broken away and in section of the tip module shown in FIG. 2;

FIG. 8 is a perspective view of the apparatus similar to FIG. 1, but showing the wiper tray pulled forward and with the pipette and electronic control modules removed and the casing off the tip module;

FIG. 9 is a front view of the supply reel subassembly showing the supply spindle and take-up spindle;

FIG. 10a is a two-dimensional plot of the grooves in the cylindrical tip cam;

FIG. 10b is a cross-section taken along lines 10b--10b of FIG. 10c;

FIG. 10c is a side view of the cylindrical tip cam;

FIG. 11 is a partial planar view showing the teeth in the take-up spindle shown in FIG. 9;

FIG. 12 is a plan view of the wiper tray showing the interrelation of the supply and take-up reels with the supply and take-up spindles;

FIG. 13 is a side view with parts in section of the transmission means for the wiper tape spool;

FIG. 14 is a plan view of the device shown in FIG. 13;

FIG. 15 is a schematic view of the A.C. motor driver circuitry;

FIG. 16 is a schematic view of the driver and breaking circuit typically used in FIG. 15;

FIG. 17 is a schematic view of the pipette logic circuitry;

FIG. 18a is a partial schematic view of the tip motor logic circuitry;

FIG. 18b is a schematic view of the remaining tip motor logic circuitry and has matching leads with FIG. 18a;

FIG. 19 is a schematic view of the shift register and logic circuitry;

FIG. 20 is a schematic view of the advance and start logic circuitry;

FIG. 21 is a schematic view of the lamp driver circuitry;

FIG. 22 is a schematic view of a typical lamp driver circuit used in FIG. 21;

FIG. 23 is a schematic view of the manual switch buffers and logic circuitry;

FIG. 24 is a schematic view of the power-up reset used in the circuitry shown in FIG. 23;

FIG. 25 is a schematic view of the automatic switch buffers and logic circuitry;

FIG. 26 is a schematic view of the malfunction and alarm logic circuitry;

FIG. 27 is a schematic view of the interface circuit used in FIG. 26;

FIG. 28 is a schematic view of a typical timer circuit used in the circuitry shown in FIG. 26;

FIG. 29 is a schematic view of the relay driver circuitry used in FIG. 17;

FIG. 30 is a diagrammatic view of a sampling and dispensing operation;

FIG. 31 is a diagrammatic view of a sampling and dispensing operation using a double bore tip;

FIG. 32 is a cross-sectional view taken along lines 32--32 in FIG. 31;

FIG. 33 is a diagrammatic view showing an alternative sampling and dispensing arrangement.

The apparatus is provided with three modules; the pipette, electronic and tip modules. Controls on the pipette and electronic modules enable an operator to adapt the apparatus to perform many and various analytical operations and functions.

The general operating function of the transporter is determined by positions of an auxiliary pipette switch and an external control switch on the function control panel in the electronic modular unit. Details of the operation may vary according to the operator set-up; for instance, in the manifolding of pipettes. There are four basic switch combinations; both OFF, either one ON, and both ON.

In the basic operation function, i.e., with the auxiliary pipette and external control switches OFF, the function control option instituting operations in the following arrangements:

1. a sample in the front tube row diluted with a sample reagent into the back tube row;

2. a reagent dispensed in each tube row; or

3. one or two reagents dispensed in the back tube row only.

With the auxiliary pipette switch ON and the external control switch OFF, the function control option provides for the use of an auxiliary dispensing pipette in conjunction with the apparatus. Basically, this application entails the preparation of a sample in the front tube row diluted with a first reagent from the transporter pipette and further with second and third reagents from the auxiliary pipette. The transporter pipette will be manifolded in the conventional way through a single or double-bore tip moved by the tip mechanism. The auxiliary pipette uses one or two fixed tips mounted over the tubes in the rear row. Discharge from the pipette tips is adapted to occur simultaneously. The auxiliary pipette may use one or two pumps in the pipette module as required by the particular application. The fixed position auxiliary tip will not touch the wall of the test tube during the operation soc that dispensed volumes should be relatively large to minimize break-off reproducibility errors.

With the auxiliary pipette switch OFF and the external control ON, the function control option provides for applications requiring supply of diluted samples to a readout instrument. An interface unit is then provided to adapt perspective readout instruments to the apparatus. In this operation, the tip module is provided with a twin tip in the tip mechanism. In the alternative, special configurations may be provided for other readout instruments to provide minimum sample carry-over and rapid sample feed to the instrument. In this adaptation, the rear tubes in the rack are omitted and a fixed cup is installed on the transporter. The transporter has a single movable tip for sample and diluent.

With the auxiliary pipette switch ON and the external control switch ON, the operation is similar to the one just described except that it allows for the introduction of one or two additional reagents through the fixed tips in the latter part of the analytical sequence.

This device is an improvement over the apparatus shown and disclosed in copending application Ser. No. 126,782, filed Mar. 22, 1971, entitled AUTOMATIC TEST TUBE TRANSPORTER AND SAMPLE DISPENSER. The improvement over the apparatus described in the copending application consists of the electronic solid state controls and a re-designed tip mechanism. The new tip mechanism facilitates many other analytical operations. The pipette unit used in said copending application is identical with the pipette unit, including the pumps and motion converting means used in this application.

Since the pipette units used in both the apparatus of the copending application and the pipette unit used in the instant device are identical, the contents of said copending application are hereby incorporated by reference in their entirety.

The structure and operation of the pipette module is described on pages 22 to 36 of said copending application. The details, including the drawings, are not included as a part of this case but the unit is identical. Generally, the apparatus is a two-piston sinusoidal stroke metering and dispensing device. A motor drives a motion converting mechanism through a gear box. The motion converting mechanism comprises a cylindrical housing having a hollow cylindrical insert member adapted to be rotated therewithin. Said member is driven by said gear box. There are two parallel juxtapositioned longitudinal slots or slideways in the inner surface of said tubular member. A second insert member is located within said tubular member and locked against rotation therewithin. The second insert member, however, is mounted for longitudinal sliding within said tubular member and its position relative to said first rotatable insert member is adjustable by means of a screw adjustment shaft. The first rotatable insert member has a pair of longitudinally extending slideways which carry one end of a crank mechanism. The other end of the mechanism is fixed within a jeweled bearing within said second nonrotatable insert member. The crank mechanism includes a shaft connecting said insert members with a bearing connected thereto. A slide block rides on the outside of said tubular member and is connected to said bearing. As the first insert member rotates, the crank and crank pin describe an arc and the motion is transmitted to the bearing and slide block on the tubular member housing. Thus, the slide block reciprocates vertically as the first insert member rotates. The slide block is connected to a crank bar, one end of which is fixed to said tubular housing and the other end is fixed to the lower driving portion of the pump piston located within said pipette unit. The motion converting means thereby converts rotary motion into sinusoidal reciprocal motion which is transmitted to the pump pistons at the end of the crank bar.

The pumps which make up part of the pipette unit are positive displacement type pumps having a cylinder, a constant diameter piston, the driving end of which is connected to the stroke bar of the motion converting means and a valve switching mechanism. There are two port bores connected to each pump, there being two pumps, and the valves are adapted either to switch from one port bore to another between each stroke, whether positive or negative, of said crank bar, or to remain in position. The valve itself has a cylindrical member located within the cylinder housing of each pump and has a V-shaped connecting channel which alternately connects each port bore with the interior of said cylinder when the valve is rotatably reciprocated. A priming means is provided on each pump. The piston is easily removed from the pumps of varying volume.

The gear box is adapted to drive a valve switching mechanism which converts the rotary motion of the gears to longitudinal reciprocating motion. At the pumped end of the valve switching mechanism are reciprocally rotatable driving pins. The driving pins may be placed in one of two positions, the first position being a driving position in which the pin is operatively connected to the pump valve whereupon the valve will switch from one port to another and the second being in a position in which the pin is disconnected from the valve and the valve remains in a preselect position, thereby maintaining only one port in connection with the cylinder. The driving gears for the valve switching mechanism have relieved areas thereon whereby after said valves are switched, no motion takes place while the piston is stroked either negatively or positively.

Thus, the pipette pumps can be operated in several fashions, the first being where the valves switch in both pumps between pumping strokes, the second being where neither valve changes ports during the pumping strokes, the third where one valve remains in a predetermined position and the second valve switches between piston strokes. Also the pistons may be stroked in the same direction simultaneously or may, through changing the relative gear positions, be alternately stroked or be simultaneously stroked in opposite directions. Thus, a great variety of dispensing and sampling operations are possible with the pipette unit.

The pipette unit also has counters located thereon which are operatively connected to the main threaded shafts for adjusting the stroke of the pump pistons. These counters are used to indicate to the operator the amount of stroke and consequently, the particular volume of each pump during that operation.

The pipette unit has a RUN switch and a SET switch thereon which, when both are depressed, provide power to the tip and wiper mechanism. The operation of the pipette unit and its components actuates several switches within the electronic solid state control system. The RUN and SET swtiches are shown in FIG. 17, the pipette logic circuitry diagram. Also shown in that diagram are switches 569, 570 and 571. They are, respectively, a pipette limit position switch, a pipette left position limit switch, and a pipette limit right position switch. Also in the drawing is switch 574 which is a pipette limit set position switch. The operation of these contact switches will be described later herein.

TIP MECHANISM

Referring now to FIG. 1, there is shown the transporter apparatus generally designated as 1. It consists of a base unit 2 having a supporting structure 3. A planar surface 4 is located on top of base portion 2 and has an exit surface 5 separated therefrom by base unit projection 6 and dividing bar 46. A pair of other base portion projections 7 and 8 act together with border strips 9 and 10 to provide an alignment guidance for the test tube racks. Member 10 contains a slot 11 therein in which rides rack guide arm 12. Arm 12 is tapered as at 14 and has a relieved area as at 13 by which an operator may grasp the arm to retract it when placing racks into the transporter. The member 10 and arm 12 and its accompanying drive mechanism form the contents of a separate application and is not described in detail in this specification.

The racks such as R are placed on surface 4 and contain adjacent rows of tubes such as T.sub.1 and T.sub.2. Usually, the sample to be tested, whether it be blood, urine, or some other substance, is placed in the row containing tube T.sub.1 and a reagent to be reacted with said sample is placed in the row containing tube T.sub.2.

A raised portion of the transporter, 15, houses a rack-advancement mechanism, not shown in detail but generally similar to the rack-advancement mechanism shown and described in said earlier copending application. The rack-advancement mechanism has teeth, such as 51, which project outwardly through a slot 50 is the housing. The housing also contains a rack sense contact 47 which tells the electronic logic of the transporter when a rack is in place and is ready for processing. Also located alongside the path of rack R in front of the housing is a tube sensing switch, such as 49, which projects through a slot 48 within housing 15, and 49' projecting from the end of bar 46. The sensing switches 49 and 49' are not shown in detail but may be simply a spring-loaded slide switch or a microswitch. A rack-ejector mechanism is also located within housing 15 but is not described in detail. Instead of using flipper arms, as used in said earlier copending application, the mechanism is adapted to drive push rods, 54 and 55, shown in phantom, through cylindrical apertures 52 and 53 in said housing to eject racks along the surface 5 once processing on the tubes contained therein has been completed.

The main console containing cabinet 16 is supported on housing 15 and contains a pipette module unit identical with the one shown and described in said earlier copending application. The unit contains pumps 18 and 19 having windows 20 and 21 cut therein respectively. The windows are for viewing the liquid within the cylinder chambers, the chambers preferably being made of glass or clear plastic. The pumps have ports, such as 20' and 21', located thereon and are used as previously described in this application and described in detail in said earlier copending application. The pistons (not shown) contained within the pumps are connected to stroke bars such as 8' and 9' which, in turn, are connected to motion converting means within the pipette module.

A SET switch 26 and a RUN switch 27 are located on said pipette control panel and are used to set both the pipette module and electronic control module into operation. Control knobs 25 and 26 are used by the operator to set the stroke adjustment or, in other words, the length of said stroke which each pump will incur. Counters 22' and 23' are adjacent the control knobs to indicate to the operator the present setting of the stroke length. Thus, the operator can quickly determine the volumetric capacity of each pump during the processing of the samples.

Located adjacent the pipette module is the tip housing module 28. It consists of a frame 29 having a window 30 therein through which the tip may be viewed or, in the alternative, the panel 30 may be non-transparent.

Located on the other side of the tip module is the electronic control module 32. It has an upper control face 31 which contains the major mode switches. It contains automatic mode switch 39, manual mode switch 40, advance mode switch 41, pipette mode switch 42, reset switch 43 and start switch 44. These switches are shown designated by different numerals on FIG. 23, the manual switch buffer and logic circuitry. Located directly above said switches is a lamp display console 45 which includes the following lamps to indicate the following conditions: open tray; advance jam; tip wiper; eject; pump sequence; tip down front; pipette; tip down back; tip up; advance; automatic; manual; advance and pipette.

Located underneath said major control switches on panel 33 are the auxiliary pipette switch 34 and the external control switch 35. Adjacent said switches on panel 36 are front stroke adjustment knob 38 and back stroke adjustment knob 37. The latter two knobs control the depth to which the transporter tip moves into tubes such as T.sub.1 and T.sub.2.

All three module units are supported on a support member 16'. Located on the underside (not shown) of member 16' is a fixed auxiliary pipette tip member 30'. As previously stated, the tip module unit and the electronic control unit will be described in detail whereas the pipette module unit, being identical with that disclosed in said earlier copending application will not be described nor shown in detail.

Referring now to FIG. 2, there is shown in section, the tip module unit 60 the major components of which are tip holder, guide mechanism, and guide driving means. During the description of the structure and operation of this portion of the apparatus, reference may be had to FIGS. 3, 4, 5, 6, 7, 8, 10a, 10b, and 10c.

A front mounting casting 61 supports most of the major components of the mechanism. It is connected, in any suitable fashion, to a base plate member 62 which, in turn, is connected to a rear plate 63 to form the supporting structure for the entire mechanism. Casting 61 has a plurality of projections 64, 65, and 66 on the rear face thereof. It also has a pair of bores 67 therein each of which receives a bushing 129. Another pair of bores 68 are in the top of said casting and each receives the forwardly extending portion 99 of a tip guide rod. Projection 64 has a bore 69 located therein with counterbored sections 71 and 72. Located within said counterbored areas are bearings 70 and 73. The bearings support a wiper cam shaft 75 therein. One end of said wiper cam shaft has a gear 74 thereon having teeth 74' and a flanged portion 77. A nut 76 secures said gear to the end of said cam shaft 75.

Gear 74 is in operative drive action with a gear 86. Gear 86 has a flange portion thereon and a machine screw 88 secures gear 86 through lock washer 89 to the drive shaft 85. Drive shaft 85 is located within a bore 79 in projection 65. Bore 79 has counterbored areas at the end thereof such as 80 and 81 in which are located journal bearings 82 and 83 which support shaft 85 for rotation. Mounted for rotation with gear 86 on its flange portion 87 is a crank 90. Crank 90 is best seen in FIGS. 3 and 4.

A bore 91 in projection 66 has a pair of journal bearings 92 and 93 therein which support a cylinder cam shaft 94 for rotation therein. On one end of cylinder cam shaft 94 is a washer 98 and a splined section 94'. Splined section 94' carries cylindrical cam 216 thereon for rotation therewith. The opposite end of shaft 94 is threaded as at 96 which receives a nut 97 and washer 95 to lock the shaft in projection 66 against longitudinal movement therein.

The upper end of crank 90 has a circular cam follower 118 mounted thereon by spacer 119 in machine screw 120. Follower 118 is adapted to ride in a longitudinal slot 117 in a cam follower guide member 113'. Cam follower guide member has projecting portions 115 and 116 which together form slot 117. The opposite ends of member 113' are vertically bored as at 114' in FIG. 2 so as to receive a pair of guide rods 111 and 111'. The tops of guide rods 111 and 111' are secured by locking washers or members 112'. They are secured to projecting tab portions such as 110'. Tab portions 110' are extensions of front castings 61.

The lower end of crank 90 (as seen in FIG. 2) has a top dead-center cam 123 secured thereto by machine screw 122. The configuration of cam 123 can be seen in FIGS. 3 and 4. Cam 123 has rounded surfaces such as 124 which are adapted to engage the actuator arm 126 of a microswitch 125. Microswitch 125 is secured to the device in any suitable manner, such as by pins 127.

The guide rods 111 and 111' support a cross slide (or cross-head) having opposed sections 113 and 113' for sliding movement thereon. As seen in FIG. 3, the cross slides have projecting transverse portions 115 and 116 connecting the two together. The guide bars 99' and 99" project outwardly from the top of casting 61 and are angled downwardly. They support a tip holder 100 for up and down sliding movement thereon. Tip holder 100 has a pair of bores, such as 101, as shown in FIG. 2 which receive the guide bars. Tip holder 100 has an aperture (not shown) for receiving the tip T, as shown in FIG. 3. A latch member 104 is supported on a shaft 102 and is biased inwardly by spring 103 to hold the tip T in position. The tip holder also has bores 106 and 106' for receiving a pair of stabilizing rods 105 and 105'. Stabilizing rods are received, at their end portions, in projection member 116 of the cross slide. As shown in FIG. 3, the tip T has a reduced diameter portion T' which is the maximum portion which is wiped.

The ends of guide bars 99' and 99" are received in a cam block 254 as shown in FIG. 7. Cam block 254 has a pair of tab portions, such as 255, which are split as at 256 to receive a machine screw 257 for locking the cam block 254 in position on bars 99' and 99". The upper portion of casting 61 is cut away as at 258 to accommodate longitudinal movement of cam block 254. Located within cam block 254 is a "toggle" mechanism comprising a snap-action lever 266 and a pair of guide cylinders 259 and 260. Located within member 254 between the cylinders is a fixed cylinder 268 having a transverse bore receiving for rotative movement therein a pin member 267 which is secured to lever 266. The upper portion of cylinder 268 is slotted as at 272 to allow lever 266 to reciprocally rotate therein. Located within cylinder 268 is a compression spring 269 which urges a ball 270 upwardly against a downwardly directed pointed projection or tab 271 on lever 266 which causes the lever 266 to snap from one position to the other when the lever 266 is moved clockwise from the position shown in FIG. 2 till the point of 271 passes over to the other side of ball 270. Since both cylinders 259 and 260 are identical, only one will be described. Guide cylinder 259 has a plunger 262 located therein with the upper portion cut away as at 261. The upper portion of 262 supports a pin 265 which is received within a notch on the end of lever 266. The other end of lever 266 has an identical notch. A cam follower 263 is secured to plunger 262 by means of a machine screw 264. Cam follower 263 is adapted to ride in grooves such as 240 in cylindrical cam 216. Cylindrical cam 216 has the hub portion 218 which extends inwardly therein to cover the splined portion 94' of shaft 94. The interior of cam 216 is cut away as at 217 to accommodate projection 66 on casting 61.

Referring now to FIGS. 10a, 10b, and 10c, the cam 216 will be described. FIG. 10a shows a development of the grooves within the cam. In other words, FIG. 10a is representative of the circumference of cam 216 in a two-dimensional plane. The cam contains two grooves, namely groove 246 and groove 248, which have side walls 240 and 247, respectively. The grooves are essentially linear and have rounded terminal portions 241 and 250, respectively. Groove 248 has a curved wall 242 at the opposite end thereof and has a portion which tapers upwardly as at 243 so as to provide a more shallow groove. The tapered portion 243 terminates at 244. Groove 248 has a curved wall section 251 which forms a portion of an upwardly tapered groove portion 252 which terminates at 253. The cam is shown in side view in FIG. 10c and the view shows that groove 240 is initially deep and then rises as at 243 to planar section 244. FIG. 10b shows a cross-sectional view of the cam taken along lines 10b-10b of FIG. 10c and shows the general cross-sectional configuration of the grooves at the tapered or upwardly slanted groove portions. As shown in FIG. 10c, the cam has a gear 249 mounted on one end portion thereof, In the alternative, referring back to FIG. 2, a gear 220 may be provided on the end of splined shaft 94' which fits within a bore 219 in cam 216. In either construction, the gear is adapted to mesh with a gear 221 which is operatively connected to drive shaft 85. Gear 221 has a flange portion 222 with a slot 223 therein. An extension of drive shaft 85 contains a roll pin 224 which engages within slot 223 to lock the gear and drive shaft against relative rotation. Gear 221 is connected to a coupling member 225 which in turn is connected to the main drive shaft 226 which projects through an aperture 227 in rear plate 63.

A machine screw 231 mounts a camming plate 230 to rear plate 63. Cam plate 230, although not shown in front view configuration, is a generally U-shaped member having two extending arm portions such as 229. Mounted on gear 221 for rotation therewith is an actuator bar 228. As gear 221 rotates, actuator bar 228 describes an arc which eventually forces it to abut one of the depending portions, such as 229, of member 230. Such an action forces member 230 to rotate on screw 231 and, as shown in FIG. 7, member 230 has a camming surface on one upper corner thereof such as 236. The camming surface 236 is adapted to engage a microswitch roller 235 which is supported between arms such as 234 of a switch actuator 233. The switch actuator 233 extends from a microswitch 232 and when actuated gives enabling signals to the solid state control logic.

Referring again to FIG. 7, the member 230 is shown to have a flange portion 236 with a semicircular recess 239' therein. Rear plate 63 has a bore therein which supports an insert member 237. Insert member 237 has a bore therein which supports a helical compression spring 237'. Spring 237' biases a ball 238 into engagement with the aperture 239' in the rear of member 230. The compression spring and ball maintain member 230 in actuated position until the actuator bar 228 rotates around in a reverse direction and engages the other leg from the one previously engaged. In other words, this prevents the member 230 from assuming normal position before the actuator bar has again made contact. Thus, it is seen that the member 230 has two positions.

Referring again to FIG. 2, the wiper cam shaft 75 is connected via an extension 78 to an extension portion 170. Mounted on shaft extension portion 170 is the cam and cam clutch assembly for operating the wiping mechanism.

TIP WIPER ASSEMBLY

Referring now to FIG. 8, there is shown the tip wiper bars and the wiping tape assembly tray. The wiping assembly is controlled by the cam and cam clutch wiping assembly 140. Assembly 140 is shown in detail in FIGS. 5 and 6. It consists of a cam member 145 having a large-diameter peripheral camming surface 141 and a small-diameter camming surface 146. The cam surfaces are merged smoothly as at 147 and 148. The cam is preferably made of nylon and has a projecting cam portion 151 having a rounded surface at one end thereof the center of which is recessed as at 152. Extending downwardly away from portion 151 is portion 156. Portion 156 is a camming surface having a recessed center area 157 and a main body section 155. The cam 145 itself is relieved as at 149. A bore 154 is provided for locking onto the cam shaft and a keyway 153 is provided to lock the cam against rotation relative to the cam shaft. The angle X is one-half of the distance of camming surface 146 and is preferably about 770.degree.. Member 142 and member 144 are clutch washers having square apertures 158 and 166, respectively, therein. Received between the cam washers is the cam clutch plate 143. The clutch plate 143 is generally circular having a reduced-thickness portion 159 and a central bore 160' therein. A pair of ears 161 and 162 are located 180.degree. apart on the cam plate. A notch 165' is located approximately midway between the ears and a second notch consisting of deep notches 163 and 164 and projecting tab portion 165 is located 180' opposite from notch 165'. Angle Y, shown in FIG. 5, is preferably approximately 38'.

Referring now to FIG. 6, the cam assembly is shown assembled together with its "toggle" or snap-action mechanism and wiper bars. The Snap-action assembly for the wiper mechanism is shown designated generally as 180. The mechanism is shown in side view in FIG. 2. Snap-action assembly 180 has a pair of guide cylinders 207 and 184. Since both the guide cylinders are identical, only one will be described in detail. Cylinder 184 is maintained in place by retaining rings 188 and 184'. Mounted for vertical sliding movement within cylinder 184 is insert member 187. Insert member 187 has a slot 189 and a pin 190 extends transversely through the slot into the adjacent portions of 187. Member 187 is relieved as at 191 to receive a helical compression spring 192. A vertical slot 195 is cut in the wall of cylinder 187 and a plunger 193, having a pin 194, is adapted to ride within aperture 191 of member 187. Pin 194 rides within slot 195 and defines the limit of travel of plunger 193. Cylinder 184 is mounted in an aperture 181 of base plate 62.

Mounted between cylinders 184 and 207 is a cylinder 196. Maintaining rings, such as 196', maintain 196 in place on plate member 62. Cylinder 196 has an aperture 197 therein which receives a helical spring 198 which, in turn, biases a ball bearing member 199 upwardly. Cylinder 196 is relieved at its upper extremity to define a notch having a pin 201 extending thereacross into the adjacent walls or prongs of 196. A snap-section lever 202 is mounted for reciprocal pivotal movement on pin 201. A pointed projecting tab 209 is adapted to engage either side of ball 199 and thus produce a snap-action as lever 202 is reciprocated. The ends of lever 202 have notches such as 203 which engage pins 190 mounted on the relieved areas of the insert members 187. A pair of tab portions such as 204 project upwardly from the top surface of lever 202 and have pins such as 206 to secure rollers 205 and 208 in place. Rollers 205 and 208 are adapted to engage camming portion 156 of cam 145.

Plunger pin 193 is adapted to ride on a twist disc 377 and engage in a slot 380 thereon. The operation of the twist disc will be described later herein.

Referring now to FIG. 2, there is shown beneath cam assembly 140 a cam follower barrel 210. The barrel is preferably made of plastic and has an aperture 212 therein. Aperture 212 receives a helical spring and a follower member 214. Follower member 214 has two longitudinally spaced and parallel extending arms 215 and 216. Arm 216 is adapted to ride in a notched area 214 of follower barrel 210. Member 215 is adapted to ride on the lower surface of tab portion 165 of clutch plate 143. At either limit of its travel, it snaps into notches 163 or 164, depending on the direction of rotation.

In projection 65 of casting 61 is a plate follower 167. Plate follower 167 is engaged by the top of camming portion 151 and has a stud 171 adapted to engage in notch 165' of clutch plate 143. A pin 168 (FIG. 6) extends from the opposite side of plate follower 167 into an aperture 169 in projection 65. A helical spring 170 maintains the plate follower in a downwardly biased condition, thereby allowing the stud 171 to snap into notch 165'.

Ears 161 and 162 on clutch plate 143 are adapted to engage a pair of rollers 177 and 177' which control the operation of the wipers. Referring to FIG. 6, roller 177' is shown attached by pin 176' to wiper crank 172'. Wiper crank 172' has an aperture 173' therein which receives one end of wiper bar 129'. The end of wiper crank 172' is split to provide grapsing portions such as 174' and has apertures therein to allow for a machine screw 175' and nut 176' to securely fasten the wiper crank to the wiper bar.

Wiper bars 131 and 131' are shown extending from the main portion of the apparatus outwardly in FIGS. 2 and 7. They have a bent portion such as 130' and a flattened end potrion such as 132 and 132'. The end of each guide rod 99' and 99" has a pair of holes bored therein, on parallel axes. The holes receive rods 133 and 134 which are attached at one end to support pads 136 and 136'. Mounted on support pads 136 and 136' are wiper pads 137 and 137' preferably made of sponge rubber or like material. FIG. 7 shows the plan view configuration of the wiper pads. A helical spring, such as 135, is mounted on rod 133 and a flange on the end of rod 133 keeps the spring 135 in place. The flattened portions 132 and 132' of the wiper bars are adapted to engage the ends of rods 133 and 133' and force them inwardly against the action of compression springs 135 and 135'. The wipers are adapted to wipe the tip as it is withdrawn upwardly through slot 367 in wiper tray 352, shown in FIG. 12.

Wiper tray 352 is shown in FIG. 12 and consists of a flattened planar portion 354 cut away as at 368 and provided with a border strip 353. As shown in FIG. 8, the wiper tray is supported within a bracket member 301 having top surfaces 302 and 303. A plurality of mounting holes such as 302' provide for mounting the pipette and solid state control logic modules on portions 302 and 303. Bracket member 301 has a depending portion 304 which allows for operation of the wiper bars 131. The wiper tray 352 is attached to the brackets by slide blocks 355 and 355'. The slide blocks are mounted to the bottom sides of portions 302 and 303 by suitable fastening means, such as 356. Rod anchor blocks, such as 358, 358', 359 and 359' support tray guide rods 357 and 357' by which are received slide blocks 355 and 355'. Therefore the wiper tray is mounted for sliding movement out of bracket 301. A pair of biased snap fasteners (not shown) are used to lock the wiper tray within bracket member 301 against inadvertent displacement. The pull exercised by an operator of the apparatus is sufficient to overcome these snap locks.

The wiper tray, as shown in FIG. 12, is seen to have a take-up reel 361 mounted for rotation about pin 361' and a supply reel 360 mounted for rotation about pin 360'. The wiper tape W is trained around pulley 362 mounted for rotation on 364 and then around wiper spool 366 and around pullyey 363 mounted for rotation on pin 365 and eventually to the take-up reel 361. As shown in FIG. 12, the tape travels in opposite directions on either side of slot 367 through which the tip T moves. The slot 367 is elongated to provide for the tip moving up and down in two positions to enter test tubes in both rows of a rack tray. Also shown in FIG. 12 is phantom, are the positions of the wiper pads 137 and 137'.

Referring now to FIG. 9, there is shown the bracket 301 having raised portions 302 and 303 and depressed portion 304. Depending from portion 302 is bracket 305 which rotatably supports on pivot pin 308 a torque arm 309. Screw 310 maintains the components in a predetermined relationship. Flange portions 306 and 307 support between them a roller (not shown) around which is wound one end of a negator spring 310. A screw 311 maintains the roller and negator spring in place. The negator spring is attached at its other end by screw 311 to torque arm 309. Torque arm 309 carries a mounting 316 attached to which is a slip clutch 317. A machine screw 312 secures an L-shaped bracket 313 to the bottom of torque arm 309. A clutch spring anchor 314 is mounted on the bottom portion of bracket 313 BY MACHINE SCREW 315. Connected to slip clutch 317 and resting upon clutch spring anchor 314 is a torquing spring 319, one end of which is received in an aperture in pin member 318 which depends from slip clutch 317. A shaft 320 extends upwardly and is mounted in any suitable fashion to a flange 322 of supply spindle 321. Supply spindle 321 has a groove around the periphery thereof which receives a resilient or elastic band 323. Supply spindle 321 is adapted to engage the tape which is wound on supply reel 360, as shown in FIG. 12. Supply spindle 321 is biased inwardly to ride against the supply of wiper tape W on reel 360 by negator spring 310.

An anchor block 324 depends from the underside of portion 303 and mounts a torque arm 325 for rotation about a pivot pin 329. A machine screw 330 maintains the components in assembled relationship. A pair of flange members 326 and 327 support a roller (not shown) therebetween, around which is wound a negator spring 328. A screw 331 maintains the roller and negator spring between flanges 326 and 327. The other end of negator spring 328 is fastened to the opposite end of the torque arm by screw 329. Mounted on the lower portion of torque arm 325 is a motor bracket 332. Machine screws 333 are used to secure motor bracket 332 to the torque arm. A motor 335 is secured to the lower portion of bracket 332, which is C-shaped in configuration, by machine screws 336. The screws 336 secure the motor to the lower portion 334 of the bracket. A shaft 337 extending from motor 335 is connected to a flexible coupling 338 and a take-up clutch 339.

Shaft 340 is connected to a flange 342 of a take-up spindle 342. The periphery of take-up spindle 342 has a raised scalloped center portion 342'(FIG. 9) such as shown in FIG. 11. It consists of a plurality of arcs which intersect in points such as 345. The arcs are designated as 343. The outline of the remainder of the circumference of spindle 342 is shown in phantom in FIG. 11 and designated as 344. Thus, it is seen that the points 345 project outwardly beyond the peripheray of the remainder of the spindle and are adapted to puncture and grasp the wiper tape W on the take-up reel.

The supply spindle 323 and the take-up spindle 342 are shown in position in FIG. 12. Arm 346 is adapted to engage a microswitch 347 having an actuator arm 350 and contact roller 351. The microswitch 347 is secured to the base of bracket 301 by studs 348. It can be seen from FIG. 12 that the spindles engage the wiper tape W on the reels.

Referring now to FIGS. 2, 13 and 14, there is shown mechanism for controlling the advancement of the wiper tape itself. The mechanism comprises a twist disc 377 having a sloping cam surface 379 which terminates in a peripheral slot 380. The cam surface 379 commences at 381 and is approximately 180.degree. in arcuate length. The twist disc 377 has a hub portion 378 which is adapted to rotate on shaft 375. Plunger 193 of escape cylinder 194 is adapted to ride on cam surface 379 until it drops down into peripheral slot 380. A supporting frame 370 is mounted beneath the twist disc and has a projecting portion 372 having a hollow passageway therein 372' and bearings 374 and 373 mounted at either end of said passageway in countersunk portions. A shaft 375 drives twist disc 377 which rides on bearing 376. Frame 370 has supporting structure (shown in phantom in FIG. 13), such as brackets 371, machine screws 369, etc. On the opposite end of shaft 375 is mounted a gear 383 which is held in place through a lock pin 382 held in aligned passageways in the shaft 375 and the gear itself. Gear 383 turns on bearing surface 384 and engages gear 385 which is on a second shaft 387. This shaft is driven by the wiper 366 rotated by the wiper tape W. Gear 385 is held on shaft 387 through lock pin 386. A projection 388 of frame 370 contains a hollow passageway 389 and journal bearings 390 and 391. Gear 385 rides on bearing surface 393. The upper end of shaft 387 is bored as at 393 and has a passageway receiving a pin 394. Mounted atop this upper end of shaft 387 is member 395 having a passageway 396 therein which receives the upper extremity of shaft 387 and a slotted area 397 which allows pin 394 to move within member 395. A helical compression spring 398 is mounted within passage 393 and is anchored at its upper end in a small passage in member 395. Thus, member 395 rotates with, but is longitudinally biased on, shaft 387 as indicated by the arrow in FIG. 13.

A projection 399 on the top of member 395 engages in an aperture 400 in the bottom of wiper spool 366. Wiper spool 366 is mounted in a journal bearing 401 in tray 354 and has a circular rotating base portion 402. Four projecting tab portions 404 extend upwardly from portion 402. Each tab 404 has a generally vertical surface with upper and lower tab portions, such as 403, and a puncture point 405 which punctures the wiper tape W to meter the tape through the supply reels and take-up reels. As shown in FIG. 14, frame 370 has mounting holes such as 370' and is generally rectangular with one edge rounded. The top of member 395 is shown in FIG. 14 and the projection 399 is shown as equal to the diameter of the upper member of circular member 395. The member is adapted to turn in aperture 406 in the frame member. Thus, it is seen that when plunger pin 193 is engaged in slot 380, it maintains the wiper spool 366 against any further movement. Wiper spool 366 automatically engages and disengages member 395 when the wiper tray 352, FIG. 12 is moved in or out.

Referring again to FIG. 2, it is seen that the cam and cams 141 and 143 clutch mechanism 140 is held in engaging position by washer 167' and a compression spring 171' which acts on washer 168' and surrounds shaft portion 169.

TIP AND TIP WIPER OPERATION

The tip motor (not shown) is bidirectional. The time that it turns in either direction, thus the tip depth stroke, is controlled by a dial setting on knob 38 on panel 36. Before the motor will reverse its direction, however, it must rotate at least 56 1/2.degree.. This minumum angular displacement is effected by actuator bar 228 on gear 221 (FIG. 2) striking either lobe, such as 229, on member 230 which in turn actuates switch 232 (FIG. 7). The minimum angle of displacement insures that the snap action of cylinders 261 and 261' will be completed and that one of the cam followers, such as 263, will fall in the back or front cam groove. It is apparent from FIGS. 10a, 10b, and 10c, that the arcuate portion of each groove (as viewed in FIG. 10a) on the cylindrical cam 216 surfaces extends through 90.degree. rotation from one side to the center. This represents 56 1/2.degree. rotation of the motor when the gear ratio of the drive and driven gear is 2.0:1.25 as is preferable.

Once the cam follower has dropped in a groove, the motor may continue to turn for any angular displacement up to 180.degree. maximum.

An angular displacement greater that 56 1/2.degree. is timed. At the end of a set time period, the tip stops and pauses until the pipette operation is completed which usually takes around 3 seconds. At that time, the motor rotational direction is reversed and the tip T is raised in a straight line until it reaches top dead center. Past top dead center position the cam follower riding in the groove in cam 216 is advanced sinusoidally forward, or backward, depending on the groove the follower is in, until a toggling action takes place, which consists of one follower riding out of the surfacing groove and the second follower dropping into the second groove. Naturally, all this action is transmitted to guide bars 99' and 99" on which the top holder 100 slides. At the same time, the motor turns crank 90 which, via cam follower 118, moves the cross slide subassembly vertically. As can be seen from FIGS. 1 through 4, rods 105 and 105' ride in holes in tip holder 100. In other words, the tip holder 100 is moved horizontally by the rods 105 and 105' and vertically by the rods on the cross slide sybassembly.

While the tip is being moved, the cam shaft 75 is being rotated in either direction via gears 86 and 74. When the crank 90 is at top dead center, the top lobe 151 on cam 145 (FIG. 5) holds up follower plate 167, thus disengaging the pin 171 on the plate follower and slot 165' in the cam plate 143. Consequently, the cam 145 rotates with gear 74 when the drive shaft 85 and motor rotate. The cam 145 turns until stopped by the top pin 215 in follower 214. Initially, the pin 215 rests against one of the walls of slots 163 or 165 of the 38.degree. arc cutout. If shaft 75 rotates more than approximately 103.degree., the radius surface 141 on cam 145 gives way to the smaller radial surface 146. This allows the follower 214 to move vertically which raises pin 215 into either slot 163 or 164. As shaft 75 continues to rotate to the angular displacement dictated by the time setting on the motor, the pin 215 remains in the upper portion of either slot. The pin goes into the slot only if more than 103.degree. shaft rotation has occurred. Presuming the motor, hence shaft 75, reverses at some displacement greater than 103.degree., then the pin 215 will remain in its slot until the larger cam surface 141 pushes it out. At that time, the friction plates 142 and 144 turn the cam 145 in the direction of shaft rotation. This results in the dropping of follower plate 167 and dropping of pin 171 into notch 165' of cam plate 143 and locking the cam plate with the ears horizontal. The ears 161 and 162 on cam plate 143 push out the rollers 177 and 177' which in turn rotate the wiper bars 131 and 131' which swing the wiper pads 137 against the tip and 137'. This action wipes the tip T. At near top dead center tip-slide 100, the top lobe 151 on cam 145 raises follower plate 167 and hence pin 171. Cam plate 143 is rotated and the ears 161 and 162 move out of the horizontal position causing the wiper pads 137 and 137' to separate. All the activity just described results in the tip being wiped only as it is raised out of a tube and only for a maximum distance of approximately 1.8 inches. This is the distance from the wipe start to the end of the tip. A shorter distance is wiped if the tip depth setting is less.

The oscillation of cam 145 causes the lever 202 to snap alternately into its positions. Each time an this occurs, one of the plunger pins 193 (in 207 or 184) is lifted out of slot 380 in twist disc 377, and the other descends to ride on top of the ungrooved or unslotted portion of the disc. This action frees the disc to rotate 180.degree. before the riding pin 193 drops into the slot and locks the disc. The disc has a constant torque on it due to take-up tension on the wiper tape being transmitted via the wiper spool 366 and the transmission assembly 180. This snap-action of lever 202 occurs shortly after the tip T passes top dead center. Therefore, the tape moves as the tip is entering the tube. The tape has advanced before the tip is retracted.

Referring now to FIGS. 8, 9 and 12, a full supply reel is placed on pin 360' and the wiper tape is routed as shown in FIG. 12. When the tray is pushed in, the spring loaded clutch assembly shown in FIG. 9 tends to take the slack out of the tape on the supply side of wiper spool 366 and the motor driven clutch 339 (FIG. 9) starts up to take the slack out of the take-up side of the wiper spool. The motor driven clutch 339 runs constantly at approximately 2 revolutions per minute. Both clutches 317 and 339 slip at a constant torque. Therefore, the tension on each side of the wiper spool 366 is always constant. The wiper spool 366 has four needles 405 press-fit with bushings which extend beyond the surface of lands as 404. During a running operation, there is approximately 3 ounces of tape tension in the supply side and 8 ounces of tension on the take-up side of the spool. Negator springs 310 and 328 are located and sized so that the spindles 321 and 342 exert a constant radial force on reels 360 and 361 at all tape diameters.

The tray 354 cannot be opened except when the tip is at top dead center. In this position, the tip is up and the wiper pads 137 and 137' are spread to the maximum position. This allows the wiper spool 366 to come out between the wiper pads and the tip assembly housing. Once the tray 354 is in place, the transporter can be started. As previously mentioned, the disc 377 is free to rotate 180.degree. every time the tip T passes top dead center. Since there is a tension differential between the supply and take-up sides of the wiper spool, the tape advances until the disc is locked again. The tape rolling diameter of the wiper spool 366 and the spools' relative distance from the two pad wiper stations provides for the tape to wipe the tip at each retraction but never twice on the same spot on the tape. Also, the wetted part of the tape goes around the wiper spool 366 between lands 404 so that the wiper spool is not contaminated.

ELECTRONIC CONTROLS

The electronic controls are shown in FIGS. 15-29. The overall systems are contained in FIGS. 15, 17, 18, 19, 20, 21, 23, 25 and 26. Sample circuitry is shown in FIGS. 16, 22, 24, 27, 28 and 29.

FIG. 15 shows the A.C. motor driver circuit; FIG. 17 is the pipette logic circuitry; FIG. 18 is the tip motor logic circuitry; FIG. 19 is the shift register and logic circuitry; FIG. 20 is the advance and start logic circuitry; FIG. 21 is the lamp driver circuitry; FIG. 23 shows the manual switch buffers and logic circuitry; FIG. 25 shows the automatic switch buffers and logic circuitry; and FIG. 26 shows the malfunction and alarm logic circuitry. The input and output leads of the aforementioned circuits shown on the figures just enumerated do not match up from figure drawing to figure drawing but are described herein. In other words, an output lead on FIG. 25 is described as connected to an input lead on FIG. 15, for instance. FIG. 18, the tip motor logic circuitry, consists of two sheets and has been designated FIGS. 18A and 18B. The latter two drawings have aligned leads which match up when the drawing sheets are placed together.

The remaining figures show circuitry which is representative of circuits which are shown as boxes on the aforementioned figures. FIG. 16 is the driver and braking circuit; FIG. 22 shows the driver circuitry; FIG. 24 is the power-up reset circuitry; FIG. 29 is the relay timer circuitry; FIG. 27 is the interface circuitry; and FIG. 28 is the timer circuitry.

The control system has six operator-controlled switches which are shown in FIG. 1 and designated as 39-44. They are the Automatic Mode Switch, the Manual Mode Switch, the Advance Mode Switch, the Pipette Mode switch, the Reset Switch and the Start Switch. To provide power to the electronic system, either the Run or Set switches have to be activated on the pipette console. These switches are shown in FIG. 1 as 26 and 27. Activation of these switches places the pipettes in a prime sequence and provides power to the electronic control system. Other switches which are activated by the apparatus itself include the Advancement Switch, Paper Reel Supply Switch, the Tray Switch, the Advance Motor Cam Switch, the Ejection Motor Cam Switch, the Rack Limit Switch, the Rack Sensing Switch, the Tube Sensing Front Switch, the Tube Sensing Back Switch, the tip Up Sensor Switch, and the tip "Toggle" Switch. Additional controls are provided by a Rear Stroke Adjustment, a Front Stroke Adjustment, an External Select Switch, and an External Potentiometer, and an Auxiliary Pipette Select Switch.

Referring now to FIG. 15, the A.C. motor driver circuitry diagram, it is seen that the circuitry consists of a group of small individual circuits for controlling the motors. A signal enters the advance motor circuit through terminal 511 and is an advance motor driver signal from terminal 875 on FIG. 20. The signal proceeds through the A.C. driver 509 and braking circuit 510 and on to the advance motor 501 which has a capacitance 507 and is connected to the A. C. voltage at 508. A tip motor driver signal enters at terminal 517 and originates in the tip motor logic circuitry, FIG. 18, at terminal 730. The signal continues on through A. C. driver 515 and braking circuit 516. The signal then proceeds through a tip reversing relay switch 514 to tip motor 502 which has a capacitance 512 and is connected to the A. C. voltage at 513.

A tip reverse relay signal enters at terminal 521 and originates in the tip motor logic circuitry, FIG. 18, at terminal 746. The signal continues on to reversing relay 518, which is used to reverse the tip motor. Terminal 520 is connected to the logic voltage. The component designated at 519 is a silicon rectifier. A pipette motor driver signal enters at terminal 526 and orginates in the pipette logic circuitry, FIG. 17, at termainl 638. The signal proceeds through A. C. driver 524 and braking circuit 525 and then on to pipette motor 503 which has a capacitance at 522 and is connected to the A.C. voltage at 523.

An ejection motor driver signal enters at terminal 530 and originates in the automatic switch buffer and logic circuitry, FIG. 25, at terminal 1091. The signal proceeds through A. C. driver 529 to the ejection motor 504. Motor 504 has a capacitance 527 and is connected to the A. C. voltage 528. A tray feed bar motor driver signal enters at terminal 534 and originates in the advance and start logic circuitry, FIG. 20, at terminal 878. The signal proceeds through A. C. driver 533 and on to tray feed bar motor 505 which has capacitance 531 and is connected to the A. C. voltage at 532.

A buzzer driver signal enters at terminal 538 and originates in the malfunction and alarm logic circuitry, FIG. 26, at terminal 1172. The signal proceeds through A. C. driver 537 to buzzer 536 which is connected to the A. C. voltage at 535. A reel motor driver signal enters at terminal 542 and originates in the malfunction and alarm circuitry, FIG. 26, at terminal 1185. This signal passes through A. C. driver 541 to reel motor 506. Motor 506 is connected to the A. C. voltage at 540 and has a capacitance 539.

FIG. 16 shows a representative A. C. driver and braking circuit. The input signal enters the circuit at terminal 549 and passes through resistor 548. The signal is then modified by silicon transistors 545 and 547 along with resistors 546, 550, 554 and 555. The signal then passes through Triac 544 and then proceeds out at terminal 563. Resistor 556, 558 and 559 and silicon rectifiers 557 and 561 and capacitors 560 and 562 comprise the braking circuit. The entire circuit is shown designated as 566. Terminals 551 and 565 are ground terminals. Terminal 552 and 553 are logic voltage connections. Terminal 564 is an A. C. voltage connection. The various arrows shown in the lead lines are merely quick-discconnect points so that the various components, such as the motors, can be easily removed from the system. Obviously, the capacitance for each of the motors, 501 thorugh 505, may vary and have a different value.

Referring now to FIG. 17, there is shown the pipette logic circuitry. The circuitry contains a plurality of switches which are located in the transporter pipette and are enclosed within the dotted line box 568. The entire circuit is designated as 567. Within box 568 are manually operated switches Run and Set, 572 and 573, respectively. These buttons or switches are depressed to initiate A. C. power into the transporter. When both the Set and Run switches are depressed, the pumps within the pipette unit are in a prime condition. Also located within the transporter are pipette limit switches 570 and 571, switch 571 being for the left position and switch 570 being for the right position. As shown in FIG. 17, these contacts are normally closed. Also located within the pipette is a pipette limit set position switch 574, normally with closed contacts, and a pipette limit right position switch 569 which is located on the double cam within the pipette unit itself. As shown in the circuit, switch 569 is grounded as at 569'.

Switch 569 has leads connected to a flip-flop acting as a switch buffer and consisting of NAND gates 576, 580, capacitance 581 and resistors 577, 578 and logic voltage 579. The output of the gates is passed through terminal 632 to terminal 836 in FIG. 20, the advance and start logic circuitry.

The signal made by either contact 570, 571, or 574 or switches 572 and 573 passes through an R-C filter containing resistors 582, 584' and capacitance 584 which is grounded at 585. Resistor 582 is grounded as at 583. The signal then passes through silicon rectifier 586 and through a SCHMITT trigger consisting of NAND gates 587 and 589 and resistors 588 together with capacitance 590 which is grounded at 591. The signal than passes through gate 592 and onto gates 628 and 629. The signal is added in AND gate 628 and passes through NAND gate 634 to terminal 633, which is connected to terminal 763 on FIG. 19, the shift register and logic circuitry. The output of gate 629 is fed into gate 635 together with a logic voltage signal originating in terminal 575' and is outputted through gate 638 to terminal 526 on FIG. 15, the A.C. motor driver circuitry. A capacitance 636 grounded at 637 is connected to the output of gate 635.

Provision for an auxiliary pipette is made by switch 593 and the auxiliary pipette connector 597 which is connected to the logic voltage as 596 and 595 and has an auxiliary pipette select switch 594. See FIG. 17. If a pipette is in use, the output is passed thorugh an R-C filter consisting of resistors 598 and 600', capacitance 599 and grounds 598', and 599'. The signal passes through a sCHMITT trigger comprising silicon rectifier 600, gates 603' and 603, resistance 602 and capacitance 604 which is grounded at 605. The output of the SCHMITT trigger is fed into gate 628 together with the output of gate 592. If auxiliary devices such as a flame spectrophotometer are used, provision is made through terminals 606 and 607 for external control pulses which pass through gate 608 and are fed also into gate 628.

A series of four additional signals are provided in the circuitry. A pipette mode signal enters the circuitry at 609 and originates from output terminal 1013 in FIG. 23, the manjal switch buffer and logic circuitry. A start signal enters the circuitry at terminal 611 and originates from output terminal 1016 in FIG. 23, the manual switch buffer and logic circuitry. Additionally, signals representing the third and sixth bit from the shift register enter the circuitry at terminals 613 and 614. respectively, and originate from output terminals 808 and 812, respectively, in FIG. 19, the shift register and logic circuitry. The signals from terminals 609 and 611 pass through gate 610 and are mixed with the shift register bit signals from terminals 613 and 614 in OR gate 615. Also, the sixth bit signal from terminal 614 is carried to a NOR gate 630 and is combined with the outut of gate 629 through capacitance 630' and resistance 631 to provide an output at terminal 631 which is connected to input terminal 701 in FIG. 18, the tip motor logic circuitry. Referring back to gate 615, the output thereof passes through capacitors 616 and through one-shot start pulse system comprising NOR gates 620, 622 and 624 and resistors 618 and 621 grounded at 619 and 621', respectively, and capacitance 623. Capacitor 617 is a filter capacitor. The output from NOR gate 624 is also fed into gates 628 and 629. Additionally, the output of gate 624 passes through a relay driver 625 and an operator auxiliary pipette start relay 626 which is connected to the logic voltage as at 627. Also included in the circuit is contact 639 of 626 having terminal connection points 640, 641, and 642, which is adapted to operate like a foot switch when an auxiliary pipette is connected into the transporter.

Referring now to FIG. 19, the shift register components are shown designated as 797, 798, 799, 800, 801, 802, 803 and 804. The component is an 8-bit Serial In Parallel-Out Shift Register. A series of input terminals are shown on the left-hand side of the drawing. A start signal enters the circuit at terminal 748 and originates from output terminal 877 in FIG. 20, the advance and start logic circuitry. A tube signal enters the circuitry at terminal 760 and originates in output terminal 1041 in FIG. 25, the automatic switch buffer and logic circuitry. An advance signal enters the circuitry at terminal 762 and originates in output terminal 876 in FIG. 20, the advance and start logic circuitry. A pipette signal enters the circuitry at terminal 763 and originates in terminal 633 in FIG. 17, the pipette logic circuitry. A tip motor signal, for running the tip motor forward or reverse, enters the system at terminal 768 and originates in output terminal 728 in FIG. 18, the tip motor logic circuitry. An automatic mode signal enters the circuitry at terminal 769 and originates in output terminal 1008 in FIG. 23, the manual switch buffer and logic circuitry. A manual mode signal enters the circuitry at terminal 770 and originates in output terminal 1009 in FIG. 23, also the manual switch buffer and logic circuitry. A start signal and automatic and manual signal enter the system at terminals 771 and 778, respectively, and originate in output terminals 1016 and 1010, respectively, In FIG. 23, the manual switch buffer and logic circuitry. A rack sense signal enters the system at terminal 779 and originates in output terminal 1049 in FIG. 25, the automatic switch buffer and logic circuitry. And, finally, a CLEAR signal enters the system at terminal 780 and originates from output terminal 879 in FIG. 20, the advance and start logic circuitry.

The start signal entering at terminal 748 is fed through a NOR gate 749 through an A.C. coupling circuit consisting of ground 751, resistor 752 and capacitor 750, and through NAND gate 753 and through another A.C. coupling circuit consisting of capacitants 754, resistor 756 and ground 755. The signal proceeds through NAND gate 757 and on to a NAND gate, which acts like an OR gate, 781. A capacitance is attached to the connecting line between gates 757 and 781 and is designated as 759, which is grounded at 758.

The tube signal passes through NAND gate 761 and is fed to an AND gate 767. The advance, pipette, and tip motor signals, originating from terminals 762, 763 and 768, respectively, are fed to gate 764. The output of NAND gate 764 is fed through NAND gate 765 to AND gate 767, together with the signal from gate 761. The automatic mode signal from terminal 769 is fed through an inverting NAND gate 772, through an OR gate 774, where it is coupled with the output of an AND gate 773, and then on to gate 767. The manual mode signal and start signal from terminals 770 and 771, respectively, are fed into AND gate 773.

The output of gate 767 is fed through an A.C. coupling circuit comprising capacitance 775, resistor 777 and ground 776, and fed to OR gate 781. The output of gate 781 is fed through two NOR gates, 782 and 785, which have an A.C. circuit comprising ground 783, resistor 784' and capacitance 786 connected thereto. The output of gate 785 is fed through an invertor 814 and then on to the components of the shift register.

The automatic and manual signal from terminal 778 and the rack sense signal from terminal 779 are fed into AND gate 821 where they are combined with the start pulse from terminal 748. The output of gate 821 is fed through inverting NOR gate 822 and then on to OR gate 823. The output of OR gate 823 is an advance lamp signal going to terminal 820 which is connected to input terminal 890 in FIG. 21, the lamp driver circuit.

The output of gate 753 is additionally fed to an entry flip-flop circuit consisting of gates 789 and 788 and capacitance 790. The output of that circuit is fed to OR gate 791 and through NOR gate 792, NAND gate 795 and invertor 796 to the first component 797 on the shift register. A capacitance 794 grounded at 793 is located between gates 792 and 795. Additionally, a signal to OR gate 823 is fed up to OR gate 791.

The connecting line between gates 791 and 823 also is connected to components 803 and 804 of the shift register and provides a seventh bit output from the register at output terminal 813 which is connected to input terminal 658 in FIG. 18, the tip motor logic circuitry. The clear signal from terminal 780 is fed through invertor 815 into the shift register. The shift register provides several outputs and also circulates a bit back from the shift register from components 803, 804 into gate 791 which is connected to gate 789 of the entry flip-flop. The bit signal from component 797 in the shift register is used to reset the entry flip-flop via gate 787. A bit signal 1 passes through output terminal 805 and is connected to input terminal 829 in FIG. 20, the advance and start logic circuitry, and input terminal 886 in FIG. 21, the lamp driver circuitry. A bit signal 2 passes through output terminal 806 which is connected to input terminal 647 in FIG. 18, the tip motor logic circuitry. A bit signal 3 passes through invertor 807 and through output terminal 808 which is connected to input terminal 613 in FIG. 17, the pipette logic circuitry. A bit signal 4 passes through output terminal 809 which is connected to input terminal 666 in FIG. 18, the tip motor logic circuitry and input terminal 887 in FIG. 21, the lamp driver circuitry. A bit signal 5 passes through output terminal 810, which is connected to input terminal 682 in FIG. 18, the tip motor logic circuitry. A bit signal 6 passes through invertor 811 and output terminal 812 which is connected to input terminal 614 in FIG. 17, the pipette logic circuitry. As stated before, a bit signal 7 passes through terminal 813 which is connected to input terminal 658 in the tip motor logic circuitry.

An output from components 802 and 803 of the shift register is connected through OR gate 818 which also receives an output from components 799 and 800 of the shift register. The output of gate 818 is a tip up lamp signal which passes through output terminal 819 connected to input terminal 889 in FIG. 21, the lamp driver circuitry. An output from components 798 and 799 is coupled with an output from components 801 and 802 of the shift register in OR gate 816. The output of gate 816 is a pipette lamp signal passing through output terminal 817 which is connected to input terminal 888 in FIG. 21, the lamp driver circuitry. Referring now to FIG. 20, there is shown the advance and start logic circuitry. Several inputs are provided on the left-hand side of the figure. A malfunction signal enters the circuit at terminal 826 and originates in output terminal 1183 of FIG. 26, the malfunction and alarm logic circuitry. An advance motor cam signal enters the circuitry at terminal 827 and originates from output terminal 1096 in FIG. 25, the automatic switch buffer and logic circuitry. The 1 bit pulse signal from output terminal 805 in the shift register circuitry enters the advance and start logic circuitry at terminal 829. A tip up signal enters at terminal 830 and originates from output terminal 1058 in FIG. 25, the automatic switch buffer and logic circuitry. An advance mode signal and a start signal enter the circuitry at terminals 831 and 834, respectively, and originate from output terminals 1012 and 1016 in FIG. 23, the manual switch buffer and logic circuit. An ejection signal enters at terminal 835 and originates from output terminal 1090 in FIG. 25, the automatic switch buffer and logic circuitry. A pipette position signal enters the circuit at terminal 836 and originates in output terminal 632 in FIG. 17, the pipette logic circuitry. A rack signal enters at terminal 837 and originates from output terminal 1049 in FIG. 25, the automatic switch buffer and logic circuitry. An automatic and manual signal enters at terminal 838 and 844 and originates from output terminal 1010 in FIG. 23, the manual switch buffer and logic circuitry. A tube signal enters at terminal 843 and originates from output terminal 1041 in FIG. 25, the automatic switch buffer and logic circuitry. A reset signal enters at terminal 847 and originates from output terminal 1015 in FIG. 23, the manual switch buffer and logic circuitry.

The malfunction signal from terminal 826 passes to an AND gate 872. The signal additionally is fed to AND gate 839 and OR gate 851. The advance motor cam signal from terminal 827 is fed to a gate 869, a NAND gate in a flip-flop, and an OR gate 871. The 1 pulse bit signal from terminal 829 is fed through an A.C. coupling circuit comprising capacitance 832', resistor 833' and ground 833 to an AND gate 854. The tip up signal from terminal 830 is fed through an inverting gate 832 and to AND gate 854 and AND gate 855. The advance mode signal from terminal 831 and the start signal from terminal 834 are also fed to AND gate 855. The ejection signal from terminal 835 is also fed to AND gate 855. Additionally, the start signal from terminal 834 is fed to an AND gate 853 and the ejection signal from terminal 835 is fed to a NAND gate 848. The pipette position signal from terminal 836 and the rack signal from terminal 837 are fed to AND gate 839 together with the start signal from terminal 834, the malfunction signal from terminal 826 and the automatic and manual signal from terminal 834. The output of gate 839 is fed through a flip-flop circuit comprising NAND gates 840 and 841 and capacitance 842. Additionally, the pipette position signal from terminal 836 is fed through an inverting gate 828, the output of which is coupled with the start signal pulse in AND gate 853. The output of the flip-flop concluding gates 840 and 841 is fed also to gate 853 and to an AND gate 856, together with the ejection signal from terminal 835. The tube signal from terminal 843 is also fed to AND gate 856. The rack signal from terminal 837 is also fed to AND gate 856 and to an inverting gate 845. The output of inverting gate 845 is passed to a NAND gate 848 which also receives an ejection signal from terminal 835. An A.C. coupling circuit is provided having capacitance 849, ground 850 and resistance 850'. The output of gate 848 is passed to an OR gate 851 which also receives a malfunction signal from terminal 826 and a reset signal from terminal 847. Additionally, the output from inverting gate 845 passes through an A.C. coupling circuit comprising capacitance 845', resistor 846' and ground 846, to a NAND gate 857. The output of OR gate 851 passes through an inverting gate 852 and provides a clear signal at output terminal 879 which is connected to input terminal 780 in FIG. 19, the shift register and logic circuitry. Additionally, the clear signal is fed back to gate 841 of the flip-flop receiving the output of AND gate 839.

The output of gate 857 is fed to a flip-flop including gates 858, 860 and capacitor 859 and the output of that flip-flop controls a three-second timer 861 which is coupled to a resistor 862 and capacitor 863. The output of AND gate 856 is fed through two NOR gates 865 and 866, which together act like an OR gate. Gate 865 also receives an output from the flip-flop including gates 858 and 860.

The tube signal from terminal 843 is also fed to an OR gate 867 and is coupled with the signal output from the 3-second timer 861. The output of AND gate 854 proceeds to a flip-flop including gates 868 and 869 and capacitor 870. The output of the flip-flop is fed to OR gate 871. Gate 869 of the flip flop also receives the reset signal from terminal 847 and the advance motor cam signal from terminal 829. The advance motor cam signal is also fed to OR gate 871 which additionally receives the output of AND gate 855. The output of gates 865 and 866 is also fed into OR gate 871. The output of gate 871 is fed through an inverting gate 873 to provide an advance signal through at output terminal 876 which is connected to input terminal 762 in FIG. 19, the shift register and logic circuitry. A capacitor 874', grounded at 874, is connected to this output line. Additionally, the output of OR gate 871 is fed through AND gate 872 which also receives the malfunction signal from terminal 826. The output of gate 872 is fed to output terminal 875 which is connected to input terminal 511 in FIG. 15, the A.C. motor driver circuitry. The output of gate 871 is also fed back to gate 857, which controls the flip-flop including gates 858 and 860. The output of AND gate 853 provides a pump sequence signal at terminal 853' which is connected to input terminal 885 in FIG. 21, the lamp driver circuitry. The output of gate 841 of the flip-flop is also used to provide a start signal at output terminal 877 which is connected to input terminal 661 in FIG. 18, the tip motor logic circuitry and input terminal 748 in FIG. 19, the shift register and logic circuitry. The output of the flip-flop including gates 858 and 860 is also passed out of the system as a tray feed motor signal at output terminal 878 which is connected to input terminal 534 in FIG. 15, the A.C. motor driver circuitry. An inverting gate 864 is connected to the three-second timer 861 in gate 860 of the flip-flop.

Referring now to FIG. 21, there is shown the lamp driver circuitry designated generally as 880. The lamp driver circuitry provides an indication to the operator of what is going to occur next and what is happening at the present time. Additionally, it provides an indication of problems such as jams in the system. An open tray signal enters the system at terminal 881 and originates from output terminal 1173 of FIG. 26, the malfunction and alarm logic circuitry. The signal passes through lamp driver circuit 895 to the open tray lamp 896 to give the operator warning if he is about to operate the system and the tray is in open conditon. The lamp driver circuits for all of these lamps are substantially identical and are illustrated in FIG. 22 to be described.

An advance jam signal enters at terminal 882 and originates from output terminal 1182 of FIG. 26, the malfunction and alarm logic circuitry. The signal then proceeds on through lamp driver circuit 897 to advance jam light 898.

A tip wiper signal enters at terminal 883 and originates from output terminal 1184 in FIG. 26 and passes through lamp driver circuit 899 to the tip wiper lamp 900.

An ejection signal enters at terminal 884 and originates from output terminal 1090 in FIG. 25, the automatic switch buffer and logic circuitry, and passes through lamp driver circuit 901 to eject lamp 902.

A pump sequence signal enters at terminal 885 and originates from output terminal 853' in FIG. 20, the advance and start logic circuitry, and passes through lamp driver circuit 903 to pump sequence lamp 904.

A 1 bit signal enters at terminal 886 and originates from output terminal 805 in FIG. 19, the shift register and logic circuitry. The signal then proceeds through invertor 907 and lamp driver circuit 905 to the tip down front light 906.

A 4 bit signal enters at terminal 887 and originates from output terminal 809 in FIG. 17, the pipette logic circuitry. The signal then proceeds through invertor 908 and lamp driver circuit 909 to the tip down back lamp 910.

A pipette sequence lamp signal enters at terminal 888 and originates from output terminal 817 in FIG. 19, the shift register and logic circuitry, and passes through lamp driver circuit 911 to pipette lamp 912.

A tip up sequence lamp signal enters at terminal 889 and originates from terminal 819 in FIG. 19, the shift register and logic circuitry. The signal then passes through lamp driver circuit 913 to the tip up lamp 914.

An advance sequence lamp signal enters the system at terminal 890 and originates from output terminal 820 in FIG. 19, the shift register and logic circuitry. The signal then passes through lamp driver circuit 915 to light advance lamp 916.

An automatic mode signal enters at terminal 891 and originates from output terminal 1008 in FIG. 23, the manual switch buffers and logic circuitry, and then passes through invertor 919 and lamp driver circuit 917 to the automatic mode lamp 918.

A manual mode signal enters at terminal 892 and originates from output terminal 1009 in FIG. 23, the manual switch buffer and logic circuitry. The signal then proceeds through invertor 920 and lamp driver circuit 921 to the manual lamp 922.

An advance mode signal enters at terminal 893 having originated in the manual switch buffer and logic circuitry, FIG. 23, at output terminal 1012. The signal then passes through invertor 923 and lamp driver circuit 924 to the advance mode lamp 925.

A pipette mode signal originates from output terminal 1013 in FIG. 23, the manual switch buffer and logic circuitry, and enters at terminal 894. The signal then proceeds on through invertor 926 and lamp driver circuit 927 to pipette mode lamp 928.

FIG. 22 is representative of the lamp driver circuits used in FIG. 21. Generally, the circuit is designated by 929 and the signal enters the system at terminal 932. Terminals 935 and 941 are connected to ground and terminal 930 is connected to the logic voltage. The signal is then processed by resistors 931, 933, 934, 937 and 938 and silicon transistors 936 and 939 to output to the appropriate lamp at output terminal 940.

Referring now to FIG. 23, there is shown the manual switch buffers and logic circuitry designated as 942. There are no inputs to this system, only outputs. The system circuitry is centered around the four major operator switches in the transporter circuitry, namely the automatic mode switch 943, the manual mode switch 949, the advance mode switch 955, the pipette mode switch 961, the reset switch 967 and the start switch 977. Each of these switches have ground connections such as 944, 950, 957, 962, 968 and 978. There are switch buffering circuits associated with each major operator control switch. Switch 943 is buffered through gates 946 and 947 and resistors 945 and 948. Switch 949 is buffered through gates 952 and 953 and resistors 951 and 954. Switch 955 is buffered through gates 958 and 959 and resistors 956 and 960. Switch 961 is buffered through gates 964 and 965 and resistors 963 and 966. Switch 967 is buffered through gates 969 and 971 and resistors 970 and 972. Switch 977 is buffered through gates 980 and 981 and resistors 979 and 982. Each resistor is connected to the logic voltage at 983. A power up reset 973 has its output connected to invertor gate 976 and is combined in gate 974 with the output from the buffering circuit for switch 967. The outputs of the buffering circuits for switches 943, 949, 955 and 961 are fed through a series of gates which are designated respectively as 984, 988 and 992 for the automatic mode switch, 985, 989 and 993 for the manual mode switch, 986, 990 and 994 for the advance mode switch, and 987, 991 and 995 for the pipette mode switch. The output of gate 992 is fed into a flip-flop mode circuit consisting of gates 996 and 997 and capacitor 1004. The output of this flip-flop exits through terminal 1008 in the form of an automatic mode signal and is connected to input terminal 891 in FIG. 21, the lamp driver circuit, and input terminal 769 in FIG. 19, the shift register and logic circuit. The output of gate 993 is fed through a flip-flop circuit consisting of gates 998 and 999 and capacitor 1005 and is coupled with a portion of the output of gate 997 in an OR gate 1011 which produces an output signal. The output signal is an automatic or manual signal which exits through output terminal 1010 which, in turn, is connected to input terminal 838 in FIG. 20, the advance and start logic circuitry, and input terminal 778 in FIG. 19, the shift register and logic circuit. The output of gate 994 proceeds through a flip-flop circuit consisting of gates 1000 and 1001 and capacitor 1006. The output of this flip-flop circuit is an advance signal exiting through output terminal 1012 which is connected to input terminal 893 in FIG. 21, the lamp driver circuit, and input terminal 831 in FIG. 20, the advance and start logic circuitry.

The output of gate 995 passes through a flip-flop circuit comprising gates 1002 and 1003 and capacitor 1007 and exits as a pipette signal at termianl 1013 which is connected to input terminals 894 in FIG. 21, the lamp driver circuitry, and input terminal 609 in FIG. 17, the pipette logic circuitry. The output of gate 974 proceeds through inverting gate 975 to produce a pulse signal at terminal 1015. The reset signal from gate 975 also connects to gates 984, 985, 986 and 987 to clear the mode flip-flops. Terminal 1015 is connected to input terminal 1119 in FIG. 26, the malfunction and alarm logic circuitry, input terminal 847 in FIG. 20, the advance and start logic circuitry, and input terminal 656 in FIG. 18, the tip motor logic circuitry. A capacitor 1014', grounded at 1014, is connected to the output terminal.

The output of the buffering circuit for the start switch 977 produces a start switch signal at terminal 1016. Terminal 1016 is connected to input terminal 771 in FIG. 19, the shift register and logic circuitry, input terminal 834 in FIG. 20, the advance and start logic circuitry, and input terminal 611 in FIG. 17, the pipette logic circuitry.

Referring now to FIG. 25, there is shown the circuitry for the automatic switch buffers and ejection logic. The circuitry is designated generally as 1031. A pair of tube sensing contacts, 1034 and 1035, have normally open contacts and act in conjunction with a pair of tube sensing contacts 1032 and 1033, having normally closed contacts for sensing tubes in the front and rear rows of a tube rack. This tube sensing circuit is grounded at 1036 and signals produced thereby are buffered through gates 1038 and 1040, resistors 1037 and 1039 and capacitor 1041'. The output of the switch buffer is a tube present signal exiting through output terminal 1041 which is connected to input terminal 760 in FIG. 19, the shift register and logic circuitry, and input terminal 843 in FIG. 20, the advance and start logic circuitry.

A rack sensing switch 1042 is grounded as at 1043 and produces a signal when a rack is in position which is buffered through gates 1045 and 1047, resistors 1044 and 1046 and capacitor 1048. The output of the buffering produces two signals. The first signal is a rack sense signal exiting at output terminal 1049 which is connected to input terminal 779 in FIG. 19, the shift register and logic circuitry and input terminal 837 in FIG. 20, the advance and start logic circuitry. The second signal is a rack sense signal exiting through terminal 1050 which is connected to input terminal 1114 in FIG. 26, the malfunction and alarm logic circuitry.

A tip up sensing switch 1051 is grounded as at 1052 and is buffered through a buffering circuit comprising gates 1055 and 1056, resistors 1053 and 1054 and capacitor 1057. The output of this buffering circuit produces a tip up signal at terminal 1058 which is connected to input terminals 659 in FIG. 18, the tip motor logic circuitry, and input terminal 830 in FIG. 20, the advance and start logic circuitry.

A toggle switch 1059, used to sense the toggle position on the tip motor cam, is grounded as at 1060 and produces a signal which is buffered through gates 1062 and 1064, resistors 1061 and 1063 and capacitor 1065. The output of the buffering produces a toggle signal at terminal 1066 which is connected to input terminal 662 in FIG. 18, the tip motor logic circuitry.

An ejection motor cam switch 1067 is grounded as at 1068 and produces a signal which is buffered through a buffering circuit which includes gates 1070 and 1072, resistors 1069 and 1071 and capacitor 1073. A rack limit switch 1074 which is grounded as at 1075 produces a signal which is buffered through a buffering circuit containing gates 1077 and 1085, resistors 1076 and 1083, and capacitor 1086. The combined signals from the latter two buffering circuits are fed into an OR gate 1087.

An advance motor cam switch 1081 is grounded at 1082 and produces a signal buffered through gates 1092 and 1093, resistors 1083' and 1084 and capacitor 1094. The output from gate 1092 is an advance motor cam signal which exits at terminal 1096 which, in turn, is connected to input terminal 827 in FIG. 20, the advance and start logic circuitry. A common buss is connected to all the buffering circuits and has its terminal to the logic voltage at 1078. Another logic voltage terminal 1095 is connected to AND gate 1089 together with the output from OR gate 1087. The output of gate 1089 produces an ejection motor driver signal at terminal 1091. Terminal 1091 is connected to input terminal 530 in FIG. 15, the A.C. motor driver circuitry.

The output from OR gate 1087 is also connected to gate 1088 whose output produces an ejection signal at terminal 1090. Terminal 1090 is connected to input terminal 1113 in FIG. 26, the malfunction and alarm logic circuitry, input terminal 884 in FIG. 21, the lamp driver circuitry, and input terminal 835 in FIG. 20, the advance and start logic circuitry.

Referring now to FIG. 26, the malfunction and alarm logic circuitry is shown designated generally as 1112. An ejection signal enters the circuit through terminal 1113 and originates in output terminal 1090 in FIG. 25, the automatic switch buffer and logic circuitry. A rack sense signal enters through terminal 1114 an originates from output terminal 1050 in FIG. 25, the automatic switch buffer and logic circuitry. A reset signal enters through terminal 1119 and originates in output terminal 1015 in FIG. 23, the manual switch buffer and logic circuitry. The ejection signal from terminal 1113 is passed through a NAND gate 1115, through an A.C. coupling circuit which includes capacitor 1115', resistor 1118 and ground 1117 to an AND gate 1116. The rack sense signal from terminal 1114 is also fed into gate 1116. The reset signal from 1119 is fed through NAND gate 1120 and NAND gate 1121. The combined outputs of gates 1116 and 1121 are fed into a flip-flop circuit comprising gates 1122 and 1123 and capacitor 1124. The output of the flip-flop circuit is fed to gate 1150 which acts like an OR gate and from there to a flip-flop circuit including gates 1155 and 1156 and capacitor 1157. Another portion of the output from gate 1122 is fed through an A.C. coupling circuit including capacitor 1151, resistor 1153 and ground 1152 to a NAND gate 1154 and into a gate 1155 in the flip-flop circuit. Additionally, the output from gate 1122 is fed to an AND gate 1162. The output from NAND gate 1121 is also fed into the gate 1156 of the second flip-flop circuit. The flip-flop circuit controls a seven-second timer 1160 which includes capacitance 1159 and resistor 1158. The output from the seven-second timer 1160 rpoceeds through gate 1161 to a second flip-flop circuit including gates 1165 and 1166 and capacitance 1167. Also the output from gate 1121 is bypassed around the seven-second timer to gate 1166 of the third flip-flop circuit. The output of the latter mentioned flip-flop circuit controls a 35-second timer 1170 which includes capacitance 1169 and resistor 1168. The output from the timer 1170 is fed through a NAND gate 1171 whose output is recycled back to gate 1166. The output of timer 1170 is also fed back to gate 1150, an OR gate.

A portion of the output of the flip-flop gate 1155 is fed to gate 1162 together with the output from gate 1122.

The output from NAND gate 1120 is fed to a series of NOR gates 1129, 1134 and 1140. These NOR gates are coupled with NOR gates 1128, 1133 and 1139, respectively, and together with capacitors 1128', 1135 and 1141 comprise switch buffering circuits. A tray open contact switch 1125, coupled to the logic voltage at 1126 provides an input into gate 1128. A jam contact switch 1130, connected to the logic voltage at 1131, provides an input to gate 1133. A phototransistor 1136, grounded at 1137, provides an input into interface unit 1138. The interface unit is shown in FIG. 27. The output from the interface unit is passed into NOR gate 1139.

A switch 1144, which is actuated when the tray is shut and if a reel is in place, is connected to the logic voltage at 1145 and provides a signal to either NOR gate 1142 or NOR gate 1143. The latter two gates together with capacitance 1148 provide a buffering for the signal. The switch buffering resistors 1127, 1132 and 1146 are grounded at 1149. The output from the buffering circuit which includes gates 1128 and 1129 provides a tray open signal at terminal 1173 which is connected to input terminal 881 in FIG. 21, the lamp driver circuitry. The output from NOR gate 1133 of the buffering circuit provides an advance jam signal at terminal 1182 which is connected to input terminal 882 in FIG. 21, the lamp driver circuitry. The output from gate 1139 provides a tip wiper signal at terminal 1184 which is connected to input terminal 883 in FIG. 21, the lamp driver circuitry. The output from gate 1142 of the buffering circuit provides a reel motor signal at terminal 1185 which is connected to terminal 542 in FIG. 15, the A.C. motor driver circuitry. The tray signal from gate 1128 and the jam signal from gate 1133 are also connected via OR gate 1174, whose output goes to inverting gate 1175. The output of inverting gate 1175 passes through capacitor 1176 and into a flip-flop circuit comprising gates 1177 and 1180 and capacitor 1181. Capacitor 1176 together with resistor 1178 and ground 1179 comprises an A.C. coupling circuit. The flip-flop gate 1180 additionally receives an input from gate 1121. The output of the flip-flop provides a malfunction signal at terminal 1183 which is connected to input terminal 826 in FIG. 20, the advance and start logic circuitry, and input terminal 646 in FIG. 18, the tip motor logic circuitry. This signal is also passed into OR gate 1163 together with the output from gate 1162. The output of gate 1163 is inverted by gate 1164 and produces a buzzer signal at terminal 1172 which is connected to input terminal 538 in FIG. 15, the A.C. motor driver circuitry.

Referring now to FIG. 18a is shown one-half of the tip motor logic circuitry. A malfunction signal enters at terminal 646 and originates in output terminal 1183 in FIG. 26, the malfunction and alarm logic circuitry. The malfunction signal continues on to AND gate 729. Since the stroke of the tip is dependent upon the time the motor runs, a front stroke adjustment is provided as at 645 and provides an input into a down front timer 724. Also included in this circuit are maximum stroke adjustment 721 and minimum stroke adjustment 722 which are located within the device and are not operator accessible. These are set before the unit is delivered. Down front timer 724 also includes resistor 722' and capacitor 723. The down front timer controls the amount of time the motor is to run and consequently the length of stroke of the tip. The entire unit, together with the minimum and maximum stroke adjustments constitutes a bistable multivibrator.

A 2-bit signal from the shift register in FIG. 19 enters at terminal 647, passes through A.C. coupling circuit including capacitor 648, resistor 649 and ground 650 and into inverter 651. A reset pulse signal enters the system at terminal 656 and originates from output terminal 1015 in FIG. 23, the manual switch buffer and logic circuitry. The 2-bit signal in terminal 647 originates from output terminal 806 on FIG. 19, the shift register circuitry. The reset signal passes through two inverters 655 and 677 and, together with the output from inverter 651 into a flip-flop circuit comprising gates 652 and 653 in capacitor 654.

A 7-bit signal enters the system at terminal 658 and originates in output terminal 813 in FIG. 19, the shift register and logic circuitry, and enters the gate 660. A tip up signal enters at terminal 659 and originates from output terminal 1058 in FIG. 25, the automatic switch buffer circuitry. The tip up signal is combined with the 7 bit signal in gate 660. A start signal enters at terminal 661 and originates from output terminal 877 in FIG. 20, the advance and start logic circuitry. A toggle signal enters at terminal 662 and originates from output terminal 1066 in FIG. 25, the automatic switch buffer and logic circuitry. The start signal and toggle signal are fed into a gate 665. The signals are additionally combined in gate 664 together with the tip up signal from terminal 659, but the toggle signal from 662 is inverted by passing through inverter 663. A 4-bit signal enters at terminal 666 and originates from output terminal 809 in FIG. 19, the shift register and logic circuitry. The 4-bit pulse signal, together with the tip up signal from terminal 659, are combined in gate 667.

The toggle switch signal present at 662 is AND gated with the output of gate 652 by gate 654'. The output of gate 654' connects to the input of timer 724.

The output from gate 653, 660 and 664 are fed into gate 668. The output from gate 653 and gate 664 are fed into gate 669. The output from gate 669 is fed through an A.C. coupling circuit comprising resistor 671, capacitor 671' and logic voltage connection 670 to a negative OR gate 678. The output from gate 665 is fed to a gate 673. The gate 673 also receives part of its input from AND gate 672 connected to leads 672' and 673' which match up with adjoining leads on FIG. 18b.

Gate 653 also receives a portion of its input through matching lead 655'. A matching lead 665' is coupled with the output from gate 665 before entering gate 673. A gate 677 receives output from the components on FIG. 18b through terminals 674' and 677'. The output from terminal 677' also enters gate 673. The output from gate 673 passes through an A.C. coupling circuit comprising capacitor 674, resistor 676 and logic voltage connection 675 to negative OR gate 678. The output from gate 677 is passed through inverting gate 726' and onto OR gate 726. OR gate 726 receives the output also of gate 668 through inverting gate 679. The output of gate 726 is connected to gate 729 and to gate 727. Gate 727 inverts the signal and provides a signal at terminal 728. Terminal 728 is connected to input terminal 768 in FIG. 19, the shift register and logic circuitry.

The output of gate 678 is passed to the circuitry in FIG. 18b through matching lead 678' and to NOR gate 731. Gate 731, together with gate 732, capacitor 734, and resistor 736, grounded at 735, provides a one-shot pulse to gate 729. The gate 729 provides a tip motor drive signal at terminal 730 which is connected to input terminal 517 in FIG. 15, the A. C. motor driver circuit.

Referring now to FIG. 18b, the remainder of the tip motor logic circuitry is shown. As FIG. 18b shows a front stroke adjustment, FIG. 18b shows a rear stroke adjustment 681 which is used to control the stroke of the tip going into the back tube as opposed to the front tube in the rack. Adjustment 681 provides input to a timer circuit 690 containing resistors 688' and capacitor 689. As in the front stroke adjustment, a maximum stroke adjustment 687 and a minimum stroke adjustment 688 are provided within the timing circuit. However, these latter adjustments are set and are not operator accessible

A 5 bit signal enters at 682 from output terminal 810 in FIG. 19, the shift register and logic circuitry. Bit 5 signal passes through an A. C. coupling circuit comprising capacitor 681', resistor 683' and ground 682' to an inverter 683. The output of inverter 683 together with the output of inverter 655 in FIG. 18a, is passed into a flip-flop circuit containing capacitor 686 and gates 684 and 685. The inverted toggle switch signal present at the output of inverter 663 in FIG. 18a connects to gate 685' via lead 690'This signal is AND gated with the output of gate 684 by 685'. The output of gate 685' connects to the input of timer 690. The output of timer circuit 690 passes through inverting gate 691 and is recycled back into the flip-flop gate 685 to reset the flip-flop. The output of timer circuit 690 is passed into AND gate 696. Terminal 692 is connected to resistor 694 with ground 693 to inverting gate 695. An external select switch is coupled to terminal 692 when other devices are to be used in conjunction with the operation of the transporter, such as a flame spectrophotometer, etc.

An external potentiometer 700 is used in conjunction with an external select switch when it is connected to terminal 692.

A delay start signal enters at terminal 701 and originates in output terminal 631 in FIG. 17, the pipette logic circuitry. The delay start signal goes to gate 705. Gate 705 also receives an external select signal hooked to terminal 692 and its output enters a flip-flop circuit comprising gates 706 and 707 and capacitor 707'. This flip-flop circuit is used to control and set a one-second timer 708. Timer 708 includes capacitor 709 and resistor 710. The output of timer 708 passes through inverting gate 711 and into a second flip-flop circuit comprising gates 712 and 713 and capacitor 713'. The output of inverting gate 711 is also fed back into the flip-flop gate 707. The second flip-flop circuit controls a variable timer 714 which includes resistor 716 and capacitor 715. The variable timer is connected to the external potentiometer 700 and is set by said potentiometer. The output of timer 714 is fed through inverting gate 717 and onto terminal 718 to provide an external pulse signal which tells an external device, such as a spectrophotometer, to start. Also, the output of gate 717 is fed back into flip-flop gate 713 to reset the flip-flop circuit. The second flip-flop circuit is also connected via matching terminal 677' to gates 673 and 677 in FIG. 18a.

The output of inverting gate 725 in FIG. 18a is passed to a gate 697 in FIG. 18b via matching terminal 725'. Gate 697 is one-half of a flip-flop circuit to run the motor in a forward direction, the other half of the flip-flop being gate 698. The output of gate 696 is fed into gate 698 together with the output of inverting gate 717 in the variable timing circuit. The output of the flip-flop comprising gates 697 and 698 are fed to an OR gate 719 together with the output of gate 665 in FIG. 18a via matching terminal 665'.

The output of OR gate 678 in FIG. 18a is fed, via matching terminal 678' to a NOR gate 737. The output of NOR gate 737 is fed to an inverting NOR gate 741 and the output of said second NOR gate is fed through an A.C. coupling circuit back into gate 737. The A.C. coupling circuit includes capacitor 740, resistor 739 and common ground connection 738. The output of NOR gate 741 is fed to NAND gate 743 together with the output of an inverting gate 720 which inverts the output of OR gate 719. The output of gate 737, together with the output of OR gate 719 are fed to a NAND gate 742. The outputs of NAND gates 742 and 743 are fed to NAND gate 744. The output of gate 744 is fed to a relay driver 745 which produces a reverse relay signal at terminal 746. Terminal 746 is connected to input terminal 521 in FIG. 15, the A. C. motor driver circuit.

ELECTRONIC SOLID STATE CONTROL SYSTEM OPERATION

The A. C. motor driver circuitry in FIG. 15 is essentially self-explanatory in the sense that when the system receives signals from the other circuit cards or circuitry they energize the appropriate motors.

In FIG. 17, the pipette logic circuitry, the switches 569, 570, 571, 572, 573, and 574 are all located within the transporter pipette. In normal operation the RUN switch 572 is closed which selects the switches 571 and 570. Whenever the transporter pipette is not running after a dispensing or discharging cycle, either switch 571 or 570 will be operated causing no signal to be present at the filtered Schmitt trigger circuit comprised of gates 587 and 589. Whenever the SET switch 573 is operated for setting the pump stroke for the pipette, switch 574 is selected and will cause the pipette to operate until switch 574 is operated by cam action. Whenever both switches 572 and 573 are selected, a condition is relaized where a signal is always present which will cause the pipette to operate continually, thus enabling pumps to be primed. The circuitry also accommodates the auxiliary pipette which has its contact switch designated as 593. The various arrows accompanying the circuit are merely pin connections as they are throughout the remainder of the circuits. Whenever the auxiliary pipette is not operating, switch contact 593 is closed. This causes a signal to be present at the input of the filtered Schmitt trigger comprised of gates 603' and 603. The auxiliary pipette select switch 594 is used to select contact 593, otherwise, a true signal is always presented to the said Schmitt trigger. The one-shot circuit consisting of gates 620, 622, and 624 produces a pulse whose duration is long enough to run the pipette to operate the cam switches in subcircuit 568 in the pipette. The said one-shot circuit is triggered by the start switch signal when the pipette mode is selected via gates 610 and 615 and by bit signals 3 and 6 from the shift register via terminals 613 and 614 and gate 615, an OR gate. The said one-shot circuit energizes relay coil 626 via relay driver 625. Relay 626 has contacts 639 which operate the auxiliary pipette via terminals 640, 641, and 642.

Gate 608 is used to enable an external device to inhibit transporter operation via gate 628 and 634 and terminal 633. Gates 628 and 634 gives a signal that indicates that the transporter pipette or the auxiliary pipette, if selected, are operating or that the external device, if selected, is functioning. Gates 629 and 635 are used to activate the transporter pipette motor via terminal 638 which connects to the A. C. drivers. Gate 630 is used to produce a delay start signal only after the transporter pipette has completed a discharge cycle. Gates 576 and 580 are used as a switch buffer for the right position limit switch 569 contacts.

Referring now to FIGS. 18a and 18b, the tip motor logic circuitry, the malfunction signal originating into the system at terminal 646 prevents the tip motor from running. Gates 652 and 653 constitute a timer flip-flop for starting the tip down front timer 724. Gate 725 constitutes a time output gate for timer 724. Each timer in all the circuits in this apparatus has such a timer flip-flop and output gate associated therewith. The purpose of gate 725 is to produce a reset signal for its respective timer flip-flop, gates 652 and 653. Whenever a timer flip-flop is set, its respective timer will start timing. At the end of the predetermined time interval a pulse will appear at its output which in turn resets the timer. This is true for all timers in the apparatus. The timer flip-flop for the tip down front timer is set by the 2-bit signal from the shift register via terminal 647. The timing of the tip motor starts after the toggle switch is operated by the tip motor via gate 654'. The tip down front timer controls the time the motor runs the tip down into the front tube. The timing interval is determined by the setting of control 645.

The operation of the tip down back timer is identical to that of the tip down front timer except that it is triggered by 5 bit signal from the shift register via terminal 682 and that the timing of the tip motor starts after the toggle switch is again operated by the tip motor via gate 685'.

In the normal operation of the tip motor, that is, when the external control is not selected, the motor reversing flip-flop comprised of gates 697 and 698 is always set after a timed forward rotation of the motor and always reset after a timed reverse rotation of the motor. This action predetermines the next direction of rotation. The output of the self-positioning circuitry consisting of gates 664 and 665 also determines the direction of rotation of the tip motor by combining with the output of the motor reversing flip-flop via gate 719. This signal is exclusively OR'ed with the signal from the one-shot circuit comprised of gates 737 and 741 which energizes the tip motor reversing relay via relay driver 745 and terminal 746. The exclusive OR function is accomplished by gates 720, 742, 743, and 744. The said one-shot circuit is normally triggered only after the tip motor runs due to the self-positioning circuitry or due to a timer action. The triggering logic is accomplished with gates 669, 673, and 678. The net result of the exclusive OR logic is to prevent the operation of the reversing relay during dynamic motor braking. Further, the one-shot circuit composed of gates 731 and 732 is also triggered at the same instant as the one-shot circuit previously described. The action of this one-shot inhibits the starting of the tip motor until the aforesaid relay contacts are closed.

The gates 660 and 667 are used to raise the tip up from the back and front tubes respectively upon command from the shift register via terminals 658 and 666 respectively. Logic comprising gates 668, 677, 726, 726', and 727 gives a signal when the tip motor is operating. The inverse of this signal is AND gated with the malfunction signal at 646 and with the output of one-shot composed of gates 731 and 732 by gate 729 to give a tip motor drive signal at 730.

When the external control select switch is operated, the normal operation of the tip is interrupted as described below. After the tip moves down into the back tube, the normal resetting of the motor reversing flip-flop is inhibited by gate 696. Also, the triggering logic for the previously described one-shot circuits is inhibited by gate 672. After a discharge cycle of the pipette, a delay start signal at 701 starts timer 708 via gate 705. Timer 708 has a delay of approximately one second to allow any reagents that the pipette has dispensed to mix with the sample. After the delay of approximately one second, timer 708 starts timer 714. This timer is adjusted through the external potentiometer 700 and makes the tip motor run the tip further down the same tube. In other words, the tip initially discharges above the liquid level in the tube, then waits for a predetermined amount of time as set into the timer 714, usually one-half second, and then goes down into the liquid to aspirate the combined liquid and sample. The external signal going out of the circuit at terminal 718 tells the external device to begin its function.

The reset signal at 656 is buffered by inverters 677 and 655 and is used to reset all timer flip-flops and the motor reversing flip-flop in the tip motor logic system.

Referring now to FIG. 19, the shift register and logic circuitry, the shift register is used to sequentially control the operations of the apparatus by the stepwise circulation of a single bit through it. The appearance of the bit at each bit position initiates the corresponding action required at that step.

The entry of the single bit into the shift register is accomplished by an entry flip-flop comprised of gates 789 and 788, and pulse delaying gates of 749, 753, and 757. When a start signal is presented at terminal 748, a negative start pulse at gate 753 sets the entry flip-flop. At the output of gate 757, a negative delayed start pulse triggers a one-shot circuit comprised of gates 782 and 785 which produces a shift signal for the shift register. Since an input signal is presented to the shift register from the entry flip-flop through gates 791, 792, and 795, a bit will be entered into the first bit position. The bit appearing at position 1 resets the entry flip-flop.

Subsequent shift pulses are produced by the completion of an advance operation, a tip operation, a pipette operation, or an external operation or by manual means.

The logic consisting of gates 761, 764, 765, 767, 772, and 774 is used to generate shift pulses when in the automatic mode upon completion of any advance, tip, pipette, or external control operation. The logic is also adapted to give shift pulses when the start switch is depressed while in the manual mode. This is accomplished specifically by gate 773.

Gates 821 and 822 are used to give an advance lamp signal before starting occurs. Gate 823 OR's this signal with that from the shift register so that the advance lamp will operate after starting at the appropriate time. The lamp driver gates 816 and 818 are connected to act like OR gates.

Referring now to FIG. 20, the advance and start logic circuitry, the malfunction signal originating at terminal 826 is used to inhibit the advance motor. Gate 853 is used to give a pump sequence signal when starting is attempted when the pipette is to perform a discharge cycle. This signal is inhibited after starting occurs. Gate 839 is used to determine the condition which must be met before the start flip-flop composed of gates 840 and 841 can be set. The conditions which must be met are a false pipette right position signal at terminal 836, a true rack signal at terminal 837, a false malfunction signal at termnal at 826, a true automatic or manual signal at terminal 838, and a true start switch signal at terminal 834. Once the start flip-flop is set, a 1 bit signal will appear at terminal 829 setting the advance start flip-flop comprised of gates 868 and 869. Gate 854 insures that the tip is up before rack advancing occurs. After the advance start flip-flop is set, gate 871 gives an advance motor drive signal at terminal 875 through gate 872. The signal furnished at terminal 876 through gate 873 is for the shift register logic. Once the advancement motor starts rotating an advance motor cam switch signal will disappear at terminal 827. This action will reset the advance start flip-flop via gate 869 and furnish another signal to gate 871. This will cause the advance motor to continue running until the signal at 827 is again true. The advance motor cam switch signal at 827 will only be true after the advance motor causes one complete cycle of rack advancement.

The advance start flip-flop is also set by another means by gate 867 as described below. Whenever a rack advances to its last tube position, the rack signal at terminal 837 disappears causing timer 861 to start by means of gates 845 and 857. The rack signal must change during an advance cycle in order for timer 861 to be triggered. This is accomplished with gate 857. If no tubes are present in the last position of the rack, the automatic advance signal produced by gate 856 and described below is inhibited by the timer by neans of gate 865 and 866. Timer 861 has a time delay which allows time for the next rack to be processed, if any, to move into the processing position. When the delay has expired the pulse from the timer goes to gate 867 and, if no tubes are present, then to the advance start flip-flop which causes an advance cycle.

Two other means are possible for causing a rack advance. Whenever a rack is advanced and no tubes are present at the new tube position and the start flip-flop is set and no rack eject is occurring, gate 856 gives a false signal to gate 871 via gates 865 and 866. When the rack is moved to the last tube position, this signal is inhibited, as mentioned above, by timer 861. The rack may also be advanced manually via gate 855. The output of gate 855 goes false, thus causing an advance signal, when the advance mode signal at terminal 831 is true and when the tip up signal from terminal 830 via gate 832 is true and when the not eject signal at terminal 835 is true and when the start switch signal at terminal 834 is true.

A clear signal is generated by the logic of gate 851 which acts like an OR gate to combine the reset signal at terminal 847, the malfunction signal at terminal 826, and the output of gate 848. The output of gate 848 gives a signal at the completion of the rack processing, that is, after a rack eject occurs with no more racks present to be processed. Therefore, a clear signal occurs at terminal 879 when a reset, a malfunction, or a complete signal is received by gate 851. This signal is used to reset the start flip-flop and the shift register via terminal 879.

The operation of the lamp driver circuit shown in FIG. 21 is relatively self-explanatory in the sense that any signal coming in through the lamp driver circuits operates the lamp to inform the operator of the present or impending condition. The manual switch buffer and logic circuitry shown in FIG. 23 is also fairly self-explanatory in that the system allows only one mode flip-flop to be set at a time. The system essentially comprises the six main control switches, the switch buffering flip-flops, the gates which permit only one control flip-flop to be set at a time, and the exclusionary control flip-flops inlcuding gates 996, 997, 998, 999, 1000, 1001, 1002 and 1003. The power up reset 973 resets the entire logic of the transporter when the run or set switch in the pipette module is operated. Rferring now to FIG. 25, the automatic switch buffer and ejection logic system, the system contains a tube sensing switch 1034 and 1032 for the front row and a tube sensing switch 1035 and 1033 for the rear row on the rack. The signal goes through a switch buffer comprising gates 1038 and 1040 and provides a "tube-present" signal. The rack sensing switch 1042, the tip up sensing switch 1051, the toggle tip switch 1059, the ejection motor cam switch 1067, the rack limit switch 1074 and the advance motor cam 1081 are all contacted by moving parts within the apparatus itself and the signals produced by the switch go through switch buffers and provide signals to the other circuits. In the case of the ejection motor cam switch 1067 and the rack limit switch 1074, the signals, after buffering, are combined in OR gate 1087 and provide an ejection signal at terminal 1090 and an ejection motor driver signal at 1089. The particular ejection mechanism is not shown as previously stated but is simply a solenoid and motor operated mechanism which operates two thrust push rod rack ejectors 55 and 54, as shown in FIG. 1, outwardly to eject the rack along surface 5.

Referring now to FIG. 26, the malfunction and alarm logic circuitry, gates 1177 and 1180 comprise a buzzer flip-flop which is set by means of gates 1174 and 1175. The output of the buzzer flip-flop is fed to gate 1163 which is wired as an OR gate to give a buzzer drive signal at terminal 1172. Gates 1128 and 1129 comprise a latching switch buffer for the tray open switch 1125. Similarly, gates 1133 and 1134 comprise a latching switch buffer for the advance jam switch 1130. When a tray open signal or an advance jam signal occurs, they appear at terminals 1173 and 1182 respectively to connect with the lamp driver circutriy for malfunction indication purposes. These signals are also OR gated together by gates 1174 and 1175 to set the buzzer flip-flop and give a malfunction signal at terminal 1183. This is the malfunction signal which acts to prohibit other portions of the circuitry in the apparatus from operating. The latching switch buffers are reset by reset signal via gate 1120 after the malfunction condition has been cleared. The reset signal also resets the buzzer flip-flop at gate 1180 to silence the buzzer.

The buzzer also sounds by the means described below to indicate the completion of rack processing. After a rack has been ejected from the processing area and no more racks are to be processed, gate 1116 sets the completion flip-flop containing gates 1122 and 1123. When the completion flip-flop is set, gates 1150 and 1162 are enabled and a pulse from gate 1154 sets the timer flip-flop for timer 1160. Timer 1160 is a 7-second timer which sounds the buzzer by means of gates 1162, 1163, and 1164. Upon the completion of the 7-second delay, timer 1160 starts timer 1170 and the buzzer is silent. Timer 1170 is a 35-second timer which allows the buzzer to operate intermittently. When the 35-second delay has elapsed, timer 1170 restarts timer 1160 via gate 1150 which, in turn, resounds the buzzer for 7 seconds. This process is repeated until the operator resets the completion flip-flop with a reset signal as at terminal 1119.

The phototransistor 1136 operates to produce a signal which is buffered by gates 1139, 1140 to produce a tape signal at terminal 1184. This signal is indicative of a low supply of tape and illuminates a lamp on the panel of the transporter.

The reel switch 1144 is actuated if one shuts the tray and if a take-up reel is in place. If a reel is not in place, the take up spindle will not run. The reel signal exits from the alarm logic circuitry at terminal 1185.

FUNCTIONS AND APPLICATIONS

The general operating function of the transporter as stated before is determined by the positions of the "auxiliary pipette" and "external control" select switches on the function control panel on the electronic module. There are the four switch combinations, in other words, both "off," either one "on" and both "on."

With the "auxiliary pipette" and "external control" switches off, the following combinations of operation are available: (1) a sample on the front tube row diluted with a single reagent into the back tube row; (2) a reagent dispensed in each tube row; or (3) one or two reagents dispensed in the back tube row only.

With the "auxiliary pipette" switch on and the "external control" switch off, the system is designed to operate in the arrangement shown in FIG. 30. The tube rack 1300 contains a front tube 1301 and a rear tube 1302 into which the tip 1303 (also shown in phantom lines in the front tube) is designed to enter. A double pipete unit comprising tubes 1304 and 1305 and a holder mechanism 1306 is arranged in fixed position on the transporter. These two tubes constitute the auxiliary dispensing pipette. Basically, the application envisioned here is the preparation of a sample in the tube 1301 diluted with a reagent 1 from the transporter pipette tip 1303 and with reagents 2 and/or 3 from the auxiliary pipette in tubes 1304 and/or 1305. The transporter pipette will be manifolded in a conventional way through a single tip moved by the tip mechanism. The auxiliary pipette utilizes a fixed tip 1304 or tips 1304 and 1305 mounted over tube 1302 in the rear row. The auxiliary pipette may use one or two pumps as required by the application. As shown, the fixed auxiliary tips 1304 and 1305 do not touch the tube well.

Referring now to FIG. 31, the device is shown adapted for the "external control" switch on and the "auxiliary pipette" switch off. This application requires the supply of a diluted sample to a readout instrument. It is assumed that either the "external control" unit or the readout unit will have means of aspirating or pumping the sample into the readout instrument. The transporter is provided with a twin tip shown as 1313 and 1314 in FIG. 31. Line 1316 connects with tip 1314 and is flexible and attached in turn to a valve 1317 which connects said line with the line 1318 going to a readout instrument. FIG. 32 shows a cross-sectional view of the twin tip. A is evidenced from FIG. 32, the two tubes may be molded as one having two passages. Basically, the rack 1310 contains a front tube 1311 and a rear tube 1312. The sequence of events is as follows: Valve 1317 is closed to tip 1314. The double tip enters the front tube 1311 is shown in phantom lines, picks up the sample therein and fills a diluting pump with a reagent. The tips move to position A in the rear tube 1312, and are wiped in transit. The sample and reagent are dispensed. Position A is preset by the potentiometer 37 on panel 36 of the logic control module. A fixed time delay of approximately 1 second is used to permit mixing and liquid motion damping. The tips 1313 and 1314 then move down tube 1312 into position B, as shown in the drawings, which position is established by an external control potentiometer as shown in the circuitry drawings. Valve 1317 then opens to tip 1314 and the diluted sample is aspirated. The aspiration time is set on a timer in the external control unit. The readout is triggered at a preset time in the aspiration cycle. Then valve 1317 closes. Valve 1317 can be three way to allow air flow through the readout instrument if desired. At this point, controls return to the transporter logic circuitry. The tips 1313 and 1314 are then removed from the rear tube and wiped and the transporter operation proceeds in the usual manner.

With the "auxiliary pipette" switch on and the "external control" switch on, the application is the same as just described except that the auxiliary pipette function allows the introduction of one or two additional reagents through the fixed tips such as 1304 and 1305 in FIG. 30 during the dispensing step of tips 1314 and 1313. In other words, the fixed pipette having the double tips shown in FIG. 30 can be used with the double-core tip shown in FIG. 31.

With the "auxiliary pipette" switch off and the "external control" switch on, the transporter is adapted for other readout instruments providing minimum sample carryover and rapid sample feed to the instrument. In this configuration, the rear tubes in the rack such as 1320 in FIG. 33 are omitted and a fixed cup such as 1332 is installed in the transporter on a mounting such as 1323. The transporter has a single movable tip 1323 for sample and diluent. The external control package is provided with a diaphragm pump 1335 to pump a solution through valve 1334 and fixed tip 1333 for rinsing cup 1332 and is also provided with a four-way valve 1329. Support 1323 has an aperture 1324 in the base thereof through which a connecting stem 1325 runs to connector 1326. A pipe 1327 runs from connector 1326 through valve 1328 and then on to valve 1329. Conduit 1330 runs to the readout instrument such as a flame spectrophotometer; conduit 1332 is the drain conduit, and conduit 1331 is the vent conduit.

In operation the sequence of events is as follows. Tip 1323 picks up a sample from the front tube 1321 and the dispensing pump (not shown) is filled. Valve 1328 is in the closed position and valve 1329 is in the position which connects the analysis instrument or conduit 1330 to vent and the cup line 1327 to the drain line 1332. Then tip 1323 moves to fixed cup 1332, is wiped in transit, and discharges the sample and diluant. A short time delay is provided for mixing and motion damping and is approximately one second. The external control logic then takes over and initiates the following functions. Valve 1328 opens for a preset time A allowing the diluted sample to flush line 1327 between cup 1332 and valve 1329. Then valve 1329 is shifted to connect the cup 1332 and the analysis instrument connected to conduit 1330. Diluted sample is aspirated into the analysis instrument for a preset time B and the instrument readout is triggered. Valve 1329 shifts then to connect the conduit 1330 to vent conduit 1331, allowing the aspirator to clear the connecting line up to valve 1329. The diaphragm pump 1335 then pulses to rinse the fixed cup 1332 and the line 1327 between the cup and the drain conduit 1332 clears by gravity flow. At this point, valve 1328 is again closed and control is returned to the transporter and normal operation proceeds. Tip 1323 is removed from the fixed cup and is wiped. The rack then advances the next sample tube and the operation is repeated.

While the one embodiment of the tip and wiper mechanism and solid state circuitry has been shown and described, it will become apparent to those skilled in the art that many changes and modifications may be made to the apparatus and circuitry without departing from the scope of the appended claims.

Claims

We claim:

1. An apparatus for selectively or automatically processing racks, each having a row of liquid sample-containing tubes and a row of additional tubes either empty or containing suitable re agents, said rows being adjacent so as to form pairs of tubes, said apparatus comprising a base member having a supporting surface divided into a rack-loading area to receive loaded racks for processing, a rack-advancement area, and a rack-ejectment area, rack-advancement means adjacent said rack-advancement area to advance a rack along a linear path from an initial position adjacent the loading area to a final position adjacent the ejectment area, liquid sampling and dispensing means, conduit means in communication with said sampling and dispensing means, an aspirating and dispensing tip means above the path and connected to said conduit means, said rack-advancement means being constructed and arranged to advance said racks incrementally to position successive pairs of tubes under said tip means, tip-moving means comprising means for shifting the tip means to and fro between two positions corresponding to those of a pair of the tubes in a rack, and means for raising and lowering the tip means in a straight line at the two positions, rack-ejection means adjacent said final position for ejecting a processed rack from said path in a direction transverse to said path into said rack-ejectment area, means for feeding the racks in the loading area successively into the initial position of the path by moving said racks transverse to said path in a direction opposite that of ejectment, and control means for coordinating the operation of said liquid sampling means and dispensing means, said rack-advancement means, said tip-shifting means, said tip raising and lowering means, and said ejection means.

2. An apparatus as in claim 1 wherein said tip-shifting means includes a driven grooved cylindrical cam means and a cam groove follower means adapted to ride in a groove of the cam means to control the position of said tip means.

3. An apparatus according to claim 2 in which the cylindrical cam means has two peripheral cam grooves and the follower means comprises a separate follower for each cam groove and a snap-action lever, connected at each of its ends to a separate one of the followers, for alternately bringing a follower into its respective groove, each groove having a portion which raises the follower therein and rocks the lever to its snap-action position, thereby causing the other follower to engage the other groove.

4. An apparatus as in claim 3 including a bidirectional tip motor, said control means adapted to rotate said motor in either direction, one direction of rotation adapted to move said tip downwardly and the other direction of rotation adapted to move said tip upwardly.

5. An apparatus as in claim 4 and further including a switch cam having a pair of lobes located adjacent said cylindrical cam, said cylindrical cam having an actuator bar thereon which is adapted to engage one of said lobes upon rotation in either direction.

6. An apparatus as in claim 1 wherein said tip-moving means includes a pair of guide rods and a cam means to move said guide rods longitudinally to a first and second position, tip holder means mounted on said guide rods, said tip means being located in said tip holder means, and a cross slide assembly means associated with said tip holder to move said tip holder and said tip means down and up along said guide in both said positions.

7. An apparatus as in claim 6 and including a drive means for rotating said cam means, a crank means associated with said drive means and operatively in engagement with said cross slide means to effect downward and upward displacement of said cross slide means and said tip holder when said cam means is rotated.

8. An apparatus as in claim 7 and including a cam follower toggle means, said toggle means having two cam followers and said cam having two cam grooves therein, said toggle means adapted to toggle when one of said cam followers rides out of one of said cam grooves and thus to force the remaining cam follower into the other cam groove.

9. An apparatus as in claim 7 wherein said crank means has a top dead center cam on one end thereof, a switch means, said top dead center cam means adapted to engage said switch means when said cross slide assembly and said tip holder are in a predetermined position for either aspirating or dispensing.

10. An apparatus as in claim 1, and including a rack bar means adapted to bias said racks into advancement position on said surface means.

11. An apparatus as in claim 1 wherein said liquid sampling and dispensing means comprises a pair of pump units, each pump unit having a piston and a common driving means for driving the pistons of each said pump unit in a sinusoidal reciprocal manner, each pump unit having at least two port bores thereon and valve means associated with said common driving means and said port bores to alternately place the chamber of each pump unit in communication with one of said port bores respectively.

12. An apparatus as in claim 1 and additionally including means for wiping said tip means as it is moved upwardly by said tip raising and lowering means in each position.

13. An apparatus as in claim 12 wherein said wiper means includes a supply reel of wiper tape and a take-up reel for the wiper tape and a driving spool means for advancing the wiper tape.

14. An apparatus as in claim 13 wherein said tip wiper means also includes a pair of pad means and means to press said wiper tape against the sides of said tip means as it is being raised in either position to effect a wiping thereof.

15. An apparatus as in claim 13 wherein said wiper spool driving means includes a plurality of peripheral projections adapted to penetrate said wiper tape.

16. An apparatus as in claim 12 including a drive means for operatively effecting rotation of said wiper spool drive means upon upward motion of said tip means.

17. An apparatus as in claim 1 wherein said control means includes a malfunction and alarm circuit means, said malfunction alarm circuit means including a buzzer which is adapted to sound for a predetermined period of time upon the completion of processing and then remain silent for a second period of time and again sound for said first predetermined period of time whereby said cycle is repeated until an operator shuts off the apparatus.

18. An apparatus as claimed in claim 1 including wiper means for wiping said tip during its upward movement out of said tubes, said wiper means including a supply reel of wiping tape, and said control means having a circuit means to prevent said apparatus from functioning if there is no supply reel in place.

19. An apparatus as in claim 1 and including wiper means to wipe said tip, said wiper means being mounted on a tray or drawer which may be pulled outwardly from the apparatus into open position for servicing, said control means including a malfunction circuitry means adapted to shut down the operation of the machine if the tray is in open position or if a jam occurs in the rack advancement means.

20. An apparatus as in claim 19 wherein said wiper means includes a reel supply of tape, and said control means has a photoelectric means which gives a signal to the operator if the supply of tape is low.

21. An apparatus as in claim 1 wherein said control means includes automatic switches for sensing the presence of a rack, sensing the condition of the tip being raised, sensing the presence of tubes on both rows on said rack tray, and sensing when said rack is through being porcessed.

22. An apparatus as in claim 21 wherein said control means additionally includes means for providing an ejection pulse, an ejection apparatus, said ejection pulse operating to allow said ejection apparatus to eject a processed rack onto said surface means.

23. An apparatus as in claim 1 wherein said control means has circuitry providing for an automatic mode wherein said tubes are sequentially processed and the rack advanced incrementally.

24. An apparatus as in claim 23 wherein said control means additionally includes a manual mode circuit by which an operator can perform one sampling and dispensing apparatus at a time.

25. An apparatus as in claim 24 wherein said control means also includes an advance mode circuit and means to advance continually the rack without allowing the pipette and tip means to process any of the tubes contained therein.

26. An apparatus as in claim 25 wherein said control means additionally includes a pipette mode circuit means adapted to allow an operator to operate the pipette without operating the tip or liquid sampling and dispensing means.

27. An apparatus as in claim 26 wherein said control means has an exclusionary circuit means allowing only one of said modes to be operated at a single time.

28. An apparatus as in claim 1 wherein said control means includes circuit means adapted to prevent processing or operation of the apparatus before the rack is in a correct position, the pipette is in correct pumping sequence, before and when there is no malfunction signal present.

29. An apparatus as in claim 1 wherein said control mans includes an advance circuit means which will advance the rack until tubes are sensed by said control, means, this allowing for a partially filled rack to be processed.

30. An apparatus as in claim 1 wherein said control means includes a binary shift register and solid state controls, the shift register acting to automatically operate the control means to provide a predetermined sequence of operation with appropriate times and time delays therebetween.

31. An apparatus as in claim 30 wherein said control mans includes a START switch means which is adapted, upon being held in depressed condition, to provide automatic processing and stepping of said shift register.

32. An apparatus as in claim 1 wherein said tip raising and lowering means includes a tip motor means, the length of time of rotation of said motor in either direction controlling the depth of stroke of said tip means, said control means providing that rotation of said motor means in one direction allows said tip to move downwardly in both front and rear positions and rotation of said motor in an opposite direction allows said tip to move upwardly in both front and rear positions.

33. An apparatus as in claim 32 wherein said control means has manually adjustable timer means to control the amount of rotation of said motor means in either direction, thereby determining the depth of stroke of said tip means in both said positions.

34. An apparatus as in claim 32 wherein said control means includes a circuit means adapted to first reverse said motor means, provide a predetermined delay period to allow the dynamic braking of said motor to take effect, switch the contacts on said motor, provide a second time delay of a predetermined amount of time and finally to start said motor rotating in an opposite direction.

35. An apparatus as in claim 1 wherein said control means has an external select switch adapted to allow an operator to control the operation of the transporter externally, said control means also having an external potentiometer means, said control means including two timing means, said first timing means adapted to provide a delay to allow the reagent to mix with a sample after it has been dispensed above the level of the sample in the tube and said second timing means adapted to provide a pulse to said tip raising and lowering means to move the tip down below the level of said mixed reagent and sample in the same tube, said potentiometer providing adjustment ot said timer whereby an operator may select the depth of additional stroke which the tip moves down into said tube.

36. An apparatus as in claim 1 wherein said liquid sampling and dispensing means includes a control circuit, said control circuit, when activated, providing power to said control means for the entire apparatus.

37. An apparatus as in claim 1 wherein said control means includes circuit means to operate an auxiliary pipette or liquid sampling and dispensing means which can be used in conjunction with said liquid sampling and dispensing means.

38. An apparatus as in claim 37 wherein an auxiliary pipette is provided on said liquid sampling and dispensing means and is attached thereto in fixed position so as to be in a position to dispense into the tubes in one row on said rack.

39. In an apparatus for transferring liquids with respect to containers, especially test tubes, comprising a base, means for incrementally moving a holder or rack having a plurality of receptacles for the containers longitudinally along a path over the base from an initial station to a final station, a movable nozzle or "tip" above an intermediate station along the path, positive-displacement pump means comprising a piston reciprocable in a cylinder having a port for passage of liquid, a flexible conduit connecting the port with the tip for communication therewith, means for moving the tip relative to the base, and control means for coordinating the operation of the several means,

the improvement wherein:

the rack has two rows of receptacles for the containers extending longitudinally of the rack,

the means for moving the tip comprises (1) means for moving it back and forth transversely of the rows from a position over a receptacle in one row of the rack to a position over a receptacle in another row of the rack and (2) means for lowering and raising the tip in each of its positions, and

the control means is constructed and arranged to perform one or more cycles, each cycle including the following steps in the order recited:

the rack is advanced in its path to bring a receptacle in one of the rows under the tip, at which time the rack-advancement-ceases,

the tip is moved down into the container under the tip,

the piston is moved through one of its alternate strokes while the tip is in the container,

the tip is raised out of the container,

the tip is moved transversely of the rack to a position over a receptacle in the other row,

the tip is lowered into the container under the tip,

the piston is moved through the other of its alternate strokes,

the tip is raised out of the container, and

the tip is moved transversely back to a position over the first row.

40. In an apparatus for transferring liquids with respect to containers, especially test tubes, comprising a base, means for intermittently moving a test tube holder or rack longitudinally along a path over the base from an initial station to a final station, a movable aspirating and dispensing tip above an intermediate station along the path, positive displacement pump means comprising a piston reciprocable in a cylinder having a port for inlet and outlet of liquid, a flexible conduit conecting the port with the tip, means for lowering and raising the tip relative to the base, and control means for coordinating the operation of the several means, the improvement wherein: the apparatus also comprises means for wiping the tip comprising a rotatable reel carrying a wound supply of an absorbent wiping material in the form of a tape of indefinite length, a driven take-up reel for the tape, means for guiding the tape from the supply reel to the take-up reel along a path adjacent the path of the tip, and means for pressing the tape into wiping engagement with the tip whenever the latter rises.

41. In an apparatus for transferring liquid with respect to containers, especially test tubes, comprising a nozzle, a plurality of receptacles, pump means, a flexible conduit connecting the pump means to the nozzle for communication therebetween, means for moving, relative to one another, the nozzle and the receptacles including means for raising and lowering the nozzle in a path relative to the receptacles, the improvement wherein there is provided nozzle-wiping means comprising a rotatable reel carrying a wound supply of absorbent wiping material in the form of a tape of indefinite length, a driven take-up reel for the tape, means for guiding the tape from the supply reel to the take-up reel along a path adjacent the path of the nozzle, and means for pressing the tape into wiping engagment with the nozzle.

42. Apparatus according to claim 41 comprising means for actuating the pressing means in response to upward movement of the nozzle.

43. In an apparatus for transferring liquids with respect to containers, especially test tubes, comprising a rack having a plurality of receptacles for supporting containers therein, a nozzle, means for intermittently moving the rack to position the receptacles successively under the nozzle, pump means, and a flexible conduit connected to the pump means and the nozzle to provide fluid intercommunication therebetween, an improved nozzle module unit comprising a support, stationary, vertically extending guide rods secured to the support, a cross-head slidably mounted for motion up and down on the guide rods, a rotatable crank arm having a roller secured thereto and projecting into a guideway in the cross-head, means for rotating the crank arm, and means secured to the cross-head for supporting the nozzle to move it up and down with the cross-head.

44. Apparatus according to claim 42 in which the nozzle module unit also comprises a pair of guide bars inclined to both vertical and horizontal and the nozzle-supporting means is a holder slidable up and down the guide bars.

45. Apparatus according to claim 52 in which the nozzle module unit also comprises a pair of normally spaced-apart sponge rubber pads and means for moving the pads towards each other and gainst the nozzle as it moves upwardly.

46. Apparatus according to claim 42 in which the nozzle module unit also comprises a pair of guide bars inclined to both vertical and horizontal and the nozzle-supporting means is a holder slidable up and down the guide bars, and the module unit also comprises a pair of sponge rubber pads, mounted on rods slidable transversely with respect to the lower ends of the inclined guide bars, spring means for normally holding the pads in an opposed but spaced relationship with each other, and means for urging the pads together against the nozzle when the nozzle moves upwardly.

47. Apparatus according to claim 46 which also comprises means for shifting the inclined guide bars back and forth between two positions so that lowering of the nozzle holder lowers the nozzle into different containers supported in the receptacles of the rack under the two positions and the means for urging the pads together is effective to press them against the nozzle in both positions.

48. Apparatus according to claim 47 in which the means for urging the pads against the nozzle comprises a pair of arms pivotally mounted on parallel horizontal axes and rotatable cam means for swinging the arms on their pivotal axes.