Patent GB-1520745-A (GB)
Title: Liquid dispensers and pre-prepared multi-cell test trays
IPC: B01L99/00
Filed: 1974-10-14
Abstract: 1520745 Liquid dispenser UNILEVER Ltd 13 Oct 1975 [14 Oct 1974] 44493/74 Heading G1B An apparatus for dispensing liquid to wells 51  of a multi-well tray 50, has an array of nozzles 41 each connected to a respective one of an array of pumps 21, each pump operable to supply a predetermined quantity of liquid from a source 14, a support 46 for supporting a multi-well tray, and means for relatively moving the array of nozzles and the support between a first position, in which the nozzles and the support are spaced apart to permit loading and unloading of a tray on and off the support, and a second position in which the nozzles and the support are in proximity whereby each well 51 of a tray on the support is located to receive the predetermined quantity of liquid from a respective one of the nozzles 41. An embodiment of the apparatus comprises a frame mounting 11 and a support 12 for carrying twelve rows each of eight tubular containers 14, each having an outlet connector 16 attached to downpipes 18 whose lower ends are connected to an array of ninety six pumps e.g. peristaltic pumps 21. In Fig. 2, each pump 21 comprises three rollers 29 carried for free rotation by a cage 28 on a rotatable shaft 27. The roller axes 24 are parallel to and at equal radial distances from the axis 26 of the shaft and are spaced equiangularly from one another. The compressible tube 22 extends over a segment of the periphery of the case 20 for engagement with the rollers 29. An arcuate support 31 with an inner surface of the same diameter as the outer circular envelope of the path of travel of the rollers 29 is mounted to support the compressible tube 22 against the pressure of the rollers, of which at least two are within the arc of the support 31 at any time. The support 31 is mounted on a stem 32 the axis of which intersects the axis 26 and which extends away from the support through a tapped central aperture in a manually rotatable adjustment wheel 34 received in a part of the frame 11 substantially against axial movement. The compression spring 36 is received between a flange 38 on the stem 31 and an externally threaded washer 39 freely rotatably carried on the stem and meshing with the thread of the wheel 34. Rotation of the wheel 34 thus varies the spring tension to provide for fine adjustment. A screw-threaded portion of the stem 31 meshes with the thread of a second similarly arranged wheel 35, so that rotation of this wheel moves the stem and the support towards or away from the rollers 29 for coarse positioning and release of pressure on the tube 22. Each of the rows of twelve containers 14 in the support 12 has underlying it a shaft 27 with twelve of the cages 28 secured to it or a single elongated cage with twelve sets of rollers 29 spaced along rigid spindles supported by spaced rotors. The downpipes 18 of the containers are connected to the collapsible tubes 22 of the pumps 21. The outlet ends 23 of the tubes 22 extend down to double ended connectors 19 mounted on a generally horizontal support plate 20 carried by the frame 11  below the array of pumps 21. At the underside of the plate 20, flexible tubes 40 lead from the lower ends of the connectors 19 to the inlet ends of nozzles 41 having the form of hollow needles, the nozzles being mounted in a lower support plate 42 releasably secured within the frame 11 on inwardly projecting flanges by clips 45. The containers 14 and the array of pumps 21 occupy a larger area than the multi-well tray 50 the wells of which are to be filled from the nozzles 41 and it is necessary for the tubes 40 to convey the liquid doses from the outermost pumps 21 inwardly as shown. The nozzles 41 must register accurately with the wells of the tray 50 and the mounting of the plate 42 permits replacement so that the nozzles can be differently arranged for co-operation with a tray having different located wells. Spaced below the support plate 42 is support 46 having surface formations for correctly locating the tray 50 thereon with the wells 51 thereof beneath the nozzles 41. The support 46 is guided in the frame 11 for vertically reciprocable movement caused by eccentric drive rollers 48 carried on a shaft 49. The eight shafts 27 and the shaft 49 are linked by a chain and sprocket or other drive linkage 54 so that all the shafts can be driven together from a single power source 55. The operation of the pumps and the movement of the support 46 are co-ordinated so that a single dose of liquid is fed to the nozzles 41 for each upward movement of the tray 50.