Patent GB-1301022-A (GB)
Title: Measuring system for an analytical centrifuge
IPC: G01N21/07
Filed: 1970-01-05
Abstract: 1301022 Photo-electric centrifuge monitoring NORSK HYDRO-ELEKTRISK KVAELSTOFAKTIESELSKAB 5 Jan 1970 [6 Jan 1969] 496/70 Heading G1A [Also in Division G2] The optical transmission of two or more sedimentation cells carried by a centrifuge rotor is investigated photo-electrically and displayed on a cathode ray tube. The apparatus used comprises a photo-electric scanning system producing electrical signals, representing optical transmission and which are applied to the vertical deflection coils of the C. R. T., a photo-electric or electronic sawtooth waveform generator supplying the horizontal deflection coils with signals representing the radial position along a particular cell, and a switching arrangement, selecting the cells to be displayed, supplying the electron gun. Photo-electric scanning system Fig. 1. A source 16 is associated with collimating lens 17 so as to illuminate fixed disc 18 having a preferably curved and adjustable slit such as described in Specification 1063057. This co-operates with a mirror 21 or prism to effect repetitive, sequential radial scans of sedimentation cells 12-15 as they pass through the zone of illumination provided by slit 19, the transmitted light being detected by photo-cell 22. Instead of a curved slit, a row of holes may be provided in the disc and the associated circuit include a diode pump and reset arrangement. If a large number of cells are to be carried by the rotor a rotating disc 24 having a sector cut out is introduced into the light path. This rotates at a lower speed than rotor 1 so that a complete radial scan of a particular cell is carried out only after a number of revolutions of the rotor. Sawtooth generator, Fig. 1. The horizontal deflection signals for the C. R. T. are provided by a further photo-cell 58 receiving repetitive radiation beams of increasing intensity synchronized with the scanning of the sedimentation cells. A disc 55 having rectilinear slits corresponding to the cells rotates in synchronism with the rotor through wheel 39, and is used in association with a fixed disc 53 having a curved slit 54 of increasing width. A disc 26 rotating in synchronism with disc 23 is added when a large number of sedimentation cells are carried by rotor 1. Switching system, Fig. 2 (not shown) comprises a triggering arrangement in the form of a disc (5) carried on rotor shaft 4, bearing a magnetic member (6) which on passing each of a number of induction coils corresponding to the number of sedimentation cells produces a pulse therein which is delivered to a network (45) in which the cells to be displayed are selected. The output of the network may include an amplifying and shaping multi-vibrator. Alternatively, a photo-electric triggering arrangement may be provided. Display format. The curves on the C.R. T. screen may be displayed in such a way as to be distinguishable e.g. using dots and dashes, By using a cell 12 with scale markings 29, Fig. 1, a radial distance scale may be displayed on the screen. This cell may be filled with a reference liquid without particles contained therein, to define the zero and 100% transmission values, Fig. 2 (not shown). A reference particle containing sample may also be carried in one of the displayed cells.