Patent GB-899534-A (GB)
Title: Apparatus for recording a plurality of cyclically repetitive time displaced signals
IPC: G01N30/86
Filed: 1958-12-24
Abstract: 899,534. Recording-apparatus. PERKINELMER CORPORATION. Dec. 24, 1958 [Dec. 26, 1957], No. 41740/58. Class 106 (4). Recording-apparatus, in which the amplitudes of signals are gated at predetermined intervals of time and recorded as bars and in which signals are provided for advancing the record strip by unit increments has means for switching to continuous advance of the strip while the gating means operate as before for the purpose of checking the timing of the gating means. An electric signal, whose amplitude varies with the concentration of the components of a sample being analysed by partition vapour chromatography, is applied to input terminals 15 of the system shown in Fig. 5 and is passed from output terminals 25 to recording-apparatus in which it determines the extent of recording in the ordinate direction on a strip, whose abscissa drive receives power from output terminals 27 derived from input terminals 16. The system comprises a five-bank selector switch 10 to 14 and two sets of time-controlled switches 36 to 42, 29 to 34, each set operating successively: 36, 29, 37, 30 . . . . Conventional chromatogram. With the wipers 17, 28, 26, 35, 24 in the first position, the ordinate signal is passed by wiper 17 to a set of attenuators 17-22 in parallel, from tap 23 to contact 1 of bank 14 and by wiper 24 to output 25; while power from terminal 16 is passed by wiper 26 to output 27 so that a co-ordinate record is made representing the percentage concentration against time. Bar diagram. From the chromatogram thus recorded the retention time of each component in the mixture is established and mechanical cam, electro-mechanical gating means or electronic switch means uniformly time-driven, are selectively adjusted to actuate each of the switches 36-40 at intervals appropriate to the times of elution of the components. Now, with the wipers in position 4, the ordinate signal is passed by wiper 17 to attenuator 17a, to be picked up by arm 36a when switch 36 is operated and passed from switch 42 to contact 4 and wiper 24 of bank 14, thence to output 25; while power from terminal 16 is passed by wiper 26 over contacts 4 of banks 12, 11, and wiper 28 to switch 29, which is operated a suitable interval after switch 36 to pass current through wiper 35 and contact 4 to terminal 27, thus driving the record strip a unit increment determined by the uniform interval for which each switch 29-34 is operated in turn. So long as the intervals for which the switches 36-40 are operated cover the corresponding peaks of the conventional chromatogram, the record drawn in position 4 will represent a bar diagram of component concentration. Verification. To check the timing of the switch operation, the wipers are set to position 2, thus switching over to continuous advance of the record strip with the ordinate gated as for the bar diagram but with the switches 29 to 34 introducing a negative potential from a resistor 45 in circuit with a battery 44 over contact 2 of bank 11 to the output terminal 25 to record the timing of these switches. Calibration. Switch positions 5 to 9 provide for calibration. A potentiometer 43 is tapped to match the amplitude of the first component recorded in the conventional chromatogram and the tap of attenuator 17 is adjusted to provide an appropriate full-scale reading and passes its signal to contact 5 of bank 14, thence to output terminal 25. The process is repeated for each position 6-9 and corresponding attenuator 18-21. Zero set operation. Position three provides for recording at uniform sensitivity. Specification 899,535 is referred to.