Patent GB-1170237-A (GB)
Title: Chart Recorder.
Inventor: FORD MICHAEL ALAN
IPC: G01D15/24
Filed: 1965-11-29
Abstract: 1,170,237. Recording-apparatus. PERKINELMER Ltd. Nov.29, 1966 [Nov. 29, 1965], No. 50610/65. Heading G1J. [Also in Division F2] Recording-apparatus comprises a support 2 for holding a recording chart 1 in repeatable register, a holder H for a marking device S for producing a trace on the chart 1, mechanism 3 enabling relative movement between the support 2 and holder H in a direction A to represent a first variable, means M for displacing the holder H in a transverse direction to represent a second variable, drive means 5, 8, 16, 19, for actuating the mechanism 3 in response to the first variable, and, to enable independent positional adjustment of the first variable and the mechanism 3, a coupling 20, 21 interposed between the drive means 19 and the mechanism 3, the coupling including positive mechanical interference between co-operating faces of two means, B, 22, movable with the driving and driven parts 20, 21 respectively. Applied to a recording spectrometer, the independent variable (wave number) is represented by movement of the chart 1 in direction A, while the stylus holder H is reciprocated along rails (R) by a servomotor (M) in response to the dependent variable (e.g. transmittance). During a scan the wave number can be read on a dial D. A motor 5, under control of a programmer 10, drives a shaft 8 for driving both a grating scan mechanism 9 (including a mechanical function generator and grating changer) and also sprocket shaft 3 when the coupling is engaged upon energization of an electromagnet 23. The coupling plate 20 drives the coupling arm 21 when a pin 22, reciprocable in the arm 21, mechanically interferes with a hole in the plate i.e. when the pin registers with a hole and is pushed by a strip 27 captive on the pin and coupled to a collar 26 pressed by a lever 25 against a return spring 28. The plate may have a single hole B or a plurality of equispaced holes (the spaces corresponding to an exact number of sprocket teeth) defining take-up positions corresponding to equal discrete displacements of the chart and of angular travel of a gear 7, secured to the shaft 8 and carrying a finger 13. The finger 13 actuates limit switches 11 and 12 or 14 to send limit signals to the programmer 10 for controlling the motor 5 and electromagnet 23. Manual adjustment of the chart position can be made by pressing a knob 4 against a spring 29 to open a micro-switch in series with the electromagnet 23 to release the pin 22 from a hole in plate 20 and then rotating the knob. Operation in two modes is described. In the first the wave number range 4000 - 1250cm<SP>-1</SP> is covered in one full scan travel without a grating change, a signal derived from switch 12 causing de-energization of the electromagnet 23 so that the chart can be held stationary while the scan drive runs back and then a signal from switch 11 causing re-energization and re-coupling. In the second mode, after a partial scan travel from 4000 - 2000cm<SP>-1</SP>, the switch 14 initiates a succession of events; de-energization of electromagnet 23 for the chart to be held stationary under the stylus S at the 2000 mark, while the scan drive runs back and the grating is changed, so that when the switch 11 re-couples the chart to the scan drive for a full scan travel for the range 2000 to 625cm<SP>-1</SP>, the trace is resumed at 2000 without risk of any shift along the wave number scale.