GB584507A - Improvements in or relating to automatic recording devices - Google Patents

Abstract

584,507. Spectrographs. ARNOLD, C. (Standard Oil Development Co.). May 31, 1944, No. 10469. [Class 97 (i)] [Also in Groups XXXVIII and XL] An automatic electrically operated recorder provided with a pen for transcribing values in the form of a curve recording the relationship of two variables, comprises a rotating shaft 12 having a toothed wheel 21 on which rides a pawl 22, an electric circuit containing a source of direct current 25 and a condenser 26 in series connected to the recorder and a switch 23, responsive to the movement of the pawl, in the circuit, between the source of current and the condenser, whereby the periodic operation of the switch causes a transient current to pass through the recorder and causes the pen to place a fiduciary mark on the curve. Applied to a recording spectrograph, Fig. 3, two beams of light from a source 1 pass through two cells 2a and 2b containing the substances under examination and a standard respectively, through a monochromator 3 and the two emergent beams fall on thermo-couples 4A and 4B, the current from which is amplified in units 5A and 5B and the voltage difference measured and recorded by a self-balancing potentiometer 7 as described in Specification 584,506 and a pen 9. The wavelength of the beams passing through the monochromator is varied by the rotation of the shaft 12 co-operating with a travelling nut and a mirror, Fig. 2 (not shown). As the shaft rotates, the pawl 22 drops from the top of one of the teeth causing a transient current to flow through the recorder giving a brief impulse indicated by a momentary excursion of the recorder pen.