GB1149384A - Improvements in automatically operating photometers - Google Patents

Abstract

1,149,384. Photo-electric apparatus. JOYCE, LOEBL & CO. Ltd. May 2, 1966 [ May 7, 1965], No.19307/65. Heading G1A. The colour, density, concentration &c. of samples is measured by a photometer which examines the samples sequentially, means being provided for rendering the indicating or recording device, which displays the measurements, inoperative while one sample is replaced by another, and, for a time before the actual measurement is made, to allow the sample, if liquid, to settle into position. Liquid samples treated by reagents &c. as described in Specification 1, 149, 382 may be transferred in turn to the measuring cuvette 4 of the photometer by means of a pipette and pump mechanism Fig. 1 (not shown), described in detail in Specification 1, 149, 383. Alternatively, liquid samples contained in their own cuvettes may be passed on a moving belt or table, which is stopped for the period of test. Solid samples may also be evaluated, by transmitted or reflected light. In the embodiment described, the photometer is of the double-beam type, light transmitted through the sample 4 and through a filter 21 and graduated wedge filter 22, being allowed alternately to illuminate a photo-cell 25, by a rotary shutter 24. Any difference in the two intensities is detected by amplifier 26 and a motor 23 caused to move the wedge 22 to equalize the beams. Also controlled, through gearing 27, is the movement of a pen on the paper roll 7, and the setting of slider 29 on potentiometer 28, which feeds a print-out device 13. The latter can produce digital print-out with or without tape punching. Adjustable resistors 31 are used to set the upper and lower limits of the potentiometer. A plug-in printed circuit 35 can be inserted to alter the potentiometer characteristic in the case of a non- linear sample property, so that the record is linear. Alternatively, a non-linear wedge 22 is used. Calibration of the photometer is by an empty cuvette to set zero and standard solutions. The operation of the photometer is controlled by a timer 33. A first pulse over lead 36 starts the pumping and a first portion of the sample washes out the cuvette 4. The cuvette is then filled with the sample and when liquid has settled down, the paper 7 and the print-out device are started. The pen and paper are stationary while the sample is removed and the cuvette flushed with the next portion of sample, while the printout device is prepared for the next sample, by movement of its sheet 9. In an alternative photometer, a single beam path device is used, the sample being compared with a reference sample or the photometer output compared with a standard signal.