SU853416A1 - Digital photometer - Google Patents

Description

The invention is intended for automatic enrichment of complex mixtures and can be used in auto-whit systems of its control of the chemical production process and for work in the conditions of chemical-analytical laboratories of industrial enterprises and research institutions. An automatic spectrophotometer for the analysis of chemical compounds is known, comprising a modulator connected sequentially to the supervisor, a light channel switch, a monochromator, a radiation receiver and a digital counting controller. A software control electronic unit associated with a digital logic system, the outputs of which are through angle sensors. the figure and the drive with a stepped change in velocity are kinematically connected with the corresponding mechanisms for adjusting the spectrophotometer to set the wavelength, open the switch The light channels Q. The disadvantage of such an automatic spectrophotometer is that it lacks automatic calibration, which results in high accuracy of measurements. The closest to the technical essence of the invention is a photometer with a digital readout, containing an illuminator, a sequentially installed cuvette compartment, a photodetector, an amplifier, an analog-to-digital converter (ADC) connected by an output to the input of a switching unit, a unit for setting the reference level code, a counter, an output which is connected to the input of the digital counting device. Such a photometer allows calibration, but the presence of electro-mechanical control circuits in it reduces the measurement accuracy and reliability of operation. The aim of the invention is to improve the measurement accuracy and reliability of the device. The goal is achieved by the fact that in a photometer with a digital readout, containing an illuminator, a sequentially installed cuvette compartment, a photodetector and an amplifier, an ADC connected by an output to the input of a switching unit, a unit for setting the reference level code, and a counter whose output is connected to the input of a digital readout device, introduced

frequency multiplier, frequency divider and register. The first output of the switching unit is connected through a serially frequency multiplier connected to the unit for setting the reference level code, and the frequency divider is connected to the input of the counter, and its second output is connected to the input of the register, the output of which is connected to the frequency divider. The ADC input is connected to the amplifier output, and the cuvette compartment is connected to the illuminator.

The drawing shows a schematic diagram of the photometer.

The photometer contains a series-connected illuminator 1, cuvette compartment 2, photodetector 3, amplifier 4, ADC 5. The output of ADC 5 via switching unit 6 is connected respectively via frequency multiplier 7 connected to unit 8 for setting the reference level code to the first input of frequency divider 9 and through the register 10 - to its second input. The output of the frequency divider 9 through the counter 11 is connected to the device 12 digital readout.

The device works as follows.

Before starting the measurements, a sample with a known concentration of the element being determined (calibration) is installed in the cuvette compartment 2, as well as samples to be analyzed. Using the unit 8 for setting the reference level code, the operator sets the number K equal to the concentration of the calibration sample in the selected units. In this case, the multiplication factor of frequency multiplier 7, determined by block 8, becomes equal to K.

In the Calibration mode, the switching unit 6 is set to connect the output of the A / D converter 5 with the counting input of the register 10. The luminous flux of the light 1 passing through the calibration sample in the cuvette compartment 2 is sensed by the photo-receiver 3. The output signal of the photo-receiver 3 is amplified by the amplifier 4 and fed to ADC 5 input The information from the ADC 5 output in a sequential code goes to the register and after the calibration mode ends, it will contain a certain number L recorded that is proportional to the optical density of the calibration oh sample. Since the output of register 10 is connected to the control of the frequency divider 9, the division factor of the latter also becomes equal to L.

In the Measurement mode by the photodetector -3, the luminous flux passing through the analyzed sample in the cuvette compartment 2 is perceived, and the switching unit 6 is set to the position providing the connection of the output AC11 5 to the input of the frequency multiplier 7. The output pulses of the transform bodies 5, the number of which is proportional to the measured optical density and equal to M, are fed through successively included multiplier 7 s

multiplication factor and divisor

9 with the division factor L to the input of the counter 11. and the end of the measurement mode in the counter 11 is recorded a number equal to the concentration of the analyzed sample in the selected units of measurement М-К

which is 5 l

displayed by the digital reading device 12.

Thus, the exclusion in the claimed photometer of the electron-mechanical adjustment circuits in the calibration and measurement modes improves the measurement accuracy and reliability of the device.

Device with a new set

5 signs in comparison with the prototype provides an increase in the accuracy of measurement of at least 0.3%, which expands the area of its use.

Claims (2)

1. USSR Author's Certificate No. 376668, cl. G 01 J 1/44, 1973. 2. USSR author's certificate number 535469, cl. G 01 J 1/44, 1976 (prototype).