SU802856A1 - Moisture-content measuring method - Google Patents

Description

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The invention relates to a measurement technique and can be used for measuring and automatically controlling humidity in the textile, chemical, metallurgical, mining and industry.

There is a known method for measuring humidity, consisting in irradiating an object of study with measuring and reference light fluxes and in recording the ratio of output light fluxes | JQ.

There is also known a method for measuring humidity by irradiating an object of study with a measuring luminous flux with a spectrum corresponding to the maximum absorption of moisture, and a reference flux with a spectrum corresponding to the minimum of absorption of moisture, and recording the output light ratio 2l.

The disadvantage of this method is low accuracy due to the nonlinearity of the light characteristics of photodetectors operating in a wide dynamic range.

The purpose of the invention is to improve accuracy.

The goal is achieved by the fact that the reference luminous flux varies in time according to the exprescent, and the humidity is judged by the length of time between the beginning of the change and the moment of comparison of the reference and measuring luminous fluxes.

The drawing shows a block diagram of a device that implements the proposed method.

The device contains the master oscillator 1, the first trigger 2, the functional unit 3 pulse power supply, the pulse power supply unit 4, emitters 5 and 6 with wavelengths I, j and l controlled object 7, the photodetector 8, the differentiating device 9, the second trigger driver Yu, a matching logic circuit 11, a third trigger 12 with separate inputs, a logic key circuit 13, and a pulse counter 14.

The device works as follows. The controlled object 7. is irradiated with two oj ;, OT) reference and measurement 1 wavelengths, respectively. .. The fluxes of Fz and Fd passed through the object are equal to I% and L4. VYl - mass of substance} Ш 2 - mass of moisture; K & Ko, the absorption coefficients at lengths of warriors I and I C The flux on the reference length bonHHj varies in time exponentially, i.e. H F. A g moment of equality noTMioB -. ,, and Cf A / t L g-K, m, f. G-Kam. e. Ф „,, д. From this expression it follows that С i is the time corresponding to the time from exponential to the exhibiting time. The master oscillator I generates a periodic investigation of impulses entering the input of flip-flop 2. antiphase outputs of the last TF and carbon pulses are applied to the input functional block 3 pulsed power and to block 4. Rectangular imps in the functional modular block for exponential curves. Through emitters 5 and 6, connected to the outputs of the power supply units, currents flow, which cause proportional radiation at wavelengths D and We assume that the flux is dependent on the linear current. This is characteristic of gallium emitters. In the IOM case, the current must be modulated ak, so that, taking into account the nonlinearity of the radiative characteristic, the amplitude of the radiation pulses can also vary exponentially. The streams passing through the controlled object at the reference and measuring wavelengths (I and I 2 are summed up and fall on the photosensitive surface of the photodetector 8. Next, the photoelectric signal is fed to the input of the differentiating device 9, from the output of which it enters the trigger trigger ffmirovater 10, and then - one of the inputs of the logic circuit 11 matches the other input of the latter with a signal from the output of flip-flop 2. When the phase of the total flow changes and, consequently, the photoelectric signal at the output of the laser circuit We receive a signal at trigger input 12 with separate inputs. This trigger is triggered and remains in that position until the Reset signal (the beginning of the exponential flow) is received from the pulsed power function block. and the prohibition signal from its output is fed to the input of the logic key circuit 13, then the last pulse does not arrive at the input of the pulse counter 14. From the moment of the beginning of the next expired-modulated signal, the trigger 12 is reset via the logic circuit 13, the counting pulses from trigger 2 are fed to the input of pulse counter 14. As soon as the phase of the total photoelectric signal changes, the trigger 12 closes the power circuit 13 and the counting stops. At the end of the exponentially missed signal from block 3, the Reset signal is sent to the pulse counter 14 and the counter is prepared for the next cycle. Thus: by the number of pulses recorded in the counter, you can determine the value of humidity. The proposed method allows to increase the accuracy and reliability of the measurement and to present the output information in a discrete (digital) form. Formula of Invention A method for measuring humidity by irradiating an object of study with a measuring luminous flux with a spectrum corresponding to the maximum absorption of moisture, and an operatic flux with a spectrum corresponding to the minimum of moisture, and recording the output light flux ratio, characterized in that the luminous flux varies with time exponentially, and the humidity is judged by the length of time between the beginning of the change and the moment of the reference and measuring light fluxes at . Sources of information taken into account in the examination 1.US Patent N 3851175, cl. q 01 N 21/00, published 1977. 2. The US patent Ms 3551678, cl. q 01 N 21/00, publ. K. 1976 (prototype).

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Claims (1)

Formula of the invention A method of measuring humidity by irradiating an object of study 802056 with a luminous flux with a spectrum corresponding to the maximum absorption by moisture and the reference beam. - with a spectrum corresponding to the minimum absorption by moisture and recording the ratio of the output light flux, characterized in that, in order to increase accuracy, the reference light flux is changed exponentially in time, and humidity is judged by the length of time between the beginning of the change and the moment of comparison reference and measuring light fluxes.