RU2548735C2 - Food products quality express evaluation device - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: food products quality express evaluation device includes piezoelectric converters with probes, a high frequency generator, a low frequency pulse generator, a mixer, an amplifier, an output signal converter and an information display unit. The mixer is designed so that to enable generation of a signal at the output for shear surface waves excitation. For this purpose, the first input is connected to the low frequency generator via a former of pulse impact designed so that to enable low frequency rectangular pulse supply; the second input is connected to the output of the high frequency sinusoidal oscillations generator. A meter is connected to a binary-decimal decoder the output whereof is connected to the information display unit, the unit designed in the form of a liquid-crystal indicator. The mixer output is connected to the first converter (from the five converters) placed in the contact head centre and being the source of shear surface waves the receivers whereof simultaneously represent the four other converters (installed along the circumference at an identical distance from the central one) the outlets whereof are connected to the amplifier in the form of a summing amplifier. The amplifier is connected to the output signal converter including an integrator connected to the input of the Schmitt trigger the output whereof is connected to the trigger input for stopping counting.

EFFECT: quality evaluation simplification and reliability improvement.

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Description

1. The technical field to which the invention relates.

The invention relates to analytical equipment designed to determine the properties, composition and structure of substances in industrial production and in scientific research.

2. The level of technology

Existing methods of food quality analysis use standard modern analytical techniques, such as gas chromatography, high performance liquid chromatography, mass spectrometry; the use of a variety of chromatographic detectors. These methods are very laborious and time consuming.

As analogues of the proposed device are considered technical means for measuring viscosity. The following can be attributed to analogues: technical means of viscometry, which allow estimating the viscosity of liquid media in accordance with the hydrodynamic theory, and technical means based on measuring the propagation velocity of a surface acoustic wave over the surface of a tissue under investigation (ultrasonic viscometry).

Closest to the claimed device is a device whose operating principle is based on measuring the propagation velocity of a surface acoustic wave over the surface of a tissue under investigation. The disadvantage of the analog device is the presence of only two piezoelectric transducers, which makes it difficult to register surface shear waves due to their rapid attenuation, on the one hand, and the need for measurements for small displacement amplitudes of the particles of the medium under study, on the other.

3. Disclosure of invention

A distinctive feature of the proposed device is that the contact measuring head, superimposed on the test surface, contains five piezoelectric transducers with probes. One of them, located in the center, is a source of surface shear waves, and the remaining four transducers, mounted around a circle at the same distance from the first, are receivers of these waves (Fig. 1). This provides spatial and temporal summation of oscillations, which increases the sensitivity of the device, noise immunity and reliability of measurements. In addition, the device is compact, wearable, with low current consumption and with an autonomous power source.

The developed device is based on a method for assessing the viscoelastic properties of a biological tissue, based on measuring the propagation velocity of a surface shear wave in it. Unlike longitudinal acoustic waves propagating in the medium volume, surface shear waves decay at a distance equal to several wavelengths, which creates certain difficulties in studying the features of their propagation. These waves are obtained and recorded using bimorph type transducers, in which plates of piezoelectric material are used. The transducers are equipped with probes that allow for point contact with the tissue site to be examined. Studies show that the shear elasticity of biological tissues for small amplitudes of displacement of the particles of the medium is directly proportional to the square of the propagation of an acoustic wave excited by a point oscillating transducer in it:

E = ρkc ² ,

where E is the dynamic shear modulus; k is the coefficient of proportionality, depending on the direction of the vibrational displacement of the particles of the medium; ρ is the density of the medium; c is the shear wave propagation velocity.

4. Brief Description of the Drawings

Figure 1 shows the contact measuring head. The structural diagram of a device for rapid assessment of food quality is presented in figure 2.

5. The implementation of the invention

The device operates as follows. On the surface of, for example, meat, the contact head of the measuring transducer is superimposed (Fig. 1, 1 - probe of the piezoelectric transducer; 2 - piezoelectric transducers; 3 - lead cable). The contact head includes five transducers (ПП1-ПП5) 9-13 with probes at the ends for contact with meat, one of them (ПП1) 9, located in the center, is a source of surface shear waves, and the rest, mounted around a circle on equal distance from the first, are the receivers of these waves. This provides spatial and temporal summation of oscillations, which increases the sensitivity of the device, noise immunity and reliability of measurements.

When the “Start” button is pressed, the pulse counting (MF) 5 from the generator (GIS) 2 occurs (see FIG. 2). From the output of the binary-decimal counter (MF) 5, the pulses are fed to the decoder (DS) 7 and to the four-digit liquid crystal indicator (LCD) 14 for visualization. At the same time, an envelope of radio pulses of power supply to the central piezoelectric transducer (PP1) 9 is formed at the output of the shaper (PIV) 4. Power pulses are formed at the output of the mixer (C) 6, to the second input of which high-frequency electric vibrations from the generator (HHF) 1 are supplied. Next, these pulses are fed to the input of the Converter (PP) 9, which excites shear vibrations on the surface of the meat. Depending on the viscosity of the meat, the speed of propagation of the surface wave has different values equivalent to the current viscosity actually recorded by this device. To do this, the electric signal from the output of the summing amplifier (SU) 15 is fed to the input of the integrator (I) 16 and then to the Schmidt trigger (TS) 17, where a pulse is generated, whose leading edge stops the count by means of the trigger (T) 3.

Information sources

1. Akopyan VB, Ershov Yu.A. Fundamentals of the interaction of ultrasound with biological objects: Textbook. allowance. M.: Publishing House of MSTU. N.E. Bauman, 2005 .-- 222 p.

2. Fridman F.E., Gundorova R.A., Kodzov M.B. Ultrasound in ophthalmology. M .: Medicine, 1989 .-- 254 p.

3. The article "Methods and technical means of assessing the quality of food" in Sat. scientific articles in the XXI International scientific-practical conference. - Penza: PDZ, 2011 .-- 120 s.

Claims (1)

A device for express quality assessment of food products, including piezoelectric transducers with probes, a high-frequency generator, a low-frequency generator, a mixer, an amplifier, an output signal converter, an information display unit, characterized in that the mixer is configured to generate a signal to excite shear surface waves, for which its first input is connected to a low-frequency generator through a pulse shaper configured to supply low rectangular frequency pulses and a second input connected to the output of high-frequency sine wave generator; the counter input is connected to a binary decimal decoder, the output of which is connected to the input of the information display unit, made in the form of a liquid crystal indicator; the mixer output is connected to the first converter of five, placed in the center of the contact head and being a source of surface shear waves, the receivers of which are four other transducers installed around the circumference at the same distance from the central one, the outputs of which are connected to an amplifier made in the form of a summing amplifier connected with an output signal converter including an integrator connected to the Schmidt trigger input, the output of which is connected to the trigger input to stop the count eta.

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