CN103487508A - High-precision ultrasonic liquid difference identification device for food safety - Google Patents

Abstract

The invention discloses a high-precision ultrasonic liquid difference recognition instrument applied to food safety. The recognition instrument is composed of two pairs of detachable ultrasonic transceiver sensors, a signal processing chip, a display screen and buttons. The signal processing chip consists of a frequency and power adjustable transmitting circuit, a receiving circuit capable of noise reduction, amplification, oversampling and filtering, a sigma-delta AD modulator, an adjustable digital filter circuit, a high-speed memory and its access interface, Wireless transmission module, microprocessor and crystal oscillator. The recognition instrument distinguishes the difference of substances by extracting the signals of ultrasonic waves passing through the liquid with high precision, and comparing the signal characteristic values corresponding to different substances, and can effectively identify counterfeit and shoddy liquid foods in food safety. At the same time, although a single integrated chip is used to integrate more high-precision signal processing circuits, the area is small, which makes the identification device small and portable, and is suitable for individuals and families.

Description

A high-precision ultrasonic liquid difference recognition instrument applied to food safety

【Technical field】

The present invention relates to the fields of integrated circuit design technology, ultrasonic sensor application technology and food safety detection, and specifically relates to a high-precision ultrasonic liquid difference recognition instrument applied to food safety, combined with ultrasonic sensor technology, and realizes high-precision signal processing through integrated circuit design Thus, the authenticity of liquid food can be distinguished.

【Background technique】

In recent years, my country's food safety incidents have occurred frequently, which is shocking. Since food safety testing mainly uses biochemical analysis and spectral analysis methods, the process is complex and the equipment is huge, it needs to be carried out in a specific laboratory, and it is mainly supervised by relevant government departments. However, our country has a large population and a huge daily food consumption. The government cannot implement comprehensive and meticulous testing and supervision, so many unscrupulous traders can rampantly manufacture and sell counterfeit goods. Although the people of the whole country are deeply poisoned, they can only complain. Complaint, but not resolved. How to fundamentally solve the hidden dangers of food safety, we believe that a food safety inspection system that the whole people can participate in is needed, and what hinders people from conducting food safety supervision is that there is no widely used instrument that can identify counterfeit and shoddy products.

After investigation, it is found that the research on food safety testing in my country mainly focuses on the use of chemical means and spectral analysis, which is not suitable for ordinary people. At the same time, what people pay attention to is not the composition and content of a certain substance, which is too professional to be recognized and accepted by the public. People want an instrument to tell them whether it is false or true, whether it is good or good or bad, and they don't really care about the specific substance content. Therefore, the advantages of using non-chemical non-qualitative and quantitative identification physical means are reflected. For example, based on light, electricity, sound waves, etc., the non-destructive testing of the measured physics can be realized, which has certain value in the popularization of food safety instruments.

This patent is based on ultrasonic sensor technology. Ultrasonic technology is currently mainly used in ultrasonic technology. It is an acoustic characteristic analysis method. The principle is that when ultrasonic waves propagate in the medium to be detected, changes in the acoustic properties of the medium and internal tissues will cause ultrasonic waves to propagate. Certain impact, through the detection of the degree and condition of ultrasonic impact, we can understand the change of medium performance and structure. Due to its low energy, weak ultrasonic waves have the advantages of non-destructive, non-invasive, no need to prepare samples, and rapid detection. At present, they are mainly used in the detection of fat content in dairy products, the detection of sugar, and the detection of hydrocarbon mixtures in food products. Specific The detection of a certain ingredient has not appeared in the application of food comprehensive quality detection.

The invention proposes an ultrasonic liquid difference recognition instrument applied to food safety. The instrument mainly focuses on how to extract high-precision ultrasonic signals after passing through the liquid, and integrates various signal processing modules in combination with integrated circuit design technology. By comparing the characteristics of ultrasonic signals after passing through different liquids, different liquids can be distinguished. People can update the standard values of the ultrasonic signal characteristics of various liquid foods through the interface or wireless transmission and reception, so as to identify whether the purchased food is genuine.

【Content of invention】

The purpose of the present invention is to propose an ultrasonic liquid difference recognition instrument applied to food safety, which is suitable for the general population to carry out food safety detection.

In order to achieve the above purpose, the present invention proposes an ultrasonic liquid difference recognition instrument for food safety, which is composed of two pairs of detachable ultrasonic transceiver sensors, a signal processing chip, a display screen and buttons.

The distance between the ultrasonic transmitting and receiving sensors is adjustable, a pair of ultrasonic transmitting and receiving sensors are used for distance calibration, and a pair of ultrasonic transmitting and receiving sensors are used to detect the measured object; at the same time, in order to ensure that the distance between the two pairs of sensors is the same, the sensors on the same side pass A fixed shaft connection, so that it is in the same position;

The signal processing chip consists of an ultrasonic transmitting circuit with adjustable frequency power, a receiving circuit capable of noise reduction, amplification, oversampling and filtering, a high-precision sigma-delta AD modulator, a high-precision adjustable digital filter circuit, a high-speed memory and its Memory access interface, wireless transmission module, microprocessor and crystal oscillator;

The ultrasonic transmission circuit is composed of a frequency division circuit, a power adjustment circuit and a switch circuit, and its transmission pulse frequency and power can be set by a microprocessor; the ultrasonic energy is in the weak ultrasonic range and does not cause damage to the measured object;

The ultrasonic receiving circuit includes a bandpass filter for noise reduction processing, a signal amplification module, an oversampling and filtering processing module. Through the noise reduction and amplification processing of the signal, a high-quality signal can be obtained, and the original analog signal can be retained with high precision through oversampling and filtering processing;

The high-precision sigma-delta AD modulator can convert the oversampling signal into a digital signal, and keep higher resolution and signal-to-noise ratio;

The high-precision adjustable digital filtering circuit receives the signal from the sigma-delta AD modulator for filtering and signal restoration processing, and the filter parameters of the filter can be set by a microprocessor;

The high-speed memory is used to store signal characteristic values of different liquids after ultrasonic waves pass through at different temperatures, and to store current measurement values in real time. The high-speed memory can support the fast storage of a large number of signals after over-sampling processing, which can be accessed by the microprocessor and the memory access interface;

The memory access interface and the wireless sending module can send local data to other terminals or update data locally;

The microprocessor is mainly used for system control and signal analysis. System control includes setting each module according to user input, such as the pulse frequency and power of the ultrasonic transmitting circuit, digital filter parameters, and ambient temperature. At the same time, control the data to interact with other terminals through the access interface or wireless transmission module, start measurement and signal analysis, control display output, etc.; signal analysis mainly calculates the propagation speed, attenuation and impedance of the ultrasonic signal in the measured object based on the detection signal , and perform distance correction, and then compare these values with the corresponding standard values to obtain the authenticity, quality, and display of the measured object;

The key is the power switch.

The beneficial effects of the present invention are: the present invention proposes an ultrasonic liquid difference recognition instrument applied to food safety. The recognition instrument distinguishes the difference of substances by extracting the signals of ultrasonic waves passing through the liquid with high precision, and comparing the signal characteristic values corresponding to different substances, and can effectively identify counterfeit and shoddy liquid foods in food safety. The beneficial effects of the present invention have:

1. A single integrated chip is used to integrate more high-precision signal processing circuits, and the configurable design makes the obtained signal have high precision, wide application range, and can effectively distinguish different substances;

2. The use of integrated circuit manufacturing technology makes the chip area smaller, so the identifier is small in size and portable, suitable for individuals and families;

3. Non-chemical method, using weak ultrasonic signal as a physical detection method, has no loss to the measured object and the instrument itself;

4. Non-qualitative and quantitative detection, focusing on differences, in line with people's understanding and needs.

【Description of drawings】

Fig. 1 is a system block diagram of an ultrasonic liquid difference recognition instrument applied to food safety;

Fig. 2 is a system diagram of a signal processing chip;

Fig. 3 is the structural diagram of ultrasonic transmitting circuit;

Fig. 4 is a structural diagram of an ultrasonic receiving circuit;

Fig. 5 is the workflow of the recognition instrument;

【Detailed ways】

The features and advantages of the present application will be described with reference to the accompanying drawings.

In the field of food safety testing, there are few applications based on ultrasonic technology, but some institutions are conducting related research on the content analysis of food components based on ultrasonic technology and the ultrasonic characteristics of foods with different concentrations and densities. For example, the Institute of Food Quality and Safety of University of Shanghai for Science and Technology published papers on ultrasonic characteristics of milk fat content and ultrasonic detection of pork quality in 2011; Tianjin University conducted research on ultrasonic characteristics of main components of milk and the influence of temperature in 2007. And published papers and patents; Zhejiang University conducted research on ultrasonic propagation characteristics and quality ultrasonic testing technology of liquid food in 2005-2006; Shaanxi Normal University, South China University of Technology, Tongji University, etc. also have related research on ultrasonic characteristics of liquids Research. After analysis, it is found that the papers and patents published by these research institutions focus on the establishment of a model of liquid composition, concentration or density and its ultrasonic characteristics. Most of their patents are also for the detection system of this model, which has certain limitations and cannot be generalized. Used in food testing and analysis.

The invention proposes an ultrasonic liquid difference recognition instrument applied to food safety, which is used for personal or family food safety detection. This patent does not depend on the ultrasonic characteristic model of a certain measured object, and is not limited by the type of the measured object. It focuses on the difference analysis of different measured objects. Its key technical points focus on how to identify the difference, that is, how to realize High-precision signal extraction.

After the ultrasonic signal is received by the ultrasonic sensor and converted into an electrical signal, its amplitude is on the order of microvolts, which belongs to the category of small signals. How to extract such a small signal and make the resolution at least in the order of microvolts is a difficult research point. Analyze the existing high-precision signal extraction methods at present. The technologies used mainly include amplifier circuits, filters, high-precision high-speed ADCs, etc. Most of these signal acquisition systems are board-level integration of discrete components, and there is loss in board-level data transmission, which has a certain distortion effect on the signal. In this patent, the existing technology is still adopted, integrating signal amplification processing, filtering, high-precision high-speed ADC, and related power supply, clock, control, storage and other modules. Integrated circuit design technology is used to integrate high-precision signal extraction and analysis and processing circuits on a single chip, which reduces the distortion caused by signal transmission between circuits. At the same time, parametric design is used in circuit design to make the system flexible. and configurability, it can be applied to a wide range of detection.

As shown in FIG. 1 , 100 is a system block diagram of an ultrasonic liquid difference identifier applied to food safety. 101 is an ultrasonic sensor, 102 is a liquid to be measured, 103 is a fixed shaft for fixing two ultrasonic sensors, 104 is a signal processing chip, 105 is a button, 106 is a display screen, and 107 is other terminals, such as PC, mobile phone, cloud, etc.

Described signal processing chip 104 is shown in Figure 2, by ultrasonic transmitting circuit 201, ultrasonic receiving circuit 202, sigma-delta AD modulator 203, digital filter 204, high-speed memory 205, storage access interface 206, wireless transmission module 207 , microprocessor 208 and crystal oscillator 209. Under the control of 208, 201 generates a pulse signal of a specific frequency and power, which excites the ultrasonic sensor to emit ultrasonic waves. Under the control of 208, 202 starts receiving the signal at the same time as 201. In 203, the analog-to-digital conversion is performed to obtain a 1-bit oversampling signal. After 204 is configured in 201, the signal of a specific frequency is filtered and restored, and then sent to the high-speed memory for storage under the control of 201. At the same time, 201 continuously reads data from the high-speed memory, detects the time of arrival of the received ultrasonic signal and the amplitude of the signal, and corrects the distance between these two values, and compares them with the characteristic value of the ultrasonic signal of the real or good quality material. By comparison, the gap between the tested substance and the real or good quality substance can be obtained, so as to evaluate the quality of the tested substance and effectively identify counterfeit and shoddy substances.

The signal processing chip 104 integrates more signal processing circuits, and the circuits are configurable, so that the detection accuracy of the recognition instrument can be adjusted and the application range is wider. For different substances to be tested, the ultrasonic signal characteristic value of the high-quality product of the substance is obtained through the storage access interface 206 or the wireless transmission module 207, and the user selects the type of the substance to be tested, and the module 201 performs a test for each system according to the type of the substance to be tested. The circuit configures the corresponding parameters, then starts the detection, and compares the obtained detection result with the characteristic value of the ultrasonic signal of the high-quality product to identify whether the substance under test is good or bad.

As shown in FIG. 3 , the ultrasonic transmitting circuit 201 is composed of a frequency division circuit 301 , a power adjustment circuit 302 and a switch circuit 303 . 301 receives the local oscillator clock from the crystal oscillator 209, generates a corresponding frequency-divided clock according to the configuration of 201, performs power amplification through 302, and the amplification factor is configured by 201, and finally 303 outputs the signal when 201 turns on the detection. This patent supports the detachment of the ultrasonic sensor 101, that is, ultrasonic sensors of different natural frequencies can be replaced. By configuring the 301 to generate excitation pulses of corresponding frequencies, a suitable sensor can be selected for a specific substance, thereby improving detection accuracy. For the measured substance that absorbs a lot of ultrasonic waves, in order to increase the strength of the signal at the receiving end, the power can be enhanced through the power adjustment module.

The ultrasonic receiving circuit 202 is shown in FIG. 4 , and is composed of a band-pass filter 401 , an amplification circuit 402 , an over-sampling circuit 403 and a low-pass filter 404 . The frequency of the received ultrasonic signal does not change during propagation, that is, the frequency of the received ultrasonic signal is equal to the natural frequency of the ultrasonic sensor. But this is an ideal situation. During the propagation process, noise from other frequency bands will be introduced. Ultrasonic signals belong to the category of small signals. If the received signal is directly amplified, the noise will also be amplified, affecting subsequent detection. Accuracy, so the noise needs to be effectively removed before amplification. This patent adopts a band-pass filter with the natural frequency of the ultrasonic sensor as the center frequency to retain the signal of the natural frequency and filter out the signals of other frequencies, so as to achieve the purpose of noise reduction. Then the small signal is amplified by the amplification circuit 402, and then processed by the oversampling 403 and the low-pass filter 404 to obtain a highly oversampled signal, which retains the original information of the analog signal to the greatest extent.

Send the oversampled signal to the sigma-delta AD modulator 203 to obtain a 1-bit digital signal, and then recover the signal through 204 to obtain a digital signal represented by multiple bits. Under the control of 208, the multi-bit digital signal is sent to the high-speed memory, and the data is read out in real time for analysis.

The microprocessor 208 mainly completes system control and signal analysis. System control includes setting each module according to user input, such as the pulse frequency and power of the ultrasonic transmitting circuit, digital filter parameters, and ambient temperature. At the same time, control the data to interact with other terminals through the access interface or wireless transmission module, start measurement and signal analysis, control display output, etc.; signal analysis mainly calculates the propagation speed, attenuation and impedance of the ultrasonic signal in the measured object based on the detection signal , and perform distance correction, and then compare these values with the corresponding standard values to obtain the authenticity, quality, and display of the measured object. Its workflow is shown in Figure 5, which is divided into 7 steps:

S1: power on, turn on the recognition device by pressing button 105;

S2: Update data, that is, the microprocessor 208 controls the memory access interface 206 or the wireless transmission module 207 to communicate with the outside world, and downloads the signal characteristic value of the new high-quality material after ultrasonic propagation to the local for comparison during detection;

S3: After confirming that there is a comparison value of the tested substance in the storage, the user selects the type of the tested substance and sets the current ambient temperature;

S4: The system configures the parameters of each internal module according to the type of substance to be tested selected by the user;

S5: Start detection, that is, turn on the pulse output switch of the ultrasonic transmitting circuit 201, start the ultrasonic receiving circuit 202 to start receiving data, and control the memory 205 to store the received data;

S6: At the same time, the microprocessor accesses the memory, detects the time when the ultrasonic signal is received, and evaluates its amplitude when the ultrasonic signal is detected, and obtains the propagation time and amplitude value and the high-quality material after ultrasonic transmission Signal characteristic value is compared;

S7: Display the comparison result.

The crystal oscillator 209 provides a working clock for each module in the system.

The invention combines ultrasonic sensing technology, integrated circuit design technology and signal high-precision acquisition technology, and proposes an ultrasonic liquid difference recognition instrument applied to food safety. The recognition instrument has the characteristics of high precision, configurability, small size, no loss to the measured object and the instrument, and the like. At the same time, the recognition instrument is not limited by the measurement object, has a wide application range, is simple and direct in physical detection, is easy to popularize, non-qualitative and quantitative detection, focuses on differences, and meets people's understanding and needs.

The above content is a further detailed description of the present invention in conjunction with the embodiments, and it cannot be assumed that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deduction or replacement can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (6)

1. An ultrasonic liquid difference identification instrument applied to food safety, the identification instrument is composed of two pairs of discrete detachable ultrasonic transceiver sensors, signal processing chips, display screens and buttons. It is characterized by: The distance between the ultrasonic transmitting and receiving sensors is adjustable, a pair of ultrasonic transmitting and receiving sensors are used for distance calibration, and a pair of ultrasonic transmitting and receiving sensors are used to detect the measured object; the sensors on the same side of the ultrasonic sensors are connected by a fixed shaft so that in the same position; The signal processing chip consists of an ultrasonic transmitting circuit with adjustable frequency power, a receiving circuit capable of noise reduction, amplification, oversampling and filtering, a high-precision sigma-delta AD modulator, a high-precision adjustable digital filter circuit, a high-speed memory and its Memory access interface, wireless transmission module, microprocessor and crystal oscillator. 2. The identifying instrument as claimed in claim 1, wherein: said ultrasonic emission circuit is made up of frequency division circuit, power adjustment circuit and switch circuit, and its emission pulse frequency and power can be set by microprocessor; Ultrasonic energy is Weak ultrasonic range, no damage to the measured object. 3. The identification device according to claim 1, characterized in that: the ultrasonic receiving circuit includes a bandpass filter for noise reduction processing, a signal amplification module, an oversampling and filtering processing module. 4. The identifying instrument as claimed in claim 1, characterized in that: said high-accuracy adjustable digital filter circuit receives the signal from the sigma-delta AD modulator for filtering and signal restoration processing, the filter of the filter Parameters can be set by the microprocessor. 5. The identification device according to claim 1, characterized in that: the memory access interface and the wireless transmission module can send local data to other terminals or update data locally. 6. The identification device as claimed in claim 1, characterized in that: said microprocessor is mainly used for system control and signal analysis, and system control includes setting each module according to user input, such as the pulse frequency and power, digital filter parameters, ambient temperature, etc. At the same time, control the data to interact with other terminals through the access interface or wireless transmission module, start measurement and signal analysis, control display output, etc.; signal analysis mainly calculates the propagation speed, attenuation and impedance of the ultrasonic signal in the measured object based on the detection signal , and perform distance correction, and then compare these values with the corresponding standard values to obtain the authenticity, quality, and display of the measured object.

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