The working principle and design of ultrasonic level transmitter

Today, I will introduce a national invention authorized patent-an ultrasonic level transmitter. The patent was applied for by Dalian Yiyuan Technology Co., Ltd., and the authorization was announced on March 8, 2017.

Content description

The utility model relates to an ultrasonic level transmitter, which belongs to the technical field of level measurement.

Background of the invention

The ultrasonic level meter is an instrument that uses the principle of sound wave reflection to measure the height of the material in the container. It can measure and display the level value (liquid level or material level), and the output signal is transmitted to the host computer in the main control room. The ultrasonic level meter is composed of an electronic unit, a piezoelectric transducer and an outer shell. It is divided into two types: one-piece and split-type. The piezoelectric transducer with a shell is also called an ultrasonic sensor. When the electronic unit and the piezoelectric transducer form an integrated structure, it is called an integrated ultrasonic level gauge. The electronic unit is inside the shell, and the lower part of the shell is combined with the piezoelectric transducer; when the electronic unit and the piezoelectric transducer When each form an independent structure, it is called a split ultrasonic level gauge, and the two are connected by an external cable.

Existing ultrasonic level gauges, whether integrated or split structure, need to be installed and used to set some installation parameters through the keys and displays provided by the ultrasonic level gauges, so that the level gauges can work normally. The ultrasonic level meter first measures the distance to the surface of the object, and the level value (liquid level or material level) is obtained by subtracting the distance measurement value from the installation height (the distance from the surface of the piezoelectric transducer to the bottom of the container) Therefore, the installation height must be set in the level gauge, and other parameters such as the full scale and zero point of the remote current signal must also be set. Ultrasonic level meters must provide buttons and display parts for users to set the necessary parameters. As a result, the ultrasonic level gauge with the above device has a complicated structure, a large volume, and a relatively large manufacturing cost.

Summary of the invention

The utility model proposes a solution to the shortage of the above-mentioned ultrasonic level meter, which is to design an ultrasonic level transmitter to remove the keys and the display part in the electronic unit, thereby compressing the volume of the entire electronic unit and integrating the electronic unit It is integrated with the piezoelectric transducer into a smaller shell to form a two-wire integrated level transmitter, which transmits a DC4-20mA current signal remotely through a 2-core cable, and is on the same loop Power is supplied externally, the part below 4mA in the loop is used for the internal circuit of the transmitter, and the part above 4mA is output as a remote signal.

The working principle and design of ultrasonic level transmitter

A small Bluetooth module is designed in the electronic unit to send and receive Bluetooth electromagnetic signals. The user can set the installation parameters required by the level transmitter through a handheld device with Bluetooth communication, such as a mobile phone. The measurement data and internal parameters of the transmitter can be read within the range, without directly approaching the transmitter, which is convenient for debugging the equipment. The Bluetooth module adopts an active sleep mode and wakes up every certain period, which can effectively reduce the power consumption of the transmitter. The voltage conversion circuit converts the external power supply into the working voltage required by each circuit in the electronic unit. The single-chip microcomputer system controls the piezoelectric transducer driving circuit to work periodically. The echo signal receiving circuit receives the echo signal of the piezoelectric transducer and triggers the single-chip microcomputer. The system performs data processing. The single-chip microcomputer system collects the temperature sensor signal and controls the signal output of the DC4-20mA current output circuit. The single-chip microcomputer controls the Bluetooth communication module to communicate with the outside world.

Therefore, the transmitter is an integrated structure, the power supply and current signal output are in the same loop two-wire form, composed of an electronic unit and a piezoelectric transducer sealed in a single shell. The electronic unit includes voltage conversion and a single-chip microcomputer system. , Piezoelectric transducer drive, echo signal receiving, Bluetooth communication and DC4-20mA current output circuit. The piezoelectric transducer is a single transducer combining transceiver.

Since the speed of sound is affected by temperature, in order to improve the measurement accuracy, a temperature sensor should be encapsulated in the housing. A 2-core cable is led out from the inside of the shell for signal transmission with the outside world and power supply to the transmitter. Because the electronic unit removes the keys and the display, and then removes the original shell used to house the electronic unit, this further reduces the cost, reduces the product price, and saves the user cost. As Bluetooth communication is provided, the parameter setting is more convenient and flexible.

TFT LCD Module

How does TFT work?
TFT is the abbreviation of "Thin Film Transistor", generally refers to thin film liquid crystal displays, but actually refers to thin film transistors (matrix)-can "actively" control each independent pixel on the screen, which is The origin of the so-called active matrix TFT (active matrix TFT). So how exactly is the image produced? The basic principle is very simple: the Display Screen is composed of many pixels that can emit light of any color, and the purpose can be achieved by controlling each pixel to display the corresponding color. In TFT LCD, backlight technology is generally used. In order to accurately control the color and brightness of each pixel, it is necessary to install a shutter-like switch after each pixel. When the "blinds" are opened, light can pass through, and " When the shutters are closed, light cannot pass through. Of course, technically, it is not as simple as the one just mentioned. LCD (Liquid Crystal Display) utilizes the characteristics of liquid crystals (liquid when heated, and crystallized into solid when cooled). Generally, liquid crystals have three forms:
Smectic liquid crystal similar to clay
Nematic liquid crystal resembling a fine matchstick
Cholestic liquid crystal
The liquid crystal display uses filaments, and when the external environment changes, its molecular structure will also change, and thus have different physical properties-it can achieve the purpose of letting light through or blocking light-which is just like the blinds just now.
Everyone knows the three primary colors, so each pixel on the display screen needs three similar basic components described above to control the three colors of red, green, and blue respectively.
The most commonly used one is twisted nematic TFT LCD (Twisted Nematic TFT LCD). Existing technologies vary greatly, and we will cover them in detail in the second part of this article.
There are grooves on the upper and lower layers. The grooves on the upper layer are arranged longitudinally and the grooves on the lower layer are arranged horizontally. When no voltage is applied to the liquid crystal in its natural state, the light emitted from the light emitting layer of the twisted nematic TFT Display working principle diagram of Figure 2a will be twisted by 90 degrees after passing through the interlayer, so that it can pass through the lower layer smoothly.
When a voltage is applied between the two layers, an electric field is generated. At this time, the liquid crystals are aligned vertically, so the light will not be twisted-the result is that the light cannot pass through the lower layer.

(2) TFT pixel structure: The color filter is divided into red, green, and blue according to the color, which are arranged on the glass substrate to form a group (dot pitch) corresponding to a pixel. Each monochromatic filter is called It is a sub-pixel. In other words, if a TFT display supports a maximum resolution of 1280×1024, then at least 1280×3×1024 sub-pixels and transistors are required. For a 15-inch TFT display (1024×768), then a pixel is about 0.0188 inches (equivalent to 0.30mm), for an 18.1-inch TFT display (1280×1024), it is 0.011 inches (equivalent to 0.28mm) .
As we all know, pixels are decisive for the display. The smaller each pixel is, the larger the maximum resolution that the display can achieve. However, due to the limitation of the physical characteristics of the transistor, the size of each pixel of the TFT at this stage is basically 0.0117 inches (0.297mm), so for a 15-inch display, the maximum resolution is only 1280×1024.

Tft Lcd Module,Lcd Liquid Crystal Display Module,Lcd Module,Lcd Screen Module

ESEN Optoelectronics Technology Co., Ltd, , https://www.esenoptoelectronics.com

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