LCD Digital Thermometer for Freezer Temperature Sensor Test

Measuring instruments are the third party standards required for measuring in order to obtain some attribute values of the target. Measuring instruments generally have scales, volumes and other units.
Scholars and navigators know very well that if the position of celestial bodies can be accurately measured on the sea, then sailors can know their latitude with certainty. To do this, we need precise measuring instruments.
Ptolemy once described the astrolabe (also called the astrometer). The larger ones are used in observatories and the smaller ones are used on ships. The use of the astrolabe requires the cooperation of three people - one holds the thumb ring on the astrolabe, one aims, and the other reads the results on the dial. When the ship shakes violently, the results are naturally not very accurate. Whenever possible, sailors will go ashore to survey.
Ancient astronomers used a cross ruler to measure the latitude of stars. Later sailors also used it in navigation. The instrument consists of a ruler and a cross ruler, with the lower end of the cross ruler placed in a horizontal position. While observing the celestial body along the ruler, slide the cross ruler until it touches the object (sun or star) in your view, and then read the degree on the ruler. This instrument can be operated by only one person.
Both the astrolabe and the cross ruler require the observer to observe the sun directly. In sunny days, too strong light will make observation impossible. In order to solve this problem, England captain and navigator John Davis invented the back ruler. It is made of a ruler and a sliding crossbar. When observing, the observer first turns his back to the sun, and then slides the crossbar until it casts a shadow in the small disk in front of him. In this way, the observer can observe the horizon.
John Davis also invented the quadrant with the help of Edward Wright, a mathematician from Cambridge. There is an eyepiece on the crossbar of this instrument, through which the observer can observe the horizon and the reflected sun.
Pierre Burger, a hydrogeographer in Kloicik, made further improvements to the object limiter. The improved quadrant enables the observer to see the sun setting on the horizon through the eyepiece.
John Hadley in England invented the octave, which was first tried in 1732. It consists of a reflecting and an alcohol level. This instrument is more accurate than any other instrument used at sea before.
Instrument index
The basic contents of the concept of measuring instrument include: precision, error, measuring standard equipment, length measurement, angle measurement, shape measurement, and traditional optical instruments. Application in precision measurement, etc.
There are two types of measuring instruments: contact test and optical test (most used) contact test: general measuring tools and 3D measuring tools (CMM is also called 3D) CMM is also called 3D, which can measure many complex spatial dimensions, such as molds and automobile products.
Common types
Electronic measuring instrument
Electronic measuring instruments have a unique strategic industry. Its own development has a very obvious impact on the development of the entire national economy, especially the electronic information industry. The market of electronic measuring instruments in China is huge and the demand is large. Electronic measuring instruments play a vital role in the development of electronic information industry.
The development of domestic electronic measurement technology and electronic measurement instruments is rapid, covering all walks of life. First, the basic theoretical research of electronic measurement technology: new testing theory and method research, artificial intelligence theory research, frequency based traceability and standard acquisition method research, new measurement and control bus and system structure research, measurement and instrument standard research and formulation are the key points in the future theoretical research. Second, the development of electronic measurement and measurement technology: the fast developing technologies include advanced measurement and control bus technology, new digital signal processing technology, new comprehensive testing and fault diagnosis technology, optical frequency standard and new precision time-frequency testing technology. The third and second types of important electronic measuring instruments: an important development direction of vector network analyzer is to build automatic measurement technology and automatic testing system with vector network analyzer as the core; In addition, vector network analyzer has stepped out of the application field of traditional linear network and played an important role in the test and analysis of nonlinear and high-power networks. Modulation domain analyzer is the only technology that can directly measure the jitter that changes with time in communication transmission, especially in the field of electronic testing. Fourth, the development of modern production technology of electronic measuring instruments: the design and production level of instrument products is an important symbol to measure a country's scientific and technological industrial foundation and industrial capacity, which runs through the entire production process and life cycle of products. In the future, in the research of instrument production technology, we should pay attention to solving the problems of product design and process supervision mode, researching new instrument devices, developing high-precision and high-quality quality inspection equipment for special instrument components, parts and complete machines, studying virtual test verification and engineering verification technology, studying advanced production processes and processes, and studying new evaluation methods for stability, reliability, maintainability and measurability, And the standardized certification system of products. Fifth, the integrated test system of electronic measuring instruments: the integrated test should focus on the system optimization of the integrated test system, the research on the unity and integrity technology of the measurement and control system, the research on sensor information processing and multi-sensor data fusion technology, and the research on the distributed network interconnection, triggering, synchronization and other technologies of field test in large areas, And the research of reconfigurable measurement and control system technology based on synthetic instruments and systems.
China's electronic measuring instruments are in the second development opportunity since the founding of New China. It is mainly due to the development of China's economy. There have been two changes in China's economy: first, the industry needs to be upgraded, and second, the industry needs to innovate independently. The selection of raw materials, the monitoring of production process, the testing of products, and the operation of an industry all require electronic measuring instruments. Therefore, electronic measuring instruments shoulder the historical mission of upgrading and independent innovation of other industries.
pixiv
Anime is also called imager, imager, two-dimensional imager, automatic imager, etc.
Manual Video
The manual image measuring instrument relies on manual operation to control the movement of X and Y axes of the measuring platform to obtain the optical image of the object to be measured. It is magnified by the optical microscope. After the magnified object image is sent to the computer by the CCD camera system, it can efficiently detect the contour and surface shape, size, angle and position of various complex workpieces, and then read out the required geometric dimensions.
Automatic imaging
Based on the manual image measuring instrument, the automatic image measuring instrument is changed from manual control to computer system to control the movement of X, Y, Z axes. It is more accurate, convenient and fast when selecting geometric quantities such as the contour and angle of the measured object. It has become the most widely used type of image measuring instrument in China, and has the tendency to replace manual image measuring instrument.
For the learning requirements of measuring instruments, it is not only necessary to understand the whole process of basic surveying and mapping work, but also to systematically master the basic skills of measuring instrument operation, data processing, construction lofting, etc. The measurement requires seriousness, carefulness, accuracy and preciseness, and very small mistakes will also cause serious consequences in the project, so we must have a serious attitude and the spirit of hard work in the measurement work.
CMM
The CMM can be classified into three types according to the operation mode: manual, motor driven and CNC.
Manual
The operator holds the spindle by hand to move it along the axis. During measurement, pay attention to the measurement error caused by the measured pressure between the probe and the workpiece, and the bending of the shaft caused by the acceleration of the probe movement.
Motor driven
The motor driven CMM can generally be controlled by a joystick. It has the advantages of high measurement accuracy, easy operation, and teaching measurement.
CNC type
In addition to the motor driven function, the CNC CMM can also automatically perform measurement according to the program preset by the computer. Even some CMMs produced by some manufacturers also provide automatic workpiece assembly and disassembly. In addition to providing dimension measurement (point-to-point measurement), CNC CMM can also be used for surface profile measurement (point-to-point measurement and scanning measurement).
Optical test measurement: it can avoid the deformation of the product in the contact test measurement and some work that cannot be completed in the contact test measurement. The products include: anime, three-dimensional laser reading machine, etc.