位移传感器(中英对照)

位移传感器又称为线性传感器，它分为电感式位移传感器，电容式位移传感器，光电式位移传感器，位移传感器超声波式位移传感器，霍尔式位移传感器。电感式位移传感器是一种属于金属感应的线性器件，接通电源后，在开关的感应面将产生一个交变磁场，当金属物体接近此感应面时，金属中则产生涡流而吸取了振荡器的能量，使振荡器输出幅度线性衰减，然后根据衰减量的变化来完成无接触检测物体的目的。

简介

电感式位移传感器具有无滑动触点，工作时不受灰尘等非金属因素的影响，并且低功耗，长寿命，可使用在各种恶劣条件下。位移传感器主要应用在自动化装备生产线对模拟量的智能控制。

位移是和物体的位置在运动过程中的移动有关的量，位移的测量方式所涉及的范围是相当广泛的。小位移通常用应变式、电感式、差动变压器式、涡流式、霍尔传感器来检测，大的位移常用感应同步器、光栅、容栅、磁栅等传感技术来测量。其中光栅传感器因具有易实现数字化、精度高（目前分辨率最高的可达到纳米级）、抗干扰能力强、没有人为读数误差、安装方便、使用可靠等优点，在机床加工、检测仪表等行业中得到日益广泛的应用。

原理

计量光栅是利用光栅的莫尔条纹现象来测量位移的。“莫尔”原出于法文Moire，意思是水波纹。几百年前法国丝绸工人发现，当两层薄丝绸叠在一起时，将产生水波纹状花样；如果薄绸子相对运动，则花样也跟着移动，这种奇怪的花纹就是莫尔条纹。一般来说，只要是有一定周期的曲线簇重叠起来，便会产生莫尔条纹。计量光栅在实际应用上有透射光栅和反射光栅两种；按其作用原理又可分为辐射光栅和相位光栅；按其用途可分为直线光栅和圆光栅。下面以透射光栅为例加以讨论。透射光栅尺上均匀地刻有平行的刻线即栅线，a为刻线宽，b为两刻线之间缝宽，W=a+b称为光栅栅距。目前国内常用的光栅每毫米刻成10、25、50、100、250条等线条。光栅的横向莫尔条纹测位移，需要两块光栅。一块光栅称为主光栅，它的大小与测量范围相一致；另一块是很小的一块，称为指示光栅。为了测量位移，必须在主光栅侧加光源，在指示光栅侧加光电接收元件。当主光栅和指示光栅相对移动时，由于光栅的遮光作用而使莫尔条纹移动，固定在指示光栅侧的光电元件，将光强变化转换成电信号。由于光源的大小有限及光栅的衍射作用，使得信号为脉动信号。

信号处理

辨向原理

在实际应用中，位移具有两个方向，即选定一个方向后，位移有正负之

分，因此用一个光电元件测定莫尔条纹信号确定不了位移方向。为了辨向，需要有π/2相位差的两个莫尔条纹信号。

细分技术

随着对测量精度要求的提高，以栅距为单位已不能满足要求，需要采取适当的措施对莫尔条纹进行细分。所谓细分就是在莫尔条纹信号变化一个周期内，发出若干个脉冲，以减少脉冲当量。如一个周期内发出n个脉冲，则可使测量精度提高n备，而每个脉冲相当于原来栅距的1/n。由于细分后计数脉冲频率提高了n倍，因此也称n倍频。通常用的有两种细分方法：其一、直接细分。在相差1/4莫尔条纹间距的位置上安放两个光电元件，可得到两个相位差90°的电信号，用反相器反相后就得到四个依次相差90°的交流信号。同样，在两莫尔条纹间放置四个依次相距1/4条纹间距的光电元件，也可获得四个相位差90°的交流信号，实现四倍频细分。其二、电路细分。

专用集成电路

四倍频专用集成电路QA740210同时具有辨相和四倍频细分的功能，可将两路正交的方波进行四倍频后产生两路加、减计数信号，可送双时钟可逆计数器进行加、减计数，也可直接送微型计算机（包括单片机）进行数据处理。

1、特点：

⑴、数字化微分电路：4路微分信号脉宽由主频周期决定，因此，是一致的，而且可在很大范围里方便地选择。

⑵、临界报警与过速报警两档速度提示：可在光栅运动速度接近极限值时给出临界报警信息，以便操作者及时控制光栅运动快慢。在速度超过极限值时本电路将给出出错信息。

⑶、绝对零位控制：绝对零位的设置将给操作者带来许多方便，如故障断电后的重新定位等。本电路有“到绝对零位开始计数”和“到绝对零位停止计数”，以及“与绝对零位无关”三种工作模式。

⑷、片选：本电路设有片选端，可以构成多标数显系统。

⑸、COMS工艺：输入输出的电压电流与4000系列CMOS及LSTTL电路兼容。

分类

根据运动方式分类

直线位移传感器

原理：

直线位移传感器的功能在于把直线机械位移量转换成电信号。为了达到这一效果，通常将可变电阻滑轨定置在传感器的固定部位，通过滑片在滑轨上的位移来测量不同的阻值。传感器滑轨连接稳态直流电压，允许流过微安培的小电流，滑片和始端之间的电压，与滑片移动的长度成正比。

将传感器用作分压器可最大限度降低对滑轨总阻值精确性的要求，因为由温度变化引起的阻值变化不会影响到测量结果。

LT直线位移传感器：

⊙ 广泛应用于注塑、机床及机械加工等行业

⊙ 无限分辨率

⊙ 行程：50至900mm

⊙ 独立线性度：±0.05%

⊙ 位移速度达到：5m/s、10 m/s可选

⊙ 工作温度：-30至+100℃

⊙ 多种电气连接方式

⊙ 保护等级：IP60（IP65可选）

角度位移传感器

根据材质分类

金属膜传感器、导电塑料传感器、光电式传感器、磁敏式传感器、金属玻璃铀传感器、绕线传感器。

电位器式位移传感器它通过电位器元件将机械位移转换成与之成线

性或任意函数关系的电阻或电压输出。普通直线电位器和圆形电位器都可分别用作直线位移和角位移传感器。但是，为实现测量位移目的而设计的电位器，要求在位移变化和电阻变化之间有一个确定关系。电位器式位移传感器的可动电刷与被测物体相连。物体的位移引起电位器移动端的电阻变化。阻值的变化量反映了位移的量值，阻值的增加还是减小则表明了位移的方向。通常在电位器上通以电源电压，以把电阻变化转换为电压输出。线绕式电位器由于其电刷移动时电阻以匝电阻为阶梯而变化，其输出特性亦呈阶梯形。如果这种位移传感器在伺服系统中用作位移反馈元件，则过大的阶跃电压会引起系统振荡。因此在电位器的制作中应尽量减小每匝的电阻值。电位器式传感器的另一个主要缺点是易磨损。它的优点是：结构简单，输出信号大，使用方便，价格低廉。

霍耳式位移传感器它的测量原理是保持霍耳元件（见半导体磁敏元件）的激励电流不变，并使其在一个梯度均匀的磁场中移动，则所移动的位移正比于输出的霍耳电势。磁场梯度越大，灵敏度越高；梯度变化越均匀,霍耳电势与位移的关系越接近于线性。霍耳式位移传感器的惯性小、频响高、工作可靠、寿命长，因此常用于将各种非电量转换成位移后再进行测量的场合。

光电式位移传感器它根据被测对象阻挡光通量的多少来测量对象的位移或几何尺寸。特点是属于非接触式测量，并可进行连续测量。光电式位移传感器常用于连续测量线材直径或在带材边缘位置控制系统中用作边缘位置传感器。

传感器市场发展前景

咨询公司INTECHNOCONSULTING的传感器市场报告显示，2008年全球传感器市场容量为506亿美元，预计2010年全球传感器市场可达600亿美元以上。调查显示，东欧、亚太区和加拿大成为传感器市场增长最快的地区，而美国、德国、日本依旧是传感器市场分布最大的地区。就世界范围而言，传感器市场上增长最快的依旧是汽车市场，占第二位的是过程控制市场，看好通讯市场前景。

目前，全球的传感器市场在不断变化的创新之中呈现出快速增长的趋势。有关专家指出，传感器领域的主要技术将在现有基础上予以延伸和提高，各国将竞相加速新一代传感器的开发和产业化，竞争也将日益激烈。新技术的发展将重新定义未来的传感器市场，比如无线传感器、光纤传感器、智能传感器和金属氧化传感器等新型传感器的出现与市场份额的扩大。

Linear displacement transducer, also known as the sensor, which is divided into inductive displacement sensor, capacitive displacement sensors, optical displacement sensor, displacement sensor ultrasonic displacement sensors, Hall-type displacement sensor. Inductive displacement sensor is a metal sensor is a linear device, powered on, the switch sensor surface will result in an alternating magnetic field, when the metal object close to the sensor surface, the metal in the vortex and absorb the energy of the oscillator, the oscillator output amplitude of linear attenuation, attenuation changes and then to complete the purpose of non-contact detection of objects.

Introduction

Inductive displacement sensor with no moving contacts from dust and other non-metallic work factors, and low power consumption, long life, can be used in a variety of harsh conditions. Displacement sensors are used in automated production line equipment, analog intelligent control.

Displacement and position of objects in motion on the amount of movement and displacement of the scope of measurement is quite extensive. Usually small displacement strain, inductive, differential transformer, eddy current, Hall sensors to detect the displacement of a large common inductosyn, grating, capacitive, magnetic and other sensor technology to measure the gate. Grating sensors which are easy to achieve because of digital, high accuracy (currently the highest resolution up to nano-scale), anti-interference ability, no one reading error, easy to install, use and reliable, in machining, instrumentation and other industries Been increasingly widely used. Principle

Metrological grating is the use of grating moire fringe phenomenon to measure the displacement. "Moore" For the original French Moire, which

means the water ripple. French silk workers found when the two layers of thin silk, stacked together, will have a ripple-like pattern hundreds of years ago; if the relative motion of thin silk, the pattern will move with it, this strange is the moire fringe pattern. Generally, as long as there is a certain cycle curve clusters overlap, they will produce Moire fringe. Grating in the practical application of measurement has two transmission gratings and reflection gratings; action principle can be classified according to their radiation grating and phase grating; according to their use can be divided into linear and circular gratings. The following example to be discussed transmission grating. Transmission grating engraved on a uniform that is parallel to the gate line engraved line, a line width for the moment, b is fracture width between the two groove, W = a + b as grating pitch. Currently used carved 10,25,50,100,250 per mm grating strips lines. Moire fringe grating measured horizontal displacement, need two gratings. A grating as the main grating, its size is consistent with the measurement range; the other one is a very small, as instructed grating. To measure the displacement must be added in the main grating side of the light source, grating side of the instruction plus photoelectric receiving elements. When the primary grating and grating relative movement direction, the shading effect of leaving the grating Moiréfringe mobile, fixed grating in the direction side of the optical components, the light intensity changes into electrical signals. Since the limited size of the light source and diffraction grating effect, making the signal for the pulse signal.

Signal Processing

To the principles identified

In practice, the displacement has two directions, that is, choose a direction, the displacement of the positive and negative points, so with a determination of Moire fringe optoelectronic devices can not determine the direction of displacement. In order to distinguish the need to have π / 2 phase difference of the two moiré fringe signals.

Subdivision

With the improvement of measurement accuracy, to pitch as a unit can not meet the requirements, the need to take appropriate measures to be broken down on the Moire fringe. Subdivision is the so-called changes in the moiréfringe of a cycle, issued a number of pulses to reduce the pulse equivalent. If given within a period of n pulses, the accuracy can improve n equipment, and each pulse is equivalent to the original pitch of 1 / n. After the count of the sub-pulse frequency increased n times, so also called n multiplier. There are two commonly used subdivision method: First, the direct segment. The difference between the 1 / 4 position on the Moire fringe spacing placed the two optical components, get the two 90 ° phase difference signal, the use of four inverter followed by a difference of RP after 90 ° of the AC signal. Similarly, in the two moire fringe order of distance between the place four 1 / 4 fringe spacing of the optoelectronic components, are available to the exchange of the

four 90 °phase difference signal, to achieve four interpolated. Second, the circuit is broken down.

ASIC

ASIC QA740210 quadrature phase and also has identified four segments of the function of frequency can be two orthogonal frequency square wave generated after four two-Luke, by counting the signal, can send even the clock reversible counter Add, subtract, count, can also be sent directly to micro-computer (including MCU) for data processing.

1, features:

⑴, digital differential circuit: 4 Differential pulse width determined by the frequency of cycles, therefore, is consistent, and can be easily in a wide range of choices.

⑵, criticality alarm and over-speed warning two speed Tip: You can limit the grating velocity when approaching the critical alarm information is given to the operator speed control in a timely grating movement. Faster than the time limit in the circuit will give an error message.

⑶, absolutely zero control: absolute zero setting will bring much convenience operators, such as power failure after the re-positioning. This circuit has "absolutely zero to start counting"and"stop the count to the absolute zero"and"has nothing to do with the absolute zero" three modes.

⑷, Chip Select: This circuit has a chip select terminal, it can be multi-standard digital display system.

⑸, COMS process: input and output voltage and current with the 4000 series CMOS and LSTTL circuits compatible.

Categories

Classified according to the motion method

Linear displacement sensor

Principle:

Function of linear displacement sensor is the linear mechanical displacement into electrical signals. To this effect, usually slide-set variable resistor the fixed part of the sensor, through the slider on the rail to measure the displacement of different resistance. Steady-state DC voltage rails connecting the sensor to allow a small flow through the micro-ampere current, slip between the film and the beginning of the voltage terminal, and the length of vane movement. The sensor can be used as a divider rails to minimize the total resistance of the requirements of accuracy, because the resistance caused by the change of temperature change will not affect the measurement results.

LT linear displacement sensor:

⊙widely used in injection molding, machine tool and machining industry

⊙infinite resolution

⊙Duration: 50 to 900mm

⊙Independent Linearity: ± 0.05%

⊙displacement speed: 5m / s, 10 m / s optional

⊙Operating temperature: -30 to +100 ℃

⊙a variety of electrical connections

⊙Protection class: IP60 (IP65 optional)

Angular displacement sensor

According to classified material

Metal film sensors, conductive plastic sensors, photoelectric sensors, magnetic sensors, metal glass uranium sensor, the sensor winding.

Potentiometer displacement sensors which components will be through the potentiometer associated mechanical displacement into a linear or any function of the resistance or voltage output. General linear and circular potentiometer potentiometer can be used as a linear displacement, respectively, and the angular displacement sensor. However, to achieve the purpose of measuring the displacement potentiometer designed to require change and resistance change in the displacement of a definite relationship between. Potentiometer displacement sensors and the measured object can be linked to dynamic brush. Potentiometer caused the displacement of objects moving side of the resistance change. Reflect the change in resistance value of displacement, the increase or decrease the resistance that the displacement direction. Usually pass on the potentiometer to supply voltage to the resistance change is converted to voltage output. Wirewound potentiometer wiper is moved due to its resistance to change turn resistance ladder, the ladder-shaped output characteristic was also found .If this displacement sensor used in the servo system position feedback device, the excessive voltage can cause system oscillation step. Therefore, the production of the potentiometer should be to minimize the resistance of each turn. Potentiometer sensor is another major drawback is easy to wear. Its advantages are: simple structure, large output, convenient, low prices.

Hall displacement sensor measuring principle is to maintain its Hall component (see semiconductor magnetic components) of the excitation current constant, and make it in a uniform magnetic field gradient to move, then move the displacement is proportional to the output of the Hall Potential. The greater the magnetic field gradient, the higher the sensitivity; gradient more uniform, Hall electric potential and the closer relationship between the linear displacement. Hall of inertia displacement sensors, high frequency response, reliable, long life, so commonly used in all kinds of non-electricity and then converted into the displacement measurement occasions.

Optical displacement sensor is based on the number of the measured object to block the flux measurement object displacement or geometry. Characterized by a non-contact measurement, and continuous measurements. Optical displacement sensor used in the continuous measurement of wire diameter or the edge of the strip edge position control system for position sensors.

Sensor market prospects

Consulting INTECHNOCONSULTING sensor market report, the global sensor market volume in 2008 was 50.6 billion U.S. dollars, the global sensor market in 2010 up to 600 billion USD. Survey shows that Eastern Europe, Asia Pacific and Canada become the fastest growing region sensor market, while the United States, Germany, Japan remains the largest regional distribution of the sensor market. On a global scale, the sensor market is still the fastest-growing auto market, accounting for the second is the process control market, promising telecommunications market prospects.

Currently, the global sensor market is changing among the innovative trend of rapid growth presents. Experts point out that the main field of sensor technology will be based on the existing extension and increase, States will compete to accelerate next-generation sensor development and industrialization, it will become increasingly fierce competition. Development of new technologies will redefine the future of the sensor market, such as wireless sensors, fiber optic sensors, smart sensors and metal oxide sensors and the emergence of new sensors to expand market share.