1、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
2、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 /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
3、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
4、机（包括单片机进行数据 处理。1、特点:、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。、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。、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。、片选:本电路设有片选端,可以构成多标数显系统。、 COMS 工艺:输入输出的电压电流与 4000系列 CMOS 及 LSTTL
5、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:-3
6、0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
7、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
8、、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
9、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 inductiv
10、e 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 alterna
11、ting 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.IntroductionInducti
12、ve 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
13、 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 a
14、nd 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
15、industries Been increasingly widely used.PrincipleMetrological 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 thinsilk, stacked together, will have
16、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 me
17、asurement 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. Transmissio
18、n 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 displacem
19、ent, 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 r
20、eceiving elements. When the primary grating and grating relative movement direction, the shading effect of leaving the grating Moirfringe 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 so
21、urce and diffraction grating effect, making the signal for the pulse signal.Signal ProcessingTo the principles identifiedIn 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 optoel
22、ectronic devices can not determine the direction of displacement. In order to distinguish the need to have / 2 phase difference of the two moir fringe signals.SubdivisionWith the improvement of measurement accuracy, to pitch as a unit can not meet the requirements, the need to take appropriate measu
23、res to be broken down on the Moire fringe. Subdivision is the so-called changes in the moirfringe 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
24、/ 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 dif
25、ference 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 thefour 90 phase difference signal, t
26、o 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 reversibl
27、e counter Add, subtract, count, can also be sent directly to micro-computer （including MCU for data processing. 1, features: , 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. , cri
28、ticality 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. , absolutely zero control
29、: absolute zero setting will bring much convenience operators, such as power failure after the re-positioning. This circuit has absolutely zero to start countingandstop the count to the absolute zerohas nothing to do with the absolute zero three modes. , Chip Select: This circuit has a chip select t
30、erminal, it can be multi-standard digital display system. , 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 differen
