1、1 The properties and application of photoelectric encoder The working principle, photoelectric encoder Photoelectric encoder, is a kind of photoelectric transformation through the machine will output shaft geometric displacement convert pulse or digital sensors. This is the most sensor, photoelectri
2、c encoder and grating is by photoelectric detection device. Grating is in certain parts of the diameter of the circular plate to open several rectangle hole. Caused by the code, motor and motor coaxial rotates grating and motor rotate speed, with the light emitting diode and other electronic compone
3、nts testing unit output pulse signal with several, its principle diagram is shown in figure 1, Through the calculation of the output pulse of photoelectric encoder per number can reflect the current motor speed. In addition, the direction of rotation, the code for the judge may also provide phase di
4、fference dish of 90 two pulses. According to the measuring principle, encoder can be divided into optical and magnetic type, inductive and capacitor. According to the calibration method and the signal output form, can be divided into incremental, absolutely and hybrid three. Incremental encoder Incr
5、emental encoder is directly for the use of photoelectric pulse output three square principle of A and B and Z, A and B group phase, pulse 90 can easily identify rotation direction, and for every turn A phase Z benchmark for positioning. Pulse, Its advantages are simple structure, mechanical principl
6、e, average life expectancy in tens of thousands of hours, strong anti-jamming capability, high reliability, suitable for long distance transmission. Its defect is not the absolute output shaft rotation location information. 图 1 光电编码器的远离示意图 Absolute photoelectric encoder Absolute encoder is direct di
7、gital output sensor, in its circular yards on several concentric yards along the radial direction of every faith, by pervious to light and not pervious to light, the sector and the adjacent code number of sectors, encoder is double the code number of bits of it in the code of digits, light source, t
8、he other side is one word has a corresponding yard photosensitive components, When the code in different position, the dish by various photosensitive components according to the corresponding conversion or light signals, binary 2 number level. This is not the encoder counter in the shaft can be read
9、 at any position of a fixed position corresponds with the digital code. Obviously, the word, the more the high resolution, for a N binary resolution coder code salver must have N barcode. Currently there are 16 bits of absolute encoder products. Single channel absolute photoelectric shaft encoder is
10、 using the natural binary or circular binary (Gregory yards) manner photoelectric conversion. Absolute photoelectric encoder and incremental encoder differs not pervious to light on the disk, the line, absolute encoders may have graphics, according to the number of code read code on coding, detectio
11、n absolute position. Code design can use binary code, circulation, binary complement, etc. Its features are: Can read Angle of absolute coordinates directly. No accumulative error. Power excision location information would be lost. But the resolution is determined by the binary digits, i.e., precisi
12、on depends on the median 10, 14 etc. Hybrid absolute encoder. Hybrid absolute encoders, its output of two groups: a group of information, information for testing poles with absolute information function, Another group of incremental encoder is completely with the output information. Photoelectric en
13、coder is an Angle (angular velocity) detection device, it will input shaft Angle for, using the principle of photoelectric convert electrical or digital accordingly, small size, high accuracy, high reliability, digital interface, etc. It is widely applied in nc machine tools, turning machine, servo
14、drive, robots, radar and military targets were needed in the Angle of device and equipment. Applied circuit of photoelectric encoder EPC - 755A application of photoelectric encoder EPC - 755A photoelectric encoder and the use of good performance in Angle measurement, displacement measurement, and ha
15、s strong anti-jamming capability of the output pulse signal is stable and reliable, and the pulse signal can be obtained by counting were measured after the digital signal. Therefore, we in the car driving simulators, steering wheel rotation Angle measurement chooses EPC - 755A photoelectric encoder
16、, the output circuit as sensors, choose open collector output resolution selection 360 pulse/circle, considering the steering wheel rotation is a two-way street, clockwise and counterclockwise, can also needs to the output signal phase coder to count. Figure 2 shows the actual use of photoelectric e
17、ncoder and discrimination, phase two-way counts circuit with a D flip-flop circuit and two cross-coupled nand gates, with 74LS193 3 counts circuit. 3 图 2 光电编码器鉴相计数电路 When the photoelectric encoder clockwise, channel, A leading channel output waveform of output waveform B 90 , D flip-flop output wave
18、form W1) for Q (high level, Q (W2) for low-level waveform cross-coupled nand gates, open, counting pulse waveform W3) by (bidirectional, send to the 74LS193 counter CU input pulses, add count, At this time, below, its output cross-coupled nand gates close for high level (waveform W4). When the photo
19、electric encoder counter-clockwise, channel A output waveform of output waveform delay than channel B 90 , D flip-flop output waveform W1) for Q (low level, Q (W2) for high level waveform, the output cross-coupled nand gates close, high level (waveform W3), Now, two cross-coupled nand gates open, co
20、unting under impulsive through (waveform W4), send to two-way 74LS193 counter reduced input pulses, CD. Subtraction. Steering wheel clockwise and counter-clockwise, the maximum rotation Angle for two laps, choose resolution for 360 pulse/circle of the output pulse coder, its biggest for 900, Actual use three slices of counts circuit 74LS193 component in the system of initialization, the signal reset (CLR), the initial set for 800H, namely 2048 (LD)； the signal, So, when the steering wheel clockwise, count the output circuit for 2048 2948, when steering counter-clockwise,
