Rotary encoder resolution！

Rotary encoder resolution


Resolution, also known as the median number of pulses, a few wire (absolute encoder have this title), for incremental encoder pulse number is in terms of rotation of the shaft encoder output; the absolute encoder device, it is equivalent to around 360 ° was divided into many parts, such as the resolution is 256P / R, is equal to around 360 ° aliquots became 256, each rotating about 1.4 ° outputs a code value. Of the resolution of the P / R.
Resolution: line (line), is the optical reticle encoder code wheel, if the encoder is a direct square wave output, it is the pulses per revolution (PPR) (Figure 1), but if it is positive cosine (sin / cos) signal output can be varied by sub-divisional analog signal to get more square wave pulse PPR output (Fig. 2), square-wave output encoder has a and phase B, a B phase difference 1/4 pulse period is determined by the rising and falling edges can be obtained in steps of 1/4 pulse period from (4x), which is the smallest measuring step (step), so, strictly speaking, , the smallest measuring step is the resolution of the encoder.
For example, Germany HEIDENHAIN ROD426 3600 line encoder, square wave output is 3600ppr, pulse period of 0.1 degrees by the A phase after phase B 4x obtained 0.025 degrees measuring steps; and its HEIDENHAIN offer precision parameter is 18 seconds of arc (0.005 degrees). Resolution values ​​greater than the precision value.
If positive cosine signal output Heidenhain 3600 line ROD486 can be 25 times the electronic segment, obtained 90,000 pulses (ppr), 0.004 degrees pulse period, quadruple through A / B phase can be get 0.001 of a minimum resolution of measuring steps, and the original HEIDENHAIN encoders provide accuracy is 18 arc seconds (0.005 degrees), (excluding sub-divisional error). Resolution value is less than the precision value.
In a communication data output type encoder or absolute encoder, the output resolution is the number of "bits" to express that the circumferential segmentation of a power of 2.

Encoder resolution
Encoder resolution


Therefore, the resolution of the rotary encoder can be expressed respectively by "wire line", the number of pulses per revolution PPR, or "Step Step". With lines to express, may also be subdivided, and some "17" of the encoder is for the actual pitches, it has been the breakdown of good. A 3600 line encoder, the resolution also entirely possible better than a "17" has a good breakdown of the encoder.

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