Contact and non-contact encoder！

An encoder is a device that converts an angular displacement or a linear displacement into an electrical signal. The former becomes the code disk, the latter known as the yardstick. According to the readout mode, the encoder can be divided into two kinds: contact type and non-contact type. Contact with the brush output, a brush contact with the conductive area or insulation area to indicate the status code is "1" or "0"; non-contact to accept the sensor is a photosensitive element or magnetic components, photosensor Light-transmitting area and opaque area to indicate whether the state of the code is "1" or "0". According to the working principle of the encoder can be divided into two types of incremental and absolute. Incremental encoder is the displacement into a periodic electrical signal, then the electrical signal into a count pulse, with the number of pulses that the size of the displacement. Each position of the absolute encoder corresponds to a definite digital code, so its indication is only related to the starting and ending positions of the measurement, independent of the intermediate process of the measurement. Rotary incremental encoder to rotate the output pulse, through the counting device to know its position, when the encoder does not move or power failure, relying on the internal memory of the counting device to remember the location. In this way, when the power failure, the encoder can not have any movement, when the caller work, the encoder output pulse process, there can be no interference and loss of pulse, otherwise, the zero point will be offset device memory, and this bias The amount of shift is no way to know, only the wrong results of the production to know. The solution is to increase the reference point, the encoder after each reference point, the reference position will be corrected into the memory location of the counting device. Prior to the reference point, the accuracy of the position can not be guaranteed. To this end, there is every time in the industrial control to find the first reference point, boot to change and other methods. For example, the positioning of the printer scanner is the incremental encoder principle, each boot, we can hear the crackle of a ring, it is looking for reference zero, and then work. Incremental encoder features: Incremental encoder shaft rotation, the corresponding pulse output, the count of the starting point of any set, to achieve multi-turn infinite accumulation and measurement. The encoder shaft rotates one revolution to output a fixed pulse. The number of pulses is determined by the number of encoders. Need to improve the resolution, you can use 90 degrees phase difference of the A, B two-way signal or the replacement of high-resolution encoder.

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