Basic Structure and Characteristics of Absolute Photoelectric Encoder！

With the incremental photoelectric encoders it is possible to generate count errors due to external disturbances and the correct position of the components before the accident can not be found after a power failure or a faulty stop. Absolute optical encoder can be used to avoid these shortcomings. Absolute photoelectric encoder of the basic principles and components and incremental photoelectric encoder is basically the same, but also by the light source, code disc, detection grating, photoelectric detection devices and conversion circuit components. Unlike the incremental photoelectric encoders, the photoelectric encoder uses a different number to indicate each different incremental position, which is a direct output digital sensor. In its circular code disc along the radial number of concentric code channel, each by the light transmission and opaque sectors of the phase, adjacent to the number of sectors of the code is double the relationship between the code disc The number of code channels is the number of bits of its binary code, one side of the code plate is the light source, the other side corresponds to each code channel has a photosensitive element; When the code disc in different positions, the photosensitive element according to the light or not The corresponding level signal, the formation of binary numbers. This encoder is characterized not to counter, anywhere in the shaft can be read out with a fixed position corresponding to the digital code. Obviously, the more code, the higher the resolution, for a binary resolution with N-bit encoder, the code must have N code channel. Absolute photoelectric encoder principle shown in Figure 1-8. Absolute photoelectric encoder is the use of natural binary, cyclic binary (Gray code), two-decimal system, such as photoelectric conversion. Absolute photoelectric encoder and incremental optical encoder is different in the disc light transmission, opaque line pattern, the absolute optical encoder can have a number of coding, according to the code read out the encoder to detect the absolute position . It is characterized by:
The absolute value of the angle coordinate can be read directly; there is no accumulation error; the position information after the power supply is cut off will not be lost; the precision of the encoder depends on the number of bits; the maximum operation speed is higher than the incremental photoelectric encoder.

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