There are many scribe lines on the optical code disk of absolute encoder, and each scribe line is 2 lines, 4 lines, 8 lines and 16 lines in turn. . . . . . In this way, at each position of the encoder, a unique set of binary codes (Gray codes) from power 0 of 2 to power n- 1 can be obtained by reading the on-off of each line, which is called an n-bit absolute encoder. Such an encoder is determined by the mechanical position of the code wheel and is not affected by power failure and interference.
The uniqueness of each position of the absolute encoder is determined by the mechanical position. It doesn't need to remember, find a reference point, and it doesn't need to keep counting. Whenever it needs to know its location, it needs to read its location. This greatly improves the anti-interference characteristics and data reliability of the encoder.
Because absolute encoder is obviously superior to incremental encoder in positioning, it has been used more and more in industrial positioning. The absolute encoder has high precision and many output bits. If parallel output is still used, every bit of the output signal must be connected. For more complicated working conditions, it must be isolated, and there are many connected cable cores, which brings a lot of inconvenience and reduces reliability. Therefore, in the multi-bit output type, absolute encoders generally choose serial output or bus output. SSI (Synchronous Serial Output) is the most commonly used serial output of absolute encoders made in Germany.
3. Single-turn absolute encoder and multi-turn absolute encoder
Rotate the single-turn absolute encoder, measure each scribe line of the rotating optical code disk, and get the unique code. When the rotation exceeds 360 degrees, the coding returns to the original point, which does not conform to the principle of unique absolute coding. This kind of encoder can only be used for measuring in the range of 360 degrees rotation, and it is called a single-turn absolute encoder.
If you want to measure more than 360 degrees of rotation, you need to use a multi-turn absolute encoder.
Encoder manufacturers use the principle of clock gear machinery. When the central code wheel rotates, the other set of code wheels (or multiple sets of gears and multiple sets of code wheels) is driven by gears, which increases the number of turns on the basis of single-turn coding and expands the measuring range of the encoder. This kind of absolute encoder is called multi-turn absolute encoder, which is also determined by the mechanical position. Each position code is unique and does not need to be memorized.
Another advantage of multi-turn encoder is that it is often rich in practical use because of its large measurement range. When installing, you don't need to find the zero point, and a middle position can be used as the starting point, which greatly simplifies the difficulty of installation and debugging.
Multi-turn absolute encoder has obvious advantages in length positioning, and has been more and more used in industrial positioning.
4. Mechanical installation and use of absolute rotary encoder:
Mechanical installation of absolute rotary encoder includes high-speed end installation, low-speed end installation and auxiliary mechanical device installation.
1) high-speed end installation: it is installed at the rotating shaft end (or gear joint) of the power motor. This method has the advantage of high resolution. Because the multi-turn encoder has 4096 turns, and the number of motor revolutions is within this range, the full range can be fully utilized to improve the resolution. The disadvantage is that the moving object has gear clearance error after passing through the reduction gear, which is generally used for unidirectional high-precision control and positioning, such as roll gap control of steel rolling. In addition, the encoder is directly installed at the high-speed end, so the motor jitter must be small, otherwise it is easy to damage the encoder.
2) Installation of low-speed end: it is installed behind the reduction gear, such as the shaft end of the winding wire rope drum or the end of the last reduction gear shaft. This method has no gear return clearance, so the measurement is more direct and accurate. This method generally measures long-distance positioning, such as the positioning of various lifting equipment and feeding trolley.
Absolute rotary photoelectric encoder has been widely used in angle and length measurement and positioning control in various industrial systems because of its absolute uniqueness, anti-interference and no power-off memory.
There are many scribe lines on the optical code disk of absolute encoder, and each scribe line is 2 lines, 4 lines, 8 lines and 16 lines in turn. . . . . . In this way, at each position of the encoder, a unique set of binary codes (Gray codes) from power 0 of 2 to power n- 1 can be obtained by reading the on-off of each line, which is called an n-bit absolute encoder. Such an encoder is determined by the mechanical position of the code wheel and is not affected by power failure and interference.
The uniqueness of each position of the absolute encoder is determined by the mechanical position. It doesn't need to remember, find a reference point, and it doesn't need to keep counting. Whenever it needs to know its location, it needs to read its location. This greatly improves the anti-interference characteristics and data reliability of the encoder.
Because absolute encoder is obviously superior to incremental encoder in positioning, it has been used more and more in industrial positioning. The absolute encoder has high precision and many output bits. If parallel output is still used, every bit of the output signal must be connected. For more complicated working conditions, it must be isolated, and there are many connected cable cores, which brings a lot of inconvenience and reduces reliability. Therefore, in the multi-bit output type, absolute encoders generally choose serial output or bus output. SSI (Synchronous Serial Output) is the most commonly used serial output of absolute encoders made in Germany.
3. Single-turn absolute encoder and multi-turn absolute encoder
Rotate the single-turn absolute encoder, measure each scribe line of the rotating optical code disk, and get the unique code. When the rotation exceeds 360 degrees, the coding returns to the original point, which does not conform to the principle of unique absolute coding. This kind of encoder can only be used for measuring in the range of 360 degrees rotation, and it is called a single-turn absolute encoder.
If you want to measure more than 360 degrees of rotation, you need to use a multi-turn absolute encoder.
Encoder manufacturers use the principle of clock gear machinery. When the central code wheel rotates, the other set of code wheels (or multiple sets of gears and multiple sets of code wheels) is driven by gears, which increases the number of turns on the basis of single-turn coding and expands the measuring range of the encoder. This kind of absolute encoder is called multi-turn absolute encoder, which is also determined by the mechanical position. Each position code is unique and does not need to be memorized.
Another advantage of multi-turn encoder is that it is often rich in practical use because of its large measurement range. When installing, you don't need to find the zero point, and a middle position can be used as the starting point, which greatly simplifies the difficulty of installation and debugging.
Multi-turn absolute encoder has obvious advantages in length positioning, and has been more and more used in industrial positioning.
4. Mechanical installation and use of absolute rotary encoder:
Mechanical installation of absolute rotary encoder includes high-speed end installation, low-speed end installation and auxiliary mechanical device installation.
1) high-speed end installation: it is installed at the rotating shaft end (or gear joint) of the power motor. This method has the advantage of high resolution. Because the multi-turn encoder has 4096 turns, and the number of motor revolutions is within this range, the full range can be fully utilized to improve the resolution. The disadvantage is that the moving object has gear clearance error after passing through the reduction gear, which is generally used for unidirectional high-precision control and positioning, such as roll gap control of steel rolling. In addition, the encoder is directly installed at the high-speed end, so the motor jitter must be small, otherwise it is easy to damage the encoder.
2) Installation of low-speed end: it is installed behind the reduction gear, such as the shaft end of the winding wire rope drum or the end of the last reduction gear shaft. This method has no gear return clearance, so the measurement is more direct and accurate. This method generally measures long-distance positioning, such as the positioning of various lifting equipment and feeding trolley.
3) Installation of auxiliary machinery:
Commonly used are rack and pinion type, chain belt type, friction wheel type, rope take-up mechanical type and so on.
5. Functional characteristics of optical encoder
Adopt reflection induction technology
Surface mount leadless package
Provides two analog signal outputs.
Counting frequency: 20 kHz
It operates with a single 5.0V power supply.
Operating temperature:-10 to 70oC