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Measuring angles with rotary encoders


Rotary encoders from HEIDENHAIN serve as measuring sensors for rotary motion, angular velocity and also, when used in conjunction with mechanical measuring standards such as lead screws, for linear motion. Application areas include electrical motors, machine tools, printing machines, woodworking machines, textile machines, robots and handling devices, as well as various types of measuring, testing, and inspection devices.

  • Line counts of typically 50 to 5000
  • Accuracy from ± 12" (depending on the line count, corresponding to ± 1/20 of the grating period)
  • Measuring steps to 0.001°.
  • The high quality of the sinusoidal incremental signals permits high interpolation factors for digital speed
    control.

In rotary encoders with integral bearing and stator coupling, the graduated disk of the encoder is connected directly to the shaft to be measured. The scanning unit is guided on the shaft via ball bearings, supported by the stator coupling. During angular acceleration of the shaft, the stator coupling must absorb only that torque resulting from friction in the bearing, thereby minimizing both static and dynamic measuring error. Moreover, the coupling mounted on the stator compensates axial motion of the measured shaft. Other benefits of the stator coupling are:

  • Simple mounting
  • Short overall length
  • High natural frequency of coupling

  • Hollow-through shaft possible

Rotary encoders with integral bearing that are conceived for separate shaft coupling are designed with a solid shaft. The recommended coupling to the measured shaft compensates radial and axial tolerances. Angle encoders for separate shaft couplings permit higher shaft speeds.
Rotary encoders without integral bearing operate without friction. The two components - the scanning head and the scale disk, drum, or tape - are adjusted to each other during assembly. The benefits are:

  • Large diameter of hollow shaft
  • For high shaft speeds
  • No additional starting torque.
 
Updated 08/2008