off-axis encoder design！

With technology innovation, magnetic encoder now has comparable optical encoder performance to a large extent, particularly ground-breaking off-axis design appears, for the magnetic encoder in a wider field of application creation a chance to show their skills. As a leader in this field, Timken Timken® off-axis magnetic encoder solve practical problems such as calibration.

Timken® off-axis magnetic encoders for multi-pole magnetic encoder chip mounting position deviated from the axis of rotation center. During operation, each pair will have a very positive cosine signals of one cycle, and insert converts the quadrature position signal via a serial or internal hardware. When the motor shaft rotates up, chip in the radial extent of the Hall element sensitive to the magnetic field strength remains constant radial motor shaft jitter (as long as the radial extent of the induced magnetic field Hall) will not affect the Hall Seoul accuracy sensor output signal. So, just make sure the chip and radial position in the actual installation process, the installation distance (with the magnetic pole pitch of about), will be able to ensure the accuracy of the output signal.

newmaker.com
Figure 2: 4% interpolator error
Off-axis magnetic encoder to improve the accuracy, but also to its code wheel diameter and changes of the magnetic poles related. In the mechanical effect of the gain, the greater the smaller the diameter of the coaxial magnetic encoder error, while the larger diameter off-axis encoder pole error is smaller. Gain precision interpolator shown in FIG aspect, a coaxial design for the direct display: 1, and the off-axis type of magnetic poles in a multiple error reduction. If the off-axis design including 32 pairs of poles, just to give each pair from the pole to the low resolution of interpolated magnification 1/32, compared to coaxial design is required into the final resolution over the entire period interpolated high magnification.

In addition, coaxial encoder typically within DSP chip interpolation processing cosine signal, although higher multiples but often require a longer response time. Off-axis encoder within just a hardware device can be inserted low magnification, even at more than 10000rpm spindle speed can work the case, first class stability.

Shown coaxial with the off-axis encoder and fully tested in a radial tolerance range results in Figure 3. Experimental comparison of three concentric encoders from different manufacturers, showed Timken® off-axis encoder error is significantly less than three coaxial encoder. But during the installation under the chip has not been properly positioned, the off-axis encoder error is smaller than coaxial.

Timken® off-axis magnetic coding can be achieved mainstream optical incremental encoder 0-5000 pulses / turn even higher resolution. With patented magnetizing magnetic field detection process technology, Timken according to customer requirements, flexibility in the design and production of a range of different specifications 0.8mm-4mm pitch magnetic code wheel, coupled with chip sensors meet the various needs of practical applications.

Previous：Off-axis encoder design
Next：Off-axis magnetic encoder designed to open up new application areas