Off-axis magnetic encoder designed to open up new application areas！

Off-axis magnetic encoder designed to open up new application areas
     The encoder used to measure the relevant data servo motor system and corner speed. At present, optical encoders and magnetic encoders used in two on the market. Compared with the former, since the magnetic encoder oil condensate from dirt dust effects, as well as other pollutants, in recent years it has been on the market more and more attention. The use of advanced design magnetic encoder technology provides comparable optical encoder accuracy (resolution), and can substantially reduce production costs while improving system efficiency.

1 Introduction

In the field of industrial automation, the encoder position as the representative of the speed sensor are playing an increasingly important role. Wherein the optical encoder for its fast response time, high precision and by a large number of users of all ages. However, the use of photoelectric pulse signal output device unit vulnerable to vibration, interference dust, humidity, temperature and other environmental factors, thus affecting the output signal and its own life. Compared with optical encoders, magnetic field and the Hall sensor generates a magnetic encoder signals, environmentally adaptable, integrated chip feedback system is also more accurate. Obvious advantages of its value in the emerging high-precision measurement and control related applications in the field.

2. Restrict heavy coaxial encoder

Magnetic encoders typically employ two different designs. Currently, the market is still coaxial magnetic encoder mainstream products.

Coaxial magnetic encoder for single-pole rare earth magnets mounted on the rotating shaft axis, forming an annular array induction use 4-8 Hall element. Two opposing Hall sensors connected to a differential amplifier, each revolution will produce a sine and cosine signal period by converting (often through DSP chip operation) position or serial input quadrature signals.

Coaxial magnetic encoder detection method is low cost, but the equipment is installed high demands. Magnetic north and south poles midpoint, center of the chip and the center of the motor shaft must be kept in the same line, because any installation errors will reduce the accuracy of the encoder. However, in practice, only radial dither motor shaft can not be avoided, and the bias magnet relative displacement caused by the chip will also affect the accuracy of the actual output signal. Further, from the inner coaxial design requires a cycle into the final resolution of the high magnification inserted, once the speed exceeds a certain range can not be accurately read the position information of the point by point, resulting in reduced accuracy of the actual output. For these reasons, coaxial magnetic encoder has long been concentrated in relatively lower-end applications.

Previous：off-axis encoder design
Next：Rotary optical encoder design trends 4