the advantages and disadvantage of Photoelectric encoder, optical scale and static magnet?

Photoelectric encoder:

1, advantages: small volume, precision, high resolution can be (currently our company through subdivision technology on diameter phi 66 encoder can reach 54000 CPR), no contact wear; Same breed is detectable Angle displacement, and can help in mechanical conversion device to detect linear displacement; Many photoelectric absolute encoder can detect a considerable range of linear displacement (e.g., more than 25 circle). Long life, casual, installation form of interface is rich, the price is reasonable. Mature technology, has been widely used at home and abroad years ago.

2, the faults: precision but for outdoor and used under the bad environment put forward higher protection requirements; Relies on measuring linear displacement mechanism transformation, to avoid the error caused by mechanical clearance; Slip detection objects orbiting difficult to overcome.

Optical electronic scale:

1, advantages: precision, high resolution (0.005 mm); Moderate volume, direct measurement of linear displacement; No contact wear and broad measuring clearance; Moderate price, the interface form is rich, has been applied to metal cutting machine industry at home and abroad to get more (such as wire cutting, edm, etc.).

2, the shortcomings: linear and Angle measurement to use different varieties; Range limited (range more than 4 m, manufacturing difficulty is expensive), is not suitable for implementation in the bad environment in a wide range displacement test.

Static magnetic grid absolute encoder:

1, advantages: moderate volume, direct measurement of linear displacement, absolute digital coding, theory there is no limit to the range; No contact no abrasion, resistance to bad environment, can be used underwater 1000 m; Interface form rich, measurement way diversity; The price is acceptable.

2, the faults: 1 mm is not high resolution; Measuring line and Angle to use different varieties; Not suitable for implementation in the essence of small displacement test (greater than 260 mm).