ENCODER READHEAD APPARATUS

摘要

The present invention relates to an encoder readhead (4;80;1 10). The readhead comprises a housing (6;82) having an opening ( 18) for capturing an encoder scale (2; 124) comprising an elongate rod having a substantially circular cross-section, the opening (18) defining an axial direction along which a captured encoder scale (2; 124) can slide back and forth. A scale reader ( 10), which may comprise an array of Hall sensors, is provided for reading a portion of an encoder scale (2; 124) located in the opening (18). The housing (6;82) includes an access portion (30) that allows the encoder scale (2; 124) to be inserted into, and/or removed from, the opening (18) by a relative movement between the housing (6;82) and the encoder scale (2; 124) in a direction other than the axial direction.