Absolute Linear Encoder

Incorporating absolute technology to a multi-substrate scale tape linear encoder design, Heidenhain introduces the LIC 4000. Besides its capability of absolute position measurement, this encoder is characterized by its high resolution of 1 nanometer and its serial EnDat 2.2 interface. Absolute encoders, which provide the current position immediately upon switch-on, offer high technological reliability and safety because they do not need the reference runs that would otherwise be necessary, the company says. The encoders are suited for use on direct drives. Together with the current position, the commutation offset is known immediately upon switch-on and the motor can immediately be provided with power and held in the control loop. According to the company, critical operating states, such as switching on a vertical axis with direct drive or retraction after an emergency stop, are controlled safely. Because of their specialized scanning technologies, these encoders are said to be insensitive to contamination and therefore guarantee a high degree of equipment availability and a high traverse speed, while at the same time achieving a high resolution. The encoders are available with as many as 27 m of measuring length. The dimensions of the LIC 4000 match those of the company’s LIDA 400 incremental linear encoder. This makes it possible to retrofit today’s machine tools to absolute measurement technology by exchanging the encoders. Only the subsequent electronics must be adapted correspondingly. Exposed linear encoders are characterized by their high accuracy, workable mounting tolerances, high traversing velocity, and low height of the scanning head.