A Design Study of a Heat Flow-Type Reading Head for a Linear Encoder Based on a Micro Thermal Sensor

A new concept of reading head for a linear encoder, in which graduations on a scale grating are read by using a micro thermal sensor composed of a thin film resistor, is proposed to realize a compact encoder system. In the proposed reading head, measurement of the in-plane relative displacement between the micro thermal sensor and the scale grating will be carried out in such a way that the graduations on a scale grating are read by the micro thermal sensor through the change in the heat flow between the sensor and the scale grating surface. In this paper, as the first step of research, theoretical calculations based on the theory of heat flow between the sensor and scale interface are carried out. In addition, basic experiments are carried out to search for the possibility of realizing the proposed concept of the reading head based on the micro thermal sensor.