Abstract: A method for controlling a torque of a door opening and closing motor for an automatic door is improved in that the door opening and closing motor is such motor that a rotary torque therein is generated on the basis of control pulses applied to that motor from a control unit, the rotary torque is regulated by changing a total pulse width of the control pulses rising in one repetition cycle, and thereby an acceleration of the motor can be controlled. In one preferred mode of embodiment of the invention, each of the control pulse has a fixed pulse width, and th total pulse width is changed by varying the number of the control pulse rising in one repetition cycle.

Abstract: For the purpose of knowing an angular position and a rotational speed of a rotary body, according to an encoding pattern on an encoder mounted to and synchronously rotated with the rotary body, rotational angular position signals consisting of n-phase rectangular waves and sensing pulses occurring at a predetermined rotational angle interval are generated. In response to the issue of each sensing pulse, levels of the respective rotational angular position signals are detected, a variation pattern of a combination of the detected n levels is compared with a reference variation pattern, and it is determined whether an abnormal condition has arisen or not, and if the condition is normal, whether the variation pattern is a forward traveling pattern or a backward traveling pattern. In the case of the forward traveling pattern, (+1) is added to a rotational angle counter, while in the case of the backward traveling pattern, (-1) is added to the rotational angle counter.