Patent ID: 7547875

Claim:
An absolute type encoder apparatus employing an incremental type encoder and a battery to obtain absolute position information in power failure condition, the incremental type encoder comprising a laser diode, an encoder wheel and a photo diode, the absolute type encoder apparatus comprising: a controller electrically connected to the incremental type encoder and supplying a control signal to the incremental type encoder; a comparator electrically connected to the incremental type encoder and processing outputs of the incremental type encoder to generate first pulse signals; a latch unit electrically connected to the controller and the comparator, wherein the latch unit is controlled by the control signal to process the first pulse signals to generate second pulse signals; wherein the controller is adapted to send the control signal of successive pulses and to calculate the second pulse signals to know the absolute position information in power failure condition, and the controller sends the control signals of continuously on state when a rotation speed of the encoder wheel is more than 30 rpm.