A code disc, comprising: a code channel component obtained by coding according to a set coding mode, and a fixed grating corresponding to the code channel component, wherein, the coding mode is configured to increase a width of an absolute window of the code channel component; wherein the code channel component comprises: more than one incremental code channel and more than one absolute code channel; the coding mode comprises: reticles of the more than one incremental code channel and the more than one absolute code channel are uniformly distributed with alternate light and dark; wherein the fixed grating comprises: more than one incremental window and more than one absolute window; the more than one absolute window is distributed on a periphery of the more than one incremental window; characterized in that when the coding bit number N of the code disk is equal to four, the more than one incremental window and the more than one absolute window comprise: a first incremental window, a second incremental window, a (N-3)-th absolute window and a (N-4)-th absolute window; the first incremental window comprises four portions arranged by using a four-quadrant split phase method to generate signals A, /A, and B, /B which are configured to obtain sine and cosine signals; the second incremental window comprises two portions phases of which are staggered by 90° to generate two square wave signals with a phase difference of 90°, the two square wave signals are configured to generate a first bit and a second bit of the absolute signal; the (N-3)-th absolute window and the (N-4)-th absolute window are configured to generate a third bit and a fourth bit of the absolute signal. wherein, the coding mode is configured to increase a width of an absolute window of the code channel component; wherein the code channel component comprises: more than one incremental code channel and more than one absolute code channel; the coding mode comprises: reticles of the more than one incremental code channel and the more than one absolute code channel are uniformly distributed with alternate light and dark; wherein the fixed grating comprises: more than one incremental window and more than one absolute window; the more than one absolute window is distributed on a periphery of the more than one incremental window; characterized in that when the coding bit number N of the code disk is equal to four, the more than one incremental window and the more than one absolute window comprise: a first incremental window, a second incremental window, a (N-3)-th absolute window and a (N-4)-th absolute window; the first incremental window comprises four portions arranged by using a four-quadrant split phase method to generate signals A, /A, and B, /B which are configured to obtain sine and cosine signals; the second incremental window comprises two portions phases of which are staggered by 90° to generate two square wave signals with a phase difference of 90°, the two square wave signals are configured to generate a first bit and a second bit of the absolute signal; the (N-3)-th absolute window and the (N-4)-th absolute window are configured to generate a third bit and a fourth bit of the absolute signal.