System and method for delay calibration in position encoders

An encoder readhead apparatus for a position encoder system which determines a delay time calibration usable to provide a desired position sample delay time for the position encoder system, the encoder readhead apparatus comprising a position transducer element and a transducer electronics, the transducer electronics comprising:

• at least one signal input line and at least one signal output line connectable to an encoder interface circuit of the position encoder system;
• a logic circuit connected to receive signal information input on the at least one signal input line, and to provide signal information sent on the at least one signal output line;
• a signal processing circuit connected to input at least one digital signal from and output at least one digital signal to the logic circuit and further connected to input at least one position signal from the position transducer element;
• and
• at least one local oscillator circuit providing a periodic signal connected to at least one of the signal processing circuit and the logic circuit;
• wherein:
• the logic circuit is operable to start a position signal sampling sequence in the readhead in response to signal information input on the at least one signal input line;
• the signal processing circuit portion is operable to sample the at least one position signal during the position signal sampling sequence;
• at least one of the signal processing circuit and the logic circuit is further operable to generate timing signals during the position signal sampling sequence;
• and
• the logic circuit is further operable to send the timing signals on the at least one signal output line to the interface electronics of the position encoder system at least when the interface electronics is configured to determine time values based on measurement of the sent timing signals and determine the delay time calibration based on the time values.

A method for operating a position encoder system to determine a delay time calibration usable to provide a desired position sample delay time for the position encoder system, the position encoder system comprising an interface circuit, a scale and a readhead, the method comprising:

• sending at least one calibration signal from the interface circuit to the readhead;
• starting a position signal sampling sequence in a calibration mode of the readhead in response to receiving the at least one calibration signal;
• performing the position signal sampling sequence in the readhead;
• sending timing signals generated during the position sampling sequence from the readhead to the interface circuit;
• and
• determining the delay time calibration based the sent timing signals and a clock signal generated in the interface circuit.

A position encoder system which determines a delay time calibration usable to provide a desired position sample delay time for the position encoder system, the position encoder system comprising a scale, a readhead and an encoder interface circuit connectable to a host processor, the readhead comprising a position transducer element and a transducer electronics, the transducer electronics comprising:

• at least one signal input line and at least one signal output line connectable to the encoder interface circuit;
• a logic circuit connected to receive signal information input on the at least one signal input line, and to provide signal information sent on the at least one signal output line;
• a signal processing circuit connected to input at least one digital signal from and output at least one digital signal to the logic circuit and further connected to input at least one position signal from the position transducer element;
• and
• at least one local oscillator circuit providing a periodic signal connected to at least one of the signal processing circuit and the logic circuit;
• wherein:
• the interface circuit is operable to send at least one calibration signal to the readhead on the at least one signal input line;
• the logic circuit is operable to start a position signal sampling sequence in a calibration mode of the readhead in response to the at least one calibration signal;
• the signal processing circuit portion is operable to sample the at least one position signal during the position signal sampling sequence;
• at least one of the signal processing circuit and the logic circuit is further operable to generate timing signals during the position signal sampling sequence;
• the logic circuit is further operable to send the timing signals on the at least one signal output line to the interface electronics of the position encoder system;
• and
• the interface circuit is operable to determine the delay time calibration based on the sent timing signals and a clock signal generated in the interface circuit.