Phase locked state detecting apparatus and image processing apparatus

An information processing apparatus including a phase locked state detecting apparatus for detecting a phase locked state of a processing clock signal generated by a phase locked loop and used in an information processing, the phase locked state detecting apparatus comprising:

• a comparing device which compares a phase of a reference clock signal as the reference for controlling a phase of the processing clock signal by the phase locked loop with a phase of the processing clock signal and generates a comparison signal;
• a detecting device which detects a frequency of the processing clock signal and generates a detecting signal;
• a first determining device which determines on the basis of the comparison signal whether or not the processing clock signal is in the phase locked state with respect to the reference clock signal;
• and a second determining device which determines on the basis of the detecting signal whether or not the phase locked state is canceled after the first determining device determines that the processing clock signal is in the phase locked state, the information processing apparatus comprising:
• a phase comparing device which detects a phase difference between the reference clock signal and the processing clock signal and outputs a phase difference signal in the phase locked loop;
• a filter device which subjects the outputted phase difference signal to a predetermined filter processing and outputs a filter signal in the phase locked loop;
• a generating device which generates an oscillation clock signal based on the outputted filter signal in the phase locked loop;
• a frequency division device which divides a frequency of the generated oscillation clock signal, generates the processing clock signal and outputs the processing clock signal to the phase locked state detecting apparatus and the phase comparing device in the phase locked loop;
• and
• a processing device using the processing clock signal in the phase locked state with respect to the reference clock signal to perform an information processing based on a result of the determination in the phase locked state detecting apparatus.

A phase locked state detecting method for detecting a phase locked state of a processing clock signal generated by a phase locked loop and used in an information processing, the phase locked state detecting method comprising:

• a comparing process which compares a phase of a reference clock signal as the reference for controlling a phase of the processing clock signal by the phase locked loop with a phase of the processing clock signal and generates a comparison signal;
• a detecting process which detects a frequency of the processing clock signal and generates a detecting signal;
• a first determining process which determines on the basis of the comparison signal whether or not the processing clock signal is in the phase locked state with respect to the reference clock signal;
• and
• a second determining process which determines on the basis of the detecting signal whether or not the phase locked state is canceled after the first determining device determines that the processing clock signal is in the phase locked state.

An information processing method including a phase locked state detecting method for detecting a phase locked state of a processing clock signal generated by a phase locked loop and used in an information processing, the phase locked state detecting method comprising:

• a comparing process which compares a phase of a reference clock signal as the reference for controlling a phase of the processing clock signal by the phase locked loop with a phase of the processing clock signal and generates a comparison signal;
• a detecting process which detects a frequency of the processing clock signal and generates a detecting signal;
• a first determining process which determines on the basis of the comparison signal whether or not the processing clock signal is in the phase locked state with respect to the reference clock signal;
• and a second determining process which determines on the basis of the detecting signal whether or not the phase locked state is canceled after the first determining process determines that the processing clock signal is in the phase locked state, the information processing method comprising:
• a phase comparing process which detects a phase difference between the reference clock signal and the processing clock signal and outputs a phase difference signal in the phase locked loop;
• a filter process which subjects the outputted phase difference signal to a predetermined filter processing and outputs a filter signal in the phase locked loop;
• a generating process which generates an oscillation clock signal based on the outputted filter signal in the phase locked loop;
• a frequency division process which divides a frequency of the generated oscillation clock signal, generates the processing clock signal and outputs the processing clock signal so as to be used for the phase locked state detecting process and the phase comparing process in the phase locked loop;
• and
• a processing process using the processing clock signal in the phase locked state with respect to the reference clock signal to perform an information processing based on a result of the determination of the first determining process or the second determining process.