Velocity detecting apparatus and liquid ejecting apparatus

A liquid ejecting apparatus comprising:

• a carriage configured to move reciprocatingly in a scanning direction;
• a liquid ejecting head mounted on the carriage, the liquid ejecting head being formed with nozzles and configured to eject liquid from the nozzles;
• and
• a velocity detecting apparatus configured to detect velocity of the carriage, the velocity detecting apparatus comprising:
• a region formation member having a first region and a second region that are arranged cyclically in the scanning direction, the first region and the second region having different optical characteristics from each other;
• an optical sensor disposed on the carriage, the optical sensor being configured to emit light to the region formation member and to output a pre-correction pulse signal that is on a first level when emitting light toward the first region and that is on a second level when emitting light toward the second region, the second level being different from the first level, the optical characteristics of the first region and the second region being such that the optical sensor receives a larger amount of light from the second region than from the first region;
• and
• a controller configured to control the optical sensor and the carriage, the controller being configured to perform:
• correcting the pre-correction pulse signal outputted from the optical sensor and outputting the corrected pre-correction pulse signal as a post-correction pulse signal that switches between a third level and a fourth level different from each other, the correcting comprising:
• switching the post-correction pulse signal from the third level to the fourth level when at least one of a first condition and a second condition is satisfied, the first condition being that the pre-correction pulse signal switches from the first level to the second level, the second condition being that duration of a section in which the post-correction pulse signal is on the third level exceeds a first reference period;
• and
• switching the post-correction pulse signal from the fourth level to the third level when both of a third condition and a fourth condition are satisfied, the third condition being that duration of a section in which the post-correction pulse signal is on the fourth level exceeds a second reference period, the fourth condition being that the pre-correction pulse signal is on the first level;
• and
• calculating a moving velocity of the carriage based on temporal changes between the third level and the fourth level of the post-correction pulse signal.