Gear defect detection device and gear defect detection method

A gear defect detection method for use in a gear defect detection device, the gear defect detection method comprising:

• obtaining, by an acquisition circuit, a pulse signal from a sensor for detecting top and bottom portions of a gear, the pulse signal including first signal sections and second signal sections alternating one after another, the first signal sections each representing a bottom portion of the gear, the second signal sections each representing a top portion of the gear;
• and
• determining, by a calculation circuitry, using the pulse signal, presence or absence of a defect of the gear on a basis of a ratio between a length of a first time period of a corresponding one of the first signal sections and a length of a second time period of a corresponding one of the second signal sections, and further determining, by the calculation circuitry, the presence or absence of a defect of the gear using at least one of acceleration or jerk of an object that acts according to rotation of the gear in the corresponding one of the first signal sections and in the corresponding one of the second signal sections by comparison of the absolute value of the acceleration with the absolute value of the maximum acceleration or comparison of the absolute value of the jerk with the absolute value of the maximum jerk.