Image forming apparatus and pulse generating method

An image forming apparatus for performing recording in order to form an image on a transported recording medium, the apparatus comprising:

• a transportation unit which transports the recording medium;
• a recording unit which performs recording in order to form the image on the recording medium transported by the transportation unit;
• an encoder which outputs an encoder signal including pulses according to a transportation position of the transportation unit;
• a measurement unit which measures a pulse period of the encoder signal;
• a storage unit which stores the measured pulse period;
• a detection unit which detects pulse omission of the encoder signal on the basis of the measured value of the measurement unit;
• and
• a pulse generation unit which generates a recording timing pulse on the basis of the pulse period stored in the storage unit when the pulse omission is not detected and generates the recording timing pulse on the basis of the pulse period stored in the storage unit and measured before the pulse omission when the pulse omission is detected,
• wherein the storage unit latches pulse period data on the basis of the detected result when the detection unit detects the pulse omission, the detection unit is set so as to detect the pulse omission when the pulse period measured by the measurement unit exceeds the threshold of a product of a newest pulse period, in which the pulse omission is not detected, and a set value, and the set value is set to a value less than the number of pieces of data to be latched in the storage unit.