Patent ID: 8432583

Claim:
An image forming apparatus comprising an image scanning device that includes: an image-data acquiring unit that scans an image of an original placed on an exposure glass and acquires image data of the image; an image processing unit that performs a predetermined image processing on the image data; a signal generating unit that generates a scanning signal for determining a section of the image data for performing the image processing; a signal control unit that stores in advance therein waveform information of a scanning signal in a normal operation as a control signal, compares the control signal with the scanning signal generated by the signal generating unit, and detects an abnormality of the scanning signal based on a result of comparison; a scan control unit that determines whether the image processing is to be continued based on a result of detection by the signal control unit, a carriage that houses a scanning unit that scans the image of the original; and a driving motor for driving the carriage along the exposure glass during an optical scanning, wherein in a platen scanning mode in which the original is manually placed on the exposure glass to scan the image of the original, the signal control unit compares the control signal with the scanning signal that is generated by the signal generating unit during an operation period of the driving motor, and waveforms of the scanning signal and the control signal match during a normal operation of the image forming apparatus.