US Patent 7336402 Image reading apparatus

Since a power supply circuit for a controller (31) and a power supply circuit for a buffer storage unit (32) are independently provided, the power voltage for the buffer storage unit (32) need only be reduced to obtain a corresponding reduction in the amplitude of the signal waveform of digital image data transmitted along an FFC (40), without the operation of the controller (31) being adversely affected. In addition, so long as a coil (47) is located at one position in the internal power supply circuit of a control chip (24), or the external circuit thereof near its power supply circuit, the signal waveform for the digital image data transmitted along the FFC (40) can be attenuated.