Solid state image sensing device having logarithmic signal output when image sensor is saturated

A solid-state image sensing apparatus comprising:

• a pixel unit having a photoelectric conversion part, a charge voltage conversion part for generating a voltage of a size which corresponds to an amount of electric charge, a transfer part for connecting said photoelectric conversion part to said charge voltage conversion part, a reset part for connecting said charge voltage conversion part to a predetermined electric potential, and a buffer part for outputting a voltage of said charge voltage conversion part;
• a pixel driving unit for supplying a transfer pulse to a gate of said transfer part and supplying a reset pulse to a gate of said reset part;
• and
• a signal processing unit for processing an output voltage of said buffer part before said reset pulse is supplied to said reset gate, as a first light detection voltage by said photoelectric conversion device, and processing an output voltage of said buffer part after said transfer pulse is supplied to said transfer gate as a second light detection voltage by said photoelectric conversion device;
• wherein when an amount of incident light is relatively large, electric charges overflow the reset gate and flow into an electric source and an output is sampled providing a signal which corresponds to a logarithm of the amount of incident light, and further wherein when the photoelectric conversion device is not saturated an output whose signal level varies in proportion to the amount of incident light is selectively provided and when the photoelectric conversion device is saturated, an output is selectively provided corresponding to the logarithmic relationship to the amount of incident light.