Patent ID: 6291810
Filing Date: 2001-09-18
Classification: H04N

Abstract:
An image sensor comprising: a plurality of linear image sensor ICs arranged linearly, each having a plurality of unit light receiving circuits, each unit light receiving circuit comprising a photodiode acting as a light receiving element; a first amplifier for amplifying a signal output by the photodiode; a reading switch for reading out therethrough an output signal of the first amplifier; and a first reset switch for returning the photodiode back to an initial state; wherein an electric potential at a first electrode of the photodiode is a fixed electric potential, a second electrode of the photodiode the electric potential of which varies depending on the amount of received light is connected to an input terminal of the first amplifier, an output terminal of the first amplifier is connected to an input terminal of the reading switch, an output terminal of the reading switch is connected to an output terminal of the reading switch of another unit light receiving circuit through a common signal line, a first electrode of the first reset switch is connected to a second electrode of the photodiode, and an electric potential at a second electrode of the first reset switch is fixed to a first electric potential that is an initial electric potential; and wherein each of the linear image sensor ICs further comprises a scanning circuit for scanning the reading switch and the reset switch of each of the unit light receiving circuits in such a way that the output signals, each varying depending on the amount of received light, from the plurality of unit light receiving circuits which are arranged linearly are read out successively in the order of arrangement of the unit light receiving circuits to a signal output terminal; a second amplifier for further amplifying the signal read out from the common signal line; and a chip selecting switch for selectively controlling the second amplifier.