Solid-state imaging device and camera
A solid-state imaging device includes a plurality of pixels arranged two-dimensionally. Each pixel includes a photoelectric converter ( 2 ) for converting incident light to a charge, and a gray filter ( 6 a, 6 b, 6 c ) having a visible light transmittance that is different depending on the photoelectric converter ( 2 ). According to this construction, the plurality of pixels have different sensitivities to incident light. By combining pixel signals obtained from three pixels having different sensitivities, a wider dynamic range can be achieved.
1 . A solid-state imaging device comprising:
a plurality of photoelectric converters each operable to generate and accumulate an amount of charge corresponding to an amount of received light;
a suppression unit operable to suppress the amount of received light of each of the plurality of photoelectric converters at a rate determined for the photoelectric converter; and
an obtaining unit operable to, for each group of a predetermined number of photoelectric converters, combine electric signals that are respectively based on amounts of charge accumulated in the predetermined number of photoelectric converters, thereby obtaining one composite signal for the predetermined number of photoelectric converters,
wherein a maximum amount of charge that is able to be accumulated is substantially same in each of the predetermined number of photoelectric converters, and the rate of suppression by the suppression unit is different in each of the predetermined number of photoelectric converters.
2 . The solid-state imaging device of claim 1 ,
wherein the plurality of photoelectric converters are each provided on a substrate,
the suppression unit is an optical filter film that covers the substrate and transmits visible light, and
the rate of suppression by the suppression unit is different because a transmittance of visible light is different in each of areas of the optical filter film that correspond to the predetermined number of photoelectric converters.
3 . The solid-state imaging device of claim 1 ,
wherein the plurality of photoelectric converters are each provided on a substrate,
the suppression unit is a photo-shielding film that covers the substrate and has apertures at positions corresponding to the plurality of photoelectric converters, and
the rate of suppression by the suppression unit is different because a size of an aperture corresponding to each of the predetermined number of photoelectric converters is different.
4 . The solid-state imaging device of claim 1 ,
wherein the suppression unit includes:
a discharge unit operable to discharge a charge accumulated in each of the plurality of photoelectric converters; and
an accumulation unit operable to accumulate a charge in each of the plurality of photoelectric converters until a predetermined time period has elapsed since the discharge by the discharge unit, and
the rate of suppression by the suppression unit is different because a length of the predetermined time period is different for each of the predetermined number of photoelectric converters.
5 . The solid-state imaging device of claim 1 , further comprising:
a prohibition unit operable to, when an electric signal that is based on an amount of charge accumulated in any of the predetermined number of photoelectric converters indicates the maximum amount of charge, prohibit the obtaining unit from combining the electric signal.
6 . The solid-state imaging device of claim 1 ,
wherein the plurality of photoelectric converters are formed by introducing a dopant to a semiconductor substrate, and
the maximum amount of charge is substantially same because each of the predetermined number of photoelectric converters has a substantially same capacity and a substantially same dopant concentration.
7 . The solid-state imaging device of claim 1 ,
wherein the predetermined number is at least three.