Imaging apparatus and signal processing method

1. An imaging apparatus comprising:

a solid-state imaging device including a plurality of photoelectric conversion units having plural first photoelectric conversion units and plural second photoelectric conversion units that are regularly arranged on a semiconductor substrate;

a drive section that controls the solid-state imaging device

to read first pixel signals that are accumulated over an exposure period, from the first photoelectric conversion units, respectively,

to read low-sensitivity pixel signals from the second photoelectric conversion units, respectively,

to read second pixel signals that are accumulated in at least a part of the exposure period, from the second photoelectric conversion units, and

to mix the first pixel signals and the second signals and produce high-sensitivity pixel signals; and

a signal processing section that combines the low-sensitivity pixel signals and the high-sensitivity pixel signals and produces an image.

2. The imaging apparatus of claim 1 , wherein the first photoelectric conversion unit and the second photoelectric conversion unit, which correspond to an identical color and are to be mixed, are disposed at positions adjacent to each other on the semiconductor substrate.

3. The imaging apparatus of claim 1 , wherein

the photoelectric conversion units are disposed on a surface of the semiconductor substrate in row and column directions, and

the first photoelectric conversion units and the second photoelectric conversion units are arranged at an identical arrangement pitch at positions shifted from each other in the row and column directions by one half of the arrangement pitch.

4. The imaging apparatus of claim 3 , further comprising:

a vertical transfer section that transfers signal charges that are read from the photoelectric conversion units, in the column direction; and

a horizontal transfer section that transfers the signal charges, which are transferred from the vertical transfer section, in the row direction, wherein

the vertical transfer section includes

a plurality of vertical transfer channels that are formed on the semiconductor substrate so as to correspond to the photoelectric conversion units being disposed in the column direction,

a plurality of vertical transfer electrodes each of which is formed so as to intersect the plurality of vertical transfer channels, and

charge reading areas that read the signal charges of the photoelectric conversion units into the vertical transfer channels, and

the first pixel signals and the second signals are mixed in the horizontal transfer section.

5. The imaging apparatus of claim 1 , wherein

the photoelectric conversion units are disposed on a surface of the semiconductor substrate in row and column directions, and

the first photoelectric conversion units and the second photoelectric conversion units are arranged at an identical arrangement pitch in an arrangement obtained by slanting a square lattice configuration having a 2×2 period.

6. The imaging apparatus of claim 5 , further comprising:

a vertical transfer section that transfers signal charges that are read from the photoelectric conversion units, in the column direction; and

a horizontal transfer section that transfers the signal charges, which are transferred from the vertical transfer section, in the row direction, wherein

the vertical transfer section includes

a plurality of vertical transfer channels that are formed on the semiconductor substrate so as to correspond to the photoelectric conversion units being disposed in the column direction,

a plurality of vertical transfer electrodes each of which is formed so as to intersect the plurality of vertical transfer channels, and

charge reading areas that read the signal charges of the photoelectric conversion units into the vertical transfer channels, and

the first pixel signals and the second signals are mixed in the vertical transfer section or the horizontal transfer section.

7. A signal processing method for an imaging apparatus including a solid-state imaging device, wherein the solid-state imaging device includes a plurality of photoelectric conversion units having plural first photoelectric conversion units and plural second photoelectric conversion units that are regularly arranged on a semiconductor substrate, the method comprising:

reading first pixel signals that are accumulated over an exposure period, from the first photoelectric conversion units, respectively;

reading low-sensitivity pixel signals from the second photoelectric conversion units, respectively;

reading second pixel signals that are accumulated in at least a part of the exposure period, from the second photoelectric conversion units;

mixing the first pixel signals and the second pixel signals to produce a high-sensitivity pixel signal;

mixing the low-sensitivity pixel signals and the high-sensitivity pixel signals to produces an image.

8. The method of claim 7 , wherein, the first photoelectric conversion unit and the second photoelectric conversion unit, which correspond to identical color and are to be mixed, are disposed at positions adjacent to each other on the semiconductor substrate.

9. The method of claim 7 , wherein

the photoelectric conversion units are disposed on a surface of the semiconductor substrate in row and column directions, and

the first photoelectric conversion units and the second photoelectric conversion units are arranged at an identical arrangement pitch at positions shifted from each other in the row and column directions by one half of the arrangement pitch.

10. The method of claim 9 , further comprising:

transferring signal charges read from the photoelectric conversion units in the column direction, by a vertical transfer section; and

transferring the signal charges, which are transferred from the vertical transfer section, in the row direction by a horizontal transfer unit, wherein

the vertical transfer section includes

a plurality of vertical transfer channels that are formed on the semiconductor substrate so as to correspond to the photoelectric conversion units being disposed in the column direction,

a plurality of vertical transfer electrodes each of which is formed so as to intersect the plurality of vertical transfer channels, and

charge reading areas that read the signal charges of the photoelectric conversion units into the vertical transfer channels, and

the first pixel signals and the second signals are mixed in the horizontal transfer section.

11. The method of claim 7 , wherein

the photoelectric conversion units are disposed on a surface of the semiconductor substrate in row and column directions, and

the first photoelectric conversion units and the second photoelectric conversion units are arranged at an identical arrangement pitch in an arrangement obtained by slanting a square lattice configuration having a 2×2 period.

12. The method of claim 11 , further comprising:

transferring signal charges read from the photoelectric conversion units in the column direction, by a vertical transfer section; and

transferring the signal charges from the vertical transfer section in the row direction, by a horizontal transfer section, wherein

the vertical transfer section includes

a plurality of vertical transfer channels that are formed on the semiconductor substrate so as to correspond to the photoelectric conversion units being disposed in the column direction,

a plurality of vertical transfer electrodes each of which is formed so as to intersect the plurality of vertical transfer channels, and

charge reading areas that read the signal charges of the photoelectric conversion units into the vertical transfer channels, and

the first pixel signals and the second signals are mixed in the vertical transfer section or the horizontal transfer section.