Driving method for solid-state imaging device and solid-state imaging device

1. A driving method for a solid-state imaging device having pixels arranged in a matrix, said method comprising:

for each of the pixels,

holding a first signal charge in a first holding unit, the first signal charge being generated from incident light at a first sensitivity within a field period of a field which temporally precedes a predetermined field, of two different fields located at a temporally equal distance from the predetermined field, and the two different fields and the predetermined field being included in a frame;

holding a second signal charge in a second holding unit, the second signal charge being generated from incident light at a second sensitivity within a field period of the predetermined field; and

adding the first signal charge held in the first holding unit, the second signal charge held in the second holding unit, and a third signal charge which is generated from incident light at the first sensitivity within a field period of a field which temporally follows the predetermined field, of the two different fields,

wherein the adding comprises:

adding the first signal charge held in the first holding unit and the third signal charge; and

adding the second signal charge held in the second holding unit and a signal charge which is a result of the addition of the first signal charge and the third signal charge.

2. The driving method for the solid-state imaging device according to claim 1 ,

wherein the frame includes a temporal series of a first field, a second field and a third field,

the predetermined field is the second field,

the adding of the first and third signal charges adds the first signal charge generated from the incident light at the first sensitivity within the field period of the first field and the third signal charge generated from the incident light at the first sensitivity within the field period of the third field, and

the adding of the second signal charge and the signal charge which is a result of adding the first and third signal charges adds the second signal charge generated from the incident light at the second sensitivity within the field period of the second field and the signal charge which is the result of the addition of the first and third signal charges, so as to calculate a signal charge of the frame.

3. The driving method for the solid-state imaging device according to claim 1 ,

wherein the two different fields located at the temporally equal distance from the predetermined field are two fields located adjacent to both sides of the predetermined field.

4. The driving method for the solid-state imaging device according to claim 1 ,

wherein the first sensitivity is higher than the second sensitivity.

5. The driving method for the solid-state imaging device according to claim 1 ,

wherein the first sensitivity is lower than the second sensitivity.

6. The driving method for the solid-state imaging device according to claim 1 ,

wherein the second sensitivity is determined so that a signal charge increases linearly with an increase in an amount of the incident light, until a luminance which is equivalent to a maximum contrast resolving power of human eyes is generated from the incident light.

7. The driving method for the solid-state imaging device according to claim 1 ,

wherein the first sensitivity and the second sensitivity are determined by an electronic shutter of the solid-state imaging device.

8. A solid-state imaging device comprising:

a photoelectric converter that includes pixels arranged in a matrix;

for each of the pixels, a first holding unit operable to hold a first signal charge generated from incident light at a first sensitivity within a field period of a field which temporally precedes a predetermined field, of two different fields located at a temporally equal distance from the predetermined field, the two different fields and the predetermined field being included in a frame;

for each of the pixels, a second holding unit operable to hold a second signal charge generated from incident light at a second sensitivity within a field period of the predetermined field;

for each of the pixels, an adder operable to add the first signal charge held in said first holding unit, the second signal charge held in said second holding unit, and a third signal charge which is generated from incident light at the first sensitivity within a field period of a field which temporally follows the predetermined field, of the two different fields; and

a controller operable to control the first sensitivity and the second sensitivity,

wherein said adder includes:

for each of the pixels, a first adder that adds the first signal charge held in said first holding unit and the third signal charge; and

for each of the pixels, a second adder that adds the second signal charge held in said second holding unit and a signal charge which is a result of the addition performed by said first adder,

wherein said photoelectric converter includes:

photodiodes for conversion provided for the pixels to convert incident light into charge;

first charge transfer paths, each of which is provided for corresponding photodiodes of said photodiodes for conversion; and

first transfer gates, through each of which the charge generated by each of said photodiodes for conversion is transferred to a corresponding one of said first charge transfer paths,

said first holding unit includes:

the same number of photodiodes for accumulation as said photodiodes for conversion, which are arranged in a same form as said photodiodes for conversion;

second charge transfer paths, each of which is provided for corresponding photodiodes of said photodiodes for accumulation; and

second transfer gates, through each of which the charge accumulated in each of said photodiodes for conversion, of said photoelectric converter, is transferred to and is accumulated in each of said photodiodes for accumulation, and then the charge accumulated in each of the photodiodes for accumulation is read, and

said second charge transfer path functions as said first adder.

9. The solid-state imaging device according to claim 8 ,

wherein said second charge transfer path allows a transfer of charge twice as much as or more than charge which can be transferred through said first charge transfer path.

10. The solid-state imaging device according to claim 8 , further comprising

an electronic shutter,

wherein said controller is operable to determine the first sensitivity and the second sensitivity by controlling said electronic shutter.