Image sensing apparatus and its control method
A drive mode is switched after readout for one frame is completed, and the reset operation for the following frame is started. In this manner, the reset operation for the following frame will not be performed during the readout period for the preceding frame. Therefore, the accumulation period for the following frame can be made consistent in that frame.
1. An image sensing apparatus comprising:
an image sensing unit adapted to generate image data in which a plurality of lines are arranged, each line having a plurality of pixel circuits each including a light-receiving unit which generates and accumulates charges according to a quantity of incident light;
a reset unit adapted to execute a first reset mode and a second reset mode on a frame basis, wherein the reset unit sequentially resets the light-receiving units at first time intervals for every predetermined line in the first reset mode, and sequentially resets the light-receiving units at second time intervals different from the first time intervals for every predetermined line in the second reset mode; and
a readout unit adapted to execute a first readout mode and a second readout mode on a frame basis, wherein in the first readout mode, the readout unit reads out as pixel values the charges accumulated in the light-receiving units at the first time intervals for every said predetermined line after a predetermined time from start of the reset in the first reset mode, and in the second readout mode, the readout unit reads out as pixel values the charges accumulated in the light-receiving units at the second time intervals for every said predetermined line after a predetermined time from start of the reset in the second reset mode, and
wherein, when the readout unit performs readout by switching between two successive frames from readout at the first time intervals for every said predetermined line to readout at the second time intervals for every said predetermined line, or from readout at the second time intervals for every said predetermined line to readout at the first time intervals for every said predetermined line, the reset unit performs reset for the following frame after completion of readout of pixel values in the preceding frame, and
wherein when the switching is not performed between the two successive frames, the reset unit performs reset for the following frame before completion of readout of pixel values in the preceding frame.
2. The image sensing apparatus according to claim 1 , wherein,
the reset unit performs reset for a frame by the reset mode different from the reset mode of the preceding frame after completion of the readout of pixel values in the preceding frame by the readout unit.
3. The image sensing apparatus according to claim 2 , wherein, the readout unit controls the time of starting readout in the following frame so that the period from start of the reset to start of readout in the following frame becomes equal to the period from start of the reset to start of readout in frames subsequent to the following frame.
4. The image sensing apparatus according to claim 2 , further comprising a gain correction unit adapted to correct a gain of pixel values in the following frame to compensate difference of accumulation period of the two successive frames when the switching is performed between the two successive frames.
5. A method of controlling an image sensing apparatus comprising:
an image sensing unit adapted to generate image data in which a plurality of lines are arranged, each line having a plurality of pixel circuits each including a light-receiving unit which generates and accumulates charges according to a quantity of incident light; and a reset unit adapted to execute a first reset mode and a second reset mode on a frame basis, wherein the reset unit sequentially resets the light-receiving units at first time intervals for every predetermined line in the first reset mode, and sequentially resets the light-receiving units at second time intervals different from the first time intervals for every predetermined line in the second reset mode, the method comprising:
a readout step of executing a first readout mode and a second readout mode on a frame basis, wherein in the first readout mode, the charges accumulated in the light-receiving units are read out as pixel values at the first time intervals for every said predetermined line after a predetermined time from start of the reset in the first reset mode, and in the second readout mode, the charges accumulated in the light-receiving units are read out as pixel values at the second time intervals for every said predetermined line after a predetermined time from start of the reset in the second reset mode;
wherein, when readout is performed in the readout step by switching between two successive frames from readout at the first time intervals for every said predetermined line to readout at the second time intervals for every said predetermined line, or from readout at the second time intervals for every said predetermined line to readout at the first time intervals for every said predetermined line, reset for the following frame is performed in the reset step after completion of readout of pixel values in the preceding frame, and
wherein when the switching is not performed between the two successive frames, reset for the following frame is performed in the reset step before completion of readout of pixel values in the preceding frame.
6. The method of controlling an image sensing apparatus according to claim 5 ,
further comprising a reset step of the reset unit performing reset for a frame by the reset mode different from the reset mode of the preceding frame after completion of the readout of pixel values in the preceding frame in the readout step.
7. The method of controlling an image sensing apparatus according to claim 6 , wherein in the readout step, the time of starting readout in the following frame is controlled so that the period from start of the reset to start of readout in the following frame becomes equal to the period from start of the reset to start of readout in frames subsequent to the following frame.
8. The method of controlling an image sensing apparatus according to claim 6 , further comprising a gain correction step of correcting a gain of pixel values in the following frame to compensate difference of accumulation period of the two successive frames when the switching is performed between the two successive frames.