CMOS image sensor having block scanning capability
A CMOS image sensor includes a plurality of pixel sensors arranged in a two-dimensional array. In each pixel sensor, a signal corresponding to the absolute value of the amount of incident light with reduced reset noise is obtained. The signals of the respective pixel sensors are then output in a block scanning fashion. The CMOS image sensor does not need to include a preprocessing circuit for discrete cosine transform or a high-capacity frame memory for raster scanning.
1. A CMOS image sensor, comprising:
pixel sensors arranged in the form of a two-dimensional array, each pixel sensor comprising a photodiode at a signal detection node and a pair of pass transistors, which passes a photodiode reset signal to a gate of a transistor that resets said photodiode, only when said pixel sensor is selected;
means, disposed in each pixel sensor, for obtaining a signal whose reset noise is reduced and that corresponds to the absolute value of the amount of incident light; and
means for outputting said signal in a block-scanning fashion
wherein said photodiode reset signal is given as the logical AND of a column block selection signal and a pixel reset signal.
2. A CMOS image sensor, comprising:
pixel sensors arranged in a two-dimensional array, each pixel sensor comprising floating diffusion at a signal detection mode and a pair of pass transistors, which passes a transfer signal to a gate of a transistor that transfers a signal charge of a photodiode, only when said pixel sensor is selected;
means, disposed in each pixel sensor, for obtaining a signal whose rest noise is reduces and that corresponds to the absolute value of the amount of incident light; and
means for outputting said signal in a block-scanning fashion;
wherein said transfer signal is given as the logical AND of a column block selection signal and a pixel transfer signal.
3. A CMOS image sensor comprising:
a pixel sensor according to claim 1 ; and
means for selectively connecting the output of the pixel sensor to a circuit for reading one row of block.
4. A CMOS image sensor comprising:
a pixel sensor according to claim 2 ; and
means for selectively connecting the output of the pixel sensor to a circuit for reading one row of block.
5. A camera that automatically controls brightness, comprising:
a CMOS image sensor according to claim 1 ;
means for estimating the average brightness over an entire screen of said CMOS image sensor from brightness detected for a several blocks in a central area and in a peripheral area of the screen; and
a programmable gain amplifier having a gain that is automatically controlled in accordance with the estimated brightness.
6. A camera that automatically controls brightness, comprising:
a CMOS image sensor according to claim 2 ;
means for estimating the average brightness over an entire screen of said CMOS image sensor from brightness detected for a several blocks in a central area and in a peripheral area of the screen; and
a programmable gain amplifier having a gain that is automatically controlled in accordance with the estimated brightness.
7. A camera that automatically controls brightness, comprising:
a CMOS image sensor according to claim 3 ;
means for estimating the average brightness over an entire screen of said CMOS image sensor from brightness detected for a several blocks in a central area and in a peripheral area of the screen; and
a programmable gain amplifier having a gain that is automatically controlled in accordance with the estimated brightness.
8. A monitor camera, comprising:
a CMOS image sensor according to claim 1 ;
means for detecting whether there is a substantial change in an image by reading several blocks in a central area and in a peripheral area of an image screen of said CMOS image sensor; and
means for continuously taking an image over the entire screen when a substantial change is detected.
9. A monitor camera, comprising:
a CMOS image sensor according to claim 2 ;
means for detecting whether there is a substantial change in an image by reading several blocks in a central area and in a peripheral area of an image screen of said CMOS image sensor; and
means for continuously taking an image over the entire screen when a substantial change is detected.
10. An autofocus camera, comprising:
a CMOS image sensor according to claim 1 ;
means for adjusting focus by reading several blocks in a central area of an image screen of said CMOS image sensor; and
means for taking an image over the entire screen after completion of the focus adjustment.
11. An autofocus camera, comprising:
a CMOS image sensor according to claim 2 ;
means for adjusting focus by reading several blocks in a central area of an image screen of said CMOS image sensor; and
means for taking an image over the entire screen after completion of the focus adjustment.
12. An autofocus camera, comprising:
a CMOS image sensor according to claim 3 ;
means for adjusting focus by reading several blocks in a central area of an image screen of said CMOS image sensor; and
means for taking an image over the entire screen after completion of the focus adjustment.