Solid state image pickup device capable of distinguishing between light sources and image pickup apparatus using such solid state image pickup device
View Patent ↗There are photographing scenes which are difficult, for a conventional image pickup apparatus having a solid state image pickup device with primary color filters, to correctly judge whether an illumination light source is the sun or a fluorescent lamp. The solid image pickup device of an image pickup apparatus uses two types of red or green pixels having different spectral sensitivities. The type of a light source can be judged by using signals from the two types of the pixels.
1. A solid state image pickup device for generating an image, comprising:
a semiconductor substrate;
a plurality of pixels disposed on a surface of said semiconductor substrate along rows and columns in a matrix shape, said plurality of pixels being disposed in an effective pixel area corresponding to a reproduced image area and an invalid pixel area defined in the surface of said semiconductor area, the invalid pixel area being defined around the effective pixel area, wherein each of said plurality of pixels comprises:
a photoelectric conversion element for accumulating electric charges; and
a color filter disposed above said photoelectric conversion element for transmitting at least one of red, green and blue light fluxes of incidence light to a corresponding one of said plurality of pixels, wherein a first of said plurality of pixels and a second of said plurality of pixels are both either red or green, and said first of said plurality of pixels and said second of said plurality of pixels have different spectral sensitivities; and
an output signal generator for generating an output signal in accordance with charges accumulated in said plurality of pixels, wherein each of said first of said plurality of pixels and said second of said plurality of pixels are included in said image, and
wherein only said first of said plurality of pixels is disposed in the effective pixel area and said second of said plurality of pixels is disposed in the invalid pixel area.
2. A solid state image pickup device for generating an image, comprising:
a semiconductor substrate;
a plurality of pixels disposed in a pixel shift layout on a surface of said semiconductor substrate along rows and columns in a matrix shape, wherein each of said plurality of pixels comprises:
a photoelectric conversion element for accumulating electric charges; and
a color filter disposed above said photoelectric conversion element for transmitting at least one of red, green and blue light fluxes of incidence light to a corresponding one of said plurality of pixels, wherein a first of said plurality of pixels and a second of said plurality of pixels are both either red or green and said first of said plurality of pixels and said second of said plurality of pixels have different spectral sensitivities; and
an output signal generator for generating an output signal in accordance with charges accumulated in said plurality of pixels, wherein each of said first of said plurality of pixels and said second of said plurality of pixels are included in said image,
wherein said plurality of pixels include rows having only green pixels and rows including red and blue pixels and
wherein two different types of red pixels are alternately disposed in row and column directions.
3. An image pickup apparatus for generating an image, comprising:
at least one solid state image pickup device configured to convert an optical image of an object into an electric signal and to output the electric signal, said at least one solid state image pickup device having a plurality of pixels, wherein a first of said plurality of pixels is a particular color selected from a plurality of colors, and a second of said plurality of pixels is said particular color, wherein said first of said plurality of pixels and said second of said plurality of pixels have different spectral sensitivities;
an image pickup optical system for focusing an object image on said at least one solid state image pickup device;
a digital signal generator for converting an output signal from said at least one solid state image pickup device into a digital signal and outputting the digital signal;
a video signal generator for generating red, green and blue signals from the digital signal output from said digital signal generator and generating a pixel signal for image reproduction by using the red, green and blue signals; and
an auto white balance circuit for receiving the red, green and blue signals, detecting a color temperature of a light source, judging a type of the light source based at least on a difference between intensities of light incident upon each of said first of said plurality of pixels and said second of said plurality of pixels, and adjusting levels of the red, green and blue signals in said video signal generator in accordance with a detection result of the color temperature and a judgment result of the type of the light source, wherein each of said first of said plurality of pixels and said second of said plurality of pixels are included in said image,
wherein the type of the light source is judged by using one of formulae (I) to (IV):
(S R1 −k 4 S R2 )/(k 1 S R1 +k 2 S R2 +k 3 S G ) (I)
(S R1 −k 11 S R2 )/(k 10 S G ) (II)
(S R1 −k 22 S R2 )/(k 20 S R1 +k 21 S R2 ) (III)
(S R1 −k 34 S R2 −k 35 S G −k 36 S B )/(k 31 S R1 +k 32 S R2 +k 33 S G ) (IV)
where S R1 : an average output of signals generated from charges read from red pixels PR 1 ; S R2 : an average output of signals generated from charges read from red pixels PR 2 ; S G : an average output of signals generated from charges read from green pixels PG; S B : an average output of signals generated from charges read from blue pixels PB; k 1 , k 2 , k 3 , k 4 , k 10 , k 11 , k 20 , k 21 , k 22 , k 31 , k 32 , k 33 k 34 , k 35 , K 36 : coefficients.