White balance adjusting apparatus having a plurality of standard color references automatically selected by the detected color temperature

Claim 1

A white balance adjusting apparatus comprising: a plurality of sensors having mutually different spectral characteristics for producing color temperature detection signals dependent on a color temperature of an environment; color temperature detecting means comprising an illuminance discriminating circuit for discriminating from an output color temperature signal of at least one of said plurality of sensors whether or not an illuminance of said environment is within a predetermined range appropriate for a white balance adjustment and for producing an illuminance discrimination signal, a color temperature discriminating circuit for producing a predetermined color temperature detection signal from the output color temperature detection signals of said plurality of sensors, for producing a color temperature discrimination signal by discriminating which one of a plurality of color temperature regions the color temperature of said environment falls in and for outputting responsive to said illuminance discrimination signal and color temperature discrimination signal produced at a time immediately before the illuminance of said environment falls outside said predetermined range, a standard color temperature setting circuit for setting and outputting one of a plurality of standard color temperature signals for each of said plurality of color temperature regions, said one of a plurality of standard color temperature signals having a level dependent on the output color temperature discrimination signal of said color temperature discriminating circuit, and a switching circuit responsive to said illuminance discrimination signal for selectively passing said predetermined color temperature detection signal when the illuminance of said environment is within said predetermined range and for selectively passing the output standard color temperature signal of said standard color temperature setting circuit when the illuminance of said environment falls outside said predetermined range, an output signal of said switching circuit being outputted as an output signal of said color temperature detecting means; white balance correction control means responsive to the output signal of said color temperature detecting means for producing first and second control signals; an image pickup device for picking up an image of an object and for producing a video signal comprising a luminance signal in a baseband and modulated waves obtained by modulating carriers by color difference signals; separating means for separating the output video signal of said image pickup device into a luminance signal and a line-sequential primary color signal; variable gain amplifier means for amplifying said line-sequential primary color signal with first and second gains respectively controlled responsive to said first and second control signals so as to produce first and second line-sequential primary color signals; and video signal processing means for producing a standard system color video signal from said first and second line-sequential primary color signals and said luminance signal from said separating means, said first control signal variably controlling the first and second gains of said variable gain amplifier means so that a level of a first primary color signal within said first line-sequential primary color signal and a level of a second primary color signal are approximately equal to a level of a low frequency component of the luminance signal when said image pickup device picks up an image of a white object.