Picture image information read-out method and apparatus

DETAILED DESCRIPTION An object of this invention is to eliminate defects or problems encountered to the prior art technique and to provide a method for reading out image information and a solid state image pick-up device for realizing the method without degrading the quality of the image data even if the image information is read out at low speed.
Another object of this invention is to provide a method and apparatus for reading out image information in which photoelectric conversion, transference, and storage steps are carried out with high speed processing and a read-out process is carried out with low speed processing, thereby to eliminate the use of a sampled-and-hold circuit and an expensive A/D converter.
According to this invention, in one aspect, there is provided a method for reading out image information in which the image information is synchronized with a clock signal which is then photoelectrically converted, transferred stored and read out as an image signal and in the improvement of the method, the image information read with a first frequency of the clock signal is read out with a second frequency of the clock signal which is low rate compared with the first frequency.
In another aspect of this invention, there is provided an apparatus for reading out image information comprising a circuit for generating a clock signal regarding image information, a circuit in which the clock signal from the clock signal generating circuit is processed so as to have first and second frequencies and which generates a clock signal in a switched manner to generate a clock signal having the first frequency or second frequency, a unit for photoelectrically converting the image signal in synchronism with the clock signal from the clock signal switching circuit, a unit for storing the image information with the first frequency transferred from the photoelectrically converting unit, and a unit for reading out a stored image information with the second frequency which is low rate compared with the first frequency