Electronic still camera provided with an electrical viewing system

Claim 1

An electrical still camera comprising: (a) optical means for forming an object image; (b) means for detecting the illumination of the object image and producing a brightness signal; (c) image pick-up means for producing picture signals each of which corresponds with the object image formed by said optical means, said image pick-up means including a solid state image pick-up device having a plurality of photoelectric conversion elements, producing means, transfer means and drain means, said plurality of photoelectric conversion elements comprising first and second groups, each of said plurality of photoelectric conversion elements storing charges corresponding to the intensity of incident light respectively impinging thereon, said transfer means transferring said stored charges of said plurality of photoelectric conversion elements to said producing means, said producing means producing said picture signals in response to said stored charges transferred by said transfer means, said drain means draining said stored charges to an outside of said solid state image pick-up device so that said stored charges are drained by said drain means irrespective of said picture signals; (d) calculating means responsive to said brightness signal for calculating a stored time during which said plurality of photoelectric conversion elements store charges; (e) driving means for controlling said transfer means and said drain means so that said producing means produces said picture signal conforming to said first group and said picture signal conforming to said second group at different times, said driving means having a first state, a second state and a third state and repeatedly performing an operation conforming to each of said three states; (f) viewfinder means for visualizing each of said picture signals; and (g) selecting means responsive to said stored time calculated by said calculating means for selecting one of said states, wherein in said first state said driving means drives said transfer means and said drain means repeatedly in a cycle corresponding to said calculated stored time so that said drain means drains said stored charges to the outside of said solid state image pick-up device in response to completion of a transferring operation of said transfer means, in said second state said driving means drives said transfer means repeatedly in a cycle corresponding to a predetermined period of time and stops said drain means continuously, and in said third state said driving means drives said transfer means and said drain means repeatedly in a cycle corresponding to said predetermined period of time so that said drain means drains said stored changes to the outside of said solid state image pick-up device for a period of time, which corresponds to a difference between said predetermined period of time and said calculated stored time, in response to the completion of the transferring operation of said transfer means.