Automatic focus detection system

An automatic focus detection system for detecting a focusing condition of an objective lens, comprising:

• an optical means;
• an image sensor means of an integration type which outputs an analog signal corresponding to an image of a target object to be photographed by the objective lens through the optical means;
• an integration time setting means for setting the integration time of said image sensor means;
• a clock signal generating means for generating a clock signal having a predetermined frequency;
• a signal outputting means for outputting the analog signal outputted by the image sensor means in synchronization with the clock signal;
• a first A/D converting means for converting the analog signal into a first digital signal of a first number of at least one bit;
• a second A/D converting means for converting the analog signal into a second digital signal of a second number of bits, the second number of bits being larger than the first number of bits;
• a selecting means for selecting either of the first digital signal and the second digital signal for being applied for the calculation of the defocus amount of the objective lens, and
• a control means for shortening the integration time set by the integration time setting means in the case where the first digital signal is selected, as compared with the integration time set in the case where the second digital signal is selected.

An automatic focus detection system for detecting a focusing condition of an objective lens, comprising:

• an optical means;
• an image sensor means of an integration type which outputs an analog signal corresponding to an image of a target object to be photographed by the objective lens through the optical means;
• a clock signal generating means for generating a clock signal having a predetermined frequency;
• a signal outputting means for outputting the analog signal outputted by the image sensor means in synchronization with the clock signal;
• a first A/D converting means for converting the analog signal into a first digital signal of a first number of at least one bit;
• a second A/D converting means for converting the analog signal into a second digital signal of a second number, the second number being larger than the first number;
• a selecting means for selecting either of the first digital signal and the secon digital signal for being applied for the calculation of the defocus amount of the objective lens, and
• a control means for raising the frequency of the clock signal generated by the clock signal generating means in the case where the first digital signal is selected, as compared with the frequency of the clock signal generated in the case where the second digital signal is selected.

An automatic focus detection system for detecting a focusing conditoin of an objective lens, comprising:

• an optical means;
• an image sensor means which outputs analog signals corresponding to an image of a target object through the optical means;
• an A/D converting means for converting the analog signals into digital signals;
• a first processing means for performing a first process with the digital signals of a first number of at least one bit;
• a second processing means for performing a second process with the digital signals of a second number of bits, the second number being larger than the first number, and
• a selecting means for selectively making either of the first processing means and the second processing means operable on the basis of a predetermined sequence of the focus detecting operation.

A processing device used in a camera, comprising:

• an image sensor means for outputting analog signals corresponding to an image of a target object;
• an A/D converting means for converting the analog signals into digital signals;
• a first procesing means for performing a first process with the digital signals of a first number of at least one bit;
• a second processing means for performing a second process with the ditial signals of a second number of bits, the second number being larger than the first number, and
• a selecting means for selectively making either of the first and second processing means operable on the basis of a predetermined sequence of the camera.