초록 ▼

A focusing mechanism for a camera includes a drive arrangement for displacing the camera lens in accordance with the contents of a counter into which the output of a pulse generator is gated during a range pulse whose duration is directly related to the distance of a subject from the camera. The pul

A focusing mechanism for a camera includes a drive arrangement for displacing the camera lens in accordance with the contents of a counter into which the output of a pulse generator is gated during a range pulse whose duration is directly related to the distance of a subject from the camera. The pulse generator is programmed so that its pulse repetition rate matches the time-derivative of the function relating the subject distance to the lens position at which a subject is in focus. Integration of the generator output is carried out by gating the generator pulses into a counter during the range pulse such that at the trailing edge of the range pulse, the contents of the counter will be the integral of the time-derivative evaluated between the limits of the range pulse, i.e., a definite integral representative of the lens position at which a subject will be in focus when located at a distance defined by the duration of the range pulse. For fully automated operation as applied to a still camera, shutter actuation can be in response to arrival of the lens to the position at which the subject is in focus. Applied to movie cameras, the lens can track a moving subject maintaning it in focus during filming.

대표청구항 ▼

In a camera having variable means for focusing image forming rays from a subject on the camera focal plane, the specific variation of said focusing means at which a subject is in focus being a predetermined nonlinear function of subject distance, and having range finding means for generating a range

In a camera having variable means for focusing image forming rays from a subject on the camera focal plane, the specific variation of said focusing means at which a subject is in focus being a predetermined nonlinear function of subject distance, and having range finding means for generating a range parameter representative of subject distance, said range parameter being a timed duration thereby establishing a relationship between subject distance and time, the improvement comprising: means responsive to said range parameter for generating a train of pulses whose number is representative of the specific variation of said focusing means at which said subject will be in focus, said pulse generating means including a counter for accumulating said pulses of said pulse train and a pulse generator with a preprogrammed time-variable pulse repetition rate, said preprogrammed repetition rate of said pulse generator being such that the contents of said counter, at the end of said range pulse, is representative of the specific variation of said focusing means at which said subject will be in focus; and means for varying said focusing means in accordance with the total number of pulses in said train of pulses, said focus ranging means including means responsive to said end of said timed duration for varying said focusing means in accordance with the contents of said counter.