Distance measurement apparatus for camera, and distance measurement method

A distance measurement apparatus for a camera, comprising:

• distance measurement means for time-serially performing a plurality of number of times of distance measurement operations;
• discrimination means for discriminating on the basis of time-serial outputs from said distance measurement means whether or not a moving amount of an object in a photographing optical axis direction is not less than a predetermined amount;
• and
• correction means for, when said discrimination means discriminates that the moving amount of the object is not less than the predetermined amount, adding a predetermined correction amount to the outputs from said distance measurement means.

A lens driving amount determination method for an auto-focus camera, comprising the steps of:

• performing a first distance measurement operation;
• waiting for a predetermined period of time;
• performing a second distance measurement operation;
• determining a driving amount of a photographing lens using at least one of two distance measurement signals obtained by the first and second distance measurement operations;
• and
• correcting the driving amount when a difference between the two distance measurement signals is not less than a predetermined value.

An auto-focus method for a camera, comprising the steps of:

• performing a first distance measurement operation according to a half-stroke operation of a shutter release button;
• driving a photographing lens on the basis of a first distance measurement result;
• performing a second distance measurement operation after said photographing lens is driven;
• discriminating on the basis of the first and second distance measurement results whether or not a moving amount of an object in a photographing optical axis direction is not less than a predetermined amount;
• and
• additionally driving said photographing lens when the discrimination results indicates that the moving amount is not less than the predetermined amount.

An auto-focus apparatus for a camera, comprising:

• light projection means for time-serially performing a plurality of number of times of light projection operations to an object;
• distance measurement means for time-serially receiving the light projected from said light projection means and reflected by the object to detect an amount of received light so as to measure a distance to the object, and integrating the amount of received light to discriminate a moving amount of the object;
• photographing lens driving means for driving a photographing lens on the basis of an output from said distance measurement means;
• and
• driving amount correction means for, when said distance measurement means discriminates that the object is moved by an amount not less than a predetermined amount, adding a predetermined correction amount to a driving amount of said photographing lens based on the output from said distance measurement means.

An auto-focus method for a camera which comprises distance measurement means for projecting infrared light toward an object, receiving the infrared light reflected by the object, and outputting a signal according to an object distance, comprising the steps of:

• outputting a first distance measurement signal;
• extending a photographing lens from an initial position on the basis of the first distance measurement signal;
• outputting a second distance measurement signal;
• obtaining a moving amount and a moving direction of the object on the basis of the first and second distance measurement signals;
• and
• extending or collapsing said photographing lens by a predetermined amount according to the moving direction only when the moving amount is not less than a predetermined value.

An auto-focus apparatus for a camera, comprising:

• distance measurement means for outputting a signal according to an object distance;
• movement detection means for outputting a signal according to object movement;
• arithmetic means for converting the output signal from said distance measurement means into an extension amount of a photographing lens, said arithmetic means including means for, when said movement detection means detects object movement of not less than a predetermined amount, adding a predetermined correction amount to the extension amount;
• and
• driving means for driving said photographing lens from an initial position on the basis of an output from said arithmetic means.

A distance measurement apparatus for a camera in which an optical axis of a photographing lens is separated from an optical axis of distance measurement means, comprising:

• object moving amount discrimination means for discriminating on the basis of an output from said distance measurement means whether or not a moving amount of an object in a photographing optical axis direction is not less than a predetermined amount;
• photographing lens driving means for driving said photographing lens on the basis of the output from said distance measurement means;
• and
• driving amount correction means for, when said object moving amount discrimination means discriminates movement of an object of not less than the predetermined amount, adding a predetermined correction amount to a driving amount of said photographing lens on the basis of the output from said distance measurement means.

An auto-focus apparatus for a camera in which an optical axis of a photographing lens is separated from an optical axis of distance measurement means, comprising:

• discrimination means for discriminating on the basis of an output from said distance measurement means whether or not a moving amount of an object in a photographing optical axis direction is not less than a predetermined amount;
• correction means for, when said discrimination means discriminates movement of the object of not less than the predetermined amount, adding a predetermined correction amount to the output from said distance measurement means;
• and
• driving means for driving said photographing lens on the basis of the output from said distance measurement means or an output added with the correction amount.

A lens driving amount determination apparatus for an auto-focus camera, comprising:

• distance measurement means for outputting a signal according to an object distance;
• detection means for detecting whether or not an object is moving;
• and
• arithmetic means for converting the output signal from said distance measurement means into a lens driving amount, said arithmetic means including means for, when said detection means detects movement of the object, adding a predetermined correction value to the lens driving amount.

An auto-focus apparatus for measuring an object distance, and adjusting a focal point position of a photographing lens according to the object distance value, comprising:

• distance measurement means for performing a plurality of number of times of distance measurement operations at different timings;
• discrimination means for discriminating on the basis of a plurality of distance measurement signals obtained by the plurality of number of times of distance measurement operations whether or not an object is moving;
• and
• correction means for, when said discrimination means discriminates movement of the object, correcting the adjusted focal point position of said photographing lens by a predetermined amount.