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Camera system capable of focus detection through an interchangeable objective lens

  • US 4,509,842 A
  • Filed: 01/31/1984
  • Issued: 04/09/1985
  • Est. Priority Date: 02/01/1983
  • Status: Expired due to Term
First Claim
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1. In a camera system capable of focus detection by means of receiving light through an interchangeable objective lens, a camera body and an interchangeable objective lens selectively attachable to the camera body comprising:

  • an opening, located in the camera body for detachably connecting with the interchangeable objective lens;

    means, located in the camera body, for receiving light through the opening to produce electric signals;

    means, located in the camera body, for processing the electric signals to generate a defocusing information indicative of defocusing degree and defocusing direction relative to an ideal focal plane;

    means, located in the camera body, for generating a driving power for automatic focus control, including a first movable member;

    means, located in the camera body, for accepting digital data to be transmitted from the interchangeable objective lens, the digital data including a converting information necessary to convert the defocusing degree of the defocusing information into a degree of movement of the first movable member;

    means, located in the camera body, for calculating the degree of movement of the first movable member in response to the defocusing degree of the defocusing information and the converting information;

    means, located in the camera body, for controlling the generating means to move the first movable member in response to the defocusing direction of the defocusing information and the calculated degree of movement;

    means, located in the camera body, for transmitting the driving power of the generating means to the interchangeable objective lens, the transmitting means including a second movable member connectable with the interchangeable objective lens and responsive to the movement of the first movable member;

    an optical system, located in the interchangeable objective lens, for forming an image of an object;

    means, located in the interchangeable objective lens, for adjusting the focus of the optical system, the adjusting means including a third movable member connectable with the second movable member for a coupled movement therewith;

    a read only memory, located in the objective lens, for storing various digital data at a plurality of addresses, the stored digital data including the converting information;

    means, located in the interchangeable objective lens, for selectively designating one of the addresses of the read only memory; and

    means for sending digital data stored in the designated address to the accepting means,wherein the converting information is formed as a digital data composed of n-bit of significant digits part and n-bit of floating point coefficient part.

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