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Automatic focusing device and the electronic image pickup apparatus using the same

  • US 6,972,797 B2
  • Filed: 10/17/2001
  • Issued: 12/06/2005
  • Est. Priority Date: 10/19/2000
  • Status: Expired due to Fees
First Claim
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1. An automatic focusing device comprising:

  • an image pickup lens including a moveable focusing lens, wherein the focusing lens moves to form an image of an object at an image plane;

    an image pickup means, wherein the image pickup means picks up the image of the object at the image plane and outputs an electrical signal corresponding to the image of the object;

    a TTL focus detecting means, wherein the TTL focus detects means detects a focusing state of the image pickup lens based on the electrical signal output from the image pickup means;

    an open-control range finding means, wherein the open-control range finding means measures the distance of the object between the automatic focusing device and the object;

    a focusing lens position detecting means, wherein the focusing lens position detecting means detects at least one of a focusing position and a shift length of the focusing lens;

    a driving and controlling means, wherein the driving and controlling means obtains a focusing position of the focusing lens based on a conversion reference for converting the distance of the object measured by the open-control range finding means to the focusing position of the focusing lens, whereby to move the focusing lens to the focusing position thereof;

    wherein the driving and controlling means moves the focusing lens based on the focusing state of the image pickup lens detected by the TTL focus detecting means when it is necessary to correct the conversion reference;

    wherein the driving and controlling means makes the focusing lens position detecting means detect the focusing position or the shift length of the focusing lens;

    wherein the driving and controlling means makes the open-control range finding means measure the distance of the object; and

    wherein the driving and controlling means corrects the conversion reference based on at least one of the detected focusing position and the detected shift length of the focusing lens, and the measured distance of the object.

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