Automatic focus adjustment apparatus for performing position control between consecutive images

• US 5,101,277 A
• Filed: 03/15/1990
• Issued: 03/31/1992
• Est. Priority Date: 07/19/1988
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kanata, Yoshio
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Metjahic, Safet
• Application Number:
  US07/465,234
• Time in Patent Office: 747 Days
• Field of Search: 358/227, 358/225, 358/55, 358/213.31, 358/93, 358/213.26, 358/213.22, 350/521, 350/520, 350/518, 350/515, 350/507, 250/201.2, 250/201.3, 354/402
• US Class Current: 348/349
• CPC Class Codes: G02B 21/244 using image analysis techniques
• CPC Class Codes: G02B 7/36 using image sharpness techniques , e.g. image processing techniques for generating autofocus signals image data processing per se G06T; in cameras having a solid state image sensor H04N23/67
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method

Abstract

The present invention is an automatic focus adjustment apparatus in which an object to be inspected is picked up by a camera (5) through an optical system (4), a video signal which is opto-electrically converted is transferred to a frame memory (9), image processing of a signal read out from the frame memory (9) is carried out, a focus adjustment evaluation quantity is calculated, and position of said optical system is controlled in a direction that the focus adjustment evaluation quantity approaches the maximum, and the position control operation of the optical system is carried out during a blanking time which is between electric charge storage times of two consecutive images of the camera.

Claims

1. An automatic focusing adjustment apparatus comprising:

a camera using a solid-state image pickup device for picking up an object to be inspected and opto-electrically converting an image of said object to a video signal,

means for transferring said video signal from said camera to a memory through an A/D converter,

means for reading out the image information stored in said memory and outputting a read signal,

means for calculating a focus adjustment evaluation quantity by carrying out image processing of said read signal,

focus adjustment evaluation means for judging completion of focus when the focus adjustment evaluation quantity becomes a maximum and outputting a judging signal representative thereof,

means for calculating a movement quantity of a motor for driving the optical system on the basis of said judging signal from said focus adjustment evaluation means and outputting a motor movement signal representative thereof,

a drive circuit for driving said motor in a stepwise manner on the basis of said motor movement signal from the motor movement quantity calculation means, and

blanking time synchronization means, responsive to a clock signal from a clock generation circuit, for synchronizing said drive circuit to perform position control operation of said optical system during a blanking time between electric charge storage time of two consecutive images of said camera or during a part of a time of said electric charge storage times before or after said blanking time in a range which does not give influence to an accuracy of calculation of said focus adjustment evaluation quantity.

2. An automatic focus adjustment apparatus comprising:

means for picking up an image of an object to be inspected through an optical system;

a camera having a 2;

1 interlacing mode for opto-electronically converting said image into alternating odd number fields and even number fields and outputting a video signal representative of a first image of one of said odd or even number fields;

means for digitizing said signal;

means for transferring said digitized video signal to a memory;

means for carrying out image processing of said transferred digitized video signal read out from said memory to obtain a focus adjustment evaluation quantity, said transfer and image processing of said first image as represented by said video signal being completed during an electric charge storage time of a second image of said one of said odd or even number fields, said means for carrying out image processing using only digitized video signals representing said one of said odd or even number fields; and

means for performing position control of said optical system in a direction that said focus adjustment evaluation quantity approaches a maximum, said position control means performing said position control of said optical system based on said first image during a blanking time between electric charge storage times of said second image and a third image of said one of said odd or even number fields or during a start part of time of the electric charge storage time of said third image or an end part of time of the electric charge storage time of said second image within a range that does not influence accuracy of the focus adjustment evaluation quantity.

3. An automatic focus adjustment apparatus comprising:

means for picking up an image of an object to be inspected through an optical system;

a camera having a noninterlace mode for opto-electrically converting said image to a video signal representing a first image;

means for digitizing said signal;

means for transferring said digitized video signal to a memory, said transfer of said digitized video signal representing said first image being performed during an electric charge storage time of a second consecutive image in said camera;

means for carrying out image processing of said transferred digitized video signal read out from said frame to obtain a focus adjustment evaluation quantity, said means for carrying out performing said image processing of said first image as represented by said video signal during said electric charge storage time of a third image consecutive to said second image; and

means for performing position control of said optical system in a direction that said focus adjustment evaluation quantity approaches a maximum, said position control means performing said position control of said optical system based on said first image during a blanking time between electric charge storage times of said third image and a fourth image consecutive to said third image or during a start part of time of the electric charge storage time of said fourth image or an end part of time of the electric charge storage time of said third image.

4. A method for automatically focusing an optical system comprising the steps of:

picking up an image of an object to be inspected through said optical system;

converting said image into a video signal using a camera having a 2;

1 interlacing mode, said camera opto-electronically converting said image into alternating odd number fields and even number fields, said video signal being representative of a first image of one said odd or even number fields;

digitizing said video signal;

transferring said digitized video signal to a memory;

carrying out image processing of said transferred digitized video signal read out from said memory to obtain a focus adjustment evaluation quantity, said transfer and image processing of said first image as represented by said video signal being completed during an electric charge storage time of a second image of said one of said odd or even number fields, said step of carrying out image processing being executed using only digitized video signals representing said one of said odd or even number fields; and

performing position control of said optical system in a direction that said focus adjustment evaluation quantity approaches a maximum, said position control step being executed based on said first image during a blanking time between electric charge storage times of said second image and a third image of said one of said odd or even number fields or during a start part of time of the electric charge storage time of said third image or an end part of time of the electric charge storage time of said second image within a range that does not influence accuracy of the focus adjustment evaluation quantity.

5. A method for automatically focussing an optical system comprising the steps of:

picking up an image of an object to be inspected through an optical system;

opto-electrically converting said image into a video signal using a camera having a noninterlace mode, said video signal representing a first image;

digitizing said video signal;

transferring said digitized video signal to a memory, said transfer of said digitized video signal representing said first image being performed during an electric charge storage time of a second consecutive image in said camera;

carrying out image processing of said transferred digitized video signal read out from said frame to obtain a focus adjustment evaluation quantity, said image processing of said first image as represented by said video signal being carried out during said electric charge storage time of a third image consecutive to said second image; and

performing position control of said optical system in a direction that said focus adjustment evaluation quantity approaches a maximum, said position control step being executed based on said first image during a blanking time between electric charge storage times of said third image and a fourth image consecutive to said third image or during a start part of time of the electric charge storage time of said fourth image or an end part of time of the electric charge storage time of said third image.