Facsimile and static presentation processing – Facsimile – Recording apparatus
Patent
1990-03-15
1992-03-31
Groody, James J.
Facsimile and static presentation processing
Facsimile
Recording apparatus
2502013, H04N 5232, G01J 120
Patent
active
051012774
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to an automatic focus adjustment apparatus of an optical apparatus for use in assembly and inspection works in a fabrication process and so on of an electronic equipment.
Further in detail, the present invention relates to an improvement in an automatic focus adjustment apparatus which is constituted in a manner that an object to be inspected is picked up through an optical system. A video signal which is opto-electronically converted with a camera is digitized and is transferred to a frame memory. Image processing is performed on a signal read out from the frame memory and a focus adjustment evaluation quantity is produced. Finally position control of the aforementioned optical system is made in a direction such that the focus adjustment evaluation quantity approaches the maximum.
2. Background Art
Hitherto, an optical inspection apparatus as shown in FIG. 1 is used in assembly and inspection works. An object 1 to be inspected is rested on a table 2, and a microscope 4 is installed on the table 2 with a slide table 3 therebetween so as to permit upward and downward movement. An industrial camera 5 using CCD for a solid-state image pickup device is mounted on the eyepiece part of the microscope 4, and the industrial camera 5 moves upward and downward together with the microscope 4. The slide table 3 is so configurated as to drive the microscope 4 to move up and down by a motor 6. The motor 6 is driven on the basis of an output signal of the industrial camera 5 as described hereafter and automatic focus adjustment is carried out. An image of a focused point is issued from the output of an A/D converter 7 and is inputted in an inspection apparatus which is not shown in the figure, and is used for shape inspection of the object 1 to be inspected or for such as position control of the object 1 to be inspected on the table 2.
The video signal of the industrial camera 5 is digitized by the A/D converter 7, and then is temporarily memorized alternately in first and second frame memories 9, 10 via a control part 8. Subsequently, in the control part 8, images of the first and second frame memories 9, 10 are read out alternately and image processing is applied to the images and a focus adjustment evaluation quantity is calculated. The control part 8 then drives the motor 6 by one step in a direction so that the focus adjustment evaluation quantity approaches the maximum through a drive circuit 11. Numeral 12 designates a clock generation circuit for generating a clock signal which is an operating reference of the control part 8.
The fundamental operation of the control part 8 is shown in FIG. 2-FIG. 4. The fundamental operation is to transfer the microscope 4 little by little as shown in FIG. 2, and the focus adjustment evaluation quantity Hi is calculated by such a method as calculating a differential coefficient or an integral value of a gradation levels on an edge part from an image data. When Hi has taken the maximum value H.sub.max so that the position of the microscope 4 is on best focus, the slide table 3 is positioned at the position GZ.sub.1. At this time, for every transfers of the microscope 4 by one step, it is necessary to carry out the respective processings of image-electric conversion, video transfer to the frame memory, calculation (image processing) of the focus adjustment evaluation quantity Hi and motor operation.
In the conventional automatic focus adjustment apparatus, in order to shorten a time period of focusing, the consecutive processings are carried out in parallel and in synchronism with a camera clock as shown in FIG. 3.
Namely, a pulse interval T which is generated by the clock generation circuit 12 is set so as to be identical with the camera clock of the industrial camera 5, and by making synchronization with this clock the respective processings of the image-electric conversion, the video transfer to the frame memory, the image processing and motor operation are accomplished. Moreover, the respective processings are parall
REFERENCES:
patent: 4740828 (1988-04-01), Kinoshita
patent: 4752831 (1988-06-01), Biber et al.
patent: 4816916 (1989-03-01), Akiyama
patent: 4829374 (1989-05-01), Miyamoto et al.
patent: 4922346 (1990-05-01), Hidaka et al.
Groody James J.
Matshushita Electric Industrial Co., Ltd.
Metjahic Safet
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