US 5,347,591 AGranted

Method of and device for determining positioning between a hole and a wiring pattern on a printed circuit board by utilizing a set of area values

AssigneeDainippon Screen Mfg. Co., Ltd.

InventorsHiroyuki Onishi, Tetsuo Hoki

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Abstract

A printed board, on which a wiring pattern and a through hole to be inspected are provided, is scanned pixel by pixel and is read optically. The data obtained by scanning is converted into an electric signal to obtain image data. On the basis of the image data thus obtained, a pattern image representing the wiring pattern an a hole image representing the through hole are obtained. A center and a radius of the hole image are obtained from the image data. Then, a plurality of ring-shaped masks are obtained by magnifying the hole image at a plurality of magnifications. The size of the pattern image is normalized by the size of the hole image, and the, respective areas of overlapped regions between a plurality of the ringshaped masks and the pattern image are detected. Since these areas are obtained with an isotropic method, they do not depend on the directions of a line entering a land. By simulation, correspondence between the area of the overlapped regions and a relative positional relation between the wiring pattern and the through hole is obtained in advance. On the basis of this known correspondence, a relative positional relation between the wiring pattern and the through hole is evaluated by utilizing a neural network that has been taught such known correspondence.

Claims12

Dependent claims

A method of inspecting a pattern on a printed board on which a wiring pattern is provided and through which a through hole is formed, said method comprising steps:

(a) of optically reading said printed board to obtain image data comprising a plurality of pixels and representing an image of said printed board;
(b) of obtaining a pattern image representing said wiring pattern and a hole image representing said through hole on the basis of said image data;
(c) of obtaining a plurality of similar ring-shaped masks from said hole image;
(d) of calculating a set of area values each representing an area of an overlapped region of said pattern image and each of said plurality of similar ring-shaped masks;
(e) of obtaining a relative positional relation between said wiring pattern and said through hole as a function of said set of area values;
said relative positional relation being expressed by a characteristic value, and prior to said step (c) said method also comprising steps:
(f) of obtaining a first correlation which shows values of said set of area values in relation to particular states of said relative positional relation, and
(g) of utilizing a first neural network to obtain a second correlation which shows values of said characteristic value in relation to particular values of said set of said area values;
said step (e) comprising step (e-1) of using said second correlation for converting said set of said area values which are yielded at said step (d) to said characteristic value;
said step (e-1) comprising steps of:
(e-1-1) preparing a second neural network,
(e-1-2) teaching said second correlation to said second neural network, and
(e-1-3) as said characteristic value, determining an output of said second neural network by inputting said step of said area values to said second neural network;
said step (g) comprising step (g-1) of utilizing a first neural network to obtain said second correlation.

11 more elements

A device for inspecting a pattern on a printed board on which a wiring pattern is provided and through which a through hole is formed, said device comprising:

(a) means for optically reading said printed board to obtain image data comprising a plurality of pixels and representing an image of said printed board;
(b) means for obtaining a pattern image representing said wiring pattern and a hole image representing said through hole on the basis of said image data;
(c) means for obtaining a plurality of similar ring-shaped masks from said hole image;
(d) means for calculating a set of area values each representing an area of an overlapped region of said pattern image and each of said plurality of similar ring-shaped masks;
and
(e) means for obtaining a relative positional relation between said wiring pattern and said through hole as a function of said set of area values;
said relative positional relationship being expressed by a characteristic value, and said (e) means comprising:
(e-1) means for holding data representing a first correlation which shows values of said set of area values in relation to particular states of said characteristic values,
(e-2) means for obtaining a second correlation which shows values of said characteristic value in relation to particular values of said set of area vales, and
(e-3) means for using said second correlation for converting said set of area values calculated by said (a) means to said characteristic value;
and
said (e-2) means comprising (e-2-1) neural network means to which said second correlation is taught and is operable to convert said set of area values into said characteristic value through said second correlation.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/784,574Filed 29 Oct 1991
Priority: JP 2-29410630 Oct 1990
Granted: 13 Sep 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G06T 7/70
Image analysis: determining position or orientation of objects or cameras
G06V 10/98
Arrangements for image or video recognition or understanding: detection or correction of errors, e.g. by rescanning the pattern or by human…
G06T 2207/30141
Industrial image inspection: printed circuit board [PCB]
G06V 2201/06
Indexing scheme relating to image or video recognition or understanding: recognition of objects for industrial automation

Family

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