Image analysis – Pattern recognition – Feature extraction
Reexamination Certificate
2001-01-31
2003-10-21
Patel, Jayanti K. (Department: 2623)
Image analysis
Pattern recognition
Feature extraction
C356S239300
Reexamination Certificate
active
06636632
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processor and image processing method.
2. Discussion of the Background
An inspected object such as a printed wiring board often includes a shape that often misjudged as a defect by a wiring pattern inspecting apparatus. Because of this a part containing the shape must not be a target of the inspection. A part of a hole connecting between layers, such as a through hole and a photo via hole (hereinafter referred to as “a via hole”) is correspondent to the shape. For example, Japanese Patent Laid-Open No. 6-294626 bulletin disclosed a conventional wiring pattern inspecting apparatus comprising a quality inspection of a wiring pattern by extracting a true defect data based on a pattern image got by capturing an inspected object, and a hole mask image made separately. That is, among defect candidate data in the pattern image, a data not correspond with the hole mask image is a true defect data. This hole mask image is made by contrasting a hole measurement signal showing a part comprising a shape considered to be a through hole in a pattern image and a hole recognition effective signal provided from a specification of the inspected object. The contents of Japanese Patent Laid-Open No. 6-294626 are incorporated herein by reference in their entirety.
In this conventional technique, the extraction of the hole measurement signal from the pattern image is done as follows. As shown in
FIG. 11
, a number that a black pixel continues is counted on every eight directions of N, NE, E, SE, S, SW, W, NW from a point where four black pixels are gathered in a binarized pattern image. And the hole measurement signal is turned on about each pixel of the point if there is a number that the black pixel continues in a predetermined range (an upper limit value and a lower limit value of a number of pixel corresponding to a through hole radius) about each direction.
However, the conventional wiring pattern inspecting apparatus includes a problem explained in the following. A penetration hole such as a through hole can be coped with, but a non-through hole such as a blind via hole formed by a laser process or a photo via hole cannot. The cause is included in a difference on a binarized pattern image with a through hole and a photo via hole. A through hole is a penetration hole, and then if an internal pixel of the through hole is binarized, the pixel becomes black by all means. Because of this, on a binarized pattern image, the through hole appears as an approximately circular mass of black pixels as shown in FIG.
3
. Therefore the through hole can be recognized by a measurement such as FIG.
11
. Still, in
FIG. 3
, “0” shows a black level with a white level “1”(the same in
FIG. 4
, FIG.
13
and so forth).
On the contrary, as for a photo via hole and so on, an internal pixel does not always become black because base copper in the hole shines dully. So, as shown in
FIG. 4
, on a binarized pattern image, the photo via hole is recognized as a black pixel area of a distorted shape. There can be a part T that has only one pixel width in the black pixel area. If the measurement such as
FIG. 11
is done with the part T, as shown in
FIG. 12
, a count start pixel on a certain direction (N, NE, NW) does not become black. Then, a hole measurement signal cannot be turned on about this part T. Therefore, the measurement such as
FIG. 11
cannot be done on this part T. Still, in
FIG. 12
, sign “x” referred right of a direction sign shows that the count on the direction cannot be done. And, a number in parentheses on right of a direction sign shows a count number on the direction (the same in FIG.
13
).
Although, by paying attention to an area except for the part T in a shape shown in
FIG. 4
, the measurement such as
FIG. 1
looks possible, the number is not in the predetermined range. A case that the measurement such as
FIG. 11
is really possible is extremely limited. Therefore, by a hole mask image of the conventional technique, the coat-ability of a photo via hole is bad, because an appropriate hole mask image can not be made. As a result in a case of an inspection of a wiring pattern, a lot of false signal occurs, and then the inspecting apparatus is inconvenience.
By the way, in
FIG. 12
, a value of a numerical sum of a black pixel on each direction becomes, even the part T in
FIG. 4
, a positive finite value (3+1+1+1+2=8). Therefore, by setting a constant upper limit value in the value of the sum, the measurement such as
FIG. 11
can recognize the part T. However, when the measurement is done with a parallel pattern consisting of a conductor spacing Z of width in unison with a diameter of a photo via hole as shown in
FIG. 13
, the value of the sum (4+4+4=12) can become equal to or less than the upper limit value. This means a place that is not a photo via hole is recognized a place that is a photo via hole. If there is a hole recognition effective signal near the parallel pattern, an unnecessary hole mask is generated, and then the reliability of the inspection is dropped. Although, it is conceivable that the affine transformation (a parallel transfer, magnification revision, a turn transfer) is made on the pattern image for matching, the inspection tact time increases largely.
SUMMARY OF THE INVENTION
According to one aspect of the invention, an image processor includes a pattern image making unit, a judgment unit, a recognition area making unit, a processing candidate authorization unit and a processing image making unit. The pattern image making unit is for making a pattern image formed from pixel data obtained by capturing a pattern of an object. The judgment means is for counting, with respect to pixels included in the pattern image and in a plural directions from a selected pixel among the pixels, a number of same kind of pixels which consecutively continues from the selected pixel, and for determining in the plural directions whether the number is larger than a reference value. The recognition area making unit is for producing a processing recognition area effective signal that shows a range in which an area to be processed exists with respect to the object. The processing candidate authorization unit is for determining whether the selected pixel is a processing candidate pixel based on a determination of the judgment unit. The processing image making unit is for making processing image by comparing the processing candidate pixel and the processing recognition area effective signal.
According to another aspect of the invention, an image processor includes a pattern image making unit, a diameter judging unit, a mask recognition area making unit, a candidate authorization unit, a mask making unit and an inspecting unit. The pattern image making unit is for making a pattern image formed from pixel data obtained by capturing a wiring pattern of an object to be inspected. The diameter judging unit is for counting, with respect to pixels included in the pattern image and in a plural directions from a selected pixel among the pixels, a number of same kind of pixels which consecutively continues from the selected pixel, and for determining in the plural directions whether the number is larger than a reference value. The mask recognition area making unit is for producing a mask recognition effective signal that shows a range in which an area which is outside an inspection area exists with respect to the object. The mask candidate authorization unit is for determining whether the selected pixel is a mask candidate pixel based on a determination of the diameter judging unit. The mask making unit is for making a mask image by comparing the mask candidate pixel and the a mask recognition effective signal. The inspecting unit is for extracting a defect shape from a part of the pattern image except for the mask image.
According to yet another aspect of the invention, an image processing method includes making a pattern image formed from pixel data obtained by capt
Azarian Seyed
Ibiden Co. Ltd.
Patel Jayanti K.
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