A kind of plasma display screen fault checking method
Technical field
The present invention relates to a kind of plasma display screen fault checking method, be used for the graphic defects of checking that plasma panel manufacturing process occurs.
Background technology
Check as traditional being used to and the method for display floater image deflects normally to adopt ccd video camera to obtain the substrate surface pattern image.Graphic defects has appearred as certain on the substrate, promptly electrode open circuit or adjacent electrode between short circuit etc. appears, the gray value of fault point will difference occur with the gray value of adjacent normal point.Adopt the gray value difference of periodic comparison and consecutive points promptly defect point can be checked out.
The electrode of plasma panel comprises electrode part branch and lead portion at present, traditional detection method can only be used to detect the graphic defects with the graphics field of periodically arranging, and for not having the graphics field of periodically arranging, graphic defects as the lead portion appearance, be the A point defect in the accompanying drawing 1, this kind inspection method can't be checked.
Summary of the invention
In order to overcome the shortcoming and defect that above prior art exists, the object of the present invention is to provide a kind of repeatedly double counting that need not to carry out, can fast detecting go out the plasma display screen fault checking method of the graphic defects on the plasma panel.
To achieve these goals, the technical solution used in the present invention is, a kind of inspection method of plasma panel defective is at first obtained the image of substrate surface, and the image that gets access to is carried out the thresholding processing promptly depict the substrate surface edge of image according to the gray value difference with video camera;
Secondly, definition is used for the detection standard picture of figure comparison, with the alignment mark on the substrate figure, compare with the corresponding alignment mark on the standard picture with detection, determine image that video camera obtains and detect, and the image that absorbs is carried out corresponding correction according to displacement and rotation amount with displacement that exists between standard picture and rotation amount;
Once more, the detection of substrate surface view data after the thresholding processing and definition is carried out difference with standard picture subtract each other processing, obtain including the binary image of defect point data;
The binary image that obtains is screened according to the inspection condition, the setting of inspection condition can be according to the big or small setting threshold of allowable defect, the point that exceeds this threshold value is judged as defective, also can be set at the gray value threshold value, binary image after difference is subtracted each other surpasses this gray value threshold value and promptly is judged as defect point, promptly can check out defect point thus.
Compare with traditional inspection method, adopt this inspection method to need not to carry out repeatedly double counting, can fast detecting go out the graphic defects on the plasma panel.Simultaneously, for the aperiodicity visuals that conventional method can't be checked, adopt this method can carry out defect inspection.
Description of drawings
Fig. 1 is a plasma panel part bus electrode schematic diagram.
Fig. 2 is the upper substrate of plasma display panel bus electrode image interception part that contains defect point that video camera gets access to.
Fig. 3 carries out thresholding image after thresholding is handled with Fig. 2.
Fig. 4 is from detecting that intercept with standard picture and part Fig. 2 same position on substrate.
Fig. 5 carries out accompanying drawing 3 and accompanying drawing 4 after the contraposition and carries out difference and subtract each other the binary map that finally obtains.
Fig. 6 is the block diagram of defect inspection of the present invention.
Embodiment
The embodiment that provides below in conjunction with accompanying drawing and inventor is described further method of the present invention.
With the bus electrode of checking 60 cun upper substrate of plasma display panel is that example further specifies this inspection method.
At first adopt ccd video camera to take the surface image of plasma panel part bus electrode shown in Figure 1.The principle of the brilliance control of lighting source is can clearly see the bus electrode lines on the image of taking during shooting, and lines parts and the gray value that does not cover the glass substrate of lines have significant difference, being convenient to the later stage carries out thresholding and handles, simultaneously to the whole base plate surface light according to evenly.Adopted the controlled high-frequency fluorescent tube of section formula brightness as lighting source in this example.
After photographing the substrate surface image, the image that photographs is carried out thresholding handle, depict the marginal information of electrode line.Fig. 2 is the upper substrate of plasma display panel bus electrode image interception part that contains defect point that video camera gets access to, and bus electrode comprises defect point as seen from the figure, and image 2 is carried out obtaining after thresholding is handled thresholding image as Fig. 3.
Definition detects uses standard picture.Detection in this example is adopted image after flawless bus electrode thresholding is handled with standard picture.Fig. 4 is from detecting that intercept with standard picture and part Fig. 2 same position on substrate.
Detection is with having alignment mark on the standard picture He on the substrate surface thresholding image, adjusts the position of substrate surface thresholding image according to the alignment mark position of the two, so that the alignment mark of the two overlaps.To detect and carry out difference with standard picture and substrate surface thresholding image and subtract each other, obtain the binary map of accompanying drawing 5.
Screen according to inspection requirements.The defective screening criteria is a defect size in this example.This example is set and is checked that threshold value is 30 elemental areas.Surpass naming a person for a particular job of this threshold value on the binary map and be judged as defect point.The defect point size is 8 * 4=32 elemental area in this accompanying drawing, and this area surpasses checks threshold value, judges that therefore this point is defect point.