Browse Prior Art Database

Row By Row Dynamic Image Analysis of Matrix of Scanned Points

IP.com Disclosure Number: IPCOM000050396D
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 7 page(s) / 115K

Publishing Venue

IBM

Related People

McAuley, D: AUTHOR

Abstract

The method described has general application to the dynamic row by row image analysis of a matrix of scanned points. Although it will be described with reference to the testing of plasma display panels for defective display points, the methodology could apply to image processing, character recognition and linear scanning applications. Connectivity, chain set-up, dynamic memory allocation and chaining algorithms are described in some detail. As is well known, a plasma display panel consists of man crosspoint each of which can be used to display a picture element (pel) Current methods of testing display panels test each crosspoint to determine whether it can be switched on and switched off (erased).

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Row By Row Dynamic Image Analysis of Matrix of Scanned Points

The method described has general application to the dynamic row by row image analysis of a matrix of scanned points. Although it will be described with reference to the testing of plasma display panels for defective display points, the methodology could apply to image processing, character recognition and linear scanning applications. Connectivity, chain set-up, dynamic memory allocation and chaining algorithms are described in some detail. As is well known, a plasma display panel consists of man crosspoint each of which can be used to display a picture element (pel) Current methods of testing display panels test each crosspoint to determine whether it can be switched on and switched off (erased). Clearly the usability of a Panel containing defective cells will depend on a good knowledge of the pattern of failed crosspoints or cells. In operation, the panel is scanned and a Cosmetic Analysis Program is called by the control processor to determine the acceptability of the panel based on a predetermined set of criteria. These criteria are used to specify the number of allowable defective cells on the panel.

The allowable defects are also known as Cosmetic Defects, and they can appear as solitary failures or as varying types and sizes of patterns under certain circumstances. The purpose of the Cosmetic Analysis software is therefore to detect and analyze these solitary failures and/or clusters of failing cells. The following documentation will describe how this analysis is carried out.

SYSTEM ANALYSIS Individual cell information is passed to the software via a Binary "Video-Out" from the camera (Fig. 1). This Video-Out reflects the status of one row of cells, since the panel is scanned one row at a time by means of a rotating mirror. Typically, there may be 768 rows with each row comprising 960 cells, giving a total number of cells to be tested of 737,280. Data transfer is achieved by successive reads of a FIFO (first in, first out) register where the binary video is held, with each read accessing one 8-bit byte of information. This means 120 reads of the FIFO per row (8 x 120=960). The binary video of actual data can therefore be compared to a previously generated mask of expected data in order to detect failing cells within this row. On encountering a defective cell, therefore, the main body of the software is invoked and proceeds to analyze this cell with respect to all other defective cells, and with reference to the specified criteria. Since a large panel cannot be scanned or viewed in its entirety, i.e., as a large 960 x 768-cell matrix, a method of "building up a picture" of the panel, row by row, is used. Since defective cell information in one row could be pertinent to defective cell information in the following row (not yet scanned), a method of logging or storing this data is required. Considering the size of the panel, and therefore the number of possible defec...