-
1 3,165,151 ' PHGTOELECTRKJ EPJSPECTEGN AND SGRTENG MACHINES Paul Nash, 1132 Trent St, Ottawa, @ntaric, (Ianada Filed Apr. 14, 1959, Ser. No. 806,349 Claims priority, application Canada Apr. 9, 1957 33 Ciaims. (Cl. 259-219) This invention relates to new and useful improvements in photo electric apparatus for inspecting sheet materials and the method of examining sheet materials for the de tection and separation of defective parts thereof and is a continuation-in-part of my application 37160
- 上一篇：基于视觉的六个自由度机器人英文文献和中文翻译
- 下一篇：有限元法设计圆杯拉深级进模英文文献和中文翻译
Serial No. 726, 920, ?led April 7, 1958, and now abandoned. The present invention is more particularly useful in the manufacture of high quality paper. When associated with a paper cutting machine, the defects of the paper are detected on the uncut and continuously moving paper sheet as it enters the cutting machine. The paper is then cut into sheets of the required size and with the aid of a de?ector or grading switch, actuated by the output of photoelectric means and associated electrical devices, is sorted into two compartments. In one compartment only the ?rst grade sheets without defects are stacked, while in the other compartment the defective, second grade sheets are stacked. Defects in ?rst grade paper consist of dark discolora tions, starch spots, holes, folds, tears and similar inclu sions ‘and discontinuities. Defects may also consist of intensely small spots or larger areas of faint discolorations and may extend in the direction of the travel of the paper or at right angles to the direction of the travel of the paper. The photoelectric means and associated circuits must therefore have different characteristics ‘for the reli able detection of defects. In contradistinction to prior proposals, the present in vention will detect and grade all types of discolorations. The prior art discloses rotating, fast moving scanning means or electronic “?ying spot” scanning type cathode ray tube for scanning and detecting the light intensity of elementary areas of a travelling paper sheet. In such scanning methods, the photoelectric means is modulated by the scanning device itself, such modulation being pres~ cut when the paper sheet under observation is without defects. As the said device scans the elementary areas from the start of the selected paper section to it end, the intensity of the re?ected light picked up by the photo electric means changes. In order to eliminate such un wanted modulation of the photoelectric means, ?lters must be employed which do not pass this basic scanning lfre- , quency component of the signal. When the paper sheet is discolored the entire length of the scanned paper sec tion, the defect signals produced have the same frequency content as the scanning frequency and therefore the de feet in the paper can not be detected. Scanning means or methods may be employed wherein modulation of the phototelectric means due to the scan ning action itself is not present.
For example, adjacent elementary areas of the sheet paper can be scanned simultaneously by two scanning devices in conjunction with two photoelectric pickup means with their outputs connected in “push-pull,” each scanning device being associated with one of the two photoelectric means. The combination of such a double, push-pull scanning system does not respond to light intensity changes which are in phase. Such systems however cannot detect discolora tions which extend in the sheet in the direction of the travel of the paper and at right angles to the scanning motion. In the foregoing description, it was assumed that the elementary areas scanned simultaneously are adjacent in the direction of movement or travel of the 15 20 55 60 65 70 2 paper. When the simultaneously scanned‘ elementary areas are adjacent in any other direction relative to the direction of the travel ‘of the paper, then faint defects which extend in the same direction as the adjacent ele mentary areas cannot be detected. For example, the elementary areas may be adjacent in the direction of scanned motion and at right angles to the direction of the travel of the paper. Further, some high grade papers, such as for example bond paper, have non-uniform textures. When such paper is scanned by the illumination of an elementary area, the photoelectric means is modulated according to the intensity changes of the bond paper texture. Such modulation is termed the “noise level" of the particular paper. Investigations on bond paper samples have shown that paper noise can result in a percentage modulation of the photoelectric means as high as three parts in one hundred. As a result, faint defects extending over large areas of bond type paper sheets and detracting from the quality of the paper, cannot be detected against the paper noise level. According to the objects of this invention all types of discolorations and defects in sheet paper are reliably de tected, the noise level of the paper is reduced as ob— served by the photoelectric means which are positioned close to the paper in'a line and preferably at right angles to the direction of motion of the paper sheet and such photoelectric means are not associated with mechanical or electronic scanning means. For purposes of simplicity in description, the material under inspection is paper, the invention however is appli cable to the sorting of other types of sheet materials un cut or already cut and of substantially uniform re?ection characteristics when unblemished. The invention is also applicable to rewinding machines, machines which manu facture the sheet materials, sorting machines and cutting machines. When the present invention is applied to cutting ma chines, the sheet paper is fed from a generally large roll via auxiliary rollers which eliminate ?utter and folds in the material moving to an inspection surface or roller above which the travelling sheet is examined by photo electric means. The 'line of photoelectric means may con sist of a number of photoelectric cells placed side by side in such a manner that each photoelectric cell observes a narrow strip of the paper through an aperture.