Well balanced cathode coupled long-tailed ampli?ers differentiate as much as 10,000 to 1 between in-phase and anti-phase signals. The cathode coupled long-tailed pair type ampli?ers will convert the signal reaching only one grid into two symmetrical anti-phase push-pull signals at the two con trol grids and plates of each amplifying stage. Further, the light source can extinguish momentarily, but such an ampli?er will not respond even to such a major disturbance in the system. According to the invention, the row of photoelectric cells in the inspection head are paired and connected in such a manner that substantially all defects of the sheet material 'are detected, while interference signals being of the same or greater magnitude than the defect signals, are not ampli?ed. V ' Having regard to the foregoing and other objects and advantages which will become apparent as the description proceeds and the details become known, the invention consists essentially of the novel combination and arrange ment of parts hereinafter described in more particular detail and illustrated in the accompanying drawings in which: FIG. 1 is a diagrammatic illustration‘ of the present invention which is shown in association with a paper cutting machine. FIG. 2 is an enlarged diagrammatic view showing the photoelectric inspecting means together with the paper ‘cutting’ and grading means. FIG. 3 is a section taken on the line 3—3 of FIG. 2. FIG. 4 is a schematic representation of a circuit ar rangement for the photoelectric cells and in block di agram form, of the double channel feature of the inven tion, as used between the photoelectric cell ampli?er and the output pulse generator. FIG. 5 is the circuit diagram of an'integrating stage as used between the photoelectric cell ampli?er and the out put pulse generator. FIG. 6 is a circuit diagram of a thyratron controlled solenoid actuator as used between the pulse generator and the grading switch. FIG. 7 is a schematic viewiof the rotary cutting blade and operating switches shown mounted on a disk sup‘ port. FIG. 8 is a block diagram representation of photoelec— tric cells connected to two ampli?ers. FIG. 9 is a block diagram representation of photoelec— tric cells connected to more than two ampli?ers. FIG. 10 is a circuit diagram of the amplifying system and of the control circuit common to all ampli?ers. FIG. 11 represents waveforms of the integrator chan nel of the amplifying system. Referring now to the accompanying drawings wherein the present invention is illustrated and wherein like nu merals and characters of reference designate correspond ing parts in the various illustrations, the numeral 1 indi cates a roll upon which the continuous paper sheet 2 is wound and stored. As observed in FIG. .1, the sheet paper moves over and under idling feed rollers 3 and 4 respectively and then, after moving ‘over inspection roll er 5, passes between draw-rolls 11 and 12 to the cutting station where stationary cutting blade :13 and rotary cutting blade 14 are located. After the sheets of paper are out, they are moved by carrying tapes 15 to a grad ing switch 16 which deflects the defective sheets onto a layboy in the second-grade compartment 19 while the sheets :of paper without blemishes or defects pass over grading switch .16 and are carried by tapes 13 onto a lay boy in the ?rst'grade compartment which is indicated by the numeral 20. In structure, inspection housing 9 is elongated as il lustrated in ‘FIG. 3 and has mounted therein multiple photoelectric cells 6 and cathode or anode follower thermionic tubes 21 as seen in FIG. 2. Directly beneath the photoelectric cells, the lower wall of the housing is formed with a narrow aperture 7 which extends from end to end of the housing. Walls 7a extend downwardly from aperture ‘7 and terminate in the form. of aperture 7 b which also extends the full length of the housing and forms an important feature of the invention.
Addition ally, the lower outer walls 10 of housing ‘9 extend down wardly from the body of the housing and provide spaced, inpidual compartments within which ?uorescent lamps 8 are mounted :on opposite sides of aperture 7b all of which will be later referred to. By again referring to FIG. 1 it will be seen that idler roller 4 is so positioned that by being close to'yet below the level of inspection roller 5', it eliminates ?utter and folds in paper sheet 2 and directs the paper in such a manner that it follows the curvature of a substantial seg ment of the ‘inspection unit 5. Thus, lamps 8 can be positioned close to the surface of the paper ‘and will not interfere with the optimal position of aperture 7. The draw rollers 11 and 12 are also so positioned that the latter purpose is served. The rotating inspection roller 5 is not an essential fea ture of the present invention since a similar stationary, polished surface can replace the rotatable inspection roll er. The former type of inspection roller has the ad vantage of minimum friction between the moving paper and the surface above which the inspection of the paper takes place but it also has the disadvantage of causing error signals when the axial symmetry of the roller is imperfect. - A non-rotating polished inspection surface is free from the aforementioned disadvantages, however, friction be tween the paper and the inspection surface can build up high static charges upon the paper, but such static elec tricity can be eliminated by ‘the use of radiating isotopes preferably located below the inspection surface. The inspection surface of the member 5 is preferably dark and non~reiiecting in order to detect the transparent defects or “shiners,” and such surface is well suited for certain types of relatively heavy, white and light coloured papers. When light weight and transparent sheets are being inspected, a white, polished metallic or gray sur face with high re?ection co-e?icient will minimize the lack of uniformity of the unblemished paper texture due to transparency, while the detection of “shiners” is still possible. Various grades of paper of various thickness and colour require different coloured light or darker in spection surfaces in order to detect, with optimal effi ciency, all types of defects and in order to minimize the inherent paper background noise. The inspection mem 10 15 20 25 30 35 40 50 55 60 65 70 75 bers 5 can be made removable in order to give best per formance with various grades of paper. The photoelectric inspection means consists of a num ber of photoelectric cells one of which is indicated by the numeral 6 in FIGS. 1 and 2. Aperture 7 is formed be tween parts of the housing 9 and 10 while lamps f’: illu minate the paper sheet 2. The lower section 10 of the housing is positioned close to the paper in order to exclude external light, while the light illumination of the inspected section of the paper is kept constant in the frequency re sponse range of the amplifying system to which the photo electric cells 6 are connected, otherwise, changes of ex ternal illumination or of the light output of lamps 8 could initiate false defect signals which would result in de?ect ing unblemished paper sheets into the second grade com partment. The lamps 8 are preferably D.C. ?uorescent lamps which have the form of elongated tubes which ex tend the entire width of the paper 2 and such lamps are fed from a regulated D.C. power supply. Regulation and peak to peak ripple of such supplies is better than a 0.5 part in a hundred for plus and a minus 10 part in a hundred line input voltage variation. In FIG. 2, I have illustrated a cathode or anode fol lower therrnionic tube 21 which is fed by an optimum number of photoelectric cells 6. The line of photo electric cells illustrated in FIG. 3 shows them close to one another for viewing the entire width of the inspected sheet. As an example, if there are sixty photoelectric cells, groups of ten cells may be joined to one cathode follower 21 so that there will be six cathode followers mounted inside vhousing 9 and each cathode will be connected to a separate ampli?er. 光电检测与分选机器英文文献和中文翻译(3):http://www.751com.cn/fanyi/lunwen_35843.html