GB1437951A - Apparatus for detercting blemishes in sheet material - Google Patents
Apparatus for detercting blemishes in sheet materialInfo
- Publication number
- GB1437951A GB1437951A GB2239372A GB2239372A GB1437951A GB 1437951 A GB1437951 A GB 1437951A GB 2239372 A GB2239372 A GB 2239372A GB 2239372 A GB2239372 A GB 2239372A GB 1437951 A GB1437951 A GB 1437951A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signal
- signals
- amplifier
- threshold circuit
- web
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K5/00—Manipulating of pulses not covered by one of the other main groups of this subclass
- H03K5/01—Shaping pulses
- H03K5/02—Shaping pulses by amplifying
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/8901—Optical details; Scanning details
- G01N21/8903—Optical details; Scanning details using a multiple detector array
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/892—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the flaw, defect or object feature examined
- G01N21/896—Optical defects in or on transparent materials, e.g. distortion, surface flaws in conveyed flat sheet or rod
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/08—Optical fibres; light guides
- G01N2201/0813—Arrangement of collimator tubes, glass or empty
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Abstract
1437951 Thresholding circuits P NASH 14 May 1973 22393/72 Heading H3T [Also in Division G1] A device for detecting flaws in moving webs of sheet material 1, Fig. 1, comprising a row of photo-cells 16 arranged transversely to the direction of movement of the web and lamps 4, 5, 6, illuminating the web from above and below, is characterized in that the outputs of the cells, shown at 20,..., 27, Fig. 2, are combined in pairs in amplifiers 51, whose outputs are in turn combined over diodes 54, ... , 57 to feed a single threshold circuit 62, thereby feeding to the threshold circuit a signal in which the noise component is of smaller peak-to-peak amplitude than that of any of the signals from the individual amplifiers. This reduction in the noise variance-but not in its absolute level-results because the arrangement is such that only the largest of the signals applied to diodes 54, ... , 57 is applied to the threshold circuit 62, and is illustrated in Fig. 17A, which shows how the range of variation 281 of the largest 278 of three random noise signals 275, 276 and 277 is less than the range of variation 279 of either of the individual noise signals. Rather than using a differential amplifier, as in Fig. 2, having inverse outputs, an operational amplifier 79, Fig. 3, can be used, in which case phototransistor pairs 64, 65 have their outputs subtracted and applied to one input 73 of the amplifier and its output is rectified positively by a diode 83, and negatively by a diode 86. As in Fig. 2, the output of many such amplifiers are combined over diodes 83, 84, 85 and 86, 87, 88, to provide the output signals, one 90 being applied to a threshold circuit constituted by a saturable amplifier 93, and the other (not referenced) being applied to a similar threshold circuit, not shown, with a threshold level of E 1 , Fig. 12A, surface defects causing signals such as 202 are detected, but small but sharply defined defects that cause spikes such as 198 are not. In a modification, Fig. 13, the signal Fig. 12A from amplifier 79, is differentiated 205, 206, to give a signal, Fig. 12B, in which the presence of the small but sharply defined defect 200 is readily detectable, and this signal is mixed over diodes 215 (together with other similar signals), with the output from amplifier 79 to form the signal 90 that is applied to the threshold circuit. In a further modification designed to recognize surface defects such as a pencil line in the direction of movement of the web, which defects whilst producing only a small increase 219, Fig. 14A, in the background noise level 218, do produce a signal of considerable duration, the signal 90 of Fig. 3 is integrated Fig. 15 so as to produce a signal Fig. 14B, which does, at its peak, exceed the threshold level E 1 . The integrator is fed via a circuit 224, 226 which is arranged to cut out the background noise 218, Fig. 14A, and is reset by pulses 221, Fig. 14B, applied to a terminal 240, Fig. 15, these pulses being produced by a uni-junction transistor oscillator (Fig. 16, not shown). By selecting an appropriate integrating capacitor 229, and the frequency of the reset pulses 221, the integration can be made to extend over varying lengths of the web being examined.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2239372A GB1437951A (en) | 1972-05-12 | 1972-05-12 | Apparatus for detercting blemishes in sheet material |
US00359511A US3827809A (en) | 1972-05-12 | 1973-05-11 | Circuits for deriving a common output signal from a plurality of amplifiers in apparatus for detecting blemishes in sheet material |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2239372A GB1437951A (en) | 1972-05-12 | 1972-05-12 | Apparatus for detercting blemishes in sheet material |
GB2371172 | 1972-05-19 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1437951A true GB1437951A (en) | 1976-06-03 |
Family
ID=26255886
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB2239372A Expired GB1437951A (en) | 1972-05-12 | 1972-05-12 | Apparatus for detercting blemishes in sheet material |
Country Status (2)
Country | Link |
---|---|
US (1) | US3827809A (en) |
GB (1) | GB1437951A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2144218A (en) * | 1983-06-28 | 1985-02-27 | Enso Gutzeit Oy | Observing streaks in paper |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1540066A (en) * | 1975-07-25 | 1979-02-07 | Nash P | Optical inspection systems |
CH627497A5 (en) * | 1978-04-26 | 1982-01-15 | Zellweger Uster Ag | DEVICE FOR OBTAINING ONE OF THE REGULATORY SIGNALS RELATING TO THE DENSITY OF THE FIBER COATING ON THE TAMBOUR OF A CARD. |
US4402604A (en) * | 1980-03-20 | 1983-09-06 | Paul Nash | Method for the on-line measurement of inclusions in pulp |
US5326963A (en) * | 1992-10-02 | 1994-07-05 | Kronos Incorporated | Electro-optic barcode reader |
US6369588B1 (en) | 1999-11-09 | 2002-04-09 | Gerard E. Sleefe | Sensor system for web inspection |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3105152A (en) * | 1959-01-12 | 1963-09-24 | Nash Paul | Inspection of sheet materials by photoelectric means |
US3128385A (en) * | 1959-02-18 | 1964-04-07 | Cutler Hammer Inc | Photosensitive hole detector using phosphor radiation source |
US3206606A (en) * | 1961-07-20 | 1965-09-14 | Eastman Kodak Co | Photosensitive inspection method and apparatus |
-
1972
- 1972-05-12 GB GB2239372A patent/GB1437951A/en not_active Expired
-
1973
- 1973-05-11 US US00359511A patent/US3827809A/en not_active Expired - Lifetime
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2144218A (en) * | 1983-06-28 | 1985-02-27 | Enso Gutzeit Oy | Observing streaks in paper |
Also Published As
Publication number | Publication date |
---|---|
US3827809A (en) | 1974-08-06 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed [section 19, patents act 1949] | ||
PCNP | Patent ceased through non-payment of renewal fee |