GB2032618A - Creation of Inventions and Patents with Artificial Intelligence

GB2032618A – Inspection of elongate articles for surface irregularities
– Google Patents

GB2032618A – Inspection of elongate articles for surface irregularities
– Google Patents
Inspection of elongate articles for surface irregularities

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Publication number
GB2032618A

GB2032618A
GB7932278A
GB7932278A
GB2032618A
GB 2032618 A
GB2032618 A
GB 2032618A
GB 7932278 A
GB7932278 A
GB 7932278A
GB 7932278 A
GB7932278 A
GB 7932278A
GB 2032618 A
GB2032618 A
GB 2032618A
Authority
GB
United Kingdom
Prior art keywords
video signal
signal
output terminal
irregularities
light
Prior art date
1978-09-18
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.)

Withdrawn

Application number
GB7932278A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Eastman Kodak Co

Original Assignee
Eastman Kodak Co
Priority date (The priority date 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 date listed.)
1978-09-18
Filing date
1979-09-18
Publication date
1980-05-08

1978-09-18
Priority claimed from US05/943,511
external-priority
patent/US4232336A/en

1978-09-18
Priority claimed from US05/943,510
external-priority
patent/US4240110A/en

1979-09-18
Application filed by Eastman Kodak Co
filed
Critical
Eastman Kodak Co

1980-05-08
Publication of GB2032618A
publication
Critical
patent/GB2032618A/en

Status
Withdrawn
legal-status
Critical
Current

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Classifications

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION

H04N7/00—Television systems

H04N7/18—Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

H04N7/188—Capturing isolated or intermittent images triggered by the occurrence of a predetermined event, e.g. an object reaching a predetermined position

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

Abstract

Apparatus and method are described for inspecting elongate material such as strands, sheets, bundles or webs for the presence of surface irregularities. The material is illuminated for a short enough period to freeze the motion thereof leg with a stroboscopic light) and the illuminated scene is imaged on a television camera, and the video signal processed to obtain information about the irregularities. In the case of crimped fibres, regular variations should be present and can be counted within a given length, and angle of crimp can be measured. The stroboscopic light source 14 is used to illuminate the elongate material 10, preferably at an angle and to form light areas and shadowed areas depending on surface variations. A television camera 16 produces a video signal of the light and shadowed areas and such signal is electronically analysed with respect to number of alternating light and dark areas within a given length, and the relative widths of such light and dark areas, from which information can be obtained to confirm presence of irregularities, count or frequency of the irregularities, and, in the case of crimped fibres, the crimp angle. A filter can be used to improve the accuracy of the apparatus by removing low frequency signals, caused by unintentional shadowing, from the useful signals.

Description

SPECIFICATION
Inspection of elongate material
This invention relates generally to an apparatus and method for inspection of elongate material. More specifically, this invention relates to apparatus and method for inspecting elongate material such as strands, sheets, bundles or webs for the presence of surface irregularities, count of irregularities within a given length, and, in the case of crimped fibre, angle of irregularities. Data obtained from such inspection may be used for quality control purposes.
This invention is particularly useful in monitoring production lines where continuous lengths of sheet or fibrous material are produced.
Although various inspection uses will be apparent to those skilled in the art, the present invention will be described herein mainly in reference to the production of fibre tow which has been evenly crimped. Such fibre tow, e.g. cellulose acetate filter tow, is mechanically crimped to provide, for
example, 120 crimps per cm. Due to various factors, there may be lengths of the tow where crimp does not appear, or the frequency (count per unit length) or the angle of crimp does not meet the specification. Such faults can be caused by incorrect mechanical adjustments or incorrect condition of the material being crimped. Loss of crimp, incorrect crimp pitch, or incorrect crimp angle in the material may result in rejection of the material by customers and subsequent heavy losses to the manufacturer because of waste.The present invention provides a method and apparatus whereby such crimp may be continuously monitored and, if faulty conditons are detected, the appropriate steps can be taken before substantial loss results. Furthermore, such detection systems can be designed so that a plurality of production lines may be monitored from a central location.
Various electronic systems are presently known for detecting defects in continuous lengths of material. For example, U.S. Patent No, 3,584,225 relates to a yarn inspection device which uses optical devices and electronic circuitry to detect defects in yarn. U.S. Patent No. 3,114,797 relates to a television system for detecting differences or changes in shape, size, colour, intensity or texture Such differences or changes are detected by comparing a scene at one instant with an image produced from the same scene after a time delay.
U.S. Patent No. 3,700,903 relates to detection systems wherein a coherent light beam is used to scan the surface of an object in a repetitive pattern. An output signal is produced by light reflected from the object for determining characteristics of the surface of the object.
While the prior art shows the detection of surface defects or differences, this is often not sufficient information for adequate quality control and the present invention provides for obtaining useful information from irregularities such as count and shape.
It is an object of the present invention to provide an apparatus for and a method of monitoring continuous lengths of material, detecting surface irregularities, obtaining data from such detected irregularities, and converting such data into useful information.
According to the present invention there is provided apparatus, for inspecting elongate material such as strands, sheets, bundles, webs or the like arranged to move along an inspection path for the presence of surface irregularities, which apparatus comprises optical devices and electrical circuitry including a stroboscopic light source positioned above the path to illuminate the elongate material, a television camera arranged to scan the iluminated material and to generate a video signal for processing in the electronic circuitry to obtain information relative to the irregularities.
Such method and apparatus provide a convenient and reliable means for monitoring production lines to obtain physical data therefrom which can be electronically processed as a quality control measure.
The invention will be described further by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic elevation illustrating a preferred arrangement of elongate material, a television camera, and a stroboscope;
Figure 2a is a diagrammatic view of a portion of crimped fibre tow;
Figures 2b to 2g are elevation and plan views, shown diagrammatically, of fibre tow crimped at different angles, and the direction of light rays from the stroboscope;
Figure 3 is a diagram of the electrical components used in the apparatus of the invention;
Figure 4 is a circuit diagram of a video analyzer and signal comparator; and
Figure 5 is a circuit diagram of the video analyzer, a filter used for removing interference signals and the signal comparator.
To ensure uniformity of a crimped fibre tow, it is necessary to maintain the presence of crimp, a particular crimp count or frequency for a given length of tow, and/or crimp angle. The present invention provides apparatus for and a method detecting variations such as absence of crimp in the tow, the number of crimps per unit length, and the crimp angle.
Referring to Figure 1, irregularfilamentary material, e.g., a continuous band of regularly crimped fibre tow 10, is fed over a support 12 in the direction indicated. For the sake of simplicity, the filamenary material will be hereinafter referred to as tow. The tow generally moves at a rapid rate, for example, about 6 metres per second, but, of course, the speed may be much slower or much faster. Support 12 may be placed in a convenient position anywhere along the path of the crimped tow.
A stroboscope 14 is positioned adjacent the band of tow 10 so as to illuminate a portion of the tow 10 as is passes over the support 12. The stroboscope 14 is positioned at an angle relative to the direction of movement of the tow 10, as shown in Figure 1, to create a pattern of alternate light and dark strips on the tow as described hereinafter. A television camera 16 is placed in dose proximity to the strobscope 14 in a manner such that the pattern of light and dark strips created by the light on the crimped tow is in its field of view. Preferably, the camera 1 6 is aimed substantially directly at a generally linear section of the tow some 10 cms. x 1 5 cms.Also, the stroboscope 14 is directed toward the tow at an angle such that the rays of light are substantially parallel to the tow sections 42 at the maximum anticipated crimp angle.
As shown in the diagram of Figure 3, the television camera 16, the synchronization pulse of which is controlled by a pulse generator 18, feeds its video signal into a video analyzer system 60. The electrical signal from the video analyzer is fed to a television monitor 24 and preferably to a filter 23 prior to being fed to a limiting circuit 79 which reshapes the waveform, then through a polarity inverter 29 which feeds square wave impulses into a computer 28. The computer 28 is preferably connected to a print-out machine 30.
Coordination of the television camera 1 6 and stroboscope 14 is maintained by the pulse generator 1 8.
Figures 2b and 2c are diagrammatic sketches illustrating in somewhat simplfied form the section of tow shown in Figure 2a. Figure 2b illustrates the principles involved in creating light and dark strips on a section of tow by directing a beam of light at an angle to the path of the tow.
Preferably, the beam of light is collimated in at least one plane, i.e., the plane of the paper. Light from the direction illustrated by the arrow creates light strips 40 and dark strips or shadows 42 on the crimped tow 10. These alternating light strips 40 and dark strips 42 are detected by the television camera 1 6 and appear in the video signal developed by the camera 1 6. Also, the width 43 and 45 of the strips which appear in
Figure 2c, for a predetermined crimp size, is a function of crimp angle 47 which can be determined mathematicaily by the computer.
In practice, crimped tow normally will not have sharply defined angles and absolutely flat sections from the angles. The light would thus be directed substantially parallel the side 42 sloping away from the light, i.e., parallel to a line 49.
Figures 2b to 2g illustrate the relationship between the width of the light and dark strips and the crimp angle. Figures 2b and 2c illustrate the case where the light rays (arrow) are parallel to side 42′ which is at the maximum anticipated
crimp angle 47′. Figures 2dand 2e illustrate a slightly decreased angle 47″ which causes the light strips 40″ to be smaller and dark areas 42″ to be larger because of the shadow 51 cast on side 40′. In Figures 2f and 2g, the angle 47″‘ has decreased even more, casting a longer shadow 51, thus making the light strips 40″‘ even smaller and the dark strips 42″‘ even larger. A direct relationship exists between the number of strips for a given length of tow and crimp count, and a direct relationship exists between the width of dark strip relative to width of light strip and the crimp angle.Such relationships may be programmed on a computer for obtaining numerical data.
The number of alternating light strips and shodow strips per unit length, and the relative width of such strips is therefore transformed into a video signal for analysis.
The video signal from the television camera is processed by a system shown diagrammatically in
Figure 3. The television camera 1 6 is synchronized
as to frame rate and scanning rate by pulse generator 1 8. The vertical synchronization pulse from the generator is used to trigger the
stroboscopic light source so that at the beginning
of each field scan, a pulse of light is triggered to
illuminate the tow. The reflected light passes through the camera lens and is imaged on a sensitive videocon tube and is stored in the tube to be read out by the scanning electron beam which generates the video signal.Because of the extremely short pulse of the strobscopic source for example, of the order of 1 106, the image stored on the tube is not blurred due to movement of the tow i.e. the tow movement is substantially frozen. The video signal from camera 16 is transferred to video analyzer 60 where a selected group of luminance signals along a line perpendicular to the scanning lines of the picture are analyzed and presented as a slow scan video signal. A composite picture of the full television frame with an added graphic display of the slow scan video signal is shown on a television monitor 24. The slow scan television signal (e.g. about 525 lines and about 30 frames per second) is fed to a limiting circuit 79 and converted to a square wave representation of the signal in which frequency is converted to pulse rate and wave length to pulse duty cycle.These pulses are analyzed for frequency and duty cycle by a computer 28 which calculates the crimp frequency (or count) and crimp angle, and presents it as a printout on the printer 30.
A system for processing the video signal is shown in Figure 4. The video signal is fed to a video analyzer system 60 where it is displayed on a kinescope monitor 66 whilst selected parts thereof are simultaneously displayed as a line also on the kinescope monitor and fed through a filter to an analog signal comparator system. The output signal from video analyzer system 60,
having the simulated waveform illustrated in
Figure 4, is filtered and shaped, generally into the form illustrated, so that it is suitable for feeding into a digital computer (not shown). Pulses from the analog signal comparator system are fed to the digital computer which is programmed to arrange them into useful information using pulse frequency and pulse widths.
It is preferred in most instances to display the video signal on the kinescope monitor 66.
Obviously however, such display is not necessary for processing the video signal to be fed into a digital computer.
The video signal produced by a standard television camera is an electrical signal characterized by a content of electrical alternating wave frequencies ranging from 30 hertz to as high as 35 megahertz. The amplitude of the waves contained within this band of frequencies defines the brightness of the portion of the television picture associated with the wave. The frequency defines the size of the picture element associated with the wave portion. High amplitudes represent bright picture elements. High frequencies represent small picture elements.
In digital analysis of a picture, the brightness of the image can be reduced to a binary number in which presence of a signal above a minimum level represents a shadow being present, and lack of such a shadow is represented by a signal which falls below the minimum level. In digital logic parlance, presence of a shadow is defined as a 1.
Absence of a shadow is defined as zero.
Simplification of the signal description relative ta amplitude conditions to a 1 or zero state makes possible the elimination of complicated electronic circuits for handling the wide range of signals which are required to synthesize a complex wave form which would normally describe the presence of a shadow.
The operation of the video analyzer system 60, which is designed to convert the video signal received from a standard television camera into a waveform suitable for being introduced into an analog signal comparator system or limiting circuit 79, may be described as follows.
The video signal 61 from the television camera 16 is applied through a suitable electrical input terminal means 62 to the first input terminal 63 af a NOR gate 64. The output of the NOR gate is electrically connected to the input terminal 65 of the kinescope monitor system 66. Thus, so long as no control signal is present at the second input terminal 67 of the NOR gate 64, the video signal 61 applied to terminal 63 is passed through the gate to and is displayed on the kenescope monitor 66.
The video signal 61 from the television camera is also simultaneously applied via via input terminal means 62 to the input terminal 68 of a suitable horizontal synchronization pulse separator circuit 69. Each horizontal synchronization pulse contained in the video signal 61 is detected by this circuit and, after being suitably reshaped, is applied as a trigger pulse from the output of circuit 69 to the input terminal 70 of a synchronization pulse timer circuit 71. Circuits 69 and 71 may be contained in a single unit, if desired.
The trigger pulse from circuit 69 starts the running of the synchronization pulse timer circuit 71, which is designed to produce a single control pulse at its output terminal of a predetermined duration for each trigger pulse received. An adjustable potentiometer 72 is electrically connected to circuit 71 and is used to adjust the point in time when the leading edge of the control pulse appears on the output terminal of the circuit
in relationship to the time at which the leading edge
of the trigger pulse appeared at the input terminal
70 of the circuit.
The first input terminal 73 of an AND gate 74 is
electrically connected directly to the input
terminal 62. The second input terminal 75 of the
AND gate 74, as well as the second input terminal
67 of NOR gate 64, is electrically connected to the
output terminal of the synchronization pulse timer
circuit 71. Preferably, an amplifier circuit 77 is
employed. If amplifier circuit 77 is used, the input
terminal 76 of amplifier circuit 77 is also
electrically connected to the output terminal of
circuit 71.
As the leading edge of the control pulse from the synchronization pulse timer circuit 71 appears
on the second input terminal 67 of NOR gate 64, it turns this gate off thereby removing the video signal from the kinescope monitor circuit 66.
Simultaneously, the leading edge of the control appears at the input terminal 76 of the amplifier circuit 77 wherein it is processed and applied through the output terminal of this circuit to the input terminal 65 of the kinescope monitor 66.
This results in part of a vertical line being produced on the face of the kinescope which is the width of the control pulse and is positioned on the kinescope face in accordance with the time when the control pulse is generated in reference to the horizontal synchronization pulse. Once the trailing edge of the control pulse passes, the NOR gate 64 is turned back on and the output from amplifier circuit 76 terminates.
When the leading edge of the control pulse from the synchronization pulse timer circuit 71 is applied to the second input terminal 75 of AND gate 74, the gate is turned on thereby passing the video signal from input terminal 62 to the output terminal 78 of the video analyzer system 60. This passing of the video signal through AND gate 74 will continue so long as the control pulse is present at input terminal 75.
As will be appreciated, through the use of this
video analyzer system, the face of the kinescope
monitor circuit will display the picture being picked up by the television camera plus a vertical
line that represents the position and portion of the
video signal that is being passed through the AND
gate 74 to the analog signal comparator circuit or
limiting circuit 79. Thus, a line selection is
provided wherein one sample of a predetermined
width is taken at a preselected point in each
horizontal sweep line of the kinescope. This
sample, combined with the others so taken, forms
a vertical line or row. The preselected point at
which the samples are taken, and therefore the
position of the vertical line formed by the samples,
can be electrically positioned to any point on the
kinescope face by adjusting potentiometer 72.The
sampled output appearing at output terminal 78
of the video analyzer system 60 is in a form
suitable for being fed directly into the analog
signal comparator circuit 79.
Video analyzer systems, described generally above, are commercially available. For example,
Video Analyzer 301 and Video Analyzer 302 are
available from Colorado Video, Incorporated, of
Boulder, Colorado, United States of America.
In the processing of television signals derived from a monitor system, signals may be produced
by the presence of areas of light and dark due to the shadowing illumination produced by a fight source positioned to reveal the presence of
crimp folds by low angle illumination. As a result
of poor illumination uniformity, areas of light and
dark may be present in the picture area, and these
areas produce signals which add algebraically to
the desired signal produced by the crimp to
produce excursions in signal level which are
frequently greater than the amplitude of the signal
produced by the crimp pattern. The excessively
strong signal may overpower any threshold
devices which may be inserted into the signal
processing chain to establish a baseline for the
normal alternating wave pattern produced by a
crimp pattern.The wide excursions caused by
unwanted signal will drive a composite television
signal (consisting of video and synchronization
pulses) past the threshold level, resulting in a
condition where the desired signal is either above
or below the threshold level and unavailable for
analysis since the function of the threshold device
is to clip or limit the normal alternating wave form
so that it possesses a square wave or pulse form
after processing. The net effect of the additional
excursion in the wave form is to push the desired
information past the threshold limits, thereby
wiDing out the desired signal information.
The video signal may be processed to remove
the synchronization signals, then to remove the interfering low frequency signals because of
uneven illumination of the picture and uneven
response from the television camera sensitive
camera tube. These synchronization and interfering low frequency signals (about 30 Hz to about 300 Hz) may be removed by filters. A suitable filter includes apparatus for removing low frequency signals by summing their integral with the original input signal. An integrator is adjusted to follow the excursions of undesired low frequency signals but not the faster excursions of the desired signal. The algebraic sum of the
integrator output and the input signal contains only the desired signal since the amplitude of signal left after the sum of the integral and input signal is completed contains a negligible amount of the undesired signal.The system perfects the television signal for further processing by counters and computers, thereby making a television crimp monitor system reliable and feasible in cost. A filter for removing low frequency signals is described in Fig. 5.
The video signal taken from the output terminal 78 of the video analyzer system 60, representing a slow-scan video signal showing the luminosity of points sampled along a vertical line which intersects each of the scanning lines of the video picture, is fed through the filter mentioned above and into the analog signal comparator circuit 79.
The video signal is fed through a resistor 80 to an analog signal comparator 81. The comparator (type LM 311 manufactured by Intersil
Corporation) delivers a digitized signal only if the introduced signal exceeds the level of a threshold voltage taken from a power source, such as shown by variable potentiometer 82. A direct current power supply 83, which also serves as the source for the comparator circuit, supplies the potentiometer. A feedback loop including a resistor 84 connects the output of comparator 81 to the input. This resistor defines the sensitivity of the comparator to signal differences.
A portion of the video signal electrically applied to the analog signal comparator circuit 79 is illustrated at 85. The threshold voltage set by the adjustment of potentiometer 82 is indicated by a broken line 86. Signals of varying strengths which represent various light and dark areas viewed by the television camera are depicted as pulses 87 to 89. The amplitude of these pulses varies depending on the brightness of the target being viewed while the width of the pulse is proportional to the duration of the target in that part of the camera’s viewing area.
When the leading edge of a pulse, such as pulse 87, rises above the threshold voltage setting 86, the analog signal comparator circuit 79 is turned on and produces the leading edge of an output pulse, such as pulse 87′. When the trailing edge of the pulse 87 falls below the threshold voltage setting, the analog signal comparator circuit 79 is turned off thereby terminating pulse 87′. This pulse generating process is repeated with each video signal pulse in pulse train 85 that exceeds the predetermined setting of the threshold voltage level 86.
As will be apparent, video input pulses that do not exceed this threshold voltage level, such as pulse 88, will not activate or turn on the analog signal comparator circuit 79 and thus will not appear in the output pulse train.
Pulses from the analog signal comparator circuit 79 are then fed in a conventional manner to a digital computer, which uses the count and width of the pulses to provide numerical information on the irregularities contained within a mass moving through the television camera’a field of view.
The square wave signal produced as described above, or by other means such as amplification in a limiter amplifier to the point where wave squaring is effected, or by shaping in a diode clipping circuit, is well suited for introduction to the input system of conventional electronic digital counters such as the series manufactured by the
Hewlett-Packard Company and marketed under the series number 5300. The square wave produced by analog signal comparator 79 is introduced to the counter. The counter registers one count of each square wave introduced to it.
The total count over a count of 4000 sample scans is found to agree with that produced by a digital computer supplied with the same signal.
Figure 5 shows a filtering circuit that can be
used in the apparatus and method of this invention. The filtering circuit comprises means for eliminating certain signals which interfere with the useful signals. These interference signals include (a) synchronizing signals which have a polarity such that they increase in amplitude from a zero signal level in a negative polarity, opposite that of the useful signals, and (b) signals having a relatively low frequency compared to the useful signals which are usually caused by shadows larger than the light and shadowed strips representing surface irregularities. The low frequency signals are characterized by having a waveform which rarely reverses in polarity over the time period described in a single television picture field in a system having a 60 Hz field rate.
The interfering synchronizing signals, i.e., those which synchronize the television picture as it is scanned by both the television camera and the television monitor, may conveniently be removed by passing the composite signal through an operational amplifier 100 biased to cut off thereby failing to amplify the negative signals. Amplifier 100 thus removes the synchronization signal from the composite signal, leaving only the useful signal and any interference (relatively low frequency) signals which may be present. These remaining signals are fed through capacitor 1 58 to remove any DC signals which may be present, and into an operational amplifier 102 which is designed algebraically to sum these remaining signals with the integrated signal output from this amplifier.The output from amplifier 102 is fed into amplifier 104, which is arranged to integrate the signal fed into it as a function of time. The output of amplifier 104 is then fed through amplifier 106 which has unity amplification, but has 1 800 phase or polarity reversal relationship with the signal from amplifier 104. The output of amplifier 106 is then fed back into second input of amplifier 102. The signal fed back into amplifier 102 is therefore polarized oppositely to the signal fed to the first input. The output from amplifier 1 02 thus consists of the difference between the integrated signal output of amplifier 102 and the interference signals which are fed into the second input of amplifier 102.
If amplifier 104 should be arranged such that its integration rate was short enough to complete the integration of each signal excursion passed to its input, the output of amplifier 104 would follow these excursions exactly, with polarity reversal, and the polarity-corrected input to amplifier 102 via amplifier 106 would add with the input to amplifier 102 from the initial signal source to produce an output of zero. Amplifier 104, however, is designed to have an integration rate which is too slow to follow the excursions of the useful signal, but fast enough to follow the excursions of the interference signals, which normally have excursions with a rate of change of approximately one-fourth to one-tenth of the useful signal.This results in the rapidly varying excursions of the useful signal not being followed by the integration of amplifier 104, and the output of this amplifier fails to contain the integral of the useful signal. When this integrated signal ouput is fed to amplifier 102, the algebraic sum of it and the composite of useful and interference signals – leaves the useful signal with an amplitude above zero
while the interference signal terms are near zero.
The useful signal term is therefore present in the
output of amplifier 102 in considerable strength,
while the interference signals have been reduced
to a point where they are insignificant by the
amplifying effect of the integrating amplifier 104.
The useful signal is raised above the interference
signal so that by minimal amplification through
amplifier 108, the useful signal may be employed for analysis.
The useful signal is then directed from the
output of amplifier 108 to the input of an
operational amplifier 81 used as a voltage comparator. The signal is compared with a steady
DC signal by an algebraic summing process.
Amplifier 81 is designed to produce its maximum output signalAthe useful signal is greater than the DC signal. If the output signal is less, the amplifier produces no signal output.
In detail, the video signal taken from the video analyzer system, representing a slow-scan video signal showing the luminosity of points sampled along a vertical line which intersects each of the scanning lines of the video picture, is fed through the filter described above and into the analog signal comparator circuit. The filtered video signal is then fed to an analog signal comparator 81 similar to that described in relation to Fig. 4.
Suitable feedback resistors 84, 120, 130, 136 and 154 are provided at amplifiers 81, 100, 102, 106 and 108 respectively. Capacitor 160 is provided at amplifier 104 to set the integration rate to correspond with a rate of 30 frames per second and 525 lines interlaced scanning.
Amplifier 1 64 serves as a polarity inverter for the signal coming from amplifier 1 62.
Typicai specifications for electrical components shown in the drawing are as follows:
Capacitor- Size
156 0.5,us 158 0.05 clef 160 0.0005,us Resistor Size
80 1K
82 1K
84 3.9K
114 10K
116 1K
120 20K
Resistor Size
122 10K
124 10K
130 10K
132 .800 ohm
134 500 ohm
136 10K
138 10K
140 10K
142 1K
144 1K
146 10K
148 1K
150 100K
152 10K
154 100K
Amplifiers Type
81 LM311,productof Signetics, Inc.
100 RCA3130
102 RCA3130
104 RCA3130
106 RCA 3130
108 RCA 3130 1 62 transistor-transistor-logic
7404 series of integrated
circuits 1 64 transistor-transistor-logic 7404 series of integrated
circuits
in the table, K represents 1000 ohms, and ,uf represents microfarads.
Pulses from the analog signal comparator circuit are then fed in a conventional manner to a digital computer, which uses the pulse width and frequency to provide numerical information on irregularities contained within a mass moving through the television camera’s field of view.
In addition to the simplified means of producing a signal suitable for introduction to a computer, an analog-to-digital converter system which translates the gray scale of the video image into a digital code and stores it in the computer memory may be used. Once in memory, the computer is programmed to accept digital codes representing a level above the threshold established, and to
reject those codes representing levels below the threshold. A count of the acceptable codes is made and the time during which the code is received recorded. One count is recorded for each time the code is received. The count is’ distributed in the record according to the time duration of the code received. A single video frame representing
1/30 second of time is digitized by the analog to digital converter and entered into the computer memory.
This invention will be further illustrated by the following example although it will be understood that this example is included merely for purposes of illustration and is not intended to limit the scope of the invention.
EXAMPLE
A Cohu television camera type 4400 is installed over a running tow line in which crimp is present in the tow. A General Radio stroboscopic lamp accepting the 60 Hz vertical synchronization pulses from a Cohu television synchronization generator is installed to illuminate the area of tow covered by the camera lens. A Colorado Video Model 301 video analyzer is supplied with video signal from the camera and, in turn, supplies a composite video picture signal and a slow scan signal to a 1 4-inch television monitor. The slow scan video signal is also supplied to a system consisting of an operational amplifier with a gain of lOX, feeding into a high pass filter with a roll-off beginning at 400 Hz, decreasing to 200 Hz (50% response) to 60 Hz (5% response). The output of this filter is again amplified with an operational amplifier (gain
lOX) and the output supplied to a type LM 311 operational amplifier comparator adjusted in circuit parameters to serve as a limiter and square wave shaping device. The output of this limiter is supplied to TTL gates and from these gates to a
microprocessor programmed to determine the crimp count and crimp angle. The microprocessor supplies signals to a printer for hardcopy printout of the processed crimp information. The system is found to produce reliable crimp information concerning the tow running under the television camera. It is found that a large degree of random crimp is present in the tow. Upon departure from normal standard crimp conditions, the alarm system incorporated in the microprocessor is activated to produce a lamp and audio alarm to the operator.

Claims (15)

1. Apparatus, for inspecting elongate material such as strands, sheets, bundles, webs or the like arranged to move along an inspection path forth presence of surface irregularities, which apparatus comprises optical devices and electrical circuitry including a stroboscopic light source positioned above the path to illuminate the elongate material, a television camera arranged to scan the illuminated material and to generate a video signal for processing in the electronic circuitry to obtain information relative to the irregularities.

2. Apparatus as claimed in Claim 1 further including means for moving the material along a predetermined path including the inspection path, and means for generating an electrical pulse at selected intervals to activate the light source for a predetermined length of time and to trigger the scanning of a frame by the television camera.

3. An apparatus as claimed in Claim 1 or 2 wherein the stroboscopic light source is positioned adjacent the path so as to direct its illumination at an angle relative to the material to cause surface irregularities thereof to make a pattern of light and shadowed areas.

4. An apparatus as claimed in Claim 1, 2 or 3 further including a separator circuit means adapted to produce a control pulse, on its output terminal, of predetermined duration for each horizontal synchronization pulse contained in the video signal produced by the television camera, gate means having a first input terminal to receive the video signal and a second input terminal electrically connected to the output terminal of the separator circuit means, the gate means being adapted to pass the video signal through to its output terminal whenever the control pulse is applied to the second input terminal, comparator means connected to the output terminal of the gate means for converting all pulses of greater than a predetermined amplitude contained within the passed video signal into a digitized signal, and a digital computer arranged to receive the digitized signal.

5. Apparatus according to Claim 4 wherein a second gate having a first input terminal to receive the video signal and a second input terminal connected to the output terminal of the separator circuit means, the second gate means being adapted to pass the video signal through to its output terminal whenever the control pulse is absent from the second input terminal, and a kinescope monitor electrically connected to the output terminal of the second gate means for displaying the video signal.

6. Apparatus according to Claim 5 wherein the output terminal of the separator circuit means is connected to the output terminal of the second gate means whereby the control pulse appears as a vertical line on the kinescope monitor.

7 Apparatus according to Claim 5 or 6 which includes amplifier circuit means for the control pulse being applied to the kinescope monitor.

8. Apparatus according to any preceding Claim which includes a filtering circuit for removing low frequency signal components from the video signal caused by different illumination intensities on’relatively large areas of the elongate material.

9. An apparatus for inspecting elongate material substantially as hereinbefore described with reference to and illustrated in Figs. 1 to 4 or Figs. 1 to 4 as modified by Fig. 5 of the accompanying drawings.

10. A method of inspecting elongate material such as strands, sheets, bundles, webs or the like for surface irregularities comprising the steps of passing the material to be inspected along an inspection path; illuminating the material for a short enough period of time substantially to freeze the movement thereof, imaging the material on a television camera, and analysing the video signal from the camera.

t 1. A method as claimed in Claim 10 wherein the video signal is analysed to provide information as to frequency and size of the irregularities.

12. A method as claimed in Claim 10 or 11 wherein the material to be examined is crimped fibre tow and the video signal is analysed to give information as to crimp count and crimp angle.

13. A method as claimed in Claim 10, 11 or 12 wherein the video signal is converted into a digital signal, is fed to a computer and is compared in a computer with desired parameters of the material.

14. A method as claimed in any of Claims 10 to 13 wherein the video signal is filtered to remove low frequency components thereof.

15. A method of examining elongate material as claimed in Claim 10 and substantially as hereinbefore described.

GB7932278A
1978-09-18
1979-09-18
Inspection of elongate articles for surface irregularities

Withdrawn

GB2032618A
(en)

Applications Claiming Priority (2)

Application Number
Priority Date
Filing Date
Title

US05/943,511

US4232336A
(en)

1978-09-18
1978-09-18
Inspection of elongated material

US05/943,510

US4240110A
(en)

1978-09-18
1978-09-18
Inspection of elongated material

Publications (1)

Publication Number
Publication Date

GB2032618A
true

GB2032618A
(en)

1980-05-08

Family
ID=27130180
Family Applications (1)

Application Number
Title
Priority Date
Filing Date

GB7932278A
Withdrawn

GB2032618A
(en)

1978-09-18
1979-09-18
Inspection of elongate articles for surface irregularities

Country Status (2)

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Link

DE
(1)

DE2937245A1
(en)

GB
(1)

GB2032618A
(en)

Cited By (17)

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Priority date
Publication date
Assignee
Title

GB2136954A
(en)

1980-06-26
1984-09-26
Diffracto Ltd
Optical measurement system

GB2144219A
(en)

1983-07-16
1985-02-27
Leicester Polytechnic
Inspecting textile products

US4637054A
(en)

1983-11-23
1987-01-13
Kearney & Trecker Marwin Limited
Inspecting articles

US4744035A
(en)

1983-07-16
1988-05-10
National Research Development Corporation
Inspecting textile products

FR2609058A1
(en)

1986-12-24
1988-07-01
Truetzschler & Co

METHOD AND EQUIPMENT FOR DETECTING FOREIGN BODIES, SUCH AS FOREIGN FIBERS, BONDING YARNS, PLASTIC RIBBONS, METAL OR OTHER YARNS, IN OR BETWEEN TEXTILE FIBERS

GB2203174A
(en)

1987-02-05
1988-10-12
Truetzschler & Co
Apparatus and method for detecting foreign bodies, inside or between textile fibre flocks

FR2621599A1
(en)

1987-10-09
1989-04-14
Hollingsworth Gmbh

METHOD AND DEVICE FOR CLEANING AND OPENING A FIBROUS MATERIAL IN THE FORM OF FLAKES, FOR EXAMPLE COTTON

DE3741616A1
(en)

1987-12-09
1989-06-22
Zahoransky Anton Fa
Test device

WO1991005984A1
(en)

1989-10-18
1991-05-02
Iggesund Pulp Fibre Oy Ab
A method and a device for determining the longitudinal direction of wood chips and the like

WO1991005983A1
(en)

1989-10-18
1991-05-02
Iggesund Pulp Fibre Oy Ab
A method and a device for measuring the height of material pieces

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1990-10-09
1992-04-22
Hajime Industries
Surface inspection device

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(en)

1991-03-13
1992-09-23
American Res Corp Virginia
Reflective optical fabric seam detector

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1991-12-13
1993-06-16
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US5566244A
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1993-11-22
1996-10-15
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Method of inspecting a workpiece surface including a picturing system with a shortened focal plane

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1998-04-22
1999-10-28
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Families Citing this family (2)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

DE3027775A1
(en)

1980-07-23
1982-02-04
Eckehardt Dipl.-Chem. 8550 Forchheim Strich
Optical defect testing of fast-moving homogeneous material – using small signal line video camera scanning reflected light

JPS62279931A
(en)

1986-05-29
1987-12-04
レンゴ−株式会社
Defective detector for single-sided corrugated board

1979

1979-09-14
DE
DE19792937245
patent/DE2937245A1/en
not_active
Withdrawn

1979-09-18
GB
GB7932278A
patent/GB2032618A/en
not_active
Withdrawn

Cited By (28)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

GB2136954A
(en)

1980-06-26
1984-09-26
Diffracto Ltd
Optical measurement system

GB2144219A
(en)

1983-07-16
1985-02-27
Leicester Polytechnic
Inspecting textile products

US4744035A
(en)

1983-07-16
1988-05-10
National Research Development Corporation
Inspecting textile products

US4637054A
(en)

1983-11-23
1987-01-13
Kearney & Trecker Marwin Limited
Inspecting articles

US4839943A
(en)

1986-12-24
1989-06-20
Trutzschler Gmbh & Co. Kg
Apparatus for detecting foreign bodies in a fiber tuft mass

FR2609058A1
(en)

1986-12-24
1988-07-01
Truetzschler & Co

METHOD AND EQUIPMENT FOR DETECTING FOREIGN BODIES, SUCH AS FOREIGN FIBERS, BONDING YARNS, PLASTIC RIBBONS, METAL OR OTHER YARNS, IN OR BETWEEN TEXTILE FIBERS

GB2200374A
(en)

1986-12-24
1988-08-03
Truetzschler & Co
Method and apparatus for identifying foreign bodies inside or between textile fibre flocks

GB2200374B
(en)

1986-12-24
1990-08-08
Truetzschler Gmbh & Co Kg
Method and apparatus for identifying foreign bodies inside or between textile fibre flocks

GB2203174A
(en)

1987-02-05
1988-10-12
Truetzschler & Co
Apparatus and method for detecting foreign bodies, inside or between textile fibre flocks

GB2203174B
(en)

1987-02-05
1990-10-24
Truetzschler Gmbh & Co Kg
Apparatus and method for detecting foreign bodies inside or between textile fibre flocks

GB2210907A
(en)

1987-10-09
1989-06-21
Hollingsworth Gmbh
Controlling cleaning and opening fibres

FR2621599A1
(en)

1987-10-09
1989-04-14
Hollingsworth Gmbh

METHOD AND DEVICE FOR CLEANING AND OPENING A FIBROUS MATERIAL IN THE FORM OF FLAKES, FOR EXAMPLE COTTON

GB2210907B
(en)

1987-10-09
1991-10-16
Hollingsworth Gmbh
Process and apparatus for cleaning and opening loose fibre stock

DE3741616A1
(en)

1987-12-09
1989-06-22
Zahoransky Anton Fa
Test device

DE3741616C2
(en)

1987-12-09
1998-05-07
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Test device for the final inspection of brushes, especially toothbrushes

WO1991005983A1
(en)

1989-10-18
1991-05-02
Iggesund Pulp Fibre Oy Ab
A method and a device for measuring the height of material pieces

WO1991005984A1
(en)

1989-10-18
1991-05-02
Iggesund Pulp Fibre Oy Ab
A method and a device for determining the longitudinal direction of wood chips and the like

GB2248935A
(en)

1990-10-09
1992-04-22
Hajime Industries
Surface inspection device

GB2253903A
(en)

1991-03-13
1992-09-23
American Res Corp Virginia
Reflective optical fabric seam detector

GB2253903B
(en)

1991-03-13
1995-01-04
American Res Corp Virginia
Optical imaging system for fabric seam detection

GB2262339A
(en)

1991-12-13
1993-06-16
Honda Motor Co Ltd
Method of inspecting the surface of a workpiece

US5379347A
(en)

1991-12-13
1995-01-03
Honda Giken Kogyo Kabushiki Kaisha
Method of inspecting the surface of a workpiece

GB2262339B
(en)

1991-12-13
1995-09-06
Honda Motor Co Ltd
Method of inspecting the surface of a workpiece

US5566244A
(en)

1993-11-22
1996-10-15
Honda Giken Kogyo Kabushiki Kaisha
Method of inspecting a workpiece surface including a picturing system with a shortened focal plane

DE19818069A1
(en)

1998-04-22
1999-10-28
Rieter Ag Maschf
System to register optical characteristics of yarn

WO2001007352A1
(en)

1999-07-21
2001-02-01
Regis Munoz
Device for observing and controlling one or more textile yarns by a succession of numerical photographs

CN111356556A
(en)

2017-09-28
2020-06-30
圣戈班磨料磨具公司
Abrasive article and method of forming the same

CN111356556B
(en)

2017-09-28
2022-06-07
圣戈班磨料磨具有限公司
Abrasive article and method of forming the same

Also Published As

Publication number
Publication date

DE2937245A1
(en)

1980-03-27

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