CA1327637C - Pulsed-array video inspection lighting system - Google Patents
Pulsed-array video inspection lighting systemInfo
- Publication number
- CA1327637C CA1327637C CA000608413A CA608413A CA1327637C CA 1327637 C CA1327637 C CA 1327637C CA 000608413 A CA000608413 A CA 000608413A CA 608413 A CA608413 A CA 608413A CA 1327637 C CA1327637 C CA 1327637C
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- Prior art keywords
- light
- lighting
- array
- primary
- elements
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- 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
-
- 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
- G01N21/8806—Specially adapted optical and illumination features
-
- 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
- G01N2021/845—Objects on a conveyor
- G01N2021/8455—Objects on a conveyor and using position detectors
-
- 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
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
- G01N2021/8887—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges based on image processing techniques
-
- 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
- G01N21/90—Investigating the presence of flaws or contamination in a container or its contents
- G01N21/909—Investigating the presence of flaws or contamination in a container or its contents in opaque containers or opaque container parts, e.g. cans, tins, caps, labels
-
- 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
- G01N2201/06—Illumination; Optics
- G01N2201/061—Sources
- G01N2201/06146—Multisources for homogeneisation, as well sequential as simultaneous operation
- G01N2201/06153—Multisources for homogeneisation, as well sequential as simultaneous operation the sources being LED's
-
- 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
- G01N2201/10—Scanning
- G01N2201/102—Video camera
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- Physics & Mathematics (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)
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Abstract
PULSED-ARRAY VIDEO INSPECTION LIGHTING SYSTEM
Abstract of the Disclosure An engineered lighting system for use in an inspection system is comprised of an array of light emitting diodes.
A specimen is brought into the viewing area, and a current pulse is provided to the diodes of the array to selectively flash all or a portion of the diodes of the array. Reflected light from the specimen is sensed and a digitized image is generated therefrom. An illumination level of the digitized image is adjustable, in whole or in part, by varying the effective lighting intensity of one or more of the diodes of the array during a flash period. The digitized image of the specimen is compared to data indicative of acceptability of the specimen, and acceptance or rejection of the specimen is decided on a basis of a comparison therebetween.
Abstract of the Disclosure An engineered lighting system for use in an inspection system is comprised of an array of light emitting diodes.
A specimen is brought into the viewing area, and a current pulse is provided to the diodes of the array to selectively flash all or a portion of the diodes of the array. Reflected light from the specimen is sensed and a digitized image is generated therefrom. An illumination level of the digitized image is adjustable, in whole or in part, by varying the effective lighting intensity of one or more of the diodes of the array during a flash period. The digitized image of the specimen is compared to data indicative of acceptability of the specimen, and acceptance or rejection of the specimen is decided on a basis of a comparison therebetween.
Description
PULSED--ARRAY VIDEO INSPECTION LIGHTING SYSTEM
Backaround of the Invention This application pertains to the art of engineered lighting systems, and more particularly to engineered - lighting systems for lighting of specimens in an inspection environment The invention is particularly applicable to video inspection apparatuses and will be described with particular raference ~her~to, although it will be appreciated that the invention ha~ broadQr application~ such as lighting of specimens in any lnspection or computQr vi~ion system Machine visiQn sy~tQms are obtaining increasing æignificance in industry to aid in robotic assembly systems as well as inspection system~ for quality control Such mac~ine vision systems are g-nerally comprised of a lighting system to light a spocimen and a camera for sensing light reflect-d thorefrom A digitized image is formed from an image roceived by the camera The data of this image is then a~ail~ble for use in controlling a robot arm, identifying the specimen, or detormining whether the specimen is acceptable to specified standard~ Tho ability to govern operations in accordanc~ ~ith ~n in~pected specimen ~8 dictatad by the guality of the digitized image ~arly attQ~pts on i~proving t~Q accuracy of image data w~re dir~ct d to improvQ~m nts in d ~era~ and performance of algorithms on captur~d imag~ data, in an effort to improve int~grity, contrast, or resolution t~ereof Little ~mphasis wao plac d on the lighting systems, which, in a typical video inspection systQ~, ~ore co~prised of inert gas strobe lamps, such as x non strob~8, partlcularly when specimens are in motion rol~tivo to the vidoo camera For non-moving ~p~ci~ n~, co~on st-ady-state light sources s ~ h as ` 1 327637 fluorescent, quartz-halogen, incandescent, or the like, are typically used.
Such video lighting systems are plagued by a variety of problems. Placement of a single lamp over a specimen which includes a reflective ~urface often causes an image of the strobe lamp itæelf to be transmitted to an inspection device. Strobe lamps were also relatively expensive, varied in intensity from -~
flash to flas~, and tended to degrade over a period of lo time, thereby resulting in lessened resolution of a resultant video image. In applications in which many ~undreds or thousands of inspections per minute are required, in addition to poor lighting characteristics, the strobes also require regular replacement, which resulted in additional down time of the entire inspection apparatus.
The present invention contemplates a new and i~proved ~pparatus and method for lighting of a specimen in a video inspection environment which overcomes all t~ above-rQferred problems and others, and provides a video inspection lig~ting syste~ with increased re~olution and longitivity.
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In accordance with an aspect of the present invention, there is provided an array of directed light e~itting elements which are secured to direct light eaitted t~erefrom to a light field.
In accordance with a more limited aspect of the ` -present invention, a diffuser plate ~lends the light eoitted from various elements of the array and thereby serves to form a light field having an increased -~
unifor~ity of light intensity thereover. -In accordance with a more limited aspect of the inYention~ the light emitting elements are comprised of `~
electric, soli~ state devices, such as LED's.
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In accordance with a still more limited aspect of ~` ` the invention, the array of LED's is shaped.
In accordance with another aspect of the present invention, a second array of light emitting elements is implemented to provide light to a specimen at a different angle to the specimen as co~pared to the light provided by the primary array.
In accordance with another aspect of the present invention, there is provided a method of lighting a lo specimen in an inspection environment which implements the above-structure.
In accordance with still another aspect of the present invention, effective intensities of various elQments of the array may be selectively varied.
lS An adv~ntage of an aspsct of the present system i8 that a lighting system is provided with increased resolution in a resultant image of an illuminated ~pecimen.
An advantage of an aQpect of the present invention 20 i8 the provision of a configured lighting array which `~
provides evenness-of-illumination; contrast over a vie~Qd ob~ect's surfac~ appear when light refleoted ~herefro~ i8 ~ocusQd at a viewing location.
An advantage of an a~pect of the present system i8 the provision of a lighting 8y~tem with increased longitivity of the lighting elements.
An advantage of an aspect of the present invention i8 tho provision of a video inspection apparatus wherein increased accuracy and resolution of an inspection process may be realized inexpensively by selectively varying a lighting of a speoimen to be inspeoted.
An advantage oX an aspeot of the present invention ~:
i- the provision of a system which provide both on-line ~-~
and off-line ad~ust~ent of a lighting system scheme by 35 soleotively varying aotivation of elements of an array. ~ -; :
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Further advantages will be apparent to those of ordinary skill in the art upon reading and understanding of the subject specification.
- Summary Of The Invention Other aspects of this invention are as follows:
An engineered inspection lighting system comprlsing:
a plurality of directed primary light generating elements directed to a primary light field;
means for securing the primary light generating elaments in a preselected array arrangement to form a primary lighting array;
means adapted for directing light from the primary light generating elements to the primary light field; . -supply means for providing a single current pulse to ..
selected light generating elements of the primary lighting array to illuminate an associated specimen :
within the primary light field; and -the primary light field including a plurality of sections, the primary light generating elements being positioned in the primary lighting array such that each ~..... -primary light generating element thereof does not contribute light equally to each section of the primary light field and wherein light in the light field from at 25 least a portion of the light generating elements of the ;.:
~rray is overlapped with light from neighbouring light ~
gonerating elements of the array.
An inspoction systom comprising~
a plurality of directed primary light generating ~0 oloments;
means for securing the primary light ganerating elements in a preselected array arrangement to form a :
primary lighting array; i:
moans adapted for directing light from the primary `. ::
3S light generating elQments to a viewing area;
tho ~iewing area including a plurality of soctions, tho primary light generating elements being positioned in the pri~ary lighting array such that each ~g ~
. r ` ~ , } ` : t i - 4a -primary light element thereof does not contribute equally to each section of the viewing area;
supply means for simultaneously providing a current pulse to each of selected of the light generating 5 elements of the primary lighting array such that an associated specimen present in the viewing area will be illuminated solely by one current pulse; and monitor means adapted for sensing reflected light emitted from the primary lighting array after a reflection ~hereof from the associated specimen.
A method of lighting a specimen in an inspection .
system comprising the steps of: .
supplying single current pulse to an array of light generating elements to illuminate an associated specimens;
generating light from each light generating element of the array as a result of the supplying cf current thereto;
generating a primary light field from light from the array, the light field including a plurality of sections in which each lighting element of the array does not contribute egually to an intensity of light in each SQCtiOn;
directing light from the array to a viewing area;
exposing a speci~en to light from the array; sensing li~ht from the array after reflection thereof from the ~peclmen; and generating data indicative of a physical characteristic of the specimen in accordance with sensed light generated by the single current pulse.
An engineered inspection lighting system comprising: .
a plurality of directed lighting elements; securing means . .:
for securing the plurality of lighting elements to be directed to a light field; .
the securing means including means for securing the lighting elements in a preselected array arrangement to form a lighting array;
means adapted for directing light from the lighting . . .
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~ 1 327637 - 4b - -elements to the light field so as to light an associated specimen disposed therein substantially solely by specular illumination; and supply means for selectively providing current to lighting elements of the lighting array to provide a single illumination period to the associated specimen disposed in the light field.
An engineered inspection lighting system comprising: -a plurality of directed lighting elements;
lo means for securing the plurality of lighting elements to be directed to a light field; ~ -the securing means including means for sacuring the lighting elements in a preselected array arrangement to form a lighting array; -means adapted for directing light from the lighting :
elements to the light field;
supply means for se.lectively providing current to ..
lighting elements of the lighting array to provide a single illumination period to an associated specimen :. 0 disposed in the light field;
light sensitive transducer means for generating an electrical signal in accordance with light exposed th~reto;
lens means for focusing light onto the light sensitive transducer means, which light was generated a~
result of currant provided to the selected lighting el~ent~ of the array by the supply means, after exposure th~reof to the associated specimen;
means for generating an image data signal representative of light focused onto the light sensitive tran~ducer means by the lens means; and means for altering the supply means in accordance with the image data signal.
An engineered video inspection system comprising:
a plurality of d.irected lighting elements;
means for securing the plurality of lighting ~lements to be directed to a light field;
means for securing the lighting elements in a - 4c -~ 1 32 7 6 3 7 preselected ar:ray arrangement to form a lighting array;
means adapted for directing light from the lighting elements to the light field;
supply means for selectively providing current to lighting elements of the lighting array to provide a single illumination period to each of a series of associated specimens sequentially disposed in the light field;
transducer means for generating an electrical signal in accordance with light exposed thereto;
a lens means for focusing light onto the light sensitive transducer, which light was generated as a result of current provided to the selected lighting elements of the array by the supply means, after exposure thareof to each of the series of associated specimens;
means for generating a series of image data signals, :~ .
representative of light from each of the series of -associated specimens, focused onto the light sensitive transducer by the lens means; and ~Qans for accumulating acceptability data :
represQntative of acceptability of future associated sp~cimens *ro~ at least a portion of the series of image data signals.
A m~thod of automated video inspection comprising tha steps of:
sQquentially conveying a sequence of specimens to a light fi-ld;
sequentially activating a lighting array to provide a singl~ illumination period for each of the sequence of spQcim~ns to the light field therewith;
focusing light on a light sensitive transducer after each ~xposure thereo* to each of the sequence of ~pecimens;
generating a sequence of image data signals ;.
corresponding to each of the sequence of specimens;
comparing each o~ image data signals to data represQntativQ of acceptability of specimens; and selQctively re~ecting specimens in accordance with -~
.,: .
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` ~ - 4d -- the step of comparing.
. . ~ An apparatus adapted for automated video inspection - with an associated lighting array comprising: ~-means for sequentially conveying a sequence of specimens to a light field;
means for sequentially activating a lighting array to provide a single illumination period for each of the seguence of specimens in the light field;
means for focusing light on a light sensitive transducer after each exposure thereof to each of the sequence of specimens;
means for generating a sequence of image data signals corresponding to each of the sequence of specimens;
means for comparing each of the image data signals to data representative of acceptability of specimens; and means for selectively rejecting specimens in accordance with an output of the means for comparing each of the image data signals.
An apparatus adapted for automated video inspection wit~ an associated lighting array comprising:
means for sequentially conveying a sequence of sipQcimens to a light field with a continuous relative ~otion between the sequence of specimens and a single video camera;
means for sequentially activating a lighting array co~prised of a plurality of light emitting diodes to provide a single illumination period for each of the ~eguence of specimens in the light fiQld;
means for focusing light from the lighting array on t~e siingle video camera after each exposure thereof to -each Or the sequence of specimens;
means for generating a sequence of image data signals corresponding to each of ~he seguence of 35 specimens; .. .
means for comparing each of the image data signals to data representative of acceptability of specimens; and -~
~eans for selectively rejecting specimens in ,'''.':. ,' ~ 1 327637 - 4e -accordance with an output of the means for comparing each of the image data signals;
wherein the lighting array includes a primary array portion of the plurality of light emitting diodes and a secondary array portion of the plurality of light emitting diodes, the primary and secondary array portions differing such that an angle of propagation of light from light emitting diodes of the primary array portion to the light field is different from an angle of propagation of light from elements of ~he secondary to the light field.
Brief Description of the Drawings The invention may take physical form in certain parts and arrangaments of parts, embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part ~ereof and wherein: -FIGURE 1 is a diagram illustrating an embodiment of -:
a video inspection syste~ incorporation an engineered lighting system of the present invention;
FIGURE 2 illustrates two sample specimens for which an engineered lighting system of the present invention is well suited;
FIGURiE 3 is an alternate lighting array of the system of FIGURE l;
FIGURE 4 is yet another alternative array of lighting elements of the system of FIGURE l;
FIGURE 5 (5a - 5c) is a flow chart of gray scale calibration for off-line calibration of a video inspection system of the type of FIGURE l; and :
FIGURE 6 (6a - 6c) is a flow chart of gray scale calibration for on-line calibration of a video inspaction system of the type o~ FIGURE 1.
Detaileq Description of the Preferred Embodiment Referring now to the drawings, wherein the showing :~.
are for the purpose of illustrating the preferred Qmbodiment of the invention only and not for the purpose of limiting the ` ;
;~ ",~.,, ~ 5 - 1327637 same, FIGURE 1 shows a video inspection system including an engineered lighting apparatus A which is controlled by and supplies video information to a proces~or means B.
The engineered lighting apparatus A is comprised of a plurality of light emitting Qlements 10 which are secured in an array by a securing means 12 to form a primary lighting array.
The light emitting elements lo are directed by the securing means 12 to primary light fleld 14 in which not every element of the array contribute~ equally to each SQction thereof. A diffuser plate or means 16 is placed in the light fiald 14 to further diffuse light therefrom to create a viewing area 18 with an increased uniformity thereovQr.
For ~iQwing certain specimens, such as the circular/domed spQcimQn 20 illustrated in the figure, a secondary light source is advantagQous for obtaining increasQd contrast and resolution of the specimen. A
sQcondary light source 26 is illustrated as a ring array of ~econdary light e~itting elements 28. The liqht therefrom i~ directed to the vie~ing area 18 at an angle of travel thereto different from that of the primary array of elements 10. As illu~trated, the light from tha sacondary array propagatos 8UC~ that a co~ponent of direction of travel of light therefro~ is parallel to the plane of the primary array. This i8 particularly suited for the illu~trated specimen 20 as it provide~ for side lighting at an angle perpendicular to the direction of travel from that the primary array of elements 10.
As illustratQd, the elements 10 of the primary array create a diffused lighting for a specimen by means of the dlffuser 14. Specular (non-diffused), directly reflected light, is r sultant on the spocimen by the array of secondary - 6 ~ ~ 1 327 637 light emitting elements 28. It will be appreciated, however, that either diffused or specular lighting from e~ther array is desirable or satisfactory in applications dependent on the object to be viewed and the individual propertie~ thereof.
The preferred embodiment iæ, however, as illustrated in FIGURE 1.
Both the primary light emitting elements 10 and the secondary light elements 28 are preferably comprised of electrically powered solid state lighting devices, such as light Qmitting diodes (nLED'sn), or the like. Focused LED's are preferred as they provide for selective illumination of a controlled portion of the viewing area 18. While it is difficult to obtain light of a suitable intensity from standard electronic lightinq elements driven within their recommended current and voltage levels, in the video inspection environment, only a short viewing time necessary.
Accordingly, drivinq the solid state light element above its standard reco~mended ratings, for a relatively short duration, i~ found to provide suitable illumination without advoræely affecting it. For example, a ~ED device overdriven for a duration in the ranqe of 20-200 microseconds provides adequato illu~in~tion for a sufficient period with virtually no degradation of the elemont.
Although lighting of specimens for analysis in accordance ~ith the present inventi~n may be facilitated with light o~ ono or ~ore wavelengths, not limited to those of the visual spectru~, it has been ~ound that sultable analysis is genorally found ~ith llght o~ generally a single wavelength.
As ~ill be soen bolow, analysls of a specimen is ultimately ~acilitatod on analysis o~ gray scale levels of black and ~hito iaagos, ~hich may sultably be generated by LED's of a single color. For oxnmple, a commonly used red LED is qenerally ad~quato in m~my applications.
..
Light of any particular wave length may be obtained by use of appropriate light emitting elements. For example, ultraviolet or infrared light emitting diodes may be easily - implemented. Combinations of two or more types of LED's may be made to provide for a viewing area compri~ing light from multiple frequencies or wavelenqths. A combination such as redj green, and blue may be implemented to provide wave lengths of the entire visible spectrum, or any sub-combination thereof.
When lighting of viewing area 18 is initiated, light thereof is reflected off of a specimen, located therein, to a monitor means 36. As illustrated, the monitor means 36 is comprised of a lens of a video camera means 38, from which an electronic ~ignal representative of the specimen is obtained fro~ the reflected light. Tbe electronic image ~ignal i8 tran~mitted to an i~age digitizer 40 wherQin a numeric representation of the image is obtained by means of the f~miliar bit ~apped technique. A numeric representation, such as a binary numbar, of a gray scale is accordingly assigned to a representation of each of a plurality of picture ele~ents (npixels~ of a raster scan of the image.
For each pixel, gray scale information is stored in a memory location for future retrie~al and comparison.
Triggering or firin~ of the light emitting elemQnts is selectively fac~litat~d by ~eans of a supply of one or ~ore curr nt pulse~ initiated from a strobe control means 48, ~hich is in turn controlled by central processor unit ("CPU") ~0. . , ' .
The CPU 50 is ~uitably compriQed of a digital computer which operates on a storQd program located in memory 52 which is pre~-rably r~ndo~ acc:ess memory (RAN). The memory 52 is also seqmented into a working buffer region into which data onto which operation~ ar per~oxmed, as WQll as a display ', - 8 _ 1 327637 buffer region which provides image data to an input/output (I/o unit) 54, in a standard bit-mapped graphics fashion, or the like Both the wor~ing buffer and the display buffer are thereby adapted to store image data s Also stored in memory 52 is a digital representation of a presalected image range against which specimen image data may be compared to determine whether a particular specimen is acceptable As will be seen below, this data is both setable and a~terable ~he CPU 50, in operation under-a suitable software routina in the memory 52, facilitatQs comparison of the preselQcted image range data to that data indicative of an examined speci~en By suitable comparison in the CPU 50, a determination of acceptab~lity of the sub~ect SpeCimQn may be ~ade The CPU 50 also intQrfaces with the (I/0) unit 54 The I/0 unit 54 permits display of digitized image data, display of an illuminated ~po¢imen, control of operation of the CPU 50, and modification of a software program in the meoory sa.
Interraced to the CPU 50 is a speed sen~or 56 which providQs a signal indicati~a of a velocity of a conveyor means 58 whi¢h i8 uged to transport a series of specimens 20 to tho vie~ing area 18 The specimens are centerad in a s~locited ori ntation to the conveyor meanQ 58 by a centering ~eans 60 Tho CPU 50 is also interfaced with a sensor means 64 which 8 n~Qs pre~ence of a specimen 20 in the viewing area 18 Ais illustrated, the sensor means 64 i9 comprised of a photos nsitive cell working in con~unction with a light ecittor 66 a pre~ence Or a specimen in the viewinq area r sults in a br akaqe Or light path between the sensor 64 and th- light e-itter 66, ther~by providing a signal indicative . ..
g of an availability of the specimen for illumination and viewing Nhen a specimen 20 has been viewed and digitized image resultant therefrom compared to preselected data parameters, acceptability of the sub~ect specimen is determined by the cPu 50 A control signal is generated to facilitate re~ection of an undesirable specimen by a re~ecting means 68 which i~ illustrated as a plurality of air nozzles The noz~les are oriented so as to remove a specimen 20 from the lo conveyor 58 by mean~ of directed air streams A position of a specimen along the belt 58 is monitored to track the position of speeimens therealong to faeilitate removal by thQ means 68 The positioning may suitably be traeked by means of the speed sensor 56 working in eon~unction with the sensor 64 by aaleulation of travel time from a triggering of th~ sensor 64 to the ra~ecting mQans 68 Of eourse, in sueh an arrangement, the speed sensor would be unneeessary should the eonveyor be driven at a eon~tant Y-loeity by ~eans such as a synchronous a c ~otor In operation, a series of specimen~ 20 travel along the eonveyor 58 As eaeh ;specimen enters the viewing area 18, ~ eurrent pulse is pro~ided under the direction of CPU
50 by strobe eontrol 48, to seleetively pulse the light ~itting le~ents ~or a perlod suitable for obtaining a video imaqa Image data i8 eaptured through th~ monitor means 36 and the video eamera ~ean~ 38, and a digitized image thereof formed by the i~age digitiser 40 The image data i8 stored in memory 52, and eomparQd with pres~lectQd data ~n CPU 50 to detexmine aeeeptability of the speeimen by comparison th reo~ uit~ preseleated parameter data This is acco~plished by the CPU 50 acting in eon~unction with a ~o~tware routine in mQ~ory 52 Any non-eonforming specimen . ~.~.-.
- lo - ~ 1 32 7 6 3 7 is then re~ected by provision of an air ~et from the rejecting means 68.
Turning now to FIGURE 2, three dimen~ional specimens for which vidQo inspection by use of a lighting system as described above is particularly suited is illustrated. The ob~ects illustrated includQ surfaces with directions that are not advantageously illu~inated by a single light source. A
mere planer array of light elements would not illuminate all surfaces evenly, as those surfaces which have a component of direction parallel to the direction of light propagation would there~y appear darker, with the darkness level being proportional to that component. In addition, absent a planar array of relatively unifor~ liqht, those surfaces of the specimen which are parallel to a ~ingle plane of light elements would present a reflection or image of the lighting element itself, and not a visua~ Qignal indicative of the prop~rties of that surface which i8 as ~ignificant as is desirable.
T~e implementation of an L~D array, a~ illustrated in FIGUR~ hieh act~ in con~unction with a CPU control, is particularly suited for manipulations in lighting in accordance uith a ~peci~en und~r review. The CPU is suitably adapted ~or individual, or group, control of ~elected firing of variou- coDblnations or sub-combination~ of light emitting ele~nts of the array. Nith such individual control, ~oft~are modifications of a lighting system are made possible by select~ve control of ~hich light emitting elements are activated at any particular time, and the extent to which they are aeti~ated. Such is ~uitably re~erred to as "dark field~ illumination.
Nhen the light ~mitting elements are comprised of L~D's, an e~fective int~nsity or illumlnation therefrom may be varied not only ~ith fluctuation Or current levels at which the LED's ere driven, but also by variations in the duration during which the LED re~ains on. As the LED's are comprised of those of the focused variety, a relatively small area of an illuminated specimen may be controlled by means of a small grouping in its elements of the array. When a camera is used to create a gray scale image, the brightness level sensed by the camera ~ill be affected as a function of the duration at which the particular light sensitive elements therein are exposed to light. Accordingly, fluctuations in lo effectivQ illumination levels of a particular portion of a specimen may be obtained by varying thQ time during which a ~orresponding LED is aetivated. It is found that a suitable gray scale ad~u~tmant is facilitated by varying the on time of the L~D's from an on duration in the ranqe of 20 microsecond~ to 200 microseconds. The aetual on time of any LED or grouping thereof is controlled by means of the strobe eontrol 48 wor~ing under direetion of the CPU 50.
T~e ability to seleetivQly vary the effective intensity of the LED's, in addition to faeilitating viewing of non-unifor~ surfaees, provides means to allow for closed-loop eorrection of lighting patterns. Should one or more of the ele ents of tha array degradQ over time, the element may be controlled to eo~pensate for this degradation. Also, should one ele ent fail entirely, the e~ective illumination of its neighborlng lQments can be increased to compensate for ~ts los~. Additionally, gradual variations in the ~peci~ens the selves uhich merits eompensation in illuJination levels is possible. Means for aceomplishing such ~ill be described further below.
In illuDinating the ~peeimens of FIGURE 2, a gradual d oping of surfaces ~ay be compen~ated for by increasing ligbt fro~ cer~aln of liqht elem-nts of a shaped (illustrated as planar) array, or alternatively, by triggering the elementi3 of the secondary array Turning to FIGURE 3, an alternate, circular array formed of lighting elements is provided which i3 suitable for illumination of a specimen such as that of FIGURE 2B To facilitate for illumination of such a specimen, the array may have more elements from a perimeter 80 activated Alternatively, those e'ements may either be driven at a higher intenslty level than those of the elements moving toward the center 82 of the array, or illuminated for a longer duration Various lighting levels across a surface of a speciman may thereby be realized Turning to FIGU~E 4, another alternate array of lighting elemQntis ii~ provided which is particularly suited for viewing of a curved ~ur~ace a~ illustrated by the ~pecimens of FI~VR~ 2~ The curved array is shaped similarly to an exterior surface of the ob~ect to be viewed A curved array 86 i~ provlded, whic~ preferably has a similar radius of curvature to that of the spQ¢imen Such an array uses the property of light where an angle of incidence eguals the angle of reflaction A yet ~ore uniform gray scale pattern to vie~ imperfections of the surface is provided when all liqhtinq ela ents, have as a focus for reflected light, ths monitor ~eans 36 As ~ith th~ arr~ys described above, selected groups of liqht e~itting ele~ents fro~ the array of FIGURE 4 may si~ilarly be nabl d or varied, and the ef~e¢tive intensity thereby controlled to facilitate modifications in the lighting patt rn via soft~are control As noted above, the above-described system i9 - particularly suited for the obtaining of a high resolutiondigiti~ d i~age by means of an engineered lighting system ~
The pre~ nt yste~ i- also designsd to ~aintain consistency ~`
.
and quality of analysis by accounting for such factors as variations in lighting due to failure of individual light~ng elements of an array, or deqradation of lighting element~
over an extended period of use Illumination leveli3 also vary due to factors such as metal characteristics and the like Such ~ay result in re~ection of suitable specimens due to gradual trend toward variation from that which was previously within acceptable bounds Accordingly, a continued updating and revision to gray scaled data is lo desirable This may be accomplished either by manipulations of data ln the ~PU, or by variations in the lighting scheme of variouis subisets of elements of the lighting array as taught above Turning to FIGURE 5, with reference again to FIGURE 1, a flow chart iis provided for a routine to be stored in memory 52 (FIGUR~ 1~ for operation of CPU 50 to facilitate variation in gray lev~l readingis fro~ an analyzed specimen by varying the acceptabla intensity lQvels realized from light emitting elementQ of the array The flo~ chart of FIGURE 5 is directed to the off-line or set up qray level calibrations wherein an operator is per~itted to view an i~age of a specimen during set-up, to inltiali~o an illuoination pattern thereof~ The off-line set-up roUtin~ function~ to perfor~i analysis of a series of speci~en~ and oreate an initial gray scalQ level therefrom ~han a pr~el-cted number of con~-cutive Qpecimens fall ~lthin gray ~oale bound~, tha ~et-up is completed When a variation i~ found, the gray scale is ad~usted to account for the variation and the qu-st for the consecut~ve parts is raco~encQd Tho partloulars of this proces~ are as discussed ln the follo~ing routine Nith particular reference to FIGURE Sa, a set-up operatlon i8 commencad at step 100, and hardware to allow - 14 - ` ~ 327637 changes of acceptable gray scale levels i~ enabled. As noted above, such variations in illumination may be accomplished by means of varying the on-time of one or more LED's of the array analogous to the shutter speed control of a camera to vary exposure of various light sensitive element~ of the video camera 38 to reflec~ed light from a specimen 20.
Step 104 zeros a consecutive part~ numb~ring counter which sets thQ number consecutive part~ for which a conclusion of variation must be made to accomplish a gray scale adjustment. A display of the I/O unit s4 interfaced with a working buffer in the memory 52 in step 106. The LED
array is pulsed and a picture is acquired from the camera 38 in step 108 A picture i8 again acquired in step 110, and the digitised image thereof is copied to a display buffer in step 112. ThQ resultant image or picture date is then routed to the display at the V 0 unit 54 from the display buffer, in ~tep 114.
Turning particularly to FIGURE 5b, as a spQcimen's position varie~ within the viewing area 18, in step 116 a position of a part or spQci~en is detected and fixed. After deteotion o~ ~uch a part in ~tep 118, a gray scale level is ~easur d at step 120 and an image resultant therefrom is displayed at step 122. Whon a specimen i~ not located, the procs~s returns to step 106 and proceeds t~erefrom. A test of thi~ i~aga data i~ mada again~t selected parameters~
When thQ gray levol i8 deteroined to be within the preseleot~d bounds at step 12~, the consecutive parts counter i8 incre ented at 1~8. When it i8 determined that the gray level is not within the preselQcted boundQ, an ad~ustment thereo~ i~ ~ade at 12~. In either instance, the system proceads to ~tep 130 wherein the gray level command is tested to deter~lne w~Qther lt i~ too low in.accordance with a presQleoted standard. X~ $t 18 too low, an error signal i~
- 15 - ~327637 generated at 132 and the process i~ aborted at 134. A
negative determination at 130 allows for continuation of the process at 136 (FIGURE 5c). At this step, it is determined whether the gray level command is too high, and if so, a corresponding error display i8 made at 1~0 and the system is exited at 140. If the gray 1QVQ1 i8 acceptablQ, the system PrOCeed8 tO step 142 wherQin the gray level is set.
At step 144, the consecutivQ counter is testQd to see wh~th~r the presQlectad number of consecutive parts fitting lo in thQ preselQctQd gray level have been achievQd. If not, t~Q proc~s-~ i~ repeated from step 106 in a ~imilar fashion as illustratQd above.
Upon achievinq a pre~elected number of consecutive parts within gray 1QVQ1 paramQter~, the gray level ad~ustment hardWarQ i8 disQnablea at 146, the gray level command is displayed on the I/0 unit 54 at 148, and the gray level is saved at stQp 150. At this time, the off-line gray scale ad~ust~Qnt i~ completQd and the system is terminated at 152.
Turning to FIGUR~ 6, with continued reference to FIGUR~ 1, a flow chart for continuous ad~ustment of gray level ~hich is perfor~ed during an actual production inspection (on-line) is disclosed. During testing of a plurality of ~pecimens or pHrt~, slight fluctuatian trends in con~ecu~iv~ part~ of an inspection run may be found due to variation~ in ~tal quality fro~ separate batches, slight variation~ in coating thlc~ne~e~ which are not sutficient to render a speci~en unacceptable, or the like. Such variations ~ay al~o result from degradation of lighting ole~en~-, or froa a complete failure of one or more elements.
~0 The sub~ect sy~tQ~ provides ~or a closed loop ~eedback system which provides for continuous ad~ustment of the brightness level during such an inspection run. When a preselected nu~ber o~ consecutive parts provide a con~istent variation in the gray scale level, a correction is made. Ad~ustment of the light intensity, for axample by varying the duration during which the LED is illuminated, facilitates continuous refinement during an inspection run.
The on-line gray scale calibration i~ commenced at step 200, and a parts counter, which i8 initially zeroed, is incremented at step 20Z. When a part 20 enterq the viewing area 18, the lighting array is triggered and a digitized video image is captured in memory 52. Determination of lo whether a gray level checX i-~ to be taken is made at step 204. An ad~ustmant need no~ be made for each part in a serie~ inspQction. Salected or random checks may be instructed for thi~ purpose. Whan a gray level check is to be made, a level ~easure~ent of a current part or specimen is made at step 206, and data indicative of the gray level of the sub~ect ~pecimen is obtained at 208. Determination of whether an updated gray l~vel should be called for is made at step 210 and if not, thQ system is exited at 212.
Proce~ding to FIGUR~ 6B, when it is determined that a qray level should be updated, the syste~ proceed~ to step 214 ~herein a parts counter i8 reset to zero. An average gray level Or checked parts i8 obtained at step 216. A
deteroination is made at 218 whether the accumulated gray level i~ within pr~solected bounds. In either instance, a test i8 made at 222 to det~r~ine whether an absolute high li~it Or tho gray scale ha~ been exceeded. If 90, the high level is road~usted at a24. In either instance, a similar chec~ Or the absolute low li~it i8 made at 226 and read~usted is made when nece~sary at step 228.
Turning to FIGURE 6¢, a determination i8 next made at step 230 whether the ad~usted level has exceeded a pres-le¢ted no~inal high li~it. If 80, an output warning i8 glven at 232 and tha y~te~ ~erminated at 234 to allow for ., ,, ,'' ' ~
'~, -` 1 327637 additional verification of whether the system is performing adequately. If the nominal high li~it ha~ not been exceeded, a similar te~t i5 made at step 236 with reqard to a nominal low limit, with a similar output warning given at step 238, and an exit at 240 should this nominal low limit be exceeded.
If both the nominal high limit~ and nominal low limit have not been exceeded, thQ ~yQtem proceeds to step 242 wherein the modified gray level parameters arQ sat. From this, modification~ to the lighting to compen~ate for gray scale levels may be made. The accumulatQd gray lavel is then zeroed at step 244, and the on-line ad~ustment scheme exited at step 246.
The invention ha~ been described with reference to the prefQrrQd ~bodiments. Obviously modifications and altQrations ~ill occur to other~ upon the reading and understanding of the ~pecification. It ia my intention to include all such modifications and altQrations insofar as th~y com~ ~ithin thQ scop- Or thQ appended claim~ or their ~quival~nts th~rQof.
Backaround of the Invention This application pertains to the art of engineered lighting systems, and more particularly to engineered - lighting systems for lighting of specimens in an inspection environment The invention is particularly applicable to video inspection apparatuses and will be described with particular raference ~her~to, although it will be appreciated that the invention ha~ broadQr application~ such as lighting of specimens in any lnspection or computQr vi~ion system Machine visiQn sy~tQms are obtaining increasing æignificance in industry to aid in robotic assembly systems as well as inspection system~ for quality control Such mac~ine vision systems are g-nerally comprised of a lighting system to light a spocimen and a camera for sensing light reflect-d thorefrom A digitized image is formed from an image roceived by the camera The data of this image is then a~ail~ble for use in controlling a robot arm, identifying the specimen, or detormining whether the specimen is acceptable to specified standard~ Tho ability to govern operations in accordanc~ ~ith ~n in~pected specimen ~8 dictatad by the guality of the digitized image ~arly attQ~pts on i~proving t~Q accuracy of image data w~re dir~ct d to improvQ~m nts in d ~era~ and performance of algorithms on captur~d imag~ data, in an effort to improve int~grity, contrast, or resolution t~ereof Little ~mphasis wao plac d on the lighting systems, which, in a typical video inspection systQ~, ~ore co~prised of inert gas strobe lamps, such as x non strob~8, partlcularly when specimens are in motion rol~tivo to the vidoo camera For non-moving ~p~ci~ n~, co~on st-ady-state light sources s ~ h as ` 1 327637 fluorescent, quartz-halogen, incandescent, or the like, are typically used.
Such video lighting systems are plagued by a variety of problems. Placement of a single lamp over a specimen which includes a reflective ~urface often causes an image of the strobe lamp itæelf to be transmitted to an inspection device. Strobe lamps were also relatively expensive, varied in intensity from -~
flash to flas~, and tended to degrade over a period of lo time, thereby resulting in lessened resolution of a resultant video image. In applications in which many ~undreds or thousands of inspections per minute are required, in addition to poor lighting characteristics, the strobes also require regular replacement, which resulted in additional down time of the entire inspection apparatus.
The present invention contemplates a new and i~proved ~pparatus and method for lighting of a specimen in a video inspection environment which overcomes all t~ above-rQferred problems and others, and provides a video inspection lig~ting syste~ with increased re~olution and longitivity.
Su~ aL, C~ n ,`` `
In accordance with an aspect of the present invention, there is provided an array of directed light e~itting elements which are secured to direct light eaitted t~erefrom to a light field.
In accordance with a more limited aspect of the ` -present invention, a diffuser plate ~lends the light eoitted from various elements of the array and thereby serves to form a light field having an increased -~
unifor~ity of light intensity thereover. -In accordance with a more limited aspect of the inYention~ the light emitting elements are comprised of `~
electric, soli~ state devices, such as LED's.
`. . ' ' ~ : .
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In accordance with a still more limited aspect of ~` ` the invention, the array of LED's is shaped.
In accordance with another aspect of the present invention, a second array of light emitting elements is implemented to provide light to a specimen at a different angle to the specimen as co~pared to the light provided by the primary array.
In accordance with another aspect of the present invention, there is provided a method of lighting a lo specimen in an inspection environment which implements the above-structure.
In accordance with still another aspect of the present invention, effective intensities of various elQments of the array may be selectively varied.
lS An adv~ntage of an aspsct of the present system i8 that a lighting system is provided with increased resolution in a resultant image of an illuminated ~pecimen.
An advantage of an aQpect of the present invention 20 i8 the provision of a configured lighting array which `~
provides evenness-of-illumination; contrast over a vie~Qd ob~ect's surfac~ appear when light refleoted ~herefro~ i8 ~ocusQd at a viewing location.
An advantage of an a~pect of the present system i8 the provision of a lighting 8y~tem with increased longitivity of the lighting elements.
An advantage of an aspect of the present invention i8 tho provision of a video inspection apparatus wherein increased accuracy and resolution of an inspection process may be realized inexpensively by selectively varying a lighting of a speoimen to be inspeoted.
An advantage oX an aspeot of the present invention ~:
i- the provision of a system which provide both on-line ~-~
and off-line ad~ust~ent of a lighting system scheme by 35 soleotively varying aotivation of elements of an array. ~ -; :
~'', ~', .. . . ... .. .
Further advantages will be apparent to those of ordinary skill in the art upon reading and understanding of the subject specification.
- Summary Of The Invention Other aspects of this invention are as follows:
An engineered inspection lighting system comprlsing:
a plurality of directed primary light generating elements directed to a primary light field;
means for securing the primary light generating elaments in a preselected array arrangement to form a primary lighting array;
means adapted for directing light from the primary light generating elements to the primary light field; . -supply means for providing a single current pulse to ..
selected light generating elements of the primary lighting array to illuminate an associated specimen :
within the primary light field; and -the primary light field including a plurality of sections, the primary light generating elements being positioned in the primary lighting array such that each ~..... -primary light generating element thereof does not contribute light equally to each section of the primary light field and wherein light in the light field from at 25 least a portion of the light generating elements of the ;.:
~rray is overlapped with light from neighbouring light ~
gonerating elements of the array.
An inspoction systom comprising~
a plurality of directed primary light generating ~0 oloments;
means for securing the primary light ganerating elements in a preselected array arrangement to form a :
primary lighting array; i:
moans adapted for directing light from the primary `. ::
3S light generating elQments to a viewing area;
tho ~iewing area including a plurality of soctions, tho primary light generating elements being positioned in the pri~ary lighting array such that each ~g ~
. r ` ~ , } ` : t i - 4a -primary light element thereof does not contribute equally to each section of the viewing area;
supply means for simultaneously providing a current pulse to each of selected of the light generating 5 elements of the primary lighting array such that an associated specimen present in the viewing area will be illuminated solely by one current pulse; and monitor means adapted for sensing reflected light emitted from the primary lighting array after a reflection ~hereof from the associated specimen.
A method of lighting a specimen in an inspection .
system comprising the steps of: .
supplying single current pulse to an array of light generating elements to illuminate an associated specimens;
generating light from each light generating element of the array as a result of the supplying cf current thereto;
generating a primary light field from light from the array, the light field including a plurality of sections in which each lighting element of the array does not contribute egually to an intensity of light in each SQCtiOn;
directing light from the array to a viewing area;
exposing a speci~en to light from the array; sensing li~ht from the array after reflection thereof from the ~peclmen; and generating data indicative of a physical characteristic of the specimen in accordance with sensed light generated by the single current pulse.
An engineered inspection lighting system comprising: .
a plurality of directed lighting elements; securing means . .:
for securing the plurality of lighting elements to be directed to a light field; .
the securing means including means for securing the lighting elements in a preselected array arrangement to form a lighting array;
means adapted for directing light from the lighting . . .
`' ~
~ 1 327637 - 4b - -elements to the light field so as to light an associated specimen disposed therein substantially solely by specular illumination; and supply means for selectively providing current to lighting elements of the lighting array to provide a single illumination period to the associated specimen disposed in the light field.
An engineered inspection lighting system comprising: -a plurality of directed lighting elements;
lo means for securing the plurality of lighting elements to be directed to a light field; ~ -the securing means including means for sacuring the lighting elements in a preselected array arrangement to form a lighting array; -means adapted for directing light from the lighting :
elements to the light field;
supply means for se.lectively providing current to ..
lighting elements of the lighting array to provide a single illumination period to an associated specimen :. 0 disposed in the light field;
light sensitive transducer means for generating an electrical signal in accordance with light exposed th~reto;
lens means for focusing light onto the light sensitive transducer means, which light was generated a~
result of currant provided to the selected lighting el~ent~ of the array by the supply means, after exposure th~reof to the associated specimen;
means for generating an image data signal representative of light focused onto the light sensitive tran~ducer means by the lens means; and means for altering the supply means in accordance with the image data signal.
An engineered video inspection system comprising:
a plurality of d.irected lighting elements;
means for securing the plurality of lighting ~lements to be directed to a light field;
means for securing the lighting elements in a - 4c -~ 1 32 7 6 3 7 preselected ar:ray arrangement to form a lighting array;
means adapted for directing light from the lighting elements to the light field;
supply means for selectively providing current to lighting elements of the lighting array to provide a single illumination period to each of a series of associated specimens sequentially disposed in the light field;
transducer means for generating an electrical signal in accordance with light exposed thereto;
a lens means for focusing light onto the light sensitive transducer, which light was generated as a result of current provided to the selected lighting elements of the array by the supply means, after exposure thareof to each of the series of associated specimens;
means for generating a series of image data signals, :~ .
representative of light from each of the series of -associated specimens, focused onto the light sensitive transducer by the lens means; and ~Qans for accumulating acceptability data :
represQntative of acceptability of future associated sp~cimens *ro~ at least a portion of the series of image data signals.
A m~thod of automated video inspection comprising tha steps of:
sQquentially conveying a sequence of specimens to a light fi-ld;
sequentially activating a lighting array to provide a singl~ illumination period for each of the sequence of spQcim~ns to the light field therewith;
focusing light on a light sensitive transducer after each ~xposure thereo* to each of the sequence of ~pecimens;
generating a sequence of image data signals ;.
corresponding to each of the sequence of specimens;
comparing each o~ image data signals to data represQntativQ of acceptability of specimens; and selQctively re~ecting specimens in accordance with -~
.,: .
' :' .
` ~ - 4d -- the step of comparing.
. . ~ An apparatus adapted for automated video inspection - with an associated lighting array comprising: ~-means for sequentially conveying a sequence of specimens to a light field;
means for sequentially activating a lighting array to provide a single illumination period for each of the seguence of specimens in the light field;
means for focusing light on a light sensitive transducer after each exposure thereof to each of the sequence of specimens;
means for generating a sequence of image data signals corresponding to each of the sequence of specimens;
means for comparing each of the image data signals to data representative of acceptability of specimens; and means for selectively rejecting specimens in accordance with an output of the means for comparing each of the image data signals.
An apparatus adapted for automated video inspection wit~ an associated lighting array comprising:
means for sequentially conveying a sequence of sipQcimens to a light field with a continuous relative ~otion between the sequence of specimens and a single video camera;
means for sequentially activating a lighting array co~prised of a plurality of light emitting diodes to provide a single illumination period for each of the ~eguence of specimens in the light fiQld;
means for focusing light from the lighting array on t~e siingle video camera after each exposure thereof to -each Or the sequence of specimens;
means for generating a sequence of image data signals corresponding to each of ~he seguence of 35 specimens; .. .
means for comparing each of the image data signals to data representative of acceptability of specimens; and -~
~eans for selectively rejecting specimens in ,'''.':. ,' ~ 1 327637 - 4e -accordance with an output of the means for comparing each of the image data signals;
wherein the lighting array includes a primary array portion of the plurality of light emitting diodes and a secondary array portion of the plurality of light emitting diodes, the primary and secondary array portions differing such that an angle of propagation of light from light emitting diodes of the primary array portion to the light field is different from an angle of propagation of light from elements of ~he secondary to the light field.
Brief Description of the Drawings The invention may take physical form in certain parts and arrangaments of parts, embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part ~ereof and wherein: -FIGURE 1 is a diagram illustrating an embodiment of -:
a video inspection syste~ incorporation an engineered lighting system of the present invention;
FIGURE 2 illustrates two sample specimens for which an engineered lighting system of the present invention is well suited;
FIGURiE 3 is an alternate lighting array of the system of FIGURE l;
FIGURE 4 is yet another alternative array of lighting elements of the system of FIGURE l;
FIGURE 5 (5a - 5c) is a flow chart of gray scale calibration for off-line calibration of a video inspection system of the type of FIGURE l; and :
FIGURE 6 (6a - 6c) is a flow chart of gray scale calibration for on-line calibration of a video inspaction system of the type o~ FIGURE 1.
Detaileq Description of the Preferred Embodiment Referring now to the drawings, wherein the showing :~.
are for the purpose of illustrating the preferred Qmbodiment of the invention only and not for the purpose of limiting the ` ;
;~ ",~.,, ~ 5 - 1327637 same, FIGURE 1 shows a video inspection system including an engineered lighting apparatus A which is controlled by and supplies video information to a proces~or means B.
The engineered lighting apparatus A is comprised of a plurality of light emitting Qlements 10 which are secured in an array by a securing means 12 to form a primary lighting array.
The light emitting elements lo are directed by the securing means 12 to primary light fleld 14 in which not every element of the array contribute~ equally to each SQction thereof. A diffuser plate or means 16 is placed in the light fiald 14 to further diffuse light therefrom to create a viewing area 18 with an increased uniformity thereovQr.
For ~iQwing certain specimens, such as the circular/domed spQcimQn 20 illustrated in the figure, a secondary light source is advantagQous for obtaining increasQd contrast and resolution of the specimen. A
sQcondary light source 26 is illustrated as a ring array of ~econdary light e~itting elements 28. The liqht therefrom i~ directed to the vie~ing area 18 at an angle of travel thereto different from that of the primary array of elements 10. As illu~trated, the light from tha sacondary array propagatos 8UC~ that a co~ponent of direction of travel of light therefro~ is parallel to the plane of the primary array. This i8 particularly suited for the illu~trated specimen 20 as it provide~ for side lighting at an angle perpendicular to the direction of travel from that the primary array of elements 10.
As illustratQd, the elements 10 of the primary array create a diffused lighting for a specimen by means of the dlffuser 14. Specular (non-diffused), directly reflected light, is r sultant on the spocimen by the array of secondary - 6 ~ ~ 1 327 637 light emitting elements 28. It will be appreciated, however, that either diffused or specular lighting from e~ther array is desirable or satisfactory in applications dependent on the object to be viewed and the individual propertie~ thereof.
The preferred embodiment iæ, however, as illustrated in FIGURE 1.
Both the primary light emitting elements 10 and the secondary light elements 28 are preferably comprised of electrically powered solid state lighting devices, such as light Qmitting diodes (nLED'sn), or the like. Focused LED's are preferred as they provide for selective illumination of a controlled portion of the viewing area 18. While it is difficult to obtain light of a suitable intensity from standard electronic lightinq elements driven within their recommended current and voltage levels, in the video inspection environment, only a short viewing time necessary.
Accordingly, drivinq the solid state light element above its standard reco~mended ratings, for a relatively short duration, i~ found to provide suitable illumination without advoræely affecting it. For example, a ~ED device overdriven for a duration in the ranqe of 20-200 microseconds provides adequato illu~in~tion for a sufficient period with virtually no degradation of the elemont.
Although lighting of specimens for analysis in accordance ~ith the present inventi~n may be facilitated with light o~ ono or ~ore wavelengths, not limited to those of the visual spectru~, it has been ~ound that sultable analysis is genorally found ~ith llght o~ generally a single wavelength.
As ~ill be soen bolow, analysls of a specimen is ultimately ~acilitatod on analysis o~ gray scale levels of black and ~hito iaagos, ~hich may sultably be generated by LED's of a single color. For oxnmple, a commonly used red LED is qenerally ad~quato in m~my applications.
..
Light of any particular wave length may be obtained by use of appropriate light emitting elements. For example, ultraviolet or infrared light emitting diodes may be easily - implemented. Combinations of two or more types of LED's may be made to provide for a viewing area compri~ing light from multiple frequencies or wavelenqths. A combination such as redj green, and blue may be implemented to provide wave lengths of the entire visible spectrum, or any sub-combination thereof.
When lighting of viewing area 18 is initiated, light thereof is reflected off of a specimen, located therein, to a monitor means 36. As illustrated, the monitor means 36 is comprised of a lens of a video camera means 38, from which an electronic ~ignal representative of the specimen is obtained fro~ the reflected light. Tbe electronic image ~ignal i8 tran~mitted to an i~age digitizer 40 wherQin a numeric representation of the image is obtained by means of the f~miliar bit ~apped technique. A numeric representation, such as a binary numbar, of a gray scale is accordingly assigned to a representation of each of a plurality of picture ele~ents (npixels~ of a raster scan of the image.
For each pixel, gray scale information is stored in a memory location for future retrie~al and comparison.
Triggering or firin~ of the light emitting elemQnts is selectively fac~litat~d by ~eans of a supply of one or ~ore curr nt pulse~ initiated from a strobe control means 48, ~hich is in turn controlled by central processor unit ("CPU") ~0. . , ' .
The CPU 50 is ~uitably compriQed of a digital computer which operates on a storQd program located in memory 52 which is pre~-rably r~ndo~ acc:ess memory (RAN). The memory 52 is also seqmented into a working buffer region into which data onto which operation~ ar per~oxmed, as WQll as a display ', - 8 _ 1 327637 buffer region which provides image data to an input/output (I/o unit) 54, in a standard bit-mapped graphics fashion, or the like Both the wor~ing buffer and the display buffer are thereby adapted to store image data s Also stored in memory 52 is a digital representation of a presalected image range against which specimen image data may be compared to determine whether a particular specimen is acceptable As will be seen below, this data is both setable and a~terable ~he CPU 50, in operation under-a suitable software routina in the memory 52, facilitatQs comparison of the preselQcted image range data to that data indicative of an examined speci~en By suitable comparison in the CPU 50, a determination of acceptab~lity of the sub~ect SpeCimQn may be ~ade The CPU 50 also intQrfaces with the (I/0) unit 54 The I/0 unit 54 permits display of digitized image data, display of an illuminated ~po¢imen, control of operation of the CPU 50, and modification of a software program in the meoory sa.
Interraced to the CPU 50 is a speed sen~or 56 which providQs a signal indicati~a of a velocity of a conveyor means 58 whi¢h i8 uged to transport a series of specimens 20 to tho vie~ing area 18 The specimens are centerad in a s~locited ori ntation to the conveyor meanQ 58 by a centering ~eans 60 Tho CPU 50 is also interfaced with a sensor means 64 which 8 n~Qs pre~ence of a specimen 20 in the viewing area 18 Ais illustrated, the sensor means 64 i9 comprised of a photos nsitive cell working in con~unction with a light ecittor 66 a pre~ence Or a specimen in the viewinq area r sults in a br akaqe Or light path between the sensor 64 and th- light e-itter 66, ther~by providing a signal indicative . ..
g of an availability of the specimen for illumination and viewing Nhen a specimen 20 has been viewed and digitized image resultant therefrom compared to preselected data parameters, acceptability of the sub~ect specimen is determined by the cPu 50 A control signal is generated to facilitate re~ection of an undesirable specimen by a re~ecting means 68 which i~ illustrated as a plurality of air nozzles The noz~les are oriented so as to remove a specimen 20 from the lo conveyor 58 by mean~ of directed air streams A position of a specimen along the belt 58 is monitored to track the position of speeimens therealong to faeilitate removal by thQ means 68 The positioning may suitably be traeked by means of the speed sensor 56 working in eon~unction with the sensor 64 by aaleulation of travel time from a triggering of th~ sensor 64 to the ra~ecting mQans 68 Of eourse, in sueh an arrangement, the speed sensor would be unneeessary should the eonveyor be driven at a eon~tant Y-loeity by ~eans such as a synchronous a c ~otor In operation, a series of specimen~ 20 travel along the eonveyor 58 As eaeh ;specimen enters the viewing area 18, ~ eurrent pulse is pro~ided under the direction of CPU
50 by strobe eontrol 48, to seleetively pulse the light ~itting le~ents ~or a perlod suitable for obtaining a video imaqa Image data i8 eaptured through th~ monitor means 36 and the video eamera ~ean~ 38, and a digitized image thereof formed by the i~age digitiser 40 The image data i8 stored in memory 52, and eomparQd with pres~lectQd data ~n CPU 50 to detexmine aeeeptability of the speeimen by comparison th reo~ uit~ preseleated parameter data This is acco~plished by the CPU 50 acting in eon~unction with a ~o~tware routine in mQ~ory 52 Any non-eonforming specimen . ~.~.-.
- lo - ~ 1 32 7 6 3 7 is then re~ected by provision of an air ~et from the rejecting means 68.
Turning now to FIGURE 2, three dimen~ional specimens for which vidQo inspection by use of a lighting system as described above is particularly suited is illustrated. The ob~ects illustrated includQ surfaces with directions that are not advantageously illu~inated by a single light source. A
mere planer array of light elements would not illuminate all surfaces evenly, as those surfaces which have a component of direction parallel to the direction of light propagation would there~y appear darker, with the darkness level being proportional to that component. In addition, absent a planar array of relatively unifor~ liqht, those surfaces of the specimen which are parallel to a ~ingle plane of light elements would present a reflection or image of the lighting element itself, and not a visua~ Qignal indicative of the prop~rties of that surface which i8 as ~ignificant as is desirable.
T~e implementation of an L~D array, a~ illustrated in FIGUR~ hieh act~ in con~unction with a CPU control, is particularly suited for manipulations in lighting in accordance uith a ~peci~en und~r review. The CPU is suitably adapted ~or individual, or group, control of ~elected firing of variou- coDblnations or sub-combination~ of light emitting ele~nts of the array. Nith such individual control, ~oft~are modifications of a lighting system are made possible by select~ve control of ~hich light emitting elements are activated at any particular time, and the extent to which they are aeti~ated. Such is ~uitably re~erred to as "dark field~ illumination.
Nhen the light ~mitting elements are comprised of L~D's, an e~fective int~nsity or illumlnation therefrom may be varied not only ~ith fluctuation Or current levels at which the LED's ere driven, but also by variations in the duration during which the LED re~ains on. As the LED's are comprised of those of the focused variety, a relatively small area of an illuminated specimen may be controlled by means of a small grouping in its elements of the array. When a camera is used to create a gray scale image, the brightness level sensed by the camera ~ill be affected as a function of the duration at which the particular light sensitive elements therein are exposed to light. Accordingly, fluctuations in lo effectivQ illumination levels of a particular portion of a specimen may be obtained by varying thQ time during which a ~orresponding LED is aetivated. It is found that a suitable gray scale ad~u~tmant is facilitated by varying the on time of the L~D's from an on duration in the ranqe of 20 microsecond~ to 200 microseconds. The aetual on time of any LED or grouping thereof is controlled by means of the strobe eontrol 48 wor~ing under direetion of the CPU 50.
T~e ability to seleetivQly vary the effective intensity of the LED's, in addition to faeilitating viewing of non-unifor~ surfaees, provides means to allow for closed-loop eorrection of lighting patterns. Should one or more of the ele ents of tha array degradQ over time, the element may be controlled to eo~pensate for this degradation. Also, should one ele ent fail entirely, the e~ective illumination of its neighborlng lQments can be increased to compensate for ~ts los~. Additionally, gradual variations in the ~peci~ens the selves uhich merits eompensation in illuJination levels is possible. Means for aceomplishing such ~ill be described further below.
In illuDinating the ~peeimens of FIGURE 2, a gradual d oping of surfaces ~ay be compen~ated for by increasing ligbt fro~ cer~aln of liqht elem-nts of a shaped (illustrated as planar) array, or alternatively, by triggering the elementi3 of the secondary array Turning to FIGURE 3, an alternate, circular array formed of lighting elements is provided which i3 suitable for illumination of a specimen such as that of FIGURE 2B To facilitate for illumination of such a specimen, the array may have more elements from a perimeter 80 activated Alternatively, those e'ements may either be driven at a higher intenslty level than those of the elements moving toward the center 82 of the array, or illuminated for a longer duration Various lighting levels across a surface of a speciman may thereby be realized Turning to FIGU~E 4, another alternate array of lighting elemQntis ii~ provided which is particularly suited for viewing of a curved ~ur~ace a~ illustrated by the ~pecimens of FI~VR~ 2~ The curved array is shaped similarly to an exterior surface of the ob~ect to be viewed A curved array 86 i~ provlded, whic~ preferably has a similar radius of curvature to that of the spQ¢imen Such an array uses the property of light where an angle of incidence eguals the angle of reflaction A yet ~ore uniform gray scale pattern to vie~ imperfections of the surface is provided when all liqhtinq ela ents, have as a focus for reflected light, ths monitor ~eans 36 As ~ith th~ arr~ys described above, selected groups of liqht e~itting ele~ents fro~ the array of FIGURE 4 may si~ilarly be nabl d or varied, and the ef~e¢tive intensity thereby controlled to facilitate modifications in the lighting patt rn via soft~are control As noted above, the above-described system i9 - particularly suited for the obtaining of a high resolutiondigiti~ d i~age by means of an engineered lighting system ~
The pre~ nt yste~ i- also designsd to ~aintain consistency ~`
.
and quality of analysis by accounting for such factors as variations in lighting due to failure of individual light~ng elements of an array, or deqradation of lighting element~
over an extended period of use Illumination leveli3 also vary due to factors such as metal characteristics and the like Such ~ay result in re~ection of suitable specimens due to gradual trend toward variation from that which was previously within acceptable bounds Accordingly, a continued updating and revision to gray scaled data is lo desirable This may be accomplished either by manipulations of data ln the ~PU, or by variations in the lighting scheme of variouis subisets of elements of the lighting array as taught above Turning to FIGURE 5, with reference again to FIGURE 1, a flow chart iis provided for a routine to be stored in memory 52 (FIGUR~ 1~ for operation of CPU 50 to facilitate variation in gray lev~l readingis fro~ an analyzed specimen by varying the acceptabla intensity lQvels realized from light emitting elementQ of the array The flo~ chart of FIGURE 5 is directed to the off-line or set up qray level calibrations wherein an operator is per~itted to view an i~age of a specimen during set-up, to inltiali~o an illuoination pattern thereof~ The off-line set-up roUtin~ function~ to perfor~i analysis of a series of speci~en~ and oreate an initial gray scalQ level therefrom ~han a pr~el-cted number of con~-cutive Qpecimens fall ~lthin gray ~oale bound~, tha ~et-up is completed When a variation i~ found, the gray scale is ad~usted to account for the variation and the qu-st for the consecut~ve parts is raco~encQd Tho partloulars of this proces~ are as discussed ln the follo~ing routine Nith particular reference to FIGURE Sa, a set-up operatlon i8 commencad at step 100, and hardware to allow - 14 - ` ~ 327637 changes of acceptable gray scale levels i~ enabled. As noted above, such variations in illumination may be accomplished by means of varying the on-time of one or more LED's of the array analogous to the shutter speed control of a camera to vary exposure of various light sensitive element~ of the video camera 38 to reflec~ed light from a specimen 20.
Step 104 zeros a consecutive part~ numb~ring counter which sets thQ number consecutive part~ for which a conclusion of variation must be made to accomplish a gray scale adjustment. A display of the I/O unit s4 interfaced with a working buffer in the memory 52 in step 106. The LED
array is pulsed and a picture is acquired from the camera 38 in step 108 A picture i8 again acquired in step 110, and the digitised image thereof is copied to a display buffer in step 112. ThQ resultant image or picture date is then routed to the display at the V 0 unit 54 from the display buffer, in ~tep 114.
Turning particularly to FIGURE 5b, as a spQcimen's position varie~ within the viewing area 18, in step 116 a position of a part or spQci~en is detected and fixed. After deteotion o~ ~uch a part in ~tep 118, a gray scale level is ~easur d at step 120 and an image resultant therefrom is displayed at step 122. Whon a specimen i~ not located, the procs~s returns to step 106 and proceeds t~erefrom. A test of thi~ i~aga data i~ mada again~t selected parameters~
When thQ gray levol i8 deteroined to be within the preseleot~d bounds at step 12~, the consecutive parts counter i8 incre ented at 1~8. When it i8 determined that the gray level is not within the preselQcted boundQ, an ad~ustment thereo~ i~ ~ade at 12~. In either instance, the system proceads to ~tep 130 wherein the gray level command is tested to deter~lne w~Qther lt i~ too low in.accordance with a presQleoted standard. X~ $t 18 too low, an error signal i~
- 15 - ~327637 generated at 132 and the process i~ aborted at 134. A
negative determination at 130 allows for continuation of the process at 136 (FIGURE 5c). At this step, it is determined whether the gray level command is too high, and if so, a corresponding error display i8 made at 1~0 and the system is exited at 140. If the gray 1QVQ1 i8 acceptablQ, the system PrOCeed8 tO step 142 wherQin the gray level is set.
At step 144, the consecutivQ counter is testQd to see wh~th~r the presQlectad number of consecutive parts fitting lo in thQ preselQctQd gray level have been achievQd. If not, t~Q proc~s-~ i~ repeated from step 106 in a ~imilar fashion as illustratQd above.
Upon achievinq a pre~elected number of consecutive parts within gray 1QVQ1 paramQter~, the gray level ad~ustment hardWarQ i8 disQnablea at 146, the gray level command is displayed on the I/0 unit 54 at 148, and the gray level is saved at stQp 150. At this time, the off-line gray scale ad~ust~Qnt i~ completQd and the system is terminated at 152.
Turning to FIGUR~ 6, with continued reference to FIGUR~ 1, a flow chart for continuous ad~ustment of gray level ~hich is perfor~ed during an actual production inspection (on-line) is disclosed. During testing of a plurality of ~pecimens or pHrt~, slight fluctuatian trends in con~ecu~iv~ part~ of an inspection run may be found due to variation~ in ~tal quality fro~ separate batches, slight variation~ in coating thlc~ne~e~ which are not sutficient to render a speci~en unacceptable, or the like. Such variations ~ay al~o result from degradation of lighting ole~en~-, or froa a complete failure of one or more elements.
~0 The sub~ect sy~tQ~ provides ~or a closed loop ~eedback system which provides for continuous ad~ustment of the brightness level during such an inspection run. When a preselected nu~ber o~ consecutive parts provide a con~istent variation in the gray scale level, a correction is made. Ad~ustment of the light intensity, for axample by varying the duration during which the LED is illuminated, facilitates continuous refinement during an inspection run.
The on-line gray scale calibration i~ commenced at step 200, and a parts counter, which i8 initially zeroed, is incremented at step 20Z. When a part 20 enterq the viewing area 18, the lighting array is triggered and a digitized video image is captured in memory 52. Determination of lo whether a gray level checX i-~ to be taken is made at step 204. An ad~ustmant need no~ be made for each part in a serie~ inspQction. Salected or random checks may be instructed for thi~ purpose. Whan a gray level check is to be made, a level ~easure~ent of a current part or specimen is made at step 206, and data indicative of the gray level of the sub~ect ~pecimen is obtained at 208. Determination of whether an updated gray l~vel should be called for is made at step 210 and if not, thQ system is exited at 212.
Proce~ding to FIGUR~ 6B, when it is determined that a qray level should be updated, the syste~ proceed~ to step 214 ~herein a parts counter i8 reset to zero. An average gray level Or checked parts i8 obtained at step 216. A
deteroination is made at 218 whether the accumulated gray level i~ within pr~solected bounds. In either instance, a test i8 made at 222 to det~r~ine whether an absolute high li~it Or tho gray scale ha~ been exceeded. If 90, the high level is road~usted at a24. In either instance, a similar chec~ Or the absolute low li~it i8 made at 226 and read~usted is made when nece~sary at step 228.
Turning to FIGURE 6¢, a determination i8 next made at step 230 whether the ad~usted level has exceeded a pres-le¢ted no~inal high li~it. If 80, an output warning i8 glven at 232 and tha y~te~ ~erminated at 234 to allow for ., ,, ,'' ' ~
'~, -` 1 327637 additional verification of whether the system is performing adequately. If the nominal high li~it ha~ not been exceeded, a similar te~t i5 made at step 236 with reqard to a nominal low limit, with a similar output warning given at step 238, and an exit at 240 should this nominal low limit be exceeded.
If both the nominal high limit~ and nominal low limit have not been exceeded, thQ ~yQtem proceeds to step 242 wherein the modified gray level parameters arQ sat. From this, modification~ to the lighting to compen~ate for gray scale levels may be made. The accumulatQd gray lavel is then zeroed at step 244, and the on-line ad~ustment scheme exited at step 246.
The invention ha~ been described with reference to the prefQrrQd ~bodiments. Obviously modifications and altQrations ~ill occur to other~ upon the reading and understanding of the ~pecification. It ia my intention to include all such modifications and altQrations insofar as th~y com~ ~ithin thQ scop- Or thQ appended claim~ or their ~quival~nts th~rQof.
Claims (56)
1. An engineered inspection lighting system comprising:
a plurality of directed primary light generating elements directed to a primary light field;
means for securing the primary light generating elements in a preselected array arrangement to form a primary lighting array;
means adapted for directing light from the primary light generating elements to the primary light field;
supply means for providing a single current pulse to selected light generating elements of the primary lighting array to illuminate an associated specimen within the primary light field; and the primary light field including a plurality of sections, the primary light generating elements being positioned in the primary lighting array such that each primary light generating element thereof does not contribute light equally to each section of the primary light field and wherein light in the light field from at least a portion of the light generating elements of the array is overlapped with light from neighboring light generating elements of the array.
a plurality of directed primary light generating elements directed to a primary light field;
means for securing the primary light generating elements in a preselected array arrangement to form a primary lighting array;
means adapted for directing light from the primary light generating elements to the primary light field;
supply means for providing a single current pulse to selected light generating elements of the primary lighting array to illuminate an associated specimen within the primary light field; and the primary light field including a plurality of sections, the primary light generating elements being positioned in the primary lighting array such that each primary light generating element thereof does not contribute light equally to each section of the primary light field and wherein light in the light field from at least a portion of the light generating elements of the array is overlapped with light from neighboring light generating elements of the array.
2. The engineered lighting system of claim 1 wherein the primary light generating elements are comprised of electrically powered solid state lighting devices.
3. The engineered lighting system of claim 2 wherein the supply means further comprises means for supplying current of at least one of a selected magnitude or duration to selected ones of the primary light generating elements.
4. The engineered lighting system of claim 2 further comprising control means for providing a high current pulse to the primary array for illumination of the associated specimen within the primary light field.
5. The engineered lighting system of claim 4 wherein the primary lighting array is generally planar.
6. The engineered lighting system of claim 5 further comprising a diffuser means for diffusing at least a portion of light from the light generating elements to provide a more uniform intensity in the light field.
7. The engineered lighting system of claim 5 further comprising means for varying an intensity of light emitted from a first subset of light generating elements of the primary array in relation to an intensity of light emitted from a second subset of light generating elements of the primary array.
8. The engineered lighting system of claim 1 further comprising:
a plurality of directed secondary light generating elements;
means for securing the secondary light generating elements in a preselected array arrangement to form a secondary lighting array;
means adapted for directing light from the secondary light emitting elements to an area which includes light of the light field; and the supply means including means for supplying a single current pulse to selected light generating elements of the secondary lighting array simultaneously with a pulse of current supplied to selected light generating elements of the primary lighting array.
a plurality of directed secondary light generating elements;
means for securing the secondary light generating elements in a preselected array arrangement to form a secondary lighting array;
means adapted for directing light from the secondary light emitting elements to an area which includes light of the light field; and the supply means including means for supplying a single current pulse to selected light generating elements of the secondary lighting array simultaneously with a pulse of current supplied to selected light generating elements of the primary lighting array.
9. The engineered lighting system of claim 8 wherein the primary lighting array is generally planar and light emitted from the secondary lighting array propagates such that a component of a direction of travel of light therefrom is parallel to the plane of the primary array.
10. An inspection system comprising:
a plurality of directed primary light generating elements;
means for securing the primary light generating elements in a preselected array arrangement to form a primary lighting array;
means adapted for directing light from the primary light generating elements to a viewing area;
the viewing area including a plurality of sections, the primary light generating elements being positioned in the primary lighting array such that each primary light element thereof does not contribute equally to each section of the viewing area;
supply means for simultaneously providing a current pulse to each of selected of the light generating elements of the primary lighting array such that an associated specimen present in the viewing area will be illuminated solely by one current pulse; and monitor means adapted for sensing reflected light emitted from the primary lighting array after a reflection thereof from the associated specimen.
a plurality of directed primary light generating elements;
means for securing the primary light generating elements in a preselected array arrangement to form a primary lighting array;
means adapted for directing light from the primary light generating elements to a viewing area;
the viewing area including a plurality of sections, the primary light generating elements being positioned in the primary lighting array such that each primary light element thereof does not contribute equally to each section of the viewing area;
supply means for simultaneously providing a current pulse to each of selected of the light generating elements of the primary lighting array such that an associated specimen present in the viewing area will be illuminated solely by one current pulse; and monitor means adapted for sensing reflected light emitted from the primary lighting array after a reflection thereof from the associated specimen.
11. The inspection system of claim 10 further comprising means for generating specimen data indicative a physical characteristic of the associated specimen in accordance with sensed reflected light.
12. The inspection system of claim 11 further comprising testing means for testing the data against data indicative of a desired preselected physical characteristic of the associated specimen.
13. The inspection system of claim 12 further comprising indicator means for indicating acceptability of the associated specimen in accordance with an output of the testing means.
14. The inspection system of claim 13 further comprising:
a secondary light generating element;
the supply means including means for supplying a single current pulse to selected elements of the secondary lighting array simultaneously with a pulse of current supplied to selected light generating elements of the primary lighting array: and means adapted for directing light from the secondary light generating element to the viewing area.
a secondary light generating element;
the supply means including means for supplying a single current pulse to selected elements of the secondary lighting array simultaneously with a pulse of current supplied to selected light generating elements of the primary lighting array: and means adapted for directing light from the secondary light generating element to the viewing area.
15. The inspection system of claim 13 further comprising means for transporting the associated specimen to the viewing area.
16. The inspection system of claim 15 further comprising means for sensing a presence of the associated specimen in the viewing area.
17. The inspection system of claim 16 further comprising means for performing one of acceptance and rejection of a specimen in accordance with an output of the indicator means.
18. A method of lighting a specimen in an inspection system comprising the steps of:
supplying single current pulse to an array of light generating elements to illuminate an associated specimens;
generating light from each light generating element of the array as a result of the supplying of current thereto;
generating a primary light field from light from the array, the light field including a plurality of sections in which each lighting element of the array does not contribute equally to an intensity of light in each section;
directing light from the array to a viewing area;
exposing a specimen to light from the array;
sensing light from the array after reflection thereof from the specimen; and generating data indicative of a physical characteristic of the specimen in accordance with sensed light generated by the single current pulse.
supplying single current pulse to an array of light generating elements to illuminate an associated specimens;
generating light from each light generating element of the array as a result of the supplying of current thereto;
generating a primary light field from light from the array, the light field including a plurality of sections in which each lighting element of the array does not contribute equally to an intensity of light in each section;
directing light from the array to a viewing area;
exposing a specimen to light from the array;
sensing light from the array after reflection thereof from the specimen; and generating data indicative of a physical characteristic of the specimen in accordance with sensed light generated by the single current pulse.
19. The method of claim 18 further comprising the step of sequentially bringing a subsequent associated specimen into the viewing area.
20. The method of claim 18 further comprising the step of testing the data against data indicative of a desired preselected physical characteristic of each associated specimen.
21. The method of claim 20 further comprising the step of performing one of rejection and acceptance of a specimen in accordance with the testing.
22. The method of claim 21 further comprising the step of sensing a presence of the associated specimen in the viewing area.
23. An engineered inspection lighting system comprising:
a plurality of directed lighting elements;
securing means for securing the plurality of lighting elements to be directed to a light field;
the securing means including means for securing the lighting elements in a preselected array arrangement to form a lighting array;
means adapted for directing light from the lighting elements to the light field so as to light an associated specimen disposed therein substantially solely by specular illumination; and supply means for selectively providing current to lighting elements of the lighting array to provide a single illumination period to the associated specimen disposed in the light field.
a plurality of directed lighting elements;
securing means for securing the plurality of lighting elements to be directed to a light field;
the securing means including means for securing the lighting elements in a preselected array arrangement to form a lighting array;
means adapted for directing light from the lighting elements to the light field so as to light an associated specimen disposed therein substantially solely by specular illumination; and supply means for selectively providing current to lighting elements of the lighting array to provide a single illumination period to the associated specimen disposed in the light field.
24. An engineered inspection lighting system comprising a plurality of directed lighting elements;
means for securing the plurality of lighting elements to be directed to a light field;
the securing means including means for securing the lighting elements in a preselected array arrangement to form a lighting array;
means adapted for directing light from the lighting elements to the light field;
supply means for selectively providing current to lighting elements m of the lighting array to provide a single illumination period to an associated specimen en disposed in the light field;
light sensitive transducer means for generating an electrical signal in accordance with light exposed thereto;
lens means for focusing light onto the light sensitive transducer means, which light was generated as a result of current provided to the selected lighting elements of the array by the supply means, after exposure thereof to the associated specimen;
means for generating an image data signal representative of light focused onto the light sensitive transducer means by the lens means; and means for altering the supply means in accordance with the image data signal.
means for securing the plurality of lighting elements to be directed to a light field;
the securing means including means for securing the lighting elements in a preselected array arrangement to form a lighting array;
means adapted for directing light from the lighting elements to the light field;
supply means for selectively providing current to lighting elements m of the lighting array to provide a single illumination period to an associated specimen en disposed in the light field;
light sensitive transducer means for generating an electrical signal in accordance with light exposed thereto;
lens means for focusing light onto the light sensitive transducer means, which light was generated as a result of current provided to the selected lighting elements of the array by the supply means, after exposure thereof to the associated specimen;
means for generating an image data signal representative of light focused onto the light sensitive transducer means by the lens means; and means for altering the supply means in accordance with the image data signal.
25. The engineered inspection lighting system of claim 24 wherein the means for altering the supply means includes means for varying at least one of activation, intensity, or duration of selected of the plurality of lighting elements.
26. The engineered inspection lighting system of claim 24 wherein the plurality of directed lighting elements include elements of each of a plurality of lighting spectra.
27. The engineered inspection lighting system of claim 24 further comprising means for generating specimen data representative of a physical characteristic of the associated specimen in accordance with the image data signal.
28. The engineered inspection lighting system of claim 27 further comprising means for testing the specimen data against data representative of a desired physical characteristic of the associated specimen.
29. The engineered inspection lighting system of claim 28 further comprising means for transporting the associated specimen to the viewing area.
30. An engineered video inspection system comprising:
a plurality of directed lighting elements;
means for securing the plurality of lighting elements to be directed to a light field;
means for securing the lighting elements in a preselected array arrangement to form a lighting array;
means adapted for directing light from the lighting elements to the light field;
supply means for selectively providing current to lighting elements of the lighting array to provide a single illumination period to each of a series of associated specimens sequentially disposed in the light field;
transducer means for generating an electrical signal in accordance with a light exposed thereto;
a lens means for focusing light onto the light sensitive transducer, which light was generated as a result of current provided to the selected lighting elements of the array by the supply means, after exposure thereof to each of the series of associated specimens;
means for generating a series of image data signals, representative of light from each of the series of associated specimens, focused onto the light sensitive transducer by the lens means; and means for accumulating acceptability data representative of acceptability of future associated specimens from at least a portion of the series of image data signals.
a plurality of directed lighting elements;
means for securing the plurality of lighting elements to be directed to a light field;
means for securing the lighting elements in a preselected array arrangement to form a lighting array;
means adapted for directing light from the lighting elements to the light field;
supply means for selectively providing current to lighting elements of the lighting array to provide a single illumination period to each of a series of associated specimens sequentially disposed in the light field;
transducer means for generating an electrical signal in accordance with a light exposed thereto;
a lens means for focusing light onto the light sensitive transducer, which light was generated as a result of current provided to the selected lighting elements of the array by the supply means, after exposure thereof to each of the series of associated specimens;
means for generating a series of image data signals, representative of light from each of the series of associated specimens, focused onto the light sensitive transducer by the lens means; and means for accumulating acceptability data representative of acceptability of future associated specimens from at least a portion of the series of image data signals.
31. The engineered video inspection system of claim 30 further comprising means for testing each image data signal against the acceptability data to determine acceptability of a specimen from which the image data signal was obtained.
32. The engineered video inspection system of claim 31 further comprising means for updating the acceptability data in accordance with selected image data signals generated from the series of associated specimens.
33. A method of automated video inspection comprising the steps of:
sequentially conveying a sequence of specimens to a light field;
sequentially activating a lighting array to provide a single illumination period for each of the sequence of specimens to the light field therewith;
focusing light on a light sensitive transducer after each exposure thereof to each of the sequence of specimens;
generating a sequence of image data signals corresponding to each of the sequence of specimens;
comparing each of image data signals to data representative of acceptability of specimens; and selectively rejecting specimens in accordance with the step of comparing.
sequentially conveying a sequence of specimens to a light field;
sequentially activating a lighting array to provide a single illumination period for each of the sequence of specimens to the light field therewith;
focusing light on a light sensitive transducer after each exposure thereof to each of the sequence of specimens;
generating a sequence of image data signals corresponding to each of the sequence of specimens;
comparing each of image data signals to data representative of acceptability of specimens; and selectively rejecting specimens in accordance with the step of comparing.
34. The method of claim 33 further comprising the step of generating the data representative of acceptability of specimens from selected of the sequence of image data signals.
35. The method of claim 33 wherein the step of sequentially activating a lighting array further includes the step of sequentially activating the lighting array comprised of solid state light generating elements.
36. The method of claim 35 wherein the step of sequentially activating a lighting array further includes the step of sequentially activating the lighting array comprised of light emitting diodes.
37. the method of claim 36 wherein the step of sequentially activating a lighting array further includes the step of sequentially activating the lighting array formed of at least one ring of light emitting diodes.
38. An apparatus adapted for automated video inspection with an associated lighting array comprising:
means for sequentially conveying a sequence of specimens to a light field;
means for sequentially activating a lighting array to provide a single illumination period for each of the sequence of specimens in the light filed;
means for focusing light on a light sensitive transducer after each exposure thereof to each of the sequence of specimens;
means for generating a sequence of image data signals corresponding to each of the sequence of specimens;
means for comparing each of the image data signals to data representative of acceptability of specimens; and means for selectively rejecting specimens in accordance with an output of the means for comparing each of the image data signals.
means for sequentially conveying a sequence of specimens to a light field;
means for sequentially activating a lighting array to provide a single illumination period for each of the sequence of specimens in the light filed;
means for focusing light on a light sensitive transducer after each exposure thereof to each of the sequence of specimens;
means for generating a sequence of image data signals corresponding to each of the sequence of specimens;
means for comparing each of the image data signals to data representative of acceptability of specimens; and means for selectively rejecting specimens in accordance with an output of the means for comparing each of the image data signals.
39. The apparatus of claim 38 further comprising means for generating the data representative of acceptability of specimens from selected of the sequence of image data signals.
40. The apparatus of claim 38 wherein the lighting array is formed of a plurality of solid state light generating elements.
41. The apparatus of claim 40 wherein the solid state light generating elements are comprised of light emitting diodes.
42. The apparatus of claim 41 further comprising securing means for securing selected light emitting diodes of the lighting array into at least one ring of light emitting diodes.
43. The apparatus of claim 42 wherein the securing means further includes means for aligning the selected light emitting diodes such that they generally circumscribe the light field.
44. The apparatus of claim 41 wherein the means for sequentially conveying includes means for conveying the sequence of specimens to the light field with a continuous motion relative to the light sensitive transducer.
45. The apparatus of claim 44 wherein the light sensitive transducer includes a single video camera.
46. An apparatus adapted for automated video inspection with an associated lighting array comprising:
means for sequentially conveying a sequence of specimens to a light field with a continuous relative motion between the sequence of specimens and a single video camera;
means for sequentially activating a lighting array comprised of a plurality of light emitting diodes to provide a single illumination period for each of the sequence of specimens in the light field;
means for focusing light from the lighting array on the single video camera after each exposure thereof to each of the sequence of specimens;
means for generating a sequence of image data signals corresponding to each of the sequence of specimens;
means for comparing each of the image data signals to data representative of acceptability of specimens; and means for selectively rejecting specimens in accordance with an output of the means for comparing each of the image data signals;
wherein the lighting array includes a primary array portion of the plurality of light emitting diodes and a secondary array portion of the plurality of light emitting diodes, the primary and secondary array portions differing such that an angle of propagation of light from light emitting diodes of the primary array portion to the light field is different from an angle of propagation of light from elements of the secondary to the light field.
means for sequentially conveying a sequence of specimens to a light field with a continuous relative motion between the sequence of specimens and a single video camera;
means for sequentially activating a lighting array comprised of a plurality of light emitting diodes to provide a single illumination period for each of the sequence of specimens in the light field;
means for focusing light from the lighting array on the single video camera after each exposure thereof to each of the sequence of specimens;
means for generating a sequence of image data signals corresponding to each of the sequence of specimens;
means for comparing each of the image data signals to data representative of acceptability of specimens; and means for selectively rejecting specimens in accordance with an output of the means for comparing each of the image data signals;
wherein the lighting array includes a primary array portion of the plurality of light emitting diodes and a secondary array portion of the plurality of light emitting diodes, the primary and secondary array portions differing such that an angle of propagation of light from light emitting diodes of the primary array portion to the light field is different from an angle of propagation of light from elements of the secondary to the light field.
47. The apparatus of claim 46 wherein at least the primary array portion is generally planar, and wherein a component of direction of travel of light from the secondary light portion is parallel to the primary array portion.
48. The apparatus of claim 44 wherein the means for generating a sequence of image data signals includes means for isolating each image data signal of the sequence of image data signals in accordance with light provided by the single illumination period associated therewith, which single illumination period is obtained from activation of the lighting array by the means for sequentially activating.
49. The apparatus of claim 44 wherein:
the solid state light generating elements are further comprised of light emitting diodes particularly adapted for generating light in the visible spectrum; and the means for sequentially activation includes overpulsing means for sequentially activating the lighting array such that the light emitting diodes thereof are driven above normal levels.
the solid state light generating elements are further comprised of light emitting diodes particularly adapted for generating light in the visible spectrum; and the means for sequentially activation includes overpulsing means for sequentially activating the lighting array such that the light emitting diodes thereof are driven above normal levels.
50. The apparatus of claim 49 wherein the overpulsing means includes means for pulsing the light emitting diodes for a duration in the range of 20 to 200 microseconds.
51. The apparatus of claim 46 further comprising securing means for securing selected light emitting diodes of the lighting array into at least one ring of light emitting diodes.
52. The apparatus of claim 51 wherein the securing means further includes means for aligning the selected light emitting diodes such that they generally circumscribe the light field.
53. The method of claim 36 further comprising the steps of conveying the sequence of specimens to the light field with a continuous motion relative to the light sensitive transducer.
54. The method of claim 53 wherein the step of focusing light includes the step of focusing the light on the light sensitive transducer formed as a single video camera.
55. The method of claim 53 further comprising the step of sequentially activating the lighting array such that the light emitting diodes thereof are driven above normal levels.
56. The method of claim 53 further comprising the step of pulsing the light emitting diodes for a duration in the range of 20 to 200 microseconds.
Priority Applications (14)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/336,642 US4882498A (en) | 1987-10-09 | 1989-04-07 | Pulsed-array video inspection lighting system |
| CA000608413A CA1327637C (en) | 1987-10-09 | 1989-08-15 | Pulsed-array video inspection lighting system |
| US07/409,148 US5051825A (en) | 1989-04-07 | 1989-09-19 | Dual image video inspection apparatus |
| US07/439,553 US4972093A (en) | 1987-10-09 | 1989-11-20 | Inspection lighting system |
| AU65380/90A AU6538090A (en) | 1989-08-15 | 1990-09-17 | Engineered video inspection lighting array |
| CA002064250A CA2064250C (en) | 1989-08-15 | 1990-09-17 | Engineered video inspection lighting array |
| PCT/US1990/005268 WO1991006846A1 (en) | 1989-08-15 | 1990-09-17 | Engineered video inspection lighting array |
| EP90914626A EP0493487B1 (en) | 1989-08-15 | 1990-09-17 | Dual image video inspection apparatus |
| JP2513780A JPH06507470A (en) | 1989-08-15 | 1990-09-17 | Dual image video inspection equipment |
| CA002064014A CA2064014A1 (en) | 1989-08-15 | 1990-09-17 | Dual image video inspection apparatus |
| EP90915370A EP0498811B1 (en) | 1989-08-15 | 1990-09-17 | Engineered video inspection lighting array |
| AU64486/90A AU6448690A (en) | 1989-08-15 | 1990-09-17 | Dual image video inspection apparatus |
| PCT/US1990/005269 WO1991004634A1 (en) | 1989-08-15 | 1990-09-17 | Dual image video inspection apparatus |
| US07/622,349 US5072127A (en) | 1987-10-09 | 1990-11-29 | Engineered video inspecting lighting array |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10726587A | 1987-10-09 | 1987-10-09 | |
| CA000608413A CA1327637C (en) | 1987-10-09 | 1989-08-15 | Pulsed-array video inspection lighting system |
| US07/409,148 US5051825A (en) | 1989-04-07 | 1989-09-19 | Dual image video inspection apparatus |
| US42978089A | 1989-10-31 | 1989-10-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1327637C true CA1327637C (en) | 1994-03-08 |
Family
ID=27426698
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000608413A Expired - Fee Related CA1327637C (en) | 1987-10-09 | 1989-08-15 | Pulsed-array video inspection lighting system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1327637C (en) |
-
1989
- 1989-08-15 CA CA000608413A patent/CA1327637C/en not_active Expired - Fee Related
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