CN1008003B - System for detecting selective refractive defects in transparent articles - Google Patents

Abstract

The present invention relates to a system for lighting transparent glass objects, such as a glass panel of a television, which is used for detecting optical defects. A light source can be changed to a plurality of collimating light beams with unchanged space, and the light beams can be transformed in all directions; a scattering element with a baffle plate, which is uniformly lightened, has the properties that the refraction defect s enhanced to the specified degree, and meanwhile, the slow refraction deformation is not detected. The present invention observes objects by a camera with a specified receiving angle and a linear diode array.

Description

System for detecting selective refractive defects in transparent articles

Detect the optical defect in the glass object,, adopt light beam to illuminate these glass jars always, use the scattering backlight usually, and observe these containers with optics or photosensitive detector such as the defective in vial, the glass jar.What March 29 nineteen eighty-three, laid-open U.S. Patents 4378493 was narrated is exactly a kind of such device.Narrated a system in this part patent, it illuminates a container that is placed on the detection position on whole height.Described light source is placed on an incandescent lamp behind the frosted glass and is formed by many, produces a sizable scattering light source with this and comes backlight to illuminate to be placed on container on the detection position.The device that adopts this scattered light backlight to illuminate will not be owing to will can enter or influence from the front of container on any significant degree or the light of opposed walls emission at the side of contiguous container light, that may have refractive defects.One focuses on image on the front wall, that chamber wall is provided on vertical direction will the orthogonal array at its pixel for the video camera of linear array.This pixel is checked continuously, the function of the light intensity that the output signal of adjacent image point relatively, output signal are thereon to be received.Adopt this method, will in the output signal of linear array, become clearly to the light in the video camera visual field by the defect reflection on the chamber wall.Certainly this special device also requires to make container to rotate around its Z-axis, and to provide the circumference scanning of entire container wall and the zone of observing, this zone may also comprise the neck and the shoulder of container.In this system, when having a reflective defective in the chamber wall as a slight crack or extinction defective such as calculus etc., if these parts of chamber wall are by the viewing area of video camera, the wall that then focuses on the video camera pixel will leave the line of sight of detector and show the shadow zone the reflection of illumination light.By preceding described, adopt this method, by the output signal of adjacent image point relatively, just can determine defective where, and also can determine the size of defective to a great extent at vertical plane.Pixel is scanned with a proper speed, makes that each zone of bottle all is observed basically, and in fact many defectives will be expanded the scope greater than a single sweep, and will repeatedly show in succession the scanning.

Yet should remember that the light that arrives front wall is from scattering light source, so the light of the most of refraction effects that produce in the object does not just exert an influence to this light.Adopt a scattering light source that is placed on below the upright container to check the optical detection system of the dirt in the container when considering great majority, the optical delivery analyser that makes several numbers one class writings of factory's name and mould can not be configured in the container top seen like that, this situation just has been perfectly clear.

In addition, also has a kind of method that the such defective of the slight crack of different parts on the glass article is carried out optical detection, it is to adopt with special angle Ray Of Light is focused on a zone of object, then with detector, is placed on one as photoelectric cell and becomes 90 ° position approximately with focused ray.As United States Patent (USP) 3245533 described this devices, light will be from the defect reflection to the photoelectric cell in, so just indicate the existence of reflection defective.Past, this was to check the bottleneck of glass container and the typical method that the bottle bottom is divided always, when container at the measuring station place that disposes pick-up unit when its Z-axis rotates, can be reflexed in the photoelectric cell by slight crack during the light that is focused, container rotates the position that is arrived around its Z-axis just makes defective obtain detecting.Be to be understood that, these detected defectives are those defectives that typically are called as slight crack, they normally in container manufacturing process generally be the glass of the heat after being shaped contacted process equipment cold position since temperature decrease cause, in general, if at a distance of being more than the half-wavelength, slight crack is exactly a reflective between the apparent surface of slight crack.If at a distance of less than half wavelength, light will pass through, and defective is reflection ray not just, so just can not detect defective.The another kind of defective that can use the focused light of orienting reflex to detect is those surface imperfection that produce in glass container, it will make focused ray produce refraction to depart from the direction in the original directive container, as United States Patent (USP) 3302787 is illustrated, detector is placed on the place that for example can be detected to refraction from the straight line on the finished product defective.

The detection of sheet glass goods, such as the face glass of televisor or glass plate for building, adopt a branch of focused beam to be radiated on the object traditionally always and make the transversal scanning on object of this light beam, simultaneously with object with the suitable angle of scanning ray under move, this method almost can be used for all glass surfaces.Light by object is received by a complementary scan light battery.Just narrated such system in the United States Patent (USP) 3199401 of Pittsburgh Flat Glass Co., Ltd.It should be noted that this system requirements adopts the illumination of a suitable angle to avoid owing to misreading that reflection is caused.Slightly the shaking of glass surface that appears in light and the vision detector will cause the refraction of focused ray and be created in the result who does not have illumination on the detector during this period.Whether all these problems are commercial unacceptable, become the problem that people are concerned about, therefore develop a kind of detection system, promptly, making product is that underproof that class defective is reinforced with regard to its intended purpose, and it is differentiated mutually that with the not serious product of those refraction effects this is still very beneficial.

As previously mentioned, an object of the present invention is to provide the method and apparatus of a kind of detection and sorting transparent substance such as televisor face glass, may be implemented on less expensive ground owing to adopt special lighting engineering, these apparatus and method can be classified defective substandard product and specification product by discriminated union effectively.

According to the present invention, it is that purpose is used up the system that illuminates the clear glass object that an optical defect with inspected object is provided, and the purpose of this illuminator is the object that moves past the detecting device visual field is provided the illumination of space invariance.

So, an object of the present invention is to use the scattering light source of a coverage on the focal plane that is placed on lens to be created in a plurality of " collimated light beams " propagated in the continuum of different directions, is " collimated light beam " illumination object under test of specific distribution with radiation direction or angular spectrum consequently so that detect refractive power defective in this object.

Another object of the present invention is the backlight irradiating object, and observe object with a linear array video camera, the signal that the analytical photography machine is received is in order to detecting the defective that those have refractive power character and have certain degree of tilt, and do not detect the defective of the refractive power deformation with gradual change character.

A further object of the invention, provide one and with the system of a space invariance object is moved with respect to light source, and observe the radiative Strength Changes of passing object system with the line sweep video camera with the bubble one class optical defect that detects the calculus in the glass object and bury by the backlight irradiating object.

Fig. 1 is the transmission plot of an embodiment of apparatus of the present invention.

Fig. 2 is the vertical cross section along the illuminator of 2-2 line among Fig. 1.

Fig. 3 (a) is the part amplification sectional view of looking along 3-3 line among Fig. 2.

Fig. 3 (b) is the part synoptic diagram along the observed amplification of 3-3 line among Fig. 2, is used for the optical observation system of key drawing 1.

Fig. 3 (c) is the diagram of the transmittance readings that obtained by the observation shown in Fig. 3 (b).

Fig. 4 (a) is the part amplification profile of the object seen along 4-4 line among Fig. 2.

Fig. 4 (b) is observed along 4-4 line among Fig. 2, to the described similar enlarged image of Fig. 3 b.

Fig. 4 (c) is the diagram of the optical transmission reading that obtains in the observation by Fig. 4 (b).

Fig. 5 is the synoptic diagram that is used for explaining optical principle of the present invention.

Fig. 6 is the transmission plot of the detection system similar to Fig. 1, and what it detected is a glass container.

Fig. 7 (a) is the sectional view along the amplification of the 7-7 line among Fig. 6, has wherein shown a bubble that includes.

Fig. 7 (b) is the image that the bottle of Fig. 7 (a) is partly photographed and observed.

Fig. 7 (c) is the diagram corresponding to the video camera signal intensity of Fig. 7 (b).

Fig. 8 (a) is the amplification profile along the object of the 8-8 line among Fig. 2, shown in the zone in a calculus is arranged.

Fig. 8 (b) is the enlarged image that the zone of Fig. 8 (a) is observed.

Fig. 8 (c) is the diagram corresponding to the photography signal intensity of Fig. 8 (b).

When producing glassware with typical glass production machinery, some not light absorbing defectives may be present in the article.When mentioning the defective that presents surface deformation, these faults of construction generally can be classified as three classes.Lines on the above-mentioned finished product defective of the first.It two is spaces, claims that sometimes they are bubble or blub, and this will decide on their relative size, and it three is discontinuities of material.Usually, all these defectives can cause that all light produces refraction or reflection.

For in the object of simple geometric shape such as detection for the refractive power defective in the sheet glass, look like more direct.Adopt the focused beam backlight to shine this glass plate, and the light of emission is described dull and stereotyped resembling with an optical system with limited receiving angle, those zones that light are mapped to outside the optical system to anaclasis will become shadow.This system depends on the acceptance angle of imaging optical system and the angle of illumination to the detection sensitivity of defective.Yet, for have than in the object of complicated shape as the detection of the refractive power defective in the glass container, have another major issue.Container will reflect and not need any specific defective because the orienting reflex light beam that the geometric configuration of container causes produces to those.In addition, the inside surface of glass container is not have constraint to form, and therefore sizable surface deformation easily takes place the inside surface of qualified commodity.The existence of these surface deformations generally can not be with the top said technology that is applied to sheet glass.

Detect televisor reflect the optical defect of underproof face glass the time, the surface imperfection of outside surface should be carried out and must be removed to this detection before finishing polish, when the light beam with a branch of finite angle frequency spectrum impinges upon on the surface imperfection, the light that transmits in the image is departed from owing to refraction action.

Can be in order to provide for the illumination of optical detection, clearly adopting a bigger light source of angular spectrum is very necessary as scattering light source.As previously mentioned, known when detecting light-absorbing defective, anaclastic unwanted effect can reach balance at last by an isotropic backlighting, and makes image formation of object with transmitted light.For example, want to detect the transparent vessel that is approximately cylindrical limit wall, a light source is placed on one side of bottle conveyor structure, and video camera is placed on relative one side, must begin and can be observed through container two walls the illumination of container.Yet, when using a general scattering light source, there is no significant difference with result when observing system chamber wall far away does not exist with the close chamber wall of observing system.So, for the sake of clarity, can eliminate the wall and the detection concept of far-end from considering in essence only to detect the system of a wall about one psychologically.There is a what is called " ripple " in the machine that great majority are made glass container, and it generally occurs with zone more than the bottom below the container middle part.This " ripple " is that glass is being produced when blank shape is blown out required bottle shape, the condition that produces is colder usually near the glass in the annular region of the blank of baffle plate, and this part glass is expanded like that equably not as other regional glass in the blank.This has produced a thicker annular region in that the limit of container wall is on glass.Usually ripple is a tangible problem, if it is also not serious, does not influence the commodity performance of container usually." ripple " can be called a gradual change, refrangible, the optical disturbance on the wall of container limit.

As shown in Figure 5, it has represented to be received by video camera 10 by the transmitted light in glass object cross section on two dimensional surface, and it has an acceptance angle Ω, mirrors near the resembling of object C point.If the object inside surface is smooth, promptly shown in dotted line 12, appear to come down to originate in source region A from the light that C is ordered.But if the inside surface injustice, shown in solid line 14, then in fact the axle of observation has been refracted an angle θ, appears to come down to originate in source region A ' from the light that C is ordered.If light source 16 brightness constancies and be isotropic owing to do not absorb, then are not subjected to the influence of described refraction on the surface brightness base that C is ordered.On the other hand, this method that reflects available occlusion area A ' is checked.Right side shading as online 18, so make this zone not launch light, resembling with bright visual field that C is ordered in this case compared and will be presented shadow.The refractive power defective just can be used by the minimizing of the apparent transmissivity of point (as the C point) and check, and is light absorbing defectives as them just.

But, adopt shading in defects detection, only to obtain very limited application, because the application of shading is not at space invariance.The appearance of a given defective depends on the relative position that C orders and the edge 18 of shading, makes the appearance of defective depend on the fore-and-aft distance of the object that it starts in the lateral attitude of visual field with from chopping point like this.Like this, even less refractive power defective is present in certain part of visual field, it also can cause the minimizing of transmitted light as the big refractive power defective of other parts.Like this, system is at spatially-variable.But, only depended on because Observing axis is refracted the angle θ that is constituted if guarantee the apparent transmitted light that C is ordered, can manage to overcome these restrictions.

As previously mentioned, suggestion uses that brightness is even, the anisotropic light source of light distribution comes the backlight irradiating object, transmitted intensity will with on light source A ' and thereby have nothing to do with C point and A ' 's relative position, to obtain desirable space invariance.Adopt newly-designed technology, produce a kind of spatial intensity distribution, and convert angular distribution to, optionally make this become sightless task and can realize in the surface gradually with optical means in the sample side of lens at the scattering light source place.Because these variations generally make Observing axis roll over very little angle,, then just do not observe those variations on these low-angles if light distribution or angular spectrum are uniformly.

With reference to Fig. 2, but represented the optical instrument of the light source of a particular design with required angular spectrum among the figure.Scattering light source S is such formation, and frosted glass 16 is placed on the front of many bulbs 17, and with focal length be that the lens 20 of F are at a distance of being the F place.Light source S goes up the point do not covered on all planes before lens such as X and Y just becomes collimated light beam, and 3 corresponding to X, and 2 corresponding to Y, they and line parallel ground ejaculation by luminous point and lens center.If light source is isotropic and has uniform luminance that every Shu Guangying has same light stream density.If a width is a=2Ftg θ ₀Covert 22 be placed on the scattering light source, then the angular spectrum of the illumination light before lens is limited in being less than or equal to ± θ ₀Angle on.So, can see, shelter width by change and can be easy to change angle θ ₀In addition, the two-dimentional angular region on the plane before lens does not need isotropy, and by selecting difform covert can at random determine its shape basically.

Use anisotropic angular spectrum and be specially adapted to detect transparent bottle, because they are not the symmetric shape of circle in shape.As can be seen, adopt the described technology of Fig. 2, a remodeling of sheltering to the situation of above-mentioned spatially-variable light source similar, space invariance is provided.The basic effect of illuminator has just provided an illumination that has strengthened, and makes the refractive defects at a steep angle to be exaggerated and to observe with bigger detecting reliability.Because video camera 10 is vertical, line sweep, linear array, it will focus on the line in space, and object moves by this line.As shown in Figure 6, light source the direction d of movement of objects or do perpendicular to the direction of vessel axis broad, but can do narrowlyer in another direction.The light that is mapped to the object back side has an exactly determined angle and direction on their illumination direction, as long as adopted a scatterer, this light source just can be to all throwing light on all directions.So just but particular design is so that adapt to the physical property and the optical property of observed object for the angle direction of optical illumination, and according to the covert selective reception angle and the focal length of lens, these lens just make light source have very accurate angle on direction.

Every bit on light source 16 all can produce the light that gang sends from lens 20 whole surfaces, and they are parallel to the straight line that is linked to be from that to the lens center.The direction of gang's light that every bit produced on the light source depends on that difference to the relative position of lens center.So just produced the angular spectrum of a light, its all position before to lens all is the same, the illumination that promptly produces space invariance.The angular spectrum of this light is the selected main points of illuminator of the present invention.Can select such frequency spectrum with the enhancing of that class refractive power defective of giving to detect, illuminate those simultaneously and generally can be directed the scrambling that gradual change that reflected light reflects is tilted with maximum.If light source is dispersed very much, all refractive power defectives all become very light, will what all can't see.Should be noted that video camera of the present invention observes for the vertical fillet on the object that moves through the visual field.The also technology of " particular design " but of using light source under the secondary imaging situation.

Like this, by aforesaid system as can be seen, the ray angles frequency spectrum that illuminator of the present invention produced has caused a kind of high-sensitive illumination system, suppresses the phenomenon of surface discontinuity of the slower variation of those glass containers that for example may be present in a visual field that moves past video camera 10 or other transparent glass article again in order to detect existence while of refractive defects more clearly.

Refer now to Fig. 1, the illuminator of the present invention of having represented to be used for to illuminate televisor face glass P among the figure with detect those selectable refractive power defectives and calculus, bury bubble, pitting and other functional defect in glass.

Because televisor face glass not only area is big but also all crooked on its length and width direction, so determine to adopt three detection meanss than suitable.The light source of describing in detail in Fig. 2 28,29 and 30 is below face glass P Width is arranged side by side at this panel.The central shaft of each light source is perpendicular to the surface of the face glass of being faced.Each light source 28,29,30 respectively has a video camera 31,32,33, aims at and arranges to observe a linear areas of the face glass that is illuminated by light source.Linear array in each video camera is all observed a wire zone of Width on the face glass, does not comprise the edge of rise.In fact face glass is to clamp with a unillustrated support, and direction moves along arc track shown in the arrow 34 that draws by the face glass two ends.The arc centers that support moved corresponds essentially to the central shaft of the camber line of face glass length direction to be checked.Because face glass is swung on camber line, so its all surface zone all will be through between light source 28-30 and the video camera 31-33, all observable zones all can be detected on the face glass.Clearly, can use the less Fresnel lens of size, and the axle of light source can move on on the position that more adapts to face glass curvature by three parts shown in light source is divided into.Yet if just must sizable single Fresnel lens of use will illuminate the whole width of face glass with the scattered light of a light source time.

Can see that in Fig. 6 lens 20 have enough big size to illuminate whole container to be checked.But for to observing around the container, the edge among Fig. 6 particularly is necessary to make container to pass through viewing area again after Z-axis rotates 90 °.In this way, the All Ranges of container is all carefully checked in detection system.Obviously, when observing the marginal portion of container, should exclude any signal that sends from the pixel of video camera with electronics method.In addition, be placed on covert 22 above the dispersing element can be according to the shape of container and particular design so that the shoulder of container and neck also can be detected.In this case, this covert will resemble the butterfly's wing of expansion, and wide part is corresponding to the shoulder regions of container lean.

With reference to Fig. 3 a and Fig. 4 a, wherein represented two types surface configuration the cross section they may when being pressed into face glass, produce.In Fig. 3 a, on glass have a line, at its top margin one quite sharp angle θ arranged ₁With the slow slope on the normal plane of getting back to face glass, it has angle θ ₂For angle θ ₁, light will be refracted, and can obtain the intensity of output signal from vertical pixel column 35 shown in Fig. 3 b.Just as seen, because θ ₁The angle is much larger than θ ₀The angle, then light is refracted, and the pixel of observing inclined surface will can not receive any significant light, on the other hand, because of the angle θ on slope ₂Less than θ ₀, its light of can refract light source not sending then, pixel will receive illumination almost completely.

Surface condition shown in Fig. 4 a is exactly an outstanding slightly zone, the angle θ of expression ramp portion ₃Less than θ ₀As the situation of Fig. 3 a Lower Half, pixel 35 will receive uniform illumination, and Fig. 4 c is the just the same this point that reflected by the signal intensity that pixel received of displayed map 4b.

Refer now to Fig. 7 (a)-(c) and Fig. 8 (a)-(c), wherein represented the defective of two amplifications, they are available subclass among the detected all types of defectives of detection system.

In Fig. 7 (a), defective is to bury bubble B, and it is that its inclination of that class or angle can make incident ray with a defective according to the bigger angle refraction of bright frequency spectrum.So the refract light that is produced by illumination light will be refracted into outside the normal observation line of several video camera pixels, then defective can be detected.Yet from Fig. 7 (c) center refracted ray not of bubble as can be seen.

Fig. 7 (b) has represented the low light intensity of video camera, and Fig. 7 (c) has represented the signal intensity shown in each pixel 35 in the video camera.Should remember when in the observed object not refraction or when absorbing light intensity be not 100%, and be substantially zero the situation shown in Fig. 3 (a) and Fig. 7 (a) when reflecting fully running into.The bottom of the defective of Fig. 3 (a) has the slope of relaxing, and selected incident light frequency spectrum makes this incident light be not refracted to any detectable degree by the slope that this kind relaxes.

Among Fig. 8 (a), expression as the defective of calculus " S ", this defective has been blocked light fully, and this is owing to calculus is not have the opaque inhomogeneity matter found in the consoluet glass in some components.Calculus has the character that constitutes stress concentration point, so touching or can become broken root during the temperature quenching at object.Like this, no matter in pipeline or retail point, should reject them to avoid the waste on the expense whenever detecting the glass container that contains calculus.Obviously, when in the TV set panel calculus being arranged, this is a flagrant functional defect.Calculus among bubble among Fig. 7 (a) and Fig. 8 (a) all is disabled, because when people watched the TV panel that contains this defective, they can become obviously.

Fig. 8 (b) and (c) represented intensity of illumination in video camera, wherein not only a pixel 35 is covered fully.

Above-described for several embodiment of system of the present invention, wherein the illuminator of examining object is made space invariance, so no matter where object is placed in the visual field, it can both obtain same intensity of illumination and available video camera is observed, like this, video camera is just insensitive by the motion of camera coverage for the position or the object of object.

Claims (6)

1, detect the method for refractive power defective in the transparent substance, this method may further comprise the steps:

The general closed planar scattering light source that-generation has uniform luminance;

-with one have place light source greater than zero focal length lens down front (distance is described focal length F) with this angular spectrum at lens front generation collimated light beam, collimated light beam sends from all points of the light source with identical flux density;

-on described light source, place a covert, with the illumination angle spectrum limitations of lens front to the equally distributed angle of light intensity and be equal to or less than extension line from the covert edge to the lens center and lens axis angulation θ ₀

-make examining object at the lens previous crops perpendicular to the moving of lens axis, thereby

-enhancing photographically has greater than θ ₀The refractive power defective at angle and with its from angle less than θ ₀The refractive power of gradual change distinguish in changing;

-observe object with the linear array video camera that focuses on body surface, thus come detection angles greater than θ by the variation of the light intensity that video camera received ₀Those refractive defects.

2, detect the method for transparent substance such as refractive power defective in the glass container, this defective has and can change other steeper receiving angle of phase region with the refractive power of gradual change in the object, when transparent substance along having the veritcal linearity cell array when moving in order to receive the linear upright track in video camera front from the focused light of this object vertical wall, this transparent substance is by backlighting, it is characterized in that the step of the backlighting of object is comprised: the behind at object forms a wide stray illumination light source, described light source has uniform luminance on its surface, on a segment distance of light source front, place a protruding or Fresnel lens, with produce along on the movement of objects path direction from the angular spectrum of the collimated light of lens; Reach the steeper angle of angle that described light source is restricted to gradual change refractive power variation to be distinguished to the light angle of lens.

3, a kind of device that detects the refractive power defective of the predetermined order of severity in the glass object, this glass object when a surveyed area by backlighting, they do top view by a video camera with linear vertical photosensitive cell array on surveyed area, it is characterized in that in the lighting process of described glass object, comprising: a scattering light source with uniform outer surface brightness for the detection that strengthens the doubling optical defect, one is placed on before the light source convex lens on the certain distance to produce one from the collimated light spectrum of lens by this surveyed area, illumination to the space invariance of described object is provided whereby, because have the refractive defects of the predetermined order of severity, the illuminating ray in camera coverage will be refracted.

According to the device of claim 3, it is characterized in that 4, further comprise a covert on the circumference part of described light source, described covert limits the irradiating angle of described distribution of light, so that make illumination become comparatively insensitive to the gradual change refractive power.

According to the device of claim 4, it is characterized in that 5, wherein said glass object is the televisor face glass, and comprise that a plurality of scattering light sources, each light source illuminate a different piece of face glass.

6, according to the device of claim 5, it is characterized in that, further comprise a plurality of video cameras, wherein each video camera is observed a different piece that is illuminated on the face glass.

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