IL43293A

IL43293A - Method and device for detecting whether a given zone is occupied by an edge portion which belongs to a transparent sheet or ribbon

Info

Publication number: IL43293A
Application number: IL43293A
Authority: IL
Inventors: J Josse; R Albert; J Declaye; M Bodart
Original assignee: Glaverbel
Priority date: 1972-10-03
Filing date: 1973-09-21
Publication date: 1976-10-31
Also published as: GB1429544A; FR2203979B1; TR17870A; AT363628B; ES195942U; JPS5623085B2; NL7313100A; FI53040C; IT1004562B; NO141280C; ATA824273A; LU66220A1; FR2203979A1; ES195942Y; SE395961B; IE38281B1; US3843264A; AU6070773A; IL43293A0; DK141385C

Description

METHOD AND DEVICE FOR DETECTING WHETHER A GIVEN a ZONE IS OCCUPIED BY AN EDGE PORTION WHICH BELONGS SO A TRANSPARENT SHEET OR RIBBON ΓΠ7 7(i) 7\SI "Π "> 717 0130 1 'ίΠ3 TUN ON "» 1 J Τ>ϋΙ3Π1 HEP 10 •ΠΊΡΗί DID IN The present invention relates to a method of detecting whether a given zone is occupied by an edge portion which > belongs to a transparent sheet or ribbon having a predetermined spatial orientation, said edge portion having a geometry fulfilling certain conditions;, and to apparatus for use in , ■ ■ performing such method.

The invention has particular, but riot exclusive reference to detecting the presence of such an edge portion of a glass sheet or ribbon in a given zone during manufacture of the glass. This information is particularly important for purposes of quality control.

It is known to project light beams along the boundaries of such a given zone so that if one of such beams is obstructed by an opaque shee edge portion and the other is allowed to pass, . then that edge portion is known to be in the zone . This method is clearly not suitable for use in connexion. with transparent sheet or ribbon edge portions, since both such beams would be allowed to pass whether or not an edge portion lay within the zone.

It is an object of the invention to provide such a method whereby the presence of such an edge portion in the given zone is detected without physical contact with the sheet or ribbon edge, since such contact might impair the quality of the edge, and because of the risk of damage to the detection apparatus should a sudden discontinuity in the edge be encountered.

The method of the present invention is therefore characterised in that a beam of light rays is projected into said zone in a direction such that, if a sheet or ribbon has said orientation and has an edge portion of a said geometry present in said zone, the light rays enter the edge portion after travellin in a direction across and at an acute angle to one side of the sheet or ribbon and light rays emerge from said edge portion to travel i a direction across and at an acute angle to the other side of said sheet or ribbon after deflection by said edge portion, and in that the existence of rays which thus emerge is detected.

The method according to the present invention has the advantage that it enables such detection in respect o transparent sheets or ribbons to be performed rapidly and accurately without physical contact with the edge portion i present.

Also, the required detection may take place at positions well spaced from the sheet or ribbon, e.g. at a distance of several metres therefrom. The method can be applied in situations where the sheet or ribbon is very hot without overheating the apparatus used in performing the method. For example, the method may be applied on a control factor in the manufacture of flat glass, e.g. in the annealing lehr of a glass drawing machine.

Preferably said light beam is caused to scan said zone, so that regular indications of the presence of such an edge portion in said zone may be obtained.

It is preferred that the method according to the invention be applied for detecting whether either or both of two given zones is or are occupied by one or the other of two opposite edge portions which belong to a transparent sheet or ribbon having a predetermined spatial orientation, such edge portions having geometries fulfilling certain conditions, and characterised in that said light beam is caused to scan both said zones. In this way, information about the presence of the opposite edge portions of the sheet or ribbon can be obtained without duplicating the light beam projecting apparatus which is required.

Arrangements where the method is applied for detecting whether either or both of two given zones is or are occupied by one or the other of. two opposite edge portions which belong to a transparent sheet or ribbon having a predetermined orientation, such edge . portions having geometries fulfilling certain conditions, and characterised in that the light rays projected into both said zones are emitted from a common source and in that deflected rays emergent from both said zones are detected at a single position, have the advantage that information about the presence oif the opposite edge portions of the sheet or ribbon can be obtained without duplicating any light ray detecting apparatus which is required.

Preferably, light rays which would otherwise pass straight to the detection position through a part of the sheet or ribbon located between said edge portions are screened off so that detection of the deflected rays, if any, is not disturbed by the projected beam.

When said light beam is displaced without interruption . for scanning both said zones in succession and the time . interval between successive detections of deflected light rays is measured, the width of the sheet or ribbon may readily be determined, and this is therefore an especiall valuable feature.

Preferably, said beam of light is caused to scan at least one said zone and a reference signal is generated at at least one predetermined point in such scanning movement, and the time interval between generation of said reference signal and detection o the existence of light rays deflected by a said edge; portio is measured.

It is advantageous if the method is continuously applied while a said sheet or ribbon is in motion along a path comprising said zone or zones, since any changes in the position of one or both edges of: the sheet or ribbon can be immediately indicated.

Apparatus according to the invention for detecting whether a given zone is occupied by an edge portion which belongs to a transparent sheet or ribbon having a predetermined spatial orientation, said edge portion having a geometry fulfilling certain conditions, is characterised in that said apparatus comprises a support for supporting such sheet or ribbon with a said orientation, a projector for projecting a beam of light rays into said zone in a direction across and .at an acute angle to one side of a sheet or ribbon having said orientation, and a detector arranged to detect the existence of deflected light rays emergent from said zone and travelling across and at an acute angle to the other side or such sheet or ribbon.

This apparatus has many advantages. It is extremely siirple, and may be contained wholly within the projected plan area of the sheet or ribbon, thus saying space. The apparatus is readily adaptable to detecting the presence of a sheet or ribbon edge portion in a large variety of given zones merely by pointing the projector and detector in the appropriate directions, without otherwise moving them.

Preferably, said projector comprises means operative to cause said light beam to scan said zone. The specific advantages of this and other preferred features of apparatus according to the invention will readily be appreciated from the advantages set . forth above in relation to corresponding preferred features of the method according to the invention.

Preferred embodiments of apparatus according to the invention, for detecting whether either or both of two given zones is or are occupied by one or the other of two opposite edge portions which belong to a transparent sheet or ribbon having a predetermined spatial orientation, such edge portions having geometries fulfilling certain conditions are characterised in that . said projector comprises means operative to cause said light beam to scan both said zones.

Advantageously, said projector is operative to project light rays into both said zones, and said detector is arranged to detect the existence of deflected light rays emergent from both said zones.

Preferably the apparatus comprises a screen located between the projector and the detector.

Embodiments wherein said projector is operative to cause said light beam to scan both said zones in succession without interruption and said detector comprises timing means for measuring the time interval between successive ' detections of deflected light rays, are preferred since they enable the width of the sheet or ribbon to be measured.

Advantageously, said projector comprises means operative to cause said light beam to scan at least one said zone and the apparatus further comprises a generator for generating a reference signal at least one predetermined point in such , scanning movement, there being further provided means for measuring the time interval between generation of such reference signal and detection of the existence of light rays deflected by a said edge portion.

Preferably, said support is a conveyor, and the apparatus is adapted to operate cohtinously during movement of a sheet or ribbon along the conveyor.

Various embodiments pf the invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which; , Figs. 1 and 2 illustrate the course of a beam of light in the zone of an edge portion of a transparent sheet having a plane edge and a curved edge respectively; Fig. 3 illustrates one embodiment of apparatus for- the performance of a method according to the invention; Fig. shows another embodiment of apparatus according to the invention; and Fig. 5 illustrates a futher embodiment of apparatus according to the invention.

Fig. 1 shows a glass sheet 1 having a rectilinear edge face 2 lying at right angles to the main plane of the sheet 1.

In figure 2 the glass ribbon 3 has an edge face which is rounded off in the shape of a semi-circle and whose median perpendicular coincides with the main plane of the ribbon 3· In the case of both the sheet 1 and the ribbon 3i when an incident ray of light 5 enters the glass it is deflected from its previous direction of propagation by refraction and passes inside the glass as far as the rectilinear edge face 2 of the sheet 1 or the curved edge face 4 or the ribbon 3· The ray of light 5 is substantially completely reflected back into the glass at the edge faces 2 and 4, and the deflected ray of light 6 passes to the next boundary between the glass and its surroundings and is there again deflected from its direction of propagation in the glass by refraction.

The existence of the deflected ray of light 6 is de t ected by the performance of the method according to the invention. The deflected ray of light 6 is strongly deflected in relation to the incident ray of light 5 and can be detected without the risk of disturbance by the incident beam of light.

Fig 3 shows an apparatus according to the invention for detecting whether each of two given zones 7 is occupied by one or the other of , two opposite edge portions 8, 9 of. 'a ribbon 10 of glass in an annealing lehr 11. The glass ribbon 10 moves substantially in the main median plane of the annealing lehr 11 perpendicularly to the plane of the drawing. The annealing lehr 11 has a bottom 12, side walls 13, and a roof 1¾. The bottom 12 and roof lA of the annealing lehr 11 have light-transmitting regions 15 and l6 respectively through which an incident beam of light 5 and also deflected beams 6, 26 of light can pass. Lying in the mid-plane 17 perpendicular to the glass ribbon 10 and below the ribbon is a rotary mirror 18 analogous to that of a mirror galvanometer located at a transmitting point 1 on the path of a beam of light emitted by a laser 20. This beam of light is caused to scan by the rotation of the rotary mirror 18 over a zone which extendi to either side beyond the edges 8, 9 of the ribbon 10.

The incident beam of light 5 i reflected and refracted at the inner surfaces of each of the edges 8, 9 during the course of scanning and the deflected beams of light 6, 26 pass back towards the vertical plane 17 and form with the ribbon 10 angles substantially equal to the angle formed by. the incident beam of light 5 with the ribbon 10 at those edges.

A photo electric detector 21 which receives the deflected beams of light 6, 26 at the moments when they pass through reference points .22, is also show in the vertical plane 17 the ribbon 10 and on rece ption of a deflected beam of light, this detector delivers an electrical impulse.

The detector 21 is connected to a timing device 23 which measures the interval of time between successive pulses. Connected to the timing device 23 is an indicating apparatus 2k which constantly indicates the measuring results. If the rate of rotation of the mirror l8 is known, the speed of scanning is known, and hence. the indicating apparatus 2k may be calibrated to give a direct reading of the width of the ribbon 10.

Disposed between the glass ribbon 10 and the detector 21 is a screen 25 so wide that when the beam of light 5 is caused to scan, only this beams of. light 6, 26 reflected by the edges 8, 9 can reach the detector 21, while the incident beam of light 5 passing through the rest of the glass ribbon 1.0 during intermediate portions of the scanning period, screened from the detector. The screen 25 can be omitted if the roof 14 and/or the bottom 12 of the annealing lehr 11 have a central portion which is opaque and adequately screens the detector against the incident beam of light 5 during this period of the scanning.

The rotary mirror 18 is preferably pivoted backwards and forwards at constant speed, so that the inoident beam of light 5 scans the ribbon 10 at a constant frequency. As soon as the beam of light 5 impinges on the edge 8, it is deflected there and the beam of light 6 deflected by. the edge 8 passes to the detector 21 where a pulse is produced which starts the timing device 23 » As soon as the incident beam of light 5 arrives durin its scan at the opposite edge 9i it is again deflected and the beam of light 26 deflected by the edge 9 also passes to the detector 21 . and produces there a second pulse which stops the timing device 23 . The interval between the two pulses is a measurement of the width of the glass ribbon 10 , since the distance apart of the edges 8 , 9 can be determined from the measured interval in time and the known speed of rotation of the rotary mirror 18 in conjunction with its distance from the main plane of the glass ribbon 10 .

The apparatus illustrated in Fig. 3 produces a pulse at its detector 21 when the beam of light 5 is deflected at either edge 8 , 9 of the ribbon 10 , provided that the respective edge is located in one of the given zones 7 · The positions and extents of these zones 7 are determined by the positions and extents of the various transparent regions 15 , l6 pf the annealing lehr . il , and of the screen 25 . In order that a pulse should be produced at the detector 21 , it is also necessary that the respective edge 8 or 9 of the glass ribbon 10 should have/ a geometry which will cause deflection of the beam to the required degree. Certain lenticular and prismatic shapes will not give rise to this deflection, but these shapes are not encountered in practice in a ribbon travelling along an annealing lehr.

In Fig. ¾ like elements have like references to those in Fig. 3 , but only that part of the measurin apparatus which is associated with the edge 9 is shown.

Shown in the drawing above the main plane of the glass ribbon 10 is a reference detector 27 , arranged to receive light passing through a reference point 28 disposed at such a distance from the vertical plane 17 that the beam of light 5 transmitted from the transmitting point 19 on the rotary mirror 18 impinges on the reference detector 27 without passing through the glass ribbon 10. Reception of this beam causes reference detector .27 to transmit a pulse to the timing device 23 to start the time measurement therein. In scanning from the reference point 27 to the edge of the ribbon 10 , the incident beam of light 5 sweeps an angle alpha. As soon as the beam of light 5 has swept this angle alpha, it is deflected at the edge 9 as described above,, and the beam of light 26 deflected by the edge 9 is received by the detector 21 which then transmits a pulse to the timing device 23 and terminates the time measurement. The interval .in time measured by the timing device 23 between the pulse from the reference detector 27 arid the pulse from the measuring detector 21 is a measurement of the value of the angle alpha, since both the distance of the transmitting point 19 on the rotary mirror 18 from the glass ribbon 10 and also the speed of scanning are known.

Since the distance of the reference point 28 from the main plane of the glass ribbon 10 and from the vertical plane 17 , which is also the median vertical plane of the annealing lehr 11 are also known, the exact position of the edge 9 - inside the annealing lehr is. given by the value of the angle alpha .

If with the apparatus illustrated in Fig. ¾ the distance of the edge 9 from the edge 8 is also measured, the same measurement can very accurately determine not only tha presence of a glass ribbon 10 in given zones 7 of the annealing lehr 11 and the width of the glass ribbon 10 , but also the position of the glass ribbon 10 inside the annealing lehr. If the beam of light 5 periodically scans between the reference point 28 and the edge 8 , the position of the glass ribbon. inside the annealing lehr 11 can be constantly monitored and indicated by the indicating device 24.

Lastly, in the construction illustrated in Fig. 5 i the laser light source 20 is disposed on a device 29 which can be pivoted around a point 30 analogous with the fixed transmitting point 19 of figures 3 and k.

In the apparatus illustrated in Fig. 5 a reference point is given by a contact (not shown) which the pivoting device 29 actuates at one limit of its pivoting movement. As soon as the contact is made, a pulse is transmitted to the timing device 2k (not shown in Fig. 5 ) · When the beam of light 5 has been pivoted through the angle alpha and impinges on the edge 9 i it is deflected there arid passes in the form of a deflected beam of light 26 to the measuring detector 21 which, on detection of the beam of light 26 , transmits a pulse to the timing device to. terminate time measurement.

The measured interval in time between the pulse from the contact and the pulse from the measuring detector 21 is again the measurement of the angle alpha swept by the beam of light from the reference point to the edge 9· Once again, as in the cases described hereinbefore, the angle alpha is a measurement of the position of the edge 9 of the glass ribbon 10 in relation to the reference point, (here given by the contact,) since the distances between the pivoting point 30 of the pivoting device 29 and the vertical axis of the annealing lehr 11 and also the main plane of the glass ribbon 10 are known.

Claims

1. 43293/2 WHAT IS CLAIMED IS: l.i A method of detecting whether a given zone is occupied by a margin of e a transparent sheet or ribbon wherein a beam of light rays to which the sheet or ribbon is at least partially transparent is directed to said sheet or ribbon and wherein the emergent light rays are detected, characterised in that the light rays enter the margin after travelling in a direction across and at an acute angle to one side of the sheet or ribbon, said incident rays being totally re lec ed by the inner face of the edge of said sheet or ribbon whereafter said light rays emerge from said margin to travel in a direction across and at an acute angle to the other side of said sheet or ribbon* and in that the existence of rays which thus emerge is detected.> 2. A method according to Claim 1, characterised in that said light beam is caused to scan said zone.* 3oi A method according to Claim 2 applied for detecting whether either or both o two given zones is or are occupied by one or the other of two opposite edge portions which belong to a transparent sheet or ribbon having a predetermined spatial orientation» such edge portions having j ' geometries fulfilling certain conditions, characterised in that said light beam is caused to scan both said zones.! 4. A method according to any preceding claim applied for detecting whether either or both of two given zones is or are occupied by; one or the other of two opposite edge portions which belong to a transparent sheet or ribbon having a predetermined spatial orientation, such edge portions having geometries fulfilling certain conditions, characterised in that the light rays projected into both said zones are emitted from a common source and in that deflected rays emergent from both said zones are detected at a single position. 5. A method according to claims 3 and 4, characterised in that light rays which would otherwise pass straight to the detection position through a part of the sheet or ribbon located between said edge portions are screened off. 6. A method according to claim 5 i characterised in that said light beam is displaced without interruption for scanning both said zones in succession and in that the time interval between successive detections of deflected light rays is measured. 7. A method according to any preceding claim, characterised in that said beam of light is caused to scan at least one said zone and a reference signal is generated at at least one predetermined point in such scanning movement, and in that the time interval between generation of said reference signal and detection of the existence of light rays deflected by a said edge portion is measured. 8. A method according to any preceding claim, character- ised in that the method is continuously applied while a said sheet or ribbon is in motion along a path comprising said zone or zones. 9. Apparatus for detecting whether a given zone is occupied by an edge portion which belongs to a transparent sheet or ribbon having a predetermined spatial orientation, said edge portion having a geometry fulfilling certain conditions characterised in that said apparatus comprises a support for supporting such sheet or ribbon with a said orientation, a projector for projecting a beam of light rays into said zone in a direction across and at an acute angle to one side of a sheet or ribbon ha-wing said orientation, and a detector arranged to detect the existence of deflected light rays emergent from said zone and travelling across and at an acute angle to the other side of such sheet or ribbon. 10. Apparatus according to claim 9i characterised in that said projector comprises means operative to cause, said light beam to scan said zone. 11. Apparatus according to claim 10, for detecting whether either or both of two given zones is or are occupied by one or the other of two opposite edge portions which belong to a transparent sheet or ribbon having a predetermined spatial orientation, such edge portions having geometries fulfilling certain conditions, characterised in that said project comprises means operative to cause said light beam to scan both said zones. 12. Apparatus according to any of claims 9 to 11, for detecting whether either or both of two given zones is or are occupied by one or the other of two opposite edge portions which belong to a transparent sheet or ribbon having a predetermined spatial orientation, such edge portions having. geometries fulfilling certain conditions, characterised in that said projector is operative to project light rays into both said zones, and said detector is arranged to detect the existence of deflected light rays emergent from both said zones . 13. Apparatus according to. claims 11 and 12, characterised in that the apparatus cpmprises a screen located between the projector and the detector. 14. Apparatus according to .claim 13, characterised in that said projector. is operative to cause said light beam to scan both said zones in succession . without interruption and said detector comprises timing means for measurin .the time interval between successive detections of deflected light rays. 15. Apparatus according to any of claims 9 to l¾, characterised in that said projector comprises means operative to cause said light beam to scan at least one said zone and in that the apparatus further cpmprises a generator for generating a reference signal at a least one predetermined point in such scanning movement, there being further provided means for measuring the time interval between generatio of such reference signal and detection of the existence of light rays deflected, b a said edge portion. 16. Apparatus according to amy of claims 9 tp 15, characterised in that said support is a conveyor, and the apparatus is adapted to operate continuously during movement of a sheet or ribbon along the conveyor. 17. A method of detecting whether a given zone is dccupied by an edge portion of a transparent sheet substantially as herein described. 18. Apparatus for detecting whether a given zone is occupied by an edge portion of a transparent sheet substantially as herein described.