US3843264A

US3843264A - Process and apparatus for determining the presence,in a given area of the edge of a sheet or of a ribbon of transparent material

Info

Publication number: US3843264A
Application number: US00397931A
Authority: US
Inventors: J Josse; M Bodart; J Declaye; R Albert
Original assignee: Glaverbel Belgium SA
Current assignee: AGC Glass Europe SA; Glaverbel Mecaniver SA
Priority date: 1972-10-03
Filing date: 1973-09-17
Publication date: 1974-10-22
Anticipated expiration: 1991-10-22
Also published as: GB1429544A; FR2203979B1; IL43293A; TR17870A; AT363628B; ES195942U; JPS5623085B2; NL7313100A; FI53040C; IT1004562B; NO141280C; ATA824273A; LU66220A1; FR2203979A1; ES195942Y; SE395961B; IE38281B1; AU6070773A; IL43293A0; DK141385C

Abstract

Method and apparatus for detecting whether either or both of two given zones is occupied by one or the other of two opposite edge portions of a transparent sheet or ribbon having a predetermined spatial orientation, the edge portions having a geometry fulfilling certain conditions, the method comprising the steps of supporting a sheet or ribbon with the aforesaid orientation, projecting a beam of light rays into the zones in a direction across and at an acute angle to one side of the supported sheet or ribbon and detecting the existence of light rays emergent from the zones deflected by edge portions therein and travelling across and at an acute angle to the other side of such supported sheet or ribbon; the apparatus comprising a support, a projector, and a detector for carrying out the aforesaid steps.

Description

United States Patent [19] Jesse et al.

[451 Oct. 22, 1974 PROCESS AND APPARATUS FOR DETERMINING THE PRESENCE, IN A GIVEN AREA OF THE EDGE OF A SHEET OR OF A RIBBON OF TRANSPARENT MATERIAL [75] Inventors: Jean Josse, Fosses-la-Ville; Joseph Declaye, Moustier sur Sambre; Roger Albert, Chatelet; Marcel Bodart, Namur, all of Belgium [73] Assignee: Glaverbel-Mecaniver Chaussee de La Hulpe, Boitsfort, Belgium 22 Filed: Sept. 17,1973 21 Appl.No.: 397,93l

[30] Foreign Application Priority Data Oct. 3, 1972 Luxembourg 66220 [52] US. Cl 356/199, 250/560, 250/561, 7 250/571, 356/160 [51] Int. CL. G0lb 11/04, GOlb ll/10,G01n 21/30 [58] Field of Search 356/199, 160; 250/560, 250/561, 571

[56] References Cited UNITED STATES PATENTS 3,307,446 3/l967 Rottman 250/560 3,495,089 2/1970 Brown 356/199 3,652,863 3/1972 Gaskell 250/571 FOREIGN PATENTS OR APPLICATIONS l,l2l,l70 l/l962 Germany 250/560 Primary Examiner-James W. Lawrence Assistant Examiner-T. N. Grigsby Attorney, Agent, or Firm-Cushman, Darby & Cushman [5 7 1 ABSTRACT Method and apparatus for detecting whether either or both of two given zones is occupied by one or the other of two opposite edge portions of a transparent sheet or ribbon having a predetermined spatial orientation, the edge portions having a geometry fulfilling certain conditions, the method comprising the steps of supporting a sheet or ribbon with the aforesaid orientation, projecting a beam of light rays into the zones in a direction across and at an acute angle to one side of the supported sheet or ribbon and detecting the existence of light rays emergent from the zones deflected by edge portions therein and travelling across and at an acute angle to the other side of such supported sheet or ribbon; the apparatus comprising a support, a projector, and a detector for carrying out the aforesaid steps.

20 Claims, 5 Drawing [Figures PROCESS AND APPARATUS FOR DETERMINING THE PRESENCE, IN A GIVEN AREA OF THE EDGE OF A SHEET OR OF A RIBBON OF TRANSPARENT MATERIAL The present invention relates to a method of detecting whether a given zone is occupied by an edge portion of 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 not exclusive reference to detecting the presence of such an edge portion of a glass sheet or ribbon in a given zone during manufactureof 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 sheet 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 connection 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 characterized in that a beam of light rays is projected into said zone in a direction such that, when a sheet or ribbon having the aforesaid predetermined orientation and edge portion of said geometry is present in said zone, the light rays enter the edge portion after travelling 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 in 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 existenceof rays which thus emerge is detected.

The method according to the present invention has the advantage that it enables such detection in respect of transparent sheets or ribbons to be performed rapidly and accurately without physical contact with the edge portion if present. Also, the required detection may take place at positions well spaced from the sheet or ribbon, e.g., at a distance of several meters 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, the light beam is caused to scan the zone, so that regular indications of the presence of such an edge portion in said zone may be obtained.

The method according to the invention also contemplates detecting whether either or both of two given zones is or are occupied by one or the other of two opposite edge portions of a transparent sheet or ribbon having a predetermined spatial orientation, such edge portions having geometries fulfilling certain conditions. This detection is achieved by causing the light beam 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 of a transparent sheet or ribbon having a predetermined orientation, such edge portions having geometries fulfilling certain conditions, and the light rays which are projected into both said zones are emitted from a common source and the deflected rays emergent from both said zones are detected at a single position, have the advantage that information about the presence of 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 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 of the existence of light rays deflected by an associated edge portion is measured.

It is advantageous if the method is continuously applied while a 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 of a transparent sheet or ribbon having a predetermined spatial orientation, said edge portion having a geometry fulfilling certain conditions, preferably comprises a support for supporting such sheet or ribbon with 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 light rays emergent from said zone deflected by an edge portion and travelling across and at an acute angle to the other side of such sheet or ribbon.

This apparatus has many advantages. It is extremely simple, and may be contained wholly within the projected plan areaof the sheet orcribbon, thus saving 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 of a transparent sheet or ribbon having a predetermined spatial orientation, such edge portions having geometries fulfilling certain conditions, are characterized 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 existance 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 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 continuously during movement of a sheet or ribbon along the conveyor.

. Various embodiments of 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. 4 shows another embodiment of apparatus according to the invention; and

FIG. 5 illustrates a further 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 FIG. 2 there is shown a glass ribbon 3 having an edge face 4 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 I and the ribbon 3, 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 of 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 detected 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 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 eachof 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 Iehr 11. The glass ribbon 10 moves substantially in the main median plane of the annealing lehr ll perpendicularly to the plane of the drawing. The annealing lehr 11 has a bottom 12, side walls 13, and a roof 14. The bottom 12 and roof 14 of the annealing lehr 11 have

lighttransmitting regions

15 and 16 respectively through which an incident beam of light 5 and also deflected

beams

6, 26 of light can pass. Lying in the mid-plane l7 perpendicular to the glass ribbon l0 and below the ribbon is a rotary mirror 18 analogous to that of a mirror galvanometer located at a transmitting point 19 on the path of a beam of light emitted by a laser 20. This beam of light 5 is caused to scan by the rotation of the rotary mirror 18 over a zone which extends to either side beyond the

edges

8, 9 of the ribbon 10.

The incident beam of light 5 is 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 shown in the vertical plane 17 of the ribbon l0 and on reception 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 24 which constantly indicates the measuring results. If the rate of rotation of the mirror 18 is known, the speed of scanning is known, and hence the indicating apparatus 24 may be calibrated to give a direct reading of the width of the ribbon 10.

Disposed between the glass ribbon l0 and the detector 21 is a screen 25 so wide that when the beam of light 5 is caused to scan, only the 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 10 during intermediate portions of the scanning period, is screened from the detector. The screen 25 can be omitted if the roof 14 and/or the bottom 12 of the annealing Iehr 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 incident beam of light 5 scans the ribbon 10 at a constant frequency. As soon as the beam oflight 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 during its scan at the opposite edge 9, 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 position and extent of each of these zones 7 are determined by the position and extent of the associated transparent regions l5, 16 of the annealing lehr 11, 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 H6. 4 like elements have like references to those in FIG. 3, but only that part of the measuring 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 and 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 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.

lf with the apparatus illustrated in FIG. 4 the distance of the edge 9 from the edge 8 is also measured, the same measurement can vary accurately determine not only the 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 l0 inside the annealing lehr 11 can be constantly monitored and indicated by the indicating device 24.

Lastly, in the construction illustrated in FIG. 5, 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 FIGS. 3 and 4.

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 24 (not shown in FIG. 5). When the beam of light 5 has been pivoted through the angle alpha and impinges on the edge 9, it is deflected there and 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.

It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodiment has been shown anddescribed for the purpose of illustrating the functional and structural principles of this invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

What is claimed is:

l. A method of detecting whether a given zone is occupied by an edge portion of a transparent sheet or ribbon having a predetermined spatial orientation, said edge portion having a geometry fulfilling certain conditions, said method comprising the steps of projecting a beam of light rays into said zone in a direction such that, when a sheet or ribbon having said predetermined orientation and an edge portion of a said geometry is present with its edge portion in said zone, the light rays enter the edge portion after travelling 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 in a direction across and at an acute angle to the other side of said sheet or ribbon. after deflection by said edge portion, and detecting the existence of rays which thus emerge after deflection by said edge portion.

2. A method according to claim 1, wherein said light beam is displaced to scan said zone.

3. A method according to claim 2, wherein said beam of light rays is projected into a second zone during the scanning displacement in a direction such that, when said sheet or ribbon having said predetermined orientation and an opposite edge portion of said geometry is present with its opposite edge portion in said second zone, the light rays enter the opposite edge portion after travelling in a direction across and at an acute angle to one side of the sheet or ribbon and light rays emerge from said opposite edge portion to travel in a direction across and at an acute angle to the other side of said sheet or ribbon after deflection by said other edge portion, and the existence of rays which thus emerge after deflection by said other edge portion is detected.

4. A method according to claim 3, wherein the light rays emergent after deflection by both of said edge portions are detected at a single position.

5. A method according to claim 4, wherein the 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, wherein said light beam is displaced without interruption to effect the scanning of both said zones in succession and the time interval between successive detections of emergent light rays is measured.

7. A method according to claim 6, wherein said sheet or ribbon is continuously moved along a path in which said zones are located during said projecting, detecting, and measuring steps.

8. A method according to claim 5, wherein a reference signal is generated at at least one predetermined point in the scanning beam of said light displacement and the time interval between the generation of said reference signal and the detection of the existence of emergent light rays deflected by an associated edge portion is measured.

9. A method according to claim 8, wherein said sheet or ribbon is continuously moved along a path in which said zones are located during said projecting, detecting. and measuring steps.

10. A method according to claim 3, wherein said sheet or ribbon is continuously moved along a path in which said zones are located during said projecting and detecting steps.

11. A method according to claim 1, wherein said sheet or ribbon is continuously moved along a path in which said zone is located during said projecting and detecting steps.

12. Apparatus for detecting whether a given zone is occupied by an edge portion of a transparent sheet or ribbon having a predetermined spatial orientation, said edge portion having a geometry fulfilling certain conditions, said apparatus comprising support means for supporting a sheet or ribbon with said orientation, projector means 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 supported by said support means, and detector means for detecting the existence of light rays emergent from said zone deflected by an edge portion therein and travelling across and at an acute angle to the other side of the sheet of ribbon supported by said support means.

13. Apparatus according to claim 12 wherein said projector means includes means for causing said light beam to scan said zone.

14. Apparatus according to claim 13 wherein said support means comprises a conveyor for continuously moving a sheet or ribbon along a path in which said zone is located.

15. Apparatus for detecting whether either or both of two given zones is occupied by one or the other of two opposite edge portions of a transparent sheet or ribbon having a predetermined spatial orientation, said edge portions having a geometry fulfilling orientation, said edge portions having a support means for supporting a sheet or ribbon with said orientation, projector means for projecting a beam of light rays into said zones in a direction across and at an acute angle to one side of a sheet or ribbon having said orientation supported by said support means and detector means for detecting the existence of light rays emergent from said zones deflected by edge portions therein and travelling across and at an acute angle to the other side of such sheet or ribbon supported by said support means.

16. Apparatus according to claim 15, wherein said projector means includes means for causing said light beam to scan said zones.

17. Apparatus according to claim 16, including a screen located between said projector means and said detector means.

18. Apparatus according to claim 17, wherein said scanning means is operable to cause said light beam to scan both said zones in succession without interruption and said detector means includes means for measuring the time interval between successive detections of deflected light rays.

19. Apparatus according to claim 17, including generator means for generating a reference signal at at least one predetermined point in the scanning movement of said light beams, said detector means including means for measuring the time interval between the generation of such reference signal and detection of the existence of light rays deflected by an associated edge portion.

20. Apparatus according to claim 19, wherein said support means is a conveyor for continuously moving a sheet or ribbon along a path in which said zones are located.

Claims

1. A method of detecting whether a given zone is occupied by an edge portion of a transparent sheet or ribbon having a predetermined spatial orientation, said edge portion having a geometry fulfilling certain conditions, said method comprising the steps of projecting a beam of light rays into said zone in a direction such that, when a sheet or ribbon having said predetermined orientation and an edge portion of a said geometry is present with its edge portion in said zone, the light rays enter the edge portion after travelling 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 in a direction across and at an acute angle to the other side of said sheet or ribbon after deflection by said edge portion, and detecting the existence of rays which thus emerge after deflection by said edge portion.