NO141280B - METHOD AND APPARATUS FOR REGISTRATION IF A GIVEN ZONE IS CONCERNED BY AN EDGE PART OF A TRANSPARENT PLATE OR A TRANSPARENT BAND - Google Patents

Abstract

Method and apparatus for detecting whether a given zone is occupied by an edge portion of a transparent plate or band.

Description

The present invention relates to a method for registering whether a given zone is occupied by an edge part belonging to a transparent plate or a transparent band with "predetermined orientation in space, the edge part having a geometric shape that meets certain criteria, as well as an apparatus for use during the implementation of the aforementioned procedure.

The invention relates in particular, but is not excluded, to registration of such an edge part of a glass plate or a glass strip in a given zone - during the manufacture of the glass. This information is particularly important for quality control.

It is known to send light rays along the boundaries of such a given zone, so that one knows that the edge portion is in the zone when one of the rays is obstructed by an opaque plate edge portion, while the other beam is allowed to pass. This method is clearly not appropriate in connection with transparent plates or strip sections, since both rays would be able to pass whether such an edge section was in the zone or not.

The invention is to provide such a method which makes it possible to register the presence of such an edge part in the given zone without physical contact with the plate or tape edge, because such contact could impair the quality of the edge and because of the risk of damage to the recording equipment , if a discontinuity suddenly occurs at the edge.

The method according to the present invention is therefore characterized by a bundle of light rays being sent into said zone in such a direction that the light rays, if a plate or a band with said orientation and with an edge portion of said geometric shape is present in the zone, will enter the edge portion after to have traveled in a direction across and at an acute angle to one side of the plate or tape, and that light rays emerge from said edge portion to travel in a direction across and at an acute angle to the other side of said plate or strip after deflection due to the aforementioned edge section, and that the occurrence of steel thus exiting is recorded.

The method according to the present invention has the advantage that it makes it possible to carry out such registration with a view to transparent plates or tapes in a fast and accurate manner without physical contact with the edge portion that may be present. The necessary registration can also take place from positions at a good distance from the disc or tape, e.g. at a distance of several meters. The method can be used in situations where the plate or tape is very hot without overheating the device used to carry out the method. This method can e.g. used for control in the production of flat glass, e.g. in the tempering furnace for a glass drawing machine.

Preferably, the light beam is brought to scan said zone, so that regular indications of the possible occurrence of such an edge portion in the zone can be obtained.

The method according to the invention is preferably used for recording whether one or both of two given zones are occupied

of one or the other of two opposite edge parts that belong to a transparent plate or a corresponding band that has a predetermined orientation in space, these edge parts having geometric shapes that meet certain criteria. The method is then distinguished by the fact that the light beam is brought to scan both zones. In this way, information about the presence of the opposite edge portions of plate or tape can be obtained without doubling the necessary light beam projector apparatus.

Devices where the method is used for recording whether one or both of two given zones are occupied by one or the other of two opposite edge parts belonging to a transparent plate or strip with a predetermined orientation, where said edge parts have geometric shapes that meet certain criteria, and which is distinguished by the fact that the light rays sent into both mentioned zones are sent from a common source and by the fact that the deflected rays emerging from both mentioned zones are registered in a single position, has the advantage that information about the presence of the opposite edge parts of the plate or the band can be obtained without doubling the required light beam recording apparatus.

Light rays which would otherwise pass directly to the recording position through a part of the plate or tape which lies between the mentioned edge parts are preferably shielded, so that the recording of any deflected rays is not disturbed by the transmitted beam bundle.

When said light beam bundle is moved without interruption to scan both zones in turn and the time interval between successive registrations of deflected light beams is measured, the width of the plate or band can be easily determined. This is a particularly valuable move.

Preferably, the beam beam is brought to scan at least one such zone and a reference signal is elicited at at least one predetermined point by such a scanning movement and the time interval between the elicitation of said reference signal and the registration of the presence of light rays deflected by said edge portion is measured .

It is advantageous if the method is carried out continuously while said plate or band is in motion along a path that includes said zone or zones, as any change in the position of one or both edges of the plate or band can then be immediately registered.

An apparatus according to the invention for recording about a

given zone is occupied by an edge portion belonging to a transparent plate or strip with a predetermined orientation in space, where said edge portion has a geometric shape that meets certain criteria, is characterized by the device comprising a base for supporting such a plate or a band with an orientation as mentioned, a projector for projecting a beam of light into said zone in a direction transverse to

and at an acute angle to one side of the plate or tape with said orientation, and a detector arranged for recording deflected light rays emerging from said zone and moving across and at an acute angle to the other side of the plate or tape.

This device has many advantages. It is extremely simple and can be placed within the planned area of the plate or tape, and is thus space-saving. The apparatus can be easily adapted for recording the occurrence of a plate or tape edge part in a large variety of given zones, simply by setting the projector and the detector in corresponding directions without them having to be moved otherwise.

Preferably, the projector comprises means that can be influenced to bring the light beam to scan said zone. The special advantages of this and other preferred features of the apparatus according to the invention will be clear from the advantages mentioned above in connection with corresponding preferred features of the method according to the invention.

Preferred embodiments of an apparatus according to the invention for recording whether one or both of two given zones are occupied by one or two opposite edge parts belonging to a transparent plate or a transparent band with a predetermined orientation in space, where the edge parts have geometric shapes that fulfill certain criteria, is distinguished by the fact that the projector includes organs that can be influenced to bring the light beam to scan both zones.

The projector can advantageously be made to send light rays into both zones and the detector is arranged so that it registers the occurrence of deflected light rays emerging from both zones.

Preferably, the apparatus comprises a screen arranged between the projector and the detector.

Embodiments where said projector can be brought to

allowing the light beam to scan both zones in turn without interruption and where the detector comprises means for measuring the time interval between successive registrations of deflected light beams, is preferred as they make it possible to measure the width of the plate or band.

The projector advantageously comprises means which can cause the light beam to scan at least one zone and the apparatus further comprises a generator for generating a reference signal at at least one predetermined point in such a scanning movement, further means being provided for measuring the time interval between the generation of such a reference signal and the recording of the occurrence of light rays deflected by an edge portion as mentioned.

The substrate is preferably a conveyor and the apparatus is adapted for continuous operation during the movement of a plate or a belt on the conveyor.

Different embodiments of the invention will now be described with reference to the schematic drawings, where Figures 1 and 2 illustrate the path of a light beam in the zone of an edge part of a transparent plate which has a flat edge and a curved edge respectively,

figure 3 illustrates an embodiment of the apparatus for carrying out a method according to the invention,

Figure 4 shows another embodiment of an apparatus according to the invention, and

figure 5 illustrates a further embodiment of an apparatus according to the invention.

Figure 1 shows a glass plate 1 with a rectilinear edge surface 2 which extends at right angles to the main plane of the plate 1. In Figure 2, the glass band 3 has an edge surface 4 which has a rounded shape like a half-circle and whose middle perpendicular coincides with the main plane of the band 3.

When an incident light beam 5 enters the glass, both

at the plate 1 and the band 3, it is deflected from its original direction by refraction and extends inside the glass as far as the rectilinear edge surface 2 of the plate 1 or the curved edge surface 4 of

the band 3. The light beam 5 is, so to speak, completely reflected back into the glass at the edge floats 2 and 4, and the deflected light beam 6 passes to the next boundary between the glass and its surroundings and is there again deflected from its direction by refraction.

The occurrence of a deflected light beam 6 is registered using the method according to the invention. The deflected light beam 6 is strongly deflected in relation to the incoming light beam 5 and can be registered without risk of interference from the incoming light beam.

Figure 3 shows an apparatus according to the invention for recording whether one or both of two given zones 7 are occupied by one or the other of two opposite edge parts 8, 9 of a glass strip 10 in a tempering furnace 11. The glass strip 10 is moved essentially in the main center plane of the tempering furnace perpendicular to the plane of the drawing. The hardening furnace 11 has a bottom 12, side walls 13 and a roof 14. The bottom 12 and the roof 14 of the hardening furnace 11 have light-permeable parts 15 and 16, respectively, through which an incident beam 5 and deflected beam beams 6, 26 can pass. In the middle plane 17, perpendicular to the glass band 10 and below the band, there is a rotating mirror 18, analogous to a mirror galvanometer placed at the sending point 19 in the path of a beam beam sent out by a laser 20. This beam beam 5 is brought by the rotation of the rotating mirror 18 to to scan over a zone extending to both sides past the edges 8, 9 of the band 10.

The incident light beam 5 is reflected and refracted at the inner surfaces of each edge 8, 9 during the scan and the deflected light beams 6, 26 return to the vertical plane 17 and together with the band 10 form angles which essentially correspond to the angle formed by the incident light beam with the band 10 at the edges.

A photoelectric detector 21 which receives the deflected light beams 6, 26 at the moments when they pass through the reference points 22 is also shown in the vertical plane 17 of the band 10. Upon receiving a deflected light beam, this detector emits an electric pulse.

The detector 21 is connected to a timing device 23 which measures the time interval between successive pulses. An indicator 24 which constantly indicates the measurement results is connected to the timing device 23. If the rotation speed of the mirror 18 is known, the scanning speed is known and the indicator 24 can therefore be divided which gives a direct reading of the width of the band 10.

Between the glass strip 10 and the detector 21 is arranged

a screen 25 which is wide enough so that only the light rays 6, 26,

which is reflected by the edges 8, 9 can reach the detector when a light

beam 5 scans, while the incident light beam 5 which otherwise passes through the glass strip 10 during intermediate periods of the scanning period, is shielded from the detector. Screen 25

can be dispensed with if the roof 14 and/or the bottom 12 of the hardening oven 11 has a central part which is opaque and shields the detector sufficiently against the incident light beam 5 during this scanning period.

The rotating mirror 18 is preferably swung backwards and forwards at a constant speed, so that the incident beam 5 scans the band 10 at a constant frequency. As soon as the light beam 5 hits the edge 8, it is deflected there and the light beam 6 which is deflected by the edge 8 goes to the detector 21, where a pulse is generated which sets the timing device 23 in motion. As soon as the incident light beam 5 during its scanning encounters the opposite edge 9, it is deflected again and the light beam 26 which is deflected by the edge 9 also goes to the detector 21 and induces a second pulse there which stops the device 23. The interval between the two pulses is a measure of the width of the glass band 10, the distance between the edges 8, 9' can be determined from the measured time interval and the known rotation speed of the rotating mirror 18 in connection with its distance from the main plane of the glass band 10.

The apparatus illustrated in figure J> induces a pulse at the detector 21 when the light beam 5 is deflected by the edges 8, 9 of the band 10, provided that the respective edge is located in one of the given zones f. The position and extent of these zones 7 is determined by the position and extent of the various transparent areas 15, 16 of the tempering furnace 11 and of the screen 25.

In order for a pulse to be induced in the detector 21, it is also necessary that the respective edges 8, 9 of the glass band have a geometric shape which causes deflection of the beam to the desired degree. Certain lenticular and prismatic shapes will not cause such deflection, but in practice these shapes do not occur in a strip moving through a tempering furnace.

In Figure 4, the same bodies are denoted by the same reference numbers as in Figure 3, but here only the part of the measuring device which belongs to the edge 9 is shown.

Above the main plane of the glass strip 10 is seen in the drawing a reference detector 27, arranged to receive light passing through a reference point 28 arranged at such a distance from the vertical plane 17 that the light beam 5 sent from the transmitting point 19

on the rotating mirror impinges on the reference detector 27 without passing through the glass strip 10. The reception of this beam causes the detector 27 to send a pulse to the timing device 23 which initiates timing there. When scanning from the reference point 27 to the edge of the band 10, the incident light beam 5 travels an angle alpha. As soon as the light beam 5 has swept this angle alpha, it is deflected at the edge 9 as discussed above, and the light beam 26 which is deflected by the edge 9> is received by the detector 21 which then sends a pulse to the timing device 23 and stops the timing. The time interval measured by the device 23 between the pulse from the reference detector 27 and the pulse from the measurement detector 21

is a measurement of the value of the angle alpha, since both the distance from the transmission point 19 on the rotating mirror 18 from the glass band 10 and the scanning speed are known. Since the distance between the reference point 28 and the main plane of the glass strip 10 and the vertical plane 17, which is also the vertical center plane of the tempering furnace 11, is also known, the exact position of the edge 9 in the tempering furnace is indicated by the value of the angle alpha.

If one also measures the distance between the edge 9 and the edge 8 with the device according to Figure 4, the same measurement can very accurately determine not only the presence of a glass band 10 in a given zone 7 of the tempering furnace 11 and the width of the glass band 10, but also the position of the glass strip 10 inside the tempering oven. If the light beam 5 periodically scans between the reference point 28 and the edge 8, the position of the glass strip 10 inside the tempering furnace 11 can be constantly monitored and indicated using the indicator 24.

In the construction illustrated in Figure 5, the laser light source 20 is arranged on a device 29 which can be pivoted around a point 30 analogous to the fixed transmission point 19 in Figures 3 and 4.

In the apparatus shown in Figure 5, a reference point is provided

by a contact not shown which the swinging device 29 affects

at a limit to its swing motion. As soon as the contact is made, a pulse is sent to the timing device 24 (not shown in figure 5) - When the light beam 5 has swept through the angle alpha and hits the edge 9, it is deflected there and passes in the form of a deflected light beam 26 to the measuring detector 21 which, upon registration of the light beam 26, sends a pulse to the timing device for stopping the timing. The measured time interval between the contact pulse and the pulse from the measurement detector 21 in turn constitutes the measurement value of the angle alpha that the light beam swept from the reference point to the edge 9. As in the cases discussed above, the angle alpha constitutes a value of the position of the edge 9 of the glass strip 10 in relation to the reference point (here given at the contact), as the distance between the pivot point 30 of the device 29 and the vertical axis of the tempering furnace 11 as well as the main plane of the glass strip is known.

Claims (16)

Procedure for registration, if a given zone is occupied by an edge part belonging to a transparent plate or a transparent band which has a predetermined orientation in space, whereby said edge part has a geometric shape that fulfills certain criteria, characterized in that a light beam bundle is sent into said zone in such a direction that if a plate or tape has said orientation and has an edge portion with said geometric shape present in said zone, the light rays will enter the edge portion after traveling in a direction across and at an acute angle to one side of the plate or band and light rays will emerge from said edge portion to move in a direction across and at an acute angle to the other side of said plate or band after deflection at said edge portion and by the occurrence of rays that appear like this are recorded. 2. Method as stated in claim 1, characterized in that the light beam bundle is brought to scan said zone. 3. Procedure as stated in claim 2, used for registration) if one or both of two given zones are occupied by one or the other of two opposite edge parts belonging to a transparent plate or a transparent band that has a predetermined orientation in the room and where the edge parts have a geometric shape that meets certain criteria, characterized by the fact that the beam of light is brought to scan both zones. 4. Procedure as stated in one of the preceding claims used for registration, if one or both of the given zones are occupied by one or the other of two opposite parties belonging to a transparent plate or a transparent tape that has a prior fixed orientation in the room and where the edge parts have a geometric shape that meets certain criteria, characterized by the fact that the light rays sent into both mentioned zones are sent from a common source and that deflected rays emerging from both mentioned zones are registered in a single position. 5. Method as specified in claims 3 and 4-, characterized in that light rays which would otherwise pass straight at the registration position through a part of the plate or tape which is located between said edge parts, are shielded. 6. Method as stated in claim 5, characterized in that the light beam bundle is shifted without interruption to scan both mentioned zones in turn and in that the time interval between successive registrations of deflected light beams is measured. 7. Method as stated in one of the preceding claims, characterized in that said light beam bundle is caused to scan at least one of the zones and a reference signal is evoked at at least one predetermined point in such a scanning movement, and in that the time interval between the elicitation of the reference signal and the recording of the occurrence of light rays deflected by the edge portion is measured. 8. Method as specified in one of the preceding claims, characterized in that the method is used continuously while a plate or a band as specified is in motion along a path comprising said zone or zones. 9. Apparatus for use in the method according to one or more of the preceding claims, for recording whether a given zone (7) is occupied by an edge part (8, 9) belonging to a transparent surface or a transparent band (10) which has a predetermined orientation in space, whereby the edge part (8, 9) has a geometric shape that meets certain criteria, characterized in that the device comprises a base for supporting a plate or a band (10) with an orientation as mentioned, a projector (20) for emitting a beam of light (5) into the zone (7) in a direction across and at an acute angle to one side of a plate or strip (10) with an orientation as mentioned, and a detector (21) arranged for recording the occurrence of deflected light rays (6, 26) which emerge from the zone (7) and travel across and at an acute angle towards the other side of the plate or band (10). 10. Apparatus as stated in claim 9, characterized in that the projector (20) comprises organs (18, 29) which can bring the light beam bundle (5) to scan the zone (7). 11. Apparatus as specified in claim 10, for recording whether one or both of two specified zones (7) is occupied by one or the other of two opposite edge parts (8, 9) belonging to a transparent plate or a transparent strip (10) with a predetermined orientation in space, and where the edge portions (8, 9) have geometric shapes that meet certain criteria, characterized in that the projector (20) comprises means (18) for bringing the light beam beam to scan both zones (7) . 12. Apparatus as specified in one of claims 9-11, for recording whether one or both of two given zones (7) is occupied by one or the other of two opposite edge parts (8, 9) belonging to a transparent plate or a transparent band (10) with a predetermined orientation in space, whereby the edge parts (8, 9) have geometric shapes that meet certain criteria, characterized in that the projector (20) can be driven so that it sends light rays (5) into in both zones and that the detector (21) is arranged so that it registers the occurrence of deflected light rays (26) that exit both zones. 13. Apparatus as stated in claims 11 and 12, characterized in that the apparatus comprises a screen (25) arranged between the projector (20) and the detector (21). 14. Apparatus as stated in claim 13, characterized in that the projector (20) can be operated so that it causes the light beam (5) to scan both zones (7) in turn without stopping and that the detector (21) includes timing devices (23) ) for measuring the time interval between successive registrations of deflected light rays. 15. Apparatus as stated in one of the claims 9-14, characterized in that the projector (201) comprises means (18) which can be driven to bring the light beam to scan at least one of the zones and in that the apparatus also comprises a generator (27) for generation of a reference signal at at least one predetermined point in the scanning movement, further being provided for means (23) which measure the time interval between the generation of the reference signal and the registration of the occurrence of light rays deflected by the edge portion. 16. Apparatus as stated in one of claims 9-15, characterized in that the substrate is a conveyor and that the apparatus is adapted for continuous operation during the movement of a plate or a belt (10) along the conveyor.