OPTICAL DEVICES FOR CALIBRATING, AND FOR ANALYZING THE QUALITY OF A GLAZING, AND METHODS

Abstract

An optical device comprises a first polariscope and a set of first photodetectors and an optical retardation generator. The device is configured to analyze the quality of a glazing.

Claims

1. An optical device comprising a first polariscope including in this order, in an optical alignment along an optical axis: a first, preferably polychromatic, light source with a given spectrum, placed orthogonal to the optical axis and delivering configured to deliver a light beam; a first circular polarizer that polarizes in a first polarization rotation direction, placed orthogonal to the optical axis and including a first linear polarizer followed by a first quarter waveplate; a first analyzer, which is a circular polarizer that polarizes in a second polarization rotation direction that is opposite to the first polarization rotation direction, placed orthogonal to the optical axis, said first analyzer including a second quarter waveplate followed by a second linear polarizer; downstream of the first analyzer and in said optical alignment, a first digital sensor, placed orthogonal to the optical axis, and a first objective, placed orthogonal to the optical axis and defining a focal plane, said first objective being located facing the first digital sensor, between the first analyzer and the first digital sensor; placed orthogonal to the optical axis, between the first polarizer and the first analyzer, and in said optical alignment, a calibrated first optical retardation generator for generating optical retardations in a range AB, the first optical retardation generator being in said focal plane; wherein the first digital sensor includes a set of first photodetectors that are sensitive to the spectrum of the first light source, having a given spectral response, one or more of the first photodetectors, which photodetectors are calibration photodetectors, being located facing the calibrated first optical retardation generator, each calibration first photodetector receiving, in succession, for each of said optical retardations in said range AB, light energy issued from the light beam that exits from the first analyzer, the first digital sensor then generating calibration digital images for said optical retardations in said range AB, each calibration digital image being formed, with one or more reference channels Ck, from one or more pixels representative of the spectral response of the one or more calibration first photodetectors; and in that wherein the optical device furthermore includes a first digital processing unit for processing all of the calibration digital images, said first processing unit forming a calibration database containing, for each optical retardation in the range AB, digital values Ik for each of the reference channels Ck, Ik being representative of the light energy collected by the one or more calibration first photodetectors.

2. The optical device as claimed in claim 1, wherein the calibrated first optical retardation generator includes an optical system made of birefringent material, chosen from: a set of calibrated static optical planar waveplates, the plates being interchangeable, each plate being inserted, in succession, into the optical device; or a system including first and second wedge-shaped plates made of birefringent material, the second plate being translationally movable with respect to the first plate, the compensator being defined by an aperture that is centered on the optical axis, the aperture being entirely illuminated by the first light source, the aperture being in said focal plane, one or more calibration first photodetectors facing the aperture.

3. (canceled)

4. The optical device as claimed in claim 2 wherein the aperture of the compensator is circular, of diameter O1, or the aperture of the compensator is of equivalent diameter O1 of diameter or of equivalent diameter of at most 30 mm, the center of the aperture is inscribed in a central disk of diameter O1/2, and the one or more calibration first photodetectors used are entirely facing said central disk of diameter or of equivalent diameter of at most 25 mm.

5. (canceled)

6. The optical device as claimed in claim 1 wherein the first optical retardation generator includes an entrance area that is illuminated by the light beam and that defines a calibration area of diameter or of equivalent diameter of at most 30 mm.

7. The optical device as claimed in claim 1, wherein the optical axis is vertical, and the first polariscope, the first digital sensor, the objective and the first optical retardation generator are on a heating and tempering line, downstream of the tempering system, the glazing not being run through the calibration zone, the line including a conveyor for conveying glazings along a conveying axis Y, the line optionally being a bending-tempering line, the first polariscope, the first digital sensor, the objective and the first optical retardation generator being downstream of the bending system.

8. The optical device as claimed in claim 7, wherein the conveyor includes two rollers that are spaced apart by an inter-roller space, the first light source is under the conveying zone, is between the two rollers and/or under the two rollers, said first light source optionally being on a source holder that is spaced apart from the ground, and the first digital sensor is linear and spaced apart from and above the two rollers.

9. The optical device as claimed in claim 7, wherein the conveyor includes two rollers that are spaced apart by an inter-roller space, and the first optical retardation generator is fastened on a mounting holder to the two rollers, said mounting holder having a hole facing the calibration area of the first optical retardation generator, which is the entrance area illuminated by the light beam.

10. The optical device as claimed in claim 1, wherein the first digital sensor is linear.

11. The optical device as claimed in claim 1, wherein the first light source forms a linear luminous strip and, lateral areas of the luminous strip are masked, a central area of the luminous strip illuminating the first optical retardation generator.

12. The optical device as claimed in claim 1, wherein that wherein the first digital sensor is a matrix-array sensor, the first photodetectors being arranged in a matrix array.

13. The optical device as claimed in claim 1, further comprising first collimating means downstream of the first light source and upstream of the first optical retardation generator and wherein the first objective is telecentric.

14. The optical device as claimed in claim 1, further comprising, between the first optical retardation generator and the linear first sensor, upstream of the first analyzer, a calibrated optical waveplate with a retardation A0 chosen in the zone in which the relationship between the value Ik and the optical retardation is substantially linear for at least one of the reference channels Ck.

15. (canceled)

16. A device for analyzing the quality of a glazing, said device including said first polariscope, the first digital sensor, the first objective and said calibration database of the optical device defined in claim 1, wherein, in operation, the glazing is between the first polarizer and the first analyzer, the optical axis is perpendicular to the plane tangential to the surface of the glazing in the illuminated area segment, and wherein each first photodetector of said set being able to receive light energy in the spectrum of the first light source, the first digital sensor then generates digital images that are quality-analysis digital images, each quality-analysis digital image being formed, with said reference channel(s) Ck, from one or more pixels that are representative of the spectral response of the first photodetectors, and wherein the device further includes a digital processing unit for processing all of the quality-analysis digital images, and all of the images of the optional second digital sensor, facing said illuminated area segment, forming a map of the optical retardations facing said illuminated area segment by means of the calibration database.

17. (canceled)

18. The device for analyzing the quality of a glazing as claimed in claim 16, wherein the optical axis is vertical, and the first polariscope and the first digital sensor are on a heating and tempering line, downstream of the tempering system, the line including a conveyor for conveying glazings along a conveying axis Y, the manufacturing line optionally being a heating, bending and tempering line, the first polariscope and the first digital sensor being downstream of the bending system, and wherein the first digital sensor is linear, the first photodetectors being in a row.

19. (canceled)

20. (canceled)

21. A line for heating and tempering that includes a conveyor for conveying glazings along a conveying axis Y, the line optionally being a bending-tempering line, and that includes, downstream of the tempering system, the optical device as claimed in claim 1, the glazing not being run through the calibration zone, and in case of bending, the first polariscope, the first digital sensor, the objective and the first optical retardation generators are downstream of the bending system.

22. (canceled)

23. (canceled)

24. A heating and tempering line that includes a conveyor for conveying glazings along a conveying axis Y, the line optionally being a bending-tempering line, and that includes, downstream of the tempering system, the quality-analyzing device as claimed in claim 16, wherein the first digital sensor is linear, the first photodetectors being in a row, and optionally the line is a heating, bending and tempering line, the first polariscope and the first digital sensor are downstream of the bending system, and in particular, in operation, the glazing is between the first polarizer and the first analyzer.

25. (canceled)

26. A method for manufacturing a glazing, comprising, in succession, forming the glazing, a heating operation and a tempering or bending-tempering operation followed by an analysis of the quality of the glazing using the analyzing device as claimed in claim 16.

27. The method for manufacturing a glazing as claimed in claim 26, wherein the analysis of the quality of the glazing is carried out on the heating and tempering line and leads to a warning or to stoppage of the manufacture and/or of the heating and/or of the line, and/or to feedback being generated on the parameters of the heating and/or tempering device.

28. (canceled)

29. A method for analyzing the quality of a glazing implemented subsequently to the calibrating method as claimed in claim 26, the glazing being between the first polarizer and the first analyzer.

30. The method for analyzing the quality of a glazing as claimed in claim 29, wherein the method is carried out on the heating and tempering line downstream of the temper, the glazing being movable over a conveyor of the line.

Description

[0223] The invention will be better understood on reading the following description, which is given merely by way of example, with reference to the appended drawings, in which:

[0224] FIG. 1 is a schematic cross-sectional view, in the X-Z plane, of an optical device 1000 according to the invention forming part of a tempering manufacturing line with a horizontal conveyor.

[0225] FIG. 1a is a schematic top view (in the horizontal X-Y plane) showing the conveyor with a mounting holder and the two apertures of two motorized Babinet-Soleil compensators used in the optical device 1000 of FIG. 1.

[0226] FIG. 1b is a schematic top view (in the horizontal X-Y plane) of a motorized Babinet compensator on a mounting holder used in the optical device 1000 of FIG. 1.

[0227] FIG. 1c is a schematic perspective view of two conveyor rollers and of the light source, and of the circular polarizer in the inter-roller space, used in the optical device 100 of FIG. 1.

[0228] FIG. 1d is a schematic perspective view showing the first circular analyzer, the first objective, the linear first camera and a mounting profile, used in the optical device 1000 of FIG. 1.

[0229] FIG. 1e is a schematic cross-sectional view, in the Y-Z plane, of the optical device 1000 of FIG. 1.

[0230] FIG. 1f shows three graphs of the values Ik as a function of the optical retardation for the three channels RGB (for a given representative pixel of a photodetector in the aperture or averaged over a plurality of pixels of photodetectors in the aperture).

[0231] FIG. 2 is a schematic cross-sectional view, in the Y-Z plane, of an optical device 2000 for analyzing the quality of a glazing according to the invention, using the same apparatus as in FIG. 1 except as regards the Babinet compensator and its control mechanism.

[0232] FIG. 2 is a schematic top view of the conveyor and of the glazing to be inspected shown in FIG. 2.

[0233] FIG. 2a is a schematic view of a detail of the conveyor.

[0234] FIG. 2b explains the acquisition on the basis of the scanned area.

[0235] FIGS. 2c and 2d are graphs showing the acquisition sequence and the dead-time sequence for the collection of acquisition data.

[0236] FIG. 3a is a schematic cross-sectional view, in the X-Z plane, of an optical device 1001 according to the invention forming part of a tempering manufacturing line in a second embodiment.

[0237] FIG. 3b is a schematic cross-sectional view, in the X-Z plane, of a device 2001 for analyzing the quality of a glazing according to the invention using the same apparatus as in FIG. 3a except as regards the Babinet compensator and its control mechanism.

[0238] FIG. 4a is a schematic cross-sectional view, in the Y-Z plane, of an optical device 1002 according to the invention in a third embodiment.

[0239] FIG. 4b is a schematic side view, in the Y-Z plane, of an optical device 2002 for analyzing the quality of a glazing according to the invention using the same apparatus as in FIG. 4a except as regards the Babinet compensator and its control mechanism.

[0240] FIG. 1 is a schematic cross-sectional view, in the X-Z plane, of an optical device 1000 according to the invention forming part of a tempering manufacturing line with a horizontal conveyor.

[0241] The optical device 1000 comprises a first vertically oriented polariscope including, in this order (from bottom to top), in an optical alignment with a vertical optical axis Z: [0242] a white first light source 1, here a strip of LEDs delivering a light beam here without collimating meansthe light of which is emitted in the direction given by the optical axis, or as a variant one or more organic light-emitting diodes (OLEDs), said luminous strip being placed orthogonal to the optical axis and producing, with or without a diffuser, uniform light; [0243] a first circular (or quasi-circular) polarizer 2 that polarizes in a firstleft or rightrotation direction, in particular including a first linear polarizer and a first quarter waveplate, against or adhesively bonded to the luminous strip 1; and [0244] a first analyzer 2, namely a circular (or quasi-circular) polarizer that polarizes in a secondright or left, respectivelypolarization rotation direction that is opposite to the first rotation direction, said first analyzer in particular including a second quarter waveplate followed by a second linear polarizer.

[0245] The optical device 1000 furthermore comprises, downstream of the first analyzer and in said optical alignment: [0246] a first digital sensor 6, placed orthogonal to the optical axis, namely here a linear digital camera with a row of first photodetectors; and [0247] a first objective 5, placed orthogonal to the optical axis and defining a focal plane, facing the first digital sensor and between the first analyzer 2 and the first digital sensor, in particular fastened to or against the first digital sensor.

[0248] Furthermore, the optical device according to the invention comprises, between the first polarizer and the first analyzer, and in said optical alignment, a calibrated first optical retardation generator 4, placed orthogonal to the optical axis, here a Babinet (Soleil) compensator, for generating optical retardations in a range AB between 0 nm and 800 nm, and the first optical retardation generator is in said focal plane.

[0249] The first digital sensor 6 therefore includes, in a row, a set of first photodetectors that are sensitive to the spectrum of the first light source 1, having a given spectral response.

[0250] Some of the first photodetectors, which are what are called calibration photodetectors, are located facing the aperture 31 of the first optical retardation generator.

[0251] Preferably, the optical device also includes, between the first optical retardation generator and the linear first sensor, upstream of the first analyzer, a calibrated optical waveplate with a retardation A0 chosen in the zone in which the relationship between the value Ik and the optical retardation is substantially linear for at least one of the reference channels, in particular of 70 or 75 to 175 nm or 185 nm or from 350 or 375 nm to 425 nm.

[0252] In this way, a glazing having little anisotropy may be measured with more precision because small retardation variations will lead to a linear rather than quadratic variation in the Ik.

[0253] The Babinet-Soleil compensator 3 includes first and second wedge-shaped plates, made of birefringent material, the second plate being translationally movable with respect to the static first plate, the compensator in particular being defined by an aperture 31 that is centered on the optical axis; the aperture is entirely illuminated by the first light source 1 and is in said focal plane, one or more calibration first photodetectors being located facing the aperture.

[0254] The change in optical retardation is automated and in particular computer-controlled. The Babinet-Soleil compensator, which is motorized and in particular controlled by a computer, is able to automatically increment the optical retardations in the range AB, in particular with an incrementation step size P0 of at most 0.5 nm and even of at most 0.3 nm, and in particular of between 15 and 25 mm and even 0 and 25 mm.

[0255] The aperture 31 of the compensator is circular, of diameter O1 of at most 30 mm; the center of the aperture is inscribed in a central disk of diameter O1/2; the one or more calibration first photodetectors used are located entirely facing said central disk. Each calibration first photodetector receives, in succession, for each of said optical retardations in said range AB, light energy issued from the light beam that exits from the first analyzer 2. The first digital sensor then generates what are called calibration digital images for said optical retardations in said range AB, each calibration digital image being formed, with one or more reference channels Ck, from one or more pixels that are representative of the spectral response of the calibration first photodetector(s). The reference channels Ck are three red, green and blue channels, referred to as RGB channels.

[0256] The first polariscope, the first digital sensor and the first optical retardation generator are mounted on a heating and tempering line, downstream of the tempering system, during stoppage, the line including a horizontal conveyor for conveying glazings along a conveying axis Y, the line optionally being a bending-tempering line.

[0257] FIG. 1a is a schematic top view (in the horizontal X-Y plane) showing the conveyor with a mounting holder and the two apertures of two motorized Babinet-Soleil compensators used in the optical device 1000 of FIG. 1. FIG. 1c is a schematic perspective view of two conveyor rollers, of the light source, and of the circular polarizer in the inter-roller space, that are used in the optical device 1000 of FIG. 1.

[0258] FIG. 1 e is a schematic cross-sectional view, in the Y-Z plane, of the optical device 1000 of FIG. 1.

[0259] The conveyor (see FIGS. 1a and 1c in particular) includes two rollers 81 and 82 that are spaced apart by an inter-roller space; the first light source 1, on a source holder 10 spaced apart from the ground and under the conveying zone, is under the two rollers and faces the inter-roller space. The first digital sensor is linear and spaced apart from and above the two rollers. The first digital sensor may be fastened to a metal gantry 70 in particular on either side of the conveyor.

[0260] The first optical retardation generator is fastened on a mounting holder 7 to the two rollers, said mounting holder having a hole 71 facing the aperture 31.

[0261] The lateral areas of the luminous strip may be masked (by opaque strips 20 for example), only the central area against the (central) portion of the first polarizer 21 illuminating the compensator 3.

[0262] The optical device 1000 lastly includes a first processing unit (a computer) for processing the calibration digital images with a view to forming a calibration database containing, for each optical retardation in the range AB, digital values Ik for each of the reference channels Ck, said digital values Ik being representative of the light energy collected by the calibration first photodetectors.

[0263] The length of the rollers is for example from 3 to 4 m. Here, a second polariscope using the luminous strip 1, the polarizer 2, the mounting holder 7 (with another hole 71), a second calibrated static waveplate 4, a second analyzer 2, a linear second camera 6 and a second compensator 3 with its aperture 31 is used.

[0264] FIG. 1b is a schematic top view (in the horizontal X-Y plane) of the motorized Babinet compensator on the mounting holder 7 with its hole 71, which is larger than the aperture 31. The control mechanism of the motor 32 (also on the holder) is connected by a cable 33 to the compensator 3 and acts on a micron-sized screw for example.

[0265] FIG. 1d is a schematic perspective view showing a static waveplate 4 (in a filter holder for example), the first objective 5, the linear first camera 6 and a mounting profile 101, and a stage 102 with a screw 103 for positioning the camera 6.

[0266] FIG. 1f shows three graphs 15, 16, 17 of values Ik as a function of optical retardation 6 (nm) for the three RGB channels averaged over a plurality of pixels of photodetectors in the aperture.

[0267] FIG. 2 is a schematic cross-sectional view, in the Y-Z plane, of an optical device 2000 for analyzing the quality of a glazing using the same apparatus as in FIG. 1 except as regards the Babinet compensator and its control mechanism. The glazing 100 is run along the axis Y and is scanned by the luminous strip 1.

[0268] FIG. 2 is a schematic top view of the conveyor in the X-Y plane, and of the glazing to be inspected 100 shown in FIG. 2.

[0269] FIG. 2a is a schematic view of a detail of the conveyor 8 with its rollers 81, 82 (and the fastening gantry 70). A presence detector 84 is used to detect the presence of the glazing (not shown) in order to trigger the acquisition. Furthermore, a rotary encoder 83, which will provide information on the instantaneous speed V, is preferably used.

[0270] FIG. 2b explains the acquisition on the basis of the scanned area. The first light source produces a beam that is uniform in the analyzed area segment.

[0271] During an acquisition, a pixel corresponds to the information integrated from an area element of the pane.

[0272] For example, a square pixel 91 of width W along the analysis length, parallel to the two rollers, is defined.

[0273] During an acquisition of duration T.sub.AQ, each photodetector of the row is liable to receive light having passed through the glazing 100 running along Y, i.e. a beam having illuminated an element of the area of the glazing defined by a width L along the conveying axis. L is equal to the acquisition duration T.sub.AQ multiplied by the instantaneous conveying speed V of the rollers bordering the first light source.

[0274] Moreover, there is a dead time t.sub.mfor collecting the datain which the pixels are not functional. For example, t.sub.m is at most 100 ms.

[0275] It is preferably arranged such that L+Vt.sub.m=W. If, during the acquisition duration, a photodetector receives a beam directly from the first light source (without having passed through a zone of the glazing), the light intensity is not modified by the anisotropic differences, and thus the pixel delivers an identifiable piece of information (black pixel=no accumulated retardation).

[0276] The (looped) acquisition sequence is for example the following: [0277] reception of pulse N from the rotary encoder of the conveyor, which triggers the acquisition sequence; [0278] exposure time T.sub.AQ adjusted with software consisting in an electronic pulse sent by the processing unitthe first sensor 6 integrates the signal (i.e. all of the light energy received during this time TAQ); [0279] dead time corresponding at least to the time required for the read-out of the pixels for processing; [0280] encoder pulse N+1 arrives after the sum of the acquisition time and the dead time.

[0281] FIGS. 2c and 2d are graphs showing, as regards FIG. 2c, the pulses 18 for launching the acquisitions and, as regards FIG. 2d, the acquisition sequence with the dead times for the collection of the acquisition data.

[0282] FIG. 3a is a schematic cross-sectional view, in the X-Z plane, of an optical device 1001 according to the invention forming part of a tempering manufacturing line in a second embodiment. It differs from the first device 1000 above all in that the beam 13 is collimated (the strip of LEDs 1 is collimated) and the first objective 6 is telecentric. A single polariscope and a single compensator 3 may then be used.

[0283] FIG. 3b is a schematic cross-sectional view, in the X-Z plane, of a device 2001 for analyzing the quality of a glazing 100 according to the invention, using the same apparatus as in FIG. 3a except as regards the Babinet compensator and its control mechanism.

[0284] FIG. 4a is a schematic cross-sectional view, in the Y-Z plane, of an optical device 1002 according to the invention in a third embodiment.

[0285] It differs from the first device 1000 above all in that the optical axis Y is horizontal, and therefore the elements 1, 2, 4, 2, 5, 6 are on planar vertical holders 70, 70 and the compensator 3 is on jambs 71, 72 that are for example lateral.

[0286] FIG. 4b is a schematic side view, in the Y-Z plane, of an optical device 2002 for analyzing the quality of a glazing 1000 using the same apparatus as in FIG. 4a except as regards the Babinet compensator and its control mechanism. The glazing is on jambs 73 that are for example lateral.