CN216559446U

CN216559446U - Glass edge stress detector

Info

Publication number: CN216559446U
Application number: CN202122819145.2U
Authority: CN
Inventors: 李俊峰
Original assignee: Beijing Jeffoptics Co ltd
Current assignee: Beijing Jeffoptics Co ltd
Priority date: 2021-11-17
Filing date: 2021-11-17
Publication date: 2022-05-17
Anticipated expiration: 2031-11-17

Abstract

The application discloses glass edge stress detector, it includes lighting unit, detecting element and sets up the detection opening between the two. The illumination unit comprises a light source and a polarizer, wherein the polarization direction of the polarizer forms an included angle of 45 degrees with an X axis and a Y axis which are perpendicular to the optical axis and are orthogonal to each other; the detection unit comprises an optical wedge and a polarization analyzer which are sequentially arranged along an optical path, the phase difference introduced by the optical wedge is changed along the X axis and is unchanged along the Y axis, and the polarization analyzer has the same or orthogonal polarization direction with the polarizer; the detection opening is used for receiving the edge of the glass to be detected along the direction basically vertical to the optical axis and enabling the edge of the glass to be detected to be positioned in parallel to the X-axis direction. According to the method and the device, convenient and accurate detection can be realized for the edge stress of the glass.

Description

Glass edge stress detector

Technical Field

The utility model relates to optical detection equipment, in particular to a glass edge stress detector.

Background

Glass sheets are common materials in both daily life and industrial production. The glass can be stressed during shaping and subsequent further processing due to bending, uneven cooling, etc. Due to the stress birefringence characteristics of the glass, the stress state of the edge portion of the glass can be calculated by measuring the optical path difference of the polarized light. The glass stress detector is an optical detection device for detecting the stress on the surface of glass by detecting the birefringence phenomenon on the surface of the glass. At present, a mature glass surface stress detector is available in the market.

However, there is no suitable detection device for detecting the stress at the edge portion of the glass. While glass typically develops compressive stress at the edges and tensile stress near the edges during the forming and processing processes, the stress varies with position. Along with the tensile stress grow, glass strength reduces, and the risk of spontaneous explosion increases, needs the stress of detection control glass edge to improve intensity, reduce the wind direction of spontaneous explosion.

At present, a stress detector suitable for detecting the stress of the glass edge is needed.

SUMMERY OF THE UTILITY MODEL

It is an object of the present invention to provide a glass edge stress detector which at least partially remedies the deficiencies in the prior art.

According to an embodiment of the present invention, there is provided a glass edge stress detector including:

an illumination unit including a light source and a polarizer that receives light from the light source and makes it linearly polarized, wherein a polarization direction of the polarizer makes an angle of substantially 45 ° with an X axis and a Y axis orthogonal to each other perpendicular to an optical axis;

a detection unit comprising a wedge and an analyzer arranged in sequence along an optical path, the wedge being arranged such that the phase difference it introduces varies along the X-axis and is invariant along the Y-axis, the analyzer having a polarization direction that is the same as or orthogonal to the polarizer; and

a detection opening formed between the illumination unit and the detection unit for receiving an edge of the glass to be detected in a direction substantially perpendicular to an optical axis and positioning the edge of the glass to be detected in parallel to the X-axis direction.

Preferably, the illumination unit further comprises a light homogenizing plate disposed between the light source and the polarizer.

Preferably, a positioning block is arranged on one side of the detection opening, and the positioning block is provided with a positioning surface perpendicular to the Y axis and used for abutting against the edge of the glass to be detected.

Preferably, the detection opening has a flat shape perpendicular to the optical axis.

The glass edge stress detector may further include a housing, preferably, the housing includes an upper housing and a lower housing disposed opposite to each other in an up-down direction, the illumination unit is disposed in the lower housing, the detection unit is disposed in the upper housing, and the detection opening is formed between the upper housing and the lower housing.

Preferably, the upper housing and the lower housing are connected to each other at one side of the detection opening, and a positioning block is disposed at the one side of the detection opening, and the positioning block has a positioning surface perpendicular to the Y axis for the edge of the glass to be detected to abut against.

Preferably, at least one of the bottom surface of the upper case and the top surface of the lower case is formed as a plane perpendicular to the optical axis.

Preferably, the glass edge stress detector further comprises an observation device disposed downstream of the detection unit for observing interference fringes formed via the detection unit.

Preferably, the glass edge stress detector further comprises an optical filter, and the optical filter is arranged between the light source and the observation device.

Preferably, the glass edge stress detector further comprises a filter switching device for moving the filter to switch between a first position in the optical path and a second position away from the optical path.

Preferably, the glass edge stress detector further comprises a housing, the housing comprises an upper housing and a lower housing which are arranged oppositely, the illumination unit is arranged in the lower housing, the detection unit and the observation device are arranged in the upper housing, and the detection opening is formed between the upper housing and the lower housing.

Preferably, the observation device includes an image acquisition device that acquires an image of the interference fringes formed via the detection unit.

According to the embodiment of the utility model, the glass edge stress can be conveniently and accurately detected.

Drawings

Other features, objects and advantages of the utility model will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a perspective view of an exemplary glass edge stress detector in accordance with embodiments of the present invention;

FIG. 2 is a schematic diagram of the optical system of the glass edge stress detector according to an embodiment of the present invention;

FIG. 3 is another perspective view of the glass edge stress detector shown in FIG. 1;

FIG. 4 is a side view of the glass edge stress detector of FIG. 1;

FIG. 5 is a schematic diagram of an exemplary processing method that may be used in a computing unit of a glass edge stress detector according to an embodiment of the present invention;

FIGS. 6, 7, and 8 are examples of first, second, and third images detected by a glass edge stress detector according to an embodiment of the present invention;

FIG. 9 illustrates an example of a glass edge stress value profile obtained using a glass edge stress detector in accordance with an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the utility model. For convenience of description, only portions related to the utility model are shown in the drawings.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

A glass edge stress detector 1 according to an embodiment of the present invention will be described below with reference to fig. 1 to 4. FIG. 1 shows a glass edge stress detector 1 according to an embodiment of the utility model in perspective view. FIG. 2 is a schematic diagram of an optical system of a glass edge stress detector according to an embodiment of the utility model. Fig. 3 and 4 are another perspective view and a side view of the glass edge stress detector 1.

As shown in fig. 1, the glass edge stress detector 1 includes an illumination unit 10, a detection unit 20, and a detection opening 30 formed between the illumination unit 10 and the detection unit 20.

The illumination unit 10 includes a light source 11 and a polarizer 12, and the polarizer 12 receives light from the light source 11 and linearly polarizes it. Referring to fig. 2, the polarization direction p1 of polarizer 12 is at an angle of approximately 45 ° to the X and Y axes orthogonal to each other perpendicular to the optical axis (the Z axis direction shown in the figure). The light source 11 may be a white light source. To provide a larger illumination range to enable detection of a larger area of the glass edge (rather than single point detection), the light source 11 is preferably formed to provide illumination approximating a surface light source. For example, the light source 11 may comprise an array of light emitting devices, such as an array of LEDs. More preferably, as shown in fig. 1, the illumination unit 10 may further include a light uniformizing plate 13, and the light uniformizing plate 13 is disposed between the light source 11 and the polarizer 12.

The detection unit 20 comprises an optical wedge 21 and an analyzer 22 arranged in sequence along the optical path. The optical wedge 21 is arranged such that the phase difference it introduces varies along the X-axis and is constant along the Y-axis. In other words, the wedge angle axis of the optical wedge 21 is parallel to the Y-axis, and the thickness or refractive index, for example, of the optical wedge 21 varies along the X-axis direction and does not vary along the Y-axis. The optical wedge 21 may be a quartz wedge, for example. In the example shown in FIG. 1, analyzer 22 is a polarizing film formed on the surface of wedge 21. It should be understood that the analyzer 22 may also be formed as a separate element from the wedge 21. As shown in FIG. 2, the polarization direction p2 of the analyzer 22 is the same as the polarization direction p1 of the polarizer 12. In other cases, the polarization direction p2 of the analyzer 22 may also be at a 90 ° angle (i.e., orthogonal) to the polarization direction p1 of the polarizer 12.

The detection opening 30 is formed between the illumination unit 10 and the detection unit 20. As more clearly shown in fig. 4, the detection opening 30 is formed to receive the edge b of the glass G to be detected (see fig. 4) in a direction substantially perpendicular to the optical axis and to position the edge b of the glass G to be detected parallel to the X-axis direction. As shown more clearly in fig. 3 and 4, the detection opening 30 preferably has a flat shape perpendicular to the optical axis (the optical axis is in the Z-axis direction shown in the drawings).

Referring back to fig. 2, after the light exits from the light source 11, the light passes through the light uniformizing plate 13 to form uniform illumination light; the illumination light passes through the polarizer 12 to form linearly polarized light (which can be decomposed into linearly polarized light in the X-axis direction and in the Y-axis direction) at an angle of approximately 45 ° to the X-axis and the Y-axis; after the linearly polarized light passes the edge b of the glass G to be inspected, the linearly polarized light in the X-axis direction and the linearly polarized light in the Y-axis introduce a first optical path difference DL1 due to the stress birefringence effect of the glass edge. By detecting the first optical path difference DL1, the stress of the glass edge can be calculated accordingly.

With continued reference to FIG. 2, the light introduced with the first optical path difference DL1 is received by the wedge 21, and after passing through the wedge 21, a second optical path difference DL2 is further introduced by the wedge 21. The optical path difference DL2 introduced by the optical wedge 21 increases along the X-axis direction and does not change along the Y-axis direction. After passing through the analyzer 22, a bright spot is formed at a position where the total optical path difference DL is n times (n is an integer) the wavelength DL1+ DL2, and a dark spot is formed at a position where the total optical path difference DL is n +1/2 times the wavelength. The bright point connecting lines form bright stripes, and the dark point connecting lines form dark stripes, so that interference stripes capable of being observed are formed.

The level of each stripe can be identified according to the brightness relationship of the stripes, so as to obtain the corresponding value of the total optical path difference DL. Knowing the total optical path difference DL, it is also necessary to calculate the second optical path difference DL2 introduced by the wedge 21 at that point. Since the wedge angle is assumed to be constant, the second optical path difference introduced by the wedge 21 at any X-axis position can be calculated by interpolation using a wave plate with known optical path difference. For example, two wave plates with known optical path difference may be inserted into the detection opening 30, respectively, to obtain two images of interference fringes, and determine X-axis coordinates, i.e. coordinates X', X ″ of the fringes of the same predetermined order in the two images of interference fringes; then, the optical path difference introduced by the optical wedge 21 at coordinates x' and x ″ can be obtained from the formula DL2 ═ DL-DL1 (in this case, DL1 is the optical path difference introduced by the wave plate). By interpolation, the second optical path difference DL2 for wedge 21 at any X-axis position X is obtained. However, it should be understood that the stress detector and the detection method of the present application are not limited to the use of the interpolation method described above to calculate the optical path difference introduced by the optical wedge.

Knowing the total optical path difference DL and the second optical path difference DL2, the first optical path difference DL1, that is, the optical path difference introduced at a certain point on the edge b of the glass G to be detected, can be obtained. The stress value of the point can be obtained by dividing the first optical path difference DL1 by the thickness of the glass G and then dividing by the photoelastic coefficient of the glass G.

Preferably, as shown in fig. 3 and 4, a positioning block 40 is disposed at one side of the detection opening 30, and the positioning block 40 has a positioning surface 40a perpendicular to the Y axis for the edge b of the glass G to be detected to abut against, so as to more conveniently and stably position the edge b of the glass G to be detected to be parallel to the X axis direction.

In the glass edge stress detector 1 according to the embodiment of the present invention, the detection opening 30 is provided so that the edge b of the glass G to be detected can be positioned parallel to the X-axis direction, and at the same time, the optical wedge 21 is provided so that the optical path difference introduced by the optical wedge varies in the X-axis direction and does not vary in the Y-axis direction, which enables the glass edge stress detector 1 according to the embodiment of the present invention to detect stress within a certain width range in the Y-axis direction, so that stress (from compressive stress to tensile stress and stress magnitude also varies) that varies along with an increase in distance from the edge (the outermost edge of the glass) can be accurately and conveniently detected.

Referring back to fig. 1, the glass edge stress detector 1 preferably further includes an observation device 50 disposed downstream of the detection unit 20 along the optical path for observing interference fringes formed via the detection unit 20. In the example shown in fig. 1, the observation device 50 includes an image acquisition device, such as a camera, which acquires an image of the interference fringes formed via the detection unit 20. In other examples, the scope 50 may also be an eyepiece system provided with position scales along the X-axis and Y-axis in the field of view, for example.

Preferably, the glass edge stress detector 1 may further include a filter F (see fig. 2, not shown in fig. 1). The filter F may be disposed at any position between the light source 11 and the observation device 50. The filter F allows only light in a narrow wavelength range to pass through with respect to the light source 11, so that the number of interference fringes that can be observed by the observation device 50 is increased, which is advantageous for improving the calculation accuracy of the optical path difference.

Preferably, the glass edge stress detector 1 may further include a filter switching device (not shown) for moving the filter F to switch between a first position in the optical path and a second position away from the optical path. This allows the user to select different fringe images as desired, providing more flexibility.

Referring again to fig. 3 and 4, the glass edge stress detector 1 includes a housing 90, and the housing 90 preferably includes an upper housing 91 and a lower housing 92 disposed opposite to each other. Referring to fig. 1 and 3 in contrast, in the illustrated example, the illumination unit 10 is provided in the lower case 92, the detection unit 20 is provided in the upper case 91, and the detection opening 30 is formed between the upper case 91 and the lower case 92.

As shown in fig. 3 and 4, the upper case 91 and the lower case 92 may be connected to each other at one side of the detection opening 30. The side of the inspection opening 30 is preferably provided with a positioning block 40, and a positioning face 40a of the positioning block 40 is used for abutting against the edge of the glass G to be inspected.

Preferably, as shown in fig. 4, the top surface 92a of the lower case is formed as a plane perpendicular to the optical axis. Thus, when the detection is performed, the edge of the glass G to be detected can be conveniently placed on the top surface 92 and kept perpendicular to the optical axis of the detection optical path, which is beneficial to improving the convenience of operation and the accuracy of detection.

Preferably, as shown in fig. 1, the observation device 50 is also provided in the upper case 91. In addition, the glass edge stress detector 1 may further include a reflector M to deflect the optical path to form a folded optical path. Thus, the space can be saved, and the miniaturization can be realized.

In the example shown in fig. 1, the observation device 50 is an image acquisition unit (e.g., a camera), and an image acquired by the image acquisition unit can be sent to a computing device through an image output interface 50a for processing and calculation, so as to calculate the stress value of the glass edge to be detected.

Although not shown, the glass edge stress detector 1 according to the embodiment of the present invention may further include a calculation unit that calculates the stress of the edge b of the glass G to be detected based on the image acquired by the image acquisition unit (observation device) 50. The computing unit (not shown) may be integrated in the housing 90 or may be a separately provided unit. For example, in the example shown in fig. 1, the image acquired by the image acquisition unit (observation device) 50 may be transmitted to the calculation unit through the image output interface 50a by, for example, wire or wireless.

FIG. 5 is a schematic diagram of an exemplary processing method 100 that may be used in a computing unit of a glass edge stress detector in accordance with embodiments of the present invention.

As shown in fig. 5, the computing unit of the glass edge stress detector 1 is configured to perform a processing method 100, the processing method 100 comprising:

(1) acquiring a first image and a second image, wherein the first image and the second image are interference fringe images acquired under the condition that a first specified optical path difference and a second specified optical path difference are respectively introduced into a detection opening, and the first specified optical path difference and the second specified optical path difference are not equal;

(2) acquiring a third image, wherein the third image is an interference fringe image acquired under the condition that the edge of the glass to be detected is inserted into the detection opening;

(3) identifying stripes with corresponding orders in the first image, the second image and the third image, and determining X-axis positions of points with the same Y-axis position on the stripes in the first image, the second image and the third image; and

(4) and calculating a stress value corresponding to the Y-axis position of the edge of the glass to be detected based on the X-axis positions of the stripes with the corresponding orders in the first image, the second image and the third image.

In process (1), the first prescribed optical path difference and the second prescribed optical path difference can be achieved by, for example, inserting no optical element (i.e., the introduced optical path difference is zero) or inserting a wave plate having a known and determined optical path difference in the detection opening 30, respectively. For example, the first image may be acquired without any intervening optical elements, and the second image may be acquired with wave plates interposed; it is also possible to acquire the first image with one wave plate inserted and the second image with a different other wave plate inserted.

Further, it should be understood that the execution order of the process (1) and the process (2) may be exchanged and is not limited to a specific sequential execution order.

For ease of understanding, fig. 6, 7, and 8 show examples of the above-described first image IM1, second image IM2, and third image IM3, respectively. The reference numeral "S0" in the figure denotes a zero-order light stripe, and X1, X2, and X3 are X-axis positions of points having the same Y-axis coordinate Y on the zero-order light stripe in the first image IM1, the second image IM2, and the third image IM 3.

FIG. 9 illustrates an example of a glass edge stress value profile obtained using a glass edge stress detector in accordance with an embodiment of the present invention, wherein the abscissa of FIG. 9 corresponds to the Y-axis coordinate and the ordinate is the stress value coordinate.

It should be understood that a glass edge stress detector according to embodiments of the present invention is not limited to integration with a computing unit; the image obtained by the image obtaining unit (observation device) 50 of the inspection apparatus can be sent to an external computing device (e.g., a computer) for processing and calculation to obtain the glass edge stress detection result.

Accordingly, according to other aspects of the present invention, there is provided a glass edge stress estimation method for the glass edge stress detector described above, including:

(4) and calculating a stress value of the edge of the glass to be detected, which corresponds to the Y-axis position, based on the X-axis positions of the stripes with the corresponding orders in the first image, the second image and the third image.

According to other aspects of the present application, there is also provided a computer storage medium storing a computer program which, when executed by a processor, implements the glass edge stress estimation method as introduced above.

According to other aspects of the present application, there is also provided a computer device comprising a processor and a storage medium having stored therein a computer program which, when executed by the processor, implements the glass edge stress gauging method as introduced above.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the utility model according to the present application is not limited to the specific combination of the above-mentioned features, but also covers other embodiments where any combination of the above-mentioned features or their equivalents is made without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims

1. A glass edge stress detector, comprising:

2. The glass edge stress detector of claim 1, wherein the illumination unit further comprises a smoothing plate disposed between the light source and the polarizer.

3. The glass edge stress detector of claim 1, wherein a positioning block is disposed at one side of the detection opening, and the positioning block has a positioning surface perpendicular to the Y-axis for abutting against an edge of the glass to be detected.

4. The glass edge stress detector of claim 1 or claim 3, wherein the detection opening has a flat shape perpendicular to the optical axis.

5. The glass edge stress detector of claim 1, further comprising a housing comprising an upper housing and a lower housing disposed in an opposing relationship, wherein the illumination unit is disposed in the lower housing, wherein the detection unit is disposed in the upper housing, and wherein the detection opening is formed between the upper housing and the lower housing.

6. The glass edge stress detector of claim 5, wherein the upper housing and the lower housing are connected to each other at one side of the detection opening, and a positioning block is provided at the one side of the detection opening, the positioning block having a positioning surface perpendicular to the Y-axis for the edge of the glass to be detected to abut against.

7. The glass edge stress gauge of claim 5 or 6, wherein at least one of the bottom surface of the upper housing and the top surface of the lower housing is formed as a plane perpendicular to the optical axis.

8. The glass edge stress monitor of claim 1, further comprising an observation device disposed downstream of the detection unit for observing interference fringes formed via the detection unit.

9. The glass edge stress gauge of claim 8, further comprising an optical filter disposed between the light source and the viewing device.

10. The glass edge stress detector of claim 9, further comprising a filter switching device configured to move the filter between a first position in the optical path and a second position out of the optical path.

11. The glass edge stress gauge of claim 8, further comprising a housing comprising an upper housing and a lower housing disposed in an opposing relationship, wherein the illumination unit is disposed in the lower housing, wherein the detection unit and the viewing device are disposed in the upper housing, and wherein the detection opening is formed between the upper housing and the lower housing.

12. The glass edge stress detector of claim 8, wherein the vision device comprises an image acquisition device that acquires an image of the interference fringes formed via the detection unit.