JP2003262553A - Method and apparatus for measuring edge stress of transparent plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for measuring edge stress of a transparent plate in which the position of measuring stress is surely discriminated, with a simple configuration, for higher measurement precision and improved operativity and usability. <P>SOLUTION: The measuring apparatus is provided with a light source 2; a fixed polarizing plate 6 fixed to an optical axis; a slit 7 of which the width and position can be adjusted; a first measuring means which uses a Babinet compensator 9; a second measuring means which uses an orthogonal sensitive tint plate 10; a switching means 8 for switching between the first and the second measuring means; a rotary polarizing plate 13 rotatable relative to the optical axis; and an eyepiece 14. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent plate edge stress measuring device and method for optically measuring the internal stress in the edge portion of a glass plate or other transparent plate.

[0002]

2. Description of the Related Art In the process of manufacturing window glass for automobiles,
A flat glass having a peripheral edge portion chamfered is bent and molded to manufacture a final window glass. Various inspections are performed on the window glass having the chamfered edge portion before shipping.
In this inspection process, the edge stress of the glass sheet is measured in order to evaluate the strength quality of the window glass. The edge stress corresponds to the internal strain of the glass plate, and the compressive stress (edge compression: E / C) which is the compressive strain of the edge portion and the tensile stress (inner tension: I) which is the tensile strain on the inner side thereof. / T) is measured and the strength of the window glass product is numerically displayed. The larger the compressive stress, the harder it is to break, and the smaller the tensile stress, the harder it is to break.

FIG. 13 is a graph of the internal stress in the edge portion of the window glass for an automobile whose peripheral portion is strengthened and in the vicinity thereof. This graph is detected by a laser beam scanning strain measuring machine. The vertical axis represents internal stress, compression above 0 and compression below 0. The horizontal axis represents the distance from the edge of the edge.

The rising portion from zero to the peak point A is the chamfered portion of the edge portion, and the point B is the neutral point where compression changes to tension. In the edge chamfer, a compressive stress that extends the graph between AB is actually generated as shown by the broken line. The compressive stress at the end of the edge, which is the intersection of the broken line and the one-dot chain line, is the compressive stress (E / C) to be measured. Point C is the peak value of the internal tensile stress, and the tensile stress at point C is the tensile stress (I / T) to be measured.

When the strain due to the stress is generated inside the glass plate, an optical path difference is generated depending on the stress component when the polarized light is transmitted through the glass plate. Therefore, the edge stress can be detected by measuring this optical path difference (Reference: Utilization Technology of Strain Inspector IV Principle and Utilization of Senarmont Method)
ss No.20 1991).

The conventional edge stress measuring device by the Senarmont method is a polarizer (fixed polarizing plate), a quarter-wave plate, a filter that passes only a specific wavelength, and an analyzer (rotating polarizing plate).
And a glass plate to be measured is set between the fixed polarizing plate and the quarter-wave plate. In this case, the direction of the glass edge (the same direction as the main stress) needs to be set at an angle of 45 ° with respect to the polarization axis of the fixed polarizing plate in order to maximize the optical path difference caused by the stress.

Linearly polarized light incident on a glass plate having a stress strain causes an optical path difference by passing through the glass plate and is changed to elliptically polarized light. When this is observed with the scale of the rotary polarizing plate set to 0 °, the position where the plane stress parallel to the edge is 0 becomes black. This appears as a line almost parallel to the edge. This is the neutral line (neutral point B in FIG. 13), compressive stress (E / C) is generated in the region closer to the edge, and tensile stress (I / T) that balances this compressive stress is generated on the inner surface side. There is. When the rotating polarizing plate is rotated, the black line moves according to the ellipticity of the elliptically polarized light. The optical path difference is measured by aligning the center of the line with the position to be measured and reading the rotation angle. Thereby, the edge stress of the glass plate is detected.

[0008]

However, in the above-mentioned conventional edge stress measuring device, the chamfered portion of the edge (see FIG. 1) is used.
It is not easy to detect (the broken line portion 3), and a technique is required to specify the edge end portion, which causes individual differences in measurement results. Moreover, since the top of internal tensile stress (point C in FIG. 13) is on a gentle curve, it is difficult to identify the peak position, and it is not easy to identify the peak position by rotating the rotary polarizing plate, which causes a decrease in measurement accuracy. . The problem caused by such difficulty in identifying the edge end portion or the tensile stress top portion is further increased as the glass plate becomes thinner. Moreover, in order to specify such a detection position, a technique is required to operate the rotary polarizing plate, and the edge of the glass plate to be measured must be held at an angle of 45 ° with respect to the measuring device. Was not easy to handle.

The present invention has been made in consideration of the above-mentioned prior art, and it is an edge stress of a glass plate or the like in which the stress measurement position is surely identified with a simple structure to improve the measurement accuracy and the operability and usability are improved. The purpose is to provide a measuring instrument and a measuring method.

[0010]

In order to achieve the above object, the present invention uses a light source, a fixed polarizing plate fixed to the optical axis, a slit whose width and position can be adjusted, and a Babinet compensator. First measuring means, second measuring means using a cross-sensitive color plate, switching means for switching between the first and second measuring means, and a rotary polarizing plate rotatable about an optical axis, An edge stress measuring device for a transparent plate, which is provided with an eyepiece.

According to this structure, since the first measuring means using the Babinet compensating plate and the second measuring means using the cross-sensitive color plate are provided, the measuring means is used for measuring the compressive stress and the tensile stress. By switching and measuring with different measuring means, it is possible to reliably identify the stress detection position with the measuring means suitable for each stress and improve the measurement accuracy, and to minimize the individual differences in measurement technology and stabilize. And highly accurate measurement results can be obtained. In addition, the slit can narrow the detection field of view, which makes it easier to specify the detection position. Moreover, the eyepiece improves the discriminating property of the glass plate within the detection visual field, and further improves the measurement accuracy.

In a preferred configuration example, the second measuring means is equipped with a quarter-wave plate for a wavelength of 566 nm.

According to this structure, the white linearly polarized light from the light source becomes elliptically polarized light by passing through the stressed glass, and the quarter axis plate combines the major axis and the minor axis of the ellipse. It becomes possible linearly polarized light (Principle of Senarmont method). The angle of this linearly polarized light changes according to the ellipticity of the elliptically polarized light. When the linearly polarized light with the changed angle passes through the orthogonal sensitive color plate, the phase is delayed and advanced by one wavelength on the left and right with respect to the green wavelength (566 nm).
As a result, with respect to linearly polarized light whose angles are deviated, the color is shifted to the blue side, which has a shorter wavelength, and the red side, which has a longer wavelength. Will increase.

In a further preferred configuration example, there is an object to be measured installation section having a rectangular shape in plan view, and the fixed polarizing plate has its polarization axis at 45 to the side of the rectangle of the object to be measured installation section. It is characterized by being tilted and fixed.

According to this structure, the measuring instrument has a rectangular casing when viewed from above, and an object to be measured such as a glass plate is set on the casing. A fixed polarizing plate is fixed to the body part (measurement object installation part), and the polarization axis of the fixed polarizing plate is 4 in advance with respect to the rectangular side of the housing.
It is fixed at an angle of 5 °. This eliminates the need to hold the glass plate to be measured at an angle of 45 ° with respect to the measuring instrument as in the past, and keeps the edge of the glass plate parallel to the horizontal direction of the measuring instrument in a natural state from the front of the measuring instrument. It can be set and held in a simple state. This improves usability.

According to the present invention, the first step of irradiating the transparent plate-shaped body as the object to be measured with light and the second step of detecting the compressive stress at the edge portion of the transparent plate-shaped body using the Babinet method. And a third step of detecting an internal tensile stress in the vicinity of the edge of the transparent plate using the Senarmont method, and a method for measuring the edge stress of the transparent plate.

According to this structure, the compressive stress is detected by the first measuring means by the Babinet compensating plate, and the tensile stress is detected by the second measuring means by the orthogonal sensitive color plate, so that each stress is highly accurate. Can be measured at.

[0018]

1 is a block diagram of an embodiment of the present invention. The edge stress measuring device 1 includes an LED light source 2, a battery 3 serving as a power source for the LED light source 2, and a commercial 100 V AC power source 4.
Power supply device 5 including an adapter (not shown) for converting power into direct current and a switching circuit for the battery 3 and a switch, and an LED
Fixed polarizing plate 6 fixedly provided on the optical path P from the light source 2.
A slit 7 composed of two slit plates 7a and 7b whose slit width and position can be adjusted; a measuring means switching mechanism 8; and a rotary polarizing plate (analyzer) 13 rotatable on the optical path P with respect to the optical axis. And an eyepiece lens 14.

The measuring means switching mechanism 8 comprises a Babinet compensator 9
And the second measuring means having the cross-sensitive color plate 10 are switched. Babinet compensator 9
Is equipped with a micrometer 11 for adjusting the wedge width of the Babinet plate. The orthogonal sharp color plate 10 is provided with a quarter-wave plate 12 for green (wavelength 566 nm).

The measuring means switching mechanism 8 is, for example, of a sliding type, and slides in the direction of arrow A to switch between the Babinet compensating plate 9 and the orthogonal sensitive color plate 10 on the optical path P.

A glass plate (not shown) to be measured is set between the fixed polarizing plate 6 and the slit 7 and held by a holding means (not shown) at a position where the optical path P passes.

The rotating polarization plate (analyzer) 13 detects stress by rotating the rotation polarization plate (analyzer) with respect to the optical axis to change the polarization axis with respect to the fixed polarization plate 6. As shown in FIGS. 2 and 3 described later, the rotary polarizing plate 13 has a scale 20 provided with a vernier scale on the circumference of the circumference.

The eyepiece lens 14 has, for example, a magnification of about 1.7. By using this eyepiece lens 14, the visual field can be limited to enhance the discriminability of the stress detection position. Regarding the magnification, the position of the observer's eyes and the position of the object to be observed (the Babinet compensating plate 9 or the orthogonal sharp color plate 10)
In the case of a measuring device having a distance of up to about 150 mm, if a lens with a focal length of 150 mm is used, the clear vision distance of a human is set to 250 mm, and the magnification of only the eyepiece lens is 250/150 = 1.7.

FIG. 2 is a perspective view of a specific structural example of the edge stress measuring device 1 of FIG. In addition, FIG. 3, FIG. 4 and FIG.
FIG. 4A is a top view, a front view, and a side view thereof.

The LED light source 2 is arranged in the light source box 15, the light source box 15 is provided with a battery box 16, and a power switch 17 and an inlet of an AC / DC conversion adapter (not shown) from an AC 100V power source. 18 is provided. The fixed polarizing plate 6 is provided on the upper surface of the light source box 15.

The light source box 15 is a casing having a rectangular shape in plan view, and a back plate 21 is fixed to the back side. A glass plate (not shown), which is an object to be measured, is installed on the light source box 15 on the front side of the back plate 21. The direction of the polarization axis of the fixed polarizing plate 6 is the rectangular shape of the light source box 15 as shown by the broken line.
It is arranged at an angle of 45 ° to the side back plate 21. In this way, the polarization axis of the fixed polarizing plate is tilted by 45 ° with respect to the rectangular side of the housing in advance, and the glass plate to be measured is held at a 45 ° angle with respect to the measuring device as in the conventional case. It is not necessary to do so, and the edge of the glass plate can be set and held in a natural state from the front side in a state parallel to the left and right direction of the measuring instrument. This improves usability.

A support 19 is provided above the fixed polarizing plate 6 with a back plate 21 interposed therebetween. The above-mentioned slide type measuring means switching mechanism 8 and the slit 7 (FIG. 1) are attached to the support base 19. The measuring means switching mechanism 8 switches between the Babinet compensating plate and the cross-sensitive color plate as described above by operating the switching knob 22 provided on the front side of the measuring device in the inserting / removing direction as indicated by arrow A. Slit plates 7a, 7 of the slit 7
The position of b (FIG. 1) is adjusted by rotating the two slit moving knobs 23, and the slit width between both slit plates is adjusted.

The rotary polarizing plate 13 and the eyepiece lens 14 are mounted on the support 19. The rotary polarizing plate 13 is for rotating the rotary polarizing plate 13 to detect a stress, and a circular scale 20 having a vernier scale 20a (FIG. 3) is formed on a supporting table 19 around the rotary polarizing plate 13.

Next, an edge stress measuring procedure by the edge stress measuring device 1 having the above-mentioned structure will be described. (I) Preliminary preparation: First, as a preliminary preparation, the zero angle of the crosswise sensitive color plate is confirmed. The procedure is as follows. The measuring device is installed so that the micrometer 11 is on the right side of the measurer, that is, the back plate 21 faces the front side of the measurer. Turn on the switch 17 and plug the adapter from the battery power source or AC power source to turn on the power source and turn on the LED.
The light source 2 is turned on. The changeover knob 22 on the back side is pushed in from the measurer to put the orthogonal sensitive color plate 10 in the visual field. The slit moving knob 23 on the left side of the measurer is turned to expand the field of view.

As shown in FIG. 6, the color tone is different between the right and left sides of the center dividing line of the orthogonal sensitive color plate 25 in the visual field (A).
Then, the rotary polarizing plate is rotated so that the color tone becomes the same (B). Confirm that the scale of the rotation angle when the color tone is the same is 0 ° or almost 0 °. ± 0.5 ° from 0 °
If there is a deviation, adjust the zero angle by the following procedure. (6-1) Align the rotary polarizing plate to 0 ° and fix it with adhesive tape so that it does not shift. (6-2) While looking through the eyepiece, turn the adjustment screw with a screwdriver so that the left and right colors are the same. (6-3) Tighten the fixing screw. (6-4) Peel off the adhesive tape to make the rotating polarizing plate rotatable. This completes the zero adjustment.

(II) E / C measurement: Next, E / C (compressive stress) is measured. The procedure is as follows. Pull the switching knob 22 to insert the Babinet compensator into the field of view. The glass plate is installed so that the side of the measurement part (edge part) of the glass to be measured is in the horizontal direction (parallel to the back plate). At this time, when the side of the edge portion is a curve, the tangent line of the measurement unit is installed so as to be parallel to the back plate. If the measurement part is a curved surface, install it so that its normal is in the optical axis direction (vertical direction). The edge of the glass plate is positioned at 1/4 to 1/3 of the width W (FIG. 7) of the Babinet compensation plate, that is, the glass plate covers 3/4 to 2/3 in the width direction of the Babinet compensation plate. The glass plate. As for the installation position of the glass plate, the glass plate is installed and held in a space above the fixed polarizing plate 6 as close to the upper Babinet compensation plate as possible.

When a compressive stress is applied to the edge, as shown in the field of view of FIG. 7, the black stripe stress curve 27 indicating the stress is shifted to the right at the glass edge 26. This deviation amount D is measured with a micrometer. This is done as follows. It should be noted that stress curves deviated by one wavelength are shown on both sides of the stress curve 27 in the visual field. (3-1) Turn the dial of the micrometer 11 so that the reference line of the micrometer (for example, the adjacent 2
Align the parallel lines in the book. (3-2) Press the zero button 11a (FIG. 3) of the micrometer 11 to set the display on the liquid crystal display unit 11b to 0.000. (3-3) Predict the tip of the curved black stripe on the glass edge 26, turn the dial, and move the reference line to that position. (3-3) Set the displayed value on the dial at the tip of the curved black stripe to 1 /
Read and record up to 100 mm.

The compressive stress value σc is calculated using the following formula. σc = (Cb × R) / (C × t) σc: Compressive stress E / C (MPa) Cb: Babine's constant (54.1 nm / mm) R: Reading of D (FIG. 7) by micrometer (m
m) C: photoelastic constant (nm / mm / MPa) t: plate thickness (mm) Therefore, σc = 54.1 × (R / C · t)

(III-1) I / T measurement: Next, I / T
T (internal tensile stress) is measured. The procedure is as follows. As shown in FIG. 8A, the black stripes of the stress curve 27 representing the stress distribution are observed with the Babinet compensator inserted, and the position of the peak 27a of the tensile stress (C in FIG. 13).
Point). In this case, it is easy to identify by using the reference line 28 of the Babinet compensator. If it is difficult to identify, (III
-2) is used. When the position of this peak 27a is confirmed, the same figure (B)
As shown in, the slit moving knob 23 is turned to move one slit plate 7a to that position. Next, in order not to shift the position of the glass plate and the measuring instrument,
The switching knob 22 is pushed in to bring the orthogonal sharpness color plate 25 into the visual field as shown in FIG. Confirm that the right and left sides of the cross-sensitive color plate are different,
The other slit moving knob 23 is turned to bring the other slit plate 7b into view, and the slit width is narrowed as shown in FIG. The orthogonal sensitive color plate 25 is observed within the narrowed slit width, and the rotary polarizing plate is rotated so that there is no difference in the left and right color tones at the center dividing line. When the left and right color tones are the same, read the angle of the rotating polarizing plate at that time. This angle is read up to 1/10 ° using a vernier scale. Calculate the tensile stress value σt using the following formula. σt = (R / 180) × λ / (C × t) σt: Tensile stress I / T (MPa) R: Angle reading of the rotating polarizing plate (°) λ: Center of white light source (566 nm) t: Plate Thickness (mm) C: Photoelastic constant (nm / mm / MPa) Therefore, σt = 566 / (180 × C) × (R / t) = 3.14
X (R / C · t)

(III-2) I / T measurement: Another procedure for measuring the tensile stress will be described. Push the switching knob 22 to put the cross-sensitive color plate in the visual field. The position of the I / T is determined by observing the change in the sensitive color plate in the left half, and the slit plate 7a is inserted at that position. The other slit plate 7b is moved to sandwich the I / T position within the slit width between the slit plates. The inside of the slit is observed, and the rotating polarizing plate is rotated so that there is no difference in color tone from the center dividing line of the crosswise sensitive color plate. Read the scale of the rotating polarizing plate at the position where the color tone is consistent to (1/10) ° using a vernier scale. Calculate the tensile stress value using the above equation.

Next, the principle of measuring the compressive stress on the edge will be described in more detail. E / C directly measures the optical path difference using a Babinet compensator. Therefore, the optical path difference can be obtained regardless of the wavelength of the light used.

As shown in FIG. 9A, the stress curve 27 is straight when the glass plate or the Babinet compensating plate alone has no stress.

FIG. 9B shows the case of a glass plate having edge stress, in which the stress curve 27 is curved in the glass plate 29.
The stress curve 27 is generated at the glass edge where the chamfered portion 29a is formed.
It comes off. As described above, the position 27b of the stress curve at the glass edge is E / C, and the internal peak 27a is I / C.
T. 27c is a stress curve of the part without glass.

When the Babinet compensator and the stressed glass plate are overlapped and observed in a cross polarization field (darkest dark field),
The black stripe, which is the neutral line, becomes a curve as shown in (B). 27b
Light near the edge end of the glass plate indicated by is passed through the Babinet compensation plate 30 and the glass plate 29, and then the Babinet compensation plate 3
A black stripe is offset by R1 on the thinner wedge of 0. Since the edge of the glass plate is chamfered, it is difficult to accurately measure the distance R1 of the edge portion 27b of the edge portion, but since it can be relatively easily predicted from the black stripe curve, this can be measured with a micrometer. Read and measure R1.

The polarized light after passing through the Babinet compensator 30 is
The optical path difference should be generated by multiplying the shift amount R1 by the Babinet constant Cb. The fact that the light turns black after passing through the stressed glass plate 29 is returned to the same linearly polarized light as the incident light due to the stress birefringence of the glass plate. From this, the optical path difference caused by edge compression becomes Cb × R1, and the stress value can be obtained by multiplying the photoelastic constant of glass and dividing by the plate thickness. The calculation formula is as shown in (II) above.

Next, the measurement of the tensile stress (I / T) will be described in more detail. As described above, the Senarmont method is a method of rotating the analyzer to move the black stripe of the neutral line to an arbitrary measurement point and obtaining the optical path difference from the reading angle thereof. When the value of / T itself is small or the change is small, the width of the black stripe becomes wide. For this reason, it becomes very difficult to align the center of the stripe with the measurement point, and the individual difference in the measurement technique becomes large.

In the present invention, in order to prevent this, the neutral color is changed to reddish purple by using a sensitive color plate instead of the conventional black, so that the neutral color can be accurately matched. This is because by using a quarter-wave plate for green, when the analyzer is aligned with the detection position and the green disappears, the stress state becomes red-purple, which is a mixed color of red and blue on both sides of green. This is because it can be identified. The measurement procedure is as follows.

After measuring E / C with the Babinet compensator, the same black stripe bending was observed to determine the I / T location,
Move the slit parallel to the edge to that location. As a result, as shown in FIG. 10, the position of I / T (the position of the bending peak 27a) is accommodated in the slit opening 31. The Babinet compensator and the cross-sensitive plate are replaced, and the analyzer is rotated to change the colors on the left and right of the center dividing line in the slit opening 31 from different colors as shown in FIG. 11A.
Make it the same magenta as shown in. Read the angle of the analyzer when the left and right colors are the same. The optical path difference is calculated using a calculation formula. In the calculation, as shown in (III-1) above, the wavelength of green is 566 nm.
use.

FIG. 12 is an explanatory view of the principle of the cross-sensitive color plate. The cross-sensitive color plate is obtained by cutting a 1λ wavelength plate in half and rotating one of them by 90 ° to connect them. As a result, the polarization axis of the wave plate is deviated by 90 °, and thus white light passing through the sensitive color plate has an optical path difference of +566 nm in the right half and an optical path difference of −566 nm in the left half. That is, as shown in FIG. 12, the position where the stress is zero is shifted to the left and right symmetrical positions in the right half and the left half.

When a glass plate with a small stress (for example, an optical path difference of 10 nm) is put in this field of view, a conventional measuring instrument using the Senarmont method can detect a slight amount of light from the central position where the optical path difference is zero. Almost unnoticeable because it is a change.

On the other hand, in this embodiment, by using the cross-sensitive color plate, light of a color corresponding to the optical path difference of 576 nm in FIG. 12 appears in the right half, but -55 in the left half.
It becomes a reddish light equivalent to 6 nm. A small change in the optical path difference can be detected as a change in color, and the two colors have completely different color tones, so that it can be clearly identified that they are deviated from zero. By rotating the analyzer,
This shift amount can be corrected, and the shift amount, that is, the optical path difference caused by the stress of the glass can be obtained from this rotation amount.

[0047]

As described above, according to the present invention, since the first measuring means using the Babinet compensating plate and the second measuring means using the crosswise sensitive color plate are provided, the compressive stress at the edge portion is reduced. When measuring the tensile stress on the inner side and the inner side thereof, it is possible to switch between the measuring means and measure by different measuring means.
As a result, it is possible to reliably identify the stress detection position with the measuring means suitable for each stress and improve the measurement accuracy,
With a simple structure, stable and highly accurate measurement results can be obtained by minimizing individual differences in measurement technology. In addition, the slit can narrow the detection field of view, which makes it easier to specify the detection position. Moreover, the eyepiece improves the discriminating property of the glass plate within the detection visual field, and further improves the measurement accuracy. Moreover, power consumption can be reduced by using the LED light source. Furthermore, the present invention can be used for stress measurement of window glass for buildings and the like other than window glass for automobiles.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an edge stress measuring device of the present invention.

FIG. 2 is a perspective view of an embodiment of the present invention.

FIG. 3 is a top view of an embodiment of the present invention.

FIG. 4 is a front view of an embodiment of the present invention.

FIG. 5 is a side view of an embodiment of the present invention.

FIG. 6 is an explanatory diagram of an operation preparation procedure according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram of a measuring method using the Babinet compensating plate of the present invention.

FIG. 8 is an explanatory diagram of an I / T measurement method of the present invention.

FIG. 9 is an explanatory view of the principle of the Babinet compensating plate of the present invention.

FIG. 10 is a procedure explanatory diagram of the I / T measurement method of the present invention.

FIG. 11 is a procedure explanatory diagram of the I / T measurement method of the present invention.

FIG. 12 is an explanatory view of the principle of the cross-sensitive color plate of the present invention.

FIG. 13 is a stress curve distribution diagram of the glass edge portion.

[Explanation of symbols]

1: Edge stress measuring device, 2: LED light source, 3: battery, 4: AC power supply, 5: power supply device, 6: fixed polarizing plate,
7: slit, 7a, 7b: slit plate, 8: measuring means switching mechanism, 9: Babinet compensating plate, 10: orthogonal sensitivity color plate,
11: Micrometer, 12: Quarter wave plate, 13:
Rotating polarizing plate, 14: eyepiece lens, 15: light source box,
16: battery box, 17: switch, 18: cross / direct adapter insertion port, 19: support, 20: scale, 21: back plate, 22: switching knob, 23: slit moving knob, 2
5: Orthogonal sensitive color plate, 26: Glass edge, 27: Stress curve, 27a: Peak position of internal stress, 27b: Edge of glass edge of stress curve, 27c: Stress curve of a part without glass, 28: Parallel mark Line, 29: glass plate, 29a: chamfered part, 30: Babinet compensating plate, 31: slit opening.

Claims (4)

[Claims] 1. A light source, a fixed polarizing plate fixed with respect to an optical axis, a slit whose width and position can be adjusted, a first measuring means using a Babinet compensating plate, and a first using a cross-sensitive color plate. A transparent plate-shaped body, comprising: a second measuring unit; a switching unit for switching between the first and second measuring units; a rotary polarizing plate rotatable about an optical axis; and an eyepiece lens. Edge stress measuring instrument. 2. The edge stress measuring device for a transparent plate according to claim 1, wherein the second measuring means includes a quarter-wave plate for a wavelength of 566 nm. 3. An object to be measured installation section having a rectangular shape in plan view, and the fixed polarizing plate is fixed to the object to be measured installation section with its polarization axis inclined by 45 ° with respect to the rectangular side of the installation section. The edge stress measuring device for a transparent plate according to claim 1 or 2, characterized in that 4. A first step of irradiating a transparent plate-shaped object which is an object to be measured with light, and a second step of detecting a compressive stress at an edge portion of the transparent plate-shaped object using a Babinet method. A third step of detecting an internal tensile stress near the edge of the transparent plate using the Senarmont method.