JP5549860B2 - Glass substrate - Google Patents

Description

  The present invention relates to a glass substrate, and more particularly, to a substantially rectangular flat plate-shaped glass substrate in which a through hole is formed in an edge peripheral region.

  As is well known, a plasma display (PDP), which is a kind of flat panel display (FPD), generates a plasma discharge by applying a voltage to a space between a front plate and a back plate arranged opposite to each other. The fluorescent material applied to the back plate is caused to emit light by the ultraviolet rays generated along with this, and an image is displayed. In this case, in order to generate plasma discharge, it is necessary to enclose a gas containing Ne, Xe or the like in the space between the front plate and the back plate. Accordingly, at least one through hole through which gas can flow is provided in the back plate (or front plate) in order to perform exhaust and gas filling. In addition, in a field emission display (FED) as another example of the FPD, at least one through hole similar to that for the PDP is provided in the back plate (or the front plate) constituting the FPD.

  Such a back plate for FPD is manufactured from a substantially rectangular glass substrate. As this kind of glass substrate, one back plate corresponding to one back plate as shown in FIG. As illustrated in FIGS. 9B to 9H, there are a multi-sided one and a multi-sided one that is used after being divided into a plurality of back plates in a later step. In the multi-chamfered glass substrate 1C illustrated in FIGS. 9B to 9H, at least one of the four sides is provided so that at least one through hole 2C is provided in a region corresponding to one back plate. Are arranged at predetermined intervals in the peripheral region of the edge. Regardless of whether it is single-piece or multi-plane, the through-hole 2C is provided in the corner portion of the area corresponding to one back plate in the glass substrate 1C from the viewpoint of FPD display or layout with respect to the back plate. It is customary to do so. In addition, the dotted line shown in each of FIG. 9 is a virtual cutting line, and the multi-faceted glass substrate 1C is cut and divided along the virtual cutting line.

  Since elements such as fine electrodes and partition walls are formed on the surface of this type of glass substrate, a heat treatment for heating and cooling the glass substrate is performed in forming the elements. This heat treatment is performed, for example, by transporting the glass substrate inside the firing furnace. At that time, the temperature difference between the front and back surfaces of the glass substrate, the temperature increase rate difference between each region of the glass substrate, or cooling. It is known that tensile stress in the direction along the side acts on the peripheral region of the edge of the glass substrate due to a speed difference or the like.

  On the other hand, the above-mentioned through-hole is usually formed by cutting (drilling) a glass substrate. However, microcracks are formed on the inner peripheral surface of the through-hole due to frictional heat generated during drilling or core deflection of the drill. May be formed. When heat treatment is performed on a glass substrate on which such microcracks are formed, the tensile stress acts to tear the microcracks, resulting in stress concentration at the bottom of the microcracks, resulting in this. Then, the problem that the micro cracks progress and the glass substrate is broken can arise.

  In order to deal with such a problem, according to Patent Document 1, when a hole is drilled separately from the upper surface side and the lower surface side of the glass substrate by drilling and the through hole is drilled, the maximum distance from the tip of the lower drill is reached. Due to the influence of frictional heat, etc., by satisfying the relationship of L> H, where L is the axial distance to the outer diameter and H is the distance from the lower end position where the upper drill has entered to the lower surface of the glass. A technique for reducing the occurrence of cracks in through holes is disclosed.

JP 2008-137354 A

  However, the technique disclosed in Patent Document 1 can only reduce the probability of occurrence of microcracks when drilling through-holes, and is a problem of damage or breakage of the glass substrate starting from the through-holes during the heat treatment described above. On the other hand, the fact is that it has not been solved reliably for the following reasons.

  That is, the through-holes drilled in the conventional glass substrate, including those disclosed in this document and those shown in FIG. 9 described above, have a circular contour shape. In this case, as shown in FIG. 10, when the circular through-hole 2C is formed in the edge peripheral region SC of the glass substrate 1C, the heat treatment described above is applied to the edge peripheral region SC and the side 1A. Since the tensile stress T in the extending direction acts, stress concentration occurs at the two points 2X at the outermost end portions in the direction orthogonal to the side 1A in the circular through hole 2C. When the stress at the two points 2X exceeds the allowable range, cracks develop from the circular through-hole 2C as a starting point, leading to damage such as cracking of the glass substrate 1C and thus breakage.

  Accordingly, as shown in FIG. 9 described above, the single-piece or multi-chamfer glass substrate 1C is also heat-treated because the circular through hole 2C is formed in the peripheral edge region SC of the glass substrate 1C. It is necessary to consider the stress concentration at the two outermost ends 2X of the circular through hole 2C due to the occurrence of tensile stress at the time. If measures for this are not appropriate, the large glass substrate 1C for FPD cannot be avoided from damage such as cracks starting from the circular through-hole 2C, and hence to the breakage.

  In view of the above circumstances, the present invention makes it possible to increase the probability of occurrence of damage such as cracking starting from a through-hole, and hence breakage, due to the glass substrate typified by FPD being subjected to heat treatment. Reduction is a technical issue.

The present invention created to solve the above technical problem is a glass substrate having a substantially rectangular flat plate shape having four sides and a through-hole formed in a peripheral region of the edge. The glass substrate is used for a flat panel display. direction as well as a glass substrate, the through hole along its elongated gas distribution, long holes der in the direction along the nearest one side from the hole forming position is, the elongated hole, the one side Characterized in that it is formed so as to satisfy the relationship 1.2 × L2 ≦ L1 ≦ 3 × L2, where L1 is L1 and L2 is the length in the direction perpendicular to the one side. It is done. Here, the “edge peripheral region” preferably means a region having a separation length of 50 mm or less from the corresponding side in the direction orthogonal to the side (hereinafter the same).

  According to such a configuration, even if the through hole is formed in the peripheral edge region of the glass substrate, the through hole is a long hole that is long in the direction along the one side closest to the hole forming position. Therefore, when tensile stress is generated in the peripheral region of the edge due to the heat treatment of the glass substrate, damage such as cracking starting from the through-hole of the glass substrate and breakage is generated for the following reasons. Can be avoided. That is, the tensile stress generated in the peripheral region at the time of heat treatment of the glass substrate acts in the direction along the one side, and the long hole is elongated in the direction along the one side. Has been. Therefore, at both ends of the long hole in the direction orthogonal to the one side, the portion where the stress acts is widened, and the stress is dispersed accordingly. Such stress concentration does not occur. As a result, it is possible to reduce as much as possible the situation that the glass substrate is damaged such as cracking or breakage starting from the through hole.

  In this case, it is preferable that a virtual straight line passing through the center of the elongated hole and connecting one end and the other end in the longitudinal direction is parallel to the one side.

  In this way, because the virtual straight line along the longitudinal direction of the long hole and the one side are parallel, the direction in which the tensile stress acts and the longitudinal direction of the long hole can be more accurately matched, It is possible to more reliably reduce the probability of occurrence of breakage or the like starting from the through-holes as well as the stress dispersion.

  Moreover, it is preferable that the outline shape of the said long hole is formed with the curved line which continues smoothly, or the straight line and curved line which connect mutually smoothly.

  By doing so, there is no angular portion in the outline shape of the long hole, so stress concentration on such a portion can be eliminated, and this is advantageous in preventing breakage starting from the through hole. It becomes.

  As a specific example, the outline shape of the elongated hole is a substantially semicircular line whose longitudinal ends are convex toward the both ends, and the central part in the longitudinal direction is smooth to the two substantially semicircular lines, respectively. It can be made into the shape which is a straight line connected to.

  In this way, tensile stress (stress to be concentrated) acts on the continuous contact points of the two substantially semicircular lines and the two straight lines in the outline shape of the long hole, that is, four points. Therefore, compared to the case of the conventional circular through hole, the hole shape can be surely relaxed.

  As another specific example, the outline shape of the long hole may be an ellipse.

  In this case, both ends of the long hole in the direction perpendicular to the one side become a gently curved line, and stress concentration is less likely to occur in such a curved part. In this case as well, the hole shape can be surely relaxed.

  In the above configuration, the long hole is preferably formed in a central region excluding a region of 12.5% of the total length of the one side from both ends of the one side.

  As described above, the region where 12.5% of the total length of the one side is excluded from the both ends of the one side from the region where the long hole is formed in the glass substrate is the tension around the corner portion of the glass substrate. Since the stress is hardly generated, the present inventors have already confirmed that even if a circular through-hole is formed in this part, stress concentration that causes damage to the glass substrate during heat treatment does not occur. It comes from knowing. Therefore, if only the through-hole formed in the central region here is a long hole, the glass substrate can be prevented from being damaged even if the other through-hole is a circular through-hole. Work complexity is suppressed.

In the present invention, as described above, the long hole is a through-hole (hereinafter referred to as an exhaust hole ) formed in the glass substrate for flat panel display and capable of flowing gas .

  In this way, since the through hole formed by the long hole formed in the peripheral region of the edge is used as the exhaust hole of the glass substrate for FPD, the glass substrate for FPD is used in a firing furnace for element formation or the like. When transported inside, cracks and breakage are less likely to occur. This is because, in the firing furnace, due to a temperature difference between the front and back surfaces of the glass substrate, a temperature increase rate difference or a cooling rate difference between each region of the glass substrate, a peripheral region of the edge of the glass substrate. However, since the through holes formed in the peripheral region of the edge are long holes having the directionality described above, the glass substrate is less likely to be damaged from the long hole as a starting point. Because.

Furthermore, in the present invention, as described above, when the length in the direction along the one side is L1, and the length in the direction orthogonal to the one side is L2, .2 × L2 ≦ L1 ≦ 3 × L2 so as to satisfy the relationship .

  That is, when the above L1 is smaller than 1.2 times L2, it becomes difficult to sufficiently distribute the stress, and the influence due to the variation in the glass strength tends to become larger, and a sufficient stress relaxation effect can be obtained. It becomes impossible. On the other hand, when the above L1 exceeds 3 times L2, a functional request due to the fact that a circular through hole is preferable (for example, the role as an exhaust hole of the glass substrate for FPD already described) Requests to fulfill properly) Therefore, if L1 and L2 are in the above relationship, these problems are unlikely to occur. When L1 and L2 are in the above relationship, when the long hole is the exhaust hole described above, the value of L1 / L2 is large in order to appropriately maintain the gas flow resistance of the long hole. Accordingly, it is preferable to increase the passage area of the long hole.

  The glass substrate having the above configuration is preferably a glass substrate for flat panel display having a plate thickness of 0.5 to 3.0 mm.

  That is, when the plate thickness exceeds 3.0 mm, factors other than the through hole become large as a cause of damage to the peripheral region of the edge of the glass substrate for FPD. On the other hand, if the plate thickness is less than 0.5 mm, it is difficult to perform drilling with a drill or an end mill. Therefore, these problems can be avoided if the thickness of the FPD glass substrate is within the above numerical range. The FPD glass substrate here includes glass substrates for liquid crystal display (LCD) and electroluminescence display (ELD) in addition to the above-described PDP and FED.

  As described above, according to the present invention, the through-hole formed in the peripheral area of the edge of the glass substrate is a long hole extending in the direction along the one side closest to the hole forming position. Even if tensile stress acts on the peripheral region of the edge of the substrate in the direction along the one side, the portion where the stress acts is wide at both ends of the long hole in the direction perpendicular to the one side. As a result, stress concentration does not occur at the periphery of the long hole as in the case of the conventional circular through hole, and as a result, the glass substrate may be damaged such as cracking or causing breakage starting from the through hole. As much as possible.

It is a top view which shows the principal part of the glass substrate which concerns on 1st embodiment of this invention. It is a top view which shows the principal part of the glass substrate which concerns on 2nd embodiment of this invention. It is a top view which shows the principal part of the glass substrate which concerns on 3rd embodiment of this invention. It is a top view which shows the principal part of the glass substrate which concerns on 4th embodiment of this invention. (A)-(h) is a schematic plan view which shows the glass substrate of 1 piece taking and multi-face drawing to which this invention is applied. It is a schematic sectional drawing which shows the state by which the exhaust pipe was connected to the glass substrate which concerns on this invention. 6 is a plan view showing a main part of a glass substrate according to Comparative Example 1. FIG. 10 is a plan view showing a main part of a glass substrate according to Comparative Example 2. FIG. (A)-(h) is a schematic plan view which shows the conventional glass substrate of 1 piece taking and other chamfering. It is a principal part top view which shows the problem of the conventional glass substrate.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following embodiments, a glass substrate having a substantially rectangular flat plate shape for FPD will be described as an example.

  FIG. 1 is a plan view showing a main part of a glass substrate 1 having a substantially rectangular flat plate shape having four sides according to the first embodiment of the present invention. As shown in the figure, an edge peripheral area S (area with cross-hatching in the figure) of the glass substrate 1 according to the present embodiment has a length as an exhaust hole penetrating from the front surface to the back surface so that gas can flow. A hole 2 is formed. The long hole 2 is elongated in a direction (A-A direction) along one side 1a (hereinafter referred to as the first side 1a) of the glass substrate 1 closest to the hole forming position. That is, the length L1 of the long hole 2 in the direction along the first side 1a is longer than the length L2 in the direction orthogonal to the first side 1a.

More specifically, the long hole 2 is formed such that an imaginary straight line K passing through the center O ₁ and connecting one end and the other end in the longitudinal direction is parallel to the first side 1a. The contour shape (contour line) of the long hole 2 is a semicircular line 2a whose both longitudinal ends are convex toward the both end sides, and its longitudinal central portion has two semicircular shapes. A straight line 2b smoothly connected to the line 2a. Further, the length L1 of the long hole 2 is 1.2 times or more and 3 times or less of the length L2. In addition, the long hole 2 is formed in the central region LZ excluding the region LY of 12.5% of the total length LX of the first side 1a from both ends of the first side 1a in the glass substrate 1. In addition, the plate | board thickness of this glass substrate 1 is 0.5-3.0 mm. Further, the peripheral edge region S of the glass substrate 1 is a region having a distance of 50 mm or less from each side 1a, 1b in a direction perpendicular to the sides 1a, 1b. Further, the long hole 2 is formed by a helical spin drill, a water jet or the like.

  According to such a configuration, when the glass substrate 1 is subjected to a heat treatment, for example, inside the firing furnace, a tensile stress is generated in the peripheral edge region S. It acts in a direction parallel to one side 1a. Therefore, the stress as shown by the arrow T acts on the long hole 2, and this stress T is mainly composed of four points which are continuous contact points between the semicircular line 2 a and the straight line 2 b of the long hole 2. 2x acts in a distributed manner. As a result, the stress concentration on the periphery of the long hole 2 is alleviated, and it is difficult for the glass substrate 1 to be damaged such as being damaged starting from the long hole 2.

  FIG. 2 is a plan view showing a main part of the glass substrate 1 according to the second embodiment of the present invention. As shown in the figure, the glass substrate 1 according to the second embodiment is different from the glass substrate 1 according to the first embodiment described above in that the outline shape of the long hole 2 is along the first side 1a. It has a long oval shape in the direction. Thus, when the outline shape of the long hole 2 is an ellipse, when the tensile stress shown by the arrow T acts on this long hole 2, both ends of the long hole 2 in the direction orthogonal to the first side 1a Since 2c is made into the elongate curved surface which curves gently, stress concentration is relieve | moderated and it becomes difficult to produce the failure | damage etc. of the glass substrate 1 which makes the long hole 2 the starting point. Since the other configuration is the same as that of the glass substrate 1 according to the first embodiment described above, components common to both embodiments are denoted by the same reference numerals in FIG. 2 and description thereof is omitted.

  FIG. 3 is a plan view showing a main part of the glass substrate 1 according to the third embodiment of the present invention. As shown in the figure, the glass substrate 1 according to the third embodiment is different from the glass substrate 1 according to the first embodiment described above in that the outline shape of the long hole 2 is along the first side 1a. The three circular lines 2d are arranged so as to overlap each other in the direction, and the three circular lines 2d are connected so as to be smoothly connected to each other. Even when the long hole 2 having such a contour shape is formed, both end portions in the direction orthogonal to the first side 1a of the long hole 2 are long curved surfaces that are gently curved. The substantially same effect as that of the glass substrate 1 according to the first embodiment described above can be obtained. Since the other configuration is the same as that of the glass substrate 1 according to the first embodiment described above, components common to both embodiments are denoted by the same reference numerals in FIG. 3 and description thereof is omitted.

  FIG. 4 is a plan view showing a main part of the glass substrate 1 according to the fourth embodiment of the present invention. As shown in the figure, the glass substrate 1 according to the fourth embodiment differs from the glass substrate 1 according to the first embodiment described above in that the outline shape of the long hole 2 is along the first side 1a. Each intersection of the four straight lines 2e forming a long rhombus in the direction is smoothly connected by a partial circular line 2f. Even when the long hole 2 having such a contour shape is formed, both end portions in the direction orthogonal to the first side 1a of the long hole 2 are composed of long straight lines and curved lines that are gently inclined. Since it is set as a curved surface, the substantially same effect as the glass substrate 1 which concerns on the above-mentioned 1st embodiment is obtained. Since the other configuration is the same as that of the glass substrate 1 according to the first embodiment described above, components common to both embodiments are denoted by the same reference numerals in FIG. 4 and description thereof is omitted.

  FIG. 5 shows a glass substrate 1 used as a back plate for an FPD, for example, in which the long holes 2 shown in the first to fourth embodiments are formed as exhaust holes. And a multi-chambered one shown in FIGS. 2B to 2H. And about any of these glass substrates 1, the long hole 2 is formed only in the center area | region LZ except the area | region of 12.5% of the full length of this edge | side from the both ends of the object side, and exists in another area | region. The exhaust hole is formed as a circular through hole similar to the conventional one. Therefore, it is not necessary for all the glass substrates 1 to have all the exhaust holes as the long holes 2, thereby avoiding complicated drilling. Needless to say, the exhaust holes formed in regions other than the central region LZ of the glass substrate 1 may also be elongated.

  FIG. 6 is a schematic cross-sectional view showing a state in which an exhaust pipe 3 for exhausting is connected to the glass substrate 1 after the heat treatment. Since the exhaust pipe 3 has a circular cross section of the internal passage 3a, if the long hole 2 is too long in the longitudinal direction, the long hole 2 cannot be accommodated in the internal passage 3a of the exhaust pipe 3. When trying to accommodate this, the flow resistance when the gas passes through the long hole 2 increases excessively. Therefore, it is significant that the length L1 of the long hole 2 is not more than three times L2.

  As an example of the present invention, a long hole 2 having a contour shape as shown in FIG. 1 is formed in a peripheral region of an edge of a glass substrate 1 having a thickness of 1.8 mm, and the glass substrate 1 is heated. Then, a thermal stress test in which a tensile stress T of 25 Mpa was applied to the long hole 2 from both ends in the direction AA in FIG. In this case, the length L1 in the direction along the first side 1a of the long hole 2 was 3 mm, and the length L2 in the direction perpendicular to the first side 1a of the long hole 2 was 1.5 mm. As a result of this test, the stress concentration value in the long hole 2 was 61 MPa.

  On the other hand, as Comparative Example 1, as shown in FIG. 7, a long hole 2A elongated in the direction perpendicular to the first side 1a is formed in the peripheral region of the edge of the glass substrate 1 having a plate thickness of 1.8 mm. The glass substrate 1 was subjected to the same thermal stress test as in the above example, and a tensile stress T of 25 Mpa was applied to the long hole 2A from both ends in the direction AA in FIG. In this case, the length L1 in the direction along the first side 1a of the long hole 2A was 1.5 mm, and the length L2 in the direction orthogonal to the first side 1a of the long hole 2A was 3 mm. As a result of this test, the stress concentration value in the long hole 2A was 117 Mpa.

  Further, as Comparative Example 2, as shown in FIG. 8, a circular through hole 2B is formed in the peripheral region of the edge of the glass substrate 1 having a plate thickness of 1.8 mm. A thermal stress test similar to that of the example was performed, and a tensile stress T of 25 Mpa was applied to the circular through hole 2B from both ends in the direction AA in FIG. In this case, the diameter L3 of the circular through hole 2B was 1.5 mm. As a result of this test, the stress concentration value on the circular through hole 2B was 106 Mpa.

  From the above test results, in comparison with Comparative Examples 1 and 2, in the example of the present invention, the stress concentration value in the hole is approximately half, and the stress concentration in the hole during heat treatment is greatly relieved. confirmed.

1 Glass substrate 1a One side (first side)
2 Long hole 2a Substantially circular line (circular line)
2b Straight line S Edge peripheral region O ₁ Center of long hole LX Total length of side LZ Central region T Tensile stress

Claims (7)

In a glass substrate having a substantially rectangular flat plate shape having four sides and a through hole formed in the peripheral region of the edge,
The glass substrate is a glass substrate for a flat panel display,
The through hole, Ri long hole der possible long gas flow in a direction along the nearest one side from the hole forming position,
When the length in the direction along the one side is L1, and the length in the direction orthogonal to the one side is L2,
1.2 × L2 ≦ L1 ≦ 3 × L2
A glass substrate, which is formed so as to satisfy the above relationship .   2. The glass substrate according to claim 1, wherein the long hole passes through the center thereof, and an imaginary straight line connecting one end and the other end in the longitudinal direction is parallel to the one side.   3. The glass substrate according to claim 1, wherein a contour shape of the elongated hole is formed of a smoothly continuous curved line, or a straight line and a curved line that are smoothly connected to each other.   The outline shape of the elongated hole is a substantially semicircular line whose longitudinal ends are convex toward the both ends, and the longitudinal center is a straight line smoothly connected to the two substantially semicircular lines. It exists, The glass substrate in any one of Claims 1-3 characterized by the above-mentioned.   The glass substrate according to claim 1, wherein a contour shape of the long hole is an ellipse.   The said long hole is formed in the center part area | region which excluded the area | region of 12.5% of the full length of this one side from the both ends of said one side. The glass substrate as described. The glass substrate according to any one of claims 1 to 6 , wherein the glass substrate is a glass substrate for a flat panel display having a plate thickness of 0.5 to 3.0 mm.

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