TW201713974A - Glass plate - Google Patents

Abstract

A glass plate 12 having a light-emitting surface 26, a light-reflecting surface 32, and a light-incident end surface 28 that is perpendicular to the light-emitting surface 26 and the light-reflecting surface 32. A light-incident-side beveled surface 40 is provided so as to be adjacent to the light-emitting surface 26 and the light-incident end surface 28, and a light-incident-side beveled surface 40 is also provided so as to be adjacent to the light-reflecting surface 32 and the light-incident end surface 28. Given that the point at which the light-incident-side beveled surface 40 and the light-emitting surface 26 intersect is a first intersecting point P1 and the point at which the light-incident-side beveled surface 40 and the light-incident end surface 28 intersect is a second intersecting point P2, then the slope angle [Theta] of a line segment L connecting P1 and P2 relative to the light-incident end surface 28 satisfies the equation 0.01<=tan[Theta]<=0.75.

Description

glass plate

The present invention relates to a glass sheet.

A liquid crystal display device represented by a liquid crystal television or a digital signage includes a planar light-emitting device that constitutes a backlight, and a liquid crystal panel that is disposed to face the light emission of the planar light-emitting device. The planar light-emitting device has a direct-type type and an edge-illuminated type, but an edge-illuminated type that can realize miniaturization of a light source is often used. The edge-illuminated planar light-emitting device includes a light source, a light guide plate, a reflection sheet, and various optical sheets (a diffusion sheet, a brightness enhancement sheet, and the like). Patent Literatures 1 and 2 disclose a light guide plate in which a glass plate having a high internal transmittance, high rigidity, and excellent heat resistance is used as a planar light-emitting device.

The rigidity of the glass plate is higher than that of the acrylic plate used as the light guide plate, and the heat resistance is also excellent. However, if the glass plate is cut, the edge is sharp and dangerous, and the strength of the glass plate is lowered. . Therefore, the chamfering process of chamfering the edge is performed. Thereby, the edge of the glass plate has a chamfered surface that is inclined with respect to the main plane and the end surface of the glass sheet. As shown in Patent Document 3, the shape of the chamfered surface is generally a cross section perpendicular to the principal plane and the end surface of the glass sheet, and has an inclination angle of 45° with respect to the principal plane and the end surface.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2013-093195

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2013-030279

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2013/31548

SUMMARY OF THE INVENTION An object of the present invention is to provide a glass sheet which can be used as a light guide plate for, for example, a planar light-emitting device which can effectively utilize the amount of light of a light source.

According to an aspect of the present invention, a glass plate having a main plane and an end surface perpendicular to the main plane and having a chamfered surface adjacent to the main plane and the end surface is provided between the main plane and the end surface. The angle of inclination θ with respect to the end face of the line segment perpendicular to the main plane and the end surface, the first intersection point connecting the chamfered surface and the main plane, and the second intersection point where the chamfered surface intersects the end surface satisfies 0.01 ≦tanθ≦0.75.

According to another aspect of the present invention, a glass plate having a main plane and an end surface perpendicular to the main plane and having a chamfered surface adjacent to the main plane between the main plane and the end surface is provided The inclined surface between the corner surface and the end surface is a cross section perpendicular to the main plane and the end surface, and a first intersection where the chamfered surface intersects the main plane and a second intersection where the chamfered surface and the inclined surface intersect The line segment includes the chamfered surface so as to be inclined with respect to the end surface at an inclination angle θ ₁ , and the inclination angle θ ₁ satisfies 0.01 ≦ tan θ ₁ ≦ 0.75, and the line connecting the second intersection point and the third intersection point where the inclined surface intersects the end surface The inclination angle θ ₂ with respect to the end surface is smaller than the inclination angle θ ₁ and satisfies 0 < tan θ ₂ ≦ 0.4.

The glass plate according to the present invention can effectively utilize the amount of light of the light source when used as a light guide plate such as a planar light-emitting device.

10‧‧‧Liquid crystal display device

12, 112‧‧‧ glass plate

14‧‧‧Face light emitting device

16‧‧‧LCD panel

18‧‧‧Light source

20‧‧‧reflector

22‧‧‧Various optical sheets

24A, 24B, 24C‧‧‧ reflection points

26, 126‧‧‧ light exit surface

28, 128‧‧‧ light end face

30‧‧‧ reflector

32, 132‧‧‧ light reflecting surface

34, 36, 38‧‧‧ non-lighting end faces

40, 140‧‧‧ into the light side chamfered surface

42‧‧‧ Non-lighting side chamfering surface

44‧‧‧Glass raw materials

46‧‧‧ glass substrate

148‧‧‧ sloped surface

A‧‧‧ length

B‧‧‧ Length

D‧‧‧ Length

L‧‧‧ line segment

L11‧‧‧ line segment

L12‧‧‧ line segment

La‧‧‧1st extension cord

L _A ‧‧‧diameter

Lb‧‧‧2nd extension cord

L _B ‧‧‧diameter

L _C ‧‧‧diameter

P1‧‧‧1st intersection

P2‧‧‧2nd intersection

P3‧‧‧3rd intersection

P4‧‧‧4th intersection

P11‧‧‧1st intersection

P12‧‧‧2nd intersection

P13‧‧‧3rd intersection

S10‧‧‧ steps

Step S12‧‧‧

S14‧‧‧ steps

S16‧‧ steps

T‧‧‧thickness

T‧‧‧ tangent

W‧‧‧ length

Θ‧‧‧ tilt angle

θ ₁ ‧‧‧ tilt angle

θ ₂ ‧‧‧ tilt angle

Fig. 1 is a side view showing a liquid crystal display device having a schematic configuration of a liquid crystal display device.

Figure 2 is a plan view of a glass plate.

Figure 3 is an overall perspective view of a glass sheet.

Fig. 4 is an enlarged cross-sectional view of a glass plate (a part of which is omitted).

Fig. 5 is a process chart showing a method of manufacturing a glass sheet according to an embodiment.

Figure 6 is a plan view of a glass raw material of a glass plate.

Fig. 7 is a plan view of a glass substrate from which a glass raw material is cut out.

Fig. 8 is an enlarged cross-sectional view showing the main part of a glass plate having a circular arc shape in a cross-sectional shape on a light side chamfered surface.

Fig. 9 is a graph showing the ratio of non-waveguide light to tan θ in a glass plate having a thickness of 1.7 mm.

Fig. 10 is a table showing the data necessary for calculating the ratio of the non-waveguide light of Fig. 9 by simulation.

Figure 11 is a graph showing the ratio of non-waveguide light to tan θ in a glass plate having a thickness of 2.5 mm.

Fig. 12 is a table showing the data necessary for calculating the ratio of the non-waveguide light of Fig. 11 by simulation.

Figure 13 is an enlarged partial cross-sectional view showing a glass plate in another embodiment.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings.

In the description of the drawings, the same or corresponding components or components are denoted by the same or corresponding reference numerals, and the description thereof will not be repeated. Further, the drawings are not intended to indicate the relative ratio between members or parts unless otherwise specified. Therefore, the specific dimensions can be determined by the operator with reference to the following non-limiting embodiments.

[Liquid Crystal Display Device 10]

FIG. 1 is a side view showing a liquid crystal display device 10 having a schematic configuration of a liquid crystal display device 10. 2 is a plan view of the glass sheet 12 incorporated in the embodiment of the liquid crystal display device 10.

As shown in FIG. 1, the liquid crystal display device 10 includes a planar light-emitting device 14 having a glass plate 12 and a liquid crystal panel 16. The liquid crystal display device 10 is mounted on, for example, a liquid crystal television. A signage card or the like realizes a thinned electronic machine.

<LCD panel 16>

The liquid crystal panel 16 is formed by laminating an alignment layer, a transparent electrode, a glass substrate, and a polarizing filter so as to sandwich a liquid crystal layer disposed at the center in the thickness direction. Further, a color filter is disposed on one side of the liquid crystal layer. The molecular layer of the liquid crystal layer is rotated around the optical axis by applying a driving voltage to the transparent electrode, thereby performing a specific display.

<Face-shaped light-emitting device 14>

As the planar light-emitting device 14, an edge illumination type for achieving a reduction in thickness is employed. The planar light-emitting device 14 includes a light source 18, a glass plate 12, a reflection sheet 20, various optical sheets 22 (a diffusion sheet, a brightness enhancement sheet, and the like), and reflection points 24A to 24C.

The light incident from the light source 18 to the inside of the glass plate 12 is advanced as shown by the arrow of Fig. 1 on the inner surface of the light exit surface 26 of the glass plate 12 and the inner surface of the light reflecting surface 32 over the total reflection surface. Further, the light whose direction of advancement is changed by the reflection points 24A to 24C and the reflection sheet 20 is emitted from the light exit surface 26 of the glass sheet 12 opposed to the liquid crystal panel 16 to the outside. The light that has been emitted to the outside is diffused by various optical sheets (which may be composed of a diffusion sheet, a brightness enhancement sheet, or the like, and may be plural or plural) 22, and then incident on the liquid crystal panel 16.

The light source 18 is not particularly limited, and an LED (Light Emitting Diode), a hot cathode tube, or a cold cathode tube can be used. The light source 18 is disposed at a position opposed to the light incident end surface 28 of the glass sheet 12.

Further, by providing the reflector 30 on the back side of the light source 18, the incident efficiency of the light emitted from the light source 18 to the glass plate 12 is increased.

The reflection sheet 20 is configured by coating a light reflection member on the surface of a resin sheet such as an acrylic resin. The reflection sheet 20 is disposed to face the light reflection surface 32 of the glass sheet 12. Further, the reflection sheet 20 may be disposed on the non-light-incident end faces 34, 36, 38 (see FIG. 2). The reflection sheet 20 may be disposed in a space apart from the glass sheet 12, or may be attached to the glass sheet 12 by an adhesive. The light reflecting surface 32 is a principal plane of the glass plate 12 opposite to the light exit surface 26. Further, the light incident end surface 28 is an end surface of the glass plate 12 opposed to the light source 18. The non-light-incident end faces 34, 36, 38 are end faces of the glass plate 12 except for the light end face 28.

In addition, when the reflection sheet 20 is disposed on the non-light-incident end surface, it is only required to be disposed at least in the non-light-incident end surface 28 opposite to the light-incident end surface 28 of the non-light-incident end faces 34, 36, 38. . Thereby, the light incident from the light incident end surface 28 is totally totally reflected inside the glass plate 12, and a direction away from the light source (toward the right direction in FIGS. 1 and 2), reaching to the non-light-incident end face. At 380, it is reflected again to the inside of the glass sheet 12 by the reflection sheet 20. Moreover, when the reflection sheet 20 is also disposed on the non-light-incident end faces 34, 36, the light scattered inside the glass plate 12 by the reflection sheet 20 can be again reached when reaching the non-light-incident end faces 34, 36. Reflected to the inside of the glass sheet 12. Thereby, the amount of light of the light source 18 can be effectively utilized.

The acrylic resin is exemplified as the material of the resin sheet constituting the reflection sheet 20, but the acrylic resin is not limited thereto. For example, a polyester resin such as PET (polyethylene terephthalate) resin or a urethane can be used. An ester resin, a material obtained by combining the same, and the like.

As the light reflecting member constituting the reflection sheet 20, for example, a film in which bubbles or particles are contained in a resin, a metal deposition film, or the like can be used.

An adhesive layer may be provided on the reflection sheet 20 and attached to the glass plate 12. As the adhesive layer provided on the reflection sheet 20, for example, an acrylic resin, a polyoxymethylene resin, a urethane resin, a synthetic rubber or the like can be used.

The thickness of the reflection sheet 20 is not particularly limited, and for example, 0.01 to 0.50 mm can be used.

As the various optical sheets 22, a milky white acrylic resin film or the like can be used. Since the various optical sheets 22 diffuse the light emitted from the light exit surface 26 of the glass sheet 12, uniform light having no unevenness in brightness is irradiated onto the back surface side of the liquid crystal panel 16. Further, the various optical sheets 22 are disposed opposite to each other so as not to be in contact with the glass sheet 12.

<Physical properties of the glass plate 12>

The glass plate 12 is composed of a glass having a high transparency. In the embodiment, as a use As the material of the glass of the glass plate 12, a multi-component oxide glass is used.

Specifically, as the glass plate 12, it is preferable to use a glass having an average internal transmittance of 90% or more at a wavelength of 400 to 700 nm at a length of 50 mm. Thereby, the attenuation of light incident on the glass plate 12 can be suppressed as much as possible. The transmittance at a length of 50 mm is obtained by cutting the glass sheet 12 in a direction perpendicular to the main plane, and sampling from the central portion of the glass sheet at a length of 50 mm × a width of 50 mm to the first and second sides facing each other. In the sample A prepared in such a manner that the cut surface has an arithmetic mean roughness Ra ≦ 0.03 μm, the beam width of the incident light is narrower than the plate thickness by a slit or the like with a length of 50 mm from the normal direction of the first cut surface. The measurement was carried out by a spectroscopic measuring device (for example, UH4150: manufactured by Hitachi High-Technologies Corporation) which can measure the length of 50 mm. The transmittance at a length of 50 mm obtained in the above manner removes the loss caused by the reflection of the surface, thereby obtaining the internal transmittance at a length of 50 mm. The average internal transmittance at a wavelength of 400 to 700 nm at a length of 50 mm is preferably 92% or more, more preferably 95% or more, further preferably 98% or more, and particularly preferably 99% or more.

The total amount A of the content of iron used as the glass of the glass plate 12 is preferably 100 ppm by mass or less, more preferably 40%, in terms of satisfying the average internal transmittance at a wavelength of 400 to 700 nm in the above 50 mm length. It is preferably ppm or less, more preferably 20 ppm by mass or less. On the other hand, the total amount A of the content of iron used as the glass of the glass plate 12 is preferably 5 ppm by mass or more, more preferably in terms of improving the meltability of the glass in the production of the multi-component oxide glass. It is 8 ppm by mass or more, and more preferably 10 ppm by mass or more. Further, the total amount A of the content of iron used as the glass of the glass plate 12 can be adjusted by the amount of iron added when the glass is produced.

In the present specification, the total amount A of the content of iron in the glass is expressed as the content of Fe ₂ O ₃ , but not all of the iron present in the glass exists in the form of Fe ³⁺ (trivalent iron). Usually, Fe ³⁺ and Fe ²⁺ (bivalent iron) are present in the glass. Fe ²⁺ and Fe ³⁺ absorb in the range of wavelength 400~700nm, but the absorption coefficient of Fe ²⁺ (11cm ^-1 Mol ^-1 ) is larger than that of Fe ³⁺ (0.96cm ^-1 Mol ^-1 ) Ten times, the internal transmittance at a wavelength of 400 to 700 nm is further lowered. Therefore, in terms of increasing the internal transmittance at a wavelength of 400 to 700 nm, it is preferred that the content of Fe ²⁺ is small.

The content B of Fe ²⁺ used as the glass of the glass sheet 12 is preferably 20 ppm by mass or less, more preferably 10 ppm by mass or less, in terms of satisfying the average internal transmittance of the visible light region under the effective optical path length. Further, it is preferably 5 ppm by mass or less. On the other hand, in terms of improving the meltability of the glass in the production of the multi-component oxide glass, the content B of Fe ²⁺ used as the glass of the glass plate 12 is preferably 0.01 ppm by mass or more, more preferably 0.05 mass ppm or more, further preferably 0.1 mass ppm or more.

Further, the content of Fe ²⁺ used as the glass of the glass plate 12 can be adjusted depending on the amount of the oxidizing agent added at the time of glass production, the melting temperature, and the like. The specific type of the oxidizing agent added when the glass is produced and the amount of the oxidizing agent added thereto will be described later. Fe ₂ O ₃ content of the A-type fluorescent X-ray measurement is determined by the content of the total iron in terms of Fe ₂ O ₃ of (mass ppm). The content B of Fe ²⁺ was measured in accordance with ASTM C169-92. Further, the content of Fe ²⁺ measured is measured in terms of Fe ₂ O ₃ .

Specific examples of the composition of the glass used as the glass plate 12 are shown below. However, the composition of the glass used as the glass plate 12 is not limited to these.

A configuration example (constitution example A) of the glass used as the glass plate 12 is expressed by mass percentage based on oxide, and includes SiO ₂ 60 to 80%, Al ₂ O ₃ 0 to 7%, MgO 0 to 10%, and CaO 0 . ~20%, SrO 0~15%, BaO 0~15%, Na ₂ O 3~20%, K ₂ O 0~10%, Fe ₂ O ₃ 5~100 mass ppm.

Another configuration example (constitution example B) of the glass used as the glass plate 12 is expressed by mass percentage based on oxide, and includes SiO ₂ 45 to 80%, Al ₂ O _{3 of} more than 7% and 30% or less, and B ₂ O _{3 .} 0~15%, MgO 0~15%, CaO 0~6%, SrO 0~5%, BaO 0~5%, Na ₂ O 7~20%, K ₂ O 0~10%, ZrO ₂ 0~10 %, Fe ₂ O ₃ 5 to 100 ppm by mass.

Another configuration example (constitution example C) of the glass used as the glass plate 12 is represented by mass percentage of the oxide standard, and includes SiO ₂ 45 to 70%, Al ₂ O ₃ 10 to 30%, and B ₂ O ₃ 0 to 15 The total amount of %, MgO, CaO, SrO, and BaO is 5 to 30%, and Li ₂ O, Na ₂ O, and K ₂ O are 0% or more in total and less than 3%, and Fe ₂ O _{3 is} 5 to 100 ppm by mass.

However, the glass used as the glass plate 12 is not limited to these.

Hereinafter, the composition range of each component of the composition of the glass of the glass plate 12 of the present embodiment having the above-described composition will be described. Further, the unit of the content of each component is expressed by the mass percentage of the oxide standard or the mass ppm, and is simply expressed as "%" or "ppm".

The main component of SiO ₂ -based glass.

In order to ensure the weather resistance and devitrification resistance of the glass, the content of SiO ₂ is preferably 60% or more, more preferably 63% or more in the configuration example A, and more preferably 45% or more in the configuration example B, more preferably It is 50% or more, and in Structural Example C, it is preferably 45% or more, and more preferably 50% or more.

On the other hand, in order to facilitate the melting, the quality of the bubbles is good, and in order to suppress the content of ferrous iron (Fe ²⁺ ) in the glass to be low, the optical characteristics are good, and the content of SiO ₂ is in the configuration example A. Preferably, it is 80% or less, more preferably 75% or less, and in Structural Example B, it is preferably 80% or less, more preferably 70% or less, and in Structural Example C, it is preferably 70% or less, more preferably 65. %the following.

Al ₂ O ₃ is an essential component for improving the weather resistance of the glass in the constituent examples B and C. In the glass of the present embodiment, in order to maintain the weather resistance necessary for practical use, the content of Al ₂ O ₃ is preferably 1% or more, more preferably 2% or more in the configuration example A, and in the configuration example B, It is preferably more than 7%, more preferably 10% or more, and in Composition Example C, it is preferably 10% or more, and more preferably 13% or more.

However, in order to suppress the content of the ferrous iron (Fe ⁺ ) to a low level, the optical characteristics are good, and the bubble quality is good, and the content of Al ₂ O ₃ is preferably 7% or less, more preferably 7% or less, in the configuration example A. It is 5% or less, and is preferably 30% or less, more preferably 23% or less in the configuration example B, and is preferably 30% or less, more preferably 20% or less in the configuration example C.

B ₂ O ₃ is a component that promotes melting of a glass raw material and improves mechanical properties or weather resistance, and the content of B ₂ O ₃ is in glass A in order to prevent problems such as ream and erosion of the furnace wall due to volatilization. The amount is preferably 5% or less, more preferably 3% or less, and in the configuration examples B and C, it is preferably 15% or less, more preferably 12% or less.

An alkali metal oxide such as Li ₂ O, Na ₂ O, or K ₂ O is a useful component for promoting melting of a glass raw material and adjusting thermal expansion and viscosity.

Therefore, the content of Na ₂ O is preferably 3% or more, and more preferably 8% or more in the configuration example A. The content of Na ₂ O is preferably 7% or more, and more preferably 10% or more in the configuration example B. However, in order to maintain the clarity at the time of melting, the bubble quality of the glass to be produced is ensured, and the content of Na ₂ O is preferably 20% or less, and more preferably 15% or less in the configuration examples A and B. In Structural Example C, it is preferably 3% or less, and more preferably 1% or less.

In addition, the content of K ₂ O is preferably 10% or less, more preferably 7% or less, and is preferably 2% or less, and more preferably 1% or less in Structural Example C.

Further, Li ₂ O is an optional component, and in order to facilitate the vitrification, the iron content contained in the form of impurities derived from the raw material is suppressed to be low, and the batch cost is suppressed to be low, in the configuration examples A, B, and C. In the middle, it may contain 2% or less of Li ₂ O.

Further, in order to maintain the time of melting and fining the bubble to ensure the quality of the manufactured glass, the total content of such alkali metal oxides _{(Li 2 O + Na 2 O} + K 2 O) in Examples A and B configuration, more Preferably, it is 5% to 20%, more preferably 8% to 15%, and in the composition example C, it is preferably 0% to 2%, more preferably 0% to 1%.

An alkaline earth metal oxide such as MgO, CaO, SrO, or BaO is a useful component for promoting melting of a glass raw material and adjusting thermal expansion and viscosity.

MgO has the effect of lowering the viscosity at the time of glass melting and promoting melting. Further, since it has a function of lowering the specific gravity and is less likely to cause enthalpy to the glass sheet, it can be contained in the configuration examples A, B, and C. Moreover, in order to lower the thermal expansion coefficient of the glass, the devitrification property is good, and MgO is The content of the composition example A is preferably 10% or less, more preferably 8% or less, and in the configuration example B, it is preferably 15% or less, more preferably 12% or less, and in the configuration example C, it is preferably 10% or less, more preferably 5% or less.

Since CaO promotes melting of a glass raw material and adjusts components such as viscosity and thermal expansion, it can be contained in Structural Examples A, B, and C. In order to obtain the above effects, in the configuration example A, the content of CaO is preferably 3% or more, more preferably 5% or more. In addition, in the configuration example A, it is preferably 20% or less, more preferably 10% or less, and in the configuration example B, it is preferably 6% or less, and more preferably 4% or less.

SrO has the effect of increasing the coefficient of thermal expansion and lowering the high temperature viscosity of the glass. In order to obtain this effect, in the configuration examples A, B, and C, SrO may be contained. However, in order to suppress the thermal expansion coefficient of the glass to be low, the content of SrO is preferably 15% or less, more preferably 10% or less in the configuration examples A and C. It is set to 5% or less, and more preferably set to 3% or less.

BaO has the same effect of increasing the coefficient of thermal expansion and lowering the high temperature viscosity of the glass, similarly to SrO. In order to obtain the above effects, BaO may be contained. However, in order to suppress the thermal expansion coefficient of the glass to be low, in the configuration examples A and C, it is preferably 15% or less, more preferably 10% or less, and in the configuration example B, it is preferably set to 5% or less, more preferably 3% or less.

Further, in order to suppress the thermal expansion coefficient to a low level, to improve the devitrification property, and to maintain the strength, the total content of the alkaline earth metal oxides (MgO + CaO + SrO + BaO) is preferably 10% in the configuration example A. ~30%, more preferably 13% to 27%, in Composition B, preferably 1% to 15%, more preferably 3% to 10%, and in Composition C, preferably 5% to 30% %, more preferably 10% to 20%.

In the glass composition of the glass of the glass plate 12 of the present embodiment, in order to improve the heat resistance and surface hardness of the glass, the composition examples A, B, and C may contain 10% or less, preferably 5% or less of ZrO _{2 .} As an optional ingredient. By setting it to 10% or less, glass becomes hard to devitrify.

In the glass composition of the glass of the glass plate 12 of the present embodiment, in order to improve the meltability of the glass, the composition examples A, B, and C may contain 5 to 100 ppm of Fe ₂ O ₃ . Further, the preferred range of the amount of Fe ₂ O ₃ is as described above.

Further, the glass of the glass plate 12 of the present embodiment may contain SO ₃ as a clarifying agent. In this case, the SO ₃ content is expressed by mass percentage, preferably more than 0% and 0.5% or less. It is more preferably 0.4% or less, further preferably 0.3% or less, further preferably 0.25% or less.

Further, the glass of the glass plate 12 of the present embodiment may contain one or more of Sb ₂ O ₃ , SnO ₂ and As ₂ O ₃ as an oxidizing agent and a clarifying agent. In this case, the content of Sb ₂ O ₃ , SnO ₂ or As ₂ O ₃ is expressed by mass percentage, preferably 0 to 0.5%. It is more preferably 0.2% or less, further preferably 0.1% or less, and further preferably substantially not contained.

However, since Sb ₂ O ₃ , SnO ₂ and As ₂ O ₃ act as oxidizing agents for glass, it is also possible to adjust the amount of Fe ^{2+ in} the glass for the purpose of adding in the above range. However, in terms of the environment, it is preferred that substantially no As ₂ O ₃ is contained.

Further, the glass of the glass plate 12 of the present embodiment may contain NiO. When NiO is contained, NiO also functions as a coloring component. Therefore, the content of NiO is preferably 10 ppm or less based on the total amount of the glass composition. In particular, NiO is preferably 1.0 ppm or less, and more preferably 0.5 ppm or less from the viewpoint of not lowering the internal transmittance of the glass plate at a wavelength of 400 to 700 nm.

Aspect of this embodiment of the glass sheet glass 12 may also contain Cr ₂ O _3. When Cr ₂ O ₃ is contained, Cr ₂ O ₃ also functions as a coloring component. Therefore, the content of Cr ₂ O ₃ is preferably 10 ppm or less based on the total amount of the glass composition. In particular, from the viewpoint of lowering the internal transmittance of the glass plate at a wavelength of 400 to 700 nm, Cr ₂ O _{3 is} preferably 1.0 ppm or less, more preferably 0.5 ppm or less.

Aspect of this embodiment of the glass sheet glass 12 may also contain MnO _2. When MnO ₂ is contained, MnO ₂ also functions as a component that absorbs visible light. Therefore, the content of MnO ₂ is preferably 50 ppm or less based on the total amount of the glass composition. In particular, from the viewpoint of lowering the internal transmittance of the glass plate at a wavelength of 400 to 700 nm, MnO _{2 is} preferably 10 ppm or less.

The glass of the glass plate 12 of this embodiment may also contain TiO ₂ . When TiO ₂ is contained, TiO ₂ also functions as a component that absorbs visible light. Therefore, the content of TiO ₂ is preferably 1000 ppm or less based on the total amount of the glass composition. From the viewpoint of lowering the internal transmittance of the glass plate at a wavelength of 400 to 700 nm, the content of TiO _{2 is} preferably 500 ppm or less, and more preferably 100 ppm or less.

The glass of the glass plate 12 of this embodiment may also contain CeO ₂ . CeO ₂ has the effect of reducing the redox of iron and can reduce the ratio of the amount of Fe ²⁺ to the total amount of iron. On the other hand, in order to suppress the reduction of the redox of iron to less than 3%, the content of CeO ₂ is preferably set to 1000 ppm or less based on the total amount of the glass composition. Further, the content of CeO ₂ is more preferably 500 ppm or less, further preferably 400 ppm or less, more preferably 300 ppm or less, and most preferably 250 ppm or less.

The glass of the glass plate 12 of the present embodiment may further contain at least one component selected from the group consisting of CoO, V ₂ O ₅ and CuO. When the components are contained, since they function as a component that absorbs visible light, the content of the above components is preferably 10 ppm or less based on the total amount of the glass composition. It is particularly preferable that the components are not substantially contained so that the internal transmittance of the glass plate having a wavelength of 400 to 700 nm is not lowered.

<Shape of glass plate 12>

3 is an overall perspective view of the glass sheet 12, and FIG. 4 is an enlarged cross-sectional view of the glass sheet 12. Further, in Fig. 4, a portion of the cross section perpendicular to the principal plane and the light incident end surface 28 is enlarged and shown.

The glass plate 12 having a rectangular shape in plan view has a light exit surface 26, a light reflecting surface 32, a light incident end surface 28, non-light incident end faces 34, 36, 38, a light incident side chamfer surface 40, and a non-light incident side chamfer surface 42. .

Here, the light exit surface 26 and the light reflecting surface 32 correspond to the principal plane of the embodiment, and the light incident end surface 28 corresponds to the end surface of the embodiment. Further, the light incident side chamfered surface 40 corresponds to the chamfered surface of the present embodiment.

The light exit surface 26 is opposed to the liquid crystal panel 16. In the embodiment, the light exit surface 26 is formed in a rectangular shape in plan view, but the shape of the light exit surface 26 is not limited thereto. Further, since the size of the light exit surface 26 is determined in accordance with the liquid crystal panel 16, it is not particularly limited. When the glass plate 12 is used as the light guide plate, for example, it is preferably 500 mm × 500 mm or more. Since the glass plate 12 has a high rigidity, the larger the size, the more the effect is exerted.

The light reflecting surface 32 is opposed to the light emitting surface 26 . The light reflecting surface 32 is configured to be parallel to the light emitting surface 26 . Further, the shape and size of the light reflecting surface 32 are configured to be the same as the light emitting surface 26.

Further, the light reflecting surface 32 is not necessarily required to be parallel to the light emitting surface 26, and may be configured to have a step or a tilt. Further, the size of the light reflecting surface 32 may be set to be different from the light emitting surface 26.

As shown in FIGS. 1 and 2, the light reflecting surface 32 is provided with a plurality of circular reflecting points 24A, 24B, and 24C. The arrangement of the reflection points may be a grid shape as shown in FIG. 2, or may be any other pattern, or may be a random shape, and the distribution of the brightness of the light emitted from the light exit surface 26 may be uniform. Appropriate adjustments. The reflection points 24A to 24C are formed by printing a resin into a dot shape or the like, and may also contain scattering particles or bubbles. The light incident from the light incident end face 28 has a strong brightness, but its brightness gradually decreases as one side is reflected back inside the glass plate 12.

Therefore, in the embodiment, the sizes of the reflection points 24A, 24B, and 24C are different from the light incident end surface 28 toward the non-light incident end surface 38. Specifically, the diameter (L _A ) of the reflection point 24A in the region close to the light incident end face 28 is set to be small, and the diameter (L _B ) of the reflection point 24B is changed as it goes further toward the light forward direction. And the diameter (L _C ) of the reflection point 24C is increased (L _A <L _B <L _C ). The diameter of the reflection point is appropriately adjusted so that the distribution of the brightness of the light emitted from the light exit surface 26 becomes uniform.

By changing the size of the reflection points 24A, 24B, and 24C toward the inside of the glass plate 12, the brightness of the emitted light emitted from the light exit surface 26 can be made uniform, thereby suppressing uneven brightness. . Further, by changing the number of the reflection points 24A, 24B, and 24C in place of the reflection points 24A, 24B, and 24C, the light toward the inside of the glass sheet 12 is changed in the forward direction, and the same effect can be obtained. Further, the same effect can be obtained by forming a groove in which the incident light is reflected by the light reflecting surface 32 instead of the reflection points 24A, 24B, and 24C.

Since the non-light-incident end faces 34, 36, and 38 of the glass plate 12 do not cause light from the light source 18 to enter, it is not necessary to process the surface with high precision until the light-incident end face 28 is reached, and the surface roughness Ra is only It can be 0.8 μm or less. However, in order to suppress unevenness in luminance due to scattering of light at the end faces, the surface roughness Ra of the non-light-incident end faces 34, 36, and 38 is preferably 0.4 μm or less, and more preferably 0.1 μm or less. In the present specification, when it is described as the surface roughness Ra, it means the arithmetic mean roughness (center line average roughness) obtained in accordance with JIS B 0601 to JIS B 0031.

The light incident end face 28 is mirror finished when the glass as the glass plate 12 is manufactured. In order to efficiently inject light from the light source 18 into the inside of the glass sheet 12, the surface roughness Ra of the light incident end surface 28 is 0.1 μm or less, preferably less than 0.03 μm, more preferably 0.001 μm or less, and particularly preferably It is 0.0005 μm or less. Therefore, the incidence efficiency of light incident from the light source 18 into the inside of the glass plate 12 is increased. The surface roughness Ra of the non-light-incident end faces 34, 36, 38 may be equal to the surface roughness Ra of the light-incident end face 28 or may be larger than the surface roughness Ra of the light-incident end face 28 from the viewpoint of improving production efficiency.

<light side chamfering surface 40 (chamfered surface)>

A light incident side chamfering surface 40 is provided between the light exit surface 26 and the light incident end surface 28 and between the light reflecting surface 32 and the light incident end surface 28. That is, between the light exit surface 26 and the light incident end surface 28, The light exit surface 26 and the light incident end surface 28 are provided adjacent to the light incident side chamfer surface 40. Similarly, between the light reflecting surface 32 and the light incident end surface 28, the light incident side chamfering surface 40 is provided adjacent to the light reflecting surface 32 and the light incident end surface 28.

In the embodiment, the light-emitting side chamfering surface 40 is provided between the light-emitting surface 26 and the light-incident end surface 28, and the light-reflecting surface 32 and the light-incident end surface 28 are both provided. One of them has a configuration in which the light-incident side chamfered surface 40 is provided. Moreover, the surface roughness Ra of the light-incident side chamfering surface 40 is preferably 0.8 μm or less, more preferably 0.4 μm or less, and still more preferably 0.1 μm or less. By setting the surface roughness Ra of the light-incident side chamfering surface 40 to 0.8 μm or less, unevenness in brightness due to light emitted from the glass plate 12 can be suppressed. In other respects, by setting the surface roughness Ra of the light incident side chamfer surface 40 to 0.8 μm or less, the incident light can be efficiently extracted to the glass plate 12. In addition, by setting the surface roughness Ra of the light-incident side chamfering surface 40 to 0.4 μm or less, the amount of glass swarf generated can be suppressed. On the other hand, the lower limit of the surface roughness Ra of the light-incident side chamfering surface 40 is not limited, and the smaller the Ra, the more the unevenness of the brightness of the glass sheet 12 can be suppressed, but the chamfering step (S12) is correspondingly performed. It takes time. The surface roughness Ra of the light-incident side chamfered surface 40 is preferably larger than the surface roughness Ra of the light-incident end surface 28 from the viewpoint of improving production efficiency. Here, the surface roughness Ra of each of the non-light-incident side chamfered surfaces 42 of the non-light-incident end faces 34, 36, and 38 is preferably 0.8 μm or less. By setting as described above, when a reflection band is provided on the non-light-incident end surface and/or the non-light-incident side chamfering surface, the non-light-incident end surface and/or the non-light-incident side chamfer surface can be temporarily leaked. The light is reflected by the reflection band and is incident efficiently again from the non-light-incident side chamfered surface.

In addition, the shape, action, and effect of the light-incident side chamfer surface 40 will be described in the column of the characteristics of the glass plate 12 described below.

In the planar light-emitting device 14 which is required to be thinned as in the embodiment, it is also necessary to make the thickness of the glass plate 12 thin. Therefore, the thickness of the glass plate 12 of the embodiment is 0.7 to 3.0 mm. By making the thickness of the glass plate 12 3.0 mm or less, the planar light-emitting device 14 can be made thin, and by making it 0.7 mm or more, sufficient rigidity can be obtained. Furthermore, the glass plate 12 The thickness is not limited to this value, but even if it is this thickness, the planar light-emitting device 14 having sufficient strength as compared with the planar light-emitting device having a light guide plate made of acrylic having a thickness of 4 mm or more can be provided.

[Manufacturing Method of Glass Plate 12]

5, 6, and 7 are views for explaining a method of manufacturing the glass sheet 12. Fig. 5 is a view showing the steps of a method of manufacturing the glass sheet 12. 6 is a plan view of the glass material 44, and FIG. 7 is a plan view of the glass substrate 46.

When manufacturing the glass sheet 12, the glass raw material 44 of Fig. 6 is first prepared. The thickness of the glass material 44 is 0.7 to 3.0 mm, and the average internal transmittance at a wavelength of 400 to 700 nm at a length of 50 mm is 90% or more. The glass raw material 44 is set to have a shape larger than the predetermined shape of the glass plate 12.

<cutting step>

First, the glass raw material 44 is subjected to the cutting step shown in the step (S) 10 of Fig. 5 . In the cutting step (S10), the cutting device is used to perform the cutting process at each position (the position on the light-incident end side and the position on the non-light-incident end face side) shown by the broken line in Fig. 6 . In addition, it is not necessary to perform cutting processing at the position of the three non-light-incident end faces, and it is also possible to cut only the position on the non-light-incident end face side opposite to the position on the light-incident end face side. .

The glass substrate 46 of Fig. 7 is cut out from the glass material 44 of Fig. 6 by performing a cutting process. In addition, in the embodiment, the glass plate 12 has a rectangular shape in plan view. Therefore, the position of the light incident end surface side and the position of the three non-light incident end faces are cut, and the cutting position is performed. It is suitably selected according to the shape of the glass plate 12.

Further, as the cutting method of the glass material 44, for example, a scribing method or a laser cutting method can be applied. From the viewpoint of productivity, the scribing method is preferred. Further, in the case where the light incident side chamfered surface 40 is formed into an arc shape, it is preferable to use a laser cutting method in which the cut cross section is an arc shape.

<1st chamfering step>

As shown in Fig. 5, when the cutting step (S10) is completed, the first chamfering step (S12) is performed. In the first chamfering step (S12), a non-light-in side is formed between the light-emitting surface 26 and the non-light-incident end surface 38, and between the light-reflecting surface 32 and the non-light-incident end surface 38, respectively, using a grinding device. Chamfered surface 42.

Furthermore, between the light exit surface 26 and the non-light incident end surface 34, between the light reflecting surface 32 and the non-light incident end surface 34, between the light exit surface 26 and the non-light incident end surface 36, and the light reflecting surface 32 When the non-light-incident side chamfered surface 42 is formed at all or any of the non-light-incident end faces 36, the chamfering process is performed in the first chamfering step (S12).

Further, from the viewpoint of productivity, it is preferable to perform between the light exit surface 26 and the light incident end surface 28 or between the light reflecting surface 32 and the light incident end surface 28 in the first chamfering step (S12). Chamfer processing. In this case, from the viewpoint of productivity, the surface roughness Ra of the obtained light-incident side chamfered surface 40' (not shown) is preferably larger than that obtained in the second chamfering step described below. The surface roughness Ra of the side chamfered surface 40. Thereby, the light incident side chamfered surface 40' is formed, and the inclination angle θ of the line segment L of the following P1 and P2 to the light incident end surface 28 is not particularly limited.

In the first chamfering step (S12), the non-light-incident end faces 34, 36, 38 are also subjected to a grinding process or a grinding process. The period in which the non-light-incident end faces 34, 36, and 38 are subjected to the grinding treatment or the polishing treatment may be performed in the front stage or the rear stage in which the non-light-incident side chamfered surface 42 is formed, or may be simultaneously performed. Further, regarding the non-light-incident end faces 34 and 36, the surface subjected to the cutting process may be directly used as the non-light-incident end faces 34 and 36.

From the viewpoint of productivity, it is preferable that the light incident end surface 28 is also subjected to a grinding treatment or a polishing treatment in the first chamfering step (S12). The period in which the light-incident end surface 28 is subjected to the grinding treatment or the polishing treatment may be performed in the front stage or the rear stage in which the light-incident side chamfered surface 42 is formed, or may be simultaneously performed.

The first chamfering step (S12) may be performed simultaneously with the mirror processing step (S14) and the second chamfering step (S16), or at a later stage thereof, preferably before the preceding stage. Row. Thereby, the processing corresponding to the shape of the glass sheet 12 can be performed at a relatively fast rate in the first chamfering step (S12), so that productivity is improved.

<Mirror surface processing step>

When the first chamfering step (S12) is completed, the mirror finishing step (S14) is performed. In the mirror processing step (S14), the light incident end surface 28 of the glass substrate 46 shown in Fig. 7 is mirror-finished to form the light incident end surface 28 having a surface roughness Ra of 0.1 μm or less.

<2nd chamfering step>

When the light incident end surface 28 is formed in the glass substrate 46 in the mirror surface processing step (S14), the second chamfering step (S16) is performed, and between the light exit surface 26 and the light incident end surface 28, and the light reflecting surface 32. A grinding process or a grinding process is performed between the light incident end face 28 and the light incident end face 28. Thereby, the light incident side chamfer surface 40 is formed. Thereby, the inclination angle θ of the line segment L connecting the following P1 and P2 with respect to the light incident end surface 28 satisfies 0.01 ≦ tan θ ≦ 0.75 on the light incident side chamfering surface 40 formed. Thereby, the amount of light loss of the light source 18 can be suppressed. Further, the second chamfering step (S16) may be performed before the mirror processing step (S14), or may be performed simultaneously with the mirror processing step (S14).

When the light-incident side chamfering surface 40 is formed, a grindstone may be used as a tool for performing a grinding process or a grinding process, and a polishing wheel or a brush including a cloth, a skin, a rubber, or the like may be used in addition to the grindstone. In this case, an abrasive such as cerium oxide, aluminum oxide, cerium carbide or colloidal cerium oxide can also be used. Among them, from the viewpoint of dimensional stability, it is preferred to use a grindstone as an abrasive tool.

The glass sheet 12 is produced by the respective steps shown in the above S10 to S16. Further, the reflection points 24A, 24B, and 24C are formed by printing the glass plate 12 and then printing the light reflection surface 32.

[Features of the glass plate 12 and the planar light-emitting device 14]

As shown in Fig. 1, in order to effectively utilize the amount of light of the light source 18 as the glass plate 12 of the planar light-emitting device 14, it is required that the light incident from the light-incident end surface 28 to the inside of the glass plate 12 is not In the state of the reflection point 24A to CC, the light is prevented from leaking to the outside, and the inner surface of the glass plate 12 is reflected and totally reflected.

However, in the glass plate having the chamfered surface of the usual shape disclosed in Patent Document 3, the light incident from the chamfered surface to the inside of the glass plate is greatly curved in the advancing direction due to the refraction, so that it does not exist in the glass plate. The problem of leaking light to the outside while conducting the waveguide. It is also confirmed that such light leakage occurs frequently in the vicinity of the entrance end face. That is, in the prior glass plate, there is no effective use without depleting the amount of light of the light source.

Therefore, in the present embodiment, it is possible to provide a planar light-emitting device 14 that can effectively utilize the amount of light of the light source 18, and a glass plate 12 that can be used as a light guide plate for the planar light-emitting device 14.

Next, it demonstrates based on FIG. 4 is an enlarged plan view showing the features of the glass sheet 12, and is a cross-sectional view perpendicular to the light-emitting surface 26 and the light-reflecting surface 32 as main planes and the light-incident end surface 28 as an end surface.

Repeatedly, the glass plate 12 has a light exit surface 26 and a light reflecting surface 32, and has a light incident end surface 28 that is perpendicular to the light exit surface 26 and the light reflecting surface 32. Further, the light-emitting side chamfered surface 40 is provided adjacent to the light-emitting surface 26 and the light-incident end surface 28, and the light-incident-side chamfering surface 40 is provided adjacent to the light-reflecting surface 32 and the light-incident end surface 28.

Further, at a cross section perpendicular to the light exit surface 26 and the light incident end surface 28, a point at which the light incident side chamfered surface 40 and the light exit surface 26 intersect is referred to as a first intersection P1, and a light incident side chamfered surface is formed. When the point at which the light incident end surface 28 intersects with the light incident end surface 28 is the second intersection point P2, the inclination angle θ of the line segment L connecting the P1 and the P2 with respect to the light incident end surface 28 satisfies 0.01 ≦ tan θ ≦ 0.75. Further, since the light incident side chamfering surface 40 on the light reflecting surface 32 side has the same configuration, the description of the light incident side chamfering surface 40 on the light reflecting surface 32 side is omitted.

The inventors of the present invention have made an effort to study the shape of the light-incident side chamfering surface 40 which can effectively utilize the light amount of the light source 18 as the glass plate 12, and have found that the light source can be used even for the glass plate having the light-incident side chamfering surface 40. The light loss of 18 is suppressed to the minimum of the glass plate 12.

That is, a glass plate is provided which is perpendicular to the light exit surface 26 and the light incident end surface 28 as shown in FIG. 4, and is connected to the first intersection P1 where the light side chamfered surface 40 and the light exit surface 26 intersect. The inclination angle θ of the line segment L of the second intersection P2 where the light incident side chamfered surface 40 intersects the light incident end surface 28 with respect to the light incident end surface 28 satisfies 0.01 ≦ tan θ ≦ 0.75.

Moreover, the inventors of the present invention have found a glass plate of another embodiment which can further suppress the loss of the amount of light of the light source 18.

Figure 13 is an enlarged partial cross-sectional view showing a glass plate 112 in another embodiment. As shown in FIG. 13, the glass plate 112 has a light incident side chamfered surface 140 which is connected to the light side chamfered surface 140 in a cross section perpendicular to the light exit surface 126 and the light incident end surface 128. The line segment L11 of the first intersection P11 intersecting the light exit surface 126 and the second intersection P12 where the light incident side chamfered surface 140 intersects the inclined surface 148 has an inclination angle θ ₁ with respect to the light incident end surface 128. The inclination angle θ ₁ satisfies 0.01 ≦ tan θ ₁ ≦ 0.75.

Further, the glass plate 112 has an inclined surface 148 which is perpendicular to the light exit surface 126 and the light incident end surface 128, and the inclined surface 148 is connected to the third intersection P12 and the third surface where the inclined surface 148 intersects the light incident end surface 128. The inclination angle θ ₂ of the line segment L12 of the intersection P13 with respect to the light incident end surface 128 is smaller than the inclination angle θ ₁ and satisfies 0 < tan θ ₂ ≦ 0.4. That is, the inclination angle θ ₁ satisfies tan θ ₁ > tan θ ₂ .

In the glass plate 12 shown in FIG. 4 and the glass plate 112 shown in FIG. 13, the light source 18 from the light-incident side chamfered surface (40, 140) of this shape is incident on the glass plate 12 or the glass plate. The inner surface of the light exit surface (26, 126) of 112 and the inner surface of the light reflecting surface (32, 132) are totally totally reflected, and are advanced along the inside of the glass plate 12 or the glass plate 112. Accordingly, according to the embodiments, the glass plate 12 or the glass plate 112 and the planar light-emitting device 14 which can effectively utilize the amount of light of the light source 18 can be provided.

In addition, in FIG. 4, the light-incident side chamfering surface 40 which has a linear cross-sectional shape is shown, but the cross-sectional shape of the light-injecting side chamfering surface 40 is also circular arc shape. In this case, as shown in the enlarged cross-sectional view of the main part of the glass plate 12 of FIG. 8, with respect to the light exit surface 26 and the light incident end The vertical cross section of the surface 28 is defined as a point P3 on a circular arc which is equally divided into two arcs forming the arc-inclination surface 40, and the tangent T of the arc on the point P3 is opposite to the light incident end surface. The inclination angle θ of 28 satisfies 0.01 ≦ tan θ ≦ 0.75. That is, in the glass plate 112 shown in FIG. 13, the cross-sectional shape of the light-incident side chamfered surface 140 and the inclined surface 148 is also circular.

In the glass plate 12 shown in FIG. 4, when the tan θ is 0.01 or more, the chamfered portion is not excessively too small, and the initial goal of removing the edge of the glass sheet 12 to improve the strength can be achieved. When the tan θ is 0.75 or less, the light leakage from the glass plate 12 is reduced, and when the glass plate 12 is used as a light guide plate, the brightness is increased. In order to further reduce light leakage, the above θ preferably satisfies 0.01 ≦ tan θ ≦ 0.5, more preferably satisfies 0.01 ≦ tan θ ≦ 0.4, further preferably satisfies 0.01 ≦ tan θ ≦ 0.3, and particularly preferably satisfies 0.01 ≦ tan θ ≦ 0.2. In particular, when the above θ satisfies 0.01 ≦ tan θ ≦ 0.2, light leakage can be completely eliminated.

In the glass plate 112 shown in FIG. 13, when the tan θ ₁ is 0.01 or more, the chamfered portion does not become extremely small, and the first objective of removing the edge of the glass plate 112 to improve the strength can be achieved. When the above tan θ ₁ is 0.75 or less, the light leakage from the glass plate 112 is reduced, and when the glass plate 112 is used as a light guide plate, the brightness is increased. In order to further reduce light leakage, the above θ ₁ preferably satisfies 0.01 ≦ tan θ ₁ ≦ 0.5, more preferably satisfies 0.01 ≦ tan θ ₁ ≦ 0.4, and further preferably satisfies 0.01 ≦ tan θ ₁ ≦ 0.3, and particularly preferably satisfies 0.01 ≦ tan θ ₁ ≦0.2. In particular, when the above θ ₁ satisfies 0.01 ≦ tan θ ₁ ≦ 0.2, light leakage can be completely eliminated.

The chamfered shape in general, the above-described θ becomes 45 °, tanθ tan [theta] ₁ becomes 1, or, when in this case, since the light incident on the side chamfered surface (40, 140) is incident to the glass sheet 12 or a glass plate 112, The direction of the light before entering will be greatly bent by refraction. The light which is largely bent in the advancing direction does not leak along the glass plate 12 or the glass plate 112, and is easily leaked from the glass plate 12 or the glass plate 112. The inventors of the present invention have found that by setting tan θ or tan θ ₁ to 0.75 or less, the influence of refraction can be suppressed, and as a result, light leakage can be reduced.

Moreover, the glass plate 12 or the glass plate 112 of the embodiment is preferably a light-incident side chamfered surface (40, 140) The surface roughness Ra is 0.1 μm or less. Thereby, the light from the light source 18 is not scattered or diffusely reflected on the light incident side chamfering surface (40, 140) and is incident on the inside of the glass plate 12 or the glass plate 112. Thereby, the light of the light source 18 can be utilized more effectively.

Further, the glass plate 12 or the glass plate 112 of the embodiment preferably has an average internal transmittance of 90% or more at a wavelength of 400 to 700 nm at a length of 50 mm, and thus has a glass plate 12 or a glass plate 112 having a high internal transmittance. Thereby, the light of the light source 18 can be further effectively utilized.

[Examples]

In order to find out the range of the above tan θ, the inventors of the present invention simulated using a ray tracing software (Light Tools: manufactured by Cybernet Systems) and using a number of rays of 1 million. In the sample used in the simulation, the light source 18 is disposed at a distance of 0.5 mm from the light-incident end surface 28 in a manner opposed to a rectangular glass plate 12 having a size of 700 mm × 700 mm, and the reflection is arranged so as to surround the light source 18. 30. Further, the glass plate 12 has a chamfered surface 40, and the inclination angle and the size thereof are variously changed as described below. The light source 18 is configured to include a plurality of point light sources connected in parallel, emit light in a wavelength range of 400 nm to 700 nm, and have a light distribution characteristic of a Lambertian distribution. The reflector 30 has a Gaussian reflection characteristic of σ = 15° and a diffuse reflectance of 98%. The glass plate 12 is provided with the light exit surface 26 and the light reflecting surface 32, and the light reflecting surface 32 does not form a reflection point. Further, the reflection sheet 20 is disposed at a distance of 0.1 mm from the light reflection surface 32 so as to face the glass plate 12. The reflection sheet has a Gaussian reflection characteristic of σ=15° and a diffuse reflectance of 98%.

In order to more accurately estimate the amount of non-waveguide light and the amount of waveguide light, it is assumed that there is no absorption of glass in the sample. The refractive index of the glass is 1.532 at a wavelength of 435.8 nm, 1.527 at a wavelength of 486.1 nm, 1.523 at a wavelength of 546.1 nm, 1.521 at a wavelength of 587.6 nm, and 1.519 at a wavelength of 656.3 nm. Use the appropriate value of the Sellmeyer coefficient to interpolate the values.

Figure 9 is a solid diamond in a glass plate 12 having a thickness t of 1.7 mm (Solid Rhombus: ◆), solid square (Solid Square: ■), solid triangle (Solid Triangle: ▲) symbol is a plot of the ratio of multiple non-waveguide light to tan θ (%). Fig. 10 is a table showing the conditions and simulation results for calculating the ratio (%) of the non-waveguide light of Fig. 9 by simulation.

Further, Fig. 11 is a glass plate 12 having a thickness t of 2.5 mm, and is marked with a solid rhombus (Solid rhombus: ◆), a solid square (Solid Square: ■), and a solid triangle (Solid Triangle: ▲). A plot of a ratio (%) of a plurality of non-waveguide lights to a tan θ value. Fig. 12 is a table showing the conditions and simulation results for calculating the ratio (%) of the non-waveguide light of Fig. 11 by simulation.

The term “a” refers to a case where the point at which the first extension line La extended along the light exit surface 26 as shown in FIG. 4 intersects with the second extension line Lb extending along the light incident end surface 28 is the third intersection point P3. The length from the first intersection P1 to the third intersection P3. Further, b is the length from the second intersection P2 to the third intersection P3. That is, the present embodiment is characterized in that a/b = tan θ and a/b value is 0.75 or less.

Further, the non-waveguide light described in FIGS. 10 and 12 means the total amount of light leaking from the light exit surface 26 in the glass sheet 12, and the non-waveguide light (%) indicates that the amount of light of the light source 18 is set to The ratio of the amount of light leakage at the above detection points at 100%.

In addition, the waveguide light means light that is reflected by the entire surface of the glass plate 12, and the waveguide light (%) indicates that the light source 18 has a light amount of 100%. The ratio of the amount of light detected by the light end face 38 away from the position of 690 mm. Furthermore, the cumulative value of the waveguide light (%) and the non-guided light (%) does not become 100% because the light is absorbed by the reflector 30 or the reflection sheet 20.

<simulation result>

According to Fig. 9 and Fig. 11, the solid rhombus (◆) symbol is used to draw b to 0.1 mm and a to 0.01 mm, 0.02 mm, 0.03 mm, 0.05 mm, 0.07 mm, and 0.1 mm. Non-waveguide light (%). Similarly, with solid The square (Solid Square: ■) symbol draws non-waveguide light (%) when b is set to 0.2 mm and a is set to 0.01 mm, 0.03 mm, 0.05 mm, 0.1 mm, 0.15 mm, and 0.2 mm, respectively. Similarly, a non-waveguide is used to set b to 0.3 mm and a to 0.01 mm, 0.03 mm, 0.05 mm, 0.1 mm, 0.2 mm, and 0.3 mm with solid triangles (▲). Light(%).

Here, when the non-waveguide light (%) is lowered as compared with when tan θ is 1, the evaluation is based on the case where the glass plate 12 having a thickness t of 1.7 mm is as shown in FIGS. 9 and 10 . When the b value is 0.75 or less (tan θ ≦ 0.75), the evaluation criteria can be satisfied. Further, when the a/b value is 0.2 or less (tan θ ≦ 0.2), the non-waveguide light (%) becomes zero. Further, it has been found that in order to satisfy the evaluation criteria, a is preferably 0.01 to 0.05 mm, and b is 0.1 to 0.3 mm.

Further, as in the case of the glass plate 12 having a thickness t of 2.5 mm as shown in Figs. 11 and 12, if the a/b value is 0.75 or less (tan θ ≦ 0.75), the evaluation criteria can be satisfied. Further, when the a/b value is 0.2 or less (tan θ ≦ 0.2), the non-waveguide light (%) becomes zero. Thus, it is known that the preferred range of tan θ does not depend on the thickness of the glass sheet 12. Further, it has been found that in order to satisfy the evaluation criteria, a is preferably 0.01 to 0.05 mm, and b is 0.1 to 0.3 mm.

Therefore, according to the glass plate 12 having an a/b value of 0.75 or less (tan θ ≦ 0.75), the amount of light of the light source 18 can be effectively utilized irrespective of the thickness of the glass plate 12. Therefore, according to the planar light-emitting device 14 including the glass plate 12 of the embodiment, the thickness of the electronic device can be reduced and the power consumption can be reduced.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific embodiments described above, and various changes and modifications may be made within the scope of the invention as described in the appended claims.

Priority is claimed on Japanese Patent Application No. 2015-148561, filed on Jan. To this article.

12‧‧‧ glass plate

26‧‧‧Light exit surface

28‧‧‧Incoming light end face

32‧‧‧Light reflecting surface

40‧‧‧Enhanced side chamfered surface

A‧‧‧ length

B‧‧‧ Length

L‧‧‧ line segment

La‧‧‧1st extension cord

Lb‧‧‧2nd extension cord

P1‧‧‧1st intersection

P2‧‧‧2nd intersection

P3‧‧‧3rd intersection

T‧‧‧thickness

Θ‧‧‧ tilt angle

Claims (8)

A glass plate having a principal plane and an end surface perpendicular to the main plane, and having a chamfered surface adjacent to the main plane and the end surface between the main plane and the end surface, a cross section perpendicular to the main plane and the end surface, a first embodiment where the chamfered surface intersects the main plane, and a line segment of the second intersection where the chamfered surface intersects the end surface has an inclination angle θ of 0.01 with respect to the end surface. ≦tanθ≦0.75. A glass plate having a principal plane and an end surface perpendicular to the main plane, and a chamfered surface adjacent to the main plane between the main plane and the end surface, and a chamfered surface and the a slanted surface between the end faces, a cross section perpendicular to the main plane and the end surface, a first intersection connecting the chamfered surface and the main plane, and a cross between the chamfered surface and the inclined surface The line segment of the two intersections includes the chamfered surface so as to be inclined at an inclination angle θ ₁ with respect to the end surface, and the inclination angle θ ₁ satisfies 0.01 ≦ tan θ ₁ ≦ 0.75, and the second intersection, the inclined surface, and the end surface are connected The inclination angle θ ₂ of the line segment crossing the third intersection point with respect to the end surface is smaller than the inclination angle θ ₁ and satisfies 0 < tan θ ₂ ≦ 0.4. A glass sheet according to claim 1 or 2, wherein said inclination angle θ satisfies 0.01 ≦ tan θ ≦ 0.2. The glass plate according to any one of claims 1 to 3, wherein the end surface has a surface roughness Ra of 0.1 μm or less. The glass sheet according to any one of claims 1 to 4, wherein the glass sheet has an average internal transmittance of 90% or more at a wavelength of from 400 to 700 nm at a length of 50 mm. The glass plate according to any one of claims 1 to 5, wherein the glass plate has a thickness of 0.7 to 3.0 mm, and the first extension line extending along the main plane intersects the second extension line extending along the end surface The point is the third intersection, the length from the first intersection to the third intersection is 0.01 to 0.05 mm, and the length from the second intersection to the third intersection is 0.1 to 0.3 mm. The glass sheet according to any one of claims 1 to 6, wherein the value of the surface roughness Ra of the end surface is smaller than the value of the surface roughness Ra of the chamfered surface. The glass plate according to any one of claims 1 to 7, wherein the chamfered surface has a surface roughness Ra of 0.8 μm or less.