JP2018145016A - Glass plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass plate capable of effectively utilizing the amount of light of a light source. A glass plate (12) of the present embodiment has a light emitting surface (26) and a light reflecting surface (32), and has an incident surface (28) perpendicular to the light emitting surface (26) and the light reflecting surface (32). Further, an incoming light side surface 40 is provided adjacent to the light emitting surface 26 and the light entering end surface 28, and an incoming light side surface 40 is provided adjacent to the light reflecting surface 32 and the light entering end surface 28. ing. When the point where the entrance side surface 40 and the light emission surface 26 intersect is the first intersection P1, and the point where the entrance side surface 40 and the light exit end surface 28 intersect is the second intersection P2. , The inclination angle θ of the line segment L connecting P1 and P2 with respect to the incident end surface 28 satisfies 0.01 ≦ tan θ ≦ 0.75. [Selection diagram] Fig. 4

Description

  The present invention relates to a glass plate.

  A liquid crystal display device typified by a liquid crystal television, digital signage, and the like includes a planar light emitting device that constitutes a backlight, and a liquid crystal panel that is disposed to face the light emitting surface of the planar light emitting device. The planar light emitting device includes a direct type and an edge light type, and an edge light type that can reduce the size of the light source is often used. The edge light type planar light emitting device includes a light source, a light guide plate, a reflection sheet, various optical sheets (such as a diffusion sheet and a brightness enhancement sheet), and the like. Patent Documents 1 and 2 disclose that a glass plate having high internal transmittance, high rigidity, and excellent heat resistance is used as a light guide plate of a planar light emitting device.

  The glass plate is higher in rigidity and heat resistance than the acrylic plate used as the light guide plate, but if the glass plate is left in a cut state, the edges are sharp and dangerous, and the strength of the glass plate May lead to decline. For this reason, the chamfering process which chamfers an edge is performed. Thereby, the edge of a glass plate is equipped with the chamfering surface inclined with respect to the main plane and end surface of a glass plate. As disclosed in Patent Document 3, the shape of the chamfered surface is generally a shape in which a tilt angle with respect to the main plane and the end surface is 45 ° in a cross section perpendicular to the main plane and the end surface of the glass plate.

JP 2013-093195 A JP 2013-030279 A No. 2013/31548

  An object of this invention is to provide the glass plate which can be used as a light-guide plate for the planar light-emitting device which can use the light quantity of a light source effectively, for example.

  According to an aspect of the present invention, a glass having a main plane and an end face perpendicular to the main plane, and having a chamfered surface between the main plane and the end face and adjacent to the main plane and the end face. An end surface of a line segment connecting a first intersection where the chamfered surface and the main plane intersect with a second intersection where the chamfered surface and the end surface intersect in a cross section perpendicular to the main plane and the end surface. Provided is a glass plate having an inclination angle θ with respect to that satisfies 0.01 ≦ tan θ ≦ 0.75.

  According to the glass plate of the present invention, for example, when used as a light guide plate of a planar light emitting device, the light amount of the light source can be effectively used.

Side view of liquid crystal display device showing schematic configuration of liquid crystal display device Top view of glass plate Overall perspective view of glass plate Cross-sectional enlarged view of a glass plate (partially omitted) Process drawing of the manufacturing method of the glass plate which is embodiment Plan view of glass material on glass plate Plan view of the glass substrate from which the glass material has been cut out Expanded cross-sectional view of the main part of a glass plate with an arc-shaped cross-section of the incident side chamfer Plotted figure showing the ratio of non-guided light to tan θ in a glass plate with a thickness of 1.7 mm A table showing necessary data for calculating the ratio of non-guided light in FIG. 9 by simulation. Plotted figure showing the ratio of non-guided light to tan θ in a glass plate with a thickness of 2.5 mm A table showing necessary data for calculating the ratio of non-guided light in FIG. 11 by simulation.

  Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  In the description in the drawings, the same or corresponding members or parts are denoted by the same or corresponding reference numerals, and redundant description is omitted. Also, the drawings are not intended to show relative ratios between members or parts unless otherwise specified. Thus, specific dimensions can be determined by one skilled in the art in light of the following non-limiting embodiments.

[Liquid crystal display device 10]
FIG. 1 is a side view of the liquid crystal display device 10 showing a schematic configuration of the liquid crystal display device 10. FIG. 2 is a plan view of the glass plate 12 of the embodiment incorporated in 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 a thin electronic device such as a liquid crystal television or digital signage.

<Liquid crystal panel 16>
The liquid crystal panel 16 is configured by laminating an alignment layer, a transparent electrode, a glass substrate, and a polarizing filter so as to sandwich a liquid crystal layer disposed in the center in the thickness direction. A color filter is disposed on one side of the liquid crystal layer. The molecules of the liquid crystal layer rotate around the light distribution axis by applying a driving voltage to the transparent electrode, thereby performing a predetermined display.

<Surface emitting device 14>
As the planar light-emitting device 14, an edge light type is adopted in order to reduce the thickness. The planar light emitting device 14 includes a light source 18, a glass plate 12, a reflection sheet 20, various optical sheets 22 (such as a diffusion sheet and a brightness enhancement sheet), and reflection dots 24 </ b> A to 24 </ b> C.

  The light incident on the inside of the glass plate 12 from the light source 18 travels while being repeatedly totally reflected on the inner surface of the light emitting surface 26 and the inner surface of the light reflecting surface 32 of the glass plate 12 as indicated by arrows in FIG. . Further, the light whose traveling direction is changed by the reflective dots 24A to 24C and the reflective sheet 20 is emitted to the outside from the light emitting surface 26 of the glass plate 12 facing the liquid crystal panel 16. The light emitted to the outside is diffused by various optical sheets (including a diffusion sheet, a brightness enhancement sheet, etc., which may be single or plural), and then enters 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 facing the light incident end face 28 of the glass plate 12.

  In addition, by providing the reflector 30 on the back side of the light source 18, the incident efficiency of the light emitted radially from the light source 18 on 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 so as to face the light reflection surface 32 of the glass plate 12. In addition, the reflection sheet 20 may be disposed on the non-light-incident end surfaces 34, 36, and 38 (see FIG. 2). All of the reflection sheets 20 may be disposed with a space from the glass plate 12 or may be bonded to the glass plate 12 with an adhesive. The light reflecting surface 32 is a main plane facing the light emitting surface 26 of the glass plate 12. Further, the light incident end face 28 is an end face of the glass plate 12 facing the light source 18. The non-light incident end surfaces 34, 36, and 38 are end surfaces of the glass plate 12 excluding the light incident end surface 28.

  In addition, when arrange | positioning the reflection sheet 20 in a non-light-incidence end surface, what is necessary is just to arrange | position at the non-light-incidence end surface 38 facing the light-incidence end surface 28 among the non-light-incidence end surfaces 34,36,38. Thereby, the light incident from the light incident end face 28 travels in the direction away from the light source (toward the right direction in FIGS. 1 and 2) while being repeatedly totally reflected inside the glass plate 12, and the non-light incident end face 38. Is reflected again by the reflecting sheet 20 into the glass plate 12. Further, when the reflective sheet 20 is also disposed on the non-light-incident end surfaces 34 and 36, the light scattered inside the glass plate 12 is reflected by the reflective sheet 20 when reaching the non-light-incident end surfaces 34 and 36. It can be reflected again inside the glass plate 12. Thereby, the light quantity of the light source 18 can be used effectively.

  An acrylic resin is exemplified as the material of the resin sheet constituting the reflective sheet 20, but is not limited thereto, and for example, a polyester resin such as a PET resin, a urethane resin, and a material formed by combining them can be used. .

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

  The reflective sheet 20 may be provided with an adhesive layer and bonded to the glass plate 12. As the adhesive layer provided on the reflection sheet 20, for example, an acrylic resin, a silicone resin, a urethane resin, a synthetic rubber, or the like can be used.

  Although the thickness of the reflective sheet 20 is not specifically limited, For example, the thing of 0.01-0.50 mm can be used.

  For the various optical sheets 22, a milky white acrylic resin film or the like can be used. Since the various optical sheets 22 diffuse light emitted from the light emitting surface 26 of the glass plate 12, the back side of the liquid crystal panel 16 is irradiated with uniform light having no luminance unevenness. The various optical sheets 22 are disposed to face predetermined positions so as not to contact the glass plate 12.

<Physical properties of glass plate 12>
The glass plate 12 is made of highly transparent glass. In the embodiment, a multicomponent oxide glass is used as a glass material used as the glass plate 12.

  Specifically, as the glass plate 12, it is preferable to use glass having a length of 50 mm and an average internal transmittance of 90% or more at a wavelength of 400 to 700 nm. Thereby, attenuation of the 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 cleaving the glass plate 12 in a direction perpendicular to the main plane, and is collected from the central portion of the glass plate in a size of 50 mm in length × 50 mm in width. In sample A in which the second fractured surface has an arithmetic average roughness Ra ≦ 0.03 μm, the spectroscopic measurement is possible with a length of 50 mm in the normal direction from the first fractured surface and measurement with a length of 50 mm. Measurement is performed with a measuring device (for example, UH4150: manufactured by Hitachi High-Technologies Corporation) with the beam width of incident light narrower than the plate thickness by a slit or the like. By removing the loss due to reflection on the surface from the transmittance at the 50 mm length thus obtained, the internal transmittance at the 50 mm length can be obtained. The average internal transmittance at a wavelength of 400 to 700 nm with a length of 50 mm is preferably 92% or more, more preferably 95% or more, still more preferably 98% or more, and particularly preferably 99% or more.

  The total amount A of iron in the glass used as the glass plate 12 is preferably 100 mass ppm or less in order to satisfy the above-described average internal transmittance at a wavelength of 400 to 700 nm at a length of 50 mm, and 40 mass ppm. More preferably, it is more preferably 20 ppm by mass or less. On the other hand, the total amount A of the iron content of the glass used as the glass plate 12 is preferably 5 ppm by mass or more in order to improve the meltability of the glass during the production of the multicomponent oxide glass, It is more preferably 8 ppm by mass or more, and further preferably 10 ppm by mass or more. In addition, the total amount A of the iron content of the glass used as the glass plate 12 can be adjusted by the amount of iron added at the time of glass production.

In this specification, the total iron content A of the glass is expressed as the content of Fe ₂ O ₃ , but all the iron present in the glass exists as Fe ³⁺ (trivalent iron). I don't mean. Usually, Fe ³⁺ and Fe ²⁺ (divalent iron) are simultaneously present in the glass. Fe ²⁺ and Fe ³⁺ have absorption in the wavelength range of 400 to 700 nm, but the absorption coefficient of Fe ²⁺ (11 cm ⁻¹ Mol ⁻¹ ) is more than the absorption coefficient of Fe ³⁺ (0.96 cm ⁻¹ Mol ⁻¹ ). Is also an order of magnitude larger, so that the internal transmittance at a wavelength of 400 to 700 nm is further reduced. Therefore, it is preferable that the content of Fe ²⁺ is small in order to increase the internal transmittance at a wavelength of 400 to 700 nm.

The Fe ²⁺ content B of the glass used as the glass plate 12 is preferably 20 ppm by mass or less in order to satisfy the above-described average internal transmittance in the visible light region with the effective optical path length, and 10 ppm by mass or less. More preferably, it is more preferably 5 ppm by mass or less. On the other hand, the Fe ²⁺ content B of the glass used as the glass plate 12 is preferably 0.01 mass ppm or more, in order to improve the meltability of the glass during the production of multi-component oxide glass. 0.05 mass ppm or more is more preferable, and 0.1 mass ppm or more is further preferable.

In addition, content of Fe ^<2+> of the glass used as the glass plate 12 can be adjusted with the quantity of the oxidizing agent added at the time of glass manufacture, or a melting temperature. Specific types of oxidizers added during glass production and their addition amounts will be described later. The content A of Fe ₂ O ₃ was determined by fluorescent X-ray measurement, a content of total iron as calculated as _Fe 2 _{O 3} (mass ppm). The Fe ²⁺ content B was measured according to ASTM C169-92. The measured Fe ²⁺ content was expressed 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.

One structural example (Structural example A) of the glass used as the glass plate 12 is an oxide-based mass percentage display, and SiO ₂ is 60 to 80%, Al ₂ O ₃ is 0 to 7%, and MgO is 0 to 10%. %, 0-20% of CaO, the SrO 0 to 15%, 0 to 15% of BaO, 3 to 20% of Na ₂ O, 0% to _{K 2 O, Fe 2} O ₃ 5 to 100 mass Contains ppm.

Another structural example (Structural Example B) of the glass used as the glass plate 12 is an oxide-based mass percentage display, and SiO ₂ is 45 to 80%, Al ₂ O ₃ is more than 7% and 30% or less, 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 to 10%, 0 to 10% of ZrO ₂ and 5 to 100 mass ppm of Fe ₂ O ₃ are contained.

Yet another configuration example of the glass used as the glass plate 12 (configuration example C) is a mass percentage based on oxides, SiO ₂ 45 to 70%, the _{Al 2 O 3 10~30%, B} 2 0 to 15% for O ₃ , 5 to 30% in total for MgO, CaO, SrO and BaO, 0% to less than 3% in total for Li ₂ O, Na ₂ O and K ₂ O, Fe ₂ O ₃ 5-100 mass ppm included.

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

  The composition range of each component of the glass composition of the glass plate 12 of the present embodiment having the above components will be described below. The unit of the content of each composition is expressed in terms of mass percentage on the basis of oxide or mass ppm, and is simply expressed as “%” or “ppm”, respectively.

SiO ₂ is a main component of glass.

In order to maintain the weather resistance and devitrification characteristics of the glass, the content of SiO ₂ is preferably 60% or more, more preferably 63% or more in the configuration example A, and preferably 45% in the configuration example B. Or more, more preferably 50% or more. In the configuration example C, preferably 45%.
% Or more, more preferably 50% or more.

On the other hand, the content of SiO ₂ is easy to dissolve and the foam quality is good, and the content of divalent iron (Fe ²⁺ ) in the glass is kept low, and the optical properties are good. Therefore, in the configuration example A, preferably 80% or less, more preferably 75% or less, in the configuration example B, preferably 80% or less, more preferably 70% or less, and in the configuration example C , Preferably 70% or less, more preferably 65% or less.

Al ₂ O ₃ is an essential component that improves the weather resistance of the glass in Structural Examples B and C. In order to maintain practically necessary weather resistance in the glass of the present embodiment, the content of Al ₂ O ₃ is preferably 1% or more, more preferably 2% or more in the configuration example A. In Example B, it is preferably more than 7%, more preferably 10% or more, and in Structural Example C, it is preferably 10% or more, more preferably 13% or more.

However, in order to keep the content of divalent iron (Fe ²⁺ ) low, make the optical properties good, and make the foam quality good, the content of Al ₂ O ₃ is preferably Is 7% or less, more preferably 5% or less. In the configuration example B, preferably 30% or less, more preferably 23% or less, and in the configuration example C, preferably 30% or less, more preferably 20% or less.

B ₂ O ₃ is a component that promotes melting of the glass raw material and improves mechanical properties and weather resistance, but it does not cause inconveniences such as generation of striae due to volatilization and furnace wall erosion. In the glass A, the content of B ₂ O ₃ is preferably 5% or less, more preferably 3% or less. In the structural examples B and C, the content is preferably 15% or less, more preferably 12%. It is as follows.

Alkali metal oxides such as Li ₂ O, Na ₂ O, and K ₂ O are useful components for accelerating melting of glass raw materials and adjusting thermal expansion, viscosity, and the like.

Therefore, in the configuration example A, the content of Na ₂ O is preferably 3% or more, more preferably 8% or more. In the structural example B, the content of Na ₂ O is preferably 7% or more, and more preferably 10% or more. However, the content of Na ₂ O is preferably 20% or less in the structural examples A and B in order to maintain the clarity during melting and maintain the foam quality of the produced glass, and 15% More preferably, in the configuration example C, 3
% Or less, and more preferably 1% or less.

Further, the content of K ₂ O is preferably 10% or less, more preferably 7% or less in the structural examples A and B, and preferably 2% or less, more preferably in the structural example C. 1% or less.

In addition, Li ₂ O is an optional component, but in the structural examples A, B, and C in order to facilitate vitrification, to keep the iron content contained as impurities derived from the raw material low, and to keep the batch cost low. , Li ₂ O can be contained at 2% or less.

In addition, in the configuration examples A and B, the total content of these alkali metal oxides (Li ₂ O + Na ₂ O + K ₂ O) maintains the clarification at the time of melting, and maintains the foam quality of the produced glass. , Preferably 5% to 20%, more preferably 8% to 15%. In the configuration example C, it is preferably 0% to 2%, more preferably 0% to 1%.

  Alkaline earth metal oxides such as MgO, CaO, SrO, and BaO are useful components for accelerating melting of glass raw materials and adjusting thermal expansion, viscosity, and the like.

MgO has the effect of lowering the viscosity during glass melting and promoting the melting. Moreover, since it has the effect | action which reduces specific gravity and makes a glass plate hard to wrinkle, it can be contained in the structural examples A, B, and C. Further, in order to make the glass have a low coefficient of thermal expansion and good devitrification properties, the content of MgO is preferably 10% or less, more preferably 8% or less in the configuration example A. In Example B, it is preferably 15% or less, more preferably 12% or less, and in Structural Example C, it is preferably 10% or less, more preferably 5% or less.

  Since CaO is a component that promotes melting of the glass raw material and adjusts viscosity, thermal expansion, and the like, it can be contained in the structural examples A, B, and C. In order to obtain the above action, in the configuration example A, the content of CaO is preferably 3% or more, more preferably 5% or more. In order to improve devitrification, in the configuration example A, it is preferably 20% or less, more preferably 10% or less, and in the configuration example B, preferably 6% or less, more preferably 4% or less.

  SrO has the effect of increasing the thermal expansion coefficient and lowering the high temperature viscosity of the glass. In order to obtain such an effect, SrO can be contained in the structural examples A, B, and C. However, in order to keep the thermal expansion coefficient of the glass low, the content of SrO is preferably 15% or less in the structural examples A and C, more preferably 10% or less, and in the structural example B It is preferably 5% or less, and more preferably 3% or less.

  BaO, like SrO, has the effect of increasing the thermal expansion coefficient and lowering the high temperature viscosity of the glass. In order to obtain the above effect, BaO can be contained. However, in order to keep the thermal expansion coefficient of the glass low, it is preferably 15% or less in Configuration Examples A and C, more preferably 10% or less, and 5% or less in Configuration Example B. Of these, 3% or less is more preferable.

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

In the glass composition of the glass plate 12 of the present embodiment, ZrO ₂ is used as an optional component in order to improve the heat resistance and surface hardness of the glass, and in the structural examples A, B and C, preferably 10% or less, preferably You may make it contain 5% or less. It becomes difficult to devitrify glass by setting it as 10% or less.

In the glass composition of the glass of the glass plate 12 of this embodiment, in order to improve the meltability of the glass, 5 to 100 ppm of Fe ₂ O ₃ may be contained in the structural examples A, B, and C. In addition, the preferable range of the amount of Fe ₂ O ₃ is as described above.

The glass of the glass plate 12 of the present embodiment may contain SO ₃ as a fining agent. In this case, the SO ₃ content is preferably more than 0% and 0.5% or less in terms of mass percentage. 0.4% or less is more preferable, 0.3% or less is more preferable, and 0.25% or less is further preferable.

Moreover, the glass of the glass plate 12 of this embodiment may contain one or more of Sb ₂ O ₃ , SnO ₂ and As ₂ O ₃ as an oxidizing agent and a fining agent. In this case, the content of Sb ₂ O ₃ , SnO ₂ or As ₂ O ₃ is preferably 0 to 0.5% in terms of mass percentage. 0.2% or less is more preferable, 0.1% or less is more preferable, and it is further more preferable not to contain substantially.

However, since Sb ₂ O ₃ , SnO ₂ and As ₂ O ₃ act as an oxidizing agent for glass, they may be added within the above range depending on the purpose of adjusting the amount of Fe ^{2+ in} the glass. However, from the environmental aspect, it is preferable that As ₂ O ₃ is not substantially contained.

  Moreover, the glass of the glass plate 12 of this embodiment may contain NiO. When NiO is contained, since NiO functions also as a coloring component, the content of NiO is preferably 10 ppm or less with respect to the total amount of the glass composition described above. In particular, NiO is preferably 1.0 ppm or less, more preferably 0.5 ppm or less, from the viewpoint of not reducing the internal transmittance of the glass plate at a wavelength of 400 to 700 nm.

The glass of the glass plate 12 of this embodiment may 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 with respect to the total amount of the glass composition described above. In particular, Cr ₂ O ₃ is preferably 1.0 ppm or less, and more preferably 0.5 ppm or less, from the viewpoint of not reducing the internal transmittance of the glass plate at a wavelength of 400 to 700 nm.

The glass of the glass plate 12 of this embodiment may contain MnO ₂ . When MnO ₂ is contained, since MnO ₂ functions also as a component that absorbs visible light, the content of MnO ₂ is preferably 50 ppm or less with respect to the total amount of the glass composition described above. In particular, MnO ₂ is preferably 10 ppm or less from the viewpoint of not reducing the internal transmittance of the glass plate at a wavelength of 400 to 700 nm.

Glass of the glass plate 12 of the present embodiment may include 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 with respect to the total amount of the glass composition described above. From the viewpoint of not reducing the internal transmittance of the glass plate at a wavelength of 400 to 700 nm, the content of TiO ₂ is more preferably 500 ppm or less, and particularly preferably 100 ppm or less.

Glass of the glass plate 12 of the present embodiment may include CeO _2. CeO ₂ has the effect of reducing the redox of iron, and the ratio of the Fe ²⁺ amount to the total iron amount can be reduced. On the other hand, in order to suppress the iron redox from decreasing to less than 3%, the CeO ₂ content is preferably 1000 ppm or less with respect to the total amount of the glass composition described above. The CeO ₂ content is more preferably 500 ppm or less, further preferably 400 ppm or less, particularly preferably 300 ppm or less, and most preferably 250 ppm or less.

The glass of the glass plate 12 of this embodiment may contain at least one component selected from the group consisting of CoO, V ₂ O ₅ and CuO. When these components are contained, they also function as components that absorb visible light, and therefore the content of the components is preferably 10 ppm or less with respect to the total amount of the glass composition described above. In particular, it is preferable that these components are not substantially contained so as not to reduce the internal transmittance of the glass plate at a wavelength of 400 to 700 nm.

<Shape of glass plate 12>
FIG. 3 is an overall perspective view of the glass plate 12, and FIG. 4 is an enlarged cross-sectional view of the glass plate 12. In FIG. 4, a part of a cross section perpendicular to the main plane and the light incident end face 28 is enlarged and displayed.

  The glass plate 12 having a rectangular shape in plan view includes a light emitting surface 26, a light reflecting surface 32, a light incident end surface 28, non-light incident end surfaces 34, 36, 38, a light incident side chamfered surface 40, and a non-light incident side chamfered surface 42. have.

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

  The light emitting surface 26 is a surface facing the liquid crystal panel 16. In the embodiment, the light emitting surface 26 has a rectangular shape in plan view, but the shape of the light emitting surface 26 is not limited to this. Further, the size of the light exit surface 26 is determined according to the liquid crystal panel 16 and is not particularly limited. However, when the glass plate 12 is used as the light guide plate, for example, 500 mm × 500 mm. The above size is suitable. Since the glass plate 12 has high rigidity, the effect is exhibited as the size increases.

  The light reflecting surface 32 is a surface facing 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 those of the light emitting surface 26.

  Note that the light reflecting surface 32 is not necessarily parallel to the light emitting surface 26, and may be configured to have a step or an inclination. Further, the size of the light reflecting surface 32 may be different from that of the light emitting surface 26.

  The light reflection surface 32 includes a plurality of circular reflection dots 24A, 24B, and 24C. The arrangement of the reflective dots may be a grid as shown in FIG. 2, may be any other pattern, or may be random, but the luminance of light emitted from the light exit surface 26 The distribution is adjusted as appropriate so that the distribution is uniform. The reflective dots 24A to 24C are formed by printing a resin in a dot shape or the like, and may contain scattering particles or bubbles. The brightness of the light incident from the light incident end face 28 is strong, but the brightness gradually decreases as it proceeds while being repeatedly reflected inside the glass plate 12.

For this reason, in the embodiment, the size of the reflective dots 24A, 24B, and 24C is varied from the light incident end surface 28 toward the non-light incident end surface 38. Specifically, the diameter (L _A ) of the reflection dot 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 dot 24B and the reflection are further directed toward the light traveling direction. the diameter of the dot 24C _{(L C)} are set so that the larger _{(L a <L B <L} C). The diameter of the reflective dot is appropriately adjusted so that the luminance distribution of the light emitted from the light emitting surface 26 is uniform.

  In this way, by changing the size of the reflective dots 24A, 24B, and 24C toward the traveling direction of the light inside the glass plate 12, the luminance of the outgoing light emitted from the light outgoing surface 26 can be made uniform, and the luminance Generation of unevenness can be suppressed. The same effect can be obtained by changing the number density of the reflective dots 24A, 24B, and 24C in the direction of the light traveling inside the glass plate 12 instead of the size of the reflective dots 24A, 24B, and 24C. Can be obtained. The same effect can be obtained by forming grooves on the light reflecting surface 32 that reflect incident light instead of the reflecting dots 24A, 24B, and 24C.

  Since the light from the light source 18 is not incident on the non-light-incident end surfaces 34, 36, and 38 of the glass plate 12, it is not necessary to process the surface as accurately as the light incident end surface 28, and the surface roughness Ra is 0.8 μm or less. However, the surface roughness Ra of the non-light-incident end surfaces 34, 36, 38 is preferably 0.4 μm or less, and more preferably 0. 1 μm or less. In addition, in this specification, when it describes as surface roughness Ra, it shall point out the arithmetic mean roughness (centerline average roughness) by JISB0601-JISB0031.

  The light incident end face 28 is mirror-finished when the glass plate 12 is manufactured. The surface roughness Ra of the light incident end face 28 is 0.1 μm or less, preferably less than 0.03 μm, more preferably 0 in order to make light from the light source 18 effectively enter the inside of the glass plate 12. 0.001 μm or less, particularly preferably 0.0005 μm or less. Therefore, the light incident efficiency of the light incident on the inside of the glass plate 12 from the light source 18 is enhanced. The surface roughness Ra of the non-light-incident end faces 34, 36, 38 may be equal to or larger than the surface roughness Ra of the light-incident end face 28 from the viewpoint of improving production efficiency.

<Light incident side chamfered surface 40 (chamfered surface)>
A light incident side chamfering surface 40 is provided between the light emitting 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, a light incident side chamfering surface 40 is provided between the light emitting surface 26 and the light incident end surface 28 adjacent to the light emitting surface 26 and the light incident end surface 28. Similarly, a light incident side chamfer 40 is provided between the light reflecting surface 32 and the light incident end surface 28 adjacent to the light reflecting surface 32 and the light incident end surface 28.

  In the embodiment, an example in which a light incident side surface 40 is provided between the light emitting surface 26 and the light incident end surface 28 and between the light reflecting surface 32 and the light incident end surface 28 is illustrated. It is good also as a structure provided with the light-incidence side chamfering surface 40 only in one. Further, the surface roughness Ra of the light incident side chamfered surface 40 is preferably 0.8 μm or less, more preferably 0.4 μm or less, and further preferably 0.1 μm or less. By setting the surface roughness Ra of the light incident side chamfered surface 40 to 0.8 μm or less, it is possible to suppress the occurrence of uneven brightness of the light emitted from the glass plate 12. If it says from another viewpoint, the incident light can be efficiently taken in into the glass plate 12 by making surface roughness Ra of the light-incidence side chamfering surface 40 into 0.8 micrometer or less. Moreover, the amount of cullet generation can be suppressed by setting the surface roughness Ra of the light incident side chamfered surface 40 to 0.4 μm or less. On the other hand, the lower limit of the surface roughness Ra of the light incident side chamfered surface 40 is not limited, and the smaller the Ra is, the more it is possible to suppress the occurrence of luminance unevenness of the glass plate 12, but the chamfering step (S12) described later accordingly. It takes time. From the viewpoint of improving the production efficiency, 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. Here, the surface roughness Ra of each of the non-light-incident side chamfers 42 of the non-light-incident end surfaces 34, 36, and 38 is preferably 0.8 μm or less. In this way, when the reflective tape is provided on the non-light-incident end surface and / or the non-light-incident side chamfer, light that has once escaped from the non-light-incident end surface and / or the non-light-incident side chamfer is reflected by the reflective tape. It is reflected and can be efficiently re-entered from the non-light-incident side chamfer.

  The shape, action, and effect of the light incident side chamfered surface 40 will be described in the column of the characteristics of the glass plate 12 described later.

  In the planar light emitting device 14 that is required to be thin as in the embodiment, it is necessary to reduce the thickness of the glass plate 12. For this reason, the thickness of the glass plate 12 which concerns on embodiment is 0.7-3.0 mm. When the thickness of the glass plate 12 is 3.0 mm or less, the planar light emitting device 14 can be thinned, and when it is 0.7 mm or more, sufficient rigidity can be obtained. In addition, although the thickness of the glass plate 12 is not limited to this value, even if it is this thickness, compared with the planar light-emitting device which has an acrylic light guide plate with a thickness of 4 mm or more, The planar light emitting device 14 having sufficient strength can be provided.

[Production Method of Glass Plate 12]
5, 6, and 7 are diagrams for explaining a method of manufacturing the glass plate 12. FIG. 5 is a process diagram showing a method for manufacturing the glass plate 12. FIG. 6 is a plan view of the glass material 44, and FIG. 7 is a plan view of the glass substrate 46.

  In order to manufacture the glass plate 12, first, the glass material 44 of FIG. 6 is 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 with a length of 50 mm is 90% or more. The glass material 44 has a shape larger than the predetermined shape of the glass plate 12.

<Cutting process>
First, the cutting process shown by step (S) 10 in FIG. 5 is performed on the glass material 44. In the cutting step (S10), cutting is performed at each position (one position on the light incident end face side and three positions on the non-light incident end face side) indicated by broken lines in FIG. The cutting process does not necessarily have to be performed on the three positions on the non-light-incident end face side, and only one position on the non-light-incident end face side facing the position on the one light-incident end face side is provided. Cutting may be performed.

  By carrying out the cutting process, the glass substrate 46 in FIG. 7 is cut out from the glass material 44 in FIG. 6. In the embodiment, since the glass plate 12 has a rectangular shape in plan view, the cutting process was performed on one light incident end face side position and three non-light incident end face side positions. The cutting position is appropriately selected according to the shape of the glass plate 12.

  In addition, as a cutting method of the glass material 44, a scribe cleaving method, a laser cutting method, etc. can be implemented, for example. From the viewpoint of productivity, the scribe cleaving method is preferable. In addition, when the light incident side chamfering surface 40 has an arc shape, a laser cutting method in which the cut surface can have an arc shape is preferable.

<First chamfering process>
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), non-light-incident side chamfering is performed between the light exit 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 using a grinding device. Each surface 42 is formed.

  In addition, between the light emitting surface 26 and the non-light-incident end surface 34, between the light reflecting surface 32 and the non-light-entering end surface 34, between the light emitting surface 26 and the non-light-incident end surface 36, and with the light reflecting surface 32, When the non-light-incident side chamfered surface 42 is formed at all or any one of the positions with respect to the non-light-incident end surface 36, chamfering is performed in the first chamfering step (S12).

  In the first chamfering step (S12), it is preferable from the viewpoint of productivity to chamfer between the light emitting surface 26 and the light incident end surface 28 or between the light reflecting surface 32 and the light incident end surface 28. . In that case, the surface roughness Ra of the light incident side chamfered surface 40 ′ (not shown) obtained is larger than the surface roughness Ra of the light incident side chamfered surface 40 obtained in the second chamfering step described later. From the viewpoint of sex. As a result, a light incident side chamfered surface 40 'is formed. At this stage, an inclination angle θ of a line segment L connecting P1 and P2 described later with respect to the light incident end surface 28 is not particularly limited.

  In the first chamfering step (S12), a grinding process or a polishing process is also performed on the non-light-incident end faces 34, 36, and 38. The timing of performing the grinding process or the polishing process on the non-light-incident end surfaces 34, 36, 38 may be performed before or after forming the non-light-incident side chamfered surface 42, or may be performed simultaneously. In addition, about the non-light-incidence end surfaces 34 and 36, you may use the surface which cut-processed as the non-light-incidence end surfaces 34 and 36 as it is.

  In the first chamfering step (S12), it is preferable from the viewpoint of productivity that the light incident end face 28 is also subjected to grinding treatment or polishing treatment. The timing of performing the grinding process or the polishing process on the light incident end face 28 may be before or after forming the light incident side chamfered surface 42, or may be performed simultaneously.

  The first chamfering step (S12) can be performed at the same time as the mirror surface processing step (S14) and the second chamfering step (S16), which will be described later, or at the subsequent stage, but it is preferable to perform at the preceding stage. Thereby, since processing according to the shape of the glass plate 12 can be performed at a relatively fast rate in the first chamfering step (S12), productivity is improved.

<Mirror finishing process>
When the first chamfering step (S12) is completed, a mirror finishing step (S14) is then performed. In the mirror surface processing step (S14), the mirror surface processing is performed on the light incident end surface 28 of the glass substrate 46 shown in FIG. 7, thereby forming the light incident end surface 28 having a surface roughness Ra of 0.1 μm or less. .

<Second chamfering process>
When the light incident end face 28 is formed on the glass substrate 46 in the mirror finishing process (S14), the second chamfering process (S16) is subsequently performed, and between the light emitting face 26 and the light incident end face 28, and A grinding process or a polishing process is performed between the light reflecting surface 32 and the light incident end surface 28. Thereby, the light incident side chamfering surface 40 is formed. In the light incident side chamfered surface 40 thus formed, the inclination angle θ of a line segment L connecting P1 and P2 described later with respect to the light incident end surface 28 satisfies 0.01 ≦ tan θ ≦ 0.75. Thereby, the light quantity loss of the light source 18 can be suppressed. In addition, a 2nd chamfering process (S16) can also be implemented before a mirror surface process (S14), and can also be implemented simultaneously with a mirror surface process (S14).

  When forming the light incident side chamfered surface 40, a grindstone may be used as a tool for performing the grinding process or the polishing process, and in addition to the grindstone, a buff or brush made of cloth, leather, rubber or the like is used. In this case, an abrasive such as cerium oxide, alumina, carborundum, colloidal silica may be used. Among these, from the viewpoint of dimensional stability, it is preferable to use a grindstone as the polishing tool.

  The glass plate 12 is manufactured through the steps shown in S10 to S16. The reflective dots 24A, 24B, and 24C are formed on the light reflecting surface 32 by a method such as printing after the glass plate 12 is manufactured.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments described above, and various modifications are possible within the scope of the gist of the present invention described in the claims. It can be modified and changed.

[Characteristics of the glass plate 12 and the planar light-emitting device 14]
As shown in FIG. 1, in order to effectively use the light amount of the light source 18 as the glass plate 12 of the planar light emitting device 14, the light incident on the inside of the glass plate 12 from the light incident end face 28 is reflected by the reflection dots 24 </ b> A to 24 </ b> C. In the state where it is not applied, it is required to proceed while repeatedly totally reflecting on the inner surface of the glass plate 12 without leaking light to the outside.

  However, in the glass plate having a chamfered surface having a normal shape disclosed in Patent Document 3, since the light incident on the inside of the glass plate from the chamfered surface is greatly bent by refraction, the inside of the glass plate There is a problem that light leaks outside without being guided. It was also confirmed that such a light leakage phenomenon occurred frequently in the vicinity of the light incident end face. In other words, there is no conventional glass plate that can be used effectively without losing the light amount of the light source.

  Therefore, in the present embodiment, a planar light emitting device 14 that can effectively use the light amount of the light source 18 and a glass plate 12 that can be used as the light guide plate in the planar light emitting device 14 are provided.

  Next, a description will be given based on FIG. FIG. 4 is an explanatory view showing the characteristics of the glass plate 12 in an enlarged manner, and is a cross-sectional view perpendicular to the light emitting surface 26 and the light reflecting surface 32 that are main surfaces and the light incident end surface 28 that is an end surface. It is.

  As will be described repeatedly, the glass plate 12 has a light emitting surface 26 and a light reflecting surface 32, and a light incident end surface 28 perpendicular to the light emitting surface 26 and the light reflecting surface 32. A light incident side chamfer 40 is provided adjacent to the light exit surface 26 and the light incident end surface 28, and a light incident side chamfer 40 is provided adjacent to the light reflecting surface 32 and the light incident end surface 28. Yes.

  Then, in a cross section perpendicular to the light exit surface 26 and the light entrance end surface 28, a point where the light entrance side chamfer 40 and the light exit surface 26 intersect is defined as a first intersection P1, and the light entrance side chamfer 40 and the light entrance chamfer 40 are incident. When the point where the light end face 28 intersects is defined as the second intersection P2, the inclination angle θ of the line segment L connecting P1 and P2 with respect to the light incident end face 28 satisfies 0.01 ≦ tan θ ≦ 0.75. ing. Since the light incident side chamfered surface 40 on the light reflecting surface 32 side has the same configuration, the description of the light incident side chamfered surface 40 on the light reflecting surface 32 side is omitted.

  The inventor of the present application intensively studied the shape of the light incident side chamfering surface 40 that can effectively use the light amount of the light source 18 as the glass plate 12, and even if it is a glass plate provided with the light incident side chamfering surface 40, the light source 18. The glass plate 12 which can suppress the light quantity loss of this to the minimum was discovered.

  That is, as shown in FIG. 4, in the cross section perpendicular to the light exit surface 26 and the light entrance end surface 28, the first intersection P1 where the light entrance side chamfer 40 and the light exit surface 26 intersect with each other, and the light entrance side chamfer Provided is a glass plate in which an inclination angle θ with respect to the light incident end face 28 of a line segment L connecting 40 and the second intersection P2 where the light incident end face 28 intersects satisfies 0.01 ≦ tan θ ≦ 0.75.

  The light of the light source 18 that has entered from the light incident side chamfering surface 40 having such a shape is repeatedly totally reflected by the inner surface of the light emitting surface 26 and the inner surface of the light reflecting surface 32 of the glass plate 12, while passing through the inside of the glass plate 12. proceed. Thereby, according to embodiment, the glass plate 12 and the planar light-emitting device 14 which can use effectively the light quantity of the light source 18 can be provided.

  In FIG. 4, the light incident side chamfered surface 40 having a linear cross section is shown. However, the cross section of the light incident side chamfered surface 40 includes an arc shape. In that case, as shown in the enlarged sectional view of the main part of the glass plate 12 in FIG. 8, the arc forming the light incident side chamfered surface 40 is equally divided into two in the cross section perpendicular to the light emitting surface 26 and the light incident end surface 28. A point on the arc to be made is a point P3, and an inclination angle θ of the arc tangent T to the light incident end face 28 at the point P3 satisfies 0.01 ≦ tan θ ≦ 0.75.

  If the tan θ is 0.01 or more, the chamfered portion is not excessively reduced, and the possibility that the original purpose of removing the edge of the glass plate 12 and improving the strength cannot be achieved is reduced. When the tan θ is 0.75 or less, light leakage from the glass plate 12 is reduced, and luminance is increased when the glass plate 12 is used as a light guide plate. 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, and 0.01 ≦ tan θ ≦ 0. .3, more preferably 0.01 ≦ tan θ ≦ 0.2. In particular, when the θ satisfies 0.01 ≦ tan θ ≦ 0.2, light leakage can be completely eliminated.

  In a general chamfered shape, θ is 45 ° and tan θ is 1. In this case, when light enters the glass plate 12 from the incident side chamfered surface 40, the light traveling direction is greatly bent by refraction. It will be. The light whose traveling direction is greatly bent is easily leaked from the glass plate 12 without being guided through the glass plate 12. The inventor of the present application has found that by setting tan θ to be 0.75 or less, the influence of refraction can be suppressed, and as a result, light leakage can be reduced.

  Moreover, it is preferable that the glass plate 12 of embodiment has surface roughness Ra of the light-incidence chamfering surface 40 of 0.1 micrometer or less. Thereby, the light from the light source 18 enters the inside of the glass plate 12 without being scattered or irregularly reflected by the incident light chamfered surface 40. Thereby, the light of the light source 18 can be used more effectively.

  Furthermore, the glass plate 12 of the embodiment is preferably a glass plate 12 having a high internal transmittance because it has a length of 50 mm and an average internal transmittance at a wavelength of 400 to 700 nm of 90% or more. Thereby, the light of the light source 18 can be used more effectively.

〔Example〕
In finding the range of tan θ, the inventor of the present application performed a simulation with 1 million rays using ray tracing software (Light Tools: manufactured by Cybernet System). In the model used in this simulation, the light source 18 is arranged at a distance of 0.5 mm from the light incident end face 28 so as to face the rectangular glass plate 12 having a size of 700 mm × 700 mm so as to surround the light source 18. A reflector 30 is arranged. Further, the glass plate 12 has a chamfered surface 40, and the simulation was performed by changing the inclination angle and size of the glass plate 12 as described later. The light source 18 is composed of a plurality of point light sources arranged in parallel, emits light in a wavelength range of 400 nm to 700 nm, and has a Lambertian light distribution characteristic. The reflector 30 has a Gaussian reflection characteristic of σ = 15 °, and the diffuse reflectance is 98%. The glass plate 12 has a light emitting surface 26 and a light reflecting surface 32, and no reflecting dots are formed on the light reflecting surface 32. Further, the reflective sheet 20 was disposed at a distance of 0.1 mm from the light reflecting surface 32 so as to face the glass plate 12. The reflective sheet had a Gaussian reflection characteristic of σ = 15 ° and the diffuse reflectance was 98%.

  In order to more accurately estimate the amount of non-guided light and the amount of guided light, it was assumed in this model that there was no glass absorption. 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. And these values interpolated by appropriate Selmeier coefficients were used.

  FIG. 9 shows that the ratio (%) of non-guided light to a plurality of tan θ in a glass plate 12 having a thickness t of 1.7 mm is a solid rhombus (solid), a solid square (Solid Square: ■). ), A diagram plotted with solid triangles (▲). FIG. 10 is a table showing conditions for calculating the ratio (%) of non-guided light in FIG. 9 and results of the simulation.

  FIG. 11 shows the ratio (%) of non-guided light to a plurality of tan θ values in a glass plate 12 having a thickness t of 2.5 mm, a solid rhombus (solid), a solid square (Solid). It is the figure plotted by the mark of Square (square) and solid triangle (Solid Triangle :). FIG. 12 is a table showing conditions for calculating the ratio (%) of non-guided light in FIG. 11 and results of the simulation.

  As shown in FIG. 4, a is a third intersection where the first extension line La extended along the light exit surface 26 and the second extension line Lb extended along the light incident end surface 28 intersect. This is the length from the first intersection P1 to the third intersection P3 in the case of P3. Further, b is the length from the second intersection P2 to the third intersection P3. That is, a feature of the present embodiment is that a / b = tan θ and the 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 plate 12, and the non-waveguide light (%) means the light amount of the light source 18. The ratio of the amount of light leakage at the detection point when 100% is shown.

  The guided light means light that travels while being totally reflected inside the glass plate 12, and the guided light (%) means that the light quantity of the light source 18 is 100%. The ratio of the amount of light detected at a position spaced 690 mm toward the light incident end surface 38 is shown. The reason why the total value of the guided light (%) and the non-guided light (%) does not become 100% is that the light is absorbed by the reflector 30 or the reflection sheet 20.

<simulation result>
According to FIGS. 9 and 11, non-waveguide light when b is set to 0.1 mm and a is set to 0.01 mm, 0.02 mm, 0.03 mm, 0.05 mm, 0.07 mm, and 0.1 mm. (%) Is plotted with solid rhombus (♦) marks. Similarly, non-guided light (%) is solid 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. Are plotted with solid squares (■). Similarly, non-guided light (%) is solid when b is set to 0.3 mm and a is set to 0.01 mm, 0.03 mm, 0.05 mm, 0.1 mm, 0.2 mm, and 0.3 mm. Each triangle is plotted with a solid triangle (▲) mark.

  Here, assuming that the non-guided light (%) is reduced compared to when tan θ is 1, the glass plate 12 having a thickness t of 1.7 mm as shown in FIGS. 9 and 10. In this case, if the a / b value is 0.75 or less (tan θ ≦ 0.75), the evaluation criteria can be satisfied. Further, it was found that if the a / b value is 0.2 or less (tan θ ≦ 0.2), the non-guided light (%) becomes zero. In order to satisfy the evaluation criteria, it was also found that a is preferably 0.01 to 0.05 mm and b is preferably 0.1 to 0.3 mm.

  Further, as shown in FIGS. 11 and 12, even in the case of a glass plate 12 having a thickness t of 2.5 mm, if the a / b value is 0.75 or less (tan θ ≦ 0.75), the evaluation criteria are satisfied. I was able to. Further, it was found that if the a / b value is 0.2 or less (tan θ ≦ 0.2), the non-guided light (%) becomes zero. Thus, it was found that the preferable range of tan θ does not depend on the thickness of the glass plate 12. In order to satisfy the evaluation criteria, it was also found that a is preferably 0.01 to 0.05 mm and b is preferably 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 light amount of the light source 18 can be effectively used regardless of the thickness of the glass plate 12. Therefore, according to the planar light-emitting device 14 provided with the glass plate 12 of an Example, power consumption can be reduced, achieving thickness reduction of an electronic device.

  DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device, 12 ... Glass plate, 14 ... Planar light-emitting device, 16 ... Liquid crystal panel, 18 ... Light source, 20 ... Reflection sheet, 22 ... Various optical sheets, 24A, 24B, 24C ... Reflection dot, 26 ... Light Emission surface, 28 ... light incident end surface, 30 ... reflector, 32 ... light reflecting surface, 34, 36, 38 ... non-light incident end surface, 40 ... light incident side chamfering surface, 42 ... non-light incident side chamfering surface, 44 ... glass Material, 46 ... Glass substrate

Claims (7)

A glass plate having a main plane and an end face perpendicular to the main plane, and having a chamfered surface adjacent to the main plane and the end face between the main plane and the end face. ,
In a cross section perpendicular to the main plane and the end surface, a line segment connecting a first intersection where the chamfered surface and the main plane intersect with a second intersection where the chamfered surface and the end surface intersect A glass plate having an inclination angle θ with respect to the end surface that satisfies 0.01 ≦ tan θ ≦ 0.75.   The glass plate according to claim 1, wherein the inclination angle θ satisfies 0.01 ≦ tan θ ≦ 0.2.   The glass plate of Claim 1 or 2 whose surface roughness Ra of the said end surface is 0.1 micrometer or less.   The said glass plate is a glass plate of any one of Claim 1 to 3 whose average internal transmittance in wavelength 400-700nm is 90% or more by 50 mm length. The glass plate has a thickness of 0.7 to 3.0 mm,
A point where a first extension line extending along the main plane and a second extension line extending along the end face intersect with each other as a third intersection.
The length from the first intersection to the third intersection is 0.01 to 0.05 mm,
The glass plate of any one of Claim 1 to 4 whose length from the said 2nd intersection to the said 3rd intersection is 0.1-0.3 mm.   The value of surface roughness Ra of the said end surface is smaller than the value of surface roughness Ra of the said chamfering surface, The glass plate of any one of Claim 1 to 5 characterized by the above-mentioned.   The glass plate of any one of Claim 1 to 6 whose surface roughness Ra of the said chamfering surface is 0.8 micrometer or less.

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