CN206338646U

CN206338646U - Glass component and glass

Info

Publication number: CN206338646U
Application number: CN201690000186.3U
Authority: CN
Inventors: 宫本尚明; 伊藤正文; 石川和也
Original assignee: Asahi Glass Co Ltd
Current assignee: AGC Inc
Priority date: 2015-02-12
Filing date: 2016-02-08
Publication date: 2017-07-18
Anticipated expiration: 2026-02-08

Abstract

The utility model is related to the glass that glass component and the glass component are used, and the glass component has glass (5) and reflector plate (6), wherein, the glass has：First face (51)；Second face (52) relative with first face；It is arranged at least one first end face (53) between first face and second face；And it is arranged at least one second end faces (54 between first face and second face and different with the first end face, 56), the effective optical path length of the glass is 5~200cm, the average internal transmissivity of visible domain in the effective optical path length of the glass is more than 80%, the surface roughness Ra of the second end face is less than 0.8 μm, and the reflector plate is configured with the second end face.Glass component of the present utility model improves adherence of the reflector plate to non-light inputting end face.

Description

Glass member and glass

Technical Field

The utility model relates to a glass component and glass.

Background

In recent years, liquid crystal display devices are provided in portable information terminals such as liquid crystal televisions, tablet terminals, and smartphones. The liquid crystal display device includes a planar light emitting device as a backlight and a liquid crystal panel disposed on a light emitting surface side of the planar light emitting device.

The planar light emitting device includes a direct type and an edge lighting type, but an edge lighting type capable of reducing the size 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, a diffusion sheet, and the like.

Light from the light source is incident into the light guide plate from a light-incident end face formed on a side face of the light guide plate. The light guide plate has a plurality of reflection dots formed on a light reflection surface opposite to a light emitting surface facing the liquid crystal panel. The reflector sheet is disposed so as to face the light reflection surface, and the diffusion sheet is disposed so as to face the light emission surface.

Light incident from the light source to the light guide plate is reflected by the reflection point and the reflection sheet, travels, and is emitted from the light emitting surface. The light emitted from the light emitting surface is diffused by the diffusion sheet and then enters the liquid crystal panel.

As a material of the light guide plate, glass having high transmittance and excellent heat resistance can be used (see patent documents 1 and 2).

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 2013-093195

Patent document 2: japanese patent application laid-open No. 2013-030279

SUMMERY OF THE UTILITY MODEL

Problem to be solved by utility model

The above-described reflection sheet is also disposed on a side surface (non-light-incident end surface) other than the light-incident end surface of the glass used as the light guide plate. Thus, light from the light source is incident from the light incident end face, and then is prevented from being emitted from the non-light incident end face, so that light is efficiently emitted from the light emitting face.

An exemplary object of one aspect of the present invention is to provide a glass member having improved adhesiveness of a reflecting sheet to a non-incident light end surface, and glass used for the glass member.

Means for solving the problems

In order to achieve the above object, the present invention provides a glass member having glass and a reflecting sheet, wherein,

the glass has:

a first side;

a second face opposite the first face;

at least one first end face disposed between the first face and the second face; and

at least one second end face disposed between the first face and the second face and different from the first end face,

the effective optical path length of the glass is 5-200 cm,

the average internal transmittance of the visible light region over the effective optical path length of the glass is 80% or more,

the second end face has a surface roughness Ra of 0.8 [ mu ] m or less,

the reflecting sheet is disposed on the second end surface.

Additionally, the present invention also provides a glass member, the glass having:

a first side;

a second face opposite the first face;

wherein,

the effective optical path length of the glass is 5-200 cm,

the second end face has a surface roughness Ra of 0.8 [ mu ] m or less.

Effect of the utility model

According to an aspect of the present invention, there is provided a glass member having improved adhesiveness to a non-incident light end surface of a reflection sheet, which can prevent a decrease in luminance when the glass member is used as a light guide plate.

Drawings

Fig. 1 is a schematic configuration diagram showing a liquid crystal display device using a glass member of one embodiment as a light guide plate.

Fig. 2 is a view showing a light reflecting surface of the light guide plate.

Fig. 3 is a perspective view of the light guide plate.

Fig. 4 is a diagram for explaining a chamfer formed on the light guide plate.

Fig. 5 is a process diagram of a method for manufacturing a glass member according to an embodiment.

Fig. 6 is a diagram illustrating a cutting structure of a method for manufacturing a glass member according to an embodiment.

Fig. 7 is a diagram for explaining the mirror-surface processing step.

FIGS. 8(a) to 8(b) are graphs for explaining the relationship between the surface roughness Ra and the difference in transmittance of the samples of examples 1 to 6.

FIG. 9 is a graph for explaining the relationship between the surface roughness Ra and the adhesive force P of the samples of examples 7 to 14.

FIG. 10 is a graph for explaining the relationship between the surface roughness Ra and the adhesive force P of the samples of examples 15 to 22.

Detailed Description

The following description will be made with reference to the accompanying drawings, which illustrate non-limiting exemplary embodiments of the present invention.

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

The embodiments described below are not intended to limit the present invention but to exemplify the present invention, and all the features or combinations thereof described in the embodiments are not necessarily essential features or combinations thereof of the present invention.

Fig. 1 shows a liquid crystal display device 1 using a glass member according to an embodiment of the present invention. The liquid crystal display device 1 is mounted on an electronic apparatus such as a portable information terminal, which is reduced in size and thickness.

The liquid crystal display device 1 includes a liquid crystal panel 2 and a planar light emitting device 3.

The liquid crystal panel 2 is formed by laminating an alignment layer, a transparent electrode, a glass substrate, and a polarization filter so as to sandwich a liquid crystal layer disposed at the center. Further, a color filter is disposed on one surface of the liquid crystal layer. By applying a driving voltage to the transparent electrode, molecules of the liquid crystal layer are rotated around the light distribution axis, thereby performing predetermined display.

The planar light emitting device 3 is of an edge illumination type for achieving miniaturization and thinning. The planar light emitting device 3 includes a light source 4, a light guide plate 5, a reflection sheet 6, a diffusion sheet 7, and reflection points 10A to 10C.

The light incident from the light source 4 to the light guide plate 5 is reflected by the reflection points 10A to 10C and the reflection sheet 6, travels, and is emitted from the light emitting surface 51 of the light guide plate 5 facing the liquid crystal panel 2. The light emitted from the light emitting surface 51 is diffused by the diffusion sheet 7 and then enters the liquid crystal panel 2.

The Light source 4 is not particularly limited, but a hot cathode tube, a cold cathode tube, or an LED (Light emitting diode) may be used. The light source 4 is disposed so as to face the light entrance end surface 53 of the light guide plate 5.

In addition, in order to improve the incidence efficiency of the light emitted radially from the light source 4 to the light guide plate 5, a reflector 8 is provided on the rear surface side of the light source 4.

The reflective sheet 6 is configured by coating a surface of a resin sheet such as acrylic resin with a light reflective member. The reflection sheet 6 is disposed on the light reflection surface 52 and the non-light-incident end surfaces 54 to 56 of the light guide plate 5. The light reflection surface 52 is a surface facing the light exit surface 51 of the light guide plate 5. The non-light-incident end surfaces 54 to 56 are surfaces other than the light-incident end surface 53 among the end surfaces of the light guide plate 5.

The glass member has a light guide plate 5 and a reflection sheet 6, and the reflection sheet 6 is disposed at least on a non-light-incident end face 56 opposed to the light-incident end face 53. Thus, the light entering from the light entrance end surface 53 is reflected inside the light guide plate 5, travels in the traveling direction of the light (in the right direction in fig. 1 and 2), and when reaching the non-light entrance end surface 56, can be reflected again inside the light guide plate 5 by the reflection sheet 6. The reflection sheet 6 is also preferably disposed on the non-light-incident end surfaces 54 and 55. Thus, when the light scattered inside the light guide plate 5 reaches the non-light-incident end surfaces 54 and 55, the light can be reflected again inside the light guide plate 5 by the reflection sheet 6.

The material of the resin sheet constituting the reflection sheet 6 is not limited to acrylic resin, and for example, polyester resin such as PET resin, urethane resin, and a material obtained by combining these resins can be used.

As the light reflection member constituting the reflection sheet 6, for example, a metal deposition film or the like can be used.

The reflection sheet 6 disposed on the non-light-incident end surfaces 54 to 56 is provided with an adhesive. As the adhesive provided on the reflection sheet 6, for example, acrylic resin, silicone resin, urethane resin, synthetic rubber, or the like can be used. The reflection sheet 6 is disposed on the non-light-incident end surfaces 54 to 56 via an adhesive.

The thickness of the reflection sheet 6 is not particularly limited, but for example, a thickness of 0.01 to 0.50mm may be used.

The diffusion sheet 7 may be formed of a milky-white acrylic resin film. The diffusion sheet 7 diffuses the light emitted from the light emitting surface 51 of the light guide plate 5, and thus can irradiate the back surface side of the liquid crystal panel 2 with uniform light without brightness unevenness. The reflection sheet 6 and the diffusion sheet 7 are fixed to predetermined positions of the light guide plate 5 by, for example, adhesion.

Next, the light guide plate 5 will be explained.

The light guide plate 5 is made of glass having high transparency. In the present embodiment, a multicomponent oxide glass is used as a material of the glass used for the light guide plate 5.

Specifically, as the light guide plate 5, glass having an effective optical path length of 5 to 200cm and an average internal transmittance of 80% or more in a visible light range (wavelength of 380 to 800nm) over the effective optical path length is used. The average internal transmittance of the glass in the visible light range is preferably 82% or more, more preferably 85% or more, and still more preferably 90% or more in the effective optical path length. The effective optical path length of glass is a distance from a light incident end surface where light enters to a non-light incident end surface on the opposite side when used as a light guide plate, and corresponds to a length in the horizontal direction in the case of the light guide plate 5 shown in fig. 1. Furthermore, the average internal transmittance T of the glass in the visible region_aveThe calculation can be performed by the evaluation method described later.

The Y value of the tristimulus value of XYZ colorimetric system according to JIS Z8701 (attached books) on the effective optical path length of the glass used as the light guide plate 5 is preferably 90% or more. The Y value is obtained by Y ═ Σ (S (λ) × Y (λ)). Here, S (λ) is the transmittance of each wavelength, and y (λ) is the weighting coefficient of each wavelength. Therefore, Σ (S (λ) × y (λ)) is a value obtained by summing up values obtained by multiplying the transmittance by the weighting coefficients of the respective wavelengths. It should be noted that y (λ) corresponds to the M cone (G cone/green) in the retinal cells of the eye, and also responds most to light having a wavelength of 535 nm. The Y value is more preferably 91% or more, further preferably 92% or more, and particularly preferably 93% or more in the effective optical path length.

(measurement of average internal transmittance in the visible region of glass)

Illustrating the internal transmission T of the glass in the visible region_inAnd average internal transmittance T_aveThe method of (4).

First, a sample A having a dimension of × mm in length and 50mm in width is selected by cutting the glass plate from the substantially central portion of the glass plate to be a target in a direction perpendicular to the first main surface of the glass plate, and then it is confirmed that the arithmetic average roughness Ra of the first and second cut surfaces of the sample A facing each other is 0.03 [ mu ] m or less, and if the arithmetic average roughness Ra is larger than 0.03 [ mu ] m, the first and second cut surfaces are polished with free abrasive grains of colloidal silica or cerium oxide, and then, in the sample A, the transmittance T in the range of 400nm to 800nm in wavelength at a length of 50mm in the normal direction of the first cut surface is measured with respect to the first cut surface_A. At a transmittance of T_AIn the measurement of (2), a spectroscopic measuring apparatus (e.g., UH 4150: manufactured by Hitachi high and New technology Co., Ltd.) capable of measuring a length of 50mm is used, and the beam width of incident light is narrowed to be smaller than the plate thickness by a slit or the like.

Then, the refractive indices of the sample A at the respective wavelengths of g-line (435.8nm), F-line (486.1nm), e-line (546.1nm), d-line (587.6nm) and C-line (656.3nm) were measured at room temperature by a precision refractometer using a V-block method. The coefficients B1, B2, B3, C1, C2, and C3 of the dispersion formula (the following formula (1)) of Sellmeier were determined by the least squares method so as to match these values, thereby obtaining the refractive index nA of sample a:

n_A＝[1+{B₁λ²/(λ²-C₁)}+{B₂λ²/(λ²-C₂)}+{B₃λ²/(λ²-C₃)}]^0.5(1)

in formula (1), λ is a wavelength.

Reflectivity R of the first and the second cut surfaces of sample A_AThe following theoretical formula (2)) is used to obtain:

R_A＝(1-n_A)²/(1+n_A)²(2)

next, using the following formula (3), the transmittance T from the sample A over a length of 50mm_AThe influence of reflection was excluded, and the internal transmittance T of the sample A was obtained over a length of 50mm from the first cut surface in the normal direction_in：

T_in＝[-(1-R_A)²+{(1-R_A)⁴+4T_A ²R_A ²}^_.05]/(2T_AR_A ²) (3)

The internal transmittance T obtained at each wavelength_inThe average internal transmittance T of the glass plate was calculated by averaging in the measurement wavelength region_ave。

The total amount a of the iron content of the glass used as the light guide plate 5 is preferably 150ppm or less, more preferably 80ppm or less, and still more preferably 50ppm or less, from the viewpoint of satisfying the above-described average internal transmittance in the visible light range and Y value in the effective optical path length. On the other hand, the total amount a of the iron content of the glass used as the light guide plate 5 is preferably 5ppm or more, more preferably 10ppm or more, and further preferably 20ppm or more, from the viewpoint of improving the meltability of the glass in the production of the multicomponent oxide glass. The total amount a of the iron content of the glass used as the light guide plate 5 can be adjusted by the amount of iron added at the time of glass production.

In the present specification, the total amount a of the iron content of the glass is expressed as Fe₂O₃But not all of the iron present in the glass as Fe³⁺(iron of valence 3). Usually, Fe is present in the glass at the same time³⁺And Fe²⁺(iron of valence 2). Fe²⁺And Fe³⁺Although there is absorption in the visible region, Fe²⁺Absorption coefficient (11 cm)^-1Mol^-1) Specific to Fe³⁺Absorption coefficient of (0.96 cm)^-1Mol^-1) Larger by 1 bit, and therefore, the internal transmittance in the visible light range is further lowered. Therefore, Fe is preferable in terms of improving the internal transmittance in the visible light range²⁺The content of (A) is small.

The glass used as the light guide plate 5 is made of Fe²⁺The content of (A) satisfies the conditions described later, and can suppress absorption of light at a wavelength of 600nm to 780nm, and can be effectively used even when the effective optical path length changes depending on the size of the display as in the edge lighting type.

The effective optical path length is set to L (cm), Fe²⁺Is B (ppm, converted to Fe)₂O₃The value of (1) is preferably 2.5 (cm. ppm) or more and L × B or less and 3000 (cm. ppm) or less, and L × B<2.5(cm ppm), Fe used as glass of light guide plate 5 for planar light emitting device with effective optical path length of 25-200 cm²⁺The content B of (B) is 0.05 to 0.1ppm, which makes mass production at low cost difficult, and L × B>3000 (cm. ppm) Fe used as glass for the light guide plate 5²⁺The content of (A) increases, so that the absorption of light having a wavelength of 600 to 780nm increases, the internal transmittance in the visible region decreases, and the above-mentioned average internal transmittance in the visible region and Y value may not be satisfied in the effective optical path length, and further, the glass used as the light guide plate 5 more preferably satisfies the relationship of 10 (cm. ppm). ltoreq.L × B.ltoreq.2400 (cm. ppm)Further preferably, the relationship of 25 (cm. ppm). ltoreq.L × B.ltoreq.1850 (cm. ppm) is satisfied.

Fe used as the glass of the light guide plate 5 in terms of satisfying the above-mentioned average internal transmittance and Y value in the visible light range in the effective optical path length²⁺The content B of (B) is preferably 30ppm or less, more preferably 20ppm or less, and still more preferably 10ppm or less. On the other hand, Fe is used as glass of the light guide plate 5 in order to improve the meltability of the glass in the production of multicomponent oxide glass²⁺The content B of (B) is preferably 0.02ppm or more, more preferably 0.05ppm or more, and still more preferably 0.1ppm or more.

Fe used as glass of the light guide plate 5²⁺The content of (b) can be adjusted by the amount of the oxidizing agent added at the time of glass production. Specific types of the oxidizing agent to be added in the glass production and the amount of the oxidizing agent to be added are described later. Fe₂O₃The content A is determined by fluorescent X-ray measurement and is converted into Fe₂O₃The total iron content (mass ppm) of (C). Fe²⁺Content B of (B) is determined in accordance with ASTM C169-92. The measured Fe²⁺Is converted into Fe₂O₃And (6) marking.

The multicomponent oxide glass used as the light guide plate 5 preferably has a low content of components that are absorbed in the visible light range, from the viewpoint of satisfying the above-described average internal transmittance and Y value in the visible light range in the effective optical path length. As a component having absorption in the visible region, for example, MnO is present₂、TiO₂、NiO、CoO、V₂O₅CuO and Cr₂O₃. The above-mentioned component (selected from the group consisting of MnO) is used as the glass of the light guide plate 5 in terms of satisfying the above-mentioned average internal transmittance and Y value in the visible light region in the effective optical path length₂、TiO₂、NiO、CoO、V₂O₅CuO and Cr₂O₃At least 1 of the components) is preferably 0.1% or less (1000 pp) in terms of mass percentage on an oxide basism is less than or equal to). More preferably 0.08% or less (800ppm or less), and still more preferably 0.05% or less (500ppm or less).

Specific examples of the composition of the glass used as the light guide plate 5 are as follows. However, the composition of the glass used as the light guide plate 5 is not limited thereto.

The composition of the glass other than iron used as one constituent example (constituent example a) of the glass for the light guide plate 5 contains SiO in terms of mass percentage on an oxide basis₂：60～80％，Al₂O₃：0～7％，MgO：0～10％，CaO：4～20％，Na₂O：7～20％，K₂O：0～10％。

The composition of the glass other than iron used as another constitutional example (constitutional example B) of the glass for the light guide plate 5 contains SiO in terms of mass percentage on an oxide basis₂：45～80％，Al₂O₃: more than 7% and not more than 30%, B₂O₃：0～15％，MgO：0～15％，CaO：0～6％，Na₂O：7～20％，K₂O：0～10％，ZrO₂：0～10％。

In still another example of the glass used as the light guide plate 5 (example C), the glass composition other than iron contained SiO in percentage by mass on an oxide basis₂：45～70％，Al₂O₃：10～30％，B₂O₃: 0 to 15%, at least 1 selected from the group consisting of MgO, CaO, SrO and BaO: 5 to 30% of a material selected from the group consisting of Li₂O、Na₂O and K₂At least 1 of the group consisting of O: more than 0% and less than 7%.

However, the glass used as the light guide plate 5 is not limited thereto.

As shown in fig. 2 to 5, the light guide plate 5 includes a light exit surface 51 (first surface), a light reflection surface 52 (second surface), a light entrance end surface 53 (first end surface), non-light entrance end surfaces 54 to 56 (second end surface), a light entrance-side chamfered surface 57 (first chamfered surface), and a non-light entrance-side chamfered surface 58 (second chamfered surface), in addition to fig. 1.

The light exit surface 51 is a surface facing the liquid crystal panel 2. In the present embodiment, the light emitting surface 51 has a rectangular shape in a plan view (a state where the light emitting surface 51 is viewed from above). However, the shape of the light exit surface 51 is not limited thereto.

The size of the light emitting surface 51 is determined according to the liquid crystal panel 2, and is not particularly limited. In the present embodiment, the size of the light output surface 51 is set to, for example, 1200mm × 700 mm.

The light reflection surface 52 is a surface opposite to the light exit surface 51. The light reflecting surface 52 is formed parallel to the light emitting surface 51. The light reflection surface 52 is configured to have the same shape and size as the light emission surface 51.

However, the light reflection surface 52 is not necessarily parallel to the light exit surface 51, and may be provided with a step or a slope. The light reflection surface 52 may have a different size from the light emission surface 51.

As shown in fig. 2, the light reflection surface 52 has reflection points 10A to 10C. The reflective dots 10A to 10C are formed by printing white ink in dots. The light entering from the light entrance end surface 53 has high brightness, and is reflected by the light guide plate 5 and travels, thereby decreasing the brightness.

Therefore, in the present embodiment, the sizes of the reflection points 10A to 10C are made different from each other in the light entrance end surface 53 toward the light traveling direction (toward the right in fig. 1 and 2). Specifically, the diameter (L) of the reflection point 10A in the region near the light entrance end face 53_A) Set to be small, the diameter (L) of the reflection point 10B is reflected from the point as it goes toward the traveling direction of light_B) Radius (L) of diameter of reflection point 10C_C) Set to be large (L)_A<L_B<L_C)。

By changing the size of each of the reflection dots 10A in the light traveling direction in the light guide plate 5 in this way, the luminance of the outgoing light emitted from the light exit surface 51 can be made uniform, and the occurrence of luminance unevenness can be suppressed. Note that, by changing the number density of the reflective dots 10A in the light traveling direction in the light guide plate 5 instead of the size of each reflective dot 10A, the same effect can be obtained. Further, by forming a groove for reflecting incident light on the light reflecting surface 52 instead of the reflection point 10A, the same effect can be obtained.

In the present embodiment, 4 end faces are formed between the light exit surface 51 and the light reflection surface 52. Of the 4 end surfaces, the light entrance end surface 53 as a first end surface is a surface on which light enters from the light source 4. The non-light-incident end surfaces 54 to 56 as the second end surfaces are surfaces on which light is not incident from the light source 4.

Since the non-light-incident end surfaces 54 to 56 do not receive light from the light source 4, the surfaces thereof do not need to be processed as accurately as the light-incident end surface 53. The surface roughness Ra of the non-incident end faces 54-56 is less than 0.8 μm. The reason why the surface roughness Ra of the non-incident end surfaces 54 to 56 is 0.8 μm or less is as follows. In the following description, the term "surface roughness Ra" refers to an arithmetic average roughness (center line average roughness) according to JIS B0601 to JIS B0031.

As shown in FIG. 1, the reflection sheet 6 is adhered to the non-incident end faces 54 to 56. In this case, if the surface roughness Ra of the non-light-incident end surfaces 54 to 56 is in a rough state exceeding 0.8 μm, the reflection sheet 6 cannot be properly adhered to the non-light-incident end surfaces 54 to 56. On the other hand, if the surface roughness Ra of the non-light-incident end surfaces 54 to 56 is 0.8 μm or less, the adhesiveness of the reflection sheet 6 to the non-light-incident end surfaces 54 to 56 becomes good. Thus, the reliability of the planar light-emitting device 3 can be improved by preventing the reflection sheet 6 from peeling off. The surface roughness Ra of the non-light incident end faces 54 to 56 is preferably 0.4 μm or less, more preferably 0.2 μm or less, still more preferably 0.1 μm or less, and particularly preferably 0.04 μm or less.

In the present embodiment, the non-incident end surfaces 54 to 56 are not ground or polished. Therefore, the surface roughness Ra of the non-light incident end surfaces 54 to 56 is set to be larger than the surface roughness Ra of the light incident end surface 53, and the surface roughness Ra of the non-light incident end surfaces 54 to 56 is preferably 0.01 μm or more, and more preferably 0.03 μm or more. Thus, the non-light-incident end surfaces 54 to 56 are easily processed or do not require processing, as compared with the light-incident end surface 53, and productivity is improved. However, the non-light-incident end surfaces 54 to 56 may be ground or polished, and the surface roughness Ra of the non-light-incident end surfaces 54 to 56 may be the same as the surface roughness Ra of the light-incident end surface 53. That is, the surface roughness Ra of the non-light-incident end surfaces 54 to 56 is preferably equal to or greater than the surface roughness Ra of the light-incident end surface 53, and the surface roughness Ra of the non-light-incident end surfaces 54 to 56 is more preferably greater than the surface roughness Ra of the light-incident end surface 53.

Further, as shown in fig. 4, when the width dimension of the non-light-incident end surfaces 54 to 56 (i.e., the dimension in the plate thickness direction of the portion of the surface provided between the first surface and the second surface excluding the non-light-incident-side chamfered surface 58 described later) is L (mm), the average value L in the longitudinal direction (hereinafter simply referred to as the longitudinal direction) of the chamfered surface of the width dimension L is L (mm)_avePreferably 0.25 to 9.8 mm. L is_aveMore preferably 0.50 to 9.8 mm. If L is_aveWhen the thickness is 9.8mm or less, the width Y of the non-light-entrance-side chamfered surface 58 can be sufficiently ensured. If L is_aveWhen the thickness is 0.25mm or more, an error of L described later can be reduced.

The width L of the non-incident end faces 54 to 56 is substantially varied in the longitudinal direction due to processing unevenness in cutting or chamfering. The average value of the width L of the non-light-incident end surfaces 54-56 in the length direction is L_ave(mm) in the longitudinal direction of L relative to L_aveIs preferably L_aveWithin 50%. That is, the maximum value in the longitudinal direction of L is set to L_max(mm), minimum value is L_min(mm), L is preferably satisfied_max≤1.5×L_aveAnd L is_min≥0.5×L_ave. The error is more preferably within 40%, still more preferably within 30%, and particularly preferably within 20%. This reduces the error in the width dimension L of the non-light-incident end surfaces 54 to 56 in the longitudinal direction, and thus reduces the possibility of light being reflected by the light guide plate 5 toward the reflection sheet 6The brightness unevenness occurred.

As described above, although the reflection sheet 6 is disposed on the non-light-incident end surfaces 54 to 56, voids due to adhesion failure are generated at the interfaces between the non-light-incident end surfaces 54 to 56 and the reflection sheet 6. The ratio of the area occupied by voids per unit area at the interface between the non-light-incident end surface and the reflective sheet (hereinafter simply referred to as the area void ratio) can be reduced by appropriately selecting the surface roughness Ra and the shape of the non-light-incident end surfaces 54 to 56, the adhesive included in the reflective sheet 6, and the like. The area void ratio of the interfaces between the non-light-incident end surfaces 54 to 56 and the reflection sheet 6 is preferably 40% or less, more preferably 30% or less, and still more preferably 20% or less. Since the area void ratio is 40% or less, it is possible to suppress a decrease in luminance due to voids when light is reflected by the light guide plate 5 toward the reflection sheet 6.

The area void ratio can be calculated by the following method. First, the peel adhesion P (N/10mm) of the reflector sheet to the non-incident end face at the interface between the non-incident end face and the reflector sheet, at which the area void ratio is to be calculated, is measured. The peel adhesion force P (N/10mm) can be measured by the peel adhesion force test defined in JIS Z0237. Then, the peel adhesion force P of the reflecting sheet to the end face of the glass having the same glass composition and shape as those of the non-incident end face and having a surface roughness Ra of 0.0050 μm or less was measured in the same manner as the end face of the glass₀(N/10 mm). Here, when the area void ratio of the end face having a surface roughness Ra of 0.0050 μm or less is 0%, the area void ratio V (%) at the interface between the non-light-incident end face and the reflection sheet can be calculated by the following formula 1.

V＝100×(1-P/P₀) (formula 1)

The light entrance end surface 53 is preferably mirror-finished when glass as the light guide plate 5 is manufactured. Specifically, the arithmetic average roughness (center line average roughness) Ra of the surface of the light entrance end face 53 is preferably 0.03 μm or less. This improves the light entrance efficiency of light entering the light guide plate 5 from the light source 4. The width W (see fig. 4) of the light entrance end surface 53 is set to a width required from the liquid crystal display device 1 on which the planar light-emitting device 3 is mounted. The surface roughness Ra of the light entrance end face 53 is preferably 0.01 μm or less, and more preferably 0.005 μm or less.

In the present embodiment, the light entrance-side chamfered surface 57 is formed between the light exit surface 51 and the light entrance end surface 53 and between the light reflection surface 52 and the light entrance end surface 53.

In the present embodiment, the light entrance-side chamfered surface 57 is formed between the light exit surface 51 and the light entrance end surface 53 and between the light reflection surface 52 and the light entrance end surface 53, but the light entrance-side chamfered surface 57 may be formed only in any one of the two.

In the planar light-emitting device 3 which is required to be small and thin as in the present embodiment, the thickness of the light guide plate 5 is also preferably small. Therefore, the thickness t of the light guide plate 5 of the present embodiment is preferably 10mm or less. However, in the case where the light guide plate 5 has a corner portion without providing the light entrance-side chamfered surface 57, the corner portion may be damaged by contact with another structure when the light guide plate 5 is assembled to the planar light emitting device 3, and the strength of the light guide plate 5 may be reduced. Therefore, the thickness t of the light guide plate 5 of the present embodiment is preferably 0.5mm or more, and the light entrance-side chamfered surface 57 is formed on the upper edge and the lower edge of the light entrance end surface 53.

In order to increase the light entrance efficiency of the light from the light source 4 into the light guide plate 5, the area of the light entrance end surface 53 needs to be increased. Therefore, since the light entrance-side chamfered surface 57 is preferably small, in the present embodiment, the light entrance-side chamfered surface 57 is chamfered.

Here, as shown in fig. 4, when the width dimension of the light entrance-side chamfered surface 57 (chamfered surface) is X (mm), the average value X in the longitudinal direction (hereinafter simply referred to as the longitudinal direction) of the chamfered surface of the width dimension X is X (mm)_avePreferably 0.01mm to 0.5mm, more preferably 0.05mm to 0.5mm, and particularly preferably 0.1mm to 0.5 mm. If X_aveWhen the thickness is 0.5mm or less, the width W of the light entrance end surface 53 can be increased. If X_aveWhen the thickness is 0.1mm or more, the error of X described later can be reduced. If X_aveIf the thickness is 0.01mm or more, damage from the chamfered surface can be suppressed, and the handleability can be improved.

The width X of the light entrance-side chamfered surface 57 actually causes an error in the longitudinal direction due to processing irregularities during chamfering. The average value in the longitudinal direction of the width dimension X of the light incident side chamfered surface 57 is X_aveIn the case of (mm), the error in the longitudinal direction of X is preferably X_aveWithin 50%. That is, X preferably satisfies 0.5X_ave≤X≤1.5X_ave. The error is more preferably within 40%, still more preferably within 30%, and particularly preferably within 20%. This reduces the error between the width X of the light entrance-side chamfered surface 57 and the width W of the light entrance end surface 53 in the longitudinal direction, and thus can reduce the luminance unevenness occurring in the light guide plate 5.

The light entrance-side chamfered surface 57 preferably has a surface roughness Ra of 0.4 μm or less. By setting the surface roughness Ra of the light entrance-side chamfered surface 57 to 0.4 μm or less, the amount of cullet generated can be suppressed, and the occurrence of luminance unevenness of the light guide plate 5 can be reduced. Since the amount of cullet generated increases as the width X of the light entrance-side chamfered surface 57 increases, the surface roughness Ra of the light entrance-side chamfered surface 57 is more preferably 0.3 μm or less, still more preferably 0.1 μm or less, and particularly preferably 0.03 μm or less.

In the present embodiment, as shown in fig. 3, the non-light-entrance-side chamfered surface 58 is formed between the light exit surface 51 and the non-light-entrance end surface 54, between the light reflection surface 52 and the non-light-entrance end surface 54, between the light exit surface 51 and the non-light-entrance end surface 55, between the light reflection surface 52 and the non-light-entrance end surface 55, between the light exit surface 51 and the non-light-entrance end surface 56, and between the light reflection surface 52 and the non-light-entrance end surface 56. However, the non-light-entrance-side chamfered surface 58 is not necessarily formed on all of the above, and the non-light-entrance-side chamfered surface 58 may be selectively formed.

Here, as shown in fig. 4, when the width of the non-light-incident-side chamfered surface 58 is Y (mm), the average value Y in the longitudinal direction of the width Y is_avePreferably 0.1 to 0.6 (mm). If Y is_aveWhen the width is 0.6mm or less, the width L of the non-incident end surfaces 54 to 56 can be increased. If Y is_aveWhen the thickness is 0.1mm or more, the error of Y described later can be reduced.

The width dimension Y of the non-light-incident-side chamfered surface 58 causes an error in the longitudinal direction due to processing irregularities during chamfering. The average value in the length direction of Y is Y_aveIn the case of (mm), the error in the longitudinal direction of Y is preferably Y_aveWithin 50%. That is, Y preferably satisfies 0.5Y_ave≤Y≤1.5Y_ave. The error is more preferably within 40%, still more preferably within 30%, and particularly preferably within 20%. This reduces errors in the width dimension L in the longitudinal direction of the non-light-incident end surfaces 54 to 56 on which incident light is reflected, and thus can reduce brightness unevenness occurring in the light guide plate 5.

From the viewpoint of improving productivity, the surface roughness Ra of the non-light-entrance-side chamfered surface 58 is larger than the surface roughness Ra of the light-entrance-side chamfered surface 57, and is preferably 0.03 μm or more, more preferably 0.1 μm or more, further preferably 0.3 μm or more, and particularly preferably 0.4 μm or more. The surface roughness Ra of the non-light-incident-side chamfered surface 58 is preferably 1.0 μm or less. Further, since the surface roughness Ra of the non-light-entrance-side chamfered surface 58 is 0.4 μm or more and 1.0 μm or less, the adhesiveness between the reflection sheet 6 and the non-light-entrance-side chamfered surface 58 is good. Further, the luminance unevenness generated in the light guide plate 5 can be reduced.

Next, a method for manufacturing glass to be used as the light guide plate 5 will be described.

Fig. 5 to 7 are views for explaining a method of manufacturing the light guide plate 5. Fig. 5 is a process diagram illustrating a method for manufacturing the light guide plate 5.

To manufacture the light guide plate 5, first, a glass raw material 12 is prepared. As described above, the glass material has an effective optical path length of 5 to 200cm, a thickness of preferably 0.5 to 10mm, an average internal transmittance of a visible light region in the effective optical path length of 80% or more, and a Y value of tristimulus values of XYZ color system in JIS Z8701 (attached books) of preferably 90% or more. The glass material 12 is formed into a shape larger than the predetermined shape of the light guide plate 5.

First, the glass raw material 12 is subjected to a cutting step (step is abbreviated as "S" in the figure) shown in step 10 of fig. 5. In the cutting step, a cutting process is performed at each position (light entrance end surface side position of 1 position and non-light entrance end surface side position of 3 positions) indicated by a broken line in fig. 6 using a cutting device. The cutting process need not be performed for the non-light-entrance end surface side positions of 3 portions, and may be performed only for the non-light-entrance end surface side positions of 1 portion opposed to the light-entrance end surface side positions of 1 portion.

By performing the cutting process, the glass base material 14 is cut from the glass raw material 12. In the present embodiment, since the light guide plate 5 has a rectangular shape in plan view, the cutting process is performed for the light incident end surface side positions of 1 portion and the non-light incident end surface side positions of 3 portions. However, the cutting position is appropriately selected according to the shape of the light guide plate 5.

When the cutting process is completed, the first chamfering step is performed (step 12). In the first chamfering step, the non-light-incident-side chamfered surface 58 is formed between the light exit surface 51 and the non-light-incident end surface 56, and between the light reflection surface 52 and the non-light-incident end surface 56, using a grinding device.

In the first chamfering step, when the non-light-entrance-side chamfer surface 58 is formed on all or any one of the light exit surface 51 and the non-light-entrance end surface 54, the light reflection surface 52 and the non-light-entrance end surface 54, the light exit surface 51 and the non-light-entrance end surface 55, and the light reflection surface 52 and the non-light-entrance end surface 55, the chamfer processing is performed.

In the first chamfering step, the light exit surface 51 and the light entrance end surface 53, or the light reflection surface 52 and the light entrance end surface 53 may be chamfered. In this case, from the viewpoint of productivity, it is preferable that the surface roughness Ra of the obtained chamfered surface be larger than the surface roughness Ra of the light entrance-side chamfered surface 57 obtained in the second chamfering step described later.

In the present embodiment, the non-light-incident end surfaces 54 to 56 are ground or polished in the first chamfering step. The grinding or polishing of the non-light-incident end surfaces 54 to 56 may be performed before or after the formation of the non-light-incident-side chamfered surface 58, or may be performed simultaneously. Note that, as for the non-light-incident end surfaces 54 and 55, the surfaces subjected to the cutting process may be used as they are as the non-light-incident end surfaces 54 and 55.

The first chamfering step (step 12) may be performed simultaneously with or after the mirror finishing step (step 14) and the second chamfering step (step 16) described later, but is preferably performed before these steps. As a result, since the processing corresponding to the shape of the light guide plate 5 can be performed at a relatively high rate in step 12, productivity is improved, and the light entrance end surface 53 and the light entrance-side chamfered surface 57 are less likely to be damaged by relatively large cullet generated in step 12.

When the first chamfering step (step 12) is completed, a mirror finishing step (step 14) is performed next. In the mirror-surface processing step, as shown in fig. 7, the light entrance end surface 53 is formed by mirror-surface processing on the light entrance end surface side of the glass substrate 14. As described above, the light entrance end surface 53 is a surface on which light enters from the light source 4. Thus, the light incident end surface 53 is mirror-finished to have a surface roughness Ra of 0.03 μm or less.

When the light entrance end face 53 is formed on the glass base material 14 in the mirror finishing step (step 14), a second chamfering step (step 16) is performed next, whereby the light entrance-side chamfered surface 57 (chamfered surface) is formed by grinding or polishing the light exit surface 51 and the light entrance end face 53 and the light reflection surface 52 and the light entrance end face 53. Step 16 may be performed before step 14, or may be performed simultaneously with step 14.

In the second chamfering step, the average value in the longitudinal direction of the width dimension X of the light entrance-side chamfered surface 57 is X_aveIn this case, the error in the longitudinal direction of X is preferably X_avePreferably within 50% of the above range, and the surface roughness Ra is preferably 0.4 μm or less.

In forming the light entrance-side chamfered surface 57, a grinding wheel may be used as a tool for grinding or polishing, and a polishing wheel, a brush, or the like made of cloth, leather, rubber, or the like may be used in addition to the grinding wheel. In this case, a polishing agent such as cerium oxide, aluminum oxide, silicon carbide, or colloidal silica may be used.

The light guide plate 5 is manufactured by performing the steps shown in steps 10 to 16. After the light guide plate 5 is manufactured, the reflection dots 10A to 10C are printed on the light reflection surface 52.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments described above, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

Examples

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

In experiments 1 to 3 below, the glass plate used was a glass plate containing 71.6% by mass of SiO₂0.97% of Al₂O₃3.6 percent of MgO, 9.3 percent of CaO and 13.9 percent of Na₂O, 0.05% of K₂O, 0.005% Fe₂O₃The glass plate (50 mm in vertical direction, 50mm in horizontal direction, and 2.5mm in plate thickness). The glass plate is a glass plate cut out in a cutting process from a glass plate manufactured by a float method (in the cutting process, a corner portion of the glass is cut to prevent breakage). The glass has 4 end faces between the light emergent face and the light reflecting face, 1 end face is a light incident end face and 3 end faces are non-light incident end facesAn end face.

After the cutting process, a first chamfering step is performed. In the first chamfering step, 3 non-incident end faces were ground. The glass is chamfered between the light exit surface and the non-incident end surface, between the light reflection surface and the non-incident end surface, between the light exit surface and the incident end surface, or between the light reflection surface and the incident end surface by using a grinding device.

(experiment 1)

First, an experiment for examining the relationship between Ra of the non-incident end face and the transmittance of light was performed.

The surface roughness Ra of the non-incident end face of the samples of examples 1 to 6 is shown in Table 1.

[ TABLE 1 ]

TABLE 1

	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6
							Ra(μm)	0.010	0.012	0.029	0.037	0.070	0.110
Difference in transmittance (%)	0.0185	-0.0296	0.0462	-0.0585	-1.9109	-4.3508

After the first chamfering step, a mirror finishing step is performed. In the mirror-surface processing step, the light incident end surface is mirror-surface processed. The surface roughness Ra of the incident end face of each of the samples of examples 1 to 6 was 0.01. mu.m. After the mirror surface processing step, a second chamfering step is performed to grind the light exit surface and the light entrance end surface and the light reflection surface and the light entrance end surface, thereby forming a light entrance-side chamfered surface.

The transmittance of the non-incident end face was measured for the samples of examples 1 to 6. In this measurement, light having a wavelength of 400nm to 800nm is made incident from the light incident end face side toward the non-light incident end face opposite to the light incident end face, and the average transmittance is calculated from the measured value of the transmittance. Further, the same measurement was carried out for a reference sample in which the non-light-incident end face was optically polished, which is different from the samples of examples 1 to 6, and the average transmittance at a wavelength of 400nm to 800nm was calculated. The difference (hereinafter, simply referred to as "transmittance difference") obtained by subtracting the average transmittance at a wavelength of 400nm to 800nm of the reference sample from the average transmittance at a wavelength of 400nm to 800nm of the samples of examples 1 to 6 is also shown in Table 1.

The relationship between the surface roughness Ra and the difference in transmittance of the samples of examples 1 to 6 is shown in fig. 8(a) to 8 (b). Fig. 8(a) and 8(b) each plot the surface roughness Ra and the transmittance difference shown in table 1, and only the range representing an approximate straight line is changed.

As shown in fig. 8(a) to 8(b), when the surface roughness Ra of the non-incident end surface exceeds 0.04 μm, the difference in transmittance cannot be ignored. If the surface roughness Ra of the non-light-incident end face exceeds 0.8 μm, the difference in transmittance is less than-50%, and most of the incident light that does not pass through the non-light-incident end face is diffused and reflected (diffused reflection) at the non-light-incident end face, causing a decrease in luminance.

(experiment 2)

Next, an experiment for studying the relationship between the adhesion area and the adhesive force between the non-incident end face and the reflective sheet was performed. First, reflective sheets (product name: polyester film adhesive tape for light-shielding, type No.6370, manufactured by Tekka) having tape widths of 6mm, 12mm and 24mm were prepared and arranged on the glass surface having a surface roughness Ra of 0.0044 μm, respectively. For these samples, 180 ° peel adhesion tests of the adhesive tape/sheet specified in JIS Z0237 were performed. A table-top precision universal tester (model name: AGS-5kNX, manufactured by Shimadzu corporation) was used as the tester. The peel adhesion test was performed 5 times for each of 1 sample, and an average value of adhesion P (N/10mm) (hereinafter, simply referred to as "adhesion") was calculated from the value of the product f (N) of the adhesion and the tape width. They are shown in table 2.

[ TABLE 2 ]

TABLE 2

Belt width (mm)	6.0	12.0	24.0
				Product of adhesive force and tape width F (N)	5.49	10.83	20.06
Adhesion P (N/10mm)	9.15	9.03	8.36

Since the area of the reflective sheet is proportional to the tape width, the product F of the adhesive force and the tape width is approximately proportional to the area of the reflective sheet. In addition, when the reflecting sheet is provided on the glass surface having the same surface roughness Ra, the area void ratio at the interface between the non-light-incident end face and the reflecting sheet is considered to be the same. Therefore, it is found that the area (adhesion area) where the non-light-incident end surface and the reflection sheet actually adhere is approximately proportional to F. Thus, the adhesive area and the area porosity can be relatively calculated by performing the peeling adhesion test using the same material and the same area of the reflection sheet for the sample having the plurality of surface roughness Ra.

The higher the area void ratio, the smaller the proportion of the adhesion area at the interface between the non-light-incident end face and the reflective sheet. Thus, even in experiment 1, the incident light transmitted through the non-light-incident end surface does not directly reach the reflective sheet at the interface, and is easily diffused and reflected in the void.

(experiment 3)

Next, an experiment for investigating the influence of the surface roughness Ra of the non-incident end face on the adhesive force between the non-incident end face and the reflective sheet was performed. First, a reflective sheet (product name: polyester film adhesive tape for light-shielding, model No.6370, manufactured by Temple and gamble) having a tape width of 12mm was prepared and disposed on the glass surface having surface roughness Ra of 0.0044 μm, 0.0395 μm, 0.0677 μm, 0.1170 μm, 0.1640 μm, 0.4040 μm, 0.5670 μm, and 2.686 μm, respectively. These samples were used as examples 7 to 14, respectively. Further, the same applies to the reflection sheets having a tape width of 24mm, which were disposed on the glass surfaces having surface roughness Ra of 0.0044 μm, 0.0395 μm, 0.0677 μm, 0.117 μm, 0.164 μm, 0.404 μm, 0.567 μm, and 2.686 μm, respectively. These samples are examples 15 to 22, respectively.

For these samples, the peel adhesion test of the adhesive tape/sheet prescribed in JIS Z0237 was performed in the same manner as in experiment 2, and the average value (hereinafter, also simply referred to as "adhesion") of the adhesion force P (N/10mm) measured by performing the peel adhesion test 5 times for each of 1 sample was calculated. The adhesion P at the interface between the non-incident end face and the reflective sheet of the samples of examples 7 to 22 is shown in table 3. Table 3 also shows the area porosity calculated from the adhesive force P when the area porosity of examples 7 and 15 is 0%. The relationship between the surface roughness Ra and the adhesive force P of the samples of examples 7 to 14 is shown in FIG. 9, and the relationship between the surface roughness Ra and the adhesive force P of the samples of examples 15 to 22 is shown in FIG. 10.

[ TABLE 3 ]

TABLE 3

As described above, the surface roughness Ra of the non-incident end face positively correlates with the area void ratio. From this, it was revealed that when the surface roughness Ra of the non-incident end face exceeds 0.8 μm, the area void ratio exceeds 40%, and the decrease in luminance cannot be ignored.

The present invention has been described in detail with reference to the specific embodiments, but it is obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

It should be noted that the present application is based on the japanese patent application filed on 12/2/2015 (japanese patent application 2015-025339), which is incorporated herein by reference in its entirety.

Description of the reference symbols

1 liquid crystal display device

2 liquid crystal panel

3-surface light emitting device

4 light source

5 light guide plate (glass)

6 reflective sheet

7 diffusion sheet

8 reflector

10A-10C reflection point

12 glass raw material

14 glass substrate

51 light emergent surface (first surface)

52 light reflecting surface (second surface)

53 incident light end face (first end face)

54. 55, 56 non-incident end face (second end face)

57 incident light side chamfer surface (first chamfer surface)

58 non-incident light side chamfer surface (second chamfer surface)

Claims

1. A glass light guide plate having glass and a reflecting sheet, wherein,

the glass has:

a first side;

a second face opposite the first face;

the effective optical path length of the glass is 5-200 cm,

the second end face has a surface roughness Ra of 0.8 [ mu ] m or less,

the reflecting sheet is disposed on the second end surface.

2. The glass light guide plate according to claim 1,

the first face is in the shape of a rectangle,

the glass has at least three of the second end faces,

the surface roughness Ra of the second end surface is less than or equal to 0.8 mu m.

3. The glass light guide plate according to claim 1 or 2,

the surface roughness Ra of the second end surface is more than or equal to the surface roughness Ra of the first end surface.

4. The glass light guide plate according to claim 3,

the second end face has a surface roughness Ra greater than a surface roughness Ra of the first end face.

5. The glass light guide plate according to claim 1 or 2,

the glass has at least one chamfered surface between the first or second face and the second end face,

an average value in a longitudinal direction of a width dimension L of the second end surface is defined as L_aveSetting the maximum value as L_maxSetting the minimum value as L_minWhen, satisfy L_max≤1.5×L_aveAnd L is_min≥0.5×L_aveWherein L is_ave、L_max、L_minThe unit of (d) is mm.

6. The glass light guide plate according to claim 3,

7. The glass light guide plate according to claim 4,

8. The glass light guide plate according to claim 1 or 2,

an area void ratio V at an interface between the second end face and the reflective sheet, which is determined by the following equation, is 40% or less,

V＝100×(1-P/P₀)

p: peel adhesion of the reflector sheet to the second end face measured by peel adhesion test specified in JIS Z0237, wherein the peel adhesion is in a unit of N/10mm

P₀: a peel adhesion of the reflector sheet to an end face of glass having a surface roughness Ra of 0.0050 μm or less, measured by a peel adhesion test prescribed in JIS Z0237, wherein the peel adhesion is a single componentThe bits are N/10 mm.

9. The glass light guide plate according to claim 3,

V＝100×(1-P/P₀)

P₀: the reflection sheet has a peel adhesion to an end face of glass having a surface roughness Ra of 0.0050 [ mu ] m or less, as measured by a peel adhesion test prescribed in JIS Z0237, wherein the unit of the peel adhesion is N/10 mm.

10. The glass light guide plate according to claim 4,

V＝100×(1-P/P₀)

11. The glass light guide plate according to claim 1 or 2,

the reflective sheet has at least one selected from the group consisting of polyester resin, acrylic resin, and polyurethane resin.

12. The glass light guide plate according to claim 3,

13. The glass light guide plate according to claim 4,

14. The glass light guide plate according to claim 1 or 2,

the glass light guide plate is used for a planar light emitting device.

15. The glass light guide plate according to claim 1 or 2,

and forming a reflection point on the second surface.

16. The glass light guide plate according to claim 1 or 2,

the second end face has a surface roughness Ra of 0.4 [ mu ] m or less.

17. The glass light guide plate according to claim 1 or 2,

the second end face has a surface roughness Ra of 0.2 [ mu ] m or less.

18. The glass light guide plate according to claim 1 or 2,

the second end face has a surface roughness Ra of 0.1 [ mu ] m or less.

19. The glass light guide plate according to claim 1 or 2,

the second end surface has a surface roughness Ra of 0.04 [ mu ] m or less.

20. A glass light guide plate, the glass light guide plate having:

a first side;

a second face opposite the first face;

wherein,

the effective optical path length of the glass is 5-200 cm,

the second end face has a surface roughness Ra of 0.8 [ mu ] m or less.

21. The glass light guide plate of claim 20,

the first face is in the shape of a rectangle,

the glass has at least three of the second end faces,

22. The glass light guide plate according to claim 20 or 21,

23. The glass light guide plate of claim 22,

24. The glass light guide plate according to claim 20 or 21,

25. The glass light guide plate of claim 22,

26. The glass light guide plate of claim 23,

27. The glass light guide plate according to claim 20 or 21,

the glass light guide plate is used for a planar light emitting device.

28. The glass light guide plate according to claim 20 or 21,

and forming a reflection point on the second surface.

29. The glass light guide plate according to claim 20 or 21,

the second end face has a surface roughness Ra of 0.4 [ mu ] m or less.

30. The glass light guide plate according to claim 20 or 21,

the second end face has a surface roughness Ra of 0.2 [ mu ] m or less.

31. The glass light guide plate according to claim 20 or 21,

the second end face has a surface roughness Ra of 0.1 [ mu ] m or less.

32. The glass light guide plate according to claim 20 or 21,

the second end surface has a surface roughness Ra of 0.04 [ mu ] m or less.