JP5459122B2 - Display device - Google Patents

Description

  The present invention relates to a display device.

  Mobile devices such as mobile phones, PDAs, and notebook personal computers are equipped with thin display devices such as liquid crystal display (LCD) devices. In this display device, a cover glass plate called a “front filter” is installed in front of the display panel, and the user visually recognizes the display on the display panel via the front plate (see, for example, Patent Document 1).

  The cover glass plate is mainly installed for the purpose of improving the aesthetics and strength of the display device and preventing impact damage. The cover glass plate is often a chemically strengthened glass plate in which a compressive stress layer is provided on at least a part of the surface layer in order to improve scratch resistance. As a method for producing chemically strengthened glass, for example, there is an ion exchange method.

  In the ion exchange method, a glass is immersed in a treatment solution, and ions having a small ion radius (for example, Na ions) contained in the surface layer of the glass are replaced with ions having a large ion radius (for example, K ions). A compressive stress layer is provided on the surface layer of the glass.

JP 2007-11210 A

  On the other hand, in recent years, liquid crystal display (LCD) devices and plasma display (PDP) devices have become larger for stationary devices such as home televisions, and the screen size is extremely large compared to mobile devices. It is getting bigger.

  The cover glass plate mounted on such a large screen (for example, 32 inches or more) display device has a larger area than that mounted on a mobile device. Moreover, in order to reduce the accompanying weight increase, the cover glass plate is often made thinner.

  However, when the cover glass plate has a large area and is thinned, the cover glass plate is easily deformed by its own weight, so that the aesthetic appearance and display quality of the display device may be impaired.

  This invention is made | formed in view of the said subject, Comprising: It aims at providing the display apparatus which can reduce the dead weight deformation | transformation of a thin cover glass board with a large area.

According to one aspect of the invention,
In a display device comprising a display panel and a cover glass plate installed in front of the display panel,
The cover glass plate has a diagonal length of 32 inches or more, a thickness of 1.5 mm or less, and a Young's modulus of 70 GPa or more, and a chemical layer in which a compressive stress layer is provided on at least a part of the surface layer by chemical strengthening treatment. A tempered glass plate,
The cover glass plate before the chemical strengthening treatment is expressed in terms of mole percentage based on oxide, ₂ 50-74%, Al ₂ O ₃ 1 to 10%, Na ₂ 6-14% O, K ₂ 3-15% O, 2-15% MgO, 0-10% CaO, ZrO ₂ 0 to 5%, SiO ₂ And Al ₂ O ₃ Total content of 75% or less, Na ₂ O and K ₂ Total Na content of O ₂ O + K ₂ A display device is provided, characterized in that O is 12 to 25%, and the total content of MgO and CaO is MgO + CaO is 7 to 15%.
According to another aspect of the present invention,
In a display device comprising a display panel and a cover glass plate installed in front of the display panel,
The cover glass plate has a diagonal length of 32 inches or more, a thickness of 1.5 mm or less, and a Young's modulus of 70 GPa or more, and a chemical layer in which a compressive stress layer is provided on at least a part of the surface layer by chemical strengthening treatment. A tempered glass plate,
The cover glass plate before the chemical strengthening treatment is expressed in terms of mole percentage based on oxide, ₂ 68-80%, Al ₂ O ₃ 4-10% Na ₂ 5-15% O, K ₂ 0 to 1% O, 4 to 15% MgO, ZrO ₂ 0 to 1%, SiO ₂ And Al ₂ O ₃ Total content of SiO ₂ + Al ₂ O ₃ A display device is provided, characterized in that is less than 85%.

  ADVANTAGE OF THE INVENTION According to this invention, the display apparatus which can reduce the dead weight deformation | transformation of a thin cover glass board with a large area can be provided.

It is side surface sectional drawing of the display apparatus in one Embodiment of this invention. It is a front view of FIG. It is side surface sectional drawing of the modification of FIG. It is a diagram showing the relationship between the molten salt (KNO ₃₎ Li content in the surface compression stress S of the glass after (mass%) and the chemical strengthening treatment (MPa). It is a diagram showing the relationship between content of ZrO ₂ in the glass (mol%) and the glass after chemical strengthening treatment Vickers hardness (HV).

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, this invention is not restrict | limited to the below-mentioned embodiment, A various deformation | transformation and substitution can be added to below-mentioned embodiment, without deviating from the scope of the present invention.

  FIG. 1 is a schematic side view of a display device according to an embodiment of the present invention. As shown in FIG. 1, the display device 10 includes a display panel 20 and a cover glass plate 30. The cover glass plate 30 has a larger area than the display panel 20, and the user visually recognizes the display on the display panel 20 through the cover glass plate 30.

(Display panel)
The display panel 20 displays an image. The display panel 20 may have a general configuration, for example, a liquid crystal panel or a plasma panel. The liquid crystal panel includes two light transmissive substrates and a liquid crystal layer provided between the two light transmissive substrates. The plasma panel is composed of two light-transmitting substrates and a phosphor layer provided between the two light-transmitting substrates.

  As the translucent substrate for the display panel 20, a glass substrate, a resin substrate, or the like is used. A glass substrate is excellent in heat resistance and chemical resistance, and can be subjected to heat treatment or chemical treatment when a transparent electrode film, a semiconductor element (for example, TFT) or the like is formed on the substrate. On the other hand, the resin substrate is excellent in flexibility. In general, a glass substrate is often used.

  The glass substrate is formed of a material corresponding to the type of the display panel 20. For example, a glass substrate for a liquid crystal panel is formed of a non-alkali glass that does not substantially contain an alkali metal oxide because alkali metal ions adversely affect the display characteristics of the liquid crystal panel. Moreover, the glass substrate for plasma panels is formed with soda-lime glass having a high strain point and a large thermal expansion coefficient.

  As a method for producing a glass substrate, first, a plurality of glass raw materials are prepared so as to have a target composition, which is continuously charged into a melting furnace and heated to, for example, 1500 to 1600 ° C. and melted. Next, this molten glass is formed to a predetermined plate thickness, and after slow cooling, it is cut to obtain a glass substrate.

  Here, a molding method for molding the molten glass into a predetermined plate thickness is not particularly limited, and examples thereof include a float method and a fusion method. In the float process, molten glass is continuously supplied to a bath surface of molten metal (for example, molten tin) in a bathtub, and is formed into a strip shape. In the fusion method, molten glass is continuously supplied into the inside of a bowl having a substantially V-shaped cross section, and the molten glass overflowing from the bowl to the left and right sides is joined at the lower edge of the bowl to form a strip.

(Cover glass plate and its peripheral members)
The cover glass plate 30 is installed mainly for the purpose of improving the appearance and strength of the display device 10 and preventing impact damage. The cover glass plate 30 is installed in front of the display panel 20.

  For example, the cover glass plate 30 may be installed so as to be separated from the display side (front side) of the display panel 20, as shown in FIG. In this case, the cover glass plate 30 and the display panel 20 may be integrated via the housing 12. In addition, although the housing | casing 12 is shown in figure so that the cover glass 30 may be covered from the outer side in FIG. 1, the end surface of the cover glass 30 may be exposed.

  Moreover, the cover glass plate 30 may be affixed on the display side (front side) of the display panel 20, as shown in FIG. For example, the cover glass plate 30 is affixed to the display side of the display panel 20 via a translucent adhesive film. The adhesive film may have a general configuration, and the material and shape thereof are appropriately selected.

  As shown in FIG. 3, by adopting a configuration in which there is no gap between the cover glass plate 30 and the display panel 20, reflection of light at the interface between the cover glass plate 30 (or the display panel 20) and the gap is suppressed. be able to. As a result, the image quality of the display device 10 can be improved. In addition, the display device 10 can be reduced in thickness.

  The cover glass plate 30 has a front surface 31 that emits light from the display panel 20 and a back surface 32 that receives light from the display panel 20. A functional film 40 may be provided on the front surface 31 and / or the back surface 32. Note that the functional film 40 is provided on the front surface 31 and the back surface 32 in FIG. 1, and is provided on the front surface 31 in FIG.

  The functional film 40 has functions such as preventing reflection of ambient light, preventing impact damage, shielding electromagnetic waves, shielding near infrared rays, correcting color tone, and / or improving scratch resistance.

  The functional film 40 is formed, for example, by attaching a resin film to the cover glass plate 30. Alternatively, the functional film 40 may be formed by a thin film forming method such as a vapor deposition method, a sputtering method, or a CVD method.

  The functional film 40 may have a general configuration, and the thickness, shape, and the like are appropriately selected according to the application.

  On the back surface 32 of the cover glass plate 30, a decorative layer 50 is provided along at least a part of the peripheral edge. The decorative layer 50 may be disposed so as to surround the outer periphery of the display panel 20.

  The decorative layer 50 is installed in order to improve the design and decoration of the cover glass plate 30 and thus the display device 10. For example, when the decorative layer 50 is colored black, no light is emitted from the front surface 31 of the cover glass plate 30 including the peripheral edge of the cover glass plate 30 when the display device 10 is in the off state. Accordingly, the appearance of the display device 10 gives a sharp impression to the user, and the aesthetic appearance is improved.

  There is no restriction | limiting in the formation method of the decoration layer 50, For example, there exists the method of apply | coating the ink containing organic pigment particle | grains to the cover glass plate 30, and irradiating this with an ultraviolet-ray or heat-firing. The ink is prepared, for example, by mixing and dispersing organic pigment particles in an organic vehicle.

(Material and characteristics of cover glass plate)
The thickness of the cover glass plate 30 is 1.5 mm or less, preferably 1.3 mm or less, and more preferably 1.1 mm or less, from the viewpoints of reduction in thickness and weight. Moreover, it is preferable that the thickness of the cover glass plate 30 is 0.5 mm or more from a viewpoint of handling property.

  The diagonal length L of the cover glass plate 30 is 32 inches (about 81 cm) or more, preferably 37 inches (about 94 cm or more), more preferably 40 inches (about 102 cm or more) from the viewpoint of increasing the area. ).

  The Young's modulus of the cover glass plate 30 is 70 GPa or more. By setting it as 70 GPa or more, the self-weight deformation of the cover glass plate 30 having a thickness of 1.5 mm or less and a diagonal length of 32 inches (about 81 cm) or more can be sufficiently reduced. The Young's modulus of the cover glass plate 30 is preferably 72 GPa or more, and more preferably 75 GPa or more.

  The cover glass plate 30 may be formed of a material having the same composition as the glass substrate of the display panel 20. When the composition is the same, warpage due to a difference in thermal expansion can be reduced, and the manufacturing cost can also be reduced. Further, the reduction of the warpage and the manufacturing cost are more remarkable as the size of the panel is increased.

  Further, the cover glass plate 30 may be a chemically strengthened glass plate in which a compressive stress layer is provided on at least a part of the surface layer by chemical strengthening treatment in order to improve scratch resistance. Examples of the chemical strengthening treatment include an ion exchange method.

  In the ion exchange method, a glass plate is immersed in a processing solution, and ions having a small ion radius (for example, Na ions) contained in the surface layer of the glass plate are replaced with ions having a large ion radius (for example, K ions). Thus, a compressive stress layer is provided on the surface layer of the glass plate.

As the treatment liquid, potassium nitrate (KNO ₃ ) molten salt or the like is used. Specific conditions vary depending on the thickness of the glass plate, it is typical to immerse 2-20 hours glass plate KNO ₃ molten salt at 400 to 550 ° C.. From an economical viewpoint, it is preferable to immerse on the conditions of 400-500 degreeC and 2 to 16 hours, and a more preferable immersion time is 2 to 10 hours.

  The cover glass plate 30 before the chemical strengthening treatment is not particularly limited, and is formed of, for example, the following glasses A to C.

(Glass A)
Glass A contains oxide-based mole percentages and contains SiO ₂ 55-70%, Al ₂ O ₃ 5-15%, Na ₂ O 4-20%, MgO 1-15%, these The total amount of the components of the glass is 85% or more.

  The Young's modulus of glass A is typically 70 to 85 GPa. The Young's modulus of the chemically strengthened glass plate obtained by chemically strengthening the glass A is substantially the same as the Young's modulus of the glass A before chemical strengthening because the compressive stress layer thickness t is sufficiently small.

(Glass B)
Glass B is a molar percentage based on oxides, SiO ₂ 50 to 74%, the _{Al 2 O 3 1~10%, 6~14} % of Na ₂ O, 3 to 15% of _{K 2} O, MgO 2 to 15%, CaO 0 to 10%, ZrO ₂ 0 to 5%, the total content of SiO ₂ and Al ₂ O ₃ is 75% or less, the content of Na ₂ O and K ₂ O Is 12 to 25%, and the total MgO + CaO content of MgO and CaO is 7 to 15%. The glass B may be the following glasses B1 to B3.

Glass B1 is the above glass B, and Na ₂ O is 12% or less, K ₂ O is 4% or more, Na ₂ O + K ₂ O is 14% or more, MgO + CaO is 8% or more, Na ₂ O + K ₂ O to Al _The difference obtained by reducing the ₂ O ₃ content is 10% or more. When BaO is contained, the content is less than 1%.

  When this glass B1 contains SrO or BaO, the total content of alkaline earth metal oxides may be 15% or less.

In this glass B1, SiO ₂ is 60~70%, _Al 2 _{O 3} is 2~8%, Na ₂ O 11% or less, _{K 2} O is 6 to 12%, MgO is 4 to 14%, CaO 0 to 8%, ZrO ₂ is _{0~4%, Na 2 O + K} 2 O may be 16 to 20%.

The glass B2 is the glass B, and SiO ₂ is 60 to 70%, Al ₂ O ₃ is 2 to 8%, K ₂ O is 8% or less, MgO is 6% or more, and Na ₂ O + K ₂ O is 18%. % or less, and the sum _{Na 2} O + 1.7K 2 O and multiplied by 1.7 to content of _{K 2} O and the content of Na ₂ O is less than 19%.

Glass B3 is the glass B, and SiO ₂ is 63% or more, Al ₂ O ₃ is 3% or more, Na ₂ O is 8% or more, K ₂ O is 8% or less, MgO is 6 to 14%, CaO is 0 to 1%, ZrO ₂ is 1 to 4%, and Na ₂ O + K ₂ O is 14 to 17%.

In this glass B3, the sum Na ₂ O + 1.7K ₂ O of the K ₂ O content multiplied by 1.7 and the Na ₂ O content may be less than 19%.

According to these glasses B (B1 to B3), since the K ₂ O content is sufficiently high, the compressive stress layer thickness t can be increased without excessively increasing the ion exchange rate of chemical strengthening. Therefore, the thickness t of the compressive stress layer can be increased while the surface compressive stress S is set to less than 1050 MPa, for example, without performing a separate polishing process after the chemical strengthening process.

  In the chemically strengthened glass plate formed by chemically strengthening the glass B, the compressive stress layer thickness t is preferably more than 20 μm. If it is 20 μm or less, there is a risk of being easily broken. More preferably, it is 30 μm or more, particularly preferably 40 μm or more, typically 45 μm or more, or 50 μm or more.

  In the chemically strengthened glass plate formed by chemically strengthening the glass B, the surface compressive stress S is typically 300 MPa or more and less than 1050 MPa. If it is less than 300 MPa, there is a risk of being easily broken. In the chemically strengthened glass plate formed by chemically strengthening the glass B2, the surface compressive stress S is typically 300 MPa or more and less than 750 MPa. In the chemically strengthened glass plate formed by chemically strengthening the glass B3, the surface compressive stress S. Is typically 700 MPa or more and less than 1050 MPa.

  The glass transition point Tg of the glass B is typically 540 to 610 ° C. in the glass B1, and typically 580 to 640 ° C. in the glasses B2 and B3.

The temperature T _{4 at} which the viscosity of the glass B becomes 10 ⁴ dPa · s is preferably 1190 ° C. or lower. If it exceeds 1190 ° C., glass molding may be difficult. Typically, it is 1180 ° C. or lower.

The temperature T _{2 at} which the viscosity of the glass B becomes 10 ² dPa · s is preferably 1650 ° C. or lower. If it exceeds 1650 ° C., melting becomes difficult, and there is a risk that product defects such as unmelted material may increase, or the melting equipment may become expensive. Typically, it is 1600 ° C or lower.

It is preferred devitrification temperature of the glass B is the T ₄ or less. Otherwise, for example, when the float process is applied, devitrification may occur and molding may become difficult. Here, the devitrification temperature is the maximum temperature at which devitrification precipitates when the glass is held at that temperature for 15 hours.

  The specific gravity ρ of the glass B is preferably 2.6 or less. If it exceeds 2.6, the weight of the display device 10 may be insufficient.

The average thermal expansion coefficient α of the glass B at 50 to 350 ° C. is typically 80 × 10 ^{−7 to} 130 × 10 ⁻⁷ / ° C.

  The Young's modulus of the glass B is typically 70 to 90 GPa. The Young's modulus of the chemically strengthened glass plate obtained by chemically strengthening the glass B is substantially the same as the Young's modulus of the glass B before chemical strengthening because the compressive stress layer thickness t is sufficiently small.

  Of the glass B, the glass B1 is a suitable mode when it is desired to increase the thickness t of the compressive stress layer while the surface compressive stress S is set to less than 750 MPa, for example, without performing a separate polishing process after the chemical strengthening process. Glass B2 and glass B3 are a suitable aspect when clarification at the time of glass manufacture is performed with a sulfate.

  Next, the composition of the glass B will be described using the mole percentage display content unless otherwise specified.

SiO ₂ is a component constituting the skeleton of glass and essential. If it is less than 50%, the stability as glass is lowered, or the weather resistance is lowered. Preferably it is 60% or more. In addition, in glass B2, it is 60% or more, Preferably it is 62% or more, and in glass B3, it is 63% or more.

If the SiO ₂ content exceeds 74%, the viscosity of the glass increases and the meltability decreases significantly. Preferably it is 70% or less, typically 68% or less. Incidentally, SiO ₂ in the glass B2 is 70% or less.

Al ₂ O ₃ is a component that improves the ion exchange rate and is essential. If it is less than 1%, the ion exchange rate decreases. Preferably it is 2% or more, typically 3% or more. In addition, Al ₂ O ₃ is 2% or more in the glass B2, and ₃ % or more in the glass B3.

If Al ₂ O ₃ exceeds 10%, the viscosity of the glass becomes high and uniform melting becomes difficult. It is preferably 9% or less, more preferably 8% or less, and typically 7% or less. In the glass B2, Al ₂ O ₃ is 8% or less.

If the total content of SiO ₂ and Al ₂ O ₃ exceeds 75%, the viscosity of the glass at a high temperature increases and melting becomes difficult. Typically 72% or less. The total is preferably 66% or more. If it is less than 66%, it is difficult to obtain a stable glass or the weather resistance tends to be lowered, and it is typically 68% or more.

Na ₂ O is a component that forms a compressive stress layer by ion exchange and improves the meltability of the glass, and is essential. If it is less than 6%, it becomes difficult to form a desired compressive stress layer by ion exchange. Preferably it is 7% or more, typically 8% or more. In the glass B3, Na ₂ O is 8% or more.

If Na ₂ O exceeds 14%, Tg and therefore the strain point is lowered, or the weather resistance is lowered. Preferably it is 13% or less, typically 12% or less. In the glass B1, Na ₂ O is 12% or less, preferably 11% or less, and typically 10% or less.

K ₂ O is a component for improving the meltability, and is a component for increasing the ion exchange rate in chemical strengthening to obtain a desired surface compressive stress S and compressive stress layer thickness t. is there. If it is less than 3%, the meltability is lowered, or the ion exchange rate is lowered. Typically 4% or more. In the glass B1, K ₂ O is 4% or more, preferably 5% or more, more preferably 6% or more, and typically 7% or more. Note that the K ₂ O mass percentage display content is typically 3% or more.

If K ₂ O exceeds 15%, the weather resistance decreases. Preferably it is 12% or less, typically 11% or less. In the glass B2 and the glass B3, K ₂ O is 8% or less, preferably 7% or less, and typically 6% or less.

If the total R ₂ O content of Na ₂ O and K ₂ O is less than 12%, desired ion exchange characteristics cannot be obtained. Preferably it is 13% or more, More preferably, it is 14% or more. In the glass B1 and the glass B3, R ₂ O is 14% or more, and in the glass B1, it is preferably 16% or more, more preferably 16.5% or more, and typically 17% or more.

If R ₂ O exceeds 25%, the chemical durability including the weather resistance of the glass becomes low. It is preferably 22% or less, more preferably 20% or less, and typically 19% or less. In order to reduce the basicity of the glass and improve the clarity with sulfates, R ₂ O is 18% or less for glass B2 and 17% or less for glass B3.

In order to reduce the basicity of the glass and improve the clarification by sulfate, the glass B2 contains Na ₂ O + 1.7K ₂ O of less than 19%. Also in the glass B3, Na ₂ O + 1.7K ₂ O is preferably less than 19%. The phrase “reducing the basicity of the glass and improving the clarification with sulfate” means that the decomposition temperature of sodium sulfate is about 1500 ° C. or less in the case of clarification with sodium sulfate.

The difference R ₂ O—Al ₂ O ₃ obtained by subtracting the content of Al ₂ O ₃ from R ₂ O is preferably 10% or more. If it is less than 10%, the compressive stress layer thickness t may be small. It is considered that the compressive stress layer thickness t becomes smaller because Tg and hence the strain point becomes higher. The glass B1 in _R 2 _O-Al 2 O ₃ is 10% or more.

The difference obtained by subtracting R ₂ O from the total content of SiO ₂ and Al ₂ O ₃ is preferably 60% or less. If it exceeds 60%, the T ₂ may exceed 1650 ° C. and melting may be difficult.

Li ₂ O is a component that lowers the strain point and facilitates stress relaxation, and as a result makes it impossible to obtain a stable compressive stress layer. Therefore, it is preferably not contained, and even if it is contained, its content is It is preferably 2% or less, more preferably 0.05% or less, and particularly preferably less than 0.01%.

Further, Li ₂ O may be eluted in a molten salt such as KNO ₃ during chemical strengthening treatment, but when the chemical strengthening treatment is performed using a molten salt containing Li, the surface compressive stress S is remarkably reduced. That is, the inventors have found that 0.005% by weight _KNO 3, Li containing no Li, 0.01 wt%, 450 ° C. The glass of the infra materials Example 19 using KNO ₃ containing 0.04 wt% When the chemical strengthening treatment was performed under conditions of 6 hours, it was found that the surface compressive stress was significantly reduced only by the molten salt containing 0.005% by mass of Li as shown in FIG. Therefore, it is preferable not to contain Li ₂ O from this viewpoint.

The ratio of the total content of K ₂ O and alkali metal oxide is preferably 0.25 or more, more preferably 0.4 or more, and typically more than 0.5.

  Alkaline earth metal oxides are components that improve the meltability, and are effective components for adjusting the Tg and therefore the strain point.

  Since BaO has the greatest effect of reducing the ion exchange rate among alkaline earth metal oxides, BaO should not be contained, or even if contained, its content should be less than 1%. Preferably, in glass B1, even if it contains, it must be made less than 1%.

  SrO may be contained as necessary, but since the effect of lowering the ion exchange rate is greater than that of MgO and CaO, the content is preferably less than 1% even when contained.

  When SrO or BaO is contained, the total content thereof is preferably 3% or less, more preferably less than 2%.

  MgO and CaO are relatively small in the effect of lowering the ion exchange rate, and must contain at least 2% of MgO.

  If MgO is less than 2%, the meltability is lowered. It is preferably 4% or more, more preferably 6% or more, and typically 6.5% or more. In addition, in the glass B2 and the glass B3, MgO is 6% or more, preferably 6.5% or more, and typically 10% or more.

  If MgO exceeds 15%, the ion exchange rate decreases. Preferably it is 14% or less, More preferably, it is 13.5% or less. In the glass B1, MgO is particularly preferably 13% or less, typically 12% or less, and in the glass B3, MgO is 14% or less.

  When CaO is contained, its content is typically 1% or more. If the content exceeds 10%, the ion exchange rate decreases. Preferably it is 8% or less, typically 6% or less. Even when CaO is contained in glass B2, its content is typically 1% or less, and in glass B3, it must be 1% or less.

  When CaO is contained, the ratio of the content of MgO and CaO is preferably 1 or more. More preferably, it is 1.1 or more.

  The total MgO + CaO content of MgO and CaO is 7-15%, typically 8% or more, and should be 8% or more for glass B1. The total content of MgO and CaO expressed in terms of mass percentage is typically 5.1% or more.

The ratio of the content of MgO + CaO and Al ₂ O ₃ is preferably 1.2 or higher, typically 1.5 or higher.

  The total RO of the alkaline earth metal oxide content is preferably more than 2% and 15% or less. If it is 2% or less, the meltability is lowered, or the adjustment of the strain point becomes difficult. It is preferably 4% or more, more preferably 6% or more, and typically 8% or more. If it exceeds 15%, the ion exchange rate tends to be low, devitrification tends to occur, or the strain point may be too low.

In glass B other than glass B3, ZrO ₂ is not essential, but may be contained in a range of up to 5% in order to increase the ion exchange rate. If it exceeds 5%, the effect of increasing the ion exchange rate is saturated, and the meltability is deteriorated and may remain in the glass as an unmelted product. Further, the Vickers hardness of the glass after chemical strengthening treatment increases by containing ZrO ₂ as shown in FIG. Incidentally, the glass shown in FIG. 5 is (1) in terms of mole percentage, in addition to the glass of material examples 5, 9, and 10 described later, SiO ₂ is 64.0%, Al ₂ O ₃ is 5.4%, Glass containing 9.6% Na ₂ O, 9.1% K ₂ O, 5.4% MgO, 4.0% CaO and 2.5% ZrO ₂ , (2) in mole percentages SiO ₂ 64.0%, Al ₂ O ₃ 5.3%, Na ₂ O 9.6%, K ₂ O 9.1%, MgO 5.2%, CaO 4.0% , Glass containing 2.7% of ZrO ₂ , (3) in mole percentage, SiO ₂ 66.8%, Al ₂ O ₃ 11.0%, Na ₂ O 13.1%, K ₂ O Is 2.5%, MgO is 6.1%, and CaO is 0.6%. ZrO ₂ is preferably at most 4%, typically at most 2%. When ZrO ₂ is contained, its content is preferably 0.5% or more, and typically 1% or more.

In the glass B3, ZrO ₂ is essential and contained by 1 to 4%. Typically 1.5 to 3%.

  Glass B consists essentially of the components described above, but may contain other components as long as the effects of glass B are not impaired. When such components are contained, the total content of these components is preferably 10% or less, and typically 5% or less. Hereinafter, the other components will be described as an example.

  ZnO may be contained up to 2%, for example, in order to improve the melting property of the glass at high temperature, but it is preferably 1% or less. In the case of producing by the float process, etc., it is preferably 0.5% or less. If it exceeds 0.5%, it may be reduced during float molding, resulting in a product defect. Typically no ZnO is contained.

B ₂ O ₃ may be contained, for example, up to 1% in order to improve the melting property at high temperature or the glass strength. If it exceeds 1%, it is difficult to obtain homogeneous glass, and it may be difficult to mold the glass. Typically no B ₂ O ₃ is contained.

Since TiO ₂ changes the redox state of Fe ions (Fe ²⁺ , Fe ³⁺ ) present in the glass and the visible light transmittance may change, and the glass may be colored. It is preferred and typically not contained.

As a fining agent for melting the glass, SO ₃ , chloride, fluoride and the like may be appropriately contained. However, in order to improve the image quality, it is preferable to reduce as much as possible components such as Fe ₂ O ₃ , NiO, and Cr ₂ O ₃ that have absorption in the visible region as impurities in the raw material, and 0.15 by mass percentage each. % Or less, more preferably 0.05% or less.

(Glass C)
Glass C is a molar percentage based on oxides, SiO ₂ 68 to 80%, the _{Al 2 O 3 4~10%, 5~15} % of Na ₂ O, 0 to 1% of _{K 2} O, MgO 4-15%, ZrO ₂ 0-1%, the total content of SiO ₂ and Al ₂ O ₃ SiO ₂ + Al ₂ O ₃ is 85% or less.

In this glass C, Al ₂ O ₃ may be 4.5% or more. In this glass C, SiO ₂ + Al ₂ O ₃ may be 75% or more. Further, in the glass C, SiO ₂ is 70~75%, _Al 2 _{O 3} is more than 5%, Na ₂ O is more than 8%, MgO is _{5~12%, SiO 2 + Al 2} O 3 is 77 to 83% It may be.

  Moreover, in this glass C, when it does not contain CaO or contains CaO, the content may be less than 1%.

Moreover, in this glass C, when one or more components of CaO, SrO, BaO and ZrO ₂ are contained, the total content of these four components may be less than 1.5%.

  According to the glass C, it is possible to sufficiently improve the strength by the chemical strengthening method, and it is possible to suppress the generation (extension) of cracks starting from an indentation that occurs when the glass after chemical strengthening is used.

  In a chemically strengthened glass plate obtained by chemically strengthening glass C, the surface compressive stress S is preferably 550 MPa or more, and typically 1200 MPa or less.

  In the chemically strengthened glass plate formed by chemically strengthening the glass C, the compressive stress layer thickness t is preferably more than 10 μm, and typically 70 μm or less.

  The chemically strengthened glass plate formed by chemically strengthening the glass C is preferably one that does not break even when a force of 5 kgf = 49 N is applied with a Vickers indenter of a Vickers hardness meter. It is more preferable that the material does not break even when a force of 7 kgf is applied, and it is particularly preferable that the material does not break even if a force of 10 kgf is applied.

  The glass transition point Tg of the glass C is preferably 400 ° C. or higher. If it is less than 400 ° C., the surface compressive stress is relaxed during ion exchange, and there is a possibility that sufficient stress cannot be obtained.

The temperature T _{2 at} which the viscosity of the glass C becomes 10 ² dPa · s is preferably 1750 ° C. or lower.

The temperature T _{4 at} which the viscosity of the glass C becomes 10 ⁴ dPa · s is preferably 1350 ° C. or lower.

  The specific gravity ρ of the glass C is preferably 2.50 or less.

  The Young's modulus E of the glass C is preferably 70 GPa or more. If it is less than 70 GPa, the crack resistance and breaking strength of the glass may be insufficient. The Young's modulus of the chemically strengthened glass plate formed by chemically strengthening the glass C is substantially the same as the Young's modulus E of the glass C before chemical strengthening because the compressive stress layer thickness t is sufficiently small.

  The Poisson's ratio σ of the glass C is preferably 0.25 or less. If it exceeds 0.25, the crack resistance of the glass may be insufficient.

  Next, the composition of the glass C will be described using the mole percentage display content unless otherwise specified.

SiO ₂ is a component constituting the skeleton of glass and essential. Moreover, it is a component which reduces generation | occurrence | production of the crack when a glass surface is damaged. If it is less than 68%, the stability, weather resistance and chipping resistance of the glass are lowered. Preferably it is 70% or more. If SiO ₂ exceeds 80%, the viscosity of the glass increases and the meltability decreases. Preferably it is 75% or less.

Al ₂ O ₃ is a component that improves ion exchange performance and chipping resistance and is essential. If it is less than 4%, the desired surface compressive stress value and stress layer depth cannot be obtained by ion exchange. Preferably it is 4.5% or more, More preferably, it is 5% or more. If it exceeds 10%, the viscosity of the glass becomes high and uniform melting becomes difficult.

The total _SiO 2 + _Al 2 _{O 3} content of SiO ₂ and _Al 2 _{O 3} is 85% increases the viscosity of the glass at high temperatures, it is difficult to melt. Preferably it is 83% or less. _Further, it is preferable that SiO 2 + _Al 2 _{O 3} is 75% or more. If it is less than 75%, the crack resistance when an indentation is made decreases. More preferably, it is 77% or more.

Na ₂ O is a component that forms a compressive stress layer by ion exchange and improves the meltability of the glass, and is essential. If it is less than 5%, it becomes difficult to form a desired compressive stress layer by ion exchange. Preferably it is 8% or more. When Na ₂ O exceeds 15%, the weather resistance decreases. In addition, cracks are likely to occur from the indentation.

K ₂ O is not essential, but may be contained up to 1% in order to increase the ion exchange rate. If it exceeds 1%, cracks tend to occur from the indentation.

  MgO is a component that may lower the ion exchange rate, but it is an essential component that suppresses the generation of cracks and improves the meltability. If it is less than 4%, the viscosity increases and the meltability decreases. Preferably it is 5% or more. If it exceeds 15%, the glass tends to be devitrified. Preferably it is 12% or less.

ZrO ₂ is not essential, but may be contained in a range of up to 1% in order to reduce the viscosity at high temperature or to increase the surface compressive stress. If it exceeds 1%, there is a possibility that the possibility of cracking from the indentation increases.

  Glass C consists essentially of the components described above, but may contain other components as long as the effects of glass C are not impaired. When such components are contained, the total content of these components is preferably 5% or less, and typically 3% or less. Hereinafter, the other components will be described as an example.

  ZnO may be contained up to 2%, for example, in order to improve the melting property of the glass at high temperature, but it is preferably 1% or less. In the case of producing by the float process, etc., it is preferably 0.5% or less. If it exceeds 0.5%, it may be reduced during float molding, resulting in a product defect. Typically no ZnO is contained.

B ₂ O ₃ may be contained, for example, in a range of less than 1% in order to improve the melting property at high temperature or the glass strength. If it is 1% or more, it is difficult to obtain a homogeneous glass, which may make it difficult to mold the glass, or the chipping resistance may be lowered. Typically no B ₂ O ₃ is contained.

Since TiO ₂ coexists with Fe ions present in the glass, the visible light transmittance is lowered and the glass may be colored brown, so even if it is contained, it is preferably 1% or less. Does not contain.

Li ₂ O is a component that lowers the strain point and facilitates stress relaxation, and as a result makes it impossible to obtain a stable compressive stress layer. Therefore, it is preferably not contained, and even if it is contained, its content is It is preferably less than 1%, more preferably 0.05% or less, particularly preferably less than 0.01%.

In addition, Li ₂ O may be eluted in a molten salt such as KNO ₃ during chemical strengthening treatment, but when the chemical strengthening treatment is performed using a molten salt containing Li, the surface compressive stress is remarkably reduced. That is, the inventors have found that 0.005% by weight _KNO 3, Li containing no Li, 0.01 wt%, 450 ° C. The glass of the infra materials Example 76 using KNO ₃ containing 0.04 wt% When the chemical strengthening treatment was performed under conditions of 6 hours, it was found that the surface compressive stress was remarkably reduced only when the molten salt contained 0.005% by mass of Li. Therefore, it is preferable not to contain Li ₂ O from this viewpoint.

  CaO may be contained in a range of less than 1% in order to improve the meltability at high temperature or to prevent devitrification. If it is 1% or more, the ion exchange rate or the resistance to cracking is lowered. Typically no CaO is contained.

  SrO may be contained as necessary, but since the effect of lowering the ion exchange rate is greater than that of MgO and CaO, the content is preferably less than 1% even when contained. Typically no SrO is contained.

  Since BaO has the greatest effect of reducing the ion exchange rate among alkaline earth metal oxides, BaO should not be contained, or even if contained, its content should be less than 1%. preferable.

  When SrO or BaO is contained, the total content thereof is preferably 1% or less, more preferably less than 0.3%.

When one or more of CaO, SrO, BaO and ZrO ₂ are contained, the total content of these four components is preferably less than 1.5%. If it is 1.5% or more, the ion exchange rate may decrease. Typically 1% or less.

As a fining agent for melting the glass, SO ₃ , chloride, fluoride and the like may be appropriately contained. However, in order to improve the image quality, it is preferable to reduce as much as possible components such as Fe ₂ O ₃ , NiO, and Cr ₂ O ₃ that have absorption in the visible region as impurities in the raw material, and 0.15 by mass percentage each. % Or less, more preferably 0.05% or less.

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

(Cover glass plate material)
(Material Examples 1 to 57)
Material Examples 1 to 57 relate to the glass B. The glass of material examples 1 to 37 satisfies the composition of the glass B, and the glasses of material examples 38 to 57 deviate from the composition of the glass B.

For example materials 1～17,19～35,38～47, so that the composition shown in the column of SiO ₂ of Table 1-6 to ZrO ₂ (or Li ₂ O or TiO ₂₎ in mole percentage display, oxide Generally used glass materials such as materials, hydroxides, carbonates, nitrates, etc. are appropriately selected and weighed to 400 g as glass, and are not shown in the above composition, but 0.4 in terms of SO ₃ It mixed about what added the sodium sulfate equivalent to the mass%. Next, it was put into a platinum crucible, put into a resistance heating electric furnace at 1600 ° C., melted for 3 hours, defoamed and homogenized, poured into a mold material, and slowly cooled at a predetermined temperature to obtain a glass block. . The glass block was cut and ground to a size of 40 mm × 40 mm and a thickness of 0.8 mm, and finally both surfaces were processed into mirror surfaces to obtain plate-like glass.

In the table, “R ₂ O—Al” is obtained by subtracting the content of Al ₂ O ₃ from R ₂ O, and “Na + 1.7K” is a content of Na ₂ O and K ₂ O of 1.7. The mass percentage display compositions corresponding to the mole percentage display compositions in Tables 1-6 are shown in Tables 7-12.

  In addition, the material examples 18, 36, 37, and 48 to 57 are those in which such melting is not performed, and the material example 47 is an example of soda lime silica glass prepared separately.

These glasses were subjected to the following chemical strengthening treatment. That is, these glasses were immersed in 450 ° C. KNO ₃ molten salt for 6 hours, respectively, and subjected to chemical strengthening treatment. For each glass, the surface compressive stress S (unit: MPa) and the thickness t (unit: μm) of the compressive stress layer were measured with a surface stress meter FSM-6000 manufactured by Orihara Seisakusho. The results are shown in the corresponding columns of Tables 1-6. As is apparent from the table, S using the glass B is 300 MPa or more and 1024 MPa or less, and t is 45 μm or more, indicating that a desired compressive stress layer is formed.

  In addition, S and t of material examples 18, 36, 37, and 48 to 57 were obtained from the composition by calculation.

In addition, regarding the material examples 5, 40, and 47, the glass transition point Tg (unit: ° C), the temperature T ₂ (unit: ° C) at which the viscosity becomes 10 ² dPa · s, and the temperature T at which the viscosity becomes 10 ⁴ dPa · s. ₄ (unit: ° C.), specific gravity ρ, and average thermal expansion coefficient α (unit: 10 ⁻⁷ / ° C.) were measured. Further, Tg, T ₂ , T ₄ , and α were measured for material examples 19 and 20, and Tg and α were measured for material examples 24 to 26. The results are shown in the corresponding column of the table. In addition, about the other material example, these values were calculated | required by calculation from the composition. The results are shown in the table.

Moreover, about the material examples 1, 4-10, 15-17, 19-35, 40, 43-47, the test regarding devitrification was done as follows. That is, devitrification in the glass is subjected to one of the test occurs when holding the glass for 15 hours at a temperature T _4. ○ in the column of “D” in the table indicates that devitrification did not occur in the above test, and x indicates that devitrification occurred. Moreover, even if devitrification occurs at temperature T _{4, the case} where devitrification did not occur at (T ₄ + 40 ° C.) is indicated by Δ.

About the material examples 19-35, the test regarding sulfate decomposition was performed as follows. That is, the amount of SO ₃ remaining in the glass was measured at 1350 ° C. and 1500 ° C., and the difference Δ was calculated (unit: mass%). In order to reduce bubbles in the glass, Δ is preferably 0.08% by mass or more. About the material examples 36 and 48-57, (DELTA) estimated value from a composition is shown. Here, the Δ estimated value of 0.4 to 0.9 mass% is described as “0.08” in the table. The Young's modulus is not described in the table, but it can be sufficiently estimated from the composition.

（材料例５８〜８２）
材料例５８〜８２は、上記ガラスＣに関するものである。材料例５８〜７５のガラスは、上記ガラスＣの組成を満足するものであって、材料例７６〜８２のガラスは、上記ガラスＣの組成から外れるものである。

(Material examples 58 to 82)
Material examples 58 to 82 relate to the glass C. The glasses of material examples 58 to 75 satisfy the composition of the glass C, and the glasses of material examples 76 to 82 deviate from the composition of the glass C.

For example materials 58～73,76～79,81,82, so that the composition shown in column mole percentage display from SiO ₂ of Table 13 to 15 up to _{K 2} O, oxides, hydroxides, carbonates Or the glass raw material generally used, such as nitrate, was selected suitably, and it measured so that it might become 400g as glass. This weighed product was mixed with a sodium sulfate having a mass corresponding to 0.2% of the mass. Next, the mixed raw materials were put into a platinum crucible, put into a resistance heating electric furnace at 1650 ° C., melted for 5 hours, defoamed and homogenized. The obtained molten glass was poured into a mold material, held at a temperature of Tg + 50 ° C. for 1 hour, and then cooled to room temperature at a rate of 0.5 ° C./min to obtain a glass block. This glass block was cut and ground, and finally both surfaces were processed into mirror surfaces to obtain a plate-like glass having a size of 30 mm × 30 mm and a thickness of 1.0 mm.

  Moreover, the material example 80 of Table 15 is the soda lime glass prepared separately, and about the material examples 74 and 75 of Table 14, the above-mentioned glass melting etc. are not performed.

  For reference, Tables 16 to 18 show the mass percentage display compositions of the glass materials of Material Examples 58 to 82, respectively.

The glass transition point Tg of the glass (unit: ° C.), temperature _{T 2} at which the viscosity becomes ¹⁰ 2 dPa · s (unit: ° C.), the temperature _{T 4} at which the viscosity becomes ¹⁰ 4 dPa · s (unit: ° C.), a specific gravity ρ, average thermal expansion coefficient α (unit: × 10 ⁻⁷ / ° C.) at 50 to 350 ° C., Young's modulus E (unit: GPa), Poisson's ratio σ, crack occurrence rate P ₀ (unit:%) when not strengthened Is shown in the table. The data indicated by “*” in the table is calculated or estimated from the composition.

P ₀ is the crack generation rate when a load of 500 gf was applied using a Vickers hardness meter, and was measured as follows.

  The plate-like glass was ground by 300 to 1000 μm using a # 1000 grindstone and then polished using cerium oxide to make the surface a mirror surface. Next, in order to remove the processing distortion of the mirror-finished surface, the temperature is raised to a temperature of Tg + 50 ° C. under atmospheric pressure in a resistance heating type electric furnace, held at that temperature for 1 hour, and then 0.5 ° C. to room temperature. The temperature was lowered at a rate of / min. The temperature increase was performed at a temperature increase rate such that the time to reach Tg was 1 hour.

The crack generation rate was measured using the sample which performed the above process. That is, a 10-point Vickers indenter was driven with a load of a Vickers hardness meter of 500 g under the conditions of a temperature of 20 to 28 ° C. and a dew point of −30 ° C. in an air atmosphere, and the number of cracks generated at the four corners of the indentation was measured. The crack generation rate P ₀ (unit:%) was obtained by dividing the number of generated cracks by the number of cracks that can be generated 40 and indicating the percentage.

It is preferable that the glass crack occurrence rate P ₀ when unstrengthened is low. Glass materials Examples 58-75 are not what P ₀ is more than 50%, it can be seen that the cracking hardly occurs even when unreinforced.

Next, the following chemical strengthening process was performed about the plate-like glass of material examples 58-73 and 76-82. That is, these glasses were each immersed in 400 ° C. KNO ₃ molten salt for 8 hours to perform chemical strengthening treatment. The KNO ₃ molten salt has a KNO ₃ content of 99.7 to 100% and a NaNO ₃ content of 0 to 0.3%.

  About each glass after a chemical strengthening process, the surface compressive stress S (unit: MPa) and the compressive-stress layer depth t (unit: micrometer) were measured with Orihara Seisakusho Co., Ltd. surface stress meter FSM-6000. The results are shown in the corresponding column of the table.

Further, for each of the 20 sheet glasses after the above-described chemical strengthening treatment of the material examples 58, 65, and 80 to 82, the Vickers hardness tester Vickers under the conditions of atmospheric pressure, temperature 20 to 28 ° C., humidity 40 to 60%. The indenter was driven at 5 kgf, that is, 49 N, and the number of fractures starting from it was divided by the number of measured 20 and expressed as a percentage, which was designated as the fracture rate P ₁ (unit:%).

Whereas _{P 1} without material example glass at 58,65 at all destruction of 0%, the glass material examples 80 to 82 had destroyed all is _{P 1} is 100%. That is, it can be seen that the glass C has a low risk of breaking even if there is an indentation.

Moreover, regarding the glass of material examples 58, 65, and 80 to 82, glass having a 4 mm × 10 mm × 1 mmt shape with a 4 mm × 10 mm surface mirror-finished and the other surfaces processed to a # 1000 finish was prepared. These glasses were subjected to chemical strengthening treatment at 425 to 450 ° C. using potassium nitrate molten salt (KNO ₃ : 98 to 99.8%, NaNO ₃ : 0.2 to 2%). The surface compressive stress S and the compressive stress layer depth t are 757 MPa and 55 μm for the material example 58, 878 MPa and 52 μm for the material example 65, 607 MPa and 15 μm for the material example 80, 790 MPa and 49 μm for the material example 81, and 830 MPa and 59 μm.

  A Vickers indenter was driven at a load of 10 kgf using a Vickers hardness meter at the center of the 4 mm × 10 mm surface of the glass after these chemical strengthening treatments to form indentations. Although the glass of material examples 80-82 broke at the time of indentation formation, material examples 58 and 65 did not break.

  Using the samples of Material Examples 58 and 65 with the indentation of 10 kgf, a three-point bending test was performed with a span of 30 mm. The bending strength average value (unit: MPa) at n = 20 is shown in the column F in Table 13. The glass of the material examples 58 and 65, which is chemically strengthened even with indentation, is extremely high at 400 MPa or more. The fracture stress was shown.

（実施例１）
実施例１では、図３に示すディスプレイ装置１０Ａを製造する。なお、実施例１では、カバーガラス板３０上に機能膜４０を設けていない。

Example 1
In the first embodiment, the display device 10A illustrated in FIG. 3 is manufactured. In Example 1, the functional film 40 is not provided on the cover glass plate 30.

(Display panel)
A liquid crystal panel is manufactured as a display panel. First, as a glass substrate for a liquid crystal panel, two non-alkali glass substrates (Asahi Glass Co., Ltd., AN100) are prepared. On one alkali-free glass substrate, a transparent electrode and a thin film transistor (TFT) are formed in a predetermined order to produce a TFT substrate. In addition, a transparent electrode and a color filter (CF) are formed in a predetermined order on the other alkali-free glass substrate to produce a CF substrate. Thereafter, the TFT substrate and the CF substrate are bonded to each other through a spacer, and a liquid crystal material to be a liquid crystal layer is sealed in the gap to manufacture a liquid crystal panel. The diagonal length on the display side of the liquid crystal panel is 37 inches.

(Cover glass plate)
As the cover glass plate, a chemically strengthened glass plate (thickness 1.1 mm, diagonal length 40 inches) is prepared. The chemically strengthened glass plate is obtained by chemically strengthening a glass plate having the same composition as that of Material Example 19 shown in Table 2 in a 100 mass% potassium nitrate melt heated to 450 ° C. for 6 hours. The Young's modulus of this chemically strengthened glass plate is 78 GPa.

(Display device)
The display panel and the cover glass plate are fixed using an adhesive. As the adhesive, a thermosetting adhesive is used. In this way, a liquid crystal display (LCD) device is manufactured.

  As an evaluation of the LCD device, the flatness of the cover glass plate is measured when the LCD device is turned off. As a result, the cover glass plate has a sufficiently high Young's modulus and good flatness (1.0 mm or less) (JIS B0021).

(Example 2)
In Example 2, an LCD device is manufactured in the same manner as in Example 1 except that the type of chemically strengthened glass plate is changed as the cover glass plate.

  As the chemically strengthened glass plate of Example 2, a glass plate having the same composition as that of the material example 65 shown in Table 13 and chemically strengthened in a 100% by mass potassium nitrate melt maintained at 450 ° C. for 10 hours is used. The Young's modulus of this chemically strengthened glass plate is 73 GPa.

  As an evaluation of the LCD device, the flatness of the cover glass plate is measured when the LCD device is turned off. As a result, since the cover glass plate has a sufficiently high Young's modulus, it has good flatness (1.0 mm or less).

(Comparative Example 1)
In Comparative Example 1, an LCD device is manufactured in the same manner as in Example 1 except that a glass (Pyrex (registered trademark)) plate is used as the cover glass plate.

  The Young's modulus of the glass of Comparative Example 1 is 68 GPa.

  As an evaluation of the LCD device, the flatness of the cover glass plate is measured when the LCD device is turned off. As a result, it can be seen that the cover glass plate has a Young's modulus and good flatness cannot be obtained.

  From the results of Examples and Comparative Examples, among the glasses described in Table 1 to Table 18, those having a Young's modulus of 70 GPa or more can obtain good flatness, and those having less than 70 GPa cannot be obtained. Guessed.

DESCRIPTION OF SYMBOLS 10 Display apparatus 20 Display panel 30 Cover glass plate 40 Functional film 50 Decorating layer

Claims (2)

In a display device comprising a display panel and a cover glass plate installed in front of the display panel,
It said cover glass plate, 32 inch or larger diagonal length, 1.5 mm thick or less, and, have a higher Young's modulus 70 GPa, provided a compressive stress layer on at least a portion of the surface layer by chemical strengthening treatment chemical A tempered glass plate,
The chemical strengthening treatment before the cover glass plate, a mole percentage based on oxides, SiO ₂ 50 to 74%, the _{Al 2 O 3 1~10%, 6~14} % of Na _{2 O, K} 2 O 3-15%, MgO 2-15%, CaO 0-10%, ZrO ₂ 0-5%, the total content of SiO ₂ and Al ₂ O ₃ is 75% or less, Na ₂ O and _{K 2} O total _Na 2 O + _{K 2} O content of 12-25%, the sum MgO + CaO content of MgO and CaO is characterized in that 7 to 15% display device. In a display device comprising a display panel and a cover glass plate installed in front of the display panel,
It said cover glass plate, 32 inch or larger diagonal length, 1.5 mm thick or less, and, have a higher Young's modulus 70 GPa, provided a compressive stress layer on at least a portion of the surface layer by chemical strengthening treatment chemical A tempered glass plate,
The chemical strengthening treatment before the cover glass plate, a mole percentage based on oxides, SiO ₂ 68 to 80%, the _{Al 2 O 3 4~10%, 5~15} % of Na _{2 O, K} 2 O 0 to 1%, MgO 4 to 15%, ZrO ₂ 0 to 1%, and the total content of SiO ₂ and Al ₂ O ₃ SiO ₂ + Al ₂ O ₃ is 85% or less A display device.

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