JP2017227753A - Screen substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To create a screen substrate that enables an observer to visually recognize a scene on the back side and a video from a projector and can easily reduce a manufacturing cost.SOLUTION: A screen substrate of the present invention is a screen substrate that receives light projected from a projector and displays a video; the screen substrate is split phase glass and has a total light transmittance in a thickness direction of 20% or more in a visible light region with a wavelength of 380 to 780 nm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a screen substrate that receives light projected from a projector and displays an image.

  Screens for displaying images projected from a projector (for example, a projector) are roughly classified into a rear type and a front type. In the front type screen, light projected from a projector installed on the front surface (observer side) of the screen substrate is diffused on the surface of the image display section of the screen substrate, and the diffused light is displayed as an image. . On the other hand, in the rear type screen, the light projected from the projector installed on the back surface of the screen substrate (the side opposite to the observer through the screen substrate) is transmitted through the image display section of the screen substrate, and the transmitted light is transmitted. It is displayed as a video. Among them, the front type screen is adopted in various facilities such as a movie theater.

  In recent years, there has been a demand for a screen substrate that can visually recognize the scenery on the opposite side (back side) of the screen substrate when no light is projected from the projector. There is also a need for a device capable of simultaneously displaying the scenery behind the screen substrate and the image on the screen substrate when light is projected from the projector. Screen boards that meet these requirements are attracting attention in the field of digital signage. For example, changing the video displayed on the video display unit according to the scenery on the back of the screen board, or displaying a description of the scenery Can do.

Japanese Patent Laid-Open No. 2006-001202

  Patent Document 1 discloses a screen substrate that satisfies the above requirements. This screen substrate has a laminated structure in which a resin substrate provided with an uneven shape and two glass substrates are laminated.

  However, since the concavo-convex structure of the resin substrate is formed by resin molding, it takes time and effort. In addition, it takes time to integrate the resin substrate and the two glass substrates. Therefore, the screen substrate described in Patent Document 1 may cause an increase in manufacturing cost.

  The present invention has been made in view of the above circumstances, and its technical problem is to devise a screen substrate that can visually recognize the backside scenery and the image from the projector and can easily reduce the manufacturing cost.

  As a result of intensive studies, the present inventors have found that the above technical problem can be solved by adopting phase-separated glass and regulating the haze value and total light transmittance of the phase-separated glass within a predetermined range. This is proposed as the present invention. That is, the screen substrate of the present invention is a screen substrate that receives light projected from a projector and displays an image, and the screen substrate is a phase-separated glass and has a wavelength of 380 to 780 nm. The total light transmittance in the thickness direction in the visible light region is 20% or more. Here, the “video” referred to in the present invention may be a moving image whose display content changes as time passes, or may be a still image whose display content does not change over time.

  In the present invention, phase separation glass is used as a screen substrate. Phase-separated glass has better scratch resistance and weather resistance than resin, paper and the like. As a result, even if excessive friction or impact is accidentally applied, the image display unit is hardly damaged, and further, when installed outside the room, contamination due to aging is less likely to occur. Moreover, the phase separation glass can scatter light due to a difference in refractive index between the first phase and the second phase. As a result, since the light projected from the projector diffuses on the glass surface, it is possible to visually recognize the image on the screen substrate.

  The screen substrate of the present invention has a total light transmittance of 20% or more in the thickness direction in a visible light region having a wavelength of 380 to 780 nm. In this way, it is possible to view the scenery on the opposite side (back side) of the screen substrate when no light is projected from the projector. Alternatively, when light is projected from the projector, the scenery behind the screen substrate and the image on the screen substrate can be simultaneously viewed.

  Second, the screen substrate of the present invention is a screen substrate that receives light projected from a projector and displays an image, and the screen substrate is glass, and in a visible light region having a wavelength of 380 to 780 nm. The total light transmittance in the thickness direction is 20% or more, and the Haze value in the thickness direction is 5% or more in a visible light region having a wavelength of 380 to 780 nm. Examples of a method for increasing the Haze value of glass include a method for crystallizing glass and a method for imparting an uneven shape to the glass surface, in addition to a method for phase separation of glass. Examples of a method for imparting an uneven shape to the glass surface include sand blasting, chemical etching treatment, and nanoimprinting.

Third, a screen board of the present invention, glass is a glass composition including, in _mass%, containing _{SiO 2 30~75%, Al 2 O} 3 0~35%, the 2 O 3 0.1 to 50% _B It is preferable to do. If it does in this way, phase separation property and devitrification resistance can be improved.

  Fourth, the screen substrate of the present invention preferably has a glass thickness of 200 μm or less. If it does in this way, flexibility will arise in glass and the freedom degree of the installation place and storage place of a screen will become high.

  Fifth, the multilayer screen of the present invention is a multilayer screen having a plurality of screen substrates, and the plurality of screen substrates is preferably the screen substrate. As described above, the screen substrate of the present invention has an appropriate total light transmittance and a Haze value in the thickness direction in the visible light region. Therefore, the multilayer screen of the present invention can display images on a plurality of screen substrates with a single projector. As a result, the required number of projectors can be reduced.

Sample No. described in Table 2 Measurement data when measuring the total light transmittance in the thickness direction, diffuse transmittance, and Haze value with a spectrophotometer (Shimadzu spectrophotometer UV-2500PC) in the visible light range of wavelength 380 to 780 nm. It is. It is a schematic sectional drawing for demonstrating experiment of the column of [Example 2].

  The screen substrate of the present invention is made of glass. Glass has better scratch resistance and weather resistance than resin, paper and the like. As a result, even if excessive friction or impact is accidentally applied, the image display unit is hardly damaged, and further, when installed outside the room, contamination due to aging is less likely to occur. As a result, a clear image can be displayed over a long period of time.

  The screen substrate of the present invention is preferably composed of phase-separated glass, that is, phase-separated glass. The phase separation glass can scatter light due to a difference in refractive index between the first phase and the second phase. As a result, it becomes possible to diffuse the light projected from the projector on the glass surface. In addition, if the glass surface after being immersed for 1 minute in 0.6 volume% hydrofluoric acid aqueous solution is observed with a field emission scanning electron microscope, the presence or absence of phase separation and the details of each phase can be confirmed.

The phase separation glass has a phase separation structure including at least a first phase and a second phase, and the content of SiO ₂ in the first phase is higher than the content of SiO ₂ in the second phase. is preferably large, and if containing B ₂ O ₃ in the glass composition, the content of the second of B ₂ O ₃ in the phases, it larger than the content of B ₂ O ₃ in the first phase Is preferred. If it does in this way, the refractive index of a 1st phase and a 2nd phase will become easy to differ, and the scattering function of glass can be improved.

  In the glass according to the present invention, the total light transmittance in the visible light region having a wavelength of 380 to 780 nm is preferably 20% or more (desirably 30% or more, 40% or more, particularly 50% or more). If the total light transmittance is too low in the visible light region having a wavelength of 380 to 780 nm, it is difficult for an observer to visually recognize the scenery on the back side of the screen substrate. On the other hand, if the total light transmittance is too high in the visible light region having a wavelength of 380 to 780 nm, the light projected from the projector is transmitted without being diffused on the glass surface, and the intensity of light that can be visually recognized on the screen substrate is increased. It tends to decrease. Therefore, the total light transmittance in the visible light region having a wavelength of 380 to 780 nm is preferably 90% or less (preferably 80% or less, 70% or less, particularly 60% or less).

  In the glass according to the present invention, in the visible light region having a wavelength of 380 to 780 nm, the diffuse transmittance is preferably 10% or more (desirably 20% or more, 30% or more, 40% or more, particularly 50% or more). If the diffuse transmittance is too low in the visible light region with a wavelength of 380 to 780 nm, the light projected from the projector is transmitted without being diffused on the glass surface, and the intensity of light that can be visually recognized on the screen substrate is likely to decrease. Become. On the other hand, if the diffuse transmittance is too high in the visible light region having a wavelength of 380 to 780 nm, it is difficult for an observer to visually recognize the scenery behind the screen substrate. Therefore, the diffuse transmittance is preferably 80% or less (desirably 70% or less, particularly 60% or less) in the visible light region having a wavelength of 380 to 780 nm.

  In the glass according to the present invention, the haze value is 5% or more (preferably 10% or more, 20% or more, 30% or more, 40% or more, particularly 50% or more) in the visible light region having a wavelength of 380 to 780 nm. preferable. If the Haze value is too low in the visible light region of wavelength 380 to 780 nm, the light projected from the projector is transmitted without being diffused on the glass surface, and the intensity of light that can be visually recognized on the screen substrate is likely to decrease. . On the other hand, if the Haze value is too high in the visible light region having a wavelength of 380 to 780 nm, it is difficult for the observer to visually recognize the scenery on the back side of the screen substrate. Therefore, the Haze value is preferably 90% or less (preferably 80% or less, particularly 70% or less) in the visible light region having a wavelength of 380 to 780 nm.

The glasses according to the invention, as a glass composition, in _{mass%, SiO 2 30~75%, Al} 2 O 3 0~35%, preferably contains 2 O 3 0.1~50% _B. Hereinafter, the reason why each component is limited as described above will be described. In addition, in description of the containing range of each component,% display means the mass%.

When the content of SiO ₂ increases, the meltability and moldability tend to decrease, and the refractive index tends to decrease. Therefore, the preferable upper limit range of SiO ₂ is 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, and particularly 48% or less. On the other hand, when the content of SiO ₂ decreases, it becomes difficult to form a glass network structure, and vitrification becomes difficult. Further, the viscosity of the glass is excessively lowered, and it becomes difficult to ensure a high liquid phase viscosity. Therefore, the preferable lower limit range of SiO ₂ is 30% or more, 35% or more, 40% or more, 42% or more, 44% or more, particularly 46% or more.

Al ₂ O ₃ is a component that enhances devitrification resistance. However, if the content of Al ₂ O ₃ is too large, the phase separation is liable to decrease, and the component balance of the glass composition is impaired. Conversely, devitrification resistance tends to decrease. Moreover, acid resistance tends to decrease. Therefore, the preferable upper limit range of Al ₂ O ₃ is 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 12% or less, 10% or less, particularly 9% or less. The range is 0% or more, 0.1% or more, 3% or more, 4% or more, especially 5% or more.

B ₂ O ₃ is a component that enhances phase separation, but if the content of B ₂ O ₃ is too large, the component balance of the glass composition is impaired, and devitrification resistance is likely to decrease. The acid resistance tends to decrease. Therefore, the preferable upper limit range of B ₂ O ₃ is 50% or less, 40% or less, 30% or less, 25% or less, 20% or less, 17% or less, particularly 15% or less. 1% or more, 0.5% or more, 1% or more, 4% or more, 7% or more, 9% or more, 10% or more, 11% or more, particularly 12% or more.

The total amount of SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ , that is, the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is preferably 55 to 80 from the viewpoint of simultaneously improving the refractive index and resistance to devitrification. %, 58-75%, 60-70%, especially 64-68%.

  In addition to the above components, for example, the following components can be introduced.

Li ₂ O, Na ₂ O, and K ₂ O are components that lower the high-temperature viscosity while increasing the phase separation, but the total amount of these components, that is, the content of Li ₂ O + Na ₂ O + K ₂ O is too large. Then, the liquid phase viscosity tends to decrease. Therefore, a suitable upper limit range of Li ₂ O + Na ₂ O + K ₂ O is 30% or less, 20% or less, 10% or less, 5% or less, less than 1%, 0.5% or less, particularly less than 0.1%. And the suitable upper limit of each of Li ₂ O, Na ₂ O and K ₂ O is 30% or less, 20% or less, 10% or less, 5% or less, less than 1%, 0.5% or less, Less than 1%.

  MgO is a component that raises the refractive index and strain point, and is a component that lowers the high-temperature viscosity. However, when MgO is contained in a large amount, the liquidus temperature rises and devitrification resistance decreases, The density may become too high. Therefore, the preferred upper limit range of MgO is 30% or less, 20% or less, 10% or less, 5% or less, particularly less than 1%, and the preferred lower limit range is 0% or more, 0.1% or more, 0.2% % Or more, particularly 0.5% or more.

  CaO is a component that lowers the high-temperature viscosity. However, when the content of CaO increases, the density tends to increase, and the balance of components of the glass composition is impaired, and devitrification resistance tends to decrease. Therefore, the preferable upper limit range of CaO is 30% or less, 20% or less, 10% or less, 8% or less, 5% or less, 3% or less, 2% or less, particularly 1% or less. % Or more, 0.1% or more, particularly 0.5% or more.

  If the SrO content is increased, the refractive index and the density are likely to be increased, and the balance of components of the glass composition is impaired, so that the devitrification resistance is likely to be lowered. Therefore, the preferred upper limit range of SrO is 30% or less, 25% or less, 20% or less, 15% or less, particularly 10% or less, and the preferred lower limit range is 0% or more, 1% or more, 3% or more, 5% or less. % Or more, 7% or more, particularly 8% or more.

  BaO is a component that increases the refractive index of alkaline earth metal oxides without extremely reducing the viscosity of the glass. If the content of BaO increases, the refractive index tends to increase, and if the content of BaO is too large, the density tends to increase, and the balance of the components of the glass composition is impaired, resulting in a decrease in devitrification resistance. It becomes easy. Therefore, the preferable upper limit range of BaO is 40% or less, 30% or less, 26% or less, 24% or less, 22% or less, particularly 20% or less, and the preferable lower limit range is 0% or more, 1% or more, 5 % Or more, 7% or more, 10% or more, 12% or more, 14% or more, particularly 15% or more.

  When the ZnO content increases, the refractive index tends to increase, but the density tends to increase, and the balance of the components of the glass composition is impaired, and the devitrification resistance tends to decrease. Therefore, the preferable upper limit range of ZnO is 20% or less, 10% or less, 7% or less, 5% or less, particularly 4% or less, and the preferable lower limit range is 0% or more, 0.1% or more, 0.5% or less. % Or more, 1% or more, 1.5% or more, particularly 2% or more.

The total content of MgO, CaO, SrO, BaO and ZnO, that is, the content of MgO + CaO + SrO + BaO + ZnO is preferably 15 to 35%, 20 to 34%, 22 to 33%, 24 to 32% from the viewpoint of improving devitrification resistance. In particular, it is 26 to 31%. The mass ratio (SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ) / (MgO + CaO + SrO + BaO + ZnO) is preferably 1.8 to 4.0, 2.0 to 3.2, 2. 1 to 3.0, 2.2 to 2.9, particularly 2.3 to 2.8. Here, “(SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ) / (MgO + CaO + SrO + BaO + ZnO)” is a value obtained by dividing the content of SiO ₂ + Al ₂ O ₃ + B ₂ O _{3 by} the content of MgO + CaO + SrO + BaO + ZnO.

TiO ₂ is a component that increases the refractive index. However, when the content of TiO ₂ increases, the component balance of the glass composition is impaired, and the devitrification resistance is likely to decrease. Therefore, the preferable upper limit range of TiO ₂ is 20% or less, 15% or less, 10% or less, 5% or less, particularly 3% or less, and the preferable lower limit range is 0% or more, 0.001% or more, 0. 01% or more, 0.1% or more, 1% or more, 1.5% or more, particularly 2% or more.

ZrO ₂ is a component that increases the refractive index. However, when the content of ZrO ₂ increases, the component balance of the glass composition is impaired, and the devitrification resistance is likely to decrease. Therefore, the preferable upper limit range of ZrO ₂ is 20% or less, 10% or less, 6% or less, 4% or less, 3% or less, particularly 2% or less, and the preferable lower limit range is 0% or more and 0.001%. Above, 0.01% or more, 0.1% or more, 0.5% or more, particularly 1% or more.

P ₂ O ₅ is a component that improves phase separation. However, when the content of P ₂ O ₅ is increased, the component balance of the glass composition is impaired, and devitrification resistance is likely to be reduced. Therefore, a suitable upper limit range of P ₂ O ₅ is 20% or less, 15% or less, 10% or less, 7% or less, 4% or less, 3% or less, particularly 2.5% or less. It is 0% or more, 0.001% or more, 0.01% or more, 0.1% or more, 0.5% or more, 1% or more, 1.2% or more, particularly 1.4% or more.

La ₂ O ₃ is a component that increases the refractive index. However, when the content of La ₂ O ₃ increases, the density tends to increase, and devitrification resistance and acid resistance easily decrease. Furthermore, the raw material cost is likely to increase. Therefore, a suitable upper limit range of La ₂ O ₃ is 10% or less, 5% or less, 3% or less, 1% or less, 0.5% or less, particularly 0.1% or less.

Nb ₂ O ₅ is a component that increases the refractive index, but as the content of Nb ₂ O ₅ increases, the density tends to increase and the devitrification resistance tends to decrease. Furthermore, the raw material cost is likely to increase. Therefore, the preferable upper limit range of Nb ₂ O ₅ is 10% or less, 5% or less, 3% or less, 1% or less, 0.5% or less, particularly 0.1% or less.

Gd ₂ O ₃ is a component that increases the refractive index. However, if the content of Gd ₂ O ₃ increases, the density becomes too high, or the balance of the glass composition component is lost, resulting in a decrease in devitrification resistance. The high-temperature viscosity is too low, and it becomes difficult to ensure a high liquid phase viscosity. Therefore, a suitable upper limit range of Gd ₂ O ₃ is 10% or less, 5% or less, 3% or less, 1% or less, 0.5% or less, particularly 0.1% or less.

Rare metal oxide is a component that increases the refractive index, but as the content of these components increases, the density and thermal expansion coefficient tend to increase, and devitrification resistance decreases, ensuring high liquid phase viscosity. It becomes difficult to do. Furthermore, the raw material cost is likely to increase. Therefore, a preferable upper limit range of the rare metal oxide is 10% or less, 5% or less, 3% or less, 1% or less, 0.5% or less, particularly 0.1% or less. The “rare metal oxide” as used in the present invention is a rare earth oxide such as La ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , CeO ₂ , Y ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O _5. Point to.

As a fining agent, one or more selected from the group of As ₂ O ₃ , Sb ₂ O ₃ , SnO ₂ , Fe ₂ O ₃ , F, Cl, SO ₃ and CeO ₂ in terms of the following oxides are 0 ~ 3% can be introduced. In particular, SnO ₂ , Fe ₂ O ₃ and CeO ₂ are preferable as the fining agent. On the other hand, it is preferable to refrain from using As ₂ O ₃ and Sb ₂ O ₃ as much as possible from an environmental viewpoint, and the content of each is preferably less than 0.3%, particularly preferably less than 0.1%. Here, “the following oxide conversion” means that an oxide having a valence different from the indicated oxide is handled after being converted to the indicated oxide.

The content of SnO ₂ is preferably 0 to 1%, 0.001 to 1%, particularly 0.01 to 0.5%. The content of Fe ₂ O ₃ is preferably 0.05% or less, 0.04% or less, 0.03% or less, particularly 0.001 to 0.02%. A preferable upper limit range of CeO ₂ is 6% or less, 5% or less, 3% or less, 2% or less, 1% or less, particularly 0.1% or less, and a preferable lower limit range is 0% or more and 0.001%. Above, especially 0.01% or more.

  PbO is a component that lowers the high-temperature viscosity, but it is preferable to refrain from using it as much as possible from an environmental point of view. The PbO content is preferably 0.5% or less, particularly preferably less than 0.1%.

  In addition to the above components, other components may be introduced in a total amount of preferably 10% (desirably 5%, more desirably 2%).

  The glass according to the present invention preferably has the following characteristics.

Refractive index _{n d} is preferably 1.51 or more, 1.52 or more, 1.53 or more, 1.54 or more, particularly 1.55 or more. When the refractive index n _d is too low, when was Bunsho glass, the refractive index difference between the two phases is reduced, the light diffusion property is liable to lower. On the other hand, if the refractive index n _d is too high, since the introduction of the components to improve the devitrification resistance is limited, it is difficult to increase the liquidus viscosity. Therefore, the refractive index _{n d} is preferably 2.30 or less, 2.00 or less, 1.80 or less, 1.70 or less, 1.65 or less, less than 1.63, 1.62 or less, 1.61 or less, 1.60 or less, 1.59 or less, particularly 1.58 or less.

  The strain point is preferably 450 ° C. or higher, 500 ° C. or higher, 550 ° C. or higher, particularly 600 ° C. or higher. The higher the strain point, the easier it is to form a film at a high temperature, and it becomes easier to form a film having high functionality on the glass surface. For example, the higher the film forming temperature of the transparent conductive film, the higher the transparency of the transparent conductive film and the lower the electrical resistance.

The temperature at a high temperature viscosity of 10 ^2.5 dPa · s is preferably 1450 ° C. or lower, 1400 ° C. or lower, 1380 ° C. or lower, particularly 1360 ° C. or lower. If it does in this way, since a meltability will improve, it will become easy to reduce the manufacturing cost of glass.

  The liquidus temperature is preferably 1200 ° C. or lower, 1150 ° C. or lower, 1100 ° C. or lower, particularly 1060 ° C. or lower. If it does in this way, it will become difficult to devitrify glass at the time of shaping | molding, for example, it will become easy to shape | mold in plate shape by the overflow downdraw method, the float glass method, etc.

The liquid phase viscosity is preferably 10 ^3.5 dPa · s or more, 10 ^3.8 dPa · s or more, 10 ^4.0 dPa · s or more, 10 ^4.2 dPa · s or more, 10 ^4.4 dPa · s or more. As described above, it is 10 ^4.6 dPa · s or more, particularly 10 ^4.8 dPa · s or more. When the liquidus viscosity is low, the devitrification resistance is lowered, and it becomes difficult to form a plate by the overflow down draw method, the float method or the like.

The phase separation temperature is preferably 800 ° C. or higher, 850 ° C. or higher, 900 ° C. or higher, 950 ° C. or higher, 1000 ° C. or higher, particularly 1100 ° C. or higher. Moreover, phase separation viscosity is preferably ¹⁰ 9.0 dPa · s or ^{less, 10} 8.0 dPa · s or ^{less, 10} 7.0 dPa · s or less, in particular ¹⁰ 3.5 ^~10 6.0 dPa · s is there. If it does in this way, it will become easy to phase-separate glass by a formation process and / or a slow cooling process, and it will become easy to shape | mold a glass plate which has a phase-separation structure by the overflow downdraw method, the float method, etc. As a result, after forming into a plate shape, a separate heat treatment step for phase separation of the glass becomes unnecessary, and the manufacturing cost of the phase separation glass can be easily reduced. Here, “phase separation temperature” indicates that clear cloudiness is observed when a glass piece is placed in a platinum boat and remelted at 1400 ° C., then the platinum boat is transferred to a temperature gradient furnace and held in the temperature gradient furnace for 30 minutes. Temperature. “Phase separation viscosity” refers to a value obtained by measuring the viscosity of glass at the phase separation temperature by the platinum pulling method.

  The glass according to the present invention is preferably in the form of a plate or a film, and is preferably formed by a downdraw method, particularly an overflow downdraw method. In this way, it is possible to produce a glass plate or glass film that is unpolished and has good surface quality. The reason is that, in the case of the overflow down draw method, the surface to be the surface is not in contact with the bowl-shaped refractory and is molded in a free surface state. In addition to the overflow downdraw method, a slot downdraw method can be employed. If it does in this way, it will become easy to produce a thin glass film. In addition to the above molding method, for example, a redraw method, a float method, a roll-out method, or the like can be employed. In particular, in the float process, a large glass plate can be efficiently formed.

  When glass is phase-separated, it is preferable to phase-separate the glass at the time of molding. However, the glass may be phase-separated by a separate heat treatment step after the glass is molded. If the glass is phase-divided at the time of molding, a separate heat treatment step is unnecessary, and the manufacturing cost of the phase-separated glass can be reduced. On the other hand, when glass is phase-separated by heat treatment after molding, it becomes easy to control the phase-separated state by controlling the heat treatment conditions, and it becomes easy to produce a screen substrate having a desired light diffusibility.

  The glass according to the present invention preferably has a thickness of 200 μm or less, 150 μm or less, 100 μm or less, particularly 50 μm or less. When the thickness is reduced, flexibility can be imparted to the glass. Thereby, when an image is not displayed, the screen substrate can be wound up in a roll shape and stored compactly. Furthermore, the degree of freedom of the installation location of the screen is increased. For example, it is possible to install the screen substrate along the side surface of the columnar column. On the other hand, when the thickness is extremely small, the glass is easily broken. Therefore, the glass according to the present invention preferably has a thickness of 10 μm or more, particularly 30 μm or more.

  The multilayer screen of the present invention is a multilayer screen having a plurality of screen substrates, and the plurality of screen substrates are preferably the screen substrates described above. As described above, the screen substrate of the present invention has an appropriate total light transmittance and a Haze value in the thickness direction in the visible light region. Therefore, the multilayer screen of the present invention can display images on a plurality of screen substrates with a single projector. As a result, the required number of projectors can be reduced. The distance between the plurality of screen substrates is preferably changed as appropriate according to the optical design of the projector.

  Hereinafter, based on an Example, this invention is demonstrated in detail. The following examples are merely illustrative. The present invention is not limited to the following examples.

  Tables 1-3 show sample No. 1 to 32 are shown.

  First, after preparing a glass raw material so that it might become a glass composition as described in a table | surface, the obtained glass batch was supplied to the glass melting furnace, and it melted at 1400 degreeC for 7 hours. Next, the obtained molten glass was poured onto a carbon plate, formed into a plate shape, and then slowly cooled from the strain point to room temperature over 10 hours. Finally, the obtained glass plate was processed as necessary to evaluate various properties.

  The strain point Ps is a value measured by the method described in ASTM C336-71. In addition, heat resistance becomes high, so that the strain point Ps is high.

  The annealing point Ta and the softening point Ts are values measured by the method described in ASTM C338-93.

The temperatures at high temperature viscosities of 10 ^4.0 dPa · s, 10 ^3.0 dPa · s, 10 ^2.5 dPa · s, and 10 ^2.0 dPa · s are values measured by the platinum ball pulling method. In addition, it is excellent in a meltability, so that high temperature viscosity is low.

  The liquidus temperature passes through 30 mesh (500 μm sieve opening), and the glass powder remaining in 50 mesh (300 μm sieve opening) is placed in a platinum boat and held in a temperature gradient furnace for 24 hours, followed by crystal precipitation. Measured temperature. The liquid phase viscosity is a value obtained by measuring the viscosity of glass at the liquid phase temperature by a platinum ball pulling method.

  The phase separation temperature was measured at a temperature at which clear white turbidity was observed when a glass piece was put in a platinum boat and remelted at 1400 ° C., and then the platinum boat was transferred to a temperature gradient furnace and held in the temperature gradient furnace for 30 minutes. Is. The phase separation viscosity is a value obtained by measuring the viscosity of the glass at the phase separation temperature by a platinum ball pulling method.

Refractive index _{n d} is the value of the d-line as determined by the refractive index measuring instrument KPR-2000 manufactured by Shimadzu Corporation. Specifically, first, a rectangular parallelepiped sample of 25 mm × 25 mm × about 3 mm is prepared, and the temperature range from (annealing point Ta + 30 ° C.) to (strain point Ps−50 ° C.) is set at a cooling rate of 0.1 ° C./min. It is a value measured by infiltrating an immersion liquid having a matching refractive index n _d after annealing.

  Sample No. described in the table. The glass plates according to 1 to 32 were heat-treated at 900 ° C. for 1 hour, and then mirror-polished to a thickness of 0.7 mm. Next, in the visible light region with a wavelength of 380 to 780 nm, the total light transmittance in the thickness direction was measured with a spectrophotometer (Spectrophotometer UV-2500PC, manufactured by Shimadzu Corporation). It was.

  In view of the above, sample no. 1-32 have phase separation, and the total light transmittance in the thickness direction after heat treatment (phase separation) is 20% or more. Therefore, sample no. 1 to 32 are considered to be suitably usable as a screen substrate.

  Sample No. described in Table 2 The glass plate according to No. 21 was heat-treated at 900 ° C. for 6 hours, and then mirror-polished to a thickness of 0.7 mm. Next, in the visible light region having a wavelength of 380 to 780 nm, the total light transmittance and diffuse transmittance in the thickness direction were measured with a spectrophotometer (Spectrophotometer UV-2500PC manufactured by Shimadzu Corporation). From both results, the haze value in the thickness direction was determined. The result is shown in FIG. As can be seen from FIG. The glass plate according to No. 21 has good light diffusibility because the Haze value in the thickness direction is 30% or more in the visible light region having a wavelength of 380 to 780 nm, and the total light transmittance in the thickness direction is 20%. That was all. In FIG. 1, the data of total light transmittance and diffuse transmittance partially overlap.

  As shown in FIG. 2, when the two glass plates were arranged in parallel and the light was projected from the projector, an image could be displayed on the surface of each glass plate.

(Comparative example)
As for the crystallized glass plate “N-11” (plate thickness 5.0 mm) manufactured by Nippon Electric Glass Co., Ltd., as shown in FIG. 2, two crystallized glass plates are arranged in parallel, and light is emitted from the projector. As a result of projection, an image could be displayed on the surface of the crystallized glass plate closer to the projector, but an image could not be displayed on the surface of the crystallized glass plate far from the projector. Further, when the total light transmittance of this crystallized glass plate was measured by the same procedure as in [Example 2], the total light transmittance in the thickness direction in the visible light region having a wavelength of 380 to 780 nm was less than 5%. It was.

Claims (5)

  A screen substrate that receives light projected from a projector and displays an image, the screen substrate being a phase-separated glass, and all light rays in the thickness direction in a visible light region having a wavelength of 380 to 780 nm A screen substrate having a transmittance of 20% or more.   A screen substrate that receives light projected from a projector and displays an image, the screen substrate being glass, and a total light transmittance in a thickness direction of 20% or more in a visible light region having a wavelength of 380 to 780 nm And a Haze value in the thickness direction in a visible light region having a wavelength of 380 to 780 nm is 5% or more. The glass contains, as a glass composition, 30% to 75% of SiO _{2, 0 to} 35% of Al ₂ O ₃ , and 0.1 to 50% of B ₂ O ₃ by mass%. A screen substrate according to any one of the above.   The thickness of glass is 200 micrometers or less, The screen substrate in any one of Claims 1-4 characterized by the above-mentioned. A multilayer screen having a plurality of screen substrates,
A multilayer screen, wherein the plurality of screen substrates is the screen substrate according to any one of claims 1 to 4.