Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
  • G01N21/958—Inspecting transparent materials or objects, e.g. windscreens
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
  • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
  • B07C5/34—Sorting according to other particular properties
  • B07C5/3416—Sorting according to other particular properties according to radiation transmissivity, e.g. for light, x-rays, particle radiation
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
  • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
  • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
  • C03C3/087—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal containing calcium oxide, e.g. common sheet or container glass
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
  • G01N2021/9513—Liquid crystal panels

Definitions

• the present invention relates to a flat panel display glazing used as a component of a flat panel display.
• the flat panel display device With the progress of various display methods such as liquid crystal and plasma, the flat panel display device has rapidly improved its image quality and enlarged its display screen. For this reason, in the course of such technological innovation, various improvements and improvements have been made to the flat glass constituting the flat panel display, and higher demands have been demanded. What is important as technology related to flat glass for flat panel displays is the improvement of glass materials required to realize functions as electronic components, and the improvement of appearance quality, which greatly affects the performance of flat panel displays. It is. Although the glass material and appearance quality depend on each other, the appearance quality of plate glass in particular requires the observation of moving images and high-definition images through the light-transmitting surface, which requires high product quality. Was.
• a typical TFT glass sheet used for liquid crystal applications must have such a quality that scratches and stains on its surface are not recognized by visual inspection under 10,000 lux illumination.
• high quality is often required for the surface accuracy of the glass sheet, such as warpage and undulation.
• Patent Document 1 Japanese Patent Application Laid-Open No. 2000-127009
• Patent Document 2 JP 2003-137591A
• Patent Document 3 JP 2004-91244 A
• a liquid crystal display using a TFT thin film transistor
• various thin film layers of amorphous silicon, an insulator, a semiconductor, etc. are formed on a thin non-alkali glass substrate and subjected to pattern processing.
• Process also called TFT array process or substrate process
• display electrodes and wiring for driving LCDs and liquid crystal
• panel process for aligning and laminating a TFT substrate and a color filter substrate, and injecting liquid crystal into the gap.
• the module process also called the mounting process
• integrated semiconductor circuits such as drive ICs are connected to the periphery of the panel to provide a backlight, is also required.
• the TFT array process is similar to various manufacturing processes using a silicon single crystal used as a substrate material of an LSI.
• a silicon single crystal used as a substrate material of an LSI the quality required for a sheet glass, which is required for a silicon single crystal used as a base material in a semiconductor mass production process.
• the decisive difference between the flat glass for display and the silicon single crystal substrate is the difference in their external dimensions, that is, the difference in volume, which overcomes the problems such as charging phenomena that occur based on this difference.
• various physical functions are added, the surface accuracy and cleanliness are improved, and the energy required to clear the required quality of various internal defects is enormous. And require excessive action.
• a flat glass for a flat panel display which has sufficient functions and performance for practical use as a flat glass used for various flat panel display devices and has a good yield, and a selection thereof. It is an object to provide a method and a manufacturing method.
• the method for selecting flat glass for a flat panel display of the present invention is a method for inspecting internal defects of a glass sheet having a light-transmitting surface and selecting good or bad, wherein the maximum size of the internal defects is 30 m or more. And the maximum depth or maximum height of the translucent surface of the partial area of the transmissive surface corresponding to the position of the internal defect exceeds 0.1 m as a defective product, and the other types of glass are selected as non-defective products. It is characterized by doing.
• Internal defects of the sheet glass include unmelted residual raw materials generated when the glass is melted at a high temperature and production, metals such as platinum generated from a furnace wall of a refractory vessel in which the molten glass stays, refractory materials, and the like. Insoluble foreign substances or gases generated from raw materials in vitrification reaction There is a glass having a heterogeneous composition called a bubble, a knot, a stria, or the like caused by the foam.
• “internal defects” do not include surface damage such as cracks, chips, scratches, and the like existing on the surface and end face of the sheet glass. That is, the “internal defect” referred to in this specification means only a defect existing inside the glass sheet.
• the present inventor has conducted long-term research on flat glass used for flat panel displays. As a result, the present inventors have found that internal defects that can be clearly identified when the flat glass is mounted on a flat panel display, which is an image display device, are not found. Has come to realize that it is like blocking the pixels of a flat panel display. Such an internal defect becomes a problem if it does not completely block one pixel but has an effect of greatly reducing the luminance of that pixel. However, excluding such cases, internal defects would not reduce product performance. In some cases, such internal defects cannot be recognized by simple visual inspection in the state of the glass sheet.
• the internal defect of the plate glass has a maximum dimension of 30 ⁇ m or more, and the internal defect blocks a plurality of pixels, the internal defect itself has the same refractive index and transmittance as the glass. If it can be considered or if the pixel is not blocked, it will not be recognized as an internal defect. And in that case, it is not recognized even by the visual inspection in the state of the sheet glass.
• inspection may be performed by detecting light scattered by internal defects using an edge light, and thus light beams from various directions are used.
• the inspection is performed by mistake, it is likely that an excessive inspection is performed, and even if the internal defect does not originally lower the performance of the product, it may be regarded as a defective product.
• the quality is judged by the selection method of the present invention, for example, by performing an inspection using transmitted light, the evaluation is performed in a state close to the original use condition of the product, and the product performance is not reduced. It becomes possible to adopt only things.
• the internal defect itself transmits visible light, it is the interface between the internal defect and the glass that blocks the light, and only the interface that is recognized as having a curved shape when viewed from the side of the sheet glass light-transmitting surface.
• the size of the internal defect in the plate glass selected as a defective product is 30 m or more.
• the light beam goes behind the internal defect due to diffraction phenomena around the internal defect or the like, and the internal defect itself cannot be confirmed.
• a flat glass having a light-transmitting surface has an internal defect with a maximum dimension of 30 m or more and corresponds to the position of the internal defect (the A portion of the light-transmitting surface (closest to the internal defect) is a convex glass plate having a maximum height of more than 0 .: m with respect to the light-transmitting surface, or with respect to the light-transmitting surface.
• a glass sheet with a concave shape with a maximum depth exceeding 0.1 m is judged as a defective product, and other glass sheets are selected as non-defective products.
• the sorting method varies depending on the size and use of the sheet glass, and preferably, the transmissivity corresponding to the position of an internal defect having a maximum size of 80 ⁇ m or more (closest to the internal defect) for one sheet of glass. If the partial surface area is closest to the internal defect with respect to the light-transmitting surface, and the irregularity on the surface of the sheet glass exceeds ⁇ 0.1 ⁇ m with respect to the light-transmitting surface of the sheet glass, it is regarded as defective. In a single sheet of glass, a part of the light-transmitting surface corresponding to the position of an internal defect having a maximum dimension of 100 m or more (closest to the internal defect) is more preferably selected.
• the surface is closest to the internal defect, and the surface of the glass sheet with irregularities exceeding ⁇ 0.08 m with respect to the light-transmitting surface of the glass sheet is to be selected as defective.
• the area of the light-transmitting surface corresponding to the position of the internal defect with a maximum dimension of 150 m or more (closest to the internal defect) in one sheet of glass is the surface of the sheet glass closest to the internal defect with respect to the light-transmitting surface About the unevenness of the sheet glass It is to select those having a size exceeding ⁇ 0.05 m with respect to the light-transmitting surface as defective, and most preferably, correspond to the position of internal defects with a maximum size of 180 / zm or more for one sheet of glass ( A part of the light-transmitting surface (closest to the internal defect) is closest to the internal defect with respect to the light-transmitting surface, and the irregularities on the surface of the sheet glass exceed ⁇ 0.03 m with respect to the light-transmitting surface of the sheet glass.
• the method for selecting flat glass for a flat panel display is a method for inspecting internal defects of a flat glass having a light-transmitting surface and selecting good or bad, wherein the maximum size of the internal defects is 30 or less. m or more, and a partial area of the light-transmitting surface corresponding to the position of the internal defect
• the sheet glass whose distance to the internal defect is less than 0.01 ⁇ m is selected as defective, and the other sheet glass is selected as non-defective It is characterized by doing.
• the distance to the partial area of the light transmitting surface corresponding to the position of the internal defect to the internal defect is defined as the force of the partial area of the light transmitting surface closest to the internal defect. It means the shortest distance (vertical shortest distance) to go to a vertical direction and reach an internal defect!
• the vertical shortest distance from the partial area of the light-transmitting surface to the internal defect is affected by the properties of the internal defect existing in the sheet glass, the composition of the sheet glass, the method of forming the sheet glass, and the like.
• the longer the vertical minimum distance the smaller the effect on the surface shape of the translucent surface partial area. Therefore, the vertical shortest distance as a criterion for selecting defective products is preferably less than 0.03 m, more preferably less than 0.05 m, more preferably less than 0.07 ⁇ m, and most preferably less than 0.07 ⁇ m. Less than 09 m.
• the flat glass for flat panel displays of the present invention has a light-transmitting surface, has internal defects, has a maximum size of 30 m or more, and corresponds to the position of the internal defects.
• the maximum depth or the maximum height of the partial region of the light transmitting surface with respect to the light transmitting surface is 0.1 m or less.
• the upper limit value of the maximum size of the internal defect is determined by the size of the flat glass, and the upper limit value is defined as the rectangular light transmitting surface of the flat glass.
• the side dimension that is, up to 90% of the length of the short side of the transmission surface of the sheet glass. If there is an internal defect with a length exceeding 90% of the short side edge size, there is a risk that the strength of the glass sheet will be problematic even if the refractive index and transmittance are not a problem optically. Is unfavorably high.
• the internal defect is, for example, a bubble, that is, a bubble containing some gas or a vacuum bubble containing no gas.
• the types of gas include oxygen, carbon dioxide, carbon monoxide, Knox (NO), nitrogen, chlorine, and bromo.
• the component at the time of bubble generation may precipitate as a solid on the inner wall of the bubble in some state.
• the foam forming the internal defect has a foam surface shape close to a spherical shape with little variation in radius of curvature, a foam shape extending in one direction, and a foam surface shape extending in one direction.
• the cross section perpendicular to the extension direction is flat, and various forms are available.
• the magnitude of the curvature of the outer surface of the bubble overlapping the adjacent pixel is smaller than the state in which the outer surface position of the bubble having the same small curvature overlaps the adjacent pixel. From such a point of view, it is more preferable that the foam surface is different from the spherical surface shape, and it is preferable that the foam surface has a shape elongated in one direction rather than a spherical shape.
• the internal defects include, for example, solid foreign matter.
• Solid foreign substances as internal defects have a shielding property that is not transparent to visible light like bubbles.
• those which do not have permeability such as fine foreign substances such as refractories and platinum and residual foreign substances of glass raw materials are applicable.
• the flat glass for flat panel displays of the present invention preferably has a light-transmitting surface on both surfaces, and the light-transmitting surface preferably has a total area of 20 ⁇ 10 5 mm 2 or more on both surfaces. In a more preferred form, one of the light-transmitting surfaces has an area of 10 ⁇ 10 5 mm 2 or more.
• a sheet glass having such an area a sheet glass having vertical and horizontal dimensions of a light-transmitting surface, for example, 1000 mm ⁇ 1200 mm, 1100 mm ⁇ 1250 mm, 1370 mm ⁇ 1670 mm, 1500 mm ⁇ 1800 mm is applicable.
• the thickness of the sheet glass is preferably 0.7 mm or less.
• the flat glass sheet for flat panel display of the present invention is, for example, produced by dividing the parent glass sheet into two or more pieces.
• the parent glass is also referred to as a base plate, a mother glass, a base material, or the like.
• the dimensions of the parent glass are not particularly limited. Further, there is no particular limitation on the dimensions, types, and the like of the display device that is manufactured by the single sheet of parent glass. Thus, a single parent glass may produce display devices with different dimensions, and also produce display devices with the same dimensions.
• the flat panel display glass sheet of the present invention is suitable for a liquid crystal display device.
• the liquid crystal can be used regardless of the type of nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, etc. It can be used regardless of differences between STN and TFT etc.
• the flat glass for flat panel displays of the present invention is also suitable for TFT display devices.
• a TFT display device is a liquid crystal display using a thin film transistor (Thin Film Transistor) method, and a TFT display device using amorphous Si, even if it uses polycrystalline Si as a semiconductor material. Any can be used.
• Thin Film Transistor Thin Film Transistor
• the flat glass for flat panel display of the present invention may be made of an inorganic or organic EL device. Also suitable for playing.
• an inorganic or organic EL display is obtained by depositing an inorganic or organic substance that emits light when a voltage is applied on a glass substrate, and applying a voltage capable of causing such a light-emitting body to emit light. This is a display that can emit light when a low voltage is applied.
• Inorganic EL displays include those using a luminous body such as zinc sulfate, and inorganic EL displays include those using a luminous body such as diamines.
• the flat glass for a flat panel display of the present invention is also suitable for field emission displays.
• the field emission display is based on the principle that the display principle of the display is such that microelectrodes are arranged in a grid on a glass substrate in the same number as the number of pixels, and each of the microelectrodes is arranged from the plane electron emission source (emitter one). mm away the phosphor on the glass substrate which is disposed opposite to direction Ke fired electronic, planar by the same principle as CRT (CRTs) which emits light by emitted electrons collide with the phosphor A display device.
• CTRs CRTs
• the flat glass for flat panel display in this application transmits information such as an image among two flat glasses used for the field emission display, and when assembled as a field emission display, the flat glass for the device is used. It is intended for the flat glass constituting the front surface. Also, due to the nature of the display, the dimensions of the pixels, and the like, the maximum size of the internal defect is the maximum depth or the maximum height of the partial transparent surface corresponding to the position of the internal defect, with respect to the transparent surface. Is not less than 100 ⁇ m, preferably not less than 150 ⁇ m, more preferably not less than 180 m, as long as the condition of not more than 0.1 m is satisfied. Preferably it may be 300 ⁇ m or more.
• the flat glass for flat panel displays of the present invention has a light-transmitting surface, has internal defects, has a maximum size of 30 m or more, and corresponds to the position of the internal defects. It is characterized in that the distance from a part of the light transmitting surface to the internal defect is 0.01 ⁇ m or more.
• the “distance of” is the shortest distance (vertical shortest distance) from the part of the light-transmitting surface closest to the internal defect to the internal defect in the direction perpendicular to the light-transmitting surface.
• the upper limit of the vertical shortest distance and the upper limit of the maximum dimension of the internal defect in the thickness direction are determined by the thickness of the glass sheet.
• the shortest vertical distance is preferably 50% or less of the sheet thickness, and the maximum dimension of the internal defect in the sheet thickness direction is preferably 30% or less of the sheet thickness.
• the maximum thickness of the internal defect in the thickness direction exceeds 30% of the thickness, the mechanical strength of the glass sheet is likely to be affected.
• the maximum dimension of the internal defect in the thickness direction is preferably 25% or less of the thickness, more preferably 20% or less, still more preferably 18% or less, and most preferably 15% or less. It is to be.
• the flat glass sheet glass for a flat panel display of the present invention is, for example, manufactured by dividing the parent glass sheet into two or more pieces.
• the parent glass is also referred to as a base plate, a mother glass, a base material, or the like.
• the flat glass for flat panel displays of the present invention has a wavelength of 450 ⁇ ! It preferably has a linear internal transmittance of 90% or more with respect to visible light of up to 650 nm.
• the wavelength of 400 ⁇ ! U desirably having a linear internal transmittance of 90% or more for visible light of up to 800 nm. This is a display that uses light from an external light source such as a liquid crystal display S-backlight, and has a low light use efficiency.
• the linear internal transmittance can be measured, for example, by cutting a plate glass into a measurable rectangular shape of 20 mm square to obtain a sample piece, and placing a thin-film reference glass (a flat plate for measurement) on the reference side of the double beam spectrophotometer.
• a thin-film reference glass a flat plate for measurement
• the thickness of the l ⁇ 5mm square plate including the area where the internal defect exists in the above-mentioned test piece has a wavelength of 450. It can be obtained by measuring at a scanning speed of 0.3 nmZsec using light in the range of 400 mn to 800 mn.
• the plate glass used as the sample is such that its light transmitting surface is coated with a thin film or the like.
• the flat glass for flat panel displays of the present invention has an SiO 1 content of 95% by mass or less
• the flat glass for flat panel displays of the present invention is preferably non-alkali glass.
• the alkali-free glass is one in which elements such as sodium, potassium and lithium, which are alkali metal elements in the glass composition, are 0.1% by mass or less in terms of an oxidized substance.
• the flat glass for flat panel displays according to the present invention can adopt the glass composition required for its application.For example, in a TFT liquid crystal display that drives pixels with thin film transistors (TFTs), it is contained in the glass. There is a danger that the alkali component will impair the function of the liquid crystal display, and the desired function can be realized by using a composition that does not contain an alkali metal element as the composition of the sheet glass, that is, a non-alkali glass composition.
• the flat glass for flat panel displays of the present invention preferably contains an alkaline earth element in an amount of 5% by mass or more in terms of an oxidized substance. Further, the content of the alkaline earth metal element is preferably not lower than the content of alumina by 10% by mass or more.
• the chemical durability of the glass can be maintained, and thus, for example, various chemicals such as acid, hydrofluoric acid, and alkali used in a process of manufacturing a liquid crystal display can be used. This makes it possible to use a glass material that is highly durable and hard to cause problems even when used in a high-humidity environment for a long time.
• the flat glass for flat panel displays of the present invention contains 0.1% by mass of AsO.
• % Is preferably contained. This is environmentally necessary, and is important in the processing environment such as the use environment and reuse of sheet glass.
• the flat glass for flat panel displays of the present invention has a low content of transition metal oxides such as Fe 2 O and O in the glass composition in order to achieve high transmittance.
• the content of the transition metal oxide is preferably 500 ppm or less, more preferably 300 ppm or less, and further preferably 200 ppm or less.
• the flat glass for flat panel display of the present invention is preferably lightweight, its density is preferably 2.6 gZcm 3 or less. Then, if attention for deformation against the external force, it is preferable the value obtained by dividing the Young's modulus in density is 28GPaZg'cm_ 3 or more.
• the flat glass sheet for a flat panel display of the present invention is preferably produced by a stretch molding method.
• the stretch molding method means that when a molten glass in a high-temperature state is molded by a desired molding method, a stretching force is applied to the glass via a heat-resistant device such as a roll to obtain a predetermined surface accuracy, This is a method for realizing the plate thickness and the plate area.
• the stretch molding method include a slot downdraw molding method, an overflow downdraw molding method, a rollout molding method, and a float molding method.
• the method for producing a flat glass sheet glass for a flat panel display includes a molding step of forming a molten glass sheet into a plate shape by a stretch molding method to obtain a parent glass sheet having a light-transmitting surface; Including an inspection process to inspect and a cutting process to cut the parent glass that has been inspected for internal defects to obtain two or more sheets of glass, the inspection process has a maximum internal defect size of 30 m or more, If a defective part whose maximum depth or maximum height with respect to the light-transmitting surface of the partial area of the light-transmitting surface corresponding to the position of the defect exceeds 0.1 m, the parent plate glass is removed so that the defective part is excluded in the cutting process. Is cut.
• the stretch forming method in the forming step performs hot forming by applying elongating force to the molten glass in a high-temperature state, and has a desired thickness and a required function.
• This is a method of forming into a sheet glass shape that can realize
• the inspection process should be performed using, for example, an apparatus equipped with an electronic device capable of recording information such as the size of the internal defect as digital information, which also has a function of mapping the position of the internal defect in the sheet glass.
• it can be executed by adopting an analog method by utilizing a visual inspection or the like by a manufacturing expert.
• the inspection step may be performed on the sheet glass during the forming step, or may be performed on the sheet glass cooled to room temperature after the forming step.
• the maximum size of the internal defect is 30 m or more, and the position of the internal defect is determined. If a defective part whose maximum depth or maximum height of the corresponding light transmitting surface partial area with respect to the light transmitting surface exceeds 0.1 m is detected in the inspection process, based on the information obtained from this inspection process power, This is a step of cutting the parent glass so as to exclude the defective portion.
• the cutting process must be performed in accordance with the area of the glass sheet to be obtained, so that a large number of glass sheets satisfying the required shape and dimensions can be obtained with the least amount of waste, avoiding the parts detected as defective in the inspection process.
• the selection is performed by selecting the plurality of regions as the parent glass glass and cutting the parent glass along the outline of the selected plurality of regions.
• the inspection process may be performed only in the first sheet glass manufacturing process, and the detection information may be used in a subsequent repeated cutting step, or may be performed in accordance with a characteristic characteristic of the sheet glass obtained in the subsequent repeated cutting step. Alternatively, it may be performed each time before the subsequent repetitive cutting step is performed by changing the allowable reference value for the internal defect.
• the cutting method in the cutting step is not particularly limited.
• a method such as mechanical scribing or laser scribing may be employed, or a cutting device equipped with a diamond grindstone or the like, or various cutting machines. May be used. Further, these cutting methods may be used in combination.
• an overflow down draw method can be employed as a stretch forming method in the forming step.
• molten glass overflows from a heat-resistant gutter structure. Then, the overflowed molten glass is stretched and formed below the gutter structure to produce sheet glass.
• the structure and material of the gutter structure are not particularly limited as long as the dimensions and surface accuracy of the sheet glass can be set to a desired state and quality that can be used for flat panel display applications can be realized.
• any method may be used to apply a force to the sheet glass in order to perform downward stretching.
• it is also possible to adopt a method in which a heat-resistant roll having a sufficiently large width is rotated and stretched while being in contact with the sheet glass.
• a method of stretching by contacting only with the substrate may be adopted.
• the inspection for internal defects of the parent glass in the inspection step can be performed by irradiating the parent glass with any one or more of visible light, laser beam, electron beam, and ultrasonic wave.
• the surface light enters and the light exits from the other light-transmitting surface.
• a solid-state imaging device can be used as a light receiving device that receives the emitted or scattered light.
• the inspection process does not prevent the use of other inspection methods. Further, it is preferable that the inspection step is performed at a temperature of the sheet glass of room temperature or higher.
• the position (distribution) of the internal defect may be specified in the plane direction of the sheet glass, or may be specified in both the plane direction and the sheet thickness direction.
• a different determination method may be adopted between the method and the position determination method in the thickness direction.
• the present invention it is possible to provide a flat glass for flat panel displays that has practically sufficient functions and performance as a flat glass used for various flat panel display devices and has a high yield.
• FIG. 1 shows the appearance of the flat glass sheet glass for a flat panel display of the present embodiment.
• FIG. 2 is an enlarged view of the vicinity of the light transmitting surface of the sheet glass.
• the flat glass 1 for flat panel display of the present embodiment has a translucent surface 2 of 1370 mm ⁇ 1670 mm, has a rectangular appearance with a thickness of 0.7 mm, and a flat glass 1 with a warp of 300 mm.
• the waviness which is 0.45 mm or less relative to the dimensions, and which is recognized as irregularities with a period of 5 mm to 20 mm or less is less than 0.2 m, and the in-plane thickness tolerance is 0.1 mm or less for the 300 mm measurement length. is there .
• the ridge line 4 is chamfered by 0.2 mm.
• the glass material of this sheet glass 1 is expressed as oxide% in terms of mass%, SiO 60%, Al O 15%, B O 10%
• the content of the alkali component is 0.05% or less in terms of oxide, and the density of this plate glass is 2.49 gZcm 3 . Further, the strain point as the thermal properties of the glass sheet, the temperature corresponding to the 660 ° C, high temperature viscosity 10 2 ⁇ 5 dPa 's is 1570 ° C.
• This glass sheet 1 has one bubble defect K having a maximum dimension L of 120 m as an internal defect, a distance W from the end face 3 of the glass sheet 1 of 20 mm, and a distance of 0.4 mm from one translucent surface 2. At the position of depth H, it exists in such a manner that it extends in the direction parallel to both the end face 3 and the translucent face 2! /
• the gas composition of the foam is 25% by mass of carbon dioxide, 73% by mass of nitrogen and 2% by mass of oxygen.
• the laser measurement device was used to measure the unevenness of the light-transmitting surface part of the area. As a result, it was found that the maximum height T with respect to the light-transmitting surface was 0.01 m, indicating that there was no problem.
• the flat glass 1 is used for liquid crystal applications or inorganic or organic EL display applications.
• a liquid crystal panel manufacturing process is used in a liquid crystal panel manufacturing line.
• the evaluation result was the same as that of the conventional product, and it was found that there was no problem with the display performance of images and the like!
• the plate glass once assembled as a panel is dismantled, and a rectangular shape having a side of 20 mm including the periphery of the portion corresponding to the internal defect is obtained. Plate glass specimens were prepared.
• the wavelength range For the rectangular area of the light-transmitting surface equivalent to 1 to 5 mm square that contains the location of the internal defect in the sample piece, the wavelength range from 450. Onm power to 650. Onm range is referred to as the double beam spectrophotometer reference.
• the measurement was performed using a reference glass with a thickness of 0.7 mm on the side and a scanning speed of 0.3 nm Zsec. This reference glass may reduce the transmittance in the visible region, such as FeO.
• FIG. 3 shows an enlarged view of the vicinity of the light-transmitting surface of a plate glass as a comparative example.
• the sheet glass 10 of the comparative example shown in FIG. 3 is also used for flat panel displays as in the example.
• a depth H of 0.008 m from one translucent surface 2 at a distance W (see Fig. 2) of 40 mm in a direction parallel to both the end surface 3 and the translucent surface 2 Existing.
• a method for selecting and manufacturing a glass sheet 1 as described above will be described.
• a predetermined glass raw material which has been uniformly prepared in advance so as to have the same composition as the glass material of Example 1 is heated to a high temperature to form a glass, and the molten glass is melted.
• the heterogeneous site is made homogeneous using a known homogenizer.
• the molten glass is introduced into a process of continuously forming by an overflow down draw method, which is a type of stretch forming method, and after the molten glass overflows from the fire-resistant gutter structure, the heat-resistant roller is removed.
• the stretch molding is performed downward by a molding device provided.
• mapping of internal defects in the parent glass sheet is performed by using the sensitivity inspection of the expert person, measurement of the foreign material size of the enlarged image by irradiating the glass sheet with visible light, and laser measurement.
• the position of the internal defect in the parent glass and the value of the internal defect size are input to the information terminal of the process management program connected to the LAN.
• the mapping location is obtained by inputting a foreign substance type and a foreign substance size into a monitor preliminarily divided into a grid pattern, thereby specifying the position of the foreign substance. This value is used to determine what kind of cutting will be performed in the next processing step.
• the measurement results obtained when the test was performed were as follows.
• Each of the internal defects shows the characteristics of bubbles, and the measured value is the maximum bubble diameter dimensional force per 15 sheets of glass 1 (1500mm x 1800mm, 0.7mm thick) ⁇
• the number was in the range of 30 from 120 m force, with two small and five large.
• a laser measuring device was used in the same manner as in Example 1 to evaluate the surface properties of the light transmitting surface 2 of the sheet glass 1 nearest to the location where the bubbles existed.
• the bubble position of the light surface 2 that is, the position of the internal defect
• the surface roughness was measured for the light-transmitting surface position at the shortest distance.
• the roughness of the surface of the light-transmitting surface 2 which did not affect the surface roughness was 0.01 ⁇ m to 0.03 ⁇ m.
• the depth, or distance, to the internal defect with respect to the light-transmitting surface is 60% of the total number in the range from 0.0511 to 1.8 m, and the remaining 40% is It existed at a position deeper than 1.8 m. Thus, it has been found that the depth of any of the internal defects does not hinder the flat glass for flat panel displays of the present invention.
• the parent glass which is a base material to which a process control number corresponding to the marking data is given, is precisely cut by scribing and end face cutting based on the information of the marking data in the machining process.
• fifteen flat glass sheets 1 were obtained from one parent glass sheet as a flat glass sheet glass 1 for 20-inch a-Si (amorphous (amorphous) silicon) TFT-LCD.
• the information of the marking data As a result, the number of internal defects in the sheet glass 1 is such that the number of internal defects is evenly distributed among a plurality of sheet glasses 1, and as a result, the number of internal defects existing in one sheet of glass 1 is uneven It became a thing.
• Example 3 In the final step, washing is performed to remove foreign matter and the like, and a plurality of glass sheets 1 are stored in a packing box that can be held in a stacked state in one rack, and transported to a panel assembly manufacturer. Assembled as a 20-inch LCD panel. A panel assembly manufacturer evaluated the liquid crystal display panel manufactured by such a series of processes and found that it was a product that could be used as well as conventional panels.
• Example 3
• a glass material having a composition of not more than 95% by mass of SiO and not less than 5% by mass of Al 2 O that can be used as a front glass plate of the device of the field emission display.
• the thin glass sheet was cut by a method similar to that of Example 2 and evaluated.
• the selection method, manufacturing method, and the results are shown in Section V below.
• Predetermined uniformly mixed glass raw materials are heated to a high temperature in a glass melting tank with a refractory structure to be vitrified, and the inhomogeneous portions in the molten glass are homogenized using a known homogenizing device.
• the molten glass is continuously introduced into a step of forming by a float method using equipment having a heating furnace provided with a tin bath, and stretch-formed by a heat-resistant roller. Thereafter, the formed parent glass is subjected to the same inspection as described above in the inspection process by using a sorting method by a skilled inspector, laser measurement, and the like, and the quality of the glass sheet is determined. The internal defect location is mapped and stored in the information terminal as predetermined data. This value is then used to determine what kind of cutting will be performed in the next processing step.
• the measurement results obtained in such an inspection process were as follows. First the internal gap The presence of bubble defects was recognized as seeding. In addition, the test was performed on a variety of glass sheets for which six field emission display glass sheets were collected from the parent glass sheet.However, the internal defects present in one glass sheet had the maximum bubble diameter size. The number ranged from 300 m to 500 m, with one small and 15 large. For any of the internal defects, the same method as in Example 2 was used to evaluate the surface properties of the light-transmitting surface 2 of the sheet glass 1 in the vicinity of the location where the bubbles existed.
• the unevenness of the surface of the light-transmitting surface 2 was 0.011 ⁇ ⁇ ⁇ 0.04 m.
• the depth to the transmissive surface that is, the distance to this internal defect, is in the range of 0.03 ⁇ m to 2.1 ⁇ m, and 30% of the total number exists. 70% existed at a position deeper than 2 .: L m.
• the parent glass corresponding to the marking data is precision cut by a known predetermined processing method based on the information of the marking data in the processing step, and six field glasses are formed from one parent glass as described above.
• the plate glass for mission display 1 was obtained.
• cutting was performed based on the information of the marking data, and the number of internal defects in the sheet glass 1 was such that the internal defect portions were almost evenly distributed in the plurality of sheet glasses 1.
• washing is performed to remove foreign substances and the like, and a plurality of glass sheets 1 are stored in a packing box that can be stacked and stacked in one rack, and transported to a panel assembly manufacturer. Assembled as a field emission display panel. Panel assembly manufacturers evaluated the field emission display panel manufactured by such a series of processes and found that it was a product that could be used as well as conventional panels.
• the technology relating to the flat glass for flat panel displays of the present invention has a very wide range of application.
• the technology is also applicable to solid-state imaging devices constituting image input devices. Cover glass manufacturing methods and EL display windows It is also possible to apply it to technology.
• the production method of the present invention can be easily applied to a processing technique for heat-resistant sheet glass that can be easily used for image display and sheet glass for radiation shielding use.
• FIG. 1 is a perspective view showing a flat panel display glass sheet according to an example.
• FIG. 2 is an explanatory view showing the vicinity of a light-transmitting surface of a flat panel display glass sheet.
• FIG. 2 (A) is a partial perspective view
• FIG. 2 (B) is a partial cross-sectional view.
• FIG. 3 is a partial cross-sectional view near a light-transmitting surface of a flat panel display glass sheet according to a comparative example.

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