WO2007099974A1

WO2007099974A1 - Envelope for field emission display

Info

Publication number: WO2007099974A1
Application number: PCT/JP2007/053686
Authority: WO
Inventors: Tsunehiko Sugawara; Yuichi Kuroki; Mikio Ueki; Hiroshi Kaneko
Original assignee: Asahi Glass Co., Ltd.
Priority date: 2006-03-02
Filing date: 2007-02-27
Publication date: 2007-09-07
Also published as: JPWO2007099974A1

Abstract

This invention provides an envelope for a field emission display (FED) which can realize a weight reduction of an envelope while suppressing relative misregistration between a pixel and an emitter. The envelope can further realize an improvement in electron beam browning resistant properties of a front glass part and an improvement in glass dissolvability and molding properties. The envelope for FED comprises a mixed alkali glass, and satisfies requirements represented by formulae 460 ≤ TSF ≤ 505, 550 ≤ TSR < 600, |αF - αR| ≤ 5 × 10-7, 2.45 ≤ dF ≤ 2.6, dF ≤ dR, and Tη2 ≤ 1500 wherein TSF represents the distortion point of the front glass part, ºC; αF represents the coefficient of linear thermal expansion of the front glass part, /ºC; dF represents density of the front glass part, g/cm3; Tη2 represents the temperature at which the viscosity of glass in the front glass part, ηF, is 102 dPa·s, ºC; TSR represents the distortion point of the backside glass part, ºC; dR represents the density of the backside glass part, g/cm3; and αR represents the coefficient of linear thermal expansion of the backside glass part, /ºC.

Description

Specification

Field emission display envelope

Technical field

The present invention relates to an envelope made of a plurality of glass members used for a field emission display (hereinafter referred to as “FED”) using electron field emission.

Background art

In recent years, as a television broadcasting receiver (hereinafter referred to as “TV”), a television using a cathode ray tube (hereinafter referred to as “CRT”) has been replaced by a liquid crystal display (hereinafter referred to as “LCD”). There is an increasing demand for flat panel displays (flat panel displays; hereinafter referred to as “FPDs”) such as display panels (hereinafter referred to as “PDPs”).

[0003] FEDs are known as FPDs other than the LCD and PDP. Note that a surface-conduction electron-emission display (hereinafter referred to as “SED”) is known as a display similar to the FED.

[0004] FED using the principle of electron emission is characterized by low power consumption compared to PDP, CRT and LCD, high brightness and high definition compared with LCD, etc., and wide viewing angle, making it easy to see Is expected.

[0005] The FED is a phosphor pixel formed on the surface of the front glass part (front substrate), a minute emitter (electron emission source) formed on the surface of the rear glass part (back substrate), or a plurality of them. It has a structure in which the arranged emitter arrays are paired and arranged opposite to each other in a matrix form with a substantially constant distance. And the back glass portion front glass portion, the inside is maintained in a vacuum (10_ ⁴ ~10_ ⁷ Pa) is sealed in a state having a airtight. Many emitters such as Spindt type and carbon nanotube type have been proposed.

[0006] Then, after controlling the electron beam emitted from the emitter in a vacuum with a gate electrode, an anode voltage in the range of several kV to 10 kV is applied to accelerate, and then fluorescence is emitted by irradiation of the accelerated electron beam. The body is excited to emit light and display an image.

[0007] As described above, in the FED, the phosphor applied on the inner surface of the front glass portion is irradiated with a high-speed electron beam, but a part of the electron beam penetrates the phosphor and passes from the glass surface. Deposits inside a few meters deep. As a result, there is a problem in that the electron beam causes browsing on the front glass.

[0008] For this reason, in addition to high optical appearance quality that does not impair image quality, the front glass portion is required to suppress browning due to the electron beam (electron beam browning characteristics). In addition, since an anode voltage of about several kV to 10 kV is applied as described above, high electrical resistance is required for the front glass portion and the rear glass portion so as not to cause voltage breakdown.

[0009] A general FED envelope is composed of a flat front glass portion and a flat rear glass portion facing each other, and a substantially rectangular outer frame forming a side wall. The member is hermetically sealed using a sealing material. In addition, a shallow box structure in which the front glass part and the outer frame are integrated, and a structure in which the rear glass part and the outer frame are integrated have been proposed.

[0010] As a method of forming an emitter or electrode on the back glass part, CVD performed at high temperature is used.

(Chemical Vapor D mark osition) method is used. Examples of the emitter formed by the CVD method include those using carbon nanotubes. In such a process, the back glass portion is repeatedly heated to a temperature of about 500 to 580 ° C. Therefore, it is necessary to prevent thermal deformation, thermal shrinkage and thermal damage of the glass due to the high temperature.

[0011] On the other hand, in the step of forming pixels and electrodes on the surface of the front glass part, heat treatment is performed to thermally decompose the organic solvent used in forming the phosphor. It is about 0 ° C. Further, the front glass part and the rear glass part, or the front glass part and the outer frame are generally sealed at a temperature of 450 ° C or lower. Furthermore, the temperature in the exhaust process after sealing (process in which heat treatment is performed at a temperature at which the surface adsorbed gas can be sufficiently desorbed) ranges from about 300 ° C to 380 ° C.

That is, throughout the entire process, the front glass part is treated at a temperature lower than the maximum temperature in the heat treatment of the back glass part. In other words, when the front glass part and the rear glass part are compared, the rear glass part that is repeatedly heat-treated at a higher temperature causes a larger thermal shrinkage than the front glass part. Therefore, after assembling the envelope by sealing the front glass part on which the pixels are formed and the rear glass part on which the emitters are formed, they face each other due to the difference in thermal shrinkage between the two glasses. The relative positional relationship between the pixel and the emitter Deviation occurs. In the present invention, the term “positional displacement” simply refers to a relative positional displacement between the opposing pixel and the emitter, which is caused by a difference in thermal shrinkage between the front glass portion and the rear glass portion. . As a result of the positional deviation, there is a concern that the electron beam emitted from the emitter collides with a position other than the predetermined pixel, causing a color purity defect and causing a fatal problem in image quality.

[0013] Is the strain point of glass the viscosity of the glass? It is defined as the temperature indicating i-force 10 ¹⁴ · ⁶ dPa 'S. Below the strain point, it is defined as a state in which the glass does not substantially cause viscous flow. That is, when the heat treatment is performed at a high temperature above the strain point of the glass, the heat shrinkage rate of the glass cannot be ignored. For example, glass used in simple matrix LCD and CRT has a strain point that is significantly lower than the heat treatment temperature (500 to 580 ° C) in the CVD method described above, so the shrinkage of the glass after heat treatment is large. It is inappropriate to use it for the back glass part.

[0014] On the other hand, the high strain point glass has an advantage that the amount of heat shrinkage is small as compared with the low strain point glass even after the high temperature treatment as described above. For this reason, the back glass has a strain point in the same temperature range (500 to 580 ° C) as that of the heat treatment temperature in the CVD method, or a slightly higher temperature range (570 to 600 ° C). Some high strain point glass is used. In consideration of heat shrinkage, convenience, and consistency of linear thermal expansion coefficient, the same high strain point glass as that of the back glass has been used for the front glass.

[0015] However, compared with the processing temperature in the emitter forming process in the rear glass part, the processing temperature in the pixel forming process in the front glass part and the subsequent heat treatment process is low, so the heat shrinkage of the front glass part. The rate is relatively small. Therefore, even if a low strain point glass is used as the front glass part, there is a possibility that the difference in heat shrinkage between the front glass part and the rear glass part may fall within the allowable range. It was not done.

[0016] On the other hand, when producing high strain point glass, the melting temperature of glass compared to low strain point glass (the melting temperature of glass generally indicates the viscosity of glass η force Sl0 ² dPa 'S of

F

Defined as temperature. ) Becomes higher. Therefore, not only does the amount of heat required for melting the glass increase, but the reactivity between the glass raw material and the furnace wall of the glass melting furnace increases, and various glass defects are eliminated. Derived and impairs merchantability. In addition, the heat damage of the heat-resistant brick used for the furnace wall of the glass melting furnace becomes severe and there is a problem of shortening the life of the melting furnace.

[0017] In the case of an envelope having a structure in which a front glass part and the outer frame are integrated, the front glass part has a three-dimensional shape like a substantially open box. Therefore, the press molding method is more suitable for the production method of the front glass part than the conventional flat glass production method such as the float method. The press molding method is a method in which several types of molds are used to press and mold a high-temperature glass lump (gob) filled in the mold.

[0018] The press molding method is a method in which the glass is cooled from the start of molding to the end of molding, and the viscosity at the start of molding is generally about 10 ² ' ⁵ to 10 ⁷ dPa' S. The viscosity at the end of molding is about lC ^ l oUdPa'S. That is, the essence of the molding process is to fix the shape of the glass by increasing the viscosity in the process of cooling and solidifying the glass.

[0019] Even when the above-described high strain point glass is used as the front glass portion, the force that needs to be press-molded with an appropriate viscosity is inevitably higher than the low strain point glass. Further, press molding at a higher temperature causes a problem that the surface of the mold is worn and the life is remarkably shortened. Furthermore, there is a problem that the glass and the mold are easily fixed. That is, when manufacturing a glass molding by a press molding method, it is preferable that the strain point of glass is as low as possible. If an attempt is made to increase the strain point without increasing the melting temperature, an appropriate temperature range for the molding operation cannot be set, and the glass composition design becomes extremely difficult.

[0020] As a low strain point glass for a display, as a fluorescent display tube or a simple matrix liquid crystal display, as a soda lime glass, an alkali oxide essentially contains only a sodium oxide. Or, potassium oxide is generally used, but the content of potassium oxide is extremely small compared to the content of sodium oxide.

[0021] In addition, in Japanese Patent Application Laid-Open No. 2002-025761 (Patent Document 1), the front substrate has a strain point of 510 ° C. and contains 13.0% (mass percentage) of sodium oxide as an alkali oxide. An organic EL display using soda lime glass containing 1.0% (mass percentage) of potassium is disclosed. [0022] However, in the FED irradiated with a high-speed electron beam, when the soda lime glass is used, sodium ions in the glass are reduced by the electron beam penetrating into the glass, and the electron beam browning proceeds remarkably in a short time. Problems arise. Soda-lime glass has a low volume resistivity (10 ⁸ · ⁵ Ω 'cm) at 150 ° C, so there is also a problem of inducing dielectric breakdown when used in an FED driven with an anode voltage of several kV or more. In other words, glass that does not or does not exhibit the mixed alkali effect, such as soda lime glass, is suitable for FED.

[0023] In addition to the glass described above, CRT glass exhibiting a mixed alkali effect has been put into practical use. The mixed alkali effect is a phenomenon in which physical properties such as ionic conductivity, dielectric properties, and mechanical properties are greatly changed when alkali ions in a single alkali glass are replaced with other alkaliions. In the case of glass, the characteristic that the mixed alkali effect is most prominent is electrical resistance. In the present invention, a glass containing two or more elements of alkali and exhibiting the above-described mixed strength effect is referred to as mixed alkali glass.

[0024] Glass having a sufficiently enhanced mixed alkali effect is advantageous in that it has a high electric resistance and good electron beam browning characteristics. As the glass (panel glass) used for the image display part (glass panel) of CRT, binary mixed alkali glass containing sodium and potassium is used for direct view type CRT. For projection cathode ray tubes, ternary mixed alkali glass containing sodium, potassium and lithium is used.

[0025] Further, as described above, in order to sufficiently secure the X-ray absorption ability, all the glass for a panel has a high density of about 2 · 7 g / cm ³ to 3 · Og / cm ³ . However, when such high-density glass is used for the front glass, it is difficult to reduce the weight of the FED envelope.

[0026] Further, the composition of the glass for the glass funnel (funnel glass), which is located on the back side of the CRT and on which the electron gun and the deflection yoke coil are mounted, is used for the panel used for the image display portion. Different from glass. Panel glass used in black and white televisions and panel glass used in early color televisions contained lead in the same way as funnel glass to prevent X-ray leakage.

[0027] After that, along with the advent of high-brightness CRT with the anode voltage increased to about 30kV, Further suppression of electron beam browning has been taken up as a technical issue. Also, in the process of sealing the glass panel and glass funnel using crystalline solder glass, the temperature reaches about 440 ° C, causing heat shrinkage and thermal deformation of the glass panel. There was a problem that the spacing between the shadow mask, which is the color selection mechanism to be mounted, fluctuated, resulting in poor color purity.

[0028] For this reason, CRT panel glass does not contain lead at all, which has been used to secure X-ray absorption, as a measure to prevent electron beam browning and thermal deformation. As a result, glass compositions that contain strontium and barium and have a high strain point while ensuring practical X-ray absorption ability have been used. As a result, the strain point of the panel glass is about 470 ° C to 480 ° C, which is about 20 ° C to 40 ° C higher than the strain point of the funnel glass containing lead.

[0029] The CRT bundles thermoelectrons emitted from at most three force swords into an electron beam with an electron gun, scans them with a deflection yoke coil, and accelerates them to generate hundreds of thousands to millions of pixels. The principle of exciting and emitting phosphors is used. That is, there is no need for a structure in which force swords and phosphor pixels are arranged in a matrix like PDP and FED, which are flat light emitting displays. In addition, it differs from the FED manufacturing method in that it does not require a high-temperature treatment process when forming a force sword on the glass funnel corresponding to the back glass part of the FED.

[0030] Therefore, in the case of the CRT, even if there is a relative thermal contraction difference between the glass panel and the glass funnel, the position of the force sword that emits electrons and the pixel that the emitted electrons collide with. There is no concern about color purity deterioration due to misalignment. In other words, in CRT, poor color purity due to the difference in relative heat shrinkage between the glass panel and the glass funnel does not exist as a technical issue, and the high strain point of the glass funnel is taken up as a technical issue. I didn't have to.

[0031] Patent Document 1 discloses an inorganic EL display using soda lime glass for the front substrate and glass having a strain point of 520 ° C or higher for the back substrate. However, the invention according to Patent Document 1 is intended to prevent thermal deformation of the back substrate itself even when baked at 650 to 700 ° C. [0032] That is, it does not provide a specific measure for solving the problems related to the production of the front glass as described above while ensuring the excellent electron beam browning characteristics required for the front glass part for FED. . Furthermore, there is no disclosure or suggestion of the above-mentioned technical issues related to misalignment.

[0033] Therefore, the invention according to Patent Document 1 has practically used a relative positional shift between the opposing pixel and the emitter, which is caused by a difference in thermal shrinkage between the front glass portion and the rear glass portion, which is a problem unique to FED. It does not provide a glass vacuum envelope that ensures good electron beam browning characteristics while keeping it within a certain range. In addition, the invention according to Patent Document 1 improves the solubility of the front glass part, which is a problem in the production technology of an FED envelope, or the moldability of glass required when the front glass part has a three-dimensional shape. It is not intended to disclose any solution to facilitate the enhancement, in addition to improving the system.

Patent Document 1: Japanese Patent Laid-Open No. 2002-025761

Disclosure of the invention

Problems to be solved by the invention

[0035] The present invention provides a practical function as an FED envelope and provides optimum glass properties and glass composition so that glass members constituting the envelope can be easily manufactured. Furthermore, it aims at providing the envelope lightened.

[0036] That is, the present invention aims to solve the following problems imposed on the FED envelope. The first problem is to reduce the above-mentioned “positional deviation” to a practical range. The second issue is to satisfy the electron beam browning characteristics required for FED. The third issue is to improve the melting property of the front glass part and prolong the life of the melting furnace. The fourth problem is to facilitate press molding when the front glass part has a three-dimensional shape. The goal is to provide an FED envelope that is lighter by using these means for solving problems.

Means for solving the problem

In order to achieve the above object, the present invention provides the following solution.

That is, the first invention is an FED envelope having a front glass part for displaying an image and a rear glass part for forming an emitter, wherein the front glass part and the rear glass part are provided. The glass part is made of mixed alkali glass.

SCIENCE FICTION

(° C), linear thermal expansion coefficient _α (/ ° C), density d (g / cm ³ ), glass viscosity 77 force Sl0 ² (dP

F F F

a'S) is T 77 (° C), and the back glass part has a strain point of T

2 S

460≤T ≤50, where (° C), linear thermal expansion coefficient is (/ ° C), and density is d (g / cm ³ )

R R R SF

5, 550≤T 600, 2.45≤d ≤ 2. 6, d ≤d, | α-α | ≤5 Χ 10 " ⁷ , and Ding

SR F F R F R

FED envelope characterized by satisfying η ≤1500.

2

[0039] In addition, according to a second aspect of the present invention, in the envelope described above, the content of the oxide standard of each component constituting the front glass portion is substantially 60≤Si0 ≤73, 0≤ in terms of mass percentage. A1〇

2 2 3

≤2.5, 8≤MgO + CaO≤12, 0. 15≤MgO / CaO≤2.3, 0≤SrO ≤3, 0≤ Ba〇≤3, 0≤ZnO≤6, 0.5.5≤Na〇 ≤4, 4≤K 0≤12, l≤Li〇≤3, 0≤ZrO

2 2 2 2

≤2.5, 0≤TiO ≤2, 0≤CeO ≤1, 0≤Sb〇 ≤0.5.

2 2 2 3

When the total content of alkali oxides Na〇, K〇 and Li〇 is R〇, 11≤R

2 2 2 2

0≤14, 0. 12≤Na〇 / R O≤0.45.

2 2 2

[0040] Further, in the third invention, the content of the alkali metal oxide constituting the front glass portion is substantially 2.0 ≤ 0.21 Na O + O. 065K O + O. 726Li in terms of mass percentage. 0≤2.

2 2 2

Satisfy 8 relationships.

The invention's effect

[0041] The envelope for FED of the present invention is composed of a front glass portion having a low strain point and a rear glass portion having a high strain point, but ensures consistency of expansion coefficients with each other. It's going to Therefore, the “positional deviation” described above can be reduced. At the same time, while satisfying the electron beam browning characteristics required for the FED front glass part, the melting property of the front glass part is improved and the melting temperature is lowered, thereby extending the life of the melting furnace. When the front glass part has a three-dimensional shape, press molding can be facilitated. In addition, a significant weight reduction can be achieved by optimizing the density of the front glass.

Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view of a field emission display envelope showing an embodiment of the present invention.

[Fig. 2] Outline of field emission display envelope showing another embodiment of the present invention. FIG.

Explanation of symbols

[0043] 1: Front glass part

2: Back glass

3: Outer frame

BEST MODE FOR CARRYING OUT THE INVENTION

[0044] Hereinafter, the present invention will be described in detail. 1 and 2 are cross-sectional views of an FED envelope showing a typical embodiment of the present invention. As shown in FIG. 1, an example of an FED envelope according to the present invention includes a front glass portion 1 having phosphor pixels (not shown) formed on the inner surface, and an emitter (not shown) for emitting electrons. And a rear glass portion 2 having a surface arranged on the surface, and a substantially rectangular glass outer frame 3 that forms a side wall. Each member is made of a sealing material. It is hermetically sealed.

[0045] The FED envelope of the present invention may have a structure in which the front glass portion and the outer frame are integrated as shown in FIG. Further, a reinforcing member may be used so as to cover the peripheral portion of the front glass portion and the outer surface of Z or the back glass portion. In addition, a spacer for keeping a constant distance between the force sword and the anode may be interposed inside the envelope.

[0046] Alkali-containing glass is used for the front glass part 1, the back glass part 2 and the outer frame 3 constituting the present invention. When alkali-free glass is used, the melting temperature of the glass becomes high, resulting in a significant reduction in productivity and loss of economy.

[0047] Under the high-voltage and high-current driving conditions applied in FED or the like, the envelope exhibits good dielectric breakdown characteristics. That is, mixed alkali glass is used for all of the front glass part, the back glass part, and the outer frame constituting the envelope of the present invention. Specifically, the front glass part, the rear glass part, and the outer frame constituting the envelope of the present invention use glass having a volume resistivity of 150 Ωcm or more at 150 ° C.

[0048] The front glass part constituting the present invention has good electron beam browning characteristics, and the substance amount ratio of the alkali oxide contained is essentially mixed in terms of the characteristics. It is in a range where the potash effect can be expressed. In other words, the substance amount ratio of the alkali oxide contained in the front glass portion constituting the present invention is excellent in volume resistivity that can ensure high insulation. Therefore, it is limited to the range where both the electron beam anti-browning characteristics are compatible.

[0049] On the other hand, since a good electron beam browning characteristic is not an essential condition for the back glass part, the material amount ratio of the alkali oxide contained in the back glass part is 10 ^η Ω 'as a volume resistivity. It may be in a range indicating cm or more.

[0050] The front glass portion and the back glass portion constituting the present invention have different strain points. Specifically, the front glass part has a strain point of 460 ° C or higher and 505 ° C or lower. When the strain point of the front glass part is less than 460 ° C, there is a problem that the amount of heat contraction becomes large during heat treatment in the sealing process, and that the front glass part is distorted due to thermal deformation. The sealing step refers to a step of sealing the front glass portion and the rear glass portion, or a step of sealing with an outer frame interposed between the front glass portion and the rear glass portion.

[0051] When the strain point of the front glass part exceeds 505 ° C, the melting energy of the glass increases, various glass melting defects increase, the melting temperature of the glass rises, and the melting furnace becomes shorter. Problems that lead to reduced productivity, such as shortening the life of press dies due to higher glass molding temperatures, become serious.

[0052] Further, the rear glass portion constituting the present invention has a strain point of 550 ° C or higher and 600 ° C or lower. When the strain point of the back glass is less than 550 ° C, the amount of thermal shrinkage increases when heat treatment is performed in a high-temperature process such as emitter formation, which impairs practicality. If the strain point of the back glass exceeds 600 ° C, the good solubility of the glass will be impaired.

[0053] The coefficient of linear thermal expansion α of the front glass part and the coefficient of linear thermal expansion of the rear glass part constituting the present invention.

F

The difference I α — α | of the number α is less than 5 X 10_ ⁷ / ° C. This allows thermal expansion and heat

R F R

Consistency during shrinkage is maintained, and thermal cracking (cracking due to thermal expansion and contraction) in a series of heat treatment steps when assembling the FED can be suppressed.

[0054] Further, in order to ensure good solubility and formability, the temperature of the glass at the front glass portion is set to 1500 ° C or lower when the viscosity η of the glass is 10 ² dPa'S.

F

[0055] In the present invention, the density of the front glass portion is 2.45 gZcm ³ or more and 2.6 g / cm ³ or less. When the density of the front glass part is 2.45 g / cm ³ or less, the viscosity of the glass is 10 ² dPa '.

F

It becomes difficult to secure the temperature when S is 1500 ° C. or less, and if the density is 2.6 g / cm ³ or more, the weight cannot be sufficiently reduced. [0056] With respect to the back glass portion, visible light transmittance is not required, so it can be reinforced with a metal member or the like and can be made as thin as possible. Therefore, the density of the back glass part may be larger than that of the front glass part.

[0057] The density of the back glass unit 2. If less than 45 g / cm ³ linear expansion coefficient 75 X 10_ ⁷ / ° C or more on, problems in 90 X 10- ⁷ Z ° C following range (sealing step It is difficult to ensure a strain point of 550 ° C or higher while maintaining the range of the linear expansion coefficient necessary for avoidance and ensuring consistency with the expansion coefficient of other materials.

Next, an embodiment of the composition of the front glass part constituting the envelope of the present invention will be described. The glass used for the front glass is composed of SiO, CaO, MgO, Li0, Na

twenty two

O and Ko are essential ingredients.

twenty two

[0059] The glass composition of the front glass portion in the envelope of the present invention is intended to facilitate lightening of the envelope at a low density. The glass composition of the front glass part makes it easy to adjust the linear thermal expansion coefficient, strain point and other high-temperature viscosities, and at the same time exhibits the mixed alkali effect in terms of electric resistance and electron beam browning characteristics. This is also the purpose.

[0060] Next, each component of the glass composition of the front glass portion will be described. Unless otherwise specified, “%” represents mass percentage.

[0061] SiO is a network former that is important for vitrification.

2

If it is less than 0%, the viscosity of the glass decreases and the chemical durability deteriorates.

If the SiO content is more than 73%, the viscosity of the glass becomes high and melt molding becomes difficult.

2

It becomes difficult. Therefore, the content of SiO is preferably 60 to 73%.

2

[0062] Al O is added to improve water resistance. If the content is more than 2.5%, the glass

twenty three

The viscosity of the mold becomes too high, making melt molding difficult. Therefore, the Al O content is 2.5.

twenty three

% Or less is preferable.

[0063] MgO and CaO are mainly used to adjust the viscosity curve of glass. If the total content of MgO and CaO is less than 8%, the viscosity becomes too high and it becomes difficult to maintain the strain point at 460 ° C or more and 505 ° C or less. If the total content of MgO and CaO exceeds 12%, the glass tends to devitrify and the liquidus temperature rises. In addition, to the CaO content If the MgO content ratio, that is, the MgO / CaO value is less than 0 · 15 or more than 2.3, the glass tends to devitrify. Therefore, the total content of MgO and CaO is preferably 8-12%.

[0064] Both SrO and BaO may be contained to increase the linear thermal expansion coefficient of the glass. However, the content of Sr〇 or Ba〇 is 3. If it exceeds / ₀ , the density of the glass becomes high and the remarkable lightening effect cannot be obtained. In addition, when the content of SrO or BaO is more than 3%, BaO-SrO-SiO-based crystals are likely to precipitate. Therefore, the content of SrO and BaO is

2

Both are preferably 3% or less.

[0065] ZnO is mainly effective in adjusting the viscosity curve of glass and suppressing electron beam browning. However, if the ZnO content is higher than 6%, the glass density increases and the glass tends to devitrify. Therefore, the ZnO content is preferably 6% or less.

[0066] LiO suppresses electron beam browning of the glass and the viscosity of the glass at high temperatures.

2

Is a component that improves the meltability of the glass and increases the coefficient of linear thermal expansion. If the content of Li is less than 1%, the viscosity of the glass at high temperature is too high to melt.

2

If the content of LiO is more than 3.0%, the glass tends to devitrify. Li O raw material

2 2 Because it is expensive, it is preferable to contain a large amount in terms of cost. Therefore, the content of Li 2 O is preferably 1 to 3%.

2

[0067] Na 0 is a component that adjusts the linear thermal expansion coefficient and viscosity of glass, but the content is 0.5%.

2

If it is less, the linear thermal expansion coefficient becomes too low to match the expansion coefficient of the back glass part, and if the NaO content is more than 4%, the viscosity of the glass becomes too low and

2

The shape becomes difficult. Therefore, the NaO content is preferably 0.5-5%.

2

[0068] Κ〇 is a component that adjusts the linear thermal expansion coefficient and viscosity of glass in the same manner as Na O, but contains

twenty two

If the percentage is less than 4%, the viscosity of the glass becomes too high, making melting and forming difficult. If the K ○ content is higher than 12%, the linear thermal expansion coefficient of the glass will increase.

2

Giru. Therefore, it is preferable to set the content of 〇 to 4-12%.

2

Is preferred.

[0069] ZrO has a force content that can be added to adjust the viscosity curve of glass.

2

The surface devitrification temperature increases between the glass and the refractory, and devitrification occurs on the surface. It becomes easy. Further, when the surface devitrification temperature is high, it is not preferable because it becomes difficult to form the glass as in the case where the liquidus temperature inside the glass is high. Therefore, the ZrO content is 2.5.

2

% Or less is preferable.

[0070] Wrinkles include a force that can be added to prevent glass coloring due to ultraviolet rays and X-rays.

2

When the percentage is more than 2%, the X-ray transmittance of the glass is lowered, which is preferable. Therefore, the content of TiO is preferably 2% or less.

2

[0071] CeO is excellent in the effect of preventing the coloring of the glass by X-rays and is used as a clarifier.

2

However, when the content is more than 1%, the glass tends to be devitrified, and the light transmittance of the glass in the visible short wavelength region is lowered. Therefore CeO

The content of 2 is preferably 1% or less.

[0072] SbO is a force that can be added as a glass refining agent. If the content is more than 0.5%,

twenty three

Glass surface devitrification becomes remarkable. Therefore, the SbO content should be 0.5% or less.

twenty three

preferable.

[0073] In the present invention, in addition to the above components, coloring components such as NiO, CoO, and FeO can be added to reduce the transmittance of the glass or adjust the color of the glass. Pb〇 is

3 4 2 3

, It is easy to cause coloring by electron beam and X-ray browning, so it is better not to contain it.

[0074] in a molar percentage display, alkali oxides Na O (mol ^_0/0), KO (mol%) and Li O (Mo

2 2 2%) content R 0 (Na 2 O + K 2 O + Li 2 O) (mol%) is 1 1 mol% or more and

2 2 2 2

Preferably, it is in the range of 14 mol% or less. Wherein RO is 1 mole ^_0/0 or less than 14 mole

2

When percent is, the linear thermal expansion coefficient of front glass portion α in the range of 75 X 10- ^⁷ ~90 X 10- ⁷

F

It becomes difficult to adjust.

[0075] Molar ratio of sodium oxide to total alkali oxide, Na O / R 0 is 0.12 or more

twenty two

It is preferable to be in the range above and below 0.45. Beyond this range, it becomes difficult to develop the desired mixed alkali effect.

[0076] Further, the present invention has been made with the following knowledge about the effect of each alkali oxide to lower the strain point. That is, to lower the strain point, Li O

2 addition is most effective, followed by Na 2 O. Add KO to set the strain point The effect to reduce is the smallest.

[0077] Further, in the above-mentioned range of the appropriate linear thermal expansion coefficient, in terms of mass percentage, it is defined as S = 0.21Na O + O. 065K O + O. 726Π〇 And 2.8

2 2 2

It is preferable to be in the following range. Here, Na 0, K〇 and Li〇 in the above formula are

2 2 2 The mass percentage value of each component shall be expressed. If the value of S is less than 2.0, it becomes difficult to set the strain point T of the glass used for the front glass part to 505 ° C or less.

SCIENCE FICTION

If the value of 2.8 exceeds 2.8, it becomes difficult to make the strain point T above 460 ° C.

SCIENCE FICTION

Example

Hereinafter, the envelope of the present invention will be described in detail based on examples and comparative examples. The envelopes in the examples and comparative examples have a structure in which the front glass part and the outer frame are integrated as shown in FIG. Moreover, the glass composition used for the front glass part and the back glass part in the following Examples and Comparative Examples is prepared by adjusting as follows.

[0079] First, a raw material batch prepared so as to have a predetermined composition was put in a platinum crucible, and the raw material was charged at about 1400 ° C, and then heated to a temperature sufficient to melt and melted for about 4 hours. In order to obtain a homogeneous glass, defoaming was carried out by stirring for 30 minutes using a platinum stirring rod during the temperature rise and fall of the molten glass. Thereafter, the molten glass is formed into a predetermined shape and then slowly cooled. The density, linear thermal expansion coefficient, strain point, viscosity, thermal contraction rate, volume resistivity, electron beam browning amount, etc. of each glass thus obtained were measured. Tables 1 to 3 show the measurement results.

[0080] Measuring methods of the above physical property values are shown below.

[Density] Measured by Archimedes method on a glass mass of about 30 g without bubbles.

[Linear thermal expansion coefficient] Measured according to the method specified in JIS R3102, from 0 ° C to 300

Average coefficient of linear thermal expansion up to ° C.

[Strain point] Measure by the method specified in JIS R3103.

[0081] [Viscosity of Glass in Molten State] Viscosity of front glass part measured by rotating cylinder method

F

The temperature when 0 ² (dPa 'S) is shown, that is, the temperature showing log 77 = 2 is T 77 (° C)

10 F 2

read. Similarly, when the back glass part shows viscosity 77 force Sl0 ² (dPa 'S)

R

, That is, a temperature indicating log 77 = 2 is read as T 77 (° C). [0082] First, the thermal shrinkage rate of each sample is measured by the Vickers indentation method. A method for measuring the heat shrinkage rate will be specifically described.

(1) As a sample, prepare a glass with dimensions of about 100mm x 30mm x 10mm produced by cooling from 600 ° C to room temperature.

(2) Using a hardness tester HMV-2000 manufactured by Shimadzu Corporation, picker indentations are formed on the sample.

(3) Using a Nikon measuring microscope, measure the distance between the indentations before heat treatment.

(4) Heat (heat-treat) the Sampnore at 450 ° C for 1 hour. (This heat treatment condition substantially corresponds to the firing condition for sealing the front glass part and the back glass part.)

(5) Using the microscope, measure the distance between the indentations after heat treatment.

(6) The heat shrinkage rate is calculated by comparing the distance between the impressions before and after the heat treatment.

The heat shrinkage rate of each sample calculated in this way is compared, and if the heat shrinkage rate is about the same as Example 1 (Example) or lower than Example 1 (the amount of heat shrinkage is small) The heat shrinkage characteristics were evaluated by setting “small”, the heat shrinkage rate being higher than that of Example 1, and “large” for (large heat shrinkage).

[0083] [Electron beam browning characteristics] After forming the glass of each sample to be about 10mm X 10mm X thickness 3mm and polishing both sides with optical mirrors, the light transmittance at wavelengths of 400nm to 700nm was measured, Evaporate. Subsequently, an electron beam of 30 kV and 20 / i A / cm ² is irradiated for 300 hours under the condition that the cooling water temperature of the sample stage is 80 ° C. After that, the light transmittance at 400 to 700 degrees is measured again, and the amount of decrease in light transmittance due to electron beam irradiation is compared to evaluate the browning characteristics. Specifically, on the basis of the decrease in light transmittance in Example 4 (Example), if it is the same as that, it is judged as good, if it is clearly lower than that, it is bad, and it is clearly lower than that. Those that did not were considered excellent, and these evaluations were regarded as electron beam browning characteristics.

[0084] Examples according to the first invention (examples:! To 4) and comparative examples (examples 5 to 8) are shown in Table 1, and examples according to the second invention (examples 9 to 10) and Table 2 shows comparative examples (Examples 11 to 13) according to the second invention. The front glass part of Examples 9 and 10 is assembled with the rear glass part shown in Table 3. Together they form an envelope.

[0085] The back glass part that forms the emitter on the surface is assumed to undergo a high-temperature process in the range of 550 ° C force 600 ° C, and heat shrinkage rate and thermal deformation of the back glass part caused by heat treatment High strain point glass with a strain point of 570 ° C was used so that the amount was within the practical range. Table:! To 2ί Sf, 0.21 Na O + O. 065K O + O. 726Li O

2 2 2 Na 0, K Ο and Li 2 O in the above formula represent mass percentages of the respective components.

2 2 2

[0086] [Table 1]

2007/053686

Example A

510 ₂ (% by mass) 57.4

Al ₂ 0 ₃ (mass? 7.0

MgO (mass%) 2.0

CaO (mass%) 5.0

SrO (mass%) 7.0

BaO (mass%) 8.0

ZnO (mass%) 0

Back Na ₂ 0 (mass%) 4.1

Surface K ₂ 0 (mass ¾) 6.3

Ga

La U ₂ 0 (g amount%) 0

The

Part Zr0 ₂ (mass ¾) 3.0

of

0 ₂ (¾%) 0

Ga

La Ce0 ₂ (mass%) 0

The

Pair so ₃ (mass%) 0.1

Completion

Fe ₂ 0 ₃ (mass »0.1

Sb ₂ 0 ₃ (mass ¾) 0

Na ₂ 0 (mol%) 4.59

Κ ₂ 0 (πιοΙ%) 4.64

Li ₂ 0 (mol%) 0.00

R _z 0 (mol%) 9.2

Na ₂ 0 (mol%) / R _z 0 (mol%) 0.5

S 1.27

Back density (g / ciD ³ ) 2.77

Face

Linear thermal expansion coefficient a _R (x10 " ⁷ / ° O 83

La

Strain point T _SR (° C) 570

Part

O ₂ (.C) 1551

object

Heat shrinkage rate (ppm) 25 450 for the front glass part of Example 1 (Example) and Example 2 (Example) in Table 1. CX heat treatment for 1 hour was performed and the heat shrinkage rate was measured. there were. On the other hand, in the case of the front glass part (strain point T = 451 ° C) of Example 5 (comparative example) where the strain point is lower than 460 ° C, thermal shrinkage at a level causing practical problems occurred.

SCIENCE FICTION

[0090] Also, the difference in linear thermal expansion coefficient between the front glass part and the rear glass part I α — α

FRI may break the thermal process that produces the envelope. I hi — hi

Example values of FRI is 5X 10_ ⁷ (/ ° C) less than 1 (Example), Example 2 (Example), Example 3 the envelope Cracking (Example) and Example 4 (Example) The In the case of Example 6 (comparative example) and Example 7 (comparative example) (I hi — hi | = 6X 1

F R

0—So. ^{C 7X 10- 7 / ° C)} , cracks occur in the heat process of manufacturing the envelope.

[0091] The front glass part of Example 8 (Comparative Example) has a high strain point (strain point T> 505 ° C).

SCIENCE FICTION

The front glass part of (Comparative Example) has a high melting temperature (Τ η> 1500 ° C).

2

Since the viscosity is too high at the settable temperature, bubbles in the molten glass cannot be sufficiently removed, and a front glass portion that is satisfactory in quality cannot be obtained.

[0092] The front glass part of Example 11 (Comparative Example) is an example in which the total amount of CaO and MgO is small (CaO + MgO <8%), the melting temperature is high, and (T 77> 1500 ° C). . Example 12 (comparative example) is CaO and Mg.

2

The total amount of O is too large (CaO + MgO> 12%), and the balance of the content of alkali oxides; ^ not suitable, S straight (0.21 Na O + O. 065K O + O. 726Li O) Force / J 、 Sai (S 2

2 2 2

0), the strain point is too high (T> 505 ° C). These comparative glasses are

SCIENCE FICTION

As described above, there is a possibility that a front glass portion that is satisfactory in quality cannot be produced.

[0093] Example 13 (comparative example) has a high alkali oxide content (R 0> 14%) and a large S value.

2

This is an example where the strain point is low (T 460 ° C) due to the threshold (S> 2.8). In this case, heat shrink

SCIENCE FICTION

This is a practical problem due to the large rate.

[0094] Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. is there.

This application is based on a Japanese patent application filed on March 2, 2006 (Japanese Patent Application No. 2006-056322), the contents of which are incorporated herein by reference.

Industrial applicability

[0095] According to the present invention, it is possible to provide an envelope having a practical function for FED applications. it can.

Claims

The scope of the claims

[1] A field emission display envelope having a front glass portion for displaying an image and a rear glass portion for forming an emitter,

The front glass part and the back glass part are made of mixed alkali glass,

The front glass part has a strain point of T (° C), a linear thermal expansion coefficient of H (/ ° C), and a density of d

SF F F

(g / cm ³ ), the temperature when the glass viscosity is 10 ² (dPa'S) is Τ (° C),

2

Strain point of surface glass is T (° C), linear thermal expansion coefficient is a (/ ° C), density is d (g / cm ^£

SR R R

),

460≤T ≤505,

SCIENCE FICTION

550≤T 600,

SR

\ a-

FRI ≤5 X 10 ^{_ 7} ,

2. 45≤d ≤2. 6,

F

d ≤d, and

F R

T? 7 ≤1500,

2

An envelope for field emission display characterized by satisfying

[2] The oxide-based content of each component constituting the front glass portion is substantially expressed in terms of mass percentage.

60≤SiO ≤73,

2

0≤A1 O ≤2.5,

twenty three

8≤MgO + CaO ≤12,

0. 15≤MgO / CaO ≤2.

3,

0≤SrO ≤3,

0≤Ba〇 ≤3,

0≤Zn〇 ≤6, And

When the total content of Na 0, K Ο and Li O is R ○ in mole percentage, 11

2 2 2 2

The fee as claimed in claim 1, satisfying ≤R〇≤14 and 0.12≤Na O / R O ≤0.45.

2 2 2

Envelope for lud emission display.

The content of the alkali metal oxide contained in the front glass portion substantially satisfies the relationship of 2.0≤0.2.21Na O + O.065K O + O.726Li 0≤2.8 in terms of mass percentage.

2 2 2

The envelope for field emission display according to claim 2.