JP2008177081A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device in which breakage of frame glass in a process of sealing a panel can be prevented, and which has high productivity. <P>SOLUTION: In the image display device having a panel structure, wherein the anode substrate in which an image forming member is formed on the front panel glass and the cathode substrate in which a plurality of electron emitting elements are formed on the rear panel glass are faced together via a plurality of spacers and frame glass, and in which the anode substrate and the frame glass are sealed airtightly by glass frit, the thermal expansion coefficient of the frame glass is made smaller than that of the front and rear frame panel glass. The thermal expansion coefficient of the frame glass is made 80 to 96%, preferably 85 to 90% against that of the rear panel glass. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image display device, and more particularly to an image display device suitable for application to a flat panel type image display device having a sealed container inside.

  As an image display device excellent in high luminance and high definition, a liquid crystal display device, a plasma display device, and the like have been put into practical use in place of the conventional color cathode ray tube. In addition, various types of panel type display devices such as an electron emission display device and an organic EL display device characterized by low power consumption have been put into practical use or are in a preparatory stage for practical use, particularly as those capable of achieving high brightness. It is in.

  Patent Document 1, Patent Document 2, Patent Document 3 and the like can be cited as those related to the electron emission display device. This type of display device includes a back panel in which a plurality of electron sources are formed on the inner surface of a first glass substrate, and an anode (on the inner surface of the second glass substrate facing the electron source forming surface of the first glass substrate). Anode) and a front panel on which a phosphor is formed. The front panel and the back panel are arranged opposite to each other with a predetermined interval, and a sealing frame is preferably made of glass at the inner peripheral edge of the first glass substrate constituting the back panel and the second glass substrate constituting the front panel. Are sealed to form a sealed container. This container is also referred to as a vacuum container.

  When a sealed frame is formed by interposing a sealing frame between the first glass substrate constituting the back panel and the second glass substrate constituting the front panel at the inner peripheral edge of the first glass substrate, An adhesive layer (seal frit glass) containing glass as a main component is applied and dried at the adhesive portion between the first glass substrate and the adhesive portion between the sealing frame and the second glass substrate.

Japanese Patent Laid-Open No. 9-283059 JP 2000-21335 A JP-A-8-227872

  In the flat panel type image display device, generally, the thermal expansion coefficients of the front and back panel glasses and the sealing frame (frame glass) are matched. Therefore, in many cases, the same material is used for the panel glass and the frame glass. Further, the sealing portion is bonded with adhesive glass having a low melting point, and is generally bonded using lead glass or the like.

  In the image display device having the above configuration, if the cooling rate at the time of sealing is increased in order to improve mass productivity, or glass other than lead glass is used for sealing to cope with environmental problems, the frame glass is cracked. Is likely to occur. As a result, it becomes difficult to maintain the inside of the panel at a high vacuum, and the manufacturing yield is lowered.

  When this cause was examined, it was found that the frame glass sandwiched between the bonded portions was less likely to cool than the front and back panel glasses during cooling in the sealing step.

  An object of the present invention is to provide an image display device that can prevent the frame glass from being damaged in the sealing step and has high productivity.

  In the present invention, an anode substrate in which an image forming member is formed on a front panel glass and a cathode substrate in which a plurality of electron-emitting devices are formed on a back panel glass are opposed to each other with a plurality of spacers and a frame glass. In an image display device having a panel structure in which a frame glass and a cathode substrate are hermetically sealed with a glass frit, the thermal expansion coefficient of the frame glass is smaller than that of the front and back panel glasses.

  In the present invention, the thermal expansion coefficient of the frame glass is preferably 80 to 96%, more preferably 80 to 96%, particularly 85 to 90% of the thermal expansion coefficient of the panel glass. The cooling rate of the sealing step can be increased as the glass having a smaller thermal expansion coefficient is used for the frame glass.

In the present invention, it is possible to use a Pb-free low-temperature glass frit that does not contain lead in the sealing portion. As the Pb-free low-temperature glass frit, a glass frit containing vanadium oxide as a main component is preferable, and those containing vanadium oxide, phosphorus oxide, antimony oxide, and barium oxide are particularly preferable. A glass frit with a low thermal expansion filler can also be used. In this case, it is preferable to use ceramic powder or high melting point glass powder as the low thermal expansion filler. Examples of suitable low thermal expansion fillers include lead titanate (PbTiO ₃ ), aluminum titanate (Al ₂ TiO ₅ ), and quartz glass (SiO ₂ ).

  The glass frit is preferably formed not only on the front and rear panel glass of the frame glass but also on the inner surface of the panel, the outer surface of the panel, or both. As a result, it is possible to prevent a decrease in the degree of vacuum when the frame glass is cracked and to improve the reliability. In addition, the yield can be improved.

  By making the thermal expansion coefficient of the frame glass smaller than that of the front and back panel glass, it prevents damage to the frame glass and improves mass productivity and yield when using sealed glass other than lead glass. Can do. Further, the reliability of the sealing portion can be ensured, and the reliability and durability of the image display device are improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows the overall structure of an image display device according to the present invention. FIG. 1 (a) is a plan view seen from the front panel glass side, and FIG. 1 (b) is FIG. 1 (a). It is sectional drawing cut | disconnected along the AA line | wire.

  In this display device, a cathode substrate 101 having a thin film electron source formed on a rear panel glass and an anode substrate 102 having a phosphor and an anode formed on a front glass panel are integrated by a sealing glass frame 103 to form a sealed container. This is an electron emission display device. The back glass panel and the front glass panel are arranged to face each other at a predetermined interval. Numerous electron emission sources (cathode, hereinafter also referred to as cathode) are formed on the inner surface of the rear glass panel. A plurality of color phosphors and an anode (anode) which are partitioned from each other by a black matrix film are formed on the facing surface of the front glass panel facing the back glass panel. The front glass panel is light transmissive.

  The cathode substrate 101 and the anode substrate 102 are arranged to face each other with a spacer 104 serving as a spacing member. A seal frit glass 105 is applied as an adhesive layer to the inner peripheral edges of the cathode substrate 101 and the anode substrate 102, fired through the sealing glass frame 103, and fixed to form a sealed container. The inside of the sealed container is evacuated through an exhaust pipe (not shown). The image is formed in the display area AR.

  Hereinafter, a specific example is shown and it demonstrates in detail.

As the panel glass, a high strain point panel glass (plate thickness: 2.8 mm) having a thermal expansion coefficient of 83 × 10 ⁻⁷ / ° C. used in PDP (plasma display panel) was used.

As the sealing glass frit paste, a Pb-based low-temperature glass frit paste containing a low thermal expansion filler having a thermal expansion coefficient of 72 × 10 ⁻⁷ / ° C., also used in PDP, was used. Pb-based low-temperature glass is 80% PbO-14% B ₂ O ₃ -3% SiO ₂ -3% Al ₂ O ₃ based glass containing PbO, B ₂ O ₃ , SiO ₂ and Al ₂ O ₃ %). As the low thermal expansion filler, lead titanate PbTiO ₃ was used.

Six types of glasses shown in the following (1) to (6) were used for the frame glass.
(1) Soda lime glass having a thermal expansion coefficient of 90 × 10 ⁻⁷ / ° C. (2) High strain point glass for PDP having a thermal expansion coefficient of 83 × 10 ⁻⁷ / ° C. (3) Thermal expansion coefficient of 80 × 10 Aluminosilicate glass with ⁻⁷ / ° C. (4) Aluminosilicate glass with a thermal expansion coefficient of 75 × 10 ⁻⁷ / ° C. (5) Aluminoborosilicate glass with a thermal expansion coefficient of 70 × 10 ⁻⁷ / ° C. (6) Thermal expansion A borosilicate glass frame glass rod having a coefficient of 66 × 10 ⁻⁷ / ° C. was produced by the redraw method shown in FIG. The redraw method comprises heating a frame glass rod preform in a drawing furnace, pulling it with a winder, and cutting it into a predetermined length with a cutting machine. In the wire drawing furnace, it was heated to a temperature at which the viscosity of the frame glass rod at the furnace outlet was about 10 ⁶ poise. In addition, the shape dimensions were measured before pulling with a winder, and the drawing speed of the winder was controlled with a dimension feedback system. By this method, rectangular frame glass rods having vertical and horizontal dimensions of 2.80 mm and 6.0 mm were produced.

  The frame glass rods were arranged as shown in FIG. 3A to assemble the frame glass, and the corner portions where the frame glass rods were in contact with each other were bonded by thermal welding. Here, heat welding is employed, but glass having a melting point higher than that of the sealing glass frit may be used for bonding.

  On the upper and lower surfaces of the assembled frame glass, that is, the surface to be bonded to the panel glass, a sealing glass frit is applied by a dispenser method as shown in FIG. 3B, and baked at a temperature of about 450 ° C. A sealing glass frit was formed on the frame glass.

The frame glass on which the sealing glass frit was formed was placed between the anode substrate and the cathode substrate together with a number of spacers, and heated to a temperature of about 430 ° C. to be hermetically sealed. Thereafter, the inside of the panel was evacuated while being heated, and the degree of vacuum inside the panel was set to 10 ⁻⁶ Pa.

  The sealing conditions for the anode substrate and the cathode substrate and the frame glass were all 6 types of frame glass, 430 ° C. and 0.5 hour heating, and the cooling rate in the cooling process after sealing was 1 ° C./min, 3 ° C. / Min and 5 ° C./min. After cooling to 280 ° C., furnace cooling was performed.

  The number of panels produced is 3 for each of the six types of frame glass, for a total of 18.

  FIG. 4 shows the relationship between the panel breakage rate and the thermal expansion coefficient of the frame glass. In the case where the panel was broken, the frame glass was broken except for a part. If the frame glass or the panel glass is broken at the time of sealing, the degree of vacuum cannot be achieved. Therefore, the panel breakage rate can be determined by measuring the degree of vacuum.

  From this example, the following findings were obtained.

  (1) In order to increase the cooling rate and improve the mass production efficiency, it is better to make the thermal expansion coefficient of the frame glass smaller than the thermal expansion coefficient of the panel glass.

(2) The thermal expansion coefficient of the frame glass is preferably 80 × 10 ⁻⁷ / ° C. or less, that is, 96% or less of the panel glass. More preferably, it is 75 × 10 ⁻⁷ / ° C. or less, that is, 90% or less of the panel glass.

(3) Since the sealing glass frit is damaged when the thermal expansion coefficient of the frame glass is too small, it is 66 × 10 ⁻⁷ / ° C. or more, preferably 70 × 10 ⁻⁷ / ° C. or more, that is, 80% or more of the panel glass. Preferably, 85% or more is good.

  In this example, Pb-free low-temperature glass containing vanadium oxide as a main component and containing no Pb in the sealing material was used.

  The same panel glass and frame glass as in Example 1 were used. As the sealing glass frit paste, the following two types of low thermal expansion filler-containing Pb-free V-based low-temperature glass frit pastes were used.

(A) The glass composition is 58% V ₂ O ₅ -22% P ₂ O ₅ -15% Sb ₂ O ₃ -5% BaO (indicated by weight%), and the low thermal expansion filler is aluminum titanate Al ₂ TiO ₅ A glass frit with a filler having a thermal expansion coefficient of 73 × 10 ⁻⁷ / ° C.

(B) a glass composition _{55% V 2 O 5 -23%} P 2 O 5 -12% Sb 2 O 3 -5% BaO-5% TeO 2 ( display wt%), and low thermal expansion filler is silica glass SiO ₂ filled glass frit with a filler having a coefficient of thermal expansion of 65 × 10 ⁻⁷ / ° C.

  The trial manufacture of the panel was performed on the same conditions as Example 1. However, after sealing, the cooling conditions from 430 ° C. to 280 ° C. were set at 2 ° C./min and 5 ° C./min. The number of prototype panels is 24.

  FIG. 5 shows the relationship between the panel breakage rate after sealing and the thermal expansion coefficient of the frame glass. In the case where the panel was damaged, the panel glass was damaged in addition to the panel glass.

  From this example, the following findings were obtained.

(1) The thermal expansion coefficient of the frame glass is 66 to 80 × 10 ⁻⁷ / ° C., preferably 70 to 75 × 10 ⁻⁷ / ° C., that is, 80 to 96%, preferably 85 with respect to the thermal expansion coefficient of the panel glass. ~ 90% is good.

  (2) Pb-free vanadium-based low-temperature glass frit can be applied to the hermetic seal and can comply with the RoHS regulations.

  (3) Since the sealing portion using vanadium glass is uniform glossy black like the black matrix, the ratio of the effective screen area can be increased.

  In the present Example, the evaluation was performed using the frame glass by the redraw method and the frame glass by the cut-out goods from a glass plate.

As the panel glass, a high strain point panel glass (plate thickness: 2.8 mm) having a thermal expansion coefficient of 83 × 10 ⁻⁷ / ° C. used in the PDP was used. As the sealing glass frit paste, a Pb-free vanadium-based low-temperature glass frit paste containing a low thermal expansion filler was used. The sealing glass is 55% V ₂ O ₅ -22% P ₂ O ₅ -14% Sb ₂ O ₃ -5% BaO-4% TeO ₂ based low temperature glass (indicated by weight%) The low thermal expansion filler is quartz glass (SiO 2), and the thermal expansion coefficient of the glass is 67 × 10 ⁻⁷ / ° C.

  The frame glass is the following five types of redraw products and cut products.

(1) A soda lime glass redraw product having a thermal expansion coefficient of 90 × 10 ⁻⁷ / ° C. and a cut-out product (2) A redraw product of the above high strain point glass for PDP having a thermal expansion coefficient of 83 × 10 ⁻⁷ / ° C. Cut-out product (3) Aluminosilicate glass redraw product and cut-out product with a thermal expansion coefficient of 80 × 10 ⁻⁷ / ° C. (4) Aluminosilicate glass redraw product and cut-out product with a thermal expansion coefficient of 75 × 10 ⁻⁷ / ° C. (5) Aluminoborosilicate glass redraw product and cut-out product having a thermal expansion coefficient of 70 × 10 ⁻⁷ / ° C. Panels were prototyped under the same conditions as in Example 1. However, the cooling rate when cooling from 430 ° C. to 280 ° C. after sealing the frame glass was 3 ° C./min. The number of prototype panels is ten.

  FIG. 6 shows the relationship between the panel breakage rate after sealing and the thermal expansion coefficient of the frame glass. All panel breakage was seen in the frame glass.

  As a result of the present example, it was found that the frame glass by the redraw method is more effective than the frame glass by the cutting process because the frame glass breakage rate is small. This seems to be because the frame glass by the redraw method has fewer chips and scratches than the cut out product. Since the frame glass by the redraw method can be produced at a lower cost than the frame glass by the cutting process, the frame glass by the redraw method is preferable from this point.

  In the present embodiment, a method for attaching a sealing glass to the entire frame glass and the effect thereof will be described.

  FIG. 7 shows a method of coating the sealing glass frit on the frame glass rod by the redraw method. The difference from the redraw method shown in FIG. 2 is that a sealing glass frit paste is applied by a die method between a drawing furnace and a winder, and then a frit is fired. That is. The redraw method is advantageous in terms of mass productivity and cost because the entire frame glass can be coated on the frame glass rod production line.

  In addition, the frame glass is sealed by forming the sealing glass frit not only on the bonding surface to be bonded to the anode substrate and the cathode substrate of the frame glass but also on the side surface portion, that is, on the panel inner surface side or the panel outer surface side. Even if it breaks, the sealing glass fills it, preventing panel leaks. Moreover, by forming the sealing glass frit on the panel inner surface side and / or the panel outer surface side of the frame glass having a smaller thermal expansion coefficient than that of the panel glass, the frame glass is hardly broken and the reliability can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows one Example of the image display apparatus of this invention, (a) is the top view seen from front panel glass, (b) is sectional drawing along the AA. It is the figure which showed the manufacturing method of the frame glass rod by the redraw method. It is the figure which showed the assembly method of frame glass, (a) is the perspective view which shows the state which assembled the frame glass and thermally welded the corner part, (b) is the state which formed the sealing glass frit on the surface of the frame glass FIG. It is the figure which showed the relationship between a panel breakage rate and the thermal expansion coefficient of a frame glass about the panel made as an experiment in Example 1. FIG. It is the figure which showed the relationship between the panel breakage rate and the thermal expansion coefficient of frame glass about the panel made as an experiment in Example 2. FIG. It is the figure which showed the relationship between the panel breakage rate and the thermal expansion coefficient of frame glass about the panel made as an experiment in Example 3. It is the figure which showed the method of coating the sealing glass frit to the frame glass rod manufactured by the redraw method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Cathode substrate, 102 ... Anode substrate, 103 ... Sealing glass frame, 104 ... Spacer, 105 ... Sealing glass frit.

Claims (12)

  An anode substrate having an image forming member formed on the front panel glass and a cathode substrate having a plurality of electron-emitting devices formed on the rear panel glass are opposed to each other via a plurality of spacers and a frame glass. And an image display device having a panel structure in which the cathode substrate is sealed with a glass frit, wherein the frame glass has a smaller thermal expansion coefficient than that of the front panel glass and the rear panel glass. apparatus.   The image display device according to claim 1, wherein the front panel glass and the rear panel glass are formed of the same material.   The image display device according to claim 2, wherein a thermal expansion coefficient of the frame glass is 80 to 96% with respect to that of the front panel glass and the rear panel glass.   The image display device according to claim 2, wherein the thermal expansion coefficient of the frame glass is 85 to 96% of that of the front panel glass and the rear panel glass.   The image display device according to claim 2, wherein a thermal expansion coefficient of the frame glass is 85 to 90% with respect to that of the front panel glass and the rear panel glass.   2. The image according to claim 1, wherein the glass frit is formed on at least one of a panel inner surface side and a panel outer surface side in addition to a contact surface between the anode substrate and the cathode substrate of the frame glass. Display device.   2. The image display device according to claim 1, wherein the glass frit is a Pb-free low-temperature glass frit.   The image display device according to claim 1, wherein the glass frit is a Pb-free low-temperature glass frit containing a low thermal expansion filler.   8. The image display device according to claim 7, wherein the Pb-free low-temperature glass frit is glass mainly composed of vanadium oxide.   The image display device according to claim 9, wherein the glass containing vanadium oxide as a main component contains phosphorus oxide, antimony oxide, and barium oxide as other components.   9. The image display device according to claim 8, wherein the low thermal expansion filler is ceramic powder and / or high melting point glass powder.   2. The image display device according to claim 1, wherein the portion sealed by the glass frit is glossy black when observed from the front panel glass.

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