Patent Application
20110127901
1. Field of the Invention
The present invention relates to a display apparatus and more particularly relates to a display apparatus having an airtight container.
2. Description of the Related Art
In display apparatuses, such as a field emission device (FED), a display unit formed of electron-emitting devices, luminous layers, and the like is provided inside an airtight container. In addition, wires are connected to the electron-emitting devices from the outside of the airtight container, and a voltage is applied to the wires, so that the electron-emitting devices are driven. A fluorescent film is bombarded with electrons emitted from the electron-emitting device, and the luminous layer emits light in accordance with an emission current. In order to obtain a stable emission current, the airtight container is required to have high airtightness.
On the other hand, since the airtight container is formed by sealing peripheral portions of a pair of insulating substrates, an abnormal potential distribution may occur in some cases due to charging of the airtight container, a potential applied to the display unit, and/or a current flowing therethrough. In particular, in the vicinities of the peripheral portions of the substrates (sealed portions), an abnormal potential distribution is liable to occur. The abnormal potential distribution as described above may cause abnormal discharge and eventually may lead to damage, such as disconnection of wires, to the display apparatus.
Japanese Patent Laid-Open No. 2004-087474 has disclosed that the potential is set using a conductive adhesion member.
In order to obtain a highly reliable display apparatus, the generation of abnormal discharge is required to be suppressed as well as the airtightness of an airtight container is ensured. Accordingly, the present invention intends to suppress the generation of abnormal discharge as well as to ensure the airtightness of an airtight container.
The present invention which solves the above problems provides a display apparatus comprising: an airtight container which includes an insulating first substrate, an insulating second substrate facing the first substrate, a conductive frame arranged between the first substrate and the second substrate, a conductive layer which is provided between the conductive frame and the first substrate and which is airtightly bonded to the conductive frame, an insulating layer which is provided between the conductive layer and the first substrate and which airtightly bonds between the conductive layer and the first substrate; a display unit provided inside the airtight container; wires which extend from the outside to the inside of the airtight container through between the first substrate and the insulating layer and which are connected to the display unit; and at least one electrode which extends from the outside of the airtight container to at least between the first substrate and the insulating layer. In the display apparatus described above, the insulating layer insulates the wires from the conductive frame and the electrode and has at least one through-hole penetrating from the electrode toward the conductive frame, and the conductive layer is connected to the electrode through the through-hole.
According to the present invention, a highly reliable display apparatus can be obtained in which the generation of abnormal discharge is suppressed as well as high airtightness is ensured.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, with reference to the drawings, an embodiment of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In each drawing, the common members are designated by the same reference numerals.
Reference numeral 5 indicates a sealing portion insulating layer which is a part of the sealing member 300 and which has a frame shape. Reference numeral 6 indicates a through-hole formed in the sealing portion insulating layer 5. Reference numeral 7 indicates a sealing portion conductive layer which is a part of the sealing member 300 and which has a frame shape provided on the sealing portion insulating layer 5. The sealing portion conductive layer 7 is partially present in the through-hole 6.
The sealing portion insulating layer 5 is formed on the first substrate 1 to have a frame shape and is provided so as to intersect and cover parts of the matrix wires 9 and parts of the potential regulating electrodes 8. As a result, the matrix wires 9 extend from the outside of the airtight container to the inside thereof through between the sealing portion insulating layer 5 and the first substrate 1 and are connected to the electron source 10 inside the airtight container. The potential regulating electrodes 8 each extend from the outside of the airtight container to at least between the sealing portion insulating layer 5 and the first substrate 1. The potential regulating electrodes 8 each may extend further to the inside of the airtight container.
As shown in
The sealing member 300 has the structure in which the sealing portion insulating layer 5, the sealing portion conductive layer 7, a conductive frame 23, and an adhesion member 22 sequentially laminated in this order from a first substrate 1 side. The sealing portion insulating layer 5 airtightly bonds between the rear plate 100 and the sealing portion conductive layer 7. The sealing portion conductive layer 7 airtightly bonds between the sealing portion insulating layer 5 and the conductive frame 23. The adhesion member 22 airtightly bonds between the conductive frame 23 and the face plate 200 (the second substrate 21).
The sealing portion insulating layer 5 will be described in detail. As described above, the rear plate 100 includes the first substrate 1, the potential regulating electrodes 8 and the matrix wires 9 (in this case, only the column wires 3 are shown), the latter two being provided on the first substrate 1. In addition, the potential regulating electrodes 8 and the matrix wire 9 are located at least between the conductive frame 23 and the first substrate 1. The sealing portion insulating layer 5 is provided between the matrix wires 9 and a sealing portion conductive member (the conductive frame 23 and the sealing portion conductive layer 7) to insulate therebetween in a Z direction. In order to improve the airtightness of the airtight container, as shown in
Furthermore, according to the present invention, the potential regulating electrode 8 and the conductive frame 23 are connected inside the sealing member 300 and, in more particular, are connected inside the through-hole 6 of the sealing portion insulating layer 5. In addition, the connection between the potential regulating electrode 8 and the conductive frame 23 is performed by the sealing portion conductive layer 7 which is a part of the sealing member 300 and which airtightly bonds between the sealing portion insulating layer 5 and the conductive frame 23. Hence, an additional electrical conduction member for electrical conduction between the potential regulating electrode 8 and the conductive frame 23 is not necessarily provided on the surface of the sealing member 300, that is, on the outside or the inside surface of the airtight container. If the electrical conduction member is provided on the surface of the sealing member 300, sufficient electrical conduction may not be obtained or abnormal discharge may occur by a projection of the electrical conduction member in some cases. In addition, since the connection is performed within the space (through-hole 6) surrounded by the sealing portion insulating layer 5, the airtightness of the sealing member 300 is hardly degraded. Hence, the airtightness of the airtight container can be sufficiently ensured, and excellent display can be performed over a long period of time.
The structure described above may also be applied to a face plate 200 side, that is, may also be applied between the face plate 200 and the conductive frame 23. For example, when an anode wire is provided which extends through between the second substrate 21 and the conductive frame 23 from the outside of the airtight container, which is connected to the anode 26, and which sets the anode 26 at an anode potential, the above structure is preferably used. In this case, a potential regulating electrode is formed on the second substrate 21, and on the second substrate 21, a sealing portion insulating layer is provided so as to cover the anode wire and the potential regulating electrode. The sealing portion insulating layer insulates between the anode wire and the potential regulating electrode and insulates between the anode wire and the conductive frame 23. A through-hole is provided in the sealing portion insulating layer, and the potential regulating electrode on the second substrate 21 and the conductive adhesion member 22 are connected to each other through the through-hole. Accordingly, the electrical conduction between the conductive frame 23 and the potential regulating electrode of the face plate 200 can be obtained. However, a significantly high anode potential is applied to the anode wire as compared to that applied to the matrix wires. Hence, the sealing portion insulating layer at the face plate 200 side is required to have significantly high insulating properties as compared to those required for the sealing portion insulating layer which is provided at a rear plate 100 side. Hence, the thickness of the sealing portion insulating layer at the face plate 200 must be increased. When being provided at the rear plate 100 side, since the sealing portion insulating layer 5 may have a small thickness as compared to that in the case in which the sealing portion insulating layer is provided at the face plate 200 side, preferable electrical conduction can be obtained between the conductive frame 23 and the potential regulating electrode 8. As described above, the anode potential can be applied to the anode 26 through between the second substrate 21 and the conductive frame 23. However, it is preferable when the anode potential is applied to the anode 26 by an anode terminal provided by penetrating the rear plate 100. In this case, the potential regulating electrode 8 may extend inside the airtight container, and the anode terminal may be provided so as to surround the potential regulating electrode 8. Accordingly, the anode terminal can control the potential distribution generated in the interior space by the potential regulating electrode 8. The structure as described above may be seen, for example, in FIG. 5 of Japanese Patent Laid-Open No. 2003-092075.
Heretofore, the example of the display performed by cathode luminescence using the electron-emitting devices 11 (electron source 10) and the screen member 24 is described. In the display apparatus using the electron-emitting devices 11 and the screen member 24, since electron rays and a high anode potential are used, the control of the potential distribution of the whole display apparatus is important. Hence, the present invention can be preferably used. However, the display unit of the present invention is not limited only to that by the cathode luminescence. For example, a display unit by electroluminescence using organic EL elements, such as organic EL display, and a display unit by photoluminescence using gas discharge elements, such as plasma display, may also be used. In the organic electroluminescence display, since having not enough resistance against moisture, the organic EL elements are formed inside an airtight container for moisture protection. In addition, in the plasma display, since a discharge gas is enclosed, the gas discharge elements are formed inside an airtight container. According to the present invention, since the potential at the peripheral portion can be preferably set while the airtightness of the airtight container is ensured, a highly reliable display apparatus can be obtained.
Next, with reference to
On the first substrate 1 having a surface which is sufficiently washed beforehand, a film which serves as a material for device electrodes 12a and 12b is deposited by a general film formation technique. As the first substrate 1, a substrate having insulating properties is used, and more particularly, for example, a glass widely used for electronic devices, such as a quartz glass, an alkali free glass, or a blue plate glass, is used. The device electrodes 12a and 12b are formed from a conductive metal or the like by a general vacuum film formation technique, such as a CVD method, a deposition method, or a sputtering method. A material for the device electrodes 12a and 12b is appropriately selected, for example, from a metal, such as Be, Mg, Ti, Zr, Hf, V, Nb, Ta, Mo, W, Al, Cu, Ni, Cr, Au, Pt, or Pd, or an alloy thereof. In addition, for example, a carbide, such as TiC, ZrC, HfC, TaC, SiC, or WC, a boride, such as HfB2, ZrB2, LaB6, CeB6, YB4, or GbB4, a nitride, such as TaN, TiN, ZrN, or HfN, or a semiconductor, such as Si or Ge, may also be used. Furthermore, for example, an organic polymer material, amorphous carbon, graphite, diamond like carbon, or carbon or a carbon compound in which diamond is dispersed may also be selected. The thickness of each of the device electrodes 12a and 12b is appropriately selected. Next, after a photoresist is applied, a series of a photolithographic technique including exposure, development, and etching is performed to remove a part of the film thus deposited, so that the device electrodes 12a and 12b are formed (
After a photosensitive conductive paste is applied on the first substrate 1 by screen printing or the like, the column wires 3 having a predetermined pattern are formed by a photolithographic technique (
Subsequently, the potential regulating electrode 8 composed of at least one line is formed on at least one of four corners of the substrate 1 at which the column wires 3 are not arranged (
Next, a film which is used as a material for the wire insulating layers 4 is formed on the first substrate 1, the column wires 3, the device electrodes 12a and 12b, and the potential regulating electrodes 8 by a general vacuum film formation method, such as a sputtering method, a CVD method, or a deposition method. Subsequently, by a photolithographic technique, this film thus deposited is partially removed, so that the wire insulating layers 4 are formed (
Next, the row wires 2 are formed on the wire insulating layers 4 (
By the step described above, the contact hole 31 is filled with the material for the row wire 2, and the device electrode 12b is connected to the row wire 2 through the contact hole 31.
Next, at least on the first substrate 1, the row wires 2, the column wires 3, and the potential regulating electrodes 8, a photosensitive film which is used as a material for the sealing portion insulating layer 5 is formed by a lamination method. Subsequently, by mask pattern exposure and development, the photosensitive film thus formed is partially removed. In this step, the through-holes 6 are formed in the photosensitive film at desired positions (typically at four corners). Next, the sealing portion insulating layer 5 is formed by firing (
Next, after a conductive material to be formed into the sealing portion conductive layer 7 is pattern-printed on the sealing portion insulating layer 5 by a screen printing method or the like, drying and firing are performed, so that the sealing portion conductive layer 7 is formed (
Next, electron emission films 13 are formed. First, conductive films are each formed so as to be connected to the device electrodes 12a and 12b (
Although a substrate having insulating properties is used as the second substrate 21 as in the case of the first substrate 1, a substrate transparent to visible light is used for performing display. The screen member 24 includes the luminous layers 25, the anode 26 which is called a metal back, and the light shielding layer 27 which is called a black matrix (or black stripe). When the luminous layer 25 is monochrome, the light shielding layer 27 may be omitted. In the case of color display, in accordance with the arrangement of the luminous layers 25, the light shielding layer 27 is formed. The reasons the light shielding layer 27 is used are that color mixture is made inconspicuous by blacking portions between three primary color fluorescent substances which are necessary in the case of color display and that a decrease in contrast by outside light reflection at the luminous layer 25 is suppressed. As a material for the light shielding layer 27, besides a commonly used material containing graphite as a primary component, a material having electrical conductivity and small light transmission and reflection may also be used.
As a method for forming the luminous layer 25, which is a part of the screen member 24, by applying a fluorescent substance, regardless of whether monochrome or color, for example, a precipitation method or a printing method may be used. At an inner surface side of the luminous layers 25, a metal back is provided as the anode 26. The metal back is formed in such a way that after the luminous layers 25 are formed, the surfaces thereof at the inner surface side are smoothed (usually called “filming”), and Al is then deposited by vacuum deposition or the like. As the anode 26, a transparent conductive film, such as indium tin oxide (ITO), may also be used instead of the metal back, and in this case, the transparent conductive film may also be arranged between the second substrate 21 and the luminous layers 25.
The adhesion member 22 used as a bond portion with the conductive frame 23 is formed in the vicinity of the screen member 24 on the second substrate 21. As the adhesion member 22, a conductive member is used as in the case of the sealing portion conductive layer 7. Although the adhesion member 22 and the sealing portion conductive layer 7 may use different conductive members, the same conductive member is preferably used. After the conductive member used as a material for the adhesion member 22 is arranged by a screen printing method or the like, the adhesion member 22 is formed by drying and firing. In consideration of the size of the conductive frame 23, the adhesion member 22 is formed so as to be located at an appropriate position (within the acceptable range of the displacement of the conductive frame 23). A firing temperature is appropriately selected in accordance with the conductive member. In addition, the thickness of the adhesion member 22 is also appropriately designed. When the adhesion member 22 is directly formed on the second substrate 21, the potential regulation of the face plate 200 can be reliably performed by the adhesion member 22 from the potential regulating electrode 8 of the rear plate 100 through the conductive frame 23.
The rear plate 100 and the face plate 200 are placed in a vacuum chamber (not shown) in which heating of the substrate, alignment (X, Y), and gap control can be performed. In the vacuum chamber, the conductive frame 23 is placed on the rear plate 100, and the rear plate 100 and the face plate 200 are aligned to each other using alignment marks (not shown) formed therein (
Under this condition, the temperature of the rear plate 100 and that of the face plate 200 are increased in the chamber to a melting point of the sealing portion conductive layer 7 and that of the adhesion member 22. Next, the rear plate 100 is placed closer to the face plate 200, and the sealing portion conductive layer 7, the conductive frame 23, and the adhesion member 22 are adhered to each other. The step described above is carefully performed so that a low melting point metal may not overflow over each side of the conductive frame 23. Subsequently, by decreasing a substrate temperature, the rear plate 100 and the face plate 200 are airtightly bonded to the conductive frame 23, so that the airtight container is formed. In this sealing step, the potential regulating electrodes 8 of the rear plate 100 and the conductive frame 23 are electrically connected to each other by the sealing portion conductive layer 7 through the through-holes 6. In addition, a conductive contact member (not shown) which is set at a predetermined potential is brought into contact with the potential regulating electrode 8. For the conductive contact member, a conductive tape, an electrical cable, or a metallic member having an elastic section, each of which is set at a predetermined potential, may be used. When the conductive contact member is electrically connected to a supporting member (such as a chassis) or a housing (such as a cover) of the airtight container of the display apparatus or a GND line of an electrical circuit, grounding can be performed. When being set at a potential other than the ground potential, the conductive contact member is connected to the electrical circuit. The contact way of the conductive contact member described above may be seen, for example, in FIGS. 8 to 16 of Japanese Patent Laid-Open No. 2003-092075. Accordingly, the potential regulating electrode 8 of the rear plate 100 to the conductive frame 23 and further to the conductive adhesion member 22 at a face plate 200 side can be set at an equipotential (predetermined potential).
Hereinafter, the present invention will be described in detail with reference to a particular example.
As the first substrate 1, a high strain point glass PD200 (manufactured by Asahi Glass Co., Ltd.) having a thickness of 1.8 mm, which was generally used for plasma display panel and the like, was used. Platinum (Pt) (20 nm in thickness) was deposited on this glass substrate 1 by a sputtering method. Next, slit coating of a positive type photoresist (TSMR-8900/Tokyo Ohka Kogyo Co., Ltd.) was performed by a photolithographic process. Then, after the photoresist was exposed using a photomask pattern, followed by development, dry etching was performed using an Ar gas, and etching was stopped on the first substrate 1, so that the device electrodes 12a and 12b were formed (
Subsequently, a Cu film having a thickness of 1.0 μm was deposited by a sputtering method on the first substrate 1 and the device electrodes 12a and 12b. Next, a resist pattern was formed by a photolithographic process as in the case of the previous step. Subsequently, wet etching was performed for 1 minute using the photoresist thus patterned as a mask and SEA-1 (manufactured by Kanto Chemical Co., Inc.) as an etchant, so that the column wires 3 were formed to have a width of 20 μm (
In the previous process, the potential regulating electrodes 8 each formed of a bundle wire of 20 lines were simultaneously formed at four corners of the substrate 1 at which the column wires 3 are not arranged thereon (
Next, a SiO2 film having a thickness of 2.0 μm for the wire insulating layers 4 was deposited on the first substrate 1, the column wires 3, the device electrodes 12a and 12b, and the potential regulating electrodes 8 by a CVD method. Subsequently, a resist pattern was formed by a photolithographic process. Next, the wire insulating layers 4 and the contact holes 31 for exposing the device electrodes 12a and 12b were formed by etching parts of the SiO2 film using the photoresist thus patterned as a mask (
Next, on the wire insulating layers 4, Cu films having a thickness of 3.0 μm and a width of 300 μm were formed as the row wires 2 by a printing technique using a mask (
Next, a photosensitive film used as a material for the sealing portion insulating layer 5 was formed by a lamination method on the first substrate 1, the row wires 2, the column wires 3, the device electrodes 12a and 12b, the potential regulating electrodes 8, and the wire insulating layers 4. JIF (manufactured by JSR Corp.) which was a glass paste was used for the photosensitive film. Then, after exposure was performed using a mask, patterning was performed by development using a sodium carbonate solution at a concentration of 0.4%, followed by firing at a temperature of 400° C., so that the sealing portion insulating layer 5 was formed (
Next, after an Ag paste ink was arranged on the sealing portion insulating layer 5 by a screen printing method and was then dried, firing was performed at a temperature of 480° C., so that the sealing portion conductive layer 7 was formed. The thickness of the sealing portion conductive layer 7 after the firing was 3 μm. In this example, when the sealing portion conductive layer 7 was formed, the Ag paste was allowed to flow in the through-holes 6 and was filled therein, and as a result, the potential regulating electrodes 8 were electrically connected to the sealing portion conductive layer 7 (
Next, a palladium proline complex was dissolved in isopropyl alcohol and was applied between the device electrodes 12a and 12b to form a dot shape having a diameter of 60 μm using an ink jet ejection device. Subsequently, a heat firing treatment was performed on this substrate at 350° C. for 10 minutes in the air, so that conductive films were formed (
In the rear plate 100 of this example, when the resistance between the sealing portion conductive layer 7 and the potential regulating electrode 8 was measured by a tester, the resistance was approximately 0Ω, and hence it was confirmed that short circuit was obtained.
The glass substrate 21 formed of a high strain point glass PD200 (manufactured by Asahi Glass Co., Ltd.) having a thickness of 1.8 mm was annealed and washed. Next, the light shielding layer 27 which had openings was formed to have a thickness of 10 μm by a screen printing method using a black pigment paste containing a glass paste and a black pigment. The size of the opening was 75 μm in the X direction and 200 μm in the Y direction. Subsequently, three primary color fluorescent substance films of R (red), G (green), and B (blue) were applied to the openings by a screen printing method. In this case, in the X direction, R (red), G (green), and B (blue) were arranged in this order, and in the Y direction, the fluorescent substances having the same color were arranged. Next, the metal back was formed as the anode 26 using a filming method which was well known in a cathode ray tube (CRT) field. After a resin interlayer was formed on the fluorescent substance films, aluminum was formed to have a thickness of 100 nm by a vacuum deposition method. Subsequently, firing was performed at 450° C., so that the resin interlayer was removed. Next, after an Ag paste ink was applied to the glass substrate 21 at positions apart from the screen member 24, followed by drying, firing was performed at a temperature of 480° C., so that the adhesion member 22 was formed. The thickness of the adhesion member 22 after the firing was 3 μm.
Heat press bonding was performed in a vacuum furnace on the rear plate 100, the face plate 200, and the conductive frame 23 of aluminum, so that the rear plate 100, the conductive frame 23, and the face plate 200 were collectively vacuum sealed. In the vacuum sealing, a glass spacer (not shown) having a thickness of 2 mm which accurately defined the gap between substrates was provided between the rear plate 100 and the face plate 200, so that the gap therebetween was made constant. In this heat press bonding step, the sealing portion conductive layer 7 of Ag and the adhesion member 22 were tightly bonded to the conductive frame 23, and as a result, the airtight container was formed. As described above, the display apparatus was formed. In the display apparatus of this example, when the resistance between the adhesion member 22 and the potential regulating electrode 8 was measured by a tester, the resistance was approximately 0Ω, and it was confirmed that short circuit was obtained.
The electron-emitting devices 11 were each driven by applying a scanning signal to the row wire 2 of the display apparatus thus formed and by applying an information signal to the column wire 3 thereof. A pulse voltage of +6 V was used as the information signal, and as the scanning signal, a pulse voltage of −10 V was used. Display was performed by applying an anode potential of 6 kV to the metal back. In addition, the electric potential regulation electrodes 8 were grounded. Although the display was observed continuously for 24 hours, no discharge occurred, and a bright image could be stably displayed. Furthermore, although the anode potential was set at 12 kV, and display was performed for 1 hour, no discharge occurred.
A rear plate used for comparison was formed by a process similar to that in Example 1 except that no through-holes 6 were formed in the sealing portion insulating layer 5. Instead of forming the through-holes 6, the following [formation of conductive film] process was performed after the above [formation of sealing portion insulating layer].
Indium was applied using a dispenser to a position from the side surfaces to the upper surface of the sealing portion insulating layer 5 which overlapped with the potential regulating electrodes 8 so as to be brought into contact with the potential regulating electrodes 8 and the conductive frame 23, so that an electrical conduction film was formed.
When a cross-sectional shape of the sealing portion insulating layer was observed by a scanning electron microscope (SEM), the thickness of the conductive film was not uniformly formed, and a disconnected portion was also observed. When the resistance between the sealing portion conductive layer 7 and the potential regulating electrode 8 was measured by a tester, the resistance was 3 MΩ, and the electrical conductivity was inferior.
Furthermore, sealing was performed with the face plate 200, and the display apparatus was formed. As in the case of the example, when the anode potential was set at 12 kV, and the display was performed for 1 hour, discharge occurred.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2009-274966 filed Dec. 2, 2009, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-274966 | Dec 2009 | JP | national |
