JP2008226664A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device capable of keeping excellent display performance over a long term by a small quantity of getter. <P>SOLUTION: This image display device is provided with: an envelope 10 having a front substrate 11 having a display surface thereon, and a back substrate 12 arranged oppositely to the front substrate; and a plurality of getter vessels 50 and 52 having getter chambers 54 and 56 provided with getters 60a and 60b, respectively, and respectively jointed to the envelope. The plurality of getter chambers communicate with the inside of the envelope with conductance values different from one another. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image display device including an envelope having a front substrate and a rear substrate arranged to face each other and maintained inside a vacuum.

  In recent years, various flat-type image display devices have attracted attention as lightweight and thin image display devices. For example, a plasma display panel (hereinafter referred to as “PDP”) that emits a phosphor by ultraviolet rays of plasma discharge, a field emission display (hereinafter referred to as “FED”) that mainly uses electron emission by an electric field, and a surface conduction electron-emitting device A surface-conduction electron emission display (hereinafter referred to as SED) that emits phosphors with an electron beam has been developed.

  These image display devices have a front substrate and a rear substrate opposed to each other with a predetermined gap as a basic configuration, and these substrates constitute a flat envelope by joining the peripheral parts to each other. is doing. In the FED and SED, a good image display is enabled by maintaining the space between the front substrate and the rear substrate, that is, the inside of the envelope at a high degree of vacuum. Further, in PDP, it is an important technique to keep the inert gas filling the inside of the envelope with high purity.

Therefore, in order to maintain a high degree of vacuum inside the envelope for a long period of time, it is usual to provide a getter that adsorbs undesired gas molecules inside the envelope. As such a getter, for example, a method of forming a non-evaporable getter layer in a region adjacent to the panel side of the PDP has been proposed (see, for example, Patent Document 1). In addition, a method has been proposed in which a getter box is provided in the periphery of the envelope of the fluorescent display tube, and a getter made of barium is formed in the getter box (see, for example, Patent Document 2).
JP-A-11-191378 Utility Model Registration No. 2547509

  Conventionally, the conductance between the envelope and the getter box is determined so that the inside of the envelope can be kept below a predetermined degree of vacuum at the initial stage of driving when the gas discharge rate of the display device is maximized. When there is a single getter box or when the conductances between multiple getter boxes and the envelope are all the same, all getters deteriorate simultaneously with the operating time of the display device, and the gas adsorption capacity over time Decreases. Although the lifetime can be extended by increasing the amount of getters in the getter box, there is a problem that the manufacturing cost is increased.

  When considering the getter materials with different adsorption characteristics in each getter box and selectively adsorbing different kinds of gases, if the conductance of the getter boxes is the same, each getter box originally has Gas that you don't want to adsorb also flows in. For this reason, the getter adsorbs gas other than the gas to be adsorbed, and selective gas adsorption cannot be performed.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an image display apparatus capable of maintaining good display performance over a long period of time with a small amount of getter.

  An image display apparatus according to an aspect of the present invention includes an envelope having a front substrate provided with a display surface and a rear substrate disposed opposite to the front substrate, and getter chambers each provided with a getter. A plurality of getter containers joined to the envelope, and the plurality of getter chambers communicate with each other with different conductances.

  According to this aspect of the present invention, it is possible for each getter to selectively adsorb a gas without all the getters disposed at the same time being deteriorated. Accordingly, it is possible to provide an image display device capable of maintaining good display performance over a long period with a small amount of getter.

Hereinafter, an embodiment in which an image display device of the present invention is applied to an SED will be described in detail with reference to the drawings.
As shown in FIGS. 1 and 2, the SED includes a front substrate 11 and a rear substrate 12 each made of a rectangular glass plate, and these substrates are arranged to face each other at a predetermined interval. The back substrate 12 is formed with a size larger than that of the front substrate 11. The front substrate 11 and the back substrate 12 constitute a flat envelope 10 whose peripheral portions are joined to each other through a rectangular frame-shaped side wall 13 and the inside is maintained in a vacuum state. The side wall 13 functioning as a bonding member is sealed to the peripheral edge of the front substrate 11 and the peripheral edge of the back substrate 12 by, for example, a sealing material 25 such as low melting glass or low melting metal, and these substrates are bonded to each other. is doing.

  A plurality of plate-like support members 14 are provided inside the envelope 10 in order to support an atmospheric pressure load applied to the front substrate 11 and the rear substrate 12. These support members 14 extend in a direction parallel to one side of the envelope 10 and are arranged at a predetermined interval along a direction orthogonal to the one side. Both ends in the longitudinal direction of each support member 14 are opposed to the side wall 13 with a gap. The support member is not limited to a plate shape, and a columnar support member may be used.

  As shown in FIGS. 2 and 3, a phosphor screen 16 that functions as a display surface is formed on the inner surface of the front substrate 11. The phosphor screen 16 is configured by arranging red, green, and blue phosphor layers R, G, and B, and a black light-shielding layer 20 positioned between the phosphor layers. The phosphor layers R, G, and B of three colors of red, green, and blue are formed alternately with a gap in the first direction, and the phosphor layers of the same color are in the second direction orthogonal to the first direction. Are arranged with a gap in between. Each of the phosphor layers R, G, and B constitutes a subpixel with single colors of red, green, and blue, and constitutes one pixel by combining the subpixels of three colors.

  A metal back layer 17 made of an aluminum film or the like is formed on the phosphor screen 16. According to the present embodiment, the metal back layer 17 has a plurality of divided regions that are divided in the vertical direction and the horizontal direction and are electrically separated from each other. The electrically separated metal back layer 17 is provided so as to overlap the phosphor layers R, G, and B, respectively.

  As shown in FIG. 2, on the inner surface of the back substrate 12, a number of surface conduction type electron emitters each emitting an electron beam as an electron source for exciting the phosphor layers R, G, B of the phosphor screen 16 are provided. An element 18 is provided. These electron-emitting devices 18 are arranged in a plurality of columns and a plurality of rows corresponding to the pixels. Each electron-emitting device 18 includes an electron emitting portion (not shown) and a pair of device electrodes for applying a voltage to the electron emitting portion. A large number of wirings 21 for supplying a potential to the electron-emitting devices 18 are provided in a matrix on the inner surface of the rear substrate 12, and end portions thereof are drawn out of the envelope 10.

  Exhaust holes 29 for exhausting the inside of the envelope 10 in the exhaust process are formed through the periphery of the back substrate 12, for example, corners. The exhaust hole 29 is provided at a position away from the phosphor screen 16, that is, at a position away from the effective display area. The exhaust hole 29 is hermetically sealed by the lid member 30. The number of exhaust holes 29 is not limited to one, and can be increased as necessary.

  In such an SED, when displaying an image, an anode voltage is applied to the phosphor screen 16 and the metal back layer 17, and the electron beam emitted from the electron-emitting device 18 is accelerated by the anode voltage to the phosphor screen. Collide. Thereby, the phosphor layers R, G, and B of the phosphor screen 16 are excited to emit light, and a color image is displayed.

  As shown in FIGS. 2 and 4, the SED includes a plurality of getter boxes each having a getter chamber, for example, two getter boxes 50 and 52, in order to maintain the degree of vacuum in the envelope 10. . The getter chamber communicates with the inside of the envelope 10 through a communication hole formed in the back substrate 12, and each getter chamber is provided with a getter. By the gas adsorption of these getters, deterioration of the degree of vacuum in the envelope 10 is suppressed.

  The getter boxes 50 and 52 as getter containers are made of, for example, glass or metal and are attached to the peripheral portion of the envelope 10. Here, the getter boxes 50 and 52 are respectively joined to two corner portions located on the outer surface of the back substrate 12 and on the opposite side of the exhaust hole 29, and two getter chambers 54 and 56 are defined by the getter box. Has been. The getter boxes 50 and 52 are formed of, for example, glass or metal in a rectangular cross section and extend along one side edge of the back substrate 12. Each getter box 50, 52 is bonded to the back substrate 12 by, for example, a low melting point glass 51.

  In the getter chambers 54 and 56 of the getter boxes 50 and 52, one type of getter is provided for each purpose. Here, getter films 60a and 60b made of Ba are formed on the inner surfaces of the getter chambers 54 and 56 by vapor deposition.

  The getter chambers 54 and 56 communicate with the inside of the envelope 10 with different conductances. The getter chamber 54 communicates with the inside of the envelope 10 through a first communication hole 58 a formed in the back substrate 12. The getter chamber 56 communicates with the inside of the envelope 10 through a second communication hole 58 b formed in the back substrate 12. The first communication hole 58a and the second communication hole 58b are formed to have different hole diameters. For example, the first communication hole 58a is formed with a hole diameter of 3 mm, and the second communication hole 58b is formed with a hole diameter of 1 mm. Thus, the conductance of the getter chamber 54 with respect to the inside of the envelope 10 is nine times the conductance of the getter chamber 56.

  The diameter of the larger first communication hole 58a is determined so that the inside of the envelope 10 is maintained at a predetermined pressure or lower when the gas discharge rate is the highest in the initial stage of driving the SED. Further, the hole diameter of the smaller second communication hole 58b and the amount of getter in the getter chamber 54 are determined so that the decrease in the gas adsorption characteristic of the getter is smaller than the attenuation of the gas discharge rate of the envelope 10. .

  In the above configuration, the gas such as carbon monoxide and carbon dioxide generated in the envelope 10 as the SED is driven enters the getter chamber 54 through the first communication hole 58a and is adsorbed by the getter film 60a. It enters the getter chamber 56 through the second communication hole 58b and is adsorbed by the getter film 60b. At this time, the getter chamber 54 has a larger conductance than the getter chamber 56, so that more gas flows into the getter chamber 54 than the getter chamber 56. Therefore, at the initial stage of driving the SED with a large amount of gas release, more gas is adsorbed mainly by the getter film 60a of the getter chamber 54, and the getter film 60b provided in the other getter chamber 56 is gradually increased by a small amount. Gas is adsorbed over the entire area. The getter film 60a in the getter chamber 54 deteriorates in a time shorter than the lifetime of the panel and does not adsorb gas, but the gas release rate in the panel also decreases with time. For this reason, after the released gas for a certain period of time from the initial stage of the drive is adsorbed by the getter film 60a of the getter chamber 54, the inside of the envelope 10 has a desired degree of vacuum only by gas adsorption by the getter film 60b provided in the getter chamber 56 Can be maintained.

  FIG. 4 shows the result of comparing the change in the getter adsorption speed according to the SED driving elapsed time for the SED including the getter box according to the present embodiment and the SED according to the comparative example. In the SED according to the comparative example, the two getter chambers have the same conductance, that is, the first communication hole and the second communication hole have the same diameter. In FIG. 4, a one-dot chain line curve B showing the gas adsorption speed necessary for maintaining the inside of the envelope 10 below a predetermined pressure, and a solid line curve C comparing the gas adsorption speed of the SED according to this embodiment. The gas adsorption rate of the SED according to the example is indicated by a chain line curve D.

  As can be seen from the comparison of these curves B, C, and D, in the SED according to the comparative example, the gas adsorption capacity of the getter is lower than the required gas adsorption speed at the point a, whereas the SED according to the present embodiment. According to the above, it is possible to maintain a necessary gas adsorption speed up to the point B, and it is possible to exhibit a sufficient gas adsorption capacity over a long period of time compared to the SED according to the comparative example. That is, when the same amount of getter material as that in the comparative example is used, the panel life of the SED according to the present embodiment is longer.

  According to the SED configured as described above, the released gas in the envelope 10 is mainly adsorbed by the getter film 60a provided in the getter chamber 54 at a stage where the gas release at the initial stage of driving of the SED is large. The getter film 60b provided in the getter chamber 56 hardly adsorbs gas at the initial stage of SED operation, and can be kept as a getter for the second half of the panel life. According to this embodiment, it is possible to maintain a good vacuum inside the envelope for a long period without using a large amount of getters, and to obtain an SED that can maintain high display performance for a long period of time. it can. Further, by providing a plurality of getter chambers communicating with the inside of the envelope and arranging the getters in these getter chambers, the getter forming process can be simplified. By providing the getter in the getter chamber, the getter film is not subject to structural restrictions of the phosphor screen or the electron-emitting device. Therefore, a getter can be formed in accordance with the gas release characteristics of the phosphor screen and the performance of the image display device.

  Next, the SED according to the second embodiment will be described. In the second embodiment, the configuration of the SED is the same as that of the above-described embodiment, but the diameters of the first communication hole 58a and the second communication hole 58b communicating with the getter chamber are changed and the two getter chambers 54, 56 are used. Different types of getters are arranged inside.

  That is, the getter chamber 54 defined by the getter box 50 communicates with the inside of the envelope 10 through the first communication hole 58a, and the getter chamber 56 defined by the getter box 52 communicates with the envelope through the second communication hole 58b. 10 communicates with the interior. The diameter of the first communication hole 58a is 10 mm, and the diameter of the second communication hole 58b is 3 mm.

  In the getter chamber 54, Ba is vapor-deposited to form a getter film 60a, and in the getter chamber 56 Ti is vapor-deposited to form a getter film 60b. The conductance of the getter chamber 56 in which Ti is disposed, here, the diameter of the second communication hole 58b, is determined so that the Ti partial pressure in the envelope 10 is kept below a predetermined value. On the other hand, the conductance of the getter chamber 54 in which Ba is arranged, here, the hole diameter of the first communication hole 58a is formed sufficiently larger than the hole diameter of the second communication hole 58b, and the conductance is set to be about 10 times. Has been.

Since Ba does not adsorb much H ₂ , it is arranged for the purpose of mainly adsorbing carbonic acid gas such as CO. The amount of Ba is set to an amount that can sufficiently adsorb carbon dioxide gas such as CO released during the life of the SED. Ti adsorbs H ₂ and carbon dioxide gas well, but in this embodiment, the getter chamber 54 in which Ba is disposed has a conductance approximately 10 times larger than the getter chamber 56 in which Ti is disposed. Therefore, the amount of carbonic acid gas on which Ti is adsorbed is about 1/10 of Ba.

Compared to the case where the conductances of the getter chamber in which Ba is arranged and the getter chamber in which Ti is arranged are set to be the same, according to the present embodiment, the flow rate of carbon dioxide gas to the getter chamber 56 in which Ti is arranged Is about 1/5 of the getter chamber 54. For this reason, early deterioration of the getter film made of Ti can be suppressed, and even a small amount of Ti can adsorb H ₂ for a long time.

  According to the second embodiment configured as described above, all the arranged getters are not deteriorated at the same time, and the degree of vacuum of the envelope can be designed according to the purpose. Moreover, it becomes possible to selectively adsorb the released gas in the envelope for each getter chamber according to the type. As a result, an image display device having good display performance over a long period of time can be provided even if the amount of getter is small.

  The present invention is not limited to the above-described embodiment, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. Some constituent elements may be deleted from all the constituent elements shown in the embodiments, or constituent elements over different embodiments may be appropriately combined.

  In the embodiment described above, the conductance of the getter chamber is adjusted by adjusting the hole diameters of the first and second communication holes. However, the conductance is adjusted not only by the hole diameter but also by changing the hole length. May be. Each getter chamber is configured to communicate with the inside of the envelope through one communication hole, but may be configured to communicate with the interior of the envelope through a plurality of communication holes. When a plurality of communication holes are provided, the conductance of the getter chamber is determined by the diameter of the plurality of communication holes, that is, the sum of the areas.

  In the above-described embodiments, the SED including the front substrate having the phosphor screen on the inner surface has been described as an example. However, the present invention is not limited to this, and other types such as FED, PDP, fluorescent display tube, and semiconductor sensor are used. It can also be applied to devices. As the electron-emitting device, a pn-type cold cathode device or a field-emission type electron-emitting device may be used. The dimensions, materials, and the like of each component are not limited to the numerical values and materials shown in the above-described embodiments, and can be variously selected as necessary.

  The getter is not limited to Ti, Ba, and the like, and various getters can be used according to the vacuum characteristics, emission gas characteristics, heat resistance, etc. of the device to be used. Other metal materials, organic materials, inorganic materials, and the like can be selected. For example, Zr, V, Ta, Y, La pure metals and alloys can be used as the evaporative getter, and Ti, Zr, V, Fe, Al, Cr, Nb, non-evaporable getters can be used. You may use metals, such as Ta, W, Mo, Ni, Mn, and Y, or these alloys.

  The size, shape, and number of installations of the getter chambers and getter boxes are not limited to the above-described embodiment. For example, the number of getter chambers is not limited to two, and may be three or more. In addition, the getter chamber is not limited to the rear substrate side of the envelope, and a portion of the side wall of the envelope may be cut out to provide the getter chamber on the side surface of the envelope.

FIG. 1 is a perspective view showing a partially broken SED according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the SED along line AA in FIG. FIG. 3 is an enlarged plan view showing a part of the front substrate and phosphor screen of the SED. FIG. 4 is a perspective view showing a getter box. FIG. 5 is a diagram showing a comparison of changes in gas adsorption speed between the present embodiment and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Envelope, 11 ... Front substrate, 12 ... Back substrate, 13 ... Side wall,
14 ... support member, 16 ... phosphor screen, 17 ... metal back layer,
18 ... electron-emitting device, R, G, B ... phosphor layer, 20 ... light shielding layer,
50, 52: Getter box, 54, 56: Getter chamber, 58a: First communication hole,
58b ... second communication hole, 60a, 60b ... getter film

Claims (7)

An envelope having a front substrate provided with a display surface and a rear substrate disposed opposite to the front substrate;
Each having a getter chamber provided with a getter, and a plurality of getter containers each joined to the envelope, wherein the plurality of getter chambers communicate with each other with different conductances in the envelope. Image display device.   The image display apparatus according to claim 1, wherein one type of getter is disposed in each getter chamber.   The image display device according to claim 1, wherein the plurality of getter chambers are provided with the same type of getter.   The image display device according to claim 1, wherein different types of getters are arranged in the plurality of getter chambers.   Each of the plurality of getter chambers communicates with the envelope through a communication hole formed in the envelope, and the plurality of communication holes have different conductances with respect to the interior of the envelope. The image display device according to any one of claims 1 to 4.   2. The getter uses any one of Ba, Ti, Zr, V, Fe, Al, Cr, Nb, Ta, W, Mo, Ni, Mn, Y, La, and Hf or an alloy thereof. The image display device described in 1.   The image display apparatus according to claim 1, further comprising: a phosphor screen disposed on the front substrate; and an electron source disposed on the rear substrate.

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