JP2009289517A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device having stable characteristics in voltage resistance over a long period of time with a simple method. <P>SOLUTION: The image display device includes a front face substrate having a fluorescent layer and a metal back layer; a back face substrate having electron emission elements; and spacers arranged between the front face substrate and the back face substrate. The metal back layer consists of a plurality of divided metal back layers spaced from one another. The front face substrate has a common electrode for applying voltage to the plurality of divided metal back layers. The common electrode is provided not to intersect the spacers on a plane parallel with the front face substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image display device.

  As an image display device, a flat image display device having a plurality of electron-emitting devices arranged to face a fluorescent layer is known. In this image display device, the front substrate having the fluorescent layer and the rear substrate having the electron-emitting device are separated from each other by a predetermined distance in a direction perpendicular to the surfaces of the substrates. And the peripheral part of a front substrate and the peripheral part of a back substrate are joined with the frame member, and the vacuum envelope is comprised by this. The inside of the vacuum envelope is kept in a vacuum.

  Therefore, in order to support the atmospheric pressure load applied to the front substrate and the rear substrate, a plurality of spacers are disposed between the two substrates. Conventionally, a display area (an area on which an image is displayed) is used as a spacer for the purpose of reducing the number of spacers, or for contacting (electrically connecting) with a potential regulating electrode provided on the peripheral edge of the front substrate. ) A plate-like spacer extending to the outside is used.

  In such an image display device, when displaying an image, a voltage (anode voltage) is applied to the phosphor layer of the front substrate. Specifically, an aluminum thin film called a metal back is formed on the back substrate side of the fluorescent layer, and an anode voltage is applied to the aluminum thin film.

  In such an image display device, the distance between the front substrate and the rear substrate is usually set to several mm or less. Therefore, a strong electric field is formed between the substrates, and discharge (dielectric breakdown) may occur between the substrates. Such a discharge causes destruction of the electron-emitting device, deterioration of display quality, and the like.

  As a conventional technique in view of such a problem, a technique for reducing the influence of discharge on an image display device by suppressing the scale of discharge has been proposed. For example, Patent Document 1 discloses a technique for suppressing charge transfer (discharge current) during discharge by making a conductive layer (metal back layer) of a front substrate electrically independent. That is, there has been proposed an image display device in which a metal back is divided into a plurality of parts and these are electrically connected to each other by a high resistance member (high resistance member). In such a configuration, a common electrode for applying an anode voltage to each metal back is generally provided.

JP 2006-185614 A

In the configuration in which the metal back is divided into a plurality of parts, the common electrode is generally formed so as to surround the display region in a plane parallel to the front substrate. As a result, the common electrode intersects the spacer in a plane parallel to the front substrate. However, when a discharge occurs between the front substrate and the rear substrate, the spacer and the common electrode of the front substrate face each other outside the display area, that is, the spacer and the common electrode intersect on a plane parallel to the front substrate. If the configuration is such that the following problems occur.
When the spacer and the common electrode are in contact with each other, a discharge is induced by physical destruction of the common electrode.
When the spacer and the common electrode are not in contact with each other, a discharge is induced between the spacer and the common electrode.

  Hereinafter, a phenomenon in which discharge is induced when the spacer and the common electrode are in contact with each other, that is, a phenomenon in which discharge is induced by physical destruction of the common electrode will be described.

  FIG. 2 is a view of the front substrate and the spacer as viewed from the rear substrate side. In FIG. 2, 21 is a divided metal back, 22 is a divided member between the metal backs, 23 is a common electrode, 24 is a connection resistance, 25 is a spacer, and 26 is a potential regulating electrode. The common electrode 23 is formed on the front substrate so as to surround the display area. The common electrode 23 and the metal back 21 are connected to each other via an electrically high resistance member (connection resistance 24). The spacer 25 is regulated in potential by connecting its end to the potential regulating electrode 26 (for example, the potential is regulated to the ground potential). In such a configuration, the common electrode 23 intersects the spacer 25 in a plane parallel to the front substrate.

  In the configuration shown in FIG. 2, if the spacer and the common electrode are in contact with each other, the common electrode 23 may be cracked or chipped. This is shown in FIGS. 3 (a) and 3 (b). 3A and 3B are cross-sectional views of the image display device. Note that if the spacer and the common electrode are in contact with each other, the spacer and the common electrode may be cracked or chipped, and the spacer and the common electrode may not be in contact with each other. The case where the spacer and the common electrode are not in contact with each other will be described later.

  In the image display device shown in FIGS. 3A and 3B, the front substrate 31 and the back substrate 32 are sealed with the frame member 33, respectively. That is, the front substrate 31, the rear substrate 32, and the frame member 33 constitute a vacuum envelope. Reference numeral 36 denotes a display area in which an image on the front substrate 31 is displayed, and reference numeral 38 denotes wiring formed on the rear substrate 32. The space between the front substrate 31 and the back substrate 32 is held by a spacer 34. Reference numeral 35 denotes a common electrode for applying an anode voltage to the metal back. In the example of FIGS. 3A and 3B, the common electrode 35 intersects with the spacer 34 in a plane parallel to the front substrate, and they are in contact with each other.

  In the configuration shown in FIG. 3A, the common electrode 35 is not physically broken (not chipped), so that the image display device operates normally. However, in the configuration shown in FIG. 3B, the common electrode 35 is chipped at the portion where the common electrode 35 and the spacer 34 are in contact with each other.

  A strong electric field is likely to be generated partially at a portion where such a chip occurs (a chip portion). For this reason, the frequency of occurrence of discharge between the front substrate and the rear substrate near the chipped portion increases.

  Next, a phenomenon in which discharge is induced when the spacer and the common electrode are not in contact with each other, that is, a phenomenon in which discharge is induced between the spacer and the common electrode will be described.

  Hereinafter, this phenomenon will be described with reference to FIG.

  FIG. 4 is a cross-sectional view of the image display device. In FIG. 4, the vacuum envelope includes a front substrate 41, a rear substrate 42, and a frame member 43 as in FIG. 3. A spacer 44 is disposed between the front substrate 41 and the rear substrate 42. The potential of the spacer 44 is regulated by electrically connecting the end thereof to the potential regulating electrode 47. In the example of FIG. 4, the common electrode 45 intersects the spacer 44 in a plane parallel to the front substrate, and they are separated from each other.

In FIG. 4, when a discharge occurs in the metal back in the vicinity of the spacer 44, the potential of the front substrate 41 decreases to the vicinity of the grant potential with the discharge point as the center. However, the potential of the common electrode 45 connected to the high-voltage power supply does not decrease so much. On the other hand, the potential of the spacer 44 (spacer near the discharge point) decreases in the same manner as the front substrate due to a decrease in the potential of the front substrate. For this reason, if the common electrode 45 and the spacer 44 are not in contact with each other, a large potential difference is generated between the common electrode 45 and the spacer 44.

  Therefore, secondary discharge is induced in this portion (a portion where the common electrode 45 and the spacer 44 intersect).

  When either of the two discharges described above occurs, the electric charge (current) of the common electrode 45 having an electrically low resistance and no current limiting function flows through the spacer 44 into the wiring 48 provided on the back substrate 42. End up. As a result, an overcurrent flows to an electron-emitting device (not shown) and a driving device that are electrically connected to the wiring 48, which may cause unacceptable defects, defects, and damage in terms of product characteristics. This is shown in FIG. An arrow is a path of current flowing from the common electrode.

  Therefore, in order to obtain stable characteristics withstand pressure over a long period of time, the spacer and the common electrode must be brought into contact with each other so that the members (common electrode, spacer, etc.) do not break. However, considering the warpage of the glass substrate due to heat, the accuracy of the height of the spacer, the accuracy of the height of the frame member, the assembly accuracy thereof, etc., guaranteeing the connection between the spacer and the common electrode is 100% on the manufacturing process. It is extremely difficult.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image display device having stable characteristics over a long period of time with a simple method.

  In order to achieve the above object, an image display device according to the present invention includes a front substrate having a fluorescent layer and a metal back layer, a rear substrate having electron-emitting devices, and a gap between the front substrate and the rear substrate. The metal back layer is composed of a plurality of divided metal back layers spaced apart from each other, and the front substrate has a common electrode for applying a voltage to the plurality of divided metal back layers. The common electrode is provided so as not to intersect the spacer in a plane parallel to the front substrate.

  According to the present invention, it is possible to provide an image display device having stable characteristics over a long period of time with a simple method.

  The image display apparatus according to this embodiment will be described below.

  The image display apparatus according to the present embodiment is an image display apparatus having electron emission elements such as a field emission electron emission element, a surface conduction electron emission element, and an MIM type electron emission element. Conventionally, in such an image display device, a discharge generated between a front substrate having a fluorescent layer and a rear substrate having an electron-emitting device has been a problem. For example, such discharge causes destruction of the electron-emitting device or the like and deterioration of display quality. The image display apparatus according to the present embodiment is for solving such a problem. Hereinafter, the image display apparatus according to the present embodiment will be described in detail with reference to examples.

<Example>
FIG. 7 shows a perspective view of the image display apparatus according to the present embodiment. In FIG. 7, 71 is a front substrate,
Reference numeral 72 denotes a back substrate. The front substrate 71 and the back substrate 72 are each made of glass. These substrates are opposed to each other with an interval of 1 to 2 mm in a direction perpendicular to the surface of the substrate. The peripheral edge portion of the front substrate and the peripheral edge portion of the back substrate are respectively joined to the frame member 73 (side wall). Thereby, a vacuum envelope is constituted. The inside of the vacuum envelope is kept at a high degree of vacuum of 10 ⁻⁴ Pa or less. In this embodiment, the front substrate 71 and the back substrate 72 are each rectangular. The shape of the frame member 73 is a rectangular frame shape. Therefore, the shape of the vacuum envelope is a flat rectangular shape.

  FIG. 8 shows a part of a cross section of the image display apparatus according to the present embodiment. Reference numeral 81 denotes a fluorescent layer formed on the inner surface of the front substrate (the surface on the rear substrate side). The phosphor layer 81 includes a phosphor layer 82a that emits red, green, and blue (R, G, and B) and a matrix-shaped light shielding layer 82b. A metal back layer 83 that functions as an anode electrode is formed on the fluorescent layer. When displaying an image, a predetermined voltage (anode voltage) is applied to the metal back layer 83. The fluorescent layer and the metal back layer will be described in detail later.

  On the inner surface of the back substrate 84, a large number of electron-emitting devices 85 that emit an electron beam for exciting the phosphor layer are provided. These electron-emitting devices 85 are arranged in a plurality of columns and a plurality of rows corresponding to each pixel. The electron-emitting device 85 is driven by applying a voltage via the wiring 86 arranged in a matrix.

  When an anode voltage is applied to the metal back layer 83, the electron beam emitted from the electron emitter 85 is accelerated. Then, the accelerated electron beam collides with the fluorescent layer 81. As a result, the corresponding phosphor layer (the phosphor layer on which the electron beam collides) emits light, and an image is displayed.

  Next, the fluorescent layer and the metal back layer in the image display apparatus according to the present embodiment will be described in detail. Although the term “metal back layer” is used in this embodiment, this layer is not limited to metal (metal), and various conductive materials can be applied. In this embodiment, the term metal back layer is used for convenience.

  As described above, the fluorescent layer provided on the inner surface of the front substrate has a (black) light shielding layer. This black light shielding layer is composed of, for example, a large number of stripe portions arranged in parallel at a predetermined interval and a rectangular frame portion along the periphery of the fluorescent layer. The fluorescent layer has a large number of striped phosphor layers R, G, and B that emit red, blue, and green, and these phosphor layers are respectively formed between the black light-shielding layers.

  The metal back layer according to the present embodiment is a divided metal back layer that is separated from each other. In this embodiment, the metal back layer 61 is divided by the dividing member 62 as shown in FIG. The division member is a member for dividing the phosphor layers R, G, and B (not shown) into a set and dividing each set. That is, each metal back layer 61 is provided so as to overlap each phosphor layer R, G, B1 set on the phosphor layer. The dividing member 62 is made of an electrically high resistance member (high resistance member) and is connected to each metal back layer 61. The metal back layer 61 may be provided so as to overlap a part of the black light shielding layer. In that case, when the black light shielding layer is composed of a high resistance member, the dividing member may not be provided. Moreover, you may form another material layer between a division member and a metal back layer as needed. Further, the area of each metal back layer may not be provided so as to be overlapped for each phosphor layer R, G, B1 set. For example, each metal back layer may be provided for each of the phosphor layers R, G, and B3.

By adopting such a configuration, even when a discharge that causes a short circuit between the front substrate and the rear substrate (discharge between the front substrate and the rear substrate) occurs during driving of the image display device, the discharge occurs due to the discharge. Charge transfer can be limited. Specifically, even when such a discharge occurs, the discharge current flowing from the metal back to the wiring of the back substrate or the like can be limited by the resistance of the dividing member (or black light shielding layer).

  During the driving of the image display device, the relationship between the front substrate and the rear substrate (metal back layer and rear substrate) can be regarded as a so-called parallel plate capacitor. Dividing the metal back layer corresponds to dividing the area of the plate of the capacitor into small regions. For this reason, the amount of charge stored in each capacitor is smaller than when the capacitors are not divided. And if each capacitor | condenser is mutually connected by a high resistance member, even if a certain capacitor short-circuits, it will become difficult to flow an electric current between capacitors. Thereby, the amount of movement of charges due to a short circuit can be limited. For the same reason, even if a discharge occurs between the front substrate and the rear substrate, the charge transfer generated by the discharge can be limited.

  The metal back layer is formed by a thin film process such as vapor deposition. Since the fluorescent layer has unevenness, when the metal back layer is directly formed on the fluorescent layer, the uneven metal back layer is formed. Therefore, in general, in order to form a metal back layer having a mirror surface, the phosphor layer is subjected to a smoothing process such as lacquer and then vapor deposition is performed. Further, as a thin film process, a method in which a sheet on which aluminum is deposited is transferred by heating can also be used. The film thickness of the metal back layer is preferably about 50 to 200 nm in consideration of electron beam transmittance and film strength.

  In this example, aluminum was vapor-deposited in a vacuum after a smoothing treatment with a lacquer. Thereby, an aluminum layer having a thickness of 150 nm was formed as a metal back layer.

  The method of dividing the metal back layer is, for example, by forming a dividing member on the black light-shielding layer in advance and removing the dividing member after forming the metal back layer when forming the metal back layer on the fluorescent layer. There is a way to divide. This method is effective when the metal back layer is formed by vacuum deposition. In this example, the metal back layer was divided and formed by the above method. In addition, when using a division member as a high resistance member, it is not necessary to remove. As another dividing method, there is a method in which a single metal back layer is formed and then divided by a heat treatment such as a laser or physical pressure.

  A voltage (anode voltage) of several kV to several tens of kV is applied to the divided metal back layer in order to display an image.

  As described above, the metal back layer is divided in order to suppress a discharge scale when a discharge occurs between the front substrate and the rear substrate. Then, the anode voltage is applied to each metal back layer from the common electrode 63 provided on the front substrate as shown in FIG. 6 via the connection resistor 64 made of a high resistance member. Thereby, a voltage can be applied to each metal back layer without affecting the discharge scale between the substrates. In this embodiment, in consideration of the influence on the image display, the common electrode 63 is provided outside the display area (area where the image is displayed).

  A spacer is arranged between the front substrate and the rear substrate in order to support the atmospheric pressure acting on these substrates. The position of the spacer may be any place that does not affect the image display, such as a place other than a region where a phosphor layer that emits light to display an image is provided. The spacer is a plate-like spacer extending to the outside of the display area, and its end is provided so as to surround the potential regulating electrode (the display area and the common electrode on the front substrate) provided on the peripheral edge of the front substrate. Potential regulating electrode). The potential regulating electrode may be formed on the front substrate on the inner side of the region where the front substrate and the frame member are in contact with each other, or may overlap the region. In this embodiment, the display area is rectangular.

  Next, the most characteristic positional relationship between the common electrode and the spacer in the image display apparatus according to the present embodiment will be described. FIG. 1 is a diagram showing the positional relationship between the common electrode and the spacer according to the present embodiment. Conventionally, the common electrode is provided so as to surround the dividing member in a plane parallel to the front substrate. For this reason, the common electrode intersects with the spacer in a plane parallel to the front substrate, and there is a problem that electric discharge is likely to occur near the intersection. In this embodiment, the common electrode is provided so as not to cross the spacer in a plane parallel to the front substrate. For example, as shown in FIG. 1, the common electrode 13 is a linear common electrode (width is not particularly limited) along one side of the display region. In this embodiment, since the spacer is provided in parallel with one side of the display area on the surface parallel to the front substrate, the common electrode and the spacer are also parallel. As a result, the anode voltage can be applied to the divided metal back layer 11 without the common electrode 13 and the spacer 15 crossing each other. Note that as long as the common electrode and the spacer are parallel to each other in a plane parallel to the front substrate, the common electrode and one side of the display region may not be parallel. As long as the common electrode does not intersect the spacer in a plane parallel to the front substrate, the common electrode and the spacer may be arranged in any manner.

  In this embodiment, since the common electrode 13 and the spacer 15 do not intersect with each other, the occurrence frequency of partial destruction of the common electrode that occurs when the common electrode 13 and the spacer are in contact with each other can be reduced. Therefore, the frequency of occurrence of electric field concentration due to partial destruction of the common electrode (that is, the frequency of occurrence of discharge) can be reduced. Further, even if a discharge between the front substrate and the rear substrate occurs in the vicinity of the spacer 15, since the low resistance region like the common electrode 13 does not exist in the vicinity, the expansion of the discharge scale (secondary discharge; It is possible to prevent discharge induced between the common electrode and the spacer. Specifically, the discharge current can be reduced to a scale that does not damage the electron-emitting devices and the drive circuit on the back substrate.

  Using the front substrate as described above, an image display device using a surface conduction electron-emitting device was fabricated, and the occurrence of discharge was evaluated. In other words, on the plane parallel to the front substrate, discharge generation was evaluated in the image display device in which the common electrode was arranged outside the region where the spacer is located and outside the region where the electron-emitting device is provided (display region). It was. In such an image display device, the discharge scale in the vicinity of the spacer is suppressed, and the occurrence of discharge in the region where the electrically low resistance member is provided (the region where the common electrode is provided) has not been confirmed.

  As described above, according to the image display device according to the present embodiment, the common electrode is arranged on the surface parallel to the front substrate so as not to cross the spacer, and the breakdown voltage is stable over a long period of time. An image display device having the above characteristics can be provided.

FIG. 1 is a diagram illustrating a positional relationship between the common electrode and the spacer according to the present embodiment. FIG. 2 is a diagram illustrating a positional relationship between the common electrode and the spacer in the conventional image display device. FIG. 3 is a diagram for explaining a phenomenon in which discharge is induced when the spacer and the common electrode are in contact with each other, and FIG. 3A is an image in which physical destruction of the common electrode does not occur. FIG. 3B is a cross-sectional view of the display device, and FIG. 3B is a cross-sectional view of the image display device in which physical destruction of the common electrode occurs. FIG. 4 is a cross-sectional view of an image display device for explaining a phenomenon in which discharge is induced when the spacer and the common electrode are not in contact with each other. FIG. 5 is a diagram illustrating a path of a current flowing from the common electrode due to discharge. FIG. 6 is a diagram for explaining the arrangement of the metal back layer and the common electrode. FIG. 7 is a perspective view of the image display apparatus according to the present embodiment. FIG. 8 is a diagram illustrating a part of a cross section of the image display apparatus according to the present embodiment.

Explanation of symbols

11, 21, 61, 83 Metal back layer 12, 22, 62 Split member 13, 23, 35, 45, 55, 63 Common electrode 14, 24, 64 Connection resistance 15, 25, 34, 44, 54 Spacer 16, 26 , 37, 47, 57 Potential regulating electrode 31, 41, 51, 71 Front substrate 32, 42, 52, 72, 84 Rear substrate 33, 43, 53, 73 Frame member 36, 46, 56 Display region 38, 48, 58 , 86 Wiring 81 Phosphor layer 82a Phosphor layer 82b Light shielding layer 85 Electron emitting device

Claims (6)

A front substrate having a fluorescent layer and a metal back layer;
A back substrate having electron-emitting devices;
A spacer disposed between the front substrate and the back substrate;
With
The metal back layer is composed of a plurality of divided metal back layers separated from each other,
The front substrate has a common electrode for applying a voltage to the plurality of divided metal back layers,
The image display apparatus, wherein the common electrode is provided so as not to intersect the spacer in a plane parallel to the front substrate. The image display apparatus according to claim 1, wherein the common electrode is provided outside a display area where an image is displayed on the front substrate. The shape of the display area where the image is displayed is a rectangle,
The image display device according to claim 1, wherein the common electrode is a linear common electrode along one side of the display region. The image display device according to claim 1, wherein the spacer is a plate-like spacer extending to the outside of a display area where an image is displayed. On the front substrate, a potential regulating electrode is provided so as to surround the display region and the common electrode,
The image display device according to claim 4, wherein an end of the plate-like spacer is connected to the potential regulating electrode. The image display device according to claim 4, wherein the common electrode is provided in parallel to the plate-like spacer on a plane parallel to the front substrate.

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