JP2005302574A - Image display device - Google Patents

Abstract

The present invention provides an image display device with improved reliability by suppressing the scale of discharge generated between substrates and preventing destruction and deterioration of electron-emitting devices and phosphor screens and circuit destruction.
A first substrate 10 on which a fluorescent screen is formed and a second substrate 12 on which a plurality of electron emission sources 18 are provided are arranged to face each other. A plurality of electron beam passage holes 26 are formed between the first and second substrates, and a support substrate 24 is provided. A plurality of spacers are erected on one surface 24a of the support substrate. The support substrate has a first surface 24a in contact with the first substrate, a second surface 24b facing the second substrate with a gap, and a plurality of electron beam passage holes 26 respectively facing the electron emission sources. Yes. When the diameter of each electron beam passage hole is D, the plate thickness T of the support substrate is formed to be D / 2 or more.
[Selection] Figure 5

Description

  The present invention relates to a flat-type image display device including a pair of substrates arranged opposite to each other and an electron emission source provided on the inner surface of one substrate.

  2. Description of the Related Art In recent years, various flat-type image display devices have attracted attention as next-generation lightweight and thin display devices that replace cathode ray tubes (hereinafter referred to as CRTs). For example, a surface conduction electron-emitting device (hereinafter referred to as SED) is being developed as a kind of field emission device (hereinafter referred to as FED) that functions as a flat display device.

  The SED includes a first substrate and a second substrate that are arranged to face each other at a predetermined interval, and these substrates form a vacuum envelope by joining peripheral portions to each other through rectangular side walls. ing. A phosphor layer of three colors is formed on the inner surface of the first substrate, and on the inner surface of the second substrate, a large number of electron-emitting devices corresponding to each pixel are arranged as an electron emission source for exciting the phosphor. . In order to support an atmospheric pressure load acting between the first substrate and the second substrate and maintain a gap between the substrates, a plurality of spacers are disposed between the two substrates. A support substrate is provided between the first substrate and the second substrate, and a plurality of spacers are erected on the support substrate. Further, a plurality of electron beam passage holes through which electron beams emitted from the electron-emitting devices pass are formed in the support substrate (Patent Document 1).

When displaying an image in the SED, an anode voltage is applied to the phosphor layer, and an electron beam emitted from the electron-emitting device is accelerated by the anode voltage to collide with the phosphor layer. As a result, the phosphor emits light and displays an image. In order to obtain practical display characteristics, it is necessary to use a phosphor similar to a normal cathode ray tube and set the anode voltage to several kV or more, preferably 5 kV or more.
JP 2002-082850 A

  In the SED configured as described above, when electrons (primary electrons) emitted from the electron-emitting device and having a high acceleration voltage collide with the phosphor layer on the inner surface of the first substrate, scattered electrons including secondary electrons and reflected electrons from the first substrate. Occurs. These scattered electrons again collide with other phosphor layers to generate unnecessary light emission. As a result, display contrast and color purity are reduced.

  In addition, the gap between the first substrate and the second substrate is set to be relatively small, such as about 1 to 2 mm, from the viewpoint of resolution, characteristics of the support member, manufacturability, and the like. Therefore, the scattered electrons generated on the first substrate side collide with the spacer disposed between the substrates, and the spacer is charged. At the acceleration voltage in the SED, the spacer is normally positively charged. In this case, the electron beam emitted from the electron-emitting device is attracted to the spacer and deviates from the original trajectory. As a result, there is a problem that electron beam mislanding occurs in the phosphor layer and the color purity of the display image is deteriorated.

  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 device with improved display quality by suppressing unnecessary light emission and electron beam trajectory shift due to scattered electrons.

  In order to achieve the above object, an image display device according to an aspect of the present invention is configured to excite the phosphor screen while being disposed to face the first substrate with a gap between the first substrate on which the phosphor screen is formed. A second substrate provided with a plurality of electron emission sources, a first surface in contact with the first substrate, a second surface opposed to the second substrate with a gap, and respectively opposed to the electron emission source A plate-like support substrate having a plurality of electron beam passage holes, and a plurality of spacers standing on the second surface of the support substrate and having tip portions contacting the second substrate; , And when the diameter of each electron beam passage hole is D, the thickness T of the support substrate is formed to be D / 2 or more.

  According to the present invention, the scattered electrons generated in the first substrate collide with the inner surface of the electron beam passage hole of the support substrate and are absorbed, thereby suppressing unnecessary light emission of the phosphor screen and charging of the spacer. An image display device with improved quality can be provided.

Hereinafter, embodiments in which the present invention is applied to an SED as a flat-type image display device will be described in detail with reference to the drawings.
As shown in FIGS. 1 to 3, the SED includes a first substrate 10 and a second substrate 12 each made of a rectangular glass plate, and these substrates have a gap of about 1.0 to 2.0 mm. Corresponding arrangement. The 1st board | substrate 10 and the 2nd board | substrate 12 comprise the flat vacuum envelope 15 by which the peripheral parts were joined through the rectangular-frame-shaped side wall 14 which consists of glass, and the inside was maintained at the vacuum.

  A phosphor screen 16 that functions as a phosphor screen is formed on the inner surface of the first substrate 10. The phosphor screen 16 is configured by arranging phosphor layers R, G, and B that emit light in red, blue, and green, and a light shielding layer 11, and these phosphor layers are formed in stripes, dots, or rectangles. ing. On the phosphor screen 16, a metal back 17 and a getter film 19 made of aluminum or the like are sequentially formed.

  On the inner surface of the second substrate 12, a number of surface-conduction electron-emitting elements 18 that emit electron beams are provided as electron emission sources for exciting the phosphor layers R, G, and B of the phosphor screen 16. Yes. These electron-emitting devices 18 are arranged in a plurality of columns and a plurality of rows corresponding to each pixel. 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. On the inner surface of the second substrate 12, a large number of wirings 21 for supplying a potential to the electron-emitting devices 18 are provided in a matrix shape, and end portions thereof are drawn out of the vacuum envelope 15.

  The side wall 14 functioning as a bonding member is sealed to the peripheral edge of the first substrate 10 and the peripheral edge of the second substrate 12 by, for example, a sealing material 20 such as low-melting glass or low-melting metal. Are joined.

  As shown in FIGS. 2 to 4, the SED includes a spacer structure 22 disposed between the first substrate 10 and the second substrate 12. The spacer structure 22 includes a support substrate 24 made of a rectangular metal plate, and a large number of columnar spacers 30 that stand integrally on the support substrate. The support substrate 24 has a first surface 24 a facing the inner surface of the first substrate 10 and a second surface 24 b facing the inner surface of the second substrate 12, and is arranged in parallel with these substrates. A large number of electron beam passage holes 26 are formed in the support substrate 24 by etching or the like.

  The electron beam passage hole 26 is formed in a rectangular shape having a major axis D. A large number of electron beam passage holes 26 are arranged in a first direction X parallel to the longitudinal direction of the vacuum envelope 15 at a first pitch via a bridge portion, and a second direction orthogonal to the first direction. Y are arranged side by side at a second pitch larger than the first pitch. Each electron beam passage hole 26 is provided such that the major axis D direction coincides with the second direction Y. The electron beam passage holes 26 are arranged to face the electron emission elements 18 and transmit the electron beams emitted from the electron emission elements.

The support substrate 24 is formed with a thickness T of 0.1 to 0.2 mm, for example, from an iron-nickel metal plate. For the major axis D of the electron beam passage hole 26, the thickness T of the support substrate 24 is
D / 2 or more, preferably D / 2 or more and less than D.

On the surface of the support substrate 24, an oxide film made of an element constituting a metal plate, for example, an oxide film made of Fe ₃ O ₄ or NiFe ₂ O ₄ is formed. Further, the surfaces 24a and 24b of the support substrate 24 and the inner surfaces of the respective electron beam passage holes 26 are covered with an insulating layer 37 mainly composed of glass, ceramic or the like, for example. Furthermore, the surfaces 24a and 24b of the support substrate 24 and the inner surface of each electron beam passage hole 26 are covered with a coating layer 38 as a high resistance film having a secondary electron generation preventing effect. The coat layer 38 is formed so as to overlap the insulating layer 37.

The coat layer 38 contains a material having a low secondary electron emission coefficient of 0.4 to 2.0, for example, a metal oxide such as chromium oxide or copper oxide, or a metal such as ITO. Various materials having such a low secondary electron emission coefficient have been found, but generally there are many good conductors having free electrons. However, as will be described later, since a relatively high voltage of about 10 kV is applied between the first substrate and the second substrate in the SED, it is necessary to select a relatively high resistance material such as an insulating material or a semiconductor as the coating layer. is there. The volume resistance value of chromium oxide is a material having a relatively high resistance of about 10 ⁵ Ωcm and a low secondary electron emission coefficient. The surface resistance of the support substrate 24 constituting the spacer structure 22 is preferably 10 ⁷ Ωcm or more. Therefore, in the present embodiment, the surface resistance value of the support substrate 24 is increased macroscopically to obtain a discharge suppressing effect by forming the coating layer 38 with a composite material obtained by mixing glass paste and chromium oxide powder.

  The support substrate 24 is provided with the first surface 24 a in surface contact with the inner surface of the first substrate 10 via the getter film 19, the metal back 17, and the phosphor screen 16. The electron beam passage hole 26 provided in the support substrate 24 faces the phosphor layers R, G, and B of the phosphor screen 16. Thereby, each electron-emitting device 18 is opposed to the corresponding phosphor layer through the electron beam passage hole 26.

  A plurality of spacers 30 are integrally provided on the second surface 24 b of the support substrate 24, and are respectively positioned between the electron beam passage holes 26. The extended end of each spacer 30 is in contact with the inner surface of the second substrate 12, here, the wiring 21 provided on the inner surface of the second substrate 12. Each of the spacers 30 is formed in a tapered shape having a diameter that decreases from the support substrate 24 side toward the extending end. For example, the spacer 30 is formed with a height of about 1.4 mm. The cross section of the spacer 30 along the direction parallel to the surface of the support substrate is substantially elliptical. Each of the spacers 30 is mainly formed of a spacer forming material mainly composed of glass as an insulating substance.

  The spacer structure 22 configured as described above acts on these substrates when the support substrate 24 comes into surface contact with the first substrate 10 and the extended end of the spacer 30 contacts the inner surface of the second substrate 12. The atmospheric pressure load is supported and the distance between the substrates is maintained at a predetermined value.

  The SED includes a voltage supply unit (not shown) that applies a voltage to the support substrate 24 and the metal back 17 of the first substrate 10. When displaying an image in the SED, an anode voltage of about 10 kV is applied to the phosphor screen 16 and the metal back 17, and the electron beam emitted from the electron emitter 18 is accelerated by the anode voltage to collide with the phosphor screen 16. Let As a result, the phosphor layer of the phosphor screen 16 is excited to emit light and display an image.

Next, the manufacturing method of SED comprised as mentioned above is demonstrated. First, a method for manufacturing the spacer structure 22 will be described.
As shown in FIG. 6, a support substrate 24 having a predetermined size, and an upper die 36a and a lower die 36b having a rectangular plate shape having substantially the same dimensions as the support substrate are prepared. As the support substrate 24, a metal plate having a plate thickness T made of Fe-50% Ni is used. The metal plate is degreased, washed and dried, and then an electron beam passage hole 26 is formed by etching. After the entire metal plate is oxidized, an insulating layer 37 is formed on the surface of the metal plate including the inner surface of the electron beam passage hole 26. Further, a coating solution in which about 30% by weight of chromium oxide (Cr ₂ O _3−α : α = −0.5 to 0.5) is mixed with glass paste on the insulating layer 37 is applied by spraying and dried. After that, the coat layer 38 is formed by firing. Thereby, the support substrate 24 is obtained. The chromium oxide raw material preferably has a particle size of 0.1 to 10 μm and a purity of 98 to 99.9%.
The coating layer 38 is not limited to the coating film, and may be a layer in which chromium oxide is formed in a thin film on the surface of the support substrate by vacuum deposition, sputtering, ion plating, or sol-gel method.

  The mold 36 is formed in a flat plate shape using a transparent material that transmits ultraviolet rays, for example, transparent silicon mainly composed of transparent polyethylene terephthalate. The molding die 36 has a flat abutting surface 41 a that abuts on the support substrate 24 and a large number of bottomed spacer forming holes 40 for molding the spacer 30. Each of the spacer forming holes 40 opens in the contact surface 41 of the mold 36 and is arranged at a predetermined interval. Each spacer forming hole 40 is formed to have a length, width, and height corresponding to the spacer 30. Thereafter, the spacer formation hole 46 of the mold 36 is filled with a spacer formation material 46. As the spacer forming material 46, a glass paste containing at least an ultraviolet curable binder (organic component) and a glass filler is used. The specific gravity and viscosity of the glass paste are appropriately selected.

  Subsequently, as shown in FIG. 7, the forming die 36 is positioned so that the spacer forming holes 40 filled with the spacer forming material 46 are positioned between the electron beam passage holes 26, and the contact surface 41 of the support substrate 24 is positioned. The first surface 24a is closely attached. As a result, an assembly including the support substrate 24 and the mold 36 is formed.

  Next, as shown in FIG. 7, the spacer forming material 46 is irradiated with 2000 mJ of ultraviolet light (UV) from the outer surface side of the support substrate 24 and the molding die 36 using, for example, an ultraviolet lamp to form a spacer. The material is UV cured. At that time, the mold 36 filled with the spacer forming material 46 is formed of transparent silicon as an ultraviolet transmitting material. Therefore, the ultraviolet rays are irradiated to the spacer forming material 46 directly and through the mold 36. Therefore, the filled spacer forming material 46 can be reliably cured to the inside.

  Thereafter, as shown in FIG. 8, the mold 36 is peeled from the support substrate 24 so that the cured spacer forming material 46 remains on the support substrate 24. Next, the support substrate 24 provided with the spacer forming material 46 is heat-treated in a heating furnace, the binder is blown from the spacer forming material, and then the spacer forming material is used at about 500 to 550 ° C. for 30 minutes to 1 hour. Firing and vitrification. As a result, the spacer 30 is integrally formed on the second surface 24 b of the support substrate 24.

  On the other hand, in the manufacture of the SED, the first substrate 10 provided with the phosphor screen 16 and the metal back 17 in advance, the second substrate on which the electron-emitting device 18 and the wiring 21 are provided and the side wall 14 is joined. 12 are prepared. Subsequently, after positioning the spacer structure 22 obtained as described above on the second substrate 12, the support substrate 24 is fixed to the second substrate 12.

  Next, the first substrate 10 and the second substrate 12 to which the spacer structure 22 is fixed are arranged in a vacuum chamber, the inside of the vacuum chamber is evacuated, and then the first substrate is bonded to the second substrate via the side wall 14. To do. Thereby, SED provided with the spacer structure 22 is manufactured.

  According to the SED configured as described above, the thickness T of the support substrate 24 is formed to be not less than D / 2, preferably not less than D / 2 and less than D with respect to the major axis D of the electron beam passage hole 26. Has been. In this case, as shown in FIG. 5, when the electron beam B emitted from the electron-emitting device 18 strikes the phosphor screen 16 through the electron beam passage hole 26, the generated secondary electrons and reflected electrons are electrons. It impinges on the inner surface of the support substrate 24 defining the beam passage hole 26 and is absorbed there. Therefore, it is possible to prevent secondary electrons and reflected electrons from projecting on the phosphor screen again, and to suppress generation of unnecessary light emission. As a result, the contrast of the display image is improved and the display quality can be improved.

  The inventors changed the plate thickness T of the support substrate 24 with respect to the major axis D of the electron beam passage hole 26 and examined the relationship between the plate thickness T, contrast, and mass productivity of the support substrate. The result is shown in FIG. As can be seen from this figure, when the thickness T of the support substrate 24 is increased, the contrast is improved, and a good contrast can be obtained by setting it to D / 2 or more. However, if the plate thickness T becomes too large, the mass productivity of the support substrate 24 decreases, and in particular, the formation efficiency of the electron beam passage holes decreases. Therefore, considering the contrast and mass productivity, the thickness T of the support substrate 24 is D / 2 or more, preferably D / 2 or more and less than D.

  Further, by absorbing and shielding the reflected electrons and secondary electrons from the first substrate 10 side by the support substrate 24, it becomes possible to suppress the charging of the spacer 30 by these scattered electrons. Therefore, it is possible to reduce the electron beam trajectory shift due to the charging of the spacer and the mislanding with respect to the phosphor layer. Therefore, the color purity of the display image can be increased and the display quality can be improved.

  Furthermore, according to the present embodiment, the surface of the support substrate 24 is covered with the coating layer 38 containing a material having a secondary electron emission coefficient of 0.4 to 2.0. Therefore, even when some of the electrons emitted from the electron-emitting device 18 collide with the surface of the support substrate 24, the generation of secondary electrons on the support substrate surface can be greatly reduced. As a result, it is possible to prevent the spacers from being charged due to secondary electrons, reduce the orbital deviation of the electron beam with respect to the phosphor layer, and further improve the display quality.

  Note that the present invention is not limited to the above-described embodiment as it is, 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. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  In the above-described embodiment, the large number of spacers are integrally formed on the support substrate. However, the present invention is not limited to this, and may be configured to stand on the second substrate. In addition, the spacer is not limited to the independent spacer used in the above-described embodiment, and other spacers such as a plate-like spacer can be used. Even in this case, similarly to the above-described embodiment. In addition, it is possible to suppress scattered electrons and improve display quality.

  In addition, the width and diameter of the spacer, the dimensions and materials of the other components are not limited to the above-described embodiments, and can be appropriately selected as necessary. The present invention is not limited to one using a surface conduction electron-emitting device as an electron source, but can also be applied to an image display apparatus using another electron source such as a field emission type or a carbon nanotube.

The perspective view which shows SED which concerns on embodiment of this invention. The perspective view of said SED fractured | ruptured along line AA of FIG. Sectional drawing which expands and shows the said SED. The top view which shows the support substrate and electron beam passage hole of said SED. Sectional drawing which expands and shows the fluorescent screen of said SED, and a support substrate. Sectional drawing which shows the manufacturing process of the spacer structure in said SED. Sectional drawing which shows the assembly which closely_contact | adhered the shaping | molding die and the support substrate. Sectional drawing which shows the state which released the said shaping | molding die. The figure which shows the relationship between the board thickness T of the said support substrate, contrast, and support substrate mass-productivity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st board | substrate, 12 ... 2nd board | substrate, 14 ... Side wall, 15 ... Vacuum envelope,
16 ... phosphor screen, 18 ... electron-emitting device, 22 ... spacer structure,
24 ... support substrate, 26 ... electron beam passage hole, 30 ... spacer.

Claims (7)

A first substrate on which a phosphor screen is formed;
A second substrate disposed opposite to the first substrate and provided with a plurality of electron emission sources for exciting the phosphor screen;
A plate-like support having a first surface in contact with the first substrate, a second surface facing the second substrate with a gap, and a plurality of electron beam passage holes each facing the electron emission source A substrate,
A plurality of spacers each standing on the second surface of the support substrate and having a tip portion in contact with the second substrate;
An image display device in which the thickness T of the support substrate is D / 2 or more, where D is the diameter of each electron beam passage hole.   The image display device according to claim 1, wherein a thickness T of the support substrate is less than D.   The image display device according to claim 1, wherein the support substrate is formed of a metal plate, and a surface of the support substrate including an inner surface of the electron beam passage hole is covered with an insulating layer.   The image display device according to claim 3, wherein a surface of the support substrate is covered with a coating layer containing a material having a secondary electron emission coefficient of 0.4 to 2.0.   The image display device according to claim 3, wherein the support substrate is formed of an alloy mainly composed of iron and nickel.   The image display device according to claim 4, wherein the material having a secondary electron emission coefficient of 0.4 to 2.0 is chromium oxide.   The image display device according to claim 1, wherein the spacer is a columnar spacer.

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