Patent Grant
7812514
1. Field of the Invention
The present invention relates to an image forming apparatus and a light emitter substrate.
2. Description of the Related Art
Conventionally, an image forming apparatus which acts as an electron-emitting apparatus using an electron-emitting device has been known. More specifically, as the image forming apparatus like this, for example, a flat type electron displaying panel in which an electron source substrate on which a number of cold cathode electron-emitting devices are formed and an anode substrate which is equipped with a metal back for accelerating the electrons emitted by the electron-emitting devices and or a transparent electrode and a fluorescent body are parallelly opposed to each other has been known. Here, the space between the electron source substrate and the anode substrate has been exhausted and vacuumized. Such an image forming apparatus using a field-emission electron-emitting device {or an FEA (Field Emitter Array) device} is well known.
To produce an image in the electron beam displaying panel, a predetermined voltage is first applied sequentially to the row-direction wirings 105 and the column-direction wirings 106 which are arranged like a matrix, thereby selectively driving the predetermined electron-emitting device 108 positioned at the cross point of the matrix. Then, electrons thus emitted are irradiated to the fluorescent body 110, thereby obtaining a light spot. Incidentally, in order to obtain the high-luminance light spot by accelerating the emitted electrons, a high voltage is applied to the transparent electrode 116 through a high voltage terminal Hv to have a high voltage as compared with the electron-emitting device 108. Here, although according to the performance of the fluorescent body, the voltage to be applied is set to several hundreds volt (V) to several tens kilovolt (kV). Accordingly, a distance d between the rear plate 101 and the face plate 102 is generally set to several hundreds micrometer (μm) to several millimeter (mm) so that vacuum dielectric breakdown (that is, electric discharge) due to the applied voltage does not occur.
In the image forming apparatus like this, as illustrated in
To solve such a conventional problem as described above, each of Japanese Patent Application Laid-Open Nos. H06-338273 and 2002-033058 discloses a proper method. In the relevant method, for example, as illustrated in
However, in the above-described conventional display panel, following problems may occur.
As described above, if the rib having the predetermined height is arranged on the black member on the side of the surface of the face plate opposite to the rear plate, the halation can be controlled. However, when aiming to achieve further high contrast and high color purity, it is necessary to further heighten the rib if it intends to sufficiently reduce the halation by the above method.
If the height of the rib increases, an amount of materials to be used to form the rib increases, and thus gas emitted from the rib increases. Consequently, since a degree of vacuum decreases, the fluorescent body, the electron source and the like deteriorate, whereby there is a fear that reliability decreases. Further, since the amount of the used materials increases, costs for manufacturing the apparatus increases resultingly. Furthermore, since it is difficult to form a more higher rib with a high degree of accuracy, it is difficult to obtain a desired shape of the rib.
The present invention, which has been completed in consideration of such conventional problems as described above, aims to provide an image displaying apparatus or the like which can achieve high image quality and high reliability.
To attain such an object, an image forming apparatus according to the present invention is characterized by comprising: a first substrate which has plural electron-emitting devices; and a second substrate which is arranged oppositely to the first substrate, and has plural light emission members for emitting light in response to irradiation of electrons and black members for mutually separating the plural light emission members from others, and is characterized in that the plural light emission members are arranged so that the adjacent light emission members emit light of mutually different colors, and a convex member, which projects from the surface of the light emission member, is provided within the area of each light emission member.
Further, a light emitter substrate, according to the present invention, which comprises a substrate, plural light emission members, provided on the substrate, for emitting light in response to irradiation of electrons, and black members for mutually separating the plural light emission members from others, is characterized in that the plural light emission members are arranged so that the adjacent light emission members emit light of mutually different colors, and a convex member, which projects from the surface of the light emission member, is provided within the area of each light emission member.
According to the present invention, it is possible to provide the image displaying apparatus which can achieve high image quality and high reliability.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, the exemplary embodiments of the present invention will be described in detail with reference to the attached drawings. Here, it should be noted that the dimensions, the materials, the shapes, the relative configurations and the like described in the embodiments do not limit the scope of the present invention as far as there is no specific description.
An image forming apparatus according to the present invention is the apparatus which forms images by irradiation of electron beams, and contains an FEA (Field Emitter Array) device, an MIM (Metal Insulator Metal) device, a surface-conduction electron-emitter device (SED) or the like as an electron-emitting device. In particular, since the surface-conduction electron-emitter device has a simple constitution and thus can be manufactured easily, a large number of surface-conduction electron-emitter devices can be formed over a wide area. For this reason, the surface-conduction electron-emitter device is a preferable in a case where the present invention is applied.
In the following, it is assumed that the present invention is applied to an image displaying apparatus which is composed of plural light emitters, plural devices for exciting the plural light emitters, and a driving circuit for outputting a driving signal to drive the plural devices. However, since the image displaying apparatus having the plural light emitters, the plural devices and the driving circuit has been well known, the detailed description thereof will be omitted. Namely, the image displaying apparatus will be roughly described.
As illustrated in
The illustrated electron-emitting device 8 is the surface-conduction electron-emitter device (SED) on which a conductive thin film having an electron-emitting portion is connected between device electrodes constituting a pair. In the embodiment, there is provided a multi electron beam source on which the N×M surface-conductive electron-emitter devices are arranged, and the M row direction wirings 5 and the N column direction wirings 6 are respectively matrix-arranged at equal intervals. Further, in the embodiment, scanning signals are applied to the row direction wirings 5 respectively through lead terminals Dx1 to Dxm, and modulation signals (image signals) are applied to the column direction wirings 6 respectively through lead terminals Dy1 to Dyn.
The electrodes of the row direction wirings 5 and the column direction wirings 6 can be formed by applying silver paste in a screen printing method. Further, for example, these electrodes can be formed by using photolithography. In addition to the above silver paste, various kinds of conductive materials can be used as the materials of the electrodes of the row direction wirings 5 and the column direction wirings 6.
Next, the spacer 3 will be described hereinafter. In the image displaying apparatus which uses electron beams as in the present invention, it is necessary in principle to form a vacuum within the image displaying panel. For this reason, since atmospheric pressure is applied to the face plate 2 and the rear plate 1, it is necessary to provide the spacer 3 acting as an interval definition member between the face plate 2 and the rear plate 1. Further, since the spacer 3 is arranged at the position between the face plate 2 and the rear plate 1 to which high voltage is applied, withstand voltage is necessary for the spacer 3. Incidentally, although it is not described in the embodiment, a function film may occasionally be formed on the surface of the spacer 3.
The side wall 4 is arranged at the periphery between the rear plate 1 and the face plate 2, and the joint between the rear plate 1 and the side wall 4 and the joint between the face plate 2 and the side wall 4 are respectively sealed by frit glasses or the like.
The face plate 2 is the anode substrate, and the fluorescent body, the black member, the side wall, the metal back and the like are formed on the surface, opposed to the real plate 1, of the face plate 2. It is needless to say that the substrate of the face plate 2 is transparent. However, the substrate of the face plate 2 preferably has the mechanical intensity and the thermal property which are the same as those of the substrate of the rear plate 1. Further, in case of forming a wide screen display panel, it is preferably possible to use a soda-lime glass, a potassium glass, a glass substrate obtained by laminating SiO2 to the soda-lime glass in liquid phase epitaxy, a sol-gel process, sputtering or the like.
The metal back is provided on the surface of the face plate 2 opposed to the rear plate 1, and a positive high voltage Va is applied from a not-illustrated external power supply to the metal back through a high voltage terminal Hv. Here, it is necessary for the metal back to act as the electrode for applying an acceleration voltage to accelerate the electrons from the electron-emitting device, transmit the accelerated electrons, and act as the reflection film for extracting the light emitted by the fluorescent body to an observer side. Further, it is necessary for the metal back to act as the antistatic device for the fluorescent body. The metal back is characterized by having an extremely thin metal film which is preferably made of aluminum through which the electrons can be easily transmitted. A voltage of 5 kV to 15 kV is applied to the metal back. The metal back may be formed by vacuum vapor deposition after filming already known in the field of CRT.
Since the display panel according to the embodiment performs color display, fluorescent materials of three primary colors (red, green and blue) are divisionally applied to the fluorescent body, and the fluorescent material of each color is applied like, e.g., a stripe. Further, a black member is provided between the adjacent stripes of the different-color fluorescent materials. The objects of providing the black member are to prevent misregistration of the displayed colors by preventing light emission of the adjacent colors even if electron beam irradiation positions are some misregistered, prevent deterioration of display contrast by preventing reflection of outside light, and prevent charging of the fluorescent body due to electron beams. The black member can be formed by a material mainly containing black lead (graphite), but can be formed by another material if it is suitable for the above objects. Further, the fluorescent materials of three primary colors may be respectively applied like, in addition to the stripe, a delta and the like.
The electrons emitted from the electron-emitting device 8 are attracted to the face plate 2, and the attracted electrons are accelerated and irradiated to the fluorescent body. At this time, if the incident electrons have sufficient energy to cause the fluorescent body to emit light, a light spot appears there. Generally, in the fluorescent body which is used in the CRT for a color TV, sufficient luminance and color can be obtained by accelerating and irradiating electrons by an acceleration voltage of several kilovolt (kV) to several tens kilovolt (kV). Since the fluorescent body for the CRT has extremely high performance although it is relatively inexpensive, the fluorescent body of this type is preferably used also in the present invention.
Here, a rib and halation will be described in detail with reference to
Plural fluorescent films 10 acting as the light emission members respectively constituted by the fluorescent bodies of three light colors (red (R), green (G), blue (B)) are arranged on the side of the face plate 2 opposed to the rear plate, and black members 12 respectively separating the adjacent fluorescent films 10 are provided between the adjacent films. Further, a metal back 11 is provided on the fluorescent films 10 and the black members 12.
Here, if it is assumed that electron is emitted from an electron-emitting source, the electron emitted from the electron-emitting source is accelerated by high voltage applied to the metal back 11, and the accelerated electron is advanced to the face plate 2. Here, the acceleration voltage to be applied to the metal back 11 is about 5 kV to 15 kV preferably. Since the accelerated electron has high energy, it passes the metal back 11 without serious energy loss. After then, the passed electron is irradiated to the fluorescent body (that is, the fluorescent body of B (blue) in this case).
Here, since a part of the irradiated electrons is reflected with almost energy maintained, back-scattered electrons (also called, reflected electrons, backside-scattered electrons, or elastically scattered electrons) of high energy are produced. The back-scattered electrons advancing toward the rear plate 1 (
To reduce this halation, it may form the rib for shielding the back-scattered electrons. As illustrated in
As illustrated in
As illustrated in
It can be understood from the graph of
As described above, to reduce halation, it may provide the rib on the black member and enlarge the aspect ratio thereof. Therefore, it can be understood that it only has to narrow the aperture width to lower the height of the rib as maintaining the halation reduction effect.
Here, a convex member which is the characterizing portion of the present invention will be described with reference to
As illustrated in
To reduce the influence to the electron beams as much as possible, the width of the convex member 15 is made narrow. More specifically, the width of the convex member 15 is made narrower than the width of the rib 14. Further, to obtain the effect of shielding the back-scattered electrons, the height of the convex member 15 from the face plate 2 is made the same as the height of the rib 14 from the face plate 2.
Further, as illustrated in
Incidentally, metals such as Ni, Cu, Ag, Al and the like and dielectric materials such as a low-melting glass frit, a ceramic, polyimide and the like can selectively be used as the materials of the rib 14 and the convex member 15. Here, a method, which is frequently used for a plasma display and the like, of forming the rib 14 and the convex member 15 by using paste containing the ceramic, the low-melting glass frit and the like can be preferably used for the reasons of cost advantages, easiness of manufacturing, and the like. Further, the black material may be included in the material of the rib 14 so that the rib 14 can also function as the black member 12. Furthermore, as the method of manufacturing the rib 14 and the convex member 15, it is possible to use a screen printing method, a photolithography method, a sandblasting method, a mold transfer method by a concave plate, and the like.
As described above, according to the embodiment of the present invention, the convex member 15 is formed in the area of the fluorescent film 10 for each color, and the convex member 15 projects from the surface of the fluorescent film 10. Consequently, since it is possible to lower the heights of the rib 14 and the convex member 15 as reducing halation by shielding the back-scattered electrons. For this reason, since it is possible to reduce an amount of the materials for constituting the rib 14 and the convex member 15, it is possible to suppress by reducing discharged gases from these materials that the fluorescent film 10, the electron source and the like deteriorate. Consequently, it is possible to provide the image forming apparatus which possesses higher reliability and can display high-contrast and high-quality images without color misregistration.
Hereinafter, the present invention will further be described in detail by using several examples.
Hereinafter, the first example of the present invention will be described with reference to
On the face plate 2 used for the image displaying apparatus of the present example, each of the plural fluorescent films 10 is provided like a stripe between the black members 12. Each of the fluorescent films 10 is composed by any one of the fluorescent bodies of three colors (red (R), green (G), blue (B)), and the fluorescent films 10 are repetitively arranged in order of R, G, and B. Therefore, the plural fluorescent films 10 are arranged so that the adjacent fluorescent films 10 respectively emit light of mutually different colors. The convex member 15, which is provided at the center of the area of the fluorescent film 10 of each color, extends along the length direction of the fluorescent film 10.
With respect to the fluorescent film 10 of each color, the width between the black member 12 and the convex member 15 is 70 μm, and the height (Z direction in
Subsequently, the rear plate 1 which is used in the present example will be described with reference to
Subsequently, the spacer 3 to be used in the present example will be described with reference to
Subsequently, the manufacturing method of the face plate to be used in the present example will be described with reference to
(Process 1) Initially, the face plate 2 which is composed of a low alkali glass substrate of which the thickness is 1.8 mm is washed.
(Process 2) The black member 12 of which the thickness (corresponding to the above-described height, i.e., the Z direction in
(Process 3) Subsequently, the paste of the materials of the rib 14 and the convex member 15, of which the thicknesses from the glass surface (corresponding to the above-described heights, i.e., the Z direction in
(Process 4) Subsequently, a fluorescent material is applied to the aperture portion formed by the ribs 14, the convex member 15 and the black members 12. More specifically, the fluorescent materials of R, G, B three colors are separately applied respectively with a desired thickness by the screen printing method. Here, a P22 fluorescent material is used as the relevant fluorescent material. After then, the applied fluorescent material is baked, and thus the fluorescent film 10 having the above-described shape is formed (
(Process 5) Subsequently, the metal back 11 is formed by a filming method which has been already known in the field of CRT. That is, an acrylic emulsion adhesive is first applied on the fluorescent film 10 by a spray method, and then the obtained film is dried. Then, aluminum is formed by vacuum vapor deposition, and the formed aluminum is baked in the atmosphere to eliminate organic constituents therefrom. Thus, the metal back 11 having the above-described shape is formed (
The rear plate 1 and the face plate 2, which were formed as described above, are arranged and sealed to be opposed to each other via the side wall 4, thereby forming the image displaying apparatus as illustrated in
Subsequently, the second example of the present invention will be described with reference to
As well as the first example, a high contrast and high color purity image in which halation has been reduced can be displayed by the image forming apparatus in the present example.
Subsequently, the third example of the present invention will be described with reference to
In the image displaying apparatus of the present example, the fluorescent film 10 of each color is positioned between the black member 12 and the convex member 15 and between the adjacent convex members 15, and the width, the length and the height (corresponding to the above-described height, i.e., the Z direction in
The same effect as that in the first example can be obtained even in the image displaying apparatus according to the present example. Further, in the image displaying apparatus according to the present example, excellent image display in which color purity is higher (color mixture is lower) as compared with the first example can be achieved.
Subsequently, the fourth example of the present invention will be described with reference to
In the image displaying apparatus of the present example, the width, the length and the thickness (corresponding to the above-described height, i.e., the Z direction in
In the present example, the convex members 15 are manufactured by patterning a resist film with use of X-ray, injecting slurry ceramics into the obtained pattern grooves, and then baking the whole.
The same effect as that in the first example can be obtained even in the image displaying apparatus according to the present example. Further, in the image displaying apparatus according to the present example, excellent image display in which color purity is higher (color mixture is lower) as compared with the first example can be achieved.
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. 2007-200936, filed Aug. 1, 2007, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-200936 | Aug 2007 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5578899 | Haven et al. | Nov 1996 | A |
| 6756729 | Na et al. | Jun 2004 | B1 |
| 20080012467 | Negishi | Jan 2008 | A1 |
| Number | Date | Country |
|---|---|---|
| 1 172 836 | Jan 2002 | EP |
| 06-338273 | Dec 1994 | JP |
| 2002-33058 | Jan 2002 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20090033203 A1 | Feb 2009 | US |
