JP2000182510A - Field emission element and field emission type display device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations in the amount of electron emission by keeping a gap between electrodes constant. SOLUTION: A cathode electrode 3 made of conductive material is formed in stripes on an insulating cathode substrate 2, a film-like emitter layer 4 made of conductive material having substantially the same width as the cathode electrode 3 is formed in stripes on the cathode electrode 3, glass beads 5 acting as insulating support members are fixed on both sides of the emitter layer 4 on the cathode substrate 2, and a film-like gate electrode 7 having porous portions is formed on surfaces of the glass beads 5. The distance between the cathode electrode 3 and the gate electrode 7 is defined by the diameter of the glass beads 5, and thus the gap between them is kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a field emission device as an electron source, and to a field emission display device for performing a desired display by projecting electrons emitted from the field emission device onto a phosphor.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing the structure of a conventional field emission display.

A field emission display device 21 shown in FIG. 5 has a cathode electrode 23 formed on a substrate 22, an insulating layer 24 formed on the cathode electrode 23, and an insulating layer 24.
A diamond cathode 25 formed in a stripe shape within an aperture 24a of
A field emission device 27 including an opening 26a and a gate electrode 26 formed on the insulating layer 24 is provided.
A stripe-shaped anode electrode 2 orthogonal to the diamond cathode 25 is provided on the inner surface of the face plate glass 28 facing the substrate 22 on which the field emission element 27 is formed.
9 are formed. A phosphor layer 30 is formed on the anode electrode 29 so as to face the diamond cathode 25.

In the field emission display device 21 having the above structure, when a predetermined potential difference is maintained between the cathode electrode 23 and the anode electrode 29, electrons are emitted from the surface of the diamond cathode 25, and the emitted electrons are gated. The light passes through the opening 26 a of the electrode 26 and collides with the phosphor layer 30 on the anode electrode 29. Thus, a desired image is displayed.

[0005]

In the above-mentioned conventional field emission display device 21, the distance between the cathode electrode 23 and the gate electrode 26 is maintained by the insulating layer 24.
However, since the insulating layer 24 is formed by a screen printing method, and the insulating paste that forms the insulating layer 24 has fluidity, as shown in FIG.
The printed insulating layer 24 has a drooping portion around the aperture 24a.

Therefore, the surface of the gate electrode 26 formed on the insulating layer 24 cannot be made smooth, and the gate electrode 26 cannot be formed at a uniform height. When the height of the gate electrode 26 varies, the distance between the cathode electrode 23 and the gate electrode 26 also varies.

As a result, even if the potential difference between the cathode electrode 23 and the anode electrode 28 is kept constant, the electric field intensity on the surface of the diamond cathode 25 changes, and the emission amount of electrons emitted from the diamond cathode 25 varies. As a result, the desired image cannot be displayed due to uneven light emission.

Accordingly, the present invention has been made in view of the above problems, and has as its object to provide a field emission device capable of maintaining a constant gap between electrodes.
It is another object of the present invention to provide a field emission display device capable of displaying an image with extremely small emission unevenness by reducing the variation in the amount of emitted electrons.

[0009]

According to a first aspect of the present invention, there is provided a field emission device, comprising: a cathode substrate having an insulating property; a cathode electrode formed on the cathode substrate; A support having a film-like emitter layer formed on the cathode electrode, an insulating support member fixed on the emitter layer, and an opening for passing electrons emitted from the emitter layer; And a film-like gate electrode formed on the side of the member opposite to the surface in contact with the emitter layer.

According to a second aspect of the present invention, there is provided a field emission device, comprising: a cathode substrate having an insulating property; a cathode electrode formed in a stripe shape on the cathode substrate; A film-like emitter layer formed in a stripe shape with the same width; an insulating support member fixed on both sides of the emitter layer on the cathode substrate; and an opening for passing electrons emitted from the emitter layer And a film-shaped gate electrode formed on a side of the support member opposite to a surface corresponding to the cathode substrate. It is characterized by the following.

According to a third aspect of the present invention, in the field emission device according to the first or second aspect, the cathode substrate is provided with a concave portion where the emitter layer is exposed at a portion corresponding to a position where a pixel is formed. A layer is formed, and the support member is fixed in the recess.

According to a fourth aspect of the invention, in the field emission device according to any one of the first to third aspects, the support member is formed of a plurality of layers, and the outer shape of the support member decreases toward the upper layer.

According to a fifth aspect of the present invention, in the field emission device according to any one of the first to fourth aspects, a resistive layer formed of a thick film or a thin film is provided between the cathode electrode and the emitter layer. I do.

According to a sixth aspect of the present invention, there is provided a field emission display device using the field emission device according to any one of the first to fifth aspects, wherein the field emission type display device is arranged so as to face the cathode substrate, and is sealed at an outer peripheral portion thereof. An insulating and translucent anode substrate forming an envelope whose inside is held in a high vacuum state, a translucent anode electrode formed on the inner surface of the anode substrate, and the anode electrode And a phosphor layer formed thereon.

[0015]

FIG. 1 is a sectional view showing a first embodiment of a field emission device according to the present invention. The field emission device 1A (1) of the first embodiment is based on a cathode substrate 2 made of, for example, rectangular glass having insulation properties. On the cathode substrate 2, a cathode electrode 3 is formed. The cathode electrode 3 is made of, for example, Al, Nb, ITO (In
(Tin Tin Oxide). The cathode electrode 3 is formed by a vapor deposition method or a CVD (Chemical) method according to the selected material.
It is formed in a stripe shape on the cathode substrate 2 by a vapor deposition method, a printing method, or the like.

On the cathode electrode 3, an emitter layer 4 made of a thin film or a thick film is formed in a stripe shape with substantially the same width as the cathode electrode 3. The emitter layer 4 contains, as a main component, a powder such as carbon nanotube, graphite, DLC (diamond-like carbon), diamond powder, or nitride.

Further, an example of a method of forming the emitter layer 4 will be described. When carbon nanotubes are used, the emitter material is ultrasonically dispersed in ethanol, mixed well with a printing vehicle, and formed by printing. There are a method in which an emitter material is mixed and dispersed in an electrolyte solution for electrodeposition, and a method in which the emitter material is mixed with a photosensitive material to perform photolithographic patterning.

On both sides of the emitter layer 4 on the cathode substrate 2, glass beads 5 having insulating properties are provided as support members. A gate electrode 7 is formed on the glass beads 5 at right angles to the cathode electrode 3. The gate electrode 7 has an opening 7 a at a portion facing the emitter layer 4.

The glass beads 5 have a surface coated with an adhesive (binder) 6 as fixing means, and are fixed to the emitter layer 4 after drying and firing. Each glass bead 5
Have substantially the same diameter selected from, for example, several μm to 200 μm. The distance between the cathode electrode 3 and the gate electrode 7 is defined by the diameter of the glass beads 5,
The gap between them is kept constant.

The gate electrode 7 is a thin film formed by oblique vapor deposition (tilt angle of 30 ° or less) of a thin film of a predetermined pattern shape (for example, dot shape) made of a metal material such as Al or Nb. The gate electrode 7 allows electrons emitted from the emitter layer 4 to pass through the opening 7a.

The gate electrode 7 is made of, for example, Al, Ag
Alternatively, a paste made by mixing a powder made of a metal material such as a metal material and a vehicle may be printed on the glass beads 5. Alternatively, a gate electrode 7 may be formed by forming a thin film having a predetermined pattern on a sheet in advance by oblique deposition or printing, and transferring the thin film onto the glass beads 5.
In addition, the screen printing method and oblique deposition may be used in combination.

Further, the cathode electrode 3 and the emitter layer 4 may be formed all over the cathode substrate 2. In this case, the glass beads 5 are provided uniformly at a portion corresponding to a position where a pixel is formed with a predetermined gap, and are provided so as to cover other portions.

FIG. 2A is a partially enlarged plan view showing a second embodiment of the field emission device according to the present invention, FIG. 2B is a sectional view taken along line AA of FIG. 2A, and FIG. FIG. 3C is a sectional view taken along line BB of FIG. Note that components that are substantially the same as those in the first embodiment are given the same numbers, and detailed descriptions thereof are omitted.

Field emission device 1B (1) of second embodiment
Is based on an insulating cathode substrate 2 made of, for example, rectangular glass. On the cathode substrate 2, a cathode electrode 3 is formed in a stripe shape. On the cathode electrode 3, the emitter layer 4 is formed in a stripe shape with substantially the same width as the cathode electrode 3.

Cathode substrate 2 including surface of emitter layer 4
An insulating layer 8 is formed thereon. The insulating layer 8 has a concave portion 8a at a portion corresponding to a position where a pixel is formed, and the surface of the emitter layer 4 is exposed from the concave portion 8a. The insulating layer 8 is formed in a layer shape by, for example, a screen printing method of an insulating paste.

In the recess 8a of the insulating layer 8, glass beads 5 as support members are randomly dispersed. The glass beads 5 are fixed to the emitter layer 4 by an adhesive 6 as a fixing means coated on the surface.

On the glass beads 5, a gate electrode 7 'made of a porous thin film is formed so that electrons emitted from the emitter layer 4 can pass therethrough. The gate electrode 7 ′ is formed in a stripe shape so as to have a width substantially equal to that of the concave portion 8 a of the insulating layer 8 and to be orthogonal to the cathode electrode 3 and the emitter layer 4. Then, the cathode electrode 3 and the gate electrode 7 '
Form an XY matrix. The gate electrode 7 'can be formed by the oblique deposition, screen printing, or transfer method described in the first embodiment.

It should be noted that the diameter of the glass beads 5 is
It is preferable that the thickness is substantially equal to the thickness of the film. Thus, the gate electrode 7 ′ can be formed at a position (opposing position) above the emitter layer 4 without being separated at the step of the concave portion 8 a of the insulating layer 8. Also, the glass beads 5 in the recess 8a
Are preferably distributed at a uniform density.

In the second embodiment, the insulating layer 8 having the concave portion 8a is not limited to a layered one formed by screen printing. For example, glass or resin beads, glass fiber, An insulating member such as a square block made of glass or resin may be provided on the cathode substrate 2.

FIG. 3 is a sectional view showing a third embodiment of the field emission device according to the present invention. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The field emission device 1C (1) of the third embodiment
Is a modified example of the first embodiment, in which the glass beads 5 as the support members are composed of two layers, and the other configuration is the same as that of the first embodiment.

Although the glass beads 5 have a two-layer structure in the third embodiment, they may be formed in multiple layers. In the example of FIG. 3, all the glass beads 5 have substantially the same diameter. However, when the glass beads 5 are formed in multiple layers, the diameter may be reduced toward the upper layer of the glass beads 5. In addition, the surface can be made flat by reducing the unevenness of the surface. This multilayer structure of the glass beads 5 can be adopted in the first embodiment and the second embodiment.

In the third embodiment, the cathode electrode 3 and the emitter layer 4 are formed solidly on the cathode substrate 2, and a portion corresponding to a position where a pixel is formed is removed to form a support member on the emitter layer 4. Glass beads 5 may be provided in one layer or in multiple layers.

FIG. 4 is a sectional view showing an embodiment of a field emission device according to the present invention. In FIG. 4, the field emission device 1A of the first embodiment is employed, but the field emission devices 1B and 1C of the second and third embodiments may be employed.

In the field emission device 11 shown in FIG. 4, an anode substrate 12 made of glass or the like having an insulating property and a light transmitting property is disposed opposite to the cathode substrate 2 of the field emission device 1A. An outer peripheral portion between the anode substrate 12 and the anode substrate 12 is sealed to form an envelope whose inside is maintained in a high vacuum state. A display unit 13 is provided on the inner surface of the anode substrate 12.
Are formed. The display unit 13 includes, for example, an anode electrode 14 in which a transparent conductive film such as ITO is entirely formed on the entire surface of the anode substrate 12, and an electron emission from the field emission element 1 </ b> A which is entirely formed on the entire surface of the anode electrode 13. And a phosphor layer 15 that emits light of a predetermined color due to collision.

In the field emission display device 11 configured as described above, a scanning signal is applied to the cathode electrode 3 to sequentially scan, and a selection signal is applied to the gate electrode 7 in synchronization with the scanning signal. As a result, selection of a pixel to emit light is performed. When a pixel is selected, electrons are emitted from the emitter layer 4 on the cathode electrode 3, and the emitted electrons pass through the porous portion of the gate electrode 7 and pass through the phosphor layer 15 on the anode electrode 14. Then, light is emitted, and the light emission at that time is observed from the outside of the anode substrate 12.

The field emission device 11 has a configuration in which a pixel to emit light is selected by the cathode electrode 3 and the gate electrode 7, but is not limited to this configuration.
For example, the cathode electrode 3 and the emitter layer 4 are formed on the entire surface of the anode substrate 12, and the anode electrode 14 on which the phosphor layer 15 is attached and the gate electrode 7 are formed in a stripe shape at right angles to form the anode electrode 14. Alternatively, a configuration may be adopted in which a pixel that emits light by the gate electrode 7 is selected.

Further, the gate electrode 7 is formed solid on the glass beads 5, and the anode electrode 14 on which the phosphor layer 15 is adhered and the cathode electrode 7 are formed orthogonally in the form of a stripe to form the anode electrode 14 A configuration in which a pixel to emit light by the cathode electrode 7 may be selected.

Further, the anode electrode 14 is formed in a stripe shape, and phosphors of three colors of R (red), G (green), and B (blue) are separately applied to the anode electrode 14 so that R, G, and B are applied. 1
A matrix-shaped pixel is formed as a set, and the cathode electrode 3
Alternatively, a pixel may be selected by the gate electrode 7 and a signal may be applied to a predetermined portion of the anode electrode 14 to select a luminescent color to perform full-color display.

The above configuration is the same even when the field emission devices 1B and 1C of the second and third embodiments are employed.

As described above, according to the above-described embodiment, the gap between the emitter layer 4 and the gate electrode 7 can be kept constant by the glass beads (post members) 5. Specifically, by changing the diameter of the glass beads, the gap can be freely and accurately maintained between about 10 μm and about 200 μm. Thus, when the emitter layer 4 is formed of, for example, carbon nanotubes, the extraction voltage of the gate electrode 7 can be reduced to several tens of volts or less. As a result, driving becomes easy, and power consumption can be reduced. In addition, a desired image display can be performed with reduced emission unevenness without causing a variation in the emission amount of electrons emitted from the emitter layer 4 as in the related art.

When the glass beads 5 are provided directly on the emitter layer 4, the switching between the cathode electrode 3 and the gate electrode 7 can be controlled at a low voltage by changing the diameter of the beads to a small one.

When the field emission device 1B having the structure shown in FIG. 2 is employed, electrons emitted from the emitter layer 4 exposed to the concave portions 8a of the insulating layer 8 can be transferred to the porous portions of the gate electrodes 7 on the glass beads 5 in the concave portions 8a. Come out through the part. Thereby, the emission direction of the electron beam becomes linear, and the spread of the electron beam can be suppressed. As a result, even when the gap between the cathode electrode 3 and the anode electrode 13 is widened and a display device driven by applying a high voltage to the anode electrode 13 is configured, a graphic display with high luminance can be realized.

Incidentally, as the support member in each of the above-mentioned embodiments, bead made of resin, cylindrical glass fiber, square block made of glass or resin, etc. can be used in addition to the glass beads 5.

When a glass fiber is used as the support member, the distance between the cathode electrode 3 and the gate electrode 7 is determined by the diameter of the glass fiber, and the gap therebetween is kept constant. When a square block is used as the support member, the distance between the cathode electrode 3 and the gate electrode 7 is defined by the length of one side of a square surface orthogonal to the longitudinal direction, and the gap therebetween is kept constant. You.

In each embodiment, the gate electrode 7
Although a porous thin film made of a metal material such as Al has been described, the metal material may be configured to include a material having a getter function (for example, Ba). Thereby, the gas in the envelope can be efficiently adsorbed.

Although the emitter layer 4 in each embodiment is formed on the cathode electrode 3, the emitter layer 4 may be formed by lamination with a resistance layer interposed therebetween. By providing this resistance layer, variation in the emission current from the emitter layer 4 can be suppressed.

[0048]

As is apparent from the above description, according to the present invention, the gap between the emitter layer and the gate electrode can be kept constant by the support members. As a result, a desired image display can be performed with reduced light emission unevenness without causing variation in the emission amount of electrons emitted from the emitter layer.

Further, according to the structure in which the support member is directly fixed on the emitter layer, the diameter of the beads or fibers forming the support member and the length of one side of the surface orthogonal to the longitudinal direction of the square block are changed to smaller ones. This makes it possible to control the switching between the cathode electrode and the gate electrode with a low voltage.

In particular, according to the structure of the third aspect, electrons emitted from the emitter layer exposed in the concave portion of the insulating layer come out through the porous portion of the gate electrode on the glass beads in the concave portion. Thereby, the emission direction of the electron beam becomes linear, and the spread of the electron beam can be suppressed. As a result, even when the gap between the cathode electrode and the anode electrode is widened and a display device driven by applying a high voltage to the anode electrode is configured, a high-luminance graphic display can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a field emission device according to the present invention.

FIG. 2A is a plan view showing a second embodiment of the field emission device according to the present invention; FIG. 2B is a cross-sectional view taken along the line AA in FIG.

FIG. 3 is a sectional view showing a third embodiment of the field emission device according to the present invention;

FIG. 4 is a sectional view showing an embodiment of a field emission device according to the present invention.

FIG. 5 is a cross-sectional view showing a configuration of a conventional field emission display device.

[Explanation of symbols]

1 (1A to 1C): field emission device, 2: cathode substrate,
Reference numeral 3 denotes a cathode electrode, 4 denotes an emitter layer, 5 denotes glass beads (post members), 7, 7 ': gate electrode, 7a: opening, 8
... insulating layer, 8a ... recess, 11 ... field emission display device, 1
2. Anode substrate.

Claims (6)

[Claims] 1. A cathode substrate having an insulating property, a cathode electrode formed on the cathode substrate, a film-like emitter layer formed on the cathode electrode, and fixed on the emitter layer An insulating pillar member, and a film-shaped gate electrode having an opening through which electrons emitted from the emitter layer pass and formed on a side opposite to a surface of the pillar member that contacts the emitter layer. A field emission device comprising: 2. A cathode substrate having an insulating property, a cathode electrode formed in a stripe shape on the cathode substrate, and a film formed in a stripe shape on the cathode electrode and having substantially the same width as the cathode electrode. -Shaped emitter layer, an insulating support member fixed to both sides of the emitter layer on the cathode substrate, and an opening portion for passing electrons emitted from the emitter layer, A field emission device comprising: a film-shaped gate electrode formed on a side opposite to a surface facing the cathode substrate. 3. An insulating layer is formed on the cathode substrate at a portion corresponding to a position where a pixel is to be formed, the insulating layer having a recess for exposing the emitter layer, and the support member is fixed in the recess. The field emission device according to claim 1. 4. The field emission device according to claim 1, wherein the support member is formed of a plurality of layers, and has a smaller outer shape toward an upper layer. 5. The field emission device according to claim 1, further comprising a thick or thin resistive layer between said cathode electrode and said emitter layer. Field emission device according to the above. 6. A field emission display device using the field emission device according to claim 1, wherein the field emission device is disposed so as to face the cathode substrate, is sealed at an outer peripheral portion thereof, and has a high inside. An insulating and translucent anode substrate forming an envelope held in a vacuum state, a translucent anode electrode formed on the inner surface of the anode substrate, and formed on the anode electrode A field emission display device comprising: a phosphor layer;