JP2752014B2 - Image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin image display device,
That is, it relates to a flat panel display.

[0002]

2. Description of the Related Art In recent years, many information devices and OA devices have been developed in response to computerization. As an image display device, a cathode ray tube having good performance with respect to color, luminance, contrast and resolution is usually used. However, in recent years, there has been an increase in the amount of information, personalization, and a need for a small, light and small market. The development of various thin panel displays has been rapidly developed in order to cope with the problems.

As a thin panel display, a flat panel display in which field-emission cold cathode microguns are arranged in a matrix has attracted attention.
Heyer et al.'S Microtips Fluorescent Display
pan Display 1986 "conference. This type of microgun is constituted by a plurality of molybdenum chips, and an electric field is applied to the chip from a gate located above the chip, and electrons are extracted from the top of the chip by the electric field effect. The anode is formed of a luminophore material and is formed at a distance of about 100 μm from the gate surface.

[0004]

However, a conventional flat panel display using a microgun of this type is thin and has a display performance superior to that of a normal CRT, but has been put to practical use for the following three reasons. Not. That is, first, since the vacuum between the cold cathode and the anode luminophore material must be maintained, the manufacturing process is complicated and the cost is high. Next, if even a small amount of foreign atoms is adsorbed on the surface of the electron emission portion of the cold cathode, the work function of the electron emission portion of the cold cathode changes significantly, so that stable electron emission characteristics cannot be realized. Finally, the residual gas ionized by the electron beam is accelerated by the anode voltage applied between the cold cathode and the luminophore material of the anode, collides with the high-energy convex cold cathode and sputters. Therefore, the life is short and the operation becomes unstable.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an image display device which can be manufactured at a low cost by a simple process and can realize a stable operation. I do.

[0006]

In order to achieve the above object, an image display apparatus according to the present invention has a substrate, an XY matrix electrode disposed on the substrate, and an XY matrix electrode disposed on the XY matrix electrode. And X is controlled by an XY matrix electrode.
An electron emission layer which selectively emits electrons from a position corresponding to the -Y matrix, an anode layer arranged opposite to the electron emission layer, and an electron emission layer arranged between the electron emission layer and the anode layer. An insulating layer through which electrons emitted from the layer toward the anode layer pass by a tunnel effect; and a phosphor layer disposed between the insulating layer and the anode layer and emitting light by electrons incident through the insulating layer. An image display device comprising:
The emissive layer is absolutely at the position corresponding to the XY matrix.
Each protrudes toward the edge layer and emits electrons from the tip
A plurality of conical discharge portions .

[0007]

[Action] In the image display apparatus of the present invention, the electron emission layer, X-Y is controlled in a matrix electrode X-Y Matrix
Cone protruding toward the insulating layer at the position corresponding to the
When the electrons are emitted from the tip of the shape emitting portion , the emitted electrons pass through the insulating layer toward the anode layer due to a tunnel effect. Here, in general, when electrons having energy equal to or higher than a certain threshold value enter the phosphor, electron-hole pairs are generated in the phosphor, and the transition of the electrons causes the phosphor to emit light. Therefore, in the present invention, when a voltage equal to or higher than a certain threshold is applied between the cathode layer and the anode layer, the phosphor layer emits light due to electrons incident through the insulating layer. Therefore, if such a light emitting operation is controlled by the XY matrix electrode, a desired image display can be obtained on the phosphor layer.

Here, according to the above-described configuration of the image display device of the present invention, the insulating layer is disposed between the electron emitting layer and the phosphor layer, and it is necessary to provide a vacuum layer as in the conventional example. Therefore, it can be manufactured in a simple process at low cost. Also, since the electron-emitting portion of the electron-emitting layer is protected by the insulating layer disposed between the electron-emitting layer and the phosphor layer, stable electron emission characteristics can be realized and the life can be extended. Operation can be stabilized.

The following examples of the present invention will further clarify such effects of the present invention, and further clarify other effects of the present invention.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a fragmentary perspective view showing an embodiment of an image display apparatus according to the present invention, FIG. 2 is an enlarged sectional view showing a part indicated by a dotted line in FIG. 1, and FIG. 1 to 2 are perspective views showing the overall appearance of the image display device, and FIGS.
FIG. 4 is an explanatory diagram illustrating a method for manufacturing the image display device illustrated in FIGS. 1 to 3.

Referring to FIGS. 1 and 2, the image display device comprises:
A transparent face plate 30 located on the display side and an anode
An electron having a transparent conductive film layer 31 as an example of an anode layer functioning as a cathode electrode, a phosphor layer 32, an electrical insulating layer 33 having a tunnel effect, and an electron emission source 34a constituting an example of a cone-shaped emission portion A cold cathode array 34 as an example of an emission layer, an electric insulating layer 35 as a core, a cold cathode array electrode 21 as an example of an XY matrix electrode functioning as a cathode electrode, and a cold cathode array 21 as an example of a substrate And a back support plate 20. In FIG. 2, the layer B on the face plate 30 side is shown.
And the layer A on the side of the back support plate 20 are shown separately, but are actually integrated.

A plurality of electron emission sources 34a having a polygonal pyramidal or conical convex shape correspond to one pixel. The electron emission source 34a has a sharp tip as an electron emission portion,
The bottoms are integrated to form a cold cathode array 34. The cold cathode array 34 is electrically surface-connected to the cold cathode array electrodes 21. Like the cold cathode array electrode 21, the cold cathode array 34 is partitioned in the form of an XY matrix, is covered by the core of the insulating layer 35, and is electrically insulated from each other. Such a tip has a tunnel effect. It is in contact with the electrical insulation layer 33. A transparent conductive film layer 31 serving as an anode electrode and a phosphor layer 32 are sequentially formed on the face plate 30, and the phosphor layer 32 is formed on the cold cathode array 34 via an electric insulating layer 33. Facing the tip.

The cold cathode array electrode (cathode electrode) 21 is
In order to address each pixel of the phosphor layer 32 applied to the face plate 30, an area defined by scanning lines 23 and signal lines 24 intersecting each other as shown in FIG. An XY matrix electrode is formed so as to be electrically insulated from the cathode electrode formed and formed in the adjacent region. That is, the flat panel display according to the present embodiment employs a driving principle substantially similar to the XY matrix method in which the scanning lines and the signal lines intersect, which are used in the liquid crystal display.

In the region where the scanning line 23 and the signal line 24 intersect,
A thin film transistor (TFT) 25 of amorphous silicon (a-Si) is formed, and the TFT 25 is used to form a cold cathode array 34 and a face plate coated with a phosphor layer 32.
An applied voltage corresponding to an arbitrary pixel between the 11 transparent conductive layers 31 can be controlled. Note that the TFT 25 of this embodiment is
It is formed in a well-known inverted staggered structure, and a gate wiring serves as a scanning line, and a signal line also serves as a source electrode and a drain electrode. Although the TFT 25 has a three-dimensional structure, it is practically flattened in accordance with the transparent conductive film layer 31.

In such a configuration, as shown in FIG. 3, a cathode electrode (cold cathode array electrode 21) on the back support plate 20 side and an anode electrode (cold cathode array electrode 21) on the face plate 30 side. When a voltage is applied between the transparent conductive film layer 31) by the phosphor voltage circuit 11 and the substrate driving circuit 12, the electron emission source 34a of the cold cathode array 34 particularly at the front end portion in contact with the electric insulating layer 33 When a strong electric field is induced, electrons are
Pass through the potential barrier between the tip of the first electrode and the electrical insulating layer 33 by a tunnel phenomenon and enter the phosphor layer 32.

Here, light is emitted by the phosphor layer by incident electrons.
It is considered that an electron-hole pair is generated in 32 and light is emitted by the transition of this electron.In order for the incident electron to contribute to light emission, it is necessary to have energy equal to or greater than the energy generated by the electron-hole pair. There is. That is, a voltage is applied between the cold cathode array electrode 21 and the transparent conductive film layer 31 so that the incident electrons have energy equal to or higher than the energy generated by the electron-hole pairs.

Next, a method of manufacturing the image display device will be described with reference to FIGS. Here, as described above, the layer A on the side of the back support plate 20 shown in FIG. 2 is almost the same as the active matrix type electrode of the known liquid crystal display, and therefore the description is omitted. In the semiconductor layer of the TFT 25, inexpensive glass can be used as a substrate, and a-Si which can easily enlarge the screen is used.

Next, the structure of the layer B on the side of the face plate 30 shown in FIG. 2 will be described in detail. First, as shown in FIG. Layer 31,
A phosphor layer 32 and an electric insulating layer 33, that is, a tunnel layer are formed.
In this embodiment, first, a transparent glass substrate having a thickness of 1.1 mm is used as the material of the face plate 30, and then, the material of the transparent conductive film layer 31 on the glass substrate is In-Sn-O.
Mainly used (ITO) or Sn O _2, the film thickness of about 0.2
It was formed to a thickness of μm. The formation method is a sputtering method in which an oxide can be used as a target.
A reactive sputtering method using an n-Sn alloy or a Sn metal target was used.

As the material of the phosphor layer 32, ZnO: Zn (10 [lm /
W]) was used. The thickness of the phosphor layer 32 is experimentally manufactured in the range of 0.08 to 1.2 μm, and is 0.3 μm in the embodiment.
The formation method is such that the base temperature is 200
After film formation at ° C, a heat treatment was performed at 550 ° C for 1 hour in a vacuum (about 10 ^-4 Pa). In addition, ZnO and Zn
, And the Zn concentration was set to an appropriate value.

Here, the energy gap of the phosphor layer 32 is about 3.26 eV, and the Fermi level is about 0.04 eV below the conduction band.
V can be estimated. Then, since the threshold value of the generation energy of the electron-hole pairs is about 7.9 eV, in order to cause the phosphor layer 32 to emit light, an electric field of at least 4.68 eV is applied to the electron emission portion of the cold cathode array 34. There is a need.

The electrical insulating layer 33, that is, the tunnel layer is formed on the planarized phosphor layer 32. This electrical insulation layer 33
Is a layer that strongly affects the electron tunneling probability.
In this embodiment, the film is formed by a plasma CVD method using SiNx. In general, Si H ₄ , NH ₃ , and N ₂ are used as the source gas. In this embodiment, however, the internal stress can be arbitrarily controlled from tension to compression by adding H ₂ . The composition ratio of the electrical insulating layer 33 is slightly N-rich (X> 1.33) than the stoichiometric composition, and the film thickness is 2%.
-3 nm.

Next, as shown in FIG. 5, an electrically insulating layer (core layer) 35 serving as a core of the convex cathode array 34 is
iO ₂ , SiC, SiN _x , Ta ₂ O ₅ , and Al ₂ O ₃ are used.
Using iNx, the layers were laminated in a similar manner to a thickness of 1 .mu.m. That is, in this embodiment, the electric insulating layers 33 and 35
Can be continuously formed.

Next, a plurality of V-shaped grooves 35a as shown in FIGS. 6 and 7 were formed in parallel using a focused ion beam processing apparatus used for fine processing of LSI. In this case, an Au-Si-Be liquid metal ion source is used as the ion source of the focused ion beam, and the acceleration energy is 40 to 300 kV.
The V groove 35a is formed so as to reach a half of the distance to the electric insulating layer 33. Further, such a beam has a Gaussian shape and a beam diameter of about 0.1 μm.
Preferred is m.

Further, as shown in FIG. 8 to FIG.
A plurality of V-grooves 35b were formed in parallel so as to be orthogonal to 35a. At this time, the processing depth was controlled so that the tip of the pyramid-shaped concave portion 35c formed at the intersection with the V-groove 35a accurately reached the electrical insulating layer 33. FIG. 8 shows a side cross section in this case, and FIG. 9 shows numerical values of the depth of the intersection region.
FIG. 10 is a perspective view of FIG. That is, as shown in FIG. 9, since the V-groove is formed twice, the point where the apex of each V-groove intersects becomes the deepest (numerical value “2” in the drawing), and this intersection reaches the electrical insulating layer 33.

Next, as shown in FIG. 11, a metal, which is a material of the convex cathode array 34, is deposited by a sputtering method, a vapor deposition method or the like so as to fill the concave portions 35a to 35c of the electric insulating layer 35, and the surface is formed. By flattening, a cathode array 34 having a pyramid-shaped electron emission source 34a corresponding to the recess 35c was formed. In this embodiment, the material of the cathode array 34 is Al.
Was used. The layer B on the side of the face plate 30 and the layer A on the side of the back support plate 20 formed in this way are combined with the cathode array 34.
When the cold cathode array electrodes 21 are closely contacted and electrically connected to each other, a flat panel display as shown in FIGS. 1 to 3 is completed.

The screen size of this flat panel display is 110 × 90 mm ² (corresponding to 6 inches) and the number of pixels is 25
6 × 256, the number of projections of the electron emission source 34a is 1 per pixel
When formed as 815 (= 33 × 55), the operating characteristics are
When the cathode-anode voltage was about 10 V, the screen luminance was about 100 cd / m ² . Therefore, a voltage of several hundred volts is required in the conventional device, but a voltage of several tens of volts is sufficient in the structure of the present invention, so that it can be put to practical use.

As a means for improving the luminous efficiency, it is desirable to use a high-quality thin film that reduces the scattering of tunnel electrons in the electric insulating layer 33 serving as a tunnel layer. In the embodiment, the SiNx amorphous film is used. However, the single crystal film of the electric insulating layer 33 may be formed by using MBE (Molecular Beam Epitaxy) technology or atomic layer epitaxy technology. It is effective to increase the capacitance of the layer 33. In this embodiment, the V-grooves 35a and 35b are formed by a focused ion beam processing apparatus, but may be formed by electron beam exposure and hot molecular beam dry etching. Further, although ZnO: Zn is used as the material of the phosphor layer 32, a color image can be displayed by using phosphors of three primary colors of red, blue and green instead.

[0028]

As described above in detail, according to the image display device of the present invention, the electron emission layer which emits electrons under the control of the XY matrix electrode, and the electron emission layer are arranged to face the electron emission layer. Between the insulating layer and the anode layer, wherein the insulating layer is disposed between the electron emitting layer and the anode layer, and the electrons emitted from the electron emitting layer toward the anode layer pass through a tunnel effect. in the image display device having a phosphor layer which emits light by electrons entering through the insulating layer is disposed
The electron emission layer has a position corresponding to the XY matrix.
In the device, each projecting toward the insulating layer
Has a plurality of cone-shaped emission portions, each of which can be manufactured at a low cost by a simple process, and can realize a stable electron emission characteristic, prolong the life, and stabilize the operation. can do.

As a result, according to the present invention, an inexpensive thin image display device having excellent reliability and stability can be realized.

[Brief description of the drawings]

FIG. 1 is a fragmentary perspective view showing an embodiment of an image display device according to the present invention.

FIG. 2 is an enlarged sectional view of a main part showing a part shown by a dotted line in FIG.

FIG. 3 is a perspective view showing an overall appearance of the image display device shown in FIGS. 1 and 2;

FIG. 4 is an explanatory view showing a method of manufacturing the image display device shown in FIGS.

FIG. 5 is an explanatory diagram showing a method of manufacturing the image display device shown in FIGS.

FIG. 6 is an explanatory diagram showing a method of manufacturing the image display device shown in FIGS.

FIG. 7 is an explanatory diagram showing a method of manufacturing the image display device shown in FIGS.

FIG. 8 is an explanatory diagram showing a method for manufacturing the image display device shown in FIGS.

FIG. 9 is an explanatory diagram showing a method of manufacturing the image display device shown in FIGS.

FIG. 10 is an explanatory diagram showing a method of manufacturing the image display device shown in FIGS.

FIG. 11 is an explanatory diagram showing a method for manufacturing the image display device shown in FIGS.

[Explanation of symbols]

 20 Back support plate 21 Cold cathode array electrode 31 Transparent conductive layer 32 Phosphor layer 33 Insulating layer (tunnel layer) 34 Cold cathode array 34a Electron emission source 35 Insulating layer (core layer)

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroshi Akagi 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-50-2487 (JP, A) (58) Investigated Field (Int.Cl. ⁶ , DB name) H01J 31/15

Claims (1)

(57) [Claims] 1. A substrate, an XY matrix electrode disposed on the substrate, and an XY matrix electrode disposed on the XY matrix electrode and controlled by the XY matrix electrode to correspond to the XY matrix. An electron-emitting layer that selectively emits electrons from the selected position, an anode layer that is arranged to face the electron-emitting layer, and the electron-emitting layer that is arranged between the electron-emitting layer and the anode layer. An insulating layer through which electrons emitted toward the anode layer pass through due to a tunnel effect; and fluorescent light that is disposed between the insulating layer and the anode layer and emits light by electrons incident through the insulating layer. Image with body layer
In the display device, the electron emission layer may include the XY matrix.
At the position corresponding to the
Multiple cone-shaped emission that emits electrons from the tip respectively
The image display apparatus characterized by having a part.