JP2004200057A - Flat panel display - Google Patents

Abstract

Provided is a flat panel display capable of realizing further reduction in power consumption while taking advantage of a plasma display panel.
In a plasma display panel, cells as constituent units are arranged in a matrix. The cell 10 has an electron source 12 having a structure in which a lower electrode 18, a tunnel insulating layer 22 and an upper electrode 32 are stacked, and a structure in which a front plate 36 and an anode 38 are stacked. 32, an anode portion 34 disposed opposite to the electron source 12 and a gas capable of emitting ultraviolet light when excitation energy is applied between the electron source 12 and the anode portion 34. A gas sealing portion 42 is formed by being sealed by a partition 44 to be disposed, and has a structure in which phosphor layers 40 a and 40 b are formed on the inner surfaces of the partition 44 and the anode 38 that define the gas sealing portion 42.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to flat panel displays.
[0002]
[Prior art]
As a commercially available color flat panel display, there is a plasma display panel (hereinafter, referred to as PDP).
[0003]
A PDP is a display device that excites gas particles (atoms and molecules) by discharge, excites a phosphor with ultraviolet rays that can be generated by the optical transition, and obtains visible light.
[0004]
PDPs have the advantages of being self-luminous, providing a wide viewing angle, having a high speed response, and being relatively easy to produce a large screen.
[0005]
[Problems to be solved by the invention]
However, in order to make PDPs more practical, further reduction in power consumption is required.
[0006]
That is, in the PDP, the same level of power is consumed in the drive circuit as in the panel. In the drive circuit, it is necessary to perform pulse control of a high voltage in order to generate a discharge. Therefore, there is a problem that the power consumption is increased and a production cost of the drive circuit is increased.
[0007]
In addition, there is a report that only about 4% of the input power contributes to the emission of ultraviolet rays (Koichi Wani: "Power Saving of Plasma Display (PDP)", ITE, 53, No. 8.1067 (1999)). The remaining 96% of the power is lost as heat after being generated and converted into kinetic energy of particles such as ions forming the plasma in the process of starting and maintaining the discharge.
[0008]
The present invention has been made in view of the above problems, and has as its object to provide a flat panel display that can realize further reduction in power consumption while utilizing the advantages of the plasma display panel described above. .
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a flat panel display according to the present invention includes an electron source (cathode unit) having a structure in which a lower electrode, a tunnel insulating layer, and an upper electrode having a positive voltage with respect to the lower electrode are stacked. It has a structure in which a transparent substrate and a transparent anode electrode having a positive voltage with respect to the upper electrode are laminated on the transparent substrate, and the transparent anode electrode faces the electron source with the transparent anode electrode facing the upper electrode of the electron source. A gas formed by being enclosed by a partition arranged between the electron source and the anode, and a gas capable of emitting ultraviolet rays when excitation energy is applied thereto. And a sealing layer, wherein a phosphor layer is formed on an inner surface of one or both of the partition wall and the transparent anode electrode that define the gas sealing section.
[0010]
In the flat panel display according to the present invention, electrons emitted by an electric field effect due to a voltage applied to an electron source excite gas particles to generate ultraviolet light, and the generated ultraviolet light excites a phosphor. Obtain visible light.
[0011]
Thereby, the contribution ratio of the input power to the ultraviolet radiation increases, so that the power consumption for obtaining the predetermined light emission can be reduced. Further, since driving can be performed with a low driving voltage, power consumption and cost of the driving circuit can be reduced.
[0012]
In this case, a distance (d: unit cm) between the upper electrode and the transparent anode electrode, a voltage (V: unit V) applied between the upper electrode and the transparent anode electrode, and a sealing pressure of the gas. If (P: unit kPa) is set so as to satisfy the following equation,
(Equation) 15 ≦ V × d ⁻¹ × P ⁻¹ ≦ 190
Power consumption can be further reduced.
[0013]
In this case, it is preferable that the pressure at which the gas is charged falls within the range of 40 to 80 kPa.
[0014]
In this case, the gas is preferably xenon gas.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of a flat panel display according to the present invention (hereinafter, referred to as an embodiment) will be described below with reference to the drawings.
[0016]
As described above, in the PDP, the efficiency of the power applied to the panel to contribute to ultraviolet radiation is low, and most of the input power is lost as heat.
[0017]
However, it is also known that a very high efficiency portion called a positive column occurs in the discharge. For example, in the case of a positive column in Xe gas, in a calculation estimating the ratio of energy consumed for ultraviolet radiation, E / P in the positive column (a type of expression of kinetic energy of electrons, E is an electric field, and P is When the gas pressure is 38 to 110 V · cm ⁻¹ · kPa ⁻¹ (5 to 15 V · cm ⁻¹ · Torr ⁻¹ ), 90% or more of the input energy is used for ultraviolet radiation. (Yukio Okamoto, "Improvement of luminous efficiency in DC gas discharge type color display," Denki Plasma Research, EP81-22, 16 (1981)).
[0018]
For this reason, it is relatively difficult to obtain a highly efficient flat panel display if there is an electron-emitting device (hereinafter, referred to as an electron source) that can emit electrons into a gas having an E / P equivalent to a positive column. It can be easily predicted.
[0019]
However, obtaining such an electron source is not always easy.
[0020]
For example, a method using a hot cathode as an electron source is conceivable, but the electron source of this method consumes large power and it is difficult to provide an electron source for each pixel.
[0021]
On the other hand, there is a field emission display (FED) as a display device using a cold cathode as an electron source, and a Spindt type (Spindt type), a carbon nanotube type, or the like, which is currently the mainstream, is used as an electron source of this type. In a type in which there is a space between the emitter and the gate that separates electrons, a large electric field is generated in this space, and the emitter may be destroyed by ions generated by ionization of a gas having an E / P equivalent to a positive column. is there.
[0022]
The present inventors have conducted intensive studies on an electron source capable of emitting electrons into a gas having an E / P equivalent to that of a positive column, and as a result, have found that the lower electrode, the tunnel insulating layer, and the upper electrode having a positive voltage with respect to the lower electrode. It has been found that the above problems can be solved by using an electron source having a laminated structure.
[0023]
Regarding the electron sources of the flat panel display according to the present embodiment, those provided for each pixel have already been reported, and these electron sources can be used. Further, in the electron source, since the high electrolysis forming portion for generating the tunnel phenomenon is in the tunnel insulating layer and the high electrolysis forming portion is isolated from the gas, the emitter of the electron source may be destroyed by the ions of the gas. Absent.
[0024]
As such an electron source, an MIM type (Metal / Insulator / Metal type), an MIS type (Metal / Insulator / Semiconductor type), a MOS type (Metal / Oxide / Semiconductor type) or the like can be used.
[0025]
The flat panel display according to the present embodiment has a structure in which a transparent substrate, a transparent anode electrode having a positive voltage with respect to an upper electrode, and a phosphor layer are laminated together with the electron source, and the phosphor layer is formed by an electron source. And an anode portion facing the electron source. Further, a gas sealing portion is provided in which a gas capable of emitting ultraviolet rays by applying excitation energy is sealed by a partition wall disposed between the electron source and the anode portion. Then, a phosphor layer is formed on the inner wall of the gas sealing portion.
[0026]
A specific configuration example of such a flat panel display according to the present embodiment will be described with reference to FIG. 1 showing a cell corresponding to one pixel which constitutes the flat panel display.
[0027]
The cell 10 of the flat panel display uses the MIM type as the electron source (for example, see T. Kusunoki et al, Asia Display / IDW '01 Proceedings, p. 1189 (2001)).
[0028]
In the electron source (cathode unit) 12, a linear lower electrode 18 is provided on a back plate 16 provided with an undercoat film 14, and a field insulating layer 20 and a tunnel insulating layer 22 are provided on the lower electrode 18. . Further, a linear contact electrode 26 and a bus electrode 28 which are spatially orthogonal to the lower electrode 18 are provided on the tunnel insulating layer 22 with an opening (electron emission portion 24) exposing the tunnel insulating layer 22 therebetween. . Further, a protective insulating layer 30 is provided on the bus electrode 28, and an upper electrode 32 is provided on the protective insulating layer 30 and the tunnel insulating layer 26.
[0029]
As the material of each layer of the electron source 12, for the undercoat films 14, 14, for example, a laminated film of SiNx and SiO ₂ can be used, for the back plate 16, for example, soda glass can be used, and for the lower electrode 18, For example, an Al-Nd alloy can be used. For the field insulating layer 20 and the tunnel insulating layer 22, for example, anodized Al can be used. For the contact electrode 26, for example, W can be used. For the bus electrode 28, for example, an Al—Nd alloy can be used. For the protective insulating layer 30, for example, Si ₃ N ₄ can be used. For the upper electrode 32, for example, Ir, At, and Au Can be used.
[0030]
The anode part 34 is provided with an anode (transparent anode electrode) 38 on a front plate (transparent substrate) 36. The phosphor layer 40a is formed on the anode 38. The material of the front plate 36 can be, for example, soda glass, and the anode 38 can be made of a transparent material such as ITO. Further, the anode 38 may be formed in a stripe shape using an opaque material such as Al or Ag to secure a light transmitting portion. The phosphor of the phosphor layer 40a, can be suitably used the materials used for example in the PDP, for example, for the red-emitting _{(Y X Cd 1-X)} BO 3: Eu 3+, Zn 2 for the green light emitting SiO ₄ : Mn ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ²⁺ or the like can be used for emitting blue light.
[0031]
The gas sealing section 42 has a partition 44 disposed between the electron source 12 and the anode section 34. The partition 44 can be formed using, for example, lead oxide glass. The phosphor layer 40b is also formed on the inner surface of the partition 44. For example, Xe gas is sealed in the gas sealing portion 42 as a gas capable of emitting ultraviolet rays when excitation energy is applied. However, the present invention is not limited to this, and another rare gas or a mixed gas of these rare gases may be used.
[0032]
Here, the distance (d: unit cm) between the upper electrode 32 and the anode 38, the voltage V ₁ (unit V) applied between the upper electrode 32 and the anode 38, and the sealing pressure P ( (Unit kPa) is set so as to satisfy the following equation.
[0033]
(Equation) 15 ≦ V × d ⁻¹ × P ⁻¹ ≦ 190
The E / P of the gas sealed between the upper electrode 32 and the anode 38 is different from the case where electrons are generated by electric discharge as described above, and the electric field intensity is substantially constant between the upper electrode 32 and the anode 38. Therefore, E / P can be approximated by V ₁ × d ⁻¹ × P ⁻¹ .
[0034]
At this time, when the gas sealed in the gas sealing portion 42 is Xe gas, the ultraviolet light for exciting the phosphors of the phosphor layers 40a and 40b emits a resonance line from the resonance level 1 _s4 under the condition of a low sealing pressure P. (Wavelength: 147 nm), but when the sealing pressure P increases, each atom of the resonance level _1s4 and the metastable level _1s5 collides with two neutral atoms to form a diatomic molecule. And emits a relatively long excimer light having a central wavelength of 173 nm at a low vibration level. For example, it has been reported that when the gas pressure exceeds 6.7 kPa (50 Torr), the above-mentioned resonance line rapidly attenuates, and the intensity of excimer light becomes maximum when the sealing pressure P is around 53 kPa (400 Torr) (P. Millet). et al, J. Chem. Phys. 69 (1), 1 Jul. (1978)). Generally, it is considered that light of a long wavelength has less self-absorption and is advantageous.
[0035]
For this reason, in the present embodiment, a relatively high pressure of, for example, about 53 kPa is selected as the gas filling pressure P within a range of 40 to 80 kPa (300 to 600 Torr). At this time, so as to satisfy the above equation, applying the voltage V ₁ of the order of 20~100V between the upper electrode 32 and the anode 38 as the anode 38 to the upper electrode 32 is a positive voltage . At this time, the upper electrode 32 for applying a voltage V _2, for example, about 5~10V between the lower electrode 18 and the upper electrode 32 such that the positive voltage to the lower electrode 18.
[0036]
As a result, it is possible to obtain a high ultraviolet ray generation efficiency with respect to the supplied electric power.
[0037]
Also, under such conditions, the energy of the encapsulated gas particles (atoms and molecules) is considered to be about 18 V or less, which is the threshold of the acceleration voltage at which the upper electrode 32 is sputtered. (See University Press (1984)).
[0038]
By manufacturing the cells 10 configured as described above in a matrix, the flat panel display according to the present embodiment can be obtained.
[0039]
In the flat panel display according to the present embodiment, the electrons emitted by the electric field effect due to the voltage applied to the electron source 12 excite gas particles to generate ultraviolet rays, and the generated ultraviolet rays emit phosphors. Visible light is obtained by excitation.
[0040]
In the above example, the flat panel display has a mono-color display function. For example, by using three cells formed by separating phosphor layers of three primary colors of light to correspond to one pixel, a full-color display is realized. A flat panel display having a function can be obtained.
[0041]
【Example】
The present invention will be further described with reference to examples. The present invention is not limited to the embodiments described below.
[0042]
A flat panel display was manufactured by the following method.
[0043]
The electron source was produced by the following method.
[0044]
An undercoat film was formed on a back plate made of soda glass having a thickness of 3 mm by sputtering a laminated film made of SiNx having a thickness of 100 nm and SiO _{2 having} a thickness of 20 nm. Then, after forming an Al-Nd alloy by sputtering on the undercoat film, wet etching was performed to form a linear lower electrode having a thickness of 300 nm. Next, anodic oxidation using a resist film for the lower electrode and anodic oxidation after removing the resist film were performed to form a field insulating layer having a thickness of 150 nm and a tunnel insulating layer having a thickness of 12 nm. Then, W and an Al-Nd alloy were sequentially formed on the tunnel insulating layer by sputtering, and then wet-etched to form a contact electrode having a thickness of 20 nm and a bus electrode having a thickness of 100 nm, which were orthogonal to the lower electrode. Next, a protective insulating layer having a thickness of 500 μm was formed by sputtering Si ₃ N ₄ on the bus electrode. Thereafter, the electron emission portion was opened by plasma etching and wet etching. Finally, Ir, At and Au were sequentially formed by sputtering to form an upper electrode formed of a 6 nm-thick laminated film.
[0045]
The anode part was produced by sputtering ITO on a 3 mm-thick front plate made of soda glass to form an anode having a thickness of 200 nm.
[0046]
The gas filling part was produced by the following method.
[0047]
A lead oxide material was applied around the anode part by a screen printing method and baked to form a partition (rib) having a thickness (height) of 100 μm. Next, a phosphor for PDP was applied to the inner surface of the partition wall and, if necessary, the anode to a thickness of 10 μm by a screen printing method to form a phosphor layer. Next, an electron source was attached to the other side of the partition wall, thereby producing a gas sealed portion defining a sealed area. Further, Xe was introduced into the gas filling portion from the gas introducing portion, the display of which was omitted in FIG. 1, and the gas filling pressure was adjusted to 53 kPa to complete the flat panel display.
[0048]
FIG. 2 shows the contribution ratio of the applied power to the generation of ultraviolet rays when a voltage is applied to the manufactured flat panel display.
[0049]
Anode was applied voltages V ₁ between the upper electrode and the anode such that the positive voltage to the upper electrode. Further, between the lower electrode and the upper electrode as the upper electrode with respect to the lower electrode becomes positive voltage is applied a voltage V ₂ of 9V.
[0050]
In FIG. 2, the contribution of the input power on the vertical axis to the generation of ultraviolet light is calculated by measuring the density of excited Xe atoms using a laser absorption method (Kunihide Tachibana and Shaojun Feng: JOURNAL OF APPLIED PHYSICS Vol.88, No. 9: 2000).
[0051]
From FIG. 2, it can be seen that the flat panel display of the present embodiment can obtain a value exceeding 4%, which is the value of the conventional PDP, as the contribution ratio of the applied power to the generation of ultraviolet rays. For example, under a condition in which a voltage of 60 V is applied between the upper electrode and the anode, the current density is 80 mA / cm ² , and the contribution ratio of the applied power to the generation of ultraviolet light (ultraviolet light generation efficiency) at this time is as follows. The power was about 9%, which was more than twice the value of 4% of the conventional PDP. That is, the power consumption of the flat panel display of this embodiment can be significantly reduced as compared with the conventional PDP.
[0052]
In addition, the flat panel display of the present example has a region where the value of V ₁ × d ⁻¹ × P ⁻¹ is less than 15, the voltage between the upper electrode and the anode is less than 8 V, and V ₁ × d ⁻¹ × In the region where the value of P ^-1 exceeds 190 and the voltage between the upper electrode and the anode exceeds 100 V, it has been found that the contribution ratio of the applied power to the generation of ultraviolet rays sharply decreases. In the former case, the electrons do not reach the divergence energy of Xe, and in the latter case, they are in the discharge region.
[0053]
In this case, the driving voltage applied between the lower electrode and the upper electrode is 9 V as described above, which is lower than the driving voltage of the conventional PDP of about 200 V, so that the power consumption of the driving circuit is reduced. And cost can be reduced.
[0054]
【The invention's effect】
According to the flat panel display according to the present invention, an electron source having a structure in which a lower electrode, a tunnel insulating layer and an upper electrode having a positive voltage with respect to the lower electrode are stacked, and a transparent substrate and a transparent substrate with respect to the upper electrode The anode has a structure in which a transparent anode electrode is laminated to be a positive voltage, and the transparent anode electrode faces the upper electrode of the electron source. A gas-encapsulating portion formed by enclosing a gas capable of emitting ultraviolet rays with a partition disposed between the electron source and the anode portion, and a partition and a transparent anode electrode defining the gas-encapsulating portion Since the phosphor layer is formed on one or both of the inner surfaces, the power consumption of the panel can be reduced, and the power consumption and the manufacturing cost of the driving circuit can be reduced. .
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a cell constituting a flat panel display according to an embodiment of the present invention.
FIG. 2 is a diagram showing a relationship between a voltage applied between an upper electrode and an anode and a contribution ratio of applied power to generation of ultraviolet rays in the flat panel display of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Flat panel display cell 12 Electron source 14 Undercoat film 16 Back plate 18 Lower electrode 20 Field insulating layer 22 Tunnel insulating layer 26 Contact electrode 28 Bus electrode 30 Protective insulating layer 32 Upper electrode 34 Anode part 36 Front plate 38 Anode 40 a 40b Phosphor layer 42 Gas sealing portion 44 Partition wall d Distance between upper electrode and anode V ₁ Voltage applied between upper electrode and anode V ₂ Voltage P applied between lower electrode and upper electrode Gas P Fill pressure

Claims (4)

An electron source having a structure in which a lower electrode, a tunnel insulating layer, and an upper electrode having a positive voltage with respect to the lower electrode are stacked;
It has a structure in which a transparent substrate and a transparent anode electrode having a positive voltage with respect to the upper electrode are laminated on the transparent substrate, and the transparent anode electrode faces the electron source with the transparent anode electrode facing the upper electrode of the electron source. An anode part arranged
A gas capable of emitting ultraviolet light by being supplied with excitation energy includes a gas sealing portion formed by being sealed by a partition wall arranged between the electron source and the anode portion,
A flat panel display comprising a phosphor layer formed on an inner surface of one or both of the partition wall and the transparent anode electrode defining the gas filled portion. The distance (d: unit cm) between the upper electrode and the transparent anode electrode, the voltage (V: unit V) applied between the upper electrode and the transparent anode electrode, and the gas filling pressure (P: 2. The flat panel display according to claim 1, wherein the unit (kPa) is set so as to satisfy the following expression.
(Equation) 15 ≦ V × d ⁻¹ × P ⁻¹ ≦ 190 3. The flat panel display according to claim 2, wherein the gas pressure is in a range of 40 to 80 kPa. The flat panel display according to claim 1, wherein the gas is xenon gas.

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