JP2008191616A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device which has a lighter display screen and can be made thin and compact. <P>SOLUTION: The display device 1 is constituted by stacking first and second display panels one over the other, wherein the second display panel is formed of a field emission display (CNT-FED) panel 4 that uses carbon nanotubes 7A, and the first display panel is formed of a liquid crystal display panel 2 and disposed on a display surface side of the second display panel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a display device that performs display by stacking two display devices, and more particularly to a display device that uses a field emission display for one display panel.

2. Description of the Related Art There is a display device that performs display by arranging two display panels in an overlapped manner for the purpose of improving the stereoscopic effect and realism of a display screen. Such display devices are also introduced in patent literature (for example,
See Patent Document 1 below).

FIG. 2 is a cross-sectional view showing a display device used in a ball game machine according to the following patent document.
A display device 20 used in a ball game machine disclosed in Patent Document 1 below includes two LCDs (
As shown in FIG. 2, each of the LCDs 21 and 22 is a known thin film transistor (TFT) type color LCD, as shown in FIG. And the rear LCD 22 are arranged in parallel. The LCDs 21 and 22 are well-known, for example, the polarizing film 2 from the rear side.
6, a glass substrate 27, a driving unit 28 made of a thin film transistor, an alignment film 29, a liquid crystal 30 in which particles serving as spacers are dispersed, an alignment film 29, a common electrode 31 made of ITO, a protective film 32,
The color filter 33, the glass substrate 27, and the polarizing film 26 are arranged in a laminated state. Further, a backlight 34 made of a planar light emitter is attached to the back surface of the rear LCD 22.
Japanese Unexamined Patent Publication No. 6-339575 (paragraph [0012], FIG. 2)

By the way, a liquid crystal display panel (LCD) generally has a very low light transmittance.
% Or less. In the display device 20 described above, such an LCD having a very low light transmittance is used.
Since two sheets 21 and 22 are stacked one above the other, the light transmittance is further reduced, for example, 1% or less. Therefore, a light source that emits higher luminance is required for the backlight 34 that illuminates the liquid crystal panels 21 and 22.

As a light source of this type of backlight, a cold cathode fluorescent tube or a light emitting diode is usually used. In order to obtain higher luminance, the number or number of cold cathode fluorescent tubes or light emitting diodes must be increased. Therefore, for example, if the number of cold-cathode fluorescent tubes is increased and the number thereof is increased, the power consumption increases proportionally and the amount of heat generation increases, which may adversely affect other components. For example, the optical sheet is affected by this heat, and the individual sheet materials constituting the optical sheet are thermally deformed, causing wrinkles and deflections in these sheet materials, which makes it difficult to view the display image. . The cold cathode fluorescent tube has a predetermined thickness (for example, an outer diameter of 2 to 8 mm).
In addition, since it is formed of a tubular body having a length, a considerable storage space is required when it is incorporated in the backlight, and there is a limit to the reduction in thickness, size, and weight of the display device. Furthermore, in a backlight using a cold cathode fluorescent tube or a light emitting diode, the light source is a linear or point light source, so that it is difficult to obtain uniform luminance and uneven luminance tends to occur. For this reason, usually, a plurality of optical sheets composed of a diffusion sheet, a lens sheet, and the like are laminated on the light emitting surface, and brightness unevenness is reduced by these optical sheets. For this reason, arrangement | positioning of an optical sheet becomes essential and thickness reduction is further restrict | limited.

In recent years, this type of stereoscopic image display device has been used in various devices as represented by game devices, and the range of use thereof tends to be further expanded. On the other hand, various kinds of specifications are required for display device manufacturers of this type, for example, thin / small, light weight, high brightness / low power consumption, long life / maintenance free. Yes. However, conventional backlights using cold cathode fluorescent tubes, light emitting diodes, and the like and display devices using two liquid crystal panels cannot meet these requirements.

Therefore, the present invention was made in order to solve such problems of the prior art,
An object of the present invention is to provide a display device in which a display screen is brightened and can be reduced in thickness and size.

In order to achieve the above object, a display device of the present invention is a display device in which a first display panel and a second display panel are overlapped, and the second display panel is a field emission using carbon nanotubes. The display panel is formed of a display (CNT-FED) panel, and the first display panel is formed of a liquid crystal display panel and is disposed on the display surface side of the second display panel.

According to the above invention, a field emission display (CNT-FED) using carbon nanotubes as the second display panel located on the back side of the display device of the present invention.
Since the panel is used, as in the prior art, it is possible to suppress a significant decrease in luminance due to the light irradiated from the light source (backlight) passing through the liquid crystal display panel having a low light transmittance twice. That is, the light source and the second display panel are integrally formed by the CNT-FED panel, and the light emitted from the CNT-FED panel has already been output as an image reflecting a predetermined display signal. Since the light emitted from the CNT-FED panel only passes through the first display panel, a reduction in luminance can be significantly suppressed. Specifically, if the light transmittance of the liquid crystal display panel is 10%, the light from the light source can be reduced to 1/10 compared to the conventional case. In addition, since the carbon nanotube can be formed on the catalytic metal layer with a very high density per unit area, for example, the diameter of the needle-like tip portion is about several nanometers to several tens of nanometers, Electrons can be emitted. Moreover, this electron emission does not decrease the amount of emission even when the applied voltage is lowered, and the power consumption is very small. Furthermore, since the carbon nanotube itself is extremely tough,
There is almost no wear and it has a long life. Therefore, this display device can be made thinner and smaller than those of the prior art, and can be made maintenance-free with high brightness, low power consumption and long life.

In addition, since display is performed using two display panels as described above, if one display image is displayed on the two display panels, a three-dimensional display can be performed. This 2
If two different display images are displayed on one display panel, the amount of information that can be displayed at one time can be dramatically increased.

Moreover, according to the display device of this aspect, the CNT-FED panel is
A cathode comprising a cathode electrode laminated on the surface, an insulating layer and a gate electrode formed in a lattice shape on the cathode electrode, and the carbon nanotube formed in a region surrounded by the insulating layer and the gate electrode A substrate,
An anode substrate formed of an anode electrode formed in a region facing the region where the carbon nanotubes are disposed, and a plurality of color phosphor layers provided on the anode electrode;
It is preferable that a vacuum atmosphere is formed between the cathode substrate and the anode substrate.

According to the display device of this aspect, the carbon nanotube is formed on the catalyst metal layer by laminating a catalyst metal layer on the cathode electrode, and the phosphor layer is an electron that develops red, green, and blue. It is preferable that it is formed of a line excitation type phosphor.

According to the display device of this aspect, it is preferable that a moire countermeasure sheet is disposed between the display panel and the FED panel.

According to the above aspect, it is possible to suitably remove moire generated between the first and second display panels by disposing the moire countermeasure sheet.

Hereinafter, the best embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a display device for embodying the technical idea of the present invention, and is not intended to specify the present invention for this display device. Other embodiments within the scope are equally applicable.

FIG. 1 is a longitudinal sectional view showing a display device according to an embodiment of the present invention in an exploded manner into two first and second display panels.

The display device 1 includes two first and second display panels (2, 4) and a moire countermeasure sheet 15 interposed between both display panels. The first display panel is a known liquid crystal panel (LCD)
2), and the second display panel is a carbon nanotube-based field emission display (hereinafter referred to as “CNT-F”).
ED ”).

The liquid crystal panel 2 includes a TFT array substrate 2a provided with a plurality of source lines, gate lines, and thin film transistors (TFTs), and a color filter substrate 2b provided with a common electrode and a color filter. The color filter substrate 2b is bonded to each other with a seal frame interposed therebetween.

The TFT array substrate 2a is formed of a base material having optical transparency and electrical insulation, for example, a glass substrate. On the surface of the substrate, a plurality of source lines and gate lines are wired in a matrix at predetermined intervals, and TF is formed in a region where each source line and gate line intersect.
T is provided. A region surrounded by each source line and gate line is a region where individual pixels are formed.

On the other hand, the color filter substrate 2b is formed of a base material having optical transparency and electrical insulation, for example, a glass substrate, like the TFT array substrate 2a. On the surface of the color filter substrate 2b, regions corresponding to the respective pixels of the TFT array substrate 2a are individually partitioned by a black matrix (not shown). Each of the divided areas has red (R), green (
Color filters 4R, 4G, and 4B made of G) and blue (B) are provided. Furthermore, a common electrode made of a transparent conductive material is formed on the color filter substrate 2b. For example, ITO (Indium Tin Oxide) is used as the transparent conductive material forming the common electrode.

In assembling the liquid crystal panel 2, first, the two substrates 2a are arranged so that the pixel region on the TFT array substrate 2a and the color filters 4R, 4G, 4B on the color filter substrate 2b face each other.
An empty liquid crystal panel is formed by bonding the surfaces of the substrates 2a and 2b with a seal frame (not shown) interposed therebetween. Next, both substrates 2 of this empty liquid crystal panel
Liquid crystals are sealed in a space surrounded by a and 2b and the seal frame. And each board | substrate 2a, 2b
Polarizing plates 3a and 3b are provided on the respective outer surfaces, and the assembly is completed.

The CNT-FED panel 4 includes a cathode substrate 5 provided with a cathode electrode 6 and an anode substrate 12 provided with an anode electrode 13, and these substrates 5 and 12 are bonded together with a seal frame interposed therebetween. It has a configuration.

The cathode substrate 5 is formed of a base material having electrical insulation, such as glass, quartz, alumina, or silicon. The cathode substrate 5 has a display area at the center of the surface, and a cathode electrode 6 is formed in the display area, and a plurality of electron-emitting devices 7A are formed on the surface of the cathode electrode 6. The formed catalyst electrode layer 7 is formed.

The catalyst electrode layer 7 having these electron-emitting devices 7A is formed by forming the cathode electrode 6 on the cathode substrate 5 and then arranging the insulating layer 8 and the gate electrode 9 in a matrix at a predetermined interval. It is formed at a location surrounded by the gate electrode 9. Specifically, it is formed on the bottom surface of the gate hole 10 surrounded by the gate electrode 9 stacked on the insulating layer 8.

The cathode electrode 6 is made of, for example, chromium, titanium, aluminum, or tungsten, and is formed on the cathode substrate 5 in a striped manner at a predetermined interval or over the entire display region.

When the cathode electrode 6 is formed in the entire display area so that it intersects (orthogonally) the cathode electrode 6 when the cathode electrode 6 is formed in a stripe shape, the gate electrode 9 is one pixel region. It is formed in a matrix form with a predetermined interval so as to surround. The insulating layer 8 is disposed below the gate electrode 9. These cathode electrode 7 and insulating layer 8
First, the cathode electrode 6 is formed on the cathode substrate 5, the insulating layer 8 and the gate electrode 9 are provided on the cathode substrate 5, and the gate hole 10 is formed using a mask or the like. Formed by a typical semiconductor manufacturing method.

The electron-emitting device 7A is formed of a plurality of carbon nanotubes. The carbon nanotubes 7A are grown and formed in the vertical direction on the catalytic metal layer 7 stacked on the cathode electrode 6. For the catalytic metal layer 7, for example, cobalt, nickel, iron, yttrium, or an alloy thereof is used. The carbon nanotubes 7A are formed by using, for example, a chemical vapor deposition (hereinafter referred to as “CVD”) method.
In this CVD method, for example, a carbon nanotube such as acetylene and a catalytic metal are chemically reacted at a high temperature to grow carbon nanotubes. Since this CVD method is known, a detailed description is omitted. Carbon nanotubes 7 formed by this method
A can be grown on the catalytic metal layer 7 at a very high density per unit area. For example, the tip portion has a needle shape, and the needle tip portion can be formed to have an extremely small diameter, for example, about several nm to several tens of nm, compared with the length of the carbon nanotube.

On the other hand, the anode substrate 12 is formed of a base material having optical transparency and electrical insulation, for example, a glass substrate. The surface of the anode substrate 12 is partitioned by a black matrix so as to correspond to each pixel of the cathode substrate 5, and anode electrodes 13 made of a transparent conductive material are respectively disposed in the partitioned regions. On the electrode 13, phosphors, specifically, electron beam excitation phosphors 14R, 14G, and 14B that develop red (R), green (G), and blue (B) colors.
Is provided. The transparent conductive material constituting the anode electrode 13 is formed of a transparent conductive material such as ITO.

The assembly of the CNT-FED panel 4 is as follows. First, the surfaces of both the substrates 5 and 12 are opposed so that the carbon nanotubes 7A formed on the cathode substrate 5 are opposed to the color filters 14R, 14G and 14B of the anode substrate 12. A seal frame 11 is interposed between the two substrates 5, 1
2 are bonded together to form a space S therein. Then, the assembly is completed by vacuum-sealing the space S so as to be in a vacuum atmosphere. The thickness of the space S of the CNT-FED panel having this configuration can be formed to about 100 μm to 700 μm, for example.

Next, the operation of this CNT-FED panel will be described.
A cathode electrode control circuit, a gate electrode control circuit, and an anode electrode control circuit (not shown) are connected to the cathode electrode 6, the gate electrode 9 and the anode electrode 13 of the CNT-FED panel 4, respectively. It has come to be added. That is, the cathode electrode 6 has a negative voltage from the cathode electrode control circuit, the gate electrode 9 has a positive voltage from the gate electrode control circuit, and the anode electrode 13 has a higher positive voltage than the gate electrode 9 from the anode electrode control circuit. Applied.

In this state, when displaying an image, for example, a scanning signal is input to the cathode electrode 6 from the cathode electrode control circuit, and a video signal is input to the gate electrode 9 from the gate electrode control circuit. Alternatively, a video signal is input to the cathode electrode 6 from the cathode electrode control circuit, and a scanning signal is input to the gate electrode 9 from the gate electrode control circuit. As a result, a voltage is applied between the cathode electrode 6 and the gate electrode 9, whereby an electric field is concentrated on the tip of the carbon nanotube 7 A, and electrons are released through the energy barrier by the quantum tunnel effect into the vacuum. . The emitted electrons are attracted to the anode electrode 12 and moved to the anode substrate 12 side, and collide with the phosphors 14R, 14G, and 14B of the anode substrate 13. As a result, each of the phosphors 14R, 14G, and 14B emits light when excited by the collision of electrons, so that a desired image can be displayed on the CNT-FED panel 4 by controlling the light emission position in units of pixels. Can do.

The display device 1 is formed by using the liquid crystal panel 2 and the CNT-FED panel 4 and laminating these panels 2 and 4 with a moire countermeasure sheet 15 interposed therebetween. The laminated structure is bonded using, for example, a transparent adhesive. However, when the panels 2 and 4 are stacked, the color filters 4R, 4G, and 4B of the liquid crystal panel 2 and the phosphors 14R, 14G, and 14B of the CNT-FED panel 4 are arranged in a straight line as viewed from the display surface. In addition, the color filters 4R, 4G, and 4B and the phosphors 14R and 14 are arranged on a straight line.
Laminate so that G and 14B have the same color.

Since the display device 1 having the above-described configuration uses the CNT-FED panel 4 using the carbon nanotubes 7A as field emission electron sources, the characteristics of the carbon nanotubes 7A can be effectively used. That is, the carbon nanotubes 7A can be arranged on the catalytic metal layer 7 with a very high density per unit area.
Since the diameter of the needle-shaped tip portion is about several nanometers to several tens of nanometers, many electrons can be efficiently emitted from these tip portions. Moreover, the electron emission does not decrease even when the applied voltage is lowered, and the power consumption is very small. Further, since the carbon nanotube 7A itself is extremely tough, it has almost no wear and has a long life. Therefore, this display device can be made thinner and smaller than those of the prior art, and can be made maintenance-free with high brightness, low power consumption and long life.

As mentioned above, although preferred embodiment of this invention was described, this invention can be variously changed without being limited to this. For example, the liquid crystal panel 2 and the CNT-FED panel 4 may be arranged at a predetermined interval without being laminated and fixed. However, even in this case, the color filters 4R, 4G, 4B of the liquid crystal panel 2 and the phosphor 1 of the CNT-FED panel 4 are used.
4R, 14G, and 14B shall be fixed so as to be arranged in the same color on a straight line.

This display device is useful as a display device in a wide range of fields such as computer terminals, industrial use, medical use, and broadcast use.

FIG. 1 is an exploded vertical sectional view of a display device according to an embodiment. FIG. 2 is a cross-sectional view of a conventional display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Display apparatus 2 ... Liquid crystal panel (1st display panel) 3a, 3b ... Polarizing plate 4 ... CNT-
FED panel (second display panel) 4R, 4G, 4B ... color filter 5 ... cathode substrate 6 ... cathode electrode 7 ... catalytic metal layer 7A ... carbon nanotube (electron emitting device)
DESCRIPTION OF SYMBOLS 8 ... Insulating layer 10 ... Gate hole 11 ... Sealing frame 12 ... Anode substrate 13 ... Anode electrode 14R, 14G, 14B ... Phosphor 15 ... Moire countermeasure sheet

Claims (4)

A display device in which a first display panel and a second display panel are stacked, wherein the second display panel is a field emission display (CNT-FE) using carbon nanotubes.
D) A display device formed by a panel, wherein the first display panel is formed by a liquid crystal display panel and is disposed on the display surface side of the second display panel. The CNT-FED panel is
A cathode comprising a cathode electrode laminated on the surface, an insulating layer and a gate electrode formed in a lattice shape on the cathode electrode, and the carbon nanotube formed in a region surrounded by the insulating layer and the gate electrode A substrate,
An anode substrate formed of an anode electrode formed in a region facing the region where the carbon nanotubes are disposed, and a plurality of color phosphor layers provided on the anode electrode;
The display device according to claim 1, wherein a vacuum atmosphere is formed between the cathode substrate and the anode substrate. The carbon nanotube is formed on a catalytic metal layer formed by laminating a catalytic metal layer on the cathode electrode, and the phosphor layer is formed of an electron beam excited phosphor that emits red, green, and blue. The display device according to claim 2. The display device according to claim 1, wherein a moire prevention sheet is disposed between the display panel and the FED panel.

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