JPH10283956A - Field emission display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a field-emission display device which can provide a high- brightness, clear image. SOLUTION: Stripes of anodes 1-1-1-6 are vertically formed on the lower surface of an anode substrate 11, and anode terminals A, B are provided in such a way as to be connected thereto in the form of comb teeth. A protective film 12 is formed on the anode substrate 11 and the anodes in a pattern having a plurality of window openings in and near the anodes. Phosphor dots 2 of R, G, and B are applied to the window openings. Focusing electrodes 3 are horizontally arranged in stripes on the lower surface of the protective film 12 and between the adjacent window openings, are formed to be integrated together at right and left ends by a vertically extending connecting wire film, and are connected to a common focusing electrode terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a field emission type display device, and more particularly, to a field emission type color display device.

[0002]

2. Description of the Related Art An electric field applied to a metal or semiconductor surface is 10
^At about ⁹ [volts / m], electrons pass through the barrier due to the tunnel effect, and electrons are emitted in a vacuum even at room temperature. This is called field emission (Field Emissin). A cathode that emits electrons according to such a principle is a field emission cathode (Field Emissin Catho).
de, hereinafter simply referred to as FEC). By making full use of semiconductor microfabrication technology, it is possible to create a surface emission type FEC composed of micron-sized FEC, and a field emission type display device (Field Emissin)
Display), hereinafter simply referred to as FED),
It is used as an electron emission source for an electron beam device for lithography.

FIG. 4 is an explanatory view of a conventional anode switch drive type color FED. In the figure, 1-1 to 1-5 are anode electrodes, 2 is a phosphor dot, 11 is an anode substrate,
13 is a cathode substrate, 31-1 to 31-4 are cathode electrodes, 32-1 and 32-2 are gate electrodes, and 33 is a spacer.

In this color FED, a cathode substrate 13 on which an FEC is formed and an anode substrate 11 on which anode electrodes 1-1 to 1-5 are formed are opposed to each other.
The gap between the substrates is kept constant by a spacer 33, the outer peripheries of both substrates are sealed by side portions (not shown), and the inside is kept in a vacuum state. In this figure, in order to make the structure easy to understand, the gap between the two substrates is enlarged.

[0005] On the cathode substrate 13, cathode electrodes 31-1 to 31-4 are formed in a stripe shape, on which an insulating layer having a plurality of openings is formed. A conical emitter cone is formed on 1-31-4. A plurality of gate electrodes 32-1 and 32-2 are formed on the insulating layer in a stripe shape, and extend in a direction orthogonal to the longitudinal direction of the cathode electrodes 31-1 to 31-4. The gate electrodes 32-1,
32-2 has a plurality of holes as shown, corresponding to the opening of the insulating layer and the emitter cone described above. The above-mentioned cathode electrode, emitter cone and gate electrode constitute a Spindt-type FEC.

On the other hand, on the lower surface of the transparent anode substrate 11, transparent anode electrodes 1-1 to 1-5 are formed in stripes in parallel with the above-mentioned cathode electrodes 31-1 to 31-4. Every other anode electrode 1-1, 1-3,
Are connected in common at one end, and every other anode electrode 1-2, 1-4 ... is connected at the other end (not shown). That is, they are commonly connected alternately in a comb-tooth shape.

The anode electrodes 1-1 to 1-5 are made of ITO.
A thin film of (conductive indium oxide) is used, on the lower surface of which a plurality of phosphor dots 2 are provided with anode electrodes 1-1 to 1-1.
1-5 in the form of dots at predetermined intervals in the longitudinal direction. The anode electrode 1-1 is red (R), the anode electrode 1-2 is green (G), and the anode electrode 1-3 is blue (B). ), Three kinds of phosphor dots 2 of R, G, B, such as red (R), are alternately arranged on the anode electrode 1-4 to constitute a display unit of a color FED.

[0008] The cathode electrodes 31-1 to 31-31 on the FEC side
.. And the gate electrodes 32-1 and 32-
When a gate voltage of several tens of volts is applied between the specific row 2..., For example, between the cathode electrode 31-1 and the gate electrode 32-1, electrons are emitted from the emitter cone at the intersection of both electrodes. You.

Comb-shaped anode electrodes 1-1, 1-3, 1
-5... And comb-shaped anode electrodes 1-2, 1
For −4,..., The cathode electrode 31 on the FEC side
In synchronization with the selective scanning of the columns -1 to 31-4, switching driving is performed so that a positive voltage is applied to the anode electrode immediately above the column. As in the above example, the cathode electrode 31-
When a gate voltage is applied between the first electrode 1 and the gate electrode 32-1, the anode electrodes 1-1, 1-3, 1-5,.
A positive anode drive voltage is applied to the side.

[0010] The electrons emitted from the emitter cone are among the anode electrodes 1-1 to 1-5 to which a positive voltage is applied.
It hits the phosphor dot 2 located immediately above. In this example, a red (R) phosphor dot on the front left on the anode electrode 2-1 emits light. At that time, the anode electrodes 1-1 to 1
By performing switching driving so that one of the adjacent ones of 1-5,... Has a positive voltage, the other has a zero voltage or a negative voltage, the emission electrons from the FEC are focused, and the target phosphor dot is formed. Electrons reach only 2. Generally, in the case of FED, the emission image is
Observation is made through the phase plate glass from the upper surface side on the anode substrate 11 side.

As described above, the voltage applied between the cathode electrode and the gate electrode on the FEC side is scanned, and the driving of the comb-shaped anode electrode in synchronization with the scanning is performed to emit light from the plurality of phosphor dots 2. Can be controlled.

In the above-described conventional color FED, the anode electrodes 1-1 to 1-5 are formed in a stripe shape or a zigzag shape, and a focusing electric field is formed on the anode electrode side by the above-described switching drive, so that the FED of the FED is formed. The convergence in the horizontal direction (the horizontal direction in the drawing) can be improved. As a result, the rate at which the emitted electrons impinge on the adjacent phosphor dots 2 of different colors decreases. Also, FE
There is a margin in the horizontal positioning accuracy between the C side and the anode electrode side. As a result, it can be said that there is no problem in terms of color bleeding.

However, in such a driving method, the FED
Has no focusing action in the vertical direction (depth direction shown).
FIG. 5 is a diagram showing a simulation result of an electron beam trajectory in the conventional FED shown in FIG. 21 is an electron beam orbit, 22 is an equipotential surface, and 23 is a current density. This figure is a view of the electron beam trajectory in the cross section in the vertical direction (the depth direction shown in FIG. 4) of FIG. 4, and shows the FEC (field emission cathode) in which an electron beam emission portion is divided into two. 9 shows a simulation result. An electron beam emitted from an FEC (field emission cathode) often strikes a phosphor dot immediately above. However, the part that emits the electron beam is
Due to the effect of the division, the spot diameter of the electron beam has a spread.

Thus, in such a driving method, F
Since there is no focusing action in the vertical direction of the ED, the rate of impact on the phosphor dots adjacent in the vertical direction does not decrease, and there is little margin of positioning accuracy in the vertical direction. As a result, there is a problem that it is difficult to obtain a clear image with high luminance.

In the above-described conventional color FED,
Since the ITO film surface of the anode electrodes 1-1 to 1-5 and the glass surface of the anode substrate 11 are exposed inside the vacuum vessel, gas is released by bombardment of an electron beam or the like, and the inside vacuum is released. There was a problem of lowering the degree.

As described in Japanese Patent Application Laid-Open No. 6-349426, a black insulating layer is formed around a phosphor dot layer, and a conductive layer is deposited on the black insulating layer. An FED has been proposed in which electrons are charged and electrons are focused by applying a large negative voltage to the conductive layer. However, for the insulating layer and the conductive layer, pattern formation and specific presentation of the materials have not been achieved. Further, there is no description about a structure suitable for colorization in which the anode electrode is driven by switching.

[0017]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is possible to obtain a high-brightness and clear image, reduce the degree of vacuum, and improve the withstand voltage of the anode electrode. It is an object of the present invention to provide a field emission type display device capable of preventing a decrease in the display.

[0018]

According to a first aspect of the present invention, in a field emission display device, a plurality of anode electrodes are formed on an anode substrate, and a protective film includes a plurality of windowed portions formed on the anode electrode. And a pattern formed in the vicinity thereof on the anode substrate and the anode electrode, wherein phosphor dots are formed on the window, and a focusing electrode is formed on the protective film between the windows. It is.

Therefore, the electron beam can be focused on the phosphor dots by the focusing electrode. The ratio of projecting to the adjacent one of the phosphor dots is reduced, and the positioning accuracy between the side emitting the electric field and the anode electrode side has a margin. As a result, a clear image with high luminance can be obtained, and the production becomes easy. Further, since the anode electrode and the anode substrate surface are covered with the phosphor dots and the protective film, no gas is released from the anode electrode and the anode substrate surface, and the degree of vacuum is not reduced. As a result, the product life can be extended. Since a constant potential can be supplied to the protective film by the focusing electrode, phenomena such as charge-up on the surface of the protective film are less likely to occur. As a result, the withstand voltage of the anode is improved, and the driving voltage of the anode electrode can be increased. Higher brightness can be achieved.

According to the invention described in claim 2, according to claim 1,
3. The field emission display device according to claim 2, wherein the anode electrodes are alternately and commonly connected every other, and the focusing electrodes are formed in a direction orthogonal to a longitudinal direction of the anode electrodes and are mutually common. Connected. Therefore, the electron beam can be focused on one anode electrode by switching driving of the anode electrode. The ratio of colliding with the phosphor dots formed on the adjacent anode electrode is reduced, and the positioning accuracy between the side emitting the electric field and the anode electrode side is allowed. As a result, a clearer image with higher luminance can be obtained, and the production becomes easier.

According to the invention described in claim 3, according to claim 1 of the present invention,
In the field emission display device described in Item 2, the focusing electrode is formed of a material having a light-shielding property. Therefore, when viewed from the upper surface side on the anode substrate side, even with a protective film that is nearly transparent, the portion where the focusing electrode is provided around the phosphor dots becomes black, and the contrast of the screen can be improved.

According to the invention described in claim 4, according to claim 3,
In the field emission display device described in the item 1, the protective film is made of SiO or SiN, and the focusing electrode is made of amorphous silicon or chromium oxide. Therefore, there is an effect that materials suitable for the protective film and the focusing electrode can be easily obtained.

[0023]

FIG. 1 is a plan view of a display unit side of a color FED according to an embodiment of the present invention. FIG.
FIG. 2 is a vertical partial sectional view of FIG. In the figure, the same parts as those in FIG. 3 is a focusing electrode, 12 is a protective film, 14 is a field emission cathode, 1
5 is an electron beam.

As shown in FIG. 1, striped anode electrodes 1-1 to 1-6 are formed in the vertical direction on the lower surface of the anode substrate 11, similarly to the conventional one shown in FIG. . The anode electrodes 1-1, 1-3, 1-5,... Are connected in a comb shape and an anode terminal A is provided. The anode electrodes 1-2, 1-4,... Are also connected in a comb shape, and an anode terminal B is provided. Wiring is performed such that one of the adjacent anode electrodes is switched to a positive voltage and the other is switched to a zero voltage or a negative voltage.

The protective film 12 shown in FIG. 2 is a pattern having a plurality of window openings in the anode electrodes 1-1 to 1-6,. 1-6,... Are formed.
After the window opening is formed in the protective film 12, each of the R, G, and B phosphor dots 2 is applied and formed on the window opening. On the lower surface of the protective film 12, the focusing electrodes 3 are horizontally arranged in a stripe pattern between adjacent window cutouts, and as shown in FIG. They are integrally formed and connected to a common focusing electrode terminal.

The above-described protective film 12 is an anode passivation film, and covers the entire surface except for a window-opening portion on which the phosphor dots 2 are formed by coating.
-1 to 1-6... ITO film surface and anode substrate 1
This is to prevent gas from being released from the glass surface. As specific materials, SiO and SiN can be used, and these have insulating properties. The focusing electrode 3 is a high-resistance film having conductivity, and for example, amorphous silicon (α-Si) or chromium oxide can be used. In FIG. 2, the window cutout portion is the anode electrode 1-1.
.., 1-6,... However, as shown in FIG. 4 as a conventional technique, the phosphor dots 2 are connected to the anode electrodes 1-1 to 1-1.
,..., And therefore, the window opening portion may be formed at least on the anode electrodes 1-1 to 1-6,.

The driving method of the anode electrodes 1-1 to 1-6 is the same as that of the conventional one shown in FIG. 4, and scans the voltage applied between the cathode electrode and the gate electrode on the FEC side. In synchronization with this, a positive anode drive voltage is applied to one of the adjacent electrodes so that the anode electrode immediately above the intersection of the cathode electrode and the gate electrode to which the voltage has been applied has a positive voltage, and the other electrode has this positive electrode drive voltage. Switching driving is performed so as to apply a potential lower than the positive anode driving voltage, for example, 0 voltage or negative voltage. On the other hand, a constant voltage lower than the positive anode driving voltage, for example, a potential or a negative voltage is constantly applied to the focusing electrode 3.

By applying a low constant voltage to the focusing electrode 3, the spread of the electron beam 15 emitted from the field emission cathode (FEC) 14 in the vertical direction is suppressed, and at the same time, the electric field at a specific position on the matrix is reduced. Anode electrodes 1-1 to 1 synchronized with scanning of emission cathode (FEC) 14
By the switching drive of 1-6, the spread in the horizontal direction is suppressed. As a result, the electron beam diameter can be reduced, and the electron beam 15 can be focused on one of the plurality of phosphor dots 2. Therefore, the ratio of projecting to the adjacent phosphor dots is reduced, and the positioning accuracy between the cathode substrate 13 and the anode substrate 11 has a margin. As a result, a clear image with high luminance can be obtained, and the production becomes easy.

As the above-mentioned protective film 12, SiO, SiN
Is used, when the luminescent image is observed from the upper surface side on the anode substrate 11 side, the contrast of the screen is not good because the protective film 12 is almost transparent. As the electrode material of the focusing electrode 3, if a non-transparent material having a light-shielding property such as α-Si or chromium oxide is used as described above,
The portion where the focusing electrode 3 is provided around the phosphor dot 2 becomes black, and the contrast of the screen can be improved.

Further, since a constant potential can be supplied to the protective film 12 by the focusing electrode 3, a phenomenon such as charge-up on the surface of the protective film 12 is less likely to occur, and as a result, the anode withstand voltage is improved and the anode electrode 1-1 is improved. .. Can be increased, and higher luminance can be achieved.

FIG. 3 is a diagram showing a simulation result of the electron beam trajectory in the FED shown in FIGS.
In the figure, the same parts as those in FIG. 3 and 5 show a type in which a part for emitting an electron beam is divided into two parts. Although the cathode-anode gap, the gate voltage, and the anode voltage are equal, the current density is 23
Are different in size. However, qualitatively, the difference in the electron beam trajectory 21 depending on the presence or absence of the focusing electrode 3 shown in FIGS. 1 and 2 appears. A negative voltage is applied to the focusing electrode 3.

In contrast to the simulation result of the conventional structure shown in FIG. 5, in the simulation result of the structure of the embodiment of the present invention shown in FIG. 3, the electron orbit 21 is focused on the phosphor dots by the focusing electrode. However, it can be seen that the spot diameter of the electron beam is reduced to 67% in the vertical direction. In FIG. 3, stray electrons can be seen, but the ratio is small and there is no problem.

In the above description, a color FED has been described. However, even in the case of a monochrome FED, brightness and sharpness can be improved by increasing the vertical convergence of the display screen of the FED, and manufacturing is also possible. Easy.

In the above description, the focusing electrode is formed only in the direction orthogonal to the anode electrode. However, the focusing electrode is also formed on the protective film between the plurality of anode electrodes in parallel with the anode electrode.
The focusing electrodes may be arranged in a grid around the window opening.

[0035]

As is apparent from the above description, according to the present invention, it is possible to improve the convergence of an electron beam and increase the brightness with a simple structure. Accordingly, high-quality and high-definition display can be performed, and the positioning accuracy required between the FEC side and the anode electrode side is reduced, so that there is an effect that manufacturing is easy.

The focusing electrode may be a single electrode, and there is no need to perform switching driving. Therefore, no additional circuit is required, and there is no increase in cost. There is an effect that the product life can be extended without lowering the degree of vacuum. Phenomena such as charge-up on the protective film are less likely to occur, and the anode drive voltage can be increased, so that the anode withstand voltage can be improved and the luminance can be increased. Because the focusing electrode has a light shielding property,
This has the effect of increasing the contrast on the display screen and obtaining a high-quality image.

[Brief description of the drawings]

FIG. 1 is a plan view of a display unit side in a color FED according to an embodiment of the present invention.

FIG. 2 is a vertical partial sectional view of FIG.

FIG. 3 is a diagram showing a simulation result of an electron beam trajectory in the FED shown in FIGS. 1 and 2;

FIG. 4 is an explanatory diagram of a conventional anode switch drive type color FED.

5 is a diagram showing a simulation result of an electron beam trajectory in the conventional FED shown in FIG.

[Explanation of symbols]

1-1 to 1-5 anode electrode, 2 phosphor dots, 3
Focusing electrode, 11 Anode substrate, 12 Protective film, 13
Cathode substrate, 14 field emission cathode, 15 electron beam, 21 electron beam orbit, 22 equipotential surface, 23
Current density, 31-1 to 31-4 cathode electrode, 32
-1, 32-2 gate electrode, 33 spacer

Claims (4)

[Claims] A plurality of anode electrodes are formed on the anode substrate, and a protective film is formed on the anode substrate and the anode electrodes in a pattern having a plurality of window openings in the vicinity of the anode electrode and the anode electrode; A field emission display device, wherein dots are formed in the window, and a focusing electrode is formed on the protective film between the windows. 2. The method according to claim 1, wherein the anode electrodes are alternately connected in common every other electrode, and the focusing electrodes are formed in a direction orthogonal to the longitudinal direction of the anode electrodes and are connected in common with each other. 2. The field emission display device according to claim 1, wherein: 3. The field emission display device according to claim 1, wherein the focusing electrode is formed of a material having a light shielding property. 4. The field emission display device according to claim 3, wherein the protection film is made of SiO or SiN, and the focusing electrode is made of amorphous silicon or chromium oxide.