JPH1092347A - Plane type image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a plane type image display device with field emission cold cathodes as being capable of selecting fluorescences without high voltage switching. SOLUTION: Plural cold cathodes 10 are arranged in rows and columns. Gate electrodes 11 (11a, 11b) consisting of sets of two electrodes divided and insulated in rows are arranged to encircle the cold cathodes 10 in the same column. The cold cathodes 10 are formed with a spindt or transfer molding method, e.g. The gate electrodes 11 are arranged perpendicular to the arrangement of a red fluorescence 12a, a green fluorescence 12b and a blue fluorescence 12c formed via an anode on the surface of a glass face plate, not explaned here.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display using a field emission type cold cathode.

[0002]

2. Description of the Related Art At present, a flat image display device (FED: Field Emission Discharge) that emits electrons from a field emission type cold cathode and collides with a phosphor coated on an anode electrode to emit light.
play) is under development. Unlike a display device using a liquid crystal panel, the FED has features such as low power consumption, a wide viewing angle, a fast response speed, and a wide operating temperature range because of its self-luminous type and high luminous efficiency. for that reason,
FEDs are receiving attention as next-generation flat panel displays.

FIG. 6 is a sectional view of a conventional FED. 6
0 is a glass plate, 61 is a cathode electrode, 62 is a cold cathode, 63 is an insulating layer, 64 is a gate electrode, 65a, 65
b and 65c are red, green and blue phosphors, respectively 66a and 6c
6b and 66c are anode electrodes, and 67 is a glass face plate.

A gray scale is realized by applying a voltage to the gate electrode 64 and applying a voltage corresponding to image data. In order to perform color display by selectively causing electrons to collide with the respective phosphors, a method called anode switching is used. This anode switching is performed for the phosphor 65 (65a, 6a).
5b, 65c) is coated on the anode electrode 66 (66
a, 66b, 66c) in order by applying a voltage of several hundreds to several kV.

However, this type of FED has the following problems. That is, it is necessary to perform anode switching for color display, and it is necessary to use a switching element such as a power transistor to switch a high voltage of several hundreds to several kV and apply it to the anode electrode 66 in order. For this reason, there is a problem that the load on the drive circuit including the switching element is large.

[0006]

As described above, in the conventional FED, it is necessary to select a phosphor by high-voltage switching in order to perform color display, and the load on the drive circuit is large. was there.

SUMMARY OF THE INVENTION An object of the present invention is to provide a flat-type image display device that can collide electrons from a cold cathode with a desired phosphor without requiring high-voltage switching such as anode switching, thereby reducing the load on a driving circuit. A display device is provided.

[0008]

[Means for Solving the Problems]

(Configuration) The flat-panel image display device of the present invention is configured as follows in order to solve the above problems. (1) A flat-panel image display device according to the present invention includes a plurality of cold cathodes two-dimensionally arranged in a row direction and a column direction on a substrate, and the cold cathodes are continuously arranged so as to surround the same column of the cold cathodes. And a gate electrode formed to be divided in the row direction to extract electrons from the corresponding cold cathode and deflect in the row direction, and to be spaced apart from the cold cathode, and to have a color display on the facing surface. And an anode electrode in which a plurality of types of phosphors are arranged in the row direction. (2) The direction of electrons emitted from the cathode electrode is controlled by controlling a voltage value applied to each of the gate electrodes including a plurality of electrodes, so that the electrons collide with the desired phosphor. (3) The gate electrode is configured as a pair of two, and is capable of deflecting electrons from the cold cathode in a one-dimensional direction. (4) The gate electrode is constituted by a set of three, and can deflect electrons from the cold cathode in a two-dimensional direction. (5) The cold cathode is formed on the cathode electrode via a resistance ballast layer.

(Function) The flat-panel image display device of the present invention comprises:
The choice of the phosphor that the electrons emitted from the cold cathode collide with,
This is performed by controlling the voltage applied to the gate electrode, not by switching at a high voltage. That is, the applied voltage to each of the plurality of divided gate electrodes is controlled, and electrons are deflected to select a phosphor. Here, the voltage applied to the gate electrode is sufficient from 0 to 100 V, which is much lower than the voltage applied to the anode electrode. Therefore, high voltage switching is not required,
The load on the drive circuit is reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a plan view showing a partial configuration of a flat panel display according to a first embodiment of the present invention.
A plurality of cold cathodes 10 are arranged in a row direction and a column direction. A gate electrode 11 (11) composed of two insulated electrodes divided in the row direction so as to surround the cold cathodes 10 in the same column.
a, 11b) are arranged corresponding to the respective cold cathode rows. The cold cathode 10 is formed by, for example, a spindt method or a transfer molding method. The gate electrode 11 is arranged in a direction (column direction) orthogonal to the arrangement direction (row direction) of the red phosphors 12a, green phosphors 12b, and blue phosphors 12c formed via an anode electrode on the surface of the glass face plate described later. ). Red,
One pixel is constituted by a set of the green and blue phosphors 12.
Although pixels are actually arranged in the row direction and the column direction, only the phosphor 12 for one pixel is shown here. Although not shown, a plurality of cathode electrodes described later are arranged in a direction perpendicular to the gate electrode 11. Note that one cathode electrode may be formed on one row of cold cathodes, or one cathode electrode may be formed on a plurality of rows of cold cathodes. Although several cold cathodes 10 are formed per pixel in the figure, thousands to tens of thousands of cold cathodes 10 are actually formed per pixel.

FIG. 2 is a sectional view of the flat panel display according to the present embodiment. A plurality of cathode electrodes 21 extending in the row direction are formed on a glass plate 20. A plurality of cold cathodes 10 are formed on a cathode electrode 21 via a resistance ballast layer 22. Each cold cathode 10
The insulating layer 23 is formed on the resistance ballast layer 22 so as to surround On the insulating layer 23, the gate electrode 11 (11a-
h) is formed.

A glass face plate 24 is spaced apart from the above structure. An anode electrode 25 is formed on a surface of the glass face plate 24 facing the cold cathode 13. Red, green, and blue phosphors 12 (12a, 12b, 12c) are formed on the surface of the anode electrode 25, respectively.

The resistance ballast layer 22 serves to prevent a short circuit between the gate electrode 11 and the cold cathode 10. Since the shape of the cold cathode 10 may differ from each other due to manufacturing variations, a large amount of current flows from the cold cathode 10 having a short distance from the gate electrode 11, causing a short circuit between the gate electrode 11 and the cold cathode 10. May occur. However, the resistance ballast layer 22 is formed between the cold cathode 10 and the cathode electrode 2.
1, the current flowing from the cathode electrode 21 to the cold cathode 10 is limited, and short circuit can be suppressed. The line width of the gate electrode 11 is 3 μm, the film thickness is 0.5 μm, and the interval between the electrodes is 0.5 μm. The diameter of the base of the cold cathode 10 is 2.6 μm, and the size of one pixel is 100 μm × 100 μ.
A 2-inch full-color display was prepared as m. By connecting a drive circuit to the gate electrode 11 and changing the pair of gate electrodes 11 surrounding the cold cathode 10 in the range of 40 to 200 V, electrons were deflected to the red, green, and blue phosphors 12. .

Since the arrangement direction of the gate electrode 11 and the phosphor 12 is orthogonal to each other due to the above structure, the gate electrode 11
Electrons emitted from the cold cathode 10 can collide with desired phosphors 12 by controlling the voltage values applied to a to h to deflect the electrons. For example, 20V for the gate electrode 11a, 100V for 11b, 30V for 11c, 80V for 11d, 50V for 11e, and 6 for 11f.
When a voltage of 60 V is applied to 0 V and 11 g, and a voltage of 50 V is applied to 11 h, the electron beam can be focused and collided with the phosphor 12 c.

The driving will be described. A voltage of 500 V is applied between the cathode electrode 21 and the anode electrode 25 corresponding to one line (one line) of the pixels arranged in the row direction. Gate electrode 1 corresponding to a pixel according to image data
A voltage of 0 to 100 V is applied between the first electrode 1 and the cathode electrode 21. Then, at the same time as controlling the amount of electrons emitted from the cold cathode 10, the electrons collide with the desired phosphor 12a of the pixel. Also, the other phosphors 12b, 1 of the pixel
Similarly, electrons sequentially collide with 2c to emit light.
At this time, instead of emitting electrons from the cold cathode 10 just below the pixel, electrons may be emitted from the adjacent cold cathode 10, and in that case, the brightness becomes higher. Then, the above driving is sequentially performed on each pixel on the same line, and all the pixels on the same line emit light. Then, the above-described driving is sequentially performed on the pixels on another line, and all the pixels emit light to display an image. As a result of the above-mentioned driving, excellent emission luminance was obtained and a good image was obtained.

Note that an image may be displayed by causing electrons on one line to emit light by colliding electrons with all the pixels on the same line at the same time and causing pixels on another line to emit light sequentially.

The cold cathode 10 is usually made of molybdenum (M
o), but with 1% barium silicide (B
It is also possible to use molybdenum silicide (MoSi ₂ ) containing aSi ₂ ). Mo, which is usually used, has a high work function of 4.2 eV and a high electric field required for electron emission. Therefore, when cold cathodes are arranged in an array to increase the electric field, non-uniformity of the electric field distribution tends to occur and current instability is often seen, and in extreme cases, eddy current is generated and the cold cathode is destroyed was there. In addition, Mo is replaced with SiO or SiO.
_In the case where Mo is formed on Mo, Mo has low adhesion to SiO and SiO _2, and has problems such as Mo peeling off and contacting with the gate electrode to cause a short circuit.

Therefore, the work function is relatively high (4.5e).
V) MoSi ₂ having high adhesion to Si and SiO ₂ ; workability and stability are relatively low but work function is low (2.2e)
V) An alloy with BaSi ₂ is used as a cold cathode. BaS
By forming the composition ratio of i ₂ to MoSi _{2 from} a material in the range of 0.1 to 10%, SiO, SiO ₂
It has been found by the present inventors that the adhesion to the metal is high and the work function is as low as 2.2 eV. When a cold cathode is made of this material, electrons are mainly converted into BaSi having a low work function.
₂ and released by MoSi ₂ to SiO, SiO ₂
Adhesive strength increases.

When the composition ratio of BaSi ₂ is 10% or more,
Although the work function is low, the surface of the cold cathode is liable to be deteriorated by oxidation (oxidation of Ba) or gas adsorption, and the emission current from the cold cathode becomes unstable. In an extreme case, electrons are not emitted. When the composition ratio of BaSi ₂ is 0.1% or less, the work function tends to be high similarly to MoSi ₂ alone, and the emission current tends to be low.

When this material is used for a cold cathode, the adhesion to the substrate is improved, and a uniform emission current with a low electric field can be obtained. In the case of obtaining an emission current of 1 μA, about 100 V is conventionally required to be applied to the gate, but in the present embodiment, a voltage as low as about 10 V can be obtained, and the uniformity and stability of the emission current are further improved.

Production of cold cathode using this material
The pindt method and the transfer molding method will be described. First, the production of a cold cathode by the spindt method will be described. As shown in FIG. 3 (a), about 1μm on the substrate 31 such as silicon dioxide (SiO ₂₎ by thermal oxidation or CVD method
The insulating film 32 is formed by deposition, and a silicon (Si) film 33 and an aluminum (Al) film 34 serving as a gate electrode are formed by sputtering, for example, at 300 and 100 nm, respectively.
Laminate.

Then, as shown in FIG. 3B, the Al film 34, the Si film 33, and the insulating film 32 are selectively etched by a selective etching method using a resist (not shown) as a mask.
A pinhole 35 of about μm is formed.

Next, as shown in FIG.
The metal film 36 made of MoSi ₂ containing BaSi ₂ is formed by vacuum sputtering or the like. At this time, the substrate 31 is rotated, and the metal film 36 is sputter-deposited from the direction perpendicular to the substrate 31. Then, the diameter of the upper part of the pinhole is closed with the deposition of the metal film 36, and the metal film 36 is deposited in a conical shape in the pinhole.

Then, as shown in FIG.
At the same time as removing the film 34, the metal film 3 on the Al film 34 is removed.
6 is removed. Thus, the conical cold cathode, the insulating layer, and the gate electrode are formed by the spindt method.

Next, the formation of the cold cathode by the transfer molding method will be described. As shown in FIG.
An SiO ₂ film 42 is formed as a protective film on a silicon (100) substrate 41 having a thickness of 1 mm to a thickness of about 100 nm by a thermal oxidation method. Resist such a SiO ₂ film 42 with ammonium fluoride selectively etched as a mask SiO ₂
A square hole is formed in the film 42. Further, the Si substrate 41 is anisotropically etched with an aqueous solution of potassium hydroxide using the remaining SiO ₂ film 42 as a mask,
A square pyramid-shaped groove 43 having a size of μm is formed.

Next, as shown in FIG.
After removing the entire O ₂ film 42, a thermal oxidation process is performed to form a 0.5 μm thick SiO ₂ film 44 on the entire surface. By this thermal oxidation treatment, the tip of the quadrangular pyramid-shaped groove is further sharpened. The SiO ₂ film 44 is configured as an insulating film between the cold cathode and the gate.

Next, as shown in FIG. 4C, Mo containing 1% of BaSi ₂ is formed by vacuum sputtering or the like.
A metal film 45 (later cold cathode) made of Si ₂ is formed in a thickness of 3 μm, and tantalum is deposited thereon in a thickness of 0.3 μm.
6 is formed.

Next, as shown in FIG. 4D, a glass substrate 47 having a thickness of 0.5 mm is adhered to the surface of the adhesive layer 46 by electrostatic adhesion. All are removed by etching. By etching the Si substrate 41, a pyramid-shaped S
An iO ₂ film 44 and a metal film 45 are formed.

Next, as shown in FIG. 4E, the Al film 48 serving as a gate electrode is formed by sputtering, for example, for 300 n.
m. Next, as shown in FIG. 4F, a resist 49 is applied to the entire surface, and the resist 49 is etched by CDE until the tip of the Al film 48 is exposed.

Then, as shown in FIG. 4G, the Al film 48 is etched by using the resist 49 as a mask.
Then, the SiO ₂ film 44 is etched to expose the tip of the metal film 45 to form a pyramidal cold cathode. Then, the resist 49 is removed.

In the flat-panel image display device of this embodiment, the voltage applied to the two divided gate electrodes is controlled to deflect the electrons emitted from the cold cathode, and the electrons collide with the desired phosphor. To emit light. Further, when the cold cathode is made of MoSi ₂ containing 1% of BaSi ₂ , electrons can be emitted from the cold cathode at a low voltage.

In the flat-panel image display device of the present embodiment, the selection of the phosphor with which the electrons emitted from the cold cathode collide is determined by the applied voltage (several hundred volts) to the anode electrode coated with the phosphor.
The above-mentioned switching is not performed, but is performed by controlling the applied voltage (0 to 100 V) to the gate electrode divided into two and arranged along one row of the cold cathodes.
Voltage switching is significantly reduced, and the load on the drive circuit is reduced.

(Second Embodiment) FIG. 5 is a perspective view showing the configuration of a cold cathode section according to a second embodiment of the present invention. On an insulating substrate 51, a cathode electrode 52 and a resistance layer 53 are laminated. A hole is formed in a part of the resistance layer 53, and a conical cold cathode 54 is formed in the hole. The gate electrode 55 (55a, 55b, 55c) is formed on the resistance layer 53. The gate electrode 55 is divided into three so as to surround the hole in which the cold cathode 54 is formed.

The gate electrode 55 has a line width of 3 μm, a film thickness of 0.5 μm, and an electrode interval of 0.5 μm. The diameter of the base of the cold cathode 53 is 2.6 μm.
m, a glass plate having a thickness of 1 mm was used as the insulating substrate 51.

The voltage applied to the three electrodes 55 is 20 to 1
It was confirmed that the electron beam was deflected in a two-dimensional plane by changing it in the range of 00V. The flat-panel image display device according to the present embodiment can deflect electrons emitted from the cold cathode in an arbitrary two-dimensional direction by controlling the voltage values of the three divided gate electrodes.

The present invention is not limited to the above embodiment. For example, the anode electrode is formed independently for each color of the phosphor, but may be common. Further, the cathode electrode can be formed on any insulating substrate other than the glass plate, and can be formed on a conductive material via an insulating layer.

The substance contained in the silicide in an amount of 0.1 to 10% includes silicide I such as SrSi _{2 in} addition to BaSi _2.
Group Ia elements are applicable. The gradation may be expressed by changing the voltage applied to the cathode electrode.

The color of the phosphor is red if color display is possible,
It is also possible to use phosphors of colors other than green and blue. In addition, various modifications can be made without departing from the spirit of the present invention.

[0039]

As described above, according to the flat-panel image display device of the present invention, by controlling the voltage values of a plurality of insulated gate electrodes, electrons emitted from the cold cathode are deflected and controlled. The load on the drive circuit is small.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a flat panel display according to a first embodiment.

FIG. 2 is a sectional view of FIG.

FIG. 3 is a process sectional view showing the formation of the cold cathode by the spindt method according to the first embodiment.

FIG. 4 is a process sectional view showing the formation of the cold cathode by the transfer molding method according to the first embodiment.

FIG. 5 is a perspective view illustrating a configuration of a cold cathode unit of the flat panel display according to the second embodiment.

FIG. 6 is a cross-sectional view showing a conventional flat panel display.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Cold cathode 11 ... Gate electrode 12 ... Phosphor 20 ... Glass plate 21 ... Cathode electrode 22 ... Resistance ballast layer 23 ... Insulating layer 24 ... Glass face plate 25 ... Anode electrode 31 ... Substrate 32 ... Insulating film 33 ... Silicon film 34 ... Aluminum film 35 ... Pin hole 36 ... Metal film 41 ... Silicon (100) substrate 42 ... SiO ₂ film 43 ... Groove 44 ... SiO ₂ film 45 ... Metal film 46 ... Adhesive layer 47 ... Glass substrate 48 ... Aluminum film 49 ... Resist Reference numeral 51: substrate 52: anode electrode 53: insulating layer 54: cold cathode 55: gate electrode

Claims (1)

[Claims] 1. A plurality of cold cathodes two-dimensionally arranged in a row direction and a column direction on a substrate, and these cold cathodes are formed continuously so as to surround the same column of cold cathodes, and are formed in a row direction. A gate electrode for extracting electrons from the corresponding cold cathode and deflecting it in the row direction, and a plurality of phosphors for color display on the facing surface, which are spaced apart from the cold cathode. And an anode electrode arranged in the row direction.