JP2716305B2 - Field emission type electron tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission type electron tube applied to a flat panel display device and the like.

[0002]

2. Description of the Related Art In recent years, flat panel display devices have been actively developed, and liquid crystal displays (LCD), electroluminescent displays (EL), light emitting diode displays (LED) and the like have appeared on the market. It is inferior to a color cathode ray tube (CRT) in resolution and full color. In order to solve these problems, a flat panel display utilizing thermionic emission from a plurality of cathodes has been developed. This is a device in which an electron beam is thermally extracted from a substantially planar electron source, and is controlled, deflected, focused, accelerated, incident on a phosphor, and emitted by an electromagnetic field.

The getter section of this flat panel display device will be described below. FIG. 5 is a perspective view of the electrode assembly 40 and the vacuum envelope 41 constituting the flat panel display device. The thickness of the electrode structure 40 including the cathode electrode, the plurality of grids, the deflection electrodes, and the like is about 10 cm, and the distance between the electrode structure 40 and the vacuum envelope 41 is about 2 cm. In this space, a getter is extended in parallel with the side surface of the vacuum envelope 41. A wire getter 42 is provided as a getter, and the wire getter 42 includes a getter material 42b made of BaAl _{4 in a} case 42a. Ba is evaporated by energizing the getter material 42b in a vacuum and heating to about 1000 ° C., and the getter film 4 is formed on the inner surface of the vacuum envelope 41.
3 is deposited. As a result, the residual gas is adsorbed and the inside of the vacuum envelope is maintained at a high vacuum.

[0004] However, due to the increase in the amount of information and social phenomena of personalization, flat panel displays that are further reduced in size and weight are rapidly demanded. And, in particular,
A flat panel display device in which field emission cold cathode microguns are arranged in a matrix has attracted attention. Examples include R. Heyer et al., "Microtips Fluorescent Display (Mic).
rotips Fluorescent Display
y) ", Japan Display (Japan D
display) at the 1986 Conference. The microgun is formed by a molybdenum cold cathode chip, and electrons are emitted from the tip of the cold cathode chip by an electric field effect between the cold cathode chip and a gate electrode provided around the top of the cold cathode chip. The anode electrode made of a luminophore material is separated from the gate electrode surface by about 100 μm.

[0005] It is impossible to install such a wire getter inside the vacuum envelope (electron tube) of this device in view of its dimensions, and no other getter is used. However, there is no flat display device provided with a mechanism for adsorbing residual gas or generated gas to maintain the degree of vacuum, and has not been put to practical use as a product.

[0006]

A flat panel display device using a field-emission cold cathode microgun has not been put to practical use despite its thinness and display performance superior to that of a normal CRT. The main reason is that it is difficult to maintain a high vacuum between the cold cathode and the anode luminophore material, the residual gas and the gas generated from inside the structure after vacuum sealing are ionized by the electron beam, The ions are accelerated by the voltage applied between the cold cathode and the anode luminophore material and between the cold cathode and the gate electrode, and collide with the cold cathode with high energy to sputter, thereby shortening the life of the cold cathode. This is because the electron emission operation becomes unstable.

As a method for maintaining a high vacuum, barium (B
a) It is conceivable to use a getter. The barium getter includes a ring getter that heats by high frequency and a wire getter that heats by energization as described above.
However, these getters have a thickness of 2 mm or more and cannot be installed in the electron tube of the field emission display device.
Further, even if the thickness is reduced, there is a danger that getter atoms wrap around at the time of getter flash, adhere to the cathode, the gate electrode and the anode electrode, and contaminate these electrodes.

Accordingly, the present invention solves the above problems,
An object of the present invention is to provide a field emission type electron tube having a long life and a stable electron emission operation.

[0009]

According to the present invention, there is provided a field emission type electron tube including a cold cathode for emitting electrons based on the principle of field emission and a getter evaporation section containing a getter material. Of the gas adsorber, on the surface of which a vapor deposition film of the getter material evaporated on the getter evaporator is formed, and the gap between the getter evaporator and the gas adsorber and the movement of electrons emitted from the cold cathode A communication portion that spatially communicates with the space, and the opening of the gap communicating with the communication portion and the opening of the moving space of the electrons are displaced from the communication portion in the electron emission direction. A field emission electron tube is provided.

[0010] The surface of the gas adsorbing section may be uneven.

[0011]

The residual gas and the generated gas in the electron emitting portion are adsorbed by the getter material deposited on the gas adsorbing portion.
Further, if the gap and the electron transfer space are displaced from each other in the electron emission direction with respect to the space, the getter atoms are less likely to move into the electron transfer space during getter flash.

Further, even in a narrow space of the electron tube, the gas adsorption area can be widened, and the residual gas and generated gas can be quickly and efficiently adsorbed.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a structure of a getter section of an embodiment of a field emission type electron tube according to the present invention, and FIG. 2 is a plan view of a flat display device using the field emission type electron tube according to the present invention. It is a perspective view which shows an example schematically.

As shown in FIG. 2, the field emission type electron tube has a vacuum envelope 10, the vacuum envelope 10 has a face plate 11 and a back support plate 14, and the face plate 11 is a display unit. 12 and a frame portion 13. In a flat display device using this field emission type electron tube, a phosphor voltage circuit 16 and a substrate driving circuit 17 are provided.
Is provided. Further, for example, the area of the front surface of the field emission type electron tube is 160 × 130 mm ² , of which the screen size is 110 × 90 mm ² (corresponding to a 6-inch type).

FIG. 1 is an enlarged view taken along line AA of FIG.

The getter material 20 is melted and stored in a box-shaped boat 21 by plasma spraying. According to this method, the getter material is formed into a thin plate having a thickness of several 100 μm. As a getter material, for example, BaAl
_A mixture of ₄ and a small amount (about 4%) of Ni is used.

The boat 21 is manufactured by reactive ion etching (RIE) of W (tungsten) and has a size of about 10 mm (length) x 50 mm (width) x
It is 0.6 mm (depth) x 0.4 mm (plate thickness). The boat 21 is accommodated in a case (insulated type case) 22 formed in a heat-insulating getter shape on the back support plate 14. The heat insulating type case 22 is formed by patterning a Si single crystal wafer in advance, and then performing anisotropic etching using either plasma ion etching or RIE or wet etching using an alkali etchant. In this manner, a getter evaporator including the getter material 20, the boat 21, and the case 22 is formed.

The gas adsorbing portion base 23 is made of a single crystal of Si similarly to the heat insulating case 22. The uneven portion 23a on the surface is formed by anisotropic etching of a wafer which has been patterned in advance, using either plasma ion etching or RIE or wet etching with an alkali etchant. The distance (the height of the peak) between the deepest part and the apex of the uneven part 23a is about several 100 μm. The area of the wafer on which the uneven portions 23a are formed is wider than the getter evaporation portion of the getter material, for example, about 14 × 54 mm ² . Then, the getter sections made up of the getter evaporator and the gas adsorber base thus manufactured are installed at both ends inside the vacuum envelope of the display device.

The formation of the getter film from the getter evaporating portion of the getter material to the gas adsorbing portion base 23 is performed by attaching an electrode to the boat 21 and using a so-called resistance heating evaporation method. At this time, the applied voltage is set so that the temperature of the
The temperature is controlled to be 100 ° C. or more and 1300 ° C. or less (a current value of 10 A at maximum is sufficient). The gas adsorber base 23 becomes a gas adsorber by forming a getter film. In this embodiment, the getter film is made of Ba, but may be made of Ba, Al, or an alloy thereof. Since it is a contact type getter film, the getter ability is proportional to the total area of a thin film even if it is a thin film. Therefore, since the surface of the gas adsorption portion base 23 is an uneven surface, the getter effect is improved about twice. The getter evaporating portion of the getter material and the substrate of the gas adsorbing portion are repeatedly formed with a getter film and do not come into contact with each other.
is seperated.

Next, the positional relationship between the getter section and the electrode assembly 24 will be described. FIG. 3 is an enlarged view of a portion B surrounded by a dotted line in the sectional view of the field emission type electron tube shown in FIG. The cold cathode 30 has a cone shape with a sharp tip (electron emission portion), and has an electrically insulating layer (for example, SiO 2).
_An electric field is applied to the cold cathode 30 by applying a voltage to the gate electrode 32 thus laminated via the ( _two films) 31, and electrons are emitted from the electron emitting portion 30 a at the tip of the cold cathode 30. The emitted electrons are accelerated toward an anode 33 made of a transparent conductive layer (for example, an ITO film). On this anode electrode 33, the phosphor 3
4 is applied, and emits light by the incidence of electrons. Color display can be achieved by appropriately attaching the three primary colors of red, blue and green as the phosphor 34. The electron emission is controlled in matrix by the gate electrode 32 and the control electrode 35 under the cold cathode.

FIG. 4 is an enlarged perspective view of a portion C of the electrode structure of the electron emission portion in FIG. The gate electrode 32 is formed so as to surround the tip of the cone type cold cathode 30. The gate electrode 32 can be driven for each cold cathode group corresponding to one pixel.

The positional relationship between the getter portion and the electrode structure of the electron emission portion is designed so that the getter material atoms evaporated from the evaporation portion do not contaminate the electron emission portion. As shown in FIG. 1, the means comprises a communication portion 27 that communicates a gap 25 formed between the getter evaporation portion of the getter material and the gas adsorption portion substrate and a moving space 26 for electrons emitted from the cold cathode. The getter evaporator and the gas adsorber base are provided so that the opening 28 through which the gap 25 communicates with the communication portion 27 is disposed forward of the opening 29 of the moving space 26 in the electron emission direction. It should be noted that the same effect can be obtained by disposing it behind the electron emission direction.

Thereby, the cold cathode and the gate electrode are protected from contamination of the getter material. However, this is a minimum required structure for preventing contamination, and in practice, contamination of the anode electrode must also be prevented. In the present embodiment, as described above, the getter evaporating portion of the getter material and the gas adsorbing portion base are brought close to each other and opposed to each other. By making the surface narrower than the opposing surface of the gas adsorbing portion base, contamination of the anode electrode is also prevented.

As described above, the following effects were confirmed by providing the getter portion having the above-described structure in the vacuum envelope. Initial vacuum degree after vacuum sealing of vacuum envelope is 10 ^-8 To
Assuming that the order is rr, if no getter is performed, the display operation is repeated to obtain 10 ^-4 T.
The degree of vacuum deteriorated to the order of orr, and stopped operating after 10 minutes. At this time, the total operation time was about 10 hours in total. On the other hand, by performing the getter timely, the degree of vacuum is constantly 10 ⁻⁷ T even during the operation of the display.
The orr order could be maintained, and continuous operation for 5000 hours or more was confirmed.

As described above, in the present embodiment, Ni-added BaAl ₄ is used as a getter material, but other than simple metals such as Ti (titanium), Zr (zirconium), Ta (tantalum), Ba, Ti, Zr , Ta, or the like can provide the same effect. Also,
As a boat material, a high melting point metal such as Ta and Mo (molybdenum) is also used. In this embodiment, as a means for evaporating the getter material, a resistance heating method is used. However, when the getter material has a high melting point, there are an electron impact method, a high-frequency induction heating method, and the like. In addition, as a method for forming the getter material, in addition to plasma spraying, a thin film forming method such as a vacuum evaporation method, a sputtering method, and an ion plating method, or a forming method such as pressure bonding may be used.

[0027]

As described above in detail, according to the present invention, there is provided a field emission type electron tube provided with a cold cathode for emitting electrons based on the principle of field emission and a getter evaporator containing a getter material. , A gas adsorbing portion is provided on the surface of which a vapor deposited film of the getter material evaporated on the getter evaporating portion is formed, so that the residual gas and generated gas in the field emission electron tube can be adsorbed. it can. Further, there is provided a communication portion that spatially communicates a gap between the getter evaporating portion and the gas adsorption portion and a moving space of electrons emitted from the cold cathode, and an opening of the gap that communicates with the communication portion. Since the opening of the electron transfer space is displaced from the communicating part in the direction of electron emission, it is possible to prevent getter atoms from adhering to the cold cathode or gate electrode and contaminating these electrodes during getter flash. can do.
Further, specifically, when the opposing surface of the getter evaporator is narrower than the opposing surface of the gas adsorber, contamination of the anode electrode by getter atoms can be further prevented.

If the surface of the gas adsorbing portion is uneven, the gas adsorbing area can be increased even in a narrow electron tube space, and the residual gas and gas generated from inside the structure after vacuum sealing can be quickly removed. Adsorbs efficiently.

With the above effects, the inside of the field emission type electron tube using the field emission type cold cathode can be maintained at a high vacuum, and as a result, the electron emission operation can be stabilized and the life can be extended. A flat panel display device using a field emission cold cathode microgun can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of a field emission type electron tube according to the present invention.

FIG. 2 is a perspective view of an example of a flat panel display using a field emission type electron tube according to the present invention.

FIG. 3 is an enlarged sectional view of a region B in FIG. 1;

FIG. 4 is a perspective view showing the entire electron emission unit shown in FIG. 3;

FIG. 5 is a perspective view of an example of a conventional field emission type electron tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Display part 13 Frame part 14 Back support plate 15 Side wall of vacuum envelope 20 Getter material 21 Boat 22 Insulated type case 23 Gas adsorption part base 24 Electron emission part electrode structure

Claims (2)

(57) [Claims] 1. A field emission type electron tube comprising: a cold cathode for emitting electrons based on the principle of field emission; and a getter evaporation section containing a getter material, wherein the field emission electron tube is opposed to the getter evaporation section. A gas adsorbing section in which a vapor-deposited film of the getter material evaporated on the surface is formed on the surface, a gap between the getter evaporating section and the gas adsorbing section, and a moving space for electrons emitted from the cold cathode. And an opening of the gap communicating with the communication portion and an opening of the moving space of the electrons are arranged so as to be shifted from each other in the electron emission direction with respect to the communication portion. A field emission type electron tube characterized by the above-mentioned. 2. The field emission type electron tube according to claim 1, wherein the surface of the gas adsorption section has an uneven shape.