KR100248306B1 - Field emission device - Google Patents

Abstract

The present invention discloses a FED of novel construction.

Since the FED has a cavity in a high vacuum state, it is difficult to construct a large size panel due to large deformation caused by vacuum pressure.

In the present invention, by attaching a functional plate to the front substrate to form a back functional layer, the deformation caused by vacuum pressure occurs only on the front substrate to reduce the change in the cell gap to 1/2 of the conventional.

Description

Field emitter

1 is a schematic cross-sectional view for showing the general structure of the FED.

Figure 2 is a schematic cross-sectional view showing the configuration of a conventional large FED.

Figure 3 is a schematic cross-sectional view showing the configuration of the present invention FED.

4 is a schematic cross-sectional view showing another configuration of the FED of the present invention.

* Explanation of symbols for main parts of the drawings

P1: Front board P2: Back board

F1: Front functional layer F2: Back functional layer

N: Function Edition T: Getter

The present invention relates to a field emission device (FED).

As shown in FIG. 1, the FED, a flat panel display device derived from the CRT flattening research process, has an anode (A) and a cathode (K) so as to cross-facing each other on the upper and lower substrates (P1, P2). ) And the cathode (K) extends an emitter (E) having a sharp edge to emit a large amount of electrons from the emitter (E) to form an electric field. The device is configured to display an image by emitting light.

Herein, the electron emission of the emitter E is controlled by the gate G. In general, the gate G forms a conductive layer on the insulating layer D surrounding the emitter E to form a conductive layer. It is configured by forming an aperture (O) in the form of a circular lamp. In general, a common control potential is applied to the gate G, and the emitter E is controlled by field emission by the edge of the aperture O.

Meanwhile, in order to maintain a cell gap, a columnar spacer S is formed on the gate G.

In addition, the two substrates P1 and P2 are sealed by the sidewalls W, are exhausted to the exhaust pipe X through the exhaust hole H1 formed in the back side substrate P2, and exhausted in a high vacuum state. However, the degree of vacuum that can be achieved by a mechanical exhaust method such as a vacuum pump is about 10 ⁻⁵ Torr, and a chemical exhaust method is used in combination to further improve the vacuum degree about 10 ⁻⁷ Torr. To this end, a getter hole H2 is formed in the back side substrate P2 and a getter cup C in which a getter T is received is installed on the back side substrate P2.

The getter T seals the panel and then heats it with a high frequency induction heating lamp outside of the getter cup C to flash, or continuously operates without diffusion. However, in this method, since the getter T is diffused through the narrow getter hole H2 at one side of the panel, the effect is not sufficient, and the getter cup C after use remains in the panel as it is, which causes inconvenience in assembly and handling. .

In addition, since the FED is composed of thin glass substrates P1 and P2, and the cavity therebetween is evacuated in a high vacuum state, even when the spacer S is installed, the two substrates P1 and P2 have an internal vacuum pressure and an external pressure. Due to the difference in atmospheric pressure, it is difficult to maintain an accurate cell gap by deforming inward.

This problem is not a problem in the small size within a few inches, but when the FED is configured to a certain size or more, the vacuum stress becomes larger than the rigidity of the substrates P1 and P2, making uniform operation difficult.

Accordingly, when a large FED of 10 "or larger is conventionally adopted, a multi-panle structure is adopted as shown in FIG. 2. This is a support plate L having panels L1 and L2 of a small FED. The support plate L is generally composed of a silicon (Si) plate having a smaller brittleness and a higher strength than the E-ring plate.

By the way, the FED of such a structure can solve the problem of vacuum stress and constitute a large sized FED, but the partition line is generated in the form of a checkerboard when the image is displayed by the invalid parts outside the panels L1 and L2. Not only is the driving circuit complicated, but there is a problem that the overall size and weight are increased.

In view of such a conventional problem, an object of the present invention is to provide a FED that can be easily enlarged by suppressing a change in cell gap caused by vacuum pressure.

In order to achieve the above object, the FED according to the present invention is a FED in which a front functional layer and a rear functional layer are disposed opposite to each other in a cavity in a high vacuum state formed between a front substrate and a rear substrate which are sealed by sidewalls. A functional plate is attached to the front substrate to form a rear functional layer on the functional plate.

At this time, the cell gap between both functional layers is maintained by forming a well on the front substrate or the functional substrate.

According to such a configuration, no vacuum pressure is applied to the functional plate at all, and the change in the cell gap is significantly reduced to 1/2 of the conventional one.

Such specific features and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the accompanying drawings.

In FIG. 3, the FED according to the present invention has two substrates P1 and P2 sealed by sidewalls W so that the cavity therebetween is exhausted through the exhaust pipe X basically the same as the conventional FED. Do.

However, the functional board N is attached to the front substrate P1 so that the front functional layer F1 is formed on the front substrate P1 as in the prior art, but the rear functional layer F2 is on the functional board N. Is formed.

Here, the front functional layer F1 generically refers to the anode A and the phosphor F of FIG. 1 formed on the front substrate P1, and the back functional layer F2 is formed on the conventional rear substrate P2. The cathode (K), the emitter (E), and the gate (G) are generic terms.

On the other hand, the back substrate P2 only serves as the outer wall of the cavity, and preferably, the getter T is applied to the surface thereof. Then, the large area of the getter T can be applied, so that the getter effect is excellent, and the getter cup C is not left in the panel, thereby facilitating assembly and handling.

However, a predetermined cell gap must be maintained between both functional layers F1 and F2. To this end, a well W1 having a predetermined depth is formed on the upper surface of the functional plate N. The well W may be formed by etching the functional plate N by a chemical etching method or a dry etching method such as laser or ion sputtering.

Alternatively, as shown in FIG. 4, a configuration in which the well W2 is formed on the front substrate P1 and the functional plate N in the flat state may be attached.

Regardless of the configuration, the functional plate N can be made of a suitable material such as a glass plate or a silicon plate, and it is located on the opposite side of the user's field of view. Therefore, the functional plate N does not need to be transparent. Rather, the closer to dark the contrast is, Is preferable since it can be improved. The functional plate (N) may be attached to the front substrate (P1) as a bonding material, but may preferably be directly contacted by anodic bonding (anodic bonding) or the like.

On the other hand, at least one through hole H3 is formed in the functional plate N so that the pressure on the upper and lower surfaces is the same. Then, even if the cavity between both substrates P1 and P2 is exhausted through the exhaust pipe X in a high vacuum state, the functional plate N is not deformed at all, so that the rear functional plate F2 formed on the upper part thereof is also not deformed at all. .

According to the configuration of the present invention as described above, the change in the cell gap between the front functional layer F1 and the rear functional layer F2 is significantly reduced to approximately 1/2 of the conventional one. That is, in the past, the front substrate P1 and the rear substrate P2 were deformed inward by atmospheric pressure, respectively, but in the present invention, the rear functional layer F2 is not the rear substrate P2 but the functional board N without deformation. Since the change in the cell gap is made only on the front substrate P1, the change in the overall cell gap is about 1/2 of the conventional one.

These results mean that the size of the panel of the FED, which can be composed of a single panel, can be significantly increased, assuming that the allowable deformation amount of the cell gap of the FED is constant.

However, the stress of the quadrilateral plate is proportional to the square of the span between support points and inversely proportional to the square of the plate thickness. The strain of the plate is also proportional to the third square of the span and inversely proportional to the third square of the thickness.

However, according to the present invention, since the deformation is reduced to 1/2, the allowable span is 2 (1/3) squared, that is, about 1.26 times even when the substrate P1 having the same thickness is used, and the allowable stress is 2 (2 / 3) squared, that is, about 1.59 times.

That is, according to the present invention, when the substrate P1 having the same thickness is used, a panel having at least 26% larger size than the conventional one can be configured, and the panel having the same size can be configured with a substrate P1 having a thickness of about 26% smaller. . In this case, it can be seen that the external force causing the same deformation is increased by 26% (1.59 / 1.26-1) than the conventional one, which also increases the strength against the external force.

This advantage can improve the light transmittance inversely proportional to the thickness of the substrate (P1) to prevent the problem that the brightness is reduced in a large sized FED panel, and that the thick substrate (P1) is deformed or damaged by repeated heat treatment To be.

Accordingly, the present invention has a great effect in implementing a large area FED having excellent image quality.

Claims (4)

A field emission device comprising a front functional layer and a rear functional layer disposed to face each other in a cavity in a high vacuum state formed by sealing a front substrate and a rear substrate with sidewalls, wherein the functional plate is attached to the front substrate to form the rear surface on the functional plate. And a front functional layer is formed on the front substrate. The field emission device according to claim 1, wherein a cell gap between the two functional layers is formed by forming a well on at least one of the functional plate and the front substrate. The field emission device as claimed in claim 1, wherein at least one through hole is formed in the functional plate. The field emission device according to claim 1, wherein a getter is applied to the rear substrate.