Description

DEFLECTION FIELD EMISSION DISPLAY

Technical Field

[1] The present invention relates, in general, to a deflection Field Emission Display

(FED) and a method of deflecting the FED and, more particularly, to a deflection FED, in which a beam deflection plate capable of deflecting electron beams is provided in the basic structure of the FED, thus deflecting respective electron beams in a predetermined direction, and a method of deflecting beams in the deflection FED. Background Art

[2] Generally, a Field Emission Display (FED) is a display device using the principles in which a field emitter array, which is a cold cathode electron source, is arranged in a matrix structure, and in which electron beams collide with phosphors to implement cathode luminescence, as in the case of a conventional Cathode Ray Tube (CRT).

[3] As shown in Fig. 1, a conventional FED is constructed so that, in the lower portion thereof, a cathode plate 10, in which micro-tips 12 are placed on a cathode conductor 11 and which includes a gate 13 placed to correspond to each tip, is disposed, and, in the upper portion thereof, an anode plate 20, which includes an Indium Tin Oxide (ITO) layer 22 coated with fluorescent substances 21, is attached to a glass plate 30, with a small vacuum gap provided between the cathode plate and the anode plate by spacers (not shown) at a uniform interval.

[4] Generally, row electrodes and column electrodes are formed on the cathode plate

10, and field emitters are driven in a matrix form through the row electrodes and column electrodes, so that electrons are emitted for the time for which a gate voltage is applied, and are accelerated by an anode voltage. The emitted electrons pass through the vacuum gap in the form of electron beams, and thus cause the fluorescent substances of the anode to fluoresce. Each pixel has R, G, and B fluorescent substances, thus realizing color display.

[5] However, only when respective R/G/B fluorescent substances 21, constituting a unit pixel, and respective field emitters are satisfactorily aligned with each other, color display can be excellently implemented in each pixel.

[6] In practice, it is not easy to align the cathode plate 10 and the anode plate 20, and it is particularly difficult to accurately align the two plates, especially in a large-sized FED device, when the interval between pixels, etc. is taken into consideration. Therefore, when misalignment occurs, the display is not clear, or the FED panel itself may be unusable.

[7] In order to solve this alignment problem, equipment capable of accurately aligning

a cathode plate and an anode plate must be used, but this equipment is very expensive, and product reliability depends greatly on this equipment.

[8] Therefore, it is preferable that such an alignment problem be solved to some degree in the FED panel itself. Disclosure of Invention Technical Problem

[9] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an FED capable of deflecting electron beams, which can correct the path of electron beams generated by a cathode plate.

[10] Another object of the present invention is to provide a method of easily correcting the path of electron beams using a deflection FED of the present invention. Technical Solution

[11] In order to accomplish the above objects, the present invention provides a Field

Emission Display (FED), the FED comprising a cathode plate having field emitters for emitting electron beams, and a plate coated with fluorescent substances, with a small vacuum gap provided between the cathode plate and the plate by spacers at a uniform interval, the FED further comprising a deflection plate interposed between the cathode plate and the plate coated with the fluorescent substances, and provided with deflection holes, arranged to correspond to tips of respective field emitters, and one or more electrodes arranged around each deflection hole, wherein the FED corrects a path of the electron beams so that the electron beams emitted from the tips of the field emitters emit corresponding fluorescent substances through the deflection holes.

[12] Further, the present invention provides a method of deflecting electron beams in a

Field Emission Display (FED), the FED comprising a cathode plate having field emitters for emitting electron beams, and a plate coated with fluorescent substances, with a small vacuum gap provided between the cathode plate and the plate by spacers at a uniform interval, the FED further comprising a deflection plate interposed between the cathode plate and the plate coated with the fluorescent substances, and provided with deflection holes, arranged to correspond to tips of respective field emitters, and one or more electrodes arranged around each deflection hole, and the method comprising the steps of detecting a difference in alignment of field emitters of the cathode plate and corresponding fluorescent substances, determining a correction value to correct a path of electron beams corresponding to the alignment difference, and correcting the path of the electron beams by applying voltages to electrodes of the deflection plate on a basis of the correction value when operation is performed to drive the FED using the field emitters and a gate.

[13] In the deflection FED of the present invention, a deflection plate capable of controlling respective electron beams is further interposed between a cathode plate and an anode plate in order to solve the problem in which the alignment of the cathode plate and the anode plate is not accurately performed, and electron beams, generated by field emitters, do not cause corresponding fluorescent substances to satisfactorily fluoresce.

[14] Generally, the cathode plate and the anode plate are aligned using a precise aligner, but, when an FED panel is manufactured as a panel for a large-scale display, an alignment error occurs. When this alignment error falls within a predetermined allowable range, the plates can be used by correcting the path of electron beams, and need not be discarded. Each of the electron beams emitted from the field emitters of the FED is the movement or flow of a plurality of electrons, and the path thereof can be changed by applying a ground voltage, a negative voltage or a positive voltage.

[15] On the basis of these principles, the deflection FED of the present invention changes the path of all electron beams using a deflection plate with respect to the phenomenon, in which electron beams emitted from field emitters do not satisfactorily reach corresponding fluorescent substances, and emit other locations due to the difference in the alignment of the cathode plate and the anode plate or other causes, thus allowing respective field emitters to cause corresponding fluorescent substances to fluoresce.

[16] Further, the deflection of electron beams in the FED is performed using a structure in which the deflection plate of the present invention includes respective deflection holes, each provided with one or more electrodes, and is arranged to allow respective electron beams, generated by the cathode plate, to reach fluorescent substances after passing through respective deflection holes. Therefore, when a predetermined voltage (including zero voltage) is applied to the electrodes of the deflection holes, the path of electron beams, which are emitted from the cathode plate and reach the fluorescent substances, changes while they pass through the deflection holes. An electron beam, which is the flow of a plurality of electrons, is drawn in the direction of the electrodes when a positive voltage is applied to the electrodes, and is pushed from the electrodes when a negative voltage is applied to the electrodes. Therefore, the path of the electron beam is changed using such a phenomenon. When zero voltage (ground voltage) is applied to the electrodes, the electron beam is drawn toward the electrodes, similar to the case where a positive voltage is applied.

Advantageous Effects

[17] Accordingly, the deflection FED according to the present invention can correct the misalignment of field emitters and corresponding fluorescent substances occurring in

an existing FED, and can allow the corrected existing FED to be used, thus facilitating the manufacture of the FEDs. [18] Further, the deflection FED according to the present invention can simultaneously perform both a deflection function and a gating or focusing function, thus enabling a deflection FED having a simple structure to be manufactured. [19] The present invention provides a method of more easily correcting the path of electron beams in the FED, and allows the FED to simultaneously perform both the function of deflecting electron beams and the function of focusing or gating the beams, thus more simply controlling the electron beams of the FED.

Brief Description of the Drawings [20] Fig. 1 is an exploded perspective view showing the structure of a conventional

FED; [21] Fig. 2 is an exploded perspective view showing the structure of an FED according to the present invention; [22] Fig. 3 is a plan view showing an example of a deflection plate according to the present invention; [23] Fig. 4 is a plan view showing another example of a deflection plate according to the present invention; and [24] Fig. 5 is a plan view showing the deflection of an electron beam performed on the basis of a unit deflection hole 251, using the deflection plate 250 of Fig. 3 as an example.

Mode for the Invention [25] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. [26] Fig. 2 is an exploded perspective view of an FED panel 100, in which a deflection plate is mounted, according to the present invention. [27] In Fig. 2, the components of the FED other than a deflection plate 150 are the same as those of the conventional FED of Fig. 1. [28] That is, the FED is constructed so that, in the lower portion thereof, a cathode plate

110, in which micro-tips 112 are placed on a cathode conductor 111 and which includes a gate 113 placed to correspond to each tip, is disposed, and, in the upper portion thereof, an anode plate 120, which includes an Indium Tin Oxide (ITO) layer

122 coated with fluorescent substances 121, is attached to a glass plate 130, with a small vacuum gap provided between the cathode plate and the anode plate by spacers

(not shown) at a uniform interval. [29] Respective deflection holes 152, each provided with four electrodes 152, are interposed between the cathode plate 110 and the anode plate 120, and are insulated by

insulators 153. The electrodes 152 and the insulators 153 are attached to an insulating plate 154, which supports both the electrodes 152 and the insulators 153. Further, the insulating plate 154 is provided with wires required to apply voltage to the electrodes 152, and also functions as a wiring plate for applying voltage to respective electrodes 152.

[30] The micro-tips 112 must emit corresponding fluorescent substances 121 with electron beams through the gate 113. However, if the panel 100 is manufactured with the cathode plate 110 and the anode plate 120 misaligned, the electron beams emitted from respective micro-tips 112 may prevent corresponding fluorescent substances 121 from fluorescing, or may cause other fluorescent substances to fluoresce, thus resulting in the failure of the panel 100.

[31] Therefore, the deflection plate 150 of the present invention functions to correct the path of electron beams so that respective electron beams generated by the cathode plate 110 reach their corresponding fluorescent substances 121.

[32] In Fig. 2, each of the deflection holes 151 is provided with four electrodes 152 at angular intervals of 90 degrees. The path of an electron beam passing through each deflection hole 151 can be changed by applying voltage to four electrodes 152. Unlike the embodiment of Fig. 2, the path of electron beams can be changed using one or more electrodes.

[33] The deflection plate 150 is spaced apart from the gate 113 by a predetermined distance. Even if the deflection plate 150 is somewhat misaligned, the path of the electron beams can be satisfactorily corrected by applying voltage to the electrodes in consideration of this misalignment. Since the sizes of the deflection holes 151 of the deflection plate 150 are sufficiently large, and the distance between the deflection plate 150 and the gate 113 can be sufficiently reduced, the deflection plate 150 and the gate 113 can be easily aligned and stacked so as not to obstruct the path of electron beams.

[34] Hereinafter, a deflection plate according to the present invention is described in detail below with reference to Figs. 3 and 4.

[35] Fig. 3 is a plan view showing an example of a deflection plate according to the present invention, and Fig. 4 is a plan view showing another example of a deflection plate according to the present invention.

[36] The deflection plate 250 of Fig. 3 is constructed so that four large electrodes 252 are arranged adjacent to each other around a single deflection hole 251 at angular intervals of 90 degrees, with two electrodes arranged above the deflection hole 251, and the remaining two electrodes arranged below the deflection hole 251, and so that each electrode is insulated by an insulator 253. The deflection plate 350 of Fig. 4 is constructed so that four electrodes 352 are respectively arranged on the upper/lower and left/right sides of a single deflection hole 351 at angular intervals of 90 degrees,

with the electrodes insulated by an insulator 353.

[37] In the deflection plate 250 of Fig. 3, each electrode 252 has a large area. Since four electrodes 252 are disposed around a single reference deflection hole 251, opposite voltages are applied to opposite electrodes if the path of an electron beam is intended to be corrected to an extent corresponding to a desired angle, thus correcting the path of the electron beam.

[38] In the deflection plate 350 of Fig. 4, each electrode 352 has a small and long-bar shape, compared to the shape of the electrode 252 of Fig. 3. Further, as shown in Fig. 4, respective electrodes 352 are wired so that four wires are connected to four electrodes, respectively. That is, the wiring of the electrodes 352 is realized in such a way that electrodes arranged around respective deflection holes 351 are connected to the same wire for each of angles of 0, 90, 180, and 270 degrees. Therefore, the same voltage is applied to electrodes having the same coordinates around respective deflection holes 351. That is, wiring is performed so that an electrode 352a, oriented at an angle of 90 degrees with respect to a single reference deflection hole 351, is connected to an input electrode 357a, an electrode 352b, oriented at an angle of 180 degrees, to an input electrode 357b, an electrode 352c, oriented at an angle of 270 degrees, to an input electrode 357c, and an electrode 352d, oriented at an angle of 0 degrees to an input electrode 357d. Accordingly, the same voltages are applied to the electrodes arranged in the same orientations, respectively, thus equally deflecting respective electron beams.

[39] As shown in Fig. 2, respective electrodes are separately arranged on the insulating plate in the case where the electrodes are arranged on the insulating plate, separate insulation is not necessary between respective electrodes, and wiring can be performed between respective electrodes.

[40] Further, if necessary, a deflection plate, in which upper and lower electrode layers are stacked on each other, with an insulating plate interposed therebetween, and in which two layers are used as an electrode layer, can be used. A plurality of layers is continuously stacked on each other, so that a deflection plate including multiple electrode layers can be manufactured. A deflection plate including two or more electrode layers is more beneficial to a focusing function, which will be described later, and can be used to more precisely control deflection, but it may be unprofitable from the standpoint of manufacturing costs or a control structure.

[41] Fig. 5 is a plan view showing the deflection of an electron beam performed on the basis of a unit deflection hole 251 in the deflection plate 251 of Fig. 3. In Fig. 5, four deflection electrodes 252a, 252b, 252c and 252d are arranged around a deflection hole 251, with two electrodes arranged above the deflection hole 251 and the remaining two electrodes arranged below the deflection hole 251. An electron beam B passes through

the deflection hole 251 in the lower right direction on the basis of the center of the deflection hole 251. In order to deflect the electron beam B toward the center of the deflection hole, voltages are applied to the deflection electrodes, thus changing the path of the electron beam B. Methods of applying voltages to the electrodes 252 to deflect the electron beam B can be variously implemented. For example, even if positive voltage is applied to the electrode 252a, the current electron beam B can move toward the center of the deflection hole. However, when voltage is applied only to the electrode 252a, a high voltage must be applied to a single electrode. Therefore, when positive voltage is applied to the electrode 252a and a negative voltage is applied to the electrode 252d, about half of the high voltage applied to the single electrode 252a can be applied both to the electrodes 252a and 252b, so that the electron beam can be easily performed. When voltages are applied to all of the four electrodes, lower voltages are applied to the four electrodes depending on the direction of the electron beam B, and thus the electron beam B can be deflected correspondingly.

[42] Therefore, there is no need to use four electrodes, as shown in the above drawings.

That is, an electron beam can be deflected using only one or more electrodes. The reason for this is that, when a positive voltage or negative voltage is selectively applied to the electrodes, an electron beam can be drawn or pushed, thus obtaining a predetermined deflection effect using only a single electrode according to the circumstances. Preferably, two or more electrodes are used. When two electrodes are used, they are preferably arranged to be perpendicular to each other, so that an electron beam can be deflected to a predetermined location by selectively applying a positive voltage or negative voltage to respective electrodes at need. When the number of electrodes is increased, there is an advantage in that the level of the voltage applied to the electrodes to control an electron beam can be decreased, but there may be a disadvantage in that, since the number of electrodes to be controlled increases, it is difficult to control the deflection of the electron beam. Therefore, it is preferable to determine the number or orientation of electrodes with reference to data about the extent of alignment.

[43] The deflection plate 250 of Fig. 3 includes electrodes, each having a large area, and is thus advantageous in that it can perform a gating or focusing function together with a deflection function. In order for the deflection plate 250 to perform a gating or focusing function, the voltage required for gating or focusing is determined, and voltages for respective orientations required for deflection are calculated and are then applied to respective electrodes.

[44] For example, if a voltage of 10V must be applied as a gating or focusing voltage, and a voltage of 20V must be applied to the electrode 252a, as in the case of the unit deflection hole of Fig. 5, a voltage of 30V needs to be applied to the electrode 252a,

and a voltage of 10V needs to be applied to the remaining electrodes. If the voltage required for deflection is -5 V at the same gating or focusing voltage, a voltage of 5V needs to be applied to the electrode 252a, and a voltage of 10V needs to be applied to the remaining electrodes. When a negative voltage increases to cause a problem in a focusing function or gating function in the case where a high negative voltage must be applied to a specific electrode as the voltage required for deflection, positive voltage, to be applied to other electrodes, is further increased, and a negative voltage, to be applied to the specific electrode, is further decreased, thus enabling the deflection plate to simultaneously perform both a deflection function and a focusing or gating function. That is, in this case, when voltage required for deflection is -10V at the same gating or focusing voltage, a method of applying a voltage of 5V to the electrode 252a and a voltage of 15V to the remaining electrodes can be used.

[45] Further, when the deflection plate is implemented using a single electrode layer in relation to the focusing function in the deflection FED according to the present invention, it is preferable to perform focusing by exploiting the gate 113 and the ITO layer 122 of Fig. 2, together with the deflection plate 150, and by utilizing the difference between the voltages of the three conductive layers. That is, the ITO layer 122 is mainly grounded and is used as a voltage of OV, constant voltage is applied to the gate 113, and predetermined voltage is adjustably applied to the deflection plate, as described above. Accordingly, focusing can be performed as in the case of a typical electronic lens by utilizing three conductive layers (gate, deflection plate, and ITO layer). Of course, the control of voltage is mainly performed by the deflection plate, and voltage can also be applied to the ITO layer if necessary. It is apparent that, when the deflection plate of the present invention is implemented using multiple electrode layers, the deflection FED can be used like the focusing lens of a typical electronic lens.

[46] In Fig. 4, the case where the wiring of respective electrodes is made to apply the same voltage for each orientation is described. The reason for this is that, when the cathode plate and the anode plate in the FED panel are uniformly misaligned with respect to respective reference pixels, the FED panel can be efficiently used. In other words, since expensive alignment equipment is generally used as equipment for aligning and assembling an FED panel, the deflection plate of the present invention is used in order to correct the misalignment of the FED panel and use the FED panel when the degree of misalignment is not serious. That is, the present invention is effective when electron beams emitted from respective micro-tips can pass through at least the deflection holes of the deflection plate. Therefore, the deflection holes of the deflection plate are preferably implemented to be as large as possible, and are not necessarily formed in the shape of circles but can be formed in the shape of polygons,

including triangles, as necessity requires. However, in this case, electrodes must be suitably selected and arranged according to necessity. If the anode plate and the cathode plate are misaligned due to twisting, it is possible to correct the path of electron beams to some degree by applying the same voltage for each orientation, but this correction may not be satisfactorily performed. When correction must be performed in the case where the degree of the twisting is serious, all of the electrodes arranged around each unit deflection hole must be separately controlled in some cases. In this case, the wring of respective electrodes is performed using a method of stacking the insulating plate 154 of Fig. 2 and forming respective wires through semiconductor etching, or a method of separately controlling respective pixels, thus separately controlling all of the electrodes. The reason for this is that, in the case of twisting, there is a need to apply separate voltages to respective unit electrodes.

[47] For an FED in which the deflection plate of the present invention can be used, various field emitters or electron emitters, such as a conventional Carbon-Nano-Tube (CNT) tip, a Cold Field Emitter (CFE), or a Thermal Emitter (TE), can be used.

[48] A conductor or semiconductor that can form an equipotential line when voltage is applied thereto can be used as the material of the deflection plate of the present invention. That is, the deflection plate can be manufactured using stacking technology used in the semiconductor field. In particular, when wiring is performed using an insulating part or an etching part, required for insulation between respective electrodes, a simpler deflection plate can be manufactured.

[49] Further, in the present invention, reference detectors may be arranged at about three positions on a deflection plate, a focusing plate or an anode plate, so that the degree of alignment between a cathode plate and an anode plate can be determined and calculated, and thus the degree of deflection can be controlled. Further, while this process is repeated or the voltages of deflection electrodes are changed, respective field emitters and corresponding unit fluorescent substances can be automatically aligned.

[50] Further, variable resistors are disposed in the wires between the input electrodes

357 and respective electrodes 352 of Fig. 4, or are disposed in predetermined locations in the FED. After the input voltages to be applied to the electrodes of the deflection plate are set to the same voltage, if voltages to be applied for respective orientations are adjusted by controlling the variable resistors, the degree of inherent misalignment of each FED panel can be calculated, and thus the misalignment can be corrected. When the FED panel is repaired or maintained, respective deflection voltages can be conveniently changed.

[51] In the above description, for convenience thereof, the plate to which fluorescent substances are attached is defined as an anode plate, but the same deflection effect as

that of the above description can be equally or similarly exhibited when the deflection plate of the present invention is disposed at a predetermined location before the location at which electron beams emitted from field emitters reach the fluorescent substances.

[52] When the deflection plate of the present invention is manufactured using a semiconductor manufacturing process, it can be manufactured in the form of a wafer, in which fine holes and electrodes can be formed. Industrial Applicability

[53] The present invention relates to a display device using an FED, which can be used for manufacturing FED devices.