TWI250819B - Method for making a field emission display - Google Patents

Abstract

The present invention relates to a method for making a triode type field emission display. A preferred embodiment of the invention comprises: dispersing a number of carbon nanotubes onto a cathode layer formed on an insulating substrate; forming an insulating layer on the cathode layer perpendicular to a length direction of the cathode layer; forming a gate electrode on a top of the insulating layer; making the carbon nanotubes located nearby two sides of the gate electrode standing up on the cathode layer; packaging and sealing a phosphor plate and a spacer, therefore a field emission display is obtained. According to the embodiment, electrons are extracted from the carbon nanotubes and are deflected and focused on a center area of a corresponding pixel by the gate electrode.

Description

1250819

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fabricating a flat-panel display. [Prior Art] After the field emission display (LCD) display, the existing display is large, the power consumption is small, and the body emission display is more and more important, and the nano-carbon tube system is more and more important, and the local electric field is almost small. The best known field of the tube system is about 2 volts/micron, which is stable, so it is very suitable for the carbon tube growth technology. The so-called two-pole type structure requires a control and a continuous application of the drive circuit. The three poles have gates to control the new theory of electrons, and the emission of the emitters is very mature. The launching of the emitters includes the costly structure of the Canadian power transmission, especially involving a cathode, followed by a cathode ray tube (CRT). ) Display and LCD, under the most development potential - on behalf of emerging technologies. Phase-emitting display has the advantages of good display effect and small viewing angle, especially based on the carbon nanotube field emission display (CNT_FED) of carbon nanotubes. In recent years, carbon materials have excellent conductivity. The end surface area (the larger the tip surface area is, the greater the % enhancement factor), so the nano carbon material, which has a very low on-state electric field (large current density, and emits an emitter of the current-emitting display. With the nano 'nano carbon The research of the tube field emission display can be divided into two-pole type and three field emission structures with anode and cathode. This pressure is not suitable for high-resolution displays. Improvement based on the polar type, the increase can be achieved under lower voltage conditions

Page 6 1250819 V. INSTRUCTIONS (2) "'-'Electronics' and electron emission is easily controlled by the gate. As shown in FIG. 11, a typical three-pole field emission device comprises a substrate 101, an insulating layer 1〇2 formed on the substrate 101, and a gate 103 formed on the insulating layer 102, wherein the substrate is insulated. The layer 1 〇 2 and the gate 1 〇 3 are formed with perforations 104 to allow electrons to pass therethrough, and at the bottom end of the perforations 1 〇 4 are formed electron-emitting emission elements 105, which are also cathodes. Further, the anode 1〇6 and the phosphor layer 1〇7 are located at a position spaced apart from the gate electrode 1〇3 by a certain distance. In use, different voltages are applied to the anode 丨〇6, the gate 丨〇3 and the cathode, and electrons can be emitted from the emitting element 105, pass through the through hole 1〇4, and then accelerate under the electric field formed by the anode 1〇6. Upon reaching the anode 丨〇6 and the phosphor layer 丨〇7, the excitation phosphor layer 107 emits visible light. Generally, the voltage of the anode 1 〇 6 is several thousand volts, and the voltage of the gate 103 is about 1 volt. In the field emission display device of this structure, the electrons emitted by the electrons of the two sides of the gate 丨03 act, and a large portion of the electrons 110 and 111 are deflected at a large angle. There are few electric horns hitting the center of the area facing the transmitting element 105, which results in a large display element point, which is difficult to adapt to a high-resolution flat display; even a small portion of the electrons can hit the fluorescent In the area of layer 1〇7, there are many electrons hitting the edge area, and the number of electrons hitting the central position is small, causing the central point of the element to be dark and the edge to be bright. *Please refer to the twelfth figure, in order to solve the above problem, the improved structure is proposed by U.S. Patent No. 6,445, 1 24, published by the researcher of the T〇shiba company, Hironori Asai, et al., September 3, 203. A substrate 211 is formed. A cathode layer 203 is formed on the substrate 211. The insulating layer 2〇2 and the gate electrode 2〇1 are sequentially formed on the cathode layer 202, and are formed with perforations at the bottom of the perforation 1250819. Description (3) An electron-emitting layer 2 〇7 is formed on the end and cathode layers 2 0 3 for emitting electrons. The improvement is that the above structure needs to conform to the ratio of L/s to be greater than or equal to 1 'where the diameter of the S-type perforation, [the shortest distance from the electron emission to the gate 2 〇1] is also the electron emission layer 2〇7 The shortest distance from the gate 2. The structure of s is relatively large, that is, the distance between the electron-emitting end of the electron-emitting layer 2 〇7 and the gate 2〇1 is large, so that the gate 2〇1 needs a very high voltage to form a sufficient electric field to act on the electron. It is not easy to reduce the emission voltage and also increase the power consumption of the device. Further, since the electron emission layer 2 〇7 is located at the bottom end of the insulating layer 2 , 2, the electron emission point is away from the gate. The pole 2〇1 is far away, and most of the emitted electrons are blocked and absorbed by the insulating layer 20 2 (this is also the reason why the structure can reduce the lateral diffusion of electrons), so the effective utilization rate of the emitted electrons is low. It is inevitable to affect the display brightness of the image.曰[Contents] For the solution and the method of electrical technical problems, the electrons can correspond to the image display. The field emission display of the prior art field has a high gate emission voltage, and the gate around the sub-emitter has a diffusion effect on the electron emission. Etc. The object of the present invention is to provide a field emission display. The field emission display produced by the method can be emitted at a low voltage to effectively control the direction of emitted electrons, focus the electron beam to the element region, and reduce the electron beam. The width of the spot, the high resolution of the f, is a preparation method for achieving the above object, and comprises the following steps of conducting electricity formed on the surface of the insulating substrate. The present invention provides a field emission display. Step 1 is to distribute the carbon nanotube to the cathode. On the layer, step two, on the conductive cathode

1250819 V. INSTRUCTIONS (4) Forming an insulating layer orthogonally on the pole layer; Step 2, ^ Electrical grid; Step 4, so that the nanometers distributed on the layer of the ^, , and the edge layer are formed on the layer The carbon tube is erected on the conductive cathode fluorescent screen and the sealing sidewall on both sides of the conductive cathode sound 5. κ ° 9, step 5, the package is in contact with the prior art, the method of the invention has a tube formed around the center of the gate, the role of the nanocarbon and electrons, ie, the grid ^ : The thumb pole also has an electric field that can be used to move the electron beam to the high-resolution flat display of the electron beam. First, the spot on the screen becomes smaller, so that the embodiment of the present invention is described in detail with reference to the accompanying drawings and specific embodiments. Referring to the sixth item, the field emission of the embodiment of the present invention is crying. 1 is not intended to include a cathode 12 formed on the surface of the glass substrate 1 , an insulating layer 13 pressed against the cathode 12 in the longitudinal direction of the cathode 12 , and a gate electrode 14 formed on the edge layer 13 , which is vertically distributed on the insulating layer 13 cathodes on both sides. The upper carbon nanotubes 16 are formed on the phosphor layer 19 on the anode 18 at a corresponding distance above the gate electrode 14. The anode 18 is attached to the surface of the transparent glass plate 71 facing the cathode 12. . The cathode 12 is formed of a conductive material such as a 丨τ〇 (indium tin oxide) conductive film or a metal layer in the form of a strip or strip formed on the glass substrate ;; obviously when there are a plurality of cathodes 1 2 They may be formed parallel to each other on the surface of the glass substrate. The insulating layer 13 is made of an insulating material such as glass.

Page 9 Country 1250819 V. Invention Description (5) " The height of the carbon nanotube 16 is lower than the insulation layer 13 by a certain distance, that is, the top end of the carbon nanotube 16 is located at a certain distance below the gate 14 to avoid The pole 12 and the gate 14 are short-circuited; however, the height of the nanotube 16 is not itself: what is the limit, and the distance between the tip and the gate 14 is not limited to the range of the US Patent No. 6,445,124. The top end of the carbon nanotube 16 can be close to the gate 14 (but not in contact). Considering that the short circuit is too close to the gate 14, the distance between the top end of the carbon nanotube 16 and the gate 丨4 is moderate. That is, in order to reduce the turn-on voltage, the gate 14 can be as close as possible without affecting the emission of the electrons 20. In addition, it is necessary to find out that 'the height of the carbon nanotubes on the shell is very small, the diameter is very small' and often exists in the form of a carbon nanotube bundle. The figure shows that the single carbon nanotube 16 is only for the sake of simplicity. It is convenient to explain, and therefore, the scope of the invention cannot be limited thereby. The anode 18 can be made of an IT0 conductive film; a phosphor layer 19 is formed on the surface of the anode 18, and visible light can be emitted when bombarded by the electrons 20; the anode 18 is supported by the insulating spacer sidewalls 5, and the cathode 丨2, the gate 1 4 and the carbon nanotubes 16 are separated by a certain distance, and sealed and evacuated to form an internal space. Preferably, the shape of the insulating layer 13 is wedge-shaped, that is, the width of the bottom surface of the insulating layer 13 in contact with the cathode 12 is the largest, and the width of the top surface in contact with the gate electrode 14 is the smallest, and the width from the bottom surface to the top surface is gradually reduced. Referring to FIG. 1 to FIG. 6 together, the method for preparing the field emission display of the present invention comprises the following steps: Step 1 'Distributing the carbon nanotubes 16 on the surface of the insulating glass substrate 1

Page 10 1250819

The cathode can be made by a plurality of steps, for example, by applying the bis & 14 directly to the surface of the cathode 12 of the surface of the prepared glass substrate 10 . It can also be achieved by: a) preparing a hydrophilic cathode a on the surface of the glass substrate 1; after 1f, applying a hydrophobic photoresist 11 on the surface of the glass substrate 10, and using a standard photolithography process The photoresist crucible on the surface of the cathode crucible 2 is removed, so that the cathode 12 is exposed (as shown in the first figure); c) the carbon nanotubes are dissolved in an organic solvent, and dispersed by ultrasonication to prepare a carbon nanotube. The solution is prepared; d) the above treated glass substrate is vertically immersed in the prepared carbon nanotube solution so that the carbon nanotube adheres to the surface of the hydrophilic cathode ; 2; e) with an eluent (for example, acetone) The photoresist 11 is washed away so that a layer of carbon nanotubes is uniformly distributed on the surface of the cathode 12 (as shown in the second figure, wherein the carbon nanotubes are not shown). In step two, an insulating layer 丨3 is formed orthogonally on the cathode 12; the insulating layer 丨3 may be a glass material. A strip of glass paste can be printed by screen printing and then sintered to form an insulating layer 13 (as shown in the third figure). Thus, a portion of the carbon nanotubes (not shown) adhered to the surface of the cathode 12 may be completely covered by the insulating layer 13; a part of the carbon nanotubes may be covered with the insulating layer 13 at one end, and the other One of the carbon nanotubes is outside the insulating layer 13, and this portion of the carbon nanotubes can be an electron emitter after being processed in a subsequent step. In the third step, the gate electrode 14 is formed on the top end of the insulating layer 13. The gate electrode 14 is generally a metal material having good conductivity, such as silver or copper. Here, only silver is used as an example. The method of forming the gate 14 can be insulated by screen printing

Page 11 1250819 V. INSTRUCTIONS (7) A layer of silver paste is printed on the top of layer 1 3 and then sintered to form gate 14 (as shown in the fourth figure). In step four, the nanotubes 16 disposed on the surfaces of the cathodes 12 on both sides of the gates 14 are erected; this step can be carried out in various ways: it can be attached to the cathode surface with a sticky tape (not shown). In the above step 2, a portion of the carbon nanotubes covered by the insulating layer 13 and the other end exposed to the outside and a portion of the carbon nanotubes near the insulating layer 13 are adhered to the adhesive surface of the tape. The tape is pulled up to pull up the carbon nanotubes 6 which are originally poured on the surface of the cathode 12 to make them substantially erect on the surface of the cathode 12; or act on the carbon nanotubes 16 by a strong electric field so as to be substantially erected on the surface of the cathode 12. As a result, the upright carbon nanotubes 16 can be used as electron emitters as shown in the fifth figure. Step 5' encapsulates the phosphor screen and the side wall 丨5. The phosphor screen includes a transparent glass plate 1 7 'anode 1 8 and a phosphor layer 19. After centering, the exhaust (sucking vacuum)' final package completes the field emission display 1 (as shown in Figure 6). Referring to the sixth figure, when the field emission display 1 is used, different voltages are applied to the anode 18, the gate 14 and the cathode 12 (generally, the voltage of the anode 18 is 1 volt to several thousand volts, the gate The voltage of 14 is about tens of volts to 100 volts, the cathode 12 is grounded or zero voltage, and the electric field at the gate 14 acts = the electron 20 is emitted from the top of the carbon nanotube 16 and is electrically charged at the anode 18. Under the action of 'accelerating bombardment through the internal space to the phosphor layer 丨9 emits visible light. In the field emission structure of the present invention, the position of the gate electrode 14 corresponds to the center of each pixel of the phosphor layer 19, and the electron emitter carbon nanotubes i6 are respectively located at the sides of the gate electrode 14. Known as the central gate structure, the % emission of the present invention is not critical. In this way, the gate 丨4 not only plays electricity

Page 12 1250819 V. Description of the invention (8) The role of the sub-extraction from the top of the carbon nanotubes 1 6 , the role of the electrons emitted by the carbon nanotubes 16 is focused on the phosphor layer In the center of 1 9 , hit the small 'to achieve electronic correct, accurate bombardment is now more flat display of the south resolution. To further understand the field of the invention, the principle of electron beam focusing and other 5 sheep description Referring to the seventh figure, the field emission of the present invention is not intended. For convenience of explanation, the embodiment only emits electrons for explanation. In fact, the carbon nanotubes on both sides of the gate 14 are exposed to electrons. Basically, 'nano carbon nanotubes 16 are emitted into four types, that is, external electrons 21, and electrons 22 whose internal electrons 22 are reflected. The so-called external electrons 2 1 are electrons from the central grid 14 and such electrons. The receiving grid: the center position of the grid is deflected, and finally the focus is at the position. This distance R is not in the position of the fluorescent screen i 9 in the prior art. ^ ^ 〇〇^ 罝C in the dotted line table 7Ϊ electronic 2 2 series At the beginning of the launch, the initial direction is biased towards the center = the field is more advanced - Step #, but there is no electron of the extreme 14, the other side of the carbon tube 16 f: hit the screen 19 closer to the screen 19 and also focus on the center of the electron beam The spot on the electric field fluorescent screen 19 of the gate 14 is changed to a desired position, and the specific characteristics of the display can be real-time. The following is a further display of electrons emitted from the original pair of root carbon nanotubes. The action and the orbital electrons are divided by the electric field, the intercepted electrons 23 and the electric field of the initial direction of the polarizer 14 at the time of the emission are closer to the center of the phosphor layer 19 when the central gate 14 is at the center of the electron τ) The inner gate is 14 and is deflected by the gate to the insulating layer 13 or the phosphor layer 19 is opposite to the nanometer than the external electron 21 hits the heart 'ie less than the distance R.

Page 13 1250819

The worn-out electronic 23 and the internal electronic 22 are similarly deflected to the central gate 14, but due to the large angle of deflection, they are directly hit at the gate, and are captured by the grid 14 and cannot be fired. On the optical layer 19, the electrons that are deflected more are the reflected electrons 24, and the electrons are deflected at the most A, directly deflected on the layer 13, and are reflected by the insulating layer 13 and focused to the center of the phosphor layer 19. From the above analysis, it can be seen that the electron width finally hitting the phosphor layer 9 is 2R. Due to the special position of the gate 14 and the structure of the field emission display of the present invention, it is determined that the present invention has the above four types of electrons. With good focusing function, most of the electrons can be focused to the central area of the phosphor layer 19. The electrons in the edge area are relatively small. In addition, by adjusting the voltage of the gate 丨4 and the anode 丨8, the center is strengthened. The action of the gate 14 on the electron beam weakens the effect of the anode i 8 on the electron beam, and can further adjust the focusing effect of the electron. Therefore, the voltage of the gate 14 can be increased, or the voltage of the anode 18 can be lowered to reach Purpose, can also increase The distance between the pole 14 and the anode 18 is achieved. Further, by increasing the thickness of the central gate 14 4, the ability to intercept the electrons 23 at a large angle is stronger. The insulating layer 13 of the above embodiment has a wedge shape and a bottom width. Larger, the top surface width is smaller. The shape of the gate 14 is also wedge-shaped, the width of the bottom surface is the same as the width of the top surface of the insulating layer 13, and the top surface width of the gate 14 is the smallest. Of course, the gate 14 The shape may also be a rectangular parallelepiped shape or other suitable shape. Please refer to the eighth, ninth and tenth views together, the field emission display of the invention can also adopt non-wedge, other different shapes of insulation layer and gate structure. The eighth figure uses an insulating layer 4 3 with a rectangular cross section and an insulating layer.

1250819 V. DESCRIPTION OF THE INVENTION (10) The width of 43 is the same as that of the gate 44, and the carbon nanotubes 46 are distributed on both sides. The insulating layer 5 3 has a rectangular cross section, but has a smaller width than the gate 504, and the carbon nanotubes 56 are distributed on both sides of the gate 504. The insulating layer of the sixth embodiment has a shape in which the upper and lower ends are wide and the intermediate width is gradually reduced, and the carbon nanotubes 6 6 are located on both sides of the lower side of the grid 64. Variations in the above structure may result in differences in the orbit of the emitted electron beam from the wedge structure described above without departing from the scope of the invention.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the present invention are intended to be included within the scope of the following claims.

Page 15 1250819 BRIEF DESCRIPTION OF THE DRAWINGS The first to sixth figures are schematic diagrams of the steps of an embodiment of a method of fabricating a field emission display of the present invention. The seventh figure is a schematic diagram of the emission electron principle of the field emission display prepared by the method of the present invention. The eighth to tenth drawings are schematic views of insulating layers of different shapes and structures employed in the present invention. The eleventh figure is a schematic diagram of the structure and electron emission of a prior art three-pole field emission display.

The twelfth figure is a structure of a field emission device disclosed in U.S. Patent No. 6,445,124. [Main component symbol description] Field emission display 1 Glass substrate 10 Photoresist 11 Cathode 12 Insulation layer Carbon nanotube glass plate Fluorescent layer 13, 43, 53, 63 Gate 14, 14, 53, 63 16,46, 56,66 Sidewall 15 17 19 Anode 18 Electronics 20 , 21 , 22 , 23 , 24

Page 16

Claims (1)

1250819 The method for preparing a patent field emission field display includes the following steps: Step 1: distributing a carbon nanotube on a conductive cathode layer formed on the surface of the insulating substrate; Step 2, forming an insulating layer orthogonally on the conductive cathode layer; Step 3, forming a conductive gate on the insulating layer; Step 4, arranging a carbon nanotube disposed on the conductive cathode layer on both sides of the conductive gate on the conductive cathode layer; and step 5, Encloses the phosphor screen and seals the sidewalls. 2. The method for preparing a field emission display according to claim 1, wherein the step 1 comprises the following substeps: directly applying the nano tube charge to the conductive cathode on the surface of the prepared insulating substrate Layer surface. 3. The method for preparing a field emission display according to claim 1, wherein the step 1 comprises the following sub-steps: preparing a hydrophilic conductive cathode layer on the surface of the insulating substrate; coating a layer on the surface of the base of the ribbed edge a hydrophobic photoresist, and removing the photoresist on the surface of the conductive cathode layer by photolithography; preparing a carbon nanotube solution for use; immersing the above-mentioned treated insulating substrate in the prepared carbon nanotube solution to make the nanocarbon The tube is attached to the surface of the hydrophilic conductive cathode layer; the remaining photoresist is washed away. 4. The method of preparing a field emission display according to claim 1, wherein the length of the carbon nanotube is less than the thickness of the insulating layer. 5. The preparation method of the field emission display as described in claim 1 of the patent application scope Page 17 1250819 VI. Scope of Application for Patent Law 'The insulating layer is a broken glass material. 6. The clothing as described in item 5 of the patent application scope. The method, wherein the insulating layer is printed on the surface of the insulating layer by using a wire X £"", and then the sintered glass is formed by a squeegee method, as described in the scope of the patent application. In the body method, the width of the bottom surface of the insulating layer is the largest, and the top of the contact with the gate is a v% cathode layer. 8. The field emission as described in the scope of the patent application is the smallest. The method wherein the insulating layer is elongated, and the field emission method according to the first aspect of the invention is the method of crying, wherein the conductive gate is printed on the insulating layer through a screen. The top end is further formed by sintering. The water-based printing I 0 is the preparation method of the field emission display according to the invention of claim 1, wherein the step 4 includes the following sub-steps: the clothing is coated with a dry tape and is electrically conductive. On the surface of the cathode layer, the tape is pulled up to stand on the surface of the conductive cathode layer and the carbon nanotubes are erected on the surface of the conductive cathode. 曰II · The method for preparing the field emission display according to claim 1, wherein step four include The following sub-steps: generating a strong electric field acting on the carbon nanotubes, so that the carbon nanotubes stand upright on the surface of the conductive cathode layer under the electric field. 1 2 · Preparation of the field emission display according to claim 1 The method, wherein the conductive cathode layer comprises a conductive film. 1 3. The method for preparing a field emission display according to claim 12, wherein the method of claim 5, wherein the conductive film comprises ΙΤ0 conductive The method of producing a field emission display according to claim 1, wherein the phosphor screen comprises a transparent substrate, an anode, and a phosphor layer. I··第19页