Carbon nano-tube field emission display having strip shaped gate

#The present invention relates to a carbon nano-tube field emission display having strip shaped gate, and more particularly to using the strip shaped gate and the electric force from the side of the gate to confine the diffusion direction of the electron beam in the same direction, and achieve high luminous efficiency.

#A carbon nano-tube field emission display (CNT-FED) uses screen-printing processes and field emission display technology to achieve the capability of flat display panel from the conventional field emission display. It not only reserves the image quality of cathode-ray tube display but also provides the advantage of saving energy and small volume. Moreover, the above advantages combine with the low conductive electric field, the high emission current density and high stability of the carbon nano-tube simultaneously, so the CNT-FED can be a novel flat display with the advantages of low driving voltage, high luminous efficiency, no view angle problem, low energy consuming, large size and reduced cost.

#Referring to FIG. 1, which shows the schematic view of a conventional field emission display wit a triode structure, the triode structure is a common structure for improving the electron energy, the luminous efficiency and reducing the control voltage. The luminous principle of a conventional carbon nano-tube field emission display is shown in FIG. 1, the conventional CNT-FED includes a substrate 101 and a cathode electrode 102 formed on the substrate 101; a carbon nano-tube layer formed on the surface of the cathode electrode 102 as an electron emitter 103; a dielectric layer 104 formed adjacent to the cathode electrode and a gate 105; wherein a plurality of electrons arc induced from the cathode electrode 102 by the gate 105, and the direction of the electron current is shown as the direction of the arrowhead in FIG. 1. After that, an anode plate 107 is provided on the opposite side of the cathode electrode 102, and a phosphor layer 106 formed on one side of the anode plate 107 is bombarded by the electron beam, and red, green and blue colors are emitting through the glass substrate 108 to outside.

#FIG. 1 is a cross sectional schematic view showing a triode structure of a conventional field emission display (FED).

#FIG. 2 is a plan schematic view showing a first hole shaped gate structure of a conventional carbon nano-tube field emission display (CNT-FED).

#FIG. 3A is a schematic view showing a second hole shaped gate structure of a conventional carbon nano-tube field emission display (CNT-FED).

#FIG. 4A is a schematic view showing a carbon nano-tube field emission display (CNT-FED) having strip shaped gates according to a first embodiment of the present invention that uses the electric force from the side of the gate layer 305 to induce cathode electrons. In the structure according to the present invention, an anode plate 307 is on the upper position, so a plurality of electrons of a cathode electrode 302 is accelerated by the anode plate 307, and ten these electrons bombard a light-emitting layer 306, substantially symmetrical with said cathode electrode 302, formed on the anode plate 307 and made of light-emitting materials (ex. phosphor) to improve the luminous efficiency. In addition, as shown in the drawing, the carbon nano-tube Reid emission display according to the first embodiment of the present invention includes a substrate 301, and a cathode plate consists of a plurality of cathode electrodes 302 formed on the substrate. The cathode electrodes 302 are formed by screen printing a conductive layer or formed by patterning a metal film via photolithography and etching steps. The gate electrodes 305 are the strip shaped gates set along carbon nano-rube emitters 303 and are also formed by screen printing a conductive layer or formed by a metal film via photolithography and etching steps and they are at a distance to the substrate and the cathode electrodes by a dielectric layer 304 provided between the cathode electrodes 302 and the gate electrodes 305. The two gate lines at the outside position of the gate layers 305 can also be control electrodes 308. The carbon nano-tube emitters 303 provided on the cathode electrodes at the sides of the gate electrodes 305 are formed by screen printing technology, phololithography step plus etching step or photolithography step plus development step. Accordingly, the plurality of emitters 303 can't interfere with each other and the carbon nano-tube emitters 303 are made of carbon nano-tube material or any emit-able material to achieve the efficiency of the present invention. In the present invention, art anode plate 307 is provided at a distance from the substrate 301, wherein a light-emitting layer 306 having a plurality of light-emitting strips formed on a surface of the anode plate 307 substantially parallel and symmetrical with the cathode electrodes 302. An accelerated electric field is formed so a plurality of electrons induced from the carbon nano-tube emitters 303 by the gate electrodes 305 bombards the light-emitting layer 306 to show colors.

#The main feature of the structure, the carbon nano-tube field emission display having strip shaped gates according to the present invention, is: the direction of the gate electrodes 305 and the cathode electrodes 302 are perpendicular to one another, and moreover, on the basis of the design of the gate shape, the gate can attract the electrons from both sides of the cathode electrode 302 simultaneously or only one side of the cathode electrode 302. The carbon nano-tube emitters 303 is controlled under the strip shaped gate (the direction of the arrowhead in FIG. 4C).

#In addition, the high accuracy of the pattern alignment is not necessary for the strip shaped gate according to the present invention. Therefore, the advantage of the structure according to the present invention is that the diffusion direction of the electron beams from the carbon nano-tube emitters 303 is confined in the same direction and it can avoid the phenomenon that die electron beams diffuse in all-directions according to the conventional hole shaped gates. The processes for forming the CNT-FED according to the present invention are easier and the yield is improved, and moreover, the surface emitting area according to the present invention is more than the conventional CNT emitter (hole shaped gates design).