Patent Application
20110101845
This application claims all benefits accruing under 35 U.S.C. §119 from China Patent Application No. 200910110440.1, filed on Oct. 29, 2009 in the China Intellectual Property Office.
1. Technical Field
The present disclosure relates to a field emission cathode device based on carbon nanotubes, and display using the same.
2. Description of Related Art
Field emission displays (FEDs) are a new, rapidly developing flat panel display technology. Generally, FEDs can be roughly classified into diode and triode structures. In particular, carbon nanotube-based FEDs have attracted much attention in recent years.
Field emission cathode devices are important elements in FEDs. A field emission cathode device based on carbon nanotubes for triode FEDs usually includes an insulating substrate, a number of longitudinal cathodes attached on the substrate, a number of electron emission units including carbon nanotubes distributed on the cathodes, a dielectric layer, and a number of gate electrodes directly mounted on the top of the dielectric layer. Usually, the carbon nanotubes of the electron emission unit are fabricated on the cathode by chemical vapor deposition (CVD). However, the carbon nanotubes fabricated by CVD are not secured on the cathode. Thus, the carbon nanotubes tend to be pulled out from the cathode by a strong electric field force causing the field emission cathode device to have a short life.
What is needed, therefore, is a field emission cathode device that can overcome the above-described shortcomings and a display using the same.
Many aspects of the embodiments can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views.
The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one.
References will now be made to the drawings to describe, in detail, various embodiments of the present field emission cathode device and display using the same. The field emission cathode device can be applied to a diode FEDs or a triode FEDs.
Referring to
The insulative substrate 110 includes a top surface 1104 and a bottom surface 1106. The insulative substrate 110 defines a plurality of openings 1102. The openings 1102 extend through from the bottom surface 1106 to the top surface 1104. The cathode electrodes 120 are substantially parallel to each other and located at the bottom surface 1106. The gate electrodes 130 are substantially parallel to each other and located on the top surface 1104. Alignment directions of the cathode electrodes 120 intersect alignment directions of the gate electrodes 130. The extending direction of the cathode electrodes 120 can be substantially perpendicular to the extending direction of the gate electrodes 130. Each of the electron emission units 140 corresponds to one of the openings 1102 and is electrically connected to one corresponding cathode electrode 120. Each opening 1102 is covered by one of corresponding cathode electrodes 120. At least one portion of each electron emission unit 140 is fixed between the insulative substrate 110 and the corresponding cathode electrodes 120. Each of the electron emission units 140 is controlled by the one of the cathode electrodes 120, and one of the gate electrodes 130 and electrons can be independently emitted.
The insulative substrate 110 can be made of insulative material. The insulative material can be ceramics, glass, resins, quartz, or polymer. A size, a shape and a thickness of the insulative substrate 110 can be chosen according to need. The insulative substrate 110 can be square plate or rectangular plate with a thickness greater than 15 micrometers. The openings 1102 can be arranged according to a certain pattern. A diameter of each opening 1102 can range from about 3 micrometers to about 3 millimeters. In one embodiment, the insulative substrate 110 is a square polymer plate with a thickness of about 1 millimeter, an edge length of about 50 millimeters. The openings 1102 are arranged in a matrix, and the number of the openings 1102 is 10×10 (10 rows, 10 openings 1102 on each row). The diameter of each opening 1102 is about 2 millimeters.
The cathode electrodes 120 can be made of metal, alloy, conductive slurry, or indium tin oxide (ITO). The metal can be copper, aluminum, gold, silver or iron. The conductive slurry can include from about 50% to about 90% (by weight) of the metal powder, from about 2% to about 10% (by weight) of the glass powder, and from about 8% to about 40% (by weight) of the binder. In one embodiment, the cathode electrodes 120 are strip-shaped copper sheets.
The gate electrodes 130 can be made of material the same as the material of cathode electrodes 120. A plurality of through holes (not labeled) can be defined by the gate electrodes 130 and be in alignment with the openings 1102. A diameter of each hole can range from about 1 micrometer to about 3 millimeters. Each of the through holes corresponds to one of the openings 1102 so that the electron emission units 140 can be exposed. The gate electrodes 130 are optional. When the field emission cathode device 100 is applied to a diode FEDs, the field emission cathode device 100 can have no gate electrodes 130. In one embodiment, the gate electrodes 130 are strip-shaped conductive films made by printing conductive slurry.
Each of the electron emission units 140 can include at least one linear carbon nanotube structure 1402. The linear carbon nanotube structure 1402 can include at least one carbon nanotube wire and/or at least one carbon nanotube cable. A carbon nanotube cable includes two or more carbon nanotube wires. The carbon nanotube wires in the carbon nanotube cable can be, twisted or untwisted. In an untwisted carbon nanotube cable, the carbon nanotube wires are substantially parallel with each other. In a twisted carbon nanotube cable, the carbon nanotube wires are twisted with each other. A diameter of the linear carbon nanotube structure can range from about 50 micrometers to about 500 micrometers. Referring to
The carbon nanotube wire can be untwisted or twisted. The untwisted carbon nanotube wire can be obtained by treating a drawn carbon nanotube film, drawn from a carbon nanotube array with a volatile organic solvent. Examples of drawn carbon nanotube film, also known as carbon nanotube yarn, or nanofiber yarn, ribbon, and sheet are taught by U.S. Pat. No. 7,045,108 to Jiang et al., and WO 2007015710 to Zhang et al. Specifically, the organic solvent is applied to soak the entire surface of the drawn carbon nanotube film. During the soaking, adjacent parallel carbon nanotubes in the drawn carbon nanotube film will bundle together, due to the surface tension of the organic solvent as it volatilizes, and thus, the drawn carbon nanotube film will be shrunk into untwisted carbon nanotube wire. Referring to
The twisted carbon nanotube wire can be formed by twisting the drawn carbon nanotube film using a mechanical force to turn the two ends of the drawn carbon nanotube film in opposite directions. Referring to
Referring to
In one embodiment, each of the electron emission units 140 includes two linear carbon nanotube structures 1402 as shown in
In another embodiment, each of the electron emission units 140 includes only one linear carbon nanotube structure 1402 as shown in
Further more, a conductive layer (not shown) can be located between the insulative substrate 110 and the gate electrodes 130, or on an inner surface of the openings 1102. The conductive layer is electrically connected to the gate electrodes 130 and insulated from the electron emission units 140. The conductive layer can conduct the electrons stroked on the conductive layer and prevent the electrons emitted from the electron emission units 140 from striking the insulative substrate 110 and producing secondary electrons.
In the field emission cathode device 100, the fixing portion 1404 of each linear carbon nanotube structure 1402 is fixed between the insulative substrate 110 and the cathode electrodes 120. Thus, the electron emission units 140 are secured and cannot be pulled out from the cathode electrode 120 by electric field force in a strong electric field. The field emission cathode device 100 has a long life.
Referring to
The cathode substrate 102 and the anode substrate 104 are connected by an insulative supporter 105. The field emission cathode device 100 and the field emission anode device 106 are sealed between the cathode substrate 102 and the anode substrate 104. The field emission cathode device 100 and the field emission anode device 106 are spaced from each other and opposite to each other. The field emission cathode device 100 is located on a surface of the cathode substrate 102 and the field emission anode device 106 is located on a surface of the anode substrate 104.
The cathode substrate 102 can be made of an insulative material such as ceramics, glass, quartz, or silicon dioxide. The anode substrate 104 can be made of a transparent material such as glass. In one embodiment, both the cathode substrate 102 and the anode substrate 104 are glass plate.
The field emission anode device 106 can include an anode electrode 107 located on an inner surface of the anode substrate 104 and a fluorescent layer 108 located on a surface of the anode electrode 107. The anode electrode 107 can be an ITO film or a carbon nanotube film. The fluorescent layer 108 can include a plurality of luminescent units (not labeled). Each of the luminescent units corresponds to one of the electron emission units 140.
Finally, it is to be understood that the above-described embodiments are intended to illustrate rather than limit the disclosure. Variations may be made to the embodiments without departing from the spirit of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200910110440.1 | Oct 2009 | CN | national |
