Patent Publication Number: US-7896723-B2

Title: Method for making a silicon quantum dot fluorescent lamp

Description:
BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates to a silicon quantum dot fluorescent lamp and, more particularly, to a method for making a silicon quantum dot fluorescent lamp that efficiently transfers heat and provides a lot of electrons. 
     2. Related Prior Art 
     Fluorescent lamps containing mercury are often used. In such a lamp, electricity causes mercury vapor to discharge, thus generating ultraviolet light. The ultraviolet light excites three fluorescent materials to emit red, green and blue light, respectively. The mercury is however hazard to the environment. 
     In addition to Edison light bulbs and fluorescent lights, light emitting diodes (“LED”) are getting more and more popular. A white-light LED is operated in three patterns as follows: 
     Firstly, a red-light LED, a green-light LED and a blue-light LED are used together. The illuminative efficiency is high. However, the structure is complicated for including many electrodes and wires. The size is large. The process is complicated for involving many steps of wiring. The cost is high. The wiring could cause disconnection of the wires and damages to the crystalline grains, thus affecting the throughput. 
     Secondly, a blue-light LED and yellow fluorescent powder are used. The size is small, and the cost low. However, the structure is still complicated for including many electrodes and wires. The process is still complicated for involving many steps of wiring. The wiring could cause disconnection of the wires and damages to the crystalline grains, thus affecting the throughput. 
     Thirdly, an ultra-light LED and white fluorescent powder are used. The process is simple, and the cost low. However, the resultant light includes two separate spectrums. A red object looks orange under the resultant light because of light polarization. The color-rendering index is poor. Furthermore, the decay of the luminosity is serious. The quality of fluorescent material deteriorates in a harsh environment. The lamp therefore suffers a short light and serious light polarization. 
     There is another serious problem with the LED-based lamps. If looking directly at an LED-based lamp, a person will feel very uncomfortable in the eyes because of the intensive light emitted from the LED-based lamp. 
     The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art. 
     SUMMARY OF INVENTION 
     The primary objective of the present invention is to provide a silicon quantum dot fluorescent lamp that transfer heat efficiently and provides a lot of electrons. 
     To achieve the foregoing objective of the present invention, a silicon quantum dot fluorescent lamp is made via providing a high voltage source between a cathode assembly and an anode assembly. The cathode assembly is made by providing a first substrate, coating a buffer layer on the first substrate, coating a catalytic layer on the buffer layer and providing a plurality of nanometer discharging elements on the catalytic layer. The anode assembly is made via providing a second substrate, coating a silicon quantum dot fluorescent film on the second substrate with and coating a metal film on the silicon quantum dot fluorescent film. 
     Other objectives, advantages and features of the present invention will become apparent from the following description referring to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will be described via detailed illustration of the preferred embodiment referring to the drawings. 
         FIG. 1  is a flowchart of a method for making a silicon quantum dot fluorescent lamp according to the preferred embodiment of the present invention. 
         FIG. 2  is a side view of a first substrate for use in the method of  FIG. 1 . 
         FIG. 3  is a side view of a cathode assembly including the first substrate shown in  FIG. 2 . 
         FIG. 4  is a side view of another cathode assembly including the first substrate shown in  FIG. 2 . 
         FIG. 5  is a side view of a second substrate for use in the method shown in  FIG. 1 . 
         FIG. 6  is a side view of a silicon quantum dot fluorescent film on the second substrate shown in  FIG. 2 . 
         FIG. 7  is a side view of an anode assembly including the silicon quantum dot fluorescent film and the second substrate shown in  FIG. 6 . 
         FIG. 8  is a side view of another anode assembly including the silicon quantum dot fluorescent film and the second substrate shown in  FIG. 6 . 
         FIG. 9  is a side view of still another anode assembly including the silicon quantum dot fluorescent film and the second substrate shown in  FIG. 6 . 
         FIG. 10  is a side view of a silicon quantum dot fluorescent lamp including the cathode assembly shown in  FIG. 3  and the anode assembly shown in  FIG. 7 . 
         FIG. 11  is a side view of a silicon quantum dot fluorescent lamp including the cathode assembly shown in  FIG. 3  and the anode assembly shown in  FIG. 8 . 
         FIG. 12  is a side view of a silicon quantum dot fluorescent lamp including the cathode assembly shown in  FIG. 3  and the anode assembly shown in  FIG. 9 . 
         FIG. 13  is a side view of a silicon quantum dot fluorescent lamp including the cathode assembly shown in  FIG. 4  and the anode assembly shown in  FIG. 7 . 
         FIG. 14  is a side view of a silicon quantum dot fluorescent lamp including the cathode assembly shown in  FIG. 4  and the anode assembly shown in  FIG. 8 . 
         FIG. 15  is a side view of a silicon quantum dot fluorescent lamp including the cathode assembly shown in  FIG. 4  and the anode assembly shown in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , there is shown a method for making a silicon quantum dot fluorescent lamp according to the preferred embodiment of the present invention. 
     Referring to  FIGS. 1 and 2 , at  11 , a first substrate  21  is provided. The first substrate  21  may be made of silicon, glass, ceramic or stainless steel. 
     Referring to  FIGS. 1 ,  3  and  4 , at  12 , the first substrate  21  is coated with a buffer layer  22 , and the buffer layer  22  is coated with a catalytic layer  23 . The coating is done in an e-gun evaporation system or a sputtering system. The buffer layer  22  is made of titanium. The catalytic layer  23  is made of nickel, aluminum or platinum. Referring to  FIG. 3 , nanometer carbon tubes  24  are provided on the catalytic layer  23  in a chemical vapor deposition (“CVD”) process in which ethane or methane is used as a carbon source. Referring to  FIG. 4 , instead of the nanometer carbon tubes  24 , nanometer silicon wires  25  are provided on the catalystic layer  23  in a CVD process in which monosilane or dichlorosilane is used as a silicon source. The nanometer carbon tubes  24  and nanometer silicon wires  25  are made of nanometer sizes and with conductivity. 
     Referring to  FIGS. 1 and 5 , at  13 , a second substrate  31  is provided. The second substrate  31  is made of a transparent material such as glass, quartz and sapphire. 
     Referring to  FIGS. 1 and 6 , at  14 , the second substrate  31  is coated with a silicon quantum dot fluorescent film  32  of a high dielectric coefficient in a CVD process. The silicon quantum dot fluorescent film  32  includes a plurality of silicon quantum dots  321  of various sizes of 1 to 10 nm. The silicon quantum dots  321  are evenly distributed in the silicon quantum dot fluorescent film  32 . The silicon quantum dot fluorescent film  32  is a conductive or none-conductive matrix made of a material such as polymer, silicon oxide, silicon nitride and silicon carbide. 
     Referring to  FIGS. 7 through 9 , at  15 , in an e-gun evaporation system or a sputtering system, the silicon quantum dot fluorescent film  32  is coated with a metal film  33 , a patterned metal film  34  or a metal mesh  35 , thus forming an anode assembly  3 . The metal film  33 , the patterned metal film  34  or the metal mesh  35  transfers heat efficiently and provides electrons in addition to electrons released from the nanometer carbon tubes  24  or the nanometer silicon wires  25 . Each of the metal film  33 , the patterned metal film  34  and the metal mesh  35  is made of gold, silver, copper or aluminum. 
     Referring to  FIGS. 10 through 15 , at  16 , the nanometer carbon tubes  24  or the nanometer silicon wires  25 , which can discharge at the tips, are connected to an external high voltage source  4 , thus forming a field-effect electron source. The high voltage source  4  generates a voltage difference between the cathode assembly and the anode assembly, thus generating a field-effect electric field for accelerating the electrons in the field-effect electron source. The electrons hit and excite the silicon quantum dot  321  in the silicon quantum dot fluorescent film  32  to emit visible light. 
     The anode assembly consisting of the silicon quantum dot film  32  and the metal film  33 , the patterned metal film  34  or the metal mesh  35  increases the transfer of heat and the number of the electrons. 
     The present invention has been described via the detailed illustration of the preferred embodiment. Those skilled in the art can derive variations from the preferred embodiment without departing from the scope of the present invention. Therefore, the preferred embodiment shall not limit the scope of the present invention defined in the claims.