Abstract:
A method of manufacturing a multi-tube fluorescent discharge lamp which construct multiple glass tubes of different caliber in coaxial structure, the both sides of the inner most tube are connected to a cathode respectively, by isolating, perforating and blocking the discharge path, forming a successive discharge path, and coating phosphor on surface of the discharge tubes. The invention can then have more fluorescent area than a conventional fluorescent lamp of the similar size and higher lumen as well as power transfer factor. Compared with the power consumption of a conventional fluorescent discharge lamp, the invention therefore has higher luminous flux.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The Invention relates to fluorescent discharge lamps, and more particularly, to a method for a multi-tube fluorescent discharge lamps which construct multiple glass tubes of different caliber in coaxial structure, Both ends of the inner most tube are connected to a cathode respectively. By isolating, perforating and blocking the discharge path, to form a succession of interconnected discharge chambers, and coating fluorescent material on surface of the discharge tubes. Such an Invention can then have more fluorescent area than a conventional fluorescent lamp of similar size and have higher lumen as well as power conversion efficiency. By comparing with the power consumption of a conventional fluorescent discharge lamp, it is therefore has higher luminous flux. 
   2. Description of the Prior Art 
   A conventional fluorescent discharge lamp generally is straight or circular tube type. In order to minimize the size and increase luminosity, straight-shaped tube is bent into a wreath or U type for thin tube. Even in some cases, couples of short straight fluorescent tubes are aligned and connected in parallel, on both ends of the tube, it is connected with a cathode tungsten filament coated with oxide such as Ba, Sr and Ca. In the discharge tube, it is in a state of vacuum and with little Hg and Ar to facilitate the discharge process. 
   The cross-section of conventional fluorescent lamp tubes is usually a round shape and only one layer of fluorescent material such as phosphor is coated on the surface of the tube inside. When the cathodes on both ends of the tube are triggered by current and high-voltage power is applied electrons are released from the two cathodes, causing the tube glows and discharges. The gaseous Ar and Hg molecules are also stimulated to form plasma. Its ions and ultraviolet rays also impact the phosphor. The light is coming from conversion of energy potential. 
   Because cross-section area of a round tube is larger than that of any shape, the average density of electronic flux inside is lower than in other kinds. Furthermore, the electronic flux on the discharge path is concentrated nearby the axis of the discharge tube, whereas the density of the electronic flux nearby the surface of the discharge tube inside is low. 
   Therefore, the luminous flux in a round tube can not be enhanced proportionally by increasing the diameter to expand the area of phosphor. Much of energy nearby the axis in the discharge tube will be depleted and converted into heat and the conversion factor of the lumen (Lm) and Watt (W) insufficient. 
   Although there is another kind of lamp with lots of segmented built-in tubes and coated with phosphor to increase the luminous fluorescent area, but it does not form a succession of interconnected discharge path. Therefore, neither a stable discharge path or equable plasma status is not guaranteed, nor an adequate and complete luminescent of fluorescent layers is excited in the discharge tube, because the discharge path in takes the shortest distance. 
   Moreover, due to the narrow spectrum of conventional fluorescent discharge lamp, the color-rendering index (Ra) is low and the color temperature (K) is a bit high causing the illuminated object unable to reveal its colors. In addition because the cathode on both-ends of the conventional fluorescent discharge lamp is hit by electrons, the tungsten filament is then vaporized to become black and it pollutes the fluorescent layer of the tube, luminous efficiency of the fluorescent layer as well as the life cycle of the fluorescent discharge lamp. 
   SUMMARY OF THE INVENTION 
   This Invention is a multi-tube fluorescent discharge lamp; the design concept of the Invention is made of multiple discharge glass tubes of different calibers in a coaxial structure. By isolating, perforating and blocking the discharge path, and applying phosphor on the surface of the discharge tubes, this creates a thin and transparent film of fluorescent coating, allowing the light of the inner tubes to pass through each of the coatings to the outside of the lamp. In addition, a pair of hot or cold cathodes helps the electronic flux in the vacuum accelerate and hit the Hg molecule, which then create plasma. The coating of the fluorescent on the inner layer surface of the discharge tube is hit by electron ion and emit light. Under the same power rate and with the same lamp volume, the tubes of the multi-tube fluorescent discharge lamp aligned in a coaxial structure have a smaller cross-section area than that of a conventional fluorescent discharge lamp to allow higher density of electron flux to pass through the discharge path in the tubes. Therefore, the high-density electron ion has better stimulating effects on the fluorescent coating and the luminous fluorescent area is larger than conventional fluorescent discharge lamp, both of these advantages increase the luminous flux. 
   Compared to conventional fluorescent discharge lamp of the same power rate, this Invention is characterized by higher luminance, lower consumption of electric and lower heat rate. Moreover, because the electric flux of the Invention is less than that of a conventional fluorescent discharge lamp, the vaporization caused by electric flux hitting the cathode is slower and the life cycle of the cathode is longer than that of conventional fluorescent discharge lamps. It is also feasible to apply a ringed cathode to increase the surface area of the hitting electron flux and then disperse the hitting, so that the oxide material on the surface of the cathode can be protected from rapid consumption. In this way, multi-tube fluorescent discharge lamp can outlive conventional fluorescent discharge lamps. 
   A multi-tube fluorescent discharge lamp with a coated surface of various fluorescent materials has different color temperatures. The fluorescent material, when stimulated, can release different spectrum and create special colors after mixing. Alternatively it can include a wider spectrum to improve the color temperature (K) as well as color-rendering index (Ra) to be close to the sun&#39;s spectrum. 
   The multi-tube fluorescent discharge lamp is designed with coaxial structure, aiming to achieve special color luminance or a balanced spectrum range of light by way of filtering the luminance released from the transparent discharge glass tube of different colors. 
   The characteristics of this Invention can be specifically presented by the following detailed figures. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a partly broken side view of a conventional fluorescent discharge lamp. 
       FIG. 2  to  FIG. 9  are cross-sectional views and end views showing a step-by-step process of fabrication of a three-tube fluorescent discharge lamp of a first embodiment. 
       FIG. 10  is a cross-sectional view and end view of the five-tube combination with phosphor of a second embodiment. 
       FIG. 11  is a cross-sectional view and end view of an electrode portion with a straight cathode. 
       FIG. 12  is a cross-sectional view and end view of an electrode portion with a ring cathode. 
       FIG. 13  is a cross-sectional view and end view of a cap. 
       FIG. 14  is a cross-sectional view and end view of a cap combined an electrode portion with a straight cathode. 
       FIG. 15  is a cross-sectional view and end view of a cap combined an electrode portion with a ring cathode. 
     FIG.  16  and  FIG. 17  are cross-sectional view to follow the  FIG. 9  showing a step-by-step process of fabrication of the three-tube fluorescent discharge lamp of the first embodiment. 
       FIG. 18  is a cross-sectional view of a three-tube fluorescent discharge lamp of a third embodiment. 
       FIG. 19  is a cross-sectional view of a dual-tube fluorescent discharge lamp of a fourth embodiment. 
       FIG. 20  is a cross-sectional view showing a five-tube portion and a pair of electrode portions of the five-tube fluorescent discharge lamp of the second embodiment. 
       FIG. 21  is a cross-sectional view of the three-tube fluorescent discharge lamp of the first embodiment showing a pair of bases unattached. 
       FIG. 22  is a cross-sectional view of the full schematic three-tube fluorescent discharge lamp of the first embodiment. 
       FIG. 23  is a cross-sectional view of the full schematic five-tube fluorescent discharge lamp of the second embodiment. 
       FIG. 24  is a partly broken and cross-sectional view of the full schematic three-tube fluorescent discharge lamp of the first embodiment. 
       FIG. 25  is a partly broken and cross-sectional view of the full schematic five-tube fluorescent discharge lamp of the second embodiment. 
   

   DETAILED DESCRIPTION 
   According to  FIG. 1 , illustrates a conventional fluorescent discharge lamp. The discharge tube  8  is a straight glass tube. One cathodes  26 , with its electrode  28  connected to the terminal  42  on the tube base  40 , is located at each end of the tube. The figure shows clearly that there is only one phosphor layer  18  on the inside surface of the tube. In addition, because the density of electronic flux is higher at the axis of the discharge tube than at the phosphor layer  18  on the inside surface, much of the energy around the axis in the discharge tube will be wastefully converted into heat. Therefore, the power conversion factor of the lumen leaves some room for improvement. 
   According to  FIG. 2 , the first tube  10  is a round straight glass tube positioned at the innermost part of the multi-tube fluorescent discharge lamp. It is where the cathodes  26  as shown in  FIG. 1  are to be inserted. 
   According to  FIG. 3 , toward the middle of the first tube  10 , the glass is softened by heating with a flame of gas and oxygen or by means of an are heating. It is twisted at the softened middle part by turning around the two ends of the tube in mutually reverse direction. Thus an isolator  12  is formed, and the pipeline of the tube is blocked at the middle, insulating and separating the discharge path of the first tube  10  into two discharge chambers. 
   According to  FIG. 4 , air is blown into the first tube  10  from both ends, and heating is performed at several points around the two sides of the isolator  12 . This way, the plural-numbered through-holes  14  are formed. 
   According to  FIG. 5 , the second tube  16  is a round straight glass tube diameter is slightly larger than that of the first tube  10 . One end of the second tube  16  is air tight, and air is blown in either from the other end, or from both ends. Also, heating is performed at several spots around both ends of the tube, and the plural-numbered through-holes  14  are formed. 
   According to  FIG. 6 , the first tube  10  is slid into the second tube  16  to form a coaxial structure. Heating is performed around the second tube  16 , at a place that corresponds to the position of the isolator  12  in the first tube  10 , and then rotation is made at both ends of the second tube  16  in mutually reverse direction. This way, the heated, softened middle part of the tube is fused with first tube  10  into another isolator  12  that blocks the pipeline of the second tube  16  and separating the discharge path of the second tube  16  into two discharge chambers. 
     FIG. 7  demonstrates how the inner and outer surface of the first tube  10  and the second tube  16  are coated with the phosphor layer  18 . 
   According to  FIG. 8 , the third tube  20  is a round straight glass tube whose diameter is slightly larger than that of the second tube  16 , and the phosphor layer  18  is coated on the inner layer surface of the third tube  20 . 
   According to  FIG. 9 , the assembly of the first tube  10  and the second tube  16  is inserted into the third tube  20  to form a coaxial structure. 
   According to FIG.  10  and refer to FIG.  6 . After the assembly of the first tube  10  and the second tube  16  is slid into the third tube  20  to form a coaxial structures, the third tube  20 , with its diameter slightly larger than that of the second tube  16 , is heated around a site that corresponds to the isolator  12  of the second tube  16 . Then, rotation is performed at both ends of the third tube  20  in mutually reverse direction, and the softened part of the third tube  20  is fused with the isolator  12  of the second tube  16  into another isolator  12  that blocks the pipeline of the third tube  20  and separate the discharge path of the third tube  20 . Next, air is allowed in from both ends of the third tube  20 , heating is performed on the third tube  20  around several points at both side of the isolator  12  of the second tube  16 , and the plural-numbered through-hole  14  are formed. 
   The assembly Also, with a glass tube of the fourth tube  22 , which the diameter is slightly larger than that of the third tube  20 , to slide into the combination of the first tube  10 , the second tube  16 , and the third tube  20 , is then slid into the fourth glass tube  22 , one with a diameter slightly larger than that of the third tube  20  to form a coaxial structure. heating Heating is also performed on the circumference of the fourth tube  22  around the area that approaches approach to the isolator  12  of the third tube  20 . The two at both ends of the fourth tube  22  are turned around in mutually is rotated in reverse direction, and the softened part twisted at the softening place of the fourth tube  22  for fusing is twisted and fused with the isolator  12  of the third tube  20  for connecting and forming an into another isolator  12  that blocks the pipeline of the fourth tube  22  to seal the pipeline and divides the discharge path of the fourth tube  22  separating the discharge path of the fourth tube  22 , thus forming into two discharge chambers so that air can be blown in from both ends of the fourth tube  22 . Moreover, heating is performed on the circumference to approach around several spots at both ends of the fourth tube  22  and at the position of plural number, thus extruding producing plural-numbered through-holes  14  with plural. 
   The phosphor layer  18  is formed on both the inside and outside surfaces of the assembly of the first tube  10 , the second tube  16 , the third tube  20  and the fourth tube  22 . It can also be found on the inside surface of the fifth tube  24 . The assembly of the first tube  10 , the second tube  16 , the third tube  20  and the fourth tube  22 , is to be inserted into the fifth tube  24  to form a coaxial structure. 
   According to  FIG. 11 , the stem  34  is a hollow conical glass post with two ends of different diameters. Its smaller end can seal and fix the electrode  28 , which is attached to a straight cathode  26 . The pipe  32  is connected with the stem  34  and its opening hole  30  is located at the sealed end of the electrode  28  and allows exhaust to pass through the pipe  32 . 
   According to  FIG. 12 , and refer to FIG.  11 . The electrodes  28  is connected with a ring cathode  38 . 
   According to  FIG. 13 , the inner diameter of the cap  36  is same as the outer diameter of the first tube  10 , and the outer diameter of cap  36  is identical to the diameter of the outermost discharge tube. 
   According to  FIG. 14 , the structure of the stem is the same as that illustrated in  FIG. 11 , but the larger end of the conical glass post is connected with the cap  36 , the outer diameter of which is identical to the diameter of the outermost tube of the multi-tube fluorescent discharge lamp. 
   Compare  FIG. 15  with FIG.  14 . The structure is identical, but the electrode  28  in  FIG. 15  is connected with the cathode  38 . 
   Take a look at FIG.  16  and FIG.  9 .  FIG. 16  also has a pair of stems  34 , which includes a cathode  26  and the paired electrode  28 , and which connects with a cap  36 . The said cathode  26  is assembled in each of the two discharge chamber of the first tube  10 . The outer diameter of the cap  36  is the same as that of the third tube  20 . 
   See to FIG.  17  and refer to the  FIG. 16. A  stem  34  with the cathode  26  is inserted into each of the two discharge chambers of the first tube  10 . The outskirts of both ends of all the assembled tubes are heated and melted together, sealing both ends of the tubes. 
   Alternatively, the cathode  26  with a pair of stems  34  linked with the cap  36  can be slid into each of the two discharge chambers of the first tube  10 . Heating is performed on the cap  36 , which is attached to the ends of all the tubes, so the two ends of all the tubes can be melted together and sealed. The sealing of the ends of all discharge tubes, together with the isolator  12  and the through-holes  14  of the first tube  10  and the second tube  16 , forms a succession of interconnected discharge chambers. 
   According to  FIG. 18 , the first tube  10  is a round straight glass tube, in which a pair of electrodes  28  and one pipe  32  with the said tube are inserted to form a coaxial structure. One end of the first tube is heating for softening, and then clamped, pressed and sealed. The pair of electrodes  28  and the pipe  32  can be fixed, and air is blown into the pipe  32 . By heating the sealed end, a hole  30  can be produced for exhaust to pass through the pipe  32 . A phosphor layer  18  is applied on the outside surface of the said tube, and the cathode  26  is installed onto the pair of electrodes  28 . At the other end of the assembly, the same process is to be performed on the other first tube  10 . 
   The second tube  16  is a round straight glass tube with a diameter slightly larger than that of the first tube  10 . Air is blown in from both ends of the second tube  16 , or one end of the said tube is air tight and air is blown in from the other end. Heating is preformed around several spots on both ends of the second tube  16 , thus producing the plural-numbered through-holes  14 . The second tube  16  is also heated toward the middle part, and both ends are rotated in mutually reverse direction so that the tube is twisted in the middle, where it is fused into an isolator  12  that blocks the path of the discharge tube and separate the discharge path of the second tube  16 . 
   The third tube  20  is a round straight glass tube with its diameter slightly larger than that of the second tube  16 . The phosphor layer  18  is formed on the inner layer surface of the third tube  20  and also on the inner and outer layer surface of the second tube  16 . 
   The cathode  26  of the first tube  10  can be slid into each of the two discharge chambers of the second tube  16  to form a coaxial structure. The two cathodes  26  are formed at the outskirts of both ends of the second tube  16  and the third tube  20  in order to seal both ends of all discharge tubes. The sealing of both ends of all discharge tubes, along with the isolator  12  and the through-holes  14  e installed near the two sides of the isolator  12 . Heating is performed at the outskirts of the two ends of the first tube  10  and the second tube  16 , thus sealing both ends of the tubes. Then it is slid into the third tube  20  to form a coaxial structure, and heating is also part of the second tube  16 , form a succession of interconnected discharge chambers. 
   As mentioned above, heating at the outskirts of the circumference at both ends of the first tube  10 , the second tube  16 , and the third tube  20 , can soften, melt, and seal both ends of all of the discharge tubes. Also, a cap  36  that fits in with the two ends of all discharge tubes can be attached to each end of the multi-tube structure. By heating the can  36 , the ends of the first tube  10 , the second tube  16 , and the third tube  20  can be melted and sealed, thus forming a succession of interconnected discharge chambers. 
   Assemblies with more than 5 tubes can be formed with the method mentioned above. Suppose the number of total tubes is N (N is an odd number), and each tube has a different diameter from the others. The isolator  12  can be formed around the middle that extends from the second tube  16  to the (N-1)th tube. The plural-numbered through-holes  14  can be formed around the ends of the even-numbered tubes from the second tube  16  to the (N-1)th tube, and also on both sides of the isolator  12  on the odd-numbered tubes from the third tube  20  to the (N-2)th tube. 
   In there, the phosphor layer  18  is coated on the inner and outer layer surface of the tubes from the second tube  16  to the (N-1)th tube, on the outer surface of the tube on the first tube  10 , and also on the inner surface of the Nth tube. A pair of electrode  28  on the cathode  26  is connected with terminals  42  on the base  40  at each end. 
   According to  FIG. 19 , the first tube  10  is a round straight glass tube. Heating is performed toward the middle of the first tube  10 , and rotation is made at both ends of the first tube  10  in mutually reverse direction. The softened part of the tube is twisted and fused into an isolator  12  that blocks the pipeline of the first tube  10  and forms two discharge chambers. Then, air is blown in from both ends of the said tube and heating is performed at several spots around the ends, resulting in the plural-numbered through-holes  14 . A phosphor layer  18  is formed on the outer surface of said tube. 
   A second tube  16  is a round straight glass tube with a diameter slightly larger than that of the first tube  10  and a phosphor layer on the inner surface of the second tube  16 . The first tube  10  is slid into the second tube  16  to form a coaxial structure. Besides, a pair of stems  34  is structured with a cathode  26 , a pair of electrodes  28 , a hole  30 , and a pipe  32 . Each of the two discharge chambers of the first tube  10  contains a cathode  26 . Heating is performed at the outskirts of both ends of the first tube  10  and the second tube  16  so as to melt and seal both ends of the first tube  10  and the second tube  16  together with the stem  34 . The isolator  12 , the through-holes  14  of the first tube  10 , and the sealing of both ends of all discharge tubes conspire to form a succession of interconnected discharge chambers. 
   Assemblies with more than 4 tubes can be formed with the method mentioned above. Let&#39;s say the number of total tubes is N (N is an even number), and each tube has a different diameter from the others. The isolator  12  can be formed around the middle that extends from the first tube  10  to the (N-1)th tube. The plural-numbered through-holes  14  can be formed on both sides of the isolator  12  on the odd-numbered tubes from the first tube  10  to the (N-1)th tube, and also around the ends of the even-numbered tubes from the second tube  16  to the (N-2)th tube. Also, a cap  36  on the stem  34  is attached to each end of the multi-tube, and heating is performed on the spots of the cap  36  that meet the assembled discharge tubes. This way, both ends of all the tubes can be melted and sealed. Therein, the phosphor layer  18  is applied on the inner and outer surfaces of the tubes from the second tube  16  to the (N-1)th tube, on the outer surface of the first tube  10 , and also on the inner surface of the Nth tube. A pair of electrodes  28  on the cathode  26  is connected to terminals  42  on the base  40  at each end. 
   Refer to  FIG. 20  FIG.  10 . The pair of stems  34  in  FIG. 20  is structured with a cathode  26 , a pair of electrodes  28 , and a cap  36 . The cathode  26  is assembled in each of the two discharge chambers of the first tube  10 . The outer diameter of the cap  36  is the same as that of the fifth tube  24 . The cap  36  is attached to each end of the first tube  10 , the second tube  16 , the third tube  20 , the fourth tube  22 , and the fifth tube  24 . Heating at the points where the two cans  36  meet all of the discharge tubes can seal both ends of all the tubes. With the isolator  12 , the through-holes  14 , and the sealing of both ends of all the discharge tubes, a succession of interconnected discharge chambers can be formed. 
   Assemblies with more than 5 tubes can be formed with the method mentioned above. Let&#39;s say the number of total tubes is N (N is an odd number), and each tube has a different diameter from the others. The isolator  12  can be formed around the middle that extends from the first tube  10  to the (N-1)th tube. The plural-numbered through-holes  14  can be formed around the ends of the even-numbered tubes from the second tube  16  to the (N-1)th tube, and also on both sides of the isolator  12  on the odd-numbered tubes from the first tube  10  to the (N-2)th tube. Therein, the phosphor layer  18  is applied on the inner and outer surfaces of the tube from the first tube  10  to the (N-1)th tube, and also on the inner surface of the Nth tube. A pair of electrodes  28  on the cathode  26  is connected to terminals  42  on the base  40  at each end. 
   Compare  FIG. 21  with  FIG. 17. A  base  40  with a pair of terminals  42  is attached to each of the two ends of the three-tube fluorescent discharge lamp. The electrodes  28  of the cathode  26  are welded to the said terminals  42  one to one. 
   As illustrated in  FIG. 22 , when negative HV is present at one of the electrodes  26  in one side of the first discharge tube  10 , electrons released from the electrode are attracted by the positive HV at the other electrode  26  in the other side of the discharge tube  10 . The electrons move into the second discharge tube  16  via the through-holes  14  of the first discharge tube  10 , and then travel into the third discharge tube  20  via the through-holes  14  of the second discharge tube  16 . The electrons that pass through the third discharge tube  20  will enter the second discharge tube  16  at the other end via the through-holes  14  of the second discharge tube and go on into the adjacent first discharge tube  10  via the through-holes  14  of the first discharge tube  10 . Here, the electrons hit the other electrode  26 . The positive of the electrode  26  are converted into negative ones during the next half cycle of the alternating current. At the other end of the discharge tube  10  with negative, the released electrons travel in the same manner, but in reverse direction, alone the route of the electron movement in the first half cycle, and arrive in time at the counterpart electrode  26  with positive charges. Meanwhile, the electronic ions and ultraviolet rays are excited by the discharge chamber of each discharge tube, causing the phosphor on the surface of each discharge tube to emit light. 
   Similarly in  FIG. 23 , when negative HV is present at one of the electrodes  26  in one side of the first discharge tube  10 , the electrons released from the electrode are attracted by the positive HV at the other electrode  26  in the other side of the first discharge tube  10 . The electrons move into the second discharge tube  16  via the through-holes  14  of the first discharge tube  10 , next travel into the third discharge tube  20  via the through-holes  14  of the second discharge tube  16 , then into the fourth discharge tube  22  by way of the through-holes  14  of the third discharge tube  20 , and finally into the fifth discharge tube  24  by passing the through-holes  14  of the fourth discharge tube  22 . The electrons that passing through the fifth discharge tube  24  will enter the fourth discharge tube  22  at the other end via the through-holes  14  of the fourth discharge tube  22 , then into the adjacent third discharge tube  20  from the through-holes  14  of the third discharge tube  20 , next into the neighboring second discharge tube  16  via the through-holes  14  of the second discharge tube  16 , and finally reaching the hugging first discharge tube  10  from through-hole  14  of the first discharge tube  10 . Here, the electrons hit another electrode  26 . The positive charges of the electrode  26  are converted into negative during the next half cycle of the alternating current. At the other end of the discharge tube  10  with negative, the released electrons travel in the same manner, but in reverse direction, along the route of the electron movement of the first half cycle, and arrive in time at the counterpart electrode  26  with positive. During this process, electronic ions and ultraviolet rays are excited by the discharge chamber of each discharge tube, causing the phosphor on the surface of each discharge tube to emit light. 
     FIG. 24  shows the relative positions of all the discharge tubes. The isolator  12  is formed near the middle across the first tube and the second tube. The cathode  26  is located in each of the two discharge chambers of the first tube  10 . The plural-numbered through-holes  14  are formed around both sides of the isolator  12  of the first tube  10  and at both ends of the second tube  16 . The phosphor layer  18  is coated on the inner and outer surfaces of the first tube  10  and the second tube  16 , and also on the inner surface of the third tube  20 . The paired electrodes  28  on the cathode  26  are connected with the terminals  42  on the base  40  at each end of the tube. 
     FIG. 25  demonstrates a similar, though more complex, mapping of the relative positions of all the discharge tubes. The isolator  12  is formed near the middle across the first tube  10 , the second tube  16 , the third tube  20 , and fourth tube  22 . The cathode  26  is located in each of the discharge chambers of the first tube  10 . The plural-numbered through-holes  14  are formed around both sides of the isolator  12  of the first tube  10  and of the third tube  20 . Other plural-numbered through-holes  14  are created around both ends of the second tube  16  and of the fourth tube  22 . The phosphor layer  18  is applied on the inner and outer surfaces of the first tube  10 , the second tube  16 , the third tube  20 , and the fourth tube  22 , and also on the inner surface of the fifth tube  24 . A pair of electrodes  28  on the cathode  26  are connected with the terminals  42  on the base  40  at each end of the multi-tube. 
   Subsequently, the assembly of tubes is heated on the outside. Meanwhile, dry air is blown in from the pipe  32  at one end and exits through the pipe  32  at the other end so as to accelerate the drying process of the phosphor layers. After the drying process is completed, one of the pipes  32  is heated and sealed, and then several mg of mercury (Hg) is injected into the discharge chamber from the other pipe  32 . What follows, the discharge chamber is vacuumed and then filled with a little Ar gas, such as several hundred Pa in pressure. Then the pipe  32  is sealed. Afterwards, the assembly of tubes is placed in an electromagnetic environment, such as a microwave chamber, to agitate the liquid Hg into vapor Hg. After high-voltage currents go through the two cathodes, a radiating glow will be generated in the discharge lamp.