Abstract:
A gas injection port structure for a flat fluorescent lap (FFL) is provided. The FFL has a flat lower plate and an upper plate that form a channel therebetween, and at least one gas injection port in communication with the channel. The gas injection port may be formed at a predetermined position on the upper plate so that a height of the gas injection port is level with or lower than a height of the channel. The gas injection port may contain a mercury getter and a sealing material having a passage formed therethrough so that mercury vapor may be injected into the channel and then the channel sealed. The gas injection port minimizes a thickness of the FFL, and improves durability of the FFL.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates, in general, to flat fluorescent lamps used as backlight units (BLU) in display devices, such as LCDs, and, more particularly, to a gas injection port structure of a flat fluorescent lamp (FFL), which is configured such that a gas injection port of the FFL is level with or lower than the height of a protruding channel provided on an upper plate of the FFL, thus minimizing the thickness of the FFL and accomplishing the recent trend of thinness of products having the FFLs. 
   2. Description of the Related Art 
   Generally, to produce a fluorescent lamp, first, a hollow glass body having a specific shape is provided by appropriately processing glass at a high temperature. Second, air is drawn out of the hollow glass body through a gas injection port so that the internal pressure of the glass body is reduced to form vacuum, and, thereafter, inert gas is injected into the vacuumized glass body through the gas injection port. After the first and second processes have been completed, the gas injection port is sealed. Conventional fluorescent lamps produced through the above-mentioned process may have various shapes, for example, linear shapes, specifically curved shapes and flat shapes. To allow the air to be drawn out of the hollow glass body of a fluorescent lamp to form a vacuum and the inert gas to be injected into the vacuumized glass body, a gas injection port is provided at each end of the glass body. Furthermore, an electrode may be provided at the gas injection port when necessary. 
     FIG. 1  is a perspective view illustrating the construction of a conventional flat fluorescent lamp (FFL)  10 .  FIG. 2  is a sectional view illustrating a gas injection port  14  of the FFL  10  of  FIG. 1 . As shown in the drawings, the conventional FFL  10  comprises a lower plate  11  having a flat shape, and an upper plate  12  having a protruding serpentine channel  13  and being integrated with the lower plate  11  into a single body. In the conventional FFL  10 , the protruding serpentine channel  13  is formed as a continuous long channel having a serpentine shape, both ends of which are separated from each other. 
   As shown  FIGS. 1 and 2 , the serpentine channel  13  that forms the lamp part of the FFL  10  is provided with a vertical gas injection port  14  at each end thereof. The gas injection port  14  is directed upwards from each end of the serpentine channel  13  on the upper plate  12  so that the port  14  protrudes to a predetermined height. During a process of manufacturing the FFL  10 , air is drawn out of the channel  13  through the gas injection ports  14  to form a vacuum in the channel  13 , and, thereafter, inert gas is injected into the vacuumized channel  13  prior to sealing the gas injection ports  14  using a sealing material. 
   However, the gas injection ports  14  of the conventional FFL  10  are directed upwards from the opposite ends of the channel  13  as described above, thus undesirably increasing the thickness of the FFL  10 . The above-mentioned increase in the thickness of the FFL  10  also thickens the display products, such as LCDs, produced using the FFLs  10 . 
   In addition to the above-mentioned problem, the upward directed gas injection ports  14  may induce damage to the upper plate  12  during the processes of drawing air out of the channel  13 , injecting inert gas into the channel  13 , and sealing the ports  14  after the inert gas has been injected into the channel  13 . Thus, the above-mentioned processes must be carefully executed, reducing work efficiency during the processes. Furthermore, to avoid damage to the gas injection ports  14  during the above-mentioned processes, the FFL  10  must be placed in a horizontal position from the start to the end of the processes, so that the FFL  10  requires a large working area. 
   In an effort to overcome the above-mentioned problems, another conventional FFL  20  having horizontal gas injection ports  24  as shown in  FIGS. 3 through 5  has been proposed. As shown in the drawings, one or more horizontal gas injection ports  24  are provided on the FFL  20  at predetermined positions of a channel  23 . Each of the gas injection ports  24  has a predetermined length and a throat having a semicircular cross-section, the sectional area of which is gradually reduced in a direction towards the channel  23 . A gas injection hole  25  is formed through a lower plate  21  of the FFL  20  so that the hole  25  communicates with the interior of an associated gas injection port  24 . 
   Furthermore, to draw air out of the channel  23  of an upper plate  22  of the FFL  20  and to inject inert gas into the channel  23  through the gas injection ports  24 , a nozzle  30  is provided at the inlet of each gas injection hole  25  of the lower plate  21 . The inside end of the nozzle  30  is provided with a flange  31  which has a diameter larger than the diameter of the gas injection hole  25 , with a stopper  32  placed on the flange  31  restricting the undesired flow of sealing material  26  out of the gas injection port  24 . Furthermore, an elastic sealing member  33  is interposed between the gas injection hole  25  and the flange  31  provided at the end of the nozzle  30 , thus providing a desired seal at the junction of the gas injection hole  25  and the flange  31 . Due to the gas injection ports  24  having the nozzles  30 , the processes of drawing air out of the channel  23  and injecting inert gas into the vacuumized channel  23  can be efficiently executed. 
   The sealing material  26  is provided in each of the gas injection ports  20 , with a passage  27  formed through the sealing material  26  in each of the gas injection ports  20 . Thus, the gas injection ports  24  communicate with the channel  23  of the upper plate  22  through the passages  27 . Due to the passages  27 , the sealing materials  26  do not interfere with the flow of air or inert gas during the processes of drawing the air out of the channel  23  and injecting the inert gas into the channel  23 . After the inert gas has been injected into the channel  23  through the gas injection ports  24 , the sealing material  26  is fused using a heater H. Thus, the passage  27  in each of the gas injection ports  24  is closed, so that the channel  23  is completely isolated from the atmosphere. 
   As described above, each of the gas injection ports  24  of the conventional FFL  20  illustrated in  FIGS. 3 through 5  must be provided with a nozzle  30  for drawing air out of the channel  23  and for injecting inert gas into the channel  23 . Therefore, the FFL  20  is problematic in that it is difficult to produce the FFL  20 . Furthermore, the gas injection ports  24  have a complex construction, causing difficulty and reducing work efficiency during the process of injecting the inert gas into the channel  23 . 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a gas injection port structure of a flat fluorescent lamp (FFL), which is configured such that a gas injection port is formed as a horizontal port lying on an edge of an upper plate of the FFL without being higher than the height of a protruding channel provided on the upper plate, thus minimizing the thickness of the FFL, and which simplifies the construction of the gas injection port and allows air to be easily drawn out of the channel and allows inert gas to be easily injected into the vacuumized channel, and, furthermore, allows the gas injection port sealing operation that follows the injection of the inert gas into the channel to be easily performed, thus improving work efficiency while manufacturing the FFLS. 
   In order to achieve the above object, according to a first embodiment of the present invention, there is provided a gas injection port structure of an FFL, the FFL having a flat lower plate, an upper plate having a protruding channel and being integrated with the lower plate into a single body, and a gas injection port provided on the FFL, wherein the gas injection port is formed on the upper plate of the FFL at a predetermined position while lying on the upper plate so that the gas injection port is level with or lower than the height of the protruding channel of the upper plate. The gas injection port may contain therein both a mercury getter and a sealing material having a passage formed through the sealing material from a first end to a second end of the sealing material. Furthermore, a gas injection pipe may be inserted into the inlet of the gas injection port, with a sealing tube interposed between the gas injection pipe and the gas injection port. 
   According to a second embodiment of the present invention, there is provided a gas injection port structure of an FFL, comprising two gas injection ports formed on the upper plate of the FFL at two predetermined positions while lying on the upper plate so that the gas injection ports are level with or lower than the height of the protruding channel of the upper plate. At least one of the two gas injection ports may contain therein a sealing material having a passage formed through the sealing material from a first end to a second end of the sealing material, with a gas injection pipe inserted into the gas injection port and a sealing tube interposed between the gas injection pipe and the gas injection port. Furthermore, a mercury vapor diffusing pipe, which is closed at a first end thereof and contains a mercury getter therein, may be inserted at a second end thereof into the other gas injection port, with a sealing tube interposed between the mercury vapor diffusing pipe and the gas injection port. 
   According to a third embodiment of the present invention, there is provided a gas injection port structure of an FFL, comprising a gas injection port formed on the upper plate of the FFL at a predetermined position while lying on the upper plate so that the gas injection port is level with or lower than the height of the protruding channel of the upper plate; a mercury vapor diffusing port formed on the upper plate at a side of the gas injection port; a mercury vapor diffusing pipe closed at a first end thereof and containing a mercury getter therein, and inserted at a second end thereof into the mercury vapor diffusing port, with a sealing tube interposed between the mercury vapor diffusing pipe and the mercury vapor diffusing port; and a connection passage connecting the mercury vapor diffusing port to the gas injection port, thus allowing the mercury vapor diffusing port to communicate with the gas injection port. The gas injection port may contain therein a sealing material having a passage formed through the sealing material from a first end to a second end of the sealing material. Furthermore, a gas injection pipe may be inserted into the gas injection port, with a sealing tube interposed between the gas injection pipe and the gas injection port. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a perspective view illustrating the construction of a conventional flat fluorescent lamp (FFL); 
       FIG. 2  is a sectional view illustrating a gas injection port of the FFL of  FIG. 1 ; 
       FIG. 3  is a perspective view illustrating the construction of another conventional FFL; 
       FIG. 4  is a perspective view illustrating a gas injection port of the FFL of  FIG. 3 ; 
       FIG. 5  is a sectional view illustrating a method of injecting gas into a channel of the FFL through the gas injection port of  FIG. 4 ; 
       FIG. 6  is a perspective view illustrating the construction of an FFL according to a first embodiment of the present invention; 
       FIG. 7  is a sectional view illustrating a gas injection port of the FFL of  FIG. 6 ; 
       FIG. 8  is a perspective view illustrating the construction of an FFL according to a second embodiment of the present invention; 
       FIGS. 9 and 10  are sectional views illustrating gas injection ports of the FFL of  FIG. 8 ; 
       FIG. 11  is a perspective view illustrating the construction of an FFL according to a third embodiment of the present invention; and 
       FIG. 12  is a sectional view illustrating a gas injection port of the FFL of  FIG. 11 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 
     FIG. 6  is a perspective view illustrating the construction of a flat fluorescent lamp (FFL) according to a first embodiment of the present invention.  FIG. 7  is a sectional view illustrating a gas injection port of the FFL of  FIG. 6 . 
   As shown in the drawings, the gas injection port structure of the FFL  20  according to the first embodiment of the present invention is configured such that only one gas injection port  40  is formed on an upper plate  22  at a predetermined position. In a detailed description, the gas injection port  40  is formed on the upper plate  22  at a position outside a protruding channel  23  such that the port  40  communicates with the internal space S of the channel  23 . The gas injection port  40  is a horizontal port that lies on the upper plate  22  such that the port  40  is level with or lower than the height of the channel  23 . Thus, the thickness of the FFL  20  is reduced, accomplishing the recent trend of thinness of products using the thin FFLs  20 . 
   The gas injection port  40  is provided to draw air out of the internal space S of the channel  23 , thus forming a vacuum, and, thereafter, to inject inert gas into the vacuumized space S of the channel  23 . Thus, the location of the gas injection port  40  on the FFL  20  is determined such that the port  40  most efficiently draws air out of the internal space S and most efficiently injects inert gas into the space S. 
   A sealing material  43 , which is fused when heated, is provided in the gas injection port  40 , with a passage  44  formed through the sealing material  43  such that the passage  44  completely extends from one end to the other end of the sealing material  43 . The passage  44  serves as a path, through which air passes outwards when the air is drawn out of the internal space S of the channel  23 , inert gas passes inwards when the inert gas is injected into the space S, and mercury vapor flows inwards when the mercury vapor is diffused into the space S as will be described in detail later herein. After the above-mentioned processes are completed, the sealing material  43  is heated and fused, thus sealing the gas injection port  40 . 
   A mercury getter  45  impregnated with mercury is placed in front of the inlet of the passage  44  formed through the sealing material  43  in the gas injection port  40 . The mercury getter  45  is used for diffusing mercury vapor into the internal space S of the channel  23  after air has been drawn out of the space S and inert gas has been injected into the space S. To diffuse the mercury vapor into the space S containing inert gas, high-frequency waves are transmitted to the mercury getter  45  so that the mercury getter  45  ruptures. Thus, mercury vapor from the ruptured getter  45  is diffused into the space S of the channel  23 . 
   When the mercury vapor has been completely diffused into the internal space S of the FFL  20 , air in the gas injection port  40  is heated using a heater (not shown) so that the sealing material  43  is fused and seals the gas injection port  40 . 
   Furthermore, a gas injection pipe  41  is axially inserted into the inlet of the gas injection port  40 . In the present invention, to provide a desired seal at the junction of the gas injection pipe  41  and the gas injection port  40 , a sealing tube  42  is preferably interposed between the outer surface of the pipe  41  and the inner surface of the port  40 . The gas injection pipe  41  is used for connecting a vacuum pump&#39;s nozzle (not shown) to the gas injection port  40  when air is drawn out of the channel  23  to form vacuum, or connecting an inert gas injector&#39;s nozzle (not shown) to the gas injection port  40  when inert gas is injected into the vacuumized space S. 
   In the above-mentioned first embodiment of the present invention, only one gas injection port  40  is provided on the FFL  20  at a predetermined position. However, two gas injection ports may be provided on the FFL  20  as shown in  FIGS. 8 ,  9  and  10  which illustrate a second embodiment of the present invention. In the second embodiment of the present invention, the two gas injection ports  50  and  50   a  provided on the upper plate  22  of the FFL  20  at two predetermined positions are separately used such that the first gas injection port  50  is used for drawing air out of and injecting inert gas into the internal space S of the channel  23 , while the second gas injection port  50   a  is provided with a mercury getter  56  therein, thus being used for diffusing mercury vapor into the space S of the channel  23 . 
   The construction of the first gas injection port  50  used for drawing air out of and injecting inert gas into the internal space S of the channel  23  is illustrated in  FIG. 9 , while the construction of the second gas injection port  50   a  provided with the mercury getter  56  therein and used for diffusing mercury vapor into the space S is illustrated in  FIG. 10 . As shown in  FIGS. 9 and 10 , a gas injection pipe  51  is axially and closely inserted into the inlet of the first gas injection port  50 , with a sealing tube  52  interposed between the pipe  51  and the port  50  to provide a desired seal. A mercury vapor diffusing pipe  55  closed at an outside end thereof and containing the mercury getter  56  therein is axially and closely inserted at an open inside end thereof into the inlet of the second gas injection port  50   a , with a sealing tube  52   a  interposed between the diffusing pipe  55  and the second gas injection port  50   a  to provide a desired seal. 
   In a similar manner as that described for the first embodiment, a sealing material  53 ,  53   a  having a passage  54 ,  54   a  is provided in each gas injection port  50 ,  50   a  of  FIGS. 9 and 10 . Therefore, after air has been drawn out of the internal space S of the channel  23  and inert gas has been injected into the space S through the first gas injection port  50 , the sealing material  53  in the first gas injection port  50  is heated and fused using a heater (not shown), thus sealing the first gas injection port  50 . 
   Thereafter, high-frequency waves are transmitted to the mercury getter  56  of the second gas injection port  50   a , thus rupturing the mercury getter  56  and diffusing mercury vapor from the ruptured mercury getter  56  into the space S of the channel  23 . After the diffusion of the mercury vapor into the space S, the sealing material  53   a  in the second gas injection port  50   a  is heated and fused using a heater (not shown) in the same manner as that described for the first gas injection port  50 , thus sealing the second gas injection port  50   a . The mercury getter  56  is placed in the diffusing pipe  55  that is axially and closely inserted into the inlet of the second gas injection port  50   a , with the sealing tube  52   a  interposed between the diffusing pipe  55  and the second gas injection port  50   a  to provide a desired seal. 
   In the gas injection port structure according to the second embodiment, the first gas injection port  50  used for drawing air out of and injecting inert gas into the internal space S of the channel  23  and the second gas injection port  50   a  provided with the mercury getter  56  and used for diffusing mercury vapor into the space S are separately provided on the FFL  20 , unlike the first embodiment. Thus, heat generated during the processes of drawing air out of and injecting inert gas into the space S of the channel  23  and the high-frequency waves transmitted to the mercury getter  56  during the process of diffusing mercury vapor into the space S are not concentrated on one gas injection port, but are distributed to the two gas injection ports  50  and  50   a . Thus, the gas injection port structure according to the second embodiment is advantageous in that it prevents damage or breakage of the gas injection ports. 
   Furthermore, due to the separate gas injection ports which comprise the first gas injection port for drawing air out of and injecting inert gas into the internal space of the FFL, and the second gas injection port containing a mercury getter for diffusing mercury vapor into the internal space of the FFL, the gas injection port structure of the second embodiment reduces the number of bad quality FFLs caused by undesired removal of the mercury getters from the gas injection ports. 
     FIGS. 11 and 12  are views illustrating the construction of a gas injection port structure of an FFL according to a third embodiment of the present invention. In the third embodiment, a gas injection port  60  is formed on the upper plate  22  of the FFL  20  at a predetermined position, with a mercury vapor diffusing port  65  formed on the upper plate  22  at a side of the gas injection port  60 . A mercury vapor diffusing pipe  66  closed at an outside end thereof and containing a mercury getter  67  therein is axially and closely inserted at an open inside end thereof into the inlet of the mercury vapor diffusing port  65 , with a sealing tube  62   a  interposed between the diffusing pipe  66  and the diffusing port  65  to provide a desired seal. The mercury vapor diffusing port  65  is connected to the gas injection port  60  through a connection passage  68  so that the diffusing port  65  communicates with the gas injection port  60 . 
   In other words, the gas injection port  60  is formed on the FFL  20  to directly communicate with the internal space S of the channel  23 , while the mercury vapor diffusing port  65  is formed on the FFL  20  such that the port  65  does not communicate with the internal space S, but communicates with the gas injection port  60  through the connection passage  68 . Thus, the gas injection port  60  is used for drawing air out of and injecting inert gas into the internal space S, while the mercury vapor diffusing port  65  is used for diffusing mercury vapor into the space S. A sealing material  63  having a passage  64  is placed in the gas injection port  60  at a position beyond a juncture at which the connection passage  68  is joined to the gas injection port  60 . 
   After the processes of drawing air out of and injecting inert gas into the internal space S of the channel  23  through the gas injection port  60  and the process of diffusing mercury vapor into the space S by transmitting high-frequency waves to the mercury getter  67  in the mercury vapor diffusing port  65  have been completed, the gas injection port  60  is heated using a heater (not shown), thus fusing the sealing material  63  and sealing the gas injection port  60 . 
   In the third embodiment, a gas injection pipe  61  and the mercury vapor diffusing pipe  66  are axially and closely inserted into the inlets of the gas injection port  60  and the mercury vapor diffusing port  65 , respectively, with a sealing tube  62 ,  62   a  interposed between each pipe  61 ,  66  and an associated port  60 ,  65  to provide a desired seal. 
   As described above, the gas injection port structure of the FFL according to the third embodiment of the present invention yields the same advantages as those described for the first and second embodiments. Furthermore, the third embodiment improves work efficiency when manufacturing the FFL, because the gas injection port  60  and the mercury vapor diffusing port  65  are placed adjacent to each other. 
   Furthermore, in the first, second and third embodiments of the present invention, when the processes of drawing air out of and injecting inert gas into the internal space of the channel of the FFL and the process of diffusing mercury vapor into the internal space of the channel have been completed, the gas injection pipe and the mercury vapor diffusing pipe may be removed from the gas injection port and the mercury vapor diffusing port, or cut such that ends of the pipes become level with the ends of the ports. 
   As apparent from the above description, the present invention provides a gas injection port structure of a flat fluorescent lamp (FFL), which is configured such that a gas injection port is formed as a horizontal port lying on an edge of an upper plate of the FFL without being higher than the height of a protruding channel provided on the upper plate, thus minimizing the thickness of the FFL and accomplishing the recent trend of thinness of products having the FFLs. 
   Furthermore, the present invention simplifies the construction of the gas injection port and allows air to be easily drawn out of the channel and allows inert gas to be easily injected into the vacuumized channel, and, furthermore, allows the gas injection port sealing operation that follows the injection of the inert gas into the channel to be easily performed, thus improving work efficiency while manufacturing the FFLs. 
   Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.