Abstract:
A quick start energy-saving fluorescent lamp comprising a bulb holder assembly, a light tube, a glass shade, a protruding cold end, a thermal insulation glue, and an amalgam vapor source. The protruding cold end is disposed at the front end of the light tube and contacts with the glass shade. The thermal insulation glue is disposed outside and around the cold end. The amalgam vapor source is disposed inside the cold end. The lamp can work at high temperature with low temperature amalgam vapor source and maintain high luminous efficiency, and the lamp can reach the rated brightness quickly. A method for producing the lamp is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Pursuant to 35 U.S.C. §119 and the Paris Convention Treaty, this application claims the benefit of Chinese Patent Application No. 200910153707.5 filed Oct. 30, 2009 and No. 200910157040.6 filed Dec. 31, 2009, the contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to an energy-saving fluorescent lamp, and more particularly to a quick start shielded energy-saving fluorescent lamp, as well as a method for producing the same. 
         [0004]    2. Description of the Related Art 
         [0005]    Energy-saving fluorescent lamps, particularly shielded energy-saving fluorescent lamps, which are very similar to incandescent lamps in appearance, have aroused more and more attention. However, these lamps have a common disadvantage at work, i.e., it takes a long time to achieve the rated brightness. The disadvantage is decided by the inherent characteristics of conventional shielded energy-saving fluorescent lamps. The shade blocks the diffusion of the lamp heat, so the lamps have higher temperature than those without a shade (naked lamps). The working principle of the energy-saving fluorescent lamps is to generate light by maintaining low pressure mercury vapor. To achieve a high luminous efficiency, the mercury vapor pressure must be maintained at a reasonable value. When lamps work at high temperature, to obtain a suitable mercury vapor pressure, high temperature amalgam must be used. Upon turning on the lamps, the initial temperature is low, so is the mercury vapor pressure generated by the high temperature amalgam, the lamps have low brightness. With the increase of the lamp temperature, the mercury vapor pressure and the brightness increase, so does the luminous flux. Generally, it takes 60-120 seconds to reach 80% of the rated luminous flux. Thus, conventional shielded fluorescent lamps cannot be lighted immediately just like an incandescent lamp. The brightness is decided by the mercury vapor pressure, and the mercury vapor pressure is decided by a cold-end temperature. Thus, the light brightness is finally decided by the cold-end temperature. 
         [0006]    Because conventional fluorescent lamps adopt high temperature amalgam, they cannot be lighted immediately. Thus, to make the shielded fluorescent lamps lighted quickly, a sufficiently low temperature cold end can be disposed in the lamps so that the low temperature amalgam can be used. 
       SUMMARY OF THE INVENTION 
       [0007]    In view of the above-described problems, it is one objective of the invention to provide a shielded energy-saving fluorescent lamp that can use low temperature amalgam and reach rated brightness quickly. 
         [0008]    To achieve the above objectives, in accordance with one embodiment of the invention, there is provided a shielded energy-saving fluorescent lamp that can use low temperature amalgam and reach rated brightness quickly, the lamp comprising a bulb holder assembly, a light tube, a glass shade, a protruding cold end, a thermal insulation glue, and an amalgam vapor source; wherein the protruding cold end is disposed at the front end of the light tube and contacts with the glass shade; the thermal insulation glue is disposed outside and around the protruding cold end, and the amalgam vapor source is disposed inside the protruding cold end. 
         [0009]    In a class of this embodiment, a transparent truncated cone is disposed outside and encloses the protruding cold end; the thermal insulation glue is disposed inside the transparent truncated cone, and the larger opening of the transparent truncated cone faces the glass shade. 
         [0010]    In a class of this embodiment, the protruding cold end comprises a convex bubble and a convex bubble wall; a third electrode is disposed on the convex bubble and passes the convex bubble wall; an inner end of the third electrode extends into the light tube, and an outer end of the third electrode contacts with the glass shade; and the amalgam vapor source is adhered to the third electrode. 
         [0011]    In a class of this embodiment, the third electrode is two dumet wires. 
         [0012]    In a class of this embodiment, the protruding cold end comprises a convex bubble; the convex bubble contacts directly with the glass shade; the amalgam vapor source is a solid amalgam and disposed in the convex bubble; and a positioning device is disposed in the rear part of the convex bubble. 
         [0013]    In a class of this embodiment, the positioning device is a convex glass ring. 
         [0014]    In a class of this embodiment, the positioning device is a barrier. 
         [0015]    Advantages of the shielded energy-saving fluorescent lamp are summarized below: 
         [0016]    1) the protruding cold end disposed in the front end of the light tube contacts with the glass shade; the amalgam vapor source is disposed in the cold end; and the thermal insulation glue is disposed outside and around the cold end; all these ensure the light tube can utilize a low temperature amalgam vapor source (for example, spherical Bi—Sn—Hg pills with diameters of 1 mm and working temperature of less than 55° C.) even working at high temperature but not affect the luminous efficiency; thus, the shielded energy-saving fluorescent lamp can be lighted quickly; 
         [0017]    2) the thermal insulation glue disposed outside and around the cold end separates the heat air in the cold end from that in the glass shade, prevents the cold end from heating by the heat air in the glass shade; thus, the cooling effect of the cold end is improved and the temperature of the cold end can be further reduced; 
         [0018]    3) the transparent truncated cone is disposed outside and encloses the cold end; the thermal insulation glue is disposed inside the transparent truncated cone, and the larger opening of the transparent truncated cone faces the glass shade; all these reduce the use amount of the thermal insulation glue but not affect heat insulating effect, and reduce the production cost of lamps; and 
         [0019]    4) the third electrode is disposed on the convex bubble and passes the convex bubble wall; the inner end of the third electrode extends into the light tube, and the outer end of the third electrode contacts with the glass shade; and the amalgam vapor source is adhered to the third electrode; thus, the third electrode functions as a cooling channel of the cold end, on the one hand, absorbing the heat of the cold end and transferring to the glass shade where the heat is diffused, on the other hand, the third electrode plays the following roles: a) to support a solid amalgam: solid amalgams may roll in conventional lamps and cause the falling of the phosphor layer; in the invention, the solid amalgam is adhered to the third electrode, so the roll of the solid amalgam is prevented; b) to further reduce the amalgam vapor pressure: the third electrode is on the edge of the plasma formed in the lamp, due to the interaction of the carriers between the electrode and the plasma, a “cover layer” forms where electrochemical effect happens, which reduces the amalgam vapor concentration and further reduces the amalgam vapor pressure; and c) reducing the load of the inner wall of the cold end: the tip of the third electrode inside the cold end can effectively reduce the negative charges adhered to the phosphor layer of the inner surface of the cold end, thereby reducing the load of the inner wall of the cold end and reducing the temperature of the cold end. 
         [0020]    In accordance with another embodiment of the invention, there is provided another shielded energy-saving fluorescent lamp that can use low temperature amalgam and reach rated brightness quickly, the lamp comprising a lamp holder assembly, an upper shade, a lower shade, an electronic ballast, a spiral tube, a glass shade, a protruding cold end, and a thermal insulation glue; wherein the protruding cold end has a height of 4-10 mm and is disposed at the front end of the spiral tube and the top thereof contacts with the bottom of the inner wall of the glass shade; a mercury vapor source is disposed inside the protruding cold end; the thermal insulation glue is transparent and disposed at the bottom of the glass shade; and the protruding cold end is surrounded by the thermal insulation glue. 
         [0021]    In a class of this embodiment, the temperature characteristic of the mercury vapor source matches that of the cold end. 
         [0022]    In a class of this embodiment, the mercury vapor source is a solid amalgam or liquid mercury. 
         [0023]    In a class of this embodiment, the spiral tube comprises two tube holders, each provided with two guide wires; the lower shade comprises a shade body and a base plate; the shade body is connected with the upper shade; the base plate is provided with two tube mounting bases at its bottom; the tube mounting base is provided with tube mounting holes penetrating through the tube mounting bases and the base plate for connection with the shade body along its axial direction; the tube mounting holes match with the tube holder; the top of the tube mounting hole is provided with a limit plate used to limit the moving distance of the spiral tube; the electronic ballast is placed on the base plate, comprising a PCB circuit board with a component side and a solder side; the solder side faces the tube holder matching with the tube mounting hole; the PCB circuit board is provided with four wrap pins; the tube holder matches with the tube mounting hole; when the space between the end surface of the tube holder and the underside of the limit plate is controlled at 3-5 mm, four guide wires are wrapped on the four wrap pins, respectively. 
         [0024]    In a class of this embodiment, the PCB circuit board is provided with jacks matching with the wrap pins; the wrap pins are provided with a first and a second limit parts with four edge angles; the lower part of the first limit part is in tight contact with the jack; a part of the wrap pin located between the first and the second limit parts serves as the main part of the wrap pin; the guide wire is wrapped on the main part of the wrap pin; and the second limit part is used to limit the sliding distance of the guide wires. 
         [0025]    In a class of this embodiment, a circular groove matching with the opening of glass shade is formed between the inner wall of the upper shade and the outer wall of the shade body when the upper shade is covered on and fixed to the shade body; high viscosity inert organic silicon glue with poor fluidity is provided inside the circular groove. 
         [0026]    In a class of this embodiment, the PCB circuit board is provided with a notch used to receive the guide wire. 
         [0027]    In another respect, the invention provides a method for producing the shielded energy-saving lamp comprising the steps of:
       a) inserting two tube holders of the spiral tube into the tube mounting holes provided on the two tube mounting bases, respectively;   b) placing the PCB circuit board of the electronic ballast on the base plate of the lower shade, the solder side of the PCB circuit board facing the tube holder;   c) keeping the space between the end surface of the tube holder and the limit plate on the top of tube mounting hole at 3-5 mm, penetrating the guide wire of the tube holder through the notch on the PCB circuit board, and wrapping on the main part of the wrap pin;   d) fixing the upper shade to the shade body of the lower shade to form a circular groove matching with the opening of the glass shade between the inner wall of the upper shade and the outer wall of the shade body, arranging the power line as per conventional process, and installing the lamp holder assembly on the top of the upper shade;   e) injecting the high viscosity inert organic silicon glue with bad fluidity into the circular groove;   f) injecting transparent thermal insulation glue into the glass shade, the opening of the glass shade being upwards;   g) keeping an integrated structure formed through connection of the lamp holder assembly, the upper shade, the lower shade, and the spiral tube upright, the lamp holder assembly and the spiral tube being on the top and at the bottom, respectively; installing the spiral tube into the glass shade before solidification of the thermal insulation glue so that the top of cold end is in contact with the bottom of the inner wall of the glass shade, the cold end being located inside the thermal insulation glue;   h) pushing the spiral tube until the edge of the opening of the glass shade is thoroughly set into the organic silicon glue, the tube holder moving upward along the tube mounting hole when pushing the spiral tube;   i) shaping and positioning the energy-saving lamp with a fixture, placing the energy-saving lamp in the room with ambient temperature no less than 25° C. for more than 3 hours; and   j) unloading the fixture and placing the energy-saving lamp into a transfer box for more than 8 hours.       
 
         [0038]    As compared with the prior art, the invention is characterized in that a protruding part with a definite height is provided at the front end of the spiral tube to serve as the cold end. The protruding part has the lowest temperature on the whole spiral tube. The cold end contacts with the bottom of the glass shade, and is surrounded by the thermal insulation glue. The mercury vapor source is disposed in the cold end so that the tube working in the environment of high temperature is available for use of low-temperature mercury vapor source. This is conducive to the maintenance of luminance of the energy-saving lamp as well as realization of quick start. The thermal insulation glue blocks the hot air from the inside of the glass shade and thus properly controls the temperature of the cold end. It is applicable to ensure ideal luminance and quicker increment in luminous flux of the spiral tube through selection of mercury vapor source whose temperature characteristic is in compatible with that of the cold end. 
         [0039]    Conventional assembly methods of a shielded energy-saving lamp affect the yield and quality. However, the assembly method of the invention has good effects. As indicated by experiments and experimental results, the contact between the cold end on the top of each spiral tube and the bottom of the inner wall of the glass shade is almost perfect and is not affected by the dimensional tolerance of the spiral tube and the glass shade. Furthermore, the method is also available for one-off abutting joint installation, before solidification of the thermal insulation glue, between the spiral tube and the glass shade as well as between the opening of the glass shade and the groove formed between the upper and the lower shade. Thus, it can significantly improve the yield and quality of the energy-saving lamp. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    The invention is described hereinbelow with reference to accompanying drawings, in which: 
           [0041]      FIG. 1  is a schematic diagram of a shielded energy-saving fluorescent lamp according to one embodiment of the invention; 
           [0042]      FIG. 2  is a schematic diagram of another shielded energy-saving fluorescent lamp according to one embodiment of the invention; 
           [0043]      FIG. 3  is a partial enlarged view of  FIG. 1 ; 
           [0044]      FIG. 4  is a partial enlarged view of  FIG. 2 ; 
           [0045]      FIG. 5  is a partial view of still another shielded energy-saving fluorescent lamp according to one embodiment of the invention; 
           [0046]      FIG. 6  is a partial view of still another shielded energy-saving fluorescent lamp according to one embodiment of the invention; 
           [0047]      FIG. 7  is a partial view of still another shielded energy-saving fluorescent lamp according to one embodiment of the invention; 
           [0048]      FIG. 8  is an assembly schematic diagram of a shielded energy-saving lamp according to one embodiment of the invention; 
           [0049]      FIG. 9  is a partial view for illustrating the match between a tube holder and a tube mounting hole and between a guide wire and a wrap pin according to one embodiment of the invention; and 
           [0050]      FIG. 10  is a schematic diagram of a wrap pin of a shielded energy-saving lamp according to one embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0051]    For further illustrating the invention, experiments detailing a shielded energy-saving fluorescent lamp are described below. It should be noted that the following examples are intended to describe and not to limit the invention. 
       Embodiment 1 
       [0052]    As shown in  FIGS. 1 and 3 , a quick start shielded energy-saving fluorescent lamp comprises a bulb holder assembly  1 , a light tube  2 , and a glass shade  3 . A protruding cold end  4  is disposed at the front end of the light tube  2 . The protruding cold end  4  comprises a convex bubble  41  and a convex bubble wall  42 . A third electrode  5  is disposed on the convex bubble  41  and passes the convex bubble wall  42 . The third electrode  5  is two dumet wires. An inner end of the third electrode  5  extends into the light tube  2 , and an outer end of the third electrode  5  contacts with the glass shade  3  by pasting. A solid amalgam  6  is adhered to the third electrode  5 . A thermal insulation glue  7  is disposed outside and around the protruding cold end  4 . 
       Embodiment 2 
       [0053]    As shown in  FIGS. 2 and 4 , a quick start shielded energy-saving fluorescent lamp comprises a bulb holder assembly  201 , a light tube  202 , and a glass shade  203 . A protruding cold end  204  is disposed at the front end of the light tube  202 . The protruding cold end  204  comprises a convex bubble  241 . The convex bubble  241  contacts directly with the glass shade  203 . A solid amalgam  206  is disposed inside the convex bubble  241 . A barrier  208  is disposed in the rear part of the convex bubble  241  to limit the roll of the solid amalgam  206 . A thermal insulation glue  207  is disposed outside and around the protruding cold end  204 . 
       Embodiment 3 
       [0054]    As shown in  FIG. 5 , a quick start shielded energy-saving fluorescent lamp comprises a bulb holder assembly (not shown), a light tube  302 , and a glass shade  303 . A protruding cold end  304  is disposed at the front end of the light tube  302 . The protruding cold end  304  comprises a convex bubble  341 . The convex bubble  341  contacts directly with the glass shade  303 . A solid amalgam  306  is disposed inside the convex bubble  341 . A convex glass ring  309  is disposed in the rear part of the convex bubble  341  to limit the roll of the solid amalgam  306 . A thermal insulation glue  307  is disposed outside and around the protruding cold end  304 . 
       Embodiment 4 
       [0055]    As shown in  FIG. 6 , a quick start shielded energy-saving fluorescent lamp has the same structure as that in embodiments 1 and 3 except that a transparent truncated cone  410  is disposed outside and encloses the protruding cold end  404 . The thermal insulation glue  407  is disposed inside the transparent truncated cone  410 , and the larger opening of the transparent truncated cone  410  faces the glass shade  403 . The other reference numbers  402 ,  405 ,  406 ,  441 , and  442  represent the corresponding elements as disclosed in embodiment 1 and 3. 
       Embodiment 5 
       [0056]    As shown in  FIG. 7 , a quick start shielded energy-saving fluorescent lamp has the same structure as that in embodiment 2 except that a transparent truncated cone  510  is disposed outside and encloses the protruding cold end  504 . The other reference numbers  502 ,  503 ,  506 ,  507 ,  508 , and  541  represent the corresponding elements as disclosed in embodiment 2. 
       Embodiment 6 
       [0057]    As shown in  FIGS. 8 ,  9 , and  10 , a quick start shielded energy-saving fluorescent lamp comprises a lamp holder assembly  601 , an upper shade  612 , a lower shade  613 , an electronic ballast  618 , a spiral tube  602 , a glass shade  603 , a protruding cold end  604 , and a thermal insulation glue  607 . The protruding cold end  604  has a height of 4-10 mm and is disposed at the front end of the spiral tube  602  and the top thereof contacts with the bottom of the inner wall of the glass shade  603 . A mercury vapor source  606  is disposed inside the protruding cold end  604 . The thermal insulation glue  607  is transparent and disposed at the bottom of the glass shade  603 . The protruding cold end  604  is surrounded by the thermal insulation glue  607 . The protruding cold end  604  is produced separately with a height d 1  as needed. The protruding cold end  604  transmits the heat outside via the inner wall of the glass shade  603  and the thermal insulation glue  607  blocks the hot air from the glass shade  603 . Thus, the protruding cold end  604  has the lowest temperature in the spiral tube  602 . The transparent thermal insulation glue  607  is mainly used to isolate the heat produced by the spiral tube  602  from the cold end  604 . 
         [0058]    To achieve good heat transmission effect, the cold end  604  is in direct contact with the inner wall bottom  653  of the glass shade  603 . Meanwhile, the transparent thermal insulation glue  607  isolates the heat produced by the spiral tube  602 . Thus, the temperature of the cold end  604  is effectively controlled. 
         [0059]    To ensure ideal luminance and quick increment in luminous flux for the spiral tube  602 , the mercury vapor source  606  whose temperature characteristic matches with that of the cold end  604  is selected. The mercury vapor source  606  is a solid mercury alloy (amalgam) or liquid mercury. 
         [0060]    The spiral tube  602  comprises two tube holders  641 , each provided with two guide wires  642 . The lower shade  613  comprises a shade body  631  and a base plate  632 . The shade body  631  is connected with the upper shade  612 . Two tube mounting bases  633  are provided at the bottom of the base plate  632 . A tube mounting hole  634  penetrating through the tube mounting base  633  and the base plate  632  for connection with the shade body  631  is provided on the tube mounting base  633  in axial direction. The tube mounting hole  634  matches with the tube holder  641 . It is no need to use glue to fix the tube holder  641  inserted into the tube mounting hole  634 . Thus, the tube holder  641  is available for vertical movement inside the tube mounting hole  634 , which facilitates free adjustment of expansion length of the spiral tube  602  when the glass shade  603  is enclosed. 
         [0061]    A limit plate  635  is provided on the top of the tube mounting hole  634  to control the moving distance of the spiral tube  602 . The electronic ballast  618  placed on the base plate  632  comprises a PCB circuit board  681  with a component side  682  and a solder side  683 . The solder side  683  faces the tube holder  641  matching with the tube mounting hole  634 . Four wrap pins  619  are provided on the PCB circuit board  681 . When the space d 2  between the end surface of the tube holder  641  and the underside of the limit plate  635  is at 3-5 mm, the tube holder  641  matches with the tube mounting hole  634  and four guide wires  642  are wrapped on the four wrap pins  619  respectively. Thus, the dimensional error upon producing the spiral tube  602  or the glass shade  603  can be offset by the motion range of 3-5 mm, and thereby forming a prefect contact between the cold end  604  and the inner wall bottom  653  of the glass shade  603 . 
         [0062]    The PCB circuit board  681  is provided with a jack  684  matching with the wrap pin  619 . The wrap pin  619  is provided with a first limit part  691  and a second limit part  692  with four edge angles. The lower section of the first limit part  691  is in tight contact with the jack  684 . The part of wrap pin  619  located between the first limit part  691  and the second limit part  692  serves as the main part  693  of the wrap pin. The guide wire  642  is wrapped on the main part  693  of the wrap pin. The second limit part  692  is used to limit the sliding distance of the guide wire  642 . The PCB circuit board  681  is provided with a notch  685  for receiving the guide wire  642 . The first limit part  691  and the second limit part  692  are fabricated through direct pressing on the wrap pin  619 . For conventional electronic ballasts, only one end of the wrap pins of the PCB circuit board is provided with a limit part used to fix the wrap pin into the jack. In the invention, two limit parts are provided, of which, the second limit part  692  plays a role of tightening the guide wire  642  on the spiral tube  602 . The guide wire  642  is unlikely to slip off after it is wrapped on the main part  693  of the wrap pin due to the obstruction of the second limit part  692 , which effectively prevents the guide wire  642  wrapped on the wrap pin  619  from sliding and becoming loose due to the advancement of the tube holder  641  to the tube mounting hole  634  in case of assembly of the energy-saving lamp. 
         [0063]    A circular groove  617  matching with an edge  652  of the glass shade  603  is formed between the inner wall of the upper shade  612  and the outer wall of the shade body  631  when the upper shade  612  is covered on and fixed to the shade body  631 . The circular groove  617  is provided with a high viscosity inert organic silicon glue with poor fluidity (not indicated in the figures). 
       Embodiment 7 
       [0064]    Conventional assembly methods of a shielded energy-saving lamp cannot ensure an effective contact between the cold end on the top of each spiral tube and the bottom of the inner wall of the glass shade and not affected by the dimensional tolerance of the spiral tube and the glass shade. Furthermore, with conventional methods, one-off abutting joint installation, before solidification of the thermal insulation glue, between the spiral tube and the glass shade as well as between the opening of the glass shade and the groove formed between the upper and the lower shade, cannot be achieved. The invention provides a method effectively solving the above problems. 
         [0065]    A method for producing the shielded energy-saving lamp comprises the steps of:
       a) inserting two tube holders  641  of the spiral tube  602  into the tube mounting holes  634  provided on the two tube mounting bases  633 , respectively;   b) placing the PCB circuit board  681  of the electronic ballast  618  on the base plate  632  of the lower shade  613 , the solder side  683  of the PCB circuit board  681  facing the tube holder  641 ;   c) keeping the space between the end surface of the tube holder  641  and the limit plate  635  on the top of tube mounting hole  634  at 3-5 mm, penetrating the guide wire  642  of the tube holder  641  through the notch  685  on the PCB circuit board  681 , and wrapping on the main part  693  of the wrap pin  619 ;   d) fixing the upper shade  612  on the shade body  631  of the lower shade  613  to form a circular groove  617  matching with the opening  651  of the glass shade  603  between the inner wall of the upper shade  612  and the outer wall of the shade body  631 , arranging the power line as per conventional process, and installing the lamp holder assembly on the top of the upper shade  612 ;   e) injecting the high viscosity inert organic silicon glue with bad fluidity into the circular groove  617 ;   f) injecting transparent thermal insulation glue  607  into the glass shade  603 , the opening  651  of the glass shade  603  being upwards;   g) keeping an integrated structure formed through connection of the lamp holder assembly  601 , the upper shade  612 , the lower shade  613 , and the spiral tube  602  upright, the lamp holder assembly  601  and the spiral tube  602  being on the top and at the bottom, respectively; installing the spiral tube  602  into the glass shade  603  before solidification of the thermal insulation glue  607  so that the top of cold end  604  is in contact with the bottom  653  of the inner wall of the glass shade  603 , the cold end  604  being located inside the thermal insulation glue  607 ;   h) pushing the spiral tube  602  until the opening  651  of the glass shade  603  is thoroughly set into the organic silicon glue, the tube holder  641  moving upward along the tube mounting hole  634  when pushing the spiral tube  602 ;   i) shaping and positioning the energy-saving lamp with a fixture, placing the energy-saving lamp in the room with ambient temperature no less than 25° C. for more than 3 hours; and   j) unloading the fixture and placing the energy-saving lamp into a transfer box for more than 8 hours.       
 
         [0076]    In the embodiments, the light tube  2 ,  202 ,  302 ,  402 , and  502  is spiral or in other acceptable shape. The glass cover  3 ,  203 ,  303 ,  403 , and  503  is bubble-shaped, spherical, barrel-shaped, or candle-shaped. The transparent truncated cone  410  and  510  may be a transparent plastic cone. 
         [0077]    While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.