Abstract:
A capacitive touch panel sequentially has a first transparent substrate, a lower touch sensitive layer, a lower conductor layer, a lower insulation layer, a lower conductive adhesive layer, a flexible circuit board, a transparent insulation adhesive laver, an upper insulation layer, an upper conductive adhesive layer, an upper conductor layer, an upper insulation ink layer, an upper touch sensitive layer and a second transparent substrate. The aforementioned structure allows fabrication of the capacitive touch panel to be separated into a lower panel fabrication process and an upper panel fabrication process. The two independent fabrication processes prevent the capacitive touch panel from being damaged in one of the processes when the process is completed, thereby increase the yield in production and further facilitate producing large-size touch panel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 12/803,763, filed Jul. 6, 2010, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a capacitive touch panel, and more particularly to a capacitive touch panel suitable for manufacturing large-size touch panel. 
         [0004]    2. Description of the Related Art 
         [0005]    Existing touch panels can be classified as resistive touch panels and capacitive touch panels. Recently, capacitive touch panels become increasingly popular in the touch screen market. 
         [0006]    With reference to  FIG. 6 , a conventional touch panel has a first glass substrate  61 , a lower touch sensitive layer  62 , an upper touch sensitive layer  63 , a flexible circuit board  64 , a transparent insulation adhesive layer  65  and a second glass substrate  66 . The first glass substrate  61  has a top surface and a bottom surface. The upper touch sensitive layer  63  and the lower touch sensitive layer  62  are respectively formed on the top surface and the bottom surface of the first glass substrate  61 . The flexible circuit board  64  is mounted on the top surface of the first glass substrate  61  and is partially and electrically connected to the upper touch sensitive layer  63 . The transparent insulation adhesive layer  65  is coated on the first glass substrate  61 . The second glass substrate  66  is covered and bonded on the transparent insulation adhesive layer  65 . 
         [0007]    However, the conventional technology involves separately forming the upper touch sensitive layer  63  and the lower touch sensitive layer  62  on the top and the bottom surfaces of the first glass substrate  61 , for example, forming the upper touch sensitive layer  63  first. Hence, when the lower touch sensitive layer  62  is formed subsequently, the completed upper touch sensitive layer  63  easily gets scratched or stained during the fabrication process of the lower touch sensitive layer  62 . As a result, the production yield is significantly lowered. Because of the low yield, such capacitive touch panels do not aim for large-size touch panel, thereby further limiting the application range thereof. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    In accordance with one embodiment, a capacitive touch panel includes a first substrate, a lower touch sensitive layer, a lower conductor layer, a transparent insulation adhesive layer, an upper conductor layer, an upper insulation ink layer, an upper touch sensitive layer, and a second substrate. 
         [0009]    The first substrate has a first circuit surface. 
         [0010]    The lower touch sensitive layer is mounted on the first circuit surface of the first substrate. 
         [0011]    The lower conductor layer is mounted on the first circuit surface of the first substrate and is electrically connected to the lower touch sensitive layer. 
         [0012]    The transparent insulation adhesive layer is mounted on the lower touch sensitive layer. 
         [0013]    The upper conductor layer is mounted on the transparent insulation adhesive layer. 
         [0014]    The upper insulation ink layer is mounted on the upper conductor layer, and has a plurality of upper through slots formed through the upper insulation ink layer, wherein each of the plurality of upper through slots is filled in with a upper conductive layer. 
         [0015]    The upper touch sensitive layer is mounted on the transparent insulation adhesive layer, partially covering the upper insulation ink layer, and is electrically connected to the upper conductor layer via the upper conductive layers in the corresponding upper through slots of the upper insulation ink layer. 
         [0016]    The second substrate is mounted on the upper touch sensitive layer and the upper insulation ink layer and has a second circuit surface in contact with the upper touch sensitive layer and the upper insulation ink layer. 
         [0017]    Given the above-mentioned structure of the capacitive touch panel, the lower touch sensitive layer and the upper touch sensitive layer respectively are in contact with the first substrate and the second substrate. Upon fabricating the capacitive touch panel, the lower touch sensitive layer and the upper touch sensitive layer can be respectively mounted on the first substrate and the second substrate with different fabrication processes. As using a substrate for fabrication of single-sided circuit layer is a mature technique, the resulting yield in production is relatively high, and the relatively high yield helps build large-size touch panel. 
         [0018]    Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is an exploded perspective view of a capacitive touch panel in accordance with the first embodiment of the present invention. 
           [0020]      FIG. 2  is a partial cross-sectional view of the capacitive touch panel in  FIG. 1 . 
           [0021]      FIG. 3A  is a top view of the lower touch sensitive layer of the capacitive touch panel in accordance with the first embodiment of the present invention. 
           [0022]      FIG. 3B  is a top view of the upper touch sensitive layer of the capacitive touch panel in accordance with the first embodiment of the present invention. 
           [0023]      FIG. 4  is an exploded perspective view of a capacitive touch panel in accordance with the second embodiment of the present invention. 
           [0024]      FIGS. 5A and 5B  are partial cross-sectional views of the capacitive touch panel in  FIG. 4 . 
           [0025]      FIG. 6  is a cross-sectional view of a conventional capacitive touch panel. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    With reference to  FIGS. 1 and 2 , a capacitive touch panel according to a first embodiment of the present invention includes a first transparent substrate  11 , a lower touch sensitive layer  12 , a lower insulation ink layer  13 , a lower conductor layer  14 , a lower insulation layer  15 , a lower conductive adhesive layer  16 , a flexible circuit board  20 , a transparent insulation adhesive layer  30 , an upper insulation layer  41 , an upper conductive adhesive layer  42 , an upper conductor layer  43 , an upper insulation ink layer  44 , an upper touch sensitive layer  45 , a second transparent substrate  46 , an upper protection layer  51  and a lower protection layer  52 . 
         [0027]    The first transparent substrate  11  has a first circuit surface  111 . The lower touch sensitive layer  12 , used for sensing touch positions of the user, is mounted on the first circuit surface  111  of the first transparent substrate  11 . 
         [0028]    The lower insulation ink layer  13  is mounted on an edge portion of the lower touch sensitive layer  12 . The lower insulation ink layer  13  has plurality of lower through slots  132  formed through the lower insulation ink layer  13  and covers the edge portion of the lower touch sensitive layer  12 . A lower conductive layer  133  is tilled in each lower through slot  132 . In the present embodiment, the lower insulation ink layer  13  is made of opaque insulating material, such as opaque black ink or opaque white ink, and is formed on the first circuit surface  111  of the first transparent substrate  11  such that, the edge portion of the lower touch sensitive layer  12  is partial covered using printing and baking technique. The materials of the lower insulation ink layer  13  can be chosen from thermal post curing insulating ink or UV-curing insulting ink. The lower conductive layer  133  adopts a conductive matter having a color identical to or different from that of the lower insulation ink layer  13 . The materials of the lower conductive layer  133  may be chosen from conductive silver paste or conductive carbon paste, and the color of the lower conductive layer  133  may be black, red, or white. The lower conductive layer  133  may be filled by one of the methods: printing or photolithography. 
         [0029]    The lower conductor layer  14  includes a plurality of signal lines  142  mounted on the lower insulation ink layer  13 , and one end of each signal line is electrically connected to the corresponding lower touch sensitive layer  12  through the lower conductive layer  133  for transmitting the touch sensing, signals to a controller (not shown). The lower conductor layer  14  may be made of silver glue or carbon glue by using lithography, printing, inkjet, or other methods known in the art. 
         [0030]    The lower insulation layer  15  is mounted on the lower conductor layer  14  to prevent the lower conductor layer  14  from being oxidized due to exposure to air. The lower insulation layer  15  has a lower indentation  151  to partially expose the lower conductor layer  14 . In the present embodiment, the lower insulation layer  15  is made of a transparent insulation material, such as post curing material or UV-curing material. 
         [0031]    The lower conductive adhesive layer  16  is mounted in the lower indentation  151  of the lower insulation layer  15  to cover the exposed portion of the lower conductor layer  14 . In the present embodiment, the lower conductive adhesive layer is formed of anisotropic conductive film (ACF) and/or anisotropic conductive paste (ACP). 
         [0032]    Upon fabricating the capacitive touch panel in accordance with the first embodiment of the present invention, a lower panel fabrication process completing the first transparent substrate  11 , the lower touch sensitive layer  12 . the lower insulation ink layer  13 , the lower conductor layer  14 , the lower insulation layer  15  and the lower conductive adhesive layer  16  can be conceived. 
         [0033]    The flexible circuit board  20  has a top surface  22  and a bottom surface  21 . The flexible circuit board  20  is mounted on the lower conductive adhesive layer  16  and the bottom surface  21  is attached to the lower conductive adhesive layer  16  and extends outwardly beyond the first transparent substrate  11 . The flexible circuit board  20  is electrically connected to the lower touch sensitive layer  12  through the lower conductive adhesive layer  16 , the low conductor layer  14  and the lower conductive layers  133  in the lower through slots  132  of the lower insulation ink layer  13 . 
         [0034]    The transparent insulation adhesive layer  30  has a thick portion  301  and a thin portion  302 . The thick portion  301  is mounted on the lower touch sensitive layer  12  and the thin portion  302  is mounted on the lower insulation layer  15 . The transparent insulation adhesive layer  30  is made of liquid optical clear adhesive (LOCA), such as UV glue with a viscosity in a range of about 500 cps to 5000 cps. 
         [0035]    The upper insulation layer  41  is mounted on the transparent insulation adhesive layer  30  and has an upper indentation  411  to expose the flexible circuit board  20 . In the present embodiment, the upper insulation layer  41  is made of a transparent insulation material, such as post curing material or UV-curing material. 
         [0036]    The upper conductive adhesive layer  42  is mounted in the upper indentation  411  of the upper insulation layer  41  to contact with the top surface  22  of the flexible circuit board  20 . In the present embodiment, the upper conductive adhesive layer  42  is formed of anisotropic conductive film (ACF) and/or anisotropic conductive paste (ACP). 
         [0037]    The upper conductor layer  43  is mounted on the upper conductive adhesive layer  42  and the upper insulation layer  41 . The upper conductor layer  43  may be made of silver glue and/or carbon glue. 
         [0038]    The upper insulation ink layer  44  is mounted on the upper conductor layer  43  and has a plurality of upper through slots  441  formed through the upper insulation ink layer  44 . An upper conductive layer  442  is filled in each upper through slot  441  to contact the upper conductor layer  43 . In the present embodiment, the upper conductive layer  442  adopts a conductive matter having a color identical to that of the upper insulation ink layer  44  to conceal the upper through slots  441 . In the present embodiment, the upper insulation ink layer  44  is made of opaque insulating material, such as opaque black ink or opaque white ink. The materials of the upper insulation ink layer  44  may be chosen from conductive silver paste or conductive carbon paste. 
         [0039]    The upper touch sensitive layer  45  for sensing touch positions of the user is mounted on the transparent insulation adhesive layer  30  and the edge portion of the upper touch sensitive layer  45  partially covers the upper insulation ink layer  44 . The upper touch sensitive layer  45  contacts with the upper conductive layer  442  in the upper through slot  441  a the upper insulation ink layer  44 . Accordingly, the upper touch sensitive layer  45  can be electrically connected to the flexible circuit board  20  through the upper conductive lavers  442  in the upper through slots  441  of the upper insulation ink layer  44 , the upper conductor layer  43  and the upper conductive adhesive layer  42 . 
         [0040]    The second transparent substrate  46  is mounted on the upper touch sensitive layer  45  and the upper insulation ink layer  44 , and has a second circuit surface  461  in contact with the upper touch sensitive layer  45  and the upper insulation ink layer  44 . When viewed from a side opposite to the second circuit surface  461  of the second transparent substrate  46 , the upper insulation ink layer  44  has a masking effect. Accordingly, the second transparent substrate  46  comprises a viewable region  462  and a neighboring region  464  next to the viewable region  462 ; the upper insulation ink layer  44  is mounted on the neighboring region  464 . 
         [0041]    Upon fabricating the capacitive touch panel in accordance with the first embodiment of the present invention, an upper panel fabrication process providing the upper insulation layer  41 , the upper conductive adhesive layer  42 , the upper conductor layer  43 , the upper insulation ink layer  44 , the upper touch sensitive layer  45  and the second transparent substrate  46  is achieved. 
         [0042]    In one example, the first transparent substrate  11  and the second transparent substrate  46  may be made of a same material or two different materials, such as glass, polymer, other transparent insulation materials, and combinations thereof. That materials may include, but are not limited to, polyethylene terephthalate (PET), polycarbonate (PC), polyether sulfone (PES), triacetyl cellulose (TAC), polymethylmethacrylate (PMMA), polyethylene (PE), polyimide (PI), composite material of polycarbonate (PC) and polymethylmethacrylate (PMMA), and the like. In the present embodiment, the first transparent substrate  11  and the second transparent substrate  46  are glass substrates. 
         [0043]    As shown in  FIGS. 3A and 3B , the lower touch sensitive layer  12  includes a plurality of first conductive assemblies  122 . These assemblies  122  are parallelly arranged in a first direction (such as X-axis). The upper touch sensitive layer  45  includes a plurality of second conductive assemblies  452  parallelly arranged in a second direction (such as Y-axis). In one example, the first conductive assemblies  122  and the second conductive assemblies  452  are arranged perpendicular to each other, forming a matrix structure. Each first conductive assembly  122  includes a plurality of first conductive cells  124 , equally spaced along the first direction. Each second conductive assembly  452  includes a plurality of second conductive cells  454 , equally spaced along the second direction. The adjacent first conductive cells  124  in the same first conductive assembly are interconnected by a first conductive line  126 . Moreover, the adjacent second conductive cells  454  in the same second conductive assembly are interconnected by a second conductive line  456 . In one embodiment, the first conductive cells  124  and the second conductive cells  454  are shaped as diamond contour. Other polygon contour, such as hexagon, octagon, rectangle, square, triangle etc., known to a person skilled in the art, can also be used as the shape of the first and second conductive cells  124 ,  454 . The first conductive cells  124  and the second conductive cells  454 , for example, are made of transparent conductive material, such as Indium Tim Oxide (ITO), Antimony Tin Oxide (ATO) or Titanium Oxide (TiO2). In one embodiment, the material of the first and second conductive lines  126  and  456  are same as the materials of first and second conductive cells  124 .  454 . In another embodiment, the material of the first and second conductive lines  126  and  456  are made of gold, silver, copper, aluminum or any other metal materials with good conductivity. 
         [0044]    With further reference to  FIG. 2 , the upper protection layer  51  is bonded to the top surface  22  of the flexible circuit board  20  and a side of the second transparent substrate  46  to protect the flexible circuit board  20  from directly contacting with a side of the second transparent substrate  46  when the flexible circuit board  20  is bent. Therefore, the flexible circuit board  20  is free from cuts and damages that may be caused by the bending of the second transparent substrate  46 . 
         [0045]    The lower protection layer  52  is bonded to a side portion of the capacitive touch panel between the bottom surface  21  of the flexible circuit board  20  and the first transparent substrate  11  to provide similar protection to the flexible circuit board  20  as the upper protection layer  51  does. 
         [0046]    With reference to  FIGS. 4 ,  5 A and  5 B, a capacitive touch panel according to a second embodiment of the present invention has a first transparent substrate  11 , a lower touch sensitive layer  12 , a lower conductor layer  14 , a lower insulation layer  15 , a lower conductive adhesive layer  16 , a lower flexible circuit board  24 , a transparent insulation adhesive layer  30 , an upper flexible circuit board  26 , an upper insulation layer  41 , an upper conductive adhesive layer  42 , an upper conductor layer  43 , an upper insulation ink layer  44 , an upper touch sensitive layer  45 , a second transparent substrate  46 , an upper protection layer  51  and a lower protection layer  52 . 
         [0047]    A method of fabricating the capacitive touch panel in accordance with the second embodiment of the present invention comprises steps of separately forming a lower panel and an upper panel, respectively mounting a lower flexible board and an upper flexible board on the lower panel and the upper panel, and bonding the lower panel and the upper panel by a transparent insulation adhesive layer. The lower panel fabrication process comprises providing a first transparent substrate  11 , forming a lower touch sensitive layer  12 , the lower conductor layer  14  the lower insulation layer  15  and the lower conductive adhesive layer  16  on the first transparent substrate  11 . 
         [0048]    The first transparent substrate  11  has a first circuit surface  111 . The lower touch sensitive layer  12 , for sensing touch positions of the user, is mounted on the first circuit surface  111  of the first transparent substrate  11 . 
         [0049]    The lower conductor layer  14 , including a plurality of signal lines  142 , covers the edge portion of the lower touch sensitive layer  12 . The lower conductor layer  14  is electrically connected to the lower touch sensitive layer  12  for transmitting the sensing signals generated by lower touch sensitive layer  12  to a controller. The lower conductor layer  14  may be made of silver glue or carbon glue by using lithography, printing, ink-jet, or other methods known in the art. 
         [0050]    The lower insulation layer  15  is mounted on a surface of the lower conductor layer  14  opposite to the lower touch sensitive layer  12  to prevent the lower conductor layer  14  from being oxidized due to exposure to air. The lower insulation layer  15  has a lower indentation  151  to partially expose the lower conductor layer  14 . In the present embodiment, the lower insulation layer  15  is made of a transparent insulation material, such as post curing material or UV-curing material. 
         [0051]    The lower conductive adhesive layer  16  is mounted in the lower indentation  151  of the lower insulation layer  15  to cover the exposed portion of the lower conductor layer  14 . In the present embodiment, the lower conductive adhesive layer is formed of anisotropic conductive film (ACF) and/or anisotropic conductive paste (ACP). 
         [0052]    Upon fabricating the capacitive touch panel in accordance with the second embodiment of the present invention, the upper panel fabrication process comprises providing a second transparent substrate  46 , forming an upper touch sensitive layer  45 , an upper insulation ink layer  44 , an upper conductor layer  43 , an upper insulation layer  41  and an upper conductive adhesive layer  42  on the second transparent substrate  46 . 
         [0053]    The second transparent substrate  46  has a second circuit surface  461 . The upper touch sensitive layer  45 , for sensing touch positions of the user, is mounted on the second circuit surface  461  of the second transparent substrate  46 . 
         [0054]    The upper insulation ink layer  44  is mounted on an edge portion of the upper touch sensitive layer  45  so that an uncovered portion of the upper touch sensitive layer  45  constitutes a viewable area  134 . The upper insulation ink layer  44  has a plurality of upper through slots  441  formed through the upper insulation ink layer  44  and covers the edge portion of the upper touch sensitive layer  45 . An upper conductive layer  112  is filled in each upper through slots  441 . In the present embodiment, the upper insulation ink layer  11  is made of opaque insulating material, such as opaque black ink or opaque white ink, and the upper insulation ink layer  44  is formed on the second circuit surface  461  of the second transparent substrate  46 , wherein the edge portion of the upper touch sensitive layer  45  is partial covered using printing and baking technique. The materials of the upper insulation ink layer  44  can be chosen from thermal post curing insulating ink or UV-curing insulting ink. The upper conductive layer  442  adopts a conductive matter having a color identical to that of the upper insulation ink layer  44  to avoid people easily seeing the upper through slots  441  from the surface opposite to the second circuit surface  461  of the second transparent substrate  46 . The materials of the upper conductive layer  442  may be chosen from conductive silver paste or conductive carbon paste, and the color of the upper conductive layer  442  may be black, red, or white. The upper conductive layer  442  may be filled by one of the methods: printing or photolithography. 
         [0055]    The upper conductor layer  43  includes a plurality of signal lines  432  mounted on a surface of the upper insulation ink layer  44  opposite to the upper touch sensitive layer  45 , and is electrically connected to the upper touch sensitive layer  45  through the upper conductive layer  442  for transmitting the sensing signals to a controller (not shown). The upper conductor layer  43  may be made of silver glue or carbon glue by using lithography, printing, ink-jet, or other methods known in the art. 
         [0056]    The upper insulation layer  41  is mounted on a surface of the upper conductor layer  43  opposite to the upper insulation ink layer  44  to prevent the upper conductor layer  43  from being oxidized due to exposure to air. The upper insulation layer  41  has an upper indentation  411  to partially expose the upper conductor layer  43 . In the present embodiment, the upper insulation layer  41  is made of a transparent insulation material, such as post curing material or UV-curing material. 
         [0057]    The upper conductive adhesive layer  42  is mounted in the upper indentation  411  of the upper insulation layer  41  to cover the exposed portion of the upper conductor layer  43 . In the present embodiment, the upper conductive adhesive layer  42  is formed of anisotropic conductive film (ACF) and/or anisotropic conductive paste (ACP). 
         [0058]    In the step of mounting a lower flexible board on the lower panel, the lower flexible circuit board  24  has a top surface  22  and a bottom surface  21 . The lower flexible circuit board  24  is mounted on the lower panel and the bottom surface  21  is attached to the lower conductive adhesive layer  16  and extends outwardly beyond the first transparent substrate  11 . The lower flexible circuit board  24  is electrically connected to the lower touch sensitive layer  12  through the lower conductive adhesive layer  16  and the low conductor layer  14 . 
         [0059]    In the step of mounting an upper flexible board on the upper panel, the upper flexible circuit board  26  has a top surface  27  and a bottom surface  28 . The upper flexible circuit board  26  is mounted on the upper panel and the top surface  27  is attached to the upper conductive adhesive layer  42  and extends outwardly beyond the second transparent substrate  46 . The upper flexible circuit board  26  is electrically connected to the upper touch sensitive layer  45  through the upper conductive adhesive layer  42 , the upper conductor layer  43  and the upper conductive layers  442  in the upper through slots  442  of the upper insulation ink layer  44 . 
         [0060]    In the step of bonding the lower panel and the upper panel, the upper panel and the lower panel are bonded by the transparent insulation adhesive layer  30 . The transparent insulation adhesive layer  30  is made of liquid optical clear adhesive (LOCA), such as UV glue with a viscosity in a range of about 500 cps to 5000 cps. 
         [0061]    With further reference to  FIG. 5B , the upper protection layer  53  is bonded to the top surface  27  of the upper flexible circuit board  26  and a side of the second transparent substrate  46  to protect the upper flexible circuit board  26  from directly contacting with a side of the second transparent substrate  46  when the upper flexible circuit board  26  is bent. Therefore, the upper flexible circuit board  26  is free from cuts and damages caused by bending of the second transparent substrate  46 . 
         [0062]    The lower protection layer  54  is bonded to a side portion of the capacitive touch panel between the bottom surface  28  of the upper flexible circuit board  26  and the first transparent substrate  11  to provide similar protection to the upper flexible circuit board  26  as the upper protection layer  53  does. 
         [0063]    In one example, the first transparent substrate  11  and the second transparent substrate  46  may be made of a same material of two different materials, such as glass, polymer, other transparent insulation materials, and combinations thereof. That materials may include, but are not limited to, polyethylene terephthalate (PET), polycarbonate (PC), polyether sulfone (PES), triacetyl cellulose (TAC), polymethylmethacrylate (PMMA), polyethylene (PE), polyimide (PI), composite material of polycarbonate (PC) and polymethylmethacrylate (PMMA), and the like. In the present embodiment, the second transparent substrate  46  is a glass substrate, and the first transparent substrate  11  is a polyethylene terephthalate film. In another embodiment, the second transparent substrate  46  is a polyethylene terephthalate film, and the first transparent substrate is another polymer film. 
         [0064]    The lower touch sensitive layer  12  and the upper touch sensing layer  45  in accordance with the second embodiment of the present invention are similar to those of the first embodiment depicted in  FIGS. 3A and 3B . 
         [0065]    Fabrication of the capacitive touch panel of the present invention can be separated into a lower panel fabrication process and an upper panel fabrication process. According to skill level of the current technology, the yield of using a substrate to fabricate single-sided circuit layer is high. Hence, the structure of the capacitive touch panel of the embodiment of present invention has a better yield than conventional capacitive touch panels in production. 
         [0066]    As the yield of the present invention in production is better, the capacitive touch panel of the present invention can be applied to the fabrication of large-size touch panel, thereby achieving a wider application range. 
         [0067]    Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.