Abstract:
A light guide plate (LGP) and LGP-based flat fluorescent panel (FFP) provides consistent light source for FFP to output consistent and high luminance light source for upgrading general light emitting efficacy to facilitate subsequent use of the light source by expanding incident angle for creating a scattering belt to destroy the total reflection of the light source passing through the scattering belt thus to avail better deflection to reduce light and shade stripes created in subsequent reflection.

Description:
BACKGROUND OF THE INVENTION 
   (a) Technical Field of the Invention 
   The present invention is related to a light guide plate (LGP) and LGP-based flat fluorescent panel (FFP), and more particularly, to one that upgrades the general light emitting efficacy of the FFP by eliminating the light interference of light and shade stripes. 
   (b) Description of the Prior Art 
   Whereas the liquid crystal penal adapted in an LCD is not capable of emitting light, a flat fluorescent panel (FFP) is required to provide a light source for achieving the purpose of display. 
   As illustrated in  FIG. 1 , an FFP  1  of the prior art is essentially comprised of a light guide plate  11 , one or multiple diffuser  12  and condenser  13  are disposed in sequence on the light outlet surface  111  of the light guide plate  11 ; multiple light guide points  113  in great number are provided on the reflective surface of the light guide plate  11 ; a reflector  14  is adhered to the outer side; one light inlet surface  114  as a minimum is provided on the light guide plate  11 ; a lamp source  15  is adapted externally to the light inlet surface  114 ; and the lamp source is substantially covered up by a lamp reflector  16 . 
   In operation of the prior art as illustrated in  FIG. 2 , the light source from the lamp source  15  forthwith emits into the light inlet surface  114  of the light guide plate  11  due to the reflection by the lamp reflector  16 . Upon entering into the interior of the light guide plate  11  by the light source, if the angle formed by the route of the light source and the light outlet  111  of the light guide plate  11  is smaller than the critical angle, the light source leaves the light guide plate  11  and varied through the diffuser  12  to achieve the purpose of condensing through the condenser  13  and finally the light source inputs toward a liquid crystal panel  2  to provide sufficient light source when the liquid crystal panel displays. Should the angle indicated by the light source in the light guide plate  11  and the light outlet surface  111  of the light guide plate  11  be greater than the critical angle, the light source indicates reflection to a reflective surface  112  to further take advantage of those light guide points  113  and the reflector  14  for reflecting its light source in seeking for the chance to output the light once again. 
   However, the FFP  1  of the prior art is vulnerable to the following flaws. As illustrated in  FIG. 3 , since the light inlet surface of the light guide plate  11  relates to a mirror without having been fogged and roughened; the incident angle is comparatively smaller when the light source from the lamp source  15  enters into the light guide plate  11 . The light source arrives in the vicinity of the edge of the light outlet surface abutted to the light inlet surface  114  is prevented from leaving the light outlet surface  111  due to that the incident angle of the light source is greater than the critical angle resulting in reflection. The light guide source after the primary reflection undergoes the second reflection through those light guide points  113  and the reflector  112 . Whereas the incident angle is equal to the exit angle, when the light source of the second reflection reaches once again on the light outlet surface  111 , the angle indicated by the light source of the second reflection and the light outlet surface  111  is greater than the critical angle to frustrate the deflection. The repeated pattern creates the light interference to indicate light and shade stripes on the light guide plate  11 , resulting in inconsistent luminance of the entire FFP and reduced total luminance to become problems pending urgent solutions by the trade. 
   To improve, an FFP  3  as illustrated in  FIG. 4  contains a light guide plate  31 ; one or multiple diffuser  32  and condenser  33  in sequence on the light outlet surface  311  of the light guide plate  31 ; multiple light guide points  313  in great number on the reflective surface  312  of the light guide plate  31  and then covered up with a reflector  34 . Meanwhile, one light inlet surface  314  as a minimum is provided on the light guide plate  31 . The light inlet surface  315  is not mirrored, instead, is molded, sandblasted, etched, or tooled into fogged or roughened status. A lamp source  35  is provided to the light inlet surface  314  and is substantially covered up by a lamp reflector  36 . 
   As the light inlet surface  314  of the light guide plate  31  is in fogged or roughened status, the angle of the light source form the lamp source  35  is expanded upon entering into the light inlet surface  314  of the light guide plate  31 . Accordingly, the angle of the primary light source in the vicinity of the edge of the light outlet surface  311  abutted to the light inlet surface is smaller than the critical angle for the light outlet surface  311  to successfully become a bright area. 
   However, as illustrated in  FIG. 5 , the angle of a primary light source L 1  farther from the light inlet surface  414  is gradually becoming equal to and larger than the critical angle to frustrate the light outlet and to turn into a dark area due to reflection even though the delivery of the light by the light source in the vicinity of the edge of the light inlet surface  314  abutted to the light outlet surface  311  presents no problem. The light source of that reflection is a secondary light source L 2  and it though may be further reflected by those light guide points  313  and the reflector  34 , the second reflection by the secondary light source L 2  becomes the tertiary light source L 3  due to that the incident angle of the light source is equal to the exit angle; and the attempted emission through the light outlet surface  311  by the tertiary light source L 3  is frustrated since the light source is prone to be greater than the critical angle, thus is reflected again, and so on. As a result, the light interference exists to create light and shade stripes, the luminance of the FFP  3  is still not consistent, and the total luminance is insufficient with the problems found with the prior art not solved. 
   While the liquid crystal display is heading for larger and for full color display, more demands are put on the luminous of the FFP to point the way for future efforts by the trade. More recently, a high luminance FFP has been developed as illustrated in  FIG. 6 . Wherein, a light guide plate  41  is provided to an FFP  4 , and the light guide plate  41  is provided with a light outlet surface  411  and a reflective surface  412 . Multiple channels  413  in V shape capable of collecting the light and one light inlet surface  414  as a minimum are provided to the reflective surface. A reflector  42  is adhered to the reflective surface  412 . A lamp source  43  is provided externally to the light inlet surface  414 , and is substantially covered up by a lamp reflector  44 . The light outlet surface is adhered with a condenser  45 . As illustrated in  FIG. 7 , both of the light outlet surface  411  and the light inlet surface  414  of the light guide plate  41  in the FFP  4  are fogged or roughened to provide soft and consistent light outlet by the subsequent light outlet from the light guide plate  41  by omitting the installation of the conventional diffuser to save the material cost and assembly cost of the diffuser for condensing the light directly through the condenser  45  to concentrate the visual angle of luminance and significantly upgrade the luminance of the FFP  4 . 
   However, the omission of the diffuser and the even further concentration of the visual angle of luminance lead to the even more conspicuous of the light and shade stripes on the light outlet surface, presenting a problem pending urgent solution for the FFP  4 . Referring to  FIG. 8 , light beams from the light inlet surface partially advance in parallel for transmission into the light guide plate  41 , and the remaining light beams are generally transmitted to the light outlet surface ( 411 ) upwardly and to the reflective surface ( 412 ) downwardly. For those light beams transmitted upwardly, their light emission angle has been already expanded by the fogged or roughened light inlet surface  414 , the light angle of the primary light source L 1  falling in the vicinity of the edge of the light outlet surface  411  abutted to the light inlet surface  414  is smaller than the critical angle and the light is smoothly deflected for the area of the primary light source L 1  to become a bright area. As the location of the primary light source L 1  falling on the light outlet surface  411  moves farther from the light inlet surface  414 , the angle of the primary light source L 1  and the critical angle of the light outlet surface  411  become larger until the deflection is prevented due to that the light angle of the primary light source L 1  is greater than the critical angle. Accordingly, a dark area B is crated on the light outlet surface  411  and the light is reflected to the reflective surface  412  to become a secondary light source L 2 . Where as the incident angle is always equal to the reflective angle, the secondary light source is reflected once again to the light outlet surface  411  to become a tertiary light source L 3 . When the tertiary light source L 3  is reflected once again to the light outlet surface by following the rule that the incident angle is always equal to the reflective angle, the light angle is greater than the critical angle to become a dark area, and so on. Consequently, the light and shade stripes are created to bring in the subsequent transmission of light the poor deviation to the highly luminance demanding FFP  4 . 
   SUMMARY OF THE INVENTION 
   The primary purpose of the present invention is to provide a light guide plate and a light guide-based flat fluorescent panel that is adapted with a scattering belt on a light outlet surface of the light guide plate to destroy the total reflection of the light source within the scattering belt for giving the light source better chances of deflection and reducing the light and shade stripes due to repeated light reflection. 
   Another purpose of the present invention is to provide a light guide plate and a light guide-based flat fluorescent panel that delivers a consistent light source for the use by the FFP to upgrade its general light efficacy by having a scattering belt on a light outlet surface of the light guide plate to destroy the total reflection of the light source within the scattering belt for giving the light source better chances of deflection and reducing the light and shade stripes due to subsequent light reflection. 
   The foregoing object and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
   Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded view of an FFP of the prior art. 
       FIG. 2  is a schematic view of the FFP of the prior art. 
       FIG. 3  is a schematic view of a light guide plate of the prior art. 
       FIG. 4  is an exploded view of another FFP of the prior art. 
       FIG. 5  is a schematic view of another light guide plate of the prior art. 
       FIG. 6  is a schematic view of another FFP of the prior art. 
       FIG. 7  is a schematic view showing that another light guide plate is in use. 
       FIG. 8  is another schematic view showing that another light guide plate is in use. 
       FIG. 9  is a schematic view of an FFP of the present invention. 
       FIG. 10  is a schematic view showing a light guide plate of the present invention. 
       FIG. 11  is a schematic view of a preferred embodiment of the present invention. 
       FIG. 12  is a schematic view of another preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following descriptions are of exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
   Referring to  FIG. 9 , a flat fluorescent panel  5  of the present invention is provided with a light guide plate  50 ; a reflector  51  adhered to the outer side of a reflective surface  501  of the light guide plate  50 , a plurality of light guide points  502  in great number are disposed on the reflective surface  501 , and one or multiple diffuser  52  and condenser  53  are arranged in sequence externally to a light outlet surface of the light guide plate  50 ; a lamp source  54  is provided externally to a light inlet surface  504  of the light guide plate  50  and is substantially covered by a lamp reflector  55 . The light inlet surface  504  is molded, etched, sandblasted or tooled to indicate fogged or roughened status for the light source from the lamp source  54  to expand its light emission angle upon entering into the light inlet surface  504 . A scattering region  505  is provided on the light outlet surface  503  and is also molded, etched, sandblasted or tooled to indicate fogged or  7242  roughened status. Meanwhile, as illustrated in  FIG. 10 , the scattering region  505  is present in an optimal coverage on the light outlet surface  503  and created in a length along the light inlet surface  504  and in a width starting from a point where the light emitted upwardly from the light inlet surface  504  to fall on a primary light source L 1  reaches a point that is greater than the critical point, until the light emitted downward from the light inlet surface  504  to fall on the reflective surface  501  at where the primary light source L 1  reaches a point that is greater than the critical point for a secondary light source L 2  to reflect once again to reach within the range of the location of the light outlet surface  503 . 
   Now referring to  FIG. 11 , once the light source outputted form the lamp source  54  enters into the light guide plate  50  through the light inlet surface  504 , the light emission angle of the light source is expanded since the light inlet surface  504  has been fogged or roughened. Accordingly, a scattering region is provided in the range between one part of the light beams from the primary light source L 1  in the vicinity of the edge of the light outlet surface  503  abutted to the light inlet surface  504  leaves away from the light inlet surface  504  to such extent that prevents deflection due to the light emission angle is beyond the critical point and the other part of the light beams from the primary light source that emits downward becomes a reflected secondary light source L 2  due to that the emission angle is greater than the critical point. The scattering region  505  destroys the total reflection of the light beams from the light source falling on the scattering region  505  since the surface of the scattering region  505  is fogged or roughened, thus to correct the reflection into deflection. Therefore the deflected light is successfully delivered to eliminate the problem of developing light interference of light and shade stripes on the light guide plate  50  for the FFP  5  to upgrade its application efficacy by providing consistent light. 
   In another preferred embodiment of the present invention as illustrated in  FIG. 12 , another FFP  6  that is applicable to larger size and high luminance light emission efficacy is provided with a light guide plate  60 , a reflector  61  adhered to the outer side of a reflective surface  601  of the light guide plate  60 , and multiple V-shaped channels  602  in great number provided with light collection function are provided on the reflective surface  601 ; a condenser  62  is provided externally to the light outlet surface; and a lamp source  63  is disposed externally to a light inlet surface  604  of the light guide plate  60  and is substantially covered up by a lamp reflector  64 . Wherein, both of the light outlet surface  663  and the light inlet surface  604  are molded, etched, sandblasted or tooled to a consistently fogged or roughened status. A scattering region  605  is provided on the light outlet surface  603  and the surface of the scattering region  605  is similarly processed as that of the light outlet surface  603  and the light inlet surface  604  with the exception that only more roughened than other position on the light outlet surface  603 . The scattering region  605  is present on an optimal coverage on the light outlet surface  603  and is created in a length along the light inlet surface  60  and in a width starting from a point where the light emitted upwardly from the light inlet surface  604  to fall on a primary light source L 1  reaches a point that is greater than the critical point, until a secondary light source L 2  reflects once again to reach within the range of the location of the light outlet surface  603 . 
   Whereas the Light outlet surface  603  of the FFP  6  has been fogged or roughened, the diffuser to soften up the light source is omitted to facilitate concentrating the visual angle of luminance and upgrade the light outlet luminance. However, to avoid the problem of exaggerating the light and shade stripes on the light outlet surface  603  of the light guide plate  60  resulted from the concentrated visual angle, the roughened extent for the scattering region  605  on the light outlet surface  603  must be greater than that for the other area than the scattering region  605  so that the light source falling on the scattering region  605  is more capable of destroying the total reflection so to make it more favorable for light outlet by deflection, thus to better meet the high luminance light outlet efficacy demanded by the FFP  6  to complete the performance of high luminance from the FFP  6 . 
   It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. 
   While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.