Abstract:
A display frame is disclosed having a base frame, a LED light source mounted inside the base frame, a light guide board mounted inside the base frame and peripherally facing the light source and having a net of dots on the back surface for dispersing light rays from the light source to provide sufficient back illumination to the photo or picture supported on the light guide board. The base frame has a frame body formed of frame bars, and clamping plates hinged to the frame bars and forced by spring members between the frame bars and the clamping plates to hold down a photo or picture on the light guide board for display.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a display frame for displaying a photo or picture and more particularly, to a display frame having a light source to provide back illumination.  
         [0003]     2. Description of the Related Art  
         [0004]     Picture frames are commonly used in our daily life to display photos or pictures. A conventional picture frame comprises a rectangular base frame, a stiff backing, and a transparent face glass. The photo or picture to be displayed is set in between the stiff backing and the transparent face glass within the rectangular base frame. The mounting arrangement of the base frame, the stiff backing and the transparent face glass is complicated. It is inconvenient to install and replace the photo or picture. Further, conventional picture frames do not provide a light source. Illumination relies upon an external light source. Therefore, external light rays may affect the display quality of the photo or picture.  
         [0005]     Further, advertising lamp boxes are commonly seen in our daily life. An advertising lamp box has a box and a lamp tube mounted inside the box to provide illumination. The use of a lamp tube in an advertising lamp box as light source means has the drawbacks of big dimension, high energy consumption, and high maintenance cost.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention has been accomplished under the circumstances in view.  
         [0007]     It is one object of the present invention to provide a display frame having a light source to provide back illumination, which is practical for use as a picture frame that eliminates the drawback of conventional picture frames to be difficult to change the display photo or picture and the drawback of conventional picture frames to have no back illumination.  
         [0008]     It is another object of the present invention to provide a display frame having a light source to provide back illumination, which is practical for use as an advertising lamp box that eliminates the drawbacks of conventional advertising lamp boxes to have a big size, high power consumption and high maintenance cost.  
         [0009]     According to one aspect of the present invention, the display frame comprises a base frame, a LED light source mounted inside the base frame, a light guide board mounted inside the base frame and peripherally facing the light source and having a net of dots on the back surface for dispersing light rays from the light source to provide sufficient back illumination to the photo or picture supported on the light guide board.  
         [0010]     According to another aspect of the present invention, a light shade film is bonded to the back surface of the light guide board, preventing passing of light rays through the back side of the light guide board.  
         [0011]     According to still another aspect of the present invention, the base frame has a frame body formed of frame bars, and clamping plates hinged to the frame bars and forced by spring members between the frame bars and the clamping plates to hold down a photo or picture on the light guide board for display.  
         [0012]     According to still another aspect of the present invention, a transparent lens is set in front of the light guide board, keeping the photo or picture sandwiched between the light guide board and the transparent lens.  
         [0013]     Other objects, 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  
       [0014]      FIG. 1  is a perspective view showing the outer appearance of a display frame according to the present invention.  
         [0015]      FIG. 2  is an exploded view of the display frame according to the present invention.  
         [0016]      FIG. 3  is a front view of the display frame according to the present invention.  
         [0017]      FIG. 4  is a cross sectional view taken along line  4 - 4  of  FIG. 3 .  
         [0018]      FIG. 5  is a cross sectional view of the present invention, showing the clamping plates opened.  
         [0019]      FIG. 6  is a cross sectional view of the present invention, showing the display frame used in an advertising lamp box and a picture secured to the light guide board by the clamping plates and the springs.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]     Referring to FIGS.  1 ˜ 4 , a display frame  10  in accordance with the present invention is shown comprising a base frame  20 . The base frame  20  is comprised of a frame body  21  and a plurality of clamping plates  25 . According to the present preferred embodiment, the frame body  21  is formed of four frame bars  22  and four angle plates  23 , configuring a rectangular shape. The rectangular frame body  21  is simply an example for understanding of the present invention but not a limitation. Alternatively, the frame body  21  can be made having a square, oval, circular, or polygonal design.  
         [0021]     The aforesaid clamping plates  25  are arranged at the front side of the frame body  21 . As shown in  FIGS. 2 and 4 , the clamping plates  25  are respectively connected to the frame bars  22  by a respective hinge  28 . Therefore, the clamping plates  25  can be turned relative to the frame body  21  between a close position as shown in  FIGS. 1, 3  and  4 , and an open position as shown in  FIGS. 2 and 5 . Each clamping plate  25  has an outer side connected to the associating hinge  28  and an inner side terminating in a retaining portion  26 . By means of the respective retaining portion  26 , each clamping plate  25  holds down a photo or picture  50  (see  FIG. 6 ). Further, two spring members  27  are connected between each clamping plate  25  and the associating frame bar  22 , imparting a pressure to the associating clamping plate  25  to hold down a photo or picture  50  on a light guide board  40 . According to the present preferred embodiment, the spring members  27  are flat springs.  
         [0022]     Another important part of the present invention is the arrangement of a light source  30  within the base frame  20 . According to the present preferred embodiment as shown in  FIGS. 2 and 4 , the light source  30  is comprised of two narrow elongated circuit boards  31 , a plurality of LEDs (Light Emitting Diodes)  32  respectively soldered to the circuit boards  31 , and two channel bars  35  adapted to accommodate the circuit boards  31  respectively. The channel bars  35  protect the circuit boards  31  and the LEDs  32 , and concentrate light rays from the LEDs  32  onto the light guide board  40 . The invention uses LEDs to emit light for the advantages of long service life and low power consumption. Further, the use of LEDs allows thin size design of the display frame  10 . Further, the frame bars  22  each have a base portion  24 . The channel bars  35  are affixed to the base portions  24  of the two frame bars  22  at two opposite lateral sides (long sides) of the base frame  20 .  
         [0023]     The aforesaid light guide board  40  is mounted inside the base frame  20 . As shown in  FIGS. 2 and 4 , the light guide board  40  can be moulded from PMMA (Polymethylmetharylate) or PC (Polycarbonate) in a shape fitting the display side of the base frame  20 . According to the present preferred embodiment, the light guide board  40  is a rectangular plate member having the four sides respectively affixed to the base portions  24  of the frame bars  22  and the two opposite long sides respectively engaged into the two opposite channel bars  35  that are respectively affixed to the base portions  24  of the two frame bars  22  at two opposite lateral sides (long sides) of the base frame  20 . Further, the light guide board  40  has a net of dots  41  longitudinally transversely aligned on the back surface thereof, and a light shade film  42  bonded to the back surface. The net of dots  41  is printed on the back surface of the light guide board  40  in a clean room. Further, the net of dots  41  is adapted to have light rays produced by the LEDs  32  be evenly dispersed through the whole area of the light guide board  40 . The light shade film  42  presents passing of light through the back surface of the light guide board  40 , thereby gathering light rays. The light guide board  40 , the light shade film  42  and the channel bars  35  can be fixedly positioned by means of the use of an adhesive or other proper measures. Further, an opaque film, such as aluminium foil or tin foil may be wrapped about the connection area between the light guide board  40  and the channel bars  35  to prevent dispersion of light rays through the gap in between the light guide board  40  and the channel bars  35 .  
         [0024]     The position of the light source  30  is determined subject to the size of the light guide board  40 . For example, for a small light guide board  40 , the light source  30  can be mounted in one lateral side within the base frame  20 ; for a medium size light guide board  40 , the light source  30  can be installed in the two opposite lateral sides within the base frame  20 ; for a big light guide board  40 , the light source  30  can be installed in the four sides within the base frame  20 . According to the present preferred embodiment, the light source  30  is installed in the left and right sides within the base frame  20 .  
         [0025]     The display frame  10  of the present invention can be used as a photo frame, picture frame, advertising lamp box, or the like.  
         [0026]     When in use, the four clamping plates  25  are opened from the base frame  20  (see  FIG. 5 ), and then the selected photo or picture  50  is placed on the light guide board  40 , and then the clamping plates  25  are closed to hold down the photo or picture  50  on the light guide board  40  (see  FIG. 6 ), and then the light source  30  is connected to power source and turned on. At this time, the LEDs  32  emit light toward the light guide board  40 , and the net of dots  41  disperse light rays from the LEDs  32  evenly to illuminate the back side of the photo or picture  50 , providing a high display quality.  
         [0027]     In order to protect the photo or picture  50 , a transparent lens (not shown) is used and pressed on the light guide board  40 , keeping the photo or picture  50  sandwiched between the light guide board  40  and the transparent lens. Further, a light source controller may be used to control the flashing mode of the LEDs  32 , producing a visual effect.  
         [0028]     Comparing to conventional designs, the invention provides an active and prominent display effect. The invention uses the clamping plates  25  and the springs  27  at the four sides of the base frame  20  to hold down a photo or picture  50  for display. This arrangement facilitates mounting/dismounting of the photo or picture  50 . Further, the LED light source  30  and the light guide board  40  are provided inside the base frame  20  to provide back illumination, improving the display quality of the photo or picture  50 . Therefore, the display of the photo or picture  50  is free from the interference of external light. Further, the use of the LEDs  32  enables the display frame  10  to be made relatively thinner.  
         [0029]     Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention.