Abstract:
An LED lamp includes a first light device and a second light device. The first light device includes a first cover and a first light strip received in the first cover. The second light device included a second cover and a second light strip received in the second cover. The second light device is movably mounted to the first light device. A light emitting area of the second light strip of the second light device is changeable according to movement of the second light device relative to the first light device whereby a total light emitting area of the LED lamp is adjustable.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to illumination, and more particularly, to an LED (light emitting diode) lamp having changeable light effect. 
       DESCRIPTION OF RELATED ART 
       [0002]    LEDs have many advantages, such as high luminosity, low operational voltage, low power consumption, compatibility with integrated circuits, easy driving, long term reliability, and environmental friendliness. Such advantages have promoted the wide use of LEDs as a light source. Nowadays, LED lamps are commonly applied in general lighting. However, the LED lamps in different lighting spaces have different lighting requirements. Generally, the LED lamp with small lighting field can meet the lighting requirement of a small space, and the LED lamp with large lighting field can meet the lighting requirement of a large space. However, light sources of the typical LED lamp is often fixed. Thus, the lamp is difficult to satisfy different lighting requirements for spaces of different sizes. 
         [0003]    What is needed, therefore, is an LED lamp having changeable light effect to overcome the above described shortcomings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the views. 
           [0005]      FIG. 1  is an isometric, assembled view of an LED lamp in accordance with a first embodiment of the present disclosure. 
           [0006]      FIG. 2  is similar to  FIG. 1 , but shows a second light device pulled out from a first light device of the LED lamp. 
           [0007]      FIG. 3  is an enlarged view of a circled part III of  FIG. 1 . 
           [0008]      FIG. 4  is an isometric, assembled view of an LED lamp in accordance with a second embodiment of the present disclosure. 
           [0009]      FIG. 5  is similar to  FIG. 4 , but shows a second light device pulled out from a first light device of the LED lamp. 
           [0010]      FIG. 6  is similar to  FIG. 5 , but shows the second light device separated from the first light device. 
           [0011]      FIG. 7  is similar to  FIG. 6 , but from another aspect. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Referring to  FIGS. 1-3 , an LED lamp  10  in accordance with a first embodiment of the present disclosure is shown.  FIG. 1  shows a retracted status of the LED lamp  10 ,  FIG. 2  shows an extended status of the LED lamp  10 . The LED lamp  10  includes a first light device  11  and a second light device  12  similar to the first light device  11 . The he first light device  11  and the second light device  12  are both strip-shaped. The second light device  12  is installed inside the first light device  11  (shown in  FIG. 1 ), and can be pulled out from the first light device  11  (shown in  FIG. 2 ). 
         [0013]    The first light device  11  includes a strip-shaped first cover  110  and a first light strip  111  received in the first cover  110 . The first cover  110  is hollow with two opposite open ends. Alternatively, a top end  115  thereof can also be closed. The first cover  110  includes a front wall  112 , a rear wall  114  and two side walls  116  interconnecting the front and rear walls  112 ,  114 . A light transmission window  1120  is defined in a middle of the front wall  112 . The first cover  110  further includes a dividing plate  118  formed in an inner chamber  1100  of the first cover  110 . The dividing plate  118  connects two middles of the two side walls  116 . The dividing plate  118  is parallel to the front wall  112 . The dividing plate  118  divides the inner chamber  1100  of the first cover  110  into a first receiving space  117  adjacent to the front wall  112  of the first cover  110  and a second receiving space  119  adjacent to the rear wall  114  of the first cover  110 . The first receiving space  117  is smaller than the second receiving space  119 . The first light strip  111  is received in the first receiving space  117 . The first light strip  111  includes a plurality of LEDs  113  exposed through the light transmission window  1120  of the front wall  112 . 
         [0014]    The second light device  12  includes a strip-shaped second cover  120  and a second light strip  121  received in the second cover  120 . The second cover  120  includes a front wall  122 , a rear wall  124  and two side walls  126  interconnecting the front and rear walls  122 ,  124 . The second cover  120  is smaller than the second receiving space  119 , and the second light device  12  is movably mounted in the second receiving space  119 . A light transmission window  1220  is defined in a middle of the front wall  122 . The second light strip  121  includes a plurality of LEDs  123  exposed through the light transmission window  1220  of the front wall  122 . An operating portion  128  is formed on a bottom of the second cover  120 . The operating portion  128  is semicircular and has a thickness equal to that of the first light device  11 . 
         [0015]    The second light device  12  is completely received in the second receiving space  119  except the operating portion  128  when the LED lamp  10  is in a retracted status. The operating portion  128  covers and abuts against the open bottom of the first cover  110 . At this status, only the LEDs  113  of the first light device  11  are working, so the LED lamp  10  produces less light and form a relatively small light field. Thus, the LED lamp  10  can be used in a small space which does not need too much light. When the LED lamp  10  is required to be applied in a larger space, the second light device  12  is pulled out from the first light device  11  by pulling the operating portion  128  downwardly. A length of the second light device  12  exposed outside of the first light device  11  can be controlled by operating the operating portion  128 , so that a number of the exposed LEDs  123  of the second light device  12  can be changeable. Only the exposed LEDs  1220  are working by photosensitive control or other control methods for energy saving. Thus, the LED lamp  10  has a changeable light effect to meet different lighting requirements. The operation to change the lighting effect of the LED lamp  10  is simple just by pulling the second light device  12  out from the first light device  11  or pushing the second light device  12  in the first light device  11 . 
         [0016]    Referring to  FIGS. 4-5 , an LED lamp  20  in accordance with a second embodiment of the present disclosure is shown.  FIG. 4  shows a retracted status of the LED lamp  20 , and  FIG. 5  shows an extended status of the LED lamp  20 . The LED lamp  20  includes a first light device  21  and a second light device  22  similar to the first light device  21 . The LED lamp  20  in this embodiment has a shape similar to that of the LED lamp  10  in the first embodiment. The first light device  21  includes a strip-shaped first cover  210  and a first light strip  211  received in the first cover  210 . The first cover  210  includes a front wall  212 , a rear wall  214  and two side walls  216  interconnecting the front and rear walls  212 ,  214 . A semicircular operating portion  218  is formed on a bottom of the first cover  210 . The operating portion  218  has a thickness equal to that of the first cover  210 . A light transmission window  2120  is defined in a middle of the front wall  212 . The first light strip  211  includes a plurality of LEDs  213  exposed through the light transmission window  2120  of the front wall  212 . 
         [0017]    The second light device  22  includes a second cover  220  and a second light strip  221  received in the second cover  220 . The second cover  220  includes two front walls  222 , a rear wall  224  and two side walls  226  interconnecting the two front walls  222  and the rear wall  224 . The two front walls  222  are connected to the two side walls  226 , respectively. A light transmission hole  2220  is defined between the two front walls  222 . The second light strip  221  includes a plurality of LEDs  223  exposed through the light transmission hole  2220  of the front wall  222 . An operating portion  228  is formed on a bottom of the second cover  220 . The operating portion  228  is similar to the operating portion  218  of the first light device  21  and has a thickness equal to a thickness of the second cover  220 . The second light device  22  is mounted to the rear wall  214  of the first light device  21 . 
         [0018]    Referring to  FIGS. 6-7 , two sliding slots  2221  are defined respectively in the two front walls  222  of the second lighting device  22 . The two sliding slots  2221  are extended from top ends of the front walls  222  to the operating portion  228  of the second light device  22 . The two sliding slots  2221  are located near the two side walls  226 , respectively. Two sliding bars  2141  are formed on the rear wall  214  of the first light device  21  corresponding to the two sliding slots  2221  of the second light device  22 . The two sliding bars  2141  are extended from a top end of the rear wall  214  downwardly to a position corresponding to the operating portion  218 . 
         [0019]    The two sliding bars  2141  of the first light device  21  are received in the two sliding slots  2221  of the second light device  22 , whereby the second light device  22  is movably mounted to the first light device  21 . The second light device  22  is completely covered by the first light device  21  when the LED lamp  20  is used in a small space. At this status, only the LEDs  213  of the first light device  21  are working. When the LED lamp  20  is used in a larger space, the second light device  22  is exposed by pulling the operating portion  228  downwardly. Only the exposed LEDs  223  are working by photosensitive control or other control methods for energy saving. Thus, the LED lamp  20  has a changeable light effect to meet different lighting requirements. The operation to change the lighting of the LED lamp  20  is simple just by pulling the second light device  22  out from the first light device  11  or pushing the second light device  22  towards the first light device  11 . 
         [0020]    It is understood, the lengths of the first light device  11 ,  21  and the second light device  12 ,  22  can be different. The LED lamp  10 ,  20  can include more than two light devices. Besides sliding, the first light device  11 ,  21  can also be moved relative to the second light device  12 ,  22  through other methods such as rotation. 
         [0021]    It is believed that the present disclosure and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the present disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments.