Abstract:
A lamp is disclosed, which comprises a tubular, an elongate and two end-caps, wherein the tubular body comprises two ends of the tubular body; the elongate light source board is inside the tubular body along a longitudinal direction thereof, and the elongate light source board comprises at least one light source arranged thereon and two ends of the elongate light source board; two end-caps are adapted to seal the two ends of the tubular body respectively, and at least one end-cap is slidingly connected to one of the two ends of the tubular body and fixedly connected to one of the two ends of the elongate light source board. The lamp of the present disclosure can be adapted to temperature changes, and can avoid an overall length variation, and/or a bending deformation in appearance.

Description:
TECHNOLOGY FIELD 
       [0001]    The present disclosure relates to lighting technology, and more particularly to a lamp which is adapted to temperature changes, and can avoid an overall length variation, and/or a bending deformation in appearance. 
       BACKGROUND 
       [0002]    In recent years, more and more fluorescent lamps in lighting industry have been replaced by LED lamps using light-emitting diodes (LED) as light sources. The LED lamps are more efficient, energy-saving, and environmental-friendly. And the LED lamps have longer service life. 
         [0003]    Linear LED lamps are also known as LED tubes. Currently, LED tubes in the market usually use tubular plastic light covers, for example, the plastic light covers may be made from polycarbonate (PC) material. The tubular light cover has two ends fixedly connected to two end-caps, and an LED light source board and a driving unit are installed inside the tubular light cover. As the LED tubes are used in different occasions and regions, even in the same area, the temperature changes will happen at different times, the tubular plastic light cover may have length variation due to thermal expansion and contraction in the case of temperature changes. For an LED tube, which has not been installed, if the LED tube becomes longer or shorter, it cannot be installed. For an LED tube, which has been installed in a lamp holder, if the LED tube becomes longer or shorter, the tubular plastic light cover will be bent and deformed in appearance, even the tubular plastic light cover will be disconnected with the end-cap, so that the LED tube will be damaged and there will be a danger of electric leakage. 
       BRIEF DESCRIPTION 
       [0004]    To solve the above-mentioned problems, the present invention discloses a lamp which is adapted to temperature changes. The overall length variation of the lamp, and/or the bending deformation in appearance can be avoided. 
         [0005]    The present invention discloses a lamp comprising: a tubular body having two ends of the tubular body; an elongate light source board inside the tubular body along a longitudinal direction thereof, the elongate light source board having at least one light source arranged thereon and two ends of the elongate light source board; and two end-caps are adapted to seal the two ends of the tubular body respectively, at least one end-cap being slidingly connected to one of the two ends of the tubular body and fixedly connected to one of the two ends of the elongate light source board. 
         [0006]    In some embodiments, the at least one end-cap comprises a cavity for receiving the one of the two ends of the tubular body and being adapted to the length variation of the tubular body due to thermal expansion and contraction of the tubular body. 
         [0007]    In some embodiments, the at least one end-cap comprises a through hole, and the one of the two ends of the elongate light source board comprises a screw hole adapted to match with the through hole. The at least one end-cap is fixedly connected to the one of the two ends of the elongate light source board through a screw. 
         [0008]    In some embodiments, the length of the elongate light source board is longer than the length of the tubular body, and at least one end of the elongate light source board extends outside of the tubular body. 
         [0009]    In some embodiments, the cross-section of the tubular body has a first width and a second width. The first width is the largest width parallel to the cross-section of the elongate light source board, and the second width is the largest width perpendicular to the cross-section of the elongate light source board. The first width is smaller than the second width. 
         [0010]    In some embodiments, the cross-section of the tubular body is oval-shaped, rectangular or water-droplet-shaped. 
         [0011]    In some embodiments, the tubular body further comprises at least one pair of fixing grooves formed on both sides of the inner surface of the tubular body for securing the elongate light source board. 
         [0012]    In some embodiments, the tubular body comprises a light transmitting part and a light reflective part separated by a plane of the elongate light source board. The light transmitting part is toward the light-emitting direction of the at least one light source, and the light reflective part is back to the light-emitting direction of the at least one light source. 
         [0013]    Preferably, the light transmitting part is bigger than the light reflective part. 
         [0014]    In some embodiments, the tubular body is formed integrally. 
         [0015]    The lamp of the present disclosure is structurally designed, so that at least one of the two end-caps is slidingly connected to one of the two ends of the tubular body and fixedly connected to one of the two ends of the elongate light source board, therefore, two ends of the tubular body are not completely fixed, and the overall length of the lamp is determined by the length of the elongate light source board, not by the length of the tubular body. When the environmental temperature changes cause the length variation due to the thermal expansion and contraction of the tubular body, the tubular body is relatively sliding with the end-cap by using the cavity of the end-cap. Furthermore, the thermal expansion and contraction of the elongate light source board is small, so the overall length variation of the lamp, and/or the bending deformation in appearance can be avoided. 
     
    
     
       DRAWINGS 
         [0016]      FIG. 1  is a top view of a first embodiment of the present invention; 
           [0017]      FIG. 2  is a section view of  FIG. 1  in the direction of AA; 
           [0018]      FIG. 3  is a cross-sectional view of the first embodiment of the present invention; 
           [0019]      FIG. 4  is a section view of a second embodiment of the present invention; 
           [0020]      FIG. 5  is a cross-sectional view of the second embodiment of the present invention; 
           [0021]      FIG. 6  is a cross-sectional view of a third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The present invention is described in detail as following with reference to the accompanying drawings and embodiments. 
         [0023]      FIG. 1  to  FIG. 3  illustrate a lamp  100  of the first embodiment of the present invention, which comprises a tubular body  110 , an elongate light source board  120  and two end-caps  130 ,  140 . The tubular body  110  comprises a plastic light cover and two ends  111 ,  113 . As shown in  FIG. 3 , a cross-section of the tubular body  110  is circular. On an inner surface of the tubular body  110 , a fixing groove  115  and a reinforcing rib  116  are set along a longitudinal direction of the tubular body  110  for securing the elongate light source board  120  and increasing the bending strength of the tubular body  110 . The tubular body  110 , the fixing groove  115  and the reinforcing rib  116  on the inner surface thereof are formed integrally. For example, they are formed integrally by injection molding method. 
         [0024]    As shown in  FIG. 2 , the elongate light source board  120  is a strip inside the tubular body  110  along a longitudinal direction thereof and comprises two ends  121 ,  123  and two screw holes  122 ,  124  located at the two ends  121 ,  123  respectively, and a plurality of LED light sources  125  located on the same side of the elongate light source board  120 . The length of the elongate light source board  120  is longer than the length of the tubular body  110 , therefore, two ends  121 ,  123  extend outside of the tubular body  110 . The two end-caps  130 ,  140  are adapted to seal the two ends  111 ,  113  of the tubular body  110 . The end-cap  130  includes a cylinder cavity  131 , a through hole  132  perpendicular to the longitudinal direction of the cylinder cavity  131 , and two pins  135 , 136  extending outwardly. Wherein the cylinder cavity  131  is used for receiving the end  111  of the tubular body  110 . The cylinder cavity  131  and the end  111  contact closely and may relatively slide along the longitudinal direction of the cylinder cavity  131  or the longitudinal direction of the tubular body  110 . The through hole  132  in the end-cap  130  is matched with the screw hole  122  on the elongate light source board, and the end-cap  130  is fixedly connection to the end  121  of the elongate light source board  120  through a screw  150 . The end-cap  140  has a symmetrical structure with the end-cap  130 , and the end-cap  140  also includes a cylinder cavity  141 , a through hole  142  and two pins  145 ,  146  extending outwardly. The end-cap  140  is slidingly connected to the end  113  of the tubular body  110 , and is fixedly connected to the end  123  of the elongate light source board  120 . 
         [0025]    Furthermore, the lamp  100  of the first embodiment of the present invention is a dual-colored lamp. As shown in  FIG. 3 , the tubular body  110  includes a light transmitting part  117  and a light reflective part  119 . The boundary of the light transmitting part  117  and the light reflective part  119  is on the plane of the elongate light source board  120 . The light transmitting part  117  towards the luminous side of the LED light source  125  and allows light emitting. The light reflective part  119  is on the back-side of LED light source  125  and the light could not be emitted. Therefore, it will effectively prevent the formation of the dark areas and make the light of the lamp  100  more beautiful. In the present embodiment, the area of the light transmitting part  117  is about three to four times than the area of the light reflective part  119 , however, the persons skilled in the art may divide the areas of the light transmitting part  117  and the light reflective part  119  reasonably according to actual needs. 
         [0026]    Structurally, two end-caps  130 ,  140  of the lamp  100  of the first embodiment of the present invention are fixedly connected to two ends of the elongate light source board  120  respectively. Therefore, the overall length of the lamp  100  is determined by the length of the elongate light source board  120 , not by the length of the tubular body  110 . The tubular body  110 , i.e. plastic light cover, has two ends  111 ,  113  received in the cylinder cavities  131 ,  141  of the two end-caps  130 ,  140 . The design standards of the length of the tubular body  110  and the length of the cylinder cavities  131 ,  141  are: in a certain temperature change range, the two ends of the tubular body  110  are always sealed by the two end-caps  130 , 140 . At the lowest temperature, either end of the tubular body  110  does not drop off the cylinder cavities  131 ,  141 . At the highest temperature, the cylinder cavities  131 ,  141  still can accommodate the tubular body  110  which may become longer due to the thermal expansion. 
         [0027]    The thermal expansion and contraction of the tubular body  110  generated by the temperature changes is obvious, because the tubular body  110  is made from plastic material. The structure design of the lamp  100  of the first embodiment of the present invention has resolved the length variation problem caused by the thermal expansion and contraction of the tubular body  110 . Although the elongate light source board and the end-cap also have the problem of the thermal expansion and contraction, the size variation is quite small determined by their material used. Since the effect on overall size of the lamp  100  is quite small, it will not be discussed here. 
         [0028]      FIG. 4  illustrates a section view of a lamp  200  of the second embodiment of the present invention. The structure of the lamp  200  is similar to the structure of the lamp  100  of the first embodiment. The mainly difference is that the tubular body  210  of the lamp  200  has an oval-shaped cross-section, as shown in  FIG. 5 . On the inner surface of the tubular body  210 , a fixing groove  215  is set along a longitudinal direction of the tubular body  210  for securing an elongate light source board  220 . The tubular body  210  and the fixing groove  215  on the inner surface thereof are formed integrally, for example, they are formed integrally by injection molding method. Compared with the tubular body  110  which has a circular cross-section, the advantages of oval-shaped cross-section include: firstly, it can save materials: for the lamps of the same size, about  11 % materials can be saved producing the tubular body  210  with the oval-shaped cross-section comparing with producing the tubular body  110  with the circular cross- section. Furthermore, the tubular body  210  with oval-shaped cross-section can install a more narrow light source board, so the materials of the light source board can be saved. Secondly, the bending resistance is better. Proved by mechanical strength simulation, the bending resistance of the tubular body with the oval-shaped cross-section is better than the tubular body with the circular cross-section when the long axis of the oval-shaped cross-section in a vertical direction. Thirdly, the tubular body with the oval-shaped cross-section can improve the light angle of the light source to achieve a wider light distribution. 
         [0029]      FIG. 6  illustrates a cross-sectional view of a lamp  300  of the third embodiment of the present invention. The structure of the lamp  300  is similar to the structure of the lamp  100  of the first embodiment. The mainly difference is that the tubular body  310  of the lamp  300  has a water-droplet-shaped cross-section, as shown in  FIG. 6 . About the water-droplet-shaped cross-section of the tubular body  310 , specifically, separated by a plane of the elongate light source board  320 , the upper part of the cross-section of the tubular body  310  is triangular, and the lower part of the cross-section is circular. On an inner surface of the tubular body  310 , a fixing groove  315  is set along a longitudinal direction of the tubular body  310  for securing the elongate light source board  320 . The tubular body  310  and the fixing groove  315  on the inner surface thereof are formed integrally, for example, they are formed integrally by injection molding method. Compared with the tubular body  110  with a circular cross-section, the tubular body  310  with a water-droplet-shaped cross-section is similar to the tubular body  210  with an oval-shaped cross-section and has the advantages of saving materials, better bending resistance and bigger light angle. 
         [0030]    While the invention has been illustrated, and described in typical embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions can be made without departing in any way from the spirit of the present invention. As such, further modifications and equivalents of the invention herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be within the spirit and scope of the invention as defined by the following claims.