Patent Publication Number: US-2011068686-A1

Title: Led lamp

Description:
TECHNICAL FIELD 
     The present invention relates to an LED lamp that uses a light emitting diode Thereinafter referred to as “LED”) as the light source and that can be used as a substitute for a fluorescent lamp, for example. 
     BACKGROUND ART 
     Fluorescent lamps used for a general-purpose fluorescent lighting fixture have drawbacks such as a short life, inclusion of harmful substances such as mercury or lead and attraction of insects. In view of this, LED lamps, which use LEDs as the light source, have been developed. Herein, the general-purpose fluorescent lighting fixture refers to a lighting fixture widely used mainly for general indoor lighting, and more specifically to a lighting fixture that uses, for example in Japan, the commercial power supply of 100 V or 200 V, and is compatible with a straight-tube fluorescent lamp according to JIS C7617 or a circular fluorescent lamp according to JIS C7618. 
       FIG. 5  is a sectional view showing an example of conventional LED lamp (see Patent Document 1 for example). The LED lamp X shown in the figure includes an elongated rectangular substrate  91 , a plurality of LEDs  92  mounted on the substrate  91 , a tube  93  accommodating the substrate  91 , and a terminal  94 , and is used as a substitute for a straight-tube fluorescent lamp. A wiring pattern, not shown, is formed on the surface of the substrate  91  for connection to the terminal  94 . The LEDs  92  are mounted on the wiring pattern. With this LED lamp X, fitting the terminal  94  into the inlet port of a socket of a general-purpose fluorescent lighting fixture allows the plurality of LEDs  92  to be turned on. 
     In recent years, lighting apparatuses that can illuminate only in a particular direction are demanded, in order to illuminate only a particular product shelf in a shop or illuminate only one side of a room with light. However, fluorescent lamps and the conventional LED lamp X emit light from the entirety. Thus, to illuminate only in a particular direction, part of the fluorescent lamp or the LED lamp X needs to be covered. With this arrangement, power consumption does not reduce, although only a little amount of the light emitted is used for illumination. 
     Patent Document 1: JP-U-6-54103 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     The present invention has been proposed under the circumstances described above. It is therefore an object of the present invention to provide an LED lamp that allows illumination in a particular direction with less electric power. 
     Means for Solving the Problems 
     To solve the problems described above, the present invention takes the following technical measures. 
     An LED lamp provided according to the present invention includes a plurality of LEDs, and a controller for switching the LEDs between a light-emission state and a non-light-emission state. The controller performs control to bring only part of the LEDs into the light-emission state. 
     In a preferred embodiment of the present invention, the LEDs are arranged in a plurality of rows extending parallel to each other. The controller performs switching of the LEDs between the light-emission state and the non-light-emission state individually with respect to each of the rows. 
     In a preferred embodiment of the present invention, the LED lamp further includes at least one receiver which is connected to the controller and which receives a signal from outside. The controller performs control to switch the LEDs included in at least one of the rows between the light-emission state and the non-light-emission state in accordance with a signal received by the receiver. 
     In a preferred embodiment of the present invention, the same number of receivers as the number of rows is provided. The controller makes the plurality of rows associated with different receivers, respectively, and when one of the receivers receives a signal from outside, the controller performs control to switch the LEDs included in the row associated with the receiver between the light-emission state and the non-light-emission state. 
     In a preferred embodiment of the present invention, the LED lamp further includes at least one light-shielding wall extending parallel to the rows and arranged between adjacent ones of the rows. 
     In a preferred embodiment of the present invention, at least part of the light-shielding wall overlaps the LEDs in a direction perpendicular to both the direction in which the rows extend and a direction in which the rows are arranged side by side. 
     Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view showing an example of LED lamp according to a first embodiment of the present invention; 
         FIG. 2  is a sectional view taken along lines II-II in  FIG. 1 ; 
         FIG. 3  is a plan view showing an example of LED lamp according to a second embodiment of the present invention; 
         FIG. 4  is a sectional view taken along lines IV-IV in FIG.  3 ; and 
         FIG. 5  is a sectional view showing an example of conventional LED lamp. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Preferred embodiments of the present invention are described below with reference to the accompanying drawings. 
       FIGS. 1 and 2  show an LED lamp according to a first embodiment of the present invention. The LED lamp A 1  of this embodiment is in the form of a straight tube elongated in x direction, and includes a substrate  10 , a plurality of LED modules  20 , receivers  31 ,  32 ,  33 , a controller  40 , bases  50  and a case, not shown, in the form of a straight tube. For instance, the LED lamp A 1  is used as attached to a general-purpose fluorescent lighting fixture as a substitute for a straight-tube fluorescent lamp. The LED lamp A 1  is configured to be fixed to e.g. a ceiling and operable by a remote control. 
     The substrate  10  is made of e.g. aluminum and has a cylindrical shape elongated in direction x. The surface of the substrate  10  on one side in direction z is covered with an insulating layer  11 . The substrate  10  has an elliptical cross section having a major axis extending in direction y. A wiring pattern, not shown, is formed on the surface of the insulating layer  11 . It is to be noted that the upper side in  FIG. 2  is the floor side, whereas the lower side in  FIG. 2  is the ceiling side. 
     Each of the LED modules  20  includes an LED and a resin package covering the LED. The LED module is electrically connected to the controller  40  via the wiring pattern, not shown, on the insulating layer  11 . The LED module  20  assumes either a light-emission state (ON) or anon-light-emission state (OFF) under the control by the controller  40 . The LED incorporated in the LED module  20  has e.g. a lamination structure made up of an n-type semiconductor layer, a p-type semiconductor layer and an active layer sandwiched between these layers. The LED chip can emit blue light when made of a GaN-based semiconductor. The resin package is made of e.g. a silicone resin that allows the light from the LED to pass therethrough. The resin package contains a fluorescent substance mixed therein that emits e.g. yellow light when excited by blue light. This arrangement allows the LED module  20  to emit while light. Alternatively, use may be made of a mixture of a fluorescent substance that emits red light when exited by blue light and a fluorescent substance that emits green light. 
     The LED modules  20  are arranged in rows extending in direction x, i.e., a first row  21 , a second row  22  and a third row  23 . The first row  21 , the second row  22  and the third row  23  are parallel to each other and arranged side by side in direction y. 
     The first row  21  is provided close to one end of the substrate  10  indirection y. The second row  22  is provided at the center of the substrate  10  in direction y. The third row  23  is provided close to the other end of the substrate  10  in direction y. As illustrated in  FIG. 2 , the LED modules  20  included in the first row  21 , those included in the second row  22  and those included in the third row  23  are different from each other in illumination range. 
     Each of the receivers  31 ,  32  and  33  comprises e.g. an infrared sensor module, and receives a signal from a remote control and transmits the received signal to the controller  40  via the wiring pattern, not shown, on the insulating layer  11 . The receiver  31  is arranged at the same position as the first row  21  in direction y. The receiver  32  is arranged at the same position as the second row  22  in direction y. The receiver  33  is arranged at the same position as the third row  23  indirection y. The light receiving range of the receivers  31 ,  32  and  33  are narrower than that of infrared sensor modules mounted on general electronic apparatuses. 
     The controller  40  comprises e.g. an IC module, and is mounted on the insulating film  11  to receive the signal transmitted from the receivers  31 ,  32 ,  33  and control the LED modules  20  in accordance with the signal. The controller  40  performs control to switch on or off the LED modules  20  included in the first row  21  upon receiving a signal from the receiver  31 , switch on or off the LED modules  20  included in the second row  22  upon receiving a signal from the receiver  32 , and switch on or off the LED modules  20  included in the third row  23  upon receiving a signal from the receiver  33 . 
     The bases  50  are cylindrical members made of e.g. aluminum and holding terminal pins  51 , and provided at ends of the substrate  10  in direction x. The terminal pins  51  are electrically connected to the wiring pattern, not shown, on the insulating film  11 . Fitting the terminal pins  50  of the two bases  50  into the inlet ports of sockets of a general-purpose fluorescent lighting fixture allows electric power to be supplied to the LED modules  20  and the controller  40 . 
     The operation and advantages of the LED lamp A 1  are described below. 
     Explanation is given below as to the case where the LED lamp A 1  is attached to the ceiling of a room and the LED lamp is not on in the initial state. For instance, when the remote control is operated from one side of the room in direction y, the signal emitted from the remote control is received only by the receiver  31 . At this time, the control means  40  performs control to turn on only the LED modules  20  included in the first row  21 . Thus, the LED lamp A 1  illuminates only the one side of the room in direction y with light. 
     When the remote control is operated from directly below the LED lamp A 1  for example, the signal emitted from the remote control is received only by the receiver  32 . At this time, the control means  40  performs control to turn on only the LED modules  20  included in the second row  22 . Thus, the LED lamp A 1  illuminates only the area directly below the LED lamp A 1  with light, without unnecessarily directing light toward the sides of the room. 
     When the remote control is operated from the other side of the room in direction y for example, the signal emitted from the remote control is received only by the receiver  33 . At this time, the control means  40  performs control to turn on only the LED modules  20  included in the third row  23 . Thus, the LED lamp A 1  illuminates only this side of the room in direction y with light. 
     As described above, the LED lamp A 1  illuminates only a particular area in which the person operating the remote control is present and does not turn on the LED modules  20  oriented toward the areas which do not need to be illuminated with light. Thus, power consumption is suppressed. 
     The signal from the remote control may be received by both the receivers  31  and  32  when the remote control is operated from a position relatively close to the LED lamp A 1  on one side of the room in direction y. In this case, both the LED modules included in the first row  21  and those included in the second row  22  are turned on. However, the LED lamp A 1  can still suppress power consumption, because the LED modules  20  included in the third row  23  are not turned on. Similarly, the signal from the remote control may be received by both the receivers  32  and  33  when the remote control is operated from a position relatively close to the LED lamp A 1  on the other side of the room in direction y. In this case again, the LED lamp A 1  can still suppress power consumption, because the LED modules  20  included in the first row  21  are not turned on. 
       FIGS. 3 and 4  illustrate an LED lamp according to a second embodiment of the present invention. In these figures, the elements that are identical or similar to those of the foregoing embodiment are designated by the same reference signs as those used for the foregoing embodiment. The LED lamp A 2  of this embodiment differs from that of the foregoing embodiment in that a plurality of light-shielding walls  12  are provided. 
     The light-shielding walls  12  are made of e.g. an opaque resin that can block light emitted from the LED modules  20  and provided on the substrate  10 . The light-shielding walls  12  extend in direction x and have a length substantially reaching the ends of the substrate  11 . In this embodiment, two light-shielding walls  12  are disposed between the first row  21  and the second row  22  and between the second row  22  and the third row  23 . The light-shielding walls  12  have a height approximately equal to that of the LED modules  20 . Preferably, in the height direction of the LED modules  20 , the light-shielding walls  12  have a size and position such that the light-shielding walls overlap the LED modules  20 . 
     According to this embodiment, when a selected one of the first row  21 , the second row  22  and the third row  23  is turned on, light from the LED modules  20  included in that row is prevented from traveling to the sides. Thus, the areas illuminated by the first row  21 , the second row  22  and the third row  23  are clearly differentiated. 
     The LED lamp according to the present invention is not limited to the foregoing embodiments. The specific structure of each part of the LED lamp according to the present invention may be varied in design in various ways. For instance, the LED modules  20  can be arranged in any number of rows as long as it is not less than two. Instead of using LED modules  20 , a plurality of LEDs may be directly mounted on the substrate  10 . 
     In the foregoing embodiments, the illumination direction changes depending on which of the three receivers  31 ,  32 ,  33  receives the signal. Unlike this, means to specify the illumination direction may be provided on the remote control side. In this case, a single receiver suffices, and the controller  40  performs control to turn on only the LED modules  20  included in the row specified by the remote control side. 
     Although the LED lamp A 1  of a straight-tube shape is described in the foregoing embodiment, the present invention is applicable to circular LED lamps.