Abstract:
There is provided a lighting device for illuminating objects inside an enclosure including a housing, an array of light emitting diodes enclosed by the housing consisting of at least two groups of diodes, one group emitting substantially white light and one group emitting colored light, a DC to DC converter feeding the light-emitting diodes and enclosed by the housing, and a light intensity controller for operating each of the groups of diodes at variable light intensities.

Description:
[0001]    This application is a Continuation-in-Part Application of U.S. patent application Ser. No. 10/879,084, filed Jun. 30, 2004. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a lighting device and more particularly, to a lighting device suitable for military use, especially in vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    There often exists a need, both for military and civilian purposes, to utilize a lighting device which can provide regular bright illumination as commonly required, as well as to selectively provide lighting of a different nature, e.g., white and colored lights of limited illumination or of controllable light intensity. 
       DISCLOSURE OF THE INVENTION 
       [0004]    According to the present invention, there is therefore provided a lighting device for illuminating objects inside an enclosure comprising a housing, an array of light emitting diodes enclosed by said housing consisting of at least two groups of diodes, at least one group emitting substantially white light and at least one group emitting colored light, a DC to DC converter feeding said light-emitting diodes and enclosed by said housing, and at least one light intensity control means for operating each of said groups of diodes at variable light intensities. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The invention is herein described, by way of example only, with reference to the accompanying drawings. 
           [0006]    With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 
           [0007]    In the drawings: 
           [0008]      FIG. 1  is a top view of the lighting device according to the present invention; 
           [0009]      FIG. 2  is an isometric view of the base plate of the lighting device of  FIG. 1 ; 
           [0010]      FIG. 3  is an isometric view of a further embodiment of the invention; 
           [0011]      FIG. 4  is a rear view of the enclosure of the lighting device of  FIG. 3 , and 
           [0012]      FIG. 5  is a block diagram for energizing and controlling the lighting device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    A first embodiment of a lighting device  2  according to the present invention is illustrated in  FIGS. 1 and 2 . Seen is a housing  4  advantageously a two-part housing composed of an enclosure  6  and a base plate  8  of a curved configuration, hermetically sealed to render it waterproof. The housing parts  6  and  8  are interconnectable in any per-se known manner such as by press fitting and/or by screws. The enclosure  6  has an opening  10 , protected by a transparent cover, preferably made of polycarbonate, accommodating an array of LEDs  12 , details of which will be described hereinafter. Further seen is a selector embodied by a toggle switch  16  and a member  18  for adjusting a light intensity controller, e.g., a potentiometer or a logic circuit, for dimming or brightening the LEDs  12 . Also provided is an inlet electrical port  20 . The base plate  8  is preferably made with flanges  22 , facilitating anchoring of the housing  4  to a wall or ceiling. 
         [0014]    The PCB-mounted array of LEDs  12 , advantageously consists of 32 white LEDs  24  interlaced with 16 blue (wavelength ˜470 nm), green or red LEDs  26  providing an active LED area of approximately 30×68 mm. The 32 white LEDs  24  are energized from a 160 mA, 14Vdc source, while the 16 blue LEDs  26  are energized from 100 mA, 14Vdc source. The desired luminous intensity of each white LED is typically ˜400 mcd at 120 degrees. 
         [0015]    The white LEDs provide light for general activity, e.g., map reading, orientation etc. during daytime and nocturnal non-combat activities, whereas the blue LEDs provide light for nocturnal combat activity. The advantage of blue light during combat activity is that blue light is less detectable by night vision equipment of the enemy in the event that some of it leaks out through openings in the vehicle, e.g., periscope. Alternatively, red (wavelength ˜630 nm) LEDs may be used instead of the blue ones during nocturnal activity. The advantage of red light is that (although detectable by night vision equipment) it does not impair the high sensitivity of the dark-adapted human eye. 
         [0016]    Referring to  FIGS. 3 and 4 , there is illustrated a further embodiment of the lighting device  2  according to the present invention. Seen is the enclosure  6 , the base plate  8  to which the enclosure  6  is attachable, the opening  10 , protected by a transparent cover, the array of white and colored LEDs  12 , an emergency button  28 , as well as other parts of the device numbered by the same numbers allocated to the various parts shown in  FIGS. 1 and 2 . Inside the enclosure  6  ( FIG. 4 ) there are further located a powerpack  30  held in position by a support plate  32 , a PCB  34  and a heat sink  36  for dispersing the heat generated by the LEDs  12 . 
         [0017]    The device  2  is externally powered from a DC source, e.g., 18-36 Vdc of a vehicle&#39;s battery  38  ( FIG. 5 ), through input plugs and/or sockets  20  and optionally includes an internal rechargeable powerpack  30 , which is held in position by a support plate  32 . The powerpack  30  may be formed by two sub-units, one operable for short periods of time using a super-capacitor, while the other sub-unit for a longer period of time, utilizing rechargeable batteries. The internal powerpack  30  enables the lighting device to provide light even in a damaged vehicle thus, for example, assisting the crew to escape and/or be rescued from the damaged vehicle. Furthermore, the internal powerpack  30  facilitates utilization of the device as an independent portable flashlight. 
         [0018]    Turning now to  FIG. 5 , there is illustrated a block diagram of the lighting device according to the present invention, illustrating the structure and operation of the lighting device. Under normal conditions the vehicle&#39;s battery  38  feeds the driver and power electronics  40 ,  42 , the LEDs  12  via a DC to DC converter  44  and the powerpack charger  46 . When the vehicle&#39;s battery is disconnected due to some reason, the internal powerpack  30 , which may be of a lower voltage than the vehicle&#39;s voltage, e.g., 3.6 Vdc, is automatically enabled for a predetermined short period of emergency operation, e.g., 30 seconds. An additional period (e.g., 15 minutes) of emergency operation is selectable by briefly pressing the emergency pushbutton  28 . This can be repeated several times with total emergency capacity of at least 60 minutes. The isolation switch  48  prevents unnecessary discharge of the powerpack  30 . The controller  50  controls the entire electronic circuit (the circuit may also include a low noise built-in EMI RFI filter) during normal and emergency operations according to the program fused into its memory, as well as the data that flows into its inputs from the circuit components, the vehicle&#39;s battery and the environment. Furthermore, the controller  50  also monitors the voltage of the vehicle&#39;s battery  38  and renders the LEDs  12  blinking when this voltage falls under a predetermined value. This feature is particularly important during a silent ambush, when the vehicle&#39;s engine is not working and the vehicle&#39;s restart is dependable on the vehicle&#39;s batteries being sufficiently charged. 
         [0019]    The light intensity control  52  serves for controlling the variable light intensity of at least one group of the two groups of light emitting diodes, for the purpose of dimming or brightening same. It may be activated manually by the manipulatable member  18  or by any per-se known manner such as a selector, a keypad, a proximity sensor, etc. It can also be activated by a software program either directly or via a communication line. 
         [0020]    It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrated embodiments and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.