Patent Abstract:
The present invention provides a lighting device having a battery housing to hold a battery, a light housing having a light source and a lens assembly into which said light source will emit light when activated, said battery and said light source being in circuit with a switch to open and close said circuit, said light housing being moveable relative to said battery housing to motivate said switch to open and/or close said circuit.

Full Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to outdoor lighting devices, particularly such as those used in gardens or to mark trails.  
       BACKGROUND OF THE INVENTION  
       [0002]     There has been a long felt need for a garden light having a relatively long run time, which is also battery operated, and is relatively inexpensive to manufacture.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention provides a lighting device having a battery housing to hold a battery, a light housing having a light source and a lens assembly into which said light source will emit light when activated, said battery and said light source being in circuit with a switch to open and close said circuit, said light housing being moveable relative to said battery housing to motivate said switch to open and/or close said circuit.  
         [0004]     The light housing is preferably a part of or is connected to an intermediate body portion. The intermediate body portion is slidably connected to said battery housing. The light housing or the intermediate body portion is preferably biased away from said battery housing with the bias being produced by a compression spring.  
         [0005]     The battery housing can include an elongated switch engagement member. The intermediate body portion preferably houses a printed circuit board on which is mounted the light source and switch. The lens assembly can include a reflector around the light source. Preferably a second reflector is located away from said light source. Preferably the lens assembly includes a cylindrical lens. The cylindrical lens can have its internal surfaces frosted to assist the diffusion of light over the surface of the lens. The outside surface of the cylindrical lens can include striations or lenticules therearound.  
         [0006]     The light housing and battery housing can be elongated. The battery housing can include a screw-on cover to access the internal portions of the battery housing. The base preferably includes a recess to receive a mounting spike. The base can also be adapted to be received by an attachable foot.  
         [0007]     Movement of the light housing relative to the battery housing is preferably limited. The limitation of movement is preferably by means of parts of the intermediate body portion engaging formations on the battery housing.  
         [0008]     The intermediate body portion can include at least two shoulders to engage the battery housing at two spaced locations preferably the shoulders one annular or port annular. Preferably the light source is an LED or low wattage lamp and preferably the battery is of a D size. A cap can be positioned over the lens assembly to assist in maintaining structural integrity and water resistance.  
         [0009]     In a further preferred embodiment the circuit of the lighting device further includes a light sensitive element adapted to detect an ambient light level, and wherein said light source is illuminated in response to said detected ambient light level.  
         [0010]     Preferably the said light source is deactivated if the detected ambient light level is above a predetermined ambient light threshold. Preferably the light source is illuminated if the detected ambient light level is below a predetermined ambient light threshold.  
         [0011]     Preferably the light sensitive element is selected from the following light sensitive elements:  
         [0012]     a light dependent resistor, a photodiode or a phototransistor.  
         [0013]     Preferably the brightness of said light source is varied in response to said detected ambient light level. In use when the detected ambient light level falls within a predetermined range of ambient light levels the brightness of said light source can be either increased or decreased when said ambient light level increases. In use when the detected ambient light level falls within a predetermined range of ambient light levels the brightness of said light source can be either increased or decreased when said ambient light level decreases. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
         [0015]      FIG. 1  is a perspective view of an outdoor light with a spike base;  
         [0016]      FIG. 2  is a cross-section through the outdoor light of  FIG. 1 ;  
         [0017]      FIG. 3  is a front elevation of an outdoor light similar to that of  FIG. 1  with an attached foot instead of a spike base;  
         [0018]      FIG. 4  is a cross-section through the light of  FIG. 3 ;  
         [0019]      FIG. 5  is a perspective view of an outdoor light similar to that of  FIG. 1 ;  
         [0020]      5   FIG. 6  shows a schematic representation of a circuit suitable for use in the outdoor light of FIGS.  1  to  5 ; and  
         [0021]      FIG. 7  shows a schematic representation of a circuit suitable for use in an outdoor light which is adapted to turn itself off during the day. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0022]     As illustrated in  FIG. 1 , an outdoor light  2  which is cylindrical in construction, has a battery housing  4 , a battery housing cover  6 , an intermediate body portion  8 , which is slidably connected to the battery housing  4  and a light housing  10  which is secured to the intermediate body portion  8 , each of which will be described in more detail later. The intermediate body portion  8  is illustrated as being separate from and joined to the light housing  10 . If desired the intermediate body portion  8  and the light housing  10  can be integrally formed.  
         [0023]     At the top of the light housing  10  is a cap  12 . The battery housing cover  6  has depending therefrom a mounting spike  14  which terminates in a pointed head  16 . The mounting spike  14  is indicated in  FIG. 1  as discontinuous so as to indicate that one or more such spikes can be joined together to form the mounting spike.  
         [0024]     As illustrated in  FIG. 2  in cross-section, the battery housing  4  has at its lowest end, a male thread  42 , which receives a female thread  62  of the battery housing cover  6 . The battery housing  4  at its upper end includes a spring contact  44  for engaging the negative terminal  22  of a D size dry cell or battery  20 . A wire (not illustrated) connects the spring contact  44  to a printed circuit board  81 .  
         [0025]     The battery housing  4  includes at its upper end an elongated switch contact column  46  which terminates in a flat contacting surface  48  to engage a switch  82  mounted on the underside of printed circuit board  81 .  
         [0026]     Beneath the surface  48  and around the column  46  is a flange  41  to provide a bearing surface against which compression spring  24  can act.  
         [0027]     The cylindrical outer surface of the battery housing  4  includes annular surfaces  43 ,  45 ,  47  and  49  which provide bearing surfaces against which parts of the intermediate body portion  8  can bear and slide. As can be seen from  FIG. 2 , the bearing surfaces  45  and  49  are recessed relative to the surfaces  43  and  47 . The intermediate body portion  8  has corresponding radially inwardly directed flanges  83  and  85 . The change of section from the surfaces  45  to  47 , and  45  to  43  respectively produces an upper shoulder  50  and a lower shoulder  52  between which the flange  85  can move. The upper shoulder  50  between surfaces  45  and  47 , limits the intermediate body portion  8  in the upward direction, whilst the lower shoulder  52  (being the shoulder formed between the surfaces  43  and  45 ) limits the downward movement of the intermediate body portion  8  relative to the battery housing  4 .  
         [0028]     The internal cylindrical surface of the intermediate body portion  8 , together with flanges  83  and  85  engage and slide relative to the annular surfaces  43 ,  45 ,  47  and  49  making the slidable interconnection between the battery housing  4  and intermediate body  8  structurally sound for the purposes to which the outdoor light  2  will be put, whilst achieving slidable relative movement between the two components.  
         [0029]     The battery housing cover  6  includes a positive battery contact  64  which makes contact with a metal contact (not illustrated) contained within the battery housing  4 . The opposite end of this contact, within the battery housing  4  is connected by a wire (not illustrated) to the printed circuit board  81 .  
         [0030]     The screwed connection of the battery housing cover  6  to the battery housing  4  helps to prevent ingress of water from this connection.  
         [0031]     The battery housing cover  6  includes in its lower portions a central, cylindrical wall  66  which receives in the internal portions thereof, the outside diameter of the mounting spike  14 . The mounting spike  14  receives in its proximal end a pointed head  16 .  
         [0032]     The upper portion of the intermediate body  8  includes radially inwardly directed shoulders  84  which support the printed circuit board  81 . The printed circuit board  81  is held against the shoulder  84  by means of a shaped LED support  86  which helps to prevent the LED from laterally moving relative to the printed circuit board  81 . The LED  30  extends from the printed circuit board  81  so that the diode of the LED extends into the light housing  10 .  
         [0033]     The light housing  10  at its base  102  is held by means of a shoulder  104  in a groove  106  on the intermediate body  8 . An internal wall  108  surrounds the LED support  86  and clamps the LED support  86  and printed circuit board  81  into position as illustrated in  FIG. 2 . A locator or index means (not illustrated) is provided either on the printed circuit board  81  or LED support  86  so that when assembled, the switch  82  is coaxial with the column  46  on battery housing  4 .  
         [0034]     The upper portion of the light housing  10  is a lens assembly  110 . The lens assembly  110  is made from a transparent or translucent material with the internal wall  112  having a frosted finish to help diffuse light over the cylindrical surface of the lens assembly  110 .  
         [0035]     The external surface of the lens assembly  110  is made up of striations or lenticules  114  which are generally annular in nature and surround the external surface of the lens assembly  110 . The upper end of the lens assembly  110  includes a reflector surface  116  whilst the internal face  118  of the surface  108  is also a reflector surface. Thus any light emitted by the LED  30  will reflect off the surfaces  118  and  116  which helps to reflect light through the cylindrical wall of the lens assembly  110 .  
         [0036]     The cap  12  has a cylindrical recess  122  to receive the upper end of the lens assembly  110 . The lens assembly  110  and the intermediate body  8  are made from two halves which are sonically welded together. However, for structural integrity, the cap  12  is positioned by means of a compressed fit and/or sonically welded to the lens assembly  110  thus helping to keep the lens assembly  110  as an integral unit.  
         [0037]     In use, the outdoor light  2  is assembled by first pushing the mounting spike  14  with pointed head  16  into the ground. If desired, additional mounted spikes  14  and pointed heads  16  can be added end on end to produce a conjoined mounting spike of a desired height. Once the mounting spike  14  is in the ground, an assembly of the battery cover  6 , battery housing  4 , intermediate body portion  8 , lens assembly  10  and cap  12  is positioned onto the mounting spike  14  by sliding the cylindrical recess formed by cylindrical wall  66  over the upper end of mounting spike  14 .  
         [0038]     Once fully assembled, the outdoor light  2  can be switched on by pushing downwardly in the direction of arrow  200  against the cap  12  which will force the light housing  10  and intermediate body portion  8  to move relative to the battery housing  4  against the bias of spring  24 , thereby pushing the switch  82  against the surface  48  atop of the column  46 . This downward action will close the circuit if it is open thus illuminating the LED  30  and the lens assembly  110 . To switch off the outdoor light  2 , the cap  12  is pushed in the direction of arrow  200  to open the circuit.  
         [0039]     In another embodiment, the outdoor light  2  can include circuitry to switch off the LED  30  as the level of ambient light increases. Such a light sensitive embodiment will include at least one light detector, such as a light dependent resistor (LDR), photodiode, phototransistor, or other optically sensitive circuit component. The light detector(s) is mounted on the light  2 , such that it is able to detect the level of ambient light in the vicinity of the outdoor light  2 .  
         [0040]     In order to prevent the light emitted from the outdoor light  2  activating the light detector and turning the LED  30  off, the light detector should be mounted such that the light omitted from the LED  30  does not impinge upon it, for example by mounting the light detector facing upward on the top face of cap  12 , or on the lower end of the intermediate body portion  8 . Other measures to prevent the LED  30  activating the light detector may also be employed, such as selecting the LED  30  or light detector such that the omission spectrum of the LED  30  falls outside the response spectrum of the light detector. The sensitivity of the light detector, or associated circuitry, can also be selected such that the light emitted by the LED  30  of the outdoor light  2 , or an adjacent outdoor light of the same type, does not activate the power down mode.  
         [0041]     It is envisaged that by selecting appropriate circuitry the light sensitive power down mode can operate to turn the LED  30  off when the ambient light reaches a particular intensity. Advantageously, once the user has placed their outdoor light  2  in the ground and activated it by pushing down on the cap  12 , the user then does not need to turn the light off. This will automatically occur when the sun comes up or a brighter light source is used to illuminate an area. In either case, the use of the outdoor light in bright conditions would be unnecessary and lead to an unwanted drain on the light&#39;s batteries.  
         [0042]     Alternatively the light detector could be configured to switch the LED  30  on and off as appropriate as the ambient light changes. Thus once the user has placed their outdoor light  2  in the ground and activated it by pushing down on the cap  12  the LED will come on and turn off as required. This embodiment is particularly advantageous when setting up the outdoor light during the day, for use during the night. Thus the outdoor light can be placed in a desired position and activated, but will not turn on the LED until the sun sets, thus allowing early activation of the light, without unnecessary use of the battery&#39;s power while the sun is up when the outdoor light will have limited effect.  
         [0043]     In a further embodiment, the circuit and light detector can be configured to control the intensity of the LED&#39;s  30  output to compensate for changes in ambient light. This embodiment is similar to that described above. However, rather than simply using the light detector to turn the LED on or off, the circuit is configured such that the light emitted by LED  30  ramps down as the ambient light increases, or ramps up as the ambient light decreases. A combination of the two modes of operation can also be used. In such an embodiment the LED is not illuminated until the ambient light falls below a predetermined threshold, but once the LED is illuminated, its intensity is varied to compensate for changes in ambient light. If the ambient light increases over a predetermined level the LED is deactivated.  
         [0044]     Alternatively, the variation in illumination intensity of the LED may be varied so that over a predetermined range of ambient light levels the brightness of the light source increases with increasing ambient light levels, so as to render the brightness of the LED as perceived by a viewer, to be constant. This mode of operation may be particularly advantageous if the outdoor light is being used to mark a path, walkway or the like, and it is necessary to ensure the pathway can be easily discerned in conditions of varying light.  
         [0045]     Illustrated in  FIGS. 3 and 4  is the outdoor light  2  similar to that of  FIG. 2  except that the mounting spike  14  has been removed and an annular foot  202  added. The annular foot  202  has a central aperture  203  and a cylindrical recess  204  to receive the outside diameter of the cylindrical skirt of the battery housing cover  6 . The annular foot  202  provides added stability allowing the outdoor light  2  when combined with a foot  202  to be placed onto a path, deck, patio or the like. The central aperture  203  allows access to the cylindrical wall  66 , when the foot  202  is in position. Thus, a user can still position the combined outdoor light  2  and foot  202  onto a mounting spike.  
         [0046]      FIGS. 6 and 7  show suitable circuits for use in an outdoor light as described above. As will be appreciated by those skilled in the art the circuit  600  is powered by a DC power source  620  (which corresponds to dry cell  20  of  FIG. 2 ) and includes a switch  610  (which corresponds to switch  82  of  FIG. 2 ), and a white LED  630  (corresponding to LED  30  of  FIG. 2 ). The circuit additionally includes transformer  640  which is used to step up the voltage from 1.5 volts, as output from the power source  620 , to 3.6 volts, which is required to illuminate the white LED  630 . As described above a user of the outdoor light can then close the switch  620  of the circuit by pushing down on the cap ( 12  in  FIG. 2 ) of the light. This completes the circuit and illuminates the LED  630 .  
         [0047]      FIG. 7  shows a circuit  700  for use in a light sensitive embodiment of the present invention. The circuit  700  differs from the circuit  600  of  FIG. 6  in that, in addition to a power source  620 , a switch  610 , a transformer  640 , and white LED  630  the circuit  700  includes a light dependent resistor  750 . The light dependent resistor (LDR)  750  is configured to increase in resistance when exposed to light. Thus, when the LDR  750  is exposed to light, eg. during the day, the LDR&#39;s  750  resistance increases and causes the transistor BC109 to shut off current to transistor S8040 thereby shutting turning off LED  630 . It should be noted that exposing the LDR  750  to light does not break the circuit by opening the switch  610 , but rather by preventing current flow through the transistors BC109 and S8040. Thus once the garden light is activated, as described above by pushing down on cap  12 , the circuit  700  is continually discharging power, irrespective of whether the LED  630  is illuminated or not, until the switch is opened. However, the rate of discharge of the circuit  700  in bright conditions with the LED  630  not illuminated is less than the self-discharge rate of the circuit  600  shown in  FIG. 6  when its switch  610  is open. Thus the circuit  700  does not result in any unnecessary discharge of power while the white LED is not emitting light despite the circuit being closed.  
         [0048]     In FIGS.  1  to  4  the external surface of the lens assembly  110  is made up of circumferential striations or lenticules  114  which are generally annular in nature and surround the external surface of the lens assembly  110 . These are can be replaced by a lens assembly  10 ′ which does not include such lenticules as is illustrated in the outdoor light  2  of  FIG. 5 .  
         [0049]     It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.  
         [0050]     The foregoing describes embodiments of the present invention and modifications, obvious to those skilled in the art can be made thereto, without departing from the scope of the present invention.

Technology Classification (CPC): 5