Abstract:
A lighting system includes multiple extendable and retractable light units. Each light unit includes a housing with inner and outer sleeves, which are telescopically interconnected. A drive assembly is located in each housing for extending and retracting the inner sleeve whereby a luminaire mounted in the inner sleeve can be selectively elevated. The housings are adapted for flush-mounting in the ground with their inner sleeves retracted. The lighting system can include a centralized control subsystem for collectively and individually operating the individual light units.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to lighting systems, and in particular to an automated lighting system with extendable and retractable light units controlled by a centralized control system. 
         [0003]    2. Description of the Related Art 
         [0004]    Lighting systems are available in a wide variety of designs, which accommodate various lighting applications and environments. For example, fixed-position lighting systems are commonly used for applications with relatively constant conditions. Other lighting systems can be repositioned as needed for particular illumination tasks. Both fixed-position and movable lighting systems are used for indoor and outdoor applications. Outdoor lighting applications present several challenges to the designer. For example, ambient weather conditions must be considered and can include precipitation, temperature extremes, ultraviolet (UV) radiation, etc. 
         [0005]    Another consideration affecting lighting design relates to concealing and/or otherwise protecting the lighting fixtures or units when they are not being used. For example, landscape lights are generally associated with exterior applications and can be used for illuminating and accentuating landscape designs. Low voltage power supplies (e.g., 12 V) are commonly used to reduce electrical shock hazards and to enable multiple light units to receive power via light gauge electrical leads from common power sources. Such power sources are commonly connected to the power systems of buildings and the transformed electrical power is distributed to multiple lighting units around the premises. For example, a common application for low-voltage lighting systems relates to illuminating walkways, driveways and other circulation structures for pedestrians and vehicles. Such light fixtures can be conveniently installed in the ground with the wiring runs between the power source and the fixtures buried below grade. Ground-mounted systems can effectively illuminate the ground-level surfaces of circulation structures such as driveways and walkways, and are particularly effective and attractive in applications not requiring general illumination. 
         [0006]    In many applications, particularly outdoors, it would be advantageous to retract the light fixtures below grade for protection from surface traffic, such as vehicles, pedestrians and maintenance equipment. Maintenance, such as mowing, snow removal, etc., can be performed more efficiently if the light fixtures are temporarily retracted into below-grade receptacles. 
         [0007]    Such extendable and retractable fixtures have previously been proposed. For example, U.S. Pat. No. 5,075,834; U.S. Pat. No. 5,513,085; U.S. Pat. No. 5,068,773; U.S. Pat. No. 5,072,345 and U.S. Pat. No. 5,124,902 all show retractable light fixtures. However, heretofore there has not been available an extendable/retractable light fixture with the advantages and features of the present invention. 
       SUMMARY OF THE INVENTION 
       [0008]    In the practice of an aspect of the present invention, an extendable and retractable light unit is provided. Multiple light units can be configured in an automated lighting system, which can be interconnected by a power and communication network with a centralized power source and controller. The controller can be programmable to control various functions of the individual light units, such as automatic extension/retraction, illumination, timing and various other functions permitting a wide range of lighting effects. The light units have first and second sleeves, which are telescopically interconnected and have extended and retracted positions with respect to each other. A luminaire is mounted in each second sleeve and is positioned to distribute light when the second sleeve is extended from the first. A drive mechanism includes a motor and an extension/retraction drive assembly connected thereto and to the sleeves for moving them between their extended and retracted positions. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a block diagram of an automated lighting system embodying an aspect of the present invention and including multiple light units. 
           [0010]      FIG. 2  is a perspective view thereof, showing an inner sleeve thereof extended. 
           [0011]      FIG. 3  is a vertical, cross-sectional view of a light unit with a scissor jack extension/retraction drive assembly, showing the inner sleeve retracted. 
           [0012]      FIG. 4  is a vertical, cross-sectional view thereof, showing the inner sleeve extended. 
           [0013]      FIG. 5  is a vertical, cross-sectional view of another aspect of the invention, with a crank arm extension/retraction drive assembly. 
           [0014]      FIG. 6  is a fragmentary, vertical, cross-sectional view of another aspect of the invention, with a rack-and-opinion extension/retraction drive assembly and the inner sleeve retracted. 
           [0015]      FIG. 7  is a fragmentary, vertical, cross-sectional view thereof, with the inner sleeve extended. 
           [0016]      FIG. 8  is a vertical, cross-sectional view of another aspect of the invention, with a threaded rod extension/retraction drive assembly. 
           [0017]      FIG. 9  is a vertical, cross-sectional view of another aspect of the invention, with a piston-and-cylinder unit extension/retraction drive assembly. 
           [0018]      FIG. 10  is a vertical, cross-sectional view of another aspect of the invention, with a solenoid extension/retraction drive assembly. 
           [0019]      FIG. 11  is a vertical, cross-sectional view of another aspect of the invention, with drainholes in a bottom of an outer sleeve thereof. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     I. Introduction and Environment 
       [0020]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Certain terminology will be used in the following description for convenience in reference only and will not be limiting. Said terminology will include the words specifically mentioned, derivatives thereof and words of similar meaning. 
         [0021]    Referring to the drawings in more detail, the reference numeral  2  generally designates an automated lighting system embodying an aspect of the present invention. A control subsystem  4  includes a microprocessor  6 , which is preferably programmable and chosen for its suitability for the intended applications of the lighting system  2 . An input device  8  can comprise any suitable device for providing an input to the microprocessor  6 . For example, the input device  8  can comprise a keyboard, another microprocessor, storage media, sensors (e.g. photovoltaic, motion-sensing, sound-responsive, voice command, etc.), switching devices and other suitable input devices. A timer  10  can be connected to the microprocessor  6  and activate the system  2  at predetermined times and for predetermined intervals. For example, the system  2  might be active only during certain hours of darkness, which condition could also be sensed by a photovoltaic sensor input device. 
         [0022]    An output  12  is connected to the microprocessor  6  and can include an optional transmitter  14  and hardwire connections  16 , which can include both communication signals and power leads from a suitable power supply  18 . The hardwire connections can extend to multiple light units  22  via a network  20 . Alternatively or in addition to the hardwire network  20 , control signals can emit from the transmitter  14  for wireless operation. 
         [0023]    Multiple light units  22  are shown, but it will be appreciated that a single light unit  22  can operate in a stand-alone mode. For example, a photovoltaic cell and a rechargeable battery can comprise the power supply  18  whereby the light unit  22  can operate independently of external connections. 
         [0024]    The light unit  22  can include an optional receiver  24 , which can receive control signals from the transmitter  14 . A sensor  26  in the light unit  22  can provide an input to the microprocessor  6 . For example, the sensor  26  can comprise a photovoltaic resistor responding to ambient light conditions and providing an appropriate light level indicating signal to the microprocessor  6 . A luminaire assembly  28  can comprise a suitable light source, which can vary considerably depending upon the desired lighting effects. For example, incandescent and fluorescent light fixtures can be installed in the unit  22 . Moreover, LEDs can be utilized effectively, including applications with low voltage electrical power. The luminaire assemblies  28  can provide a wide range of lighting effects, including chromatics (color), blinking and flashing (strobe) effects. Another application of the system  2  is for airport lighting, e.g. airfield runway and taxiway lights. The light units  22  can be retracted into protected positions when not in use. The control subsystem  4  can operate the lights  22  according to predetermined sequences, color effects and other operational characteristics as necessary for airfield operations. 
         [0025]    An extension/retraction drive assembly  30  is connected to the luminaire assembly  28 , which is operated by a motor  32 . The motor  32  can comprise any suitable motive source, including electrical motors, solenoids, piston-and-cylinder units (pneumatic and hydraulic), etc. The luminaire assembly  28  can be automatically activated, for example when the light unit is extended by the drive assembly  30 . Electrical contact switches or other suitable devices can be utilized for such an automatic illumination function. 
         [0026]      FIG. 2  shows an in-ground application of the light unit  22  including a telescoping housing  34  with a lower, outer sleeve  36  located generally below grade and telescopically receiving an upper, inner sleeve  38  for raising and lowering between extended and retracted positions. The outer sleeve  36  includes proximate and distal ends  35 ,  37 . The inner sleeve  38  includes proximate and distal ends  39 ,  41 . A cap  40  is mounted on the distal end  41  of the inner sleeve  38  and can comprise a light-transmitting material. The cap  40  can have various configurations, including cylindrical, domed, etc., and can comprise a light-transmitting lens. 
         [0027]      FIGS. 3 and 4  show an aspect of the invention wherein drive assembly  30  of the light unit  22  includes a reversible, DC motor  32  drivingly connected to a threaded rod  34 , which is threadably connected to a scissor jack  42  at a lower end  44  thereof. An upper end  46  of the scissor jack  42  is connected to a boss  48  extending into the interior of the inner sleeve  38 . As shown in  FIG. 4 , the inner sleeve  38  is extended by turning the motor  32  in a first direction and thereby expanding the scissor jack  42 . Turning the motor  32  in a second, opposite direction contracts the scissor jack  42  and retracts the inner sleeve  38 . The scissor jack  42  includes a first articulated linkage  43  with upper and lower arms  43   a ,  43   b  and a second articulated linkage  45  with upper and lower arms  45   a,    45   b.  The scissor jack  42  can optionally comprise opposed pairs of articulated linkages  43 ,  45 , with the motor  32  and the boss  48  located therebetween. A pivot pin  50  extends through the scissor jack  42  in proximity to its lower end  44  and is embedded in or otherwise attached to the outer sleeve  36  in proximity to its proximate end  35 . 
         [0028]      FIG. 5  shows a light unit  52  comprising an alternative aspect or embodiment of the invention with a crank arm drive assembly  54 , which includes a DC electric motor  56  mounting a crank arm  58  connected to a linking arm  60 , which in turn is pivotally connected to the inner sleeve  38 . Rotating the motor  56  (in either direction) raises and lowers the inner sleeve  38  between its extended and retracted positions.  FIGS. 6 and 7  show a light unit  62  comprising another modified embodiment or aspect of the invention and including a rack-and-pinion drive assembly  64 , which is adapted for lowering (retracting) the inner sleeve  36  when a pinion  66  rotates counterclockwise (as viewed in  FIG. 6 ) and for raising (extending) the inner sleeve  36  when the pinion  66  rotates clockwise. 
         [0029]      FIG. 8  shows a light unit  72  comprising another alternative aspect or embodiment of the present invention and including a drive assembly  74  including a reversible, DC electric motor  76  drivingly connected to a threaded rod  78  connected to and adapted for extending and retracting the inner sleeve  38 .  FIG. 9  shows a light unit  82  comprising another alternative aspect or embodiment of the present invention with a fluid-powered drive assembly  84  including a piston-and-cylinder unit  86  with upper and lower fluid lines  88 ,  90 . The centralized power supply  18  can include, in addition to an electrical power source, a fluid power source such as a compressor or an hydraulic pump for driving the piston-and-cylinder unit  86 . A suitable network of air or hydraulic fluid lines can be extended from the centralized power supply  18  to the individual light units  82 . Alternatively, individual fluid power sources can be provided for each light unit  82  and individually or collectively controlled by the control subsystem  4 . The piston-and-cylinder unit  86  can be either single-acting with a return spring or double-acting for a fluid power return stroke. 
         [0030]      FIG. 10  shows a light unit  92  comprising another alternative aspect or embodiment of the present invention with a drive assembly  94  including a solenoid  96  connected at a lower end thereof to the outer sleeve  36  and connected to the inner sleeve  38  at an upper end of an actuating rod  98  thereof.  FIG. 11  shows a modified outer sleeve  100  with multiple drain passages  102  located in a base  104  of the modified outer sleeve  100 . The outer sleeve  100  is thereby adapted to drain. Alternatively, the housing  34  can be constructed with suitable seals and watertight construction for maintaining a relatively dry interior, even when buried in soil conditions susceptible to high moisture contents and flooding. 
         [0031]    In operation the lighting system  2  can be preprogrammed for a wide variety of special effects. For example, extension and retraction of the light units can be timed for operation during predetermined hours of darkness. Photovoltaic sensors can be provided for automatically actuating the extension/retraction mechanisms in response to predetermined light levels. The light units can be preprogrammed for sequential operation and various other operating sequences, including random operation. 
         [0032]    The luminaire assemblies  28  can utilize various lighting technologies in order to achieve desired operating and lighting effects. For example, incandescent, fluorescent, LED and other lighting technologies can be utilized. The luminaire assemblies can comprise multiple individual lights, which in turn can have different characteristics such as color, intensity, directional orientation, etc. The individual lights within the light units can also be individually controlled for sequencing and timing effects. 
         [0033]    It is to be understood that the invention can be embodied in various forms, and is not to be limited to the examples discussed above. Other components and configurations can be utilized in the practice of the present invention.