Abstract:
A system of lighting in which a multitude of secondary line extra-low voltage lights each have an individual dimmer control with voltage compensating circuitry. This enables pre-setting of individual brightness for each light in the multitude. The individual lights have substantially spherical housings that allow for partial burial at different angles of illumination. The system is especially suited for garden lighting.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to outdoor lighting, where variation in placement and brightness of individual lights may provide striing contrasts of illumination of plants or buildings within a garden or other area.  
       SUMMARY OF THE INVENTION  
       [0002]     A system of lighting in which a multitude of secondary line extra-low voltage lights each have an individual dimmer control enables setting of individual brightness for each light in the plurality. Each individual dimmer control can be pre-set during insallation or adjusted afterward. The entire system can be switched on or off with a manual switch, timer switch, or photocell switch on the primary line voltage side of an approved transformer for the system. “Line voltage” is defined as voltage in the range of 30-750 Volts. Household electrical voltage of approximately 110 Volts is an example of line voltage. “Extra-low voltage” is defined as voltage of less than 30 Volts. Garden lights and study lamps are often run at 12 or 24 volts and are an example of extra-low voltage lines. The secondary line extra-low voltage lights with their respective individual dimmer controls are powered from the extra-low voltage secondary side of the transformer, preferably in the range of 10 to 24 Volts.  
         [0003]     The multiple dimmer lighting system adjusts the brightness and power drawn by individual lamps via a configuration of secondary extra-low voltage lines. The extra-low voltage lamps thus have their light output adjusted individually. A printed circuit board which contains the control circuitry is mounted inside each lamp unit. After adjusting each lamp for brightness, the entire system can be turned on and off with a single switch. The system allows the use of extra-low voltage lamp units and extra-low voltage lines to connect the lamps in a configuration of AC or DC circuits preferably in the range of 10-24 volts, with light bulbs or like lighting units preferably being rated in the range of 12 to 40 Watts.  
         [0004]     Such extra-low voltage lines are suitable for installation by home owners and amateur electricians as garden lighting. The lines can be buried without special conduits or building permits in many areas, preserving safety for pets, children and others who might later dig in the area in which the system is installed.  
         [0005]     The dimmer control circuit compensates for voltage drop input and gives substantially the pre-selected light output, despite variations in secondary side output from the transformer or voltage drop due to secondary line length for various individual secondary power supply lines in the configuration. The individual lamp brightness is controlled by a switching dimmer circuit which varies the duty cycle of the power. This affects the lamp on time and hence varies the light output. To minimize lamp brightness changes with minor voltage variations, the supply voltage is sensed through divider resisters with feedback to an adjustment subcircuit. The voltage at the junction of the two resisters is fed to the integrated circuit to vary the duty cycle inversely to the supply voltage, thereby reducing the duty cycle as the voltage increases to maintain the lamp brightness about a constant level.  
         [0006]     In a preferred embodiment, each unit lamp is contained in a housing that is substantially spherical and watertight sealed, suitable for embedding in a garden or beneath a shrub or tree, with its light aperture uncovered and oriented in a selected direction. When buried the housing is secure and stable in its orientation and protected from collision or vandalism.  
         [0007]     The system switch can be an ordinary electrical wall-mounted switch inside or outside a house or building adjacent to or integral with an approved transformer. The system switch is on the primary voltage side of the transformer with the configuration of individual lamps connected to the secondary side of the transformer. Optionally, the system switch can be part of a remote control module implementing one of two methods. Radio, comprising a portable electronic radio frequency electronic remote control transmitter that transmits signals to control units in the housing of individual lights could be used, but it would be expensive. Alternatively and less costly, data can be sent down the power cables, using a remote control unit that would talk to a master receiver which would then send the signal down the power lines. Whether radio or data down the power cables is used, each lamp has its own ID and so although the signal would be received by all the lamp units, only the one with the correct ID would respond to the command.  
         [0008]     As a further option, the system can be programmable such that the extra-low voltage lamp units can be turned on or off in accordance with a predetermined order, to perform a light show. Several modes can be stored, for example, a bright mode for a party, a dimmer mode when users of the ground are unlikely, and an emergency or alarm mode.  
         [0009]     The individual lights are preferably supplied with soft-start electronics so that the individual lamps&#39; brightness is increased gradually after turning on the system until each individual lamp reaches its pre-set brightness level set by its dimmer circuit. The soft-start is part of the control integrated circuit and minimizes current surges and so helps extend the life of the individual lamps. The integrated circuit used is for power supply circuits where current surges can be damaging. Soft start occurs very quickly in the matter of a fraction of a second and may be barely noticed by an observer when the lamps are turned on. A longer, more noticeable soft start for aesthetic purposes could optionally be programmed into the system and could be done irrespective of remote control.  
         [0010]     The invention thus comprises a system of lighting in which a primary line voltage switch turns on or off a plurality of secondary extra-low voltage lines and lights each having individual dimmer controls that enable setting of different individual brightness levels.  
         [0011]     The dimmer controls each have a voltage variation compensating circuit that maintains a pre-selected brightness level for its light despite supply line voltage variations to the transformer or extra-low voltage variations in the transformer&#39;s output.  
         [0012]     An excellent embodiment would be to have such a system of multiple individually dimmed lights, in which:  
         [0013]     a) a plurality of individual dimmer controls can be accessed after installation for adjustment of pre-set dimming;  
         [0014]     b) a soft start module controls the multitude of lights upon turning on the system such that the lights gradually brighten to a pre-set level;  
         [0015]     c) a plurality of lights are each encased in a substantially spherical housing suited for tilting in a substantially spherical mounting place at various selected orientations;  
         [0016]     d) a plurality of lights are each encased in a weather-proof housing suited for partial burial in a garden;  
         [0017]     e) extra-low voltage insulated electrical supply lines are used to connect a plurality of lights within the system, suited for installation by property owners who are not electricians;  
         [0018]     f) a plurality of lights use extra-low voltage, long-life bulbs;  
         [0019]     This system of lights that are buried but shining upwards to illuminate trees, shrubs, and overhanging can be complemented by having some of the individually dimmable lights equipped with housings that each have a ledge and a rim surrounding a lens for the light. The ledge and rim are used to support and hold the cylindrical walls of a column supporting a mushroom cap shade that captures light energy shining up from the light and reflects it downward. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]      FIG. 1  is a block diagram showing a system of garden lights using the invention.  
         [0021]      FIG. 2  is a schematic diagram showing the electronics of an individual garden light of the system of  FIG. 1 .  
         [0022]      FIG. 3  is a top view of an individual garden light of the system of  FIG. 1 .  
         [0023]      FIG. 4  is a cross-sectional side view of the garden light of  FIG. 3 .  
         [0024]      FIG. 5  is an exploded cross-sectional side view of the garden light of  FIG. 3 .  
         [0025]      FIG. 6  is a side view showing a mushroom cap fitting into the garden light of  FIG. 4 .  
         [0026]      FIG. 7  is a perspective view showing the system of  FIG. 1  in operation. 
     
    
     DETAILED DESCRIPTION  
       [0027]     Referring to  FIG. 1 , the configuration consists of a first individual lamp  1 , a second individual lamp  2 , a third individual lamp  3 , a fourth individual lamp  4 , connected to a central primary line voltage control switch  5 , by extra-low voltage lines  6 ,  7 ,  8 . Each individual lamp  1 - 4  has its own dimmer circuit  9 ,  10 ,  11 , and  12  respectively.  
         [0028]     Referring to  FIG. 2 , the lamp brightness is controlled by a switching circuit in integrated circuit (IC) U 1  which controls the soft start and varies the duty cycle of the power through Q 1 . The dimming level is set with screw adjuster pot RV 1  which is rated 1K 20% 250 mW. This affects the lamp on time and hence the light output. To minimize lamp brightness changes with minor Voltage flow variations, the supply Voltage is sensed through the divider comprising R 9  and R 11 .  
         [0029]     Further electrical components complete the required circuits as shown in  FIG. 2 . C 1 , C 5  and C 6  are 100 nF monocap 50 V 20%; C 2  is 4,700 uF Electrolytic 35V 20%; C 3  is 10 uF electrolytic 16 V. Diodes D 1 -D 4  are 5 amps, 40 V; D 5  is 12V 5% 500 mW; D 6  is 1 Amp, 40 V. R 1  is 1K 5% 500 mW. R 2 -R 11  are all 5% 250 mW; with values R 2 - 6 K 8 , R 3  and R 4 - 10 K, R 5 - 22 K, R 6 - 10 R, R 7 - 47 K, R 8 - 1 K 2 , R 9 - 150 K, R 10 - 2 K 7 , R 11 - 4 K 7 . Fuse F 1  is a fast 4 amp fuse, mounted in fuse clip HW 1  on the dimmer control board  20 , which comprises a printed circuit board HW 2 . HW 3  is a heat sink to dissipate excess heat during operation to allow the components to function without degradation due to overheating. Q 1  is an FET rated at 60V 55A and Q 2  is a general purpose transistor 60 V 100 mA A current mode controller at U 1  has a 100% duty cycle and is rated to operate in the range of 0- to 70 degrees C. A microcontroller is used to decode the remote control commands, checks the message ID and decides if the command is for this particular lamp unit. If the command is for another lamp unit, it is ignored. Commands for the lamp control are interpreted by the microcontroller and the appropriate output signal produced. The microcontroller circuitry at P 1  can be set to instruct the controller U 1  to perform a “soft” start, whereby the lights gradually increase in output until the desired, pre-set brightness of the lights in the system is achieved. The radio frequency receiver module RF 1  is connected to the programmable logic integrated circuit P 1  to enable a remote control transmitter RC 1  to send commands to the dimmer control board  20 .  
         [0030]     Referring to  FIG. 3 , the lamp has a substantially spherical housing  21 , which is waterproof, suitable for burying such that only a top portion  22  adjacent to the lens cover  23  is exposed to shine on the target objects to be illuminated. The lens rim seal  24  keeps rain and dust from entering the lamp.  
         [0031]     Referring to  FIGS. 4 and 5 , the housing  21  has a wire inlet  31 , a wire inlet grommet  32 , adapted to seal around an electrical supply wire and match the waterproof functionality of the housing  21 , a wire inlet bolt  33 , and a complementary nut  34 . The wire inlet bolt  33  also serves to hold the bottom flange  35  of the dimmer control board  36 . The dimmer&#39;s screw adjuster pot RV 1  is set on an upper side flange  36  to enable to be positioned behind adjuster aperture  37 . A dimmer screw adjuster plug  38  fits into the aperture  37  to seal against rain and dirt. A sealed beam light source  39 , with electrical contacts  40  and  41  fits within the sealed beam cradle  42 . The cradle is held in position in the housing  21  by means of compression flange  43 . The lens rim seal  24  can be made of resilient material of a close-fitting tolerance pressed into position on the lens seal rim ledge  44 . The housing  21  has an optional shade support ledge  71  and shade holding rim  72 , suited to hold a shade wall  73 . Thus in place of a flush lens seal, a mushroom shaped shade and reflector can be fitted onto the housing  21  as shown in  FIG. 6 . The mushroom shade and reflector  51  has a hollow column  52  up which the light from the lamp travels. Slots in the column near its top allow the light to then be reflected down from the underside  53  of the mushroom-shaped cap  54 . The top of the mushroom-shaped cap  55  acts as a roof or umbrella to deflect rain, wind, dust, and snow from falling on the lamp.  
         [0032]     Referring to  FIG. 7 , the individual lamps  1 ,  2 ,  3  and  4  are pre-set at different levels of brightness. Lamp  1  is set at maximal brightness to illuminate a tall tree  61 . Lamp  2  is set at a medium level to illuminate a shorter tree  62 . Lamp  3  is set at a moderate level to illuminate a flower bed  63  via a mushroom-shaped shade and reflector  51 . Lamp  4  is shown buried at an angle to illuminate an adjacent upright plant  64 .  
         [0033]     The extra-low voltage lines from the transformer to the individual lights can be more than a hundred yards long yet provide a consistent pre-selected light level due to the dimmer voltage compensation circuit.  
         [0034]     As an alternative to having a remote control transmit wirelessly to individual lamp units&#39; receiving modules is to transmit control signals down the extra-low voltage lines, which can thus be used as signal lines as well as electrical power supply lines.  
         [0035]     The within-described invention may be embodied in other specific forms and with additional options and accessories without departing from the spirit or essential characteristics thereof The presently disclosed embodiment is 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 equivalence of the claims are therefore intended to be embraced therein.