A three-level LED security light, comprising:
- at least one first light-emitting unit configured with at least two LED circuits electrically connected in parallel including at least a first LED circuit comprising a first LED load emitting a first white light with a first color temperature and at least a second LED circuit comprising a second LED load emitting a second white light with a second color temperature for generating an illumination characterized by a light intensity and a mingled light color temperature, wherein the illumination of the first light-emitting unit is designed to brighten up an outdoor living space, wherein the second color temperature is higher than the first color temperature, namely CT2>CT1;
- at least one first light diffuser covering the at least one first light-emitting unit to serve as a light mixer capable of blending the first white light and the second white light to generate the illumination of the first light-emitting unit with the mingled light color temperature, wherein the at least one first light-emitting unit is installed inside a lamp housing covered by the first light diffuser;
- a second light-emitting unit configured with at least a third LED circuit including a third LED load emitting a third white light with a third color temperature for generating an illumination characterized by a light intensity and the third color temperature, wherein the illumination of the second light-emitting unit is an edge lighting for performing a surface-wash illumination designed to brighten up at least a first surface of a mounting surface behind the LED security light, wherein the second light-emitting unit is installed inside a back plate housing which mounts the LED security light to the mounting surface and covers an electric outlet of the mounting surface, wherein at least a first side surface of the back plate housing is designed with a first opening covered by a second light diffuser to enable the third LED load to outwardly emit and diffuse the third light along the first surface to perform the surface-wash illumination thru the first opening;
- a switching circuitry electrically coupled with a power source from a power supply unit and the two light-emitting units to output at least one DC power with a constant current for energizing the first light-emitting unit and the second light-emitting unit;
- a first power allocation circuitry installed with the switching circuitry and the first light-emitting unit to allocate a first electric power X delivered to the first LED circuit and a second electric power Y delivered to the second LED circuit to perform a selection of the mingled light color temperature of the illumination generated by the first light-emitting unit thru the first light diffuser when the first light-emitting unit is energized;
- a second power allocation circuitry installed with the switching circuitry and the second light-emitting unit to control a third electric power delivered to the third LED circuit to emit the third white light with the third color temperature for generating the illumination of the second light-emitting unit;
- a power allocation algorithm, working in conjunction with the first power allocation circuitry to operate a power allocation scheme comprising a plurality of power loading options configured with different paired combinations of the first electric power X delivered to the first LED circuit and the second electric power Y delivered to the second LED circuit by implementing a reverse yet complementary power adjustment process between the first electric power X and the second electric power Y such that a total light intensity generated by the first LED load and the second LED load remains unchanged while the mingled light color temperature of the illumination of the first light-emitting unit thru the first light diffuser is being adjusted;
- wherein the first LED load, the second LED load and the third LED load are phosphor based white LEDs produced by coating phosphor compounds on the surface of LEDs to respectively generate the white light LEDs with the first color temperature, the second color temperature and the third color temperature;
- wherein the units of the mingled light color temperature generated by the first light-emitting unit, the first color temperature generated by the first LED load, the second color temperature generated by the second LED load and the third color temperature generated by the third LED load are Kelvin (K), and the units of the first electric power X and the second electric power Y are Watt (W);
- at least one first external control device, configured with a selection switch comprising a plurality of switching positions to operate the first power allocation circuitry for selecting and activating a corresponding power loading option in the power allocation scheme for performing a corresponding mingled light color temperature;
- A light sensing control unit;
- A motion sensing unit;
- and
- a controller, electrically coupled with the first power allocation circuitry, the second power allocation circuitry, the light sensing control unit, the motion sensing unit and at least the first external control device;
- wherein the first power allocation circuitry is configured with a first semiconductor switching device electrically connected with the switching circuitry and the first LED circuit, and a second semiconductor switching device electrically connected with the switching circuitry and the second LED circuit, wherein the second power allocation circuitry is configured with a third semiconductor switching device electrically connected with the switching circuitry and the third LED circuit;
- wherein the controller is electrically coupled with the first semiconductor switching device, the second semiconductor switching device, the third semiconductor switching device and at least the first external control device;
- wherein for activating the first power allocation circuitry, the controller outputs a first control signal to control a first conduction rate of the first semiconductor switching device to deliver the first electric power to the first LED circuit and a second control signal to control a second conduction rate of the second semiconductor switching device to deliver the second electric power to the second LED circuit for controlling the light intensity and the mingled light color temperature of the illumination generated by the first light-emitting unit, wherein for activating the second power allocation circuitry, the controller outputs a third control signal to control a third conduction rate of the third semiconductor switching device to deliver the third electric power to the third LED circuit for controlling the light intensity of the second light-emitting unit such that the LED security light respectively generates illuminations of different light intensity and different color temperatures according to control signals respectively received from the light sensing control unit, the motion sensing unit and the first external control device;
- wherein when an ambient light detected by the light sensing control unit is lower than a first predetermined value, the controller operates to activate the first power allocation circuitry to deliver the first electric power to the first LED circuit and the second electric power to the second LED circuit to perform a first level illumination characterized by a first light intensity and a first mingled light color temperature for a first predetermined time duration with the motion sensing unit being temporarily deactivated;
- wherein upon a maturity of the first predetermined time duration, the controller operates to deactivate the first power allocation circuitry to turn off the first light-emitting unit and simultaneously operates to activate the second power allocation circuitry to deliver the third electric power to the second light-emitting unit to perform a second level illumination characterized by a second light intensity and the third color temperature, at the same time the motion sensing unit is activated;
- wherein when a motion signal is detected by the motion sensing unit, the controller operates to deliver the first electric power to the first LED circuit and the second electric power to the second LED circuit to perform a third level illumination characterized by a third light intensity and a second mingled light color temperature for a second predetermined time duration before being turned off to switch back to continue the second level illumination characterized by the second light intensity and the third color temperature;
- wherein when the ambient light detected by the light sensing control unit is higher than a second predetermined value, the controller operates to switch off the LED security light.