Multi-level LED security light with motion sensor

An LED security light comprising:

• a light-emitting unit comprising a plurality of LEDs divided into two LED loads including a first LED load with N number LEDs emitting light with a first color temperature and a second LED load with M number LEDs emitting light with a second color temperature, wherein the first color temperature is designed with a value in a range between 1800K and 3000K and the second color temperature is designed with a value in a range between 4000K and 6500K, wherein M and N are positive integers with a value of M being greater than or equal to a value of N;
• a light diffuser covering the first LED load and the second LED load to create a diffused light with a diffused light color temperature;
• a loading and power control unit;
• a light sensing control unit;
• a motion sensing unit;
• a power supply unit;
• and
• an external control unit including at least one external control device outputting at least one external control signal for tuning and setting the diffused light color temperature;
• wherein the loading and power control unit includes at least a controller and an LED driver circuitry, wherein the LED driver circuitry is electrically connected with a DC power source of the power supply unit and the light-emitting unit for managing a DC power delivered to the light-emitting unit;
• wherein the LED driver circuitry is further configured with a first LED driver comprising a first semiconductor switching device electrically coupled to the first LED load and a second LED driver comprising a second semiconductor switching device electrically coupled to the second LED load;
• wherein the controller is electrically coupled with the first LED driver, the second LED driver, the light sensing control unit, the motion sensing unit, and the at least one external control device;
• wherein when the light-emitting unit is in a turned-on state, the controller further outputs a first control signal to control a first conduction rate of the first semiconductor switching device of the first LED driver and a second control signal to control a second conduction rate of the second semiconductor switching device of the second LED driver to respectively deliver a first electric power to the first LED load and a second electric power to the second LED load to generate the diffused light with the diffused light color temperature thru the light diffuser according to the at least one external control signal;
• wherein for tuning the diffused light color temperature, the controller operates a power allocation algorithm to reversely and complementarily adjust the first electric power and the second electric power respectively delivered to the first LED load and the second LED load such that a sum of the first electric power and the second electric power remains unchanged;
• wherein for tuning the diffused light color temperature to a lower diffused light color temperature, the controller operates according to the power allocation algorithm to increase the first conduction rate of the first semiconductor switching device to increase the first electric power delivered to the first LED load and simultaneously operates to decrease the second conduction rate of the second semiconductor switching device to decrease the second electric power delivered to the second LED load with the same pace such that a total light intensity generated by the light-emitting unit remains unchanged while the diffused light color temperature is accordingly adjusted to the lower diffused light color temperature;
• wherein for tuning the diffused light color temperature to a higher diffused light color temperature, the controller operates according to the power allocation algorithm to decrease the first conduction rate of the first semiconductor switching device to decrease the first electric power delivered to the first LED load and simultaneously operates to increase the second conduction rate of the second semiconductor switching device to increase the second electric power delivered to the second LED load with the same pace such that the total light intensity generated by the light-emitting unit remains unchanged while the diffused light color temperature is accordingly adjusted to the higher diffused light color temperature;
• wherein when a light intensity level of an ambient light detected by the light sensing control unit is lower than a first predetermined value, the loading and power control unit operates to activate the motion sensing unit for controlling a lighting performance of the light-emitting unit;
• wherein when a motion signal is detected by the motion sensing unit, the loading and power control unit operates to deliver an electric power to the light-emitting unit to generate an illumination characterized by the diffused light with a selected diffused light color temperature according to the at least one external control signal received from the motion sensing unit for a predetermined time duration before resuming to a turned-off state of the light-emitting unit;
• wherein when the light intensity level of the ambient light detected by the light sensing control unit is higher than a second predetermined value, the loading and power control unit manages to deactivate the motion sensing unit to turn off all LEDs of the light-emitting unit;
• and
• wherein the N number LEDs of the first LED load and the M number LEDs of the second LED load are respectively designed with a configuration of in series and/or in parallel connections such that when incorporated with a power level setting of the DC power, a constant electric current passing through each LED of the first LED load and each LED of the second LED load remains at a level such that a voltage V across each LED complies with an operating constraint of Vth<V<Vmax featuring electrical characteristics of an LED, wherein Vth is a reference value of a threshold voltage required to trigger each LED to start emitting light and Vmax is a reference value of a maximum operating voltage across each LED at which at least one LED construction in said plurality of LEDs is vulnerable to a thermal damage.

A method of configuring an LED lighting device with a tunable diffused light color temperature, comprising:

• using a light-emitting unit comprising a plurality of LEDs divided into at least two LED loads including at least a first LED load with N number LEDs emitting light with a first color temperature and at least a second LED load with M number LEDs emitting light with a second color temperature, wherein the first color temperature is designed with a value in a range between 1800K and 3000K and the second color temperature is designed with a value in a range between 4000K and 6500K, wherein M and N are positive integers with a value of M being greater than or equal to a value of N;
• using a light diffuser covering the first LED load and the second LED load to create a diffused light with a diffused light color temperature;
• using a power allocation circuitry electrically connected with a power source from a power supply unit and the light-emitting unit to manage a distribution of a DC power between a first electric power delivered to the first LED load and a second electric power delivered to the second LED load to perform an illumination characterized by the diffused light with the diffused light color temperature;
• and
• using at least one external control device to output at least one external control signal for tuning and selecting a corresponding diffused light color temperature performance;
• wherein the power allocation circuitry comprises at least a controller and an LED driver circuitry, wherein the LED driver circuitry is further configured with a first LED driver comprising a first semiconductor switching device electrically coupled to the first LED load and a second LED driver comprising a second semiconductor switching device electrically coupled to the second LED load for controlling the first electric power and the second electric power respectively delivered to the first LED load and the second LED load;
• wherein the controller is electrically coupled with the first LED driver, the second LED driver, and the at least one external control device;
• wherein for tuning the diffused light color temperature, the controller operates a power allocation algorithm to reversely and complementarily adjust the first electric power and the second electric power respectively delivered to the first LED load and the second LED load such that a sum of the first electric power and the second electric power remains unchanged;
• wherein the controller operates the power allocation algorithm to output a first control signal to control a first conduction rate of the first semiconductor switching device of the first LED driver and a second control signal to control a second conduction rate of the second semiconductor switching device of the second LED driver to respectively deliver the first electric power to the first LED load and the second electric power to the second LED load to generate the diffused light with the diffused light color temperature thru the light diffuser according to the at least one external control signal;
• wherein for tuning the diffused light color temperature, the controller operates the power allocation algorithm to reversely and complementarily adjust the first electric power and the second electric power respectively delivered to the first LED load and the second LED load such that the sum of the first electric power and the second electric power remains unchanged;
• wherein for tuning the diffused light color temperature to a lower diffused light color temperature, the controller operates the power allocation algorithm to increase the first conduction rate of the first semiconductor switching device to increase the first electric power delivered to the first LED load and simultaneously operates to decrease the second conduction rate of the second semiconductor switching device to decrease the second electric power delivered to the second LED load with the same pace such that a total light intensity generated by the light-emitting unit remains unchanged while the diffused light color temperature is accordingly adjusted to the lower diffused light color temperature;
• wherein for tuning the diffused light color temperature to a higher diffused light color temperature, the controller operates the power allocation algorithm to decrease the first conduction rate of the first semiconductor switching device to decrease the first electric power delivered to the first LED load and simultaneously operates to increase the second conduction rate of the second semiconductor switching device to increase the second electric power delivered to the second LED load with the same pace such that the total light intensity generated by the light-emitting unit remains unchanged while the diffused light color temperature is accordingly adjusted to the higher diffused light color temperature;
• and
• wherein the N number LEDs of the first LED load and the M number LEDs of the second LED load are respectively designed with a configuration of in series and/or in parallel connections such that when incorporated with a power level setting of the DC power, a constant electric current passing through each LED of the first LED load and each LED of the second LED load remains at a level such that a voltage V across each LED complies with an operating constraint of Vth<V<Vmax featuring electrical characteristics of an LED, wherein Vth is a reference value of a threshold voltage required to trigger each LED to start emitting light and Vmax is a reference value of a maximum operating voltage across each LED at which at least one LED construction in said plurality of LEDs is vulnerable to a thermal damage.

An LED lighting device configured with a tunable diffused light color temperature, comprising:

• a light-emitting unit comprising a plurality of LEDs divided into at least two LED loads including at least a first LED load with N number LEDs emitting light with a first color temperature and at least a second LED load with M number LEDs emitting light with a second color temperature, wherein the first color temperature is designed with a value in a range between 1800K and 3000K and the second color temperature is designed with a value in a range between 4000K and 6500K, wherein M and N are positive integers with a value of M being greater than or equal to a value of N;
• a light diffuser covering the first LED load and the second LED load to create a diffused light with a diffused light color temperature;
• a power allocation circuitry electrically connected with a power source from a power supply unit and the light-emitting unit to manage a distribution of a DC power between a first electric power delivered to the first LED load and a second electric power delivered to the second LED load to perform an illumination characterized by the diffused light with the diffused light color temperature;
• and
• at least one external control device to output at least one external control signal for tuning and selecting diffused light color temperature performance;
• wherein the power allocation circuitry comprises at least a controller and an LED driver circuitry, wherein the LED driver circuitry is further configured with a first LED driver comprising a first semiconductor switching device electrically coupled to the first LED load and a second LED driver comprising a second semiconductor switching device electrically coupled to the second LED load for controlling the first electric power and the second electric power respectively delivered to the first LED load and the second LED load;
• wherein the controller is electrically coupled with the first LED driver, the second LED driver, and the at least one external control device;
• wherein when the light-emitting unit is in a turned-on state, the controller further outputs a first control signal to control a first conduction rate of the first semiconductor switching device of the first LED driver and a second control signal to control a second conduction rate of the second semiconductor switching device of the second LED driver to respectively deliver the first electric power to the first LED load and the second electric power to the second LED load to generate the diffused light with the diffused light color temperature thru the light diffuser according to the at least one external control signal;
• wherein for tuning the diffused light color temperature, the controller operates a power allocation algorithm to reversely and complementarily adjust the first electric power and the second electric power respectively delivered to the first LED load and the second LED load such that a sum of the first electric power and the second electric power remains unchanged;
• wherein for tuning the diffused light color temperature to a lower diffused light color temperature, the controller operates to increase the first conduction rate of the first semiconductor switching device to increase the first electric power delivered to the first LED load and simultaneously operates to decrease the second conduction rate of the second semiconductor switching device to decrease the second electric power delivered to the second LED load with the same pace such that a total light intensity generated by the light-emitting unit remains unchanged while the diffused light color temperature is accordingly adjusted to the lower diffused light color temperature;
• wherein for tuning the diffused light color temperature to a higher diffused light color temperature, the controller operates to decrease the first conduction rate of the first semiconductor switching device to decrease the first electric power delivered to the first LED load and simultaneously operates to increase the second conduction rate of the second semiconductor switching device to increase the second electric power delivered to the second LED load with the same pace such that the total light intensity generated by the light-emitting unit remains unchanged while the diffused light color temperature is accordingly adjusted to the higher diffused light color temperature;
• wherein the controller is designed with at least one diffused light color temperature switching scheme comprising a plurality of different diffused light color temperature performances to be respectively activated by the at least one external control signal generated by the at least one external control device, wherein different paired combinations of the first conduction rate and the second conduction rate respectively for controlling the first electric power delivered to the first LED load and the second electric power delivered to the second LED load for creating different diffused light color temperatures are preprogrammed and executed by the controller for operating a pick and play process according to the at least one external control signal generated by the at least one external control device for selecting a corresponding diffused light color temperature performance in the at least one diffused light color temperature switching scheme;
• and
• wherein the N number LEDs of the first LED load and the M number LEDs of the second LED load are respectively designed with a configuration of in series and/or in parallel connections such that when incorporated with a power level setting of the DC power, an electric current passing through each LED of the first LED load and each LED of the second LED load remains at a level such that a voltage V across each LED complies with an operating constraint of Vth<V<Vmax featuring electrical characteristics of an LED, wherein Vth is a reference value of a threshold voltage required to trigger each LED to start emitting light and Vmax is a reference value of a maximum operating voltage across each LED at which at least one LED construction in said plurality of LEDs is vulnerable to a thermal damage.

An LED lighting device comprising:

• a light-emitting unit comprising a plurality of LEDs divided into two LED loads including a first LED load with N number of LEDs emitting light with a first color temperature and a second LED load with M number of LEDs emitting light with a second color temperature, wherein the first color temperature is designed with a value in a range between 1800K and 3000K and the second color temperature is designed with a value in a range between 4000K and 6500K, wherein M and N are positive integers with a value of M being greater than or equal to a value of N;
• a light diffuser covering the first LED load and the second LED load to create a diffused light with a diffused light color temperature;
• a power allocation circuitry electrically connected with a power source from a power supply unit and the light-emitting unit to operate a plurality of different power loading options between delivering a first electric power to the first LED load and delivering a second electric power to the second LED load to perform an illumination characterized by the diffused light with the diffused light color temperature;
• and
• at least one external control device to output at least one external control signal for tuning and selecting a corresponding diffused light color temperature performance;
• wherein the power allocation circuitry is designed to operate the plurality of different power loading options according to a power allocation algorithm for distributing and loading a DC power between the first electric power delivered to the first LED load and the second electric power delivered to the second LED load, wherein each of the plurality of different power loading options is configured with a paired combination of the first electric power and the second electric power for generating the diffused light with the diffused light color temperature to form a diffused light color temperature switching scheme comprising a plurality of different diffused light color temperature performances for selection, wherein for generating and executing each of the plurality of different power loading options, the first electric power and the second electric power in each paired combination are to be reversely and complementarily adjusted according to the power allocation algorithm such that a sum of the first electric power and the second electric power respectively delivered to the first LED load and the second LED load is maintained at a constant level to characterize a technical foundation of the color temperature switching scheme;
• and
• wherein the N number LEDs of the first LED load and the M number LEDs of the second LED load are respectively designed with a configuration of in series and/or in parallel connections such that when incorporated with a power level setting of the DC power, an electric current passing through each LED of the first LED load and each LED of the second LED load remains at a level such that a voltage V across each LED complies with an operating constraint of Vth<V<Vmax featuring electrical characteristics of an LED, wherein Vth is a reference value of a threshold voltage required to trigger each LED to start emitting light and Vmax is a reference value of a maximum operating voltage across each LED at which at least one LED construction in said plurality of LEDs is vulnerable to a thermal damage.

A multi-level LED security light comprising:

• a light-emitting unit configured with at least a first LED load for emitting light with a first color temperature in a range between 1800K and 3000K and at least a second LED load for emitting light with a second color temperature in a range between 4000K and 6500K;
• a light diffuser covering the first LED load and the second LED load to create a diffused light with a diffused light color temperature;
• a loading and power control unit;
• a light sensing control unit;
• a motion sensing unit;
• a power supply unit;
• and
• an external control unit including at least one external control device outputting at least one external control signal;
• wherein the loading and power control unit includes at least a controller and an LED driver circuitry, wherein the LED driver circuitry is electrically connected with a power source of the power supply unit and the light-emitting unit for managing a DC power delivered to the light-emitting unit;
• wherein the LED driver circuitry is further configured with a first LED driver and a second LED driver, wherein the first LED driver comprises a first semiconductor switching device electrically connected to the first LED load and the second LED driver comprises a second semiconductor switching device electrically connected to the second LED load for managing a distribution of the DC power between delivering a first electric power to the first LED load and delivering a second electric power to the second LED load;
• wherein the controller is electrically coupled with the first LED driver, the second LED driver, the light sensing control unit, the motion sensing unit, and the at least one external control device;
• wherein when the light emitting-unit is in a turned-on state, the controller outputs a first control signal and a second control signal to respectively control a first conduction rate of the first semiconductor switching device and a second conduction rate of the second semiconductor switching device to respectively deliver the first electric power to the first LED load and the second electric power to the second LED load to perform different illumination modes of the multi-level LED security light characterized by different diffused light intensities and different diffused light color temperatures according to signals respectively received from the light sensing control unit, the motion sensing unit and the at least one external control device;
• wherein the controller is designed with a diffused light color temperature switching scheme comprising a plurality of different diffused light color temperature performances to be activated by the at least one external control device, wherein different paired combinations of the first conduction rate and the second conduction rate respectively for controlling the first electric power delivered to the first LED load and the second electric power delivered to the second LED load for creating different diffused light color temperatures are preprogrammed and executed by the controller for operating a pick and play process according to the at least one external control signal generated by the at least one external control device for selecting a corresponding diffused light color temperature performance in the diffused light color temperature switching scheme;
• wherein when a light intensity level of an ambient light detected by the light sensing control unit is lower than a first predetermined value, the loading and power control unit manages to deliver an average electric power to the light-emitting unit to operate a first illumination mode to perform a first level illumination characterized by a first diffused light intensity and a first diffused light color temperature for a first predetermined time duration;
• wherein when the light intensity level of the ambient light detected by the light sensing control unit is higher than a second predetermined value, the loading and power control unit manages to switch off the light-emitting unit;
• wherein when a motion signal is detected by the motion sensing unit, the loading and power control unit manages to increase the average electric power to the light-emitting unit to operate a second illumination mode to perform a second level illumination characterized by a second diffused light intensity and a second diffused light color temperature for a second predetermined time duration before switching back to the first illumination mode to perform the first level illumination, wherein the second diffused light intensity is always higher than the first diffused light intensity and the second diffused light color temperature is higher than or equal to the first diffused light color temperature;
• wherein the at least one external control device is used for adjusting and setting at least one operating parameter of the multi-level LED security light including but not limited to at least one of the first diffused light color temperature of the first illumination mode, the second diffused light color temperature of the second illumination mode, the first predetermined time duration of the first illumination mode or the second predetermined time duration of the second illumination mode;
• wherein the LEDs of the first LED load and the LEDs of the second LED load are respectively designed with a configuration of in series and/or in parallel connections such that when incorporated with a level setting of a DC power source, an electric current passing through each LED of the first LED load and each LED of the second LED load remains at a level such that a voltage V across each LED complies with an operating constraint of Vth<V<Vmax featuring electrical characteristics of an LED, wherein Vth is a reference value of a threshold voltage required to trigger the LED to start emitting light and Vmax is a reference value of a maximum operating voltage across the LED to avoid a thermal damage or burning out of LED construction;
• wherein when each of the first LED load and the second LED load is configured with a plurality of LEDs electrically connected in series or sets of in parallel connected LEDs electrically connected in series, a working voltage across the first LED load or the second LED load is confined in a domain between a minimum voltage equal to a sum of the threshold voltages of all LEDs electrically connected in series or sets of in parallel connected LEDs electrically connected in series across each of the first LED load and the second LED load and a maximum voltage equal to a sum of the maximum operating voltages of all LEDs electrically connected in series or sets of in parallel connected LEDs electrically connected in series across each of the first LED load and the second LED load;
• and
• wherein when the plurality of LEDs are phosphor based white light LEDs produced by coating at least one phosphor compound on surfaces of LEDs, the reference value of the threshold voltage is estimated at 2.5 volts and the reference value of the maximum operating voltage is estimated at 3.5 volts, wherein the LED has the voltage V across each LED complying with an operating constraint of 2.5 volts<V<3.5 volts and the working voltages imposed on the first LED load and the second LED load respectively represented by VN and VM are confined in domains expressed by NS×2.5 volts<VN<NS×3.5 volts and MS×2.5 volts<VM<MS×3.5 volts, wherein NS and MS are positive integrals denoting respective numbers of in series connected LEDs in the first LED load and the second LED load.

A multi-level LED security light comprising:

• a light-emitting unit configured with at least a first LED load for emitting light with a first color temperature designed with a low color temperature in a range between 1800K and 3000K, and at least a second LED load for emitting light with a second color temperature designed with a high color temperature in a range between 4000K and 6500K;
• a loading and power control unit;
• a light sensing control unit;
• a motion sensing unit;
• a power supply unit;
• and
• an external control unit including at least one external control device outputting at least one external control signal;
• wherein the at least one external control device is used for adjusting and setting at least one operating parameter of the multi-level LED security light including but not limited to at least one of a light intensity, a color temperature or a time duration;
• wherein the loading and power control unit includes a controller and an LED driver circuitry, wherein the LED driver circuitry is electrically connected with a power source of the power supply unit and the light-emitting unit for managing a DC power delivered to the light-emitting unit;
• wherein the LED driver circuitry is configured with a first LED driver and a second LED driver, wherein the first LED driver comprises a first semiconductor switching device electrically connected to the first LED load and the second LED driver comprises a second semiconductor switching device electrically connected to the second LED load, wherein the controller is electrically coupled with the first semiconductor switching device, the second semiconductor switching device, the light sensing control unit, the motion sensing unit and the at least one external control device;
• wherein the controller outputs a first control signal and a second control signal to respectively control a first conduction rate of the first semiconductor switching device and a second conduction rate of the second semiconductor switching device to respectively deliver different electric powers to the first LED load and the second LED load to perform different illumination modes of the multi-level LED security light characterized by different light intensities and different light color temperatures according to signals respectively received from the light sensing control unit, the motion sensing unit and the at least one external control device;
• wherein the first LED load is configured with N pieces of LED and the second LED load is configured with M pieces of LED, wherein M and N are positive integers with a value of M being greater than or equal to a value of N;
• wherein when a nighttime signal is received by the controller defined as a light intensity level of an ambient light detected by the light sensing control unit being lower than a first predetermined value, the loading and power control unit operates to turn on the light-emitting unit, wherein the controller outputs at least the first control signal to control at least the first conduction rate of the first semiconductor switching device to deliver an electric power to the light-emitting unit to operate a first illumination mode to generate a first level illumination with the first color temperature for a first predetermined time duration;
• wherein when a daytime signal is received by the controller defined as the light intensity level of the ambient light detected by the light sensing control unit being higher than a second predetermined value, the loading and power control unit operates to switch off the light-emitting unit;
• wherein when a motion signal is detected by the motion sensing unit, the controller operates to output at least the second control signal to control at least the second conduction rate of the second semiconductor switching device to operate a second illumination mode to generate a second level illumination with the second color temperature for a second predetermined time duration;
• wherein the light intensity of the first level illumination is designed with a level in a range greater than 0% of a maximum light intensity but less than or equal to 50% of the maximum light intensity designed for the light-emitting unit to characterize the first level illumination, wherein the light intensity of the second level illumination is designed with a level in a range greater than 50% of the maximum light intensity but less than or equal to 100% of the maximum light intensity to characterize the second level illumination being higher than the first level illumination;
• wherein the N number LEDs of the first LED load and the M number LEDs of the second LED load are respectively designed with a configuration of in series and/or in parallel connections such that when incorporated with a power level setting of the DC power, an electric current passing through each LED of the first LED load and each LED of the second LED load remains at a level such that a voltage V across each LED complies with an operating constraint of Vth<V<Vmax featuring electrical characteristics of an LED, wherein Vth is a reference value of a threshold voltage required to trigger each LED to start emitting light and Vmax is a reference value of a maximum operating voltage across each LED at which at least one LED construction in said plurality of LEDs is vulnerable to a thermal damage;
• wherein when each of the first LED load and the second LED load is configured with a plurality of LEDs electrically connected in series, or sets of in parallel connected LEDs electrically connected in series, a working voltage imposed on each of the first LED load and the second LED load is confined in a domain between a minimum voltage equal to the sum of the threshold voltages of all LEDs electrically connected in series or sets of in parallel connected LEDs electrically connected in series and a maximum voltage equal to the sum of the maximum operating voltages of all LEDs electrically connected in series or sets of in parallel connected LEDs electrically connected in series;
• and
• wherein when the first LED load and the second LED load are configured with a plurality of white light LEDs produced by coating at least one phosphor compound on surfaces of LEDs, said reference value of said threshold voltage Vth is estimated at 2.5 volts and said reference value of said maximum operating voltage Vmax is estimated at 3.5 volts subject to an operating condition that a temperature of each LED connecting pin is controlled at or below 80 degree centigrade, wherein said voltage V across each LED of said plurality of LEDs complies with an operating constraint of 2.5 volts<V<3.5 volts, wherein the working voltage VN imposed on the first LED load is required to operate in a domain NS×2.5 volts<VN<NS×3.5 volts, and the working voltage VM imposed on the second LED load is required to operate in a domain MS×2.5 volts<VM<MS×3.5 volts, wherein NS and MS respectively denoting the numbers of in series connected LEDs in the first LED load and the second LED load, wherein NS≤N and MS≤M.

A multi-level LED security light comprising:

• a light-emitting unit comprising at least a first LED load configured with N pieces of LEDs and at least a second LED load configured with M pieces of LEDs, wherein M and N are positive integers with a value of M being greater than or equal to a value of N, wherein the first LED load is covered by a first light diffuser and the second LED load is covered by a second light diffuser;
• a loading and power control unit;
• a light sensing control unit;
• a motion sensing unit;
• a power supply unit;
• and
• an external control unit including at least one external control device outputting at least one external control signal;
• wherein the at least one external control device is used for adjusting and setting at least one operating parameter of the multi-level LED security light including but not limited to at least one of a light intensity or a time duration;
• wherein the loading and power control unit includes a controller and an LED driver circuitry, wherein the LED driver circuitry is electrically connected with a power source of the power supply unit and the light-emitting unit for managing a DC power delivered to the light-emitting unit;
• wherein the LED driver circuitry is configured with a first LED driver electrically connected to the first LED load and a second LED driver electrically connected to the second LED load, wherein the first LED driver comprises a first semiconductor switching device electrically connected to the first LED load and the second LED driver comprises a second semiconductor switching device electrically connected to the second LED load;
• wherein the controller is electrically coupled with the first semiconductor switching device, the second semiconductor switching device, the light sensing control unit, the motion sensing unit and the at least one external control device;
• wherein the controller outputs a first control signal and a second control signal to respectively control a first conduction rate of the first semiconductor switching device and a second conduction rate of the second semiconductor switching device to perform different illumination modes of the multi-level LED security light characterized by different light intensities according to signals respectively received from the light sensing control unit, the motion sensing unit and the at least one external control device;
• wherein when a nighttime signal is received by the controller defined as a light intensity level of an ambient light detected by the light sensing control unit being lower than a first predetermined value, the controller outputs at least the first control signal to control at least the first conduction rate of the first semiconductor switching device to operate a first illumination mode to generate a first level illumination for a first predetermined time duration;
• wherein when a daytime signal is received by the controller defined as the light intensity level of the ambient light detected by the light sensing control unit being higher than a second predetermined value, the controller operates to switch off the light-emitting unit;
• wherein when a motion signal is detected by the motion sensing unit, the controller operates to output at least the second control signal to control at least the second conduction rate of the second semiconductor switching device to operate a second illumination mode to generate a second level illumination for a second predetermined time duration;
• wherein the light intensity of the first level illumination is designed with a level in a range greater than 0% of a maximum light intensity but less than or equal to 50% of the maximum light intensity designed for the light-emitting unit to characterize the first level illumination, wherein the light intensity of the second level illumination is designed with a level in a range greater than 50% of the maximum light intensity but less than or equal to 100% of the maximum light intensity to characterize the second level illumination being higher than the first level illumination;
• wherein the N number LEDs of the first LED load and the M number LEDs of the second LED load are respectively designed with a configuration of in series and/or in parallel connections such that when incorporated with a power level setting of the DC power, an electric current passing through each LED of the first LED load and each LED of the second LED load remains at a level such that a voltage V across each LED complies with an operating constraint of Vth<V<Vmax featuring electrical characteristics of an LED, wherein Vth is a reference value of a threshold voltage required to trigger each LED to start emitting light and Vmax is a reference value of a maximum operating voltage across each LED at which at least one LED construction in said plurality of LEDs is vulnerable to a thermal damage;
• wherein when each of the first LED load and the second LED load is configured with a plurality of LEDs electrically connected in series, or sets of in parallel connected LEDs electrically connected in series, a working voltage imposed on each of the first LED load and the second LED load is confined in a domain between a minimum voltage equal to the sum of the threshold voltages of all LEDs electrically connected in series or sets of in parallel connected LEDs electrically connected in series and a maximum voltage equal to the sum of the maximum operating voltages of all LEDs electrically connected in series or sets of in parallel connected LEDs electrically connected in series;
• and
• wherein when the first LED load and the second LED load are configured with a plurality of white light LEDs produced by coating at least one phosphor compound on surfaces of LEDs, said reference value of said threshold voltage Vth is estimated at 2.5 volts and said reference value of said maximum operating voltage Vmax is estimated at 3.5 volts subject to an operating condition that a temperature of each LED connecting pin is controlled at or below 80 degree centigrade, wherein said voltage V across each LED of said plurality of LEDs complies with an operating constraint of 2.5 volts<V<3.5 volts, wherein the working voltage VN imposed on the first LED load is required to operate in a domain NS×2.5 volts<VN<NS×3.5 volts, and the working voltage VM imposed on the second LED load is required to operate in a domain MS×2.5 volts<VM<MS×3.5 volts, wherein NS and MS respectively denoting the numbers of in series connected LEDs in the first LED load and the second LED load, wherein NS≤N and MS≤M.