Patent Publication Number: US-2023160541-A1

Title: Selectable adjustable control for changing color temperature and brightness of an led lamp

Description:
FIELD 
     The present invention relates generally to lighting control, and more particularly to a selectable adjustable control for changing color temperature and brightness of an LED lamp. 
     BACKGROUND 
     Color temperature defines the color appearance of a white light. CCT is defined in degrees Kelvin; a warm light is around 2700 K, moving to neutral white at around 4000 K, and to cool white, at 5000 K or more. Since it is a single number, CCT is simpler to communicate than chromaticity or SPD, leading the lighting industry to accept CCT as a shorthand means of reporting the color appearance of “white” light emitted from electric light sources. 
     Phase-cut dimmers are the most common dimming control and are often referred to as TRIAC dimmers. A phase-cut light dimmer is used to adjust power that is supplied to a lamp in order to adjust the brightness (amount of light) emitted by the lamp. Phase-cut dimmers modify an alternating current (AC) signal that is input to a lighting device by “cutting” or removing some portion of the sinusoidal waveform phase, which reduces the root-mean-square (RMS) voltage of the waveform. An incandescent lamp’s illumination is based on thermal radiation. Therefore, both output brightness and correlated color temperature (CCT) of an incandescent lamp’s emitted light is a positive function of the lamp’s input power, in that both brightness and CCT increase with increasing input power and decreases with decreasing power. 
     Light Emitting Diode (LED) technology is being used in more and more lighting applications. LED technology is highly energy efficient, and has the potential to fundamentally change the future of lighting. Typical LED-based products use at least 75% less energy, and last 25 times longer, than incandescent lighting. Since, lighting plays an important role in the design and usability of interior spaces, it is desirable to have improvements in LED lighting control. 
     SUMMARY 
     In one embodiment, there is provided an apparatus comprising: an LED (light emitting diode) driver, the driver configured to provide power to: a first LED that is configured to emit a first white light of a first correlated color temperature (CCT); a second LED that is configured to emit a second white light of a second CCT that is lower than the first CCT, for the first white light to mix with the second white light to yield a combined white light having a combined-light CCT with a combined-light brightness; receive a user-adjustable DC input voltage Vin from a selectable control device, wherein the selectable control device comprises a plurality of CCT selection values; and distribute supply power to the first LED and second LED. 
     In another embodiment, an apparatus comprising: a microcontroller; an LED (light emitting diode) driver; a controller configured to provide power to: a first LED that is configured to emit a first white light of a first correlated color temperature (CCT); a second LED that is configured to emit a second white light of a second CCT that is lower than the first CCT, for the first white light to mix with the second white light to yield a combined white light having a combined-light CCT with a combined-light brightness; wherein the microcontroller is configured to receive a user-adjustable DC input voltage Vin from a selectable control device, wherein the selectable control device comprises a plurality of CCT selection values; and wherein the driver is configured to distribute supply power to the first and second light-emitting devices according to a power-distribution scheme based on a configuration of the selectable control device. 
     In yet another embodiment, there is provided a lightbulb comprising: a first LED (light emitting diode); a second LED; an LED driver, the driver configured to: provide power to: the first LED, wherein the first LED is configured to emit a first white light of a first correlated color temperature (CCT); and the second LED, wherein the second LED is configured to emit a second white light of a second CCT that is lower than the first CCT, enabling the first white light to mix with the second white light to yield a combined white light having a combined-light CCT with a combined-light brightness; receive a user-adjustable DC input voltage Vin from a selectable control device, wherein the selectable control device comprises a plurality of CCT selection values; and distribute supply power to the first and second light-emitting devices according to a power-distribution scheme based on a configuration of the selectable control device; and a base configured and disposed to mechanically and electrically engage with a light socket. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying figures (FIGs). The figures are intended to be illustrative, not limiting. 
       Certain elements in some of the figures may be omitted, or illustrated not-to-scale, for illustrative clarity. The cross-sectional views may be in the form of “slices”, or “near-sighted” cross-sectional views, omitting certain background lines which would otherwise be visible in a “true” cross-sectional view, for illustrative clarity. 
       Often, similar elements may be referred to by similar numbers in various figures (FIGs) of the drawing, in which case typically the last two significant digits may be the same, the most significant digit being the number of the drawing figure (FIG). Furthermore, for clarity, some reference numbers may be omitted in certain drawings. 
         FIG.  1    is a diagram of an apparatus with a selectable control device in accordance with embodiments of the present invention. 
         FIG.  2    is a diagram of an apparatus in accordance with additional embodiments of the present invention with an integrated selectable control device. 
         FIG.  3    is a diagram of an apparatus with a selectable control device in series configuration in accordance with additional embodiments of the present invention. 
         FIG.  4    is a diagram of an apparatus in accordance with a microcontroller unit and integrated selectable control device in accordance with additional embodiments of the present invention. 
         FIG.  5    is a diagram of an apparatus in accordance with a microcontroller unit and external selectable control device in accordance with additional embodiments of the present invention. 
         FIG.  6    shows a user interface of a selectable control device in accordance with embodiments of the present invention. 
         FIG.  7    is a side cutaway view of an indoor downlight device utilizing embodiments of the present invention. 
         FIG.  8    is a perspective view of the indoor downlight device of  FIG.  7   . 
         FIG.  9    is a side view of an embodiment utilizing a BR-type lightbulb. 
         FIG.  10    is a side view of an embodiment utilizing an A-type lightbulb. 
         FIG.  11    is a side view of an embodiment utilizing a PAR-type lightbulb. 
         FIGS.  12  -  15    are example voltage traces of input supply power that the selectable control device might output to a controller. 
         FIG.  16    shows a schematic representation of a selectable control device in accordance with disclosed embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed embodiments provide techniques and devices for changing the color temperature and/or brightness of an LED lamp utilizing a selectable control device. The selectable control device may include one or more buttons, sliders, and/or rotary knobs. The buttons, sliders, and/or rotary knobs may be coupled to resistors, including variable resistors (potentiometers), that utilize resistance shunting. In embodiments, the shunt resistance varies under different dialing conditions (configuration of the selectable control device), so as to obtain different current ratios and achieve the purpose of mixing different color temperatures. 
     Embodiments may further include a constant power/color temperature (CPCT) mode. This may be achieved by detecting the phase angle signal of TRIAC dimming, corresponding to different phase angles, different operating modes are possible. In a first mode, the power is constant while the color temperature changes as a result of configuration of the selectable control device. In a second mode, both the power and the color temperature change as a result of configuration of the selectable control device. In a third mode, the power changes and the color temperature remains constant as a result of the configuration of the selectable control device. In some embodiments, the selectable control device  114  may further include an integrated dimmer with a slider control, rotary knob control, or other suitable adjustment mechanism. Other embodiments may utilize an external dimmer. 
       FIG.  1    shows an example circuit  100  in accordance with embodiments of the present invention configured for selectable control. Circuit  100  includes LED driver  102 , which includes a DC (direct current) output module  112 . The driver  102  includes AC/DC converters, voltage convertors, rectifiers, and/or other components to produce a low-voltage signal for powering light-emitting devices  122 , and  124 . In embodiments, light-emitting devices  122  and  124  are LEDs. In embodiments, light-emitting device  122  has a first CCT value and light-emitting device  124  has a second CCT value. By combining light from light-emitting device  122  and light-emitting device  124 , a combined white light with various CCT values can be produced. 
     The LED driver  102  comprises an input  104  and an input  106 . Input  104  may be an L (line, or hot) signal, and input  106  may be a neutral (N) signal, as provided by an AC power source  143 . 
     A selectable control device  114  is configured and disposed to control the DC output module  112  of the driver  102 . The selectable control device  114  may include one or more switches, sliders, buttons, knobs, and/or dials for controlling output to the light-emitting devices  122  and  124 . 
     In embodiments, the selectable control device is used to select the mode and can select a specific color temperature such as 5000 K, 4000 K, and/or 3000 K. Embodiments can also include a constant power/color temperature (CPCT) mode, and cooperate with a dimmer to achieve the function of not only constant power color temperature, but also light adjustment. In embodiments, the selectable control device is installed on the lamp (lightbulb) body, which can facilitate the realization of dialing (configuration of the selectable control device). In embodiments, in a first range, power and CCT are constant, in a second range, power is constant and CCT varies, in a third range, both power and CCT vary, and in a fourth range, the power varies and the CCT is constant. In embodiments, the selectable control device is a rotary knob having a range from zero to 180 degrees. In some embodiments, the rotary knob is configured such that between zero to 20 degrees, power and CCT are constant. In a range from 20 degrees to 40 degrees, power is constant, and CCT varies from 5000 K to 3000 K. In a range from 40 degrees to 60 degrees, power and CCT vary, and in a range from 60 degrees to 180 degrees, power varies, and CCT is constant at 2000 K. Other ranges and CCT values are possible in disclosed embodiments. 
       FIG.  2    shows an example circuit  200  in accordance with embodiments of the present invention configured for a selectable control using an integrated selectable control device. Circuit  200  includes LED driver  202 , which includes a DC (direct current) output module  112  similar to as described for  FIG.  1   . The driver  202  includes AC/DC converters, voltage convertors, rectifiers, and/or other components to produce a low-voltage signal for powering light-emitting devices  122 , and  124 . In embodiments, light-emitting devices  122  and  124  are LEDs. In embodiments, light-emitting device  122  has a first CCT value and light-emitting device  124  has a second CCT value. By combining light from light-emitting device  122  and light-emitting device  124 , a combined white light with various CCT values can be produced. 
     The LED driver  202  comprises an input  104  and an input  106 . Input  104  may be an L (line, or hot) signal, and input  106  may be a neutral (N) signal, as provided by an AC power source  143 . A selectable control device  214  is configured and disposed to control the DC output module  112  of the driver  202 . The selectable control device  214  may include one or more switches, sliders, buttons, knobs, and/or dials for controlling output to the light-emitting devices  122  and  124 . 
     In embodiments, the selectable control device is used to select the mode and can select a specific color temperature such as 5000 K, 4000 K, and/or 3000 K. Embodiments can also include a constant power/color temperature (CPCT) mode, and cooperate with a dimmer to achieve the function of not only constant power color temperature, but also light adjustment. In embodiments, the selectable control device is installed on the lamp (lightbulb) body, which can facilitate the realization of dialing (configuration of the selectable control device). The lightbulb body can include an A-type form factor, BR-type form factor, PAR-type form factor, or other suitable form factor. The lamp body can include a downlight device, or other suitable lighting device that includes an enclosure, and connection terminals such as a screw terminal (Edison screw), prongs, bayonet cap base, or other interface to connect to a lighting system. In embodiments, the screw terminal of the base is configured and disposed to mechanically and electrically engage with a light socket. 
       FIG.  3    shows an example circuit  300  in accordance with embodiments of the present invention configured for a selectable control device in series configuration in accordance with additional embodiments of the present invention. Circuit  300  includes LED driver  302 , which includes a DC (direct current) output module  112  similar to as described for  FIG.  1   . The driver  302  includes AC/DC converters, voltage convertors, rectifiers, and/or other components to produce a low-voltage signal for powering light-emitting devices  122  and  124   
     The LED driver  302  comprises an input  104  and an input  106 . Input  104  may be an L (line, or hot) signal, and input  106  may be a neutral (N) signal, as provided by an AC power source  143 . 
     A selectable control device  314  is configured and disposed to control the DC output module  112  of the driver  302 . The selectable control device  314  may include one or more switches, sliders, buttons, knobs, and/or dials for controlling output to the light-emitting devices  122  and  124 . In this configuration, the selectable control device  314  is configured in electrical series with the light-emitting devices  122  and  124 . In embodiments, selectable control device  314  may be similar to selectable control device  114  of  FIG.  1   , with possible variations in connection terminals to support a series connection to the light-emitting devices. In embodiments, the selectable control device is configured and disposed to be in series with the first LED and second LED. 
       FIG.  4    shows an example circuit  400  in accordance with embodiments of the present invention including a microcontroller unit (MCU)  408  and integrated selectable control device  414  in accordance with additional embodiments of the present invention. Circuit  400  includes LED driver  402 , which includes a DC (direct current) output module  412 . DC output module  412  may be similar to DC output module  112  described for  FIG.  1   , but may be further configured to receive a PWM input from microcontroller  408  to determine output voltages/currents provided to the light-emitting devices  122  and  124 . The driver  402  includes AC/DC converters, voltage convertors, rectifiers, and/or other components to produce a low-voltage signal for powering light-emitting devices  122 , and  124 . In embodiments, light-emitting devices  122  and  124  are LEDs. In embodiments, light-emitting device  122  has a first CCT value and light-emitting device  124  has a second CCT value. By combining light from light-emitting device  122  and light-emitting device  124 , a combined white light with various CCT values can be produced. In embodiments, the microcontroller  408  is configured such that the signal provided to the driver comprises a pulse-width modulated (PWM) signal. 
     The selectable control device  414  is configured and disposed to control the DC output module  412  of the driver  402 . The selectable control device  414  may include one or more switches, sliders, buttons, knobs, and/or dials for controlling output to the light-emitting devices  122  and  124 . In some embodiments, the selectable control device can be a wireless receiving module. In this configuration, the selectable control device  314  is configured to control a signal that is configured as an input to microcontroller  408 . The microcontroller includes a processing unit that executes instructions stored in a built-in non-transitory computer-readable medium. The instructions, when executed by the microcontroller, cause the microcontroller to adjust a PWM output  409  in response to a voltage change in input  407 , caused by resistance changes that are due to configuration of the selectable control device  414 . In the embodiment shown in  FIG.  4   , the selectable control device  414  is integrated into the LED driver  402 . 
       FIG.  5    shows an example circuit  500  in accordance with embodiments of the present invention including a microcontroller unit (MCU)  408  and external selectable control device  514  in accordance with additional embodiments of the present invention. 
     Circuit  500  includes LED driver  502 , which includes a DC (direct current) output module  512 . DC output module  512  may be similar to DC output module  112  described for  FIG.  1   , but may be further configured to receive a PWM input from microcontroller  408  to determine output voltages/currents provided to the light-emitting devices  122  and  124 . The driver  502  includes AC/DC converters, voltage convertors, rectifiers, and/or other components to produce a low-voltage signal for powering light-emitting devices  122 , and  124 . In embodiments, light-emitting devices  122  and  124  are LEDs. In embodiments, light-emitting device  122  has a first CCT value and light-emitting device  124  has a second CCT value. By combining light from light-emitting device  122  and light-emitting device  124 , a combined white light with various CCT values can be produced. In embodiments, the microcontroller  408  is configured such that the signal provided to the driver comprises a pulse-width modulated (PWM) signal. 
     The selectable control device  514  is configured and disposed to control the DC output module  512  of the driver  502 . The selectable control device  514  may include one or more switches, sliders, buttons, knobs, and/or dials for controlling output to the light-emitting devices  122  and  124 . In this configuration, the selectable control device  314  is configured to control a signal that is configured as an input to microcontroller  408 . The microcontroller includes a processing unit that executes instructions stored in a built-in non-transitory computer-readable medium. The instructions, when executed by the microcontroller, cause the microcontroller to adjust a PWM output  409  in response to a voltage change in input  407 , caused by resistance changes that are due to configuration of the selectable control device  514 . In the embodiment shown in  FIG.  5   , the selectable control device  514  is external to the LED driver  502 . 
     The LED driver  102  comprises an input  104  and an input  106 . Input  104  may be an L (line, or hot) signal, and input  106  may be a neutral (N) signal, as provided by an AC power source  143 . In this embodiment, an external dimmer  547  is shown. The external dimmer  547  may be mounted on a wall, or other suitable location for controlling the brightness of the light-emitting devices  122 , and  124 . The other embodiments shown in  FIGS.  1 - 4    may also utilize an external dimmer. 
       FIG.  6    shows a user interface of a selectable control device  600  in accordance with embodiments of the present invention. In embodiments, the selectable control device  600  comprises a plurality of buttons disposed within a housing  635 , the buttons indicated as  622 - 634 . Each button may configure a different resistance, resulting in a different voltage input to an LED driver and/or microcontroller unit (MCU). Button  622  may configure an infinite (or sufficiently high) resistance, corresponding to an “off” configuration. Button  624  may correspond to a first resistance, which corresponds to a CCT value of 2700 K. Button  626  may correspond to a second resistance, which corresponds to a CCT value of 3000 K. Button  628  may correspond to a third resistance, which corresponds to a CCT value of 3500 K. Button  630  may correspond to a fourth resistance, which corresponds to a CCT value of 4000 K. Button  632  may correspond to a fifth resistance, which corresponds to a CCT value of 5000 K. Other resistance values may be used to allow selection of other CCT values. Additionally, one or more sliders, knobs, dials, switches, buttons, or other suitable controls may be included to allow selection of one or more resistance values that correspond to a CCT value for a combined white light from multiple light-emitting devices. Button  634  may correspond to a sixth resistance, which corresponds to a CPCT mode of operation. 
     In the CPCT mode of operation, the selectable control device  600  may operate with a circuit that includes a TRIAC. The TRIAC inputs electrical supply power (electrical current) in the form of an AC (alternating current) input supply voltage, which can include a mains (wall power) 120 V 60 Hz electrical supply. 
     The TRIAC inputs an alternating electrical current at its input terminal. When the TRIAC is triggered by a positive or negative trigger voltage applied to the TRIAC’s gate, the TRIAC starts to conduct the input current to the TRIAC’s output. The TRIAC continues to conduct even after the trigger voltage ceases. The conduction ceases when the input current drops below a holding current level which can be substantially near zero current. Thus, within a half-cycle in either direction of current, the TRIAC is in a conducting state from the time it receives the gate trigger until the end of the half-cycle. Within a half-cycle, the earlier the controller applies the trigger, the greater the conduction-time during that half-cycle, and therefore the greater the current and power applied to the lamp, and therefore the greater the lamp’s brightness. The TRIAC dimmer includes a TRIAC controller that controls the power applied to the lamp by controlling the time at which the trigger is applied. 
     In embodiments, the selectable control device includes five CCT settings. In particular embodiments, the five CCT settings include: a 2700 K setting; a 3000 K setting; a 3500 K setting; a 4000 K setting; and a 5000 K setting. In embodiments, the selectable control device may further include a constant power color temperature (CPCT) setting. 
       FIG.  7    is a side cutaway view of an indoor downlight device  700  utilizing embodiments of the present invention. The device  700  has a lamp housing  762 . The lamp housing  762  has a top defined by a horizontal flat top surface  737 . The housing  762  has a side surface  764  that includes a substantially-cylindrical upper section and a frustoconical (flared) lower section. The lamp housing  762  has a bottom  765  with a round bottom opening  766 . The bottom opening  766  opens to a light cavity  767  in the housing  762 . In the light cavity  767 , light-emitting devices  732 - 735  are mounted to an internal surface  768  in the housing  762 . The light-emitting devices  732 - 735  emit light that exits the cavity  767  through the bottom opening  766  and is directed downward. The bottom opening  766  is surrounded and bounded by an annular flange  769  that extends radially outward from the bottom opening  6 . The top surface  737 , the side surface  764 , the bottom opening  766 , and the flange  769  are components of the housing  762 . 
     The device  700  in this example includes selectable control device  714  for adjusting characteristics (e.g., brightness and CCT) of combined white light emitted by the downlight device  700 . The selectable control device  714  may be similar to the selectable control device  600  shown in  FIG.  6   . The selectable control device  714  may include housing  735  mounted on a top surface  737  of the downlight device  700 . The selectable control device  714  may include a plurality of buttons  722 ,  724 ,  726 ,  728 ,  230 ,  732 , and  734 , which are similar to buttons  622  -  634  of  FIG.  6   . Alternatively, or additionally, the selectable control device  714  may include one or more slides, knobs, dials, or other suitable control mechanism. The selectable control device  714  in this example is user adjustable, in that it can be adjusted manually (i.e., by a person). 
     In embodiments, the selectable control device  714  can include a slider, and the positional movement of the slider is linear. In embodiments, the selectable control device  714  can include a rotatable knob and the positional movement of the knob is rotational. The knob might project from the enclosure  735  and be moved rotationally (i.e., turned) by the user’s fingers along a range of angular positions (angular positional range) from a first end of an angular positional full-scale range (e.g., fully counterclockwise) to a second end of the angular positional full-scale range (e.g., fully clockwise), and vice versa. These embodiments may also include the buttons as depicted in  FIG.  7     
     The indoor downlight device  700  further includes an LED driver  702 . Driver  702  may be similar to one of the drivers  102 ,  202 ,  302 ,  402 , and/or  502 , previously described. The driver  702  includes AC/DC converters, voltage convertors, rectifiers, and/or other components to produce a low-voltage signal for powering light-emitting devices  732 ,  733 ,  734 , and  735 . In embodiments, light-emitting devices  732  -  735  are LED devices. In embodiments, one or more of the devices  732  -  735  emits light of a different CCT value than the others. In some embodiments, device  732  and  733  emit light of a first CCT value, and device  734  and device  735  emit light of a second CCT value. The light-emitting devices  732  -  735  are in positions relative to each other such that the first white light of the first CCT value will mix with the second white light of the second CCT value to yield a combined white light that has a combined CCT with a combined brightness. While four light-emitting devices are shown in  FIG.  7   , embodiments may have more or fewer light-emitting devices. 
       FIG.  8    is a perspective view of the indoor downlight device  700  of  FIG.  7   . In this view, the controls of the selectable control device  714  can be seen on the top surface  737 . In such embodiments, the selectable control device  714  may be set to a desired setting prior to installation in a ceiling of a room. In addition to being included in an indoor downlight device, embodiments may also be included in lamps having a lightbulb form factor. 
       FIG.  9    is a side view of an embodiment utilizing a BR-type lightbulb  900 . In this embodiment, the lightbulb may include multiple LEDs housed within enclosure  901 . A selectable control device  914  may be disposed on the enclosure  901 , near the base  949 . The base  949  may include a screw terminal or other suitable connector to receive power. In this way, the lightbulb  900  can be configured for a desired CCT value and/or constant power/color temperature (CPCT) mode to be used with an external dimmer. Thus, in embodiments, the lightbulb comprises a BR-type form factor. 
       FIG.  10    is a side view of an embodiment utilizing an A-type lightbulb  1000 . In this embodiment, the lightbulb may include multiple LEDs housed within enclosure  1001 . A selectable control device  1014  may be disposed on the enclosure  1001 , near the base  1049 . The base  1049  may include a screw terminal or other suitable connector to receive power. In this way, the lightbulb  1000  can be configured for a desired CCT value and/or constant power/color temperature (CPCT) mode to be used with an external dimmer. Thus, in embodiments, the lightbulb comprises an A-type form factor. 
       FIG.  11    is a side view of an embodiment utilizing a PAR-type lightbulb  1100 . In this embodiment, the lightbulb may include multiple LEDs housed within enclosure  1101 . A selectable control device  1114  may be disposed on the enclosure  1101 , near the base  1049 . The base  1149  may include a screw terminal or other suitable connector to receive power. In this way, the lightbulb  1100  can be configured for a desired CCT value and/or constant power/color temperature (CPCT) mode to be used with an external dimmer. Thus, in embodiments, the lightbulb comprises a PAR-type form factor. 
       FIG.  12    shows a graph of voltage versus time of an example of a single cycle of mains supply power. The cycle corresponds to 360 degrees (deg) and lasts 1/60 second (sec). Accordingly, each half cycle of input voltage/current corresponds to 180 deg and has a duration of 1/120 sec. 
       FIGS.  13  -  15    illustrate examples of different voltage traces of supply power that a dimmer is configured to output. The dimmer outputs only a segment of each half-cycle of the AC mains supply. Each output segment ends at, or substantially at, the end of the half-cycle (labelled “Turn-Off” in the figures) when the TRIAC turns off, which corresponds to 180 deg. Each output segment starts at a point in time (labelled “Turn-On” in the figures) when the TRIAC turns on. The Turn-On point is located at a point within the half-cycle, correlating to a cycle-angle between 0 deg and 180 deg, that is selected (controlled) by the user through the dimmer. 
       FIG.  13    shows an example in which a dimmer is at the first end of the operational full-scale range. This causes the TRIAC’s Turn-On point, and thus the output segment’s starting point, to be about 0 deg. So, the output segment’s duration is about 180 deg, which corresponds to 100% of the half-cycle and about 1/120 sec. 
       FIG.  14    shows an example in which the dimmer is at an intermediate position about 80% of the way from the second end of the full-scale range to the first end of the full-scale range. This causes the TRIAC’s Turn-On point to be about 20% of the way through the 180 deg half-cycle. So, the TRIAC is on for a duration of only 80% of the 180 deg half-cycle, corresponding to 1/150 sec (which is 80% of the 1/120 sec half-cycle). 
       FIG.  15    shows an example in which the dimmer is at the second end of the full-scale range. This causes the TRIAC’s Turn-On point to be at the end of the half-cycle which coincides with the Turn-Off point, so that the output segment’s duration is about 0 deg and about 0 sec. 
     As shown in  FIGS.  13  -  15   , the output segment’s duration (in terms of time in seconds or cycle-angle in degrees) is a function of the user-interface component’s value. And the user-interface component’s value corresponds to the component’s position or number-of-bars-lit or displayed number. As the user-interface component’s position progresses from the first end, through the full-scale range, to the second end, the output supply’s segment duration progresses from 180 deg down to 0 deg and from 1/120 sec down to 0 sec. Conversely, as the user-interface component’s position progresses from the second end, through the full-scale range, to the first end, the dimmer’s supply’s segment duration progresses from 0 deg up to 180 deg and from 0 sec up to 1/120 sec. In this example, the segment duration is continuously-variable, and the position of the dimmer is continuously-variable, for the segment duration to be a smoothly-continuous monotonic function of the dimmer configuration. 
       FIG.  16    shows a schematic representation  1600  of a selectable control device  1610  in accordance with disclosed embodiments. Selectable control device  1610  includes variable resistance selection device  1620 . In embodiments, variable resistance selection device  1620  can be a potentiometer, slider, rotary selection switch, and/or other suitable device. The selectable control device  1610  is coupled to a first bank of LEDs  1630  and a second bank of LEDs  1640  via a plurality of resistors, diodes, and/or other passive and/or active components. In embodiments, the first bank of LEDs  1630  has a first CCT value and the second bank of LEDs  1640  has a second CCT value. In embodiments, the first CCT value is 2700 K and the second CCT value is 5000 K. Other CCT values are possible in disclosed embodiments. Light from the first bank of LEDs  1630  and the second bank of LEDs  1640  can combine to create a combined light with a combined-light CCT value. 
     As can now be appreciated, disclosed embodiments enable color temperature and dimming functions on a dimming light of an existing lamp. This allows a user to easily obtain the color temperature and dimming brightness lighting experience. At the same time, due to the traditional TRIAC dimming interface, it can be compatible with the current dimmers on the market to the greatest extent, allowing for flexibility of use and ease of marketing. 
     Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, certain equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, circuits, etc.) the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiments of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several embodiments, such feature may be combined with one or more features of the other embodiments as may be desired and advantageous for any given or particular application.