Abstract: A method of operating a color-temperature-tunable device is described. The method drives a first light emitting diode (LED) chip with a first driving current from a first power source. The first LED chip is configured to emit a first light having a first peak wavelength. The method also drives a second LED chip with a second driving current from a second power source. The second LED chip is configured to emit a second light having a second peak wavelength. The method further maintains a total driving current, which includes the first driving current and the second driving current, approximately constant. The second peak wavelength is different from the first peak wavelength.

Abstract: A method of operating a color-temperature-tunable device is described. The method drives a first light emitting diode (LED) chip with a first driving current from a first power source. The first LED chip is configured to emit a first light having a first peak wavelength. The method also drives a second LED chip with a second driving current from a second power source. The second LED chip is configured to emit a second light having a second peak wavelength. The method further maintains a total driving current, which includes the first driving current and the second driving current, approximately constant. The second peak wavelength is different from the first peak wavelength.

Abstract: A method of operating a color-temperature-tunable device is described. The method drives a first light emitting diode (LED) chip with a first driving current from a first power source. The first LED chip is configured to emit a first light having a first peak wavelength. The method also drives a second LED chip with a second driving current from a second power source. The second LED chip is configured to emit a second light having a second peak wavelength. The method further maintains a total driving current, which includes the first driving current and the second driving current, approximately constant. The second peak wavelength is different from the first peak wavelength.

Abstract: A color-temperature-tunable device comprises a first light emitting diode (LED) chip group comprising at least one first blue LED chip that emits a first light having a first peak wavelength, a second LED chip group comprising at least one second blue LED chip that emits a second light having a second peak wavelength different from the first peak wavelength, and a wavelength converting layer above at least a portion of the first LED chip group and a portion of the second LED chip group. The first LED chip group and the second LED chip group are driven by a first driving current and a second driving current, respectively.

Abstract: A color-temperature-tunable device comprises a first light emitting diode (LED) chip group comprising at least one first blue LED chip that emits a first light having a first peak wavelength, a second LED chip group comprising at least one second blue LED chip that emits a second light having a second peak wavelength different from the first peak wavelength, and a wavelength converting layer above at least a portion of the first LED chip group and a portion of the second LED chip group. The first LED chip group and the second LED chip group are driven by a first driving current and a second driving current, respectively.

Abstract: A color-temperature-tunable device comprises a first light emitting diode (LED) chip group comprising at least one first blue LED chip that emits a first light having a first peak wavelength, a second LED chip group comprising at least one second blue LED chip that emits a second light having a second peak wavelength different from the first peak wavelength, and a wavelength converting layer above at least a portion of the first LED chip group and a portion of the second LED chip group. The first LED chip group and the second LED chip group are driven by a first driving current and a second driving current, respectively.

Abstract: A method of determining the number of light sources is adapted to determine the number of each kind of light sources of an illumination device. The method includes following steps. A photon number of a single light source of each kind of the light sources is calculated. Next, a number ratio of each kind of the light sources is determined according to a power ratio of each kind of the light sources and the photon number of a single light source of each kind of the light sources. Finally, the number of each kind of the light sources is determined according to the number ratio and a total number of the light sources of the illumination device.

Abstract: A color-temperature-tunable device comprises a first light emitting diode (LED) chip group comprising at least one first blue LED chip that emits a first light having a first peak wavelength, a second LED chip group comprising at least one second blue LED chip that emits a second light having a second peak wavelength different from the first peak wavelength, and a wavelength converting layer above at least a portion of the first LED chip group and a portion of the second LED chip group. The first LED chip group and the second LED chip group are driven by a first driving current and a second driving current, respectively.

Abstract: A method of determining the number of light sources is adapted to determine the number of each kind of light sources of an illumination device. The method includes following steps. A photon number of a single light source of each kind of the light sources is calculated. Next, a number ratio of each kind of the light sources is determined according to a power ratio of each kind of the light sources and the photon number of a single light source of each kind of the light sources. Finally, the number of each kind of the light sources is determined according to the number ratio and a total number of the light sources of the illumination device.