The purpose of the present invention is to provide an LED driving circuit with which it is possible to easily manage the color temperature by adjusting light. An LED driving circuit, characterized in having: a first LED group in which a plurality of first LEDs are serially connected, the first LED group contributing to emission of light having a first color temperature; a second LED group in which a plurality of second LEDs are serially connected, the second LED group contributing to emission of light having a second color temperature; a third LED group in which a plurality of second LEDs are serially connected, the second LED group contributing to emission of light having the second color temperature; and a control unit for switching, in response to an increase in a rectified output voltage, from illumination of only the first LED group to illumination of only the second LED group and then from illumination of only the second LED group to illumination of the second LED group and the third LED group, the number of first LEDs included in the first LED group being less than the number of second LEDs included in the second LED group.

Provided is an LED drive circuit whereby the light emission color is easily changed when dimming by adjusting the current that drives the LED. The LED drive circuit has: a variable constant current source; a first LED row having a plurality of LEDs connected in series and emitting light in a first light emission color; a second LED row having a plurality of LEDs connected in series and emitting light in a second light emission color; and a current limiting circuit including a current detection element and a switch element. The LED drive circuit is characterized by: the threshold voltage for the first LED row being larger than the threshold voltage for the second LED row; the first LED row and the second LED row being connected in parallel to the variable constant current source; and the current limiting circuit limiting the current flowing to the second LED row, on the basis of the current flowing to the current detection element via the first LED row.

An LED filament comprising a plurality of LED filament units, each of the plurality of LED filament units includes a LED chip with an upper surface and a lower surface opposite to the upper surface of the LED chip, and a light conversion layer comprising a top layer and a base layer, and the base layer comprises an upper surface and a lower surface opposite to the upper surface of the base layer, where the top layer with an upper surface and a lower surface opposite to the upper surface of the top layer is disposed on at least two sides of each of the LED chips, the lower surface of each of the LED chips is close to the upper surface of the base layer, and the upper surface of the top layer is away from each of the LED chips.

A method (400) of controlling a plurality of lighting units (112, 114) of a lighting system (100) is disclosed. The method (400) comprises receiving (402) a first input indicative of that a light scene of a first type has been activated, receiving (404) a second input indicative of a dimming command for the plurality of lighting units (112, 114), obtaining (406) data indicative of functions of the plurality of lighting units (112, 114), wherein a first lighting unit (112) has a first function to provide ambient lighting and a second lighting unit (114) has a second function to provide functional lighting, and, if the light scene of the first type is active, controlling (408) the first lighting unit (112) based on the dimming command according to a first dimming profile, wherein the first dimming profile for the first lighting unit (112) is based on the first function, and simultaneously controlling (408) the second lighting unit (114) based on the dimming command according to a second dimming profile different from the first profile, wherein the second dimming profile for the second lighting unit (114) is based on the second function.

A method (400) of controlling a plurality of lighting units (112, 114) of a lighting system (100) is disclosed. The method (400) comprises receiving (402) a first input indicative of that a light scene of a first type has been activated, receiving (404) a second input indicative of a dimming command for the plurality of lighting units (112, 114), obtaining (406) data indicative of functions of the plurality of lighting units (112, 114), wherein a first lighting unit (112) has a first function to provide ambient lighting and a second lighting unit (114) has a second function to provide functional lighting, and, if the light scene of the first type is active, controlling (408) the first lighting unit (112) based on the dimming command according to a first dimming profile, wherein the first dimming profile for the first lighting unit (112) is based on the first function, and simultaneously controlling (408) the second lighting unit (114) based on the dimming command according to a second dimming profile different from the first profile, wherein the second dimming profile for the second lighting unit (114) is based on the second function.

A linear drive circuit and an LED light including the same. The linear drive circuit includes an AC-DC module, an LED module, a CCT and brightness control module, and a drive control module. The AC-DC module is connected to the LED module through a first unidirectional conductive element, and is configured to obtain an AC input voltage control signal, and convert the AC input voltage control signal into a corresponding DC voltage control signal. The CCT and brightness control module is connected to the LED module, and is configured to obtain a corresponding CCT control signal or a brightness control signal according to the DC voltage control signal, so as to adjust the CCT of each LED string in the LED module. The drive control module is configured to receive the brightness control signal, thereby adjusting the brightness of the LED module.

The disclosed invention is embodied in an improved LED-based lighting fixture for projecting a beam of light having a substantially uniform intensity, rotationally, and a selectable, substantially uniform chromaticity. The lighting fixture includes (1) a concave reflector having circumferential facets, a focal region, an aperture, and a central opening; and (2) a light source assembly including two or more groups of LEDs mounted at the forward end of an elongated, thermally conductive support. The light source assembly is mounted relative to the reflector with the elongated support's longitudinal axis aligned with the reflector's longitudinal axis and with the groups of LEDs located at or near the reflector's focal region. Each of the two or more groups of LEDs includes a plurality of LEDs arranged in two or more columns substantially parallel with the light source axis, with each column including only LEDs configured to emit light in a limited range of the visible spectrum and having the same distinct dominant wavelength, and with each group of LEDs including LEDs configured to emit light in two or more dominant wavelengths. The two or more groups of LEDs are configured to cooperate with the faceted concave reflector to project a beam of light having a selectable, substantially uniform chromaticity.

The disclosed invention is embodied in an improved LED-based lighting fixture for projecting a beam of light having a substantially uniform intensity, rotationally, and a selectable, substantially uniform chromaticity. The lighting fixture includes (1) a concave reflector having circumferential facets, a focal region, an aperture, and a central opening; and (2) a light source assembly including two or more groups of LEDs mounted at the forward end of an elongated, thermally conductive support. The light source assembly is mounted relative to the reflector with the elongated support's longitudinal axis aligned with the reflector's longitudinal axis and with the groups of LEDs located at or near the reflector's focal region. Each of the two or more groups of LEDs includes a plurality of LEDs arranged in two or more columns substantially parallel with the light source axis, with each column including only LEDs configured to emit light in a limited range of the visible spectrum and having the same distinct dominant wavelength, and with each group of LEDs including LEDs configured to emit light in two or more dominant wavelengths. The two or more groups of LEDs are configured to cooperate with the faceted concave reflector to project a beam of light having a selectable, substantially uniform chromaticity.

The present invention relates to a lamp (1), comprising a lamp base (3), a semi-reflective envelope (2), at least one first solid state light source filament (4a-d) arranged inside the semi-reflective envelope (2), and a second solid state light source (5) arranged inside the semi-reflective envelope (2), wherein the reflectivity of the semi-reflective envelope (2) is in the range from 30% to 70% for light emitted by the at least one first solid state light source filament (4a-d) and the second solid state light source (5), wherein the at least one first solid state light source filament (4a-d) is arranged at a first distance lower than 7 millimeters from the semi-reflective envelope (2), and wherein the second solid state light source (5) is arranged at second distance higher than 15 millimeters from the semi-reflective envelope (2).

A light fixture is configured to produce an output via a driver circuit to drive an array of LED light sources. Controlling the light fixture includes receiving a first light intensity value related to a light intensity value for the array of LED light sources, determining a first dimming curve based on the first light intensity value and a color temperature value to determine a first value, receiving a second light intensity value related to a light intensity value for the array of LED light sources at which the color temperature value for the output of the light fixture is achieved, wherein the second light intensity value is different than the first light intensity value, determining a second dimming curve based on the second light intensity value and the color temperature value to determine a second value, wherein the second dimming curve is different than the first dimming curve.