Apparatus and method for adjusting the color temperature of white semiconduct or light emitters

A method of adjusting the color temperature of light output from an LED arrangement, the method comprising:

• supplying a first drive current to at least one white LED such that a white light is output at a first intensity;
• supplying a second drive current to at least one colored LED such that a colored light is output at a second intensity;
• combining the white light with the colored light to produce a resultant light having a desired color temperature;
• and
• adjusting the color temperature of the resultant light by adjusting the second intensity of the colored light;
• wherein the color temperature of the resultant light is adjusted between about 2500 to about 5000 degrees Kelvin.

A temperature adjustable LED arrangement comprising:

• at least one white LED;
• a first drive circuit operable to supply a first drive current to the at least one white LED such that a white light is output at a first intensity;
• at least one red LED arranged to output a red light that combines with the white light;
• a second drive circuit operable to supply a second drive current to the at least one red LED such that the red light is output at a second intensity;
• at least one yellow LED arranged to output a yellow light that combines with the white light and the red light to produce a resultant light having a color temperature;
• a third drive circuit operable to supply a third drive current to the at least one yellow LED such that the yellow light is output at a third intensity,
• the second drive circuit being adjustable so as to adjust a level of the second drive current supplied to the at least one red LED and the third drive circuit being adjustable so as to adjust a level of the third drive current supplied to the at least one yellow LED so as to vary the color temperature of the resultant light;
• wherein the color temperature of the resultant light is adjustable between about 2500 to about 5000 degrees Kelvin.