Lighting device capable of changing a color of illumination light and lighting fixture

A lighting device capable of changing a color of illumination light, comprising:

• a first light source which includes one or more first solid light emitting elements for emitting first color light and has a first range of an individual difference in chromaticity;
• a second light source which includes one or more second solid light emitting elements for emitting second color light different in color from the first color light and has a second range of an individual difference in chromaticity;
• a third light source which includes one or more third solid light emitting elements for emitting third color light different in color from the first color light and the second color light and has a third range of an individual difference in chromaticity;
• a first lighting circuit configured to supply a first drive current according to a first desired value to the first light source;
• a second lighting circuit configured to supply a second drive current according to a second desired value to the second light source;
• a third lighting circuit configured to supply a third drive current according to a third desired value to the third light source;
• and
• a controller configured to provide the first desired value, the second desired value, and the third desired value to the first lighting circuit, the second lighting circuit, and the third lighting circuit, respectively,
• the controller being configured to, to adjust a color of illumination light composed of the first color light, the second color light, and the third color light, to a color represented by a desired chromaticity point in a chromaticity diagram, determine the first desired value, the second desired value, and the third desired value, based on a correction coefficient for correcting a chromaticity point of the first color light, a chromaticity point of the second color light, and a chromaticity point of the third color light to a first chromaticity point, a second chromaticity point, and a third chromaticity point, respectively,
• the first chromaticity point being defined as an intersection of a straight line in contact with the first range and the second range and another straight line in contact with the first range and the third range in the chromaticity diagram,
• the second chromaticity point being defined as an intersection of a straight line in contact with the second range and the first range and another straight line in contact with the second range and the third range in the chromaticity diagram, and
• the third chromaticity point being defined as an intersection of a straight line in contact with the third range and the first range and another straight line in contact with the third range and the second range in the chromaticity diagram,
• the correction coefficient including:
• a combination of a ratio of the first drive current corresponding to the first chromaticity point to a rated current of the first light source, a ratio of the second drive current corresponding to the first chromaticity point to a rated current of the second light source, and a ratio of the third drive current corresponding to the first chromaticity point to a rated current of the third light source;
• a combination of a ratio of the first drive current corresponding to the second chromaticity point to a rated current of the first light source, a ratio of the second drive current corresponding to the second chromaticity point to a rated current of the second light source, and a ratio of the third drive current corresponding to the second chromaticity point to a rated current of the third light source;
• and
• a combination of a ratio of the first drive current corresponding to the third chromaticity point to a rated current of the first light source, a ratio of the second drive current corresponding to the third chromaticity point to a rated current of the second light source, and a ratio of the third drive current corresponding to the third chromaticity point to a rated current of the third light source, and
• the controller being configured to store the correction coefficient corresponding to any of chromaticity points included in a triangle on the chromaticity diagram formed by a segment interconnecting the first chromaticity point and the second chromaticity point, another segment interconnecting the second chromaticity point and the third chromaticity point, and another segment interconnecting the third chromaticity point and the first chromaticity point.