Lighting system and lighting control device equipped for the lighting system

1. A lighting system, comprising:

a lighting load including a plurality of light source elements having different kinds of correlated color temperatures; and

a lighting control device configured

to adjust a light output of the lighting load to a first light output corresponding to a first correlated color temperature and a first illuminance in a first time slot, and

to decrease the light output of the lighting load up to a second light output with the passage of time in a second time slot after the first time slot, the second light output corresponding to a second correlated color temperature and a second illuminance,

wherein the lighting control device is configured to cooperatively decrease, in the second time slot, a correlated color temperature and an illuminance obtained from the lighting load, the cooperative decrease is performed within a target region defined by Kruithof's Curve in which a horizontal axis represents the correlated color temperature and a vertical axis represents an illuminance, wherein the target re ion is bounded b a first curve that delimits an upper side of the target region and a second curve that delimits a lower side of the target region.

2. The lighting system of claim 1 ,

wherein the lighting control device is configured to adjust a correlated color temperature and an illuminance obtained from the lighting load by adjusting each light output of the light source elements.

3. The lighting system of claim 1 , wherein the first correlated color temperature is higher than a color temperature of neutral white color.

4. The lighting system of claim 1 , wherein the first correlated color temperature is equal to or lower than a color temperature of daylight color.

5. The lighting system of claim 1 , wherein the first illuminance is a horizontal illuminance of 500 lx or more in an installation space of the lighting load.

6. The lighting system of claim 1 , wherein the start of the second time slot is a time between one and three o'clock after noon.

7. The lighting system of claim 1 , wherein the second correlated color temperature is lower than a color temperature of neutral white color.

8. The lighting system of claim 1 , wherein the second correlated color temperature is higher than a color temperature of light bulb color.

9. The lighting system of claim 1 , wherein the second illuminance is a horizontal illuminance of 300 lx or more and 500 lx or less in the installation space of the lighting load.

10. The lighting system of claim 1 , wherein the lighting control device is further configured to decrease the light output of the lighting load to a third illuminance lower than the first illuminance in a third time slot between the first and second time slots.

11. The lighting system of claim 1 , further comprising a human detector configured to detect the presence or nonpresence of a person in an installation space of the lighting load,

wherein the lighting control device is configured:

to adjust a light output of the lighting load to the first light output in the first time slot and also to decrease the light output of the lighting load up to the second light output with the passage of time in the second time slot, when the human detector is detecting the presence of a person; and

to change the first light output to a light output corresponding to the first correlated color temperature and a lower illuminance than the first illuminance in the first time slot and also to change the second light output to a light output corresponding to the second correlated color temperature and a lower illuminance than the second illuminance in the second time slot, when the human detector is detecting the nonpresence of a person.

12. The lighting system of claim 1 , further comprising a luminance sensor configured to sense illuminance in an installation space, capable of receiving light from an outside, of the lighting load,

wherein the lighting control device is configured to control the light output of the lighting load based on the illuminance sensed with the luminance sensor.

13. The lighting system of claim 1 , wherein the lighting control device is configured to adjust the light output of the lighting load to a fourth illuminance lower than the first illuminance in a fourth time slot just before the first time slot.

14. The lighting system of claim 1 ,

wherein the first curve passes approximately through points having coordinates of: 2000 K and 17 lx, 3000 K and 500 lx, and 4400 K and 50,000 lx, on the horizontal axis and the vertical axis, respectively, and

the second curve passes approximately through points having coordinates of: 2000 K and 6 lx, 3000 K and 100 lx, and 8000 K and 500 lx, on the horizontal axis and the vertical axis, respectively.

15. The lighting system of claim 1 , wherein the first curve and second curve diverge with increasing temperature.

16. A lighting control device, configured to adjust a light output of a lighting load to a first light output corresponding to a first correlated color temperature and a first illuminance in a first time slot, and

To decrease the light output of the light load up to a second light output with the passage of time in a second time slot after the first time slot, the second light output corresponding to a second correlated color temperature and a second illuminance,

wherein the lighting control device is configured to cooperatively decrease, in the second time slot, a correlated color temperature and an illuminance obtained from the lighting load, the cooperative decrease is performed within a target region defined by Kruithof's Curve in which a horizontal axis represents the correlated color temperature and a vertical axis represents an illuminance, wherein the target region is bounded by a first curve that delimits an upper side of the target region and a second curve that delimits a lower side of the target region.

17. The lighting control device of claim 16 ,

wherein the first curve passes approximately through points having coordinates of: 2000 K and 17 lx, 3000 K and 500 lx, and 4400 K and 50,000 lx, on the horizontal axis and the vertical axis, respectively, and

the second curve passes approximately through points having coordinates of: 2000 K and 6 lx, 3000 K and 100 lx, and 8000 K and 500 lx, on the horizontal axis and the vertical axis, respectively.

18. The lighting control device of claim 16 , wherein the first curve and second curve diverge with increasing temperature.