Lighting system for controlling the color temperature of artificial light under the influence of the daylight level

• US 5,861,717 A
• Filed: 08/15/1997
• Issued: 01/19/1999
• Est. Priority Date: 03/10/1995
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Van Den Beld, Gerrit J., Tenner, Ariadne D., Begemann, Simon H. A.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Philogene, Haissa
• Application Number:
  US08/911,868
• Time in Patent Office: 522 Days
• Field of Search: 315/158, 315/154, 315/151, 315/152, 315/153, 315/157, 315/159, 250/214 AL, 250/205
• US Class Current: 315/158
• CPC Class Codes: H05B 39/042 by measuring the incident light
• CPC Class Codes: H05B 41/3922 and measurement of the incident light
• CPC Class Codes: H05B 47/10 Controlling the light source

Abstract

A lighting system having at least one light source for supplying artificial light and a control unit for controlling the light source. The light source is of the type having an adjustable color temperature. The control unit is provided with a control signal form a signal from a signal generator. The signal generator is dependent on the mean daylight level. The control unit is arranged to adjust the color temperature of the light source in dependence on a predetermined relationship between the mean daylight level and the color temperature of the artificial light. The lighting system will provide artificial light which will when the daylight level, as measured on an office desk, increases from approximately 400 lux to approximately 800 lux, increase the color temperature from approximately 3300 K to approximately 4300 K.

Claims

1. A lighting system, comprising at least one light source for supplying artificial light and a control unit for controlling the light source, the control unit comprising means for forming a control signal which is dependent on a daylight level, characterized in that the light source is of the type having an adjustable colour temperature, and the control unit is arranged to adjust the colour temperature of the light source in dependence on a predetermined relationship between the daylight level and the colour temperature of the artificial light.

2. The lighting system as claimed in claim 1, characterized in that the control unit comprises modification means which are arranged to modify the predetermined relationship between the daylight level and the colour temperature.

3. The lighting system as claimed in claim 2, characterized in that the control unit comprises a second control member which is arranged to readjust the adjusted colour temperature and to operate the modification means.

4. The lighting system as claimed in claim 2, in which the color temperature and daylight level substantially increase together.

5. The lighting system as claimed in claim 3, in which the color temperature and daylight level substantially increase together.

6. The lighting system as claimed in claim 1, characterized in that when the daylight level, measured on an office desk, increases from approximately 400 lux to approximately 800 lux, the colour temperature increases from approximately 3300 K to approximately 4300 K.

7. The lighting system as claimed claim 1, characterized in that the control unit stores at least two different, predetermined relationships between the daylight level and the colour temperature, and that the control unit comprises a first control member which is arranged to select one of said relationships.

8. The lighting system as claimed in claim 1, in which the color temperature and daylight level substantially increase together.

9. The lighting system as claimed claim 8, characterized in that the control unit stores at least two different, predetermined relationships between the daylight level and the colour temperature, and that the control unit comprises a first control member which is arranged to select one of said relationships.

10. The lighting system as claimed in claim 8, characterized in that when the daylight level, measured on an office desk, increases from approximately 400 lux to approximately 800 lux, the colour temperature increases from approximately 3300 K to approximately 4300 K.