LIGHTING DEVICE WITH MULTIPLE PRIMARY COLORS

• US 20100060185A1
• Filed: 12/17/2007
• Published: 03/11/2010
• Est. Priority Date: 12/20/2006
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Van Duijneveldt, Wido
• Granted Patent: US 8,525,444 B2
• Time in Patent Office: Days
• US Class Current: 315/287
• CPC Class Codes: H04N 1/6086 by scene illuminant, i.e. conditions at the time of picture capture, e.g. flash, optical filter used, evening, cloud, daylight, artificial lighting, white point measurement, colour temperature
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback

Abstract

The invention relates to a lighting device (10) with at least four light emitters (1 IR, 1 IG, 1 IB, 1 IW) of different primary colors that shall be controlled according to given primary target values, for example target values for the color point (x, y) and flux (Φ). This object is achieved by determining secondary target values, for example for the total power consumption (P) of the light emitters, that are in accordance with primary target values and with the possible control commands (r, g, b, w) (e.g. duty cycles between 0% and 100%). By fixing the secondary target values, the control commands for the light emitters can uniquely be determined, in preferred embodiments by a simple matrix multiplication.

Claims

1. A lighting device (10) comprising:

a) a number of N≧

4 light emitters (11R, 11G, 11B, 11W) with different primary colors;

b) a target determination unit (13) for determining a number of s<

N secondary target values (P) that are functionally related to the driving commands (r, g, b, w) for the light emitters;

c) a driving unit (14) for determining individual driving commands (r, g, b, w) for the light emitters based on the secondary target values (P) and on a number of p<

N given primary target values (x, y, Φ

) for the light output of the lighting device.

2. The lighting device according to claim 1,

characterized in that the driving unit comprises a matrix multiplication module (14) for evaluating a linear relation between the vector of driving commands (r, g, b, w) and a target vector (X, Y, Z, P) derived from the primary and secondary target values.

3. The lighting device according to claim 1,

characterized in that the target determination unit (13) determines the secondary target values (P) in dependence on the given primary target values (x, y, Φ

).

4. The lighting device according to claim 1,

characterized in that the secondary target values comprise the power consumption (P) of a subset of the light emitters (11R, 11G, 11B, 11W) and/or that the primary target values comprise the color point (x, y) and flux (Φ

) of the lighting device.

5. The lighting device according to claim 1,

characterized in that the target determination unit (13) comprises a range estimator for determining the range of allowable primary target values (P) that are in accordance with the allowable driving commands (r, g, b, w) and at least a subset of the given primary target values (x, y, Φ

).

6. The lighting device according to claim 1,

characterized in that the driving commands are duty cycles (r, g, b, w) of a pulse width modulation.

7. The lighting device according to claim 5,

characterized in that the target determination unit (13) selects a vector V of secondary target values from the allowable range according to the relation

V=(Φ

_t/Φ

_x)·

V_x,

with V_x being the vector of secondary target values from the allowable range that corresponds to a maximal primary target value Φ

_x and with Φ

_t being a given primary target value.

8. The lighting device according to claim 5,

characterized in that the target determination unit (13) selects for given primary target values (x, y, Φ

) the secondary target values (P) from the allowable range according to some optimization criterion, particularly according to a minimization of power consumption or a minimization of the highest duty cycle driving command.

9. The lighting device according to claim 1,

characterized in that the light emitters (11R, 11G, 11B, 11W) comprise a LED, phosphor converted LED, organic LED (OLED), LASER, phosphor converted LASER, colored fluorescent lamp, filtered (colored) halogen lamp, filtered (colored) high intensity discharge (HID) lamp, and/or filtered (colored) UHP lamp.

10. A method for controlling a lighting device (10) comprising a number of N≧

4 light emitters (11R, 11G, 11B, 11W) with different primary colors, comprising the steps of

a) determining s<

N secondary target values (P) that are functionally related to the driving commands (r, g, b, w) for the light emitters;

b) determining individual driving commands (r, g, b, w) for the light emitters based on the secondary target values (P) and on a number of p<

N given primary target values (x, y, Φ

) for the light output of the lighting device.