Ambient light compensation sensor and procedure

• US 8,207,676 B2
• Filed: 09/08/2008
• Issued: 06/26/2012
• Est. Priority Date: 09/11/2007
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Hilgers, Achim
• Primary Examiner(s): Owens, Douglas W
• Assistant Examiner(s): A, Minh D
• Application Number:
  US12/676,629
• Publication Number:
  US 20100308737A1
• Time in Patent Office: 1,387 Days
• Field of Search: 315/149, 315/50, 315/151, 315/152, 315/153, 315/154, 315/155, 315/156, 315/157, 315/158, 250/200, 250/203.3, 250/201.1, 250/203.2, 250/205, 250/552, 250/553, 362/800
• US Class Current: 315/152
• CPC Class Codes: G01J 1/02 Details
• CPC Class Codes: G01J 1/0214 Constructional arrangements for removing stray light
• CPC Class Codes: G01J 1/04 Optical or mechanical part supplementary adjustable parts
• CPC Class Codes: G01J 1/0407 Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings
• CPC Class Codes: G01J 1/0474 Diffusers cavities G01J2001/0481
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01J 2001/1636 one detector directly monitoring the source, e.g. also impulse time controlling
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0205 Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
• CPC Class Codes: G01J 3/021 using plane or convex mirrors, parallel phase plates, or particular reflectors
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G01J 3/0262 Constructional arrangements for removing stray light
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/50 using electric radiation detectors
• CPC Class Codes: G01J 3/505 measuring the colour produced by lighting fixtures other than screens, monitors, displays or CRTs
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback

Abstract

The present invention relates to a solid-state based light source, a corresponding circuitry and a method of emitting light, including one or more light source elements for generating light, a first sensor for receiving light emitted by the light source elements and ambient light and for generating a first sensor signal (S1) representing the received light, a second sensor for only receiving ambient light and for generating a second sensor signal (S2) representing the received ambient light. Moreover, the solid-state based light source comprises a control unit for receiving the first and the second sensor signals (S1, S2) and for generating control signals (Sc) for controlling the light source elements, based on the difference between the first and the second sensor signals (S1, S2), to compensate for the influence of the ambient light.

Claims

1. Solid-state based light source for emitting light, comprising

one or more light source elements for generating light,

a first sensor for receiving light emitted by the light source elements and ambient light and for generating a first sensor signal representing the received light,

a second sensor for only receiving ambient light and for generating a second sensor signal representing the received ambient light,

a third sensor protected from light for generating a third sensor signal representing darkness for use as a reference;

a control unit for receiving the first and the second sensor signals and for generating control signals for controlling the light source elements based on the difference between the first and the second sensor signals to compensate for the influence of the ambient light, wherein the control unit further receives the third sensor signal for generating control signals for controlling the light source elements taking into account the third sensor signal; and

directing means for selectively directing the ambient light together with the light generated by the light source elements to the first sensor and the ambient light alone to the second sensor.

2. Solid-state based light source according to claim 1, further comprising an input unit for inputting information concerning the desired properties of the light emitted by the solid-state based light source and the control unit for receiving the information from the input unit and for generating control signals for controlling the light source elements according to the desired properties.

3. Solid-state based light source according to claim 1, further comprising a main diffuser at least partially located above the light source elements and the sensors for improving the quality of the sensor signals (S1) by directing at least part of the light generated by the light source elements to the first sensor and by demodulating and uniformly directing the ambient light to the first sensor.

4. Solid-state based light source according to claim 1, further comprising

a filter construction comprising a first diffuser for collecting the ambient light and the light generated by the light source elements and a second diffuser for only collecting the ambient light, and

a mounting unit for integrally mounting the first and the second sensors and the filter construction, wherein the first diffuser directs the collected light to the first sensor and the second diffuser directs the collected light to the second sensor.

5. Solid-state based light source according to claim 4, wherein

the first diffuser protrudes over the mounting unit and has at least one first sidewall and a first end-surface with a first outwardly facing layer and a second inwardly facing layer, wherein the parts of the sidewall protruding over the mounting unit and the first outwardly facing layer are transparent and the second inwardly facing layer at least partially directs the light having penetrated the sidewalls to the first sensor, and

the second diffuser has at least one transparent second sidewall and a second transparent end-surface, the end-surface aligning with the mounting unit, said mounting unit having delimiting walls which are non-transparent.

6. Solid-state based light source according to claim 5, wherein

the first and the second sensors and the first and second diffusers of the filter construction are concentrically arranged around each other,

the second sensor is surrounded by the first sensor,

the second diffusor is surrounded by the first diffusor,

the first sidewall is transparent, and

the second sidewall is non-transparent.

7. Solid-state based light source according to claim 6, wherein the first and the second diffusers are funnel-shaped for only receiving the ambient light emitted within a predetermined angle range.

8. Circuitry for compensating for ambient light, comprising

at least one first input channel for inputting first sensor signals representing combinations of generated and ambient lights,

at least one second input channel for inputting second sensor signals representing ambient lights,

at least one third input channel for inputting third sensor signals representing darkness for use as a reference,

a first transformation unit for transforming the first sensor signals into first tristimulus signals,

a second transformation unit for transforming the second sensor signals into second tristimulus signals,

a signal processing unit for calculating the difference between the first and the second tristimulus signals taking into account tristimulus signals corresponding to the third sensor signals, for compensating for the ambient light and for generating a corresponding control tristimulus signal, and

at least one output channel for outputting the control tristimulus signal.

9. Solid-state based light source for emitting light, comprising

one or more light source elements for generating light,

a first sensor for receiving light emitted by the light source elements and ambient light and for generating a first sensor signal representing the received light,

a second sensor for receiving ambient light and for generating a second sensor signal representing the received ambient light,

a control unit for receiving the first and the second sensor signals and for generating control signals for controlling the light source elements based on the difference between the first and the second sensor signals to compensate for the influence of the ambient light,

a filter construction comprising a first diffuser for collecting the ambient light and the light generated by the light source elements and a second diffuser for only collecting the ambient light;

a mounting unit for integrally mounting the first and the second sensors and the filter construction, wherein the first diffuser directs the collected light to the first sensor and the second diffuser directs the collected light to the second sensor; and

directing means for selectively directing the ambient light together with the light generated by the light source elements to the first sensor and the ambient light alone to the second sensor.

10. Solid-state based light source according to claim 9, wherein the first diffuser protrudes over the mounting unit and has at least one first sidewall and a first end-surface with a first outwardly facing layer and a second inwardly facing layer, wherein the parts of the sidewall protruding over the mounting unit and the first outwardly facing layer are transparent and the second inwardly facing layer at least partially directs the light having penetrated the sidewalls to the first sensor, and the second diffuser has at least one transparent second sidewall and a second transparent end-surface, the end-surface aligning with the mounting unit, said mounting unit having delimiting non-transparent walls.

11. Solid-state based light source according to claim 10, wherein

the first and the second sensors and the first and second diffusers of the filter construction are concentrically arranged around each other,

the second sensor is surrounded by the first sensor,

the second diffusor is surrounded by the first diffusor,

the first sidewall is transparent, and

the second sidewall is non-transparent.

12. Solid-state based light source according to claim 11, wherein the first and the second diffusers are funnel-shaped for only receiving the ambient light emitted within a predetermined angle range.