Ambient light sensor with reduced sensitivity to noise from infrared sources

• US 8,076,628 B2
• Filed: 09/25/2008
• Issued: 12/13/2011
• Est. Priority Date: 09/25/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Mahowald, Peter H.
• Primary Examiner(s): Le, Que T
• Assistant Examiner(s): Bui Pho, Pascal M
• Application Number:
  US12/238,380
• Publication Number:
  US 20100072351A1
• Time in Patent Office: 1,174 Days
• Field of Search: 250/214.AL, 250/214.R, 250/338.1, 250/339.01, 250/339.02, 250/339.05, 250/221, 250/205, 348/602, 348152-155, 340/500, 340/541, 340/545.3, 340/538.12, 340/540, 340/573.1, 340/600, 455/39, 455/67.11, 455/91, 455/92, 455/95, 455/114.2, 455/130
• US Class Current: 250/214.AL
• CPC Class Codes: G01J 1/02 Details
• CPC Class Codes: G01J 1/0219 Electrical interface; User interface
• CPC Class Codes: G01J 1/029 Multi-channel photometry
• 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 1/1626 Arrangements with two photodetectors, the signals of which are compared
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00

Abstract

Systems and methods are provided for detecting ambient light with reduced sensitivity to infrared sources. An electronic device may include an infrared sensor, an ambient light sensor, a decoder, and a processor. The infrared sensor may detect an intensity of infrared light. The ambient light sensor may be configured to detect incident light and to generate an electronic signal indicative of an intensity of visible light. The decoder may be configured to receive the intensity of infrared light and to generate an intensity of decoded infrared light. The processor, which may be coupled to the decoder and the ambient light sensor, may be configured to substitute an alternate electronic signal for the electronic signal if the intensity of infrared light exceeds a threshold amount.

Claims

1. An electronic device comprising:

an infrared sensor configured to detect an intensity of infrared light;

an ambient light sensor configured to detect incident light, wherein the ambient light sensor is configured to generate an electronic signal indicative of an intensity of visible light;

a decoder configured to receive the intensity of infrared light and to generate an intensity of decoded infrared light; and

a processor coupled to the decoder and the ambient light sensor, wherein the processor is configured to substitute an alternate electronic signal for the electronic signal if the intensity of the decoded infrared light exceeds a threshold amount.

2. The device of claim 1 further comprising:

an infrared filter interposed between the infrared sensor and an infrared source, wherein the infrared filter transmits infrared light over near-infrared wavelengths.

3. The device of claim 1 further comprising:

a photopic filter interposed between the ambient light sensor and an ambient light source, wherein the photopic filter transmits incident light over visible wavelengths, wherein the photopic filter receives incident light transmitted by the infrared window.

4. The device of claim 1, wherein the alternate electronic signal is a previous electronic signal.

5. The device of claim 4 further comprising:

a sample-and-hold circuit for providing the previous electronic signal.

6. The device of claim 1 further comprising:

an illumination mechanism configured to respond to the electronic signal or the alternate electronic signal.

7. An ambient light sensor module comprising:

an infrared filter for transmitting incident light over a band of near-infrared wavelengths;

an infrared sensor for receiving light transmitted by the infrared filter and for detecting an intensity of infrared light over near-infrared wavelengths; and

an ambient light sensor for detecting an intensity of visible light and for generating an electronic signal indicative of an intensity of ambient light, wherein the ambient light sensor is configured to modify the electronic signal based on the intensity of the infrared light.

8. An ambient light sensor module comprising:

a first sensor for detecting an intensity of all light at substantially any wavelength;

a second sensor for detecting an intensity of infrared light over near-infrared wavelengths; and

infrared light over near-infrared wavelengths; and

a light processing module coupled to the first sensor and the second sensor, wherein the light processing module is configured to determine an intensity of visible light based on a difference between the intensity of all light and the intensity of infrared light, and wherein the light processing module is configured to substitute an alternative intensity of visible light for the intensity of visible light if the intensity of infrared light exceeds a threshold amount.

9. The module of claim 8 further comprising:

a decoding module coupled to the second sensor and the light processing module, wherein the intensity of infrared light exceeds the threshold amount if the light processing module receives a blocking signal from the decoding module.

10. The module of claim 9, wherein the blocking signal is one of a carrier sense signal, decoded byte signal, and a decoded bit signal.