Indoor/outdoor detection
A light sensor is used to detect ambient light conditions. According to an example embodiment, a light sensor ( 112 ) detects color temperature and, in some instances, intensity characteristics of ambient light ( 120, 130, 140 ) in an environment and uses these detected characteristics ( 116 ) to determine the location of the sensor relative to natural and artificial light sources. This location determination is used to selectively operate circuits in a device such as a hand-held telephone, computer device or personal data assistant (PDA).
1. For use in controlling the operation of an electronic device, a sensor arrangement comprising:
a light sensor circuit configured and arranged to provide at least one output corresponding to an intensity of light incident upon the light sensor circuit, the light sensor circuit including:
a first light sensor configured and arranged to respond predominantly to light incident upon the light sensor circuit and in the visible spectrum, and
a second light sensor configured and arranged to respond predominantly to light incident upon the light sensor circuit and in the infrared spectrum; and
a controller circuit configured and arranged to
determine the presence of artificial light based upon the at least one output, by
determining a ratio between a response of the first light sensor and a response of the second light sensor,
determining a color temperature of light incident on the light sensor circuit based upon the determined ratio,
filtering, for light incident on the light sensor circuit, direct current (DC) components of light intensity variations from the at least one output of the light sensor circuit to produce a filtered output, and
detecting, using the filtered output, the presence of an artificial source by correlating variations in the intensity, for light incident on the light sensor circuit, to variations in intensity resulting from a corresponding type of artificial source, and
selectively operate circuits in the electronic device in response to determining the presence of artificial light.
2. The sensor arrangement of claim 1 , wherein the controller is configured and arranged to:
provide an indication that artificial light is present in response to the determined color temperature of light incident on the light sensor circuit being less than 4000K;
provide an indication that artificial light is present in response to the determined color temperature of light incident on the light sensor circuit being greater than 6500K;
provide an indication that artificial light is present in response to detecting, using the variation in intensity in the filtered output having a frequency of 100-120 Hz; and
provide an indication that artificial light is present in response to the first and second sensors indicating a light intensity greater than 4 kLux.
3. The sensor arrangement of claim 1 , wherein the controller circuit determines the presence of artificial light by using the at least one output to determine that the incident light has a color temperature that is greater than the color temperature of natural light.
4. The sensor arrangement of claim 1 , wherein the controller circuit determines the presence of natural light by using the at least one output to determine that the incident light has a color temperature that is greater than a color temperature of incandescent light and less than a color temperature of fluorescent light.
5. The sensor arrangement of claim 1 , wherein the controller circuit
determines a location of the light sensor circuit to be an indoor location or an outdoor location in response to the determined presence of artificial light,
operates a first set of circuits in the electronic device for indoor use in response to determining that the sensor is located at an indoor location, and
operates a second set of circuits in the electronic device for outdoor use in response to determining that the sensor is located at an outdoor location.
6. The sensor arrangement of claim 1 , wherein the a light sensor circuit provides an intensity output indicative of the intensity of light incident upon the light sensor circuit, and wherein the controller circuit
determines the presence of at least one of artificial light and natural light, using the intensity indicated via the intensity output and
selectively operates circuits in the electronic device in response to the determination.
7. The sensor arrangement of claim 1 , wherein the controller circuit
determines the presence of artificial light by using the at least one output to detect the presence of a frequency component that corresponds to a frequency of an alternating current source that provides power to an artificial light source, and
selectively operates circuits in the electronic device in response to the determination of the presence of artificial light.
8. The sensor arrangement of claim 1 , wherein the light sensor circuit provides an intensity output indicative of the intensity of light incident upon the light sensor circuit, and wherein the controller circuit is configured and arranged to perform the steps of the determination of the ratio, the determination of the color temperature, filtering, and detecting in response to the
intensity output being less than an expected intensity of natural light.
9. The sensor arrangement of claim 1 , wherein the light sensor circuit provides an intensity output indicative of the intensity of light incident upon the light sensor circuit, and wherein the controller circuit
determines the presence of artificial light by using the intensity output to detect at least one of: the variation in intensity and an intensity of incident light that is less than an expected intensity of natural light, and
selectively operates circuits in the electronic device in response to the determination.
10. The arrangement of claim 1 , wherein the first light sensor is configured and arranged to filter visible light from reaching the second light sensor and wherein the first and second light sensors each include a photodiode.
11. An indoor/outdoor electronic control circuit arrangement to selectively control indoor and outdoor electrical functionality of a portable electronic device, the arrangement comprising:
an ambient light sensor arrangement configured and arranged to provide, for ambient light, color and intensity data indicative of variations in intensity; and
a control circuit to receive and process the color and intensity data to generate an indoor control signal for operating the portable electronic device under indoor conditions in response to the intensity, and to generate an outdoor control signal for operating the portable electronic device under outdoor conditions.
12. The arrangement of claim 11 , wherein the control circuit generates
an indoor control signal by identifying the presence of an artificial light source subject to alternating current fluctuations in response to the intensity data being indicative of intensity fluctuation, and
an outdoor control signal in response to at least one of
the intensity data being indicative of ambient light intensity that is greater than a predefined threshold that corresponds to an expected intensity of artificial light, and
the color data being indicative of ambient light color temperature that is in a range of color temperatures that is between color temperatures respectively associated with infrared light and with fluorescent light.
13. The arrangement of claim 11 , wherein the control circuit generates
an indoor control signal in response to the intensity data indicating cyclic fluctuation in intensity, and
an outdoor control signal in response to
the intensity data indicating that the intensity of the ambient light is greater than about 4 kLux, or
the color data indicating that the color temperature of the ambient light is between about 4000K and 6000K.
14. The arrangement of claim 11 , wherein the ambient light sensor arrangement includes a visible light sensor selectively responsive to visible light and an infrared light sensor selectively responsive to infrared light.
15. The arrangement of claim 11 , wherein the ambient light sensor arrangement includes
a bottom photodiode that is predominantly responsive to infrared light, and
a top photodiode that is predominantly responsive to visible light, and that filters light passed to the bottom photodiode.
16. The arrangement of claim 11 , wherein the control circuit is responsive to time data indicating a night time condition by disabling the generation of the control signals.
17. The arrangement of claim 11 , wherein the control circuit is responsive to time data indicating a night time condition by
using GPS data characterizing a GPS signal to determine the location of the portable electronic device as either an indoor location or an outdoor location,
generating an indoor control signal for operating the portable electronic device under indoor conditions in response to determining that the location is an indoor location, and
generating an outdoor control signal for operating the portable electronic device under outdoor conditions in response to determining that the location is an outdoor location.
18. A method for controlling the operation of an electronic device according to ambient light conditions, the method comprising:
detecting the presence of at least one of artificial light and natural light based upon light color and variations in light intensity;
in response to the step of detecting, determining the location of the electronic device as being one of: an indoor location and an outdoor location;
operating a first set of circuits in the electronic device in response to determining that the location of the electronic device is an indoor location; and
operating a second set of circuits in the electronic device in response to determining that the location of the electronic device is an outdoor location.
19. The method of claim 18 , wherein
the step of detecting includes detecting a color temperature that is in a range of color temperatures attributable to artificial light, and
the step of determining includes determining that the electronic device is located indoors.
20. The method of claim 18 , wherein
the step of detecting includes using a first sensor circuit to detect light having a wavelength in a first range of wavelengths, and using a second sensor circuit to detect light having a wavelength in a second range of wavelengths, and
the step of determining includes using outputs from the first and second sensor circuits to determine a color temperature of the detected light.
21. The method of claim 18 , wherein the step of detecting includes detecting intensity variation in artificial light and the step of determining includes determining that the source of the detected light includes an alternating current source.
22. The method of claim 18 , wherein the step of detecting includes detecting intensity, intensity fluctuation due to an alternating current light source, and color characteristics of ambient light.