Matrix arrangement of photodetector for use as a proximity sensor and ambient light sensor
An optical sensor and optical system are disclosed. The optical sensor is disclosed to include a light source, a photodetector having a proximity sensing portion and an ambient light sensing portion, and a controller configured to implement a proximity sensing phase where the proximity sensing portion of the photodetector is utilized to obtain an incident light reading when the light source is ON and then implement an ambient light sensing phase where the ambient light sensing portion of the photodetector is utilized to obtain an incident light reading when the light source is OFF.
1. An optical sensor, comprising:
a light source;
a photodetector comprising a plurality of pixels which are used for both proximity light sensing and ambient light sensing; and
a controller configured to implement a proximity sensing phase where pixels used for proximity light sensing are utilized to obtain an incident light reading when the light source is ON and then implement an ambient light sensing phase where pixels used for ambient light sensing are utilized to obtain an incident light reading when the light source is OFF, wherein the pixels used for the proximity light sensing are different from the pixels used for ambient light sensing, and wherein the pixels used for the proximity light sensing are connected to a different set of capacitors and switches than the pixels used for ambient light sensing.
2. The optical sensor of claim 1 , wherein the controller is further configured to control an exposure time for the photodetector such that a sufficient amount of signal is accumulated by the photodetector to accommodate a dynamic voltage range.
3. The optical sensor of claim 1 , wherein the controller is configured to subtract an incident light reading taken during the ambient light sensing phase from an incident light reading taken during the proximity sensing phase to obtain an intrinsic proximity sensing reading that is caused by ambient light.
4. The optical sensor of claim 3 , wherein the intrinsic proximity sensing reading that is caused by ambient light is used to determine a distance to an object detected during the proximity sensing phase.
5. The optical sensor of claim 1 , wherein the proximity sensing phase is conducted during a time that does not overlap with the ambient light sensing phase.
6. The optical sensor of claim 1 , wherein the plurality of pixels are arranged in an array and divided between at least a first selected set of pixels and a second selected set of pixels, wherein readings from the first and second selected set of pixels are used to obtain a determination of object movement during the proximity sensing phase.
7. The optical sensor of claim 1 , further comprising a plurality of capacitors that are connected to the photodetector, wherein the plurality of capacitors are coupled to the controller and are selectively switched by the controller thereby enabling the controller to implement the proximity sensing phase and the ambient light sensing phase.
8. The optical sensor of claim 7 , further comprising one or more digital filters that are used to control a comparison of readings obtained at specific ones of the plurality of capacitors to determine a movement of an object.
9. An optical system, comprising:
at least one optical element that focuses light passing therethrough; and
a photodetector comprising an array of photo-sensitive unit segments, wherein the photo-sensitive unit segments in the array include a set of ambient light sensor unit segments and a set of proximity sensor unit segments that are intermixed among one another such that no two adjacent pixels are of the same type, and wherein an overall area of the array is larger than a focus area of the at least one optical element.
10. The optical system of claim 9 , wherein ambient light sensor unit segments and the proximity sensor unit segments are intermixed among one another such that a diagonal route across the array of photo-sensitive unit segments includes pixels of a single type.
11. The optical system of claim 9 , wherein at least one photo-sensitive unit segment in the array is used as an ambient light sensor unit segment during an ambient light sensing phase of operation and wherein the at least one photo-sensitive unit segment in the array is also used as a proximity light sensor unit during a proximity sensing phase of operation.
12. The optical system of claim 9 , wherein the array is established on a single piece of silicon.
13. The optical system of claim 9 , wherein the overall area of the array is larger than the focus area of the at least one optical element at least by a placement tolerance associated with placing the at least one optical element relative to a center of the array.
14. The optical system of claim 9 , further comprising a light source that emits light to be reflected by an object and then detected by the proximity sensor unit segments.
15. The optical system of claim 14 , wherein light readings obtained from the ambient light sensor unit segments are subtracted from light readings obtained from the proximity light sensor unit segments to determine an intrinsic proximity sensing reading caused by ambient light.
16. The optical system of claim 15 , wherein the intrinsic proximity sensing reading caused by ambient light is used to determine a distance between the array and the object.
17. A sensor, comprising:
a photodetector comprising an array of photo-sensitive unit segments, the array including a proximity sensing portion and an ambient light sensing portion, wherein photo-sensitive unit segments belonging to the proximity sensing portion are intermixed among photo-sensitive units belonging to the ambient light sensing portion such a diagonal route across the array includes photo-sensitive unit segments of a single type; and
a controller that implements two distinct sensing phases that include a proximity sensing phase and an ambient light sensing phase, wherein the proximity sensing portion of the photodetector is used during the proximity sensing phase, and wherein the ambient light sensing portion of the photodetector is used during the ambient light sensing phase.
18. The sensor of claim 17 , wherein the proximity sensing phase and ambient light sensing phase do not overlap in time.
19. The sensor of claim 17 , wherein the proximity sensing portion is used to detect incident light on the photodetector array during the proximity sensing phase, wherein the ambient light sensing portion is used to detect incident light on the photodetector array during the ambient light sensing phase, wherein the proximity sensing phase corresponds to a time during which a light source of the sensor is ON, and wherein the ambient light sensing phase corresponds to a time during which the light source of the sensor is OFF.
20. The sensor of claim 17 , wherein the controller is further configured to control an exposure time for the photodetector such that a sufficient amount of signal is accumulated by the photodetector to accommodate a dynamic voltage range and wherein at least one photo-sensitive unit segment from the array belongs to both the proximity sensing portion and the ambient light sensing portion.