Proximity sensor with adaptive threshold

• US 20050200603A1
• Filed: 02/11/2005
• Published: 09/15/2005
• Est. Priority Date: 01/30/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Casebolt, Mark W., Lee, Mark R.
• Granted Patent: US 7,002,550 B2
• Time in Patent Office: Days
• US Class Current: 345/157
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3231 Monitoring the presence, absence or movement of users
• CPC Class Codes: G06F 1/3259 Power saving in cursor control device, e.g. mouse, joystick, trackball
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: H03K 2217/94026 Automatic threshold calibration; e.g. threshold automatically adapts to ambient conditions or follows variation of input
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A proximity sensor measures receptor output with an energy source deactivated. The sensor then measures receptor output with the energy source activated. The measurements with the energy source activated are compared to the measurements with the energy source deactivated to compensate for the effect of ambient conditions. A near condition is recognized if the change between the two groups of measurements exceeds a designated value. To compensate for receptor output that may decrease after reaching a peak value during approach of an object, a near condition can be maintained until the change between the two groups of measurements no longer exceeds a different designated value. Multiple sensors can be used to avoid false near conditions caused by, e.g., placing a device equipped with the sensors next to a stationary object. In one embodiment, a sensor comprises an infrared light emitting diode and a phototransistor.

Claims

1. A data input device, comprising:

a first detection means for detecting object proximity to a first position on the device, the first detection means including a first source means for emitting electromagnetic energy and a first receptor means for generating an output in response to electromagnetic energy;

a second detection means for detecting object proximity to a second position on the device, the second proximity detection means including a second source means for emitting electromagnetic energy and a second receptor means for generating an output in response to electromagnetic energy; and

control means for

selectively activating the first and the second source means,

sampling outputs of the first and the second receptor means,

storing indicators for sampled outputs,

comparing sets of indicators stored during intervals when the first and the second source means are deactivated with sets of indicators stored during intervals when the first and second source means are activated, and

recognizing an object-near condition only if the comparisons of sets stored while the first and second source means are deactivetaed with sets stored while the first and second source means are activated identify triggering levels of difference between the compared sets.

2. The data input device of claim 1, wherein the control means further comprises means for inducing hysteresis in the recognition of an object-near condition.

3. The data input device of claim 1, wherein the control means further comprises means for checking for anamolous input from at least one of the first and second detection means.