Capacitive switch reference method
AssigneeToyota Motor Engineering & Manufacturing North America, Inc.
InventorNicholas Scott Sitarski
Life of this patent
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Abstract
An example capacitive switch apparatus comprises a capacitive switch sensor providing a capacitive switch signal, a capacitive reference sensor providing a capacitive reference signal, and an electronic circuit, receiving the switch and reference signals and detecting switch activation by comparing the switch signal level with a threshold level. The threshold level is adjusted as a function of the reference signal level. The reference signal is obtained, for example during periods of operator proximity to the reference sensor. For a finger-operated switch, the reference signal is obtained when a finger is proximate the reference sensor.
Claims17
An apparatus, the apparatus being a capacitive switch operated by sensing the presence of a finger:
- said apparatus comprising:
- a capacitive switch sensor, providing a capacitive switch signal indicating the presence of the finger;
- a capacitive reference sensor, sensing a capacitive reference signal;
- and
- an electronic circuit, receiving the capacitive switch signal and the capacitive reference signal,
- the electronic circuit detecting switch activation by comparing the capacitive switch signal to a threshold signal level,
- the threshold signal level being adjusted as a function of the capacitive reference signal,
- the capacitive reference sensor sensing the capacitive reference signal only when the finger is in proximity to the capacitive reference sensor.
A capacitive switch apparatus for a vehicle operated by sensing the presence of a vehicle operator hand;
- said apparatus comprising:
- a capacitive switch sensor, operable to provide a capacitive switch signal indicating the presence of the vehicle operator hand;
- a capacitive reference sensor, operable to sense a capacitive reference signal;
- and
- an electronic circuit, receiving the capacitive switch signal and the capacitive reference signal,
- the electronic circuit detecting switch activation by comparing the capacitive switch signal with a threshold signal level,
- the threshold signal level being adjusted as a function of a signal level of the capacitive reference signal,
- the capacitive reference signal being sensed only during periods when the vehicle operator hand is in proximity to the capacitive reference sensor.
A method of detecting an activation of a capacitive switch within a vehicle by sensing the presence of a hand of a vehicle operator, the method comprising:
- sensing a reference signal from a capacitive reference sensor only when the hand of the vehicle operator is proximate the capacitive reference sensor;
- using the reference signal to adjust a threshold level for switch activation to determine an adjusted threshold level;
- obtaining a capacitive switch signal from a capacitive switch sensor;
- comparing the capacitive switch signal with the adjusted threshold level to detect activation of the capacitive switch.
Dependencies are inferred from the claim text.