Always-on Sensor Circuit for Human Touch Detection
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Solution Overview
Problem
Conventional fingerprint sensing technologies in consumer devices face high power consumption issues, making them unable to be turned on continuously without rapidly draining the device's battery.
Innovation Solution
A device with always-on circuitry that separates the sensing of human touch into a low-power detection stage and a full-power analysis stage, allowing continuous or nearly continuous sensing without significant battery drainage, and eliminates the need for physical actuation devices like buttons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fingerprint sensor is turned on continuously to enable always-on touch sensing, then touch sensing capability is improved, but power consumption increases rapidly draining the battery
Solution Approach 1:
The patent segments the sensing system into two distinct parts: always-on circuitry for basic touch detection and a processor that can be in sleep or active modes. The always-on circuitry continuously monitors for touch events using minimal power, while the processor remains dormant until triggered by a detected touch, thus resolving the contradiction between continuous sensing capability and power consumption
Solution Approach 2:
The always-on circuitry performs preliminary touch detection before activating the full processing system. This preliminary action filters out false positives and only triggers the power-intensive processor when actual touch events are detected, enabling continuous monitoring capability while maintaining low average power consumption
2Use of energy by moving object
If conventional fingerprint sensor is turned off to save power, then power consumption is reduced, but touch sensing capability is lost requiring physical buttons
Solution Approach 1:
The system separates touch detection functionality from full processing functionality, allowing the detection circuitry to remain active while the processor sleeps. This enables the device to maintain buttonless operation for power-on events without requiring the full processing system to be continuously active
Solution Approach 2:
The always-on circuitry autonomously detects touch events and generates wake-up signals to activate the processor only when needed. This self-service mechanism eliminates the need for physical buttons or other activation inputs, as the system automatically responds to user touch while maintaining low power consumption
3Use of energy by moving object
If physical actuation devices like buttons are used to wake the device, then power consumption is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the power-on activation function from physical buttons and transfers it to the always-on circuitry that monitors the touch-sensitive display. This eliminates the need for separate physical actuation devices, reducing device complexity and manufacturing costs while maintaining low power consumption through intelligent circuit design
Data Source
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AI summary
Always-on or nearly always-on sensing of human touch at a device is provided. The sensing is split into a low-power detection stage and a full-power analysis stage, where the detection stage is implemented continually or nearly continually and causes system circuitry to perform analysis of the human touch after the low-power detection stage has confirmed the human touch. The sensing permits avoiding the reliance on physical actuation of a trigger prior to analysis of human touch.