Optical Finger Navigation Jitter Reduction via Modulated Light Detection
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Solution Overview
Problem
Conventional optical finger navigation systems in portable devices are prone to erroneous cursor movements due to ambient light and unintended finger placement or removal, causing jittering and sudden cursor jumps, especially at high finger speeds.
Innovation Solution
An object detection device with a light source, sensor, and pattern detection engine that emits a series of alternating high and low current intensities, allowing the system to differentiate between object movement and ambient light, thereby reducing or eliminating erroneous cursor movements by only recognizing the presence of a finger for navigation operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sensor continuously monitors light for navigation operations, then the navigation system remains responsive to user input, but erroneous cursor movements occur due to ambient light and unintended finger placement or removal
Solution Approach 1:
The system performs preliminary detection of object presence before enabling navigation operations. The pattern detection engine analyzes the received light signal to determine if an object is present on the navigation surface before the navigation engine processes movement data, preventing false cursor movements from ambient light or unintended finger placements
Solution Approach 2:
The pattern detection engine serves as an intermediary between the sensor and navigation engine. It filters and validates the raw light signal data, determining whether the signal represents a valid object presence before allowing the navigation engine to process the data for cursor movement, thereby eliminating erroneous movements
2Measurement precision
If the light source emits continuous light for object detection, then the sensor receives sufficient light signal for accurate detection, but the system cannot differentiate between reflected light from objects and ambient light
Solution Approach 1:
The light source emits light in periodic pulses rather than continuously. The current controller drives the light source to emit light pulses at specific intervals, and the pattern detection engine identifies objects by detecting these periodic patterns in the reflected light, allowing differentiation from ambient light which lacks this periodic structure
Solution Approach 2:
The system uses temporal variations in light intensity (analogous to color changes in time domain) to encode object presence information. The light source alternates between emitting and non-emitting states, creating a temporal pattern that the pattern detection engine uses to distinguish reflected light from objects against the background of continuous ambient light
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces or eliminates cursor jittering and unwanted motion caused by ambient light, ensuring more accurate navigation by only registering finger movements when an object is detected, thus improving navigation precision in portable electronic devices.
Implementation Method 1
The light source (102) is configured to emit light in response to a drive current having a pattern provided by a current controller (104)
Implementation Method 2
The sensor (106) is operable to receive light, notably light reflected from an object at the detection area (101) and subsequently generates a signal in response to the light received
Data Source
AI summary
A device for detecting the presence of an object is provided. The device includes a light source, a current controller coupled to the light source, a sensor and a pattern detection engine. The current controller sets to provide the light source with a drive current having a pattern. The sensor is operable to receive light, notably light reflected from an object at the detection area and subsequently generates a signal in response to the light received. The pattern detection engine receives the signal from the sensor and subsequently reports the presence of the object upon determining the presence of the pattern in the signal. The object detection system is further configured to provide a navigation operation when an object is detected at the detection area.