Ambient Light Sensor Orientation Adaptation
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Solution Overview
Problem
Mobile electronic handheld devices with multiple orientations face issues with light sensor obstruction, leading to unreliable backlight adjustments, as the sensor can be covered by the user's fingers or thumbs, especially in landscape mode, affecting readability in varying environments.
Innovation Solution
A method that utilizes a light sensor and an orientation sensor to adjust backlight intensity based on ambient light samples and device orientation, employing threshold values to switch between DIM, OFFICE, and BRIGHT modes, ensuring accurate backlight control even when the sensor is obstructed, by using a processor to determine the device's orientation and adjust the backlight accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light sensor is positioned on the device for automatic backlight adjustment, then the display readability in different lighting conditions is improved, but the sensor may be covered by user's fingers or thumbs in certain orientations, leading to unreliable sensing
Solution Approach 1:
The system dynamically adjusts the light sensor sampling rate based on device orientation. When the device is in a first orientation (e.g., portrait mode where sensor is accessible), sampling occurs at a first rate. When switched to a second orientation (e.g., landscape mode where sensor may be covered), sampling switches to a second rate. This dynamic adaptation resolves the contradiction by making the sensing system reliable across different usage scenarios.
Solution Approach 2:
The patent changes the sampling rate parameter of the light sensor based on detected device orientation. By monitoring orientation changes and adjusting the sampling frequency accordingly, the system optimizes sensor utilization - using higher sampling rates when the sensor is likely unobstructed and lower rates when obstruction is probable, thereby maintaining measurement precision while ensuring operational reliability.
2Speed
If the light sensor samples ambient light continuously at a high rate, then the backlight can respond quickly to lighting changes, but power consumption increases and brief fluctuations cause constant backlight state transitions
Solution Approach 1:
The system implements periodic light sampling with variable periods based on device orientation and current backlight state. Instead of continuous high-rate sampling, the light sensor is activated at specific intervals. The sampling period is adjusted dynamically - shorter periods when rapid response is needed and longer periods during stable states, thereby reducing overall power consumption while maintaining appropriate responsiveness.
Solution Approach 2:
The sampling rate is dynamically adjusted based on device orientation and environmental conditions. When the device is in orientations where the sensor is likely unobstructed, higher sampling rates are used for faster response. When orientations suggest potential obstruction or during stable lighting conditions, sampling rate decreases to conserve power. This dynamic adjustment resolves the contradiction between speed and energy consumption.
3Adaptability or versatility
If the backlight adjusts frequently in response to light sensor readings, then the display adaptability to lighting changes is improved, but constant state transitions cause instability and user discomfort
Solution Approach 1:
The system performs preliminary assessment of light sensor readings against hysteresis thresholds before triggering backlight state transitions. Instead of immediately responding to every light level change, the system first checks whether the change exceeds predefined thresholds that account for normal fluctuations. This preliminary filtering action prevents unnecessary transitions while maintaining adaptability to genuine lighting changes.
Solution Approach 2:
The system implements feedback mechanisms through hysteresis thresholds that prevent oscillation between backlight states. When the light level crosses a threshold to trigger a state change, a corresponding reverse threshold is set that must be crossed before the next state change can occur. This feedback loop stabilizes the system by requiring significant lighting changes to trigger transitions, thereby preventing constant state flipping while preserving adaptability to sustained lighting variations.
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 method effectively maintains readable screen brightness across different environments and orientations, ensuring reliable backlight operation by filtering out brief lighting fluctuations and adjusting gradually to prevent constant state transitions, thus enhancing user experience and reducing eye strain.
Implementation Method 1
a light sensor for sampling ambient light conditions
Implementation Method 2
an orientation sensor and a display... determining orientation of said device
Data Source
AI summary
A method is set forth for automatically adjusting display brightness on a mobile electronic device having a light sensor, display screen and orientation sensor, for legibility under varying lighting conditions and orientations of the device. The method includes obtaining light level samples from the light sensor, and orientation from the orientation sensor, and adjusting backlight intensity of the display responsive to the light level samples and orientation of the device. Preferably, backlight adjustments are made from dim to bright notwithstanding orientation of the device whereas adjustments from bright to dim are made only for orientations of the device where the light sensor is unlikely to be covered.