Ambient Light Sensor Behind OLED Display
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ambient light sensors behind OLED displays face challenges in accurately detecting ambient light due to interference from light generated by the display itself, leading to undesirable fluctuations in display brightness.
Innovation Solution
A processor is used to estimate the light signal generated by the display and subtract it from the combined light signal detected by the ambient light sensor, allowing for the calculation of an ambient light value to control display brightness effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the ambient light sensor is disposed behind the OLED display screen to maximize screen area and reduce bezel width, then the screen area is increased and bezel width is reduced, but the sensor cannot accurately detect ambient light due to interference from display-generated light
Solution Approach 1:
The patent segments the detected light signal into two distinct components: display-generated light and ambient light. By separating these signals through frequency analysis, the system can accurately measure ambient light despite the sensor's position behind the display.
Solution Approach 2:
The patent intentionally allows the sensor to detect excessive light (including display-generated light) and then selectively removes the unwanted portion through signal processing. This approach enables accurate ambient light detection by subtracting the display light component from the total detected signal.
2Illumination intensity
If the protective film on the OLED backside is removed in a very small area to allow light passage, then ambient light can reach the sensor, but the OLED remains not very optically transmissive requiring a very sensitive sensor
Solution Approach 1:
The system uses feedback from the display controller to provide information about display-generated light characteristics to the sensor processing system. This feedback enables accurate subtraction of the display light component, allowing reliable ambient light detection even through the opaque OLED structure.
3Productivity
If the ambient light sensor detects both ambient light and display-generated light, then the sensor provides continuous light detection data, but the display brightness fluctuates with changes in pixel brightness above the sensor
Solution Approach 1:
The patent exploits the periodic nature of display refresh cycles to separate display-generated light from ambient light. By analyzing signals at the display refresh frequency, the system can identify and subtract the periodic display light component, leaving only the stable ambient light measurement.
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
This approach enables accurate measurement of ambient light levels, improving the operation of portable devices by stabilizing display brightness and reducing energy consumption.
Implementation Method 1
An ALS sensor will detect not only ambient light (e.g., background light, sunlight, etc.) passing through the display, but will also detect the light generated by the display itself
Data Source
AI summary
Techniques are described for portable computing devices and other apparatus that include an ambient light sensor. The techniques can be particularly advantageous for situations in which the ambient light sensor is disposed behind a display screen of a host device such that ambient light detected by the sensor passes through the light emitting display before being detected by the sensor.