Optical Fingerprint Sensing Device with Temperature Compensation
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Solution Overview
Problem
Conventional fingerprint identification sensors in smartphones, especially those integrated into OLED panels, are sensitive to environmental conditions such as temperature variations, leading to distorted sensing data.
Innovation Solution
An optical fingerprint sensing device comprising optical sensing pixels and optical blocked pixels, along with a readout circuit that uses a differential amplifier to generate output signals by comparing sensing signals from optical sensing pixels with tracking signals from optical blocked pixels, effectively compensating for environmental distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If fingerprint identification sensors are integrated into OLED panels, then frame size is minimized, but sensing data becomes distorted due to temperature variations
Solution Approach 1:
The patent introduces a compensation pixel as an intermediary element that mediates between the temperature-sensitive sensing pixel and the environmental conditions. The compensation pixel, which is not exposed to light, tracks temperature-induced signal changes and provides correction data to eliminate distortion in the fingerprint sensing signal.
Solution Approach 2:
The system implements a feedback mechanism where the compensation pixel continuously monitors environmental condition changes (temperature) and feeds this information back to correct the sensing pixel's output. This closed-loop approach dynamically compensates for temperature variations, maintaining sensing accuracy despite thermal fluctuations in the OLED panel.
2Adaptability or versatility
If environmental conditions change (e.g., heats accumulated in the OLED panel), then sensing data becomes distorted, but integration into display panel is maintained
Solution Approach 1:
The compensation pixel serves as a mediator that isolates the sensing function from environmental interference. By placing a non-light-exposed pixel adjacent to the sensing pixel, the system captures pure environmental effects (temperature) without optical contamination, enabling reliable correction of sensing data under varying thermal conditions.
Solution Approach 2:
The patent converts the harmful effect of temperature variations into a useful signal by using the compensation pixel to track these changes. The same thermal environment that distorts sensing data also affects the compensation pixel in a measurable way, allowing the system to calculate and apply corrections that actually improve reliability under the same environmental conditions.
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 enables precise fingerprint detection that is not affected by environmental factors like temperature variations, improving the accuracy and reliability of fingerprint recognition in various conditions.
Implementation Method 1
Each of the optical sensing pixels includes a first photodevice for sensing an illumination through an optical path
Implementation Method 2
Each of the optical blocked pixels includes a second photodevice blocked from the illumination
Implementation Method 3
Output signals are generated according to differences between the sensing signals and the tracking signals by a differential amplifier
Data Source
AI summary
An optical fingerprint sensing device includes optical sensing pixels, optical blocked pixels and a readout circuit. Each of the optical sensing pixels includes a first photodevice for sensing an illumination through an optical path. The optical sensing pixels are configured to generate sensing signals. Each of the optical blocked pixels includes a second photodevice blocked from the illumination. The optical sensing pixels are configured to generate a plurality of tracking signals. The readout circuit is configured to generate output signals according to differences between the sensing signals and the tracking signals.