Optical Navigation Sensor Segmentation for Liftoff Detection
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Solution Overview
Problem
Conventional optical navigation systems face challenges in detecting liftoff and ambient light without reducing the tracking frame rate, leading to increased power consumption and potential misoperation, especially in high-speed applications like gaming mice.
Innovation Solution
The optical navigation system employs improved timing control for the photosensitive unit, alternating between bright and dark exposure periods within the same image frame to capture and read data, using a single or dual photosensitive units with one unit partially exposed during dark periods to reduce power consumption and maintain frame rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dark frame is inserted between two bright frames for liftoff detection, then liftoff detection capability is improved, but the time gap between bright frames increases thereby reducing the tracking frame rate
Solution Approach 1:
The patent divides the photosensitive unit into multiple regions (first photosensitive unit and second photosensitive unit) where different regions perform different functions simultaneously. The first region captures bright frames for tracking while the second region captures dark frames for liftoff detection, allowing parallel operation without time gaps.
Solution Approach 2:
The patent implements periodic switching between bright and dark exposure within the same image frame period. By alternating exposure timing between different photosensitive unit regions, the system maintains continuous tracking frame rate while periodically capturing dark frames for liftoff detection.
2Reliability
If a dark frame is inserted between two bright frames for liftoff detection, then liftoff detection capability is improved, but power consumption increases due to extended operation time
Solution Approach 1:
The patent segments the photosensitive unit into multiple independent regions that can be controlled separately. This allows the dark frame capture to occur in parallel with bright frame capture in different regions, eliminating the need to extend the overall operation time and thereby reducing power consumption.
Solution Approach 2:
The patent maintains continuous operation of the optical navigation system by performing both bright frame capture and dark frame capture within the same image frame period without interruption. This continuous parallel operation avoids extending the total operation time and reduces power consumption compared to sequential operations.
3Measurement precision
If ambient light detection is implemented using conventional timing control, then detection accuracy is improved, but the tracking frame rate is reduced
Solution Approach 1:
The patent divides the photosensitive unit into dedicated regions for different detection functions. The second photosensitive unit region is specifically allocated for ambient light and liftoff detection, allowing accurate measurements to be performed simultaneously with tracking operations in other regions without compromising frame rate.
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 effectively detects liftoff and ambient light without reducing the tracking frame rate, preventing misoperation and minimizing power consumption, thereby enhancing the performance and efficiency of optical navigation systems.
Implementation Method 1
the image sensor receives light reflected from the working surface
Data Source
AI summary
There is provided an optical navigation system including a light source, a first photosensitive unit, a second photosensitive unit, a control unit and a processing unit. The light source is configured to emit light of a predetermined wavelength. The first photosensitive unit is configured to receive reflected light of the predetermined wavelength reflected by a working surface. The second photosensitive unit is covered with a coating to block light of the predetermined wavelength. The control unit is configured to control the light source, the first photosensitive unit and the second photosensitive unit to expose both the first photosensitive unit and the second photosensitive unit when the light source is turned on. The processing unit is configured to read first image data and second image data respectively from the first photosensitive unit and the second photosensitive unit thereby identifying an ambient light mode or a liftoff mode.