Optical Navigation Motion Scaling for Asynchronous USB Reporting
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Solution Overview
Problem
Conventional optical navigation devices face issues due to asynchronous sensor and USB report rates, resulting in inconsistent motion report sizes and user experience problems, such as non-constant speed when controlling icons.
Innovation Solution
An optical navigation system and method that scales motion reports to correspond to a fixed time interval by calculating and reporting motions at specific times based on image frames, using a control circuit to determine scaled motions from the reported motions and time differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sensor report rate is asynchronous with the USB report rate, then the optical navigation device can operate with flexible sensor timing, but the motion report sizes become inconsistent causing non-constant speed perception
Solution Approach 1:
The system dynamically adjusts the motion report scaling factor based on the time interval between image frames. The control circuit calculates a scaled motion value that compensates for variable time intervals, transforming the fixed USB report rate into dynamically adjusted motion values that reflect actual device movement, thereby resolving the contradiction between flexible sensor timing and consistent motion perception.
Solution Approach 2:
The patent changes the parameter of motion report values by introducing a scaling factor that adjusts the motion magnitude based on the actual time interval. Instead of reporting raw motion values that vary with timing, the system transforms these values into scaled motion values that normalize the perception of constant speed, thus resolving the inconsistency caused by asynchronous reporting rates.
2Productivity
If motion reports correspond to different time intervals, then the device can report motions as they are captured, but the report sizes vary causing user experience issues
Solution Approach 1:
The control circuit acts as an intermediary between the motion reporting device and the host device. It receives raw motion values and time interval information, calculates a scaled motion value that accounts for the variable time interval, and transmits this corrected value to the host. This intermediary processing ensures that all USB reports have consistent sizing and represent equivalent time periods, eliminating user experience issues while maintaining efficient reporting.
3Stability of the object's composition
If USB reports are generated at fixed time intervals, then the reporting rhythm is stable, but the reports may correspond to different numbers of image frames causing inconsistent motion data
Solution Approach 1:
The system uses feedback from the actual time interval measurement to adjust the motion report values. The motion reporting device provides timing information along with motion data, and the control circuit uses this feedback to calculate the appropriate scaling factor. This closed-loop approach ensures that while USB reports are generated at fixed intervals, the motion values accurately reflect the actual device movement by compensating for variations in the number of image frames captured during each interval.
Data Source
AI summary
An optical navigation system comprising a control circuit and an optical navigation device. The optical navigation device comprises: an image sensor, configured to generate a plurality of image frames; and a motion reporting device, configured to report a first motion of the optical navigation device to the control circuit at a first time after a reference time, and configured to report a second motion to the control circuit at a second time after the first time. The first motion and the second motion are calculated according to the image frames. The control circuit calculates a first scaled motion according to the first motion, the second motion, a first time difference between the first time and the reference time, and a second time difference between the first time and the second time.