LED Current Ramping for Optical Mouse Power Management
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Solution Overview
Problem
Standard optical mice consume excessive power due to constant LED current settings, which are not optimized for varying speeds, leading to inefficient power management at low speeds.
Innovation Solution
Implementing a speed-related current setting for the optical mouse LED by determining the mouse speed, setting control bits, and adjusting the current through a constant current LED driver using a digital circuit to selectively open and close switches, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant high LED current setting is maintained across all speeds, then image quality and tracking performance are improved at high speeds, but power consumption increases unnecessarily at low speeds
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant current setting to a dynamic current ramping system that adjusts LED current based on detected motion speed. The digital circuit ramps the current up or down in discrete steps according to the mouse's speed, allowing the system to adapt its power consumption and performance characteristics to match actual operational conditions.
Solution Approach 2:
The patent changes the electrical parameter (LED current) from a fixed constant value to a variable parameter that changes in discrete steps. The digital circuit controls current ramping through multiple stages, adjusting the current parameter dynamically based on speed detection, thereby optimizing both performance and power efficiency.
2Manufacturing precision
If a constant high LED current is used, then image blurring is reduced at high speeds, but unnecessary power is consumed at low speeds
Solution Approach 1:
The system dynamically adjusts LED current based on real-time speed detection, transitioning from a static high-current mode to a dynamic multi-level current system. This allows the LED current to be optimized for each speed condition, reducing image blurring at high speeds while minimizing power waste at low speeds.
Solution Approach 2:
The LED current parameter is changed from a fixed high value to a variable parameter that changes in discrete steps. The digital circuit implements current ramping through multiple stages, allowing the current parameter to be adjusted according to speed, thereby optimizing image quality while reducing energy loss.
3Loss of time
If LED current is increased, then pre-flash time is reduced at high speeds, but power consumption increases overall
Solution Approach 1:
The patent implements dynamic current adjustment where the LED current is ramped up or down in discrete steps based on detected speed changes. This dynamic response allows pre-flash time to be reduced at high speeds when necessary, while avoiding unnecessary power consumption at low speeds where high current provides no additional benefit.
Solution Approach 2:
The LED current parameter is changed from a constant high value to a variable parameter that changes in discrete steps. By adjusting the current parameter dynamically based on speed, the system reduces pre-flash time at high speeds while minimizing overall power consumption.
Data Source
AI summary
An LED current ramping method for an optical mouse includes: determining a speed of the optical mouse; setting control bits according to the determined speed; sending the control bits to a digital circuit of the mouse; and decoding the control bits to selectively open and close switches in a constant current LED driver of the mouse to adjust a current according to the speed.