Document Camera Current Control via USB
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Solution Overview
Problem
Document cameras operating with power supplied via USB cables face limitations due to the defined upper current limit, leading to restricted operation and potential underutilization of available current capacity.
Innovation Solution
Incorporating a detection unit to monitor current consumption and a control unit that adjusts the operation of the light source and drive units, allowing the document camera to operate closer to the upper current limit without exceeding it, while maintaining flexibility in lens movement and light brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the operation of the document camera is limited in advance to ensure current consumption does not exceed the USB upper limit value, then the reliability of power supply is improved, but the productivity of the document camera deteriorates as the maximum current consumption drops significantly below the upper limit value
Solution Approach 1:
The patent applies dynamics by transitioning from static predetermined operation limiting to dynamic real-time current monitoring and control. The detection unit continuously monitors current consumption, and the control unit dynamically adjusts operation based on actual current levels, allowing the system to operate closer to the USB upper limit while maintaining reliability through active management rather than conservative fixed limits
Solution Approach 2:
The patent implements feedback by introducing a detection unit that monitors current consumption and feeds this information back to the control unit. This closed-loop feedback mechanism enables the control unit to adjust operations based on real-time current status, optimizing current utilization while preventing exceedance of the USB upper limit value, thereby resolving the contradiction between reliability and productivity
2Productivity
If a separate power cable is provided to the document camera, then the productivity and power availability are improved, but the device complexity increases making the document camera less user-friendly
Solution Approach 1:
The patent applies merging by combining the power transmission function with the existing USB signal cable. Instead of requiring a separate power cable, the system utilizes the USB cable's existing electrical connections to transmit both data and power, thereby reducing cable complexity while maintaining adequate power availability for document camera operations
Data Source
AI summary
A document camera which operates with electric power supplied via a USB cable includes: an image pickup unit which picks up an image of a subject via a lens; a light source unit which emits light toward the subject; a drive unit which drives the lens; a detection unit which detects an amount of current supplied via the USB cable; and a control unit which controls an operation of the light source unit and the drive unit according to the amount of current detected by the detection unit.