IC Card Low Precision Clock for Power Saving
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Solution Overview
Problem
IC Cards face challenges in measuring time independently of a reader device, especially during power-saving modes where the clock signal is suspended, and rely on potentially untrusted host devices for timer services, leading to security vulnerabilities and power consumption issues.
Innovation Solution
Incorporating a low precision clock within the IC Card that remains active during clock stop status to measure time, activated only when necessary, reducing power consumption and avoiding reliance on external timer services.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the clock signal is suspended during power-saving mode, then power consumption is reduced, but the IC Card loses awareness of elapsed time
Solution Approach 1:
The patent divides the clock system into two independent parts: an external high-precision clock from the reader device and an internal low-precision clock within the IC Card. The internal clock specifically measures time during clock stop periods, while the external clock handles normal operation timing, allowing time measurement to continue even when power is reduced
Solution Approach 2:
The internal low-precision clock acts as an intermediary that bridges the gap between the external clock suspension and the need for time measurement. It takes over time measurement functionality when the external clock is stopped, ensuring continuous time awareness without requiring full power
2Device complexity
If the IC Card relies on external host device for timer service, then internal time measurement can be avoided, but security vulnerabilities arise from untrusted host devices
Solution Approach 1:
The IC Card performs time measurement independently using its own internal low-precision clock during clock stop status, rather than relying on external host device timer services. This self-service approach ensures the IC Card maintains time awareness and security control even when disconnected from or interacting with potentially untrusted external devices
3Measurement precision
If the internal clock remains active continuously, then time measurement is always available, but power consumption increases
Solution Approach 1:
The internal low-precision clock operates periodically rather than continuously - it is activated specifically during clock stop status when the external clock is suspended, and remains inactive during normal operation when the external clock is running. This periodic activation maintains time measurement availability while minimizing power consumption
Data Source
AI summary
An IC Card may include electronic components to receive a power supply and a main clock signal by a reader device. The power supply may be provided to a subset of the electronic components during a main clock stop status wherein the main clock signal is suspended for avoiding a maximum power consumption threshold. The IC Card may also include a low precision clock included in the subset of electronic components for measuring time in the main clock stop status.