Contactless IC Card Clock Control for Power-Limited Processing
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Solution Overview
Problem
Current contactless communication devices face challenges in optimizing CPU processing speed due to the trade-off between communication distance and processing speed, leading to increased circuit size and processing load, with difficulties in accurately estimating consumption current fluctuations and determining optimal frequency settings.
Innovation Solution
A contactless communication device with a detection unit for absolute surplus current detection, allowing precise control of clock signal frequency based on detected surplus current, reducing processing time and circuit size, and enabling flexible frequency selection without additional circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the internal processing speed of the PICC is increased to decrease processing time, then the processing speed is improved, but the consumption current increases which reduces the communication distance
Solution Approach 1:
The patent implements dynamic clock frequency adjustment where the PICC adapts its operating speed based on real-time power availability. The PCD transmits power level information to the PICC, which then dynamically selects appropriate clock frequencies for different operational phases (reception, processing, transmission) to match the available power budget, resolving the contradiction between speed and energy consumption
Solution Approach 2:
The system changes operational parameters (clock frequency) based on power conditions. Different clock frequencies are assigned to different processing stages depending on the received power level, allowing the system to optimize between speed and energy consumption by adjusting parameters rather than maintaining fixed operation
2Length of stationary object
If the consumption current of the PICC is decreased to increase communication distance, then the communication distance is improved, but the internal processing speed must be decreased
Solution Approach 1:
The system dynamically adjusts clock frequency based on communication distance and power availability. When communication distance requires lower power consumption, the system automatically reduces clock frequency to match the reduced power budget, maintaining optimal operation within available power constraints
Solution Approach 2:
The patent implements periodic power level reporting where the PCD periodically transmits power level information to the PICC. This periodic feedback enables the PICC to adjust its operating parameters in discrete steps, balancing communication distance requirements with processing speed in a controlled manner
3Measurement precision
If a new energy monitoring unit is added to monitor received energy independently from the power generation system, then the detection precision of received power is improved, but the circuit size and power consumption increase
Solution Approach 1:
The patent makes the existing current detection unit serve multiple functions: it detects both the power consumption of the PICC and the received power level from the PCD. By utilizing the same hardware resource for dual purposes, the system achieves precise power monitoring without adding extra circuitry, thus improving measurement precision while avoiding increased device complexity
Solution Approach 2:
The system uses its own power consumption detection capability to infer received power levels. The PICC leverages its inherent current monitoring function to simultaneously measure both its consumption and the power it receives, making the system self-sufficient for power monitoring without external or additional monitoring units
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 solution enables efficient control of clock signal frequency, optimizing data processing speed while maintaining communication distance, reducing processing time, and improving data processing efficiency without increasing circuit size.
Implementation Method 1
the power to the PICC is generated, by electromagnetic induction, from carrier waves supplied from the PCD
Implementation Method 2
A contactless communication device applied to the PICC rectifies a signal inputted from an antenna terminal and supplies a direct current obtained by rectification to a regulator
Data Source
AI summary
There is included a detection unit for detecting a magnitude of a surplus of a direct current to a source voltage generated by a voltage generation unit generating the source voltage from the direct current obtained by rectifying a signal inputted from an antenna terminal. A data processing unit operating at the source voltage and performing data processing on a transmission/reception signal includes a clock control unit for determining a frequency of a clock signal for the data processing based on the magnitude of the surplus current detected by the detection unit in a state where a frequency of the clock signal is set to a predetermined reference frequency. Since the power consumed by the data processing unit at the time of detecting the surplus of the direct current is determined by the specific reference frequency, the surplus of the direct current can be detected as an absolute surplus.