Offset Cancelling Circuit for Hall Element Using Four-State Averaging
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Solution Overview
Problem
Existing offset cancelling circuits for Hall elements fail to accurately cancel output voltage offsets due to voltage dependency of resistors R1-R4, as they assume no change in resistor values between different states.
Innovation Solution
An offset cancelling circuit that applies voltages from four directions and switches current flowing in the Hall element by 90° through four states, averaging the output voltages across these states to cancel the offset value, utilizing a structure with switching elements, amplifiers, and capacitors to account for voltage dependency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional offset cancelling circuit is used that assumes no change in resistor values, then the circuit structure is simple, but the offset cancellation accuracy deteriorates due to voltage dependency of resistors
Solution Approach 1:
The patent segments the offset cancellation process into four distinct measurement states, where each state measures the offset under specific voltage conditions. By dividing the cancellation process into multiple discrete measurements and averaging them, the circuit achieves accurate compensation for voltage-dependent resistor variations without requiring complex real-time adjustment mechanisms.
Solution Approach 2:
The patent changes the voltage parameters applied to the Hall element across four different states, measuring the offset at each voltage condition. By varying the voltage parameters systematically and averaging the results, the circuit compensates for the voltage dependency of resistors R1-R4, achieving high precision offset cancellation while maintaining relatively simple circuit structure.
2Measurement precision
If the current flowing in the Hall element is switched by 90° through four states to account for voltage dependency, then the offset cancellation accuracy is improved, but the operation time increases
Solution Approach 1:
The patent employs periodic action by systematically cycling through four distinct voltage states in a predetermined sequence. Each state is maintained for a specific duration to allow accurate measurement, then transitions to the next state. This periodic measurement approach ensures comprehensive coverage of voltage-dependent effects while maintaining efficient timing, as the four states can be executed in rapid succession.
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
Effectively cancels both voltage-dependent and independent offset values in the output voltage of the Hall element, ensuring accurate signal correction and high-quality image capture.
Implementation Method 1
a Hall element is used for detecting a position of the optical component such as the lens which is driven
Data Source
AI summary
In an offset cancelling circuit of a Hall element, a voltage is applied from four directions and from outside such that a current flowing in the Hall element is switched by 90°, to set a first state through a fourth state, and output voltages of the Hall element in the first state through the fourth state are averaged.