Rotation Detector Signal Processing Circuit with Adaptive Waiting Time
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Solution Overview
Problem
Conventional signal processing circuits for rotation detectors face challenges in accurately detecting rotational motion when the rotational direction changes frequently, leading to a lack of output pulses or unnecessary pulses, especially when the rotational direction is changed with a short period.
Innovation Solution
A signal processing circuit for a rotation detector that includes two magnetic sensors and a logic circuit with specific modules to determine the rotational direction and output pulses based on phase relationships, effective edges, and waiting times to prevent pulse masking and chattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the first pulse of the rotation detecting signal Sa after the change of rotational direction is masked to prevent unnecessary pulses, then the signal level changes are controlled, but the rotational motion detection accuracy deteriorates
Solution Approach 1:
The patent segments the pulse handling into two distinct phases: a waiting period during which the first pulse is masked to prevent unnecessary pulses, and a resumption period after the waiting time elapses where pulse detection is restored to maintain detection accuracy. This temporal segmentation resolves the contradiction by applying different pulse masking strategies at different times.
Solution Approach 2:
The patent implements periodic pulse masking based on rotational direction changes. The masking action is applied periodically - initially masking the first pulse after direction change, then stopping masking after a predetermined waiting time. This periodic application of masking prevents unnecessary pulses while allowing accurate detection to resume, resolving the technical contradiction.
2Object-generated harmful factors
If the first pulse is masked to prevent chattering during successive direction changes, then unnecessary pulse output is reduced, but the detection of rotational motion during short-period changes is lost
Solution Approach 1:
The patent applies preliminary pulse masking when a rotational direction change is detected. The first pulse after the direction change is masked in advance to prevent chattering. However, the system prepares for resumption by setting a waiting time counter that will automatically restore pulse detection after the predetermined period, thus preventing chattering while maintaining detection reliability through this preliminary and temporary action.
Solution Approach 2:
The patent makes the pulse masking dynamic rather than static. The masking state changes over time based on the waiting time counter - initially masked to prevent chattering during successive direction changes, then dynamically restored after the predetermined waiting time elapses. This dynamic adjustment allows the system to adapt to different rotational patterns, preventing chattering while maintaining detection reliability.
3Stability of the object's composition
If pulse masking is applied after rotational direction change to control signal levels, then signal stability is improved, but the output pulse quantity is reduced
Solution Approach 1:
The patent implements periodic pulse masking that is temporarily applied after rotational direction changes to ensure signal stability. The masking is not continuous but periodic - applied during the waiting period after direction change, then stopped after the predetermined waiting time. This periodic application maintains signal stability when needed while preserving output pulse quantity during normal operation.
Solution Approach 2:
The patent applies pulse masking locally to specific pulses (the first pulse after direction change) rather than to all pulses continuously. The masking is applied only to the specific local case of post-direction-change pulses to ensure signal stability, while normal pulse output continues uninterrupted during steady-state rotation. This localized approach maintains signal stability without excessively reducing output pulse quantity.
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
The circuit effectively restricts the lack of output pulses when rotating in one direction and prevents unnecessary pulses during successive rotational direction changes with short periods, ensuring accurate detection of rotational motion.
Implementation Method 1
The first magnetic sensor and the second magnetic sensor are arranged opposite a rotating object having gear teeth. The first magnetic sensor and the second magnetic sensor respectively output a first sensor signal and a second sensor signal in accordance with movement of top lands and bottom lands of the gear teeth
Data Source
AI summary
A signal processing circuit for a rotation detector includes a normal-rotation pulse request holding portion, a reverse-rotation pulse request holding portion, a resetting portion, and a waiting time switching portion. When an output of one of a normal-rotation pulse and a reverse-rotation pulse is finished and a waiting time elapses, the resetting portion resets an output request signal of the one of the normal-rotation pulse and the reverse-rotation pulse held by one of the pulse request holding portions. The waiting time switching portion sets the waiting time to a first waiting time when one of the pulse request holding portions holds the output request signal, and the waiting time switching portion sets the waiting time to a second waiting time longer than the first waiting time when both the pulse request holding portions hold the output request signals.