Sensor Hysteresis Restoration Circuit
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Solution Overview
Problem
Sensors face ambiguity in output when powered on after being shut down, particularly when the input signal is within the hysteresis region, leading to incorrect counting of rotations or positions in motor control systems.
Innovation Solution
The sensor includes a threshold comparison circuit that determines if the sensing signal is within the hysteresis range upon powering on and sets the digital value to a predetermined value based on the hysteresis restoration state, ensuring consistent output by restoring the previous hysteresis state before shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the sensor employs hysteresis feature to avoid switching glitches, then the output stability is improved, but the device complexity increases due to additional circuit components
Solution Approach 1:
The patent stores the previous hysteresis state in memory before power-down occurs. When power is restored, this stored state is retrieved and used to initialize the hysteresis circuit, preventing ambiguity without requiring complex real-time detection circuits. The preliminary storage of state information resolves the contradiction by preparing the necessary data in advance.
Solution Approach 2:
The patent introduces a microcontroller or control circuit as an intermediary that manages the hysteresis state storage and restoration process. This intermediary component coordinates between the sensing elements, memory, and hysteresis circuit, simplifying the overall system architecture while maintaining output stability through controlled state management.
2Use of energy by moving object
If the sensor is powered off to reduce power consumption, then the energy usage is reduced, but the hysteresis state is lost leading to output ambiguity upon power-on
Solution Approach 1:
Before powering off the sensor, the current hysteresis state is stored in non-volatile memory. This preliminary action ensures that when power is restored, the sensor can retrieve the stored state and restore it to the hysteresis circuit, preventing output ambiguity. The state information is preserved during the power-off period, resolving the information loss problem while maintaining low power consumption.
Solution Approach 2:
The patent changes the operational state of the memory element from active to standby or deep sleep mode during power-off periods, maintaining the stored hysteresis state with minimal power consumption. Upon power-on, the memory transitions back to active state, allowing rapid retrieval of the stored state. This parameter change enables persistent state storage with negligible power usage during off-periods.
3Measurement precision
If the sensor restores hysteresis state upon power-on, then the measurement accuracy is improved by avoiding output ambiguity, but the device complexity increases due to additional memory and control circuits
Solution Approach 1:
The hysteresis state is stored in memory before power-down, and this stored state is automatically retrieved and applied upon power-on. This preliminary storage action ensures measurement accuracy is restored without requiring complex real-time analysis circuits. The system uses simple read-back of stored state information, minimizing additional circuit complexity while maintaining precision.
Solution Approach 2:
The sensor system performs self-restoration of its hysteresis state using internally stored information. The microcontroller or control circuit automatically retrieves the stored state and reinitializes the hysteresis circuit without external intervention. This self-service approach maintains measurement accuracy while avoiding the need for external calibration equipment or complex restoration algorithms.
4Use of energy by moving object
If the sensor employs power reduction features by powering off components, then the power consumption is reduced, but the reliability decreases due to potential state loss and startup ambiguity
Solution Approach 1:
Before power-down, the sensor stores its operational state including hysteresis information in non-volatile memory. This preliminary action ensures that when power is restored, the sensor can reliably retrieve and restore its previous state, eliminating startup ambiguity. The reliability is maintained through this advance preparation, allowing aggressive power reduction without sacrificing operational consistency.
Solution Approach 2:
The system implements a feedback mechanism where the restored hysteresis state is verified upon power-on to ensure correct restoration. The microcontroller monitors the restored state and can detect any anomalies, providing a feedback loop that enhances reliability. This feedback verification ensures that power reduction cycles do not compromise system reliability.
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 approach prevents incorrect output and ensures accurate counting of rotations or positions by maintaining the hysteresis state, reducing ambiguity and improving sensor reliability.
Implementation Method 1
Many sensors generate analog signals and compare the analog signals to a threshold to generate a digital output signal. Such sensors often employ a hysteresis feature to avoid undesirable switching glitches when generating digital output signals.
Data Source
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Figure 2A
AI summary
Described embodiments provide circuits, systems and methods for generating a sensing signal in response to an ambient condition, comparing the sensing signal to a threshold hysteresis range to generate a digital signal (104'), and upon powering on the sensor (102'), determining whether the sensing signal (203a,203b, 203c) is within the threshold hysteresis range and, if the sensing signal is within the threshold hysteresis range (310), setting the digital signal to a predetermined level based on a hysteresis restoration state associated with the sensor before the sensor has been powered off.