Omnipolar Schmitt Trigger Sensor Using Polarity Inversion

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Solution Overview

Problem

Existing omnipolar magnetic switch sensors require multiple components and are costly due to their need for separate detection mechanisms for magnetic fields of different polarities, limiting their versatility and efficiency.

Innovation Solution

A sensor design featuring a magnetic field sensing element, a switching circuit that changes the polarity of the magnetic field signal at a predetermined frequency, and a comparison device that generates an output signal based on threshold crossings, allowing for detection of magnetic fields of either polarity using a single comparison device, thereby reducing component count and size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If separate detection mechanisms are used for magnetic fields of different polarities, then detection accuracy is improved, but device complexity and cost increase

Engineering Contradiction:

Improvedetection accuracyVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies inversion by switching the polarity of the magnetic field signal itself rather than switching the detection mechanism. The magnetic field signal polarity is inverted at a predetermined frequency, allowing a single comparison device to detect both north and south polarities by comparing the inverted signal against a reference level, thereby reducing device complexity while maintaining detection accuracy

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The comparison device is designed to perform multiple functions: it compares both positively polarized and negatively polarized magnetic field signals against a reference level, enabling a single device to detect magnetic fields of either polarity. This multi-functionality eliminates the need for separate detection mechanisms for different polarities

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple components are used for omnipolar detection, then detection capability is improved, but sensor size increases

Engineering Contradiction:

Improveomnipolar detection capabilityVSAvoidsensor size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent merges the detection of both magnetic polarities into a single comparison device. By combining the reference level comparison function for both north and south polarities into one device and using a single magnetic field sensing element, the sensor achieves omnipolar detection capability with reduced size compared to using separate detection mechanisms for each polarity

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If separate detection mechanisms are used for different polarities, then detection reliability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvedetection reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The comparison device is designed as a universal component that reliably detects both magnetic polarities through reference level comparison. This single multi-functional device replaces what would traditionally require multiple specialized components, reducing manufacturing complexity and cost while maintaining detection reliability across both polarities

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 configuration enables the sensor to detect magnetic fields in any direction with reduced size and cost, while maintaining accurate switchpoint characteristics and sensitivity to magnetic field strengths of both polarities, enhancing its applicability in various orientations and motions.

Implementation Method 1

a magnetic field sensing element configured to generate a magnetic field signal in response to a sensed magnetic field

Methodology Applied

Scientific EffectMagnetic field sensing: Hall Effect

Data Source

PatentUS10627458B2Omnipolar schmitt trigger

Publication Date: 2020.04.21 ALLEGRO MICROSYSTEMS LLC

AI summary

A sensor is provided having a magnetic field sensing element to generate a magnetic field signal, a switching circuit coupled to receive the magnetic field signal and generate a switching signal that changes a polarity of the magnetic field signal at a predetermined frequency, and a comparison device configured to receive the switching signal and generate an output signal that changes a level in response to the switching signal crossing a predetermined threshold. The switching circuit is disposed between the magnetic field sensing element and the comparison device and can provide the comparison device an input signal (i.e., the switching signal) that changes polarity at the predetermined frequency. The comparison device can sense characteristics, such as but not limited to crossing operate and release threshold levels, of both north and south polarity magnetic field signals using the switching signal.