Angular Rate Sensor Amplifier Saturation Prevention

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Solution Overview

Problem

Angular rate sensors with differential and synchronous detection circuits face saturation issues when excessive impacts are applied, leading to incorrect outputs due to varying amplification rates and saturation voltages, which can result in false detection.

Innovation Solution

A physical quantity sensor design with a first amplifier circuit and a second amplifier circuit, where the dynamic range of the second amplifier circuit is greater than the first, and the saturation voltage to amplification rate ratio of the second circuit is higher than that of the first, preventing saturation and ensuring accurate output even under excessive conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the amplification rate of the differential amplifier decreases to prevent saturation under excessive impact, then the output saturation is prevented, but the amplification rate of the synchronous detection circuit increases and may exceed its saturation voltage, causing output saturation and incorrect sensor readings

Engineering Contradiction:

Improveoutput accuracyVSAvoidsaturation voltage limitation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the amplification function into two separate stages: a first amplifier circuit (differential amplifier) and a second amplifier circuit (synchronous detection circuit). Each circuit has its own amplification rate that can be independently controlled. This segmentation allows the system to prevent saturation in one circuit without necessarily causing saturation in the other, as each stage processes signals at different amplification levels.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different amplification rates to different parts of the signal processing system. The first amplifier circuit uses a first amplification rate while the second amplifier circuit uses a second amplification rate. This local differentiation of amplification characteristics allows each circuit to be optimized for its specific function and prevents saturation in the second circuit even when the first circuit's amplification is reduced under excessive impact conditions.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the dynamic range of amplifier circuits is limited, then the circuit design remains simple, but the sensor cannot accurately detect angular rates beyond the normal detection range under excessive impact conditions

Engineering Contradiction:

Improvedetection rangeVSAvoidamplifier circuit configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the amplification function across two separate amplifier circuits, each with its own dynamic range characteristics. The first amplifier circuit handles initial signal amplification while the second amplifier circuit provides additional amplification stage. This segmentation enables the system to achieve an extended effective dynamic range that exceeds what a single amplifier circuit could provide, allowing accurate detection even under excessive impact conditions without requiring a single complex high-range amplifier.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9927238B2Physical quantity sensor, electronic apparatus, and moving object

Publication Date: 2018.03.27 SEIKO EPSON CORP

AI summary

Dynamic range of a second amplifier which is provided in a subsequent stage of a synchronous detection circuit is set greater than dynamic range of a first amplifier which is provided in a preceding stage of the synchronous detection circuit, and thus, an output is prevented from being saturated.