Stepping Motor Control Circuit for Analog Timepiece Rotation Detection

Solution Overview

Problem

Existing stepping motor control circuits in analog electronic timepieces face challenges in accurate rotation detection due to load variations, leading to false detection and increased power consumption.

Innovation Solution

A stepping motor control circuit that detects induced currents through a drive coil in divided sections, using a pattern to determine rotation states based on detection time and current levels, and selects appropriate drive pulses to maintain accurate rotation detection and reduce power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If rotation detection is performed using induced signal detection in a stepping motor, then rotation state can be detected, but accurate detection becomes difficult when load variation is large

Engineering Contradiction:

Improverotation detection accuracyVSAvoidload variation tolerance

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The detection section is divided into multiple sections, and the polarity determination is performed separately in each section. This segmentation allows the system to analyze the induced signal pattern across different time intervals, making the rotation detection more robust against load variations that might affect a single detection point.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs periodic polarity determination by dividing the detection section into multiple sections and evaluating the induced signal in each section sequentially. This periodic evaluation approach enables accurate rotation detection even when load conditions change, as the system samples the signal at multiple periodic intervals.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If detection section is divided into multiple sections for rotation detection, then detection accuracy improves, but detection process complexity increases

Engineering Contradiction:

Improverotation detection accuracyVSAvoiddetection process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The detection section is divided into multiple sections, and the polarity determination is performed separately in each section. This segmentation allows the system to analyze the induced signal pattern across different time intervals, making the rotation detection more robust against load variations that might affect a single detection point.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs periodic polarity determination by dividing the detection section into multiple sections and evaluating the induced signal in each section sequentially. This periodic evaluation approach enables accurate rotation detection even when load conditions change, as the system samples the signal at multiple periodic intervals.

Inventive Principle:

Principle #19Periodic action

3Reliability

If false rotation detection occurs due to load variation, then correction drive pulse is incorrectly applied, but power consumption increases and battery lifetime decreases

Engineering Contradiction:

Improverotation detection reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system performs periodic polarity determination by dividing the detection section into multiple sections and evaluating the induced signal in each section sequentially. This periodic evaluation approach enables accurate rotation detection even when load conditions change, as the system samples the signal at multiple periodic intervals.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system uses feedback from the induced signal polarity detection to determine whether to apply correction drive pulses. By accurately detecting the rotation state through multi-section analysis, the system provides correct feedback signals that prevent false triggering of correction pulses, thereby reducing unnecessary power consumption and extending battery life.

Inventive Principle:

Principle #23Feedback

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 solution enables accurate rotation detection by minimizing the effect of load variations, ensuring precise hand movement and reducing power consumption in analog electronic timepieces.

Implementation Method 1

detects an induced current flowing through a drive coil due to free vibration of a stepping motor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9190941B2Stepping motor control circuit, movement, and analog electronic timepiece

Publication Date: 2015.11.17 SEIKO WATCH CORP

AI summary

A rotation detection circuit detects an induced current flowing through a drive coil of a stepping motor in a detection section divided into a plurality of sections, and detects a rotation state of the stepping motor on the basis of a pattern indicating whether or not the induced current exceeds a predetermined reference value in each of the sections. A control unit selects a drive pulse corresponding to the rotation state detected by the rotation detection unit, and supplies a drive current to a drive coil to rotatably drive the stepping motor. The rotation detection unit carries out detection by selecting a detection direction of the induced current in the sections after the first section on the basis of whether or not the induced current exceeding each of a plurality of reference values is detected plural times in the first section.