Hand Position Detection for Wristwatch Power Conservation

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Solution Overview

Problem

Conventional hand position detecting devices for timepieces consume significant battery power when left in darkness due to repeated detection attempts, leading to inefficient energy usage.

Innovation Solution

A hand position detecting device equipped with an optical detection unit, a darkness detector, and a hand rotation controlling unit that determines if the device has been in darkness for a predetermined time, allowing for controlled hand rotation to a reference position and reduced detection frequency, thereby conserving power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the hand position detecting device continuously detects hand positions in darkness, then detection accuracy is maintained, but battery power consumption increases significantly

Engineering Contradiction:
Improvehand position detection accuracyVSAvoidbattery power consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic detection by controlling the detecting unit to operate only at predetermined time intervals during darkness conditions. The control unit determines whether continuous detection is necessary based on darkness duration and hand position information, switching between continuous and periodic detection modes to optimize power consumption while maintaining adequate detection accuracy.

Inventive Principle:
Principle #19Periodic action

2Measurement precision

If the hand position detecting device rotates hands to reference position in darkness, then hand position accuracy is ensured, but device complexity increases

Engineering Contradiction:
Improvehand position accuracyVSAvoidcontrol mechanism complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs a self-service mechanism where the detecting unit itself provides the solution by detecting hand positions and transmitting this information to the control unit. The control unit then autonomously determines whether hand rotation to reference position is necessary, eliminating the need for external intervention or complex additional control mechanisms.

Inventive Principle:
Principle #25Self-service

3Reliability

If the hand position detecting device performs repeated detections in darkness, then detection reliability is improved, but time consumption increases

Engineering Contradiction:
Improvedetection reliabilityVSAvoiddetection time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by having the detecting unit detect hand positions and the control unit store this information in advance during darkness periods. This pre-detected information is then used to determine whether continuous detection or hand rotation is necessary, reducing the need for repeated detections and minimizing time consumption while maintaining detection reliability.

Inventive Principle:
Principle #10Preliminary action

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 effectively reduces battery power consumption by minimizing unnecessary detections when the device is in darkness, ensuring accurate hand position detection while optimizing energy usage.

Implementation Method 1

an optical detection unit configured to detect whether or not light passes through light-passing apertures provided in hand wheels having hands

Methodology Applied
Scientific EffectLight transmission: Light

Data Source

PatentEP2128720B1Hand position detecting device and hand position control method
Publication Date: 2012.09.26 CASIO COMPUTER CO LTD
  • EP2128720B1 patent drawingFigure 1
  • EP2128720B1 patent drawingFigure 2
  • EP2128720B1 patent drawingFigure 3

AI summary

A solar panel (9) determines whether or not a wristwatch (1) is in darkness. When the darkness has continued for a predetermined time period, e.g., for 61-70 minutes, it is determined that the wristwatch (1) is not in use and set in a sleep state. Out of seconds, center and hour hands (2, 3 and 4), at least the seconds hand (2) is rotated to a reference position (00-second position) and stopped, and positions of the center and hour hands (3 and 4) are detected. Therefore, power consumption during can be reduced when the wristwatch (1) is not in use.