Spiral Solar Cells for Timepiece Pointer Light Blocking

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The existing solar panels in pointer-type timepieces suffer from a significant loss of output current due to the uneven light-receiving areas caused by the pointer, which results in the smallest light-receiving area determining the overall output current, leading to inefficient power generation.

Innovation Solution

The solar panel is designed with a circular arrangement of solar cells divided into spiral shapes, ensuring that the pointer, specifically the minute hand, consistently covers equal areas of two or more solar cells, thereby distributing the light-blocking effect evenly across multiple cells, connected in series to minimize electrical resistance and maximize light exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If solar cells are arranged in a circular pattern with a pointer shaft in the center, then the pointer can move above the solar cells to indicate time, but the pointer blocks light from reaching the solar cells directly beneath it, causing unequal light-receiving areas and reducing overall output current

Engineering Contradiction:
Improvepointer indication functionVSAvoidoutput current loss
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The solar panel is divided into multiple fan-shaped solar cells arranged circularly around the pointer shaft. Each solar cell is positioned at a different angular position, so when the pointer blocks light from one cell, other cells remain exposed. This segmentation distributes the light-blocking effect across multiple cells rather than concentrating it on a single cell, maintaining more consistent overall power generation.

Inventive Principle:
Principle #1Segmentation

2Productivity

If solar cells are arranged to maximize light exposure, then power generation efficiency is improved, but the pointer shaft and pointer structure become more complex to accommodate the circular arrangement

Engineering Contradiction:
Improvepower generation efficiencyVSAvoidsolar panel structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The solar cells are arranged in a circular pattern around the central pointer shaft, with each cell shaped like a fan segment. This curved, radial arrangement allows the pointer to rotate freely in the center while each solar cell captures light from its specific angular position. The circular geometry naturally accommodates the rotating pointer while maximizing the light-exposing surface area of all solar cells combined.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 increases the overall output current by distributing the light-blocking effect across multiple solar cells, maintaining consistent output current and reducing power generation losses, while ensuring equal light-receiving areas for each cell, thus enhancing power generation efficiency.

Implementation Method 1

a solar panel (3) having a plurality of solar cells (11 to 16) arranged in a circular shape

Methodology Applied
Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Data Source

PatentEP2965363B1Solar panel and timepiece including solar panel
Publication Date: 2017.06.07 CASIO COMPUTER CO LTD
  • EP2965363B1 patent drawingFigure 1
  • EP2965363B1 patent drawingFigure 2A~2C
  • EP2965363B1 patent drawingFigure 3

AI summary

A solar panel (3) of the present invention, above which a pointer (7) mounted on a pointer shaft (6) inserted in a through hole (3a) in a center portion of the solar panel moves, includes a plurality of solar cells (11-16) arranged in a substantially circular shape, and these solar cells (11-16) have been divisionally formed into a substantially spiral shape so that the pointer is positioned over two of the plurality of solar cells (11-16). Accordingly, the pointer (7) can always be positioned over two of the plurality of solar cells (11-16), and therefore a decrease of light-receiving area due to the pointer (7) can be distributed between the two solar cells (11-16). As a result, a decrease in the output current of the plurality of solar cells (11-16) over which the pointer (7) is positioned can be suppressed, and the output current of the entire plurality of solar cells (11-16) can be improved.