Touch Panel Pressure Path Structure for Wider Switch Range

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Solution Overview

Problem

Existing touch panels have a limited switch range due to their complex configuration and react poorly to presses outside the conductive path area, restricting the size of the switch range and increasing production costs.

Innovation Solution

A touch panel design featuring a first and second sheet with conductive paths and spacers that allow for a wider switch range by using structures with high hardness or stiffness to uniformly sink and transmit pressure, enabling detection beyond the minimum pressure-sensitive regions without the need for transparent conductive films.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If transparent conductive films and parallel wires are provided on both upper and lower substrates to detect depression position, then detection capability is achieved, but device complexity increases and manufacturing cost rises

Engineering Contradiction:
Improvedepression position detectionVSAvoidconfiguration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the complex transparent conductive film and parallel wire configuration from both substrates. Instead, it uses a simplified structure with conductive paths only on the lower substrate and pressure-sensitive ink on the upper substrate, reducing device complexity while maintaining depression detection capability through electrical contact formation upon pressing.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses pressure-sensitive ink as a simplified copy or alternative to the complex transparent conductive film system. The pressure-sensitive ink layer with conductive paths replicates the detection function through a much simpler mechanism: electrical contact between the lower substrate's conductive path and the upper substrate's pressure-sensitive ink upon depression, eliminating the need for complex multi-layer transparent conductive structures.

Inventive Principle:
Principle #26Copying

2Device complexity

If conductive paths are arranged only on specific locations to simplify configuration, then manufacturing cost is reduced, but switch range is limited to approximately 5 mm

Engineering Contradiction:
Improveconfiguration simplicityVSAvoidswitch range
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The invention uses flexible thin film structures for the conductive paths on both substrates. The upper substrate's pressure-sensitive ink layer and the lower substrate's conductive path are designed as flexible thin films that can deform under pressure. This flexibility allows the conductive paths to extend and make contact over a larger area when pressed, expanding the switch range beyond the limitations of rigid conductive structures while maintaining configuration simplicity.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention introduces dynamic deformation of the flexible conductive paths and pressure-sensitive ink layer in response to applied pressure. When force is applied, the flexible upper substrate deforms, causing the pressure-sensitive ink conductive path to contact the lower substrate's conductive path. This dynamic response enables the switch range to expand with the flexibility and deformation capability of the thin film structures, allowing detection over a larger area than static rigid conductive paths would permit.

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If the touch panel structure is simplified by using contact between conductive paths, then manufacturing cost is reduced, but the panel only reacts to pressing in the vicinity of the conductive path

Engineering Contradiction:
Improvemanufacturing costVSAvoidpressure-sensitive area
Core Design Contradiction:
Ease of manufactureVSArea of stationary object

Solution Approach 1:

The invention employs flexible thin film conductive paths on both the upper and lower substrates. The upper substrate's pressure-sensitive ink layer is formed as a flexible thin film that can deform and extend its contact area when pressed. This flexibility allows the conductive path on the upper substrate to make contact with the lower substrate's conductive path over a larger area than the original conductive path location, effectively expanding the pressure-sensitive area while maintaining the simple contact-based detection mechanism and low manufacturing cost.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention utilizes dynamic deformation of the flexible conductive paths during pressing operation. When force is applied to the upper substrate, the pressure-sensitive ink layer deforms dynamically, allowing the conductive path to extend and contact the lower substrate's conductive path at multiple points or over a larger area. This dynamic behavior enables the simple contact-based detection structure to respond to pressing over a broader area, effectively increasing the pressure-sensitive area without adding complexity or cost.

Inventive Principle:
Principle #15Dynamics

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 design simplifies the configuration, expands the switch range, and reduces production costs by allowing presses to be detected across a larger area without additional sensing components, enhancing user interaction and operational flexibility.

Implementation Method 1

an upper pressure sensitive ink member, covering the upper electrode, comes in contact with both of the electrodes on the second sheet and conducts them

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3495927B1Touch panel
Publication Date: 2020.04.22 MITSUBISHI ELECTRIC CORP
  • EP3495927B1 patent drawingFigure 1
  • EP3495927B1 patent drawingFigure 2
  • EP3495927B1 patent drawingFigure 3

AI summary

A touch panel (106) includes a first sheet (111) and a second sheet (112) that are disposed opposing each other. A first conductive path (113) and a second conductive path (114) are formed facing each other on main surfaces of the first sheet (111) and the second sheet (112), respectively. The second conductive path (114) is spaced apart from the first conductive path (113) when viewed in the normal direction of the first sheet (111). On the main surface of the second sheet (112), pressure-detecting conductive paths (115a to 115i) electrically connected to the second conductive path (114) are arranged. The pressure-detecting conductive paths (115a to 115i) intersect the first conductive path (113) as viewed in the normal direction. Structures (105a to 105i) are disposed on a second sheet(112) main surface not opposing the first sheet, and cause flexing of the corresponding pressure-detecting conductive path (115a to 115i) to contact the first conductive path (113) when pressed down.