Press-Type Input Device Fulcrum Mechanism for Sensor Protection
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Solution Overview
Problem
Existing pressing type input devices for portable terminals, such as mobile phones, risk damaging load sensors when subjected to high loads due to direct pressure application, particularly those using piezoelectric ceramics which are prone to damage under overload conditions.
Innovation Solution
The design incorporates a fulcrum mechanism that reduces the initial load on load sensors by converting the operation load through a lever system, allowing for adjustable detection accuracy and the use of load sensors with various ratings, and includes a biasing member to generate a stable initial load, thereby reducing the risk of sensor damage and improving design flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If load sensors are directly applied to the touch screen to detect press position, then detection accuracy is improved, but the load sensor may be damaged when large load is applied
Solution Approach 1:
A pressing member is introduced as an intermediary between the operation member and the load sensor. The pressing member transmits the operation load to the load sensor while being pre-loaded by a biasing member, preventing direct exposure of the load sensor to overload conditions and thus resolving the contradiction between detection accuracy and sensor durability
Solution Approach 2:
The biasing member applies a preliminary load (initial load) to the pressing member before any operation load is applied. This preliminary action ensures the pressing member is already under tension, creating a buffer that protects the load sensor from sudden overload and maintains reliable operation under various loading conditions
2Reliability
If a lever mechanism with fulcrum is introduced to reduce initial load on load sensor, then load sensor damage is prevented, but device complexity increases
Solution Approach 1:
The pressing member integrates multiple functions: it serves as the lever arm for load transmission, the mounting structure for the biasing member, and the direct interface with the load sensor. By merging these functions into a single component, the design achieves load sensor protection without proportionally increasing device complexity
Solution Approach 2:
The pressing member is designed as a multi-functional component that simultaneously provides mechanical leverage for load reduction, structural support for the biasing member, and a loading surface for the load sensor. This universality allows the system to achieve reliability improvements while minimizing additional complexity
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 effectively prevents load sensor damage from overloads and allows for the use of load sensors with different ratings, enhancing detection accuracy and design freedom while reducing the number of parts required.
Implementation Method 1
the pair of elastic arm portions may pull the press portion on the load sensor side to generate an initial load by locking the free end sides of the pair of elastic arm portions in the pair of locking portions
Implementation Method 2
the load sensor using piezoelectric ceramics gets easily damaged
Data Source
AI summary
A pressing type input device includes: a load sensor (13) which outputs a signal corresponding to an operation load from an operation plate (3); a biasing member which generates an initial load with respect to the load sensor (13) ; a pressing plate (14) which presses the load sensor (13) by receiving a biasing force of the biasing member; and a support member (11) which oscillatably supports the pressing plate (14), in which the pressing plate (14) has a pressed portion (45) to receive an operation load from the operation plate (3) and a press portion (46) to press the load sensor (13), and in which the operation load applied to the pressed portion (45) causes a force to act on the press portion (46) in a direction to reduce the initial load on the load sensor (13), with a position supported by the support member (11) as fulcrum.