Data Input Device Cam Mechanism for Tactile Feedback
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Solution Overview
Problem
Existing data input devices with tactile sensation for aircraft instrument panels face challenges in maintaining accurate tactile feedback due to wear and tear, requiring tight production tolerances and significant materials to sustain repeated operations, which affects the reliability and longevity of the devices.
Innovation Solution
A data input device with a stem and return spring system that includes a circular element and cam with a slope and counter-slope, allowing for modulation of the force exerted to create a peak force for switch operation, reducing wear and allowing for softer materials to be used while maintaining reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a ball and cam mechanism with significant clearance is used to provide tactile sensation, then the tactile feedback is identifiable, but the compression forces are significant causing rapid wear requiring hard materials and tight tolerances
Solution Approach 1:
The invention changes the geometric parameters of the cam mechanism, specifically using a cam with a slope and counter-slope configuration that modifies the force-displacement relationship. This allows achieving the same tactile sensation with reduced peak forces by distributing the mechanical interaction over a longer path, thereby reducing wear on the ball and cam components.
Solution Approach 2:
The invention introduces a dynamic modulation of the force exerted by the return spring through the cam mechanism. The cam's slope and counter-slope create a variable force profile during stem displacement, generating a peak force that provides tactile feedback while controlling the overall force magnitude to reduce wear.
2Reliability
If significant compression forces are applied to the ball and cam to ensure switch operation, then the switch triggering is reliable, but the wear of the cam and ball increases affecting tactile sensation over time
Solution Approach 1:
The invention modifies the force parameters by using a cam with optimized slope and counter-slope angles. This configuration ensures that the peak force required for switch operation is achieved while the maximum compression force on the ball is limited, reducing wear and maintaining tactile sensation consistency over the device lifetime.
Solution Approach 2:
The cam acts as an intermediary element between the return spring and the ball. It transforms the continuous force from the return spring into a modulated force with a distinct peak, ensuring reliable switch triggering while distributing the mechanical stress to minimize wear on the ball and cam surfaces.
3Measurement precision
If tight production tolerances are imposed on ball diameter and position to ensure accurate tactile feedback, then the tactile sensation is precise, but the manufacturing complexity and cost increase
Solution Approach 1:
The invention changes the design parameters from relying on tight tolerances of small components (ball diameter and position) to relying on the geometric configuration of the cam (slope and counter-slope angles). This shift in critical parameters makes the system less sensitive to manufacturing variations and easier to produce with standard tolerances.
Solution Approach 2:
The invention segments the tactile feedback function into two parts: the cam geometry (slope and counter-slope) that defines the force profile, and the ball that simply follows the cam contour. This segmentation allows the cam to be manufactured with standard tolerances while still achieving precise tactile feedback through its geometric design.
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 ensures consistent tactile feedback, reduces wear on components, and allows for the use of less expensive materials, enhancing the reliability and longevity of the data input device.
Implementation Method 1
a return spring enabling the stem to return to a stable position in which the stem is not operated
Implementation Method 2
means for modulating a force exerted by the return spring in order to define a peak of force at a point of the travel of the stem beyond which the switch is operated
Data Source
AI summary
The invention relates to a data input device produced by means of a switch operated by a stem. A return spring enables the stem to return to a stable position. According to the invention, the device comprises a circular element that can be displaced roughly perpendicularly to the displacement of the stem, a cam attached to the stem, and elastic means holding the circular element pressed against the cam, the cam comprising a slope, a high point and a counter-slope on which the circular element bears in succession when the stem is operated from its stable position to a position in which the switch is operated.