Split Friction Ring Braking for Trackball Precision
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Solution Overview
Problem
Current data input devices, such as trackballs, face challenges with uncontrolled movements due to vibrations and precision issues, particularly in turbulent environments like aircraft, where traditional braking solutions are complex, expensive, and difficult to adjust, leading to variable friction and separation torques that affect user experience and accuracy.
Innovation Solution
A data input device featuring a split friction ring with an annular spring for radial compression, allowing for easy adjustment of braking torque by the operator, which is tolerant to dimensional variations and can be adapted in real-time to changing vibratory conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional brake with a pad rubbing against the sphere is used, then uncontrolled sphere movement is limited, but the friction torque is highly dependent on coaxiality accuracy requiring precise assembly and machining
Solution Approach 1:
The brake is segmented into a fixed element (friction ring) and a movable element (adjusting mechanism), allowing independent adjustment of braking force without requiring precise coaxiality between the sphere and brake components. The friction ring can be positioned radially outward from the sphere's rotational axis, eliminating the need for exact coaxial alignment.
Solution Approach 2:
An intermediary adjusting mechanism is introduced between the operator and the brake force application. This mechanism (such as a spring-loaded adjuster or threaded adjustment) mediates the transmission of braking force, allowing precise control of friction torque independent of the sphere's positional tolerances.
2Reliability
If vertical bracing for the brake is added to limit dependence on sphere position, then the braking system becomes more stable, but the cost increases due to individual adjustment requirements
Solution Approach 1:
The brake design incorporates self-adjusting features where the friction ring automatically adapts to the sphere's position through elastic deformation or mechanical compliance. The adjusting mechanism allows the operator to set the brake force once, and the system maintains consistent performance without requiring complex vertical bracing or frequent individual adjustments.
Solution Approach 2:
The brake system allows easy adjustment of the friction force parameter through a simple operator-accessible mechanism. By changing the braking force parameter independently of the sphere's positional parameters, the system achieves consistency without complex structural modifications.
3Force
If the friction surface is positioned above the plane of symmetry of the sphere, then braking force is applied, but the usable surface area is reduced
Solution Approach 1:
The brake system transitions from a vertical friction surface (above the equatorial plane) to a horizontal friction ring positioned at the equatorial plane of the sphere. This dimensional change allows the friction interface to be distributed around the entire circumference of the sphere at its widest point, maximizing the usable surface area while maintaining effective braking force through radial compression.
4Measurement precision
If the friction torque is set during assembly, then the brake is calibrated, but modification requires disassembly which is unacceptable in the aeronautical field
Solution Approach 1:
The brake system incorporates a dynamic adjusting mechanism that allows the friction torque to be modified in real-time during operation. The adjusting mechanism (such as a threaded rod, spring preload adjuster, or micrometer-style control) enables the operator to fine-tune the braking force without disassembling the device, transforming a static calibration process into a dynamic, adaptable system.
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 provides a more stable and adjustable braking system that minimizes uncontrolled movements and enhances precision, allowing operators to customize the braking torque according to their needs without requiring complex assembly or adjustments, thus improving user experience and accuracy in dynamic environments.
Implementation Method 1
As the sphere moves, the pressure of the pad generates a frictional torque that opposes its rotation
Implementation Method 2
The pad is held against the sphere by a spring that bears against the fixed part
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
The invention relates to a data input device comprising a body for mounting on a workstation, a movable part (13) rotating relative to the body, a set of sensors providing relative position information of the movable part (13) with respect to the body, and means for braking the rotational movements of the movable part (13) with respect to the body. According to the invention, the braking means comprise a friction ring (20) clamping the movable part (13), the ring (20) being split and extending primarily in a plane perpendicular to an axis (15) of symmetry of the movable part (13), an annular spring (25) extending in the plane and radially compressing the friction ring (20) against the movable part (13), and means for adjusting the length of the annular spring (25).