Touch-Sensitive Operating Area With Boundary-Line Touch Detection
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Solution Overview
Problem
Existing touch-sensitive operating units, particularly in vehicles, often inaccurately determine activation locations due to reliance on centroid calculations, leading to delayed function triggering and accidental selection of fields, especially when fingers move tangentially or with varying speeds.
Innovation Solution
The operating unit determines the activation location by correlating the position of the boundary line of the fingertip rather than the centroid of the touched area, with the control unit considering the direction of movement and speed to ensure precise selection, using a matrix of capacitive sensor cells and optionally a camera unit for spatial information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the activation location is determined using centroid calculation of the touched area, then the system can handle stationary touches, but the function triggering is delayed and accidental field selection occurs during finger movement
Solution Approach 1:
Instead of calculating the centroid of the entire touched area (conventional approach), the patent inverts the approach by identifying the boundary line of the fingertip and determining the activation location at the front of this boundary line in the direction of movement. This inversion resolves the contradiction by providing both rapid response (no delay waiting for centroid calculation) and accurate field selection (boundary line method prevents accidental selection).
2Ease of operation
If the activation location is determined from the centroid of the touched area, then the calculation is simple, but the system cannot distinguish between intended and unintended touches during finger movement
Solution Approach 1:
The patent applies preliminary action by analyzing the direction of finger movement and identifying the boundary line of the fingertip before determining the activation location. This preliminary analysis of movement direction and boundary position allows the system to distinguish between intentional touches (where the boundary line reaches the field) and accidental touches (where the centroid may fall in the field but the boundary line does not), thereby improving both ease of operation and reliability.
3Productivity
If the system uses boundary line detection for activation location, then the response speed improves, but the system complexity increases due to additional movement analysis
Solution Approach 1:
The patent changes the parameter used for activation location determination from centroid coordinates to boundary line position in the direction of movement. This parameter change enables faster response because the system only needs to track the leading edge of the fingertip rather than calculate the centroid of the entire contact area. The complexity increase is minimized by focusing analysis on the boundary line and movement direction rather than analyzing the entire touched area.
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 approach allows for quicker and more accurate activation of intended functions, preventing accidental field selection and ensuring reliable operation, especially in automotive applications like steering wheels, by distinguishing between intended and unintended touches based on movement speed and direction.
Implementation Method 1
Each element of the matrix has a capacitive sensor cell which, in response to a position of a user's finger on the touch-sensitive operating area, has a capacitance signal that changes in response to movement of the finger
Data Source
AI summary
An operating unit includes a touch-sensitive operating area and control unit. The control unit determines an activation location on the operating area from the information relating to the touched regions. If the activation location is in a predefined field, the control unit performs a function assigned to the field. The control unit determines the activation location from a position on or in the region of a boundary line bounding a fingertip and that is at the front in the direction of movement of the finger on the surface of the operating area, only when a determined speed of movement of a course of the regions of the touched operating exceeds a predefined limit value. Otherwise, the activation location is determined from an area centroid of all regions of the operating area which have been touched by the finger at a point in time.