Plastic HMI Interface Film With Localized Haptic Feedback
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Solution Overview
Problem
Capacitive buttons in plastic man-machine interfaces lack tactile feedback, making them unsuitable for noisy environments or multi-touch use, and conventional haptic actuators are too large to provide localized vibration effectively in embedded plastic surfaces.
Innovation Solution
A method involving a decorative film with integrated haptic actuators and capacitive sensors, where a free zone in the injection mold is filled with a flexible material and an anti-deformation part is used to prevent blistering, allowing for localized vibration and aesthetic integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If capacitive buttons are integrated into plastic surfaces, then the surface becomes completely smooth and aesthetic, but tactile feedback is lost
Solution Approach 1:
The patent combines capacitive sensors with haptic actuators into a single integrated assembly that is embedded within the plastic surface. This merging allows the smooth aesthetic surface to be maintained while providing localized tactile feedback through the haptic actuators when capacitive buttons are actuated.
Solution Approach 2:
The haptic actuators serve as intermediaries between the capacitive sensors and the user's finger. When the capacitive sensor detects a touch, it triggers the haptic actuator to generate localized vibrations or tactile sensations, mediating the feedback to the user without compromising the smooth surface appearance.
2Ease of operation
If conventional haptic actuators are used to provide tactile feedback, then tactile feedback is achieved, but the actuators are too large to be individually associated with each button
Solution Approach 1:
The patent employs haptic actuators that are specifically designed to be compact and localized, with each actuator corresponding to a specific capacitive button. This local quality ensures that tactile feedback is provided precisely at the location of each button rather than vibrating the entire surface, enabling individual button identification and multi-touch capability.
Solution Approach 2:
The haptic actuators are nested within the plastic surface structure, embedded in cavities or recesses formed during the injection molding process. This nesting allows the actuators to be housed within the overall assembly without increasing the external dimensions of the control interface.
3Ease of operation
If the entire keyboard vibrates to provide haptic feedback, then tactile feedback is achieved, but localized vibration cannot be achieved for multi-touch use
Solution Approach 1:
The patent segments the haptic feedback system into individual actuators, each associated with a specific capacitive button. This segmentation allows independent control of each actuator, enabling localized vibration at specific button locations while other buttons remain stationary, which is essential for providing feedback during multi-touch operations.
4Ease of manufacture
If capacitive buttons replace mechanical push buttons, then assembly steps are reduced and robustness is improved, but tactile feedback is lost
Solution Approach 1:
The patent merges the capacitive sensor assembly with the haptic actuator assembly into a single integrated unit that is embedded during the plastic injection molding process. This combination maintains the manufacturing simplicity and robustness of capacitive buttons while adding the tactile feedback capability that was lost.
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
Enables tactile feedback through localized vibration in embedded plastic surfaces while maintaining aesthetic appeal and preventing deformation, enhancing user interaction in noisy environments and multi-touch scenarios.
Implementation Method 1
a layer of haptic actuators (3) configured to vibrate the decorative film (2) when actuated
Implementation Method 2
a layer of capacitive sensors (4) configured to detect a position and a pressure of contact of a finger of the user on the decorative film (2)
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The main object of the invention is a method for manufacturing a plastic part forming a human-machine control interface, characterized in that it comprises the following steps: formation of a decorative film; formation of a technical film comprising a layer of haptic actuators and a layer of capacitive sensors; assembly to form an interface film (6); positioning in an injection mold (7), comprising an upper part (7a) and a lower part (7b) comprising a movable support pad (8) adapted to come into contact with the interface film (6) so that a thickness (E) is left free between the interface film (6) and the lower part (7b) of the injection mold (7) outside the support pad (8); injection of a plastic material into the thickness (E) free on both sides of the support pad (8); opening of the injection mold (7) and ejection of the plastic part formed.