Segmented LCD Keypad with Soft Deflection Zone for Tactile Feedback
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Solution Overview
Problem
Conventional handheld electronic devices with touch screens lack substantial tactile feedback when activating keys, as they typically have a hard clear substrate that inhibits key deflection, which is essential for providing a positive user experience.
Innovation Solution
A programmable keypad system that incorporates a liquid crystal display (LCD) with a collapsible dome switch mechanism, where the LCD generates key images and provides tactile feedback through key deflection and compression of the dome switch, allowing for dynamic key identification and activation feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard clear substrate is used to cover the display area, then the display is protected, but key deflection is inhibited and tactile feedback is reduced
Solution Approach 1:
The substrate is segmented into hard peripheral regions for protection and a soft key region for deflection. The hard substrate includes hard edges around the perimeter and a soft key region in the center that allows key deflection, enabling both protection and tactile feedback simultaneously.
Solution Approach 2:
Different regions of the substrate have different mechanical properties. The peripheral edges are made hard for protection while the key areas are made soft to allow deflection and provide tactile feedback when keys are pressed.
2Adaptability or versatility
If a touch-sensitive device is incorporated into the LCD to register key activation, then key input is enabled, but substantial tactile feedback is not provided
Solution Approach 1:
The invention merges the visual display function with the tactile feedback function in a single integrated key structure. The soft key region serves both as the visual key identifier on the LCD and as the tactile element that deflects when pressed, eliminating the need for separate touch-sensitive devices.
Solution Approach 2:
The soft key region acts as an intermediary between the user's finger and the underlying electronics. It provides the tactile feedback sensation while transmitting the press force to activate the key signal, bridging the gap between visual display and tactile response.
3Adaptability or versatility
If the LCD is used as a substrate for virtual keypads, then programmable key assignments are achieved, but tactile feedback is inhibited
Solution Approach 1:
The key structure incorporates dynamic elements that allow it to change state when pressed. The soft key region can deflect dynamically in response to user input, providing tactile feedback that varies with the key press while maintaining programmable assignments through the LCD display.
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 system offers improved tactile feedback and dynamic key assignment, enhancing user interaction by combining visual and haptic feedback, thus addressing the lack of substantial tactile feedback in existing touch screen devices.
Implementation Method 1
The keypad may be implemented in part with a liquid crystal display (LCD) that can be programmed to generate an image of a keypad
Implementation Method 2
The feedback can be provided by a combination of one or more of a deflection of a key area in the display as the user presses on the image of the key and compression of a collapsible dome underneath the key
Data Source
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AI summary
The embodiments relate to a key (24) in a keypad of an electronic device and a system to control the value associated with the key. The key comprises: a programmable display (14B) to generate a character associated with the key; and a switch assembly (316,318) associated with the key to register activation of the key. In the key, part of the display deflects inwardly into the device when external pressure is applied to the key, and the display transmits the external pressure to the switch assembly. The key have an elastomer (304) located between the display and the switch assembly. The display may be a cholesteric liquid crystal display.