Optical Depression Sensor for Touch Display Force Detection
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Solution Overview
Problem
Existing touch-sensitive displays in portable electronic devices face challenges in accurately detecting depression or force exerted on the screen, leading to unintended selections due to limited size and space, and existing solutions like strain gauges and mechanical devices may not provide reliable tactile feedback.
Innovation Solution
The use of optical depression sensors and piezoelectric actuators in conjunction with touch-sensitive displays to detect depression and provide tactile feedback, allowing for accurate selection confirmation by measuring changes in optical reflections and applying controlled forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of portable electronic devices is decreased to improve portability, then device compactness is improved, but the accuracy of touch detection is worsened due to limited space for sensors
Solution Approach 1:
The patent replaces mechanical strain gauges with an optical detection system using light sources and photodetectors to detect touch-induced changes in light reflection or transmission. This substitution eliminates the need for physical contact sensors, enabling accurate touch detection in smaller device form factors without mechanical components that occupy space.
Solution Approach 2:
The patent introduces light as an intermediary medium between the touch surface and the detection system. By measuring changes in light properties (reflection, transmission, or absorption) caused by touch pressure, the system achieves indirect measurement of touch force, allowing for compact sensor integration while maintaining detection accuracy.
2Device complexity
If conventional touch sensors are used without force detection, then device complexity is reduced, but unintended selections occur due to inability to detect force thresholds
Solution Approach 1:
The patent detects changes in optical parameters (light intensity, reflection angle, or transmission) in response to applied force on the touch surface. By monitoring these parameter changes and comparing them against threshold values, the system distinguishes between intentional touches requiring selection and incidental contacts, thereby improving selection reliability without significantly increasing system complexity.
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
Enhances user experience by reducing unintended selections and providing reliable tactile feedback through accurate detection of force thresholds, improving the reliability and usability of touch-sensitive displays in portable devices.
Implementation Method 1
detecting depression of the touch-sensitive display by detecting a change in reflection
Implementation Method 2
The force sensor comprises a piezoelectric actuator
Data Source
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AI summary
An electronic device includes a touch-sensitive display and a sensor configured to detect a force that results in depression of the touch-sensitive display. The sensor includes an optical device that receives a reflection of a pattern on a surface of the touch-sensitive display, wherein the force affects the reflection.