Touch Device Invisible Light Filter Outdoor Reliability
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Solution Overview
Problem
Conventional optical touch devices experience decreased reliability and sensitivity in outdoor settings due to ambient light penetrating through the light guide plate and interfering with infrared light detection.
Innovation Solution
Incorporating an invisible light filter that blocks ambient light with a wavelength distribution matching the invisible light beam, preventing it from entering the touch device and improving sensitivity and reliability by using an invisible light detector to capture the invisible light beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional optical touch device uses a light guide plate and infrared light detector without additional filtering components, then the device structure remains simple, but ambient light penetrates through the light guide plate and causes decreased reliability and sensitivity
Solution Approach 1:
An invisible light filter is introduced as an intermediary component between the light guide plate and the invisible light detector. This filter selectively blocks ambient light with wavelengths matching the invisible light beam while allowing the invisible light to pass through, thereby improving touch detection reliability without requiring fundamental changes to the overall device architecture
Solution Approach 2:
The solution changes the wavelength parameter characteristics by using a filter that specifically targets the wavelength distribution of the invisible light beam. The invisible light filter is designed to block ambient light at the same wavelength range as the invisible light, creating a spectral distinction that enables reliable touch detection even in outdoor conditions
2Reliability
If the invisible light filter blocks all light at the invisible light wavelength, then ambient light interference is reduced, but the invisible light beam transmission is also blocked
Solution Approach 1:
The invisible light filter is designed with spatially selective properties where different regions or layers of the filter have different transmission characteristics. The filter allows invisible light to pass through while blocking ambient light at the same wavelength, creating a localized quality difference that enables simultaneous achievement of reliable touch detection and invisible light transmission
Solution Approach 2:
The invisible light filter employs composite material structure combining multiple layers or materials with complementary optical properties. This composite structure enables selective wavelength filtering where ambient light is blocked while invisible light transmission is maintained, resolving the contradiction between interference reduction and signal transmission
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 effectively enhances the reliability and sensitivity of the touch device and touch projection system by blocking ambient light interference, allowing for accurate detection of touch positions even in outdoor conditions.
Implementation Method 1
The invisible light filter is contacted tightly with the first surface, and corresponds to a size of the first surface for blocking an ambient light beam from entering the touch device
Implementation Method 2
When the user touches the optical touch device, a total internal reflection of the infrared light beam in the light guide plate is destroyed
Implementation Method 3
an infrared light image capturing device does not detect the infrared light beam emitted from the light emitting unit
Data Source
AI summary
A touch device including a light guide unit, a light emitting unit, an invisible light filter and an invisible light detector is provided. The light guide unit has at least one light incident surface and a first surface connected to the light incident surface. The light emitting unit is disposed beside the light incident surface and is capable of emitting an invisible light beam. The invisible light filter is contacted tightly with the first surface. The light guide unit is disposed between the invisible light filter and the invisible light detector. Moreover, a touch projection system including the touch device is also provided.