Optical Touch Module Light Distribution via Diffusing Plate
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Solution Overview
Problem
Conventional optical touch modules face accuracy issues and touch failures due to uneven light distribution on large touch screens, where the direct image capturing method results in brightness differences across the touch surface, affecting positioning accuracy.
Innovation Solution
The optical touch module incorporates a transparent diffusing part with a bar structure on the light entrance surface of the light emitting unit, scattering invisible light to increase the light emitting angle and ensure uniform coverage of the touch surface, enhancing light distribution and positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the direct image capturing method is applied to a large-size monitor, then the touch surface area is increased, but uneven light distribution occurs across the touch surface
Solution Approach 1:
A transparent diffusing plate is introduced as an intermediary component between the light emitting unit and the touch surface. This diffusing plate scatters the light from the light emitting unit, transforming the concentrated light beam into uniformly distributed light across the entire touch surface area, thereby resolving the uneven light distribution problem while maintaining large touch surface coverage
2Area of stationary object
If a near-infrared light emitting device illuminates only part of the enlarged touch surface, then the light emitting device area is reduced, but brightness differences occur across different regions
Solution Approach 1:
The light emitting angle parameter of the light emitting unit is changed from a narrow angle to a wide angle (specifically 120 degrees) by using a transparent diffusing plate. This parameter change allows a single light emitting device to cover the entire enlarged touch surface uniformly, eliminating brightness differences and maintaining positioning accuracy across all regions
3Area of stationary object
If the light emitting angle is increased, then the light coverage area is expanded, but the light intensity per unit area may be reduced
Solution Approach 1:
The transparent diffusing plate transforms the light parameters by expanding the light emitting angle to 120 degrees while maintaining sufficient light intensity across the coverage area. The diffusing plate achieves this by scattering light in multiple directions, ensuring that the increased coverage area receives adequate uniform illumination without significant intensity loss
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 design achieves uniform light distribution and increased light use efficiency, improving the accuracy of optical touch positioning and preventing incorrect touch recognition on large touch screens.
Implementation Method 1
A bar structure is formed on a light entrance surface of the transparent diffusing part for scattering the invisible light to be distributed over the touch surface
Data Source
AI summary
An optical touch module includes a screen and at least one optical positioning device disposed on the screen. The optical positioning device includes a case, at least one light emitting unit, a circuit board, a transparent diffusing part and an image capturing unit. The light emitting unit is disposed on case for emitting invisible light. The circuit board is electrically connected to the light emitting unit for controlling the light emitting unit. The transparent diffusing part is disposed at a light emitting side of the light emitting unit. A bar structure is formed on a light entrance surface of the transparent diffusing part for scattering the invisible light to be distributed over a touch surface of the screen. The image capturing unit is disposed on the case to capture an optical image for a touch object on the touch surface when the touch object is illuminated by the invisible light.