Display Selection Button With Prismatic Light-Guide Finger Detection
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Solution Overview
Problem
Conventional switch units in presentation devices like vending machines require complex configurations with light projecting and receiving units at push button positions, necessitating a simplified and efficient detection mechanism.
Innovation Solution
A display device with a light guide plate and prisms that reflect light towards a user's finger, combined with light receiving units to detect finger proximity or touch, and a seven-segment display for numeral display, using separate light wavelengths for detection and display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light projecting unit and light receiving unit are disposed at push button positions to detect finger proximity, then finger detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the light projecting unit and light receiving unit into a single integrated switch unit module. The light guide plate integrates both light emission and light reception functions, allowing finger detection while simplifying the overall configuration. Multiple light receiving units are arranged within the same module to detect reflected light from different directions, achieving accurate detection without requiring separate complex systems.
Solution Approach 2:
The light guide plate serves multiple functions: it guides light from the projecting unit, reflects light toward the finger, and directs reflected light to the receiving units. This multi-functional design reduces the number of separate components needed while maintaining detection accuracy across multiple push button positions.
2Reliability
If separate light wavelengths are used for detection and display, then detection reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies different wavelengths locally within the same device: infrared light (wavelength 700-1000nm) is used for finger detection while visible light is used for display purposes. The light guide plate and filtering structures are designed to separate these wavelengths spatially, allowing each function to operate with optimal wavelength characteristics without interference.
Solution Approach 2:
The light guide plate acts as an intermediary that separates and directs different wavelengths to their respective functions. It guides infrared light to the receiving units for detection while directing visible light to the display area, preventing wavelength mixing and ensuring reliable operation of both detection and display functions.
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
Simplifies the configuration of the switch unit while accurately detecting finger operations and displaying desired numerals, allowing for reliable operation without mixing detection and display lights.
Implementation Method 1
a first light guide plate having an incident surface on which the light emitted from the first light projecting unit is incident, a plurality of first prisms that reflect the light incident from the incident surface toward the side approached or touched by the finger
Implementation Method 2
The plurality of light receiving units are provided at positions corresponding to the push buttons and receive the light emitted from the exit surface and reflected by the finger approaching or touching the push button
Data Source
AI summary
A display selection button 10 comprises a light projecting unit 21, a light guide plate 13, a light receiving units 22, a control unit 30, and a printed sheet 14 and a LED 25. The light guide plate 13 has an incident surface 13a to which the light emitted from the light projecting unit 21 is incident, a plurality of prisms 13d that reflect incident light toward the side approaching or touching a finger and are provided at positions corresponding to push buttons 10c, and an exit surface 13b that emits the light reflected in the direction in which the finger approaches. The light receiving units 22 receive light emitted from the exit surface 13b and reflected from a finger. The control unit 30 detects the approach of a finger depending on the amount of light received by the light receiving units 22. The printed sheet 14 displays the desired numerals. The LED 25 emits light for displaying the desired numerals in the printed sheet 14.