Light Emitting Device With Wavelength Conversion For Image Reading
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Solution Overview
Problem
Conventional line lighting devices for image reading devices, particularly when reading black-and-white images, face challenges with low sensitivity due to the low output of green and red LEDs, and the impracticality of using a yellow LED for full-color image reading due to its low output.
Innovation Solution
A light emitting device with a blue light emitting region and a yellow light emitting region, where the yellow light emitting region has a higher output, achieved by using a wavelength converting member to convert light from a second light emitting element, and optionally featuring a larger light emitting area or multiple light emitting elements, to enhance luminance efficiency and color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If green LED and red LED are used for black-and-white image reading, then the device can read images, but the output is insufficient due to low sensitivity
Solution Approach 1:
The patent changes the emission wavelength parameters by using blue LEDs (higher energy) instead of green/red LEDs, and uses wavelength converting members to transform the light to appropriate colors for image reading, thereby achieving higher output while maintaining sensitivity
Solution Approach 2:
The patent introduces wavelength converting members as intermediary elements that convert blue light from the LED to other wavelengths needed for image reading, solving the contradiction between high output and sufficient sensitivity
2Adaptability or versatility
If yellow LED is used for full-color image reading, then color reproducibility can be improved, but the output is too low compared to blue LED
Solution Approach 1:
The patent uses wavelength converting members as intermediaries that convert blue LED light to yellow light with high efficiency, achieving both high output (inherited from blue LED) and good color reproducibility (through controlled wavelength conversion)
Solution Approach 2:
The patent changes the approach from directly using yellow LEDs to using blue LEDs with wavelength converting members, thereby achieving high output yellow light while maintaining color reproducibility for full-color image reading
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 increases the output of yellow light, improving the sensitivity of image reading devices and allowing for better color reproducibility in full-color image reading.
Implementation Method 1
a wavelength converting member which is arranged to absorb light from the second light emitting element and to convert the wavelength thereof to emit yellow light
Data Source
AI summary
The device includes a blue light emitting region having a first light emitting part and a yellow light emitting region having a second light emitting part and a wavelength converting member arranged to absorb light from the second light emitting part and to convert the wavelength thereof to emit yellow light. The second light emitting part has a higher output than that of the first light emitting part. With this arrangement, output of the yellow light can be increased, so that the device can be used in an image reading apparatus with a high sensitivity.