Sheet Feeding Device LED Illumination Uniformity
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Solution Overview
Problem
Conventional dome-type LEDs used in image reading apparatuses provide non-uniform illumination, making it difficult for users to correctly read the display screen due to their small area and uneven illuminance.
Innovation Solution
A sheet feeding device with a dome-type LED adjacent to the stacking tray, a reflector to scatter and diffuse the light, and a controller to regulate the LED's emission based on a sheet presence-absence detector, ensuring uniform illumination of the display portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a dome-type LED is used to illuminate the display screen, then the cost is reduced, but the illumination area is small and the illuminance is non-uniform
Solution Approach 1:
A reflector is introduced as an intermediary component between the dome-type LED and the display screen. The reflector has a specific curved shape that redirects and distributes the light from the LED across the entire display screen surface, transforming the concentrated light source into uniform illumination while maintaining the cost advantage of using a dome-type LED
Solution Approach 2:
The invention changes the spatial distribution parameters of light by using a reflector with a specifically designed curved surface. This alters the direction, angle, and distribution of light rays from the LED, transforming the light pattern from concentrated and non-uniform to distributed and uniform across the display screen
2Ease of manufacture
If a dome-type LED is used to illuminate the display screen, then the cost is reduced, but the area of illumination is small
Solution Approach 1:
The reflector acts as a light-distributing intermediary that takes the limited light output from the small dome-type LED and redirects it to cover a much larger area of the display screen, effectively amplifying the illumination area without increasing the LED size or cost
Solution Approach 2:
The reflector utilizes angular and directional dimensions to distribute light across the display screen surface. By controlling the reflection angles and light paths in multiple directions, the system expands the effective illumination area beyond what the LED could provide directly
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 provides improved uniformity and visibility of the display screen, allowing users to easily recognize the presence of documents and their orientation, even for those with weak eyesight, by ensuring consistent and adequate lighting.
Implementation Method 1
an LED provided adjacent to the sheet stacked on the stacking tray and configured to emit light
Implementation Method 2
a reflector provided opposed to the display portion and configured to reflect and scatter the light emitted by the LED, toward the display portion
Implementation Method 3
a sheet presence-absence detector configured to detect presence/absence of the sheet on the stacking tray
Data Source
AI summary
A sheet feeding device includes a stacking tray for stacking a sheet; a sheet detector for detecting presence/absence of the sheet on the stacking tray; a feeder for feeding the sheet detected by the sheet detector; an LED, provided adjacent to the sheet stacked on the stacking tray, for emitting light; a display, provided substantially in parallel with an optical axis of the LED, for being illuminated by the light emitted from the LED; a reflector, provided opposed to the display portion, for reflecting and scattering the light emitted by the LED, toward the display; and a controller for controlling emission of the light of the LED on the basis of a signal outputted by the sheet detector.