Dual LED Illumination for Uniform Scanning
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Solution Overview
Problem
The existing image scanning apparatus using a single LED array as a light source faces issues with shadow formation due to narrow irradiation width and temperature-related substrate warping, leading to uneven illuminance and potential ripples on the document surface.
Innovation Solution
The apparatus employs dual LED arrays mounted on both surfaces of a substrate, with one array emitting direct light and the other emitting indirect light via reflection mirrors, to achieve a stable and uniform light distribution, reducing temperature differences and substrate warping, and incorporating a light-amount adjusting mechanism to control current values for optimal illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one LED array irradiates the document surface, then the device complexity is low, but the irradiation width is narrow causing shadow appearance
Solution Approach 1:
The patent divides the single LED array into two separate LED arrays (first LED array and second LED array) positioned at different locations. Each LED array independently irradiates the document surface, collectively providing wider coverage and eliminating shadows caused by level difference portions while maintaining manageable device complexity through modular segmentation.
2Device complexity
If one LED array is used, then the device complexity is low, but the light amount is insufficient
Solution Approach 1:
The patent combines two LED arrays (first LED array and second LED array) to work simultaneously, merging their light output to achieve sufficient total light amount for document scanning. This merging approach provides the required illumination intensity while keeping each individual LED array at a manageable complexity level.
3Illumination intensity
If current value is increased to increase light amount, then the light amount increases, but ripple of illuminance occurs on document surface
Solution Approach 1:
Instead of increasing the current of a single LED array which causes illuminance ripple, the patent segments the lighting function into two separate LED arrays. Each array operates at a lower, more stable current level, and their combined light output provides uniform illuminance across the document surface without the ripple effects caused by high-current operation.
4Duration of action of stationary object
If LEDs are kept on for long time, then continuous illumination is achieved, but temperature difference occurs between component surface and solder surface causing substrate warping
Solution Approach 1:
The patent positions the first LED array on the component surface and the second LED array on the solder surface of the substrate, creating an asymmetric distribution that balances heat generation across both surfaces. This asymmetric placement ensures that during continuous operation, temperature differences are evenly distributed, preventing localized thermal expansion and substrate warping.
5Duration of action of stationary object
If substrate warps due to temperature difference, then continuous operation is maintained, but illuminance characteristic of document surface is adversely affected
Solution Approach 1:
By placing LED arrays on both the component surface and solder surface in an asymmetric configuration, the patent balances thermal loads across the substrate. This prevents warping during continuous operation, thereby maintaining consistent illuminance characteristics and uniform light distribution across the document surface throughout extended operation periods.
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 configuration ensures stable and uniform illuminance on the document surface, reducing ripples and shadows, while maintaining efficient light distribution and preventing substrate warping, thereby enhancing image scanning quality.
Implementation Method 1
plural first light emitting elements located on one surface of the substrate, the first light emitting elements each emitting light for irradiating the original document on the document table; and plural second light emitting elements located on the other surface of the substrate, the second light emitting elements each emitting light for irradiating the original document on the document table
Implementation Method 2
FIG. 5 is a schematic diagram formed by tracing indirect light irradiated on the document table from an LED array located on a solder surface via reflection mirrors
Data Source
AI summary
According to one embodiment, an image scanning apparatus includes a document table on which an original document is stacked; a substrate; plural first light emitting elements located on one surface of the substrate, the first light emitting elements each emitting light for irradiating the original document on the document table with direct light not reflected by a reflection member; and plural second light emitting elements located on the other surface of the substrate, the second light emitting elements each emitting light for irradiating the original document on the document table with indirect light reflected by the reflection member. The reflection member includes a first reflection member and a second reflection member, and the first reflection member and the second reflection member are located in positions opposed to each other across a reflection optical path of light reflected by the original document on the document table.