Scanner Illumination Control for Edge Detection and Dazzle Reduction
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Solution Overview
Problem
Image reading apparatuses face issues with erroneous detection of original sizes due to dust or dirt on the platen cover, and users are dazzled by direct light emission during scanning with the platen cover open.
Innovation Solution
An image reading apparatus with a controller that adjusts illumination duration and position based on the platen cover's open or closed state, reducing light exposure to the user and accurately determining original size by moving the reading unit between the front-end and rear-end of the original, and using binarization of luminance to differentiate between the original and background.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light source is kept ON while scanning the original table to extract the edge of the original, then the original edge can be accurately detected, but the user is dazzled by the direct light reaching their eyes
Solution Approach 1:
The light source is controlled to be turned ON and OFF periodically during the scanning process. Specifically, the light is turned ON only when the reading unit is at positions where original edge detection is needed, and turned OFF when the reading unit moves to positions where light would directly reach the user's eyes. This periodic illumination pattern enables accurate edge detection while preventing user dazzle.
2Reliability
If the illumination portion irradiates the reading position continuously to ensure accurate reading, then the reading quality is maintained, but the light exposure to the user increases when the platen cover is open
Solution Approach 1:
The control unit receives feedback from the platen cover open/close detection sensor to dynamically adjust the illumination duration. When the sensor detects that the platen cover is in the open state, the control unit shortens the illumination duration compared to when the cover is closed. This feedback-based control maintains reliable reading quality while reducing harmful light exposure to the user based on the actual platen cover state.
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
Minimizes user dazzle and accurately detects original edges even with the platen cover open, ensuring precise original size determination and reduced light exposure.
Implementation Method 1
an illumination portion for irradiating a reading position with light
Implementation Method 2
a reader, which includes an illumination portion for irradiating a reading position with light, and is configured to read the original while moving the reading position
Data Source
AI summary
An image reading apparatus includes a reading unit, which includes an illumination portion for irradiating an original placed on an original table with light and a light receiving portion for receiving irradiated light reflected from the original. The image reading apparatus reads the original one line at a time in a main scanning direction according to the received reflected light. The image reading apparatus determines the size of the original based on the reading result of the reading unit. The image reading apparatus shortens, in a case where the platen cover is in an open state, the lighting duration of the illumination portion than the duration where the platen cover is in a close state.