Image Reading Shutter Mechanism for Extraneous Light Control
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Solution Overview
Problem
Existing image reading apparatuses face challenges in accurately reading images due to extraneous light entering the reading unit, particularly when the bypass path extends straight towards it, leading to less accurate shading correction data.
Innovation Solution
The apparatus incorporates a shutter and actuator mechanism that blocks or opens the second conveying path upstream of the junction, allowing the controller to direct sheets along either path, ensuring the reading unit is not affected by extraneous light, and includes a detection sensor to manage the shutter's position and conveyance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bypass path extends substantially straight from the sheet support toward the reading unit, then the sheet can be conveyed efficiently through the bypass path, but extraneous light enters the reading unit causing inaccurate image reading
Solution Approach 1:
The patent extracts and removes extraneous light from the system by introducing a shutter that blocks light from the bypass path from reaching the reading unit. The shutter is positioned to specifically intercept light coming from the bypass path direction, separating the light path from the sheet conveyance path, thereby eliminating the harmful light effect while preserving the efficient bypass conveyance function.
Solution Approach 2:
The shutter acts as an intermediary element between the bypass path and the reading unit. It is positioned in the light path from the bypass path to the reading unit, controlled by an actuator that responds to sheet presence detection. The shutter mediates by blocking light when a sheet is detected on the bypass path and allowing light when the bypass path is empty, thus protecting the reading unit from extraneous light while maintaining operational efficiency.
2Measurement precision
If a shutter mechanism is introduced to block extraneous light, then image reading accuracy is improved, but device complexity increases
Solution Approach 1:
The shutter mechanism is designed to operate automatically based on sheet presence detection. The detection sensor on the sheet support detects when a sheet is placed on the bypass path, and this detection directly triggers the actuator to move the shutter into the light-blocking position. The system serves itself by using the sheet detection signal to control the light blocking action, eliminating the need for separate control logic or manual intervention, thereby reducing operational complexity despite the added hardware.
Data Source
AI summary
A conveying device conveys a sheet selectively along a first conveying path and a second conveying path which are connected at a junction into a common path portion. A reading unit reads an image of a sheet conveyed in the common path portion. A shutter is disposed in the second conveying path at a position upstream of the junction in a sheet conveying direction. The shutter is movable between a first position and a second position. The actuator is disposed in the common path portion and movable between a third position and a fourth position in response to the shutter moving between the first position and the second position, respectively. In a case where a detection sensor detects that the actuator is at the fourth position, a controller controls the conveying device to convey the sheet along the second conveying path.