Light Shielding Cover for Photo Sensor False Detection
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Solution Overview
Problem
Image forming apparatuses, such as laser printers, often falsely detect the presence of a recording medium due to reflected light entering the photo sensor, leading to incorrect operation of the sheet feeding mechanism.
Innovation Solution
A light shielding cover is integrated with the sensor actuator, positioned to prevent light other than that emitted from the light emitting element from entering the light receiving element, ensuring accurate detection by shielding the sensor from external light reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the photo sensor is used to detect recording medium presence, then detection function is provided, but false detection occurs due to reflected light entering the sensor
Solution Approach 1:
A light shielding cover is introduced as an intermediary element between the light source and the photo sensor. This cover selectively blocks reflected light from entering the sensor while allowing the direct light path to remain open, thus mediating the interaction between light and sensor to prevent false detection
Solution Approach 2:
The harmful reflected light is extracted or removed from the light path reaching the sensor by using the light shielding cover. The cover is positioned to specifically extract only the unwanted reflected light components while preserving the useful direct light for accurate detection
2Measurement precision
If a light shielding structure is added to prevent false detection, then detection accuracy improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The light shielding cover is merged with the existing sensor actuator structure, forming an integrated component. This combination eliminates the need for separate light shielding parts, reducing assembly steps and manufacturing complexity while maintaining the light shielding function necessary for precise detection
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 solution effectively prevents false detection of recording sheets in the manual feed tray, ensuring reliable operation of the sheet feeding mechanism without increasing the number of assembly operations or manufacturing costs.
Implementation Method 1
The photo sensor has a light emitting element and a light receiving element, which are disposed facing each other
Implementation Method 2
The photo sensor has a light emitting element and a light receiving element, which are disposed facing each other
Implementation Method 3
The sensor actuator has a light path shielding plate that moves between a position where the light path shielding plate cuts off a light path from the light emitting element to the light receiving element
Data Source
AI summary
An image forming apparatus that forms an image on a recording medium includes a sensor including a light emitting element configured to emit light and a light receiving element configured to receive light emitted from the light emitting element. A sensor actuator is configured to cause a transition between a first state where the light emitted from the light emitting element is received at the light receiving element and a second state where the light emitted from the light emitting element is not received at the light receiving element in response to a recording medium being detected. A light shield is coupled to the sensor actuator and configured to cover at least a part of the sensor and to prevent light other than light emitted from the light emitting element from entering the light receiving element in the second state.