Printer Light Shielding Member for Optical Sensor Detection Accuracy
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Solution Overview
Problem
Portable printers face inaccurate sheet detection due to external light interference with optical sensors, which affects detection accuracy and sheet conveyance, especially when used outdoors.
Innovation Solution
Incorporating a light shielding member positioned closer to the opening than the optical sensor, combined with a guide member featuring a concavo-convex profile and ribs to ensure smooth sheet conveyance and detection accuracy by preventing external light from reaching the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light shielding member is provided to block external light from reaching the optical sensor, then detection accuracy is improved, but the structure becomes more complex and sheet conveyance may be hindered due to contact with the guide member surface
Solution Approach 1:
The guide member surface is segmented into two distinct regions: a concavo-convex portion with ribs for sheet conveyance and a flat surface portion for light shielding contact. This segmentation allows each region to perform its specific function independently, resolving the contradiction between sheet conveyance requirements and light shielding requirements.
Solution Approach 2:
Different surface qualities are applied to different locations on the guide member: the concavo-convex portion has a rough, ribbed surface optimized for reducing friction during sheet conveyance, while the flat surface portion has a smooth surface optimized for intimate contact with the light shielding member. This local differentiation resolves the contradiction between the two competing requirements.
2Object-affected harmful factors
If the light shielding member contacts the guide member to block light, then external light interference is reduced, but gaps may still exist due to the concavo-convex profile preventing complete light blocking
Solution Approach 1:
The guide member surface is divided into functional zones where the flat surface portion specifically serves as a light-blocking contact interface, separating the light shielding function from the sheet conveyance function performed by the concavo-convex portion. This ensures complete light blocking without compromising sheet handling.
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 effectively shields the optical sensor from external light, maintaining detection accuracy and facilitating smooth sheet conveyance even in intense outdoor light conditions, ensuring reliable operation of the portable printer.
Implementation Method 1
an optical sensor (sheet detection sensor) provided in the housing... image formation by the thermal line head are controlled on a basis of a result of sheet detection performed by an optical sensor
Implementation Method 2
The thermal line head generates a printing image on the sheet that is conveyed by the platen roller
Data Source
AI summary
A printer includes a casing in which a confronting portion is provided between a platen roller and a thermal line head. The casing has an opening. A guide member provides an inlet passage in the casing and includes a plurality of ribs and a flat surface portion. The ribs are spaced away from each other in a widthwise direction of a sheet. The ribs are in contact with the sheet to guide the sheet. The flat surface portion is positioned at a portion other than the plurality of ribs. An optical sensor is provided to optically detect the sheet. A light shielding member is provided in the casing and protrudes toward the inlet passage at a position closer to the opening than the optical sensor to the opening. The light shielding member has a protruding end in intimate contact with the flat surface portion.