Image Sensor Unit Light Blocking Portion Stray Light
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Solution Overview
Problem
In image sensor units where the light source and image sensor are mounted on the same circuit board, a portion of the light emitted from the light source becomes stray light and is received by the image sensor, leading to inefficiencies in image reading processes.
Innovation Solution
An image sensor unit design that includes a light guide with a bent portion and a light condenser, housed within a frame that has a light blocking portion protruding towards the circuit board between the light source and image sensor, along with conductive portions overlapping with external lines to prevent stray light from entering the image sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the light source and image sensor are mounted on the same circuit board, then the device complexity is reduced and manufacturing cost is lowered, but stray light from the light source is received by the image sensor causing measurement errors
Solution Approach 1:
A light blocking portion is introduced as an intermediary element between the light source and image sensor. This light blocking portion protrudes from the circuit board surface and blocks stray light from reaching the image sensor, while allowing the light source and image sensor to remain mounted on the same circuit board. The light blocking portion acts as a mediator that prevents harmful light interference without requiring separate mounting boards.
Solution Approach 2:
The light blocking portion is positioned in advance to prevent stray light from reaching the image sensor. By placing the light blocking portion between the light source and image sensor before stray light can interfere with the imaging process, the design proactively eliminates the harmful effect of stray light while maintaining the simplified single-board mounting structure.
2Measurement precision
If a light blocking portion is added to prevent stray light, then measurement precision is improved, but the device complexity increases
Solution Approach 1:
The light blocking portion is merged with the circuit board structure, forming an integrated component rather than a separate assembly. The light blocking portion protrudes from the circuit board surface and is positioned to block stray light, while the circuit board continues to serve its primary function of mounting and electrical connection. This merging approach adds light blocking functionality without requiring a completely separate structural component.
Solution Approach 2:
The circuit board serves multiple functions: it provides electrical connections for the light source and image sensor, and through the integrated light blocking portion, it also provides optical shielding. The light blocking portion itself serves dual purposes by both blocking stray light and maintaining the structural integrity of the mounting assembly, reducing the need for additional specialized components.
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
Effectively prevents stray light from being received by the image sensor, improving the accuracy and efficiency of image reading operations without the need for expensive materials like black solder resist.
Implementation Method 1
a light guide where a light emitter and a bent portion are formed... light emitted from a light source is incident on an incident surface of a bent portion of a light guide, passes through the insides of the bent portion and the light emitter, and is linearly emitted from a light emission surface of the light emitter
Implementation Method 2
a light condenser that focuses light from the object of illumination... an image sensor that receives the light focused by the light condenser
Implementation Method 3
an image sensor that receives the light focused by the light condenser, and converts the light into an electric signal
Data Source
AI summary
In an image sensor unit, a frame includes a light blocking portion that protrudes toward one surface of a circuit board at a position between a light source and an image sensor. On the one surface of the circuit board, a conductive portion that continuously overlaps with external lines of the light blocking portion in a sub-scan direction in a view of the circuit board in a direction orthogonal to the one surface is formed.