Optical Reader Layout for Low-Noise Passport Imaging
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Solution Overview
Problem
Optical information readers face challenges in capturing clear images due to optical noise from reflections within the housing, particularly when reading large media like passports, and require a compact design that allows easy handling of such media while minimizing the housing size.
Innovation Solution
The optical information reader incorporates a reflective member outside the primary imaging region to redirect illumination light, ensuring it is not captured in the image and uses a transparent protective plate to minimize optical noise, while arranging the operation part and display on an end portion of the housing to maximize the reading surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reading surface is covered with a dustproof plate and an illuminant is housed in the housing, then the reading surface is protected and illumination is provided, but optical noise is generated due to reflection of illumination light from the dustproof plate
Solution Approach 1:
The patent extracts the harmful reflected light from the imaging path by positioning the illuminant and its reflecting surface outside the imaging region of the imager. The imaging region is defined as the space between the image former and the reading surface, and the illuminant is arranged so that its reflected light does not enter this region, thereby removing the source of optical noise from the critical imaging path.
Solution Approach 2:
The patent resolves the spatial conflict between the illuminant and the imaging path by transitioning to a different spatial dimension. The illuminant is positioned in a region that is laterally displaced from the optical axis of the imager, allowing both the illuminant and the reading surface to coexist without their light paths intersecting in a way that causes reflection into the imaging region.
2Volume of moving object
If the housing size is reduced to make the reader compact, then portability is improved, but large media such as passports cannot be easily held over the reading surface
Solution Approach 1:
The patent extends the top surface of the housing in the lateral direction beyond the boundaries of the reading surface. This creates an extended operational surface where operation parts and displays can be positioned outside the reading area, allowing users to comfortably place and operate with large media like passports on the extended surface without increasing the footprint of the reading surface itself.
3Ease of operation
If operation parts and displays are provided on the top surface of the housing, then operability and visibility are improved, but the housing size increases
Solution Approach 1:
The patent positions operation parts and displays on the extended top surface of the housing, in a region that is laterally displaced from and does not overlap with the reading surface. This spatial separation allows both the reading function and the user interface to coexist on the same top surface without requiring additional vertical space or increasing the overall housing volume.
4Manufacturing precision
If the imaging region includes the space between the reading surface and the reflective member, then the optical path is optimized, but the reflected illumination is captured as optical noise in the image
Solution Approach 1:
The patent extracts the illuminant and its reflecting surface from the imaging region, creating a clear separation between the illumination subsystem and the imaging subsystem. The imaging region is strictly defined as the space between the image former and the reading surface, and the illuminant is positioned outside this region, ensuring that reflected illumination light cannot enter the imaging path and be captured as optical noise.
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 configuration effectively reduces optical noise and allows for a compact housing design that can easily handle large reading targets like passports, ensuring clear image capture and efficient operation.
Implementation Method 1
a reflective member (50) that reflects illumination light (Lf) emitted from the illuminant (21) toward the reading surface (14)
Data Source
AI summary
An optical information reader includes a reflective member that reflects illumination light emitted from an illuminant toward a reading surface, and an image former ensured to present an imaging target held over the reading surface within an imaging region of an imager. The imaging region includes a first imaging region defined between the image former and the reading surface, and a second imaging region defined between the reading surface and the reflective member so as to be continuous to the first imaging region when light is internally reflected on the reading surface inside the housing. The reflective member is arranged outside the first imaging region, while the illuminant, the imager and the image former are arranged outside the second imaging region. The illuminant emits illumination light toward a reflecting surface of the reflective member in the second imaging region.