Tablet Side-Face Inspection Using Optical Path Conversion Sheets
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Solution Overview
Problem
Existing tablet inspection devices face challenges with large camera sizes due to telecentric optical systems and require adjustments for varying tablet shapes and sizes, leading to inefficiencies and increased device size.
Innovation Solution
A tablet inspection device using optical path conversion sheets to convert light paths from tablet side faces onto an imaging element, allowing simultaneous imaging and inspection of multiple tablets without multiple cameras, and accommodating shape and size variations without adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an object-side telecentric optical system is used to ensure in-focus image data for all tablets, then measurement precision is improved, but device size increases due to larger camera requirements
Solution Approach 1:
A transparent plate with an optical path conversion layer is introduced as an intermediary between the tablets and the imaging element. This layer converts oblique light paths into optical paths parallel to the optical axis, enabling the use of smaller cameras while maintaining in-focus image quality for all tablets regardless of their distance from the imaging element.
Solution Approach 2:
The optical path conversion layer changes the direction parameter of light rays by converting oblique incident light into light traveling parallel to the optical axis. This parameter transformation allows the imaging system to capture focused images of tablets at various positions without requiring large telecentric optical systems.
2Measurement precision
If multiple cameras are placed around the inspection area to capture side face portions of tablets, then measurement precision is improved, but device complexity increases due to physical interference and layout requirements
Solution Approach 1:
Multiple imaging functions are merged into a single camera system. The optical path conversion layer enables one imaging element to capture light reflected from all side face portions of multiple tablets simultaneously, eliminating the need for multiple cameras and their complex spatial arrangement.
Solution Approach 2:
The optical path conversion layer provides multi-functionality by directing light from different spatial positions (multiple tablet side faces) onto a single imaging element. This allows one camera to perform the inspection function that would otherwise require multiple cameras.
3Measurement precision
If a circular prism is used to obtain image data of the entire circumference of side face portions, then measurement precision is improved, but adaptability decreases when tablet shape or size changes
Solution Approach 1:
The optical path conversion layer provides universal imaging capability for tablets of various shapes and sizes. Unlike a circular prism that is geometry-specific, the layer converts oblique light paths into parallel optical paths regardless of the tablet's dimensions or shape, enabling a single configuration to inspect all tablet variations.
Solution Approach 2:
The optical path conversion layer transforms the imaging approach from geometry-dependent (circular prism matching tablet shape) to parameter-independent by converting light direction parameters. This allows the system to accommodate changes in tablet shape and size without requiring physical adjustments or replacements.
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 device achieves a compact and efficient inspection with high accuracy and precision, capable of inspecting the entire circumference of tablets without needing multiple cameras and accommodating shape or size changes.
Implementation Method 1
an optical path conversion sheet configured to convert an optical path of light that is emitted from the irradiation unit and that is reflected from a one side face area
Data Source
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AI summary
There is provided a tablet inspection device having a simple and compact configuration. A tablet inspection device 23 includes optical path conversion sheets 62a to 62d, each being configured to convert an optical path of light reflected from a one side face area of a tablet; and an imaging optical system 66 configured to form an image of the lights having the optical paths converted by the optical path conversion sheets 62a to 62d, on an imaging element 64c. The tablet inspection device 23 is configured to perform defective/ non-defective determination for a side face portion of the tablet, based on image data obtained by the lights imaged on the imaging element 64c. Each of the optical path conversion sheets 62a to 62d is provided to be laid across multiple lines of the tablets 5, when being viewed from an imaging element 64c-side. A plurality of the optical path conversion sheets 62a to 62d are provided along a transfer direction of the tablets. The plurality of optical path conversion sheets 62a to 62d respectively correspond to different one side face areas and are configured to convert the optical paths of lights reflected from the corresponding one side face areas into optical paths along a direction of an optical axis of the imaging optical system 66. A plurality of one side face areas respectively corresponding to the optical path conversion sheets 62a to 62d cover the entire circumference of the side face portion of the tablet.