Circular Loop Prism Plate for Image Pickup Illumination
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Solution Overview
Problem
Existing illumination optical systems for image pickup apparatuses face challenges in controlling the directivity of illumination light, leading to irregular light distribution and reduced precision due to regular-reflection noise, which is not adequately addressed by conventional prism plates that fail to emit light in the ridge-line direction and have limited control over light directivity.
Innovation Solution
A circular loop patterned illumination optical system featuring a prism plate with inclined portions and flat portions on its surface, allowing for the control of illumination light directivity by equalizing light within a light guide and emitting it in a controlled manner, including in the ridge-line direction, thereby reducing regular-reflection noise and improving precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional prism plate is used to control light direction, then the directivity of illumination light can be controlled to some extent, but the light distribution becomes irregular and cannot achieve uniform illuminance
Solution Approach 1:
The patent applies local quality by creating prism columns with different inclination angles at different locations on the prism plate surface. Specifically, prism columns in the first region have a first inclination angle while those in the second region have a second inclination angle, allowing different light deflection characteristics in different areas to achieve overall uniform light distribution
Solution Approach 2:
The patent segments the prism plate surface into multiple regions (first region and second region) with different prism column inclination angles. This segmentation allows independent optimization of light control in each region, enabling the system to achieve uniform illuminance across the entire subject surface
2Adaptability or versatility
If a blasted surface is used to diffuse light, then light scattering is achieved, but the system cannot precisely control the directivity and light distribution pattern
Solution Approach 1:
The patent combines local quality with blasted surfaces by applying blasted surface treatment to specific regions of the prism plate where light diffusion is needed, while maintaining precise prism column structures in other regions for directed light control. This allows the system to achieve both scattering capability and precise directivity control
3Device complexity
If conventional illumination optical systems are used, then the system structure is simple, but regular-reflection noise cannot be sufficiently reduced and reading precision deteriorates
Solution Approach 1:
The patent segments the illumination optical system into distinct functional components: light source, prism plate with segmented prism columns, and subject. This segmentation allows each component to be optimized independently - the prism plate controls light directivity while the segmented structure manages regular-reflection noise, thereby improving reading precision without excessive complexity
Solution Approach 2:
The patent applies local quality by creating different prism column configurations in different regions of the prism plate, which allows targeted control of light paths to specific areas of the subject. This localized control enables reduction of regular-reflection noise from specific regions while maintaining adequate illumination of others, improving overall reading precision
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 enables arbitrary control over illumination light directivity, reducing regular-reflection noise and enhancing the precision of image pickup by ensuring consistent light distribution across the image pickup apparatus, allowing for more effective utilization of illumination light and downsizing the system while maintaining efficiency.
Implementation Method 1
The prism plate allows incident light that enters from the prism-surface-201 side to be deflected by refraction at the prism surface 201 and the plane surface 203 so as to control the outgoing direction
Data Source
AI summary
An illumination optical system for an image pickup apparatus includes a plurality of light sources arranged in a circular loop pattern and a prism plate shaped like a circular loop. the prism plate includes a prism surface at which illumination light from the light sources enters and on which a plurality of prism columns arranged in a circular loop pattern in a circumference direction of the prism plate are formed and an outgoing surface from which the illumination light is emitted. the prism surface includes a flat portion on at least one of a peak formed by each of the plurality of prism columns and a trough formed between the plurality of prism columns. the flat portion is substantially parallel to a tangential direction of the prism plate.