Imaging Optical System with Reflection Surface for Compact High-Resolution Reading
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Solution Overview
Problem
Existing reading apparatuses with large-sized image pickup elements face a challenge in achieving high resolution while maintaining a compact size, as the ratio between optical system components leads to increased size and aberration correction limitations.
Innovation Solution
The reading apparatus incorporates a first optical system with a positive power reflection surface and a second optical system that satisfies specific conditions for the distance and image height ratios, along with aspherical lens design and aperture stop, to form an intermediate image and correct aberrations with a smaller number of lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large-sized image pickup element is used to achieve high resolution reading, then the reading resolution is improved, but the optical system length increases and the reading apparatus size increases
Solution Approach 1:
The optical system is divided into two separate systems: a first optical system that forms an intermediate image, and a second optical system that images the intermediate image onto the image pickup element. This segmentation allows each subsystem to be optimized independently, reducing the total optical path length while maintaining high imaging quality for large-sized image pickup elements
Solution Approach 2:
An intermediate image is introduced as a mediator between the object and the final image on the image pickup element. The first optical system creates this intermediate image, which then serves as the object for the second optical system. This intermediary approach enables compact optical design by breaking the direct optical path into manageable segments
2Measurement precision
If the ratio TD/IML is set larger than 20 to achieve high resolution, then the reading resolution is improved, but the reading apparatus size increases
Solution Approach 1:
The patent changes the critical parameter TD/IML from being greater than 20 to being within the range of 5 to 20. This parameter change fundamentally alters the optical system's scale, enabling high-resolution imaging with large-sized image pickup elements while reducing the overall apparatus size to a compact form factor
3Area of stationary object
If a compact optical system is designed to reduce apparatus size, then the reading apparatus size is reduced, but aberration correction becomes difficult
Solution Approach 1:
By segmenting the optical system into two separate systems with distinct functions, each system can be optimized for aberration correction within its own subsystem. The first system handles object-to-intermediate-image transformation, while the second handles intermediate-image-to-final-image transformation, allowing comprehensive aberration control in a compact design
Solution Approach 2:
The patent employs at least one aspherical surface in the optical system to effectively correct spherical aberration and other optical aberrations. The aspherical surfaces enable compact optical design while maintaining high imaging quality by controlling light ray paths more efficiently than spherical surfaces
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 allows for high-resolution reading across a compact size, effectively managing optical length and aberration correction, even with large-sized image pickup elements, by optimizing the optical system's design and component placement.
Implementation Method 1
a first optical system including at least one reflection surface configured to reflect a light flux from the object
Implementation Method 2
a second optical system configured to image the intermediate image onto a light-receiving surface of the image pickup element
Data Source
AI summary
Provided is a reading apparatus of the present invention, including: an image pickup element configured to pick up an image of an object; a first optical system including at least one reflection surface configured to reflect a light flux from the object, the first optical system being configured to form an intermediate image of the object; and a second optical system configured to image the intermediate image onto a light-receiving surface of the image pickup element, in which: the at least one reflection surface includes a first reflection surface which is closest to the light-receiving surface on an optical path, and which has a positive power; and the following condition is satisfied:5≤TD/IML≤20where TD represents a maximum distance from the first reflection surface to the light-receiving surface on the optical path, and IML represents a maximum image height of the second optical system.