Eccentric Lens Cancels Comatic Aberration in Projection Display
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Solution Overview
Problem
Conventional projection-type display devices using reflection-type image display elements suffer from image deterioration due to comatic aberration caused by air gaps, limiting high-definition image quality.
Innovation Solution
Incorporating a prism unit with an obliquely disposed air gap and at least one eccentric lens in the projection lens system to cancel out comatic aberration, thereby improving image quality by reducing flare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an air gap is used to guide illumination light by total reflection, then the device structure is simplified and illumination efficiency is improved, but comatic aberration occurs causing image deterioration and flare
Solution Approach 1:
The invention utilizes the comatic aberration generated by the air gap to illuminate areas that would otherwise be dark. The aberration causes light to spread into regions adjacent to the main image, effectively converting the harmful optical defect into a beneficial illumination source for peripheral or background areas of the display.
2Object-affected harmful factors
If optical elements are added to correct astigmatism in an inclined dichroic filter, then image quality is improved, but device complexity increases and retrofitting becomes difficult
Solution Approach 1:
The invention extracts the astigmatism correction function from the traditional lens system and relocates it to a dedicated correction optical element positioned in a specific location within the optical path. This separation allows for targeted correction without requiring complex modifications to the entire lens system, making it easier to implement in existing devices.
Solution Approach 2:
The invention introduces a correction optical element as an intermediary component between the dichroic filter and the lens system. This intermediate element specifically addresses the astigmatism issue without requiring direct modification of the existing lens elements, thereby maintaining the original lens system while adding corrective capability.
3Object-affected harmful factors
If a conventional lens system is used without air gap, then comatic aberration is avoided, but illumination light guidance becomes less efficient
Solution Approach 1:
The invention converts the harmful comatic aberration produced by the air gap into a beneficial effect for illuminating peripheral areas. Instead of eliminating the air gap and its associated aberration, the system harnesses the aberrated light to provide useful illumination, thereby maintaining high illumination efficiency while productively utilizing the optical defect.
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 enhances image quality by minimizing flare from comatic aberration, enabling the creation of bright, high-definition projection-type display devices without compromising brightness.
Implementation Method 1
an air gap for guiding illumination light to the image display element by total reflection
Implementation Method 2
comatic aberration produced when the image light is transmitted through the air gap
Data Source
AI summary
A projection-type display device, provided with: a reflection-type image display element (DP), in which illumination light is reflected at an image display surface so as to be converted to image light and emitted; a prism unit (PU1) that bends a light path of the illumination light and transmits image light; and a projection lens system (PO) that projects the image light transmitted through the prism unit onto a screen. The prism unit (PU1) has an air gap (AG) that is disposed obliquely with respect to the main light rays of the image light emitted from the center of the image display surface. At least one lens (DL) in the projection lens system (PO) is eccentric in relation to the optical axis of the projection lens system (PO) so that comatic aberration produced when the image light is transmitted through the air gap (AG) will be canceled out.