Under-Display Camera Optical System with Freeform Lens
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Solution Overview
Problem
Camera modules installed under display panels in devices like smartphones face issues with image quality deterioration, reduced brightness, and ghosting due to light loss, necessitating an optical system with improved resolution and illuminance regardless of camera position.
Innovation Solution
A camera module with an optical system comprising five lenses sequentially arranged, including a fifth lens with a freeform surface, optimized to maintain improved optical characteristics and relative illumination, allowing for miniaturization and enhanced light transmission without increasing lens aperture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the camera is placed at the bottom of the display to achieve front display functionality, then the form factor is improved and front camera function is enabled, but brightness drops to 20% of existing level and image quality deteriorates due to light loss
Solution Approach 1:
The optical system is divided into multiple lens units (first through fifth lenses) with specific positive and negative refractive powers. This segmentation allows light to be progressively guided and concentrated through each lens, compensating for the light loss caused by the display panel and maintaining sufficient brightness at the sensor.
Solution Approach 2:
The patent combines multiple lenses with different refractive powers (positive and negative) into a single integrated optical system. This merging of optical elements with complementary functions enables the system to both guide light from the display and correct optical aberrations, achieving high resolution and sufficient illuminance simultaneously.
2Measurement precision
If multiple lenses with positive and negative refractive power are used to achieve high resolution, then resolution is improved, but device complexity increases
Solution Approach 1:
Each lens in the optical system is designed to perform multiple functions: the positive power lenses converge light and the negative power lenses diverge light to correct aberrations. This multi-functionality within a compact five-lens configuration achieves high resolution without requiring a larger or more complex optical system.
Solution Approach 2:
The patent optimizes specific parameters of each lens including refractive power, focal length, and curvature radii (as defined in the mathematical expressions). By precisely controlling these parameters, the system achieves high resolution with a compact configuration, balancing performance and complexity.
3Illumination intensity
If lens aperture is increased to improve light transmission and brightness, then illuminance is improved, but device size increases preventing miniaturization
Solution Approach 1:
Instead of increasing the physical aperture size to improve light transmission, the patent uses optical design principles including freeform surfaces and optimized refractive power distribution. This substitutes mechanical enlargement with optical optimization, maintaining high illuminance while enabling miniaturization of the overall device.
Solution Approach 2:
The patent changes optical parameters such as refractive power, focal length, and surface curvature (including freeform surfaces) to maximize light transmission efficiency. These parameter optimizations allow the system to achieve high illuminance with a compact lens aperture, preventing device size increase.
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 optical system achieves improved resolution and illuminance, maintaining image quality across various positions and reducing the need for post-correction, while enabling miniaturization and easy application to diverse display devices.
Implementation Method 1
an optical system including a first lens, a second lens, a third lens, a fourth lens, and a fifth lens sequentially arranged along an optical axis
Data Source
AI summary
An optical module disclosed to an embodiment includes a sensor, and an optical system including a first lens, a second lens, a third lens, a fourth lens, and a fifth lens sequentially arranged along the optical axis in the direction from the object side to the sensor side, and at least one of the object-side and sensor-side surfaces of the fifth lens includes a freeform surface.