Spherically Curved Photosensor Camera Design for Compact High-Resolution Imaging
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Solution Overview
Problem
Conventional small cameras in mobile devices capture images at lower resolutions and with lower image quality due to limitations in pixel size and lens systems, such as z-height constraints and manufacturing limitations, which restrict achievable resolution and image quality.
Innovation Solution
A high-resolution camera design featuring a spherically curved photosensor and a lens system with in-line lens elements that refract light to form an image on the concave surface of the photosensor, following the f*θ image height law, allowing for a small pixel size while maintaining sharp, high-resolution images, and including a third lens element to correct for chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional planar photosensors and lens systems are used in small cameras, then the camera package size can be reduced, but image resolution and image quality deteriorate
Solution Approach 1:
The patent applies spherical curvature to the photosensor surface, transforming it from a conventional planar structure to a spherically curved surface. This curvature allows the photosensor to better match the natural focusing characteristics of the lens system, enabling high-resolution imaging in a compact form factor. The spherical photosensor surface radius is specifically designed to be within about 20% of the lens system's effective focal length, optimizing the balance between package size and image quality.
2Measurement precision
If pixel size is reduced to achieve higher resolution in small cameras, then image resolution improves, but manufacturing precision and image quality deteriorate due to limitations in small pixel fabrication
Solution Approach 1:
The patent changes the fundamental geometric parameter of the photosensor from planar to spherical curvature. This parameter change allows the system to achieve high resolution not by minimizing pixel size to the point of manufacturing difficulty, but by optimizing the overall optical geometry. The spherical surface with radius within 20% of the effective focal length creates favorable optical conditions that maintain image quality while using practically manufacturable pixel sizes.
3Length of moving object
If conventional lens systems are used with small axial length, then camera compactness improves, but image quality deteriorates due to z-height constraints
Solution Approach 1:
The spherical photosensor surface fundamentally changes the optical path geometry, allowing the lens system to achieve proper focus with reduced axial length. The curved surface naturally accommodates the converging light cones from the lens elements, eliminating the need for extended z-height distances required by planar sensors. This enables compact axial length while maintaining diffraction-limited image quality.
Solution Approach 2:
By changing the photosensor surface from planar to spherical with radius within 20% of effective focal length, the patent optimizes the optical parameters to achieve high image quality in a compact axial length configuration. This parameter change allows the lens system to operate at its diffraction limit without requiring excessive back focal length or complex lens element spacing.
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
Enables the capture of sharp, high-resolution images in a small package size, suitable for mobile devices, with a total axial length of 2.0 mm or less, and includes a distortion correcting algorithm to address barrel distortion.
Implementation Method 1
The lens system may include in-line lens elements that refract light from an object field to form an image on the concave surface of the photosensor
Implementation Method 2
the lens system may further include a third lens element, positioned between the first two lens elements and the photosensor, with optical characteristics that correct for chromatic aberration of the first and second lens elements
Data Source
AI summary
A camera including a spherically curved photosensor and a lens system. Effective focal length f of the lens system is within about 20% of the radius of curvature of the photosensor. An image is formed by the lens system at a spherically curved image plane that substantially matches the concave surface of the photosensor. The camera is diffraction-limited with small spot size, allowing small pixels to be used in the photosensor. F/number may be 1.8 or less. The spherically curved image plane formed by the lens system at the photosensor follows f*θ image height law. Chief rays of the lens system are substantially normal to the concave surface of the photosensor. Total axial length of the camera may be 2.0 mm or less. The camera may be implemented in a small package size while still capturing sharp, high-resolution images, making the camera suitable for use in small devices.