Variable Focal Length Camera Autofocus via Mechanical Stress
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Solution Overview
Problem
Existing autofocus cameras with integrated optical devices of variable focal length face challenges in focusing, particularly at near distances, due to restrictive optical power ranges and sensitivity to manufacturing dispersions and temperature variations, leading to inefficient use of the optical device's power range and potential defocusing issues.
Innovation Solution
The camera employs a mechanical stress mechanism to adjust the optical power of the optical device with variable focal length without electrical actuation, using permanent stress to modify the device's optical power, allowing for focusing at infinity and near distances within a broader range of optical powers, and compensating for temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an optical device with variable focal length is integrated at the front of the camera, then autofocus functionality is achieved, but the optical power range becomes restrictive and manufacturing precision requirements increase
Solution Approach 1:
The patent changes the optical parameter (optical power) of the device with variable focal length by applying mechanical stress to the substrate. This allows adjustment of the optical power range to compensate for manufacturing dispersions and temperature variations, thereby resolving the contradiction between achieving autofocus functionality and maintaining manufacturing precision tolerances.
2Adaptability or versatility
If the optical device is positioned at the front of the camera, then autofocus is enabled, but access to the barrel for focusing operations is blocked
Solution Approach 1:
The patent replaces the mechanical focusing system (barrel rotation and displacement) with a stress application mechanism that directly adjusts the optical power of the device with variable focal length. This substitution eliminates the need for barrel access during focusing operations while maintaining autofocus functionality.
3Device complexity
If the optical device operates without electrical actuation, then device complexity is reduced, but optical power adjustment capability is limited
Solution Approach 1:
The patent achieves optical power adjustment without electrical actuation by applying mechanical stress to the substrate of the device with variable focal length. This physical stress changes the optical parameters of the device, enabling optical power range adjustment while maintaining low device complexity.
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 simplifies focusing, optimizes power usage, and reduces manufacturing constraints, enabling effective autofocus functionality across a wider optical power range while maintaining performance and temperature stability.
Implementation Method 1
a camera (100) according to any one of claims 1 to 7, characterised in that the initial optical power is made to vary from a reference configuration by exerting permanent stress on a region of the optical device (30) other than the central part of the membrane and the actuation region
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention relates to an autofocus camera (1) comprising: - an image sensor (10), - an optical block (20) comprising a plurality of lenses with fixed focal length, - an optical device (30) with variable focal length comprising: • a deformable membrane (301), • a support (302) to which a peripheral anchoring area (301c) of said membrane is connected, • a cavity (303) filled with a constant volume of fluid, said cavity being delimited at least in part by said membrane (301) and a support wall (302), • an actuation device (304) of a region (301b) of the membrane located between the peripheral anchoring area (301c) and a central part (301 a) of the membrane, configured to bend by application of electrical actuation voltage so as to displace some of the fluid volume towards the centre or towards the periphery of the cavity (303), wherein at least one region distinct from the central part (301a) and of the actuation region (301b) of the membrane is stressed mechanically permanently so as to cause permanent deformation of the central part of the membrane by the fluid, the focal distance of the optical device (30) at rest under the effect of said mechanical stress being different from the focal distance of said optical device at rest prior to application of said stress.