Front Camera Discrete Focus Positions for Mobile Devices
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Solution Overview
Problem
Front-facing cameras in mobile devices have limited depth of field, making it difficult to achieve good focus quality for both faces and objects simultaneously, especially with smaller pixel sizes and larger apertures required for low-light performance, which increases cost and power consumption due to the need for auto-focus mechanisms.
Innovation Solution
A mobile device with a front-facing camera that has two discrete focus positions: a hyperfocal distance for camera mode and a range of 20 cm to 1 meter for video mode, allowing the camera to automatically switch between these positions without using auto-focus, thereby optimizing focus for selfies and video chatting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed focus camera is used, then the device structure is simple and cost is reduced, but the depth of field is limited and focus quality for both faces and objects cannot be achieved simultaneously
Solution Approach 1:
The patent applies the dynamics principle by implementing a camera module that can switch between two discrete focus positions (hyper-focal distance and macro distance) rather than being completely fixed. This allows the camera to adapt its focus characteristics dynamically based on the shooting scenario, achieving both simple structure and good focus quality for different use cases.
2Illumination intensity
If a small F-number is used, then low light performance is improved, but the depth of field becomes shorter and auto-focus is required
Solution Approach 1:
The patent applies the local quality principle by optimizing the optical parameters (F-number, focal length) specifically for two local scenarios: hyper-focal distance shooting and macro shooting. Instead of using a variable auto-focus system, the camera uses locally optimized optical characteristics for each shooting distance range, achieving good low light performance without requiring complex auto-focus mechanisms.
3Manufacturing precision
If an auto-focus mechanism is added, then focus quality is improved, but power consumption and process flow complexity increase
Solution Approach 1:
The patent applies the extraction principle by removing the complex auto-focus mechanism entirely and instead using a fixed optical system with two discrete focus positions. This extraction of the auto-focus component directly reduces power consumption and process flow complexity while maintaining adequate focus quality through the specially optimized optical parameters for different shooting distances.
Data Source
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AI summary
A device with a front facing camera having two discrete focus positions is provided. The device comprises: a chassis comprising a front side; a display and a camera each at least partially located on the front side; the camera adjacent the display, the camera facing in a same direction as the display, the camera configured to: acquire video in a video mode; acquire an image in a camera mode; and, discretely step between a first and second focus position, the first position comprising a depth of field ("DOF") at a hyperfocal distance and the second position comprising a DOF in a range of about 20 cm to about 1 metre; and, a processor configured to: when the camera is in the camera mode, automatically control the camera to the first position; and, when the camera is in the video mode, automatically control the camera to the second position.