Camera Zoom Lens Driving Rate Coordination
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Solution Overview
Problem
Conventional camera equipment with zoom and auto-focus functions often result in image defocusing during zooming operations, leading to increased burden on the camera's control unit due to frequent adjustments in focus speed based on high-frequency components of the video signal.
Innovation Solution
The camera equipment includes a distance-information obtaining unit, zoom driving unit, focus driving unit, drive controlling unit, and driving-rate controlling unit, which synchronize and adjust the zoom and focus lens positions and driving rates to ensure that the zoom and focus driving times coincide at predetermined zoom magnification factors, maintaining image focus without frequent control adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the focus speed is frequently altered based on high frequency components of the video signal during zooming operation, then object-image defocusing is restricted within an allowable range, but the burden on the camera equipment control unit increases significantly
Solution Approach 1:
The patent calculates and stores driving time data for zoom lens and focus lens in advance, organized by zoom magnification factor intervals. This preliminary preparation allows the control unit to quickly retrieve and apply appropriate driving parameters without performing complex real-time calculations, thereby reducing processing burden while maintaining focus stability during zoom operations
Solution Approach 2:
The patent dynamically adjusts the driving rates of zoom lens and focus lens based on the current zoom magnification factor and pre-calculated driving time data. The control unit modifies focus driving rate according to the relationship between zoom driving rate and focus driving time, enabling adaptive control that maintains image focus while optimizing processing efficiency
2Reliability
If the focus lens is controlled to move to a position corresponding to the object distance after zooming operation, then the object image can be brought into focus at the altered zoom position, but the object image becomes out of focus during the zooming operation
Solution Approach 1:
The patent implements continuous coordination of zoom lens and focus lens driving operations. By synchronizing the driving rates and using pre-calculated driving time data, the system maintains continuous focus adjustment during the entire zooming process, ensuring the object image remains within the allowable focus range throughout the transition rather than allowing defocusing to occur and then correct it afterward
Solution Approach 2:
The control unit uses feedback from the zoom lens position and pre-stored driving time data to dynamically adjust the focus lens driving rate. This feedback mechanism ensures that the focus lens reaches its target position at the correct moment during zooming, preventing image defocusing while maintaining smooth and accurate focus tracking
Data Source
AI summary
In a camera, a zoom lens and focus lens are driven to predetermined positions corresponding to a zoom magnification factor to be changed upon a demand for altering the zoom magnification factor. During a zooming operation after the camera has been brought into focus by an auto-focusing function, driving rates of the zoom lens and focus lens are controlled in each of zoom intervals to set driving times required to drive the zoom lens and focus lens to positions corresponding to the next zoom magnification factor to the quickest zoom driving time Tz of the zoom lens and the longer driving time among the quickest focus driving times Tfa, Tfb of the focus lens corresponding to object distances.