Lens Control Device Focus Range Limiting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing autofocus technologies in imaging apparatuses struggle to control focus lenses accurately, especially in lens interchangeable systems where absolute position information is not available, leading to unintended focus positions.
Innovation Solution
A lens control device that includes a reception unit for designating end positions of a focus lens drive range, an acquisition unit for acquiring information on these positions, and a control unit for managing the focus lens drive based on the acquired information, ensuring the focus lens is driven within a predetermined movable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If focus limit control is implemented using relative position information, then the focus lens drive range can be limited, but the control accuracy deteriorates because absolute position information is not available
Solution Approach 1:
The system performs preliminary actions by driving the focus lens to predetermined end positions (near end and far end) to acquire reference position information before actual focus control operations. This establishes a known baseline from which relative position measurements can be accurately interpreted, enabling focus limit control even without absolute position sensors.
Solution Approach 2:
The system continuously monitors the focus lens position through pulse count feedback from the drive mechanism. By comparing the current pulse count against the predetermined end position references, the system can accurately determine the focus lens position within the drivable range and implement reliable focus limit control based on this feedback loop.
2Device complexity
If relative position information is used for focus lens control, then the device can operate with simpler positioning systems, but errors occur when focus rings are manually manipulated
Solution Approach 1:
The system performs preliminary calibration by driving the focus lens to the near end and far end positions to establish reference pulse counts. This preliminary action creates a known relationship between pulse counts and physical positions, allowing the system to maintain accurate tracking even during manual focus ring manipulation without requiring complex absolute positioning hardware.
Solution Approach 2:
The system uses continuous pulse count feedback from the focus lens drive mechanism to track position changes during manual manipulation. By comparing current pulse counts against the calibrated end position references, the system can detect when the focus lens reaches predetermined positions and adjust control accordingly, maintaining reliability despite the simpler positioning system.
3Ease of operation
If focus lens drive range is not limited, then the lens can be controlled freely, but unintended focus positions occur during autofocus operations
Solution Approach 1:
The system performs preliminary acquisition of end position information (near end and far end) and stores this as reference data. This preliminary action establishes the boundaries of the drivable range, enabling the autofocus system to automatically constrain focus lens movement within safe limits while maintaining operational freedom within those limits, preventing unintended focus positions.
Solution Approach 2:
The system continuously monitors focus lens position through pulse count feedback and compares it against the predetermined end position references. This feedback mechanism enables real-time control of the focus lens drive range during autofocus operations, automatically preventing the lens from reaching unintended positions while allowing free operation within the safe drivable range.
Data Source
AI summary
An imaging apparatus is able to perform limit control of limiting a drive range of a focus lens and performing control of the focus lens. When first information regarding an end position of the drive range of the focus lens in the limit control is set, a body control unit drives the focus lens from a position set as one end position of the drive range of the focus lens in the limit control on a near side and a far side to one end position of the movable range of the focus lens on a near side and a far side, and then stores information corresponding to a drive amount during the drive as the first information.