3D Imaging Autofocus Using Displacement Compensation
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Solution Overview
Problem
Three-dimensional imaging devices with two imaging units face challenges in autofocus adjustment due to individual differences in lens diameters, light sensitivities, and other factors, leading to inaccuracies in focus positioning and reduced efficiency when performing auto focus operations independently on each unit.
Innovation Solution
A three-dimensional imaging device that includes a first and second imaging unit with focus lenses, a storage for focus position displacement data, and a focus adjustment unit that performs search operations within predetermined search ranges to accurately determine and adjust the in-focus positions of both lenses, taking into account the stored displacement data to compensate for individual differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If contrast AF is performed only in one imaging unit and the result is reflected to the other imaging unit, then time required for contrast AF is reduced, but individual differences cause displacement on the in-focus position of the other imaging unit
Solution Approach 1:
The patent performs contrast AF in only one imaging unit (partial action) rather than both units, accepting that one unit will have incomplete focus data. This reduces total AF time while the focus position is then adjusted using individual difference compensation to maintain accuracy when combining images.
Solution Approach 2:
The patent changes the focus position parameter by calculating a correction amount based on individual differences between imaging units. The focus position of the second imaging unit is adjusted by adding the correction amount to compensate for manufacturing variations, thereby maintaining focus accuracy despite performing AF in only one unit.
2Measurement precision
If individually performing AF operation in the respective imaging units, then focus accuracy is maintained, but efficiency is reduced
Solution Approach 1:
The patent performs complete contrast AF in only one imaging unit instead of both units, which maintains sufficient focus accuracy for the stereo pair while halving the AF operation workload and time required.
Solution Approach 2:
The patent introduces an intermediary correction mechanism that uses individual difference data to adjust the focus position of the second imaging unit. This intermediary step allows one unit to perform AF while the other unit's focus is derived through calculation, maintaining accuracy without requiring independent AF operations.
3Productivity
If the in-focus position of one imaging unit is reflected to the other imaging unit, then AF time is reduced, but individual differences in lens diameters and light sensitivities cause focus position displacement
Solution Approach 1:
The patent performs preliminary measurement of individual differences between imaging units during manufacturing or initial setup. These correction values are stored and applied during normal operation, allowing fast AF by reflecting one unit's focus position to the other while compensating for manufacturing variations.
Solution Approach 2:
The patent dynamically adjusts the focus position parameter of the second imaging unit by adding a correction amount that accounts for individual differences in lens diameters, focal lengths, and light sensitivities. This parameter transformation maintains focus accuracy while enabling efficient focus position reflection between units.
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 approach enables efficient and accurate autofocus adjustment by narrowing the search range for the second focus lens based on the first lens's in-focus position, reducing overall search time and ensuring focus accuracy despite individual differences between the imaging units.
Implementation Method 1
a first imaging sensor which performs photoelectric conversion on subject light imaged thereon through the first imaging optical system to output a first viewpoint image
Implementation Method 2
a second imaging sensor which performs photoelectric conversion on subject light imaged thereon through the second imaging optical system to output a second viewpoint image
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
An autofocus adjustment method for a three-dimensional imaging device according to an aspect of the present invention, includes: a step of, when a first lens position (in-focus position) is not found during search operation of a first focus lens of a first imaging optical system within a first search range, allowing a second focus lens of a second imaging optical system to perform search operation within the first search range, and during the search operation, searching for a second lens position at which the second focus lens focuses on the subject based on a second viewpoint image acquired from the second imaging unit; a step of allowing the second focus lens to move to the second lens position searched for within the first search range; a step of calculating the first lens position based on the second lens position searched for within the first search range and a focus position displacement amount preliminarily stored in a storage; and a step of allowing the first focus lens to move to the first lens position thus calculated.