Surveillance Camera Depth of Field Control via Dynamic Aperture Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image capture apparatuses for surveillance struggle to maintain an appropriate depth of field without increasing noise, as they require complex subject detection and distance measurement systems to control the diaphragm and focus lens effectively.
Innovation Solution
An image capture apparatus with an image sensor, processor, memory device, and control units that calculate the in-focus level and adjust the diaphragm and focus lens positions to maintain a specific region within the depth of field, using user-set focus positions and gain control to optimize depth of field while minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a small aperture is used to place all subjects within depth of field, then subject visibility is improved, but noise in the acquired image increases
Solution Approach 1:
The patent implements dynamic control of the diaphragm aperture and focus lens position based on real-time detection of subject distances. The system continuously adjusts the aperture size and focus position to maintain optimal depth of field coverage while minimizing noise, rather than using a fixed small aperture setting.
Solution Approach 2:
The system changes the aperture diameter and focus lens position parameters based on detected subject distances. By calculating appropriate aperture sizes and focus positions that maintain depth of field coverage, the system achieves clear subject visibility without unnecessarily small apertures that would increase noise.
2Measurement precision
If subject detection and distance measurement systems are added to control diaphragm and focus lens, then depth of field control is improved, but device complexity increases
Solution Approach 1:
The image sensor serves multiple functions: it captures the subject image and also provides data for calculating the in-focus level. This multi-functionality reduces the need for separate dedicated detection and measurement systems, thereby controlling device complexity while maintaining precise depth of field control.
Solution Approach 2:
The system uses its own image sensor output to calculate the in-focus level and determine appropriate diaphragm and focus lens settings. This self-service approach eliminates the need for external or separate detection systems, reducing overall device complexity while achieving accurate depth of field control.
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
The apparatus effectively maintains an appropriate depth of field, reducing noise and complexity by dynamically controlling the diaphragm and focus lens based on in-focus levels and user inputs, ensuring all subjects are in focus without excessive noise amplification.
Implementation Method 1
an image sensor configured to capture a subject image, formed by an imaging optical system having a focus lens and a diaphragm, and to output an image signal
Implementation Method 2
an imaging optical system having a focus lens and a diaphragm
Data Source
AI summary
A focusing adjustment method includes calculating an in-focus level of an imaging optical system including a diaphragm and a focus lens based on an output signal of an image sensor, setting an optional focus lens position based on an instruction from a user, performing first control for determining a diaphragm driving direction and a diaphragm driving amount, based on the in-focus level; and performing second control for determining a moving direction of the focus lens, based on an output signal of the image sensor and determining a driving amount of the focus lens based on the diaphragm driving amount, wherein, in the first control and the second control, the diaphragm and the focus lens are controlled in such a range that a specific region of captured image can be included in depth of field.