Video Camera Light Sensor Variable Field of View
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Solution Overview
Problem
Current camera systems with retractable IR-cut filters often experience flickering between night-mode and day-mode due to difficulties in quantifying IR contribution, leading to unnecessary actuator wear and annoying video stream issues, especially when switching back to night-mode after IR-filter insertion.
Innovation Solution
A video camera system with a separate light sensor that measures ambient light levels in a variable field of view, allowing for precise control of the IR-cut filter based on the current field of view, eliminating the need for additional mechanical actuators or variable optics, and enabling accurate switching between night-mode and day-mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light sensor with IR-cut filter is used to control IR-filter switching, then the light level in visible spectrum can be accurately measured, but flickering between night-mode and day-mode still occurs
Solution Approach 1:
The patent introduces a variable field of view for the light sensor that dynamically adapts to the current field of view of the camera. This is achieved by providing a plurality of light sensors with different fields of view or by making the field of view variable, allowing the system to select or adjust the appropriate field of view to match the camera's current settings, thereby preventing flickering caused by mismatched measurement areas.
Solution Approach 2:
The patent segments the light sensing function by providing multiple light sensors, each with a different field of view. This segmentation allows the system to independently measure light levels in different angular ranges, and select the appropriate sensor or combination of sensors that corresponds to the current camera field of view, improving the accuracy and stability of mode switching decisions.
2Use of energy by moving object
If the IR-filter is completely removed for night-mode, then more IR radiation reaches the image sensor, but the actuator experiences considerable wear from repeated switching
Solution Approach 1:
The patent enables partial retraction of the IR-filter based on the measured light level. Instead of only complete insertion or complete removal, the filter can be retracted to a partial extent when the light level is insufficient but not completely dark. This partial action reduces the frequency of complete switching cycles, thereby reducing actuator wear while still allowing sufficient IR radiation to reach the sensor in low-light conditions.
3Manufacturing precision
If the IR-filter is inserted for day-mode, then color image quality is maintained, but the light level becomes too low causing unnecessary switching back to night-mode
Solution Approach 1:
The patent implements a dynamic field of view adjustment for the light sensor that matches the camera's current field of view. By dynamically adapting the measurement area to the actual imaging area, the system accurately assesses the light level in the relevant region, preventing premature switching back to night-mode due to measurements taken from an inappropriate area.
Solution Approach 2:
The system uses feedback from the light sensor measurement to control the IR-filter position. The measured light level is continuously monitored and used to adjust the filter state, creating a closed-loop control system that responds to actual lighting conditions in the camera's field of view, thereby maintaining color image quality while preventing unnecessary mode switching.
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 system effectively reduces flickering and wear on actuators by accurately determining when to switch modes, ensuring stable video streaming and extending the lifespan of camera components.
Implementation Method 1
a separate light sensor with an IR-cut filter may be used for controlling when to insert and when to remove the IR-filter, such that when the level of ambient light becomes too low
Implementation Method 2
An IR (cut) filter may be used during daylight conditions, enabling acquisition of color images
Implementation Method 3
Pixels of the image sensor will then operate in a first manner, where the incident light is divided into colors and detected as a charge on individual photodetectors thus enabling color separation
Implementation Method 4
The addition of an IR light source may enhance the image even further
Data Source
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Figure 3A~8D
Figure 9
AI summary
A video camera system comprises an imaging system having a camera lens and an image sensor, and a retractable IR-cut filter, and a control unit for controlling the imaging system. The video camera system has a day-mode in which the IR-cut filter is arranged in front of the image sensor, and a night-mode in which the IR-cut filter is retracted from its position in front of the image sensor. Furthermore, the video camera has a field of view defined by properties of its imaging system, and it comprises a separate light-sensor for measuring an ambient light level so as to support a decision regarding when to actuate a transfer from night-mode to day-mode, or vice versa. The camera system is characterized in that the separate light sensor has imaging optics and is enabled for a variable field of view, which is aligned with a field of view of the video camera system, and in that a current field of view of the video camera system is used when selecting an active field of view of the separate light sensor.