Variable-Transmittance ND Filter Voltage Control for Low-Temperature Response Lag
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Solution Overview
Problem
The response speed of liquid crystal ND filters decreases at low temperatures, leading to delayed exposure control and increased focus lag in compact digital cameras due to the slow response of the ND filter's transmittance change with applied voltage.
Innovation Solution
An action control device and method that includes a transmittance specifying unit and an applied voltage control unit to maintain the desired transmittance of a variable-transmittance ND filter by adjusting the applied voltage, ensuring optimal transmittance is achieved at the time of imaging preparation or instruction, using stored voltage data and response characteristic data to compensate for temperature and elapsed time effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid crystal ND filter is used to control exposure by changing transmittance, then exposure control is achieved, but response speed decreases at low temperatures causing focus lag
Solution Approach 1:
The system performs preliminary action by controlling the ND filter transmittance in advance during imaging preparation (half-press of shutter button) before actual imaging. The applied voltage control unit maintains the transmittance at the desired level at the timing when imaging preparation instruction is given, ensuring the filter is ready before focus adjustment begins, thereby preventing focus lag caused by slow response at low temperatures.
2Adaptability or versatility
If the transmittance of the ND filter is changed by applying voltage, then exposure adjustment is achieved, but the control is delayed at low temperatures
Solution Approach 1:
The system employs feedback by using a transmittance specifying unit that specifies the transmittance at a certain timing after voltage application starts, and an applied voltage control unit that adjusts the voltage to achieve the desired transmittance. This closed-loop control ensures the ND filter reaches the correct transmittance state despite temperature variations, eliminating control delay while maintaining exposure adaptability.
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 solution reduces focus lag by ensuring the ND filter's transmittance is properly controlled at the time of imaging, maintaining optimal brightness and reducing the impact of temperature on response speed.
Implementation Method 1
a liquid crystal ND filter is used to reduce a drastic change in exposure and thus reduce an observer's fatigue by changing a transmittance when a light quantity drastically changes
Implementation Method 2
an imaging unit configured to image an image through the variable-transmittance ND filter
Data Source
AI summary
According to the first aspect of the present technology, there is provided an action control device, including a transmittance specifying unit configured to specify a transmittance of a variable-transmittance neutral density (ND) filter having a transmittance that varies according to an applied voltage, and an applied voltage control unit configured to control a voltage to be applied to the variable-transmittance ND filter such that the transmittance specified by the transmittance specifying unit is obtained. The applied voltage control unit controls the voltage to be applied to the variable-transmittance ND filter such that the transmittance of the variable-transmittance ND filter specified by the transmittance specifying unit is maintained at a timing at which an imaging preparation instruction or an imaging instruction is given.