Variable Focal Length Lens Temperature Correction
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Solution Overview
Problem
Temperature changes in the fluid or vibrating member of a variable focal length lens apparatus affect the focal length, leading to abnormal image detection even when pulse illumination is provided under the same conditions.
Innovation Solution
A variable focal length lens apparatus that includes a temperature detector to correct the timing of the light emission signal based on temperature information, ensuring that the image is detected at the desired focal length by adjusting the phase of the drive signal in response to temperature fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable focal length lens apparatus uses a fluid lens system with AC voltage applied to generate standing waves, then the focal length can be varied by adjusting the amplitude of the drive signal, but temperature changes in the internal fluid or vibrating member cause the focal length to shift abnormally even when the drive signal timing remains the same
Solution Approach 1:
The patent implements a feedback mechanism where the actual focal length is detected and compared with the target focal length, and the drive signal amplitude is automatically adjusted based on the detected focal length to maintain accuracy despite temperature changes
Solution Approach 2:
The patent changes the drive signal amplitude parameter dynamically to compensate for temperature-induced focal length shifts, thereby maintaining the desired focal length under varying thermal conditions
2Productivity
If pulse illumination is provided synchronized with the phase of the sine wave drive signal, then images at multiple focal lengths can be obtained simultaneously, but temperature changes cause the focal length corresponding to the same drive signal phase to shift
Solution Approach 1:
The system detects the actual focal length for each drive signal phase and uses this feedback to correct the timing or amplitude of the drive signal, ensuring that the intended focal length is achieved even when temperature changes occur
Solution Approach 2:
The patent performs preliminary detection of the focal length corresponding to each drive signal phase under various temperature conditions and stores correction data, which is then applied during operation to maintain measurement precision
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 reliably maintains the desired focal length despite temperature changes, ensuring accurate image detection by correcting the focal length variation using temperature data stored in a correction value table or function.
Implementation Method 1
a hollow cylindrical vibrating member formed of a piezoelectric material. In the lens system, when AC voltage is applied to both an inner circumferential surface and an outer circumferential surface of the vibrating member, the vibrating member expands and contracts in a thickness direction and causes the fluid on an inner side of the vibrating member to vibrate.
Implementation Method 2
By adjusting a frequency of the applied voltage in response to the natural frequency of the fluid, a standing wave of concentric circles is formed in the fluid
Implementation Method 3
concentric circular regions having different refractive indexes are formed centered on a center axis line of the vibrating member. Therefore, in the lens system, when light transits along the center axis line of the vibrating member, the light travels along a path that either magnifies or reduces the light in accordance with the refractive index of each concentric circular region.
Data Source
AI summary
A variable focal length lens apparatus includes a lens system where a refractive index changes in response to an input drive signal; a field lens arranged on the same optical axis as the lens system; an image detector detecting an image of a measured object through the lens system and the field lens; a pulse illuminator providing pulse illumination of the measured object based on an input light emission signal; a temperature sensor detecting temperature information for an interior of the lens system; and a controller outputting the drive signal and the light emission signal in addition to correcting the timing of the light emission signal based on the temperature information.