ND Filter Exposure Control for Vertical Resolution
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Solution Overview
Problem
Existing imaging apparatuses experience resolution degradation of optical object images due to the partial application state of Neutral Density (ND) filters, where different optical densities applied to the aperture lead to image-forming point differences and light diffraction, degrading image quality.
Innovation Solution
An imaging apparatus and exposure control method that adjust the aperture area and ND filter position using a control section, a memory storing exposure control tables, and light intensity detection to avoid partial application states of the ND filter, ensuring optimal exposure control without degrading vertical resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If exposure control is carried out by adjusting both aperture area and ND filter position, then exposure control flexibility is improved, but vertical resolution is degraded due to partial application state of ND filter
Solution Approach 1:
The patent extracts the problematic partial application state of the ND filter from the exposure control process. By detecting when the ND filter would be in a partial application state and excluding these specific aperture-ND filter combinations from the exposure control table, the solution removes the source of vertical resolution degradation while preserving exposure control flexibility through alternative settings.
Solution Approach 2:
The patent implements feedback by using light intensity detection to monitor the actual exposure conditions and comparing them against pre-calculated exposure control tables. The system detects the brightness of the object and selects appropriate aperture and ND filter combinations from the exposure control table, ensuring that combinations causing partial application states are automatically avoided, thus maintaining both exposure flexibility and image quality.
2Use of energy by moving object
If ND filter is applied partially to the aperture, then exposure amount can be adjusted, but image-forming point difference and light diffraction occur degrading image quality
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal aperture and ND filter combinations in an exposure control table before actual imaging. The table is generated in advance with aperture values and ND filter transmission rates that avoid partial application states. During imaging, the system simply retrieves pre-determined combinations based on detected brightness, ensuring image quality is maintained without real-time complex calculations.
3Adaptability or versatility
If exposure control table includes all aperture and ND filter combinations, then exposure control range is expanded, but partial application states cause resolution degradation
Solution Approach 1:
The patent applies local quality by making the exposure control table non-uniform - it includes all possible aperture and ND filter combinations except those that would create partial application states. The exposure control table has different densities of valid combinations depending on the aperture value, with certain aperture values having restricted ND filter options. This localized exclusion of problematic combinations maintains overall exposure control versatility while preventing resolution degradation in specific regions of the parameter space.
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 solution enables optimal exposure control that maintains vertical resolution and avoids image quality degradation by determining and adjusting for ND filter positions and aperture settings, ensuring consistent image quality across varying brightness levels.
Implementation Method 1
an ND filter 30, which adjusts light intensity of an optical object image received by the light receiving surface 14a of the solid state image sensor 14
Implementation Method 2
an aperture blade 26a, 26b, which forms an aperture 26 for the imaging lens 12a, 12b, 12c, and 12d
Data Source
AI summary
An imaging apparatus includes a shutter drive section, an aperture blade drive section, an ND filter drive section, a light intensity detection section, a memory, and a control section. The shutter drive section opens and closes a shutter for a light receiving surface of a solid state image sensor. The aperture blade drive section drives an aperture blade forming an aperture. The ND filter drive section adjusts the position of an ND filter against the aperture. The control section calculates the exposure control voltage representing an exposure amount from the light intensity signal output from the light intensity detection section, and reads out the F value and the shutter speed corresponding to the exposure control voltage from the exposure control table stored in the memory so as to avoid a partial application state of the ND filter, for controlling respective drive sections.