Digital Camera Light Division for Focus and Exposure
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Solution Overview
Problem
Conventional digital cameras face challenges in maintaining focus and image quality during consecutive image capture modes, as the focus sensor is not effectively able to detect focus after the aperture ratio is adjusted for appropriate exposure, leading to potential blurring due to subject or camera positional displacement.
Innovation Solution
A digital camera system that divides light into two beams, with one beam entering an image sensor for image capture and the other entering a focus sensor for focus detection, featuring an exposure condition determining section that sets the aperture ratio to ensure the focus sensor can detect focus, even after adjusting for exposure, and a focus control section that continuously monitors and adjusts the focus during image data output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the aperture ratio is adjusted to achieve appropriate exposure, then the image sensor can capture images with correct exposure, but the focus sensor cannot detect focus due to insufficient light
Solution Approach 1:
The patent divides the light path into two separate beams using a half mirror: one beam goes to the image sensor for exposure-critical imaging, while the other beam goes to the focus sensor for focus detection. This segmentation allows each sensor to receive optimized light amounts - the image sensor gets sufficient light for proper exposure, while the focus sensor receives dedicated light for reliable focus detection, resolving the contradiction between exposure quality and focus detection capability.
2Manufacturing precision
If the aperture ratio is reduced for better exposure control, then the image quality improves, but the focus sensor receives insufficient light for accurate focus detection
Solution Approach 1:
By segmenting the light path into two separate beams using a half mirror, the patent enables the image sensor to receive light through the aperture for quality imaging while the focus sensor receives a separate beam dedicated to focus detection. This eliminates the trade-off where reducing aperture for image quality would simultaneously starve the focus sensor of light.
Solution Approach 2:
The half mirror acts as an intermediary optical element that divides the incident light into two separate paths. This intermediary device allows the system to simultaneously achieve both good image exposure control through aperture adjustment and reliable focus detection by directing light to the appropriate sensors without interference between the two functions.
3Productivity
If consecutive image capture is performed with aperture adjusted for exposure, then image data can be output continuously, but focus detection fails during the capture process
Solution Approach 1:
The patent segments the light path using a half mirror to send separate beams to the image sensor and focus sensor. This allows continuous image capture at the optimized aperture ratio while the focus sensor continuously receives dedicated light beams for real-time focus detection throughout the consecutive capture process, eliminating the focus detection failure that occurs in conventional systems.
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 allows the focus sensor to detect focus while outputting image data with appropriate exposure, preventing blurring and maintaining image quality even when the shutter button is held halfway down for an extended period.
Implementation Method 1
a half mirror for dividing light, which has originated from the subject and passed through an image capture optical system, into two beams of light
Data Source
AI summary
To provide a digital camera capable of causing a focus sensor to detect a focus while outputting to an image sensor image data for providing appropriate exposure after having adjusted an aperture ratio of an aperture in an image capture optical system such that appropriate exposure is achieved. A digital camera divides light from a subject having passed through an aperture into two beams of light; causes one of the beams to enter the image sensor to thus cause the image sensor to capture a subject image; and causes the other beam to enter the focus sensor to thus cause the focus sensor to detect a focus from the other beam of light. The digital camera adjusts an aperture ratio of the aperture such that the quantity of the other beam reaches the minimum quantity of light at or above which the focus sensor can detect a focus.