Range-Gated Image Capture With Dual Exposure Timing
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Solution Overview
Problem
Existing range-gated cameras face challenges in capturing clear images of objects at varying distances and in low-light conditions, leading to potential delays in latency-critical applications like collision avoidance and reduced visibility in dark areas.
Innovation Solution
An image capturing apparatus that simultaneously captures a clear image of an object at a predetermined distance and an image with high visibility in dark areas by using a photoelectric conversion element with stacked substrates, color filters, and synchronized exposure and emission control, allowing for both RGB and range-gated IR imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If range-gating control is used to capture clear images of objects at predetermined distances, then measurement precision is improved, but productivity deteriorates due to the need for multiple frames and longer time periods
Solution Approach 1:
The image sensor is divided into two distinct regions: a first region with photoelectric conversion units that capture reflected light for range-gated imaging, and a second region with photoelectric conversion units that capture ambient light for general imaging. This segmentation allows both range-gated and non-range-gated images to be captured simultaneously within a single frame period, eliminating the need for multiple frames and resolving the contradiction between measurement precision and productivity
Solution Approach 2:
The patent introduces a spatial dimension by stacking two substrates with different functional regions. The first substrate captures images with range-gating control for precise distance measurement, while the second substrate captures images without range-gating for broader scene coverage. This dimensional approach enables simultaneous operation of both imaging modes, improving productivity without sacrificing measurement precision
2Measurement precision
If exposure time is limited to correspond to target distance in range-gating control, then measurement precision is improved, but illumination intensity deteriorates in dark areas
Solution Approach 1:
The image sensor is segmented into two functional regions: the first region performs exposure only during the range-gating period to ensure precise target distance measurement, while the second region performs exposure continuously or for extended periods to accumulate sufficient light for bright images in dark areas. This segmentation resolves the contradiction by allowing different exposure strategies in different spatial zones
Solution Approach 2:
Different exposure characteristics are applied to different regions of the image sensor. The first region uses short, precise exposure timing synchronized with light emission for accurate range-gated imaging, while the second region uses longer exposure times to maximize light accumulation for visible imaging in low-light conditions. This local quality approach ensures each region optimizes its performance for its specific function
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
Enables clear imaging of objects at varying distances and in adverse weather conditions, improving visibility in dark areas without the need for multiple frames, enhancing safety in applications like collision avoidance.
Implementation Method 1
an image sensor including a plurality of photoelectric conversion units arranged in a two-dimensional pattern
Data Source
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AI summary
An image capturing apparatus includes at least one processor or circuit configured to function as color filters (30, 40), a light-emitting unit (501, 901) configured to emit light a plurality of times within one frame period, a sensor unit (102) configured to emit pulses according to a reception frequency of photons, a plurality of pixel units each including a counter (211) that counts the pulses and a memory (212) that stores a count value, and a count-enable generation unit (104) configured to generate a count enable signal. The count-enable generation unit (104) generates a first count enable signal that is asynchronous with an emission timing of the light-emitting unit (501, 901) and that includes a single enable period within one frame period, and/or a second count enable signal that is synchronous with the emission timing and that includes a plurality of enable periods within one frame period.