Time-of-Flight Object Detection Against Dust-Induced Invalid Pixels
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Solution Overview
Problem
Dust in the vicinity of the imaging direction causes lens flare, leading to the generation of invalid pixels with incorrect or uncalculable distance values in object detection devices.
Innovation Solution
An object detection device and method that utilize a light emitter and sensor to generate pixel signals through controlled exposures, setting the first exposure timing to avoid dust reflection and adjusting the time difference between exposures to inhibit invalid pixel generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor performs exposure to reflected light from objects at all distances, then complete distance measurement coverage is achieved, but invalid pixels are generated due to lens flare from dust in the vicinity
Solution Approach 1:
The patent divides the measurement space into two sections: a first section (near field, 0 to predetermined distance) and a second section (far field, beyond predetermined distance). Different exposure strategies are applied to each section - the first exposure avoids the near field to prevent dust-related lens flare, while the second exposure captures the far field. This segmentation allows the system to measure distances accurately without generating invalid pixels from dust interference.
2Measurement precision
If the first exposure timing is set to capture reflected light from near objects, then near object detection is improved, but lens flare from dust causes invalid pixels
Solution Approach 1:
The patent performs a preliminary assessment of the measurement environment by analyzing reflected light characteristics. Based on this preliminary information, the system determines whether dust is present in the near field. When dust is detected, the system adjusts the first exposure timing to avoid capturing reflected light from the contaminated near field region, thereby preventing invalid pixel generation while maintaining measurement reliability.
3Device complexity
If a single exposure strategy is used for all distance ranges, then device complexity is reduced, but measurement accuracy deteriorates in dust conditions
Solution Approach 1:
The patent implements dynamic exposure control that adapts to environmental conditions. The exposure timing and parameters are adjusted based on the detected presence of dust and the distance to objects. The system dynamically selects between different exposure strategies: using only the second exposure when dust is present in the near field, or combining both exposures when conditions are clear. This dynamic adaptation maintains measurement accuracy without requiring complex hardware modifications.
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
Inhibits the creation of invalid pixels due to dust, enhancing the accuracy of object detection by preventing lens flare effects.
Implementation Method 1
a lens flare occurs due to strong reflected light from the dust
Implementation Method 2
a light emitter that emits light; a sensor that generates a first pixel signal by exposure to reflected light
Implementation Method 3
generating a distance image by ratio operation using the first pixel signal and the second pixel signal, wherein timing of the first exposure is set to timing during which the sensor is not exposed to reflected waves from an object included in a first section in which a distance from the object detection device is from 0 to a predetermined value
Data Source
AI summary
An object detection device includes: a light emitter that emits light; a sensor that generates a first pixel signal by exposure to reflected light according to a combination of emission by the light emitter and first exposure and a second pixel signal by exposure to reflected light according to a combination of the emission and second exposure; and a distance calculator that generates a distance image by ratio operation using the first pixel signal and the second pixel signal. Timing of the first exposure is set to timing during which the sensor is not exposed to reflected waves from an object included in a first section in which a distance from the object detection device is from 0 to a predetermined value. A time difference between the emission and the second exposure is greater than a time difference between the emission and the first exposure.