TOF Distance Sensor Pixel Group Exposure Control
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Solution Overview
Problem
Conventional distance measuring devices using time of flight techniques face accuracy issues due to varying exposure conditions and the influence of ambient light, leading to unstable measurement accuracy and a limited distance measurable range.
Innovation Solution
A distance measuring device with a light emitter and a solid-state image sensor that independently exposes pixels in a matrix, using a light emission and exposure controller to manage exposure timing and periods, allowing for accurate distance measurement by calculating pixel signals from adjacent pixels at different exposure times, thereby reducing the impact of ambient light and expanding the measurable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional TOF techniques use a single exposure condition per frame, then the device structure remains simple, but the measurement accuracy decreases when object distance changes
Solution Approach 1:
The pixel array is divided into multiple pixel groups, where each pixel group can be exposed independently with different exposure conditions. This segmentation allows the system to capture reflected light from objects at different distances simultaneously, resolving the contradiction between maintaining simple device structure and achieving accurate distance measurement across varying distances.
Solution Approach 2:
The exposure timing for each pixel group is made dynamically adjustable rather than fixed. By independently controlling the exposure timing of each pixel group, the system can adapt to objects at different distances within the same frame, improving measurement accuracy without significantly increasing overall device complexity.
2Measurement precision
If conventional devices combine distance images with different exposures, then the measurable distance range expands, but measurement accuracy becomes unstable due to ambient light variation
Solution Approach 1:
The system uses periodic pulsed light emission with synchronized periodic exposure of pixel groups. By coordinating the light emission timing with the exposure timing of different pixel groups, the system captures reflected light at different time points within the same frame, enabling stable distance measurement across a wide range while minimizing ambient light interference through temporal gating.
3Adaptability or versatility
If conventional devices use fixed exposure timing, then the device operation is simple, but the distance measurement range is limited
Solution Approach 1:
The pixel array is divided into multiple pixel groups with independently controllable exposure timing. This segmentation enables the system to measure distances to objects at various ranges simultaneously by assigning different exposure timings to different pixel groups, expanding the measurable distance range while maintaining relatively simple operational control through standardized exposure sequences.
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 device achieves stable and accurate distance measurement across a wider range, unaffected by changes in object distance and ambient light, without the need for frame memory, resulting in a compact and cost-effective solution.
Implementation Method 1
a solid-state image sensor that includes a plurality of pixels included in a plurality of pixel groups capable of being exposed independently, and causes the plurality of pixels to perform photoelectric conversion of reflected light from the object
Data Source
AI summary
In a distance measuring device that measures a distance to an object using a round-trip time of light, a solid-state image sensor includes a plurality of pixel groups capable of being exposed independently, and causes each of the plurality of pixel groups to receive, at a different exposure time, reflected light from the object that is originally pulsed radiation light from a light emitter. A light emission and exposure controller cyclically and intermittently exposes each of the plurality of pixel groups of the solid-state image sensor at the different exposure time to obtain pixel signals of types corresponding to a time difference between the reflected light and the radiation light, and a signal processor obtains information about the distance to the object according to pixel signals of adjacent pixels exposed at different exposure times for each of the plurality of pixel groups.