Distance Image Sensor Pixel Timing for Flare Noise Reduction
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Solution Overview
Problem
Strong reflected light from an object near the measuring device can cause flare, leading to noise in the measurement due to light being incident at a position different from the image position, which affects the accuracy of distance image measurement.
Innovation Solution
A distance image measuring device with a pixel circuit unit and charge transfer control means that outputs control pulses at specific timings to separate charge generation from background light and pulsed light, allowing for correction of flare influence in the detection signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light source generates pulsed light to enable time-of-flight distance measurement, then distance measurement capability is improved, but flare noise occurs due to strong reflected light being incident at positions different from the image position
Solution Approach 1:
The pixel circuit unit is divided into multiple charge reading regions (first to M-th regions) with different integration time periods. By segmenting the charge accumulation process into multiple time windows, the device can selectively integrate signals from different time periods, allowing separation of the desired reflected light signal from the flare noise that occurs at different times
Solution Approach 2:
The light source generates pulsed light periodically, and the pixel circuit unit performs periodic charge integration across multiple time windows. This periodic action enables time-of-flight measurement by comparing signals from different time periods, while the ability to select specific integration windows allows rejection of flare noise that occurs at non-desired time points
2Measurement precision
If multiple charge reading regions with different integration time periods are used to reduce background light influence, then distance measurement accuracy is improved, but device complexity increases
Solution Approach 1:
Multiple charge reading regions are integrated within a single pixel circuit unit, combining multiple functions (background light measurement, signal integration, charge transfer) into one compact structure. This merging approach reduces the overall device complexity compared to using separate circuits for each 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
The device reduces the impact of flare noise, enabling high-resolution and accurate distance calculation by using multiple time windows with reduced background light influence, improving dynamic range and accuracy of distance measurement.
Implementation Method 1
a photoelectric conversion region for converting light into charge
Data Source
AI summary
A distance image sensor including a light source that generates pulsed light, a light source control means that controls the light source, a pixel circuit including a photoelectric conversion region, charge reading regions, a charge discharging region, and control electrodes, a charge transfer control means that outputs control pulses to the control electrodes, and a distance calculation means that reads voltages of the charge reading regions as detection signals and repeatedly calculates a distance on the basis of the detection signals. The charge transfer control means sets a timing at which the control pulse is output to be before a timing at which the pulsed light is generated.