Light Source Driving Device Delay Correction
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Solution Overview
Problem
Existing light source driving devices for distance measuring devices face challenges in reducing errors due to variations in delay time of light emission from the light emitting element.
Innovation Solution
A light source driving device that includes a light emission drive unit, a drive signal generation unit, a phase difference detection unit, and a delay detection unit, which detects the phase difference between the light emission period and the light emission control signal to correct for delays in light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light emitting element is driven using conventional driving devices with target current and bias current, then the emission intensity can be controlled, but variations in delay time of light emission occur causing distance measurement errors
Solution Approach 1:
The patent implements feedback by detecting the actual light emission timing using a photodetector and comparing it with the drive signal timing. The detected delay time is fed back to correct the distance measurement calculation, ensuring that variations in delay time do not compromise measurement precision.
Solution Approach 2:
The patent replaces direct electrical timing measurement with optical detection. Instead of measuring delay time directly through electrical signals, a photodetector detects the actual light emission timing by receiving the light from the light emitting element, converting the timing measurement into an optical domain for more accurate detection.
2Ease of operation
If the drive signal is generated and processed through multiple units (drive signal generation unit, light emission drive unit), then the light emission can be controlled, but delay time variations are introduced
Solution Approach 1:
The patent performs preliminary measurement of the delay time between the drive signal generation and actual light emission. This delay characteristic is detected in advance and stored, then used to correct subsequent distance measurements, compensating for the time loss introduced by the multiple processing units.
Solution Approach 2:
The patent introduces a photodetector as an intermediary to detect the actual light emission timing. This intermediary component bridges the gap between the electrical drive signal and the optical output, enabling accurate measurement of the delay time introduced by the signal processing chain.
3Measurement precision
If phase difference detection is implemented to detect delay time, then distance measurement errors can be reduced, but device complexity increases
Solution Approach 1:
The light emitting element itself serves as the light source for detection. The same light that is being controlled for distance measurement is used by the photodetector to detect the emission timing, eliminating the need for separate calibration light sources or additional complex detection mechanisms.
Solution Approach 2:
The patent merges the light emission function and light detection function into a unified system. The photodetector detects the light emitted by the light emitting element, combining the transmission and detection paths. This integration reduces device complexity compared to using separate calibration systems.
Data Source
AI summary
An error based on a delay time that occurs when driving a light emitting element is reduced.A light source driving device includes a light emission drive unit, a drive signal generation unit, a phase difference detection unit, and a delay detection unit. The light emission drive unit supplies a light emission current for causing a light source to emit light. The drive signal generation unit generates a drive signal for driving the light emission drive unit on the basis of a light emission control signal for causing the light source to emit light. The phase difference detection unit detects the phase difference between a light emission period of the light source and the light emission control signal. The delay detection unit detects a delay in the light emission on the basis of the detected phase difference.