LiDAR Mirror Scan Timing Synchronization Without Range Error

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Solution Overview

Problem

Existing optical distance measuring devices face issues with timing adjustments affecting distance measurement accuracy, particularly when synchronizing with other vehicles' LiDAR devices, leading to inaccurate distance calculations.

Innovation Solution

The optical distance measuring device adjusts the backward movement time of the mirror without altering the forward movement time, synchronizing the scanner operation with timing signals to maintain accurate distance measurements by adjusting the backward movement period based on threshold values and using internal or external control units to calculate and implement timing adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If timing adjustment is performed to synchronize with other vehicles' LiDAR devices, then coordination between devices is improved, but distance measurement accuracy deteriorates

Engineering Contradiction:
Improvecoordination between devicesVSAvoiddistance measurement accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the mirror scanning cycle into two distinct parts: forward movement period (for distance measurement) and backward movement period (for timing adjustment). By separating these functions temporally, the system can adjust overall timing without affecting the forward movement measurement window, thus resolving the contradiction between coordination and measurement accuracy

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent dynamically adjusts only the backward movement time of the mirror based on timing deviation from external timing signals, while keeping the forward movement time constant. This dynamic adjustment strategy allows the system to adapt to synchronization requirements while preserving the stability needed for accurate distance measurement

Inventive Principle:
Principle #15Dynamics

2Reliability

If the scanner operation is synchronized with timing signals by adjusting the time of one cycle, then synchronization is improved, but the distance measuring period may be affected

Engineering Contradiction:
ImprovesynchronizationVSAvoiddistance measuring period
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent divides the scanner cycle into forward movement (measurement) and backward movement (adjustment) segments. Timing synchronization is achieved by adjusting only the backward movement duration, leaving the forward movement measurement segment unchanged, thus maintaining both synchronization and measurement precision

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies timing adjustment locally to only the backward movement portion of the scanner cycle, while maintaining the forward movement portion's timing characteristics unchanged. This localized adjustment ensures synchronization without compromising the quality of distance measurement

Inventive Principle:
Principle #3Local quality

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

This approach ensures that timing adjustments do not impact distance measurement accuracy, allowing for precise calculation of distances to targets by synchronizing scanner operations effectively.

Implementation Method 1

a light emitting part; a mirror configured to reflect an irradiation light emitted by the light emitting part... a light receiving part configured to detect a reflected light returned by reflecting the irradiation light from a target

Methodology Applied
Scientific EffectLight emission and detection: Light

Implementation Method 2

a mirror configured to reflect an irradiation light emitted by the light emitting part... detect a reflected light returned by reflecting the irradiation light from a target

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP4249945B1Optical distance measuring device
Publication Date: 2026.04.08 DENSO CORP
  • EP4249945B1 patent drawingFigure 1
  • EP4249945B1 patent drawingFigure 2
  • EP4249945B1 patent drawingFigure 3

AI summary

An optical distance measuring device (10, 11) includes a light emitting part (21), a mirror (26) that reflects the illumination light (IL) emitted by the light emitting part, a scanner (28) that scans a predetermined scanning range with the irradiation light by operating the mirror in a forward movement motion and a backward movement motion, a light receiving part (30) that detects a reflected light returned by reflecting the irradiation light from a target existing in the scanning range, a distance calculating part (40) that calculates a distance to the target using a time from an emission of an irradiation light by the light emitting part to the detection of the reflected light from the target by the light receiving part during the forward movement motion of the mirror, a timing signal generating part (60) that generates the timing signal according to a signal from an outside of the optical distance measuring device, and a control unit (50, 51) that controls a light emission of the light emitting part and an operation of the scanner. The control unit (50) synchronizes the operation of the scanner with a predetermined timing signal by adjusting a time of one cycle of the scanner while maintaining the distance measuring period of the forward movement motion of the mirror.