Electronic Surveying Instrument Projection Light Synchronization

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Solution Overview

Problem

Electronic surveying instruments experience imaging errors due to oversaturation and stray light from projected visible light, which affects the accuracy of images displayed to the human eye.

Innovation Solution

Synchronizing the projection light emission with the image acquisition process to reduce the received power during image acquisition phases, using techniques such as periodic pulsing or modulation of the projection light, and employing a controller unit to manage the synchronization between the projection light source and the image sensor, ensuring that the image sensor is not oversaturated by the projection light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If projection light is emitted continuously for visualization and measurement, then the visibility and measurement capability are improved, but imaging errors occur due to oversaturation and stray light in the image sensor

Engineering Contradiction:
Improveprojection light visibilityVSAvoidimage acquisition accuracy
Core Design Contradiction:
Illumination intensityVSMeasurement precision

Solution Approach 1:

The projection light is emitted periodically in synchronization with the image sensor's frame rate, creating pulsed illumination that appears continuous to the human eye but prevents oversaturation during image acquisition. The controller unit modulates the projection light source to emit light only during specific time windows within each frame cycle.

Inventive Principle:
Principle #19Periodic action

2Productivity

If the image sensor operates at high frame rate for continuous image display, then the image continuity and display quality are improved, but the received power from projection light causes saturation during acquisition phases

Engineering Contradiction:
Improveimage acquisition rateVSAvoidimage sensor saturation
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The image sensor operates in periodic cycles of image acquisition and pause, with the projection light synchronized to these cycles. During acquisition phases, the projection light is suppressed or reduced, while during pause phases, the light is emitted. This periodic coordination allows high frame rates without saturation.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The controller unit pre-coordinates the projection light emission timing with the image sensor's acquisition schedule. Before each image acquisition phase begins, the projection light is turned off or dimmed in advance, preventing saturation before it occurs.

Inventive Principle:
Principle #10Preliminary action

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 minimizes imaging errors by reducing artifacts caused by projection light, allowing for more accurate and artifact-free image acquisition, which enhances the precision of spatial measurements and projections in electronic surveying instruments.

Implementation Method 1

an optical receiving light path from the object to an image sensor with a frame rate

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

a projection light emitting unit, in particular a laser, with an optical emitting light path from the projection light emitting unit to an object

Methodology Applied
Scientific EffectLight: Light

Data Source

PatentEP3988897B1Electronic surveying instrument
Publication Date: 2023.09.27 LEICA GEOSYSTEMS AG
  • EP3988897B1 patent drawingFigure 1~2
  • EP3988897B1 patent drawingFigure 3~4
  • EP3988897B1 patent drawingFigure 5~8

AI summary

The invention relates to an electronic surveying instrument and to a method for synchronizing the emitting of projection light (8,8a) by the electronic surveying instrument and the acquiring of images by an image sensor (6) of the electronic surveying instrument to reduce the visibility of the projection light (9,9a) in at least a part of the images acquired by the image sensor (6).