Projector Camera Timing Synchronization for Gesture Detection

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Solution Overview

Problem

Digital cameras equipped with pico-projectors face interference patterns like Moire patterns when recording gestures illuminated by projected images, which hinder accurate gesture detection.

Innovation Solution

Synchronizing the timing between the projector and the digital camera by generating a control signal to align the projector's refresh rate with the camera's exposure time, reducing or eliminating interference patterns such as Moire patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the pico-projector projects images while the digital camera records simultaneously without synchronization, then the system can function as both projector and camera, but Moire patterns and interference occur that prevent accurate gesture detection

Engineering Contradiction:

Improvedual function as projector and cameraVSAvoidgesture detection accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies periodic action by synchronizing the projector's refresh rate with the camera's frame rate using timing signals. The projector operates at a refresh rate that is a integer multiple of the camera's frame rate, creating periodic synchronization intervals that eliminate Moire patterns while maintaining dual functionality. This periodic coordination allows both projection and recording to occur without interference.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If additional hardware filters are added to eliminate Moire patterns, then gesture detection accuracy improves, but device complexity and cost increase

Engineering Contradiction:

Improvegesture detection accuracyVSAvoidhardware filter complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical/optical hardware filters with an electronic/software-based synchronization solution. By using timing signals to coordinate the projector and camera operations, the system eliminates Moire patterns through temporal coordination rather than spatial filtering. This substitution reduces device complexity while maintaining gesture detection accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2461592B1A timing solution for projector camera devices and systems

Publication Date: 2019.12.25 SONY ERICSSON MOBILE COMMUNICATIONS AB

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AI summary

An imaging system includes an integrated projector (50) that projects images on to an external display (20) surface and a digital camera (30) that records gestures and/or other objects that are in or illuminated by the projected images. The camera (30) and/or the projector (50) generate a timing signal to synchronize a refresh rate of the projector (50) with an exposure time of the digital camera (30). The synchronization reduces or eliminates interference patterns that may be caused by gestures in or illuminated by the projected image, and allows the digital camera (30) to more accurately detect the gestures.