Modulated Backlight Depth Sensing for Compact Projectors
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Solution Overview
Problem
Existing depth camera technologies face challenges in adapting to portable or small form factor devices due to power and space limitations, making it difficult to achieve compact size and reduced power consumption while maintaining effective depth sensing capabilities.
Innovation Solution
A video projector device is designed with a modulated backlight that creates light pulses detectable by a visible light camera, transforming the light pulses into depth data using a time-of-flight principle, allowing for compact size and reduced power consumption without affecting image quality, and can be integrated into various mobile or non-mobile devices for diverse applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a depth camera is adapted for portable or small form factor devices, then the device size is reduced, but power consumption and space limitations increase
Solution Approach 1:
The patent integrates the backlight assembly of the display device to perform dual functions: serving as the light source for display illumination and simultaneously functioning as the illuminator for depth sensing operations. This eliminates the need for a separate infrared illuminator, reducing both power consumption and device volume while maintaining depth camera functionality in portable devices
Solution Approach 2:
The patent combines the display backlight system with the depth sensing illumination system by modulating the backlight assembly to emit light pulses for depth measurement. This merging of functions allows the same hardware component (backlight assembly) to serve both display and depth sensing purposes, thereby reducing overall device complexity, power consumption, and space requirements
2Reliability
If a separate infrared illuminator is added to the depth camera, then depth sensing capability is improved, but device complexity and power consumption increase
Solution Approach 1:
The backlight assembly is designed to serve dual purposes: providing illumination for the display screen and generating modulated light pulses for depth sensing. This eliminates the need for a separate infrared illuminator, reducing device complexity while maintaining reliable depth sensing capability through the same hardware component
Solution Approach 2:
The display backlight assembly serves itself by being modulated to provide depth sensing illumination without requiring an external or separate illuminator. The same backlight that illuminates the display for normal operation is repurposed to emit modulated light pulses for time-of-flight depth measurement, thereby reducing system complexity
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 solution enables the creation of a compact, low-power video projector device capable of generating depth data for 3D sensing, enhancing its functionality beyond traditional projection, allowing for natural user interfaces and various applications such as gesture recognition and 3D data detection without compromising image quality or increasing power consumption.
Implementation Method 1
transforming the light pulses into depth data using a time-of-flight principle
Implementation Method 2
sense visible light which is reflected from at least one object in the field of view
Implementation Method 3
one or more sensors such as charge-coupled devices (CCDs) are provided which sense visible light
Data Source
Figure 1~2
Figure 3
Figure 4A~4C
AI summary
A video projector device includes a visible light projector to project an image on a surface or object, and a visible light sensor, which can be used to obtain depth data regarding the object using a time-of-flight principle. The sensor can be a charge-coupled device which obtains color images as well as obtaining depth data. The projected light can be provided in successive frames. A frame can include a gated sub-frame of pulsed light followed by continuous light, while the sensor is gated, to obtain time of flight data, an ungated sub-frame of pulsed light followed by continuous light, while the sensor is ungated, to obtain reflectivity data and a background sub-frame of no light followed by continuous light, while the sensor is gated, to determine a level of background light. A color sub-frame projects continuous light, while the sensor is active.