Image Sensor Simultaneous Color and Depth Imaging via Phase-Shifted Modulation
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Solution Overview
Problem
Current image sensors are unable to simultaneously capture high-quality color and depth images, which is essential for advanced applications like stereoscopy and 3D imaging.
Innovation Solution
An image sensor design that includes a light source, multiple pixels, and an image processing unit, which emits modulated light and applies gate signals with specific phase differences to generate both color and depth images from pixel signals, utilizing a row decoder and photo-gates on an integrated circuit chip to process the reflected light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a conventional image sensor captures color information, then color image quality is maintained, but depth information cannot be obtained simultaneously
Solution Approach 1:
The image sensor is designed to perform multiple functions simultaneously: capturing both color information (through standard photodetectors) and depth information (through time-of-flight measurement). This multi-functionality allows a single sensor to replace what would traditionally require separate sensors, resolving the contradiction between obtaining complete information and maintaining device simplicity
Solution Approach 2:
The sensor divides the detection function into separate components: photodetectors for color capture and time-of-flight measurement for depth capture. This segmentation allows each component to specialize in its function while working together within the same sensor array, enabling simultaneous color and depth imaging without excessive complexity
2Loss of information
If modulated light and phase detection are used to obtain depth information, then depth imaging capability is achieved, but color image quality deteriorates
Solution Approach 1:
The system uses modulated light that varies periodically in intensity, and the photodetectors sample this modulated signal at different phases. By using periodic modulation and phase-shifted sampling, the system can extract depth information through phase difference measurement while the photodetectors continue to capture color information during different phases of the modulation cycle
Solution Approach 2:
The photodetectors perform preliminary color capture during the modulation cycle, and the time-of-flight measurement is performed concurrently using the same light photons. This preliminary action during different phases of the modulation allows both color and depth information to be extracted from the same light input without interfering with each other's quality
3Measurement precision
If multiple photo-gates are used to detect phase differences, then depth measurement precision improves, but device complexity increases
Solution Approach 1:
Instead of using all four phase gates simultaneously for every pixel, the system applies gate signals sequentially or selectively to different pixel groups. This partial action approach reduces the instantaneous complexity of the photo-gate structure while still achieving the necessary phase difference measurements for accurate depth determination through statistical processing of the collected signals
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
Enables the simultaneous generation of high-quality color and depth images, improving the capability of image sensors to capture detailed color information and depth data, enhancing applications in fields like photography and 3D imaging.
Implementation Method 1
The pixels include at least one pixel for outputting pixel signals according to light reflected by the target object. The at least one pixel may include one photo-gate that responds to the gate signals in a photoelectric conversion area.
Implementation Method 2
The gate signals may include first through fourth gate signals respectively having phase differences of 0, 90, 180, and 270 degrees from the modulated light, which are sequentially applied to the photo-gate to output first through fourth pixel signals. The depth calculator may generate the depth image based on an arc tangent of a ratio of a difference between the second pixel signal and the fourth pixel to a difference between the first pixel signal and the third pixel signal.
Data Source
AI summary
An image sensor includes a light source that emits modulated light such as visible light, white light, or white light-emitting diode (LED) light to a target object, a plurality of pixels, and an image processing unit. The pixels include at least one pixel for outputting pixel signals according to light reflected by the target object. The image processing unit simultaneously generates a color image and a depth image from the pixel signals of the at least one pixel.