Effects of Offset Pixel Aperture Width on the Performances of Monochrome CMOS Image Sensors for Depth Extraction.

Lee Lee,Park Park,Lee Lee,Shin Shin,Kim Kim,Choi Choi,Chang Chang

doi:10.3390/s19081823

Abstract

This paper presents the effects of offset pixel aperture width on the performance of monochrome (MONO) CMOS image sensors (CISs) for a three-dimensional image sensor. Using a technique to integrate the offset pixel aperture (OPA) inside each pixel, the depth information can be acquired using a disparity from OPA patterns. The OPA is classified into two pattern types: Left-offset pixel aperture (LOPA) and right-offset pixel aperture (ROPA). These OPAs are divided into odd and even rows and integrated in a pixel array. To analyze the correlation between the OPA width and the sensor characteristics, experiments were conducted by configuring the test elements group (TEG) regions. The OPA width of the TEG region for the measurement varied in the range of 0.3–0.5 μm. As the aperture width decreased, the disparity of the image increased, while the sensitivity decreased. It is possible to acquire depth information by the disparity obtained from the proposed MONO CIS using the OPA technique without an external light source. Therefore, the proposed MONO CIS with OPA could easily be applied to miniaturized devices. The proposed MONO CIS was designed and manufactured using the 0.11 μm CIS process.

Highlights

An image is an important method by which visual information is shared in modern society.it is difficult to obtain stereoscopic information using images reproduced by general image sensors
Since the pixel of the proposed MONO CMOS image sensors (CISs) with offset pixel aperture (OPA) was based on the front side illumination (FSI) method, a pinned photodiode (PPD) structure is applied to reduce the defects generated on the surface of the photodiode (PD)
Because the two types of OPA were designed to yield a constant offset in the symmetric direction, the difference in the disparity changed according to the distance between the object and the sensor

Summary

Introduction

An image is an important method by which visual information is shared in modern society. The light field technique contains microlens arrays that are integrated at a small distance from the image sensor [15,16,17,18,19]. Because the light field image sensor contains as many sets of disparity information as the number of microlenses, a stereoscopic image can be reproduced. CMOS image sensors (CISs) are integrated, has been performed with advancements in technology This is due to advantages such as their small required area, easy portability, and low power consumption. Some of the disadvantages of the above 3D imaging system technology include the need for an infrared source that has high power consumption, the use of a plurality of cameras, and the sensor’s limited resolution depending on the number of microlenses.

Pixel Structure

MONO CIS with OPA Technique

Measurement of the Disparity Depending on the Distance

Conclusions