Development of High-range-resolution Time-of-Flight range Image Sensors

2018 Fiscal Year Final Research Report

• Project/Area Number: 15H05524
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Electron device/Electronic equipment
• Research Institution: Shizuoka University
• Principal Investigator: Yasutomi Keita 静岡大学, 電子工学研究所, 助教 (50621661)
• Research Collaborator: KAWAHITO shoji
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: Time-of-Flight / ３次元計測 / CMOSイメージセンサ / 距離計測 / 時間分解撮像

Outline of Final Research Achievements

A time-of-flight range CMOS image sensor with sub-100-um range resolution has been developed. By using a lateral electric charge modulation, a three-tap lock-in pixel with photocurrent response of several hundred picoseconds have been developed. To suppress the low-frequency jitter in the light trigger that limits the range resolution, we have developed a novel technique using reference plane sampling (RPS) with a reference pixel array embedded in the same focal plane of the main pixel array. This technique improves the range resolution significantly. To reduce the clock skew of the gating clocks, a column-parallel digital delay-locked loop (DLL) with a dual clock tree is implemented with a short calibration time of approximately 42 us.
The prototype range imager with 192 x 4 effective pixels is implemented in a 0.11-um CMOS image sensor technology. Using the RPS, a range resolution of 64 um has been achieved, corresponding to a 430-fs time resolution with a 25-mm range.

Free Research Field

撮像素子

Academic Significance and Societal Importance of the Research Achievements

従来のTOF距離撮像では、数ミリメートルの距離分解能（時間にして数１０ピコ秒）しか得られておらず、その用途は「認識」用途に限られる。本研究により、100マイクロメートル以下の距離計測が可能であることが実証され、３次元スキャナなどの計測分野にも応用できる可能性が示された。また、イメージセンサ内のジッタを低減することにより、さらなる高距離分解能化も期待でき、TOF距離撮像素子の新たな応用展開が期待できる。また、要素技術として高速なロックイン検出が可能な複数出力の電荷変調素子や、スキューを短時間で補正できる全電子式スキュー補正回路も実証しており、他の時間分解撮像にも有用な技術を確立した。