|The OV6930 CMOS image sensor enhances image quality in endoscopy, bronchoscopy, gastroscopy, and other applications.|
For nearly two decades, charge-coupled devices (CCDs) were the technology of choice for capturing images in such devices as endoscopes. Prized for their image quality, they continued to dominate over image sensors based on CMOS technology until the mid- to late-1990s. But then, CMOS sensors began to take off in medical imaging applications. Furthering this trend, OmniVision has introduced a CMOS-based image sensor that it claims offers enhanced image quality, low power consumption, improved system integration capability, and a small size.
Featuring a package footprint of 1.8 × 1.8 mm, the OV6930 image sensor is based on OmniVision's OmniPixel3-HS technology, the latest iteration of the company's front-side illumination pixel architectures, according to James Lei, director of marketing for medical solutions. "This architecture is the result of systematically analyzing the performance of many pixel designs over many process variations. As a result of our analyses, we arrived at a proprietary image technology that doubles the sensitivity of the previous-generation OmniPixel3 architecture to 3300 mV/lux-sec." The new technology enhances image capture under low-light conditions, Lei adds, enabling a new generation of compact camera solutions for medical applications that require low-light performance without the need for a flash.
In addition to its compact footprint and high sensitivity, the chip provides either full-frame or cropped analog images in raw RGB format via serial camera control bus interface control. It also has a 0.1-in. optical format and features an image array capable of operating at up to 30 frames per second in 400 × 400 resolution or 60 frames per second in 400 × 200 resolution.
"In the last couple of years, CMOS-based image sensors have become accepted in a range of imaging applications," Lei remarks. "This, in turn, has encouraged the development of a complementary ecosystem that supports CMOS sensors--including the lens, image-signal processor, and display elements. These developments have allowed for the adoption of CMOS image sensors in a wide range of medical endoscopy applications."
The adoption of CMOS imaging technology is due largely to its inherent benefits, including higher integration and a lower overall system bill of materials compared with CCD-based cameras or fiber-optic bundles, according to Lei. And the potential of the CMOS production process to combine functions in various ways can lead to advantages in terms of space, cost, and design options. "Thus, CMOS technology is finding wider use in medical imaging applications," Lei adds.
CMOS image sensors for medical applications could develop in several directions, Lei comments. They could replace other image-capture systems, and they could lead to the emergence of new endoscope tips and tubes, culminating in a new generation of disposable instruments. "The sensor has already been used in bronchoscopy, gastroscopy, OB/GYN, and urology applications," Lei says.
Santa Clara, CA