G-Link licenses logarithmic pixel-imaging-sensor technology
G-Link Technology (Santa Clara, CA), a chip maker for computer, consumer, and communications markets, has signed an exclusive license agreement and entered into a five- to seven-year research-and-development partnership with the Institute for Microelectronics Stuttgart (IMS) Chips, an imaging-technology research foundation in Germany, for its patented high-dynamic-range CMOS (HDRC) image-sensor technology. G-Link is leveraging its expertise in memory-chip technology with IMS Chips` electronic-vision technology to produce next-generation, logarithmic-pixel-compression CMOS image sensors at higher resolution and at lower power and cost than linear-pixel-response CCD and CMOS image sensors. These new sensors are expected to be designed into consumer digital video cameras, digital cameras, and videophones, as well as into industrial digital cameras for machine-vision, security, traffic, robotics, and automotive applications.
Says Max Blankenzee, C-Link`s vice president of imaging products, "We believe that we have an approach that differs from all the current CCD and CMOS image-sensor makers. Basically, they are working with inherent limitations due to linear-pixel response. Typically, those limitations include a restricted dynamic range, varying exposure control that results in oscillating brightness, and the fundamental failure to acquire all the information contents in the image and to achieve color constancy and fidelity because of varying saturations of light. For machine-vision applications, therefore, we provide a maximum amount of information with our sensors for digital imaging as to dynamic range, speed, contrast resolution, and color fidelity."
The analog HDRC-based sensors are specified with a dynamic range of 120 dB, or six decades of light intensity, a constant shutter time of <120 ns/pixel, a constant pixel rate of 8 to 16 Mpixels/s, and a color constancy of more than two decades of luminance. These characteristics eliminate the need for aperture or shutter control, color correction, or buffer memories, thereby simplifying system design and lowering hardware and software costs.
Current linear-sensor technologies possess several imaging limitations. They provide an inherent limited linear-pixel-response range of 1000:1, which often causes white or dark saturation and color distortion under varying light or exposure conditions. These conditions generally wipe out parts of, or even whole, images. Further, attaining a constant high-speed pixel rate becomes complicated because of varying shutter (integration) times, costly buffer memories, and restricted digital compression.
In contrast, HDRC technology offers a pixel response of 1,000,000:1 using logarithmic CMOS photo receptors that imitate the response of human eyes. These capabilities eliminate exposure errors and provide maximum exposure content that exceeds an eye`s real-time capacity. In addition, random access to every pixel is possible. Adds Blankenzee, "The sensors are built using standard CMOS 0.35-µm fab processing and can be classified as 0.5-in. photosensors. High-speed black-and-white HDRC image sensors with 512 ¥ 256-pixel resolution are available now. Color HDRC image sensors are expected to be ready in May with VGA [640 ¥ 480-pixel] resolution."
Says Ralph Waggitt, senior vice president, sales and marketing, "The 1997 sales of G-Link`s internally developed memory products were $33.5 million and were equally split between Asian and US markets. Our 1998 sales are targeted at $85 million, and that goal includes only a small impact for the HDRC sensors, as developers need about a 90-day design cycle to incorporate the new sensors. The sensors are expected to sell in large volumes in 1999 and will also be put into single-package embedded solutions."