DpiX expands business strategy with rollout of flat-panel monitors

DpiX expands business strategy with rollout of flat-panel monitors

Expression 100 displays could be used in PACS networks

Digital x-ray detector firm dpiX served notice this month that it does not intend to limit its flat-panel technology to image acquisition applications. The Palo Alto, CA, firm on Nov. 3 unveiled Expression 100, a new line of active-matrix liquid crystal displays (AMLCDs) that the company is targeting at high-end applications such as medical imaging.

Expression 100 uses the same core technology that forms the basis for dpiX's FlashScan 20 flat-panel detectors, which the company is providing to medical imaging vendors on an OEM basis for inclusion in completed digital x-ray systems. Such systems are expected to make it easier for hospitals to incorporate x-ray studies into PACS networks.

DpiX's technology can also be used for flat-panel display applications, however. At the most basic level, dpiX's panels consist of a glass substrate, on which is deposited a layer of amorphous silicon that acts as a thin-film transistor. To build an x-ray detector, the plate receives photodiodes and a phosphor-based x-ray conversion layer that converts x-rays into light. The photodiodes then convert the light into digital data. For an image display panel, the photodiodes are replaced by a large capacitor that controls the twisting of a liquid crystal material, which modulates the illumination used to create an image. Each AMLCD array also includes a backlight and filters to display images.

The market for AMLCDs is valued at some $7 billion annually, with the laptop computer market generating most sales. The AMLCD industry is also dominated by Japanese companies, which concerns the U.S. computer industry and government officials in Washington, DC. In fact, the paucity of U.S.-based AMLCD manufacturers was a contributing factor in the formation of dpiX.

DpiX is the outgrowth of a cooperative relationship between dpiX's parent, Xerox Palo Alto Research Center (PARC), and the Department of Defense's Defense Advanced Research Projects Agency (DARPA), according to Carl Cobb, general manager of display products at dpiX. To avoid reliance on foreign suppliers, the Department of Defense is interested in creating a U.S. source for AMLCDs, which are often used for military applications such as high-resolution displays in fighter jets. DARPA has provided $75 million to help dpiX build a manufacturing capacity, an amount that Xerox has matched and exceeded. Perhaps due to the DARPA influence, dpiX has targeted high-end applications for its first AMLCD products, rather than the laptop market. Military avionics and medical imaging are the first target markets.

Large size and high-definition image quality are among the distinguishing features of the Expression 100 display unveiled this month. The 19-inch color display is far larger than AMLCDs used in laptops, providing the equivalent of two pages of viewing area, and is the largest AMLCD manufactured in North America, according to the company. The monitors have fully digital electronics subsystems, with no analog-to-digital conversion, and have uniform linearity from center to corner, meaning that images do not lose their sharpness toward the edges of the monitor, as occurs with CRT-based displays.

In addition, Expression 100 displays are immune to magnetic distortion, which enables them to be sited near MRI scanners without requiring the shielding used on CRT monitors. The resolution of the monitors is 1280 x 1024 in color, with a color-bit depth of 24 bits in 16.7 million colors and a brightness of 45 foot lamberts. The monitors also support full-motion video at 30 fps.

DpiX has begun shipping Expression 100 samples to OEM clients, and plans to begin full production in the first quarter of 1998. The monitors will carry a list price of $10,000, although the company has said it is willing to negotiate with OEM customers buying large quantities.

Gray-scale monitors

DpiX does not yet have a gray-scale version of Expression 100, and that may limit the penetration of the displays into the PACS market. Nearly all soft-copy diagnosis is done on black-and-white displays, with color used only for selected medical imaging applications. DpiX is also investigating the development of a gray-scale offering, which would put the company into the mainstream of the PACS display market. At its debut in early 1996, dpiX displayed a prototype 7-million pixel gray-scale display, although that product has been limited to vision research applications due to its $35,000 price tag.

"We're not ready to announce (gray scale) yet, but it's something we're very interested in," Cobb said. "It's definitely a priority."

Until then, dpiX will sell Expression 100 into medical imaging markets where color is used often. Such markets could include ultrasound, where a smaller version of Expression 100 could be useful on a color Doppler scanner. The displays might also be appropriate on postprocessing workstations, such as 3-D or presurgical planning computers, that use color to highlight different regions-of-interest. At least one OEM customer, which dpiX is unwilling to identify at present, will show Expression 100 incorporated into its products at the upcoming Radiological Society of North America meeting, Cobb said.

Developing products for both image acquisition and display applications has been part of dpiX's business strategy since the company was spun off from Xerox PARC in March 1996. By targeting two markets at once, dpiX has been able to increase volume at its flat-panel fabrication plant, which eventually will help the company reduce the cost of its products, according to Chi Huang, manager of corporate marketing for the company. Some of dpiX's competitors that are developing x-ray digital detectors don't have this advantage.

"They have to amortize the fixed costs in their fabrication facility into the products they are developing in order to be profitable," Huang said. "By running more volume through (our fab), we are able to distribute our fixed costs over more units than they can."

There are also possible synergies between the AMLCD business and the FlashScan 20 digital detector operations. Within x-ray, it's possible that the same image acquired with a FlashScan 20 detector could be displayed on a gray-scale version of Expression 100, with each pixel on the display corresponding to the same pixel location on the sensor, Huang said. This could help clinicians localize small structures such as microcalcifications.

In the long run, it's possible that the market for dpiX's AMLCDs in medical imaging could be larger than that of digital detectors. While FlashScan 20 addresses one modality-x-ray-the monitors can be used across all modalities, further helping the company find new volume for its manufacturing capacity.

"There are other modalities that the image sensors don't address that the displays will," Cobb said. "With the image sensors, there is going to be a paradigm shift, and most of the market will start to shift toward digital image capture, but that is a market that is deep but not very wide. Displays are the opposite."