EL Technology Today

In the past EL displays, because of their unique performance and visual characteristics, were used mainly in the most challenging and demanding applications where other technologies were simply inadequate. Today, equipment and systems' designers use EL displays in a much wider range of applications. This is to fulfill the growing demands from their customers for improved image quality, longer lifetime and higher reliability. In addition, EL better meets the needs of the designer by offering a proven solution as well as ease of application.

As a relatively new technology, the pace of display innovation has been swift. Dramatic improvements in the brightness of the luminescent films, development of drive schemes to extend display life, significantly improved brightness, contrast, reduced power consumption, proprietary gray-scale algorithms, improved packaging to reduce size and enhanced shock and vibration resistance as well as the development of color, have all placed Planar in the position of setting the standards for the EL flat panel industry. A number of key patents plus a proprietary manufacturing process knowledge protect Planar's position.

Fast developing technology for fast developing markets

Planar's EL flat panel display technology has achieved major breakthroughs during the last decade:

• Dramatic improvements in the luminous efficiency of the thin films
• New drive schemes that extend display brightness and life
• Significant improvements in contrast and readability in bright ambient light
• Reduced power consumption
• Improved packaging to reduce size and enhance shock and vibration resistance
• Extended reliability, up to 100,000 hours MTTF
• Color capability
• Rapidly reducing costs

These innovations in the inherent performance of EL technology have set the image quality standard for the flat panel display industry. Planar displays are proving themselves as the best display solution in such demanding applications and markets as medical, instrumentation, industrial process control and defense equipment, as well as transportation and communications systems.

Thin Film EL Technology

Planar's ICEBrite EL Displays consist of a solid-state glass panel, an electronic control circuit, and a power supply.

The thin film EL glass panel consists of a luminescent phosphor layer sandwiched between transparent dielectric layers and a matrix of row and column electrodes. A circuit board containing the drive and control electronics is connected to the back of the glass panel. Voltage is applied to row and column electrodes causing the area of intersection (a pixel) to emit light.

The result of this solid-state design is a flat, compact, reliable, and inherently rugged display with exceptionally fast response times (< 1 ms).

Features and Benefits of EL Displays

• Unrivaled visual performance
• High brightness and contrast
• Wide viewing angle > 160°
• Rapid display response < 1 ms
• Space efficient mechanical package
• Low EMI emissions
• Extremely rugged and durable
• Reliable, long operating life
• Superior Brightness and Contrast means incomparable image quality

Planar's proprietary Integral Contrast Enhancement (ICE) incorporates a dark, light-absorbing layer at the rear of the display to capture stray light from the environment and from adjacent lit pixels, eliminating blooming or haloing.

The resulting image clarity plus the higher brightness of ICEBrite means superior readability across a wide range of lighting conditions. The ICEBrite architecture eliminates the need for expensive contrast-enhancing filters, further reducing the cost of the display system.

ICEBrite is a ground-breaking technology aimed at passive LCD replacement. It has higher brightness, greater contrast, and an LCD-compatible interface in a cost-competitive package.

Wide Temperature Range means reliable performance and stable image quality - hot or cold

Planar EL displays are frequently used in a demanding industrial temperature range and also for equipment that is used outdoor in arctic winter and desert heat. All Planar displays are designed to operate over a wide temperature range which can extend from -40 up to +85°C.

Over the normal -25 to +65°C operating range the image quality is virtually unchanged. The fast response time of the display is maintained even at low extremes of the range, and there is no decrease in contrast or viewing angle that require operating adjustment.

Rugged Design means reliable operation in "hostile" and demanding physical environments

Planar EL displays are commonly used in harsh and demanding industrial and defense environments. An EL display consists of the emissive El glass panel - a totally solid-state structure - pixel drive electronics and power supply, all built into a compact, lightweight, but rugged package. Planar EL displays have superb shock resistance of 100g and are therefore widely used in portable devices and applications where shock and vibration or rough handling of the devices cannot be avoided.

Wide Viewing Angle means you can easily read these displays from anywhere in the room

The viewing angle of Planar EL displays is wide both in the horizontal and vertical directions. Unlike pixel masking display technologies such as Liquid Crystal Displays (LCDs), Planar's EL displays maintain luminance and contrast levels that are constant over the whole viewing angle range. This means that the data on the screen can be easily discerned, no matter from what angle you view the screen. The wide viewing angle (greater than 160°) of Planar EL is critical in applications where the screen has to be read from off-angles or when the equipment has multiple users simultaneously, for example, in an operating room, on a factory floor, or in a defense situation.

Low Electromagnetic Interference (EMI) means simplified designs and "clean" environments

Planar EL displays are designed to minimize both EMI susceptibility and EMI generation. Designing a display for minimizing EMI susceptibility means ensuring that stray EMI, generated from power lines or other powered equipment in the vicinity, will not interfere with the proper operation of the Planar EL display.

Designing with minimized EMI generation means assuring that the display itself does not generate electromagnetic signals that will interfere with other equipment in the area or the proper operation of the instrumentation in which the display is being used.

Planar's EMI conscious designs simplify the structure and design of the equipment in which they are used. In fact, many Planar displays have incorporated a simple, inexpensive ground plane shield, which covers the whole back area of the display. This ground plane acts as a closed door, shutting in any EMI signals that the customer's system would otherwise attempt to release through the display "window".

Low Power Consumption means that better display performance is available for battery operated applications

Today EL displays utilize advanced, power saving drive techniques. The power consumption of Planar's Small Graphics Displays (SGD) is typically lower than the power needed for backlit LCDs. This has allowed rapid adoption of EL displays into battery powered applications for customers who until recently had to suffice with the poor viewing characteristics of LCD technology. In addition, most Planar displays feature user-friendly, screen saver methods for cutting the power consumed to less than 1 watt.

Another important feature of Planar EL displays is the simplicity of the input power requirements. All required display addressing voltages are generated internal to the display electronics typically from +5 Vdc and +12 Vdc. No additional variable power supplies are needed as in LCD displays.

Fast Response Time means crisp, clear and accurate wave form representations

The response of an EL display (the time it takes to show the data) is very fast, less than one millisecond. This means that moving objects on the screen are displayed real time without aftershading (for situations like mouse movements) and there is no ghosting in video images. This also means that crisp, clear, accurate waveforms are represented, improving the accuracy of the information displayed. These are critical requirements in applications like medical and test instrumentation. The rapid display response is due to the fundamental physics of the EL thin film structure and is virtually constant over the complete operating temperature range from -25 to +65°C.

Long Term Reliability means reduced warranty cost and improved customer satisfaction

The lifetime of a Planar thin film EL (TFEL) panel is very long. Based on luminance stability measurements of long run existing applications, the brightness decrease of the phosphor of Planar EL displays can be estimated to be less than 25% on 180,000 hours' (20 years) continuous use at 60 Hz frame rate.

Planar verifies, through long term testing, that the expected trouble-free operating time (MTBF) of the display assembly, which includes drive electronics, is up to 50,000 hours. Planar offers a warranty period of one year on all OEM Component displays. During the warranty period, and after, Planar provides a quick repair turnaround time for the displays.

Download a PDF of our Electroluminescent Display Technology Overview white paper.