INFORMING THE SIGN INDUSTRY. LED Message Centers

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1 INFORMING THE SIGN INDUSTRY LED Message Centers As a recognized leading supplier of LED displays, Daktronics seeks to provide information to the sign industry to help keep standards high for message centers. This is intended as an educational tool to help people recognize the attributes of a high-quality LED message center. Daktronics provides the facts about LED technology and the reasons why Daktronics designs and manufactures displays the way it does... to provide the greatest value and utility for Daktronics customers.

2 About LED Message Centers Introduction The dynamic capabilities of electronic message centers using light emitting diode (LED) technology continue to attract more and more retailers. Retailers, and non-retail entities, such as libraries, houses of worship and schools, use this affordable, reliable and flexible medium to advertise inventories, circulate information and reach out to communities with public service announcements. A number of suppliers manufacturing LED systems have emerged in response to this rising market demand. How can the quality of the displays they offer be evaluated? This brochure provides you some critical points to consider when assessing an LED electronic message center: Light Emitting Diodes (LEDs) Critical characteristics LED Display Lifetime What affects LED display lifetime LED Colors & Intensities Requirements of different LED colors LED Display Contrast Effects of good and poor contrast LED Display Dimming Suitable dimming for readability in all conditions LED Display Color Depth Determining available colors Video What constitutes a video-capable display LED Message Center Industry Characteristics of a reliable supplier Questions to Ask a Potential Supplier About their LED message centers

3 About LED Message Centers Light-Emitting Diode (LED) LED is an abbreviation for light-emitting diode. An LED is a solid-state electronic device that emits light when energized by applying power. The LED die is mounted to a lead frame (see right) which is encapsulated in an epoxy lens. The epoxy lens directs the emitted light and protects the LED die from physical damage.the lead frame provides the electrical connections, the physical mounting and a thermal heat sink to remove the heat generated within the LED. A display manufacturer must have an in-depth understanding of LEDs and their properties, as well as use high-quality components in order to develop effective designs that stand the test of time. What Daktronics Does Daktronics uses LEDs from the industry s leading suppliers and only from suppliers capable of meeting Daktronics specifications for brightness longevity and color standards. Daktronics uses more LEDs than any other display manufacturer.* Daktronics has excellent relationships with the top LED manufacturers in the world. Daktronics contributes to the research and development efforts of our LED suppliers, spending significant time at their facilities reviewing processes, communicating market needs and discussing development paths. Daktronics has excellent relationships with the top light-emitting diode manufacturers in the world * Daktronics is the #1 user of Nichia light emitting diodes in the LED display market in America. Hideki Kaneguchi Manager Nichia Corporation Daktronics is an Avago (formally Agilent) Premiere Partner. Premiere partners are longterm, high-volume Avago customers. Jovani Torres Regional Manager Avago Technologies

4 About LED Message Centers LED Display Lifetime The operational lifetime of an LED display is determined by the lifetime of the LEDs. LED manufacturers estimate the LED lifetime to be 100,000 hours under certain operating conditions. LED display end of lifetime is when the frontal brightness has decreased to 50% of original brightness. Three primary factors determine LED lifetime: - Manufacturing process of the LED diode - Driving (powering) method of the LED - Temperatures present at the LED die during operation LED thermal management is vitally important to maintaining LED lifetime. Increasing the power through an LED increases brightness but reduces its lifetime due to increased power generation. Increased exposure to higher temperature also shortens the lifetime. LED thermal management can only be done through the LED lead frame by conducting the heat to a Printed Circuit Board (PCB) and by allowing airflow to cool the LED lead frame. Thermal design of the end product is of paramount importance. The designer must consider how to manage heat in order to enhance the performance of the LEDs. If heat management is not considered, the lifetime of the LED will be significantly decreased or the LED will fail. Nichia Corporation Thermal Management of LEDs LED Application Note October 31, LED display components must be designed to handle a wide range of outdoor environmental factors, such as temperature and humidity. All components must be coated to protect from possible corrosion. What Daktronics Does Daktronics designs and manufactures its own LED modules to ensure the consistency and quality of the manufacturing process. Some display manufacturers purchase LED modules from low-cost manufacturers who many times have sacrificed quality to ensure lower cost. Daktronics mounts LEDs directly to a Printed Circuit Board (PCB) that is installed as part of the cabinet construction. This allows ventilated air to cool the PCB and lead frame, thereby cooling the LED die and providing thermal management of the heat to maintain LED lifetime as recommended by the LED manufacturers. Some manufacturers encapsulate the entire LED lead frame in a pixel separate from the cabinet, not allowing the LED to cool through the lead frame. Daktronics performs a module-coating process that protect the displays to lengthen their lifetimes. Some manufacturers skip this step to cut costs.

5 About LED Message Centers LED Colors & Intensities The color and brightness emitted by an LED are determined by the chemical composition and construction. Single-color (monochrome) displays are made up of one color of LEDs, whereas full-color displays contain LEDs that emit red, green and blue light. The color efficiency of the human eye has different sensitivity to different colors, and therefore perceives the brightness of each color differently. The number of LEDs alone does not determine display brightness. The design, quality, brightness, lens and viewing angle of the LEDs, as well as the drive method and contrast of the module, determine the overall brightness of a display. In fact, the more LEDs used per unit area create more heat and therefore require more cooling. What Daktronics Does Daktronics designs displays for proper color efficiency matching which provides a red, amber or full-color display with uniform intensities. Some manufacturers design displays for the same brightness for all colors, which creates red displays that are too bright and amber displays that are not bright enough. Daktronics powers the LEDs according to manufacturers specifications and uses the optimal number of LEDs required for the application. Some manufacturers suggest that more LEDs create a brighter and therefore better display, but as noted above, this may not always be the case.

6 About LED Message Centers LED Display Contrast Along with proper brightness, a display must have high contrast for good readability. Contrast is the difference between the background s off state (blank display area) versus the on state (illuminated display area). High contrast increases the readability of a message, much like white text on a black background, causing readers to focus on what needs to be seen. The highest contrast appears in a display with a dark border and a consistent dark black background across the entire display with minimal sunlight reflection. A louver system provides shading and black, non-reflective materials ensure the least amount of reflection. Polycarbonate or acrylic face material may provide sufficient contrast, although with a potential for glare, but does not provide as high a contrast as flat black paint or a black potting encapsulant. What Daktronics Does Daktronics LED modules feature a full-length, seamless black louver system across the entire module, providing a consistent contrast across the complete display face. Poor contrast Good contrast Some display manufacturers use individual louvers over each pixel or LED, which produces a pixelized effect and adversely affect uniform contrast. Daktronics offers different display products with carefully selected face materials, each having a preferred application and quality of image. Some manufacturers offer customers a limited choice.

7 About LED Message Centers LED Display Dimming For maximum effectiveness, a display must have the capability to adjust brightness levels for correct intensity and high contrast according to ambient light conditions during any time of day. At night, during lower light conditions, a display that is too bright due to inadequate adjustment may 1 be worse 2 than a display 3 that is too dim. An overly bright display can be distracting and difficult to read, which can damage market acceptance and result in stricter sign codes. A good display control system should have multiple dimming control methods including: automatic dimming as determined by ambient light conditions, scheduled dimming that can be preset to adjust at scheduled times and manual dimming that instantly adjusts the brightness. Scheduled dimming is required when an auto dimming system must be overridden to meet certain conditions or as sign codes require. What Daktronics Does To ensure effective dimming, Daktronics displays feature these capabilities: automatic dimming through a light sensor, scheduled or manual dimming through software control. Not all manufacturers have options for automatic dimming or scheduled dimming, resulting in an overly-bright display that will be difficult to read. Daktronics displays dim to an optimal level according to current ambient light conditions using many levels of dimming to provide superior readability and maximum effectiveness of the display. Many other manufacturers displays don t dim low enough in dark conditions, or don t provide multiple levels that allow a wide range of dimming, resulting in unclear content and diminished effectiveness.

8 About LED Message Centers LED Display Color Depth Dimming and shading refer to entirely different functions and the terms should not be interchanged. The word dimming refers to a uniform brightness adjustment across the entire display to correct the intensity for ease of reading during different ambient light conditions. Shading, or color depth, affects the light output variations of each individual red, green and blue LED to create images within the display. Color Depth Chart Bits per Color Resulting Shades Per Color Resulting RGB Color Capability 5-bits 32 32,768 6-bits ,144 8-bits million 10-bits 1, billion 12-bits 4, billion 2 5 x 2 5 x 2 5 = 32,768 colors Calculation explanation: Each individual red, green and blue LED can be in one of two states, either on or off. This example uses a color data processing of 5 bits for each color. So, each color is 2 to the 5th power and multiplying each color s depth provides the overall color depth of 32,768 colors. Although dimming and shading have different meanings, some manufacturers will combine grey scale shading values with dimming values to create a color specification that appears more impressive on paper than it is capable of producing in the field. Combining shading values with overall dimming values is a deceiving and misleading practice. Below is an incorrect calculation that includes dimming as part of the color depth: 2 5 x 2 5 x 2 5 x 32 dimming = 1 million colors What Daktronics Does Daktronics matrix displays are available in no shading monochrome, 64 shades monochrome, 32,768 colors RGB or 68 billion RGB and 4.4 trillion colors for video displays. Some display manufacturers will combine shading and dimming values to create a more impressive number. This practice can be deceiving.

9 About LED Message Centers Video Video can be described as displaying a moving image, which is made up of many individual frames played at a fast rate. Good video is played at 30 frames per second or higher. Slower rates can begin to look choppy and affect the presentation quality. Video content can be live, such as from a camera feed, or pre-produced, such as previously recorded live feeds, or previously created content. The LED display industry generally defines fully-capable video displays as being capable of both live feeds and pre-produced content, whereas graphic messaging displays are only capable of pre-produced, or stored content. Many LED display applications do not require the live feed capability or complexity of these systems. The higher the level of expectation, the higher the required display capability. Video graphical frames require high pixel counts and color depth to provide good definition for highly detailed, accurate and recognizable images. Video clips can be run on small displays with minimal color depth, but the image will look pixelated and will lack definition; however, the results may be acceptable for certain applications. Color depth, or levels, is the amount of color available to portray the image. Most digital video content is 16.7 million colors, but more levels of color depth are recommended to provide proper color matching to the original image. Video purists suggest a minimum of 1 billion colors for the best video images. Daktronics Position Daktronics offers many different display types that can meet the entire range of application needs, from small graphic displays, to simple video messaging displays, to the highest quality level of true video displays. Some manufacturers overstate their products as video capable, when in reality, these products are limited to only graphic capability or pre-produced video clips.

10 About LED Message Centers LED Message Center Industry Since the advent of high-brightness red, green and blue light-emitting diodes in the mid 1990s, many firms have entered the LED display manufacturing industry, and many have failed. To be successful in the industry, a company must provide dependable displays capable of showing high-quality imagery, control systems that offer creation and management of content appropriate for the needs of each particular customer and ongoing product support for many years. Daktronics Position Dedicated to the electronic display industry since Since 2001, independent market research firm isuppli Corp. lists Daktronics as the world s leading provider of LED displays. Daktronics LED displays are constructed in Brookings, S.D., United States, on one of the largest manufacturing floors devoted to building LED displays in the industry. Manufacturing space expands as needed, in response to changing market needs. Daktronics is committed to continued investment in research and product development to expand the market. Daktronics is a financially stable, publicly traded company that will be around for years to come to support your Daktronics display systems. Daktronics offers a comprehensive set of service options and maintenance agreements to keep customers display systems operating at maximum impact. Daktronics staffs more than 40 regional offices nationally and internationally with highly trained sales and technical service specialists. In addition to the regional sales & service offices, Daktronics partners with more than 100 authorized service companies evaluated and trained to provide customers with prompt and efficient service.

11 About LED Message Centers Questions to ask a potential supplier... about their LED message centers Now that you have had a chance to review these important points, here is a list of questions that will help you apply what you have learned to assess the quality of an LED display. Do you use the highest LEDs available, manufactured by industry leaders? How are the LEDs mounted in the modules? How is heat removed from the LEDs? Do you design and build your own modules? Is your display controller an industrial-grade, embedded controller made for outdoor signage, or only a commercially available personal computer? Do you have different display intensities for red, amber or full-color displays? What contrast enhancement features does your display provide? What types of display construction methods do you offer? What are your displays dimming capabilities? How do you calculate your color capability? Is your video display capable of running a live video feed? What is your plan to provide service? Do you provide local service? Do you have an 800 number available for service?

12 331 32nd Avenue PO Box 5128 Brookings, SD tel fax Copyright 2006 SL Rev