The screening process

We are all familiar with the large screen LED displays used throughout the entertainment, advertising and corporate event world. Steve Montgomery talks to users and manufacturers about how their screens are evolving to meet new demands placed upon them.

Early systems utilised blocks of discrete LEDs in clusters to create a colour, or at least best approximation to, full colour pixel. Mounted in hefty cases with all associated picture processing, cooling and power supplies, whole displays would be painstakingly assembled and lifted into position.

The emphasis today is on smaller, easier to install displays and value for money whether it is targeted at the fixed installation indoor or outdoor or rental market. LED technology has developed to the benefit of matrix displays as Martin Brown, Video Product Marketing Manager of Daktronics explains: “For indoor displays, black-package SMD (surface mount device) LED technology is becoming mainstream. This technology features an LED with a black body and tinted lens to increase display contrast, which is very important to the overall image quality of the screen. The blacker the better, as long as one can still generate the 2,000 nits of brightness ideal for indoor viewing. Outdoor displays are benefiting from a new generation of brighter through-hole LEDs. These have enabled screens in the outdoor segment to jump from 6,000 nits to 7,500 nits of intensity for many products without increasing power demands or decreasing product lifetime.” Black LEDs are also making an appearance in Hibino’s new range of 10mm outdoor displays, Kris Delafontaine, European Manager: “In general, the image quality of outdoor displays lags behind that of indoor displays. Our new 10mm outdoor display uses black LEDs and has similar levels of colour uniformity, depth and image processing to indoor displays. We are currently installing this display in Japan and working to promote this level of quality in Europe.”

From the user’s viewpoint, critical requirements are centre around usability, reliability and creativity. Al Green, Business Development Manager at XL Video, one of the UK’s largest rental and staging AV suppliers explains: “We work with manufacturers right across the range, but the most successful relationships, which are of the greatest benefit to us are those where we can collaborate and assist in their designs. Specifically where our needs are designed in to the product, for example where facilities such as access ladders can be attached and hot repairs carried out during a live performance and where installation procedures are streamlined. We have sets of displays where hundreds of square metres of LED screens can be positioned, installed and switched on within half an hour because we have worked with the manufacturer to develop a dolly-to-stage construction using motors and chains that fit our applications exactly. For world tours of global artists this is highly beneficial and often essential to the smooth running of the events.” Other aspects that of support are also critical, he continues: “Our job is to pull together all the screen elements of a live show for the production team; the content, various video inputs, construction and operation of the displays on behalf of users – whether they are rock groups or multi-national corporations at major conferences. We need manufacturers to invest their trust and support in us to ‘front‘ their product on their behalf and this can be in both rental and permanent installations. In return we deliver applications and sales to them as well as feeding back considerable information on market requirements.”

In terms of viewing characteristics, each project has specific requirements and priorities, Martin Brown: “A few items that consistently receive strong attention are display brightness: everyone is concerned about being able to see the display in all lighting environments; viewing angles: will the display turn a strange color when viewing from the side – also known as color shift and, of course, reliability and manufacturer track record. As many customers desire a custom screen to differentiate them from others in the area, design engineering and project management services also become important considerations. Companies such as Lamar, Clear Channel, JCDecaux and EyeCorp are, to varying degrees, incorporating LED technology into their display inventories. The technology is being accepted at a fairly rapid pace. LED is also being used by architects and urban planners to breathe new life into older city districts – often in combination with other rejuvenation efforts.”

Companies like Lighthouse Technologies, Mitsubishi and Barco have driven the development of display modules with models that cover pixel pitches from 4mm to 30mm. All are branching out into non-standard applications Simon Taylor, Sales Director of Lighthouse: ”Traditional applications in signage, rental and corporate are growing and becoming more demanding as users apply more sophisticated techniques and content. As LEDs are used for more diverse applications in special effects, lighting and mood setting, the industry is becoming far more fragmented and creative. Which has driven the development of our new products such as LEDScape Stripe, Mesh and Tile used in backdrops, flooring and stage sets in live events and broadcast as well as retail and exhibitions.” Similarly Barco has been at the forefront of product development, Andrew Healey: “Our NX indoor extra contrast displays use black LEDs on carbon fibre frames for uniformity, brightness of 2000 nits and contrast ratio of 4000:1 on a 4mm and 6mm pitch. Outdoors there has been a pull toward high resolution larger screens so that large areas can be covered. The sweet spot is around 15mm. Creative applications abound such as concerts where a 10mm blocks are positioned at 100mm pitch to cover a whole backdrop with a display that is part video, part special effect. On from there the MiStripe stip and MiTrix array yield design opportunities and huge creative potential.”

For larger walls, greater pixel pitches are appropriate although there is a balance between pitch and viewability, Andrew Hawker, Senior Product Manager at Element Labs: “We manufacture a range of products where traditional screen display manufacturers leave off, our products generally have a larger pixel pitch and are aimed at creative lighting applications and large scale displays. Our new Helix H37 product is a light weight and flexible fabric backed display, this has a 37mm pixel pitch and is ideal for outdoor, daylight readable applications such as a large scale video display or architectural features. Our products have pixel pitches ranging from 25mm to 100mm. Generally resolutions around 75 to 100mm are not for daylight applications. These are suitable for evening and night viewing, over larger distances. Where we find a lot of interest in the larger pitch displays is on stage sets where it is possible to construct the whole of a backdrop as an LED display and use it not just for video display but also as a special effects panel. These types of display are ideal for creative applications and our approach is to provide a video-enabled system so that content can be created using a computer graphics workstation and played out from a media server.”

Architectural applications have produced a need for modular, transparent LED matrices, resulting in the release of new mesh designs from several companies. These utilise metal or plastic tubular cross piece supports for LEDs with spaces between the pixels, making the screen both lighter and transparent, with up to 60% transparency. This extends the scope of applications so that new opportunities can be served; for example whole buildings can be covered in a mesh type display which does not adversely affect inhabitants inside the building, but offers full video display capability to external viewers. GKD’s Media Mesh is a stainless steel mesh with interwoven LED profiles and with connected media controls installed behind it. The LEDs reflect the images onto the facade, offering the ability to display a wide spectrum of graphics, text and video. Supplied as a roll of fully assembled Mediamesh fabric ready for installation it is simply unrolled and tensioned on a simple framework and will not destroy the aesthetic appearance of a building’s façade. This approach has met with a high level of acceptance in the industry, even where panels are used as architectural lighting features, rather than as video displays, although as Andrew Hawker explains, there is a slight change in mindset required: “ Lighting designers have to make a change in approach from traditional DMX style control to video based applications, but once they grasp that they become very enthusiastic and creative, developing effects that surmount those they had previously done.” With today’s control systems, it is possible to link a common presentation across multiple displays and display technologies within a facility or even across a continent. It is not necessary to have one control system for the projectors, one for the flat panel displays and one for the LED video displays. A single solution can do it all and make life much easier.”

An extension to the mesh and video technology is to physically separate blocks of displays and position them in three-dimensions rather than two. Element Labs has taken this a stage further in the release of Versa Tube; a single tube of multiple pixels that can be interconnected to form larger grids as desired and suspended vertically. This concept is regularly used on stage sets to create depth. Andrew Hawker: “Two dimensional graphics are mapped over a 3 dimensional display in such a way that there is a 3D effect with an impression of depth in the animations. This is particularly effective with graphic images designed for this type of event”

Clearly, the industry has taken advantage of the rapid developments in both display technology and video manipulation concepts to deliver new product and effects that meet and are driven by the creativity and requirements of installation teams in a huge and varied range of applications, which extend far beyond the original LED TV screen or advertising hoarding.

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