Content may need to be clearly visible across a wide viewing angle without distortion or haze.
Image courtesy Samsung
Supporting content
The display and the content it presents could be said to be ‘joined at the hip.’ The warmth, hue and visual appeal of content can vary from screen to screen. This is most obvious when comparing a strong brand colour—e.g. red—on two displays side-by-side. Brightness, resolution, contrast ratio, refresh rate and colour accuracy are all worthy of attention during selection.
Beyond appearance, though, much of the technology ‘under the hood’ has a significant impact on how content will play out. With respect to connectivity, for example, some manufacturers now embed the media player—i.e. the compact personal computer (PC) dedicated to content playback—within the panel, but most networks use external media players instead to take better advantage of a more diverse range of content management software. To cross the distance between a panel and an external media player, connections may use proximity cabling via Digital Video Interface (DVI), High-Definition Multimedia Interface (HDMI) or DisplayPort (DP) technology or a transmitter and receiver for wireless signals.
Connectivity of the panel to content management software is also important for reporting performance, as is ‘failover’ functionality to ensure content is displayed from internal memory without interruption when an external input is not working.
“Effective management capabilities are a vital consideration when choosing a digital signage display,” says Dan Smith, director of digital signage for LG Electronics. “Simple Network Management Protocol (SNMP) standards allow system integrators to communicate remotely with screens for more efficient troubleshooting, reducing staff time and resources spent monitoring and maintaining the displays. A panel-facing pixel sensor, for example, provides the ability to monitor the front of the display continuously, even if the backlighting is powered down. Wireless-fidelity (Wi-Fi), hardwiring and failover options for failed image inputs ensure content is always running seamlessly.”
Other functions that add value include automatic brightness adjustment to ambient light conditions, ‘screen wash’ to prevent phantom images from burning in and user lockout to prevent content hacking.
Some manufacturers now embed media players within their LCD panels.
Image courtesy Advantech
Viewing angles
While most flat panel manufacturers claim to provide a nearly 180-degree viewing angle, a screen’s image quality off the perpendicular viewing axis and at wide angles can erode quickly. The real issue, when selecting a display, is the degree to which content is easily viewable from a wider horizontal or vertical angle without the degradation of colour accuracy and brightness.
Off-axis viewing is a common requirement for displays mounted along walkways, beside drive-thru lanes, near customer service counters and in exhibits. As such, content needs to be clearly visible without distortion or haze from a wide viewing angle. The use of an anti-reflection coating or of anti-glare glass, in particular, can improve image quality and ease of viewing for these situations.
Selecting a supplier
Flat-panel LCDs may be purchased from (a) original equipment manufacturers (OEMs), (b) specialized firms that source key components from OEMs, (c) distributors or (d) resellers. In any case, the integrator will benefit from sourcing screens from a provider with a long track record and solid depth of experience with digital signage applications. Also, the supplier should be ‘healthy’ from a corporate standpoint to ensure they will still be around to honour warranties and upgrade devices should the need arise in the future.
It is important to keep in mind how sales representatives’ recommendations may be influenced by inventory levels, special promotions and commission structures. At the same time, integrators should be open to options that seem more expensive initially, but promise a lower total cost of ownership (TCO) and better performance over the expected four to eight years of operations.
Ultimately, flat panel selection for digital signage comes down to the question of which model will best showcase the planned content at the lowest cost over its length of use. Answering this question requires supplier and buyer to assess a range of options, set aside their biases and make a decision based on facts.
Lyle Bunn is an independent digital signage industry analyst, advisor and educator based in Brighton, Ont. For more information, contact him via e-mail at lyle@lylebunn.com.
