By Jack Gershfeld
In the last 10 years table and wall mount AV interconnections have become standard in corporate boardrooms and training rooms. Early designs consisted of a wall mount plate with five BNC connectors for an RGBHV-type signal and maybe a network connection. As AV installations became more sophisticated, so did the wall mount AV interconnections.
A new product category evolved that allowed easy connection of laptops to display devices in training rooms, boardrooms, and conference rooms. With the introduction of tabletop interconnect boxes, conference tables looked aesthetically pleasing and at the same time became AV functional when laptop computers were used to display presentations.
Today, table and wall mount AV plates, boxes, and interfaces play an integral role in many AV installations. The choices that AV designers face are numerous; many companies offer different approaches to address specific needs. To make reference to these devices easier, we call them "AV portals."
Wall Mount AV Ports
Standard wall plates come in many different variations that can fit a variety of applications. One of the standards used extensively is "Decora"-style wall plates.
Figure 2.1 Decora-style wall plates
The convenience of Decora wall plates is obvious because of the modular way of designing wall plates for network and AV interconnections. The plates are well-suited for light-duty applications in office environments.
In many cases "Keystone" connectors become connectors of choice for Decora applications as they can be easily snapped in and out to meet specific requirements (see Figure 2.2).
Overall, Decora and Keystone combinations provide low-cost design for standard applications. The Decora plate solution works equally well for small or large installations, with little variation in cost per plate (see Figure 3).
Some limitations of Decora-based plates include limited connector layout options, relatively weak structural integrity due to the plastic construction, and limited color choices. In addition, not all of the connectors are available in Decora-style, pushing design into different type wall plate solutions.
Customizable Wall Plates
When faced with custom wall plates, options are open to design wall plates that provide all necessary functionality in one easy-to-use solution. In a custom wall plate, the size of the plate is adjusted to fit standard U.S. electrical gang boxes. Typically, wall plates will fit into one-, two- or three-gang plate size (see Figure 4.1). Within the wall plate, connectors are positioned and logically arranged to provide necessary functionality.
The color choices are available fit any designer's taste and vary from any type of painted color to brushed aluminum, antique brass, a black anodized look, or stainless steel. The lettering is provided by using a silkscreen process, displaying artwork and company logo.
Designed for flexibility and aesthetics, these wall plates provide a perfect blend of style and budget. This solution becomes more affordable as number of plates increases.
A good benchmark is more than 10 plates.
Custom Wall Plates
The most flexible wall plate design is allowed when there is no limitation on the form factor of a plate and when functionality of the plate is of paramount importance. Some of the applications involve high-profile boardrooms and corporate meeting rooms.
These wall plates are designed for functionality and style. More and more customers are asking for solutions that provide maximum flexibility in design combined with rapid product delivery and reasonable price.
To fulfill this need, there is free software now available that allows designers to see their wall plate designs before they are ordered. Once designed, the file is provided to a manufacturer who produces plates (see Figure 4.2).
A fully customized wall plate solution becomes cost-effective with order quantities of 25 or more. In many cases these plates combine AV interconnection with isolated power sockets, providing easy hookup for laptops, video game consoles, iPods, or any other AV sources.
Figure 3 Keystone snap-in connectors
Depending on the specific application, different connectors may be required. The most common connectors for typical conference room installations are:
- Network RJ45
- VGA HD-15 and Stereo 3.5mm
- Power Socket (USB, HDMI, etc.)
For educational environments, such as classrooms, additional connectors for composite video and audio can be added. At times an S-Video connector is added for better video quality.
- RCA Yellow Video
- RCA Red - Right Audio
- RCA Black - Left Audio
And for a total audiovisual experience, additional functionality is added to derive the ultimate interconnect portal (see Figure 5):
- Multiple USB ports - for charging USB-powered equipment (phone, camera)
- Audio and video on a 3.5mm - compatible with output from an iPod fed directly to a display device
- HDMI connector - for high-definition players including portable video games
For a large boardroom or conference room, multiple wall plates need to be routed and switched to a projector. This can be accomplished by using a select switch on each plate. In a typical configuration, a select switch will contain an LED that will be illuminated when a specific wall plate is selected. The video switcher can be set to auto-select mode to select video between inputs depending on the signal available at the plate. In this configuration every wall plate has a priority assigned to it. The wall plate with the highest priority will be routed to the display once the video signal is available. In manual configurations a specific wall input plate is selected by using the "Show me" button located on a wall plate. When the button is pressed, a signal is sent to a switcher to select that input.
Cabling Requirements
Important to wall plate design are cable connections on the back side of wall plates. In typical applications, gender changers are installed on the plate, and cable from the back of the plate is connected directly to the gender changer. In many cases this can present a challenge because a gender changer with a cable attached to it can extend 3 to 4 inches deep. Allowing sufficient wall depth is important using this approach.
Another approach is to bring cable directly to the plate and use solder-type connectors soldered directly to cables. Although very reliable, it makes servicing the wall plate rather difficult. Replacing connectors becomes laborious and requires specialized equipment. It is probably better to avoid this type of configuration.
One of the best ways to connect cables to the wall plate is to use isolated panel mount connectors with small 8-inch pigtails on the back. The isolation of connectors from metal chassis or from the metal electrical box is important to avoid potential ground loop in AV systems. Although not as prevalent in video, a small audio ground loop can create an annoying buzz that is difficult to troubleshoot and resolve. A small cable pigtail allows easy cable routing and provides for very shallow installation. Typically the AV plate with pigtails can be installed within 2 inches of wall space. Presence of pigtails also allows for ease of maintenance.
Figure 4.1 Standard wall plate sizes
One of the more troublesome connectors is the VGA connector. Originally designed for less than 100 plug-ins, this connector will need to be replaced some time in the future after installation.
Automating the AV Interconnect Design
Wall plate design is an important part of an overall AV system. Today, with pressures from customers to deliver product fast and according to specific requests, any automated system would provide direct benefits to AV designers. A typical CAD-type system would provide the ability to design both standard and custom wall plates with a minimal amount of time.
The heart of any CAD design environment is a well-designed library of components. For AV wall interconnect plates, that would include a library of different panel mount connectors, a library of standard wall plates, and a library of standard rack plates. With available libraries, the design becomes a simple drag-and-drop exercise. In many cases it is better to select software that is designed with AV systems in mind. It would give users the ability to lay out wall panels and provide instant pricing on the selected options.
Figure 5 Ultimate wall plate for total AV experience Conclusion
As AV installations become more demanding, so do requirements for robust and user-friendly wall mount solutions. Customized wall mount interconnect plates provide designers with an opportunity to provide solutions that uniquely fit customer requirements. With proper selection of required wall mount connectors, an AV system will perform the intended task of connecting the customer to the AV system.
Jack Gershfeld is the CEO of Altinex and focuses on product development for the wall mount and tabletop mount market. He has been involved in the AV field since 1983 and has developed numerous innovative AV products that earned him multiple industry awards. Over the years he has taught ICIA seminars and participated in many industry conferences.
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