Displacing mono character modules: a question of fit

Character modules are often used to fit the cost budget, power budget or physical aperture available. There is no need. We offer you a cost-competitive alternative with our cut down TFT.

As Apple and Samsung push the boundaries of display development in the quest for smartphone market share, why is it that so many professional products still ship with mono character displays? One reason is that graphics displays come in a relatively small number of standard sizes and the cost of redesigning and retooling the case to accommodate the display is prohibitive. So what are your options if you are committed to retaining the existing enclosure but need to give the user interface a thorough facelift?  

Right size displays


For some monochrome displays, it is possible to adapt a colour TFT module to fit the front panel slot. A creative display supplier can adapt a 2.8” QVGA module with a custom housing and backlight to fit into the aperture of a mono character module of 128x64 to 240x128. They can also adapt the driver PCB to minimise the redesign of the interface electronics, simplifying the transition. It is even possible to include touch control if required, to provide a fully up to date user interface. All the customer then needs to do is develop content to feature on the display. To keep programming effort to a minimum, this can be kept comparatively simple, but most customers want to make full use of the graphics features available.

For applications where such a module can’t be made to fit, there is a further alternative to a full custom module.  Using a new manufacturing process, standard  4.3” and 2.8” colour TFT displays can be cut to a specified height to suit the space available, opening up a whole new world of potential applications. A good example is rack mounted equipment. A standard TFT screen is too high to fit into a 1U rack case.  These two sizes of colour graphics TFT displays are 10.5 and 5 cm wide respectively and are 240 x 320” and 480 x 272 resolution respectively for the full size displays.

Clearly, this level of work must be done to the highest standards to maintain the quality and integrity of the original display. It needs to be carried out at an ISO9001 accredited site, with the appropriate clean room facilities. There is an initial NRE (non-recurring engineering) cost for this service, but it is less than one-tenth the normal upfront charge.

Sunlight readability

An issue with colour TFT especially with hand held instruments can be sunlight readability. In bright conditions, the backlight on a colour display needs to be turned right up whereas a reflective monochrome display can actually use the ambient light to improve readability.

Optical bonding can help address this, and this is also becoming more economical at much lower volumes than before.  It dramatically reduces the reflections in displays by eliminating air gaps between the layers using an optically matched filler adhesive. Using this technique, reflections can be reduced from 13.5% of the incident light to just 0.2%. This makes a huge difference to readability, especially in brightly lit and outdoor environments. Optical bonding also prevents condensation and improves mechanical shock resistance. In the past, many customers with lower volumes and /or price sensitive applications have dispensed with optical bonding for economic reasons despite its great and well recognised advantages.

New flexible manufacturing processes are allowing optical bonding to be offered on displays of 2.8” to 23.6” sizes with a very low minimum order quantity. The entire bonding process is carried out under one roof, at the site where the modules are manufactured ensuring both an extremely high standard of quality and a low cost of around one-third the normal price. This service covers modules with integrated touch controllers, scratch resistant or anti-reflective coatings, or protected by vandal proof glass. IP65/67 sealed panels for use in wet environments, and panels compliant with PCI standards for payment terminals, are also offered within the service.

Thinking out of the box

A more radical, and increasingly popular option is to move the user interface off the system altogether and implementing it on a separate module, bypassing the character module altogether. Embedded Display platforms priced at under £100 feature a pre-integrated TFT touch screen, an ARM processor and wireless connectivity and can be turned into a full independent controller.  These platforms come with a rich variety of interface options: USB ports, Ethernet, Bluetooth, WiFi, serial ports, GPIO, CAN bus and general purpose ADC sockets.  The best option is wireless control, which can be implemented at the host system end by adding one of the many standard WiFi or Bluetooth modules to a USB or Serial Port on the system, eliminating any redesign. 

These platforms are offered as a ready to go prototype and development boards that can also form the basis of the production system, eliminating unwanted interfaces and other features to improve security and reduce cost. Developers can, if they wish, just add a suitable enclosure and load their application software to deliver a finished product.


However the designer approaches revising the user interface, he or she should bear in mind that the quality and appearance of the display is central to the user’s experience of your product. You need to take care that this component is of a consistent high standard and resist the temptation to source low cost displays. Good quality industrial displays from reputable manufacturers are offered with guaranteed availability. Low cost suppliers are likely to be focussed on the consumer market, and their displays are often in production for as little as six months before the design or specification is changed. The trend is now for smartphone displays to get bigger rather than smaller, which means that production lines for the smaller 4.3” sizes and below are now increasingly being turned to producing larger sizes.

It has been shown again and again that the user interface has a huge impact on the user’s perception of their equipment, and is a real differentiator in the market. The options we’ve described are allowing designers to raise their game in user interface design, and replacing character modules with colour graphics screens, touch control and other enhancements. Manufacturing volume and cost are no longer an excuse for a drab user interface.

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