Choosing a TFT LCD Display Module

The TFT display is now the de-facto standard for most applications so how do you choose which is the right display for your application?

3 June 2019

Choosing a TFT LCD Display Module

The TFT display is now the de-facto standard for most applications so how do you choose which is the right display for your application?

There are a number of questions to be asked and many factors to be considered when answering them.

There are fundamentals from size and brightness to the operating environment, technology and interfacing, all of which have a bearing on the product that is right for you in this market of multiple options.

Size is the initial starting point for most projects and there is a seemingly infinite choice, however, there are some elements that can help narrow the field. Whether its handheld, HMI or Kiosk there are factors that are good to understand, there are sweet spots where products have made the leap from commercial commodity to full industrial supported such as 3.5”, 5”, 7”, 10.1”, 15.6” in the small and medium size range.

Format 16:9 or 4:3 comes into the picture especially when upgrading an existing design. Wide format is a growing trend with touch function replacing keypads for a new modern look where your existing 4:3 aspect ratio design gets a revamp without changing the chassis size. 

Brightness, viewing angle and contrast ratio are also important issues governed by the environment in which your product is to be used, as well as how it is to be used. There are many variants in these parameters with the technology of the display, TN, STN, Reflective and IPS, governing the basics but with optical enhancements such as circular polarizers, O-film (contrast enhancement) and Anti-Reflective coating amongst others also playing a part.

Brightness:- there are options in brightness levels with range and size and there are technical options which allow the ability for extending the life and reducing power with many displays now offering integrated LED drivers which reduce the number of external components required.

Viewing Angle:- mainly governed by LCD type but with options available such    as contrast enhancement mechanisms with IPS technology offering virtual 180-degree viewing capability  

Contrast Ratio:- most important factor in terms of optical performance and where most losses are seen is in high ambient light conditions. There are many mechanisms available to manage this parameter from timing control (TMR)   internally to surface coatings such AS AR (anti-reflection and for outdoor conditions optical bonding).

These 3 characteristics above are closely linked and are where most enhancements can be made to suit all environments and applications.                                                                        

Interfacing is also an area where there are multiple options, whether you are adding a TFT display to your embedded design or looking at a completely bespoke solution, the implementation is an important factor

TFT displays come in a wide variety of interfaces, RGB, LVDS, MIPI, SPI, Parallel MCU and Direct Drive. Which of these you should consider is determined by the resources you have available as they each put different demands on time and system requirements.

Temperature There are some basic Physics behind the specification of temperature range which needs management to give best lifetime performance. Most Panels now offer operating ranges in the -20/30 to +70/80 - degree range and again there are techniques and mechanisms to increase and enhance this performance where required.

Form, Function, Fit, Compatibility These are very much dependent on the manufacturer with some having this as a central principle in their range development TIANMA offer backwards compatibility in their NL range even going as far as to make the step between standard and wide format aspect ratio as easy as possible in terms dimension form and fit

Power Consumption is again basically governed by physics and dependent on the display type and backlight brightness requirement and interface drive type. If low power is a particular requirement then there are specific technologies to suit.

Surface Coating, Touch Screens, Cover Lens and Optical Bonding   Displace enhancement has become a major factor in the present market with more products being used outdoors. In the world of Tablets and Smart Phones, intelligent user interfaces and touch functions being a prerequisite for most new designs. 

The options and availability of these enhancements of a standard display option have therefore become much easier and much more cost-effective. Whatever is required there is now an easy cost-effective option available.

Price  Lastly but not least price can be the ultimate arbiter in the decision process and there are products to suit all pockets and requirements. TFT pricing is at a point where it is open to all applications and is at the lowest price/performance.

Whatever your Application, Requirement or Price,  RDS has the technical know-how, product range and service package to support.