LCD Interface Options

There are three common ways to interface to an LCD:

Third Party A/D Boards
A third-party A/D board which takes the video output from a computer (that is intended for a CRT) and translates the signals into LCD flat panel compatible signals. These interfaces are the simplest because they use existing solutions that are commonly available for computers. These solutions are often used to replace an existing CRT monitor with an LCD. These offerings often include cable solutions and power supplies so it is almost a plug-and-play approach. The drawback is that they tend to be relatively expensive.

Single Board Computers with Integrated Controllers
The next level of interface is a single-board computer with an LCD controller built-in. These are often available in the form of kits with all of the bits and pieces included. The difference from the first approach is that the controller is embedded with a processor which must be included. These unfortunately tend to be very expensive. The advantage of this approach is the tight integration all on a single board.

Custom Designs using Off-the-Shelf Chip Controllers
The previous levels of interface are basically self-contained solutions that do not require extensive design expertise. The next level of interface requires design. It is appropriate for the customer who is already developing their own custom CPU board and wants to integrate a flat panel controller such as that which is available from Chips & Technology or Epson. The advantage is that the components are much less expensive. This approach requires software expertise to write (or integrate) the required drivers for the operating system.

Embedded LCD controllers such as Sharp's BlueStreak LH79520 are often used since they provide all the computing resources needed for a small application. This approach greatly simplifies the effort since software drivers, reference designs and cabling are already available from Sharp.

TFT Specific Interfaces
The lowest level of integration is the TFT-specific interface. This is often used for small displays where space and power are at a premium. In this case both the controller solution and the interface electronics, and power must be provided. This is the most difficult approach requiring a significant amount of engineering and development time and skill. This is also more difficult to manufacture because many of these interfaces have to be individually tuned.