Hi All ,
I 'm wondering why there is LCD Driver IC. I interfaced with the LCD with out it so I want why it is exist ? and in which it can help ?

 

The serial interface IC drivers open up several pins for other uses.

If you are talking about the Hitachi "Onboard" LCD Driver that listens to 14/16 pins, it translates the bits you send it into a character set.

The most common LCD interface is a serial interface, either a simple shift register, SPI, or UART based. Some are easier to work with in different languages (UART in BASIC), others free up pins in Assembly or C (SPI). In addition to creating a 'user friendly' protocol, some allow turning the backlight off and on through serial commands as well. It depends on what you need for features.

What I've seen most common is to simply use the pins to directly interface with the 16Pin LCD (Hitachi interface). Then use the LCD Enable line to allow other inputs on the same ports as the LCD, since data isn't read and written at the same time. The speeds are such that it seems simultaneous. Unlike talking to a graphical LCD though a serial interface.

Or did I miss the question?

 

The LCD displays that you normally interface with have an on-board driver chip. Usaully the Hitachi HD44780 or similar that stores the incoming data, converts the ASCII into display characters, does general housekeeping and drives the display with the correct waveform.

I suspect the driver chip you are talking about is for driving a static LCD display. Strictly speaking you don't need to use a special driver chip, you can drive a static display straight from a microcontroller, but using a driver chip frees up your microcontroller resources for more useful tasks.

This linkhttp://www.ubasics.com/driving_static_lcds describes how to drive static LCD displays with a PIC and give a bit of info about static LDC displays in general.