Drive and control technology to accelerate the implementation of new applications

Unconsciously, our daily use of a variety of portable devices quietly changed. The main purpose of the mobile phone from call extended to a variety of auxiliary functions, such as games, Internet, email, photos etc.; enhance the demand for video player MP3, upgrading to PMP; more and more PDA, and even mobile TV equipment also appears in the US. A common feature of these devices is to improve the requirements of image browsing and video playback, and to emphasize the friendly user interface.

The size of the screen is not only larger, higher display brightness and display the details of the stronger, faster response speed, and requires the entire display control and drive system can not consume too much power, not occupy too much space on the circuit board, so as to reduce the power consumption and integration shows an important development trend of drive and control circuit. In addition, the touch screen is more and more popular based on capacitive interfaces, which make mobile phone equipment operation more friendly, but how many touch from the market plan, choose the suitable scheme of touch is a primary problem to solve. In this paper, we will discuss the driving and controlling technology of LCD and OLED, and the development trend of the touch screen control technology.

Integration of the driver IC must balance the global factors

At present, most manufacturers provide LCD drive more and more to the integrated development, not only the booster, source driver, gate driver integrated into a single chip, but also some pioneer electronic part is integrated into the display glass. How to balance the pros and cons of integration? How to achieve maximum power savings? How to deal with the new requirements of the new display driver? These issues become a hot topic in the field of driving.

For portable devices in the display driver circuit, reducing the volume is particularly important. The source driver IC, gate driver IC, clock control, power supply, and even cache integrated on a single chip approach will undoubtedly reduce the volume of the system, but also simplifies the design of portable equipment engineer, so popular.

In addition, due to the coexistence of a variety of high speed serial interface standard, such as mobile digital display interface (MDDI) standard, LVDS technology based on mobile video interface standard (MVI) and mobile industry processor interface (MIPI) standard, so in the display controller, interface conversion chip or IC driver integrated these interfaces become a way to reduce the complexity of design. For example: Samsung, Toshiba, SHARP, EPSON, Renesas, Rom and other companies have launched their own built-in MDDI interface display controller and interface conversion chip, Systech also launched a MIPI interface with the LCD driver IC.

Application diagram of PowerLite module in display screen.

In order to meet the application requirements of the mobile phone, but also gave birth to some of the mobile phone application program interface (API) of the intermediate platform, including the Systech launch support mini-RGB interface flexible connection in mobile telephone system. The solution consists of mini-RGB controller SSD1270, a series of single chip TFT driver (SSD1276, SSD1269, SSD2006 and SSD2116) and mini-RGB interface, which greatly simplifies the baseband system and display the connection between modules.

It is worth noting that, in addition to a higher degree of integration and integration of a variety of IC interface, the industry has a number of manufacturers launched the LCD driver integrated into the display products. However, the take-off of the technology still need to solve the problem of cost, yield, and capacity.

"The higher integration enables customers to reduce the passive components outside the display module, but in many display technologies, only a low temperature poly (LTPS) TFT screen is suitable for integrating the electronic parts on the display screen. Leadis IC, vice president of LED driver and power management Donato Montanari said.

The company's executive vice president and chief operating officer Ken Lee added: "in the end, require a higher pixel density of the product, the market share of LTPS than the conventional display driver a-TFT (amorphous silicon), but in the low-end module, a-TFT will continue to perform well, because a-TFT off the capacity to bring lower costs. "Leadis is currently focused on small, single chip display driver solutions.

The driver is integrated into the display glass in the advantage of reducing cost, and simplify the LCM driven process, but the Systech Zhou Zhiguang also pointed out: "the negative impact of this integrated approach will enable higher power consumption, in addition due to the realization of RAM and high speed interface in the panel (500MHz-1GHz) is not easy, so this it is not a kind of flexible solutions. "But he believes that embedded drives will be a trend that takes 5 to 10 years and a lot of investment to achieve.

A new algorithm to achieve smart power savings

With the status of the display in the portable devices is becoming more and more important, the consumption of the power consumption of the whole system is increasing, and the demand of low power consumption and even zero power consumption is rising rapidly. Shortly before the United States of California at the "SID 2007" exhibition, many new technologies are aimed at this need, including MEMS bistable bistable electrophoresis display, LCD, (MEMS) display, electrowetting display, traditional low power LCD.

For power saving, the display driver IC is also an important consideration in the design of power system