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September 9, 1997

Hitachi Releases a High-Resolution TFT Driver Set for Multi-Scan Monitors

- LCD Driver Achieves the Industry's First Expansion and Centering of Display Data for the Multi-Scan Function -

TFT displays are widely used in notebook PCs and OA equipment due to their high contrast, fast response, and excellent overall image quality. Recently, in addition to the large display size and high resolution, multiple output and high-speed data transfer capabilities are required to allow LCD drivers to handle XGA and SXGA. Hitachi has already released the HD66322, 384-output data line driver, for color TFT to handle larger display sizes. At the same time, in the field of workstation monitors and desktop PCs with built-in monitors, multi-scan monitors are taking the main stream position and screen displays that handle various display modes such as XGA and VGA(*5) are required. For example, to display VGA data of 640 x 480 pixels on a TFT display screen that handles XGA of 1,024 x 768 pixels, the data must be expanded horizontally and vertically according to the display size in order to center the data. To achieve this capability, as much frame memory as the screen size must be incorporated in the display control circuit section. Before transferring the data to the TFT and other driving circuits, image processing such as expansion and centering must be performed for the data within the CPU. As the size of the TFT display increases, more frame memory is required, in addition to an increase in the CPU load for the expansion and centering processing.

To handle these requirements, Hitachi has developed a TFT driver set, the HD66321 and the HD66326, that achieves expansion and centering of display data according to the screen size. The HD66321 is a gate line driver with 258 outputs; three HD63321s implement the gate line required for XGA, and four HD63321s implement the gate line required for SXGA. This driver expands and centers data in the vertical direction according to the external control signals for multi-scan operations. To handle large displays, the HD 66321 allows a wide range of settings, up to +25 V for the ON level and down to -15 V for the OFF level. In addition, since up to two OFF levels occur, the HD66321 handles a dual electrode inversion method and a driving method that uses a coupling capacity to the front gate line in addition to a pixel inversion method.

The HD66321 is provided in a TCP(*6) of a tape 35 mm in width and the lead width (outer lead pitch) that connects with the LCD display is 90 micrometers. The HD66326 is a line driver with 384 outputs. Eight HD66326s implement the data line for XGA and ten HD66326s implement the data line for SXGA. This driver expands and centers data in the horizontal direction according to the external control signals for multi-scan operations. With the high-resolution and high-speed operation amplifier that can withstand 12V, the driver can charge a data line load of 60 pF load capacity at 10 microseconds and can drive displays of high-resolution effectively.

The inversion operation by dot that outputs a positive polarity voltage and a negative polarity voltage to the output pin section alternately achieves a high picture quality of low cross-over noise interference. The HD66326 is provided in a TCP using the 50-micrometer pitch inner lead technology, which is the industry's finest pitch. Since the HD66326 was designed giving consideration to both chip size and TCP size minimization, it can achieve reduced cost in end products. The TCP is provided in a 35-mm tape width with an outer lead pitch of 65 micrometer. This driver set eliminates the requirements for external frame memory and a dedicated control circuit for expansion and centering of data to handle multi-scan operations, thereby simplifying the system. Based on the newly-developed multi- scan method, high-speed operation amplifier circuit, and multi-pin technologies, Hitachi continues to develop the TFT displays which correspond to market needs such as low demand for voltage products.

- Note -
1. Gate line driver
Wiring that scans a TFT display line in order to supply the electric charge supplied from the data line to the selected line; normally, wiring for the horizontal direction.
2. Data line driver
Wiring for supplying electric charges in order to determine the display color of each dot of TFT displays; normally, wiring in the vertical direction. The amount of charge supplied determines the graduation of each dot.
3. XGA: Extended Graphics Array
A standard for display resolution. XGA is a registered trademark of International Business Machines Corporation, and stipulates a resolution of 1024 x 768 pixels.
4. SXGA: Super Extended Graphics Array
A standard for display resolution that stipulates a resolution of 1,280 x 1,024 pixels.
5. VGA: Video Graphics Array
A standard for display resolution. VGA is a trademark of International Business Machines Corporation, and stipulates a resolution of 640 x 480 pixels.
6. TCP: Tape Carrier Package
A package technology in which devices are mounted on a thin-film tape. It supports ultrathin mounting with a thickness of less than 1 mm.

- Application Product Examples -
- Workstation monitors
- Desktop PCs with built-in displays
- Notebook PCs

- Pricing in Japan -

Catalog No.	Sample Price (yen)
HD66321TA0	1,200
HD66326TA0	1,700

- Specifications -

HD66321

Item	Specifications
Function	TFT gate line driver
Power supply voltage	3.0 to 3.6 V (logic system) +15 to +25 V (gate positive polarity) -5 to -15 V (gate negative polarity)
Operating temperature	-20 to +75oC
Packages	294-pin TCP
Number of drive outputs	258 outputs (256 for the scan line)
ON-resistance	0.8 kilo-ohms
Clock speed	200 kHz
Other functions	Switching the number of scan lines between gate lines (Select one of 1, 2, 16, and 32) Vertical expansion and centering Can handle switching to gate OFF level alternate current Supports coupling capacity drive

HD66326

Item	Specifications
Function	64-level TFT data line driver
Power supply voltage	3.0 to 3.6 V (logic system) 6.0 to 10.0 V (LCD)
Operating temperature	-20 to +75oC
Packages	450-pin TCP
Data input	36-bit digital input (6 bits x 6 pixels)
Number of drive outputs	384 outputs
Output drive precision	+/- 10 mV
Data line charge period	5 micorseconds (2 kilo-ohms, 75 pF ladder)
Clock speed	45 MHz
Other functions	Fetching horizontally expanded data Fetching horizontally centered data Display and output of vertically expanded data Bit inversion function Asymmetrical drive Chip Enable automatic generation function Bi-directional shift function

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