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June 10, 1999

Hitachi Releases Four-level grayscale Graphics LCD Controller/Driver for Mobile Communication Products Providing Industry's Largest-Size 128 x 128-Dots Display with One Chip

- On-chip 7X step-up circuit, implementation of simple browser function for digital portable phones -

Hitachi, Ltd. (TSE: 6501) today announced the HD66750/751 LCD controller/drivers for four-
level grayscale graphics display*1, providing drive by single-chip for the industry's largest display 
size of 128 x 128 dots, for LCD displays in mobile communication products such as digital 
portable phones, message pagers, and small PDAs.  Sample shipments will begin on June 10, 1999 
in Japan.

These new products can drive monochrome LCD panels of up to 128 x 128 dots with four-level 
grayscale, enabling them to handle information distribution services, including e-mail and Internet 
WWW contents, on the small LCD panels of mobile communication products.  An on-chip 7X 
step-up circuit enables a low system supply voltage to be used, and the pins for common signals 
among the display output signals are arranged on both sides of the chip in the HD66750 and on 
one side only in the HD66751, offering a choice of models to suit the available mounting space.

Recently in the field of mobile communication products, there is a constant demand for thinner and 
lighter designs together with lower costs.  Meanwhile, digital portable phones are becoming 
widely used not only as voice terminals, but also as data communication terminals handling 
information distribution services such as e-mail and WWW contents via the Internet.  There is 
consequently a need for the small LCD panels on these products to be able to handle graphics 
display with level grayscale, such as GIF*2, in addition to conventional text-based displays such as 
phone numbers and kanji messages.  Achieving this capability also requires a larger screen size.

In the mobile communication product field, a conventional graphics LCD controller/driver 
supports a monochrome display size of around 128 x 80 dots with one chip.  However, as this 
display size can only accommodate 60 characters in a 12 x 12-dot kanji font, two or more chips 
are needed for large-screen displays capable of handling kanji message communication, e-mail, and 
similar information distribution services.

To provide a better solution, Hitachi developed the HD66750/751 graphics LCD 
controller/drivers, providing single-chip drive of a large 128 x 128-dot screen (with the display 
area extended vertically to exploit the mounting area characteristics of portable phones and similar 
products), and capable of displaying a greater amount of information at one time.  The HD66750 
and HD66751 can display up to 100 characters (10 lines x 10 characters) when using a 12 x 12-
dot kanji font, and up to 132 characters (11 lines x 12 characters) when using a 10 x 11-dot 
compact kanji font, enabling them to handle new information distribution services such as e-mail 
and WWW contents.

In addition, use of the four-level grayscale display facility enables a wide variety of graphics 
displays to be implemented, and a bit operation function is also provided for smooth processing of 
large amounts of data to support larger screen sizes and level grayscale data, making it possible to 
greatly reduce the graphics processing load on the microcomputer software.

Larger screen sizes generally mean a higher LCD drive voltage, lower display quality, and 
increased power consumption, but these new products keep these effects to a minimum.  
Regarding the rise in LCD drive voltage, the on-chip step-up circuit can generate an LCD drive 
voltage up to seven times that of the power supply voltage, enabling an LCD drive voltage of 
approximately 17 V to be attained from a 2.5 V power supply.

The LCD drive voltage generation op-amp and step-up circuit drive current can be controlled by 
software, allowing power consumption to be minimized while maintaining display quality.

The LCD drive method used is the C-pattern LCD drive method used in large LCD display 
systems.   With this method, alternating drive is performed in units of several LCD lines, and the 
alternation frequencies of the illuminated and non-illuminated parts of the LCD display are made 
uniform, reducing the crosstalk noise due to contrast fluctuations associated with alternation 
frequency deviation.

As a power reduction measure, a partial display function is provided that enables only a part of the 
screen display area to be driven.  By providing only a limited display, such as a pictogram or time 
indication, when a portable phone is in standby mode, it is possible to reduce the LCD drive 
duty*3 and LCD drive voltage, and greatly decrease power consumpion.  For example, power 
consumpion is 600 uW (at 3 V operation) during full-screen display but only 210 uW (at 3 V 
operation) when the partial display function is used to provide selective drive for only part of the 
display area.  This enables power consumption to be cut by approximately two-thirds while the 
phone is on standby, greatly extending battery drive.

Supported mounting methods are COF*4 mounting, in which the device is mounted face-down on 
a flexible film substrate, and TCP*5 mounting, in which the device is directly connected to the 
LCD glass.  The HD66750, with the 128 common drivers output from the right and left sides of 
the chip (64 from each side), is suitable for TCP or COF mounting.  With the HD66751, on the 
other hand, in which all 128 common drivers are output from the left side of the chip, the use of 
COF mounting enables a larger effective display area to be secured on the LCD screen.

Hitachi plans to expand the product lineup in the future with the development of models capable 
of handling even larger screen sizes.

Notes:	1.Four-level grayscale graphics display: Bit-mapped display RAM is incorporated, 
	and graphics are implemented by controlling four-level grayscale independently for 
	each dot.
	2. GIF (Graphics Interchange Format): A graphical data format frequently used for 
	WWW images on the Internet.
	3. LCD drive duty: Ratio of the single-line drive time of an LCD screen to the time 
        for one frame of which the line is a part.
	4. COF (Chip On Film): A mounting method in which a die with gold bump is directly 
        mounted face-down on a flexible film substrate.
	5. TCP (Tape Carrier Package): A package in which the chip is mounted on a thin-
        film tape.  Ultra-thin type mounting is possible.

< Typical Applications >
Digital cellular phones (PDC, GSM, CDMA, etc.)
Message pagers, two-way pagers
Small PDAs, handheld GPS terminals, handheld POS terminals, etc.

< Prices in Japan (For Reference Only) >
Product Code	Shipment Form	Common Drivers		Sample Price (Yen)
HCD66750BP	Die with gold	On both left and right	700        
		bump		sides                                             
HCD66751BP	Die with gold	On one side		700
		bump							  	
HD66750TB0	Bending TCP	On both left and right	950
				sides                                     


WRITTEN BY Secretary's Office
All Rights Reserved, Copyright (C) 1999, Hitachi, Ltd.