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
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