Hitachi, Ltd. (NYSE:HIT) today announced the HD66728 graphic liquid crystal controller/driver for liquid crystal display systems in mobile communication products
such as digital portable, PHS, and digital cordless
phones, offering the capability of switching between a
112 x 80-dot graphic display*1 (the largest in this class) and a 10-line/16-digit character display*2 with a single-chip.
Sample shipments will begin in August 1998 in Japan. The HD 66728's ability to handle an 80-dot vertical
screen display enables a large-screen LCD to be incorporated without increasing the horizontal width of the system.
COG*3, COF*4, and TCP*5 mounting types are available to meet the needs of different users.
With the rapid growth of the market for mobile communication products such as portable and PHS phones, there are
constant demands for lower power consumption, greater multifunctionality, reduced size and weight, and lower costs.
And with the increasing multifunctionality and higher added value of the small LCD panels used in these products, it has become necessary to provide a large-screen-size graphic display to implement additional functions such as kanji message communication, e-mail, games, and scheduler facilities, as well as the conventional phone number
display and directory functions.
Typical single-chip graphics LCD controller/drivers in this class have previously supported a display size of 132 dots horizontally by 65 dots vertically. However, since the sets themselves must be small and lightweight in the case of mobile communication products such as portable phones, the products need to be slim in design,
and this has limited the display size that can actually be used by the graphic LCD controller/driver to around
96 x 65 dots. With a 16 x 16-dot kanji font, this display size allows only 24 characters to be displayed (4 lines
x 6 digits), insufficient for acceptable kanji message communication or e-mail.
In response to this problem, Hitachi has developed the HD 66728 graphic LCD controller/driver which enables the display size to be extended vertically (in which direction the mounting area is less restricted due to the set construction), allowing the simultaneous display of a
large amount of information on a 112 x 80-dot screen.
Using a 12 x 13-dot kanji font, up to 54 characters (6 lines x 9 digits) can be displayed within the LCD screen, enabling services such as kanji messaging and e-mail to be offered. Like the 72 x 26-dot graphic display HD66724, 96 x 26-dot HD66725, and 96 x 42-dot HD66726 currently in production, the HD66728 is also capable of displaying standard alphanumeric and kana characters.
As the HD66728 extends the display size vertically, the LCD drive duty is higher. Generally speaking, a higher LCD drive duty is associated with such side effects as a higher LCD drive voltage, lower display quality, and increased current dissipation, but the HD66728 includes features to keep such side effects to a minimum.
For example, to handle the higher drive voltage, a step-up circuit is included that generates an LCD drive voltage
up to 5 times the system supply voltage. This enables a drive voltage of approximately 15V to be obtained in a 3V
system. In addition, since the LCD drive bias ratio is
software-programmable, the bias ratio can be kept low through the use of liquid crystal materials with excellent on/off transient characteristics, thus enabling the LCD drive voltage itself to be reduced.
To prevent a drop in display quality, the drive capacity
of the LCD drive voltage generation op-amp has been increased, and the on-resistance of each driver output has also been
kept low. Also, to reduce crosstalk noise generated on the LCD screen, the HD66728 uses the C-pattern LCD drive method employed in large liquid crystal display systems. With
the C-pattern LCD drive method, the alternation frequencies of illuminated and non-illuminated parts of the LCD are equalized by performing liquid crystal alternating drive for multiple lines at one time, so reducing the contrast fluctuations associated with alternation frequency deviation.
To reduce power consumption, a partial display function is incorporated that allows only part of the screen display area to be driven. Total power consumption for full-screen
display is 420 microwatts (at 3V operation), but only 210
microwatts (at 3V operation) with partial display drive. Use of this partial display function during system standby and waiting periods enables power consumption to be cut by approximately 50%, greatly extending battery life.
The HD66728 includes a synchronous serial interface for interfacing to a microcomputer, and a 68/80-type 8-bit or 4-bit bus interface.
Access to on-chip registers and RAM can be performed by continuous high-speed writing, independently of the internal operating clock frequency, enabling adequately fast data transfer to be achieved even over a serial interface.
In addition, built-in key-scan and port control functions enable the entire operating panel, including the liquid crystal display and key matrix, to be controlled via three serial interfaces. This makes it possible to use fewer parts
and to cut the number of microcomputer I/O ports by more
than 20, for example, resulting in lower system size, weight, power consumption, and costs.
Supported mounting methods are COG mounting, in which the device is directly mounted face-down on the LCD glass, COF mounting, in which the device is mounted face-down on a flexible film substrate, and TCP mounting, in which the device is connected to the
LCD glass via a heatseal. To minimize the mounting glass area in COG mounting, a slim chip shape is used, with a width of only 2.78 mm.
Hitachi plans to expand the product lineup in the future, based on the HD 66728, to provide support for even larger display sizes.
Hitachi, Ltd., headquartered in Tokyo, Japan, is one of
the world's leading global electronics companies, with fiscal 1997 (ending March 31, 1998) consolidated sales of 8,417 billion yen (63.8 billion dollars*). The
company manufactures and markets a wide range of products, including computers, semiconductors, consumer products and power and industrial equipment. For more information on Hitachi, Ltd., please visit Hitachi's Web site at
http://www.hitachi.co.jp.
*At an exchange rate of 132 yen to the dollar.
|
Notes |
1. |
Graphic display: |
|
On-chip bit-mapped display RAM is provided, and the microcomputer can display arbitrary patterns such as kanji and game patterns by rewriting display data dot by dot. |
|
2. |
Character display: |
|
An on-chip character generator that generates font patterns
is provided, and the microcomputer can easily display
kana, alphanumeric, and other characters in the character generator simply by specifying one-byte character codes. |
|
3. |
COG (Chip On Glass): |
|
A mounting method in which a chip with a gold bump is directly mounted face-down on the LCD glass. |
|
4. |
COF (Chip On Film): |
|
A mounting method in which a chip with a 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 systems (PDC, GSM, CDMA, etc.), PHS
- Message pagers
- Simple portable terminals (electronic wallets, GPS
terminals, POS terminals, etc.)
Prices in Japan (For Reference Only)
| Product Code |
Display Size |
Shipment Form |
Mounting Form |
Sample Price (Yen) |
HCD66728BP |
112 x 80 dot |
Chip with gold bump |
COG, COF |
600 |
| HD66728TB0 |
Straight TCP |
TCP |
900 |
[Supplementary Information]
Specifications
| Item |
Specifications |
| Graphic display size |
112 x 80 dots |
| Character display characters |
10 lines x 16 digits (6 x 8-dot font) |
|
Fonts (6 x 8 dots) |
Built-in fixed fonts: 432
User-programmable fonts: 64 |
| Display functions
| Graphics/character superimposed
display |
| Vertical smooth scroll display |
| Screen top/bottom graphic icon display (fixed display) |
| Vertical double-size display
(perpendicular enlarged display
function) |
| Cursor display per display line |
| Blinking mark display support |
| Liquid crystal drive duty |
1/32, 1/40, 1/48, 1/64, 1/72,
1/80 duty (programmable) |
| Liquid crystal drive bias |
1/4 to 1/10 bias (programmable) |
| Liquid crystal drive step-up circuit output |
x3 to x5 output (programmable) |
| Power consumption control |
Sleep mode, standby mode functions |
| Variable liquid crystal drive
duty/bias/voltage |
| Liquid crystal drive power
supply on/off function |
|
System interfaces |
Synchronous serial interface |
| 68/ 80-type 4-bit bus interface |
| 68/80-type 8-bit bus interface |
| Liquid crystal drive step-up circuit |
On-chip x3 to x5 step-up circuit |
| Liquid crystal drive power supply circuit |
On-chip liquid crystal drive
level power supply op-amp |
| On-chip liquid crystal drive
level bleeder resistance |
| On-chip electronic control for
contrast adjustment |
| Key-scan functions |
4 x 8 (32-key) matrix control
Key-scan interrupt generation |
| General output ports |
3 |
| Operating power supply voltage |
1.8V to 5.5V |
| Liquid crystal drive voltage |
5V to 15V |
Total power consumption
(internal logic block + liquid crystal drive power supply block)
VCC = 3V, typ. conditions |
Full-display: 420 microwatts
Partial display: 210 microwatts
No display (standby): 3
microwatts |
| Shipment forms |
Chip with gold bump (COG, COF)
Bent-lead TCP |
WRITTEN BY Secretary's Office
All Rights Reserved,
Copyright (C)
1998, Hitachi, Ltd.
