Hitachi, Ltd. (NYSE:HIT) today announced a liquid crystal controller/driver series lineup with the commercial development of the HD66741 graphic display*1 liquid crystal controller/driver for LCD systems in mobile communication products such as digital cellular phones, PHS phones, and message pagers, supporting a 128x80-dot graphic display, the largest in this class. Sample shipments will begin in October 1998 in Japan.
The HD66741 enables a large-screen LCD panel of up to 128x80 dots to be driven by a single chip, facilitating support for information services such as kanji messages and e-mail, and WWW contents. COG*2, COF*3, and TCP*4 mounting types are available to meet a variety of user needs.
With the rapid growth of the market for mobile communication products such as cellular and PHS phones, there is a constant demand for slimmer and lighter products, together with lower cost. And to meet the need for multifunctionality and higher added value, it has also become necessary for the small LCD panels used in these products to provide a large-screen-size graphic display capable of implementing additional functions such as information services that include kanji messages and e-mail, and WWW contents, as well as the conventional phone number display and directory functions.
Typical single-chip graphic LCD controller/drivers in this class have previously supported a vertical display size of around 65 dots. However, this display size allows the display of only five rows of 12x13-dot kanji characters, insufficient to handle new information services such as kanji message communication and e-mail.
In response to this problem, Hitachi has developed the HD66741 graphic LCD controller/driver, which enables the display size to be extended vertically (in which direction the mounting area is comparatively less restricted due to the set construction), allowing the simultaneous display of a large amount of information on a 128x80-dot screen. This makes it possible to display up to 60 characters (6 rows of 10 characters) using a 12x13-dot kanji font, or 84 characters (7 rows of 12 characters) using a 10x11-dot compact kanji font, enabling new information services such as kanji messaging and e-mail, and WWW contents, to be offered.
The HD66741 offers the largest screen display size of the series, at 128x80 dots. Generally speaking, increasing the liquid crystal screen size to the 128x80-dot class incurs such side effects as a higher LCD drive voltage, lower display quality, and increased current dissipation, but the HD66741 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 of up to 5 times the system supply voltage. This enables a drive voltage of approximately 15 V to be obtained in a 3 V 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 been kept low. Also, to reduce crosstalk noise generated on the LCD screen, the HD66741 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. Use of this partial display function enables the liquid crystal drive duty and liquid crystal drive voltage to be lowered and current dissipation to be greatly reduced by displaying pictograms, the time, etc., on a portable phone, for instance, only during standby periods. For example, total power consumption for full-screen display is 420 
W (at 3 V operation), but only 210 W (at 3 V operation) when drive is selected for only part of the display area with the partial display drive function. This enables power consumption in standby mode to be cut by approximately 50%, greatly extending battery life.
In addition, to support a lower system power supply voltage, a voltage stepped up by a factor of up to 5 can be generated using a 1.8 V single power supply. With full display on the entire screen at a power supply voltage of 1.8 V, total power consumption is 110 W, approximately one fourth the power consumption in 3 V operation.
The HD66741 includes a high-speed synchronous serial interface for interfacing to a microcomputer, and a 68 or 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 fast data transfer to be achieved even over a serial interface.
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 heat seal. 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 lineup in the future, based on the HD66741, to provide products supporting even larger display sizes and products supporting gray-scale display.
| 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. |
| 2. |
COG (Chip On Glass): A mounting method in which a chip with gold bumps isdirectly mounted face-down on the LCD glass. |
| 3. |
COF (Chip On Film): A mounting method in which a chip with gold bumps is directly mounted face-down on a flexible film substrate. |
| 4. |
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, bidirectional pagers, kanji/Chinese-language pagers
Handheld GPS terminals, handheld POS terminals, electronic wallets, etc.
Prices in Japan
| Product Code |
Display Size |
Shipment Form |
Mounting Form |
Sample Price (Yen) |
| HD66741BP |
128x80 dots |
Chip with gold bumps |
COG,COF |
600 |
| HD66741TB0 |
128x80 dots |
Bent-lead TCP |
TCP |
850 |
Specifications
| Item |
Specifications |
| Display size |
128x80-dot graphic display |
| Display functions |
-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 |
| Partial display functions |
-Switchable to low-duty/low-voltage liquid crystal display (partial display function)
-Partial display of screen center only (centering display function)
-Partial display of top and bottom of screen only |
| 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 |
3X to 5X output (programmable) |
| Power consumption control functions |
-Sleep mode, standby mode
-Variable liquid crystal drive duty/bias/voltage
-Liquid crystal drive power supply on/off function |
| System interfaces |
-Synchronous serial interface
-68 or 80-type 4-bit bus interface
-68 or 80-type 8-bit bus interface |
| Liquid crystal drive step-up circuit |
On-chip 3X to 5X 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 |
| Operating power supply voltage |
1.8 V to 5.5 V |
| Liquid crystal drive voltage |
4.5 V to 15 V |
Total power consumption
(internal logic block + liquid crystal drive power supply block)
Typ. conditions |
| -Full-display | : 420 W (VCC = 3 V, 5X step-up) |
| : 110 W (VCC = 1.8 V, 5X step-up) |
-Partial display: 210 W (VCC = 3 V, 3X step-up)
-No display (standby): 3 W (VCC = 3 V) |
| Shipment forms |
-Chip with gold bumps (for COG or COF mounting)
-Bent-lead TCP |
WRITTEN BY Secretary's Office
All Rights Reserved,
Copyright (C) 1998, Hitachi, Ltd.
