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News Release

September 7, 1998

Hitachi Releases Single-Chip LCD Controller With On-Chip Bitmap RAM for Use in Portable Information Equipment

- Support for both the large screen size of 160 x 100 dots in a single chip for the first time in the industry and four-level gray scale display or four-color display with reflective color LCD panels -

Hitachi, Ltd.(NYSE:HIT) today announces the release of the HD66421 LCD controller/driver with bitmap RAM*1 provided on a chip. This device is designed for multifunction portable telephones and other portable information equipment, supports the large screen size of 160 x 100 dots, and achieves four-level gray scale display or four-color display on reflective color LCD panels for the first time in the industry. This product can use high speed switching two plain of display, when monochrome display mode. Sample shipments will begin in September 1998 in Japan.

Recently, information and communication infrastructures have been greatly improved and information can be acquired whenever and wherever desired. In this context, a wide range of portable information equipment has appeared on the market. There are now strong desires for LCD displays used in these devices to be enlarged to display even more information and to support graphical displays to improve visual impact. To respond to these needs and to achieve miniaturization and to reduce power consumption required in portable information equipment, single-chip implementations of LCD display systems, and gray scale and color displays in the LCD controller driver circuit are required.

Hitachi is already mass producing the HD66410 LCD controller /driver with on-chip bitmap RAM. This device is designed for use in pagers and other multifunction portable telephone products and can drive a 128 x 33-dot monochrome LCD in a single chip. To further respond to these market needs, Hitachi has developed and is releasing the HD66421.

The HD66421 includes 32k bits of bitmap RAM and an LCD drive power supply circulation chip. At the same time as supporting a 160 x 100dot large screen display in a single chip for the first time in the industry, the HD66421 also achieves monochrome display, four-level gray scale display or four-color display with reflective color LCD panels.

In monochrome display mode, two plain of display can be selected in this mode using internal memory. These two operations are independent of each other, thus one plain can be rewritten while the other plain is displayed. This product can use high speed switching two plain of display, when applications require animated display.

Since the appearance of the displayed gray scale or colors differs depending on the characteristics of the LCD panel used, the HD66421 includes a 32-color palette and allows an arbitrary four colors to be selected for optimal four-color display on the LCD panel used. The HD66421 uses a variable pulse-width scheme to implement the gray scale/color display, and thus achieves four-level/four-color display without flicker or smear. The HD66421 can also drive reflective color LCDs that use the ECB (electrically controlled birefringence)*2 technique to display four colors with the same drive circuit used for monochrome displays. It is also possible to implement 160 x 200-dot displays or 320x 100-dot displays by connecting two chips in a master/slave*3 configuration.

The HD66421 provides several power-saving features. One such feature is a partial display mode. This modeallows only an arbitrary 8 lines of the display to be driven, with the rest of the display turned off. This can be used to reduce power in standby mode. Another power-saving feature is the inclusion of the divider resistor, voltage follower, and electronic potentiometer circuit required for the LCD power-supply circuit. This allows application circuits to be implemented compactly, and the inclusion of the on-chip power-supply circuit can reduce the power consumption of the LCD system as a whole.

The HD66421 is provided in a TCP (tape carrier package) format to support light-weight and compact implementation of LCD display systems. Future developments in this area will include modified and enlarged display sizes and the incorporation of even more of the power-supply system components into the IC itself to further reduce the number of external components required in the power-supply circuit.

Notes*

1.Bitmap RAM: Memory used to store the data bits corresponding to the image to be displayed.

2. ECB (electrically controlled birefringence): Refers to LCD panels that take advantage of the phenomenon thattransmitted light that has been diffracted by liquid crystal molecules appears colored. Multi-color displays can be implemented since the color changes with the strength of the applied electric field. Currently, panels that support 4 or 5 colors have been produced commercially.

3. Master/slave connection: Refers to expanding the display size by using two or more ICs with one operating as the master and the other(s)operating as slave(s).

 

Application Product Examples

  • Multifunction portable telephones
  • Portable information equipment that includes communications functionality
  • Bi-directional pagers

Sample prices in Japan

Catalog No.

Sample Price (Yen)

HD66421TB0

1,200

Features

1. Large-screen drive circuit implemented in a single chip
The HD66421 achieves a 160 x 100-dot display in a single chip. Although the 128 x 33-dot HD66410 currently in volume production can display two lines with eight Japanese kanji characters in 16 x 16 dot kanji character, this new product can display six lines with ten characters.

2. Support for gray-scale or color displays
Since the HD66421 supports arbitrary selection from a palette of 32 gray levels or colors, it supports optimal gray-level display and can drive the reflective color LCDs that require subtle voltage control. Also, the HD66421 uses a variable pulse-width scheme to implement the grayscale/color display, and thus achieves gray scale/color display without flicker or smear.

3. Support for partial displays
As a low-power mode, the HD66421 supports a mode in which only 8 line sat an arbitrary position are displayed. This mode achieves reduced power consumption during standby by operating the LCD drive outputs from only the logic operating power supply, which makes the high voltage used for the LCD drive unnecessary.

Specifications

Item

Specification

Internal RAM capacity

32k bits (160 x 100 x 2)

Number of LCD
drive circuits

Segment outputs

160 outputs

Common outputs

100 outputs

Color/gray-scale display

Simultaneous display of four colors/gray levels from a palette of 32 levels.

CPU interface

8-bit parallel 8086-compatible interface

Display duty

1/8, 1/64, 1/80, 1/100

Display control functions

Display on/off, vertical scroll, blinking, reverse video, partial display

Oscillator circuit

CR oscillator (Only requires an external resistor.)

Power-supply circuit

Bleeder resistor, voltage follower, electronic potentiometer

Power-supply voltage

Vcc

2.2 V to 5.5 V

VLCD

6 V to 18 V

Package

TCP


WRITTEN BY Secretary's Office
All Rights Reserved, Copyright (C) 1998, Hitachi, Ltd.