For Immediate Release
December 5, 1997
NTT Takes A Great Leap Toward a Watch-sized PHS
(Background)To cope with the trend toward miniaturization of info-communications equipment, Nippon Telegraph and Telephone Corporation (NTT) has begun research and development of "wearable communications tools," communications devices that can be used easily without paying special attention to carrying them around and other complications.
The company succeeded last year in developing a prototype wrist-watch-sized PHS (personal handy phone system) that uses voice recognition technology to allow a caller to place a call without dialing and respond to incoming calls without groping for a handset in a pocket or handbag. The company has since made a great effort to test and refine the device's component technologies. As a result, NTT has implemented further miniaturization and improvements in performance, such as extending the operating time and allowing direct connectivity to public base stations.
(Features)
1. Low power-consumption LSI
NTT has developed a low power-consumption LSI for voice recognition and howling suppression. Consisting of an MT-CMOS* device, the LSI incorporates two transistors with high and low threshold values. The transistor with the higher threshold is used as a barrier against current leaks during circuit idling times. The transistor with the lower threshold is used during normal operation, thereby substantially reducing power consumption of the device as a whole. This innovation is the key technology that allows for voice dialing and small-sized batteries.
2. High energy-density lithium-ion battery and micro-antenna
A high energy-density lithium-ion battery and a miniaturized antenna are housed neatly inside the unit. The built-in miniature battery, in particular, allows for a low power-consumption circuit design and extended call duration and standby times.
3. Design, features, etc.
The new watch-sized PHS is design so that it can perform all its major functions with just four buttons. The voice-dial function can make a telephone connection with the person the caller wants to talk to by entering the number in the memory in advance and simply saying his or her name or by saying the telephone number.
The voice recognition feature allows for two registration methods; one, by entering the name of the party the caller wants to talk to based on the Japanese kana syllabary by pressing the buttons. The other method is to record the destination party's name in the caller's own voice. This means that the former works only in Japanese, while the latter is available in any language.
The caller can also dial with a pushbutton if his surroundings are noisy or if he wants to avoid being overheard by others.
(Future Prospects)
NTT is determined to continue with research and development of terminal equipment with the aim of implementing the concept of "wearable communications tools" through the further evaluation of its newly developed watch-sized PHS. The company plans to further study the applicability of the discrete technologies embodied in the new product to other types of terminals.
(Terminology)
* MT-CMOS (Multi-Threshold Complementary Metal-Oxide Semiconductor) device: A device with multiple transistors with different threshold voltages designed into a single silicon chip.
CMOS device: A complementary metal-oxide semiconductor device. A low power-consumption device that is the fundamental unit of today's LSIs.
