(Nikkei BP Group)
(No.1 High-Tech News Site in Japanese)
| Competition Heats to Reduce Weight of Cellular Phones
August 31, 1998 (TOKYO) -- Manufacturers of digital cellular phones are
competing fiercely to reduce the weight of their products.
|A 69g digital cellular phone introduced by Kyocera Corp. in July set
the competition on fire again after it had calmed down for the prior
year or so.
Kyocera's competitors are developing new models weighing about 70g as
a first volley or setting their goal as Kyocera's 69g model.
They are expected to debut new models weighing less than 60g by the end
of 1999. Most technologies and components needed for the new models
are already available.
Cellular phones lighter than 50g, however, still are not on the horizon.
The number of parts available to reduce weight decreases with each gram
of the reduction. So the weight must be reduced in fine steps ranging
Cellular Phone Weight Falls Two-Thirds in
Past 5 Years
Personal Digital Cellular (PDC) phones in the country's standard digital
cellular phone system have seen their weight drastically reduced over
the past five years (See chart).
The minimum weight of a cellular phone was 220g in 1993, when Japan's
mobile communications operators started services. It remained at about
160g during 1995-1996. And then in October 1996, the market encountered
competition for weight reduction targeting products weighing less than
The weight remained about 80g, with no remarkable progress from July
1996 through June 1998, when Kyocera marketed the 69g cellular phone,
stoking competition again. The next goal is the realization of cellular
phones weighing less than 60g.
Notwithstanding analysts' comments that the weight reduction has reached
"its limit" or "a thorough level," manufacturers have buckled down to
the activities of reducing the weight, because the lightest cellular
phone always has been in the highest demand.
A marketing official of NTT Mobile Communications Network Inc. (NTT DoCoMo),
Japan's largest mobile communications operator, confirmed that users
are purchasing the lightest cellular phone.
In 1997, Matsushita Communication Industrial Co., Ltd., NEC Corp. and
Fujitsu Ltd., which marketed models weighing about 80g, ranked high
in market share.
Each Structural Element is A Target for Weight Reduction
To realize a 50g-class cellular phone, its structural elements such as
the lithium-ion secondary battery, body unit and external parts, printed
circuit board and display, which account for about 30 percent, 20 percent,
20 percent and 5 percent of the total weight, respectively, must be
scrutinized separately and closely.
That ratio applies to the lightest, stick-type cellular phones. Other
types, such as the folding-type and flip-up cover type, increase the
weight of their body and external parts because of a hinge.
The battery, the heaviest element of a cellular phone, is reducing its
weight thanks to the development in its energy density. Sanyo Electric
Co., Ltd., a major manufacturer of secondary batteries, said that batteries
will become lighter in weight by about 5 percent (about 1g) in 1999
and by about 10 percent through 2000.
The efficiency of the power amplifier that transmits radio waves also
contributes to the weight reduction of the battery. Japan's major semiconductor
makers said efficiency will be improved by more than 10 percent by the
end of 1999.
There is a market trend to reduce the weight of the body unit using a
magnesium alloy in place of plastics.
The dimensions of most cellular phones are around 120 mm (high) x 40
mm (wide) x 20 mm (thick). They do not vary among the models because
the length depends on the physical distance between the ear and mouth
and the width depends on three-line, user-friendly buttons.
But a magnesium alloy can reduce its current thickness of 20 mm, determined
from the strength of the body unit.
The printed circuit board will reduce its weight in 1999 by about 20
percent (about 3g) by reducing its thickness and downsizing parts to
be mounted on it, cellular phone makers said.
For the purpose of downsizing the components, Fujitsu, for example, will
proceed to reduce the area of multi-chip modules (MCMs), and NEC will
use its stacked chip size package (CSP) technology, which stacks microchips
to reduce the area of microchips.
It is expected that replacement of a glass substrate used for protecting
the LCD panel with a plastic film will reduce the weight by about 2g.
Only Kenwood Corp., however, is using the film because of problems with
Opinions Differ on Cellular Phones Lighter than 50g
Although weight reduction in cellular phones is proceeding, manufacturers
disagree about emergence of new products lighter than 50g.
Matsushita Communication Industrial expects that further weight reduction
will be promoted, because downsizing and weight reduction are basic
needs for mobile communications devices. Ryuji Hori, director of Corporate
Engineering Division, is putting his final goal at 0g. Users look to
purchase communications services, not a box, Hori said.
Yasuo Nishiguchi, executive vice president of Kyocera, added that the
lighter weight should be the first priority as far as transportability
Makers without weight-reducing technology might be dismissed from the
market if users continue accepting the lightest cellular phones.
Even if the feature of lightness loses its brightness, cellular phone
makers will be able to beat their competitors in design, brands or user
interfaces. But if they fail to differentiate themselves, it is very
probable that only cut-price competition will follow.
There is a possibility that a microprocessor from ARM Ltd. of the United
Kingdom, the ARM7TDMI, and the Nucleus Plus operating system of Accelerated
Technology Inc. of the United States will become the defacto standards
for digital cellular phones conforming to the Global System for Mobile
Communications (GSM) format of Europe, or the IS-95 and IS-136 formats
of the United States.
Japan's cellular phone makers cannot go against the stream of global
standardization in the industry. Matsushita Communication Industrial
said it is very interested in ARM cores.
Chart: Cellular Phone Weights Are Reduced by Two-Thirds in 5 Years
Data are mainly based on NTT DoCoMo's cellular phones.
The company is Japan's largest mobile communications operator.
Data of cellular phones marketed by IDO Corp. in July 1998 are also shown.
Data are only for cellular phones with an 800MHz band,
phones for packet communications.
The blue line indicates the lightest products.
The products will be divided into two categories after 2000:
stick-type and wristwatch-type in pursuing transportability.
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