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  • 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 from 0.1-0.01g.

    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 100g.

    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 mass production.

    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 is concerned.

    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,
    excluding phones for packet communications.
    The blue line indicates the lightest products.
    The products will be divided into two categories after 2000:
    conventional stick-type and wristwatch-type in pursuing transportability.

    (return to news)

    (Nikkei Electronics)


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    Updated: Fri Aug 28 18:37:43 1998 PDT