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Mobile Computing


FSTJ 1998-09 Cover Image

1998-09(Vol.34, No.1)



1998-9(Vol.34, No.1) Contents

1. Preface (51 KB)
---[Tadayasu Sugita, Group President Personal Systems Business Group. ]
2. Technology Review of Mobile Computing (277 KB)
Mobile computing is becoming popular all over the world. Especially, notebook PCs are playing an important role in mobile computing. Fujitsu has been focusing on the importance of mobile computing and has been developing new technologies for downsizing, power management, and communication. These technologies have been applied to the latest notebook PCs and to a mobile information tool called INTERTop. This paper looks at the development history of Fujitsu's mobile computing products, the features of the latest models, and the technologies required in mobile computing. Then, we describe the current trends in Fujitsu's technology development. Finally, we describe the important technology of simulation by giving an example of transmission waveform simulation technology on a printed-circuit board (PCB). This technology is one of the key elements that enabled us to achieve the high graphic performance of the FMV-BIBLO 6266NA (called Lifebook 990Tx2 in North America and Europe) released in April 1998. ---[Seiichi Saito ]
3. Packaging and Mechanical Technologies for Mobile Notebook PCs (199 KB)
In recent years, increases in MPU speeds have brought dramatic increase in the performance and functionality of notebook PCs. For mobile notebook PCs, there have also been reductions in size, weight, and thickness. However, mobile notebook PCs must still be easy to use and reliable. We have developed techniques for achieving the following regarding packaging and mechanical technologies and implemented them for mobile notebook PCs now on the market: - Thinner LCD, keyboard, and other devices - Higher mounting densities to enable reductions in the size of PC boards - Heat dissipation without a fan - Protection of built-in hard disk from shock - Thinner, more rigid cabinet walls This paper describes the features of our mobile notebook PCs, the FMV BIBLO NP Series and NC Series, and explains the technologies we developed to address the above issues. Since the circuit scale and the heat generated by mobile notebook PCs are likely to continue to increase with performance and functionality being higher, yet the demand is for further reductions in size, weight, and body thickness. To simultaneously achieve these tougher, conflicting demands, we will continue to develop new packaging and mechanical technologies. ---[Kazuhiro Igarashi ]
4. INTERTop (105 KB)
Interest in mobile information equipment has surged in recent years. This report introduces the INTERTop portable information equipment that was developed to satisfy this demand. INTERTop is mobile information equipment with open architecture hardware. It includes PIM and an editing function, and is easily portable. Specifically, AT compatible architecture is used with the MS-DOS environment to improve response. The maximum weight is set at 750 g. This report explains the process of achieving these design targets, the ingenuity employed and future potential of the equipment. ---[Yasuyuki Fukuda ]
5. INTERTop WORLD Services-Official Homepage for New Portable Information Tool "INTERTop" (275 KB)
Keeping pace with the rapid progress of mobile computing, Fujitsu has released a new portable information tool called "INTERTop". One of the key concepts of INTERTop is to allow users to obtain on-line support over the Internet. Various departments of the company have combined forces to create a homepage that is specific to INTERTop and is called "INTERTop WORLD". The key services of this homepage provide information for users, enable information to be exchanged among users, and allow software to be downloaded. Also, various homepage articles and the WebCAT server service are provided. We can thus provide improved access and other useful services for users. Therefore, the number of accesses to the homepage is increased. ---[Susumu Yamamoto]
6. Network Applications for Mobile Computing (168 KB)
Mobile computing, which enables real-time remote access to corporate networks from a notebook computer, is now being spotlighted as notebook computers become smaller and more complex, and ISDN, wireless networks, and cellular phones become more popular. Unlike conventional networks, many problems encountered when constructing mobile computing environments affect mobile computing users and network administrators. This paper discusses these problems and introduces three communications software products to help users overcome them. ---[Akiyoshi Ochi, Toru Atsumi, Keiji Michine ]
7. Third Generation Mobile Radio Systems(IMT-2000) Using Wideband CDMA Technology and Interference Canceller for Its Base Station (110 KB)
This paper introduces the IMT-2000 third generation mobile radio system, which is expected to become the new worldwide infrastructure for advanced mobile computing. This paper also introduces the multi-stage parallel interference canceller (MPIC) which has been developed for the IMT-2000 base station. MPIC is a powerful technique for enhancing the uplink channel capacity. Direct sequence code division multiple access (DS-CDMA) is one of the most promising radio access technologies for IMT-2000 because of its capability of flexible multi-rate transmission and its high spectrum efficiency. However, the channel capacity of a DS-CDMA system is restricted by co-channel interference due to imperfect orthogonality between channels. We confirmed by computer simulation that applying our proposed 2-stage MPIC to a DS-CDMA base station increases the cell capacity on a multi-path fading channel to about 2.2 times that of a conventional receiver under the same conditions. ---[Yoshinori Tanaka, Hiroyuki Seki]
8. Design Development of Portable Information Equipment (409 KB)
As the use of computers in our daily lives becomes more widespread, there is a growing need for portable machines that can be used anytime, anywhere. Rapid progress in electrical technology has led to networking, downsizing, and dense mounting technologies that have enabled various portable information devices, such as notebook PCs, to enter practical use. Conventionally, the design development of portable information equipment focused on the useability and the cosmetic design factors such as form and color, based on the product specifications mainly affected by technology trends. However, since there is a wide range of fully-mobile, compact portable information products, there is no de facto standard. Therefore, the design development must be geared to the users' needs and way of use, purpose, and situation, and the results must be fed back to the product specifications. This paper explains the fundamental process of industrial design development of portable information equipment by studying the style of use. A new portable information unit called "INTERTop", which was designed using this design development process, is taken as an example. ---[Yoshihiro Ueda]
9. Power Management Technology (243 KB)
Fujitsu has developed three power control LSI chips for power management in power circuits to increase the operating time of battery-driven notebook personal computers. The first LSI chip is the MB3841 power management switch that stops supplying power to non-operating sections of the device. The second LSI chip is the MB3828 DC-DC control circuit that efficiently converts the battery voltage to voltage required by the device. This circuit has been developed for the Pentium CPU to improve performance by about 5 percent over conventional circuits. The third LSI chip is the MB3814 DC-DC control circuit for the charger of the lithium ion rechargeable battery. This circuit enables simultaneous charging and can charge multiple lithium ion rechargeable batteries concurrently, thus reducing recharging time by half. The MB3814 also implements differential charging in which power consumption of a personal computer is measured and the battery recharging current is controlled dynamically, which reduces the charging time for rechargeable batteries during operation of the personal computer. ---[Hidekiyo Ozawa, Seiya Kitagawa ]
10. Low-cost Flip Chip Technology for Organic Substrates (205 KB)
This paper introduces a flip chip technology that is used on various kinds of substrates (glass-epoxy, flexible printed circuit board, and MCM-L/D). In this technology, Au bumps are formed on the chip I/O pads by wire bonding and the bumps are pressed onto the substrate pads. The chip is bonded and encapsulated with a thermosetting adhesive, and conductive paste improves the mechanical and electrical connection between the Au bumps and the substrate in order to increase the connection reliability. To apply this technology to different types of substrates, we investigated the deformation characteristics of the substrate pad and the adhesive strength and insulation of the adhesive for encapsulation. This technology has been applied to some practical products and reduces the mounting areas of LSI to 1/10 or less that of LSI that use the existing SMD package approach. ---[Shunji Baba ]
11. Fan-less Cooling Technology for Notebook Computers (156 KB)
Cooling technologies are becoming critical for handling increased heat output in portable computers. This is because the increased heat output of components (elements and modules) used in the latest notebook computers and the miniaturization of cabinets has led to high internal temperatures in equipment and the intensification of partial heat density. The situation has almost reached the point where MPU performance may have to be limited due to higher temperatures, especially for devices with small cabinets, such as sub-notebook computers. This paper extracts a technological problem necessary for achieving the fan-less cooling of notebook computers, and verified the cooling structure and method of solution. The result of thermal fluid simulation on our notebook computers (which incorporate new cooling technology) and measurement values were found to correspond well. ---[Masumi Suzuki, Minoru Hirano]
12. Hybrid Housing for Notebook Computers (135 KB)
Fujitsu has developed a new type of housing for notebook computers. It is a hybrid housing composed of resin and metal which provides a combination of structural strength, efficient heat dissipation, and light weight. This hybrid housing is manufactured by adapting an in-mold method in which resin is bonded to an aluminum plate inside a metallic mold with the aid of an adhesive. At first, we checked that the hybrid housing has the high heat dissipation characteristics required for sub-notebook PCs by using thermal simulation. We investigated the relationship between the aluminum/resin ratio and heat dissipation characteristics of the hybrid housing model. We found that the use of aluminum on the bottom (which must be strong and have a high heat dissipation) and the use of resin on the side (which must have good moldability for forming complex shapes) provided the best balance between weight and cooling performance. In the next step, we conducted experiments to find the following: (1) an adhesive suitable for bonding aluminum with resin inside a metallic mold, (2) a resin that minimizes warpage in the housing caused by the different thermal expansion coefficients of its two materials, and (3) a molding process suitable for mass production. Compared to a conventional resin housing, the hybrid housing we developed resulted in a reduction of component temperature in a sub-notebook PC of from 5℃ to about 10℃ and a 20% weight reduction. This hybrid housing was applied to Fujitsu's sub-notebook PC, the FMV-BIBLO NC. ---[Kota Nishii, Koichi Kimura, Motonobu Kawarada ]
13. LCD Technology (338 KB)
This paper looks at the various factors that affect the display quality of liquid crystal displays (LCDs) and outlines a new standard we have designed for the evaluation of LCD display quality. Also, this paper looks at the increasingly important electromagnetic radiation interference (EMI) from LCDs and how it can be reduced. ---[Akio Sotokawa, Osamu Ishibashi ]
14.Small, Low-profile Keyboard That Does Not Impair Operability (96 KB)
This paper introduces a method of miniaturizing a keyboard while maintaining its operability. Two techniques have been developed. The first is a new gear link mechanism for the key switches which results in a keyboard that is approximately 40% thinner with no decrease in the stroke distance. The second technique involves reducing the vertical key spacing while maintaining the horizontal key spacing at 19.05 mm. Subjects having little experience with conventional keyboards preferred 17.05 mm and 15.05 mm spacings over a 19.05 mm spacing. ---[Goro Watanabe, Tamotsu Koike, Hideyuki Motoyama]
15.Secure PC Card (142 KB)
The mobile terminal is expected to become an indispensable tool for business, and the security of data held on these devices will become an important problem. This paper introduces the Secure PC card, which is a user-friendly, high-speed file encryption tool for mobile security that can be automatically combined with application software and provides user authentication for control of access to encrypted files. ---[Naoya Torii, Takayuki Hasebe, Seigou Kotani ]
16. Mobile Image Scanner (186 KB)
The progressive downsizing of notebook personal computers and the spread of communication tools such as portable phones, electronic mail, and the Internet have accelerated the mobile use of notebook personal computers. To meet the demand for clipping articles from newspapers and magazines outside the home and office and for collecting information from a library, Fujitsu has developed a high-performance mobile image scanner, named "Pen Scanner", which is small, lightweight, and portable. ---[Fumitaka Abe, Tsutomu Oshima, Shigeru Fujii ]

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