Fujitsu Reveals Inside of Waterproof High-end Handset

Nov 21, 2008
Takeyoshi Yamada, Nikkei Electronics
The F-01A immersed in water
The F-01A immersed in water
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Fujitsu Ltd revealed the inside of the "F-01A," a mobile phone for NTT DoCoMo Inc's mobile service, at a press meeting in Tokyo Nov 19, 2008. The handset was released on the same day.

The F-01A is one of the "docomo PRIME series" mobile phones, the high-end models of the winter 2008 handsets marketed by NTT DoCoMo (See related article). It features a 3.2-inch 864 x 480-pixel LCD touch panel, which is equipped with a biaxial hinge and can be turned around for displaying 1seg broadcasts.

Supporting GSM, GPS, Bluetooth, etc, the handset is a so-called "all-inclusive" model. On top of that, it has a waterproof function that complies with IPX5/IPX7 standards. Though Fujitsu launched several water-resistant handsets in the past, this is the first time that the company has applied the function to a high-end model, it said.

It is not easy to add a waterproof function to high-performance mobile phones: It will increase the amount of internal wiring because those handsets have many capabilities.

The F-01A has a control circuit for the LCD panel, ICs for GPS and Bluetooth capabilities, and other components mounted on the board located on the side of the LCD panel. And there is an increased number of lines connected from the main board, which is attached to the keyboard side of the chassis, through the hinge.

This time, because of the adoption of the biaxial hinge, Fujitsu had to use thin coaxial cables. The company said it was not easy to combine the biaxial hinge and coaxial cables while ensuring sufficient waterproof property.

The company also provided a twist on the fingerprint sensor, which is mounted on the back of the keyboard side of the chassis. In the past, a bare sensor chip was formed on a flexible substrate. This time, however, a reversed chip was mounted, and a fingerprint is recognized from the side of the flexible substrate. In addition, the sensor chip was fixed with resin to enhance its waterproof property.

To achieve water resistance and slimness at the same time, the F-01A employs a structure in which the panel and the rear cover of the LCD panel side of the chassis are attached to each side of a frame by using double-coated tape. This method has been adopted for some of Fujitsu's previous handsets including non-waterproof slim models. However, the company emphasized that it has know-how to stably produce waterproof handsets with the same quality so as to avoid the possibility of water exposure, it said.

The internal structure of the F-01A
The internal structure of the F-01A
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An FPC antenna for 1seg reception is attached on the lower part of the main board.
An FPC antenna for 1seg reception is attached on the lower part of the main board.
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The biaxial hinge through which thin coaxial cables pass features waterproof property.
The biaxial hinge through which thin coaxial cables pass features waterproof property.
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A board on the side of the LCD panel. It is mounted with a control circuit for the LCD panel and circuits for GPS and Bluetooth capabilities. A built-in antenna and an IC for Bluetooth capability are seen on the upper right part of the board, and a built-in antenna for GPS capability is seen on the upper left part of the board. An IC for GPS is located to the left of the center.
A board on the side of the LCD panel. It is mounted with a control circuit for the LCD panel and circuits for GPS and Bluetooth capabilities. A built-in antenna and an IC for Bluetooth capability are seen on the upper right part of the board, and a built-in antenna for GPS capability is seen on the upper left part of the board. An IC for GPS is located to the left of the center.
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An antenna for Felica and a speaker
An antenna for Felica and a speaker
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The LCD panel is attached to a frame with double-coated tape.
The LCD panel is attached to a frame with double-coated tape.
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The chassis on the keyboard side is made water resistant by using rubber packings in joining areas.
The chassis on the keyboard side is made water resistant by using rubber packings in joining areas.
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