Space saving mobile device

Details Space saving mobile device Space saving mobile device

1999-10-26

2001-10-16

Picard, Leo P. (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electrical power distribution systems and devices

C361S689000, C361S727000, C312S223200, C429S054000

Reexamination Certificate

active

06304430

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to making the structure of mobile communication devices thinner.
BACKGROUND OF THE INVENTION
There are on the market a great number of various small hand-held mobile stations in which a battery can be used as a power supply. Previously, it was used mainly Ni—Cd (nickel-cadmium) batteries which were quite big and heavy, compared with their capacity. Lately they are being replaced by Ni—MH (nickel-metal hybrid) batteries and Li—Ion (lithium-ion) batteries, the capacity of which, as to size and weight, is better than that of Ni—Cd batteries. Simultaneously, the development of semiconductor technology has resulted in more compact mobile stations with lower power consumption, and it has been possible to further reduce the size of the batteries used in them.
As the thickness of the batteries used in mobile communication devices and other corresponding small devices has been reduced at its lowest to just a few millimetres, even the space required by their casing has changed from an insignificant factor to a more and more important element in regard with the size of a battery-operated device. In the first stage the thickness of battery walls could be reduced due to the reduced need of mechanical support because of the batteries being lighter, out of economic reasons, but in the newest and smallest devices it has been possible to choose even new materials and advanced manufacturing processes in order to minimize the size of the final product. In patent application publication EP 795 968 there is provided a solution for making the battery walls thinner, in which solution two of the plastic walls normally enveloping the battery cells are manufactured from thin steel foil. A construction made using two different materials is, however, slightly problematic in regard to the production technology and also in regard to the recycling at the end of the life span of the product. Additionally, if the metal surface remains visible on the outside of the product, its looks may differ from the otherwise plastic case of the product in an embarrassing way.
Thanks to the developments in battery and semiconductor technologies it has been possible to reduce the size of battery operated mobile stations without compromising the operating times of the devices. In spite of that it is desired to manufacture the future mobile stations even smaller and lighter, because they are intended to be continuously carried by their users. Of these devices particularly problematic in regard to the use of space are two-part folding devices of the PDA (Personal Digital Assistant) type, such as Nokia Communicator. It is difficult to reduce the thickness of such a device integrating the functions of a PDA and a mobile station, because inside the covers of a folded device there must be room for at least one, but preferably two displays, a keyboard comprising preferably a complete set of characters, the electronics of a mobile station and that of a PDA, and a battery. Yet, the keyboard should be large enough to be good to use and that in order to present the purposes of the keys the corresponding symbols can be printed in connection with the keys. An additional problem in integrating a PDA and a mobile station is that the power consumption normally is higher than that of only one of these and a battery facilitating a sufficient operating time is reasonably big. Naturally the same problem concerns also other hand-held devices, such as PDA-equipment, wireless telephones, mobile and wireless telephones provided with a flap, palmtop computers and laptop computers. It has been attempted make such devices thinner by designing the electronics to take up as little space as possible and by manufacturing the covers of the product as thin as possible whenever it can be done. For example, when using injection moulding technique the minimum thickness of a plastic component is determined by the flowing properties in a mould of the melted plastics, and when the flow-channel inside a mould is small enough, the plastics will no longer fill it and in such a point there will be a hole instead of a thin wall.
Further, devices sold in large series to consumers have to be provided with a marking of their origin and they are often provided with an individual serial number, by using which it is possible to track the manufacturing date and the machine among other things in order to avoid the misuse of warranty service and to make the detection of piratism easier. This has often been implemented by attaching in the case of a device a sticker, in which the required product data has been printed. A sticker is, however, exposed to wear and damage and it is relatively easy to forge into a pirate product.
SUMMARY OF THE INVENTION
Now such a mobile device has been invented, the size of which it has been possible to reduce by manufacturing part of its walls of thin plastic folio fixed to the surrounding thicker walls using for example ultrasonic welding. Particularly, by using the invention it is possible to make thinner such parts which increase the size of a mobile device, and in which the wall remains inside the outer case of the mobile equipment in transport position. Examples of such parts of a mobile device are the outer skin of the case of a mobile station and the walls of the battery of a mobile station, and out of the walls of the case of a mobile station particularly the side wall(s) remaining inside a two- or multi-part mobile station and the inner surfaces ending up against each other in a closed two-part mobile station that may e.g. envelope a display and a keyboard inside a device. The case of the battery of a mobile station can for example be manufactured of injection moulded plastic on five faces and on its sixth face of a thin plastic foil fixed to four side walls e.g. using ultrasonic welding. In that case the thin wall remains protected by the structure of the equipment. Respectively, walls enveloping the keyboard and display can be manufactured of thin plastic foil. The top cover of an unfolding two-part device can also be made of plastic foil and in this it is possible to form so-called membrane keys, in which case the space taken by the keys is clearly reduced and the outer surface of the device is easier to clean because of its smoothness, and dirt, dust and moisture are prevented from penetrating through any gaps in the keyboard. The same technique is also applicable to the lens of the display and to the keyboard plastic, leaving no gaps for dust and water. Additionally, the plastic foil can be manufactured to have a hard-facing, which increases the resistance to wear of the outer surface. Further, the plastic foil is preferably printed to include the required product data, in which case a device carries on its case all required information without a separate sticker. If plastic foil is used in the top cover, graphics can be printed on the inside of the plastic foil, in which case it is achieved good colouring possibilities and resistance to wear.
In another embodiment of the invention the wall of the case of a mobile station and the keyboard are made thinner by manufacturing the wall comprising the keyboard of thin plastic foil. The locations and symbols of the keys are printed in this foil e.g. using laser marking and switching means are grouped below the plastic foil under the marked key positions in order to detect the pressing of a key. In this way it is possible to improve the resistance against dirt and moisture of the keyboard. Such a keyboard requires very little space and is, additionally, neat and easy to clean, because next to the keys there will remain no such areas, which would be difficult to clean.
A mobile device according to the invention, comprising a case limiting a space of a certain shape and form, the case having a wall, is characterized in that
said case comprises a first part and a second part which forms at least a part of the area of said wall,
said first part is made of injection moulded plastic,
said second part is made of plastic foil, and
said second par

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