The present invention relates to a RF unit and a portable communication device for enabling using a rigid coaxial conductor in a multi-part portable communication device.

One trend within the design of portable communication devices, such as mobile phones is the so called clam shell type of phone. Another type of phone is the jack-knife type of phone and a third is the flip-type of phone. These types of phone, all being of non-stick type, are composed of two major parts, often one upper part and one lower part.

The clam-shell type of phone has the advantage of enabling fitting a large display together with a fairly large keyboard within small outer dimensions.

Due to the nature of the design and the need for aspiration for optimal performance, it is common practise to position electronics in the lower part of the phone and and an antenna in the upper part. For these reasons the radio frequency (RF) signals need to be transferred between the two parts.

The RF signals are usually transferred between the two parts by leading the signals through conducting flexible coaxial cable that is positioned through a hinging region connecting the lower and the upper parts.

In the american patent document US 5,561,437, a two position fold-over dipole antenna is disclosed which is thus used in a two-part type of mobile phone. This antenna has a first part in a flap portion of the mobile phone and a second portion in a main part of the mobile phone. These portions are connected to one another by a flex strip conductor that is postioned in a hinge region between the first and the second part.

The technique as disclosed above thus uses a flexible strip conductor.

In another type of state of the art mobile phone coaxial cables are used to allow RF signals to be transferred from one part of two-part mobile phone to the other part of the phone. Such phones having two parts that are movable in relation to one another and in which the parts are rotatable in relation to one another the coaxial cable in the hinge region is problematic.

In order to allow opening and closing of a two part phone the coaxial cable have to allow bending and/or twisting motions. These cables are therefore flexible in order to allow such motions.

There is however a problem with using flexible coaxial cables and that is that the outer diameter of such cables needs to be small in order not to provide to high forces counteracting an opening or a closing motion applied by the user when operating the mobile phone. A small enough diameter of the coaxial cable, however, increases the radiofrequency losses in the cable.

Another drawback of using a flexible coaxial cable is that it is difficult to connect the shield of the cable to the electrical ground in an appropriate way. If poorly grounded the RF signal can generate interference in other sensitive regions of the phone. Moreover, the antenna radiation performance may also be difficult to optimise when the coaxial cable is poorly grounded.

A disadvantage with the current technology is the difficulty to fixate a flexible cable at the hinge region. The cable can get squeezed easily between the mechanical detailed parts, which exerts a counteracting force, as mentioned above and which also may reduce the RF signal transfer performance of the cable through the hinge region.

It is therefore desired to circumvent the above mentioned drawbacks of using a flexible conductor for the transfer of the RF signals in a two-part mobile phone.

The invention is directed towards providing a RF unit and a portable communication device, comprising multiple rigid parts for enabling use within a multi-part portable communication device.

This is achieved by providing a semi-rigid radio communication unit for enabling RF signals transfer through said unit.

One object of the present invention is to provide a radio communication unit enabling motion between connection sites of said radio communication unit.

According to one aspect of this invention, this object is achieved by a radio communication unit comprising a first rigid arm, having a first and a second end, a connecting unit, having at least two rigid parts, one of which is fitted with a first connection site, and another with a second connection site, wherein at least two of said parts are rotatably mounted, in relation to one another, around an axis of rotation through said connection unit, wherein the first end of the first arm is connected to the first connection site of the connection unit, and wherein the first arm includes an outer conductor and an inner conductor, coaxially arranged and electrically insulated in relation to one another, for enabling transfer of radio-frequency signals between the first rigid arm and the second connection site of the connection unit, via the rotatable connection unit.

A second aspect of the present invention is directed towards a radio communication unit including the features of the first aspect, further including a second arm, having a first and a second end, wherein the first end of the second arm is connected to the second connection site of the connection unit, and wherein the second arm includes an outer conductor and an inner conductor, coaxially arranged and electrically insulated in relation to one another.

A third aspect of the present invention is directed towards a radio communication unit including the features of the second aspect, wherein the second arm is a rigid arm.

A fourth aspect of the present invention is directed towards a radio communication unit including the features of the second aspect, wherein at least one of said first and second arms are elongated.

Another object of the present invention is to provide a portable communication device containing a radio communication unit, enabling motion between connection sites of said radio communication unit.

According to a fifth aspect of this invention, this object is achieved by a portable communication device for enabling radio communication transfer, including a radio communication unit containing a first rigid arm having an outer conductor and an inner conductor, coaxially arranged and electrically insulated in relation to one another, and a connection unit, said portable communication device comprising an upper part, containing the first rigid arm having a first and a second end, a lower part, being connected to the upper part via a rotation region, allowing rotation of the upper part in relation to the lower part, around an axis of rotation, wherein said rotation region contains the connection unit having at least two rigid parts, of which one is fitted with a first connection site and another with a second connection site, wherein the first end of the first arm is connected to the first connection site, and wherein at least two of the at least two rigid parts are rotatably arranged around the axis of rotation to allow rotation in relation to one another, such that radio-frequency signals can be transferred between the first rigid arm in the upper part and the second connection site of the connection unit.

A sixth aspect of the present invention is directed towards a portable communication device including the features of the fifth aspect, further including a second arm positioned in the lower part of the device, and having a first and a second end, wherein the first end of the second arm is connected to the second connection site of the connection unit, and wherein the second arm includes an outer conductor and an inner conductor, coaxially arranged and electrically insulated in relation to one another.

A seventh aspect of the present invention is directed towards a portable communication device including the features of the fifth aspect, wherein the second arm is a rigid arm.

An eighth aspect of the present invention is directed towards a portable communication device including the features of the fifth aspect, wherein the rotational region is a hinging region.

A ninth aspect of the present invention is directed towards a portable communication device including the features of the fifth aspect, wherein the device is a mobile phone.

By using a radio communication unit according to the present invention, said radio communication unit having a coaxial connection unit including parts that are rotatable in relation to one another, folding of said radio communication unit is enabled.

Another advantage by using a radio communication unit, according to the present invention, is that is has better RF performance relative flexible RF cables. The radio communication unit obtains a lower insertion loss, enhanced shielding and better possibilities for grounding, compared to flexible cables.

Yet another advantage is that the RF performance may be further increased due to the fact that a larger diameter may be used when using a rigid coaxial cable as compared to when using a flexible cable.

It is furthemore advantageous that the shield of a rigid arm can be soldered directly to a printed wire board (PWB) for instance within the different housing parts of a mobile phone, giving better antenna performance and better interference immunity, that minimised interference between sensitive electrical/electronical parts in the portable communication device.

Also, by fixating a rigid arm by soldering it to a PWB and by connecting it to a rotatable radio communication unit, the rigid arm will be fixed in the rotation area of the portable communication device, reducing potential problems of conductors being squeezed, reducing the performance of the portable communication device.

The present invention will now be described in more detail in relation to the enclosed drawings, in which:

• fig. 1 shows a radio communication unit, according to a preferred embodiment of the present invention,
• fig. 2 is a side view of a cross-section of a portable communication device in a folded state, according to a preferred embodiment of the present invention, and
• fig. 3 is a side view of a cross-section of a portable communication device in an un-folded state, according to a preferred embodiment of the present invention.

The invention thus relates to providing a RF signal conducting unit and a portable communication device, comprising multiple rigid parts that can move relative to one another, for enabling transferring RF signals.

Portable communication devices having at least an upper part and a lower part that can be moved relative another, such as a clam-shell type of mobile phone, typically contain a RF cable between RF circuitry in the lower part of the mobile phone and an antenna in the upper part of the phone. Since the upper and the lower parts are movable in relation to another the RF cable has to allow such motion.

The present invention also relates to a radio communication unit and a portable communication device for enabling using a rigid coaxial conductor in a multi-part portable communication device.

Fig. 1 shows a radio communication unit 100 according to a preferred embodiment of the present invention. This radio communication unit comprises a first rigid arm 102 and a second rigid arm 104 connected to each other by a connecting unit 106. The first and second rigid arms 102 each have a first electric conductor and a second electric conductor, that are coaxially arranged in relation to each other. These conductors are also electrically insulated in relation to each other. In a preferred embodiment these arms are tubular.

The arms are thus rigid coaxial tubes and as such they possess good RF transferring properties, such as having low RF losses.

However, can rigid coaxial tubes be fitted in a mobile phone of a clam-shell type for transferring RF signals between a lower part and an upper part? The answer is no, unless the rigid tubes can be connected in a way such that rotational motion is allowed.

In fig. 1 the first rigid arm 102 is connected to the second rigid arm 104 at a connecting unit 106. This connecting unit allows rotational motion. As seen in fig. 1 the first arm 102 has a first end 110 and a second end 108, where the first end 110 of the first arm 102 is connected to the conneting unit 106 at a first connecting site 112. As can also be seen, the second arm 104, has a first 116 and a second end 118, of which the first end 116 is connected to the connecting unit 106 at a second connecting site 114.

The connecting unit 106 is typically made of two halves that are arranged rotatably in relation to one another around an axis of rotation, A. This axis is directed through the center of the connecting unit and allows rotation of the first connection site in relation to the second connection site of the connection unit.

As the first end 110 of the rigid arm 102 is connected to the first connection site 112 of the connection unit 106 and the first end 116 of the second rigid arm 104 is connected to the second connecting site 114 of the connection unit 106, the radio communication unit 100 will not be completely rigid, although the first 102 and second arms 104 are rigid. As the connection unit allows rotation around the axis of rotation, indicated with A in fig. 1, the first 102 and second 104 arms are rotatable around the same axis of rotation, rotation axis A. The first rigid arm 102 and the second rigid arm 104 of the radio communication unit 100 can thus be folded towards or away from each other. The radio communication unit 100 is thus foldable.

According to a preferred embodiment of the present invention connection unit 106 comprises a first electric conductor and second electric conductor that are coaxially arranged and electrically insulated, in relation to each other. This connection unit 106 thus has coaxial conductors. By connecting the connection site 112 of the connection unit 106 to the first end 110 or the first rigid arm 102, the coxially arranged conductors are contacted with the coaxially arranged conductors of the first rigid arm, in such a way that the inner conductor 120 of the first rigid arm 102 is contacted to the inner conductor of the connection unit 112, and the outer conductor of the first rigid arm 102 is contacted with the outer conductor of the connection unit 106.

The connection unit 106 having two coaxial rigid parts rotatable in relation to each other, preferably comprises electrical contact between the two parts, such that the first connection site 112 is electrically connected to the second connection site 114. This electrical contact comprises electical contact between the inner conductor of the first connection site 112 and the inner conductor of the second connection site 114. Moreover, the electrical contact within the connection unit 106 preferably also provides electrical contact between the outer conductor of the first connection site 112 and the outer connector of the second connection site 114. Moreover, the inner conductors are electrically insulated with respect to the outer conductors.

The electrical contact between the two inner conductors and the two outer conductors, respectively, can be realised in many different ways. One way of arranging the two rigid parts of the connection unit 106 rotatably in respect to each other, and establishing an electric contact between the two inner conductors, still allowing rotational motion with respect to the two rigid parts, may be by using a slip ring contact between the inner conductors. The two inner conductors can thus slip against each other to allow said rotational motion. Similarly, a slip ring contact may be provided to establish the electrical contact between the outer conductors of the first and second connection sites, which slip ring contact would allow a rotational motion. The two outer conductors would thus slip against each other upon rotational motion of the two rigid parts.

Similarly, when connecting the second connection site 114 of the connection unit 106 to the first end 116 of the second rigid arm 104, the inner conductor of the second rigid arm 104 is contacted with the inner conductor of the connection unit 106 and the outer conductor of the second rigid arm is contacted with the outer conductor of the connection unit 106. By contacting the outer conductors to each other and the inner conductors to each other, having an electric insulation in between the two conductors, enables a good RF signals transfer performance.

Fig. 1 also shows an inner conductor 122 of the second rigid arm 104, which arm is of the same type as the first rigid arm 102. By connecting the first 102 and second 104 rigid arms 102 to the connection unit 106, electrical contact between the inner conductor 120 of the first arm 102 and the inner conductor 122 of the second rigid arm 104 is obtained. Similarly, by connecting the first rigid arm 102 and the second rigid arm 104 to the connection unit, as described above, an electrical contact is obtained between the outer conductor of the first rigid arm 102 and the outer conductor of the second rigid arm 104, via the connection unit. The inner and outer conductors remain electrically insulated, in relation to each other.

According to the preferred embodiment of the present invention, the first rigid arm 102 is elongated and is connected to the first connection site 112 of the connection unit 106, in a direction that is substantially perpendicular to the axis of rotation A, of the connection unit 106, as shown in fig. 1.

According to another embodiment of the present invention the first arm 102 is connected to the first connection site 112 in a direction that is substantially parallell with the direction of the axis of rotation A (not shown). In this embodiment, the inner and the outer conductors of the first connection site are coaxial with the rotation axis, A. In this embodiment of the present invention, the direction in which the first rigid arm may be elongated is still perpendicular to the axis of rotation A. The first rigid arm is formed as the letter L, with the base of the letter coaxial with the rotation axis A and the stem of letter L substantially directed in the direction in which the first rigid arm may be elongated.

According to another embodiment of the present invention the first end 110 of the rigid arm 102 may be connected to the first connection site 112 of the connection unit 106, such that the direction of the first connection site 112 having the connected first rigid arm 102 and the direction of the axis of rotation forms an acute angle.

The radio communication unit 100 as shown in fig. 1 thus enables folding of the first rigid arm 102 in relation to the second rigid arm 104. This folding possibility is advantageously used in the portable communcation device as shown in fig. 2, according to a preferred embodiment of the present invention.

Fig. 2 is a side view cross section of a portable communication device according to a preferred embodiment of the present invention. This figure shows a mobile phone, as one example of a portable communication device, in a state in which an upper part 224 and a lower part 226 are folded against each other, in a rotation area 228. The mobile phone 200 is in a folded state.

Fig. 2 also shows a radio communication unit having a first rigid arm 202, a second rigid arm 204 and a connection unit 206, wherein the first rigid arm is locatd in the upper part 224 of the mobile phone 200, the second rigid arm 204 is located in the lower part 226 of the phone 200, and the connection unit 206 is located in the rotation area 228 of the device 200. Moreover, a first end 210 of the first rigid arm 202 is connected to a first connection site 212 of the connection unit 206, and a first end 216 of the second rigid arm is connected to a second connection site 214 of the connection unit 206.

In a preferred embodiment of the present invention the connection unit 206 is of the type as described in relation to fig. 1, that is a type that has an axis of rotation, in fig. 1 indicated by A. The connection unit 206 thus also possesses an axis of rotation enabling rotation of the first connection site 212 and the second connection site 214 are rotatable.

Furthermore, the rotation area 228 of the mobile phone 200 is also designed to allow rotation of the upper part 224 of the phone in relation to the lower part 226 of the phone 200. For this reason an axis of rotation is defined within the rotation area 228. In order to enable rotation of the first rigid arm 202 located in the upper part 224 of the phone 200 in relation to the second rigid arm 204 located in the lower part 226 of the phone 200, the axis of rotation of the connection unit 206 must coincide with the axis of rotation of the rotation area 228.

The first rigid arm 202 and the second rigid arm 204 are designed to allow transferring RF signals between the upper part 224 and the lower part 226 of the mobile phone. Typically, the second end 208 of the first rigid arm 202 is connected to an antenna 220 and the second end 218 of the second rigid arm 204 is connected to a printed wire board (PWB) 222, between which RF signals are transferred upon receiving or transmitting radio signals. The fact that the PWB is located in one part, here the lower part, and the antenna is located in another part, here the upper part, of the two-part mobile phone 200, makes demands on a transfer of RF signals between the upper 224 and the lower 226 part of the device 200.

As fig. 2 is a side view cross section of a portable communication device in a folded state of the device, fig. 3 shows a portable communication device in a side view cross section in an un-folded state. Fig. 3 shows one type of a portable communication device of the type mobile phone. This mobile phone 30 being in an un-folded state, contains a first rigid arm 32 and a second rigid arm 34, connected to each other at a connection unit 36, as shown in fig. 3. The connection unit 36 is designed to enable the first rigid arm 32 to be rotatable in relation to the second rigid arm 34, when being connected to the connection unit 36, as shown in fig. 3. This is enabled by designing the connection unit 36 as described above in relation to figs. 1 and 2.

It is emphasized that this invention can be varied in may ways, of which the alternative embodiments below only are examples of a few. These different embodiments are hence nonlimiting examples. The scope of the present invention, however, is only limited by the subsequently following claims.

According to another embodiment of the present invention, the connection unit comprises a first rigid arm and a connection unit, to which the first rigid arm is connected.

According to another embodiment of the present invention, the portable communication device comprises a rigid first arm and a second arm, which both are connected to a connection unit.

According to another embodiment of the present invention, the portable communication device comprises a first rigid arm connected to a connection unit, for enabling,rotation around an axis of rotation within the connection unit.

According to another embodiment of the present invention, the portable communication device comprises a first rigid arm connected to one site of one part of a connection unit, whereas another site of another part of a connection unit, is connected directly to RF circuitry, for enabling RF signal transfer between the RF circuitry and the second rigid part.

According to another embodiment of the present invention the connection unit comprises more than two parts of which at least two are movable around an axis of rotation in relation to one another.

According to yet another embodiment of the present invention the portable communication device may be any kind of portable communication device containing multiple housing parts that can be moved in relation to one another. Examples of such portable communication devices are flap-mobile phones, jack-knife mobile phones to mention a few.

By using a radio communication unit, having a coaxial connection unit including parts that are rotatable in relation to one another, folding of said radio communication unit is enabled.

Another advantage by using a semi-rigid radio communication unit is that is has better RF performance relative flexible RF cables. The semi-rigid radio communication unit obtains a lower insertion loss, enhanced shielding and better possibilities for grounding, compared to flexible cables.

Yet another advantage is that the RF performance may be further increased due to the fact that a larger diameter may be used when using a rigid coaxial cable as compared to when using a flexible cable.

It is furthemore advantageous that the shield of a rigid arm can be soldered directly to a printed wire board (PWB) for instance within the different housing parts of a mobile phone, giving better antenna performance and better interference immunity, that minimised interference between sensitive electrical/electronical parts in the portable communication device.

Also, by fixating a rigid arm by soldering it to a PWB and by connecting it to a rotatable radio communication unit, the rigid arm will be fixed in the rotation area of the portable communication device, reducing potential problems of conductors being squeezed, reducing the performance of the portable communication device.