GB2385021A

GB2385021A - A method of manufacturing by moulding and a product thereof

Info

Publication number: GB2385021A
Application number: GB0203001A
Authority: GB
Inventors: David Ganeshmoorthy; Kandiah Ganeshmoorthy; Richard Ganeshmoorthy
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-02-08
Filing date: 2002-02-08
Publication date: 2003-08-13
Also published as: GB0203001D0

Abstract

An antenna sub-assembly comprises a core unit of a first plastics material and a member of a second plastics material extending around the core unit forming an antenna, the second plastics material having a higher electrical conductivity than the first plastics material. Also disclosed is a method for the manufacture of the antenna comprising the steps of locating the core unit of plastics material in a mould, injecting into the mould a second plastics material of higher electrical conductivity than the first material, so as to surround the core unit and form the antenna. A cover material may be overmoulded around the antenna to complete the sub-assembly or may be provided by other means. The antenna sub-assembly may be provided with an attachment to enable the antenna to be secured to a mobile telephone so that electromagnetic radiation may be picked up by a helical path of the antenna and passed to the mobile telephone which would make use of the signals received by the antenna sub-assembly.

Description

A METHOD OF MANUFACTURING BY MOULDING AND A PRODUCT THEREOF This invention relates to a method of manufacturing by moulding and to a product of the method.

Antenna for mobile devices, particularly phones, involve the production in large numbers of a device manufactured to close tolerances. Heretofore the design of such antenna has involved the provision of a number of components which are subsequently assembled as a unit for subsequent addition to form a complete device such as a mobile phone.

According to a first aspect of the present invention there is provided a method of manufacturing by moulding an antenna subassembly comprising the steps of: locating a core unit of a first plastics material having a given electrical conductivity in a given mould in a mould sequence so that the given mould and the core unit form, in combination, a mould plenum defining boundaries of an antenna of predetermined configuration; injecting into the mould plenum a second plastics material of higher electrical conductivity than the given conductivity of the first plastics material so as to form the antenna; and providing a cover of material of relatively low conductivity over the formed antenna either by way of a further moulding stage in the mould sequence or otherwise to complete the sub-assembly.

According to a first preferred version of the first aspect of the present invention the core unit is formed by a preliminary moulding step undertaken prior to the locating step in a mould in the mould sequence prior to the given mould.

According to a second preferred version of the first aspect of the present invention or of the first preferred version thereof the step of injecting the second plastics material

into the plenum results in the provision of an antenna which is at least in part of strip form spaced around, and off-set from, a longitudinal axis of the core unit.

According to a third preferred version of the first aspect of the present invention or of the first preferred version thereof the step of injecting the second plastics material into the plenum results in the provision of an antenna which is at least in part in the form of a helical member disposed about, and off-set from, a longitudinal axis of the core unit.

According to a fourth preferred version of the present invention or of any preceding preferred version thereof the core member incorporates an attachment enabling the antenna to be attached to a device making use of signals received by, or to be transmitted from, the antenna; the attachment being formed integrally with, or attached to, the core unit so that the attachment is wholly or substantially of first plastics material of the given conductivity.

According to a fifth preferred version of the first aspect of the present invention or of any preceding preferred version thereof the sub-assembly incorporates an attachment enabling the antenna to be attached to a device making use of signals received by, or to be transmitted from, the antenna; the attachment being attached to the antenna so that the attachment is at least substantially of the first plastics material.

According to a second aspect of the present invention there is provided an antenna sub-assembly comprising: a core unit of first plastics material, the unit being of substantially cylindrical form, with a longitudinal axis; an attachment means at or near one end of the core unit whereby the subassembly can be connected to a unit providing for the transmission or reception of signals by way of the sub-assembly;

the core unit having a central passage, an external surface incorporating path or region serving to define an antenna region in, and a linking channel joining the central passage to the external path or region; a continuous member of a second plastics material extending from the central passage by way of the linking channel and occupying the antenna region; the continuos member being of a second plastics material having a higher electrical conductivity than the first plastics material.

According to a first preferred version of the second aspect of the present invention the antenna region is of plate like form that is to say the thickness of the zone measured radially from the longitudinal axis is substantially less than the width of the zone measured as an arc subtending the longitudinal axis.

According to a second preferred version of the second aspect of the present invention the antenna region is in the form of a helix disposed about the longitudinal axis.

According to a third preferred version of the second aspect of the present invention or of any preceding preferred version thereof the central passage includes a rod like member of the second plastics material extending co-axially and longitudinally over at least some of the antenna region to provide for interaction with the continuous member to provide for enhanced transmission or reception of electro-magnetic radiation by means of the antenna.

According to a third aspect of the present invention there is provided a mobile communication device equipped with an antenna sub-assembly according to the second aspect of the present invention or any preferred version thereof.

Amongst other benefits the present invention provide a method involving, and a fabrication by, starting with basic materials and ending with the completed subassembly by means of an automated sequence of steps so avoiding, or reducing the need for, hand assembly steps.

Exemplary embodiments of the invention will now be described with reference to the accompanying drawings of an antenna sub-assembly for a mobile phone.

First Embodiment Figure 1 shows a side view of a moulded plastic core; Figure 2 shows an internal section of the core of Figure 1; Figure 3 shows a combination of the core of Figure 1 and 2 with a conductive material injected around it; Figure 4 shows the combination of Figure 3 with a finishing moulding snapped in place over the combination.

Second Embodiment Figure 5 shows a side view of a moulded plastic core; Figure 6 shows an internal section of the core of Figure 5; Figure 7 shows a combination of the core of Figure 5 and 6 with a conductive material injected around and in to it; Figure 8 shows the component of Figure 5 with a finished moulding injected around it.

FIRST EMBODIMENT Figures 1-4 variously show some internal components of a moulded antenna subassembly incorporating a moulded plastic core 10 with: a recessed track 11 on its periphery 11 A ; a feed connection 12; a connector shaft 13; a connector contact 14; and a snap fit over-mould 15.

Cavity 16 serves as a tooling transport location for a core pin.

The moulding process is undertaken on a multi-station machine at a first station to provide the core 10 shown in Figures 1 and 2. The core 10 is in this case includes a

threaded connector C section whereby the sub-assembly is on completion eventually connected to the remainder of a mobile phone.

The moulded core 10 is located in the moulding tool by means of cavity 16. Having formed the core 10 at a first work station the core 10 is then moved and located in a second mould cavity to provide for the moulding of a conducting antenna for the transmission and reception of radio signals.

Figure 3 shows the result of a second injection stage of the electrically conducting material in order to fill the track recess 11, feed connector 12 and connector shaft 13.

The injected conducting material is shown hatched and on the periphery of 11A the antenna is in the form of a strip of greater width than thickness.

Having completed two injection mouldings composite component of Figure 3 is then ejected from the moulding machine. Assembly of the sub-assembly is then completed by the addition of a snap-fit over-moulding 15 whose skirt 15A contains a recess for engagement with external lip L on core 10.

In this embodiment the conductive shaft 13 extends through connector C of core unit 10 which is of relatively non-conducting plastic. Thus the unit W is mounted on, for example, a mobile radio by way of an insulated connector C and shaft 13 is connected within the mobile radio by separate means.

This first embodiment provides an automated process wherein a single moulding machine two moulding stages occur. The first stage provides a basic core for the subassembly, the second is of a relatively conducting material to provide the conducting antenna element. The fabrication process is completed once the two moulding stages are completed by removing the unit from the machine and adding snap on cover 15 which is a separately manufactured moulding.

SECOND EMBODIMENT

In the second embodiment the manufacturing process is automated further by undertaking three moulding stages so reducing, if not eliminating, the need for significant manual handling.

Figures 5 and 6 variously show a core member 20 with a central channel 21 and a periphery 22 into which is provided a recessed helical path 23 which at inner end 24 opens into a radial path 25 extending through wall 26 of member 20 to open into a channel 27 coaxial with, but or reduced diameter relative to, channel 21.

Figure 7 shows the result of an injection step wherein a conductive plastic is injected into the core member 20 whilst it is held mounted in a mould (not shown) whose inner boundaries serve to define an injection plenum whose inner boundary is defined by the periphery 22 of the member 20 and whose outer boundary is defined by the mould.

This injection step results in the formation of helical antenna 29, radial connection 32 and central electrode 30. In this case the central electrode 30 extends outside the core member 20 in the form of a threaded connector 33 so as to provided for good electrical contact between the electrode 30 and a socket of complementary form such as can be provided on a radio with which the antenna 29 is to be used. However other forms of connecting means can be used to conform with other assemblies of which the antenna A is to be connected.

Figure 8 shows the final moulding step where the sub-assembly shown in Figure 7 is located in a final mould cavity and a final injection stage is undertaken involving a low conductivity plastic to provide an over moulding 35 covering the remainder of the antenna unit.

Following the final stage described in connection with Figure 8 the complete antenna sub-assembly X is withdrawn from the sequence of moulds on the machine and subjected to, for example, testing and packing or assembly.

A number of variants can be developed utilising the concepts of the present invention shown in the preceding embodiments.

Claims

CLAIMS 1 A method of manufacturing by moulding an antenna subassembly comprising the steps of: locating a core unit of a first plastics material having a given electrical conductivity in a given mould in a mould sequence so that the given mould and the core unit form, in combination, a mould plenum defining boundaries of an antenna of predetermined configuration; injecting into the mould plenum a second plastics material of higher electrical conductivity than the given conductivity of the first plastics material so as to form the antenna; and providing a cover of material of relatively low conductivity over the formed antenna either by way of a further moulding stage in the mould sequence or otherwise to complete the sub-assembly.
2 A method as claimed in Claim 1 wherein the core unit is formed by a preliminary moulding step undertaken prior to the locating step in a mould in the mould sequence prior to the given mould.
3 A method as claimed in any preceding claim wherein the step of injecting the second plastics material into the plenum results in the provision of an antenna which is at least in part of strip form spaced around, and off-set from, a longitudinal axis of the core unit.
4 A method as claimed in Claim 1 or Claim 2 wherein the step of injecting the second plastics material into the plenum results in the provision of an antenna which is at least in part in the form of a helical member disposed about, and off- set from, a longitudinal axis of the core unit.

<Desc/Clms Page number 9>
5 A method of manufacturing by moulding an antenna wherein the core member incorporates an attachment enabling the antenna to be attached to a device making use of signals received by, or to be transmitted from, the antenna; the attachment being formed integrally with, or attached to, the core unit so that the attachment is wholly or substantially of first plastics material of the given conductivity.
6 A method as claimed in any of preceding claims 1 to 4 wherein the sub- assembly incorporates an attachment enabling the antenna to be attached to a device making use of signals received by, or to be transmitted from, the antenna; the attachment being attached to the antenna so that the attachment is at least substantially of the first plastics material.
7 An antenna sub-assembly comprising: a core unit of first plastics material, the unit being of substantially cylindrical form, with a longitudinal axis; an attachment means at or near one end of the core unit whereby the sub-assembly can be connected to a unit providing for the transmission or reception of signals by way of the sub-assembly; the core unit having a central passage, an external surface incorporating path or region serving to define an antenna region in, and a linking channel joining the central passage to the external path or region; a continuous member of a second plastics material extending from the central passage by way of the linking channel and occupying the antenna region; the continuos member being of a second plastics material having a higher electrical conductivity than the first plastics material.
8 An antenna as claimed in Claim 7 wherein the antenna region is of plate like form that is to say the thickness of the zone measured radially from the longitudinal axis is substantially less than the width of the zone measured as an arc subtending the longitudinal axis.

<Desc/Clms Page number 10>
9 An antenna s claimed in Claim 7 wherein the antenna region is in the form of a helix disposed about the longitudinal axis.
10 An antenna as claimed in Claim 9 wherein the antenna is formed as a rod like member.
11 An antenna as claimed in Claim 7,8, 9 or 10 wherein the central passage includes a rod like member of the second plastics material extending co-axially and longitudinally over at least some of the antenna region to provide for interaction with the continuous member to provide for enhanced transmission or reception of electro-magnetic radiation by means of the antenna.
12 A method of manufacture as hereinbefore described with reference to the accompanying drawings.
13 A sub-assembly manufactured has hereinbefore described with reference to the accompanying drawings.
14 A mobile communication device equipped with an antenna sub-assembly as claimed in any of preceding Claims 7 to 11 and 13.