PLASTIC MATERIAL, AND METHOD OF PRODUCING IT

Field of the Invention

The present invention relates to a hybrid unit comprising a metal part combined with a plastics part, the surface of which is coated using for instance a PVD process (Physical Vapour Deposition). The hybrid unit according to the invention makes it possible to manufacture and apply objects of a very fine decorative quality, which objects possess special characteristics that are achieved by the combination with integrated plastic parts, upon which a coating of aluminium or aluminium alloys has been applied by an evaporation technique. The complete hybrid unit has an anodisable surface having op- timal decorative and corrosion protecting characteristics.

Background of the Invention

It is of interest to be able to apply user interfaces with a high content of information in dialogue with the user of a given apparatus. This means that for instance control but- tons and displays can aid the user with interactive display means. An extended use of metal for surfaces and operational handles that enhances the aesthetic appearance of an apparatus raises the need for new means for communication with the user. In summary, the need can be expressed as how is it possible to communicate information via a metal surface? How can a control button indicate a status or an information?

DE 100 18 933 CI describes a control button that can indicate a status or an information. This control button comprises a metallic base body, in the inner portion of which is formed (by use of a stamp) an inner cavity, which comprises outwardly extending leg portions that extend from the inner cavity in a direction towards the front face of the metallic base body. These leg portions however do not extend all the way to the front face of the metallic base body but only to a certain distance from the front surface. The inner cavity including the leg portions are filled with a liquid plastic material that undergoes a hardening process. When this is completed, the front face of the metallic base body is milled to such a degree that the end portions of the leg portions that face away from the inner cavity are exposed at the front face, after which processing (milling) the resulting front face comprises metal portions and a suitable pattern of plastic portions, through which plastic portions light from a light source placed behind the metallic base body can pass. The end faces of the exposed plastic leg portions remain uncovered. The applicant has developed a system including aluminium surfaces that are permeable for ordinary light. The system is described in the applicant's patent US 7,663,612. The system fulfils the above requirements completely, but it is desired to obtain an alternative that is more simple, and hence cheaper, to produce. An alternative to light-permeable metal objects is metal coated plastic objects.

The present invention combines different technologies into a new and effective manufacturing process, which is practically applicable. Standard processes that can be used for manufacturing metal coated plastic objects are for instance:

• Physical vapour deposition (PVD), which is a general method, in which a thin film of material is applied in the form of vapour. The coating method involves physical processes, such as high temperatures or plasma sputter bombardment.

• Ion vapour deposition (IVD), which is a physical process, wherein pure aluminium are vapour deposited on different substrates. The process takes place in vacuum to avoid oxidation of the surface of the substrate.

Description of the Invention

According to a first aspect of the invention, metal parts and plastic parts that have been surface treated are combined to a complete hybrid unit. Surface treatment can in this context be a material coating that is (a) painted on the object, or (b) PVD or IVD treated, or a combination of these means.

A hybrid unit that consists of a metal part combined with a plastic part is characterised by: • A first part made of metal is processed to enable it to accommodate another (second) part;

• The second part, which is made of plastic, is processed to enable it to be accommodated within the first part;

· The second part is completely or partially surface treated by a material applying process;

• The first and the second parts are assembled to provide a homogenous unit, such that the treated surface on the second part totally or partially appears as an integrated portion of the surface of the first part;

· The plastic part and/or the metal part can optionally be coated with a protective layer that reduces abrasion of the surface.

The second part consists of a plastic material that is transparent for light. Different plastic materials can be used, such as PMMA that can be milled or injection moulded. Examples of suitable materials are PMMA, PC, PVC or PE.

The second part may be coated by a layer of the same basis material as the first part, for instance aluminium.

A hybrid unit may comprise a second part with the treated surface on the second part being completely or partially transparent for light.

According to a preferred embodiment of the invention a layer of aluminium is applied of a thickness of approximately 10 nano meters. This thickness ensures that the layer is of sufficient strength and also transparent for light.

As an option it is possible to apply a protective layer of AI2O ₃ of a thickness of a few nano meters. The mentioned thickness of approximately 10 nano meters is achieved by rotation of the respective parts in a vacuum chamber a number of times. Alternatively, the surface can be coated with a hardcoat based on UV hardened acrylic. As an option to pure aluminium a combination of aluminium and another metal can be evaporated onto the surface. The purpose of this is to provide a desired colour effect of the coating. The PVD process operates in this case at a temperature of typically 70 degrees Centigrade.

A second aspect of the invention relates to implementing optic fibres (light conducting portions, such as one or more channels) and possibly diffusers into the compound unit. Processing of the first part is carried out in order to be able to include the second part herein, which results in subdividing the first part in two or more other parts

The first part and the second part and two or more other parts are assembled to a single hybrid unit. The first and the second parts are assembled such that there is created one or more light-transparent channels or regions from the rear face to the front face of the hybrid unit.

The plastic and the aluminium objects can for instance be glued together using Loctite ^® 3295 two-component acrylic glue.

A third aspect of the invention relates to the provision of light sources behind the compound unit. When a light source is placed on the rear face of the hybrid unit, one or more points, symbols or regions are illuminated that appears on the front face of the hybrid unit. One or more points, symbols or regions that appear on the front face of the hybrid unit are created by:

• The first part of metal has through holes corresponding to those symbols (e.g. points, text, numbers and letters, 7-segment graphics) that shall be illuminated. · If the first part is subdivided in two or more other parts, these can have the same types of holes as described above. • The second part, that shall function as an light transmission path or optical fibre is formed such that it fits into - and fills the above mentioned holes in the first part plus holes in two or more other parts, if such parts are present.

• Those portions of the second part that shall function as a light-conducting ob- ject are vaporized onto the transparent aluminium layer.

A unit that uses the present invention may find application in many fields. Specifically, where the unit is an operational button and/or a source of information in consumer electronics, cars, boats, aeroplanes and control systems.

Description of the Drawing

The present invention will be better understood with reference to the cross-sectional view presented in figure 1 in conjunction with the following detailed description of an embodiment of the invention.

Detailed Description of the Invention

With reference to figure 1 there is shown cross-sectional views of the two parts that are used to implement an embodiment of the hybrid unit according to the invention. The basic part 1 is a metal object that has been processed into a given shape. The shown embodiment is a round operational button made of aluminium.

This can be moulded, processed, drilled, roulet, etc. depending on the specific functional requirements or use requirements.

In the basic part a cavity 4 has been provided allowing a plastic part 5 to be inserted into the cavity 4 and secured herein for instance by gluing of the plastic part 5 to the basic part 1.

The surface of the basic part 1 may be processed to provide it with symbols, points, text, etc. as functional or decorative elements on the front face of the operational button, according to the requirements of the specific application. Processing of the basic part 1 can take place from the front face and may be confined to the surface, i.e. not extending through the unit. Processing may also comprise through holes 2 depending on the specific need.

In the shown embodiment of a basic part 1 a circular cavity 2 has been milled in the part. The milling is extending through the part such that a separate circular object 3 with a specified distance between the basic part 1 and the circular object 3 is created.

The shown plastic part 5 is according to one embodiment of the invention made of transparent plastic material. This object can hence be used as an optical fibre or light conducting portion in addition to function as a stabilizing object for the basic part 1 and the circular object 3, when these are glued together.

The shown plastic part 5 is according to one embodiment of the invention provided with a layer of aluminium in a PVD/IVD vaporization process. The thickness of the aluminium layer is typically 10 nano meters, which makes the layer transparent for normal light, but still appears as an object in homogeneous aluminium, when light is not passing through it.

The entire part 5 can be provided with a metal layer, such as aluminium or alloys com- prising aluminium, but normally only those portions 6 that pass through the cavities or holes 2 that extend through the entire wall portion of the basic part 1 will be coated with aluminium or an aluminium alloy. The plastic part 5 can thus function as a light conducting path or fibre optic, when light is passed through if from the rear portion of the hybrid unit, and still make the hybrid unit appear as a homogeneous body of for instance aluminium when light is not passed through the cavities or holes 2.

In the preferred embodiment the complete hybrid unit includes the basic part 1, the plastic part 5 and the separate circular object 3. The surface of the hybrid unit appears homogeneous, which makes the unit appear as a complete aluminium construction. When lighted from the rear face, the cavities appear as lighting symbols via the transparent aluminium-coated regions. Units made after the teachings of the present invention can find wide application in products with particularly severe requirements for optimal decorative and/or corrosion protecting characteristics, such as: · Consumer electronic devices, such as audio/video systems, PC's, portable units like mobile phones, GPS's, media players, etc.

• Consumer implements for home use, such as white goods and sanitary implements.

• Consumer implements for use outside the home, such as in cars, boats, aero- planes and caravans.