Cutlery – Razors – With cooperating shearing blades
Reexamination Certificate
1999-10-21
2001-10-23
Watts, Douglas D. (Department: 3724)
Cutlery
Razors
With cooperating shearing blades
C156S274400
Reexamination Certificate
active
06305083
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an apparatus, such as a shaver, a toothbrush, or a kitchen machine, with a housing which has a synthetic resin wall portion on which a synthetic resin panel is fastened.
It is often desirable for wall portions of a housing to be provided with panels. Such panels may have a decorative function, but also a technical function. Various methods are known for fastening such panels to a housing wall. Examples are screw connections and snap connections. If the panel is present at the outside of the wall portion, the above methods do not lead to an attractive appearance. Snapping home in practice often gives rise to play, so that the panel will be slightly loose. Gluing is a better method in this case. Although there are satisfactory glue compositions nowadays, they are not resistant to chemical substances such as additives (lotions) in the long run. Another fastening method is ultrasonic welding. Here a vibratory force is applied to one of the parts by means of a tool. This often causes damage to the surface of the wall, which is not acceptable visually. In addition, the choice of materials is limited in the case of ultrasonic welding, inter alias on account of the material characteristics.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an apparatus in which a synthetic resin panel is fastened to a synthetic resin wall portion of a housing in a reliable and visually acceptable manner.
The invention is for this purpose characterized in that an element of electrically conducting material having the shape of a closed loop is present between the panel and the wall portion, by means of which element the panel is fastened to the wall portion through an RF (Radio Frequency) adhesion process. In an RF (Radio Frequency) adhesion process, also called inductive welding, an electromagnetic field is generated close to the element, so that an induction current will flow through the element. The ohmic resistance of the element causes a heat generation in the element which melts the synthetic resin parts adjacent to the elements, whereupon these elements are fused together and fused to the element upon cooling down. Melting takes place through a small depth, so that no deformations are visible at the surface of the synthetic resin panel. It was found that this method leads to a reliable connection of the panel to the wall portion which is visually acceptable and is resistant to liquids, especially chemical liquids. An additional advantage of this method is that the element need not be plane but may also have a curved shape, adapted to the shape of the wall portion and the panel. This offers a designer a considerable freedom in design.
A preferred embodiment is characterized in that the synthetic resin housing is at least partly watertight, and the wall portion has at least one opening for accommodating electrical or mechanical elements, such as a display or a switch, while the panel is arranged over said opening and the element of electrically conducting material encircles the opening. If the synthetic resin wall portion of the housing is provided with an opening and the housing has to be watertight for cleaning purposes, the opening must also be closed in a watertight manner. The most well-known method for rendering the opening with a panel watertight is through the application of an elastic seal between the panel and the wall portion. The parts must then be fastened against one another with force, for example with screws. This is a good method in principle, but it is found in practice that the seal may lose its elasticity after a longer period, and thus its sealing effect, also through the action of chemical substances. Nowadays, the seal is integrally manufactured with one of the synthetic resin parts in the injection molding process. This leads to another problem if at least one of the parts is to be painted. The painting process must take place before electrical or mechanical components are fastened in or against the housing wall. It is not possible, however, to injection-mold a sealing to painted parts. As was mentioned earlier, a glue connection and ultrasonic welding also have their disadvantages. The joint obtained through inductive welding supplies a highly reliable seal.
A further embodiment is characterized in that the wall portion is provided with two openings, one opening for a display and the other opening for a switch, said openings being both covered at an inside of the wall portion by said panel, the latter being provided with a window of a transparent material situated in front of the display opening and with a membrane with an actuator situated in the opening for the switch.
A yet further embodiment is characterized in that a second panel is present which is fastened to the outside of the wall portion, again by means of an element of electrically conducting material in the shape of a closed loop and an RF adhesion process, which panel has an operational surface of a flexible material which lies opposite the membrane with the actuator of the panel mentioned earlier, and which panel covers the opening in the wall portion in front of the switch.
REFERENCES:
patent: 4801343 (1989-01-01), Tamba et al.
patent: 5483745 (1996-01-01), Izumi
Meijer Matthijs J.
Rijken Martinus M.
Bartlett Ernestine C.
Spain Norman N.
U.S. Philips Corporation
Watts Douglas D.
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