The original helix coil was invented by Chubb in 1911. It was an air coils, wound using a flat wire in a helix manner.

Around 1990, Williamson patented a series of designs of magnetic core inductors using the helix windings with claims that are sufficiently different than the original helix design for patents to be granted. Williamson patents claimed magnetic core inductor comprising in combination of, among other things,

The helical coils used in CWS's design follows the original Chubb's design where the above 2 features are not incorporated. In CWS's design, by having the output tabs the same width and cross sectional area as the rest of the turns, we are able to reduce the manufacturing cost substantially and make the coils mass manufacturable. This is because we can use a same uniform strip of coils to do the helix windings. CWS uses kapton insulation coating which has better dielectric ( hi-pot) and offer higher temperature characteristic.

In addition the helix coils are not compacted to make n+1 winding characterized by a height substantially equal to the height of a similar uncompacted coil of n turns. In CWS's coils, compacting the coils to achieve the above feature will cause the insulation layer to degrade and hence may lower the dielectric breakdown of the insulation.

Therefore, we believe CWS's HW series does not infringe of any known patents.

The Williamson patents are currently owned by Schott Corporation. Please refer to their patents for more information and their patents expiration dates.

Note: The above is the opinion of CWS's patent attorney and is not necessarily the views of any other parties.