Variable resistance device having a resistance element with laser cuts

A method of making a variable resistance device which comprises:

• depositing a layer of resistance material on the surface of an electrically non-conducting substrate to form a resistance path for a multi-fingered contact wiper;
• connecting a first electrical contact to the resistance material at one end of the resistance path;
• connecting a second electrical contact to the resistance material at the end of the resistance path opposite to the end of the resistance path at which the first electrical contact is connected;
• cutting, with a computer controlled laser system, at least one series of overlapping cuts in the edges of the resistance material generally transverse to the resistance path, said cuts having relatively small widths compared to the dimensions of the resistance path and with each successive cut made in the edge opposite to the preceeding cut;
• monitoring the total resistance along the resistance path between the first and second electrical contacts as the cuts are made;
• controlling the length of each laser cut and the spacing between cuts to provide a desired non-linear resistance function along the resistance path;
• and
• positioning a multi-fingered contact wiper in contact with and at an angle to the cuts in the resistance path whereby the wiper may move along the resistance path to provide different resistance values when the wiper is in contact with different sections of the resistance path and whereby deviations from the desired non-linear resistance function, due to the wiper crossing the cuts in the resistance path, are substantially eliminated.