Bar code and device for reading the bar code

摘要

The bar code (2-4) is cut (notched) into an electrically conductive material (1). As reading head, the device has an electromagnet (6) arranged in a tuned circuit (5, 6) in such a manner that in the event of the reading head being placed upon the material (1), the electromagnet (6) induces a locally closely delimited eddy current (9; 10) in the material (1). In addition, it has a device for detecting the different magnetic resistance of the tuned circuit (5, 6) in the event of placing the reading head over the uncut material and over a notch (4), as well as for converting the detected differences into the information contained by the bar code. The application of this bar code and the device can be used, for example, to check the workpieces used in a production process for correctness. Contamination of the bar code by means of lubricants or coolants and by particles of dirt does not disturb the reading. A complete coverage is also possible, for example with a primer or, in the finished product, with a lacquer. The bar code can even be made invisible by being filled in, whether it be because of the appearance of the object or in order to hide the bar code. <IMAGE>