US Patent 7315018 Machine tool analysis device and method

The invention relates to a device and method for analysis of a tool (50) e.g. used on a machine tool. A tool detector (5) includes a light emitter (12) and a light receiver (34). Tool (50) when progressed into a beam (20) of light emitted from the emitter (12) will cause a signal from the receiver to change. Circuitry (32) includes a digital signal processor which processes the signal from the receiver and produces an output only if the signal conforms to a predetermined condition. Preferably this predetermined condition could be e.g. a characteristic shape of the signal from the receiver, a change in a value derived from a succession of such signals or a change in the minimum or maximum values of a succession of signals from the receiver.