PROBLEM TO BE SOLVED: To judge whether a plurality of types of metals exist or not in a product and whether the amount is appropriate or not by generating a metal reaction signal in reaction to the metals and judging a signal level when a product is passed through a magnetic field and the product has the metals. SOLUTION: A product P is carried by a conveyor C and is passed between a transmission coil and reception coils 6 and 7 of a metal detection machine 1. When a product P has a metal, the metal affects a magnetic field E and the magnetic flux of the coils 6 and 7 becomes unbalanced, a difference is generated in an inducted voltage, and a voltage signal is inputted to a differential amplifier 10. The amplified differential signal passes through a phase discriminator 12 as a metal reaction signal and is outputted to a judging means 4. A level for judging the mixture of unneeded iron is set to a judgment level d1 by a level-setting means 3, and a judgment level for sealing a needed soup bag made of aluminum is set to d2. A signal level is compared with judgment levels d1 and d2 by the judging means 4. And, the mixture of iron and presence or absence of sealing of the soup bag made of aluminum are judged based on the result and are displayed in a bar graph.

Metal detection machine and metal detection system

PROBLEM TO BE SOLVED: To provide a device or a method for discriminating a target object in a non-contact and non-destruction fashion and with little influence from the distance to the target object, and a device or a method for measuring the electric resistance of a target object having a dielectric constant close to 1 in a non-contact, non-destruction fashion and with little influence from the distance to the target object.SOLUTION: The discrimination device includes: a resonance circuit 10 having a resonance coil 11 and a capacitor 12 connected in parallel; a high frequency generating unit 21 for supplying a high frequency signal to the resonance circuit 10 through a resistance 24; a detection unit 20 for detecting the phase difference and amplitude of a signal generated at the resonance coil 11; and a data processing unit 30 for discriminating the difference in a composition or tissue of the target object based on a ratio between an amount of phase variation and an amount of amplitude variation when the target object is brought close to the resonance coil 11 from a state where the target object is not present in the vicinity of the resonance coil 11 from the phase difference and the amplitude detected by the detection unit 20.

Discrimination device and discrimination method for target object, electrical resistivity measuring device and electrical resistivity measuring method, component content estimation device and component content estimation method, and plate thickness estimation device and plate thickness estimation method

PURPOSE: To make high-reliability identification by inputting the voltage signal of a resonance circuit driven at the subcritical excitation frequency to a phase detector, outputting the phase shift signal when the phase is the threshold value or above, and transmitting the signal indicating a nonferrous metal or a ferrous metal respectively depending on whether the signal is the active state or inactive state. CONSTITUTION: A resonance circuit 13 containing a coil acted on a metal 14 via inductance L and a capacitance C has an impedance ZLC, and it is driven by a constant- amplitude oscillator 15 at the fixed frequency of the critical frequency (about tens kHz) or below. A constant exciting current flows in the circuit 13 at a high impedance 17 (R>>ZLC). The signal S0 of the oscillator 15 and the voltage signal S1 of the circuit 13 are inputted to a phase detector 20, the phase difference is compared with the threshold value, and the phase shift signal S2 is outputted when the phase difference exceeds the threshold value. A phase detector 21 compares the signal S1 with the other threshold value and outputs the brake signal S3 when the signal S1 is the threshold value or below. A discriminating logic 18 feeds the signal S2 or S4 indicating a nonferrous metal or a ferrous metal based on the signal S2 , S3 to an output circuit 19 and drives a display device.

Deideie Reonaaru

Papers

Inductive proximity sensor