SU798669A1 - Metal detector - Google Patents

Description

The rators are connected to the output of the amplifier, and their outputs to the inputs of elements And opposite channels, the outputs of elements AND are connected to the inputs of the OR element, the output of which is connected to the input of the actuator, and the clock pulse generator is connected to the shift inputs of the shift registers of both channels.

In addition, the amplifier metal detector is made selective, and the comparator of one of the channels is inverting.

The drawing shows a block diagram. MA metal detector. .

The metal detector contains a series-connected sensor 1, generator 2, detector 3, amplifier 4, the output of which is connected to the inputs of two channels, each of which contains a comparator 5, shift register 6, element 7 I. The output of channels is connected to the inputs of element 8 OR, the output of which connected to the input of the actuator 9, and the generator output 10 clock pulses connected to the shift inputs of registers b, and the outputs of the Comparators 5 are additionally connected to the inputs of the elements 7 And opposite channels.

The metal detector works as follows.

Metallic items accidentally caught in the technological mass: together with the mass, the first and second coils of the inductive sensor 1 are passed. the signal is a sequence of two different-polarized pulses, following one after the other with a time equal to the time of movement of the metal object from the first coil of the sensor about the second. The polarity of the pulses is due to the fact that the coils of the sensor 1 are turned on oppositely, and their magnetic fields are balanced for increased sensitivity. A metal object, pass sensor 1, violates this balance. Two cases are possible: a gauge object with magnetic permeability ju 1 (steel, cast iron, nickel-iron alloys, etc.) passes through the coils of the sensor. At the output of the amplifier, the signal is a sequence of negative and positive pulses. Both cases are possible, since it is equal to the probability of getting into the technological mass of metallic values of ferrous or non-ferrous metal inclusions controlled by the metal detector.

In order to ensure the operability of the slotter in both cases, a two-channel scheme was introduced into it.

The elements of the metal detector in the first case interact as follows.

The amplified signal from the output of amplifier 4 falls on the inputs of two comparators .5. The first positive impulse, consisting of the signal from the movement of a metal object through the sensor, passes through comparator 5, channel A, where its amplitude is estimated (the sensitivity of the metal detector is set by comparators) and fed to the counting input of the shift register 6, filling in several of its bits. The clock pulse generator 10 provides a delay of the pulse received in the register for the time it moves through all bits. The delay time is mj, where m is the number of bits of the shift register, and f is the frequency of the clock pulses of the generator 10. The delayed signal is fed to the first input of the logic element 7 of this channel. The second pulse (negative), which constitutes the signal from the movement of a metal object through the second coil of the sensor, does not pass the channel A comparator through the inverted comparator 5 of channel B and without the back of the input signal to the second input of the logic element 7 of channel A. Since the delay BpeivOT is first pulse corresponds to the time of movement of the metal object between the coils of the sensor, then, consequently, the delayed pulse and the second component signal to the element 7 will come at the same time. At the output of the circuit 7, a pulse is formed, which passes through the element 8 OR and is used to control the actuating device (sound or light signaling, or a mechanical metal remover).

The first (positive) pulse, which constitutes the signal from the output of the comparator 5 of channel A, is also directed to the second input of element 7 and kangsha B.

However, the second (negative) pulse, the passage of the comparator 5 of channel B and hitting the counting input of the register 6 of the shift of channel B, is delayed in it

at the same time t

which excludes

year

the coincidence of the pulses on channel B on element 7 and channel B.

In the second case, the elements of the proposed device interact in the same way, with the only difference that the first negative pulse is inverted by the inverting comparator 5 of channel B, delayed in shift register 6 and fed to the first input of element 7 And channel B.

Claims (2)

The clock pulse generator 10 is made with an adjustable frequency, which makes it possible to set the delay time equal to the time of movement of a metal object in the field of sensor 1 for any speeds of movement through it controlled technological masses in accordance with the conditions of a specific production. A prerequisite for the actuation of the actuator 9 is a delayed first pulse and a second component signal from the passage of a metal object through the sensor. False actuation of an executive device that does not correspond to a detected metal object is practically excluded, since the probability of coincidence of impulses from interference in any of the channels is extremely small. Thus, the two-channel scheme allows decreasing the threshold for the comparators of both channels, i.e., to increase the sensitivity of the metal detector due to the fact that amplified noise 4 enters the inputs of the comparators 5 at the same time, which eliminates false alarms. Claims of the invention:. A warm-air detector containing a successively connected sensor with two oppositely connected and located in parallel planes of coils, a generator, a detector, an amplifier and an actuator, characterized in that, in order to improve the noise immunity and sensitivity, a clock pulse generator is added to it , an OR element and a two-channel circuit, each channel of which contains a series-connected comparator, a shift register and an AND element, with the inputs of the comparators being connected to the output of the amplifier, and x outputs to the inputs of the AND opposite channel elements and outputs connected to inputs of OR gate whose output is connected to the input of the actuator, and a clock generator coupled to the inputs of both channels sdvigakhtsimi shift registers. 2. The metal detector of claim 1, wherein the amplifier is selective and the comparator. one of the channels - inverting. Sources of information taken into account in the examination 1. The author's certificate of the USSR 147153, cl. G 01 V 3/00, 1961. 2. Kritsky E. L. and M. M. N. Protection of crushers from hitting metal objects. M., Gosgortehiz-dates, 1963, p. 45-47 (prototype). Cnalal I W Channel b