CN101387708A

CN101387708A - Receiving coil of door type metal detector

Info

Publication number: CN101387708A
Application number: CNA2008100718488A
Authority: CN
Inventors: 曾文阳
Original assignee: Suns Electric (Zhangzhou) Co Ltd
Current assignee: Suns Electric (Zhangzhou) Co Ltd
Priority date: 2008-09-22
Filing date: 2008-09-22
Publication date: 2009-03-18

Abstract

The invention discloses a receiving coil of door type metal detectors, comprising a skeleton and a coil which are symmetric to axis, wherein the coil is coiled on the skeleton in 8-form type. The receiving coil can make detection accurate and sensitive, having fast regulation and high efficiency.

Description

The receiving coil of door type metal detector

Technical field

The present invention relates to pick-up unit, particularly the structure of receiving coil in the door type metal detector.

Background technology

Door type metal detector mainly is to be used for checking the instrument that whether is mixed with metallics among logistics in the operation passage, the stream of people, and the logistics that is widely used in non-conducting material in the safety check department of customs, airport, station, harbour and the plant produced line detects.Existing door type metal detector mainly is made of probe and control circuit, and control circuit comprises high frequency oscillator, probe, tuned amplifier, wave detector, low-frequency amplifier, monostalbe trigger, power supply and topworks, referring to Fig. 3; Three coils around the logistics corridor coiling are arranged, wherein transmitting coil L in the probe ₀Between two parties, two receiving coil L ₁₀And L ₂₀Oppositely connection is arranged on transmitting coil L symmetrically ₀Both sides, the travelling belt that transports material therefrom passes, whole probe is peripheral by the electromagnetism conductor shielding, with reference to shown in Figure 4.Its principle of work is: transmitting coil L ₀Under oscillator high-frequency current GF drives, (receiving coil L in the notch of logistics corridor ₁₀With L ₂₀Near) form the high frequency alternating electromagnetic field, at receiving coil L ₁₀With L ₂₀Under the ideal conditions that near no metal object exists, two groups of technical parameters are identical, oppositely the receiving coil L that connects ₁₀And L ₂₀Induction electromotive force e ₁₀And e ₂₀Cancel each other no signal output.When being mixed with metallic impurity in the detected logistics when entering the detecting head notch, just destroyed the symmetry of transmitting coil both sides alternating electromagnetic fields, occur uneven, receiving coil L at this moment ₁₀And L ₂₀Just produce a high-frequency am signal output, wherein, the oscillation frequency of oscillator is a carrier wave, metal signal is a modulating wave, this mixes ripple through frequency-selecting amplification, detection, take out metal signal, deliver to low-frequency amplifier and amplify, in order to promote monostalbe trigger control warning, indication and topworks's action.

By above stated specification as can be seen, as if the accuracy and the sensitivity that will guarantee to detect, must guarantee two receiving coil L ₁₀With L ₂₀Can the number of turns equate that shape is identical, the two realizes that balance receives, could be at receiving coil L ₁₀With L ₂₀Near during no metal object, two receiving coil L ₁₀With L ₂₀Induction electromotive force e ₁₀With e ₂₀Can cancel out each other, maloperation can not occur.When making, all be at first enameled wire to be wrapped in respectively on the skeleton that shape is identical one by one (being generally circle) at present, require to select two receiving coil L according to making again with same number of turns and shape ₁₀With L ₂₀, electrically connect by the mode opposite, and be arranged on transmitting coil L symmetrically with winding direction ₀Both sides, find out that easily this combination production method can not be guaranteed two selected receiving coil L ₁₀With L ₂₀The winding number of turns and shape identical, the inductance value of the two and incomplete same is subjected to the influence of outside electromagnetic interference easily, reduces the accuracy and the sensitivity of testing result greatly; And the two is difficult to guarantee on the space with transmitting coil L when group is established ₀Symmetry needs respectively to two receiving coil L when debugging ₁₀And L ₂₀The position adjustment of being correlated with, very trouble wastes time and energy inefficiency.

Summary of the invention

Fundamental purpose of the present invention is to provide a kind of receiving coil of door type metal detector, and the accuracy of its detection is good, and is highly sensitive.

Secondary objective of the present invention is to provide a kind of receiving coil of door type metal detector, and its debugging is quick, efficient is high.

In order to reach above-mentioned purpose, solution of the present invention is:

A kind of receiving coil of door type metal detector comprises axisymmetricly skeleton and coil, and coil is wrapped on the skeleton in 8 font modes.

Above-mentioned skeleton is combined in the rotational symmetry mode by two shapes and the identical support body of size.

Above-mentioned support body is fixedly installed on the flat board.

After adopting such scheme, the present invention is by selecting axisymmetric skeleton for use, and the mode of coil with 8 fonts is wrapped on the skeleton, has the following advantages:

(1) axisymmetric skeleton has guaranteed that the shape of two receiving coils making is identical, and the winding mode of 8 fonts can guarantee that the winding turns of the two equates, closure is opposite, thereby during near can be receiving coil no metal object, the inductance value of two receiving coils is in full accord, be not subjected to extraneous other electromagnetic interference effect yet, the situation of maloperation can not occur, improve the accuracy and the sensitivity that detect;

(2) existence of skeleton fits together two receiving coils, and then in when debugging, two same moved further of receiving coil move debugging to two receiving coils respectively in compared to existing technology, and are simple to operate, increase work efficiency.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the circuit connection diagram of the present invention when working;

Fig. 3 is the structured flowchart of existing door type metal detector;

Fig. 4 is that the position of receiving coil and transmitting coil concerns synoptic diagram in the existing door type metal detector.

Embodiment

Below in conjunction with accompanying drawing the present invention is elaborated.

As shown in Figure 1, the present invention discloses a kind of receiving coil of door type metal detector, comprises skeleton 1 and coil 2.

Skeleton 1 is a plastic material, form axisymmetricly, and promptly axisymmetric two ends shape is identical, equal and opposite in direction; Skeleton 1 can be one-body molded, also can be as shown in this embodiment, form by two shapes, all

identical support body

11 and 12 of size, herein for the ease of being provided with, two

support bodys

11,12 can be arranged at the dull and stereotyped (not shown) of going up in the rotational symmetry mode, so just can realize the same moved further of two

support bodys

11,12, handled easily when making debugging improves debugging efficiency.

Coil 2 is to use enameled wire to be wrapped on the skeleton 1 in 8 font modes, specifically, supposes that lead is from the A point, at first wind with one circuit with counter clockwise direction along support body 11, and then wind with one circuit in a clockwise direction along support body 12, so promptly finish a circle coiling, again with same winding mode, until reaching the number of turns that needs, finish to the B point, as shown in Figure 1, the coil 2 that obtains with this kind winding mode, can guarantee to twine the number of turns and equate, meet the requirement of receiving coil in the metal detector.

The present invention in use, with reference to shown in Figure 2, the coil 2 that is wrapped on two

support bodys

11,12 can equivalence be the L2 among the figure, transmitting coil L1 is positioned at the centre of two receiving coil L2, transmitting coil L1 forms the high frequency alternating electromagnetic field around receiving coil L2, when not having metal object near receiving coil, only provide direct supply by VCC in the circuit, the AC signal that the negative terminal of operational amplifier U1A receives is 0, and this moment, the output terminal of U1A did not have detection signal output; As metal object when the receiving coil, destroy () symmetry of transmitting coil both sides alternating electromagnetic field, the AC signal balance that receiving coil L2 receives is destroyed, produce exchange current in the circuit, make detected signal of operational amplifier U1A output, drive follow-up warning circuit (topworks) and report to the police; And when other electromagnetic interference (EMI) occurring, because the undesired signal equal and opposite in direction that receives of two groups of coils 2 among the receiving coil L2, direction is opposite, so the output of the output terminal of operational amplifier U1A still is 0, can not produce the situation of maloperation.

In addition, receiving coil that can also several are disclosed carries out evenly distributed installation, the number of selected receiving coil and concrete arrangement mode can determine according to the zone that reality need be surveyed, as using Security Inspection Office AT STATION, can one group of received coil respectively be set in the top, middle part and the bottom side of inlet, just can carry out comprehensive safety inspection to the passenger of process, improve checking efficiency, testing result is more accurate.

In sum, the receiving coil of door type metal detector of the present invention, focus on in the prior art respectively two groups of coils of coiling be combined into receiving coil again, change into two groups of coils be wrapped on one and the axisymmetric skeleton, make two groups of coils to move simultaneously, be convenient to debugging; And adopt the winding mode of 8 fonts, and guarantee that the number of turns of two groups of coils making equates, size shape is identical, thereby guarantee the consistance of two groups of winding inductance quantities to the full extent, make testing result accurate, highly sensitive.Above embodiment only for explanation technological thought of the present invention, can not limit protection scope of the present invention with this, every technological thought that proposes according to the present invention, and any change of being done on the technical scheme basis all falls within the protection domain of the present invention.

Claims

1, a kind of receiving coil of door type metal detector is characterized in that: comprise axisymmetricly skeleton and coil, coil is wrapped on the skeleton in 8 font modes.

2, the receiving coil of door type metal detector as claimed in claim 1 is characterized in that: described skeleton is combined in the rotational symmetry mode by two shapes and the identical support body of size.

3, the receiving coil of door type metal detector as claimed in claim 2 is characterized in that: described support body is fixedly installed on the flat board.