JPH02144765U

JPH02144765U -

Info

Publication number: JPH02144765U
Application number: JP4969390U
Authority: JP
Priority date: 1990-05-10
Filing date: 1990-05-10
Publication date: 1990-12-07
Also published as: JPH0428059Y2

Description

[Brief explanation of drawings]

第１図は本考案の基礎となる構成を示す回路図
、第２図は周波数に対応した２次コイル３の起電
力を示すグラフ、第３図は１次コイル２次および
２次コイル３の位置関係を示す図、第４図は１次
コイル２および２次コイル３の第３図と異なる位
置関係を示す図、第５図は本考案の一実施例の検
出部１を示す回路図である。１……検出部、２……１次コイル、３，３ａ，
３ｂ……２次コイル、４，Ａ，Ｂ，Ｃ……金属片
、５……第１発振器、６……第２発振器、７……
第１バンドパスフイルタ、８……第２バンドパス
フイルタ、９……第１比較器、１０……第２比較
器、１１……第１基準電源、１２……第２基準電
源、１３……処理回路、１８……検出手段。 Fig. 1 is a circuit diagram showing the basic configuration of the present invention, Fig. 2 is a graph showing the electromotive force of the secondary coil 3 corresponding to frequency, and Fig. 3 is a graph showing the electromotive force of the secondary coil 3 of the primary coil and the secondary coil 3. FIG. 4 is a diagram showing the positional relationship between the primary coil 2 and the secondary coil 3, which is different from that in FIG. 3. FIG. be. 1...Detection unit, 2...Primary coil, 3, 3a,
3b... Secondary coil, 4, A, B, C... Metal piece, 5... First oscillator, 6... Second oscillator, 7...
1st band pass filter, 8...2nd band pass filter, 9...1st comparator, 10...2nd comparator, 11...1st reference power supply, 12...2nd reference power supply, 13... Processing circuit, 18... detection means.

Claims

[Claims for Utility Model Registration] (a) A detection unit 1 having a single primary coil 2 and a pair of secondary coils 3a, 3b, wherein the pair of secondary coils 3a, 3b are connected to these two coils. 3a and 3b are connected in series so that the polarities are opposite to each other. To detect metal pieces A, B, and C that are magnetically coupled so that the output voltage from the pair of secondary coils 3a and 3b becomes zero when pieces A, B, and C are not present. (b) a first oscillator 5 that supplies an oscillation voltage of a first frequency f1 to the primary coil 2; (c) a first oscillator 5 that supplies an oscillation voltage of a first frequency f1 to the primary coil 2; a second oscillator 6 that supplies an oscillation voltage of two frequencies f2; and (d) a first filter that allows only the output voltage of the first frequency f1 to pass among the output voltages of the pair of secondary coils 3a and 3b. 7, (e) a second filter 8 that allows passage of only the output voltage of the second frequency f2 among the output voltages of the pair of secondary coils 3a and 3b; and (f) a first discrimination level V1. (g) a second reference power source 12 that generates a second discrimination level V2; and (h) a first reference power source 11 that generates a second discrimination level V2; a first comparator 9 that performs level discrimination based on the level V1 and outputs a binarized signal based on the level discrimination result; (i) a first comparator 9 that performs level discrimination based on the level discrimination result; a second comparator 10 that performs level discrimination based on the level V2 and outputs a binarized signal based on the level discrimination result; (j) the metal at a predetermined position in relation to the detection section 1; (k) in response to the output from the detection means 18, when the metal pieces A, B, C are detected, each of the comparators a processing circuit 13 that discriminates and outputs the types of metal pieces A, B, and C based on a combination of binary signals from 9 and 10; Output levels EA1, E for each frequency f1, f2 corresponding to at least three types of metal pieces A, B, C
B1, EC1; EA2, EB2, EC2,
Two approximate values EA1, EB1; EB2, EC
2 and their values EA1, EB1; EB2, EC
A detection device for a metal piece, characterized in that the values are determined between another value EC1 and EA2 which are separated from EC1 and EA2.