JPH089654Y2 - Metal detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a metal detector for detecting the presence or absence of foreign metal in an object to be inspected.

[Conventional technology]

First, an outline of a conventional metal detector will be described with reference to FIG. In this figure, 1 is an oscillator, 2 is a transmission coil connected to the oscillator 1, 3
a and 3b are receiver coils arranged to face the transmitter coil 2, and the receiver coils 3a and 3b are placed in the alternating magnetic field of the transmitter coil 2 so that their magnetic lines of force are equally linked. There is. 4a and 4b are induced voltages of the receiving coils 3a and 3b
_It shows the volume for adjusting the phase and amplitude of ₁ and ₂ , and it is usually _1-
It is set so that ₂ = 0. 5 is differential induced voltage ₁ −
Amplifier for amplifying ₂ , 6a and 6b are synchronous detectors for detecting ferrous and non-ferrous metals, 7a and 7b are analog filters of about 2 to 20Hz, 8 and 9 are synchronous signals supplied to the synchronous detectors 6a and 6b 2 shows first and second phase shifters forming Further, 10 is a discrimination circuit, which is a central processing unit (hereinafter referred to as CPU) 11,
It is composed of a ROM 12, a RAM 13, an I / O port 14, a bus 15 and the like.
_F and _s are synchronous detection signals.

In the metal detector having such a configuration, when the object W to be inspected passes between the transmitting coil 2 and the receiving coils 3a and 3b and the object W is mixed with the metal, the type of the metal (iron or iron A detection signal is generated in the discrimination circuit 10 by the non-ferrous metal.

This point 3 (a), will be described by a vector diagram of (b), normally, the receiving coils 3a, the induced voltage _{1, 2} 3b ₁ at the input side of the amplifier 5 - set such that ₂ = 0 However, when the inspection object W containing iron passes from the direction of the arrow, first, as shown in FIG. 3 (a), the induced voltage ₁ of the receiving coil 3a increases to ′ ₁ , and then , The induced voltage ₂ of the receiving coil 3b increases to ' ₂ . Therefore,
₁ - differential induced voltage of ₂ = _Df is input to the synchronous detector 6a, is detected by the synchronous detection signal _F of the same phase being supplied to the synchronous detector 6a.

On the other hand, when the inspected object W mixed with non-ferrous metal (stainless steel, aluminum, etc.) passes, an eddy current flows in the ferrous metal under the influence of the alternating magnetic field of the oscillator 1. Then, due to the effect of this eddy current, the induced voltages ₁ , ₂ of the receiving coils 3a, 3b are
Will change the phase.

That is, as shown in FIG. 3 (b), the receiving coil 3a
"If changes to _1, the differential induced voltage" phase of the induced voltage _{1 2} - ₂ = _DS, as shown, occur point shifted substantially 90 ° phase. Therefore, non-ferrous metal can be detected by phase detection in the synchronous detector 6b to which the synchronous detection signal indicated by _S , which is almost in phase with the differential induced voltage _DS , is supplied.

In the above metal detector, the product type data is stored in the RAM 13. That is, there are hundreds of types of the inspection object W, and adjustments are sequentially performed for each type, and the optimum adjustment values of the respective parts of the metal detector are stored in the RAM 13 as a result. As a result, even if the type of the inspection object W changes,
The optimum adjustment value can be taken out from the RAM 13 and automatically set to deal with it immediately.

[Problems to be solved by the device]

By the way, in a food packaging line in a supermarket or the like, there are often a plurality of inspection lines for detecting the metal in the packaging, and even if an optimum adjustment value adjusted in one inspection line is used in another inspection line, It couldn't be done easily. In addition, it is impossible to prevent the accident that the optimum adjustment value stored in the RAM 13 is lost due to consumption of the backup power supply or the like.

This invention was made in order to solve the above-mentioned problems, and by using a memory card, the optimum adjustment value obtained once can be used for all inspection lines without fail, and the backup power supply is consumed. It is an object of the present invention to provide a metal detector that does not lose stored contents.

[Means for solving the problem]

The metal detector according to the present invention comprises a readable and writable memory card as an external storage element of the central processing unit for storing the optimum adjustment value for metal detection with respect to the object to be inspected.

[Action]

In this operation, since the memory card which can be read and written is provided, the optimum adjustment value once adjusted in the inspection line is stored in the memory card, so that it disappears even when the backup power supply is exhausted. Never.

〔Example〕

FIG. 1 shows an embodiment of the present invention. Reference numeral 16 denotes a memory card provided by the present invention, which is directly connected to the bus 15 as shown in the drawing or through an I / O port not shown in the drawing. It is detachably installed. Other symbols are the same as those in FIG.

 Next, the operation will be described.

In the adjustment, a standard sample is used instead of the object W to be inspected.

Since a known metal piece is mixed in advance in this standard sample, optimum adjustment values such as product data are stored in the memory card 16 in the discrimination circuit 10. Once this adjustment is completed, the memory card 16 can be inspected with the same characteristics as it is or by copying it and using it for another inspection line.

[Effect of device]

As described above, according to the present invention, the read / write memory card that stores the optimum adjustment value for metal detection with respect to the object to be inspected is provided as the external storage element of the central processing unit. It can be used as a part of the product, and it becomes easy to write and read the contents of the internal memory such as product data and programs.If you want the product data to be the same on all inspection lines, copy the memory card. It has the advantage that it can be realized easily and the labor of adjustment can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a conventional metal detector, and FIGS. 3 (a) and 3 (b) are for explaining the detection operation of FIG. It is a block diagram for doing. In the figure, 1 is an oscillator, 2 is a transmitting coil, 3a and 3b are receiving coils, 4a and 4b are volumes, 5 is an amplifier, 6a and 6b are synchronous detectors, 7a and 7b are analog filters, and 8 and 9 are first. , Second phase shifter, 10 determination circuit, 11 CPU, 12 ROM, 13 RAM, 14 I
/ O port, 15 is a bus, 16 is a memory card.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-1-281266 (JP, A) JP-A-63-204151 (JP, A) JP-A 64-52552 (JP, A) Actual development Sho-64- 46810 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. An object to be inspected is passed between a transmission coil that generates an alternating magnetic field and a receiving coil that receives this alternating magnetic field, and the magnitude of a detection signal obtained by the receiving coil is determined by a central processing unit. In the metal detector for detecting foreign metal, the read / write memory card for storing the optimum adjustment value of metal detection for the type of the inspection object is provided as an external storage element of the central processing unit. And a metal detector.