JPS6035711B2 - magnetic signal detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic signal detection device that uses a magnetoresistive element to read magnetic signals written on a magnetic card such as a thin rubber magnet sheet.

Conventionally, as a magnetic card system using a rubber magnet sheet, a permanent magnet pen is used to input information, and when reading information, a saturable coil is arranged according to the magnetization pattern of the magnetic card. A method has been proposed to detect changes in the impedance of the saturable coil, but this method requires peripheral circuits such as an oscillation circuit and a detection circuit in order to flow alternating current through the saturable coil, resulting in high cost. There is a limit to the size of the disk, and there are drawbacks such as the inability to increase the recording density.

The present invention uses a magnetic card in which N (N is an integer of 2 or more) magnetizations are attached in a predetermined arrangement format within the surface of the magnetic card so that the direction of each magnetization defines the information content, In particular, at the time of the proposal, these magnetic cards are arranged facing each other and arranged in an array format corresponding to the predetermined array format.
magnets, and each set is provided with a bias magnetic field by each of the N magnets, and each magnetoresistive element of each set is provided between the N magnets and the N magnetizations, and each set is provided with a bias magnetic field by each of the N magnets. N sets of two serially connected magnetoresistive elements arranged opposite to the corresponding magnetic poles of each magnetization, and a direct current applied to both ends of each set of two serially connected magnetoresistive elements. A magnetic signal detection device is provided that includes a voltage source and N output sections connected to the connection midpoints of each set of two series-connected magnetoresistive elements.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 indicates a magnetic detection section, and the N-pole surface of permanent magnets 2, 2 (
Two series-connected magnetoresistive elements M, , M2 are arranged on the magnetic field (or S pole surface).

As the magnetoresistive elements M, M2, a high mobility semiconductor such as indium antimonide lnSb can be used. A DC voltage V is applied to both ends of the two magnetoresistive elements M, , M2, and an output terminal 3 (FIG. 2) is taken out from the intermediate connection point. The permanent magnets 2, 2 are for applying a magnetic bias to the magnetoresistive element M, . 4 is a magnetic card (Fig. 3) formed of a rubber ferrite magnet sheet, and a predetermined portion is magnetized to form a magnetic signal portion 5, 5...
It forms...

These magnetic signal sections 5, 5...... each have N
It consists of a pair of magnetized parts, a pole and an S pole, and is associated with a "1" or "0" signal depending on their positional relationship. In the case of this embodiment, N/S is "1" and S/N is "1". 0”. FIG. 4 shows the operation of writing signals to the magnetic sheet 4,
Magnetic signal sections 5, 5, . . . are formed using a magnetizing head 6 at predetermined positions on a sheet 4 made of a rubber magnet sheet. Note that magnetization can also be achieved by using an ordinary permanent magnet 6' instead of an electromagnet such as the magnetizing head 6. The distance between these two pairs of magnetized portions having different polarities is approximately equal to the distance between the magnetoresistive elements M, , M2 of the detection unit 1. Therefore, when the magnetic card 4 is moved along the detection section 1, the two magnetized portions of the magnetic signal section 5 are connected to a pair of magnetoresistive elements M. , M2 (in the figure), and the bias magnetic field is disturbed. That is, the magnetic field applied to the magnetoresistive elements M, , M2 becomes weaker when the magnetic signal portion has the same magnetic pole as the bias magnetic field, and becomes stronger when the magnetic signal portion has the opposite magnetic pole. For example, if the bias magnetic field is set to the north pole and the magnetic signal section 5 moves to the north pole under the magnetoresistive element M, and the south pole to the other magnetoresistive element M2, the resistance of the magnetoresistive element M decreases. However, the resistance of magnetoresistive element M2 increases. The resistances of the magnetoresistive elements M, , M2 are respectively R
,,R2, the output signal from output terminal 3 is R2
It is expressed as 10△R2 V+=RI+R2-△RI+R2・V ~ 3rd base base-V.

Here R. R2=R, △R, △R2 and △R (increase/decrease in resistance). On the other hand, if the signal on the magnetic sheet 4 side is reversed, v-=3rd base. An output signal of v is obtained.

These output signals V+ and V- are input to a comparator circuit 7 shown in FIG. 2 and converted into digital signals, and a binary code signal is obtained from its output terminal 8.

Also, if the magnetic card 4 is not magnetized, or
When the same magnetic field is applied to the two magnetoresistive elements M1 and M2, V is applied to the output terminal 3. ＝A signal called wife appears,
If this value is also used, it is possible to obtain a three-value code signal from V-, Vo, and V+.

FIG. 5 shows another embodiment of the present invention, in which bias magnetic fields of a plurality of detecting sections, for example, three detecting sections, 12, 13 are set in advance, and a magnetic card is written with a corresponding predetermined signal. It was used as a power signal signal that detects only 4 and outputs a matching signal.

In the figure, a bias magnetic field of a north pole is applied to the detection part 1, and a bias magnetic field of a south pole is applied to the detection parts 12 and 13, respectively. Therefore, only when the magnetization signal sections 5, 5, and 5 formed in the magnetic force field 4 are magnetized in the relationship of N.S., S.N., and S.N., the detection sections 1, 12, and 13. All of them become the output signal V+, and a coincidence signal is outputted via the AND gate 9 shown in FIG. With this kind of structure, peripheral circuit parts such as a diode matrix or ROM are not required, compared to a device that sets a specific code in a diode matrix or ROM like a conventional verification machine, reads the card code, and then compares and verifies it. It is. That is, in the above example, if the direction of the magnetic bias is determined in advance according to the verification code,
Since an output is obtained from the AND gate 9 when the code of the card and the code of the detection unit match, a complicated judgment circuit is not required. Such an embodiment is practical in application to electronic door locks, for example. In summary, the magnetic signal detection device of the present invention applies a predetermined bias field to two serially connected magnetoresistive elements, and approaches the element and a magnetic card having a pair of magnetic pole portions formed corresponding to the elements. The system detects changes in the strength of the bias magnetic field applied to both elements and reads out the signal in the magnetization signal section as a logic signal of "1" or "0", so it is suitable for conventional AC-driven detection devices using saturable coils. Compared to this, oscillation circuits, detection circuits, etc. are not required, and even when used as a matching device, it can be easily configured by changing the magnetization bias as appropriate and installing one AND gate, resulting in a significant cost reduction. can do.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a circuit block diagram of the same example, Fig. 3 is a front view of a magnetic card used in the same example, and Fig. 4 is a view of a magnetic sheet. A diagram showing the operations to
FIG. 5 is a schematic diagram illustrating another embodiment of the present invention, and FIG. 6 is a circuit block diagram of the same example. 1...Magnetic detection unit, 2...Permanent magnet,
M,, M2... Magnetoresistive element, 3, 8...
...Output terminal, 4...Magnetic card, 5...
Magnetic signal section, 7... Comparator circuit. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A magnetic card in which 1 N (N is an integer of 2 or more) magnetizations are attached in a predetermined array within the surface of the magnetic card so that the direction of each magnetization defines the information content. and N magnets arranged opposite to the magnetic card in an array format corresponding to the predetermined array format, and arranged between the N magnets and the N magnetizations, two magnetoresistive devices connected in series, each set being provided with a bias magnetic field by each of the N magnets, and each magnetoresistive element of each set being arranged opposite to the corresponding magnetic pole of each magnetization; N sets of elements, a DC voltage source applied across the two serially connected magnetoresistive elements of each set, and two serially connected magnetoresistive elements of each set.
A magnetic signal detection device comprising N output sections connected to connection midpoints of N magnetoresistive elements. 2. In claim 1, a plurality of magnetic detection sections are provided, the direction of a bias magnetic field applied to each magnetic detection section is made different, and the output signal of each magnetic detection section is inputted to an AND gate, A magnetic signal detection device characterized in that a matching signal is output from an AND gate only when a magnetic card on which specific information corresponding to the detection section is written is detected.