JPH01169707A - Magnetic head circuit for recording on special medium - Google Patents

Abstract

PURPOSE:To limit data write capability to write on a magnetic recording such as magnetic card, etc., with a simple constitution and thereby to prevent a sly use of a counterfeit by connecting a slicing circuit between both terminals of a winding around a magnetic core having a gap. CONSTITUTION:Between the two terminals (1), (1)' of the winding 2 around the magnetic core 1 having a gap, the slicing circuit 3 is connected. The circuit 3 consists of two rectifying elements (including a diode, a Zener diode, and another with a coil) D1, D2 in opposite directions to each other connected in parallel, and is connected to the external circuit through input terminals (2), (2)'. Even when a write signal in high voltage is impressed to the terminals (2), (2)' of the circuit 3, the voltages of the terminals (1), (1)' do not go higher than a slicing level, hence by using a head whose winding is so specified as able to write on a prescribed magnetic recording medium, writing on a medium having a higher coercive force than that of said medium can be disabled, thus the use of a counterfeit card can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic head, and particularly to a magnetic head circuit for recording on a specific medium used for recording on a magnetic recording medium such as a magnetic card having a specific coercive force. It is related to.

[Conventional technology]

Recently, magnetic cards such as cash cards, telephone cards, and cresotto cards have become widespread, and it is said that the era of cards has arrived. With the spread of magnetic cards, magnetic card readers/writers have become easily available to people who write data on magnetic cards. For this reason,
Measures to prevent counterfeiting of magnetic cards are urgently needed.

Conventional measures to prevent counterfeiting of magnetic cards have been taken by improving the recording signal system used when recording data on magnetic cards, or by improving the structure of the magnetic head.

[Problem that the invention seeks to solve]

However, at present, there is no single method that is perfect for preventing counterfeiting, and counterfeit prevention measures are currently being taken that combine the above-mentioned methods.

The present inventors believe that the reason why conventional measures cannot completely prevent counterfeiting of magnetic cards is that conventional magnetic heads have the ability to write to magnetic cards of any coercivity. I thought.

Therefore, an object of the present invention is to improve the structure of the magnetic head to eliminate the function of writing data to a magnetic recording medium having a higher coercive force than a magnetic recording medium such as a magnetic card having a specific coercive force. An object of the present invention is to provide a magnetic head circuit for recording on a specific medium.

Remaining days below [Failure to solve the problem] A magnetic head circuit for recording on a specific medium according to the present invention is as follows.

It is characterized in that a slice circuit is connected between both terminals of a winding wound around a magnetic core having a gear rough 6.

[Operation] According to such a configuration, when writing data to a magnetic recording medium, when a voltage signal waveform is applied between the windings via the slice circuit, a part of the stain pressure signal waveform is applied to the slice circuit between the two windings. A voltage waveform with a thin cut is obtained. This is because the current flowing through the winding due to this thin-cut voltage is limited to a constant value.

The leakage magnetic field near the gear lug of the magnetic core is constant.

It is possible to magnetize only the magnetic recording medium that causes magnetization reversal due to the leakage magnetic field. Therefore, with this magnetic head circuit, it is possible to write data only to a magnetic recording medium having a specific coercive force.

Even if you try to record on a magnetic recording medium with a high coercive force using this specific medium recording magnetic head circuit and apply a larger signal voltage, the voltage will be canted by the slice level of the slice circuit, so Only slice-level voltage is applied to. Therefore, this specific medium recording magnetic head circuit cannot record on a magnetic recording medium having a high coercive force.

〔Example〕

Two embodiments of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, a magnetic head circuit for recording a specific medium according to a first embodiment of the present invention consists of a magnetic core 1 having a gap of 7° and a winding 2 wound around the magnetic core 1. It has a magnetic head. A slice circuit 3 is connected between both terminals ■-■' of the winding 2.

The slice circuit 3 of this embodiment has both terminals of the first winding 2 -■'
In between, two diodes D1 and D2 are connected in parallel in opposite directions. In an actual specific medium recording magnetic head circuit, the magnetic head and the slice circuit 3 are integrated. That is, the terminals ■-■' of the slice circuit 3 connected to both terminals ■-■' of the first winding 2 are connected to an external circuit as input terminals of the magnetic head circuit for recording on this specific medium.

A case will be explained in which data is written to a magnetic recording medium such as a magnetic card by flowing current from an external circuit using the magnetic head circuit for recording on a specific medium (FIG. 1).In this case, the voltage between the terminals Even if a high-level write signal is applied, the slice circuit 3 will cause the terminals of the winding 2 to
The voltage between them does not rise above about 0.7V, which corresponds to the forward voltage drop of a typical diode.

Now, if the circuit resistance of the first winding 2 is set so that the leakage magnetic field from the gap of the magnetic core generated by this voltage is sufficient to reverse the magnetization of a magnetic recording medium having a specific coercive force, then Recording can be performed on this recording medium.

Furthermore, even if a high-voltage write signal is applied between the terminals (1) and (2), the voltage between the terminals does not rise above the slice level, so the leakage magnetic field from the gap in the magnetic core does not increase.

Therefore, as winding 2 of the magnetic head, its terminal voltage is 0.
．． If you use one with wire-wound specifications that allows data to be written to a specified magnetic recording medium at 7V.

Using the specific medium recording magnetic head circuit of this embodiment, it becomes impossible to write data to other magnetic recording media having a coercive force higher than a predetermined coercive force, and it is possible to prevent counterfeiting of magnetic cards.

Note that the present invention is of course not limited to the above embodiments. For example, as shown in FIG. 2, capacitors C1 and C2 are added in series with diodes D1 and D2, respectively, as shown in FIG.

Resistors R1 and R2 may be added. Also, as shown in FIG. 4, Zener diodes zD1 and zD2 may be used instead of the two ordinary diodes D1 and D2,
As shown in FIG. 5, transistors Tr and T
r2 may also be used. Furthermore, as shown in FIG. 6, two sets of two diodes connected in series may be connected in parallel with opposite polarities. Alternatively, one bidirectional diode may be used as the slice circuit. Note that, in the case of an Ipn junction diode, this bidirectional diode can be easily manufactured by increasing the impurity concentration so that the reverse breakdown voltage is approximately the same as the forward voltage drop. Still another embodiment is shown in FIG. This is a coil connected in series with two diodes.

This is to improve the rising edge 9 of the write signal applied to the winding 2. That is, as the frequency of the write signal becomes higher, the inductance of the winding 2 becomes more important as a resistance component, resulting in a slower rise. Therefore, by inserting a suitable coil Lt on the diode side, it is possible to increase the impedance on the diode side during startup and improve the startup on the winding 2 side. In addition to the above-mentioned embodiments, there are also two
Of course, various modifications are possible.

〔Effect of the invention〕

According to one aspect of the present invention, as is clear from the above description.

A simple structure in which a slice circuit is connected between both terminals of a winding wound around a magnetic core with a gap can limit the ability to write data to a magnetic recording medium such as a magnetic card. Therefore, the magnetic head circuit for recording on a specific medium according to the present invention is highly effective in preventing counterfeiting of magnetic cards.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. FIG. 2 is a circuit diagram showing a second embodiment of the invention, FIG. 7 is a circuit diagram showing a sixth embodiment of the invention, and FIG. 7 is a circuit diagram showing a seventh embodiment of the invention.
It is a circuit diagram showing an example of. 1... Magnetic core, 2... Winding wire, 3... Slice circuit.

Claims (1)

[Claims] 1. A magnetic head having a magnetic core with a gap and a winding wound around the magnetic core, characterized in that a slice circuit is connected between both terminals of the winding. Magnetic head circuit for recording on specific media. 2. The magnetic head circuit for recording a specific medium according to claim 1, wherein the slice circuit includes two rectifying elements connected in parallel in opposite directions between both terminals of the winding. 3. A magnetic head circuit for recording on a specific medium according to claim 2, wherein the rectifying element is a diode. 4. A magnetic head circuit for recording on a specific medium according to claim 2, wherein the rectifying element is a Zener diode. 5. A magnetic head circuit for recording on a specific medium according to claim 1, 2, 3, or 4, wherein the slice circuit includes a coil.