RU24746U1 - MAGNETIC MEDIA RECORDING DEVICE - Google Patents

Description

Device for erasing recordings from a magnetic carrier

The utility model relates to the technique of erasing skids from magnetic media, in particular, hard and flexible disks, magneto-optical disks, magnetic tapes, etc.

As you know, information recorded on a magnetic medium corresponds to a certain sequence of sections of the surface of the medium (magnetic cells), in which the magnetization vectors

corresponding to bit zero MD and unit MT,

oriented in opposite directions parallel to the magnetic field H3 of the recording, which was recorded

information (hereinafter - the recording vector). Moreover, all cells are in stable magnetic states. The most common two types of recordings - parallel and perpendicular, differing in the orientation of the field vector

H3 records relative to the carrier plane. As a rule, on such

media, like hard drives manufactured before 1994 - 1996, flexible magnetic disks, magnetic tapes, parallel recording is performed, and on modern hard and

magneto-optical disks are perpendicular recording. The most common methods of erasing a record are demagnetization or magnetization of a magnetic carrier by exposing it to an external magnetic field.

A device is known for erasing records from a magnetic medium by exposing it to a saturating alternating magnetic field containing a constant component (1).

The disadvantage of this device is the low energy efficiency of the erasure due to the need to maintain during the entire erase cycle of an undamped field. Erasing information from the entire medium is ensured by sequentially moving the head along the entire medium, which makes it impossible to quickly erase the information.

A device for erasing recordings from a magnetic medium comprising a main circuit consisting of a constant voltage source, a solenoid and a capacitor connected alternately to a constant voltage source and a solenoid through a two-position switch, equipped with at least one additional circuit similar to the main one, and, at least two damping diodes, each of which is connected in parallel with each solenoid

contour. The solenoids of the main and additional circuits are installed with the possibility of orienting the intensity vectors of the generated magnetic fields, rotated relative to each other by an angle a not equal to 180 ° and 360 °, and the moments of connecting the capacitor to the solenoid in the main and additional circuits are shifted relative to each other (2), The basis of the operation of this device is the method of erasing recordings on a magnetic medium, which includes creating a magnetic field and exposing it to a magnetic medium until it is saturated with a series of unipolar pulses that create magnetic fields with different orientations of intensity vectors.

The disadvantage of this device is the difficulty of use, since in each case it is necessary to select both the orientation of the erasing fields and the time of connecting an additional circuit, which reduces the efficiency of this device. In addition, the device is characterized by high energy costs associated with the need to create a magnetic field with an amplitude that is greater than the saturation field of the magnetic material of the carrier.

Closest to the claimed device in technical essence is a device for erasing recordings from a magnetic medium, comprising a control unit and two circuits, each of

which contains a solenoid, a co-detector, a power source and a key, the control input of which is connected to the output of the control unit, and the solenoids are located so that the vectors of the magnetic fields they create are mutually perpendicular. The control unit alternately connects the solenoids of each circuit to a power source (3). The operation of this device is based on the method of erasing recordings on a magnetic medium, in which at least two pulses of mutually perpendicular magnetic fields lying in the plane of the carrier are applied to the medium, and both pulses do not overlap in time.

The disadvantages of this device is the limited scope, due to the fact that the pitting fields created by both solenoids lie in the plane of the carrier, that is, the device is ineffective for disk media with perpendicular recording. In addition, the device has low energy efficiency, which is associated with the need for multiple repetition of erasing pulses. This is caused by uneven erasing from different parts of the carrier due to the fact that the direction of the uniform field created by the solenoids turns out to be different with respect to the recording field in different parts of the carrier. Necessity

repeated repeating of erasing pulses is also associated with the fact that each of the field pulses acts independently of one another.

A common drawback of these devices is the low reliability of erasing due to the fact that the magnetization reversal of cells with different initial orientations of the magnetization vectors (corresponding to zero and one of the recorded binary code) occurs asymmetrically, i.e., the angles between the direction of the erasing field and

directions of the magnetization vectors Md and Mts substantially

vary. With imperfect rectangularity of the hysteresis loop of the magnetic carrier, this leads to a residual magnetization difference of these cells, which can be used to restore the recording.

The technical problem solved by this utility model is to increase the uniformity and reliability of erasing records from magnetic media, as well as to reduce energy costs.

This problem is solved in that in a device for erasing recordings from a magnetic medium, including a control unit and at least a first and a second circuit, each of which contains

a solenoid, a capacitor, a power source and a key, and the control input of the key of the second circuit is connected to the output of the etch block), and the solenoids are arranged so that the vectors of the magnetic fields they create in the region of the magnetic carrier are mutually perpendicular, according to a utility model, an amplitude-time sensor is introduced parameters of the magnetic field created by the solenoid of the first circuit, the output of this sensor is connected to the input of the control unit, while the solenoid of the first circuit is set so that the vector of the magnetic the first field in the placement of the magnetic carrier is perpendicular to the direction of the vector of the magnetic recording medium. The operation of the claimed device is based on the method of erasing recordings on a magnetic medium, in which at least two pulses of mutually perpendicular magnetic fields are shifted in time, and in the first pulse the magnetic field is oriented perpendicular to the recording vector, and its amplitude is set to exceed the coercive force of the magnetic carrier in the direction of the recording vector, in the second pulse, the magnetic field is oriented parallel to the recording vector, and its amplitude is set ivayut value exceeding the coercive force of the magnetic carrier in the direction, perpendicular to the direction of entry of the vector

this time of the second pulse on is selected in the interval from Tmax TO where Tmax is the moment of achievement in the first pulse

maximum magnetic field strength, TJ - moment

the time at which the magnetic field in the first pulse is reduced to a value equal to the coercive force of the magnetic carrier in a direction parallel to the recording vector.

In addition, the applicant considers it necessary to incorporate the following development and / or refinement of the totality of common essential features of a utility model related to particular cases of its implementation or use.

The solenoid of each circuit can be made of two cylindrical coils located coaxially with a gap between them, the coils of one solenoid have a diameter smaller than the diameter of the coils of the other solenoid and are located coils of the latter coaxially with them, while the coils of a smaller diameter are connected to each other so that the vectors the magnetic fields created by them on the axis of the magnetic fields are antiparallel, and the coils of large diameter are connected to each other in such a way that the vectors of the magnetic fields created by them in the region of the magnetic carrier are parallel.

The sensor amplitude-time parameters of the magnetic field can be made in the form of a sensor of the magnetic field strength.

The sensor amplitude-time parameters of the magnetic field can be made in the form of a sensor changes in time the magnetic field strength.

The sensor amplitude-time parameters of the magnetic field can be made in the form of a current sensor.

The sensor amplitude-time parameters of the magnetic field can be made in the form of a voltage sensor on the solenoid.

The sensor amplitude-time parameters of the magnetic field can be made in the form of a time interval sensor.

The essence of the utility model is illustrated by drawings.

In FIG. 1 shows the orientation of the erasing magnetic fields

Hj and H || relative to the recording vector Нз information on

magnetic carrier, as well as the orientation of the magnetization vectors corresponding to zero (Mts) and unity (Mts)

digital information for the case of perpendicular recording.

In FIG. 2 shows the time sequence for switching on the first and second pulses of erasing magnetic fields.

In FIG. 3 shows a block diagram of one embodiment of the proposed device.

In FIG. 4 shows an example implementation of a device with solenoids, each of which consists of two coils.

In FIG. 5 schematically shows the mutual arrangement of the coils of the solenoids and the magnetic carrier in the case of out-of-phase switching on of the internal coils, and also shows the configuration of the magnetic fields created by such solenoids.

In FIG. 6 shows an example of a first circuit of the proposed device with a sensor of the amplitude-time parameters in the form of a voltage sensor on the solenoid.

In FIG. 7 shows an example of a first circuit of the proposed device with a sensor of amplitude-time parameters in the form of a sensor of a change in time of the magnetic field strength.

In FIG. 8 shows an example of a first circuit of the proposed device with a sensor of amplitude-time parameters in the form of a time interval sensor.

For clarity, the applicant considers it appropriate to begin the description of the claimed device with an explanation of the principle underlying the operation of the claimed device, illustrated in FIG. I and FIG. 2. It consists in the fact that the magnetic medium 1 (Fig.

1) with a known orientation of the recording vector, Нз is affected by the nerve impulse of the magnetic field Н, oriented perpendicular to the recording vector Нз - The amplitude of the magnetic field

 exceeds the coercive force of the NSC carrier in the direction

recording vector. This field momentum transfers all magnetic cells to an unstable state with almost identical directions of the magnetization vectors along the direction

HJL field applied. Next, the magnetic carrier 1 is affected by the second magnetic field pulse Hc, which is oriented parallel to the recording vector H3 and turns on at a point in time lying in the range from Tmax nao ii (Fig. 2), where Tmax is the moment when the magnetic field Hj reaches its maximum intensity, TI is the moment time in which the magnetic field strength Hj decreases to a value equal to the coercive force HC || magnetic carrier in a direction parallel to the recording vector Нз. The amplitude of the magnetic field

the coercive force of the HCJ carrier in the direction perpendicular to the

recording vector. Starting from the moment of turning on the second field

the carrier is exposed to a magnetic field whose direction changes from the direction corresponding to the unstable position of the magnetization vectors of the magnetic cells in the direction of their stable state. This is because

the resulting field is the sum of the falling first HX and

the growing second NTs fields. Nri this is a complete

magnetization of the medium corresponding to the recording on its entire surface of bit zeros or ones (depending on

field direction НЦ), which corresponds to the erasure of the initial

information. When this principle is implemented by the claimed device, all the processes of magnetization reversal of magnetic cells corresponding to zero and one in the original record proceed in a symmetrical manner, which significantly reduces the difference in the residual magnetizations of the cells after the erasing process and, thus, increases the reliability of erasing digital information. Erase reliability can also be improved by repeating the indicated sequence of pulses, which can be

periodic. Energy costs are reduced due to the fact that there is no need to create magnetic fields that exceed the amplitude of the napping of the material of the magnetic carrier, which is two to three times the value of the coercive force.

After explaining the principle underlying the utility model, the applicant further provides a detailed description of the device.

The claimed device for erasing recordings from a magnetic medium contains the first and second circuits, respectively containing solenoids 2, 3 (Fig. 3), capacitors 4, 5, power supplies 6, 7 and keys 8, 9, a control unit 10 and a sensor 11 amplitude-time parameters of the magnetic field created by the solenoid 2 of the first circuit. The output of the sensor 11 is connected to the input of the control unit 10, and the output of the latter is connected to the control input of the key 9 of the second circuit. The solenoids 2 and 3 are arranged so that the vectors of the magnetic fields created by them in the region where the magnetic carrier 1 is placed are mutually perpendicular, while the vector of the magnetic field created by the solenoid 2 of the first circuit is perpendicular to the direction of the recording vector of the magnetic carrier in this region. The sensor 11 of the amplitude-time magnetic field parameters in this embodiment of the device is made in the form of a magnetic intensity sensor

loke (9

field, for example, in the form of a Hall sensor, a sensor based on nuclear magnetic resonance (NMR), a Faraday sensor, etc., and is located in the immediate vicinity of solenoid 2.

In the embodiment of the device shown in FIG. 4, each of the solenoids 2 and 3 is made of two cylindrical coils 12, 13 and 14, 15, respectively, located coaxially with a gap between them. The coils 12, 13 (FIG. 5) of the solenoid 2 of the first circuit have a diameter less than the diameter of the coils 14, 15 of the solenoid 3 of the second circuit and are located coaxially with them in the coils 14, 15. Coils

12, 13 are connected to each other so that the vectors created by them

I on the axis OO of the magnetic fields Hj are antiparallel, i.e.

directed towards each other, and coils 14, 15 are connected to each other so that the vectors of the magnetic fields created by them

H || in the area of placement of the magnetic carrier 1 are parallel.

The antiparallelism of the magnetic fields on the axis of the coils of smaller diameter is ensured by their antiphase inclusion if they are wound in one direction, or by in-phase inclusion if they are wound in different directions. In these cases, in the gap between the coils, into which the magnetic carrier 1 is interfered, there will be a radial magnetic field lying in the plane of the carrier 1.

(9

The described embodiment and the relative position of the coils of the solenoids 2, 3 of the first and second circuits are used for the case of erasing a record with a recording vector perpendicular to the plane of the carrier 1. In the case of erasing a record with a recording vector parallel to the plane of the carrier, the coils 12, 13 of the first circuit solenoid 2 have a diameter greater than diameter cat) Щ1ек 14, 15 of the solenoid 3 of the second counterfeiter. Coils 14, 15 are located in coils 12, 13 coaxially with them. Coils 12, 13 are connected to each other

another so that the vectors of the magnetic fields Hc they create in

the areas of placement of the magnetic carrier 1 are parallel, and the coils

14, 15 are connected to each other so that the vectors created by them

I on the OO axis of the magnetic fields Hj are antiparallel. Sensor

amplitude-time parameters of the magnetic field generated by the solenoid of the primary circuit, in the embodiment shown in FIG. 4, is made in the form of a current sensor 16 in the solenoid 2, for example, in the form of a resistor connected in series with the solenoid 2 in the first circuit.

Either a voltage sensor 17 (Fig. 6) included in the first circuit parallel to the solenoid 2, as shown in Fig. 2, can also be used as a sensor of the amplitude-time field parameters. 6, or parallel to capacitor 4, or sensor 18

(Fig. 7) changes in time and the magnetic field strength of the solenoid 2, located in the immediate vicinity of the latter. As the sensor 18 can be a miniature coil, the voltage on which is proportional to the time derivative of the magnetic field strength of the solenoid 2.

The last two versions of the sensor are due to the fact that the magnitude of the magnetic field in the solenoid 1 is directly proportional to the current in this solenoid and inversely proportional to the voltage on it.

With the known dependence of the magnitude of the magnetic field on time, which is determined by the structural characteristics of the circuit, that is, the inductance and shape of the solenoid 2, the capacity of the capacitor 4 and the power source 6, a time interval sensor 19 can be used as a sensor of the amplitude-time parameters of the magnetic field (Fig. 8 ), which starts simultaneously with the inclusion of key 8.

The device shown in FIG. 3, works as follows. In preparation for erasing, the capacitors 4, 5 through the keys 8, 9 are charged from power supplies 6, 7 to the rated voltage. The magnetic medium 1 from which the information with the known orientation of the recording vector is to be erased is placed in the erasure device so that the field of the solenoid 2 is for some hours oriented perpendicular to the recording vector. For example, if it is a hard disk (hard drive) with a perpendicular recording, then the lines of force of the magnetic field of the solenoid 2 must lie in the plane of this disk. When you switch the key 8, the capacitor 4 begins to discharge through the solenoid 2, in which the flowing current creates a magnetic field, the amplitude value of which exceeds the coercive force of the carrier in the direction of the recording vector. This is achieved by the appropriate choice of the number of ampere-turns of solenoid 2. In solenoid 2, a magnetic field varies in time, the amplitude-time characteristics of which are measured by the magnetic field sensor 11. The signal from the sensor 11 enters the control unit 10, which determines the time derivative of the output signal of the sensor 11 and, when the sign of the derivative is changed, generates a signal including the key 9. After connecting the capacitor 5 to the solenoid 3, a field appears, perpendicular to the field of solenoid 2, with an amplitude exceeding the value of the coercive force of the carrier in the direction perpendicular to the recording vector. This is also achieved by the appropriate choice of the number of ampere turns of the solenoid 3. From this moment, the carrier is affected by the c field from two solenoids. Since field 1 is decreasing, and field of solenoid 3

an increasing, total field vector is rotated 90 ° from the initial orientation. When the first pulse reaches the field

the maximum value that turns the coercive force of NSC into

direction of the recording vector, the magnetization vectors of the elementary magnetic cells, regardless of their initial orientation, are oriented perpendicular to the recording vector. In this position, they are in a state of unstable equilibrium. When they are exposed to a rotating field, they are transferred to a state of stable equilibrium, which corresponds to the complete magnetization of magnetic carrier 1, that is, recording on the entire carrier with either a bit unit or bit zero (depending on the direction of the solenoid field 3). Since the magnetization reversal of all magnetic cells is made from topologically close states corresponding to unstable equilibrium, there is practically no difference in the residual magnetization of the cells after the erasure is completed, which ensures complete erasure of the initial information.

The operation of the device of FIG. 4 occurs similarly to the operation of the device depicted in FIG. 3, except that in the device of FIG. 4 coils 12, 13 and 14, 15 solenoids create axially symmetric erasers

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magnetic fields, the configuration of which most closely matches the cylindrical symmetry of magnetic information carriers. Since the coils 12, 13 are turned on so that when the discharge current flows through them, the axial components of their magnetic fields are equal in magnitude and directed towards each other, they are mutually destroyed, while the radial components of the magnetic field of the coils 12, 13 are added. Thus, when current flows through the coils 12, 13 in the plane of the magnetic carrier 1, a powerful radial field is created (Fig. 5).

In the case of using a resistor as a current sensor 16 (Fig. 4) by selecting the value of the resistor, it is possible to reduce the quality factor of the first circuit to a value less than unity and thereby

get a unipolar magnetic field pulse HX. Output

the signal from the current sensor 16, proportional to the magnetic field strength, is supplied to the control unit 10, which, when the sign of the derivative of the signal from the sensor 16 is changed, turns on the key 9 and connects the capacitor 5 to the coils 14, 15 of the solenoid 3. When the discharge current flows through these coils the magnetic fields on their axis are directed in one direction and, folding, create a powerful magnetic field perpendicular

both the field of coils 12, 13 and the plane of the magnetic carrier 1. The diameter of the coils 14, 15 is larger than the diameter of the magnetic carrier, so the radial component of the field created by them does not affect the configuration of the resulting field formed during the erasure of the record. This embodiment of the solenoids can significantly reduce the gap in which the magnetic carrier 1 is placed, and obtain a radial magnetic field that is most concentrated in the plane of the carrier, which increases the uniformity of erasing the recording and reduces energy costs and reduces the scattering field.

The proposed device, in which the first circuit is made, as shown in FIG. 6, FIG. 7 and FIG. 8 operates similarly to the device of FIG. 3. Using the sensor 17 (Fig. 6) of the voltage on the solenoid of the first kontff avoids additional active losses in this circuit, which increases its quality factor and allows you to erase the recording in the mode of a damped sinusoidal field at the resonant frequency of the circuit. Just as it was described in general, the key 9 is turned on through the control unit 10 at the moments when the derivative of the signal from the sensor 17 passes through zero.

When used in the primary circuit of the sensor 18 (Fig. 7) changes in time of the magnetic field from block 10

control unit can be excluded the unit of differentiation of the input signal of the sensor, since the latter is a time derivative of the magnitude of the magnetic field in the solenoid 2.

The use of a time interval in the primary circuit of the sensor 19 provides for a preliminary measurement of the time dependence of the magnetic field of the solenoid 2, since this dependence is determined only by the parameters of the primary circuit, it can be considered unchanged and the moment of switching on the key 9 can be set by the output signal of the sensor 19, which counts the necessary time interval from turn on the key 8. In this case, the control unit 10 will contain only the power amplifier necessary to turn on the key 9. The use of the sensor 19 interval Time is advisable in those cases where, for reasons kakimlibo (high level of electrical interference at the time of discharge current flow, the sensor insufficient mechanical strength, space deficit) is undesirable to use the above sensors.

Thus, the claimed technical solution can significantly increase the reliability of erasing magnetic recordings by reducing the residual magnetization difference between the original bits of information, as well as reduce energy

(costs, because to erase a record of saturating fields.

Sources of information taken into account when preparing the application

1.Patent of Japan, No. 10293903, cl. G11B5 / 027, published. 1998 year

2. RF patent No. 2144223, cl. G 11 B 5/024, published. 2000 year

3. US patent No. 3143689, published. 1964 (prototype)

i oto;

Claims (7)

1. A device for erasing recordings from magnetic media, including a control unit and at least first and second circuits, each of which contains a solenoid, capacitor, power source and key, and the control input of the second circuit key is connected to the output of the control unit, and the solenoids are arranged so that the vectors of the magnetic fields created by them in the region of the magnetic carrier are mutually perpendicular, characterized in that a sensor of amplitude-time parameters of the magnetic field created by the solenoid Vågå circuit, this sensor output is connected to the input of the control unit, the solenoid of the first circuit is set so that the vector of the magnetic field created by them in the area of placement of the magnetic carrier is perpendicular to the direction of the vector of magnetic recording media.  2. The device for erasing recordings from magnetic media according to claim 1, characterized in that the solenoid of each circuit is made of two cylindrical coils located coaxially with a gap between them, the coils of one solenoid have a diameter smaller than the diameter of the coils of the other solenoid and are located in the coils of the last coaxially with them, while the coils of smaller diameter are connected to each other so that the vectors created by them on the axis of the magnetic fields are antiparallel, and the coils of larger diameter are connected to each other so that the vectors of the created by them agnitnyh fields in the placement of the magnetic carrier are parallel.  3. A device for erasing recordings from a magnetic medium according to claim 1 or 2, characterized in that the sensor of amplitude-time parameters of the magnetic field is made in the form of a sensor of magnetic field strength.  4. The device for erasing recordings from a magnetic medium according to claim 1 or 2, characterized in that the sensor of the amplitude-time parameters of the magnetic field is made in the form of a sensor of a change in time of the magnetic field strength.  5. A device for erasing recordings from a magnetic medium according to claim 1 or 2, characterized in that the sensor of the amplitude-time parameters of the magnetic field is made in the form of a current sensor.  6. A device for erasing recordings from a magnetic medium according to claim 1 or 2, characterized in that the sensor of the amplitude-time parameters of the magnetic field is made in the form of a voltage sensor on the solenoid. 7. A device for erasing recordings from a magnetic medium according to claim 1 or 2, characterized in that the sensor of the amplitude-time parameters of the magnetic field is made in the form of a time interval sensor.