JP2595863B2 - Transfer bias magnetic field generator in magnetic recording information copying machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording information copying apparatus.

[0002]

2. Description of the Related Art A magnetic recording information copying apparatus for transferring magnetic recording information recorded on a recorded magnetic recording medium to an unrecorded magnetic recording medium has been conventionally used. It is well known that various configurations such as a copying apparatus and a magnetic recording information copying apparatus using a magnetic field transfer method have been proposed. Then, when transferring the magnetic recording information recorded on the recorded magnetic recording medium to the unrecorded magnetic recording medium, the recorded magnetic recording medium (master tape) and the unrecorded magnetic recording medium (slave tape) Is passed in a direction perpendicular to the direction of the magnetic field in the bias magnetic field for transfer while keeping the magnetic surfaces of the magnetic recording media in close contact with each other, and is recorded on the recorded magnetic recording medium (master tape). The magnetic recording information copying apparatus according to the magnetic field transfer method described above, which transfers the recorded magnetic recording information to an unrecorded magnetic recording medium (slave tape), obtains a duplicate tape by a so-called 1: 1 dubbing method. The feature is that a duplicated tape can be obtained at a higher speed than in the case of the above.

FIG. 9 is a view showing a conventional example of a transfer bias magnetic field generator for a magnetic recording information copying apparatus using a magnetic field transfer system. In FIG. Is a head holder, and 4 is a magnetic head for generating a bias magnetic field. The magnetic head 4 for generating a bias magnetic field is a C-type head having a magnetic gap 4a. Reference numeral 5 denotes a soft magnetic drum. The soft magnetic drum 5 is rotated by a rotating shaft 6. The above-described magnetic head 4 for generating a bias magnetic field has a magnetic gap 4a.
Is provided on a component including the main head base 1 and the sub head base 2 so as to occupy a position separated from the outer peripheral surface of the soft magnetic material drum 5 by a minute distance. Side portions 1a and 2a of the main head base 1 and the sub head base 2 facing the outer peripheral surface of the soft magnetic drum 5 are spaced apart from the outer peripheral surface of the soft magnetic drum 5 by a small distance. It is configured as a face-to-face state.

[0004] Recorded magnetic recording medium (master tape) 7
The two recording media 7, 8 arranged along the outer peripheral surface of the soft magnetic drum 5 in a state in which the magnetic surfaces of the unrecorded magnetic recording medium (slave tape) 8 are in close contact with each other.
The soft magnetic drum 5 is pressed against the outer peripheral surface of the soft magnetic drum 5 by air ejected from air ejection holes provided in the main head base 1 and the sub head base 2. The recording media 7 and 8 running as described above and running as described above are provided with the soft magnetic drum 5 from the magnetic gap 4a of the C-type head constituting the magnetic head 4 for generating the bias magnetic field. The magnetic flux flowing in the direction passes. If the soft magnetic drum 5 is not disposed close to the magnetic gap 4a of the C-type head in the bias magnetic field generating magnetic head 4, the C The magnetic field component leaking from the magnetic gap 4a of the die head has a large horizontal component. When the soft magnetic drum 5 is disposed close to the magnetic gap 4a of the C-type head of the bias magnetic field generating magnetic head 4, the C Magnetic gap 4 of die head
The magnetic field component leaking from a has a large vertical component.
FIG. 10 shows leakage in a magnetic gap 4a of a C-type head constituting a magnetic head 4 in a conventional example of a transfer bias magnetic field generating device in a magnetic recording information copying apparatus shown in FIG. FIG. 9 is a characteristic curve diagram showing a result of a magnetic field strength distribution characteristic obtained by a model experiment, showing a perpendicular magnetic field component Hy in a leakage magnetic field from a magnetic gap 4 a of a C-type head constituting the magnetic head 4.
The state of the magnetic field intensity distribution of (Hy ′) depends on the center position of the magnetic gap 4a of the C-type head constituting the magnetic head 4 (FIG. 1).
This indicates a bimodal characteristic in which mountains are present on both sides with respect to (a position where 0 is written on the horizontal axis in 0).

A transfer bias magnetic field generator in a conventional magnetic recording information copying apparatus having a configuration as shown in FIG. 9 has a bimodal characteristic as indicated by a curve Hy shown by a solid line in FIG. However, in a magnetic recording information copying apparatus using a magnetic field transfer method, a transfer bias used when transferring magnetic recording information recorded on a recorded magnetic recording medium to an unrecorded magnetic recording medium is originally used. The required magnetic field strength distribution characteristics are shown in FIG. 10 by the magnetic air gap 4 in the magnetic head 4 composed of a C-type head.
Only the portion of the attenuation gradient in the magnetic field intensity distribution indicated by the mountain on the right side of the center position of a (the position indicated by 0 on the horizontal axis in FIG. 10), and the center of the magnetic gap 4a described above. Position (position where 0 is written on the horizontal axis in FIG. 10)
The portion of the magnetic field intensity distribution shown on the left side is not only a portion of the magnetic field intensity distribution unnecessary as a transfer bias magnetic field, but also a portion of this magnetic field intensity distribution recorded magnetic recording medium (master tape) When the recording medium 7 passes, there is a problem that the recorded magnetic recording medium (master tape) 7 is easily demagnetized.

[0006] In the characteristic curves of the magnetic field strength distribution shown in FIG. 10, the characteristic curves Hy and Hx of the magnetic field strength distribution indicated by solid lines correspond to the recorded magnetic recording medium (master tape) 7 and the unrecorded magnetic tape. Magnetic recording medium (slave tape) 8
The nozzle member formed in the vicinity of the magnetic head 4 is made of a non-magnetic material and a non-conductive material ( For example, a vertical magnetic field strength distribution characteristic curve Hy and a horizontal magnetic field strength distribution characteristic curve Hx obtained in the case of using ceramics). In the characteristic curves of the magnetic field intensity distribution shown in FIG. 10, the characteristic curves Hy ′ and Hx ′ of the magnetic field intensity distribution indicated by the broken line correspond to the recorded magnetic recording medium (master tape) 7 and the unrecorded magnetic recording medium (master tape). Nozzle formation provided to form a nozzle near the magnetic head 4 in order to blow air for pressing the magnetic recording medium (slave tape) 8 against the outer peripheral surface of the soft magnetic drum 5 Of the nozzle forming members N arranged on the left side of the magnetic head 4 in FIG.
B1 is a non-magnetic and non-conductive substance (for example, ceramics or the like), and is a nozzle forming member NB2 disposed on the left side of the magnetic head 4 in FIG.
Are a vertical magnetic field strength distribution characteristic curve Hy 'and a horizontal magnetic field strength distribution characteristic curve Hx' obtained when the material is nonmagnetic and made of a conductive substance (for example, aluminum alloy or stainless steel). .

In FIG. 10, the vertical magnetic field intensity distribution characteristic curve Hy 'and the horizontal magnetic field intensity distribution characteristic curve Hx' indicated by the broken line are compared with the vertical magnetic field intensity distribution characteristic curve Hy and the horizontal magnetic field indicated by the solid line. When compared with the intensity distribution characteristic curve Hx, the peak on the right side of the center position of the magnetic gap 4a (the position indicated by 0 on the horizontal axis in FIG. 10) in the magnetic head 4 composed of a C-type head. The curve shown by the broken line in the portion of the attenuation gradient of the magnetic field strength distribution shown is steeper than the curve shown by the solid line because the magnetic head 4 is located near the magnetic head 4. A demagnetizing field is generated which cancels out the lines of magnetic force penetrating the metal nozzle member, and an eddy current flows through the metal nozzle member. Center position This is because the field strength of the skirt portion of the attenuation gradient in the magnetic field intensity distribution shown in the right mountain is reduced than (the position on the horizontal axis are the representation of 0 in FIG. 10).

As described above, the attenuation gradient in the magnetic field intensity distribution indicated by the mountain on the right side of the center position of the magnetic air gap 4a in the magnetic head 4 (the position indicated by 0 on the horizontal axis in FIG. 10). When the slope of the curve at the bottom of the curve becomes steep, the area to which the transfer bias magnetic field is applied becomes narrower. Therefore, the recorded magnetic recording medium (master tape) 7 and the unrecorded magnetic recording medium (slave tape) 8 Can be narrowed in a magnetic transfer area that needs to be pressed against the outer peripheral surface of the soft magnetic drum 5 in a favorable state without vibration due to the air flow ejected from the nozzle. On the other hand, in the magnetic transfer region set to be narrow as described above, the transfer bias is set so that the bias magnetic field is inverted a predetermined number of times or more in the narrow magnetic transfer region. It will be necessary to select a high frequency of the current for generating the magnetic field.

If the metal nozzle member is arranged near the magnetic head 4 as described above, an eddy current flows through the metal nozzle member, so that the magnetic head 4 composed of a C-type head is formed. Increasing the slope of the tail of the attenuation gradient in the magnetic field intensity distribution indicated by the mountain on the right side of the center position of the magnetic air gap 4a (the position indicated by 0 on the horizontal axis in FIG. 10). Can be. However, when a metal nozzle member is arranged in the vicinity of the magnetic head 4, a large amount of eddy current is naturally generated, so that the transfer bias magnetic field generator is of low efficiency due to the eddy current. Also, when a high-frequency current is used for the above-described reason, the core loss of the magnetic material increases and the amount of heat generated increases, and the drive circuit also handles high-frequency current, so that it is expensive. There are problems such as the necessity of a simple one.

The soft magnetic drum 5, which is rotated by a rotary shaft 6 driven and rotated by receiving power from a power source (not shown), has the precision of a bearing for supporting the drum and the soft magnetic property. Depending on the degree of roundness of the body drum 5,
Eccentricity always occurs during rotation. Therefore, the intensity of the transfer bias magnetic field changes with the change in the distance between the position of the magnetic head in the transfer bias magnetic field generator and the outer peripheral surface of the soft magnetic drum 5, so that a good copy can be obtained. There is a problem that it is difficult to obtain. Further, in the conventional transfer bias magnetic field generator shown in FIG. 9, a passage for compressed air is provided on the side surface of the C-type head, but the magnetic head used is a C-type head. It is necessary to press the magnetic recording medium (master tape) 7 and the unrecorded magnetic recording medium (slave tape) 8 over a wide range on the outer peripheral surface of the soft magnetic drum 5 from the viewpoint of magnetic saturation of the core. Therefore, there is also a problem that a large amount of compressed air is required to press the recording medium against the outer peripheral surface of the soft magnetic drum 5.

As a transfer bias magnetic field generator having no such a problem in the conventional transfer bias magnetic field generator described above with reference to FIG. Has proposed a transfer bias magnetic field generator whose schematic configuration is shown in FIG. In FIG. 8, reference numeral 9 denotes a rotating magnetic cylinder whose at least the outer peripheral surface is made of a high-permeability magnetic material; 10 denotes a head block mounting member;
Mounting piece 10a provided with holes 1 and 12 and holes 13 and 1
4 is fixed to a predetermined mounting portion of the magnetic recording information copying apparatus by the mounting piece 10b provided with the magnetic recording information. A mounting member 15 for the transfer bias magnetic field generating magnetic head is fixed to the recess 10d provided in the head block mounting member 10 by screws 16 and 17.

The recess 10d provided in the head block mounting member 10 is provided in the head block mounting member 10.
When a lid plate (not shown) is fixed to the upper surface 10c of the head block, an air chamber into which compressed air is sent from a compressed air supply hole 18 provided on the rear wall of the head block mounting member 10 is formed. The compressed air sent into the air chamber formed by the concave portion 10d provided in the head block mounting member 10 is applied to the bias magnetic field mounted on the mounting member 15 of the transfer bias magnetic field generating magnetic head. The compressed air is ejected from compressed air jet ports 21 and 22 provided near the bias magnetic field generating main pole 19 in the transfer bias magnetic field generating magnetic head TBH including the generating main magnetic pole 19 and the core member 20. The compressed air ejected from the compressed air outlets 21 and 22 as described above is used for the master recording medium (recorded magnetic recording medium) and the slave recording medium (recorded magnetic recording medium) whose magnetic surfaces face each other. An unrecorded magnetic recording medium) is pressed against the outer peripheral surface of the rotating magnetic cylinder 9 near the tip of the main magnetic pole 19 for generating a bias magnetic field.

The transfer bias magnetic field generating magnetic head TBH, which is attached to the transfer bias magnetic field generating magnetic head mounting member 15, has its magnetic surfaces formed by compressed air blown out from compressed air jets 21 and 22. The part where the master recording medium (recorded magnetic recording medium) and the slave recording medium (unrecorded magnetic recording medium) facing each other are pressed against the outer peripheral surface of the rotating magnetic cylinder 9. On the surface set at a position close to the surface of the magnetic recording medium, at least the entire width of the magnetic recording medium is extended, and the tip surface shape is narrow in the running direction of the magnetic recording medium. Between the main magnetic pole 19 provided with the tip end face of the main magnetic pole for generating the bias magnetic field having the above, and the tip end of the main pole and the outer peripheral face of the rotating magnetic cylinder 9. The rotating magnetic cylinder is located at a position separated from the position of the main magnetic pole 19 for generating the bias magnetic field by an extremely large distance G as compared with the short distance g in the direction of the outer peripheral surface of the rotating magnetic cylinder 9. And a core member 20 configured to have a wide opposing surface when approaching the outer peripheral surface of the body 9.

Magnetic head TB for generating bias magnetic field for transfer
An excitation coil 23 is wound around a magnetic path between the main magnetic pole 19 and the core 20 at H.
Is supplied with a bias current of a predetermined frequency from a bias current supply circuit, and a magnetic flux detecting coil 24 for detecting magnetic flux in the main magnetic pole 19 is provided near the tip of the main magnetic pole 19 described above. Is wound, and a signal detected by the magnetic flux detection coil 24 is used to operate a circuit of an automatic control circuit that automatically controls the amplitude of the bias current so as to be a predetermined reference value. Is done. Between the main magnetic pole 19 and the core 20, there are provided block members 25 and 26 made of a non-magnetic insulator, and between the block members 25 and 26 and the core 20. Compressed air passages 31 and 32 connecting the already described air chamber (recess 10 d) and compressed air jets 21 and 22.
Is constituted.

In the transfer bias magnetic field generator proposed by the present applicant shown in FIG. 8, a magnetic surface of a recorded magnetic recording medium serving as a master recording medium and an unrecorded magnetic field serving as a slave recording medium are used. With the recording medium and the recording medium facing each other, at least the outer peripheral surface portion is brought into pressure contact with the outer peripheral surface of the rotating magnetic cylindrical body 9 made of a high-permeability magnetic material by air pressure, Main magnetic pole 19 in magnetic head TBH for generating bias magnetic field for transfer
Exciting coil 2 wound on a magnetic path between the coil and the core 20
A bias current of a predetermined frequency is supplied from a bias current supply circuit to the main magnetic pole 19 for generating a magnetic field and the outer peripheral surface of the rotating magnetic cylinder 9 whose outer peripheral surface is made of a high magnetic permeability material. When an alternating magnetic field of a predetermined frequency is generated as a transfer bias magnetic field during this time, the magnetic flux that penetrates the magnetic recording medium from the main magnetic pole 19 and reaches the rotating magnetic cylinder 9 passes through the rotating magnetic cylinder 9, The outer circumference of the rotary magnetic cylinder 9 from the position of the main magnetic pole 19 for generating the bias magnetic field by an extremely large distance as compared with the shortest distance between the tip of the main magnetic pole and the outer peripheral surface of the rotary magnetic cylinder 9. It is configured between the core member 20 and the rotary magnetic cylinder 9 which are configured to have a wide opposing surface in a position separated from the surface in a state close to the outer peripheral surface of the rotary magnetic cylinder 9. Return home Flows through via the magnetic path, the magnetic field intensity distribution in the vicinity of the main magnetic pole 19 described above may be something as shown in the upper part of FIG. In FIG. 8, Hy indicates a vertical magnetic field component, and Hx indicates a horizontal magnetic field component.

In the copying apparatus of magnetic recording information proposed by the present applicant shown in FIG. 8, the transfer bias magnetic field having a unimodal characteristic generated by the transfer bias magnetic field generator generates only once on the master recording medium. The demagnetizing effect can be prevented, and the magnetic flux detecting coil 2 provided near the tip of the main magnetic pole 19 for detecting the magnetic flux in the main magnetic pole 19
4 is effective for magnetic transfer by automatically controlling the amplitude of the bias current by a one-cycle automatic control circuit so that the signal detected by step 4 becomes a predetermined reference value and keeping the transfer bias magnetic field intensity constant. A transfer bias magnetic field having a single-peak characteristic such that most of the vertical magnetic field component is generated is a distance between the tip of the main pole 19 of the magnetic head TBH for transfer bias magnetic field generation and the outer peripheral surface of the rotating magnetic cylinder 9. However, even if it fluctuates due to various causes, the transfer bias magnetic field strength is always small, high efficiency that can be maintained at a predetermined value set in advance, and the consumption of compressed air is small. A bias magnetic field generator for transfer in a magnetic recording information copying apparatus having the above features can be provided.

[0017]

As described above, in the copying apparatus for magnetically recorded information proposed by the present applicant described with reference to FIG. 8, the magnetic head TB for generating a transfer bias magnetic field is used.
H is a distance G from the position of the main magnetic pole 19 for generating a bias magnetic field, which is an extremely large distance G as compared with the shortest distance g between the tip of the main magnetic pole 19 and the outer peripheral surface of the rotary magnetic cylinder 9. 9 is provided with a core member 20 configured to have a wide opposing surface in a state close to the outer peripheral surface of the rotating magnetic cylinder 9 from a position separated in the outer peripheral surface direction of the rotating magnetic cylinder 9. , An excitation coil 23 wound around a magnetic path between the main magnetic pole 19 and the core 20,
Due to the magnetomotive force (ampere turn) generated in the magnetic path in response to the bias current of a predetermined frequency supplied from the bias current supply circuit, the magnetic path of the portion where the exciting coil 23 is wound → the main magnetic pole 19 → Closed magnetic field such as the outer peripheral surface of the rotating magnetic cylinder 9 → the rotating magnetic cylinder 9 → the gap between the rotating magnetic cylinder 9 and the core member 20 → the core member 20 → the magnetic path where the exciting coil 23 is wound → A magnetic flux flows through the path, and a bias magnetic field having a magnetic field intensity distribution as shown in the upper part of FIG.
As described above, the transfer of the magnetically recorded information from the recorded magnetic recording medium formed by the H and the rotating magnetic cylinder 9 to the unrecorded magnetic recording medium is performed as described above.

The magnetic field generated in the gap between the main magnetic pole 19 and the outer peripheral surface of the rotating magnetic cylinder 9 in the transfer bias magnetic field generating magnetic head TBH shown in FIG. Although a magnetic field of a specific polarity is generated in an area Zm in which an upper part is hatched with a downward slanting line, a returning magnetic field of the opposite polarity is shown near the main magnetic pole 19 with a downward slanting line in the figure. Since the transfer magnetic field is generated in the hatched areas Zf and Zb and the transfer magnetic field is an alternating magnetic field, the magnetic field intensity distribution of the substantial magnetic field generated near the main magnetic pole 19 is shown by the composite magnetic field Ze in FIG. As described above, the magnetic field Ze is represented by the combined magnetic field Ze of the magnetic fields in the regions Zm, Zf, and Zb. The area of the area Zm and the areas of the areas Zf and Zb are expressed by the following equation: (area of the area Zm) = (area of the area Zf) + (area Zb)
Area).

Thus, when the transfer bias magnetic field generating magnetic head TBH shown in FIG. 8 is used,
The transfer bias magnetic fields applied to the recorded magnetic recording medium and the unrecorded magnetic recording medium in a state where the magnetic surfaces are superimposed face to face are equal to the above-described regions Zm and Zm.
The magnetic fields of f and Zb are synthesized, and a magnetic field having a monomodal but loosely distributed intensity distribution as shown by Ze in FIG. 11 is substantially applied. Then, the transfer bias magnetic field generating magnetic head TBH shown in FIG.
Is used, it is a problem that the magnetic flux passes through the magnetic recording medium and returns, as is apparent from the magnetic flux path described above. As described above, in the transfer bias magnetic field generating magnetic head TBH shown in FIG.
The core member 20 configured to have a large opposing surface in a state in which it is sufficiently separated from the outer peripheral surface of the rotating magnetic cylinder 9 and is close to the outer peripheral surface of the rotating magnetic cylinder 9 has a small return magnetic flux. Although the magnetic recording medium has a magnetic flux density, if the pressed state between the recorded magnetic recording medium and the unrecorded magnetic recording medium in a state where the magnetic surfaces are superimposed face to face changes, the recorded magnetic recording medium changes. The S / N of the magnetically recorded information copied from the recording medium to the unrecorded magnetic recording medium is degraded, or the magnetically recorded information is demagnetized.

The above problem will be described below with reference to FIG. FIG. 11 is an enlarged view of a part of the transfer bias magnetic field generating magnetic head TBH shown in FIG. 8, and the master recording is performed by compressed air ejected from the transfer bias magnetic field generating magnetic head TBH. The medium 7 and the slave recording medium 8 are pressed against the outer peripheral surface of the rotating magnetic cylinder 9 with the magnetic surfaces of the medium facing each other, and the transfer bias magnetic field generating magnetic head TBH and the rotating magnetic cylinder 9 face each other. Running in a magnetic field in the gap. Since the outer peripheral surface of the rotary magnetic cylinder 9 to which the recording media 7 and 8 are pressed against each other has a finite curvature, the compressed magnetic head TBH ejected from the magnetic head TBH for generating the transfer bias magnetic field is used. The portion of the recording medium pressed against the outer peripheral surface of the rotating magnetic cylinder 9 by air (the inner portion) near the rotating magnetic cylinder 9 is in a compressed state, and the outer portion is in an expanded state. Become. In FIG. 11, an arrow shown in the gap where the transfer bias magnetic field generating magnetic head TBH and the rotating magnetic cylinder 9 face each other, the above-mentioned recording media 7 and 8 are connected to the outer peripheral surface of the rotating magnetic cylinder 9. The arrows shown inside the two recording media 7 and 8 in the drawing indicate the stresses that cause the compressed and expanded states inside the recording media. Is shown. When the pressing force of the compressed air against the outer circumferential surface of the rotating magnetic cylinder 9 is no longer applied to the recording media 7 and 8, the recording media try to return to the original state. When the bias magnetic field is applied under the condition, the magnetic recording information copied from the master recording medium 7 to the slave recording medium 8 is demagnetized, the copy level of the magnetic recording information is reduced, and the copied magnetic recording information is reduced. However, there is a problem that the S / N is deteriorated, and the master recording medium 7 may be gradually demagnetized by being exposed to an unnecessary magnetic field. Thus, a solution to the above problem was sought.

[0021]

According to the present invention, a recorded magnetic recording medium serving as a master recording medium and an unrecorded magnetic recording medium serving as a slave recording medium are combined with each other by changing the magnetic surfaces of the two recording media. In a state facing each other, at least the outer peripheral surface portion is pressed against the outer peripheral surface of the rotating magnetic cylindrical body made of a high magnetic permeability magnetic material, and the thickness of the recording medium with respect to the pressed portions of the two recording media described above. A transfer bias magnetic field generator in a magnetic recording information copying apparatus, wherein a magnetic recording information of a master recording medium is copied to a slave magnetic recording medium by applying a transfer bias magnetic field in a direction. The first and second outer peripheral surface areas to which the recorded magnetic recording medium and the unrecorded magnetic recording medium in a state of being superposed face to face are pressed against each other. A rotating magnetic cylindrical body including a second outer circumferential surface region set at a position largely separated in the width direction of the magnetic recording medium with a gap therebetween, and a first outer circumferential surface of the rotating magnetic cylindrical body On the surface set at a position close to the surface of the area, the tip extends over at least the entire width of the magnetic recording medium, and has a narrow tip surface shape in the running direction of the magnetic recording medium. The main magnetic pole provided with the tip end surface of the main magnetic pole for generating the bias magnetic field as described above, and an extremely large distance compared to the shortest distance between the tip end of the main magnetic pole and the outer peripheral surface of the rotating magnetic cylinder. At a position spaced apart from the position of the main magnetic pole for generating the bias magnetic field in the width direction of the magnetic recording medium, a wide area is opposed to a portion of the second outer peripheral surface region of the rotating magnetic cylinder. To have a surface Transfer bias magnetic field generating apparatus in a magnetic recording information copying apparatus comprising a core member formed as described above, a recorded magnetic recording medium as a master recording medium, and an unrecorded magnetic recording as a slave recording medium With the medium and the magnetic surfaces of both recording media facing each other, at least the outer peripheral surface portion is pressed against the outer peripheral surface of a rotating magnetic cylinder made of a high-permeability magnetic material, and the two recording media are pressed against each other. Transfer of magnetically recorded information in a copying apparatus in which a transfer bias magnetic field in the thickness direction of the recording medium is applied to the pressed portion of the recording medium to copy the magnetically recorded information of the master recording medium to the slave magnetic recording medium. In a bias magnetic field generator for use, a recorded magnetic recording medium and an unrecorded magnetic recording medium in a state of being superposed with their magnetic surfaces facing each other are pressed against each other. A first outer peripheral surface region to be formed, and a second outer peripheral surface region set at a position largely separated from the first outer peripheral surface region via a space in the width direction of the magnetic recording medium. Extending over the entire width of the magnetic recording medium at least on a surface set at a position close to a surface of a portion of the first outer peripheral surface region of the rotating magnetic cylinder. A main magnetic pole provided with a front end surface of a main magnetic pole for generating a bias magnetic field having a narrow end surface shape in a running direction of the magnetic recording medium, and a front end of the main magnetic pole described above. At a position separated from the position of the main magnetic pole for generating the bias magnetic field in the width direction of the magnetic recording medium by an extremely large distance as compared with the shortest distance between the portion and the outer peripheral surface of the rotating magnetic cylinder. Second in rotating magnetic cylinder A magnetic flux detection coil for detecting a magnetic flux in the main magnetic pole, comprising: a core member configured to have a surface facing a wide area in a portion of the outer peripheral surface region; A circuit for automatically controlling the amplitude of the bias current so that the signal detected by the detection coil becomes a predetermined reference value; and A transfer bias magnetic field generator in a copying apparatus, and a recorded magnetic recording medium serving as a master recording medium and an unrecorded magnetic recording medium serving as a slave recording medium are placed on the same magnetic surface of both recording media. And at least the outer peripheral surface is pressed against the outer peripheral surface of a rotating magnetic cylinder made of a high-permeability magnetic material, and the pressure of the two recording media is reduced. A transfer bias magnetic field is generated in a magnetic recording information copying apparatus in which a transfer bias magnetic field in a thickness direction of a recording medium is applied to a portion to copy magnetic recording information of a master recording medium to a slave magnetic recording medium. In the apparatus, a first outer peripheral surface area to be pressed against a recorded magnetic recording medium and an unrecorded magnetic recording medium in a state where the magnetic surfaces face each other, and the first outer peripheral surface described above. A rotating magnetic cylinder configured to include a second outer peripheral surface region set at a position largely separated in the width direction of the magnetic recording medium via a space with respect to the region; 1
The end surface shape extends at least over the entire width of the magnetic recording medium and is narrow in the running direction of the magnetic recording medium on a surface set at a position close to the surface of the portion of the outer peripheral surface region of the magnetic recording medium. In comparison with the shortest distance between the main magnetic pole provided with the front end face of the main magnetic pole for generating the bias magnetic field having the above and the front end of the main magnetic pole and the outer peripheral surface of the rotating magnetic cylinder body, At a position separated from the position of the main magnetic pole for generating the bias magnetic field by a large distance in the width direction of the magnetic recording medium, a wide area is opposed to a portion of the second outer peripheral surface region of the rotating magnetic cylinder. A core member configured so as to have a surface having a curved surface, and an exciting current value detecting means for detecting a magnetomotive force for generating a magnetic flux flowing through the main magnetic pole, and the exciting current value. Detection means A magnetic recording information copying apparatus provided with a single-cycle automatic control circuit for automatically controlling the amplitude of the bias current so that the detected excitation current value becomes a predetermined reference value, and the transfer bias magnetic field intensity is kept constant. And a transfer bias magnetic field generator.

[0022]

With the magnetic surface of the recorded magnetic recording medium serving as the master recording medium and the unrecorded magnetic recording medium serving as the slave recording medium facing each other, at least the outer peripheral portion has high magnetic permeability. The two recording media are pressed against the outer peripheral surface of the rotating magnetic cylinder made of a magnetic material by air pressure. A first outer peripheral area to which a recorded magnetic recording medium and an unrecorded magnetic recording medium in a state of being superposed with their magnetic surfaces facing each other are to be pressed against each other, and the first outer peripheral area described above. The second position is set at a position largely separated in the width direction of the magnetic recording medium through the space.
The magnetic flux from the main magnetic pole, which is disposed to face the first outer peripheral surface region in the rotating magnetic cylinder configured to have the outer peripheral surface region, has a main magnetic pole → a magnetic surface facing each other. The recorded magnetic recording medium and the unrecorded magnetic recording medium in the superimposed state → the first outer peripheral surface area of the rotating magnetic cylinder → the inner part of the rotating magnetic cylinder → the second outer peripheral area of the rotating magnetic cylinder → rotation A recorded magnetic recording medium in a state in which the magnetic surfaces face each other and are superimposed on each other in order to flow in a path from the core member to the main magnetic pole arranged opposite to the second outer peripheral surface area of the magnetic cylinder. Since only the bias magnetic field near the main magnetic pole is applied to the unrecorded magnetic recording medium, the transfer of the magnetically recorded information from the recorded magnetic recording medium to the unrecorded magnetic recording medium is performed in a good state. Further, the amplitude of the bias current is cycled so that the signal detected by the magnetic flux detection coil provided near the tip of the main magnetic pole for detecting the magnetic flux in the main magnetic pole becomes a predetermined reference value. Automatically controlled by the automatic control circuit of
The bias current of the bias current is determined so that the transfer bias magnetic field intensity is constant or the exciting current value detected by the exciting current detecting means for detecting the magnetomotive force for generating the magnetic flux flowing through the main magnetic pole is a predetermined reference value. The amplitude is automatically controlled by a single-cycle automatic control circuit to make the transfer bias magnetic field strength constant, so that a constant bias magnetic field is always generated.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific contents of a transfer bias magnetic field generator in a magnetic recording information copying apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of a magnetic circuit in a transfer bias magnetic field generating device of the present invention, and FIG. 2 is an exploded perspective view of a transfer bias magnetic field generating magnetic head used in the transfer bias magnetic field generating device of the present invention. FIG. 3 is a diagram showing a magnetic head for generating a transfer bias magnetic field, FIGS. 4 to 6 are enlarged views of a part of the magnetic head for generating a transfer bias magnetic field, and FIG. 7 is a block diagram of a bias current supply circuit. . FIG. 1 shows a schematic configuration of a magnetic circuit in a transfer bias magnetic field generation device of the present invention. FIG. 1A shows a transfer bias magnetic field generation magnetic head TB.
FIG. 1B is a longitudinal sectional view of a state in which a portion H is combined with a portion of the rotating magnetic cylinder 29 in which at least the outer peripheral surface portion is made of a high-permeability magnetic material. FIG. 1C is a perspective view of a portion of the transfer bias magnetic field generating magnetic head TBH.

As the rotary magnetic cylinder 29, for example, a rotary drum made of compacted sintered ferrite exhibiting high magnetic permeability and configured as a grooved annular drum can be used. The illustrated rotating magnetic cylinder 29 is shown as having a radius of r, a thickness of t, a height of H, and having annular grooves 45 and 46 on the outer peripheral surface. The surface has a width of m in the center
The first outer peripheral surface region 29m and the second outer peripheral surfaces 29u and 29d are formed outside the grooves 45 and 46 described above. The first outer peripheral surface area 29m at the central portion of the rotating magnetic cylinder 29 is formed by a recorded magnetic recording medium serving as a master recording medium and an unrecorded magnetic recording medium serving as a slave recording medium. The outer peripheral surface portion which is pressed against the magnetic surfaces with the magnetic surfaces facing each other,
In the outer peripheral surface region 29m, the tip of the main magnetic pole 19 provided in the transfer bias magnetic field generating magnetic head TBH used as a pair with the rotating magnetic cylinder 29 is extremely spaced through the gap g. They are arranged facing each other in a state of being close to each other. The rotary magnetic cylinder 29 is driven and rotated without eccentricity by a rotary drive mechanism (not shown).

The details of an example of the structure of the magnetic head TBH for generating a transfer bias magnetic field are shown in an exploded perspective view of FIG. 2, and FIG. 1C shows the rotary magnetic cylinder 29 described above. And an upper core 27 having an arcuate end face 27a facing over a wide range of the second outer peripheral surface area 29u, and an arcuate end face 28a opposing over a wide range of the second outer peripheral surface area 29d of the rotating magnetic cylinder 29 described above. A lower core 28 having
Only the part of the back core 30 connecting the 7 and the lower core 28 and the main pole 19 provided at the center is shown. Reference numerals 43 and 44 in the figure denote non-magnetic members which are inserted into cutouts provided in portions corresponding to the position of the main pole 19 in the upper core 27 and the lower core 28. The non-magnetic members 43 and 44 are used to prevent a magnetic short circuit between the main pole 19 and the upper and lower cores 27 and the lower core 28.
Compressed air ejected from the transfer bias magnetic field generating magnetic head TBH to press the magnetic recording medium against the first outer peripheral surface region 29m of the rotating magnetic cylindrical body 29 from the notch portion provided in There is no such thing. 3A is a top view of the transfer bias magnetic field generation magnetic head, FIG. 3B is a front view of the transfer bias magnetic field generation magnetic head, and FIG. 3C is a transfer bias magnetic field generation. FIG. 2 is a side view of a magnetic head for use in the present invention.

In FIG. 2, reference numeral 47 denotes a head block mounting member.
Screws 8 and 49 are attached and fixed to predetermined attachment portions in the magnetic recording information copying apparatus. The lower core 28 of the transfer bias magnetic field generating magnetic head TBH, the spacer 50 made of a non-magnetic material, the nozzle portion 51 made of a non-magnetic material, the back core 30,
After assembling the non-magnetic air chamber member 52, the main magnetic pole 19 and the exciting coil 23, the upper core 27, the non-magnetic spacer 53, the fixing plate 54 and the like in this order, the whole is screwed. Stick. Reference numerals 55 to 66 in the drawing denote the screw holes and holes for screwing.

The main magnetic head 19 to which the above-mentioned excitation coil 23 is mounted has a state in which the tip of the main magnetic pole 19 is inserted into a through hole 68 provided in the front wall of the nozzle portion 51 made of a non-magnetic material. Thus, it is arranged in a notch 67 provided in the nozzle portion 51 made of a non-magnetic material. In the through hole 68 in the front wall of the nonmagnetic nozzle portion 51 into which the tip of the main magnetic head 19 has been inserted, compressed air outlets are provided on both sides of the tip of the main magnetic head 19 described above. It is formed. The notch 67 provided in the nonmagnetic nozzle 51 is also provided.
Constitutes an air chamber. The air chamber formed by the cutout portion 67 provided in the nonmagnetic nozzle portion 51 is formed in the nonmagnetic air chamber member 52 via a hole 69 formed in the back core 30. The compressed air is supplied from a compressed air supply port 71 formed in a rear wall 52a of the air chamber member 52 made of a nonmagnetic material. .

The compressed air supply port 7 formed in the rear wall 52a of the air chamber member 52 made of a non-magnetic material.
1 supplies compressed air, the compressed air is supplied from the air chamber 70 of the non-magnetic air chamber member 52 to the back core 30.
Hole 69 → air chamber formed by a cutout 67 provided in the nonmagnetic material nozzle portion 51 → both sides of the front end of the main magnetic head 19 in the through hole 68 in the front wall portion of the nonmagnetic material nozzle portion 51 Is ejected from the above-described ejection port through a path of a compressed air ejection port formed in the portion of the rotary magnetic cylinder 29, and is formed as a master recording medium on the surface of the first outer peripheral surface region 29m in the central portion of the rotating magnetic cylinder 29. The recorded magnetic recording medium and the unrecorded magnetic recording medium serving as the slave recording medium are pressed against each other with their magnetic surfaces facing each other and superposed.

Magnetic head TB for generating bias magnetic field for transfer
The H main magnetic pole 19 is pressed against the surface of the first outer peripheral surface area 29m at the central portion of the rotating magnetic cylinder 29 by the compressed air ejected from the compressed air ejection port. Wound on a magnetic path between the main magnetic pole 19 and the core 20, which is located on a surface set close to the surface of the magnetic recording medium already recorded) and the surface of the slave recording medium (unrecorded magnetic recording medium). By supplying a bias current having a predetermined frequency to the rotated excitation coil 23 from a bias current supply circuit described later with reference to FIG. A bias magnetic field having a predetermined magnetic field strength is generated in the gap g.

Then, the first outer peripheral surface area 29m to be pressed against the recorded magnetic recording medium and the unrecorded magnetic recording medium in a state where the magnetic surfaces face each other and overlap each other.
And second outer peripheral areas 29u and 29d which are set at positions far apart from the first outer peripheral area 29m via the space in the width direction of the magnetic recording medium. The magnetic flux from the main magnetic pole 19 disposed opposite to the first outer peripheral surface region 29m in the rotating magnetic cylindrical body 29 is recorded in a state where the main magnetic pole 19 → the magnetic surfaces face each other and are superimposed. And the unrecorded magnetic recording medium → the first outer peripheral surface area 29m of the rotating magnetic cylinder 29 → the inside of the rotating magnetic cylinder 29 → the second outer peripheral area 29u, 29d of the rotating magnetic cylinder 29 → The upper core 27 and the lower cores 27, 28 which are arranged to face the second outer peripheral surface areas 29u, 29d of the rotating magnetic cylinder 29.
→ Only the bias magnetic field in the vicinity of the main magnetic pole 19 is applied to the recorded magnetic recording medium and the unrecorded magnetic recording medium in a state of being superposed with their magnetic surfaces facing each other because they flow along the path of the main magnetic pole 19. Therefore, the transfer of the magnetically recorded information from the recorded magnetic recording medium to the unrecorded magnetic recording medium is performed in a good state.

FIGS. 4 and 5 show an example of the configuration of the main pole 19 of the transfer bias magnetic field generating magnetic head TBH used in the transfer bias magnetic field generating device in the magnetic recording information copying apparatus of the present invention. FIG. 3 is an enlarged side view of the vicinity of the tip of the magnetic pole 19, and the waveform diagram shown in the upper part of each figure shows the main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH shown in each figure; A recorded magnetic recording medium and an unrecorded magnetic recording medium in a state in which a magnetic field generated in a gap between the rotating magnetic cylinder 29 and the surface of the first outer peripheral surface region 29m are superposed with their magnetic surfaces facing each other. 5 shows a state on the time axis of the intensity of the alternating magnetic field applied to any specific portion of the two recording media when the vehicle travels at the speed v. In the drawing, the speed of the two magnetic recording media and the bias for generating the transfer bias magnetic field are set so as to form a magnetic field gradient such that a 14-wave alternating magnetic field attenuation waveform effective for magnetic transfer is obtained. An example in which the signal frequency is selected is shown.

The main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH shown in FIGS. 4 and 5 is oriented in the width direction of the first outer peripheral surface area 29m of the rotating magnetic cylinder 29 (in the drawing, the paper surface). 1), and has a predetermined length m (see FIG. 1) in the vertical direction).
A first component 19a having a predetermined width Tw in a circumferential direction of 9 m (horizontal direction in the drawing) and a tip 19b1 and a tip 19b1 at a position retracted from the tip 19a1 of the first component.
The second and third components 19b, connected at the side surface of the first component 19a so that c1 is located,
19c, and the outer surfaces 72, 73 of the second and third components 19b, 19c intersect at an acute angle with the side surface of the first component 19a. It has been. In the figure, 24 is the main magnetic pole 1
9 is a magnetic flux detecting coil for detecting the magnetic flux in the coil 9.

The main pole 19 shown in FIG.
Symmetrically with respect to the first component 19a of the second
This is an example of a configuration in which the components 19b and 19c are provided, and the main pole 19 shown in FIG. 5 has an asymmetric second configuration with respect to the first component 19a having a width Tw. , A third component 19b, 19c are provided, and the tip 19a of the first component 19a is an inclined surface. The main magnetic pole 19 of the magnetic head TBH for generating a transfer bias magnetic field is configured as having a second component 19b and a third component 19c as shown by solid lines in FIG. The magnetic field generated in the gap between the main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH and the surface of the first outer peripheral surface region 29m of the rotating magnetic cylinder 29 is overlapped with their magnetic surfaces facing each other. When the recorded magnetic recording medium and the unrecorded magnetic recording medium in the
The state of the change on the time axis of the intensity of the alternating magnetic field applied to any specific portion of the two recording media is as shown in the waveform diagram shown in the upper part of FIG.

The main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH includes a second component 19b 'and a third component 19c' as shown by broken lines in FIG. Main pole 19 of the transfer bias magnetic field generating magnetic head TBH configured as
In a magnetic field generated in a gap between the rotating magnetic cylinder 29 and the surface of the first outer peripheral surface region 29m, a recorded magnetic recording medium and an unrecorded magnetic recording medium in a state where the magnetic surfaces face each other and overlap each other are superposed. When the recording medium travels at the speed v, the time-dependent change in the intensity of the alternating magnetic field applied to any specific portion of the two recording media is shown by the waveform shown in the upper part of FIG. It will be the one shown in the figure.

As described above, in the main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH, the shape of the portion facing the surface of the first outer peripheral surface region 29m of the rotating magnetic cylinder 29 has a solid line in FIG. By changing from the illustrated state to the state illustrated by the dotted line, a gap is generated between the main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH and the surface of the first outer peripheral surface region 29 m of the rotating magnetic cylinder 29. In a magnetic field, a recorded magnetic recording medium and an unrecorded magnetic recording medium in a state where they are superposed with their magnetic surfaces facing each other have a velocity v
When the vehicle travels, the intensity of the intensity of the alternating magnetic field applied to any specific portion of the two recording media on the time axis is as shown in the waveform diagram shown in the upper part of FIG. The magnetic field gradient characteristic changes to a state with a different slope. This means that the transfer bias magnetic field generating magnetic head TBH
By changing the outer shape of the tip of the main pole 19 of
Main magnetic pole 1 of magnetic head TBH for generating transfer bias magnetic field
9 means that the intensity distribution of the magnetic field generated in the gap between the rotating magnetic cylinder 29 and the surface of the first outer peripheral surface region 29m can be arbitrarily changed and set. When a low-cost magnetic recording information copying apparatus is configured by employing the method, a magnetic field gradient characteristic having a gentle gradient can be obtained in correspondence with a low-frequency bias signal used as a bias signal for generating a bias magnetic field. By adopting the main pole 19 having such an outer shape, it becomes easy to expand the degree of freedom in device design.

The main pole 19 shown in FIG.
As the first component 19a of w, a magnetic material having a high magnetic saturation level, for example, a laminated structure of an amorphous metal thin film is used, and a configuration in which the tip 19a1 has an inclined surface is used. This is a configuration example in which the second and third components 19b and 19c are provided asymmetrically with respect to the first component 19a. The position of the tip 19c1 of the third component provided at a position occupying a position preceding the first component 19a follows the first component 19a with respect to the traveling magnetic recording medium. The position is set so as to be more distant from the surface of the first outer peripheral surface region 29m of the rotating magnetic cylinder 29 than the position of the tip 19b1 of the second component provided at the position occupying the position. .

The main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH having the main magnetic pole 19 having the structure shown in FIG. When a recorded magnetic recording medium and an unrecorded magnetic recording medium in a state of being superposed with their magnetic surfaces facing each other run at a speed v in a magnetic field generated in a gap with the surface of the outer peripheral surface region 29m, As shown by the waveform diagram shown in the upper part of FIG. 5, the state of the change of the intensity of the alternating magnetic field applied to any specific portion of the two recording media on the time axis is shown in FIG. In the central part of the first component part in 19, the amplitude intensity of the magnetic field becomes maximum, a part preceding the above-mentioned position (left side in the figure) shows a steep magnetic field gradient, and follows the above-mentioned position. Loose in the part (right side in the figure) It is as shown the magnetic field gradient. Then, a magnetic field having a gentle magnetic field gradient generated at a portion (right side in the figure) subsequent to the position of the center of the first component in the main pole 19 where the amplitude strength of the magnetic field is maximum is applied to magnetic transfer. Since it is an effective part, if the magnetic field gradient in this part is moderate to some extent, a low frequency bias signal can be used (in the transfer bias magnetic field, the required bias signal signal has a wavenumber of about 14). The drive circuit to be used can also be a low-speed and inexpensive drive circuit, and can be higher than the position of the central portion of the first component in the main pole 19 at which the amplitude intensity of the magnetic field is maximized. A magnetic field showing a steep magnetic field gradient in the preceding part (left side in the figure) applies a magnetic field to the magnetic tape for only a short time, so that the demagnetizing effect on the master recording medium is minimized. It is advantageous to Kusuru.

Next, the signal detected by the magnetic flux detecting coil 24 provided near the tip of the main magnetic pole 19 for detecting the magnetic flux in the main magnetic pole 19 becomes a predetermined reference value. The amplitude of the bias current is automatically controlled by a single round of automatic control circuit to make the transfer bias magnetic field strength constant or the exciting current detected by the exciting current detecting means for detecting the magnetomotive force that generates a magnetic flux flowing through the main magnetic pole. A constant bias magnetic field is always generated by automatically controlling the amplitude of the bias current by a one-time automatic control circuit so that the value becomes a predetermined reference value, and making the transfer bias magnetic field intensity constant. Used to make That is, the transfer bias magnetic field generating device in the magnetic recording information copying apparatus of the present invention is similar to the main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH illustrated in FIGS. 4 and 5, for example. The above-described magnetic flux detecting coil 24 in the transfer bias magnetic field generating magnetic head TBH having a configuration in which the magnetic flux detecting coil 24 is provided near the distal end portion.
The signal detected by the operation of the automatic control circuit for automatically controlling the amplitude of the bias current so as to become a predetermined reference value by a circuit arrangement as illustrated in FIG. 7B without controlling the transfer bias magnetic field strength to be constant or providing the main magnetic pole 19 with the special magnetic flux detecting coil 24, for example. Depending on the arrangement, the amplitude of the bias current is changed in one round so that the exciting current values detected by the exciting current detecting means 33 and 34 for detecting the magnetomotive force for generating the magnetic flux flowing through the main magnetic pole become a predetermined reference value. The tip of the main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH and the rotating magnetic cylinder 29 are automatically controlled by an automatic control circuit to keep the transfer bias magnetic field strength constant. Distance g between the first outer circumferential surface area 29m
However, the transfer bias magnetic field strength can always be maintained at a predetermined value, even if it fluctuates due to various causes.

First, a constant bias magnetic field is always generated by using a signal detected by the magnetic flux detecting coil 24 provided near the tip of the main magnetic pole 19 for detecting the magnetic flux in the main magnetic pole. An embodiment in such a case will be described with reference to FIG. In the bias current supply circuit illustrated in FIG. 7A, reference numeral 35 denotes a bias signal generator, and the bias signal generator 35 is provided with a reference signal generated by a reference oscillator built therein or provided outside. A frequency divider (programmable frequency divider) for converting a reference signal supplied from a given reference signal source into a signal of a predetermined frequency, a phase locked loop (PLL), and the like. Anything that can generate a bias signal with a predetermined frequency value can be used. The bias signal having a predetermined frequency value generated by the signal generator 35 is supplied to a pulse width modulation control circuit 36 and a head resonance circuit 39. The output signal from the pulse width modulation control circuit 36 is supplied to an H-bridge circuit 37. In the H-bridge circuit 37, the voltage applied between the terminal 38 and the ground by a switching element constituting the H-bridge circuit 37 is described above. Switching is performed by an output signal from the pulse width modulation control circuit 36, and a transfer bias magnetic field generating magnetic head TBH is transferred via a head resonance circuit 39 including a coupling circuit 40 including a control coil and a resonance capacitor 41. Magnetic pole 19 and core 20
And a bias current is supplied to the exciting coil 23 wound on the magnetic path between.

Due to the magnetomotive force generated in the transfer bias magnetic field generating magnetic head TBH by the bias current supplied to the exciting coil 23, the main magnetic pole 19 → the main magnetic pole 1
9 and the first outer peripheral surface area 29m of the rotating magnetic cylindrical body 29 → the first outer peripheral surface area 29m of the rotating magnetic cylindrical body 29
→ Internal magnetic path of rotating magnetic cylinder 29 → Rotating magnetic cylinder 29
Second outer peripheral surface areas 29u, 29d of the rotary magnetic cylinder 2
Since the magnetic flux flows through the magnetic circuit from the upper core 27 and the lower core 28 to the main magnetic pole 19 which are disposed to face the second outer peripheral surface areas 29u and 29d of the main magnetic flux 19, the main magnetic flux 19 is wound around the leading end. The magnetic flux detecting coil 24 includes a main magnetic pole 19 → a main magnetic pole 19 and a rotating magnetic cylinder 2
9, a gap g with the first outer peripheral surface region 29m → the first outer peripheral surface region 24m of the rotating magnetic cylinder 29 → the rotating magnetic cylinder 29
Internal magnetic path → second outer peripheral surface region 2 of rotating magnetic cylinder 29
Magnetic flux detection signals corresponding to the magnetic fluxes flowing through the magnetic circuits 9u and 29d, that is, the main magnetic pole 19 → the first outer peripheral surface area 29m of the main magnetic pole 19 and the rotating magnetic cylinder 29 → the first outer periphery of the rotating magnetic cylinder 29 A magnetic flux detection signal indicating the differential value of the amount of magnetic flux flowing through the magnetic circuit in the surface region 29m is generated.

The magnetic flux detection signal detected by the magnetic flux detection coil 24 is supplied to an amplitude detection circuit 42 (for example, a peak value detection circuit, an average value detection circuit). In the following description, it is assumed that a peak value detection circuit is used as the amplitude detection circuit 42. In the amplitude detection circuit 42, after integrating the magnetic flux detection signal and converting it into a magnetic flux signal, the peak value of the magnetic flux signal is converted into a DC voltage value by an operational amplifier, and the output signal is subjected to the pulse width modulation control described above. It is supplied to the input circuit of the error amplification circuit in the circuit 36. In the error amplification circuit in the pulse width modulation control circuit 36, when the gap size g between the main magnetic pole 19 and the first outer peripheral surface region 29m of the rotating magnetic cylinder 29 is a predetermined value (for example, g = 75 microns). Corresponding to the strength Hs (for example, Hs = 2000 Oersted) of the magnetic field generated in the gap between the main magnetic pole 19 and the first outer peripheral surface region 29m of the rotating magnetic cylinder 29, the coil is wound near the tip of the main magnetic pole 19. The DC voltage value V output from the amplitude detection circuit 42 based on the magnetic flux detection signal generated in the turned magnetic flux detection coil 24.
s (for example, Vs = 2 volts), a voltage value of Vs = 2 volts prepared as a standard voltage is compared with a DC voltage value output from the amplitude detection circuit 42 to generate an error signal. In the pulse width modulation control circuit 36, the bias signal supplied from the signal generator 35 to the pulse width modulation control circuit 36 is supplied according to the polarity and magnitude of the error signal generated in the error amplifier circuit. The pulse width is changed so that the error signal becomes zero.

The excitation coil wound on the magnetic path between the main pole 19 and the core 20 of the magnetic head TBH for generating the transfer bias magnetic field for the pulse width modulation control circuit 36 → H bridge circuit 37 → head resonance circuit 39 23 → Main pole 1
9 → a magnetic flux detection signal detected by the magnetic flux detection coil 24 wound around the tip of the main magnetic flux 19 → an amplitude detection circuit 42 → a pulse width modulation control circuit 36, which forms an automatic control circuit. In operation, the distance g between the tip of the main pole 19 of the transfer bias magnetic field generating magnetic head TBH and the first outer peripheral surface area 29m of the rotating magnetic cylinder 29 fluctuates due to various causes. However, the transfer bias magnetic field intensity is always maintained at a predetermined value set in advance.

In a state where the transfer bias magnetic field generator in the magnetic recording information copying apparatus is started,
Since no magnetic flux flows in the main magnetic pole 19, the main magnetic pole 19
No magnetic flux detection signal is generated in the magnetic flux detection coil 24 wound near the tip of the coil, the DC voltage value from the amplitude detection circuit 42 is zero, and the pulse width modulation control circuit 36
In the error amplifier circuit, a voltage value of Vs = 2 volts prepared as a standard voltage is generated as an error signal. As a result, the pulse width modulation control circuit 36 generates a signal having the maximum conduction pulse width,
Start by giving to When a switching element (for example, a MOS-FET, a transistor, or the like) in the H-bridge circuit 37 performs a switching operation, a circuit between the power supply terminal 38 and the ground is turned on and off, and a bias current generated thereby causes the head resonance circuit 39 to operate. When the bias current is supplied to the exciting coil 23 wound around the magnetic path between the main magnetic pole 19 and the core 20 in the transfer bias magnetic field generating magnetic head TBH through the transfer, the bias current supplied to the exciting coil 23 is supplied. The main magnetic pole 19 → the gap g between the main magnetic pole 19 and the first outer peripheral surface area 29m of the rotating magnetic cylinder 29 → the second magnetic pole of the rotating magnetic cylinder 29 1 outer peripheral surface area 29m → internal magnetic path of rotating magnetic cylinder 29 → second outer peripheral surface areas 29u, 29 of rotating magnetic cylinder 29 → rotating magnetic cylindrical body 29 of the second outer circumferential surface area 29u, upper core is disposed opposite the 29d 27 and the lower core 28 →
The magnetic flux flows through the magnetic circuit of the main pole 19, and the subsequent operation is performed as described above.

Next, the magnetic flux detecting coil 24 is attached to the main magnetic pole 19.
In the circuit arrangement illustrated in FIG. 7B, the exciting current values detected by the exciting current detecting means 33 and 34 for detecting the magnetomotive force for generating the magnetic flux flowing through the main magnetic pole are not previously provided. A description will be given of an embodiment in which the amplitude of the bias current is automatically controlled by a one-cycle automatic control circuit so as to be a predetermined reference value so that the transfer bias magnetic field intensity is kept constant. In the bias current supply circuit exemplified in FIG. 7B, reference numeral 35 denotes a bias signal generator, and the bias signal generator 35 is provided with a reference signal generated by a reference oscillator built therein or provided outside. A frequency divider (programmable frequency divider) for converting a reference signal supplied from a given reference signal source into a signal of a predetermined frequency, a phase locked loop (PLL), and the like. Anything that can generate a bias signal with a predetermined frequency value can be used.

The bias signal having a predetermined frequency value generated by the signal generator 35 is supplied to a pulse width modulation control circuit 36. An output signal from the pulse width modulation control circuit 36 is supplied to an H bridge circuit 37,
In the H-bridge circuit 37, the voltage applied between the terminal 38 and the ground by the switching element constituting the H-bridge circuit 37 is switched by the output signal from the pulse width modulation control circuit 36, and the resonance capacitor 41 and the transfer Excitation coil 23 wound around a magnetic path between main pole 19 and core 20 in magnetic head TBH for generating bias magnetic field
The bias current is supplied to the exciting coil 23 in the head resonance circuit 39 configured by the above. Bias current (excitation current) supplied to the aforementioned excitation coil 23
The excitation current detection coil 3 provided in the detection current transformer 33 functioning as excitation current detection means 33 and 34 for detecting a magnetomotive force for generating a magnetic flux flowing through the main magnetic pole 19.
4 detected.

The main magnetic pole 19 → main magnetic pole 1 is generated by the magnetomotive force generated in the transfer bias magnetic field generating magnetic head TBH by the bias current supplied to the exciting coil 23 described above.
9 and the first outer peripheral surface area 29m of the rotating magnetic cylindrical body 29 → the first outer peripheral surface area 29m of the rotating magnetic cylindrical body 29
→ Internal magnetic path of rotating magnetic cylinder 29 → Rotating magnetic cylinder 29
Second outer peripheral surface areas 29u, 29d of the rotary magnetic cylinder 2
The magnetic flux flows through a magnetic circuit from the upper core 27 and the lower core 28 to the main magnetic pole 19, which are disposed to face the second outer peripheral surface areas 29u and 29d. By maintaining the current value detected by the exciting current detection coil 34 provided in the transformer 33 at a predetermined constant value, the current value can be maintained at a predetermined value.

That is, the magnetic flux detection signal detected by the exciting current detection coil 34 is supplied to an amplitude detection circuit 42 (for example, a peak value detection circuit, an average value detection circuit). The above-described amplitude detection circuit 42 → pulse width modulation control circuit 36 → H bridge circuit 37 → head resonance circuit 39 → wound around the magnetic path between the main magnetic pole 19 and the core 20 in the magnetic head TBH for generating a transfer bias magnetic field. Excitation coil 23
→ Flux detection signal detected by exciting current detection coil 34 →
An automatic control circuit consisting of the amplitude detection circuit 42 → operates to operate the end portion of the main magnetic pole 19 of the transfer bias magnetic field generating magnetic head TBH and the first outer peripheral surface region 29m of the rotating magnetic cylinder 29. Even if the distance g fluctuates due to various causes, the transfer bias magnetic field strength is
It is always kept at a predetermined value set in advance. The operation from the start of the transfer bias magnetic field generator to the normal state in the copying apparatus for magnetically recorded information until the transition to the normal state is the same as that described in the circuit arrangement of FIG. Detailed description here is omitted.

As described above, in the transfer bias magnetic field generating apparatus in the magnetic recording information copying apparatus of the present invention, the magnetic flux detecting device provided near the tip of the main pole 19 of the transfer bias magnetic field generating magnetic head TBH is used. A circuit for automatically controlling the amplitude of the bias current so that the signal detected by the coil 24 becomes a predetermined reference value by a circuit arrangement as illustrated in FIG. 7A. The operation of (1) controls the transfer bias magnetic field strength to be constant, or detects the magnetomotive force that generates a magnetic flux flowing through the main magnetic pole by, for example, the circuit arrangement illustrated in FIG. 7B. Current detecting means 33, 3
By automatically controlling the amplitude of the bias current by a one-cycle automatic control circuit so that the exciting current value detected in step 4 becomes a predetermined reference value and making the transfer bias magnetic field strength constant, the transfer is performed. Of the main magnetic pole 19 of the magnetic head TBH for generating a bias magnetic field and the rotating magnetic cylinder 2
9, even if the distance g from the first outer peripheral surface area 29m fluctuates due to various causes, the transfer bias magnetic field intensity can always be maintained at a predetermined value set in advance. However, such an operation cannot be realized by a transfer bias magnetic field generating magnetic head using a C-type head as in the conventional magnetic recording information copying apparatus described above with reference to FIG.

The above point will be described with reference to FIG. In FIG. 6, reference numeral 4 denotes an enlarged view of the vicinity of the magnetic gap 4a in the C-type head, reference numeral 5 denotes a soft magnetic drum, and reference numeral 24 denotes a magnetic flux wound around the core of the C-type head. Coil 24. In FIG. 6, the gap length G of the magnetic gap 4a in the C-type head is C
If the gap g between the magnetic gap 4a and the soft magnetic drum 5 in the mold head is extremely large, the signal detected by the magnetic flux detection coil 24 wound around the core is, for example, shown in FIG. By the circuit arrangement as exemplified in the above, by the operation of a single-cycle automatic control circuit that automatically controls the amplitude of the bias current so as to be a predetermined reference value,
Although it is possible to control the transfer bias magnetic field strength to be constant, the soft magnetic drum 5 changes the magnetic gap 4a in the C-type head and the gap g between the soft magnetic drum 5 due to eccentricity or the like. However, when the amount of the change becomes not negligible with respect to the gap length G of the magnetic gap 4a in the C-type head, an automatic control circuit for automatically controlling the amplitude of the bias current operates to detect the magnetic flux. Even if the magnetic flux passing through the use coil 24 is kept constant, if the magnetic gap 4a in the C-type head and the gap g between the soft magnetic material drum 5 in the C-type head become large due to, for example, eccentricity, the above-mentioned C-type Since the magnetic resistance in the gap g between the magnetic gap 4a in the head and the soft magnetic drum 5 increases, only the magnetic flux that returns through the gap length G of the magnetic gap 4a in the C-type head increases. From the above, the circuit arrangement as illustrated in FIG. 7A described above is used to control the operation of a single-cycle automatic control circuit that automatically controls the amplitude of the bias current so that the bias current becomes a predetermined reference value. It is impossible to control the transfer bias magnetic field strength to be constant.

[0050]

As is apparent from the above description, the transfer bias magnetic field generating apparatus in the magnetic recording information copying apparatus of the present invention is not limited to the magnetic surface of a recorded magnetic recording medium serving as a master recording medium. And a non-recorded magnetic recording medium serving as a slave recording medium facing each other, and at least an outer peripheral surface portion of the rotating magnetic cylindrical body made of a high-permeability magnetic material. A first outer peripheral surface area where a recorded magnetic recording medium and an unrecorded magnetic recording medium in a state where the two recording media are pressed against each other by air pressure and the superposed magnetic surfaces face each other are to be pressed against each other; A rotating magnetic cylinder having a second outer peripheral area set at a position largely separated from the first outer peripheral area by a space in the width direction of the magnetic recording medium via a space. The magnetic flux from the main magnetic pole arranged opposite to the above-mentioned first outer peripheral surface area is transferred from the main magnetic pole to the unrecorded magnetic recording medium in a state of being superposed with the magnetic surfaces facing each other. Magnetic recording medium → first outer peripheral area of rotating magnetic cylinder → magnetic path inside rotating magnetic cylinder → second outer peripheral area of rotating magnetic cylinder → second of rotating magnetic cylinder
Transfer of a single-peak characteristic generated by the transfer bias magnetic field generator in the magnetic recording information copying apparatus of the present invention, because the magnetic flux flows in a path from the core member to the main magnetic pole disposed opposite to the outer peripheral surface region of the magnetic recording information. With the bias magnetic field, the demagnetization effect can be applied only once to the master recording medium, and the recorded magnetic recording medium and the unrecorded magnetic recording medium in a state where the magnetic surfaces face each other and overlap each other are Since only the bias magnetic field near the main magnetic pole is applied, the transfer of the magnetically recorded information from the recorded magnetic recording medium to the unrecorded magnetic recording medium is performed with a good S / N, and Eliminating the problem of demagnetization, and a signal detected by a magnetic flux detection coil provided near the tip of the main magnetic pole for detecting magnetic flux in the main magnetic pole is a predetermined signal. The amplitude of the bias current so that the reference value is automatically controlled by the automatic control circuit of round,
The bias current of the bias current is determined so that the transfer bias magnetic field intensity is constant or the exciting current value detected by the exciting current detecting means for detecting the magnetomotive force for generating the magnetic flux flowing through the main magnetic pole is a predetermined reference value. The distance between the tip of the main pole of the magnetic head for generating the transfer bias magnetic field and the outer peripheral surface of the rotating magnetic cylinder by automatically controlling the amplitude by a single round of the automatic control circuit to keep the transfer bias magnetic field strength constant. However, even if it fluctuates due to various causes, the transfer bias magnetic field strength can always be maintained at a predetermined value set in advance, and further, it is necessary to change the outer shape of the tip of the main magnetic pole. As a result, a bias magnetic field exhibiting any desired magnetic field gradient characteristics can be easily formed, and according to the present invention, the efficiency of the head can be increased without unnecessarily increasing the frequency of the bias signal. A high transfer bias magnetic field generator can be easily configured, and in the transfer bias magnetic field generator in the magnetic recording information copying apparatus of the present invention, a single main magnetic pole mostly generates a vertical magnetic field component effective for magnetic transfer. Since the transfer bias magnetic field having a single-peak characteristic is stably generated as described above, a metal member is arranged near the magnetic head for generating the bias magnetic field as in the conventional apparatus described above, and the magnetic field gradient is steep. A bias magnetic field generator for transfer in a magnetic recording information copying apparatus according to the present invention, which is compact, highly efficient, and consumes a small amount of compressed air without reducing the efficiency by employing such means. According to the present invention, all of the above-described problems of the conventional device can be satisfactorily solved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an example of a transfer bias magnetic field generator of the present invention.

FIG. 2 is an exploded perspective view of a transfer bias magnetic field generation magnetic head used in the transfer bias magnetic field generation device of the present invention.

FIG. 3 is a diagram showing a magnetic head for generating a transfer bias magnetic field.

FIG. 4 is an enlarged view of a part of a transfer bias magnetic field generation magnetic head that can be used in the transfer bias magnetic field generation device of the present invention.

FIG. 5 is an enlarged view of a part of a transfer bias magnetic field generating magnetic head that can be used in the transfer bias magnetic field generator of the present invention.

FIG. 6 is an enlarged view of a part of a transfer bias magnetic field generating magnetic head that can be used in a conventional transfer bias magnetic field generator.

FIG. 7 is a block diagram of a bias current supply circuit.

FIG. 8 is a perspective view showing a conventional example of a transfer bias magnetic field generator.

FIG. 9 is a diagram showing a schematic configuration of an example of a transfer bias magnetic field generator already proposed.

FIG. 10 is a characteristic curve diagram showing a result of a magnetic field distribution characteristic of a leakage magnetic field in a magnetic gap 4a of the C-type head in the conventional transfer bias magnetic field generator shown in FIG. 9 obtained by a model experiment.

FIG. 11 is an enlarged view of a portion near a magnetic head for generating a transfer bias magnetic field for explaining a problem of a conventional transfer bias magnetic field generator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main head base, 2 ... Sub head base, 3 ... Head holder, 4 ... Magnetic head for generating a bias magnetic field, 4a ...
Magnetic gap, 5: Drum made of soft magnetic material, 6: Rotating shaft, 7: Recorded magnetic recording medium (master tape), 8: Unrecorded magnetic recording medium (slave tape), 9, 29: Rotating magnetic cylinder, 10 ... Head block mounting member, 10a, 10b ...
Mounting piece, 10c: upper surface of head block mounting member 10,
10d: a recess provided in the head block mounting member 10, 15: a mounting member for the transfer bias magnetic field generating magnetic head, 18: a compressed air supply hole provided in the rear wall of the head block mounting member 10, Reference numeral 19: a main magnetic pole for generating a bias magnetic field; 20, a core member; 21, 22, an outlet for compressed air; 23, an exciting coil; 24, a magnetic flux detecting coil for detecting a magnetic flux in the main magnetic pole 19; 26: Block material made of nonmagnetic insulator, 27: Upper core, 28: Lower core, 29m: First of rotating magnetic cylinder
, 29u, 29d... Of the rotating magnetic cylinder
, Compressed air passage, 35 bias signal generator, 33 current transformer, 34 detection coil, 36 pulse width modulation control circuit, 37 H bridge circuit, 39 head resonance circuit , 41 ... resonance capacitor,
42 ... amplitude detection circuit, TBH ... magnetic head for generating transfer bias magnetic field,

Claims (4)

(57) [Claims] 1. A recorded magnetic recording medium serving as a master recording medium and an unrecorded magnetic recording medium serving as a slave recording medium are set in a state where the magnetic surfaces of the two recording media face each other. At least on the outer peripheral surface of the rotating magnetic cylinder made of a high-permeability magnetic material, and applying a bias magnetic field for transfer in the thickness direction of the recording medium to the pressed portions of the two recording media. A bias magnetic field generator for transfer in a magnetic recording information copying apparatus in which a magnetic recording information of a master recording medium is copied to a slave magnetic recording medium by applying the magnetic recording information to a master magnetic recording medium. A first outer peripheral area to which a recorded magnetic recording medium and an unrecorded magnetic recording medium in a state are to be pressed, and a magnetic recording medium via a space with respect to the first outer peripheral area. A rotating magnetic cylinder including a second outer peripheral surface region set at a position largely separated in the width direction of the rotating magnetic cylinder;
The end surface shape extends at least over the entire width of the magnetic recording medium and is narrow in the running direction of the magnetic recording medium on a surface set at a position close to the surface of the portion of the outer peripheral surface region of the magnetic recording medium. The main magnetic pole provided with the tip end face of the main magnetic pole for generating a bias magnetic field having such a position, and the shortest distance between the tip end of the main pole and the outer peripheral surface of the rotating magnetic cylinder is extremely small. At a position separated from the position of the main magnetic pole for generating the bias magnetic field by a large distance in the width direction of the magnetic recording medium, a wide area is opposed to a portion of the second outer peripheral surface region of the rotating magnetic cylinder. A transfer bias magnetic field generator for a magnetic recording information copying apparatus, comprising: 2. A recorded magnetic recording medium serving as a master recording medium and an unrecorded magnetic recording medium serving as a slave recording medium are set in a state where the magnetic surfaces of the two recording media face each other. At least on the outer peripheral surface of the rotating magnetic cylinder made of a high-permeability magnetic material, and applying a bias magnetic field for transfer in the thickness direction of the recording medium to the pressed portions of the two recording media. In a transfer bias magnetic field generator in a magnetic recording information copying apparatus in which the magnetic recording information of the master recording medium is copied to the slave magnetic recording medium by A first outer peripheral area to which a recorded magnetic recording medium and an unrecorded magnetic recording medium are to be pressed, and a magnetic recording medium via a space with respect to the first outer peripheral area. A rotating magnetic cylinder including a second outer peripheral surface region set at a position largely separated in the width direction of the rotating magnetic cylinder;
The end surface shape extends at least over the entire width of the magnetic recording medium and is narrow in the running direction of the magnetic recording medium on a surface set at a position close to the surface of the portion of the outer peripheral surface region of the magnetic recording medium. The main magnetic pole provided with the tip end face of the main magnetic pole for generating a bias magnetic field having such a position, and the shortest distance between the tip end of the main pole and the outer peripheral surface of the rotating magnetic cylinder is extremely small. At a position separated from the position of the main magnetic pole for generating the bias magnetic field by a large distance in the width direction of the magnetic recording medium, a wide area is opposed to a portion of the second outer peripheral surface region of the rotating magnetic cylinder. And a core member configured to have a surface that has a magnetic flux, a magnetic flux detection coil for detecting the magnetic flux in the main magnetic pole, and a signal detected by the magnetic flux detection coil. Predetermined And the amplitude of the bias current so that the reference value is provided an automatic control circuit of round for automatically controlling the transfer bias magnetic field generating device in the copying apparatus of a magnetic recording information in which the transfer bias magnetic field strength constant. 3. A recorded magnetic recording medium serving as a master recording medium and an unrecorded magnetic recording medium serving as a slave recording medium are set in a state where the magnetic surfaces of the two recording media face each other. At least on the outer peripheral surface of the rotating magnetic cylinder made of a high-permeability magnetic material, and applying a bias magnetic field for transfer in the thickness direction of the recording medium to the pressed portions of the two recording media. In a transfer bias magnetic field generator in a magnetic recording information copying apparatus in which the magnetic recording information of the master recording medium is copied to the slave magnetic recording medium by A first outer peripheral area to which a recorded magnetic recording medium and an unrecorded magnetic recording medium are to be pressed, and a magnetic recording medium via a space with respect to the first outer peripheral area. A rotating magnetic cylinder including a second outer peripheral surface region set at a position largely separated in the width direction of the rotating magnetic cylinder;
The end surface shape extends at least over the entire width of the magnetic recording medium and is narrow in the running direction of the magnetic recording medium on a surface set at a position close to the surface of the portion of the outer peripheral surface region of the magnetic recording medium. The main magnetic pole provided with the tip end face of the main magnetic pole for generating a bias magnetic field having such a position, and the shortest distance between the tip end of the main pole and the outer peripheral surface of the rotating magnetic cylinder is extremely small. At a position separated from the position of the main magnetic pole for generating the bias magnetic field by a large distance in the width direction of the magnetic recording medium, a wide area is opposed to a portion of the second outer peripheral surface region of the rotating magnetic cylinder. A core member configured so as to have a surface having a curved surface, and a means for detecting an exciting current value for detecting a magnetomotive force for generating a magnetic flux flowing through the main magnetic pole, and the exciting current value. Detection means A magnetic recording information copying apparatus provided with a single-cycle automatic control circuit for automatically controlling the amplitude of the bias current so that the detected excitation current value becomes a predetermined reference value, and the transfer bias magnetic field intensity is kept constant. Transfer bias magnetic field generator. 4. When a main magnetic pole for generating a bias magnetic field is constituted by using a plurality of magnetic materials having different magnetic properties,
As the magnetic material constituting the central portion of the tip of the main pole, the magnetic material having the highest saturation magnetic flux density is used, and the outer shape of the main pole is defined as the distance between the tip of the main pole and the outer peripheral surface of the rotating magnetic cylinder. 4. A transfer bias magnetic field generator in a magnetic recording information copying apparatus according to claim 1, wherein the transfer bias magnetic field is asymmetric with respect to a central portion of the main magnetic pole in a longitudinal direction of the magnetic recording medium.