JPH0237526A - Magnetic copying device - Google Patents

Abstract

PURPOSE:To realize proper copying corresponding to the material of each recording medium to be used by pressurizing a master recording medium contact with a slave recording medium, and adjusting the phase difference of the AC exciting currents of two exciting means interposing both planes. CONSTITUTION:Magnetic heads H1 and H2 are provided so that mutual gap can be confronted with the inside of drums D1 and D2 consisting of nonmagnetic material. A master tape M and a sleeve tape S are pressurized contact by the drums D1 and D2 with a driving tape T, and are fed by applying a bias magnetic field for copying from the heads H1 and H2. The serial resonant oscillation circuit OSC of a bias magnetic field generation device oscillates by the winding coil L1 of the head H1 and the serial resonance frequency of a capacitor C1, and oscillation output is inputted to a phase shifter circuit (phi). And a phase shift characteristic is adjusted by a variable resistor R in the circuit (phi), and the head H2 can be driven via a power amplifier PW. In such a way, it is possible to change the bias magnetic field by adjusting the resistor R, and to perform the copying suitable for tapes of various kinds.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a magnetic copying apparatus.

(Prior Art) It is easy to record signals recorded on a magnetic recording medium onto a new medium. For example, this can be done using an audio cassette tape dubbing deck or the like. Furthermore, when a large number of copies of a music tape or the like are to be made at once, the medium transfer speed is increased in the tape running direction, and the recording bias frequency is also increased correspondingly. As a result, music tapes can be mass-produced, for example, at about 50 times the normal speed. However, with this method, a video tape recorder (hereinafter referred to as VTR)
or digital audio tape recorder (hereinafter referred to as D
AT) tapes cannot be copied at high speed. In other words, VTRs and DATs use a rotating head system, so it is necessary to increase the number of rotations of the rotating head in accordance with the tape running speed, and of course, it is necessary to widen the frequency response characteristics of recording and playback. becomes.

This involves technical difficulties. Therefore, instead of such a method, generally many tape decks are connected in parallel or in cascade to copy a large number of tapes at a constant speed.

The method described above has a limit in increasing the productivity of tape copying of VTR and DAT tapes.

For this reason, there is a magnetic copying method in which a master tape and a slave tape, which are mirror images in advance, are pressed together, a bias magnetic field as external energy is applied to the pressed part, and the tapes are wound at high speed.

FIG. 6(a) shows a diagram of its principle. Same figure <a
), M is the master tape and S is the slave tape. Further, H is a bias magnetic field generating means such as a solenoid or a magnetic head. The bias frequency is provided by an oscillator SG. The magnetic film surfaces of the master tape M and slave tape S are pressed against each other by the bias magnetic field generating section H, magnetic copying is performed, and in this state, each tape M and S is wound onto their respective take-up reels M'S'. It will be done.

This magnetic copying method generally has the following problems. That is, (1) It is necessary to have a master tape that is a mirror image, and it is necessary that the coercive force He of the master tape is approximately 2.5 times or more greater than that of the slave tape.

(2) Demagnetization of the master tape due to the applied bias magnetic field is unavoidable.

(3) It is necessary to bring the master tape and slave tape into close contact.

In order to solve problems (1) and (2) above, it is necessary to select materials for the master tape and slave tape.

FIGS. 6(b) and 6(c) are cross-sectional views showing the state of magnetization of master tape and slave tape made of different materials. Generally, in coated magnetic tape, the orientation of magnetic powder is aligned after coating and before solidification. Figure 6 (b
) indicates the case where both the master tape and slave tape are oriented in the tape longitudinal direction. In this case, the vertical direction in FIG. 6(b) is the axis of difficult erasing, and the longitudinal direction of the tape is the axis of easy magnetization. In order to apply an external magnetic field in the case of Fig. 6(b), applying a magnetic field along Y-Y' so that the magnetic flux is concentrated in the longitudinal direction for both the mask and tape slave tape will improve the bias application efficiency. can be improved. Naturally, the strength of the bias magnetic field in this case needs to be as small as possible than the coercive force Hc of the master tape and at least 2.5 times the coercive force Hc of the slave tape.

FIG. 6(C) shows a case where a tape oriented in the longitudinal direction as described above is used as the master tape, and a tape coated with magnetic powder made of, for example, hexagonal ferrite is used as the slave tape. FIG. 3 is a cross-sectional view showing the state of magnetization. In this case, the applied bias magnetic field is x
As shown by -x' in FIG. 6(C), a bias magnetic field directed in the vertical direction is effective for transfer.

As described above, it is necessary to appropriately set the direction and strength of the bias magnetic field depending on the characteristics of the magnetic medium used for copying.

FIGS. 7(a) and 7(b) are examples in which alternating current is supplied to the magnetic head H to generate a bias magnetic field, and the strength of the magnetic field generated near the gap is measured. This seventh
The magnetic field strength distribution in the longitudinal direction (X-axis direction) and the vertical direction (X-axis direction) of the tape will be explained using FIGS. (a) and (b). By the way, Figure 7(a).

The shape of the magnetic head H shown in (b) is the same as the magnetic head of the embodiment described later. 1 in the figure. 2. 3 is the magnetic field distribution through which magnetic flux passes in the longitudinal direction of the tape, 1',
2' and 3' are magnetic field distributions through which magnetic flux passes in a direction perpendicular to the tape magnetic film surface. FIG. 7(a) shows the shape of the gap portion of the magnetic head H. Gap dimension G
If the distance from the gap tip X (in the tape thickness direction) is changed while keeping constant The situation is reversed. However, when the distance from the tip of the gap (tape thickness method) is kept constant and the gap dimension G is changed, the longitudinal component of the tape is always strong near the gap, and the vertical component is strong as shown in Figure 7 (b). No magnetic field is obtained. On the other hand, if one attempts to change the ratio of the magnetic field strengths of the X-axis component and the Y-axis component, the magnetic head H must be rotated clockwise or counterclockwise with respect to the tape vi attachment area.

Therefore, a bias magnetic field generating device devised to increase the perpendicular component of the magnetic field generated from a magnetic head (bias head) has been made public.

FIG. 8(a) is an example. In FIG. 8(a), M is a master tape and S is a slave tape.

The tapes M and S are brought close to each other via guides 01 to G4 and Gl' to G4', and are brought into close contact with each other on the surface of the drum D by air force. In FIG. 8(a), the manner in which the bias magnetic field is generated from the magnetic head H is illustrated in FIG. 8(b) and (e). If the drum D is a non-magnetic material, the same figure (b)
A magnetic field is generated in the longitudinal direction of the tape. When the drum D is made of a magnetic material such as electromagnetic soft iron, many magnetic fields are generated in the vertical direction as shown in FIG.

According to the above method, when a hexagonal ferrite cloth tape (valume ferrite tape) is used as a slave tape, a bias magnetic field along the hard-to-erasing axis of the master tape is used, and the master tape becomes demagnetized. It becomes difficult to do. However, as can be easily understood from FIG. 8(C), although the strength of the bias magnetic field can be changed arbitrarily by changing the current supplied to the magnetic head H, The strength and vertical ratio are determined by a) the gap length of the magnetic head H, Therefore, it is difficult to set it arbitrarily depending on the characteristics of the materials of the master tape and slave tape. In other words, the device can only handle specific master tapes and slave tapes.

(Problems to be Solved by the Invention) As stated above, copying tapes such as VTRs and DATs requires time to increase the transfer speed of the medium, and especially with magnetic tapes using rotating heads, it is difficult to copy tapes such as VTRs and DATs. Simply increasing the transfer speed in the longitudinal direction would not allow the rotary head to follow the transfer, so a method was used in which the master tape and slave tape were brought into pressure contact and a bias magnetic field was applied to copy. but,
There were problems such as demagnetization of the master tape due to the bias magnetic field and setting of the optimum bias for each slave tape, which hindered its implementation. In other words, in the method of generating a large perpendicular magnetic field using a bias head structure, the magnetic field distribution is determined by the dimensions of the head structure and the constants of the magnetic head, and the magnetic field distribution can be arbitrarily set according to the characteristics of the master tape and slave tape. The drawback was that it could not be done.

The present invention has been made in view of the above, and its purpose is to:
It is an object of the present invention to provide a magnetic copying apparatus in which a bias magnetic field can be adjusted so that an appropriate bias magnetic field can be applied depending on the materials of the master recording medium and slave recording medium used.

(Means for Solving the Problems) The magnetic copying apparatus of the present invention brings a master recording medium and a slave recording medium into pressure contact, applies a bias magnetic field for copying to those media in this state, and preliminarily applies a bias magnetic field to the master recording medium. In a magnetic copying device for copying recorded information onto a slave recording medium, a first recording medium is provided facing the master recording medium in pressure contact with the slave recording medium, and is magnetized by applying an excitation current to the slave recording medium. 1
An excitation means and a second excitation means are provided, the first excitation means is configured as a gapped closed magnetic circuit core, and the second excitation means has at least one end of the core opposed to the first excitation means. and further comprising a first current supply means for supplying a first AC excitation current to the first excitation means for exciting it, and a second AC excitation for exciting the second excitation means. It is configured to include a second current supply means for supplying a current in synchronization with the first AC excitation current.

(Function) The first excitation means and the second excitation means sandwich the master recording medium and slave recording medium which are in pressure contact with each other. 1st 2nd
The excitation means is supplied with first and second AC excitation currents from first and second current supply means, respectively. The phase difference between the first and second AC excitation currents is arbitrarily adjusted by a phase difference adjusting means. By selecting an appropriate phase difference between them, the ratio of the magnetic field strengths in the vertical and horizontal directions of the copying bias magnetic field to the master and slave recording media can be arbitrarily set. As a result, appropriate copying is performed depending on the material of each recording medium used.

(Embodiment) FIG. 1 illustrates a bias magnetic field generating section in an embodiment of the magnetic copying apparatus of the present invention.

In FIG. 1, H, H2 are magnetic heads for generating a bias magnetic field. They are provided inside the drums D1 and D2 so that their gap portions face each other. T is a driving tape, M is a master tape, and S is a slave tape. The master tape M and the slave tape S are arranged with their magnetic film surfaces in close contact with each other. Those tapes M, S, together with the driving tape T, are placed between the drums D l , D 2 under a pressure force Y1 . Y
2, the magnetic heads H1 and H2 are configured to come into pressure contact at the center of the gap.

A pinch roller P is pressed against the outer periphery (or inner periphery) of the drum D1. This pinch roller P is rotated counterclockwise, for example, as shown in the figure.

This pinch roller P rotates the drum D1 clockwise. As a result, the driving tape T1 master tape M and slave tape S are transferred to the drum D1. It is configured so that it can run in the direction of the arrow (downward in the figure) while being held by D2.

As can be seen from Figure m1, the drums DI and D2 have a hollow structure and are made of a non-magnetic material, such as ceramic. A polished hard material is used for the outer peripheral surfaces of the drums D t and D 2 . The driving tape T is a film-like tape having a predetermined elasticity, and is made of a non-magnetic material like the drum. The driving tape T is for absorbing running shock in the direction of drum pressure contact, improving adhesion, and stabilizing tape running. Furthermore, the magnetic heads H1 and H2 have wire-wound coils L.
1°L2 is wound. Those coils L1゜L2
Terminals a, b; c, d of are connected to a series resonant circuit O8C and a power amplifier PW in FIG.

FIGS. 2(a) and 2(b) are explanatory diagrams illustrating the operating principle of the apparatus shown in FIG. 1. In FIGS. 2(a) and 2(b), magnetic helads H1 and H2 are used as yoke materials, for example, M
It is preferable that a material with a high 1n magnetic saturation level, such as -Z-based ferrite or silicon steel plate, be used, and that the loss is small. Figure 2(a) shows the magnetic head H.
This is a case where DC currents 11 and 12 are applied so that the upper yoke ends of the winding coils L1 and L2 provided in the coils L1 and H2 are magnetized to the north pole and the lower yoke ends to the south pole. This case is hereinafter referred to as in-phase drive. In this case, the magnetic flux generated from the gap is concentrated from the top to the bottom of the drawing. In this state, the bias magnetic field becomes stronger in the longitudinal direction of the tape.

In FIG. 2(b), a current i is applied so that the upper yoke end of the magnetic head H1 in the figure becomes the N pole and the lower yoke end becomes the S pole, and conversely, the upper yoke end of the magnetic head H2 becomes the S pole. S
The case is shown in which a current 12 is passed so that the lower yoke end becomes the north pole. This case is hereinafter referred to as reverse phase drive. The form of the magnetic flux leaking to the outside from the gap is as shown in FIG. 2(b). That is, magnetic flux is generated simultaneously in the vertical direction of the drawing and in the horizontal direction of the drawing.

In FIGS. 2(a) and 2(b), for ease of understanding, the case where a direct current is supplied to the excitation coil is described. However, when supplying alternating current,
It goes without saying that just by alternating the north and south poles shown in FIGS. 2(a) and 2(b), there is no change in the magnetic field distribution in which the magnetic flux is concentrated in the vertical and horizontal directions.

Next, a case where variable phase power is supplied to such magnetic heads H1 and H2 from a drive circuit as a bias magnetic field generator shown in FIG. 3 will be described.

In FIG. 3, O20 is a series resonant oscillator circuit, and P
W is a power amplifier, and φ is a phase shift circuit.

In the series resonant oscillator circuit O8C, Ql and O2 are operational amplifiers, Ω is a starting trigger transformer, and CI.

C is a resonant capacitor, and R, , R1, and R2 are resistors. The inverting input terminal of the operational amplifier Q1 is grounded, and the non-inverting input terminal is connected to a resonant capacitor C and a bias resistor R1 connected in parallel. The other ends of the capacitor C1 and resistor R connected in parallel are grounded. The output of the operational amplifier Q1 is connected to one end of the primary winding coil g1 of the starting trigger transformer g, and
It is connected via a resistor R to the inverting input terminal of the operational amplifier Q2. Primary winding coil g of starting trigger transformer g
The other end of the magnetic head H1 is connected to one end of the winding coil L1 of the magnetic head H1. Secondary winding g of starting trigger transformer p
One end of 2 is grounded, and the other end is feedback-connected to the inverting input terminal of the operational amplifier Q1 and connected to the oscillation waveform monitor terminal S. The inverting input terminal of the operational amplifier Q2 is grounded, and the output terminal is connected to the winding coil L1 of the magnetic head H1 via the resonant capacitor C1.
It is connected to the other end and is also feedback-connected to the inverting input terminal of itself (operational amplifier Q2) via a resistor R2. As a result, operational amplifier Q2 outputs V − − V, −R2/
It operates as a general inverting amplifier circuit called R1.

Such a series resonant oscillator circuit O8C is configured such that after the power supply stage is turned on, the operational amplifier Q1 starts a positive feedback oscillation operation determined by the parallel resonant impedance of the coil fI2 and the capacitor CI (magnetic head)! Oscillation is maintained at the series resonant frequency of the No. 1 winding coil L1 and the resonant capacitor C1.

The signal from the oscillation waveform monitor terminal S of the series resonant oscillator circuit O8C is configured to be applied to the input terminal φ1 of the phase shift circuit φ. For example, the phase shift circuit φ is configured as a general first-order phase shift circuit. Its characteristics are
The amplitude characteristic has a gain of 1, and the phase shift characteristic between input and output can be changed by a variable resistor R. The output φ from the phase shift circuit φ is applied to the input terminal P of the power amplifier PW.

The power amplifier PW is a general TL (balanced transformer-less) amplifier. However, the resonant capacitor C2 is inserted in order to easily drive the winding coil L2 of the magnetic head H2 and to resonate with the coil L2 to reduce impedance.

According to the apparatus shown in FIG. 3, the excitation currents 11° and 12 supplied to the winding coils L, L2 of the magnetic heads H1 and H2 can have a phase difference Δφ as shown.

That is, by changing the variable resistance R of the phase shift circuit φ,
The power supply phase difference Δφ changes. As a result, the magnetic head H
, , H2, the vertical and horizontal components of the magnetic field generated between the gaps change at an arbitrary ratio. FIG. 4 shows the distribution state of the changing magnetic field.

FIGS. 5(a) and 5(b) are principle diagrams of other embodiments, and in FIGS. 2(a) and 2(b), the magnetic head H2 is connected to the gapped closed magnetic path yoke like the magnetic head H1. On the other hand, in FIGS. 5(a) and 5(b), the magnetic head H2o is constructed with an open magnetic path core (bar antenna type core).

In FIG. 5(a), the upper yoke end of the magnetic head H1 is the N pole, the lower yoke end is the S pole, and the end of the open magnetic path core H2o closer to the gap is the N pole. current 12
This shows the case where the flow is carried out. In this case, vertical magnetic flux is generated at the bottom of the drawing. FIG. 2(b) shows a case where the current 12 is passed in the opposite direction through the open magnetic path core H20 so that the end of the core H2o on the gap side becomes the S pole. In this case, perpendicular magnetic flux is generated on the upper side of the drawing. This figure 5(a)
.

The device shown in (b) is used in place of the devices shown in FIGS. 2(a) and (b). That is, in FIG. 3, the magnetic heads H1 and H2 are replaced with those shown in FIGS. 5(a) and 5(b).
A magnetic head H1''20 can be used.

According to the above embodiment, the following effects can be obtained.

That is, when constructing a magnetic copying apparatus using a bias magnetic field, it is necessary to increase the strength of the perpendicular component magnetic field or to supply an appropriate bias magnetic field depending on the magnetic material used for the slave tape. Conventionally, the bias magnetic field has been determined by the physical dimensions and material constants of the head. However, in the embodiment described above, the vertical component/horizontal component ratio, intensity, and frequency can be determined and changed electrically by the variable resistor as desired.

Therefore, even if the same head uses various tapes such as metal tape or barium ferrite tape as the slave tape, the bias magnetic field can be changed instantaneously without replacing the bias head. Since the vertical component/horizontal component ratio can be set accurately electrically, transfer efficiency can be significantly improved without demagnetizing the master tape.

(Effects of the Invention) According to the present invention, the ratio of the vertical and horizontal magnetic field strengths of the copying bias magnetic field applied to the master recording medium and the slave recording medium can be set to an appropriate value according to those media. , thereby making it possible to copy appropriately depending on the medium.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the essential parts of an embodiment of the present invention, Fig. 2 is an explanatory diagram showing its operation, Fig. 3 is a circuit diagram showing its drive circuit, and Fig. 4 is the distribution of its bias magnetic field. A magnetic field distribution diagram showing the state, FIG. 5 is an explanatory diagram showing the operation of different embodiments,
FIG. 6 is a diagram explaining the principle of magnetic copying, FIG. 7 is a characteristic diagram showing an example of measurement of bias magnetic field distribution, and FIG. 8 is a plan view showing conventional magnetic copying.

Claims (1)

[Claims] A magnetic recording medium that brings a master recording medium and a slave recording medium into pressure contact, applies a bias magnetic field for copying to those media in that state, and copies information prerecorded on the master recording medium to the slave recording medium. A copying apparatus, comprising a first excitation means and a second excitation means, which are provided to face each other with the master recording medium and the slave recording medium in a press-contact state interposed therebetween, and each generate a magnetic field by flowing an excitation current; The first excitation means is configured as a closed magnetic circuit core with a gap, the second excitation means is provided with at least one end of the core facing the first excitation means, and further, the first excitation means a first current supply means for supplying a first AC excitation current for exciting the second excitation means, and a second AC excitation current for exciting the second excitation means is synchronized with the first AC excitation current. a second current supply means for supplying the second alternating current as a current, and the second current supply means has a phase difference adjusting means capable of adjusting a phase difference between the second alternating current and the first alternating current. Copying equipment.