DE4030326C2 - Magnetic recording and reproducing apparatus having a plurality of composite magnetic heads and method of manufacturing a composite magnetic head usable with this apparatus - Google Patents

Description

The invention relates to a device for magnetic Recording and playback with multiple composite Magnetic heads according to the preamble of patent claim 1 as well as a method for producing one at this Device usable composite magnetic head.

From JP 1-223608 A, such a device for magnetic recording and playback with multiple Composite magnetic heads known, the individual composite Magnetic heads each have a main gap and a pair of Have pseudo columns. The main gap of the first composite Magnetic head has an azimuth angle, which for the Record or play back a first signal on a Track is set. The pseudo columns of the first composite Magnetic head are neither parallel to the main gap of the first composite magnetic head still parallel to the main gap of a second composite magnetic head. In this publication  the second composite magnetic head only serves as Erase head and not as a second read / write head.

Another composite magnetic head is known from US 4701819 known to have a main gap and a pair of Has pseudo columns, the main gap in is substantially perpendicular to the main axis of the magnetic head, while the position of the pseudo columns is determined such that they are not parallel to the main gap.

Furthermore, from US 4769898 a composite magnetic head and a method for its production is known in which the Magnetic head made of different materials and therefore, in addition to the main gap, also has pseudo-columns. However, the pseudo-columns are beat-shaped and in designed essentially parallel to the main gap.

Furthermore, JP 1-67707 A is another composite Magnetic head with a turn substantially perpendicular to the Main axis of the magnetic head standing main gap and one Pair of pseudo columns known, in which case the Pseudo columns arcuate and essentially parallel to Main gap are arranged.

10, according to the VHS HiFi or S-VHS HiFi system according to FIG. 10, a recording azimuth 12 for the video signal and a recording azimuth 13 for a frequency-modulated audio frequency signal are used on a single recording track 11 recorded. When the video signal is recorded, the frequency-modulated audio frequency signal is recorded as a track in the depth of the same recording track 11 . Now consider the case that the composite magnetic head shown in Fig. 10 is used as the video head. If for the video head the azimuth angle of the pseudo-gap 2 is selected to be equal to or very close to the azimuth angle of the main gap (not shown) chosen for the other frequency for the audio frequency signal, namely for the sound head, ie the recording azimuth 13 , the pseudo-gap 2 will Video head recorded an audio frequency signal, which deteriorates the signal-to-noise ratio of a signal recorded through the main gap 1 of the video head. The same problem occurs with the head.

The invention is therefore based on the object of a device for magnetic recording and playback with several Composite magnetic heads of the type mentioned above to further develop that several signals on one Recording track can be recorded or played back can, with a large signal-to-noise ratio or a high Recording / playback quality is ensured. Further is said to be a method of making one with this device usable composite magnetic head can be specified.

Regarding the magnetic recording device and Playback will do this task according to the characteristic Features of claim 1 solved.

With regard to the method, this task is performed according to the characterizing features of claim 8 solved.

Due to the fact that the azimuth angles of the main and Pseudo columns of several arranged side by side Composite magnetic heads can be set differently thus the signal-to-noise ratio when recording or playing back improved several signals on one recording track become.

In the subclaims 2 to 7 are advantageous Characterized embodiments of the invention.

The invention is illustrated below with reference to embodiments play explained with reference to the drawing.

Show it:

Fig. 1 is a Ausführungsbei game,

Fig. 2 Aufzeichnungsazimuthe at a standard mode,

3 is a graphical representation illustrating the calculation of reproducing Azimuthverlusten on a pseudo gap on a video signal, wherein the azimuth angle of the pseudo gap is set as a parameter Fig.

Fig. 4 is a graph showing the calculation of dospalt playback Azimuthverlusten to the Pseu illustrates in a frequency-modulated audio signal, wherein the azimuth angle of the pseudo gap is set as a parameter,

FIGS. 5 and 6 in perspective and in plan view a composite magnetic head according to an embodiment,

Fig. 7 are perspective views, the composite magnetic head shown in said sequence to FIG. 5 in the Aufeinan show manufacturing processes,

Fig. 8 is a view for explaining a state in which the composite magnetic head shown in FIG. 5 of a VHS video tape recorder, a recording track under scanning surface contact at a long time mode with this,

Fig. 9 is an illustration for explaining a state in which a composite magnetic head according to a further embodiment scans a recording track corresponding to the recording track shown in Fig. 8 with surface contact therewith, and

Fig. 10 is an illustration for explaining problems that arise when a reproducing operation or a recording / reproducing operation is performed with a conventional compound magnetic head.

Fig. 1 shows a main gap 1 and pseudo column 2 of a composite magnetic head 21 according to 12 (z. B. a Videosig Nals) one embodiment, a Aufzeichnungsazimuth a signal is distinguished 1 up with the azimuth angle of the main air gap, a Aufzeichnungsazimuth 13 of a Signal (e.g. a frequency modulated audio signal) recorded with an azimuth angle different from that of the main slit 1 , an angle Θ 1 that the recording azimuth 12 of a video signal recorded with the azimuth angle of the main slit forms with the pseudo slit 2 , an angle Θ 2 that the recording azimuth 13 of a frequency-modulated or FM audio frequency signal recorded with the azimuth angle, which is different from that of the main gap 1 , forms with the pseudo gap 2 , an angle Θg that the pseudo gap 2 with the width direction a recording track 11 forms an azimuth angle Θ 11 of the main gap 1 and an A zimuth angle Θ 22 of the recording azimuth 13 of the FM audio frequency signal recorded with the azimuth angle different from the main gap 1 , that is, the azimuth angle of the main gap of the head. Here, angles are clockwise positive angles.

According to Fig. 1 of the pseudo gap 2 forms the angle Θ 2 with the Aufzeichnungsazimuth 13 of the FM audio signal recorded muthwinkel with the different from the azimuth angle of the main gap 1 Azi, and the angle Θ1 with the Aufzeichnungsazimuth 12 of the video signal with the Azi muthwinkel the main gap 1 is recorded.

Generally, an azimuth loss L is given by the following equation given:

where w is the track width, λ is the recording wavelength and Θ the azimuth angle difference between the azimuth angle of a recorded signal and the azimuth angle of one Playback slit; the following also applies:

Θ 1 = Θ _g - Θ 11 and

Θ 2 = Θ _g - Θ 22 (2)

According to equation (1), by inserting Θ 1 and Θ 2 for Θ, it is possible to determine the conditions for Θ 1 and Θ 2 such that a required azimuth loss is achieved in a desired range of recording wavelengths. Furthermore, it becomes possible to reduce the reproduction sensitivity for a signal picked up by the pseudo-gap 2 , namely the reproduction sensitivity for the FM audio frequency signal which is recorded with the azimuth angle 13 , which is different from the azimuth angle of the main gap 1 , and the reproduction sensitivity for the video signal recorded at the azimuth angle 12 which is equal to that of the main slit 1 . As a result, the output level of the signal picked up by the pseudo gap 2 is suppressed or decreased, thereby making it possible to almost completely turn off the deterioration of the signal-to-noise ratio of the signal picked up by the main gap 1 .

As described above, in a VHS-HiFi or S-VHS-HiFi system video tape apparatus, a method is applied in which an FM audio frequency signal is recorded in the deep area of the video signal track to obtain a high quality audio frequency signal. In addition, can be switched between adjacent recording tracks 11 between the recording azimuths 12 and 13 for the video signal and the FM audio frequency signal. D. h., FIG. 2 is recorded on a Aufzeich voltage trace 11 a the video signal and the FM audio signal at angles .theta.v = 6 ° and Θa = -30 ° to the track width Rich tung, while b to a next Aufzeich voltage track 11, these signals are recorded at angles Θv = -6 ° and Θa = 30 ° to the track width direction. Since the method according to this embodiment and the effects achieved are the same for both channels, they are explained only with regard to the first recording track. The recording azimuths 12 and 13 shown in Fig. 2 represent an embodiment in a standard mode (SP mode).

If, according to FIG. 2, the azimuth angle Θg of the pseudo-gap 2 is determined in such a way that a sufficient azimuth loss L is achieved according to equation (1), the deterioration of the signal-to-noise ratio of the video signal can be prevented in a suitable manner.

As an example, the calculation of the playback azimuth loss L of the video signal is shown in FIG. 3 in the standard operating mode or SP operating mode of a video tape device with a VHS hi-fi system, the azimuth angle Θg of the pseudo gap 2 being set as a parameter. The calculation is carried out by inserting Θ 1 into equation (1).

The azimuth loss L is calculated here in that the equation (1) as λ the recording wavelength at a carrier frequency 629 kHz of a color signal, namely the longest recording wavelength of a video signal is set to a sufficient for the video signal Get azimuth loss.

Furthermore, it is considered sufficient that the reproducibility of the pseudo-gap 2 is one-tenth that of the main gap 1 , namely -20 dB, and that the total loss of the pseudo-gap 2 is one hundredth of that of the main gap 1 , namely -40 dB. It is therefore seen that the azimuth angle Θg satisfies this first condition in the range of -22 ° or below and 32 ° or above.

Furthermore, the calculation of the reproducing azimuth loss L in FIG. 4 for the FM audio signal, wherein both of the pseudo gap 2 is used as a parameter as shown in Fig. 3 of the azimuth angle. The calculation is done by inserting Θ 2 into equation (1).

The azimuth loss is calculated by the fact that in the Equation (1) as λ the longest recording wavelength of the FM audio frequency signal is used, which with a lower carrier frequency of 1.3 MHz of the two carrier fre frequencies of the FM audio frequency signal is recorded, or for 1.7 MHz and 1.3 MHz.

It can therefore be seen that the azimuth angle Θg the the aforementioned azimuth loss condition second Condition in the range -39.5 ° or below and -18 ° or about that is enough.

Furthermore, since the angle is obviously in the range of -90 ° <Θg <90 °, the azimuth angle Θg the first condition and the second condition in the following Area:

-90 ° <Θg ≦ -39.5 ° or 32 ° ≦ Θg <90 °

FIGS. 5 and 6 show in perspective view and in plan view a composite magnetic head. In FIGS. 5 and 6 with 4 a and 4 b semi-core yoke assemblies formed of a magnetic oxide material such as MnZn ferrite described net, which together form a magnetic core 31. 32 with magnetic metal films are referred to, which consist of Sendust or an amorphous alloy and which are each formed on the opposite surfaces of the two half-core yoke units 4 a and 4 b. At 33 , a non-magnetic gap spacer for setting the main gap 1 is designated as a magnetic gap for recording or reproducing a signal on or from a (not shown) recording medium. With 34 a flint glass or Ver connection glass is referred to, which is inserted between the half-core units 4 a and 4 b and is melted to secure them; 35 is a winding window opening for inserting a coil; with 36 is a molded glass or cast glass, which has a lower softening point than the flint glass or connecting glass 34 and which is melted and applied to the surface of the half-core units 4 a and 4 b in order to summarize the core units.

The method for producing this composite magnetic head in the sequence of process steps will now be explained with reference to FIG. 7. First, as shown in FIG. 7 (a) on gap surfaces 41 a and 41 b of half-core blocks 4 a and 4 b with a diamond grinding wheel, grooves 42 a and 42 b for the connecting glass as well as a plurality of grooves 43 a and 43 b and 43 c to 43 f incorporated in order to determine the track width in such a way that the bottoms of the latter grooves do not run parallel to the gap surfaces 41 a and 41 b. With regard to these track width determination grooves, a track width determination groove on the half-core unit 4 a corresponds to a pair of track width determination grooves on the other half-core unit 4 b, the groove width being chosen to be greater than the entire track width w according to FIG. 1. Furthermore, the center of the groove formed on the half-core unit 4 a, or the bottom of the V-shaped groove and the center of the pair of grooves formed on the other half-core unit 4 b, namely the triangular intersection, are aligned such that they are centered on the track width w fall.

Second, according to FIG. 7 (b), the magnetic metal film 32 is sprayed onto the track width determination grooves 43 a to 43 f, the grooves 42 a and 42 b for the connecting glass 34 and the other gap surfaces 41 a and 41 b of the two half-core units 4 a and 4 b trained.

Third, according to FIG. 7 (c), the grooves 42 a and 42 b for the connecting glass 34 and the grooves 43 a to 43 f for the track width determination are filled with the flint glass or connecting glass 34 . Furthermore, the winding window opening 35 is incorporated on the track surface 41 a of the half-core unit 4 a.

Fourth, the gap surfaces 41 a and 41 b are polished in accordance with FIG. 7 (d) in such a way that the width of the floor covering a track is kept sufficiently wide than the final track width w. Subsequently, a gap spacer 33 is formed by spraying a film. In this case, it makes no difference whether the gap spacer 33 is applied to the gap surface 41 a or 41 b on one side or on both sides.

Fifth, according to FIG. 7 (e), the undersides of the two half-core units 4 a and 4 b are aligned, a rough alignment being sufficient, and the half-core units 4 a and 4 b are put up with temporary clamping. Thereafter, in the winding window opening 35, a glass rod is inserted 34 A from the bonding glass 34, after which the whole is melted bonding glass 34, so that the Halbkerneinhei th 4 a and 4 b together to form a one-piece core block be connected.

Sixth, grooves 44 a and 44 b are worked in with the diamond grinding wheel in such a way that the predetermined track width w is achieved. The bottoms of these grooves 44 a and 44 b are lower than the apex of the Wicklungsfen star opening 35 , ie that the grooves 44 a and 44 b are deeper than the gap; this prevents the formation of a closed magnetic circuit. In the grooves 44 a and 44 b, a glass with a lower softening point than the connecting glass 34 is filled and melted to form the cast glass 36 (the glass molding section).

Seventh, according to FIG. 7 (g), the one-piece core block is cut into small plates along cutting lines M and N.

In this way, the composite magnetic head shown in Fig. 5 is made. If necessary, the surface that comes into contact with the magnetic tape during scanning can be machined into a rounded shape. A winding (not shown) is then placed through the winding window opening 35 .

Fig. 8 is an illustration for explaining a state in which the magnetic head according to the embodiment in a long-term mode (EP mode) of the VHS hi-fi video tape device scans the recording track while keeping the touch on the surface of the track. Fig. 8 shows the main gap 1 , the pseudo column 2 , a contact surface 41 on which the composite scanning magnetic head is held in contact with the track surface, the recording azimuth 12 for the video signal, the recording azimuth 13 for the FM audio frequency signal and azimuth angle Θg1 and Θg2, each of which forms the pseudo gap with the track width direction.

According to Fig. 8 are on tracks 11 a and 11 c, the video signal at an azimuth angle of 6 ° and the FM Tonfrequenzsig nal at an azimuth angle of 30 ° tung recorded to the track width Rich, while on another track 11 b, the video signal at an azimuth angle of -6 ° is recorded and the audio frequency signal is recorded at an azimuth angle of -30 °. In the long-term mode or EP mode, the video signal and the audio frequency signal on the tracks in the sequence 11 a- 11 b- 11 c. . . recorded. The track 11 b which, like those of the head has been recorded with the same width, is in the manner shown in Fig. 8 lane width w characterized aligned so that the signal is overwritten in the recording at an overlapping area Tw.

According to Fig. 8 is the area in which the azimuth angle of the pseudo gap 2 corresponds to the azimuth angle of the set in the depth recorded FM audio signal, reduced to a designated D small area, whereby the disturbance of the received at the main gap 1 signal is considerably reduced .

The azimuth angles Θg1 and Θg2 of the pseudo-gap 2 are to be determined in such a way that a sufficient azimuth loss L according to equations (1) and (2) can be achieved.

Fig. 9 shows an embodiment which is achieved by an improvement in the game Ausführungsbei shown in Fig. 8. According to FIG. 9, the apex of the pseudo gap 2 is offset from the center of the head and aligned with the edge portion of the recording track. This eliminates the overlap area at which the azimuth angle of the pseudo-gap 2 coincides with the azimuth angle of the FM audio frequency signal. This results in a clearer or more interference-free signal.

According to the above, it becomes possible with the composite magnetic head according to the invention to considerably reduce the interfering effects caused by the signal taken from the pseudo-gap 2 from the signal taken from the main gap 1 , and thereby to reproduce a signal which concerns of the useful signal / interference signal ratio or signal-to-noise ratio is better.

Therefore, there is an advantage in the magnetic recording / reproducing apparatus equipped with the composite magnetic head described above that the signal level with which the pseudo gap receives the signal which is reproduced or recorded by the main gap 1 of the other head can be reduced; thereby the Störab stood that signal is improved, which is reproduced or recorded and reproduced at the main gap 1 of the magnetic head.

Claims (8)

1. A device for magnetic recording and playback with a plurality of composite magnetic heads, each having a main gap ( 1 ) and a pair of pseudo columns ( 2 ), wherein
the main gap ( 1 ) of a first composite magnetic head has an azimuth angle which is fixed for recording and / or reproducing a first signal (FM audio frequency signal) on a track ( 11 ),
the pseudo-gaps ( 2 ) of the first composite magnetic head each have an azimuth angle that is not parallel to the main gap ( 1 ) of the first composite magnetic head, and
the pseudo-gaps ( 2 ) of the first composite magnetic head are not parallel to the main gap ( 1 ) of a second composite magnetic head, characterized in that
the main gap ( 1 ) of the second composite magnetic head has a fixed azimuth angle which is fixed for the recording and / or reproduction of a second signal (video signal) on the track ( 11 ) and which is related to the azimuth angle of the main gap ( 1 ) of the first composite Magnetic head is different. 2. Device according to claim 1, characterized in that the azimuth angle Θg of the pseudo column ( 2 ) are determined in that an azimuth loss L at the pseudo gap is calculated, where w is the recording track width, λ is a recording wavelength and the angle Θ is the azimuth angle difference Θ 1 = Θg-Θ 11 between the azimuth angle of the pseudo column ( 2 ) and the azimuth angle of a recording signal ( 12 ) or the azimuth angle difference Θ 2 = Θg-Θ 22 is used between the azimuth angle of the pseudo column ( 2 ) and that of another recording signal ( 13 ), Θ 11 is the azimuth angle of the first signal recorded with an azimuth angle which is equal to the azimuth angle of the main gap ( 1 ) of the is the first composite magnetic head on which the pair of pseudo columns is formed, and Θ 22 is the azimuth angle of the second signal recorded with an azimuth angle that is equal to the azimuth angle of the main gap ( 1 ) of the second composite magnetic head on which the pseudo-gaps ( 2 ) are formed, with protruding L in obtaining a desired azimuth loss de equation as the angle Θ the angles Θ 1 and Θ 2 are used to determine the angle Θg as the azimuth angle of the pseudo column ( 2 ). 3. Apparatus according to claim 2, characterized in that the azimuth angle Θg of the pseudo column ( 2 ) meets one of the following conditions: -90 ° <Θg ≦ -39.5 ° or 32 ° ≦ Θg <90 ° 4. Device according to one of claims 1 to 3, characterized in that the pseudo-gap ( 2 ) is V-shaped or vice versa V-shaped to the recording azimuth angle. 5. Apparatus according to claim 4, characterized in that the apex of the V-shaped or vice versa V-shaped pseudo gap ( 2 ) coincides with the center of the magnetic head. 6. Apparatus according to claim 4, characterized in that the apex of the V-shaped or vice versa V-shaped pseudo gap ( 2 ) coincides with the edge of a recording track ( 11 ). 7. Device according to one of claims 1-6, characterized in that the azimuth angle of the main column ( 1 ) of the first and second composite magnetic head for video signals or for audio frequency signals are fixed. 8. A method for producing a composite magnetic head that can be used in a device according to claims 1 to 7, characterized by the steps:
Incorporation of a large number of grooves ( 42, 43 ) into half-core blocks ( 4 ) for a connecting glass ( 34 ) and for setting the track width,
Spraying a magnetic film ( 32 ) on the grooves ( 42, 43 ) and the gap surfaces ( 41 ) of the half-core blocks ( 4 ),
Filling the grooves ( 42, 43 ) with connecting glass,
Polishing the gap surfaces ( 41 ) and spraying a film as a gap spacer ( 33 ),
Aligning the half-core blocks ( 4 ),
Melting the connecting glass ( 34 ) for integrally connecting the two half-core blocks ( 4 ),
Incorporation of additional grooves ( 44 ) for the track gauge (w) and melting of glass into these grooves, and
Cut the one-piece core block into small plates.