JPH0740329B2 - Rotating magnetic head unit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary magnetic head device for a helical scan video tape recorder, and more particularly to a rotary magnetic head device having an erasing rotary magnetic head.

[Background of the Invention]

In home-use helical scan video tape recorders (hereinafter referred to as VTRs), when performing continuous shooting or inserting, generally, a method of overwriting a new signal on a track formed on a magnetic tape is adopted.
However, according to this method, there is a problem that the previously recorded signal remains unerased and the S / N of the reproduced signal is deteriorated.

As one method of solving such a problem, an erasing rotary magnetic head is provided in the rotary magnetic head device prior to a video signal recording / reproducing rotary magnetic head (hereinafter referred to as a video head) to directly erase a track on a magnetic tape. However, it is known that a signal is recorded by a video head on the portion erased by this. According to this, not only the unerased portion of the signal previously recorded on the magnetic tape can be eliminated, but also the fixed magnetic head for full-width erasing which has been used conventionally is not required, and the miniaturization of the VTR is promoted. There is an advantage that

By the way, the erasing performance of the erasing magnetic head is expressed by the erasing rate defined by (signal reproducing level after erasing) / (signal reproducing level before erasing), and the frequency and magnitude of the erasing current and saturation of the head. It is related to magnetic flux density and magnetic gap length. Therefore, in order to obtain an erasing rate capable of sufficiently erasing the video signal, for example, the erasing magnetic head is made of a material having a high saturation magnetic flux density, and the magnetic gear length is 3
μm, the frequency of the erasing signal is equal to or higher than the frequency of the video signal, and the magnitude of the erasing current is 3 to
5 times. As a method of obtaining such a large erasing current, for example, as disclosed in JP-A-57-117109, it is known to provide a peaking circuit between a signal source of an erasing signal and a recording amplifier. There is.

On the other hand, between the recording amplifier for the video signal and the video head, and between the recording amplifier for the erasing signal and the erasing rotary magnetic head, signal lines are respectively provided via rotary transformers. In the rotating magnetic head having a diameter of 62 mm or 40 mm, the signal lines for video signals and the signal lines for erasing signals are almost parallel to each other and are very closely arranged at intervals of several mm or less.

For this reason, in the above-mentioned conventional technique in which the erasing signal has a large current, the erasing current leaks to the video signal signal line, and there is a problem that beat interference or S / N deterioration occurs on the reproduction screen.

[Object of the Invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotary magnetic head device which solves the above-mentioned problems of the prior art and prevents an erase signal from interfering with a video signal to increase the erase rate.

[Outline of Invention]

To achieve this object, the present invention provides a mounting base of an erasing rotary magnetic head comprising a substrate and a capacitor integrally formed with the substrate, the capacitor being connected in parallel with the erasing rotary magnetic head. As described above, the erasing signal is peaked by the capacitor and the inductance of the erasing magnetic head for erasing.

Example of Invention

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

FIG. 1 is a plan view showing an embodiment of a rotary magnetic head device according to the present invention, in which 1 is a rotary cylinder, 2a and 2b are video heads, 3 is a rotary magnetic head for erasing, and 4a, 4b and 5 are attached. Bases, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b are signal lines, 10 are capacitors, and 11a, 11b are through holes.

In the figure, video heads 2a and 2b and an erasing rotary magnetic head (hereinafter simply referred to as erasing head) 3 are attached to the rotary cylinder 1 via mounting bases 4a, 4b and 5, respectively. The video heads 2a and 2b are arranged symmetrically with respect to the center 0 of the rotary cylinder 1. Further, the erasing head 3 is arranged in front of the video head 2b as a rotating cylinder rotating counterclockwise in the drawing, and a track which the video head 2b on a magnetic tape (not shown) scans and then a video head 2b. The track width of the magnetic gear and the step difference with respect to the video heads 2b and 2a are set so that two tracks including the track scanned by 2a can be simultaneously erased.

The video head 2a is attached to the mounting base 4a, and the signal line 6a connected to each terminal of its winding (not shown).
Is connected to the signal line 9a through a cross-hatched pattern wiring formed on the mounting base 4a. The signal line 9a is connected to the rotary transformer shown in FIG. 2 through the through hole 11a. The same applies to the video head 2b, and the signal line 9b is connected to the rotary transformer through the through hole 11b.

The erasing head 3 is also attached to the mounting base 5, and the mounting base 5 is provided with a capacitor 10, and one terminal of a winding (not shown) of the erasing head 3 has a signal line 7a.
Is connected to one electrode of the capacitor 10 and the other terminal of the winding is connected to the other electrode of the capacitor 10 via the signal line 7b. Both electrodes of the capacitor 10 are also connected to signal lines 8a and 8b, respectively, and these signal lines 8a and 8b are connected to the rotary transformer through the through holes 11a. Therefore, the capacitor 10 is connected in parallel with the erase head 3.

FIG. 2 is a vertical cross-sectional view taken along the line X-O-X 'in FIG. 1, in which 12 is a bearing, 13 is a rotary shaft, 14 is a disk, 15 is a fixed cylinder, 16 is a rotary transformer, 16a is a rotor, Reference numeral 16b is a stator, 17 is a screw, and 18 is a shield wire, and the portions corresponding to FIG.

In FIG. 2, a rotary shaft 13 which is rotationally driven by a motor (not shown) is rotatably supported by a fixed cylinder 15 by a bearing 12. A disk 14 is fixed to the tip of the rotary shaft 13, and the rotary cylinder 1 is integrally attached to the disk 14. Mounting bases 4a, 4b, 5 are attached to the bottom surface of the rotary cylinder 1 with screws 17.

Further, a space is provided between the rotary cylinder 1 and the fixed cylinder 15, and the rotary transformer 16 is arranged in this space. The rotary transformer 16 includes a rotor 16a and a stator 16b that face each other.
The rotor 16a is fixed to the disk 14, and the stator 16b is mounted to the fixed cylinder 15. As shown in FIG. 1, the rotor 16a is connected to signal lines 8a, 8b, 9a, 9b through through holes 11a, 11b, and the stator 16b is shielded from a recording amplifier or a reproducing amplifier (not shown). Line 18 is connected.

In this configuration, the capacitor 10 provided on the mounting base 5 and the inductance of the erase head 3 form a peaking circuit. This peaking circuit has the function of enhancing the erase current for enhancing the erase performance, and as a result, the shield line 18 to the rotary transformer 16 and the signal lines 8a, 8
The erase current passing through b can be set small enough not to interfere with the recording signal supplied to the video heads 2a and 2b.

FIG. 3 is a partial sectional view showing a specific example of the mounting base 5 in FIG. 1, in which 19 is an electrode layer, 20 is a dielectric layer, 21 is an electrode layer, and 22a, 22b, 23a and 23b are electrodes, respectively. Terminals, 24 is a non-magnetic substrate, 24a is a protruding portion, 25 is a resist, 26 is a wiring substrate, 27
Is a screw hole, 28 is a winding wire, and the portions corresponding to those in FIG.

In FIG. 3, the mounting base 5 is composed of a non-magnetic substrate 24 and a wiring substrate 26, and a protruding portion provided on the non-magnetic substrate 24.
Erasing head 3 is attached to 24a. This non-magnetic substrate 24 is made of brass, BeCu, nickel silver, stainless steel, or MnO-NiO.
It is desirable to use a material that can be sintered and has a low coefficient of thermal expansion, such as a ZrO ₂ system or a ZrO ₂ system.

The wiring board 26 has a laminated structure of an electrode layer 19, a dielectric layer 20, and an electrode layer 21, and the capacitor 10 (FIG. 1) is formed by these. Two electrode terminals 22b and 23b are formed on the electrode layer 19 (two electrode terminals 22a and 22b are also formed on the electrode layer 21. Then, the winding of the erase head 3 is formed on the electrode terminal 22a. The signal line 7a from one end of the winding 28 is connected, and the signal line 7b from the other end of the winding 28 is connected to the electrode terminal 22b.
Are connected. Further, signal lines 11a and 11b are connected to the electrode terminals 23a and 23b, respectively. This allows the electrode layer 1
The capacitor 10 composed of 9,21 and the dielectric layer 20 is connected in parallel to the erase head 3. A resist 25 is provided on the upper surface of the wiring board 26 in order to separate the electrode terminals 22a, 22b, 23a, 23b from each other.

A material that can be vapor-deposited such as Cu is used for the electrode layers 19 and 21, and a material that can be vapor-deposited is Al ₂ O ₃ or SiO as a material for the dielectric layer 20.
₂ , SiO, SiNTiO, La (MgZr) O ₃ , LaCrO ₂ , BoTiO ₂ , Bi ₂ O ₃
SnO ₂ , TaO ₂ or the like can be used.

In such a mounting base 5, the screw 17 is passed through the screw hole 27, and the second
As shown in the figure, it is fixed to the rotary cylinder 1.

In this way, the wiring board 26 forming the capacitor 10 in FIG.
Is integrally formed on the non-magnetic substrate 24,
These are very tightly connected and the rotary cylinder 1
Even if (Fig. 1) suddenly starts rotating at high speed or suddenly stops, the capacitor 10 will be disengaged from the non-magnetic substrate 24 compared to the case where the capacitor is simply placed on the mounting base. Moreover, since the capacitor 10 is connected to the erase head with the shortest transmission path, the transmission loss of the erase signal can be reduced.

FIG. 4 is a circuit diagram showing a signal transmission system of this embodiment, in which parts corresponding to those in the previous drawings are designated by the same reference numerals.

In the figure, the portion surrounded by the broken line is the portion of the mounting base 5, and the peaking circuit is formed by the capacitor 10 and the inductance of the erasing head 3 in this portion.

The capacitance of the capacitor 10 formed by the electrode layers 19 and 21 and the dielectric layer 20 in FIG. 3 depends on the thickness t of the electrode layers 19 and 21, the thickness T of the dielectric layer 20, and the area S of the dielectric layer 20. And use the materials listed above as the material for the dielectric layer 20, and Then, the capacitance C _{p of the} capacitor 10 is 1000 to 6000 pF. Therefore, the capacitance C _p of this capacitor 10 = 1000 pF, the inductance L of the erasing head 3 L = 0.5 μH, the rotary transformer 1
If the erase current at 6 is 60mA, the erase head 3 winding 28
, Erase current of 2000mA per turn, -35dB
(Color signals) can be erased. This erase rate is
A home VTR has sufficient image quality performance.

By the way, when each signal line is arranged as described in FIGS. 1 and 2, the stray capacitance between the signal line of the erase signal and the signal line of the video signal is recorded from each base 4a, 4b, 5 Or the one up to the reproduction amplifier is the maximum. In FIG. 4, this is divided into a stray capacitance C _K1 on the head side and a stray capacitance C _K2 on the amplifier side from the rotary transformer 16.

Now, _letting K ₁ and K ₂ be the crosstalk amounts of the erase signal by the stray capacitances C _K1 and C _K2 to the video signal, these are expressed by the following equation.

Where ω: frequency of video signal, ω ′: frequency of erase signal L _V : inductance of video signal side rotor 16a L ′ _V : inductance of video signal side stator 16b I _V : video signal primary current, I ′ _V : video signal secondary current L _F: inductance L cancellation signal side rotor 16a _'F: inductance I _F cancellation signal side stator 16b: erase signals the primary current, 1' _F: floating in erase signal secondary current FIG. 4 volume C _K1, C _K2 are first view, in the configuration shown in FIG. 2, a _{10~30pF, L 'V, L'} F = 10~40μH I 'V, I' with _F = _10~50mA Atsute, I _V, I _F is the turns ratio of the rotary transformer 16 1: 2 to 1: connexion determined by the 4. When the crosstalk amounts K ₁ and K ₂ are calculated from these conditions using the equations (1) and (2), these are −50 dB.
Within that range, the image quality performance is sufficient.

FIG. 5 is a process chart showing a specific example of a method of manufacturing the base 5, and the same reference numerals are given to the portions corresponding to FIG.

First, the non-magnetic substrate 24 was formed from a sinterable ceramic (MnONiO, ZrO ₂ , MgOSiO ₂ ). (FIG. 5 (a)). Other non-magnetic materials such as brass and stainless steel can be used as long as they can deposit a predetermined material on the upper surface. in this case,
A screw hole 27 is also formed.

Next, a cylindrical PIQ 40 is inserted into the screw hole 27, a conductive material such as Cu or W is deposited, and when a predetermined film thickness is reached, a mask is applied and deposition is further continued. As a result, the electrode layer 19 and the electrode terminals 22b and 23b are formed as shown in FIG. 5 (b). Then, a dielectric material is deposited on the entire surface of the electrode layer 19 to form a dielectric material layer 20 (FIG. 5 (c)). The material of the dielectric is determined by the affinity with the electrode layer 19, the coefficient of thermal expansion, the dielectric constant, etc. If the material of the non-magnetic substrate 24 is ZrO ₂ ,
Lanthanum-based and barium titania-based materials are preferable.

Next, the electrode layer 21 and the electrode terminals 22a and 22a are formed on the entire surface of the dielectric layer 20 in the same manner as when the electrode layer 19 is formed (FIG. 5 (d)). In this case, the side surfaces of the electrode terminals 22b and 23b are also covered with the dielectric layer 20 in the step of FIG. 5C so that the electrode 21 does not come into contact with the electrode terminals 22b and 23b already formed.

Then, a layer of resist 25 is provided on the entire surface of the electrode layer 21 up to the surface of the electrode terminals 22a, 22b, 23a, 23b, and the PIQ 40 is pulled out (fifth).
Figure (e)).

Through the above steps, the base 5 is obtained, the erase head 3 is attached to the base 5, and the signal lines are connected to the electrode terminals 22a, 22b, 23a, and 23b.

FIG. 6 is a partial cross-sectional view showing another specific example of the mounting base 5 in FIG. 1, 19a, 19b, 21a, 21b are internal electrode layers, and the same reference numerals are given to the portions corresponding to FIG. I am wearing it.

In this specific example, one electrode layer 19 is further provided with two internal electrode layers 19a and 19b at predetermined intervals, and the other electrode layer is composed of two internal electrode layers 21a and 21b. The internal electrode layers 19a and 19b and the internal electrodes 21a and 21b are alternately stacked with a dielectric layer in between.

As a result, the multilayer capacitor 10 is obtained, and the capacitor 10 having a predetermined capacity can be obtained by selecting the number of layers.

Other points are the same as the specific example shown in FIG.

FIG. 7 is a perspective view showing still another specific example of the mounting base 5 in FIG. 1, 29, 30 are electrode terminals, 31, 32 are electrodes, 31a to 31d, 32a to 32d are electrode layers, 34 Is a dielectric layer, and the same symbols are given to the portions corresponding to the above drawings.

In this specific example, strip-shaped electrode terminals 29 and 30 are provided on both edges of the upper surface of the non-magnetic substrate 24, and electrodes are placed between these electrode terminals 29 and 30.
A capacitor 10 composed of 31,32 is provided. Electrode 3
1 is composed of electrode layers 31a to 31d arranged in a sawtooth shape, and the electrode 32 is also composed of electrode layers 32a to 31d arranged in a sawtooth shape, one of these electrode layers 31a to 31d, 32a to 32d. The other is arranged so that the other is inserted, and the dielectric layer 33 is provided between these electrode layers.

In this specific example, the same effect as the specific example shown in FIGS. 3 and 6 is obtained, and when the mounting base 5 is attached to the rotary cylinder 1, the head 17a of the screw 17 is placed on the surface of the non-magnetic substrate 24. Since it contacts with the head of the screw 17 from the upper surface of the wiring board 26, as in the concrete example shown in FIG. 3 and FIG.
17a never projects. Therefore, capacitor 10
If the height of is less than or equal to the height of the head 17a of the screw 17,
The space for mounting the mounting base 5 on the rotary cylinder 1 is
The space is about the same as the space required for a conventional mounting base without a capacitor, and it is possible to prevent the rotating magnetic head device from increasing in size.

In this embodiment, the electrodes 31 and 32 are connected to the nonmagnetic substrate 24.
May be formed integrally with the electrode terminals 29, 3 separately.
It may be attached to 0.

〔The invention's effect〕

As described above, according to the present invention, since the erasing current is peaked on the erasing head side, the erasing current in the portion where the signal line of the recording signal and the signal line of the erasing signal are close to each other can be made sufficiently small. The interference of the erase signal with the recorded signal can be sufficiently reduced, and the inductance of the erase head winding is used instead of a separate peaking circuit, and the erase head mounting base can be used. Since the peaking is performed with the formed capacitor, it is possible to suppress the increase of the space due to the provision of the peaking means, and the mounting base of the erase head is connected to the board in parallel with the erase head. Since the capacitor to be used is formed integrally, there is no possibility that a shock may cause the capacitor to come off. Further, since it is provided integrally with the same mounting base an erasing head and said capacitor,
It is possible to obtain excellent effects such as reduction of transmission loss of the erased signal and reduction of power consumption.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a rotary magnetic head device according to the present invention, FIG. 2 is a longitudinal sectional view taken along the section line X--O--X 'in FIG. 1, and FIG. 3 is shown in FIG. FIG. 4 is a partial sectional view showing a specific example of the mounting base of the erasing rotary magnetic head, FIG. 4 is a circuit diagram showing the signal transmission system in FIG. 1, and FIG. 5 is a method of manufacturing the mounting base shown in FIG. 6 is a process diagram showing one specific example, FIG. 6 is a partial sectional view showing another specific example of the erasing rotary magnetic head in FIG. 1, and FIG. 7 is still another specific example of the erasing rotary magnetic head in FIG. It is a perspective view which shows an example. 1 ... Rotary cylinder, 2a, 2b ... Rotary magnetic head for recording / reproducing video signals, 3 ... Rotary magnetic head for erasing, 5 ... Mounting base, 10 ... Capacitor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Tamura 1410 Inada, Katsuta City, Ibaraki Prefecture Inside the Tokai Works, Hitachi, Ltd. (56) References: 60-146902 (JP, U)

Claims (2)

[Claims] 1. A rotary magnetic head device comprising a rotary transformer, wherein a rotary magnetic head for recording / reproducing video signals and a rotary magnetic head for erasing are mounted via mounting bases, respectively. The mounting base has a flat plate shape, a substrate having a protrusion for mounting the erasing rotary magnetic head, and a capacitor integrally formed on almost the entire surface of the substrate other than the protrusion. The capacitor consists of 2n capacitors (where n is 1) separated from each other by a dielectric layer.
The above integers), the first electrode terminal integrated with every other n electrode layers, and the second electrode terminal integrated with every other n electrode layers. And the first electrode terminal is one terminal of the capacitor to which one terminal of the winding of the erasing rotary magnetic head and one signal line from the rotary transformer are connected. The second electrode terminal is the other terminal of the capacitor to which the other terminal of the winding of the erasing rotary magnetic head and the other signal line from the rotary transformer are connected. Rotating magnetic head device. 2. A rotary magnetic head device comprising a rotary transformer, wherein a rotary magnetic head for recording / reproducing a video signal and a rotary magnetic head for erasing are mounted via mounting bases, respectively. The mounting base has a flat plate shape and has a substrate having a protrusion for mounting the erasing rotary magnetic head and a mounting screw hole, and a portion other than the protrusion and the mounting screw hole on the surface of the substrate. A capacitor formed integrally with the portion and having a height equal to or less than the height of the screw head when inserted into the mounting screw hole, the capacitors being separated from each other by a dielectric layer. 2n (where n is 1
The above integers), the first electrode terminal integrated with every other n electrode layers, and the second electrode terminal integrated with every other n electrode layers. And the first electrode terminal is one terminal of the capacitor to which one terminal of the winding of the erasing rotary magnetic head and one signal line from the rotary transformer are connected. And the second electrode terminal is the other terminal of the capacitor to which the other terminal of the winding of the erasing rotary magnetic head and the other signal line from the rotary transformer are connected. Rotating magnetic head device.