JPS62129902A - Rotating magnetic head device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application 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 equipped with a rotary magnetic head for erasing.

[Background of the invention]

Helical scan video tape recorder for home use (
When performing splicing or inserting in a VTR (hereinafter referred to as a VTR), a method is used in which a new signal is overwritten on the track formed on the magnetic tape.

However, this method has the problem that previously recorded signals remain unerased and the S/N of the reproduced signal deteriorates.

One way to solve this problem is to provide a rotary magnetic head for erasing in advance of a rotary magnetic head for recording and reproducing video signals (hereinafter referred to as the video head) in a rotary magnetic head device, and directly erase tracks on the magnetic tape. However, it is known that a video head records a signal on the erased portion. This not only makes it possible to eliminate unerased signals previously recorded on the magnetic tape, but also eliminates the need for a fixed magnetic head for full-width erasing, which was previously used, and promotes the miniaturization of VTRs. It has the advantage of being

By the way, the erasing performance of the erasing magnetic head is expressed by the erasing rate determined by (signal reproduction level after erasing)/(signal reproduction level before erasing), and is determined by the frequency and magnitude of the erasing current, and the saturation of the head. Related to magnetic flux density and magnetic gap length. Therefore, in order to obtain an erasing rate that can sufficiently erase video signals, for example, the erasing magnetic head is constructed using a material with a high saturation magnetic flux density, and the magnetic gap length is set to 3μ.
m, the frequency of the erase signal is set to be higher than the frequency of the video signal, and the magnitude of the erase current is set to about 3 to 5 m of the video signal.
It is doubled. As a method of obtaining such a large erase current, it is known to provide a peaking circuit between the signal source of the erase signal and the recording amplifier, as disclosed in, for example, Japanese Patent Laid-Open No. 57-117109. There is.

On the other hand, signal lines are connected between the video signal recording amplifier and the video head and between the erasing signal recording amplifier and the erasing rotary magnetic head via rotating transformers, respectively. In a rotating magnetic head with a diameter of 62 mm or 40 mm, the video signal signal line and the erase signal line are wired almost parallel to each other and extremely close to each other with an interval of several mm or less.

For this reason, in the above-mentioned conventional technology in which the erasing signal is a large current, there is a problem that the erasing current leaks to the video signal signal line, causing beat disturbance on the reproduced screen and a reduction in S/N.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotary magnetic head device that solves the problems of the prior art described above, prevents interference of the erase signal with the video signal, and increases the erase rate.

[Summary of the invention]

In order to achieve this object, the present invention is characterized in that a capacitor is provided on the base of the rotating magnetic head for erasing, and the erasing signal is peaked by the capacitor and the inductance of the rotating magnetic head for erasing. There is.

[Embodiments of the 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 erasure, 4a and 4b
, 5 is the mounting base, 6a, 6b, 7a, 7b, 8a, 9
b, 9a, 9b are signal lines, 10 is a capacitor, lla,
Ilb is a through hole.

In the figure, a video spatula F2a, 2b and an erasing rotating magnetic head (hereinafter simply referred to as an erasing head) 3 are attached to a rotating cylinder 1 via mounting bases 4a, 4b, 5, respectively. The video heads 2a, 2b are arranged at symmetrical positions with respect to the center 0 of the rotating cylinder l. Further, the erasing head 3 is arranged in advance of the video head 2b with a rotary cylinder rotating counterclockwise in the drawing, and the erasing head 3 is arranged in advance of the video head 2b on a magnetic tape (not shown).
two tracks, the track scanned by video head 2a and the track scanned by video head 2a, can be erased simultaneously;
The track width of the magnetic gap and the level difference between the video heads 2b and 2a are set.

The video head 2a is attached to a mounting base 4a, and the signal wires 6a connected to the respective terminals of its windings (not shown) follow the wiring pattern shown as a crosshatch formed on the mounting base 4a. It is connected to the signal line 9a through the signal line 9a. This signal line 9a passes through a through hole 11a and is connected to a rotating transformer shown in FIG. Video hella l'
The same goes for 2b, and the signal line 9b is connected to the through hole 1.
It is connected to the rotating I lance through 1b.

The erasing head 3 is also attached to the mounting base 5, and the mounting base 5 is provided with a capacitor 1o.
One terminal of the erase head 30 winding (not shown) receives the signal v
A7a is connected to one electrode of this capacitor 10, and the other terminal of this winding is connected to capacitor 1 through signal line 7b.
o, respectively. Further, both electrodes of the capacitor 1o are also connected to line 13 lines 8a and 8b, respectively, and these signal lines 8a and 8b are connected to the rotary transformer through a through hole 11a. Therefore, capacitor 1
0 is connected in parallel with the erase head 3.

FIG. 2 is a longitudinal cross-sectional view taken along the x-o-x' line in FIG.
16b is a stator, 17 is a screw, and 18 is a shield wire, and parts corresponding to those in FIG. 1 are given the same reference numerals.

In FIG. 2, a rotating shaft 13 rotated by a motor (not shown) is rotatably supported by a fixed cylinder 15 through a bearing 12. As shown in FIG.

A disk 14 is fixed to the tip of the rotating shaft 13, and a rotating cylinder l is integrally attached to the disk 14. A mounting base 4 is attached to the bottom of this rotating cylinder 1.
a, 4b, and 5 are attached with screws 17.

Further, a space is provided between the rotating cylinder I and the fixed cylinder 15, and a rotating transformer 16 is arranged in this space. The rotary transformer 16 consists of a rotor 16a and a stator 16b facing each other, the rotor 16a being fixed to the disk 14 and the stator 16b being attached to the fixed cylinder 15. As shown in FIG. 1, this rotor 16a has signal lines 3a, 3 passing through through holes 11a, 1],
b.

9a and 9b are connected, and a shielded wire 18 from a recording amplifier and a reproduction amplifier (not shown) is connected to the stator 16b.

In this configuration, a peaking circuit is formed by the capacitor 10 provided on the mounting base 5 and the inductance of the erasing head 3. This peaking circuit has the function of increasing the erasing current to improve the erasing performance, so that the erasing current that passes from the shield wire 18 to the rotary transformer 16 and the signal lines 8a and 8b is transmitted to the video head 2a,
It can be set small enough not to interfere with the recording signal supplied to 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, 22a, 22b.

23a and 23b are electrode terminals, 24 is a non-magnetic substrate, 2
4a is a protrusion, 25 is a resist, 26 is a wiring board, 27
The punch hole 28 is a winding, and parts corresponding to those in FIG. 1 are given the same reference numerals.

In FIG. 3, the mounting base 5 consists of a non-magnetic substrate 24 and a wiring board 26, and the erasing head 3 is attached to a protrusion 24a provided on the non-magnetic substrate 24. This nonmagnetic group +ffj24 is desirably formed of a material that can be sintered and has a low coefficient of thermal expansion, such as brass, BeCu, nickel silver, stainless steel, Mn0-Ni0 series, ZrO2 series, etc.

Distribution %1 substrate 26 is tiil 9, dielectric r/l 120
and an electrode layer 21, forming a capacitor 10 (FIG. 1). Moreover, the electric fiJi 19 has two electrode terminals 22b.

23b is formed, and the electrode layer 21 also has two electrode terminals 2'.
la and 22b are formed. And electrode terminal 22
The signal line 7a from one end of the volume vA28 of the erasing head 3 is connected to the electrode terminal 22b.
8 is connected to the signal line 7b from the other end. Further, the electrode terminals 23a and 23b have signal lines 11a and Ilb, respectively.
is connected. Thereby, the capacitor 10 consisting of the electrode layer 19, 21 and the dielectric layer 20 is connected in parallel to the erasing head 3. A resist 26 is provided on the upper surface of the wiring board 26 to separate the electrode terminals 22a, 22b, 23a, and 23b.

′:! The unipolar layers 19 and 21 are made of a material that can be deposited by vapor, such as Cu, and the material of the dielectric J'W20 is Al, O, SiO□, Sin, 5iNTiO,
La (MgZr)O,, LaCr0z.

BoTiOz, Biz O* ・5noffi
, Tact, etc. can be used.

This mounting base 5 has screws 17 passed through screw holes 27,
As shown in FIG. 2, it is fixed to the rotating cylinder 1.

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

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

Electrode layer 19.21 and dielectric material rrJ2 in FIG.
The capacitance of the capacitor 10 due to the electrode layer 19.21
It is determined by the thickness t of the dielectric layer 20, the thickness T of the dielectric layer 20, and the area S of the dielectric layer 20.1. And when t = 500 people T = 2000 people 3 = l c me', the capacitance MkC,, of the capacitor 10 is 1000
~6000pF. Therefore, if the capacitance Cp of the capacitor 10 is 1000 pF, and the inductance L of the erasing head 3 is 0.5 μH, and the erasing current in the 1-rotation transformer 16 is 60 mA, the winding 28 of the erasing head 3 has 1
Erase current flows to 20QOm per turn, -35dB
(color signal) erasure rate becomes possible. This erasing rate is sufficient in terms of image quality and performance for home VTRs.

By the way, when each signal line is arranged as explained in FIG. 1 and FIG. 2, the stray capacitance between the signal line of the erase signal and the signal line of the video signal is the same as that of each base 4a.

The largest number is from 4b and 5 to the recording or playback amplifier. In Fig. 4, this is expressed as the stray capacitance Ckl from the rotary transformer 16 to the head side, and the stray capacitance fC* on the amplifier side.
It is shown separately by z.

Now, let us assume that the amount of crosstalk of the erase signal to the video signal due to these stray capacitances CKI+Ckt is as follows.
These are expressed as follows.

(2) where ω: frequency of video signal, ω′: frequency of cancellation signal Lv: inductance of video signal side rotor 16a L′v: inductance of video signal side stator 16b v: video signal Primary current, I'v: Video signal secondary current,: Erase 1 word side rotor 16a inductance L'F: Erase signal side stator 16b inductance ■,: Erase signal primary current, ■'F: Erase The stray capacitance CKI+CKZ in the signal secondary current in Fig. 4 is shown in Fig. 1.

In the case of the configuration shown in Fig. 2, it is 10 to 30 pF, L'V, L'F''10 to 40 μ, I I'v, I'v = 10 to 50 mA, and IV and IF are rotary transformers. 16 turns ratio 1:
Determined by 2 to 1:4. From these conditions, formula (1)
, T2+, the crosstalk amount KI, is calculated to be 2, which is within -50 dB, which is sufficient in terms of image quality performance.

FIG. 5 is a process diagram showing a specific example of a method for manufacturing the base 5, and parts corresponding to those in FIG. 3 are given the same reference numerals.

First, sinterable ceramics (MnONiO, ZrO2, M
A non-magnetic substrate 24 was formed using g OS I O2).

(Figure 5(a)). Other non-magnetic materials can be used, such as brass or stainless steel, as long as a predetermined material can be deposited on the upper surface. In this case, a screw hole 27 is also formed.

Next, insert the cylindrical PTQ4Q into the screw hole 27, and
A conductive material such as U or W is deposited, and when a predetermined film thickness is reached, a mask is applied and the deposition is continued for further ms*. Thereby, as shown in FIG. 5(b), the electrode layer 19 and electrode terminals 22b and 23b are formed. Then, a dielectric material is deposited on the entire surface of the electrode [19] to form a dielectric layer 20 (FIG. 5(C)).

The dielectric material is determined based on affinity with the electrode layer 19, coefficient of thermal expansion, dielectric constant, etc.1. When the material of the nonmagnetic substrate 24 is ZrO, lanthanum-based or barium titania-based materials are preferable.

Next, in the same manner as in the case where the electrode layer 19 is formed on the entire surface of the dielectric layer 20, the Tl electrode layer 21 and the electrode Pj layers 22a, 2 are formed.
3a (FIG. 5(d)).

In this case, the electrode terminal 22 on which the electrode 21 is already formed
b, 23b and tfl To avoid unnecessary damage, the side surfaces of the electrode terminals 22b and 23b are also coated with the dielectric layer 20' in the process shown in FIG. 5(c).
7' Make it covered.

Then, the entire surface of the electrode layer 21 is connected to an electrode terminal 22a.

250 layers of resist are provided up to the surfaces of 22b, 23a, and 23b, and the PIQ/lo is pulled out (FIG. 5(e)). Through the above steps, the base 5 is obtained. The erasing head 3 is attached to this, and then the electrode terminal 22a is formed.

Each signal line is connected to 22, b, 23a, and 23b.

FIG. 6 is a partial cross-sectional view showing another specific example of the mounting base 5 in FIG. 1, 193, 19b.

21a and 2tb are internal electrode layers 7j, and portions corresponding to those in FIG. 3 are given the same reference numerals.

In this specific example, one electrode layer 19 is further provided with two internal electrode layers 9a and 19b at a predetermined interval, and the other electrode layer is provided with two internal electrode layers 21a.

21b, and the internal monopole layers 19a, 19b and the internal electrodes 21a, 21b are arranged on the electrode layer 19 with dielectric layers interposed therebetween, and the internal electrodes 21a, 21b are arranged alternately in mW.

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

Other points are similar to 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, in which 29.30 is an electrode terminal;
．． 32 is an electrode, 31a to 31d.

32a to 32d are electrode layers, 34 is a dielectric layer, and parts corresponding to those in the previous drawings are given the same reference numerals.

In this specific example, electrode terminals 29 and 30 are provided in the form of strips on both edges of the upper surface of the non-Ti substrate 24.
．． A capacitor IO consisting of electrodes 31 and 32 is provided between the electrodes 30 and 30. The electrode 31 consists of electrode layers 31a to 31d arranged in a sawtooth pattern, and the electrode 32 also consists of electrode layers 32a to 31d arranged in a sawtooth pattern, and one of these electrode layers 31a to 31d, 32a to 32d A dielectric layer 33 is provided between these electrode layers.

In this specific example, when the mounting base 5 is attached to the rotating cylinder 1, the screw H17a of the screw 17 is attached to the non-magnetic substrate 24.
Since this makes contact with the surface of the wiring board 26, the head 17a of the screw 17 does not protrude from the upper surface of the wiring board 26 as in the specific examples shown in FIGS. 3 and 6. Therefore, if the height of the capacitor 1o is equal to or less than the height of the head 17a of the screw 17, the space required for mounting on a mounting pace of 50 rotations is the same as that required for a conventional mounting base without a capacitor. This makes it possible to prevent the rotating magnetic head device from becoming larger.

In this embodiment, the electrodes 31 and 32 may be formed integrally with the nonmagnetic substrate 24, but they may also be formed separately and attached to the electrode terminals 29 and 30.

〔Effect of the invention〕

As explained above, according to the present invention, since the erasing current is peaked on the erasing head side, the erasing current can be sufficiently reduced in the portion where the recording signal signal line and the erasing signal signal line are close to each other. , the interference of the erase signal with the recording signal can be sufficiently reduced, and instead of having a separate circuit for peaking, the inductance of the winding of the erase head is used, and the peaking circuit is installed on the mounting base of the erase head. Since peaking is performed with the formed capacitor, the increase in space due to the provision of the peaking means can be suppressed, and furthermore, the erasing head and the capacitor are integrally provided on the same mounting base. Therefore, it is possible to obtain excellent effects such as being able to reduce the transmission loss of the erasure signal and achieving lower power consumption.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of a rotating magnetic head device according to the present invention, FIG. 2 is a longitudinal sectional view taken along the dividing line X-o-x' in FIG. 1, and FIG. Partial sectional view showing a specific example of the mounting base of the rotary magnetic head for erasing, No. 4
The figure is a circuit diagram showing the signal transmission system in Fig. 1, Fig. 5 is a process diagram showing a specific example of the manufacturing method of the mounting base shown in Fig. 3, and Fig. 6 is the rotating magnet for erasing in Fig. 1. FIG. 7 is a partial sectional view showing another specific example of the head, and FIG. 7 is a perspective view showing still another specific example of the erasing rotary magnetic head shown in FIG. DESCRIPTION OF SYMBOLS 1... Rotating cylinder, 2a, 2b... Rotating magnetic head for recording and reproducing video signals, 3... Rotating magnetic head for erasing, 5... Mounting base, 10... Capacitor. W57', - Fig. 1 IX' Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 23゜(b) [

Claims (1)

[Claims] In a rotary magnetic head device including a rotary magnetic head for recording and reproducing video signals and a rotary magnetic head for erasing, a capacitor is provided on a mounting base for mounting the rotary magnetic head for erasing, and a capacitor is provided on a mounting base for mounting the rotary magnetic head for erasing, and the inductance of the rotary magnetic head for erasing is A rotary magnetic head device characterized in that the capacitor is configured to enable peaking of an erase signal.