JPS6236289B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a tape guide device for a magnetic recording/reproducing device.

First, a conventional tape guide device of this type will be explained with reference to FIGS. 1 and 2. FIGS. 1 and 2 are flow diagrams of fluid (air) in a conventional tape guide device. In Figures 1 and 2, 3 is a rotating drum of the tape guide drum;
35 is a magnetic tape, 45 is a tape guide (pin) that regulates the tape winding angle (a little more than 180 degrees here) on the tape guide drum. This is the case where it is located inside the tape 35 (on the magnetic layer side).

In Figures 1 and 2, θ is the rotating drum 3
Angular coordinates along the circumference of θ=0°, θ=90
゜, θ=180゜ are the rotating drum 3 and tape 35, respectively.
Indicates the point of contact with θ=0° on the front side and θ=0° on the rear side.
180°, and the intermediate position is θ=90°. Also, c
is a visualization of the front flow between the rotating drum 3 and the tape 35, and the direction of the arrow represents the fluid vector. d is a visualized portion of the trailing flow between the rotating drum 3 and the tape 35, and the arrow portion represents the fluid vector. Further, h indicates the flying height of the tape 35 with respect to the rotating drum 3 (thickness of the air film).

Now, it is generally thought that the gas bearing theory can be applied between the rotating drum 3 and the tape 35, but in the industry, in reality, the thickness of the tape 35 tends to become thinner year by year, and the tape 35 and the drum Since the shape of No. 3 also has a finite length, the fluid phenomenon becomes complicated. It is no exaggeration to say that this complicated fluid phenomenon appears as a problem or drawback of the conventional tape guide device due to a causal relationship.

To explain the fluid phenomenon of a conventional tape guide device with reference to FIGS. 1 and 2, for example, when the diameter is 110 mm,
The rotating drum 3 has an angular velocity ω (for example, 2π×
30 rad/s) in the direction of the arrow, a turbulent vortex vector c is generated as a fluid phenomenon in the front region of θ=0° as shown by the arrow. Also, θ
As shown by the arrow, a turbulent vortex vector d is also generated in the rear region of =180°. Further, in the front region where θ=0°, the inertial flow prevents the air film amount h between the drum 3 and the tape 35 from becoming uniform. Also, θ=
The 180° rear region causes longitudinal vibration to the tape 35 due to expansion flow, and in the magnetic recording device,
Jitter and wow and flutter will occur.
As described above, the conventional tape guide device suffers from various kinds of deterioration in performance due to the turbulent vortices of c and d.

Next, FIG. 3 shows an example of actually measured tape floating characteristics of the conventional tape guide device shown in FIGS. 1 and 2. Third
In the figure, the horizontal axis is the tape winding angular position θ (degrees), and the vertical axis is the tape flying height h (μm). The experimental conditions were that the diameter of drum 3 was 110 mm and the rotation speed was 1800 r.p.
m, the thickness of the tape 35 is 27 μm, and the width is 3/4 inch (=1.9 cm). It can also be seen from FIG. 3 that the non-uniformity of the tape flying height h is remarkable. Also, θ≧180
Fluid phenomena in the ° range are the cause of jitter and wow and flutter.

Therefore, the conventional tape guide device has the following drawbacks. There is an effect of disturbance due to fluid. The uneven thickness of the air film causes uneven contact between the magnetic head and the tape. Frequency characteristic S/N deteriorates. Induces longitudinal vibration (jitter, wow and flutter). The rotating drum is making a lot of noise. The life of the tape and rotating magnetic head is short.
Significant changes over time. Poor compatibility (especially problematic as the tape gets thinner).

The present invention has been proposed in an attempt to overcome and improve the drawbacks of the above-mentioned conventional devices.

The present invention provides a tape guide drum equipped with a rotating magnetic head, and a magnetic tape winding start position and winding end position of the tape guide drum, respectively, located close to the tape guide drum and facing the rotating magnetic head. A rotationally adjustable eccentric rectifying guide device having a constriction is provided to equalize the flying height of the magnetic tape relative to the tape guide drum.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a plan view of an example of a tape guide device of a magnetic recording/reproducing apparatus according to the present invention, and FIG. 5 is a longitudinal sectional view thereof. In FIGS. 4 and 5, 1 is an eccentric rectification guide (or fluid control guide), and 2 is a guide set screw (guide shaft). 3 is a rotating drum (upper drum), 4 is a fixed drum (lower drum)
These constitute a tape guide drum. 5
is a rotating shaft of the rotating drum 3, and 6 is a rotating flange. 7 is a rotating magnetic head (transducer);
8 is a head set screw, and 9 is a head height adjustment screw. 10 is a flange set screw, 11 is a washer, 12 is a set screw, 13 is a drum set screw,
14 is a head substrate. 15 is a rotor of the rotating transformer, and 16 is a stator of the rotating transformer.
17 is a magnet assembly constituting the rotational position signal generator, 18 is a fine adjustment screw, and 19 is a PG coil (pulse generator coil). 20 is a preload spring, 21 is a ball bearing, and 22 is a bearing nut. 23 is a positioning pin, 24
is the base. 25 is a yoke plate, and 26 is an insulating seal. 27 is a bobbin, 28 is a motor coil, 29 is a motor board, 30 is a motor magnet, and 31 is a yoke plate. 32 is Watsusha, 3
3 is a set screw. 46 is a positioning pin.

The rotating drum 3 and fixed drum 4 that guide the magnetic tape form a pair with coaxial cores.
A rotating drum 3 having several heads 7 is mounted on a rotating flange 6. This flange 6 is attached to the rotating shaft 5, supported by two bearings 21, and has a direct drive structure {symbol 25
~30}.

At a position adjacent to the pair of drums 3 and 4, an eccentric rectifying guide (fluid control guide) device a,
Place b. The guide devices b and a are arranged near the contact points of the drums 3 and 4 and the tape 35, and are positioned as a front region fluid control guide device and a rear region fluid control guide device, respectively. Tape 35 is drum 3, 4
and the fluid control guide 1 of the guide devices a, b, and is wound around the drum circumference. Now when the drum 3 rotates, the Reynolds equation for fluid lubrication is given as follows.

δ/δx(ph3δp/δx)+δ/δz(ph ³ δz/
δp) = 6μUδ(ph)/δx+12μδ(ph)/δt By the way, in the conventional tape guide device, as the tape thickness becomes smaller, as shown in Fig. 3,
In addition to the Reynolds equation, tape deformation occurs due to disturbances. Therefore, in order to eliminate such an inconvenient phenomenon, in the embodiment of the present invention, as shown in FIGS. 4 and 5, by providing fluid control guide devices a and b, the Reynolds equation is corrected. It becomes possible to create a form that satisfies the conditions.

The fluid control guide devices a and b shown in FIGS. 4 and 5 each consist of a fluid control guide 1 and a guide set screw (guide shaft) 2, the detailed structure of which is shown in cross-section in FIG.

In FIG. 6, fluid control guide devices a and b are located adjacent to the drums 3 and 4, a tape 35 is arranged between the drums 3 and 4 and the control guide 1, and the drums 3 and 4 are It is wound around the circumferential surfaces of the drums 3 and 4 with a radial gap formed by fluid lubrication.

What is particularly problematic here is the positioning accuracy of the gap ( _ha ) between the drums 3, 4 and the fluid guide 1 for determining the tape flying height (thickness h of the air film). In the embodiment of the present invention, the fluid control guide 1 has an eccentric cam shape, and by selecting the eccentricity ε to be approximately 10 to 100 μm, the gap h _a between the drums 3 and 4 and the fluid guide 1 is In the guide control device b, h _a =42 μm, and in the fluid control guide device a, h _a =29.5 μm. The guide 1 is provided with a constriction 1a extending around the entire circumference of the guide 1 at a portion facing the rotating magnetic head 7 so as not to impede its rotation. Here, the thickness t of the tape 35 is 27μ
It is m. In other words, the forcibly regulated tape floating height (thickness h of the air film) is h = 15μ in device b.
m, h=2.5 μm in device a.

After the adjustment of h _a of each part of the apparatuses a and b is completed, the fluid guide 1 is tightened and fixed to the base 24 with the set screw 34 via the spring washer 34.

Fig. 7 and Fig. 8 show fluid control guide devices a and b.
A modified example is shown. In Fig. 7, the fluid guide 1 has an eccentric cam shape, and the eccentric amount ε is
The diameter _d2 is 10 to 100 μm and 3 to 4 mm. Base 2
The shaft 2 is inserted into the reference hole 4, and is rotatable by a spring 38. 37 is a flat washer or E-ring. When the adjustment of h _a is completed, the pin 40 is pushed by tightening the taper screw 39, and the fluid guide shaft 2 is tightened and fixed.

Further, in FIG. 8, an eccentric cam-shaped fluid guide 1 is attached to a guide shaft 2 press-fitted into a base 24, and the fluid guide 1 is attached to a nut 44 via a spring 43.
Fixed by

Next, the positional relationship between the fluid guide devices a and b will be explained with reference to FIGS. 9 to 12. In FIG. 9, guide devices a and b are outside the tape 35, θ=0°, θ
= 180° position. In FIG. 10, the guide devices a and b are arranged between the tape 35 and the drum 3 at the start and end positions of the tape 35. In FIG. 11, the position of the guide device a is the same as in FIG. 10, and the position of the guide device b is the same as in FIG. 9. In FIG. 12, the position of guide device a is the same as in FIG. 9, and the position of guide device b is the same as in FIG. 10.

The tape from the tape cassette shown in FIG. 10 is pulled out and loaded onto the tape guide drums {drums 3, 4}. It is suitable for application to ordinary VTRs, and 50 and 51 are tape guides (pins) (corresponding to 45 in Figs. 1 and 2) that regulate the winding angle of the tape 35 on the drums 3 and 4. .
Note that the guide devices a and b are tape guides 50 and 51.
It is closer to the drums 3 and 4 than the drums 3 and 4.

Next, referring to FIG. 13, a special VTR suitable for applying the present invention will be described. This is a VTR
The unit is built into a television receiver, and open reels 54 and 55 are built into the VTR unit. The tape 35 is always loaded onto the drums 3 and 4. 50,
51 is a tape guide that regulates the winding angle of the tape 35 around the drums 3 and 4, and 52 and 53 are tape guides that change the running direction of the tape 35.

Figures 9 to 12 are all special cases of Figure 13.
Applicable to VTR. However, in FIG. 10, the tape guides 50 and 51 are excluded. Also, Figure 9~
Guide devices a and b in FIG. 12 are tapes 35
In this case, it is desirable to provide flanges at both upper and lower ends of the guide 1 to regulate the width direction of the tape 35.

Fig. 14 shows the characteristic curve of the tape flying height h (μm) against the tape winding angle position θ (degrees) in the conventional device with the dashed-dotted line (corresponding to the curve in Fig. 3).
, and the one according to the present invention is shown by a solid line.
According to this, in the case of the present invention, compared to the conventional device,
The tape flying height (thickness of the air film) h is made uniform, and the contact of the rotating magnetic head 7 between the spans of the fluid control guides a and b is optimized, which contributes to various performances such as improved image quality and improves the performance of the fluid control guides c and d. Disturbance factors can be removed by the fluid control guide devices a and b.

According to the present invention described above, there are the following advantages.
To smoothly lubricate air between a tape guide drum and a tape. The tape flying height (air film thickness) can be made uniform. The effects of external disturbances can be removed (jitter and wow and flutter are reduced). Image quality improves (the rotating magnetic head hits the tape optimally). The tape and rotating magnetic head will have a longer lifespan and their damage will be eliminated.
Changes over time are reduced. This will lead to lower prices for magnetic recording and reproducing devices.

[Brief explanation of the drawing]

1 and 2 are schematic plan views showing a tape guide device of a conventional magnetic recording/reproducing device, FIG. 3 is a conventional characteristic curve diagram, and FIG. 4 is a plan view showing an embodiment of the present invention. , Fig. 5 is its vertical cross-sectional view, Fig. 6 A, B
7 and 8 are cross-sectional views showing essential parts of other embodiments of the present invention, and FIGS. 9 and 10 11 and 12 are schematic plan views of each embodiment of the present invention, and FIG. 13 is a schematic plan view showing an example of a preferred magnetic recording and reproducing apparatus to which the present invention is applied. FIG. 14 is a characteristic curve diagram of the conventional and the present invention. a and b are eccentric rectification guide devices (fluid control guide devices), 1 is the fluid guide, 1a is the constriction,
2 is a guide shaft, 3 and 4 are rotating and fixed drums constituting a tape guide drum, and 35 is a magnetic tape.

Claims (1)

[Claims] 1. A tape guide drum equipped with a rotating magnetic head, and a magnetic tape winding start position and a winding end position of the tape guide drum, respectively, in proximity to the tape guide drum and at a portion facing the rotary magnetic head. 1. A tape guide device for a magnetic recording and reproducing device, characterized in that a rotationally adjustable eccentric rectifying guide device having a constriction is provided to equalize the flying height of the magnetic tape with respect to the tape guide drum.