JPH0312384B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording/reproducing device, and particularly to a magnetic recording/reproducing device suitable for use in a VTR or the like equipped with a rotating magnetic head that utilizes centrifugal force.

In general, in a rotating drum type VTR, a so-called air film can exist between the rotating drum and the tape under certain conditions, but in today's electronic machinery industry, in reality, the thickness of the tape is They tend to become thinner year by year, and the shapes of recording media such as magnetic tapes and drums have finite lengths, making fluid phenomena increasingly complex. In this case, the complexity of this fluid phenomenon becomes conspicuous as a problem or drawback of the prior art.

To explain the fluid phenomenon of this prior art with reference to FIGS. 6 and 7, suppose that the rotating drum 1 is rotating in the direction of the arrow, for example, with a diameter φ110 and an angular velocity ω=2π×30 rad/s. , tape winding angle position θ
A turbulent vortex vector as shown by arrow e ₁ occurs in the front region of = 0°, and similarly a turbulent vortex vector as shown by arrow e ₂ occurs in the rear region of tape winding angle position θ = 180°. arise. In addition, the inertial flow in the front region of θ=0° has a negative effect on the uniformity of the amount of air film between the rotating drum 1 and the magnetic tape 2, while the turbulent vortex in the rear region of θ=180° This causes longitudinal vibration of tape 2,
When applied to a magnetic recording/reproducing device, jitter, wow, flutter, etc. will occur.

As described above, in the prior art, various performances of the device are degraded due to the turbulent vortices. The diameter of the rotating drum 1 is φ110, and the drum rotation speed is 1800 r.p.
m, the tape 2 thickness is 27 μm, and the tape width is 3/4'', the curve of the tape flying height with respect to the tape winding angle position θ according to the prior art is shown by the broken line in FIG. 10.As can be understood from this figure, In the case of the prior art, the non-uniformity of the flying height of the tape is noticeable.

Next, regarding the problem of contact between the rotating magnetic head 3 and the tape 2, as shown by the broken line in FIG. This will have a negative effect on the impact of head 3 on the target. Also, if the head pressure is large or fluctuates greatly, the tape 2 will deteriorate.
Alternatively, it may cause the head 3 to become clogged, and it will take more time to clean it.

In view of these points, the present invention can improve various characteristics such as the S/N ratio of the device by removing turbulent vortices that degrade various performances of the device, and can also automatically clean the magnetic head. The present invention provides a magnetic recording and reproducing device.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the basic structure of the present invention, FIG. 1A is a plan view thereof, and FIG. 1B is a side view of a rotating magnetic head 4 according to the present invention. In FIG. 1, 5 is a head chip, 6 is a centrifugal force auxiliary board to which the head chip 1 is fixed, 7 is a front centrifugal force balance spring that elastically supports one side of the auxiliary board 6, and 8 is the auxiliary board 6. a rear centrifugal force balance spring elastically supporting the other side; 9 a head board to which springs 7 and 8 are fixed; 10 placed on the head board 9 so as to abut one side of the auxiliary board 6; This is a damper for absorbing vibrations of the auxiliary board 6, springs 7, 8, etc. These parts 5 to 10 constitute the head 4. This head 4 is attached to the rotating drum 1 through a head attachment hole 11 formed in a head base plate 9.

12 is a fluid guide disposed close to the drum 1, and 13 is a cleaning member built into the fluid guide 12, the structures of which will be described in detail later. In this figure, for convenience of explanation, the fluid guide 12 and the cleaning member 13 are shown enlarged from their actual size.

14 is a sliding trajectory of the head tip 5 on the tape, 15 is a sliding trajectory of the head tip 5 on the tape at an angular velocity ω ₁ , 16 is a sliding trajectory of the head tip 5 on the tape at an angular velocity ω ₂ , and a is the initial stage of the head. The amount of protrusion, b is the amount of head protrusion at angular velocity ω ₁ , c is the increment of the amount of head protrusion when the angular velocity changes from ω ₁ to ω ₂ , d is the amount of head protrusion when the tape is sliding, and e is the initial amount of head protrusion. This is the difference between a and the amount of head protrusion when the tape is sliding.

Next, to explain the operation of this embodiment, when the head 4 is mounted on the drum 1, the amount of protrusion of the head tip 5 is adjusted in advance so that when the drum 1 is stationary, the amount of protrusion of the head tip 5 is the initial amount of protrusion a of the head. has been done. Now, when the drum 1 is rotated in the direction of the arrow f at an angular velocity ω ₁ , the head tip 5 of the head 4 will fly out from the position of the initial protrusion amount a to the position of the protrusion amount b due to the centrifugal force effect, and will move on the orbit 15. . Therefore, first considering the centrifugal force Fc of the head chip system, it becomes Fc=W/g(R+b)ω ² ...(1). In the above equation (1), W is the equivalent weight, g is the gravitational acceleration, R is the radius of the drum 1, and ω is the angular velocity.

Next, considering this centrifugal force Fc from the spring system of the head 4, it becomes Fc=k(ba-a)...(2). In the above equation (2), k is a composite spring constant.

When the head protrusion amount b is determined from the above equations (1) and (2), it becomes b=ka+W/gRω ² /kW/gω ² (3).

For example, now k = 0.118g/μm, W = 0.03g,
With a shape of R = 37.5 mm, the initial protrusion amount a of the head is
Adjust to 16 mm and move drum 1 at angular velocity ω ₁ (2π×
30rad/s), the amount of head protrusion b〓 ₁ (30) is: b〓 ₂ (30) = ka + W / gRω ₁ ² / k - W / gω ₁ ² = 50.
5μm...(4) That is, the head tip 5 protrudes 50.5 μm from the circumferential surface of the drum 1 in the radial direction. In reality, the head chip 5 is ω=2π× in Fig. 1.
The orbit radius at 30 rad/s is R+b〓 ₁ (30)=
37.55mm, it will move on orbit 15.

Next, when cleaning is performed when the head 4 is clogged, the head tip 5 is further projected to come into contact with the cleaning member 13. That is, by increasing the angular velocity to 2π×40 rad/s (ω ₂ ), which is larger than that during steady operation, the amount of head protrusion b〓 ₂ (40) becomes b〓 ₂ (40)=ka+W/gRω ₂ ² /k−W. /gω ₂ ² =77.
5 μm...(5) Therefore, the trajectory of the head chip 5 during cleaning becomes the trajectory 16 shown in FIG. 1, and the radius of the trajectory is R+b〓 ₂ (40)=37.577 mm. In this case, the increment c of the head protrusion when changing from the steady state to the cleaning state is the difference between the above equations (5) and (4), so from both equations, c = b〓 ₂ (40) - b〓 ₁ (30)=27μm...(6) Therefore, by positioning the circumferential surface of the cleaning member 13 at a distance of, for example, 27 μm or less (≦b+c), the head tip 5 will slide on the cleaning member 13, and the head tip 5 will be cleaned by the cleaning member 13. That will happen.

Furthermore, when calculating the centrifugal force at angular velocities ω ₁ and ω ₂ at this time, from the above equation (1) or (2), Fcω(30)=4g−W and Fcω(40)=7.3g−W ……(7 ) becomes.

Generally, when the drum 1 is rotated at a constant speed, the head tip 5 jumps out to the position b and moves along the track 12, but when sliding on the tape, it moves along the track 14. At this time, the contact force F between the tape and the head and the protrusion amount d of the head are determined as follows: F=0.056δ _T ...(8) F=-0.118δ _H +5.88 ...(9) Substituting the above conditions into equations (8) and (9), the contact force F at this time is F=1.9 g-W, and the protrusion amount d of the head is d=34 μm. Therefore, in equations (8) and (9) above, δ _T is the amount of tape deflection, and δ _H
is the amount of head movement, 0.056 is the tape spring constant, -
0.118 is the spring constant of the head, and 5.88 is the initial condition that takes into account not only the centrifugal force but also the spring constant. And the above d=34μm, F=1.9g−W are the above (8) and
In equation (9), let δ _T and δ _H be x, for example, and find x to find d=34μm.Furthermore, by substituting this value into equation (8) above, the contact force at that time F=
1.9g-W can be obtained. This makes it possible for the invention to reduce the contact force compared to the conventional type, and furthermore, due to this fact and the responsiveness of the head, it is possible to make the contact between the head and tape more uniform, improve the S/N ratio, etc.
This makes it possible to extend the lifespan.

Furthermore, in the event that the head tip 5 should cross, by changing the angular velocity ω of the drum 1 as described above, the orbital movement of the head tip 5 will be shifted from the orbit 15 to 16, and the head tip 5 will come into contact with the cleaning member 13 and be cleaned. It turns out. In this case, the centrifugal force is 4g-W from equation (7) above.
Since the power is 7.3 g-W, there is an advantage that a larger force is applied to the head tip 5 during cleaning than during normal operation, and the cleaning effect can be increased in a short time. Also, when the tape slides, centrifugal force (e.g. 4g-
W) It is possible to reduce the contact force by allowing the head 4 to travel with a lower contact force (for example, 1.9-W).

The theoretical and experimental values thus obtained are shown in FIGS. 8 and 9. That is, FIG. 8 shows a head protrusion amount versus angular velocity curve in a rotating magnetic head, and FIG. 9 shows a centrifugal force versus angular velocity curve in a rotating magnetic head. In Fig. 8, the solid line is the theoretical curve obtained from the theoretical formula (formula (3) above), ●
Each mark represents an experimental value under certain conditions,
In addition, in Fig. 9, the solid line represents the theoretical curve obtained using the theoretical formula (formula (1) above), and the marks indicate experimental values under certain constant conditions. It can be seen that the experimental values are in virtually complete agreement with each other, and the principle is proven.

Next, regarding the specific configuration of the fluid guide 12 and the cleaning member 13 built therein, the second
This will be explained with reference to FIGS. In each figure, parts corresponding to those in FIG. 1 will be described with the same reference numerals.

In FIG. 2, 21 is a base, and 22 is a base 21.
Mounted thereon is a fixed drum 22, which is arranged concentrically with the rotating drum 1, on which the head 4 is mounted via the hole 11.
A fluid guide 12 is provided adjacent to these drums 22 and 1, and is fastened to the base 21 via a pin 23 with a mounting screw 24.

A cleaning member 13 is built into the fluid guide 12 so as to be movable within a predetermined range, and a cleaning shaft 25 is provided which is screwed to engage with one end of the cleaning member 13. Therefore, by rotating the cleaning shaft 25, the cleaning member 13 which is interlocked with the cleaning shaft 25 is connected to the fluid guide 1.
It can be moved arbitrarily along the inner circumferential surface of 2.

Further, when the tape 2 is wound along the circumferential surfaces of the drums 1 and 22 and the tape 2 is guided by the fluid guide 12 at the inlet and output parts, the head tip 5 slides on the tape 2. , will move along the trajectory 14 shown in FIG.

In addition, in FIG. 2, when the fluid guide 12 is attached to the base 21, the fluid guide 12 is slightly eccentric.
2 is an example in which an eccentric cam is used, and the eccentricity ε is, for example, about 100 μm. Thereby, the gap between the drums 1, 22 and the fluid guide 12 can be adjusted optimally, and the longitudinal vibration of the head 4 relative to the tape 2 can be effectively absorbed. Further, a notch 12a sufficient to expose a part of the cleaning member 13 built into the fluid guide 12 is provided near the head of the fluid guide 12.

FIG. 3 shows the state during head cleaning when the fluid guide 12 having the configuration as shown in FIG. 2 is used, that is, the case where the head tip 5 slides along the track 16 shown in FIG. By contacting the cleaning member 13, the head tip 5 is effectively cleaned by the cleaning member 13. In this case, if the same location of the cleaning member 13 is used many times, the cleaning member 13 may wear out and lose its cleaning effect.
By rotating the cleaning member 13 and moving the cleaning member 13 by a predetermined amount, other parts of the cleaning member 13 can be used, and a good cleaning effect can always be obtained.

FIG. 4 shows a case where a fluid guide 12A having a guide structure with good roundness is used in place of the fluid guide 12 in FIGS. 2 and 3. If good accuracy can be obtained in machining, A structure other than an eccentric structure may also be used.

Figure 5 shows the cleaning screw 2 in Figures 2 to 4.
In the case where a cleaning nut 26 having a nut structure is used instead of the cleaning nut 26
is fixed to one end of the cleaning member 13, and by rotating the cleaning nut 26, the cleaning member 13 can be arbitrarily moved along the inner peripheral surface of the fluid guide 12, as described above.

The positional relationship of the fluid guide 12 configured in this way is shown in FIGS. 6 and 7, respectively. That is, the sixth
The figure shows the tape winding angle position (θ) of the fluid guide 12.
placed at 0° and 180°, tape 2 connects fluid guide 1
When traveling between the drum 2 and the drum 1, FIG. 7 shows a case where the fluid guide 12 on the θ=180° side is arranged between the drum 3 and the tape 2 with respect to the positional relationship shown in FIG. By arranging the fluid guide 12 in this way, when the drum 1 rotates at an angular velocity ω, in the prior art, θ=
In this invention, the turbulent eddy vectors generated in the 0° front region and the θ=180° rear region are eliminated, and the curve of the tape flying height against the tape winding angle position (θ) at this time is shown by the solid line in Figure 10. It will be shown as follows. From FIG. 10, it can be seen that in the present invention, the flying height of the tape is approximately uniform over the tape winding angle position (θ) of 0° to 180°.

As described above, according to the present invention, the fluid guiding means is provided adjacent to the rotating drum to equalize the air film generated between the rotating drum and the tape, and also to stabilize the flow properties, which makes it possible to improve the flow characteristics of the air film, which is not possible with conventional devices. It is possible to improve the performance of the device without causing the adverse effects such as jitter, wow, and flutter that have been observed.

Furthermore, since the contact pressure of the head with the tape can be reduced, various characteristics of the device such as S/N can be improved, and the lifetime of the head can be extended.

Furthermore, since the cleaning member is integrated into the fluid guide means, it is possible to achieve miniaturization, and when the head causes a clock, etc., cleaning can be performed automatically by simply sliding the head tip against the cleaning member. It can be carried out.

In the above embodiment, the front centrifugal force balance spring 7 and the rear centrifugal force balance spring 8 are used as elastic members.
Although a case has been described in which a plurality of elastic members are used, a single elastic member may be used as necessary.

[Brief explanation of the drawing]

FIG. 1 is a plan view and side view showing an embodiment of the present invention, FIGS. 2 and 3 are sectional views showing an example of essential parts of the invention, and FIGS. 4 and 5 are respectively views of the present invention. Cross-sectional views showing other examples of main parts, FIGS. 6 and 7
The figure is a diagram for explaining the operation of this invention, and FIGS. 8 to 10 are characteristic diagrams for explaining the operation of this invention. 1 is a rotating drum, 4 is a rotating magnetic head, 5 is a head chip, 6 is a centrifugal force auxiliary board, 7 is a front centrifugal force balance spring, 8 is a rear centrifugal force balance spring,
9 is a head substrate, 12 is a fluid guide, and 13 is a cleaning member.

Claims (1)

[Claims] 1 At least one elastic member 7, 8 fixed to a head substrate 9 mounted on the rotating drum 1, and an auxiliary substrate 6 attached to the other end of the elastic member 7, 8.
and a head chip 5 fixed to the end of the auxiliary board 6, which is arranged adjacent to the rotary drum 1 with its central axis substantially parallel to the rotation axis of the rotary drum 1,
A cylindrical fluid guide means 12 having a built-in member 13 for cleaning the head tip 5 is provided at approximately the same height as the head tip 5, and the head tip 5 is fixed by the rotational centrifugal force of the rotating drum 1. The auxiliary substrate 6 is moved to the fluid guide means 12 against the elastic force of the elastic members 7 and 8.
1. A magnetic recording and reproducing device characterized in that the device is made to protrude toward.