JPH0132206Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic sheet recording and reproducing device that performs magnetic recording and reproducing by bringing a magnetic head into contact with a rotating magnetic sheet. The present invention relates to a magnetic sheet recording and reproducing apparatus that performs magnetic recording and reproducing using an in-line head.

In magnetic sheet recording and reproducing devices or magnetic sheet recorders, if you want to increase the recording density or record a large amount of information per unit time, it is important to have a narrower track, shorten the recording wavelength, and increase the number of heads. It is considered a means. For example, R (red), G (line), B for color image composition in a still screen information signal that corresponds to one frame or one field of a television video signal.
(Blue) Signals are assigned to each of three magnetic heads for recording and reproduction, or n bits, which are the constituent units of digital signals such as computer data signals, are assigned to each of n magnetic heads. The above-mentioned multi-head configuration is extremely useful in cases such as parallel recording and reproduction.

By the way, when performing magnetic recording and reproduction using such a plurality of magnetic heads, it is necessary to improve the positional accuracy between the individual heads, and if this positional accuracy is low, the phase shift of the information signal shared by each head will occur. Since this becomes a problem, a so-called in-line configuration in which a plurality of magnetic heads are arranged in a straight line in the radial direction of the seat, or a configuration similar to this, is required.

FIG. 1 shows the main parts of a magnetic sheet recorder that performs magnetic recording and reproduction on a rotating magnetic sheet 1 using the above-mentioned inline multiple head structure. In FIG. 1, a magnetic sheet 1 is rotationally driven by a rotary drive shaft 2, and a plurality of magnetic heads 3a, 3b, 3c, 3d, for example, four magnetic heads 3a, 3b, 3c, 3d are arranged in the direction of arrow A, which is the radial direction of the magnetic sheet 1. has been done. Each magnetic head 3 has an external shape as shown in FIG. 2, and a gap 4 is formed at the tip (upper part in the figure). Then, as shown in FIG. 3, the four magnetic heads 3a, 3
Gap 4a, 4 of b, 3c, 3d, respectively
b, 4c, and 4d are positioned so as to be arranged in a straight line in the radial direction (direction of arrow A), and are supported and fixed to the head base 5 shown in FIG. In this case, each magnetic head 3a, 3b, 3c,
The main surface 3d is arranged in a direction perpendicular to the radial direction (direction of arrow A), that is, parallel to the rotation tangent direction of the rotating magnetic sheet 1 (direction of arrow B in FIG. 3).

In such a conventional magnetic sheet recording/reproducing device having an in-line multi-head structure, there is a problem in that it is difficult to make contact between the rotating magnetic sheet 1 and the tips of the heads 3a, 3b, 3c, and 3d, that is, so-called head contact. As shown in Figure 1,
Even if the tips of the radially outer magnetic heads 3a, 3d contact the magnetic sheet 1, the tips of the inner magnetic heads 3b, 3c move away from the magnetic sheet 1 due to the rigidity of the sheets. For this purpose, a pad made of felt, for example, is placed at a position facing the magnetic heads 3a, 3b, 3c, and 3d via the magnetic sheet 1, and this felt pad makes it possible to connect all the heads 3.
It is possible to bring the magnetic sheet 1 into contact with a, 3b, 3c, and 3d, but friction during sliding contact between the felt pad and the sheet 1 may cause uneven rotation or damage the sheet 1. There is a drawback.

In view of these conventional circumstances, the present invention prevents damage to the sheet due to sliding contact between the pad and the rotating magnetic sheet, and also provides sufficient head contact. The purpose of the present invention is to provide a magnetic sheet recording/reproducing device which can obtain good head contact without damaging the sheet when applied to an object such as a head where it is difficult to make contact between all the heads and the sheet. do.

That is, the magnetic sheet recording and reproducing apparatus according to the present invention is characterized in that the magnetic sheet recording and reproducing apparatus has a magnetic head that comes into contact with a rotating magnetic sheet, and includes an air pad that is disposed opposite to the magnetic head with the magnetic sheet interposed therebetween. This air pad has at least two tip portions that sandwich the tip of the magnetic head along the direction of the rotation radius of the magnetic sheet, and these tip portions hold the tip of the magnetic head in the direction perpendicular to the surface of the magnetic sheet. In addition to being inserted beyond the radial direction, an arc is formed in the rotation tangential direction perpendicular to the radial direction, and an arc is also formed in the radial direction, and the radius of curvature of each arc is is set depending on the thickness of the air film formed between the end face of the tip of the air pad and the surface of the magnetic sheet.

Below, preferred embodiments of the present invention will be described.
This will be explained with reference to FIGS. 4 to 7.

First, FIG. 4 is a schematic cross-sectional view showing the main parts of a magnetic sheet recording/reproducing apparatus as an embodiment of the present invention. In FIG. 4, a rotating magnetic sheet 1 is rotationally driven by a rotational drive shaft 2. As shown in FIG. A plurality of magnetic heads 3a, 3b, 3c, 3d, for example, four magnetic heads 3a, 3b, 3c, 3d, are arranged in the direction of arrow A, which is the radial direction of this rotating magnetic sheet 1.
is installed. As mentioned above, these magnetic heads have the external shape shown in FIG. 2, and are arranged in the arrangement form shown in FIG.
The gears 4a, 4b, 4c, and 4d of gears 4a, 4b, 4c, and 4d are arranged in a straight line in the radial direction, and their main surfaces are parallel to each other in the rotation tangent direction (direction of arrow B). It is supported and fixed by 5.

Also, the magnetic head 3 is connected via the magnetic sheet 1.
An air pad 10 made of a material that hardly undergoes deformation, such as a metal material or hard plastic, is disposed at a position facing a, 3b, 3c, and 3d. This air pad 10 has magnetic heads 3a, 3 in the direction of arrow A which is the radial direction of the seat.
It has tip portions 11a, 11b, 11c, 11d, and 11e that sandwich the tips of the tips b, 3c, and 3d, respectively. That is, in the direction of arrow A, the tips 11a and 11b of the air pad 10 sandwich the magnetic head 3a, and the tips 11b and 11c sandwich the magnetic head 3b.
The tips 11c and 11d are arranged so as to sandwich the head 3c, and the tips 11d and 11e are arranged so as to sandwich the head 3d, respectively. And head base 5
and the air pad 10 are connected by an arm portion 13, and are configured to be movable in the radial direction of the magnetic sheet 1 (in the direction of arrow A) without changing their relative positions. Note that when attaching or detaching the magnetic sheet 1 from the recording/reproducing device, the arm portion 13
The air pad 10 is rotated in the direction of arrow C around the rotation axis 14 of the air pad 10.

Incidentally, the radial cross-sectional shape (in the direction of arrow A) of the tip end 11 of this air pad 10 is formed as shown in the enlarged cross-sectional view of the main part shown in FIG. That is, from the state where the magnetic sheet 1 is brought into contact with the tips of the two magnetic heads 3, 3, these heads 3, 3
The periphery of the distal end portion 11 is formed along a curved shape (so-called ideal tent shape) obtained when the midpoint P of the sheet between the sheets is pressed in the direction of arrow D, which is perpendicularly downward to the sheet surface. This curve has the x-axis in the sheet radial direction and the y-axis in the direction perpendicular to the surface of the sheet 1 in the pressing direction (arrow D
direction) is the positive direction, y=wl ⁴ /24EI (x ² /l ² −2x ³ /l ³ +x ⁴ /l ⁴ )... It is approximately approximated by the formula. In this formula,
1 is the distance between the heads 3, 3, w is the linear load obtained by dividing the above pressing force by the width a of the tip 11 of the air pad 10, and E and I are the Young's modulus and the moment of inertia of the sheet 1, respectively. FIG. 6 is a graph showing this equation, and the displacement y in the direction of the arrow D is largest at the midpoint position l/2 between the heads 3, 3, which is wl ⁴ /384EI. The tip end 11 of the air pad 10 may be formed into an external shape as shown by the imaginary line in FIG.

Next, the peripheral shape of the tip 11 of the air pad 10 in the rotation tangential direction (direction of arrow B) which is perpendicular to the radial direction on the surface of the magnetic sheet 1 is, for example, a circle with a radius R as shown in FIG. It is formed in an arc shape that forms part of the circumference. Then, the magnetic sheet 1 is rotated with a tangential velocity component v in the direction of arrow B, and at this time, an air film with a thickness Δh is formed between the end face of the air pad tip 11 and the surface of the magnetic sheet 1. Δh is Δh=αR・(6μv/T)2/3... In this formula, α is a constant and takes a value of approximately 0.65, R is the radius of curvature of the air pad tip 11 in the tangential direction of the rotation, and μ is the viscosity coefficient of air, 1.86×10 ^-6 Kg・s/m ² = 1.86×10 ^-9 g・s/mm ²
where v is the relative velocity between the pad tip and the sheet in the tangential direction of the rotation, and T is the tension of the magnetic sheet 1. Then, magnetic sheet 1 and air pad tip 1
The tip portion 1 of the air pad 10 is obtained by obtaining the air film thickness Δh that is larger than the depth of the surface unevenness depending on the mirror finishing accuracy or surface roughness of the surface of the air pad 10.
By setting the air pad 10 so that it does not come into direct contact with the magnetic sheet 1, the air pad 10 can be pressed through the air film without damaging the sheet 1, and the head contact required for magnetic recording and reproduction can be obtained. be able to. Due to recent advances in processing technology and improvements in sheet surface properties, it has become possible to obtain surface processing accuracy (surface roughness) on the order of submicrons. This is due to the fact that it has become possible to fully utilize the effects of the air film, and the advancement in numerical calculation technology using computers has made it possible to effectively simulate the ideal tent shape.

By the way, as an example of a specific numerical value, it is preferable that the film thickness Δh of the air film is, for example, 1 μm or more. Each value of the above formula is determined so as to satisfy this Δh, but when processing and forming the tip portion 11 of the air pad 10, it is necessary to find the radius of curvature R. That is, from the above formula, R=Δh/0.65×(6μV/T)2/3... is obtained. Here, as mentioned above, μ=1.86×
10 ^-9 g・s/mm ² , Δh≧1μm. Furthermore, the relative speed v in the rotational tangential direction is v=2πr, where r is the radial distance from the rotational drive shaft 2 to the air pad 10 in FIG. 4, and the rotational frequency (rotational frequency). , r=10mm, and =60Hz, then v=3.77×10 ³ mm/s. Further, the sheet tension T in this case is equal to the rotating centrifugal force of the sheet at this position, and is approximately 11 g. Substituting these specific values into the above formula, R≧
The radius of curvature R of the air pad tip 11 in the tangential direction of rotation may be 6.31 mm or more.

As is clear from the above explanation, in the case of a conventional magnetic sheet recording/reproducing device having multiple inline heads, the sheet is damaged due to contact and sliding with the sheet caused by pressing felt pads, etc. Although it had the disadvantage of being used less frequently and having a shorter lifespan,
According to the magnetic sheet recording and reproducing device according to the present invention,
Since the tip of the air pad is pressed against the magnetic sheet via the air film, it is possible to keep the end surface of the tip of the air pad and the surface of the magnetic sheet almost in a non-contact state while ensuring sufficient contact between the inline multiple heads and the sheet. This allows the sheet to be used for a long time without damaging the sheet.

Note that the present invention is not limited to the above embodiments; for example, the number of magnetic heads may be one,
Alternatively, it can be any number of two or more heads, and in the case of multiple heads, each gap may be arranged in a straight line in the radial direction, or in an in-line shape, or offset to some extent in the rotational direction. A nearly inline multi-head array structure may also be used. Further, the air film thickness Δh may be determined depending on the surface roughness (processing accuracy) of the tip of the air pad and the magnetic sheet. Furthermore, it goes without saying that the present invention can be applied to a device that performs either recording or reproduction on a magnetic sheet, such as a recording-only machine or a reproduction-only machine.

[Brief explanation of drawings]

Fig. 1 is a schematic side view showing the main parts of a conventional magnetic sheet recording/reproducing device, Fig. 2 is a perspective view showing only the magnetic head taken out, and Fig. 3 is a plan view showing the arrangement of a plurality of magnetic heads. be. Figures 4 to 7 are diagrams for explaining one embodiment of the present invention, with Figure 4 being a schematic side view showing the main parts, and Figure 5 being an enlarged view of the tip of the air pad in Figure 4. 6 is a graph showing the ideal tent shape of the magnetic sheet, and FIG. 7 is a sectional view taken along the line in FIG. 4 for explaining the shape of the tip of the air pad in the direction tangential to rotation. 1... Rotating magnetic sheet, 2... Rotating drive shaft,
3, 3a, 3b, 3c, 3d...magnetic head, 5
...Head base, 10...Air pad, 11,1
1a, 11b, 11c, 11d, 11e... tips of air pads.

Claims (1)

[Scope of utility model registration request] A magnetic sheet recording/reproducing device having a magnetic head in contact with a rotating magnetic sheet includes an air pad disposed opposite to the magnetic head with the magnetic sheet interposed therebetween, and the air pad extends along the rotation radius direction of the magnetic sheet. It has at least two tip parts that sandwich the tip of the head, and these tip parts are inserted beyond the tip position of the magnetic head in the direction perpendicular to the surface of the magnetic sheet, and in the radial direction. A circular arc is formed in the rotation tangential direction at right angles, and a circular arc is formed in the radial direction,
A magnetic sheet recording and reproducing device characterized in that the radius of curvature of each of the circular arcs is set according to the thickness of an air film formed between the end face of the tip of the air pad and the surface of the magnetic sheet.