JPH04192154A - Double sided magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To decrease the burden of a magnetic sheet and to stabilize rotation and head touch by forming the inclined flat surfaces of magnetic heads on both surfaces of the magnetic sheet to a specific shape and area and disposing these heads in the positions shifted along the rotating direction of the sheet. CONSTITUTION:Both upper and lower magnetic heads 1, 2 are disposed in the positions shifted to the extent of preventing the overlap thereof in the rotating direction R of the magnetic sheet 3. The positional relations of the flat surfaces 4, 5 and the free rotating surface N are maintained constant. The magnetic heads execute recording and reproducing in the state where the heads are brought into sliding contact with the sheet by the negative pressure generated by the rotation of the sheet. The abrasion loss by the amount of the negative pressure to be generated and the sliding quantity of the sheet varies with the shapes of the flat surfaces 4, 5. Then, the radial length of the sheet of the flat surfaces is specified to >=0.8mm and the circumferential length to >=0.5mm and the area is specified to <=12mm<2>, by which the optimum negative pressure is attained and the load of the sheet is decreased. The rotation and head touch are thus stabilized.

Description

Detailed Description of the Invention <Industrial Application> The present invention reduces the load on the magnetic sheet by forming an inclined flat surface for generating negative pressure on the surface of the magnetic head facing the magnetic sheet. The present invention relates to a double-sided magnetic recording and reproducing device that achieves reduced head touch, stable head touch, and prevention of damage to magnetic sheets.

<Prior Art> Conventionally, in a double-sided magnetic recording/reproducing device using a flexible magnetic sheet, such as a video floppy disk, as a recording medium, each magnetic head on both sides is pressed against the magnetic sheet by the force of a spring to perform recording or reproduction. I was going.

<Problems to be Solved by the Invention> If an attempt is made to obtain a head touch by pressing the magnetic head against a magnetic sheet in this way, the head touch becomes unstable. Moreover, the load on the magnetic sheet increases, preventing stable rotation. Furthermore, there is a problem that the recording surface of the magnetic sheet is easily scratched.

An object of the present invention is to provide a double-sided magnetic recording/reproducing device that solves the above-mentioned problems.

Means for Solving the Problems> The structure of the double-sided magnetic recording/reproducing device according to the present invention is such that one recording surface of a flexible magnetic sheet is disposed with an opposing surface having a magnetic gap portion facing the second recording surface. In a double-sided magnetic recording/reproducing device comprising a first magnetic head and a second magnetic head disposed with a facing surface facing the other recording surface, each of the facing surfaces of the first and second magnetic heads is magnetically It is an inclined flat surface that generates negative pressure between the magnetic sheet and the magnetic sheet as the sheet rotates to draw the magnetic sheet to the magnetic gap, and the length 1K of the flat surface in the radial direction of the magnetic sheet is 0. 8
The length 12 in the circumferential direction is 0.5 m or more, the area j,
The magnetic heads are characterized in that their respective flat surfaces are arranged at positions offset from each other along the rotational direction of the magnetic sheet.

When the magnetic sheet is rotated, the inclined flat surface formed on the surface of the magnetic head facing the magnetic sheet generates negative pressure between the magnetic sheet and the magnetic sheet, which causes the magnetic sheet to move toward the magnetic head. The magnetic head is attracted and comes into close sliding contact with the magnetic gap formed on the opposing surface of the magnetic head.

Here, the radial length 11 of the inclined flat surface is 0.8
If the length I2 in the circumferential direction is less than 0.5 degrees, sufficient negative pressure will not be generated and stable sliding contact will not be possible.

Also, the area of the inclined flat surface (#, xjQ) is 12+w
If the value is greater than F, the negative pressure increases and is strongly attracted, resulting in increased wear on the magnetic sheet.

Since the flat surfaces of the first and second magnetic heads are at different positions with respect to the rotational direction of the magnetic sheet, the magnetic sheets can be drawn in opposite directions without interfering with each other.

As a result, the magnetic sheet rotates without being significantly deformed from the free rotation surface, in other words, the attitude at which it enters the magnetic head on the upstream side in the direction of rotation and the attitude at which it exits from the magnetic head on the downstream side are almost the same. .

Embodiments Hereinafter, the present invention will be described in detail along with embodiments with reference to the drawings.

FIG. 1 shows a main part of an embodiment of a double-sided magnetic recording/reproducing apparatus according to the present invention. In the same figure, two magnetic heads 1 and 2
are thin film herad chips, which are placed above and below the flexible magnetic sheet 3 between them. Both the upper and lower magnetic heads 1 and 2 have flat surfaces 4° 5 inclined with respect to the free rotation surface N, and the dimensions of each flat surface 4 and 5 are 2×2, and magnetic gap portions 6 and 7 are formed therein. It is formed.

Both the upper and lower magnetic heads 1 and 2 are arranged so as to be offset along the rotation direction R of the magnetic sheet 3 so that their respective flat surfaces 4 and 5 do not overlap in the rotation direction R of the magnetic sheet 3. Remagnetization Herad 1
, 2 and the free rotation surface N are kept constant.

In this embodiment, the lower magnetic head 2 is located on the upstream side in the rotation direction R, and the lower magnetic head 2 freely moves the magnetic sheet 3 by the negative pressure generated between the flat surface 5 and the magnetic sheet 3. After pulling downward from the rotating surface N and making sliding contact, the upper magnetic head 1 on the downstream side uses its negative pressure to pull the magnetic sheet 3 upward and making sliding contact, and then the magnetic plate 3 returns to the free rotating surface N. . In this sliding contact state, recording or reproduction is simultaneously performed on both the upper and lower recording surfaces of the rotating magnetic sheet 3.

Next, negative pressure will be explained with reference to FIGS. 1 and 2.

As shown in FIG. 1, the flat surface 4 of each magnetic head 1, 2,
5 is inclined so as to gradually move away from the free rotation surface N toward the downstream side in the rotation direction R of the magnetic sheet 3.

As a result, as the magnetic sheet 3 is rotated, negative pressure is generated in the area between the magnetic sheet 3 and the inclined flat surfaces 4 and 5 of the magnetic heads 1 and 2, and the magnetic sheet 3 is drawn toward the magnetic head. Furthermore, the magnetic heads 1 and 2 come into sliding contact with the magnetic gap portions 6 and 7 provided at the tips of the magnetic heads 1 and 2, thereby realizing a good head touch.

Here, the inclination angle θ of the flat surfaces 4 and 5 with respect to the free rotation surface N is preferably about 1.0° to 4,000°. This is because sufficient negative pressure will not be generated if the pressure is lower or higher than that.

Also, the dimensions i, t, of the flat surfaces 4 and 5 shown in FIG.
is limited by the amount of negative pressure generated, the amount of wear of the magnetic sheet 3, etc.

That is, an experiment was conducted to determine whether sufficient negative pressure could be generated between the flat surfaces 4 and 5 and the magnetic sheet 3 to generate suction by variously changing the dimensions j, 12 of the flat surfaces 4 and 5, and the following results were obtained. .

However, the judgment result of 0 means that sufficient suction was possible,
Δ in document number 11.12 indicates that the suction was too strong and the motor stopped, Δ in document number 9 indicates that the running of the magnetic sheet 3 became unstable, and × indicates that suction was not possible.

As is clear from this result, the dimension 11 of the flat surface 4°5
It can be seen that sufficient suction cannot be achieved if the is less than 0.8 m or I2 is less than 0.5 m.

This is considered to be because if the flat surfaces 4 and 5 do not have a certain degree of dimensional expansion, negative pressure will not be generated, or even if it is generated, it will disappear immediately.

Also, if the dimensions 11 of the flat surfaces 4, 50 are 0.8 m or more and 12 is 0.5 m or more, sufficient suction is possible, but if the area (j, x/,) of the flat surfaces 4, 5 is 12j It can be seen that if the value is exceeded, excessive suction occurs. This is considered to be because the area of the flat surfaces 4 and 5 is too large, resulting in an increase in negative pressure. If the capacity of the motor is increased, the motor will not stop even if the area of the flat surface 4.5 is increased, but the wear of the magnetic sheet 3 will become significant, which is not preferable.

The above experimental results were conducted using a thin magnetic sheet called a methyl video floppy. Here, the main physical standards for still video floppies are that the diameter of the recording medium is 46.9 wa to 47.9 wa.
2 was, thickness 40±2μm1 maximum deflection ±0.
41, Young's modulus is 400 kg/w;'~600
kg/m11゜Thermal expansion coefficient is 9 x 10-'en
/am/'Q~25x10 cn/cm/'Q, humidity expansion coefficient is 15x10-'Gloss/Gloss/%RH or less.

In addition, according to the NTSC standard, the rotation speed is 360 Orp.
m, the radius of the outermost track is 20 m, and the radius of the innermost track is 15 m. Further, although we did not conduct an experiment using the PAL system standard, similar results are expected since this standard also has a rotational speed of 300 rpm, which is not much different from the above standard.

The dimension I of the flat surface 4.5 is the length in the direction approximately perpendicular to the rotation direction of the magnetic sheet 3, which is indicated by the arrow R in FIG. 1, and the dimension 12 is the length indicated by the arrow R in FIG. This is the length of the magnetic sheet 3 along the direction of rotation indicated by R.

Based on the principle of negative pressure generation described above, the amount of negative pressure generated is approximately different within the planes of the flat surfaces 4 and 5 of each magnetic head 1 and 2. Therefore, no matter where the magnetic gap parts 6, 7 are formed on the flat surfaces 4, 5, they can be in good sliding contact with the magnetic sheet 3. An embodiment focusing on this point is shown in FIG.

In FIG. 3, the magnetic gap portion 7 of the lower magnetic head 2 on the upstream side is formed at the rearmost portion of the flat surface 5, and the magnetic gap portion 6 of the upper magnetic head 1 on the downstream side is formed on the flat surface 5.
It is formed at the leading edge of the As a result, the upper and lower magnetic gap portions 6 and 7 become extremely close to each other in the rotation direction R. As a result, the timing of recording or reproducing can be made almost simultaneous between both the upper and lower magnetic heads 1.2. Also, both the upper and lower magnetic heads 1 and 2 can easily set the azimuth within the allowable #i range! It can be done. For example, according to the standards for still video cameras, the azimuth is within ±6'.
The distances 9, 9 from the ideal center 1/a8 to each magnetic gap portion 6, 7 may be set to within 0.2 m.

That is, the azimuth angle in a track with a radius of 20 is m-'
(0,2720) = 34.4', and the azimuth angle for a track with a radius of 15 cm is -'-' (0,2/15)
= 45.8', and the azimuth difference is 11.4'
Therefore, the 9 minute swing can be adjusted to ±5.7' by adjustment, and ±
It falls within 6'.

4 and 5 show an embodiment in which the upper and lower magnetic gap portions 6.7 are set at the same position with respect to the rotational direction R. FIG. As shown in FIG. 4, the flat surface 4 of the upper magnetic head 1 and the flat surface 5 of the lower magnetic head 2 have a symmetrical trapezoidal shape 9 and are arranged so that they just touch at the top and bottom. The upper and lower magnetic gap portions 6 and 7 are offset from each other in the off-track direction, and are formed at the rearmost and most distal ends of the flat surfaces 4 and 5, respectively. As a result, as shown in FIG. 5, the upper and lower magnetic gap parts 6 and 7 are at the same position in the rotation direction R. Note that each magnetic gap portion 6.7 is formed for two channels.

<Effects of the Invention> According to the present invention, each magnetic head facing both sides of the magnetic sheet draws the magnetic sheet into sliding contact with each other by the negative pressure generated by the magnetic head, so that the deformation of the magnetic sheet is small, and therefore the magnetic The load on the seat is reduced, the head touch is stable, and it is less likely to get scratched.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a main part of one embodiment of the present invention, FIG. 2 is a diagram showing a flat surface of a magnetic head, FIG. 3 is a diagram showing a main part of another embodiment, and FIGS. FIG. 5 relates to still another embodiment, and FIG. 4 is a diagram showing the shape of the flat surface and the position of the magnetic gap part.
FIG. 5 is a diagram showing the main parts of the same embodiment. In the drawing, 1 indicates the upper (first) magnetic head, and 2 indicates the lower (second) magnetic head.
) Magnetic head, 3 is a magnetic sheet, 4 and 5 are flat surfaces, 6 and 7 are magnetic gears, and protrusions.

Claims (1)

[Claims] A first magnetic head disposed with a facing surface having a magnetic gap portion facing one recording surface of a flexible magnetic sheet, and a facing surface facing the other recording surface. In a double-sided magnetic recording and reproducing device, each of the opposing surfaces of the first and second magnetic heads generates negative pressure between them and the magnetic rate as the magnetic sheet rotates. It is an inclined flat surface that pulls the magnetic sheet toward the magnetic gap portion, and the length l_ of the flat surface in the radial direction of the magnetic sheet.
1, is 0.8 mm or more, and its circumferential length l_2 is 0
．． 5mm or more, the area l_1×l_2 is 12mm^2
1. A double-sided magnetic recording and reproducing device, characterized in that the first and second magnetic heads are arranged at positions where their respective flat surfaces are shifted from each other along the rotational direction of the magnetic sheet.