GB2181672A - Production of magnetic recording discs - Google Patents

Abstract

Anisotropic magnetic recording discs are produced by smoothing a disc base 1, coated with magnetic recording solution, by means of radial magnetic head 7 to obtain orientation in the direction of the circumference, that is rotation direction, of the disc base. A toroidal coil 13 (Figure 8) comprising an upper divided unit 14 and a lower divided unit 15 can be used as the orientation device. The magnetic recording solution is applied onto the disc base from a nozzle located near the centre hole of the disc base (Figure 1). <IMAGE>

Description

SPECIFICATION Method for producing anisotropic magnetic recording media and device therefor Background of invention The present invention relates to a method for producing anisotropic magnetic recording media of no output variation even if rotation angle is changed, more particularly to an orienting method of anisotropic magnetic recording media and a device used in the method.

In known methods of this kind, a nonmagnetic sheet delivered from feed rolls is treated with a magnetic recording solution by means of a coating device and it is directly delivered, otherwise after being treated by smoothing method such as photogravure coating to make uniform the thickness of the layer of the coated solution, to a random orientation device to disorient easy magnetization axes of magnetic particles contained in said magnetic recording solution, then to a dryer, and finally to a take-up winder, otherwise it is directly delivered to a cutting machine to produce disk bodies by punching machine.In conventional smoothing system, a nonmagnetic base is coated its surface with magnetic materials comprising acicular magnetic powders and then treated by polyesterfilm, metal roll, metal knife orthe like which are disposed in close proximity above said base ata rightangleto its longitudinal direction. However, in conventional system said acicular magnetic powders are inclined to be oriented in a specific direction due to imperfectness of random orientation and a considerable skillfulness is required to remedy such phenomenon. Moreover, output value of nonoriented magnetic recording media is small in comparison with that of magnetic tapes which were oriented in a specific direction and it is difficultto record various information in high density condition and regenerate them.There has been also a problem that output varies in accordance with rotation angle of disk be cause of imperfectness of random orientation.

Summary of the invention The present invention is intended to obviate the drawbacks inherent to the conventional system as described above. To this end it is required that the easy magnetization axes of magnetic particles contained in the magnetic recording solution are oriented in the direction of circumference, that is rotation direction, so that said magnetic recording solution may be coated in high density condition and increase amount of information to be recorded as well as a high south and north Sand N ratio. The anisotropic magnetic recording media produced by this method do not vary their output values even if rotation angle is changed.

The present invention is characterized in that the magnetic recording solution containing the magnetic particles is dropped from a hole located above the center of a disk body, said disk body being rotated at a desired rotation speed, and said magnetic recording solution is coated thoroughly and evenly and then smoothed by means of a magnetic head whose longitudinal axis is disposed in the radius direction of said disk body. By this method the easy magnetization axes of the magnetic particles are ori- ented in the direction of circumference and the anisotropic magnetic recording media of high quality are produced.

Further in order to exactly perform the above mentioned object, a toroidal coil which can house the disk type magnetic recording media is added. In thistoroidal coil there is provided a shaft projected uprightly from the bottom and an electric power source is disposed between said shaft and tops of the two opposite wall sides where said shaft is projected out of said toroidal coil to connect said shaft and wall sides to make an electric circuit. This orientation device of the magnetic recording media coated with the magnetic recording solution is additionally used.

Brief description of the drawings Figure 7 is a perspective view showing how to coat magnetic recording solution on a disk body.

Figure2 is a perspective view showing how to smooth and orient magnetic recording solution on a disk body.

Figure 3 is a vertical cross-sectional view of Figure 2.

Figure 4is a side view of a magnetic head.

Figure5is a vertical cross-sectional view showing smoothing treatment.

Figure 6 is a vertical cross-sectional view of other embodiment of smoothing and orientation treatments of the present invention.

Figure 7is an explaining view showing how the orientation treatment of Figure 6 is performed.

Figure 8 is a vertical cross-sectional view showing orientation treatment according to an orientation device of the present invention.

Detailed description of the preferred embodiments Now a method for producing anisotropic magnetic recording media is explained hereinafter in accordancewith drawings.

In Figure 1 a disk base 1 is placed on a rotation bed 3 comprising rubber, plastic, aluminum orthin stainless steel plate in a coating device 2. The magnetic recording solution is dropped from a nozzle 4toward circumference of the central hole of a disk body. The disk body 1 is rotated by means of the rotation bed 3 driven by a driving motor(notshown in drawings).

The magnetic recording solution (hereinafter called as MRS) is spread thoroughly and evenly over said disk base 1 by centrifugal force due to the rotation of said disk base itself. Sometimes it is recommended to move the nozzle 4toward peripheral direction of said disk base 1 to facilitate an effect of such coating.

As shown in Figure 2the MRS coated onthesurface of said disk base 1 is treated by a smoothing de vice 5 to uniform the thickness of the coated MRS and at the same time the easy magnetization axes of the magnetic particles contained in said MRS are oriented toward circumferential direction, that is rotation direction, of said disk base 1. In this consequence ani sotropicorientation is performed. In the smoothing and orientation treatments, as shown in Figure 2 and Figure 3, the disk base 1 coated with the MRS on its surface is placed on a rotation bed 6, said rotation bed 6 being rotated by means of a driving motor, and a magnetic head 7 disposed in the close proximity beneath the magnetic bed 6 affects the MRS with its magnetic field.In this case the magnetic head 7 goes downward when the MRS is coated, and it adversely goes upward to the closest proximity position to the back surface of said rotation bed 6 when the smooth- ing and orientation treatments are carried out. As shown in Figure 4the magnetic head 7 is disposed on a base plate 8 whose head pieces 9 and 10 of hook typeface each other with a proper gap d between their head points and a magnet 11 is placed between said head pieces 9 and 10. As magnetic head it is also possible to apply an electromagnet in place of head pieces 9,10 and magnet 11. In Figure 4 ferromagnetic substances wound with coil (shown in imagination line) are shown as electromagnet.The magnetic head or electromagnet 7 is disposed in such a mannerthatthe magnetic field of said magnetic head affects from central hole toward the radius direction of said disk base 1. The number ofthe magnetic head 7 to be disposed is selected according to the degree of orientation. The plural number ofthe magnetic head 7 can uniform the thickness ofthe coated solution in a short duration. As shown in Figure the MRS being affected by the magnetic head 7 pass over said magnetic head 7 as the disk base 1 rotates and an uniformed thickness is gradually obtained. After the smoothing and the orientation treatments have been completed said disk base 1 is delivered to a dryer and dried up as final products.In like manner the disk base 1 is coated with the MRS atthe opposite surface in the coating device 2 and it is again treated by the aforesaid smoothing and orientation treatments.

In Figure 2 and Figure 3 the reference numeral 6a and 3a designate a rotation shaft respectively.

Figure 6 shows other embodiment of the invention in which magnetic heads 12a and 12b are mounted to a support 13,the magnetic head 12a being mounted to face the back side of the rotation bed 6, while the magnetic head 1 2b being mounted to face the upper surface of said rotation bed 6. As the rotation bed 6 rotates the disk base 1 is rotated together and the MRS on said disk base 1 is affected by the magnetic field of the magnetic heads 12a and 1 2b and the smoothing and the orientation treatments are performed.

In Figure 7 the magnetic heads 12a and 1 2b are disposed to face each other holding the disk base 1 coated with the MRS therebetween, thus when the disk base 1 is rotated in the direction shown by an arrow Q by means of the rotation bed the easy magnetization axes ofthe magnetic particles contained in the MRS are affected by the magnetic field U of the magnetic heads 12a and 12b atthe pointXand the disk base 1 is oriented in the direction of circumference.

The coating method of the MRS is not limited to the aforesaid manner buta printing or the like methods are applied too.

As above mentioned, a method for producing the anisotropic magnetic recording media of the present invention is disclosed in such a mannerthatthe disk base coated with the magnetic recording solution is delivered to the smoothing treatment by the magnetic heads and atthe same time said disk base is oriented in the direction of circumference. Therefore, the an isotropic magnetic recording media produced by the present invention, unlike the conventional isotropic floppy disks, do not vary its output even if rotation angle is changed in the use and it is expected withoutfail to take out higher output as well as higher density recording. It is possible to increase the recording amounts ten times as much as that of a disk of the same area. It also presents a considerable higher effect in south and north Sand N ratio.

Another embodiment of the present invention is shown with an orientation device 13 in Figure 8. The orientation device 13 is composed of the two parts, that is an upper divided unit 14 and a lower divided unit 15. The upper divided unit 14is made in an up sidedown form of a dish with a proper wall 16 and a hole 17 on its top. On the other hand the lower divided unit 15 is made in the form of a dish with another properwall 18 and there is provided a vertical shaft 19 projected uprightlyfrom the bottom.The upper divided unit 14 and the lower divided unit 15 are manufactured by the electric conductive materials such as copper or the like. Both the upper and the lower divided units are made bending a piece of sheet into a dish form respectively, otherwise they are made by casting. It is also possible to manufacturethemwith wiring materials. In this case the upper divided part 14 is made in such a mannerthatmanywiringmat- erials constructing the unit are hardened bythe insulating compound in the downward direction from the top of the wall 16.The upper parts of each wiring materials are electrically connected by means of el ectricconductive rings and the lower parts of each wiring materials are remained free of connection so thatthey are easily connected with the wiring mat erialsofthe lower divided part 15 when both the upper and the lower divided parts are assembled into one unit On the other hand the lower divided part 15 is made in such a manner that many wiring materials are disposed and hardened by insulating compound in the downward direction from the top of the shaft 19 and turning up from the bottom of said divided unittothe upper part of the wall 18. The wiring materials at the top oftheshaft 19 are connected by means of electric conductive rings.All the wiring materials atthetop part of the wall 18 are remained free of connection so that they are easily connected with that of the upper divided unit 14 when both the upper divided unit 14 and the lower divided unit 15 are assembled into one unit. There is provided an electric power source 20 between the top of the wall 16 of the upper divided unit 14 and the top ofthe shaft 19 of the lower divided unit 15. The electric power source 20 is selected from among the direct current, alternating current electric power or pulse generator.

When turning on an electric current as an arrow A a magnetic field occurs in the orientation device according to the Ampere's right-handed screw rule.

This magnetic field affects the magnetic recording solution coated on the disk base 1 and the easy magnetization axes of the magnetic particles are oriented in the direction of circumference.

Besides the aforesaid orientation device 13 various kinds of toroidal coil type orientation devices are applied if such devices are possible to receive a nondried disk base coated with magnetic recording solution and take out easily after orientation treatment has been completed.

Moreover after coating ofthesurfaceofthe disk base has been completed, the other side of said disk base is treated and oriented in the same manner. It is also possible to orient both sides ofthe disk base at a time.

As aforesaid there is provided an electric power source between a shaft projected in the upright direction from the bottom and the upper part of the wall where said shaft is projected passing through the hole 17 of said upper part of the wall, and the easy magnetization axes of the magnetic particles contained in the magnetic recording solution coated on the surface of the disk base is oriented in the direction of circumference of the disk base. It was therefore observed that regenerated information output is increased twice to fourtimes as much as that of conventional disk base and also information density is increased fourto eight times as much as that of conventional one. It is also possible to increase south and north Sand N ratio.

The present invention has been described above with respect to the illustrated embodiment but it should of course be understood that it should not be limitedonlytothisandvariouschangesormodi- fications may be made in any acceptable manner without departure from the scope ofthe invention as defined by the appended claims.

Claims (4)

1. A method for producing magnetic recording media characterised in that a disk base made from a nonmagnetic sheet is rotated and magnetic recording solution containing magnetic particles is coated thoroughly and evenly on the surface of the disk base by dropping the magnetic recording solution from a nozzle located near the circumference of the centre hole of said disk base, further as said disk base is rotated, a magnetic head having its longitudinal axis in the radial direction of said disk base and disposed beneath said base smooths the thickness of the layer of the coated magnetic recording solution orientates the easy magnetization axes of said magnetic particles contained in said magnetic recording solution in the circumferential direction of said disk base.

2. A device to orientate the easy magnetization axes of the magnetic particles contained in the magnetic recording solution coated on the surface of a disk base characterised in that there is provided atoroidal coil being disposed with a shaft projecting uprightlyfrom a bottom plate and a wall made by assembling upper and lower divided units, the top of said shaft and the top of the wall being connected with an electric power source.

3. A method for producing a magnetic recording media and which is substantially as described herein.

4. A device of apparatus for the orientation of magnetic particles contained in a coating of magnetic recording solution and which is substantially as described herein.