JPH051552B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a magnetic recording and reproducing device, and more specifically, a tracking magnet that has a soft magnetic plate in the center of a magnetic sheet, and this soft magnetic plate is provided on a spindle. The present invention relates to a magnetic recording and reproducing device that rotates and drives a magnetic sheet by attracting it with a net and fixing it to a spindle.

[Prior Art] Conventionally, devices having this type of mechanism include a floppy disk drive using a disc-shaped magnetic recording medium and a video sheet recorder (hereinafter referred to as VSR).

It is also known that floppy disks rotate by directly chucking a magnetic sheet, but
In VSR, the magnetic sheet is rotated at high speed due to the video frequency, so the above mechanism is adopted in consideration of the accuracy of sheet damage, rotational drive, spacing loss, etc.

Here, FIGS. 1 and 2A and 2B show the structure of a conventional magnetic recording/reproducing apparatus.

FIG. 1 is a sectional view of the main parts of a conventional VSR, and what is indicated by the reference numeral 1 in the figure is a magnetic sheet as a magnetic recording/reproducing medium. The magnetic sheet 1 is housed in a jacket 2 and fed into a position on a spindle 11 from the top or from the left and right in the figure.

The magnetic sheet 1 is rotationally driven by a spindle 11, and a magnetic head 3 performs magnetic recording and reproduction on magnetic tracks on its surface.

The magnetic sheet 1 has a center core 4 made of members indicated by numerals 5 to 9 at its center.
That is, the magnetic sheet 1 is held and fixed at its center by a spindle engaging part 5 and a magnetic sheet pressing part 7 made of synthetic resin or the like, and a thin ring-shaped soft magnetic plate 8. A positioning rib 9 is provided on the lower surface of the soft magnetic plate 8 in order to align the center of the magnetic sheet 1 with the rotational drive shaft. Further, a PG yoke (index pin) 6 made of a magnetic material for detecting the number of rotations is embedded in a part of the spindle engaging part 5 and the magnetic sheet pressing part 7.

On the other hand, the spindle 11 has a table-shaped part around the central axis 11a6, and a flange 12 is formed on this table-shaped part, so that the spindle 11 has a cup-shaped structure as a whole. A ring-shaped chucking magnet 10 as shown in FIG. 2A is fixed to the bottom of the cup-shaped structure. As can be seen from FIG. 1, the tracking magnet 10 has a thickness lower than that of the flange 12, and its magnetization direction is in the second direction.
As shown in Figures A and B, it coincides with the thickness direction.

Therefore, when the magnetic sheet 1 and the jacket 2 are fed to the position of the spindle 11, the jacket 2 is positioned by a stopper (not shown) or the like.
The center core 4 is chucked and fixed to the flange 12 by the attractive force between the chuck magnet 10 and the soft magnetic plate 8.

Thereafter, the magnetic sheet 1 is driven to rotate by the spindle 11. At this time, the rotation speed is detected by picking up the passage of the PG yoke 6 with a magnetic sensor (not shown), and the rotation of the spindle 11 is controlled according to the detection output. Frequency oscillator (FG)
is controlled. In the case of the NTSC VSR, the rotation speed of the magnetic sheet 1 is maintained at 3600 rpm.

By the way, when the magnetic sheet 1 is fixed to the spindle 11 in the above method, the ring-shaped chucking magnet 1 is formed as shown by the broken line in FIG. 2C.
Magnetic flux appears from 0 through the soft magnetic plate 8. Almost no magnetic flux flows through the spindle engaging portion 5 and the magnetic sheet holding portion 7 (the PG yoke 6 is omitted here) made of resin or the like, but the magnetic flux coming out from the N pole of the chucking magnet 10 The magnetic flux passes through the soft magnetic plate 8 of the center core 4 and also passes through the recording area of the magnetic sheet 1.

This leakage magnetic flux of the tracking magnet 10 affects the magnetic head 3 or the magnetic track,
In the case of VSR, there may be adverse effects such as moiré on the image. Although the configuration of VSR has been illustrated above, this problem is common to all magnetic recording and reproducing devices that use a similar magnetic sheet fixing method.

[Objective] The present invention has been made in view of the above-mentioned drawbacks of the conventional magnets.The present invention has been made in view of the above-mentioned drawbacks of the conventional magnets. The purpose is to provide a recording/playback device.

[Structure of the Invention] In order to achieve the above object, the present invention has a soft magnetic plate in the center of the magnetic sheet, and this soft magnetic plate is attracted and fixed to the spindle by a chucking magnet provided on the spindle. In a magnetic recording and reproducing device that rotationally drives a magnetic sheet, a configuration is adopted in which a bent portion is formed on the outer peripheral edge of the soft magnetic plate toward the chuck magnet side.

[Example] Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

[First example] A first embodiment of the present invention is shown in FIGS. 3A to 3C.

FIG. 3A is a plan view showing a soft magnetic plate structure provided at the center of the magnetic sheet. As shown in the figure, in this embodiment, a ring-shaped soft magnetic plate 20
U-shaped notches 23 facing toward the center are formed at eight locations on the outer periphery.

FIG. 3B is a cross-sectional view taken along the line A-A in FIG. 3A, and as shown in FIG. There is. In addition, the part provided in the middle of the notch part 23 indicated by the reference numeral 22 in FIGS. 3A and 3B is a half-cut part used when forming the positioning rib by an outsert of a mold.

After forming the conventional positioning ribs 9 on the soft magnetic plate 20 as described above, if it is attached to the magnetic sheet 1 in the same manner as shown in FIG. 1 and used, the cross section of the device when the magnetic sheet 1 is fixed is as shown in FIG. become that way.

FIG. 3C is a sectional view similar to FIG. 2C, and shows a case where the soft magnetic plate 20 formed as described above is used in the apparatus of FIG. 1.

As shown in FIG. 3C, since the soft magnetic plate 20 is formed with a bent portion 21, the magnetic flux emitted from the N pole of the tracking magnet 10 passes through the bent portion 21 and exits downward. Since it enters the pole, magnetic head 3
Leakage of magnetic flux to nearby areas can be reduced.
Therefore, recording and reproducing errors caused by leakage magnetic flux of the tracking magnet 10 to the recording track and the magnetic head 3 are prevented, and highly reliable recording and reproducing can be performed. In the case of VSR, it is possible to prevent image deterioration such as moiré and perform high-quality image recording and playback.

[Second Embodiment] FIGS. 4A and 4B show a second embodiment of the present invention.

FIG. 4A is a plan view showing a part of the structure of the soft magnetic plate. As seen in the figure, in this embodiment, the notch 34 is extended to the outer periphery, that is, the notch 34 is shaped like a U. Rather than having a shape, it is shaped like a linear notch cut out from the periphery of the soft magnetic plate 30. Then, as shown in FIG. 4B, the inner part of the notch is bent downward at a right angle to form a bent part 31.

According to the above configuration, as shown in FIG. 4B, the length of the bent portion 31 can be made longer than in the case of FIGS. There is an advantage that it can be reduced.

In addition, in FIGS. 4A and 4B, the reference numeral 32 indicates a half-opening part similar to that shown in FIG. It is a through hole.

[Third Embodiment] FIGS. 4C and 4D show a third embodiment of the present invention.

FIG. 4C is a diagram similar to FIG. 4A, in which the soft magnetic plate 4
FIG. As shown by reference numeral 44 in the same figure, in this embodiment, the notches are not parallel as in the embodiment of FIG. 4A, and the soft magnetic plate 40
It is cut into a fan shape that is open along the radial direction or beyond. This portion is then bent downward at a right angle as shown in FIG. 4D to form a bent portion 41.

In addition, in FIGS. 4C and 4D, the reference numeral 32 indicates a half-opening part similar to that in FIG. It is a through hole.

By combining the above configuration with a configuration in which the tracking magnet 10 is magnetized in the radial direction, that is, in the diameter direction of the magnet, as shown in FIG. 4D, a large leakage flux blocking effect can be obtained. can. Chatting magnet 1
If the magnetization direction of zero is set to the radial direction, the magnetic flux emitted from the N pole of the tracking magnet 10 will immediately enter the end of the soft magnetic plate, which will reduce leakage toward the magnetic head, and will prevent the magnetic flux from bending as described above. By providing 41, a greater blocking effect can be obtained. In this case, it is preferable that the area for blocking the leakage magnetic flux of the tracking magnet 10 is large, so the bent portion 41 is preferably formed into a fan shape as described above.

The configuration of the present invention described above is not limited to the VSR device, and can be implemented in any of the devices described at the beginning.

[Effect] As is clear from the above description, according to the present invention, a soft magnetic plate is provided at the center of the magnetic sheet, and this soft magnetic plate is attracted to the spindle by a chucking magnet provided on the spindle. In a magnetic recording/reproducing device that rotates a fixed magnetic sheet, a simple and inexpensive structure in which a bent portion is formed on the outer periphery of the soft magnetic plate toward the chucking magnet side allows the chucking magnet to be rotated. It is possible to provide an excellent magnetic recording and reproducing device that can reduce leakage magnetic flux of the net and perform highly reliable recording and reproducing.

[Brief explanation of the drawing]

Figure 1 shows an example of a conventional magnetic recording/reproducing device.
Figure 2A is a cross-sectional view showing part of the structure of the VSR, and Figure 2A is a perspective view of the tracking magnet in Figure 1.
Figure B is a partial cross-sectional view of the tracking magnet, Figure 2C is an explanatory diagram showing the flow of magnetic flux in the device of Figure 1, and Figure 3A is a soft magnet according to the first embodiment of the present invention. A plan view showing the structure of the plate, Figure 3B is the third
Sectional view of the soft magnetic plate in Figure A along line A-A, No. 3
Figure C is an explanatory diagram showing the flow of magnetic flux when the soft magnetic plate of Figure 3 A is used in a VSR device, and Figure 4 A is a part of the structure of the soft magnetic plate according to the second embodiment of the present invention. Figure 4B is a plan view showing the device in Figure 4A.
An explanatory diagram showing the flow of magnetic flux when used in a VSR device, FIG. 4C is a plan view showing a part of the structure of the soft magnetic plate according to the third embodiment of the present invention, and FIG. FIG. 4 is an explanatory diagram showing the flow of magnetic flux when the device of FIG. 4C is used in a VSR device. 1...Magnetic sheet, 3...Magnetic head, 10...
...Chicking magnet, 11... Spindle, 20, 30, 40... Soft magnetic plate, 21, 3
1, 41...bent part, 22, 32...half punched part,
23, 34, 44...notch portion.

Claims (1)

[Claims] 1. In a magnetic recording and reproducing device that has a soft magnetic plate in the center of a magnetic sheet, this soft magnetic plate is attracted by a chuck magnet provided on a spindle, and is fixed to the spindle to rotate the magnetic sheet. 1. A magnetic recording/reproducing device characterized in that a bent portion is provided on the outer peripheral edge of the plate and is formed toward the tracking magnet side.