JPH02195501A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To prevent the double writing actions by shifting a magnetic head to both the position of a reference track to be recorded on a magnetic disk and the position of the magnetic head where the maximum output level is secured for a head amplifier which is recorded in a memory circuit and performing an erasing operation. CONSTITUTION:The position of a magnetic head 3 where the maximum output level of a head amplifier 8 is secured is outputted from a comparator 11 and stored in a memory circuit 12. The head 3 is shifted to the position stored in the circuit 12, and the head 3 is connected to an erasing circuit 9 via a changeover switch 6. Thus an erasing operation is carried out at the position of the head 3 where the maximum output level of the amplifier 8 is secured. Then a control drive circuit 7 moves the head 3 to the reference track position of a magnetic track and carries out an erasing operation there. Thus the head 3 performs the earing operations at the reference track position and the actually recorded position of the magnetic track where the output level of the amplifier 8 is maximum. As a result, the recorded video signals are completely erased and therefore the video signals are never written double.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording/reproducing apparatus for recording or reproducing video signals using a disc-shaped magnetic disk such as a video floppy disk.

2. Description of the Related Art In recent years, various techniques have been proposed for improving the image quality of magnetic recording and reproducing apparatuses that record and reproduce video signals of still images using video floppy disks (hereinafter abbreviated as VF). Generally, VF magnetic recording and reproducing devices erase information from recorded tracks using a magnetic head for recording and reproducing.

An example of the above-mentioned conventional magnetic recording/reproducing device will be described below with reference to the drawings. FIG. 4 shows a configuration diagram of a conventional magnetic recording/reproducing device, and FIG. 5 shows an explanatory diagram. In FIGS. 4 and 5, 1 is a magnetic trunk, and in the case of VF, the width in the radial direction is 60 μm, and the distance from the adjacent magnetic trunk (guard band 1b) is 40 μm.
There are 52 tracks on the magnetic disk 2, and the radial position (this is referred to as the reference track 1a) for recording is determined by the standard (the radial position of the center of the nth track is 2
For example, 27 toranok is located at a radius of 17.4 MM).

3 is a magnetic head whose head width is the same as the magnetic track 1 (SO .mu.m), contacts the magnetic disk 2 which is rotating under control, and records and reproduces video signals on the magnetic track 1.

A moving mechanism 4 supports the magnetic head 3, converts the rotational motion of the stepping motor 5 into linear motion, and moves the magnetic head 3 in the radial direction with high precision.

7 is a control drive circuit that drives and controls the rotation of the stepping motor. 6 is a changeover switch, and magnetic head 3
It is connected to a head amplifier 8, an erasing circuit 9, and a recording circuit (not shown), and switches the input/output circuit to the magnetic head 3. The head amplifier 8 linearly amplifies the output of the magnetic head 3 and outputs it to a video signal processing circuit (not shown). Further, the erasing circuit 9 is connected to the magnetic head 3 during erasing, supplies an erasing current to the magnetic head 3, and erases the magnetic track 1.
Delete information.

The operation of the magnetic recording/reproducing apparatus configured as described above will be explained below. The magnetic head 3 comes into contact with the magnetic disk 2 at an arbitrary position on the magnetic track 1 by means of the stepping motor 5 visually controlled by the control drive circuit 7 and the moving mechanism 4 which converts its rotation into linear movement.

When recording a video signal, the selector switch 6 is switched to 9, the magnetic head 3 is connected to a recording circuit (not shown), a recording current is passed through the magnetic head 3, and the video signal is transferred to the rotating magnetic disk 2. recorded.

During playback, the selector switch 6 switches between the magnetic head 3 and the head.
An amplifier 8 is connected to the magnetic head 3, which detects a video signal from the rotating magnetic disk 2. The output of the magnetic head 3 is amplified by the head amplifier 8, sent to a video signal processing circuit (not shown), and reproduced.

In the case of erasing, the changeover switch 6 connects the υ erasing circuit 9 to the magnetic head 3, causing an erasing current to flow through the magnetic head 3, thereby erasing the video signal recorded on the magnetic track 1.

Problems to be Solved by the Invention However, in the above configuration, since the tolerance of the center diameter of the magnetic track allowed by the VF standard is ±14 μm, as shown in FIG.
There is a case where the magnetic head 3 is positioned on the magnetic track 1 which is recorded with a deviation of 4 μm in the opposite direction with a deviation of 14 μm. In this state, even in the case of erasing, the previously recorded information (A) for 2 B and cam that is not in contact with the magnetic head 3 will remain without being erased, and next, in the case of recording, if it is shifted by 14 μm in the original direction. When the magnetic head 3 records a new recording,
As a result, the data will be overwritten by 28 μm in the worst case.

When this overwritten video signal is reproduced, there is a problem in that the S/N ratio of the reproduced signal deteriorates and cross modulation occurs, resulting in a very poor quality of the reproduced image.

In view of the above-mentioned problems, the present invention provides a magnetic recording and reproducing device that eliminates overwriting while maintaining the track center diameter tolerance of the VF standard, eliminates S-deterioration and cross-modulation of reproduced video signals, and improves the image quality of reproduced images. It is something to do.

Means for Solving the Problems In order to solve the above problems, the magnetic recording and reproducing apparatus of the present invention includes a magnetic head for recording and reproducing video signals on a magnetic disk having a plurality of circumferential magnetic tracks, and a magnetic head for recording and reproducing video signals on a magnetic disk having a plurality of circumferential magnetic tracks. A moving mechanism that moves the magnetic head in the radial direction of the disk, a head amplifier that amplifies the output of the magnetic head, a level discrimination circuit that determines the output level of the head amplifier, and a moving mechanism that moves the magnetic head slightly. A comparison circuit that compares the output level at each position determined by the level determination circuit, a storage circuit that stores the head position where the output level determined by the comparison circuit is the maximum, and a magnetic head used to record on a magnetic disk. When erasing the video signal recorded on the magnetic disk, the erase circuit erases the video signal recorded on the magnetic disk. It has a configuration in which the magnetic head is moved to both positions where the output level of the amplifier is maximum and erased.

Effect of the Invention With the above-described configuration, the present invention allows the magnetic head to operate at both the position of the reference trunk to be recorded determined by the standard and the position of the actually recorded magnetic track where the output level of the head amplifier is maximum. Since erasing is performed, there is no unerased recorded video signal, no overwriting of video signals occurs, and no S/N drop or cross modulation of the reproduced video signal occurs.

Embodiment Below, a magnetic recording and reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of a magnetic recording/reproducing apparatus according to an embodiment of the present invention.

1o is a level discrimination circuit which inputs the output of the head amplifier 8 and converts it from analog to digital. 11 is a comparison circuit,
The digital output of the level discrimination circuit 1o is inputted, and in conjunction with the control drive circuit 7 that drives the stepping motor 5, the position of the magnetic head 3 and the magnitude of the output of the level discrimination circuit 10 at that time, that is, the head amplifier 8. Compare the output of
The position of the magnetic head 3 at which the maximum value occurs is output. A storage circuit 12 is connected to the control drive circuit 7 and stores the position of the magnetic head 3 where the output of the head amplifier 8 is maximum. Other components are the same as the conventional example.

The operation of the magnetic recording/reproducing apparatus configured as described above will be explained below with reference to FIG. 1, FIG. 2, and FIG. 3.

FIG. 1 shows a configuration diagram, and when erasing a video signal recorded on a certain magnetic track, the changeover switch 6 first connects the magnetic head 3 and the head amplifier 8. First, the magnetic head 3 is fixed at the reference track 1a position of the magnetic track 1 to be erased, and the magnitude of the output of the magnetic head 3 is sent to the comparator circuit 11 through the head amplifier 8 and the level discrimination circuit 10. is input. Next, the control drive circuit 7 moves the magnetic head 3 by 10μ via the moving mechanism 4.
The stepping motor 5 is moved so as to move the magnetic head 3 to the outer circumference by m minutes, and the magnitude of the output of the magnetic head 3 is measured in the same manner and input to the comparison circuit 11.

Similarly, the magnetic head is moved to the outer circumference by another 10 μm, and the magnitude of the output at that position is measured and inputted to the comparison circuit 11. Next, move the magnetic head 3 40 μm toward the inner circumference.
minute (that is, 2 minutes toward the inner circumference from the original reference track 1a position)
0 μm), and the magnitude of the output of the magnetic head 3 is also measured and input to the comparator circuit 11. Finally, the magnetic head is moved 10 μm toward the outer circumference, and the output of the magnetic head is similarly input to the comparator circuit. The position of the magnetic head 3 at which the output of the head amplifier at this position is maximum is output from the comparison circuit 11 and stored in the storage circuit 12. After that, after moving the magnetic head 3 to the position stored in the memory circuit 12, the changeover switch 6 connects the magnetic head 3 and the erasing circuit 9, and first the magnetic head 3 is moved to the position where the output of the head amplifier 8 is maximized. Erase (Figure 2, in the figure, the innermost side is erased)
. Next, the control drive circuit 7 moves the magnetic head 3 to the reference track 1a position of the magnetic track to perform erasing (Fig. 3).
.

As described above, according to this embodiment, the head amplifier output is maximized in conjunction with the level discrimination circuit that A/D converts the output of the head amplifier and the control drive circuit that moves the magnetic head via the moving mechanism. By providing a comparison circuit that outputs the magnetic head position and a storage circuit that stores the magnetic head position, the position where the magnetic head output is maximum is found before erasing, and that position and the magnetic track reference are set. Erasing can be performed at both track positions, eliminating unerased areas of recorded video signals, and eliminating reproduction signal S/N deterioration and cross-modulation caused by overwriting.

In the embodiment, data is first erased at the output position of the storage circuit 12 and then erased at the magnetic track reference track position, but this is because it is convenient when storing data immediately thereafter, and the reverse may also be used. do not have.

Furthermore, although the magnetic head is first sent to the outer circumferential side when detecting the magnitude of the head amplifier output, it may also be sent first to the inner circumferential side.

In addition, although the magnetic head movement steps are set to 10 μm each, they can be made smaller (in that case, since the guard band is 40 μm, the amount of movement of the magnetic head from the reference track position must be 20 μm or less). .

Effects of the Invention As described above, according to the present invention, it is possible to eliminate unerased portions of recorded video signals, and to reduce the reproduction signal S/' due to overwriting.
N It is possible to obtain excellent effects such as being able to eliminate deterioration and cross modulation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams thereof, FIG. 4 is a block diagram of a conventional magnetic recording/reproducing apparatus, and FIG. 5 is an explanation thereof. It is a diagram. 1...Magnetic track, 1a...Reference track, 1b...Guard band, 2...
...Magnetic disk, 3...Magnetic head, 4...
...Moving mechanism, 6...Stepping motor, 6...Selector switch, 7...Control drive circuit, 8...Head amplifier, 9・・・・・・
... Erasing circuit, 1o... Level discrimination circuit, 11.
... Comparison circuit, 12 ... Memory circuit. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] A magnetic head for recording and reproducing video signals on a rotating disc-shaped magnetic disk, a moving mechanism for moving the magnetic head in the radial direction of the magnetic disk, a head amplifier for amplifying the output of the magnetic head, and the head. - a level discrimination circuit that discriminates the magnitude of the output level of the amplifier; a comparison circuit that moves the magnetic head slightly by the moving mechanism and compares the output level at each position discriminated by the level discrimination circuit; a storage circuit for storing the position of the head at which the output level determined by the comparison circuit is maximum; and an erasing circuit for erasing the video signal recorded on the magnetic disk using the magnetic head; When erasing the video signal recorded on the magnetic disk, the position of the reference track at which the magnetic head should be recorded on the magnetic disk, and the position of the head at which the output level of the head amplifier stored in the storage circuit is maximized. A magnetic recording/reproducing device characterized in that it is configured to move and erase data in both directions.