JPH02254603A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the unerased remainder of an already-recorded video signal, the overlapping write of the video signal, a reduction in S/N of a reproduced video signal and a mixed modulation by erasing a magnetic head in positions at two places stored with an arithmetic means at the time of erasing the video signal recorded to a magnetic disk. CONSTITUTION:A position moved by the degree of 10mum is operated and stored at the external sides of both positions of a position stored with a storage means 12 and a reference track 1a position to be originally stored within 20mum in an inner circumference in making the reference track 1a position to be originally recorded into a center. In such a case, according to the output of an arithmetic means 13, a magnetic head 3 is moved to the position at a side far from the reference track 1a position, thereafter, a changeover switch 6 connects the magnetic head 3 and an erasing circuit 9, and the erasing is executed in the position at the external side by 10mum of a position C of the magnetic head 3 in which the output of a head amplifier 8 is maximized. Next, a control driving circuit 7 moves the magnetic head 3 to the position of the outer circumferential side 10mum of the reference track 1a, and the erasing is executed. Thus, the overlapping write is eliminated, the S/N deterioration and mixed modulation of the reproduced video signal are eliminated, and the picture quality of a reproduced image can be made good.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus for recording and reproducing video signals using 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 apparatus, and FIGS. 5 and 6 show schematically enlarged views of a magnetic disk. 4, 6, and 6, 1 is a magnetic track, and in the case of the well-known υVF, the radial width is Wl-604m, and the distance to the adjacent magnetic track (guard band 1b) is W2
-40μm, 62 are provided 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 2o -(n-1)xo, 1n, e.g. 2
7 track is located at radius 17, 4fi). A magnetic head 3 has a head width of 60 μm, the same as the magnetic track 1, and is in contact with the magnetic disk 2 which is being controlled, and records and reproduces video signals on the magnetic track 1. 4 is a moving mechanism that supports the magnetic head 3 and performs stepping and
The rotational motion of the motor 6 is changed into linear motion, and the magnetic head 3
to move it in the radial direction with precision. 7 is a control drive circuit;
The rotation of the stepping motor 6 is controlled.

6 is a changeover switch, which allows magnetic head 3 and head amplifier 8 to be selected.
．． Erasing circuit 9. It is connected to a recording circuit (not shown) and switches the circuit that inputs and outputs to the magnetic head 3. head·
The amplifier 8 linearly increases the output of the magnetic head 3, produces a sound, and outputs it to a video signal processing circuit (not shown). Further, the erasing circuit 9 is connected to the magnetic head 3 by the changeover switch 6 during erasing, and supplies an erasing direct current to the magnetic head 3 to erase information on the magnetic track 1. Reference numeral 1o denotes level determining means, which inputs the output of the head amplifier 8 and converts it from analog to digital. Reference numeral 11 denotes a comparison means which inputs the digital output of the level discrimination means 1o and works in conjunction with the control drive circuit 7 that drives the stepping motor 6 to determine the position of the magnetic spatula 3 and the magnitude of the output of the level discrimination means 1o at that time. , that is,
The outputs of the head amplifiers 8 are compared, and the position of the magnetic head 3 at which the outputs are maximized is output. A storage means 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.

Level determination means 10. Comparison means 11. The storage means 12 is
It is included in the system control circuit 14.

The operation of the magnetic recording/reproducing apparatus configured as described above will be explained below. By means of a stepping motor 6 whose rotation is controlled by a control drive circuit 7 and a movement mechanism 4 which converts its rotation into linear movement, the magnetic head 3 comes into contact with the magnetic disk 2 at an arbitrary position of the magnetic track 1.

When recording a video signal, the magnetic head 3 is moved to the position of the reference track 1a originally stored in the storage means 12, the changeover switch e is switched, and the magnetic head 3 and a recording circuit (not shown) are connected. A recording current is applied to the magnetic head 3, and a video signal is recorded on a reference track position of the rotating magnetic disk 2. During playback, the selector switch 6 connects the magnetic head 3 and head amplifier 8, and the output of the magnetic head 3 that detects the video signal from the rotating magnetic disk 2 is amplified by the head amplifier 8 and sent to the video signal processing circuit (Fig. (not shown) and played. At this time, the magnetic head 3 is moved in 10 μm steps around the reference track position by the control drive circuit 7° movement mechanism 6, and the output of the head amplifier 1o is output by the level determining means 10. The comparing means 11 compares the magnitude of the output, and the magnetic head 3 is moved to a position where the highest output can be obtained. Finally, in the case of erasing, after the magnetic head 3 is moved to the reference track position, the erasing circuit 9 is connected to the magnetic head 3 by the changeover switch e, and an erasing current is passed through the magnetic head 3 to record on the magnetic track 1. The video signal that was displayed will be erased.

Problems to be Solved by the Invention However, in the conventional configuration as described above, the tolerance of the magnetic track center diameter allowed by the VF standard is ±14μ.
m, so as shown in FIG.
There is a case where the magnetic head 3 is positioned on the magnetic track 1 recorded with a deviation of 14 μm from W3 in the opposite direction. In this state, even in the case of erasing, the 28 μm worth of previously recorded information ■ that is not in contact with the magnetic head 3 remains unerased, and next, in the case of recording, if the magnetic head 3 is shifted by 14 μm in the original direction, When you record a new
As a result, the data will be overwritten by 28 μm in the worst case.

In addition, as shown in FIG.
Even if the magnetic head 3 is positioned with a 14 μm shift in the same direction on the magnetic track 1 recorded with a μm shift,
Normally, the rotation center of the magnetic disk 2 is different from when recording,
As the magnetic track rotates, the recorded information (
5) remains without being erased and is overwritten during recording. Generally, the above two conditions overlap, resulting in larger overwriting. 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 image quality of the reproduced image.

In view of the above problems, the present invention eliminates overwriting while maintaining the track center diameter tolerance of the VF standard, and improves the S/
The present invention provides a magnetic recording and reproducing device that improves the quality of reproduced images by eliminating N deterioration and cross modulation.

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 determining means that determines the magnitude of the output level of the head amplifier, and a moving mechanism that moves the magnetic head slightly. a comparison means for comparing output levels at individual positions determined by the level determination means; a storage means for storing the position of the head at which the output level determined by the comparison means is maximum; calculation means for calculating and storing two positions that are slightly moved outside each position from the maximum head position and the reference track position to be recorded on the magnetic disk;
Equipped with an erasing circuit that erases video signals recorded on a magnetic disk using a magnetic head, and a changeover switch that switches and connects the magnetic head to a head amplifier and an erasing circuit,
When erasing the video signal recorded on the magnetic disk, the magnetic head is configured to erase the image signal at two positions stored by the calculation means.

Operation The present invention has the above-described configuration, so that both the position of the reference track to be recorded determined by the standard, the position of the actually recorded magnetic track where the output level of the head amplifier is maximum, and the outside of each position are determined.・Since the magnetic head performs erasing at a very small position (III), there is no recorded video signal left unerased, no overwriting of video signals occurs, and S/N reduction and cross-modulation of the reproduced video signal occur. do not have.

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. Reference numeral 13 in the figure denotes a calculating means, which calculates the effect of 10 Am on the outside of both the position stored in the storage means 12 and the standard track position that should be stored, within 20 Am on the inner and outer circumferences around the reference track position that should originally be recorded. Calculate and store the position.

Arithmetic means 13 is also included in system control circuit 14 .

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 the configuration of this embodiment. When erasing a video signal recorded on a certain magnetic track,
First, the selector switch 6 is the magnetic head 3 and the head amplifier 8.
Connect. First, the magnetic head 3 is fixed at the position of the reference track 1a of the magnetic rack 1 to be erased, and the magnitude of the output of the magnetic head 3 is determined by the head amplifier 8. The signal is inputted to the comparing means 11 through the level determining means 10.

Next, the control drive circuit 7 moves the magnetic head 3 through the moving mechanism 4.
Stepping to move 10μm toward the outer circumference
The motor 6 is operated, and the magnitude of the output of the magnetic head 3 is similarly measured and inputted to the comparison means 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 means 11. Next, the magnetic head 3 was moved 40 μm toward the inner circumference (that is, 20 μm toward the inner circumference from the original reference track 1a position), and the output of the magnetic head 3 was measured in the same way.
It is input to the comparison means 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 comparing means 11. The position of the magnetic head 3 at which the output of the magnetic head becomes maximum among the head amplifier outputs at these six positions is outputted from the comparison means 11 and stored in the storage means 12.

Next, the calculating means 13 calculates the reference track 1a within a range not exceeding 20 μm on the inner and outer circumferences around the reference track position.
The position and two positions moved by 10 μm outside each position stored in the storage means 13 are calculated and stored. According to the output of this calculation means 13, first, the reference track 1 is
After moving the magnetic head 3 to a position far from position a, the changeover switch 6 connects the magnetic head 3 and the erasing circuit 9 to the position of the magnetic head 3 where the output of the head amplifier 8 is maximum (10 μm of q). Outside (however, reference track 1
Erasing is performed at a position within 20 μm of the inner and outer circumferences from position a (in Fig. 2, W4 = 10Ii from the reference track 1a position).
Position 0 on the inner circumference side is the position where the output of the head amplifier 8 is maximum, and erasing is performed by moving the magnetic head 3 further from that position to a position W4=10 μm on the inner circumference side). Next, in accordance with the output of the calculating means 13, the control drive circuit 7 moves the magnetic head 3 to a position 10 μm on the outer circumferential side of the reference track 1a to perform erasing (FIG. 3).

Furthermore, if the position where the output of the head amplifier 8 is at its maximum happens to be the reference track position 1a, it goes without saying that erasing is performed at positions 10 μm from the inner and outer circumferences around the reference track position 1a.

As described above, according to this embodiment, the head amplifier output is maximized in conjunction with the level determination means for A/D converting the output of the head amplifier and the control drive circuit that moves the magnetic head via the moving mechanism. a comparison means for outputting a magnetic head position, a storage means for storing the magnetic head position, and two positions that are slightly moved outside each position from the position stored in the storage means and the reference track position. By providing a calculation means for calculation and storage, the position where the output of the magnetic head is maximum is searched for before erasing, and the output of the calculation means is used to move the magnetic head via a moving mechanism, and the position and the reference track of the magnetic track are determined. You can erase the position and its neighboring positions, including each position. Thereby, it is possible to eliminate unerased portions of the recorded video signal due to the deviation of the center of rotation, and it is possible to eliminate S/N degradation and cross-modulation of the reproduced signal due to overwriting.

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

In addition, in this embodiment, the movement step of the magnetic head is 10μ.
I made it in m increments, but you can also make it smaller.

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 S/N of the reproduced signal due to overwriting.
Excellent effects such as eliminating degradation and cross-modulation can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a magnetic recording/reproducing apparatus according to a first embodiment of the present invention, FIGS. 2 and 3 are enlarged views of the same main parts, and FIG.
The figure is a block diagram of a conventional magnetic recording/reproducing device, and FIGS. 6 and 6 are enlarged views of the same essential parts. 1...Magnetic track, 1a...Reference track, 1C...Guard band, 2...
...Magnetic disk, 3...Magnetic head, 4...
...Movement mechanism, 6...Stepping motor, e...Selector switch, 7...Control drive circuit, 8...Head amplifier, 9...
. . . Erasing circuit, 10 . . . Level discrimination means, 1
1... Comparison means, 12... Storage means,
13... Arithmetic means, 14... System control circuit. Name of agent: Patent attorney Shigetaka Awano and one other person Figure 1α-Kuroko Torashik 3-・-? i! Rod head lα-- Storage truck lα...-i Semi-track 1b...-Card parid 3--... To magnetic field 16 Figure Ia---* Arm track To---75-Do band 3--- magnetic heud

Claims (1)

[Claims] A magnetic head for recording and reproducing video signals on a magnetic disk having a plurality of circumferential magnetic tracks, a moving mechanism for moving the magnetic head in the radial direction of the magnetic disk, and a head amplifier for amplifying the output of the magnetic head. a level determining means for determining whether the output level of the head amplifier is large or small; and a comparison for slightly moving the magnetic head by the moving mechanism and comparing the output level at each position determined by the level determining means. storage means for storing the position of the head at which the output level determined by the comparison means is the maximum; the position of the head at which the output level is the maximum stored in the storage means; and the position to be recorded on the magnetic disk. a calculation means that calculates and stores two positions that are slightly moved outside each position from the position of the reference track; and an erasing circuit that erases the video signal recorded on the magnetic disk using the magnetic head; a changeover switch for switching and connecting the magnetic head to the head amplifier and the erasing circuit; and when erasing the video signal recorded on the magnetic disk, the magnetic head is moved to two positions stored in the arithmetic means. A magnetic recording/reproducing device characterized in that erasing is performed using a .