JPH051551B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention is directed to a magnetic disk reproducing device compatible with a magnetic disk type electronic still camera, which receives signals from a magnetic disk having a plurality of signal recording/reproducing tracks. In a magnetic disk reproducing machine configured to be capable of reproducing, when reproducing a signal, the magnetic head for picking up the reproduced signal is used to record/record the signal.
The present invention relates to a tracking device provided to follow a reproduction track.

(Prior Art) An example of a device that uses a magnetic disk to record video signals and accompanying information signals is a magnetic disk type electronic still camera. This electronic still camera is a device configured to perform only recording operations, and in order to reproduce the signals recorded on the magnetic disk, a separate device is required from the electronic still camera dedicated to recording. A special machine for playing magnetic disks is required.

Therefore, when different devices are used for recording and playback, problems such as eccentricity of the tracking position with respect to the magnetic disk or misalignment of the magnetic head in one or both of the recording and playback devices are particularly important. Due to this, when playing back with a magnetic disk player, the tracking position and the position of the magnetic head with respect to the magnetic disk will be in a different state than when recording with a magnetic disk recorder, and the track on which the signal was recorded will be in a different state. On the other hand, an inconvenient phenomenon (so-called track deviation) is likely to occur in which the magnetic head for picking up the reproduced signal cannot trace accurately and cannot perform good reproduction.

Furthermore, the above-mentioned phenomenon of track deviation is caused by
This phenomenon does not necessarily occur only in magnetic disk playback machines, but can also occur during playback in magnetic disk recording/playback machines due to the expansion, contraction, and deformation of the magnetic disk itself due to the effects of temperature, humidity, etc. be.

Therefore, in order to ensure a good playback function in a magnetic disk device equipped with a magnetic disk playback function, whether it is a dedicated magnetic disk playback machine or a magnetic disk recording/playback machine, it is necessary to so that the magnetic head for signal pickup can accurately trace the recording track.
It is necessary to appropriately control the position of the magnetic head for picking up the reproduced signal.

By the way, magnetic disks generally rotate at a high speed of 3,600 revolutions per minute, while magnetic heads are normally fed at a pitch of several microns by a stepping motor, which can cause track misalignment due to the reasons mentioned above. In order to cause the magnetic head to accurately trace the track that has been drawn, an extremely complex and sophisticated control mechanism using a servo head or the like using high-grade voltage elements is required. Therefore, when such a mechanical control means is adopted, it is not only difficult to expect stable control functions over a long period of time, but also has the drawback of causing a significant increase in manufacturing costs.

Therefore, the inventor of the present invention conducted intensive research to find an effective means for preventing the track deviation without relying on mechanical control means that would cause various inconveniences as described above, and as a result, obtained the following knowledge. It came to this.

That is, when the track deviation as described above is large, as shown in FIG. When the track deviation is small, both the upper and lower envelope outlines A and B of the reproduced output are relatively flat, as shown in Figure 3A. In the case of FIG. 3B where the track deviation is large, and in the case of FIG. It can be seen that this is much smaller in the case of Figure 3 (b) where the track deviation is large. Based on this result, if the best reproduction output is obtained with no track deviation at all, the difference between the maximum value 2Max and the minimum value 2Min of the interval between the upper and lower envelope outlines A and B must be (or equivalent to half of that |Max−Min|)
It can be estimated with very high certainty that .

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional situation and new findings as a result of research, and its purpose is to have a relatively simple structure, low manufacturing cost, and long-term durability. In order to be able to expect a stable control function, the system does not rely on the mechanical control means described above, even when there is a risk of track deviation of the attached magnetic disk.
An object of the present invention is to provide a tracking device for a magnetic disk player that can automatically control the position of a magnetic head for picking up a reproduced signal so that the quality of the reproduced signal is the best.

(Structure of the Invention) In order to achieve the above object, a tracking device for a magnetic disk player according to the present invention has the basic structure described at the beginning.
Signal recording/recording of magnetic head for playback signal pickup
A moving means for moving the magnetic head for picking up the reproduced signal by a predetermined amount to position it to follow the reproduction track; and upper and lower envelopes of the reproduced signal output from the magnetic head for picking up the reproduced signal after being moved by the moving means. detection means for respectively detecting the maximum value and minimum value of the outer contour lines, and the reproduction signal at a position where the difference between the maximum value and the minimum value of the reproduction signal output detected by the detection means is substantially minimum. control means for controlling the moving means so that the signal pickup magnetic head is positioned;
It is equipped with

(Example) Hereinafter, specific examples of the present invention will be described based on the drawings (FIGS. 1 and 2).

A tracking device in a magnetic disk player according to the present invention is constructed as shown in the block circuit diagram of FIG.

That is, the reproduced signal is picked up by a magnetic head for picking up the reproduced signal (reproduction head) 1 and amplified by the head amplifier 2, and after the lower half of the reproduced waveform is cut by the limiter 3, it is input to the low-pass filter 4. In this low-pass filter 4, the upper envelope outline (A in FIG. 3) of the upper and lower envelope outlines of the reproduced waveform is approximately symmetrical.
is extracted, and after reducing its sensitivity to short-term noise and dropout, it is input to the Max sampling Hall circuit 5 and the Min sampling hold circuit 6, and the Max sampling hold circuit 5 detects both the upper and lower envelopes of the reproduced waveform. The maximum value Max of the upper envelope outline A corresponding to half of the maximum value 2Max of the interval between the outline lines (A and B in FIG. 3) is sampled and held, and the Min sampling and hold circuit is provided. 6 samples the minimum value Min of the upper envelope outline A, which corresponds to half of the minimum value 2Min of the interval between the upper and lower envelope outlines A and B of the reproduced waveform, and holds that value. A switch controlled by the system controller 7
When the SW is controlled to switch to the terminal a side, the Max signal output from the Max sampling and hold circuit 5 is input to the A/D converter 8 and converted from an analog value to a digital value. , is input to the system controller 7, and similarly, the switch SW is input to the terminal b
When the switch is controlled to the side, the Min output from the Min sampling hold circuit 6
The signal is input to the A/D converter 8, converted from an analog value to a digital value, and then input to the system controller 7. Then, as shown in detail in the control flowchart of FIG. 2, the system controller 7 determines the maximum value of the upper envelope outline A of the input reproduction waveform
After calculating and storing the difference Max-Min between Max and the minimum value Min, a signal is sent to the stepping motor drive circuit 9 to drive the stepping motor 10 by a predetermined unit amount to position the magnetic head 1 for picking up the reproduced signal. Move by a predetermined unit amount (1 pitch),
Again, as above, the upper envelope outline A of the reproduced waveform
By repeating the operation of calculating and storing the difference Max-Min between the maximum value Max and the minimum value Min, and comparing the previous and current differences Max-Min, the upper envelope outline of the reproduced waveform can be calculated. Maximum value of line A
The difference between the Max and the minimum value Min, Max−Min, that is, the difference between the maximum value 2Max and the minimum value 2Min of the interval between the upper and lower envelope contour lines A and B of the reproduced waveform is substantially minimized. The position of the magnetic head 1 for picking up the reproduced signal is automatically adjusted to correct track deviation.

In the above embodiment, since the switch SW controlled by the system controller 7 is used, the A/D converter 8 only receives one signal (Max and Min).
It is necessary to perform two A/D conversions for
If an analog adder is used in place of the changeover switch SW, the A/D conversion by the A/D converter 8 only needs to be performed once, and the switch changeover control and addition calculation by the system controller 7 can be omitted. This has the advantage of significantly reducing time.

(Effects of the Invention) As is clear from the above detailed description, according to the tracking device in the magnetic disk reproducing machine according to the present invention, the difference between the maximum value and the minimum interval between the upper and lower envelope outlines of the reproduced signal With a relatively simple configuration in which the position of the magnetic head for picking up the reproduced signal is automatically adjusted so that the magnetic head is substantially minimized, the manufacturing cost is low and a stable control function can be expected over a long period of time. Even though an electrical control means is used, the position of the magnetic head for picking up the reproduced signal is adjusted so that the quality of the reproduced signal is always the best, even when there is a possibility that the track of the attached magnetic disk may be misaligned. The excellent effect of reliable and automatic control has been achieved.

[Brief explanation of the drawing]

1 and 2 show a specific embodiment of a tracking device in a magnetic disk player according to the present invention, and FIG. 1 is a block circuit diagram of the device configuration;
FIG. 2 is a flowchart showing the control sequence. 3A and 3B are for explaining the problems in the prior art and the technical background of the present invention, and FIG. 3A is a time chart of the reproduced signal when the track deviation is small, and FIG. 3B shows time charts showing reproduced signals when the track deviation is large. 1...Magnetic head for picking up the playback signal (playback head), A, B...Both upper and lower envelope outlines of the playback signal, 2Max...Maximum value of the interval between the upper and lower envelope outlines of the playback signal, 2Min...Playback The minimum distance between the upper and lower envelope outlines of the signal.

Claims (1)

[Scope of Claims] 1. In a magnetic disk reproducing machine configured to be able to reproduce signals from a magnetic disk having a plurality of signal recording/reproducing tracks, when reproducing a signal, a magnetic head for picking up a reproduced signal is connected to the signal recording/reproducing track.
A tracking device is provided for positioning the reproduction signal pickup magnetic head accurately to follow the reproduction track, and the reproduction signal pickup magnetic head is provided for positioning the reproduction signal pickup magnetic head to follow the signal recording/reproduction track. A moving means for moving the head by a predetermined amount, and a detection for detecting the maximum and minimum values of the upper and lower envelope outlines of the reproduced signal output from the magnetic head for picking up the reproduced signal after being moved by the moving means. and controlling the moving means so that the magnetic head for picking up the reproduced signal is positioned at a position where the difference between the maximum value and the minimum value of the reproduced signal output detected by the detecting means is substantially minimized. A tracking device for a magnetic disk player, comprising: a control means for controlling; and a tracking device for a magnetic disk player.