JPS63205864A - Tracking device - Google Patents

Abstract

PURPOSE:To simplify a device by recording a tracking signal at the centers of one pair of data tracks, and detecting simultaneously the tracking signals by means of using one pair of data reproducing heads, and controlling the device by comparing the tracking outputs of both heads. CONSTITUTION:The tracks N-1, N, N+1 are provided on a recording medium 21, and one pair of data tracks 22, 23 and a servo track 24 at a central part are formed on the respective tracks. On the servotrack 24, the tracking signal (f) of a single frequency in a different frequency band from the data track is recorded. The tracking signal (f) of the servotrack 24 is reproduced from the data reproducing heads 26, 27 of a multi-channel head 25, as well. By controlling so that the tracking output signals of the reproducing heads 26, 27 are equal, the tracking signal can be a single frequency, and the device can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking device, and more particularly to a tracking device for controlling the tracing position of a head with respect to a track on a recording medium.

[Prior Art] For example, in a tracking method adopted in a fixed disk device, one surface of a single recording medium 1 made of a magnetic disk is dedicated for tracking, as shown in FIG. 2(A). There is a method used for

Tracking signals ft and f2 of two different frequencies are recorded alternately on this tracking-only surface, and now,
When the tracking head 2 is located in the middle of two adjacent servo tracks N and N+1, the two tracking signals ft and f2 from the head 2 have the same amplitude as shown in FIG. 2(B). is played. When the position of head 2 changes in the direction of one servo track N+1,
Tracking signal f1 increases, tracking signal f2
decreases. When the head 2 changes in the opposite direction, the tracking signal f2 increases and the tracking signal f1 decreases. If the reproduced tracking signals f1 and f2 are separated using a bandpass filter and the head 2 is controlled by a signal corresponding to the level difference between the two signals, the head 2 will move to follow the centers of tracks N and N+1. It turns out.

However, in the case of flexible disk drives, if one side of a single recording medium is occupied exclusively for tracking, data can only be recorded on the other side, resulting in poor efficiency. Therefore, in a conventional flexible disk device, as shown in FIG. 3, data tracks N-1°N and N+1 are generally arranged on a recording medium 3 made of a flexible disk with a guard band G of a constant width interposed between them. The head (not shown) is controlled to run on the data track in an oven loop during reproduction. However, since it has a guard band G, in this case as well, the data recording area is reduced and efficiency is poor.Furthermore, since the head is run in an oven loop, highly accurate tracking is not possible. Not done.

Therefore, in video tape recorders etc., Fig. 4 (
As shown in A), tracking signals ft, f2-fa, and tracks of different frequencies are applied to tracks N-1, N, N+1°N+2 on the recording medium 4 made of videotape, respectively.
There are cases where f4 is superimposed on the video signal and recorded without a guard band.

Tracking signals f1. of four types of frequencies. f2゜fa,
f4 is recorded in circular order. Azimuth recording is used for the video signal to prevent crosstalk between adjacent tracks. Recording and reproduction are performed by the head 5, and during reproduction, a video signal and a tracking signal having different frequency bands are separated by a filter.

Now, when the head 5 is located at the center of track N when reproducing the video signal of track N, as shown in FIG.
As shown in , the tracking signal f2 is mainly output, but when the head 5 deviates in the direction of track N+1, the tracking signal f3 increases, and conversely, when the head 5 deviates in the direction of track N-1, the tracking signal f2 increases. Signal fl increases. Since the head 5 moves in the direction of track N+1 in proportion to the amplitude of the tracking signal f1, and in the direction of track N-1 in proportion to the amplitude of the tracking signal f2, the tracking signals f1 and f2 The head 5 is stabilized at a position where the amplitudes of the signals are equal, and the video signal of track N is reproduced.

However, in such a tracking device, the tracking signal is superimposed on the video signal and recorded on the same track, so it is necessary to provide a filter to separate the tracking signal and the video signal, and this filter However, it is difficult to completely separate the video signal and the tracking signal, resulting in deterioration of the video signal.

Therefore, as an improved version of such a tracking device, there is a tracking device disclosed in Japanese Patent Application Laid-Open No. 58-35769. As shown in FIG. 5, recording tracks N-1, N, and N+1 are formed on a recording medium 6 such as a flexible disk, and these recording tracks are a data track 7 on which data is recorded. ,
It consists of 8.9 servo tracks on both sides of which tracking signals are recorded. Each pair of servo tracks, recording tracks N-1, N, and N+1, receives tracking signals f1. f2. f3 are recorded and formed in a circular order. The head 10 integrally includes a data head 11 for recording and reproducing data and a tracking head 12 for reproducing tracking signals, both of which are separated by a magnetic shield plate 13. Now, when the head 10 is scanning the recording track N, among the reproduction signals obtained from the tracking head 12, the tracking signal f2 is the largest, the tracking signal f1 of the recording track N-1, and the tracking signal f3 of the recording track N+1. is output less than that. tracking signal f
Since the position of the head 10 is controlled so that the amplitudes of 1 and fa are equal, the head 10 moves to follow the recording track N, and the data head 1.1 correctly reproduces the data on the data track 7. .

[Problems to be Solved by the Invention] However, in the tracking device shown in FIG. 5, the tracking signals are composed of at least three different frequency signals f1. f2. Needs f3. 5th above
Even in devices other than those shown in the figure, all closed-loop tracking devices use tracking signals with multiple different frequencies, so they require complex circuits using band-pass filters, etc. to separate each tracking signal. Configuration required.

In view of the above-mentioned points, an object of the present invention is to provide a tracking device that can use a tracking signal of a single frequency.

[Means and effects for solving the problem] The tracking device of the present invention is a tracking device that reproduces a pair of data tracks of a recording medium in which a tracking signal is recorded at the center of a pair of data tracks to form a servo track. a reproducing head; means for detecting the tracking signal of the servo track by the pair of reproducing heads and comparing the output signals from both of the reproducing heads; and a means for generating a signal for controlling the positional relationship between the two playback heads, and the tracking signal detected by the pair of playback heads is transmitted to the central one of the data tracks.
It is a single frequency tracking signal that forms the servo track of the book.

[Embodiment] An embodiment of the present invention will be described with reference to FIGS. 1(A) and 1(B). Figure 1 (A) shows a flexible disk (FD)
This is a track pattern formed on a recording medium 21 such as.

In FIG. 1(A), adjacent recording tracks N-1, N, and N+l on the recording medium 21 are a pair of data tracks 22, 23, and a pair of data tracks 2, respectively.
2. Servo track 24 formed in the center part of 23
It consists of

The data tracks 22 and 23 are formed with the same track width a, and the servo track 24 is formed with the same track width. Said recording track N-1,N.

On each of the N+1 servo tracks 24, a tracking signal f of a single frequency in a frequency band different from the frequency of the data recorded on the data tracks 22 and 23 is recorded.

A multi-channel head 25 is used to form the recording tracks N-1, N, and N+1. The multi-channel head 25 integrally includes data recording/reproducing heads 26 and 27 for recording and reproducing data, and a tracking signal recording head 28 for recording a tracking signal f. Therefore, as shown in FIG. 1(A), when this multi-channel head 25 is located on the recording track N, the data recording/reproducing head 26.
27 are located opposite to the data tracks 22 and 23, respectively, and the tracking signal recording head 28 is located opposite to the servo track 24. In other words, when recording is performed using the multi-channel head 25, the data track 22 on which data is recorded by the data recording/reproducing heads 26 and 27
．． At the same time, a servo track 24 on which a tracking signal f is recorded by a tracking signal recording head 28 is formed, thereby forming a recording track N. Recording tracks N-1 and N+1 are also formed in the same manner. Therefore, each servo track 24 of recording tracks N-1, N, and N+1 is formed with two data tracks 22 and 23 having a track width a separated from the adjacent recording track. The distribution state of magnetic flux density due to the tracking signal f recorded on each servo track 24 is as shown in FIG. 1(B), and the tracking signals r on each servo track 24 are magnetically separated from each other.

Next, tracking of the multi-channel head 25 will be explained. When the multi-channel radar 25 is tracking, the data recording/reproducing heads 26 and 27 are in a reproducing state, and the tracking signal recording head 28 is in an inactive state.

During playback, the data recording/reproducing heads 26, 27 reproduce each data recorded on the data tracks 22, 23, and at the same time, the tracking signals f recorded on the servo track 24 are also reproduced by each head 26, 27. do. If the data recording/reproducing heads 26.27 of the multi-channel head 25 are running correctly on the data tracks 22.23, the data recording/reproducing heads 26.2
The amplitudes of the tracking signals f output from the heads 26 and 7 are equal to each other, but if the data recording/reproducing heads 26 and 27 are shifted to one side and deviate on the data track 22 and 23, the amplitudes of the tracking signals f output from the heads 26 and 27 are the same. The amplitudes of the tracking signals f are different. That is, if the multi-channel head 25 is on recording track N and deviates from its correct position in the direction of recording track N+1, as shown in FIG. 24, and the other data recording/reproducing head 27 moves away from the servo track 24, so the amplitude of the tracking signal f output from the data recording/reproducing head 26 increases, and the tracking signal f output from the data recording/reproducing head 27 increases. The amplitude of signal f decreases. Conversely, when the multi-channel head 25 deviates in the direction of recording track N+1, the amplitude of the tracking signal f output from the recording/reproducing head 26 in the above direction decreases, and The amplitude of the output tracking signal f increases. Therefore, the amplitudes of the tracking signals f output from the upper recording/reproducing heads 26 and 27 are compared using a differential amplifier or the like, and the tracking signal f from the recording/reproducing head 26 is larger than the tracking signal f from the recording/reproducing head 27. In this case, the multi-channel head 25 is moved in the direction of the recording track N-1 by the head actuator, and conversely, when the tracking signal f from the recording/playing head 27 is larger than the tracking signal f from the recording/playing head 26. moves the multi-channel head 25 in the direction of recording track N+1.

As a result, the multi-channel head 25 moves forward and backward on the recording track N.

Here, the multi-channel head 25 moves from the recording track N to the adjacent recording track N+1 or N-1 as follows:
The head is fed at a head feed interval of (2a+b). Therefore, the mechanical accuracy of head feed is ±(a +
b/2), when the multi-channel head 25 is reproducing a predetermined recording track N, the multi-channel head 25 will move to the adjacent recording track N+ unless the head is moved.
1. To perform accurate tracking without shifting to N-1.

At present, the positioning accuracy α of the stepping motor for head feeding is approximately ±4 to 5 μm, so it is possible to achieve a minimum value aff11n of the data track width a of about 5 μm.

Further, in the tracking device of the present invention, two data recording/reproducing heads 26 and 27 are used to track the data tracks 22.
For example, a luminance signal may be recorded on one data track 22, a color signal may be recorded on the other data track 23, or independent data may be recorded on each data track 22 and 23. may be recorded and then played back. For example, when trying to perform digital recording or high-quality recording, which is currently attracting attention, multi-channel recording is required, and therefore it is necessary to use the two data recording/reproducing heads 26 and 27 as described above. The tracking device is suitable for digital recording and reproduction of high-quality recorded data.

[Effects of the Invention] As described above, according to the present invention, since the tracking signal forming the servo track can be made to have a single frequency, reproduction is simple and the reproduction device, that is, the tracking device is simplified. be able to.

[Brief explanation of the drawing]

FIGS. 1(A) and (B) are a diagram showing an example of a track pattern of a recording medium used in the present invention, and a diagram showing a distribution state of magnetic flux density of a recorded tracking signal; FIG. 2(A) and (B) is a diagram showing a track pattern of a recording medium used in an example of a conventional tracking device, and a diagram showing a distribution state of magnetic flux density of a recorded tracking signal. A diagram showing an example of a track pattern of a recording medium used. FIGS. 4A and 4B are diagrams showing a track pattern of a recording medium used in another example of a conventional tracking device and recorded tracking signals. FIG. 5 is a diagram illustrating a track pattern of a recording medium used in yet another example of a conventional tracking device. 21・・・・・・・・・・・・Recording medium 22.2
3...Data track 24...
・・・・・・Servo track 25・・・・・・・・・・
...Multi-channel head 26.27...
・Data recording/playback head (pair of playback heads)

Claims (1)

[Scope of Claims] A pair of playback heads for playing back the pair of data tracks of a recording medium in which a tracking signal is recorded at the center of the pair of data tracks to form a servo track; means for detecting a tracking signal of a track and comparing the output signals from the two playback heads; and a signal for controlling the positional relationship of the playback heads with respect to the data track on the recording medium based on the output from the comparing means. A tracking device characterized by comprising means for generating.