JPS60140522A - Detection for tracking error - Google Patents

Abstract

PURPOSE:To make high-precision tracking control possible by multiplexing two carrier waves with a main signal in such arrangement that a tracking error voltage can be detected and recording them and performing a control at a reproducing time so that this tracking error voltage is minimum. CONSTITUTION:One track is divided to a prescribed number of (generally, even) blocks, and for example, a carrier wave Asinomega1t is recorded in every even-numbered block of an A track 11 and every odd-numbered block of a B track 12, and a carrier wave Asinomega2t is recorded in every even-numbered block of a C track 13 and every odd-numbered block of a D track 14, and these four tracks are used as one unit, and hereafter, this arrangement is repeated. In this case, these carrier waves are multiplexed with the main signal and are recorded. At a reproducing time, crosstalk quantities from tracks adjacent to a scanned track are defined as (a) for the carrier wave Asinomega1t and as (b) for the carrier wave Asinomega2t. The direction of tracking deviation of a reproducing head is discriminated by the sign of a voltage (a-b), and the extent of tracking deviation is proportional to ¦a-b¦, and therefore, a servo operation is always performed for (a-b)=0.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a tracking error detection method, and in particular, when high-density recording and reproduction is performed on a recording medium such as a magnetic tape or a magnetic disk, a dedicated tracking track or tracking error detection method is used. The present invention relates to a tracking method that allows tracking without using a sensor.

[Prior Art] Tracking on conventional magnetic disks is performed only within the range of mechanical precision, and in video tape recorder (VTR) devices that use magnetic tape, tracking is performed using a dedicated control track.・)
ing.

FIG. 1 is a diagram showing a tracking method in a conventional general VTR device. In FIG. 1, magnetic tape 1
αF racks 2 and β tracks 3 are provided alternately. Further, a control track 4 is provided at the lower end of the magnetic tape 1. A control signal 5 is recorded on this control track 4.

In the α track 2 and the β track 3, si is sequentially recorded in units of one field. On the other hand, a control signal 5 is recorded on the control track 4 in synchronization with the recording start time of each track. In playback mode,
The control signal 5 is regenerated and the tracking control is performed using the change point as a reference signal, so that the normal α track 2i
15 and β track 3. Tracing is performed in the direction of the arrow in FIG. 1 with the control signal as a reference.

FIG. 2 is a diagram showing the configuration of one track in a VH8 type VTR. One track shown in FIG. 2 has a configuration in the standard mode, but the ratio of the track width (58 .mu.-) to the track length (approximately 1Qc+n) is actually 1700 times. Incidentally, since the tracking control is performed using the control signal 5 representing the track recording start point, the control points are only the points shown in FIG. 2A. This rectangular tracing is performed only at the A point, and no control is applied after that, so in order to reproduce without causing track deviation, track bending due to mechanical precision or expansion and contraction of the magnetic tape 1, etc. There are strict requirements regarding 6.

Furthermore, in a long-time mode VTR, the track width is one third, 19 μm, making tracing even more difficult and requiring greater precision.

Since the conventional tracking method is configured as described above, it has the drawbacks of being too dependent on mechanical precision and being unable to perform sufficient tracking of track bends 6 within one track.

[Summary of the Invention] Therefore, the main object of the present invention is to multiplex and record electric signals as raw signals under predetermined rules, thereby making it possible to obtain track deviation information over the entire track length during playback, and It is an object of the present invention to provide a tracking method that does not require a control track that requires mechanical precision.

□The above-mentioned objects and other objects and features of the present invention will become clearer from the detailed description given below with reference to the drawings.

[Embodiment of the Invention] FIG. 3 is a diagram showing an example of a carrier wave arrangement necessary for tracking error signal detection of the present invention, and FIG. 4 shows carrier wave amplitude values of each block for the arrangement shown in FIG. 3. It is a diagram. . In FIG. 3, one track is divided into a predetermined number of blocks (generally an even number), and as shown in track A 11, for example, a carrier wave As1n is applied to an even numbered part of each block.
Record ω and t. In the next eight tracks 12, a carrier wave As1nω,t is recorded for each odd-numbered block, in the C track 13, a carrier wave A sinω2t is recorded in an even-numbered part, and in the β track 14, a carrier wave As1nω2t is recorded in an odd-numbered part.
This arrangement is then repeated using these four tracks as one unit. Note that a blank space within a block in FIG. 3 means that no carrier wave is recorded.

To summarize the above-mentioned m transmission recording example, carrier waves having the first frequency (hereinafter referred to as the 111th transmission wave) are arranged alternately in each block over two tracks, and the carrier wave having a frequency of 2 (hereinafter referred to as the 2nd carrier wave)
(referred to as carrier waves) are arranged alternately, but at this time, when looking at the carrier waves of the tracks on both sides from the non-carrier block, the arrangement is performed so that there are mutually different carrier waves.

Furthermore, the recording amplitudes of both carrier waves are the same. When recording,
Appropriate processing is performed to obtain this pattern, and the signal is multiplexed with, for example, the main signal and recorded.

During reproduction, when a head (not shown) scans a track, crosstalk from adjacent tracks naturally exists. At this time, the amount of crosstalk from adjacent tracks before and after the scanned track is calculated as follows: a for a carrier wave having a first frequency (first carrier wave), and a for a carrier wave having a second frequency (second carrier wave). For this, it is set as b. By frequency-discriminating the signals from the scanning track and comparing the crosstalk levels of the 11th transmission wave and the second carrier wave, amplitude information as shown in FIG. 4, for example, can be obtained. In addition, in scanning the B track 12, the track one before this scanning track is the A track 11, and the track one after this scanning track is the C track 13.

The same applies to the following tracks. If the carrier waves of each track are recorded under the same conditions (conditions where the amplitude is constant), the amounts of crosstalk a and b from adjacent tracks
The value of has symmetry with respect to track deviation, and (a − b
) becomes the tracking error signal. For example, when scanning the B track 12, if the playback head on this scanning track is shifted to the previous track, that is, to the A track 11 side, then a > b > O, and (
a-b) becomes a positive voltage.

However, when the playback head moves to the next track, that is, C.
If it deviates to the track 13 side, h>a>Q, so (a-b) becomes a negative voltage.

In the optimal tracking state, it is a-b, and (a-b> is O voltage).

Therefore, the direction of the tracking deviation of the playback head is
(a-b) It can be determined depending on whether the voltage is positive or negative, and the amount is proportional to 1a-bl, so it is always (
The servo operation may be performed with the goal of a − b ) =O.

By the way, as shown in FIG. 4, depending on the scanning track, the polarity is reversed like b - a -- (a - b ), but this polarity reversal appears regularly;
In both cases, the carrier wave of the track immediately before the scanning track is the second W transmission wave.

Therefore, it is detected by appropriate means whether the carrier wave of the track immediately before the scanning track is the 11th IIIi transmission wave or the second carrier wave, and only when it is the second carrier wave - (a - b ) By reversing the voltage polarity, tracking control can be performed on all tracks under the same conditions.

Now, in a block where a carrier wave does not exist, the influence of the first and second carrier waves is only due to crosstalk and does not cause major interference to the main signal, but in a block where a carrier wave exists, there is a risk of affecting the main signal. be. In this case, by frequency-discriminating the first or second carrier wave from the main signal, inverting it, and then adding it to the main signal, the influence can be reduced.

Note that the above embodiment can also be applied to a disk, and if concentric circles with the same radius are assumed to be tracks, carrier wave arrays similar to those described above may be performed for adjacent concentric circles. .

Furthermore, in the above embodiment, the application to a VTR device or a disk@H was explained as an example, but it can also be applied to other devices such as a rotary head type digital audio tape recorder, an optical IA density recording/reproducing device, etc. It is.

[Effects of the Invention] As described above, according to the present invention, two carrier waves with different frequencies are recorded in multiple positions in the main signal in an arrangement in which a tracking error voltage can be detected, and during playback, this tracking F
Since the i4g voltage is controlled to be the lowest, the device can be made inexpensive without imposing excessive demands on mechanical accuracy, and since tracking is performed over the entire length of the track, highly accurate tracking control is possible. be able to.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a tape format in a conventional VTRM device. FIG. 2 is a diagram showing the configuration of one track shown in FIG. 1. FIG. 3 is a diagram showing an example of a carrier wave arrangement necessary for detecting a tracking error signal according to the present invention. FIG. 4 is a diagram showing carrier wave amplitude values of each block for the arrangement shown in FIG. 3. In the figure, 1 is a magnetic tape, 2 is an α track, and 3 is a β track.
[・Rack, 4 is control 1 rack, 5 is control 1
Herol Shintan, 11 to 18 indicate trucks. Masuo Daiiwa Figure 1 Figure 2 Figure 3 Figure 4 Procedural amendment (voluntary) Commissioner of the Japan Patent Office 1, Indication of the case, Patent Application No. 1983-250186 2, Name of the invention Tracking error detection method 3. Relationship with the case of the person making the amendment Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name
(601) Mitsubishi Electric Co., Ltd. Representative Katayuni 8th Department 4, Agent Address: 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo, Column 6 of Detailed Description of the Invention in the Specification Subject to Amendment, ? IA positive details! i Page 15, line 7, line 7 letter B, set 1 to "main signal"
Correct to. that's all

Claims (2)

[Claims] (1) In a recording medium in which a plurality of recording trajectories of information recorded on the recording medium are lined up in the width direction of the recording trajectories, the recording trajectories are equally divided in the traveling direction of the trajectories into a plurality of blocks. In the 11th recording trajectory, a carrier wave having the first frequency is recorded for each even numbered block, and in the 2% 1st recording trajectory, a carrier wave having the first frequency is recorded for each odd numbered block. Record 3
In the first recording trajectory, a carrier wave having a second frequency is recorded for every even numbered block, and in the fourth recording trajectory, a carrier wave having a second frequency is recorded for every odd numbered block, These four recording trajectories are 1
Before repeating this array as a unit from now on! A tracking error signal is obtained by recording carrier waves having first and second frequencies, and comparing the amount of crosstalk between the carrier waves having the first frequency signal and the carrier wave having the second frequency signal during playback. A tracking error detection method characterized by: (2) Furthermore, the tracking error signal is inverted depending on whether the frequency of the carrier wave recorded in the recording trajectory one before the recording trajectory to be reproduced is the first frequency or the second frequency. A tracking error detection method according to claim 1, characterized in that: