JPS61156555A - Rotary head type recording and reproducing device - Google Patents

Abstract

PURPOSE:To align a locus of a head of the time of recording to a correct position by determining a height of the second head so as to draw a center locus which has been shifted in the advance direction of a tape by half of a nominal value of a lap width in case of azimuth recording, and executing a servo-control so that the second head executes tracking correctly. CONSTITUTION:Reproducing heads 41, 42 and recording heads 43, 44 are fixed to a substrate 45, respectively, rotated in the direction as indicated with an arrow x2, and a tape 47 is wound diagonally to a part of the substrate 45, and runs in the direction as indicated with an arrow x1. The recording heads 43, 44 have each different azimuth angle, and contact alternately to the tape 47 by a rotation of the substrate 45, therefore, a track is formed, and a center locus of the head is deviated by 45 deg. by spacers 49, 50. In this way, even at the time of after-recording, the locus of the recording head can be aligned to an optimum position by making a dynamic range of a tracking-servo equal to that of the time of usual reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rotary head type recording/reproducing device, and more particularly to a device for partially re-recording (after-recording) on a previously recorded tape.

[Technical background of the invention]

In rotary head type recording and reproducing devices used in video tape recorders and the like, two heads with different azimuth angles are used to increase the recording density, and as shown in Figure 3, they are alternately stacked against each other. Methods of forming tracks to match are known. In this method, during reproduction, since the head width is larger than the track width, the magnetic flux from the adjacent track is also received, but since the azimuth angle is different, the signal from the adjacent track is not reproduced.

To explain this in more detail, the tape recorder travels in the direction of arrow Xi, and the track is moved to AI by the head traveling in the direction of arrow x2.

B1. , 2, and so on are recorded sequentially. Trunk AJ.

Tracks A2... are recorded by the A head (not shown), and tracks Bl... are recorded by the B head 2. The A head and B head 2 have different azimuth angles. Trunk A7, Bl
, A, 2, etc. are recorded in an overlapping manner Φ, and the overlapping portions of the previous tracks are erased, and the tracks AI' and Bl' in the figure remain on the Qi fl.

A 2'... becomes. That is, focusing on track B1, the center trajectory of the head during recording is a dashed-dotted line t1, the center line of the trunk B7' formed by overwriting is a dashed-dotted line t2, and during playback, the center trajectory of the head is along the dashed-dotted line t2. Tracking servo is applied so that the center locus of ′ coincides with this. When B'head 2' plays back track B1', both ends of B'head 2' play back track A7',
A 2' is contacted, but since the azimuth angle is different, the signal of 2' is not reproduced on the rack kl'.

However, due to the influence of the anomalous angle, <b low frequency components are also reproduced from adjacent tracks. Utilizing this, a low frequency signal for tracking (so-called 2-Ironoto signal) is frequency multiplexed with a high frequency signal or recorded in a different area from the high frequency signal, and the low frequency signal from both adjacent tracks is The tracking error is detected by comparing the magnitude of the playback output. In order to distinguish which low-frequency signal is being reproduced from an adjacent track, or whether it is a low-frequency signal being reproduced from one's own track, it is necessary to change the frequency of the low-frequency signal for each track.
A method such as making use of the fact that each track is shifted by S in FIG. 3, and configuring recording/turning so that the low frequency signals of each trunk are not reproduced at the same time is taken.

[Problems with background technology]

However, the above configuration has the following problem during after-recording. Consider a case where each track that has already been recorded as shown in FIG. 4 is partially rewritten (for example, part X in FIG. 4) (after recording).

In the case of after-recording, when recording the X portion, the center locus of the head needs to match the dashed-dotted line t1. However, the pilot signal for tracking needs to be obtained when reproducing parts other than X, but in order to correctly maintain the center trajectory of the head during recording, /
Even when reproducing the IP pilot signal, the center of the head must coincide with the dashed line t1. In other words, if the head width is 1.5 times the width of track B1', etc., each track B
If the center of 1' + A 2' * B 2' is set to 00, and the centers of both adjacent tracks are set at ±180° as shown in the figure, reproduction must be performed centered at a position of 45°. FIG. 5 shows the relationship between the level (Lm) of the tracking error signal obtained from the low frequency signal for tracking and the tracking error angle &(θ,). During normal playback, a wide dynamic range centered around 0° can be obtained, but during after-recording the control center shifts to a 45° position, so if one side of the dynamic range is narrow or the track linearity is poor, etc. This makes it easy for the vehicle to go off track.

[Purpose of the invention]

This invention was made to address the above-mentioned circumstances, and even during after-recording, the dynamic range of the tracking servo is kept the same as during normal playback, while
It is an object of the present invention to provide a rotary head type recording/reproducing device capable of adjusting the head trajectory to the correct position during recording.

[Summary of the invention]

For example, during after-recording, the present invention uses a first head used for recording and a second head used for reproducing low-frequency signals for tracking, and azimuthals the central trajectory of the first head on the tape. By determining the height of the second head so as to draw a center locus shifted in the tape traveling direction by half the nominal value of the overlapping width in recording, and by controlling the servo so that the second head tracks correctly, The configuration is such that a correct trajectory of the first head can be obtained.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a head assembly portion 40 according to an embodiment of the present invention.

The second head 41, 42 is a playback head, and the first head 4
3.44 is a recording head. Each head is fixed to the substrate 45 and rotates in the direction of arrow x2. Chi f47
is wrapped diagonally around a part of the substrate 45 as shown in the figure,
Travel in the direction of arrow x1. The track is recording head 4
It is formed when 3°44 is in contact with chie f47. The recording heads 43, 44 have different azimuth angles and contact the tape 47 alternately (due to the rotation of the substrate 45), so that tracks such as the example of FIG. 4 are formed. In the case of the example shown in FIG. 4, the center locus of the recording head 43, 44 is shifted by 45 degrees due to the spacer 49, 60.

FIG. 2 shows the overall structure of an embodiment of the present invention. An l-pump 47 is sandwiched between a cab stan 52 driven by a motor 51 and a pinch roller 53, as indicated by the arrow XI.
Drive in the direction of.

The reproduced signal obtained from the head assembly section 40 is given to a servo control circuit 55 including a tracking error detection circuit via a head amplifier 54, and its output is used to rotate a motor 51 by a motor driver 56 and drive a driver 7047.
to drive.

The servo control is performed so that the reproducing heads 41, 42 correctly track the tracks as explained in FIGS. 4 and 5.

The signal to be after-recorded is sent to the recording head 43.
．． The timing at which data should be written is regulated by the relative position between F 44 and Q 47, and the data is applied to the head assembly section 40 through the write amplifier 7657, distributed to the appropriate recording heads 43 and 44, and after-recorded at a predetermined position. Ru.

The azimuth angles of the reproducing heads 41 and 42 have the following relationship.

That is, the azimuth angles of the recording heads 44 and 43 and the azimuth angles of the reproducing heads 42 and 41 are set to be equal to each other.

With this configuration, the recording heads 43 and 44 perform partial after-recording on one track, and the playback heads 41 and 42 subsequently detect a low-frequency signal for tracking, so the causal relationship appears to be reversed. However, since the time constant of the mechanical system is sufficiently low and the servo response speed is slow, and there are no sudden changes in the track pattern, the recording head 4 can be
The trajectory of 3.44 is determined, so there is no problem.

Further, the azimuth angle of the reproducing heads 41 and 42 may be determined as follows. That is, the azimuth angles of the recording heads 43, 44 and the reproducing heads 42.degree. 41 are made equal. However, in this case, playback head 4
It is necessary to make the height of 1.42 higher so that the reproducing head and the recording head with the same azimuth angle scan one track. Although the case where two second heads are provided has been described, it goes without saying that there may be three or more.

〔Effect of the invention〕

As described in detail above, according to the present invention, even during after-recording, it is possible to adjust the trajectory of the recording head to the optimum position while maintaining the same dynamic range of the tracking sensor as during normal playback. Further, if the anomalous angle of the reproducing head is determined so that the recording head having the same azimuth angle precedes the recording head, there is an advantage that reproduction can be performed immediately after recording, and so-called simultaneous monitoring is also possible.

[Brief explanation of drawings]

Figure 1 shows the configuration of an embodiment of the present invention, particularly the configuration of the head assembly section, Figure 2 shows the overall configuration of an embodiment of the invention, and Figure 3 shows the tracking FIG. 4 is a diagram showing the relationship between the error signal and the tracking error angle, FIG. 4 is a diagram for explaining azimuth recording, and FIG. 5 is a diagram for solving problems during after-recording of anomalous recording. 40... Head assembly section, 41.42... Second head (reproduction head), 43.44... First head (recording head), 45... Substrate, 47... Tape, 5 No...Motor, 52...Cab stan, 53
...Pinch roller, 54...Head amplifier, 55.
... Servo control circuit, 56 ... Motor driver, 57
...Writing amplifier. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claim] A rotary head type recording and reproducing device that performs azimuth recording, extracts a tracking error signal from a reproduced signal, and reproduces it while applying tracking servo, comprising: a first head; A second head is arranged to draw a center trajectory that is shifted in the tape traveling direction by half the overlapping width in azimuth recording with respect to the trajectory on the tape, and a playback signal obtained by this second head is servo means for performing tracking so that the center locus of the second head coincides with the center line of the track using the obtained tracking error signal; A rotary head type recording/reproducing device, characterized in that it is configured to record a new signal.