JP3008712B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for recording information such as video, audio and data on a magnetic tape and reproducing the recorded information, and more particularly to an insert editing (rewriting of a predetermined recording area) function. The present invention relates to a magnetic recording and reproducing apparatus having

[0002]

2. Description of the Related Art Magnetic recording / reproducing apparatuses using a magnetic tape as a medium, such as a video tape recorder (hereinafter abbreviated as VTR), have been put into practical use and spread. Further, the miniaturization and digitization of the apparatus by higher density recording are being developed. In order to increase the recording density and ensure compatibility, it is important to accurately track the rotating head and the track. A VTR adopting a tracking control method called an ATF system for performing tracking using a signal has been put to practical use.
Hereinafter, an example of a conventional magnetic recording / reproducing apparatus will be described.

First, at the time of recording, diagonal recording tracks are sequentially formed on a magnetic tape by a rotary head attached to a cylinder. At this time, in addition to the information signal to be recorded, a pilot signal for tracking is frequency-multiplexed in the signal from the rotary head. For example, two types of pilot signals recorded at different frequencies f1 and f2 are alternately recorded every other track. Generally, this pilot signal is selected from one to four low-frequency frequencies that do not interfere with the information signal, and is recorded by being sequentially switched.

[0004] The following describes how the track thus formed is tracked during reproduction. Now, when the rotary head passes over the track to be reproduced, pilot components f1 and f2 from adjacent tracks are induced in the rotary head in addition to the information signal. The relative positional relationship between the rotating head and a desired track can be known.
That is, the f1 and f2 components are detected by the band-pass filter, converted into DC components corresponding to the respective levels by the AM detection circuit, and compared by the difference circuit. The output of the difference circuit is a relative position error between the rotating head and the track to be reproduced, that is, a tracking error signal. This tracking error signal is input to a capstan motor control circuit for controlling the tape running, and the control circuit controls the tape feed so that the rotating head moves to the center of the desired track by moving the capstan motor.

[0005] Regarding the operation for rewriting the information signal of the recorded tape to another information signal (hereinafter abbreviated as "insert editing"), the mode is switched from reproduction to recording at the time of rewriting, and overwriting is performed. At the same time as erasing the information signal, a new information signal is recorded. At this time, the tracking error signal is detected from the area on the track where the rewriting is not performed, and the tracking is performed. Usually, a tracking signal recording area is provided in a specific area on a track, and a tracking error is detected when the area is scanned by a head. Further, a positioning information signal is recorded in part or all of the tracking signal recording area. As this positioning information signal, a relatively high frequency which is hardly affected by an adjacent track is selected. The timing for sampling the tracking error signal is determined based on the timing at which the positioning information signal is detected. The timing of rewriting is also determined by this positioning information signal.

At the time of insert editing, a procedure of starting a rewriting operation after completion of tracking from the start of tape running is performed.

[0007]

However, in the conventional example described above, the time required for pulling in the tracking from the start of the tape running at the time of insert editing may be greatly deteriorated in some cases. As described above, in the conventional operation at the time of insert editing, the positioning information signal is detected, and the tracking error is sampled from the tracking signal recording area based on the timing. Since the positioning information signal cannot be read when the tracking error is large, the tracking error cannot be detected in that case,
That is, accurate tracking control was not performed, and the pull-in time was deteriorated.

In this case, the sampling rate is lower than in the case where the tracking error signal is sampled from the entire track as in the case of normal reproduction, that is, the tracking control response frequency has to be lowered. I was

As described above, if the tracking pull-in time during insert editing varies, or if the required time is long, the time from the editing start command to the actual rewriting start varies, or the rewriting is performed before the tracking is completed. Is started. This leads to a deterioration in editing accuracy.

It is an object of the present invention to provide a magnetic recording / reproducing apparatus having excellent editing accuracy by improving the pull-in time during insert editing.

[0011]

In order to solve the above-mentioned problems, a magnetic recording / reproducing apparatus according to the present invention uses a rotating head for scanning.
On an inclined track formed on a magnetic tape, an information signal area for recording a pilot signal for tracking together with an information signal and a tracking signal area for recording a pilot signal for tracking are recorded separately. A rotary head that scans a tape to output a reproduction signal; a tracking error signal detection unit that generates a tracking error signal from the pilot signal included in the reproduction signal; and determines a mode change during insert editing of the information signal. Mode signal generating means for generating a mode signal for performing the operation, sampling timing generating means for generating a sampling timing of the tracking error signal in accordance with the mode signal of the mode signal generating means, and sampling timing of the sampling timing generating means. Sun pudding And equipped with a tape running means for running said magnetic tape in accordance with a tracking error signal, the mode signal of the mode signal generating means, first corresponding to the state from the tape stopped state until the tracking satisfied
And a second mode corresponding to a rewriting execution state of the information signal area. When the mode signal of the mode signal generating means is the first mode, the sampling of the sampling timing generating means is performed. The timing is a timing at which the tracking error is sampled from the entire area on the track, and when the mode signal is in the second mode, the sampling timing is a timing at which the tracking error in the tracking signal area is sampled. The configuration is characterized by the following.

Further, when the mode signal of the mode signal generating means is the first mode, the sampling number of the tracking error per scanning of the rotary head is larger than the sampling number when the mode signal indicates the second mode. The configuration is characterized by many.

[0013]

According to the present invention, in the mode from the start of tape running to the tracking pull-in, a tracking error is detected at an arbitrary timing synchronized with the control signal of the rotary head from the pilot signal recorded on the entire track. I have. Therefore, the control frequency band can be increased by increasing the sampling rate of the tracking error, and the adverse effect due to the fact that the positioning information signal for sampling the tracking error cannot be detected due to the large off-track amount can be removed. The tracking pull-in time can be shortened. Further, at the time of rewriting operation, tracking control can be performed while rewriting part of the information signal by detecting a tracking error from a pilot signal recorded in the tracking signal area.

[0014]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a magnetic recording / reproducing apparatus according to one embodiment of the present invention. In FIG.
1 is a magnetic tape, 2 is a track formed on the magnetic tape 1, and 3a and 3b are rotary heads mounted on cylinders (not shown). The tracks 2 formed on the magnetic tape 1 are recorded separately in a first information signal area 21, a second information signal area 22, and a tracking signal area 23. Further, the positioning information signal 24 is recorded in part or all of the tracking signal area 23. Reference numeral 5 denotes a tape traveling unit, which includes a capstan motor 6, a pinch roller 7, a capstan control circuit 8, and a sample hold circuit 9.
It consists of. 10 is a tracking error detector, 11 is a rotary head controller, 12 is a rotary head 3
a reference signal generator for creating the control reference signals a and 3b. Reference numeral 13 denotes a mode signal generator, which outputs a signal indicating the first mode from the start of tape running during insert editing to the completion of tracking pull-in or the second mode in a rewriting execution state. A sampling timing generator 14 outputs a signal indicating the timing at which the sample and hold circuit 9 samples the tracking error of the tracking error detector 10. Reference numeral 15 denotes a positioning information signal detector, 16 denotes an edit timing generator, and 17 denotes an edit area indicator. Reference numeral 18 denotes a recording signal generator, and reference numeral 19 denotes an edit point changeover switch. The present embodiment is an example in which two tracks are recorded and reproduced almost simultaneously by the 2ch rotating magnetic heads 3a and 3b. FIG. 2 is a diagram showing the arrangement of the rotary head on the cylinder in the present embodiment, and 4 is a cylinder.

FIG. 3 is a diagram showing the configuration of each track shown in FIG. 1. A positioning information signal 24 is recorded in a part of a tracking signal area 23 formed at the head of the track. As this positioning information signal, a relatively high frequency which is hardly affected by an adjacent track is selected. Further, the first information signal area 21 has a video signal and the second information signal area 2
In 2, an audio signal is recorded. Further, a pilot signal for tracking is frequency-multiplexed and recorded over the entire track. This pilot signal is recorded alternately at two different frequencies f1 and f2 every other track, as in the prior art described above.

Next, an operation at the time of insert editing in which an information signal is recorded from above on a track formed as shown in FIG. 3 will be described. In this case, assuming that the tape is in a stop state, a part of the information area signal, that is, the first information signal area or the second information signal area is rewritten from the first mode from the start of the tape running to the completion of the tracking pull-in. To the second mode. The time chart at this time is shown in FIG. FIG. 4A shows the tape running speed, which starts running at time ta in the drawing. Thereafter, the speed pull-in is completed at time tb. FIG. 4B shows a tracking error. When the polarity of the tracking error is positive (+), the position of the rotary head is off-track toward the preceding track from the target track. Tracking error polarity is negative (-)
When it is off-track in the opposite direction. Here, the tracking error becomes almost zero at time tc, and the tracking pull-in is completed. FIG. 4C shows a mode signal of the mode signal generator 13. Here, after completion of the tracking pull-in, the mode signal is switched from “L” (low potential state) to “H” (high potential state) at time td. When the mode signal is “L”, the mode is the first mode, and when the mode signal is “H”, the mode is the second mode. Here, the mode signal generator 13 switches the mode signal after judging that the tracking pull-in is completed. However, the method of the judgment deviates from the gist of the present invention, so that the details are omitted.

For example, a method of detecting the tracking error and determining that the pull-in has been completed when the tracking error has been less than a specific value for a certain period of time, or a method of determining the envelope of the reproduced signal by examining the magnitude of the envelope is generally considered. . In addition, if the tracking pull-in time is greatly reduced by the method described below, and the amount of variation can be estimated, the mode signal is switched after the time required from the tape start time ta to the completion of the tracking pull-in has elapsed. There is no particular problem. Next, the operation at that time will be described in detail. First, a common operation in the two modes will be described.

The reference signal generator 12 generates a reference signal of 150 Hz, and the rotary head controller 11 controls the rotary heads 3a and 3b so as to synchronize with the reference signal of the reference signal generator 12.
Controls the rotation speed of the cylinder 4 on which is mounted.

The magnetic tape 1 runs by a capstan motor 6 whose rotation speed is controlled by a capstan control circuit 8 and a pinch roller 7. Further, the capstan control circuit 8 performs tracking control in accordance with a tracking error sampled at a timing described later.

It is assumed that insert editing is started from a state where the tape is stopped. The mode signal of the mode signal generator 13 becomes "L", indicating the first mode. This mode signal is input to the edit timing generator 16. The edit timing signal, which is the output of the edit timing generator 16, is supplied to the edit point switch 19.
Is input to The edit timing signal at this time is “L”
And the edit point changeover switch 19 is connected to the terminal 19b. That is, in the first mode, the tracking error signal can always be detected from the reproduction signals from the rotary heads 3a and 3b.

At this time, the mode signal of the mode signal generator 13 is also input to the sampling timing generator 14. In the sampling timing generator 14, the sample and hold circuit 9 outputs a sampling timing signal indicating the timing at which the tracking error of the tracking error detector 10 is sampled. The sampling timing signal is such that the mode signal of the mode signal generator 13 is "
L ”is synchronized with the reference signal of the reference signal generator 12.

FIG. 5 is a time chart of the sampling timing signal of the sampling timing generator 14 at this time. Inside the sampling timing generator 14, a built-in timer is activated at the same time as the input of the reference signal to perform time management and determine the output timing of the sampling timing signal. Here, the sample and hold circuit 9 samples the tracking error of the tracking error detector 10 at the timing of the rising edge of the sampling timing signal, and the rotating heads 3a and 3
b shows a case where sampling is performed six times while scanning each track.

Tracking control is performed based on the tracking error sampled at the timing determined as described above.

Now, it is assumed that the tracking pull-in is completed. The mode signal of the mode signal generator 13 is "
H "indicates the second mode. A method of generating the sampling timing signal of the sampling timing generator 14 and the editing timing signal of the editing timing generator 16 at this time will be described with reference to FIGS. Outputs from the heads 3a and 3b are input to a positioning information signal detector 15 separately from the tracking error detector 10. The frequency of the positioning information signal 24 recorded in the tracking signal area 23 is determined by the positioning information signal detector. Fifteen
And the positioning information signal detector 15
A pulse signal indicating the position of the positioning signal is generated as shown in FIG. This pulse signal is first input to the sampling timing generator 14. The sampling timing generator 14 receives a pulse signal and operates a built-in timer to generate a sampling timing signal as shown in FIG. 7C after a specified delay time t1 has elapsed.

The tracking error of the tracking error detector 10 is sampled by the sample and hold circuit 9 at the timing of the rising edge of the sampling timing signal. The sampled tracking error signal is input to the capstan control circuit 8, and performs tracking control between the rotary head 3a and a track to be reproduced. Next, the pulse signal from the positioning information signal detector 15 is separately input to the edit timing generator 16.
In order to rewrite each information area, the start position and the end position of the area to be rewritten must be designated. However, the edit timing generator 16 receives an edit area instruction signal from the edit area indicator 17, The delay time t2 of the first delay circuit 16a and the delay time t3 of the second delay circuit 16b shown in FIG. 6 are designated based on this signal.

The delay pulse signal of each delay circuit is generated by counting a clock built in the magnetic recording / reproducing apparatus. Then, those signals are converted to RS FF16c.
6 as shown in FIG. 6, an edit timing signal as shown in FIG. 7D is generated. In this case, the timing is for rewriting the first information signal area.
This edit timing signal is sent to the edit point changeover switch 19.
Only when the edit timing signal is "H", the edit point changeover switch 19 is
a, and a new information signal is applied to the rotary head 3a. In this case, the information signal recorded in the first information signal area 21 is rewritten to a new information signal. The edit point changeover switch 19 is switched from the terminal 19b to the terminal 19a by a timing signal generated by the edit timing generator 16, and a new information signal is applied to the rotary head 3a and simultaneously the rotary head 3b.
Also, another new information signal is added by another edit point changeover switch (not shown), so that the information signal recorded in the first information signal area 21 is almost equal to the new information signal with two tracks. Rewritten at the same time. In addition, since the rotary head 3b is disposed very close to the rotary head 3a and can accurately maintain the relative positional relationship with the rotary head 3a, the tracking of the rotary head 3a and the target track enables Tracking with the target track can be achieved at the same time.
Therefore, it is not always necessary to record the positioning information signal on the track scanned by the rotary head 3b among the tracks recorded two by two. Although the case of rewriting the first information signal area has been described with reference to FIG. 7, the operation of rewriting other areas is almost the same.

As described above, during the insert editing, from the start of the tape running to the tracking pull-in, the tracking error signal is sampled at an arbitrary timing synchronized with the rotation reference signal of the rotary head, and the tracking control is performed. . As described above, the positioning information signal is recorded at a relatively high frequency which is hardly affected by the next track, but cannot be detected unless the tracking pull-in is completed, and therefore a tracking error cannot be detected. Would.
This leads to significant deterioration of the tracking pull-in time. Thus, until the tracking pull-in is completed, sampling is performed at an arbitrary timing synchronized with the rotation reference signal of the rotary head as described above, and if tracking control is performed, the tracking pull-in time can be reduced.

Further, by increasing the sampling rate of the tracking error (6 times in the present embodiment) as described above until the pull-in is completed, the response frequency of the tracking control can be set high.
Therefore, the tracking pull-in time can be reduced. In the present embodiment, the sampling frequency of the tracking error signal in the first mode is 900 Hz, and the sampling frequency of the tracking error signal in the second mode is 150 Hz. The optimum tracking control band in each case is determined by the entire control system of the capstan motor 6, but it is obvious that the higher the sampling frequency, the higher the control band can be set. FIG. 8 is a diagram showing the tracking pull-in characteristic when the tracking control band is changed. FIG. 8A shows a speed error, and FIG. 8B shows a tracking error. In the figure, A is a case where the tracking control band is doubled as compared with B. FIG.
In the case of A and B in (b), if the time until the tracking error becomes substantially zero, that is, the tracking pull-in time is compared, the tracking control band is clearly 2
It can be seen that in the case of the doubled A, the retraction is completed in a shorter time. Therefore, the effect of increasing the sampling rate of the tracking error signal in order to reduce the tracking pull-in time is significant.

Although the present embodiment has been described with reference to the case of simultaneous recording on two channels, the combination and arrangement of the rotary heads are not limited to the present embodiment, but can be applied to other cases.

In this embodiment, two types of tracking pilot signals are shown.
Pilot signals of four kinds of frequencies as used in R may be used.

Further, in this embodiment, the case where the tracking pilot signal is recorded after being frequency-multiplexed is described. However, the recording method is not limited to this, and a digital pilot method may be used in digital recording.

In this embodiment, the case where only one tracking signal area is provided at the head of the track is shown, but the position and the number are not limited.

Further, in this embodiment, the information signal is 2
Although the case of the type is shown, the number is not limited, and for example, in addition to the video signal and the audio signal, an index signal may be provided in an area and recorded.

[0034]

As is apparent from the above description, according to the present invention, it is possible to greatly reduce the variation in the time from the tape running stop state to the tracking pull-in at the time of insert editing, and to greatly reduce the pull-in time. Since the length can be shortened, it is possible to realize a magnetic recording / reproducing apparatus in which editing accuracy is significantly improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a magnetic recording and reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a layout view of a rotary head on a cylinder in an embodiment of the present invention.

FIG. 3 is a configuration diagram of a recording track in one embodiment of the present invention.

FIG. 4 is a time chart at the time of insert editing in the embodiment of the present invention.

FIG. 5 is a time chart of a sampling timing signal in a first mode in the embodiment of the present invention.

FIG. 6 is an internal detailed diagram of an edit timing generation circuit in one embodiment of the present invention.

FIG. 7 is a time chart of each signal in the second mode in the embodiment of the present invention.

FIG. 8 is a diagram showing an example of a tracking pull-in characteristic.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic tape 2 Track 3a, 3b Rotating head 4 Cylinder 5 Tape running device 6 Capstan motor 7 Pinch roller 8 Capstan control circuit 9 Sample hold circuit 10 Tracking error signal detector 11 Rotating head controller 12 Reference signal generator 13 Mode Signal generator 14 Sampling timing generator 15 Positioning information signal detector 16 Editing timing generator 17 Editing area indicator 18 Recording signal generator 19 Editing point changeover switch 21 First information signal area 22 Second information signal area 23 Tracking Signal area 24 Positioning information signal

Continued on the front page (72) Inventor Haruo Isaka 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-59-75451 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G11B 15/467

Claims (2)

(57) [Claims] 1. An information signal area for recording a tracking pilot signal together with an information signal on an inclined track formed on a magnetic tape by scanning of a rotary head, and a tracking signal area for recording a tracking pilot signal. A rotating head that scans the tape and outputs a playback signal, a tracking error signal detection unit that creates a tracking error signal from the pilot signal included in the playback signal, and the information signal. A mode signal generating means for generating a mode signal for determining a mode change at the time of insert editing, and a sampling timing generating means for generating a sampling timing of the tracking error signal according to a mode signal of the mode signal generating means, The sampling timing generation means Tape running means for running the magnetic tape in accordance with the tracking error signal sampled at the pulling timing, wherein the mode signal of the mode signal generating means is a first signal corresponding to a state from the tape stop state to the tracking establishment. And a second mode corresponding to a rewriting execution state of the information signal area. When the mode signal of the mode signal generating means is the first mode, the sampling timing of the sampling timing generating means is determined. Is a timing for sampling the tracking error from the entire area on the track, and when the mode signal is in the second mode, the sampling timing is a timing for sampling a tracking error in the tracking signal area. Characterized by Magnetic recording and reproducing apparatus. 2. The method according to claim 1, wherein the mode signal of the mode signal generation means is a first
2. The magnetic recording / reproducing apparatus according to claim 1, wherein the number of samplings of the tracking error per one scanning of the rotary head in the mode is larger than the number of samplings when the mode signal indicates the second mode.