JPH07114040B2 - Recording / playback device - Google Patents

Description

The present invention relates to a rotary head type digital audio tape recorder (R-DAT) for stabilizing a reproduction signal in a high speed reproduction mode such as a cue or review mode. ) And the like, the present invention relates to a recording / reproducing apparatus suitable for such applications.

[Prior Art] In a recording / reproducing device such as a rotary head type digital audio tape recorder (R-DAT), a speed n times as fast as a regular reproducing speed such as cue (fast forward reproduction) and review (rewind reproduction). In the high-speed reproduction mode in which the reproduction is performed, the reproduction is performed with a locus different from the normal reproduction track locus, as shown in FIG.

In such an apparatus, the azimuth recording method is usually adopted to increase the recording density. When the + azimuth track is TA and the −azimuth track is TB as shown in FIG. As shown by the scanning locus of la, in the rewinding mode, as shown by the scanning locus of the straight line lb, + azimuth track TA and −azimuth track TB are n−1 times in the fast-forward mode per revolution, and in the rewinding mode. You will straddle n + 1 times.

The envelope of the reproduction output from the reproducing head at this time is as shown in FIG. That is, when the azimuth of the tracks passed by the reproducing head is the same, the reproduction output is large, and in the case of the reverse azimuth, the reproduction level of the high frequency component is remarkably lowered due to the azimuth loss.

As a result, as shown in FIG. 5, during reverse azimuth reproduction, the reproduction level is remarkably lowered and reproduction becomes impossible.

[Problems to be Solved by the Invention] By the way, in the above-described R-DAT, a signal is reproduced by using a reproduction output obtained from the same azimuth during high-speed reproduction such as cue and review modes.

Then, the control of the tape feeding speed (usually the rotation speed of the capstan motor) at that time is usually obtained by switching a preset control voltage by a switch circuit.

Also, the tape feeding speed at that time is relatively low,
Normally, the same settings are made for the two modes of queue and review.

However, as mentioned above, the number of crossing tracks for one rotation is different in cue mode and review mode.
The optimum tape feed speed for realizing the queue and review mode at a higher speed may differ.

Also, there is a mode in which the track pitch is 1.5 times for the R-DAT because of the pre-recorded tape. In that case, it is desirable to independently set the optimum tape feeding speed in the cue and review modes.

On the other hand, in devices with control tracks dedicated to tracking, such as 1/2 inch VTR (β, VHS),
The frequency of the reproduction signal can be used as a tape feed speed detection signal.

However, as is well known, the R-DAT does not have a control track dedicated to tracking, and the tracking operation is based on an ATF (Automatic Track Finding) area provided on the same track as the PCM data area by area division.

Therefore, the operation in the ATF area works well only in the tracking during the normal 1 × speed reproduction, and it is difficult or impossible to detect the current tracking state using the ATF area during the high speed reproduction.

Therefore, in the conventional system, a signal that can be read accidentally is reproduced at the time of high-speed reproduction.

As described above, in the conventional configuration, the reproduction signal at the time of high-speed reproduction cannot be sufficiently stabilized to the extent that it is audibly satisfactory.

In view of the above, the present invention is to solve the above-mentioned conventional problems with a simple structure, and is particularly directed to a recording / reproducing apparatus which does not have a dedicated control track for tracking such as R-DAT. Therefore, the present invention proposes a recording / reproducing device capable of stably reproducing a signal even at high speed reproduction.

[Technical Means for Solving the Problem] According to the present invention, in a recording / reproducing apparatus using a rotary magnetic head having no control track dedicated to tracking, the tape speed is detected by using a frame address included in a reproduced signal. And a tape feed speed control means for controlling the tape feed speed with respect to the rotation speed of the rotary magnetic head based on the output obtained from the tape feed speed detection means. It has a comparison means for comparing two frame addresses obtained from the reproduction signals separated from each other by one rotation cycle to obtain a comparative output corresponding to the tape speed, and is N times the steady speed (7 ≦ N ≦) in the cue mode. 11), the ratio from the above comparison means should be (N-2) times the steady speed in the review mode. By controlling the tape feed speed control means based on the comparison output, the data of the PCM main area of at least one of the first half or the second half of the PCM main area included in the reproduction signal at the time of high speed reproduction. It is characterized in that it can always read.

[Operation] The tape feed speed detecting means for the head rotation phase detects the deviation of the tape feed speed from the head rotation speed.

The tape feeding speed is controlled by controlling the rotation speed of the capstan according to the detected output.

As the signal supplied to the detecting means, a signal related to the frame address in the reproduced signal can be used.

The tape feed speed relative to the head rotation speed is N (7 ≤ N ≤ 11) in the cue mode and (N-
If the control can be performed so as to be 2), the number of times the head crosses over the track per one rotation can be made constant at all times. As a result, the data in the PCM main area in either the first half or the second half of the PCM main area can be read out at all times.

[Embodiment] Next, an example of a recording / reproducing apparatus according to the present invention will be described in R-DAT.
The case applied to the above will be described in detail with reference to FIG.

For convenience of description, first, the relationship between the head rotation speed and the tape feeding speed will be described with reference to FIGS. 2 and 3.

Now, the number of blocks that can be reproduced by the same magnetic head as the recording azimuth is the number of readable blocks, and conversely, the number of blocks that are reproduced by the magnetic head of reverse azimuth is the number of unreadable blocks. Further, a repeating cycle of the number of readable blocks and the number of unreadable blocks is a noise bar cycle.

As described above, at the time of high-speed reproduction, the head alternately runs over the same azimuth track and the reverse azimuth track, so the relationship between the tape speed and the number of blocks in the tape running direction is as shown in FIG.

However, the drum rotation speed is selected in relation to the multiple at the time of steady reproduction, and the track length is sufficiently long. Further, if the track width is 13.6 μm, the head gap width is 20.4 mm, and the magnetic head hits the track by 7 μm or more, this is counted as a readable block.

n is the running speed (double speed number) of the tape, and the steady playback speed is n = 1.

In this way, when the phase relationship between the head rotation phase and the tape feed phase can be fixed, the relationship between the readable block position (and unreadable block position) and the head rotation phase can be fixed. .

When the readable block is represented by a high level and the unreadable block is represented by a low level, as shown in FIGS. 3C, E, and G in FIG. Output and-Azimuth magnetic head
The output of HB is symmetrical.

On the other hand, at odd-numbered speeds, the patterns are the same as shown in B, D, F, H of the same figure.

FIG. A shows an example of a track pattern standardized in R-DAT, in which L and R signals are recorded in PCM. A frame address, a block address, etc. exist in this PCM area.

As is clear from FIG. 2, the fast-forward mode and the steady playback speed N times N times the steady playback speed (7 ≦ N ≦ 11).
It corresponds to the -2 times rewind mode.

As is apparent from FIGS. 2 and 3, when an appropriate tape speed is selected, at least half of the PCM area can be always reproduced as a readable block by the magnetic heads HA and HB.

That is, as shown in FIG. 3A, the recording format of the PCM area has a Q code for error correction in the middle and even samples in the first half and odd samples in the latter half, so even if either half is missing. This is because it can be reproduced by interpolation.

In this example, the tape speed is 9x in fast-forward mode,
The rewind mode is set to be 7 times speed.

In this way, by controlling the tape feed speed relative to the head rotation speed as desired and adjusting the phase relationship between the two, it is possible to always read half of the PCM area as a readable block as described above.

In order to fix the speed relationship between the two, the tape feed speed relative to the head rotation speed may be detected and the capstan speed control may be performed based on this.

The frame address added to the recording data is used to detect the tape feed speed relative to the head rotation speed.

The embodiment shown in FIG. 1 is a specific example.

The magnetic tape 2 delivered from the cassette 1 is wound around the rotary drum 3 over a predetermined range through a tape path as shown in the figure.

The magnetic tape 2 is capstaned by the pinch roller 5.
A predetermined running force is applied to the magnetic tape 2 by pressing the magnetic tape 2 onto the magnetic tape 2.

The RF signal reproduced by the pair of magnetic heads HA and HB provided on the rotating drum 3 is supplied to the signal processing circuit 21,
Various types of data are reproduced by performing decoding processing such as demodulation processing and error detection and correction. In this example, the signal processing is completed with one frame time at the time of normal reproduction, that is, one drum rotation time as a cycle, and particularly with respect to the processing of the frame address, the frame address read first in the processing cycle is set as the cycle. Frame address.

After the signal processing is completed, the reproduced frame address is supplied to the first stage latch circuit 22 and latched. At the same time, the frame address of the previous cycle, which has been latched by the latch circuit 22 of the first stage until then, is re-latched by the latch circuit 23 of the latter stage.

The two latch outputs are compared in a digital comparator 24 to calculate how many tracks were crossed during the period.

Then, when the number of tracks crossed is small, a speed control signal for increasing the tape feeding speed is transmitted via the capstan servo drive circuit 15 to the capstan drive motor 16
Is supplied to.

On the contrary, when the number of tracks straddled is large, a speed control signal for slowing the tape speed is transmitted via the capstan servo drive circuit 15 to the capstan drive motor 16
Is supplied to.

By such speed control, the rotation speed of the drum 3 and the tape feeding speed are fixed so as to have a predetermined relationship.

The number of stages of latch circuits used is not limited to two. The speed control accuracy is improved as the number of stages is increased.

[Effects of the Invention] As described above, according to the configuration of the present invention, the tape feed speed detecting means for detecting the tape speed by using the frame address in the reproduction signal, and the rotary magnetic head based on the tape feeding speed detecting means. A tape feed speed control means for controlling the tape feed speed with respect to the rotation speed is provided so that at least one of the first half and the second half of the PCM main area in the reproduction signal during high-speed reproduction can be always read. Since the tape feed speed controlled based on the reproduction frame address is set to the steady speed N (7 ≦ N ≦ 11) in the cue mode and (N−2) in the review mode, The relationship between the tape feeding speed and the rotation speed can be regulated as expected.

By controlling the speed relationship as expected, a suitable high-speed reproduction speed can be achieved, and by controlling the phase relationship, a predetermined block on the scanning track of the magnetic head with respect to the tape can be read. As a result, the stabilization of the reproduced music signal can be achieved.

Therefore, the recording / reproducing apparatus according to the present invention is extremely suitable for being applied to a recording / reproducing apparatus such as an R-DAT which does not have a control track and therefore does not have a linear track that can be used for speed detection.

[Brief description of drawings]

FIG. 1 is a system diagram of an essential part showing an example in which a recording / reproducing apparatus according to the present invention is applied to an R-DAT, and FIG. 2 is a diagram showing a relationship between the number of readable blocks and the number of unreadable blocks,
FIG. 3 is a waveform diagram for explaining a change state of the reading block with respect to the reproduction speed, FIG. 4 is a diagram showing a head locus during high speed reproduction, and FIG. 5 is a waveform diagram of a reproduction signal. 2 ... Magnetic tape 3 ... Rotating drum 4 ... Capstan drive motor 15 ... Drive circuit 21 ... Signal processing circuit 22 ... First stage latch circuit 23 ... Second stage latch circuit 24 ... Digital comparator

Claims (1)

[Claims] 1. In a recording / reproducing apparatus using a rotary magnetic head having no control track dedicated to tracking, a tape feeding speed detecting means for detecting a tape speed by using a frame address included in a reproducing signal, and this detecting means. A tape feed speed control means for controlling the tape feed speed relative to the rotation speed of the rotary magnetic head based on the output obtained from It has a comparison means for comparing two obtained frame addresses to obtain a comparison output corresponding to the tape speed, which is N times (7 ≦ N ≦ 11) of the steady speed in the cue mode and ( N-2) times the tape feed speed control means based on the comparison output from the comparison means. It is characterized in that the data in the PCM main area of at least one of the first half and the second half of the PCM main area included in the reproduced signal can be always read during high-speed reproduction by being controlled. Recording / playback device.