JPH01213854A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To stabilize a regenerative signal at the time of a high speed reproducing by providing a tape feeding speed detecting means relative to a head rotating speed and controlling a capstan rotating speed in response to an output of the detecting means. CONSTITUTION:An RF signal regenerated by magnetic heads HA and HB is supplied to a signal processing circuit 21, where a decoding processing is performed to regenerate various data. At the same time that a regenerated frame address is latched by a first latch circuit 22, a frame address of the previous period which has been latched in the first latch circuit 22 is latched again by the following latch circuit 23, and two latch outputs are compared by a digital comparator 24, and a speed control signal is supplied via a capstan servo drive circuit 15 to a capstan motor 16, so that when the number of tracks crossed in the period is few, the tape feeding speed is to be faster, and when the number of crossed tracks is numerous, the tape speed is to be slower, and hence the rotating speed of a rotary drum 3 and the feeding speed of the magnetic tape 2 are fixed in a prescribed relation.

Description

Detailed Description of the Invention [Industrial Application Field] This invention relates to a rotary head type digital audio tape recorder (R -DAT
), and the like.

[Prior Art] In recording and reproducing devices such as low-rehead digital audio chip recorders (R-DAT), speeds of n times the normal playback speed are used for cue (fast-forward playback), review (rewind playback), etc. In the high-speed playback mode in which tracks are played back at a certain speed, as shown in FIG. 4, the tracks are played back with a trajectory different from the normal playback track trajectory.

Such devices usually employ an azimuth recording method to increase the recording density, and as shown in Figure 4, when the +azimuth track is set as TA and the -azimuth track is set as TB, a straight line is recorded in fast forward mode. (As shown by the scanning trajectory of la, in the rewind mode, as shown by the scanning trajectory of the straight line ub, the +azimuth track TA and -azimuth track TB are moved n-1 times per rotation in the fast forward mode, and n-1 times in the rewind mode. Then, you will straddle it n+1 times.

The envelope of the reproduction output from the reproduction head at this time is as shown in FIG. That is, when the azimuths of the tracks through which the reproducing head passes are the same, the reproduction output becomes large, and when the azimuths are reversed, the reproduction level of high frequency components in particular drops significantly due to the azimuth loss.

As a result, as shown in FIG. 5, during reverse azimuth regeneration, the regeneration level drops significantly and regeneration becomes impossible.

[Problems to be Solved by the Invention] Incidentally, in the above-mentioned R-DAT, signals are reproduced using reproduction outputs obtained from the same azimuth during high-speed reproduction such as cue and review modes.

The tape feeding speed (usually the number of revolutions of the capstan motor) during printing is normally controlled by switching a preset control voltage using a switch circuit.

Also, the tape feeding speed at that time was relatively low;
Normally, the same settings are made for the two modes, cue and review.

However, as mentioned above, the number of times the tracks are crossed per rotation is different in cue mode and review mode, so
The optimal tape feed speed to achieve higher speed cue and review mode may differ.

Furthermore, R-DAT has a mode of 1.5 times the track pitch for pre-recorded tape, but in that case it is desirable to independently set the optimum tape feed speed for the cue and review modes.

On the other hand, in a device such as a 1/2-inch VTR (β, VH3) that has a control track exclusively for tracking, the reproduction (No. 3 frequency) can be used as a detection signal for the tape feed speed.

However, in the case of R-DAT, as is well known, it does not have a control track dedicated to tracking, and the tracking operation is performed using an ATF (Automatic Tractor) that is divided into areas on the same track as the PCM data area.
ck Finding) area.

Therefore, the operation of the ATF area is suitable only for tracking during normal 1x playback, and it is difficult or impossible to detect the current tracking state using this during high-speed playback.

Therefore, the current situation in conventional systems is to reproduce signals that are accidentally read during high-speed reproduction.

As described above, with the conventional configuration, it has not been possible to sufficiently stabilize the reproduced signal during high-speed reproduction to a level that is audibly satisfying.

Therefore, the present invention solves these conventional problems with a simple structure, and is particularly intended for recording and reproducing apparatuses that do not have a dedicated control track for tracking, such as R-DAT. And,
The present invention proposes a recording and reproducing device that can stably reproduce signals even during WJ speed replay.

[Technical Means for Solving the Problems 1] In order to solve the above-mentioned problems, in the present invention, in a recording/reproducing apparatus using a rotating magnetic head that does not have a control track dedicated to tracking, tape feed is adjusted according to the rotational speed of the head. The present invention is characterized in that a speed detection means is provided, and the tape feeding speed is controlled by controlling the rotational speed of the capstan in accordance with the detection output of the speed detection means.

[Function] The tape feeding speed detection means for the head rotational phase can detect a deviation in the tape feeding speed with respect to the head rotational speed.

By controlling the rotational speed of the capstan according to the detected output, the tape feeding speed is controlled.

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

If the tape feed rate relative to the head rotation speed can be fixed as desired, then the number of times the head straddles the track per revolution can be kept constant.

[Example] Next, an example of the recording/reproducing device according to the present invention will be described as an R-DA.
The application to T will be described in detail with reference to FIG. 1 and subsequent figures.

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

Now, let us say that the number of blocks that can be reproduced with a magnetic head with the same recording azimuth as the number of readable blocks, and conversely, the number of blocks that can be reproduced with a magnetic head with the opposite azimuth as the number of unreadable blocks. Further, the repetition period of the number of readable blocks and the number of unreadable blocks is defined as a noise bar period.

As described above, during high-speed playback, the head alternately straddles the same azimuth track and the opposite azimuth track, so the relationship between the tape speed in the tape running direction and the number of blocks is as shown in FIG. 2.

However, it is assumed that the drum rotation speed is constant and the track length is sufficiently long. Further, if the track radius is 13.6 μm and the gap width of the head is 20.4 μm, and the magnetic head hits the track by 7 μm or more, this is counted as a readable block.

n is the running speed of the tape (multiple speed number), and the steady playback speed is assumed to be n=1.

In this way, if the phase relationship between the head rotational phase and the tape feeding phase can be fixed, the relationship between the readable block position (and unreadable block position) and the head rotational phase can be fixed. .

Further, when a readable block is represented by a high level and an unreadable block is represented by a low level, at even speed, the values are as shown in FIGS. 3C and 3E.

As shown in G, the output of the +azimuth magnetic head HA and the output of the -azimuth magnetic head HB are symmetrical.

On the other hand, at odd-numbered speeds, B, D, and F in the same figure.

The pattern is the same as shown in H.

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

As is clear from FIG. 2, the fast-forward mode at N times the normal playback speed corresponds to the rewind mode at N-2 times the normal playback speed.

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

In other words, the recording format of the PCM area is as shown in Figure 3A.
As shown in the figure, a Q code for error correction is placed in the middle, and even samples are placed in the first half and odd samples in the second half.
This is because even if either half is missing, it can be reproduced by interpolation.

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

In this way, by appropriately fixing the tape feeding speed relative to the head rotational speed and further adjusting the phase relationship between the two, half of the PCM area can always be read out as a readable block as described above.

In order to fix the speed relationship between the two, it is sufficient to detect the tape feeding speed relative to the rotational speed of the head and control the capstan speed based on this.

In order to detect the tape feeding speed relative to the rotational speed of the head, it is possible to use a frame address added to recording data.

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

A magnetic tape 2 unwound from a cassette 1 is wound around a rotating drum 3 over predetermined ranges through a tape path as shown.

The magnetic tape 2 is attached to the capstan 4 by the pinch roller 5.
By pressing the magnetic tape 2 against the magnetic tape 2, a predetermined running force is applied to the magnetic tape 2.

A pair of magnetic heads HA and HB provided on the rotating tram 3
The reproduced RF signal is supplied to the signal processing circuit 21, where it undergoes demodulation processing, decoding processing such as error detection and correction, and various data are reproduced. In this example, signal processing is completed in cycles of one frame time during normal playback, that is, the time it takes for the drum to rotate once.In particular, regarding frame address processing, the first frame address read during the processing cycle is used. The frame address is set to be the frame address of that period.

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 had been latched in the first stage latch circuit 22, is transferred to the second stage latch circuit 22.
is relatched.

The two latch outputs are compared in a digital comparator 24, and it is possible to calculate how many tracks are crossed during a period.

When the number of tracks spanned is small, a speed-side aII signal for increasing the tape feeding speed is supplied to the capstan drive motor 16 via the capstan servo drive circuit 15.

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

Through such speed control, the rotational speed of the drum 3 and the tape feeding speed are fixed to have a predetermined relationship.

The number of stages of latch circuits used is not limited to two stages.

As the number of stages increases, speed control accuracy improves.

[Effects of the Invention] As explained above, according to the configuration of the present invention, a tape feed speed detection means for the head rotation speed is provided,
Since the rotational speed of the capstan is controlled in accordance with the detected output, the relationship between the rotational speed of the drum and the tape feeding speed can be regulated as desired.

By regulating the speed relationship as desired, it is possible to achieve a suitable high-speed reproduction speed, and by roughly regulating the phase relationship, it is possible to read a predetermined block on the scanning trajectory of the magnetic head with respect to the tape. It can now be used as a playback block, and stabilization of the played music signal can be achieved.

Therefore, the recording/reproducing apparatus according to the present invention is extremely suitable for application 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 explanation of the drawing]

FIG. 1 is a system diagram of main parts showing an example of the case where the recording/reproducing apparatus according to the present invention is applied to R-DAT, FIG. 2 is a diagram showing the relationship between the number of readable blocks and the number of unreadable blocks, and FIG. FIG. 3 is a waveform diagram for explaining changes in read blocks with respect to reproduction speed, FIG. 4 is a diagram showing a head trajectory 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... Later stage latch circuit 24 ...Digital comparator

Claims (2)

[Claims] (1) In a recording/reproducing device using a rotating magnetic head that does not have a dedicated control track for tracking, a means for detecting the tape feed speed relative to the head rotation speed is provided, and the rotation speed of the capstan is controlled in accordance with the detected output. A recording and reproducing device characterized in that a tape feeding speed is controlled by. (2) The recording/reproducing apparatus according to claim 1, wherein a frame address in a reproduced signal is used as the signal supplied to the detection means.