JPS6378362A - Rotary head type digital audio reproducing device - Google Patents

Abstract

PURPOSE:To check a bent track simply with accuracy to some degree by using a 2nd support means outputting a capstan servo control signal at the non-check mode as a means outputting the capstan servo control signal at the check mode setting. CONSTITUTION:A level difference of the crosstalk of pilot signals at both adjacent tracks is held in a S/H circuit 17 in the ATF area of each track of the standard tape at each generation f a sampling signal SPA at the check mode and the result is outputted as a check signal. A level difference of the crosstalk of pilot signals of both adjacent tracks in the ATF region of the midpoint of each track is held in a S/H circuit 16 by using a sampling signal SP2 and an ATF error signal is fed to a capstan servo to take the tracking at the reproduction of the standard tape. Thus, a bent track is checked by displaying the output of the S/H circuit 17.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention converts an audio signal into a PCM signal, and reproduces the digital signal recorded by a rotating head as one diagonal track on a recording medium for each unit of time. The present invention relates to a rotary head type digital audio playback device suitable for playing.

[Technical background of the invention and its problems]

A device that records audio signals on a magnetic tape by forming one diagonal track every unit time using a helical scan type rotary head, and when reproducing the audio signals, converts the audio signals into PCM and records and reproduces them. There is a device called R-DAT (rotating head digital audio tape recorder), which is considered as a rotary head digital audio tape recorder.

The format of the track actually recorded on R-DAT is the pattern shown in Figure 5 (al), and the frequency of each of MARGIN, PLL, and PO3 TAMBLE is 1/2 fs (fM = 9.4 MHz), I
The frequency of BG is 1/6f, 4. The SOB and PCM are composed of blocks as shown in FIG. 5(b). 5YNC is 10 bits (fixed at 9 bits), and the remaining bits have various patterns depending on the location, audio signal, etc. In the case of SUB, there are 8 blocks, and in the case of PCM, there are 128 blocks. Note that the numerical values in fal in FIG. 5 represent the number of blocks occupied by each area.

The ATFI and ATF2 areas located between 5UB-1 and PCM and between PCM and 5UB-2 (ATF
: Automatic Track Findin
g) is for making it possible to perform tracking control so that the rotary head correctly scans the recording track during reproduction using the output of the rotary head without providing a special head.

In other words, the A T F jlI area is used to compress the time axis of a PCM signal and record the track diagonally on a magnetic tape using two rotary heads without a guard band. A tracking pilot signal is recorded in a separate recording area from the PCM signal in the part, and during playback, the recording track is scanned by a rotating head whose scanning width is wider than the track width, and the rotating head tracks the track being scanned. The reproduced output of pilot signals from both adjacent tracks is used to control the tracking of the rotary head.

Then, the track pattern for this ATF is the first one.
As shown in Figure 3, the pattern shown is a drum diameter of 30 mm, a drum winding angle of 90'', and a rotation speed of 20 mm.
The case of 00 rpm will be explained.

ATFl and A in the front and rear parts of each track
TF2 is a low frequency signal f that is a biloft signal for tracking and has little azimuth effect.

This is used to detect the level of crosstalk from both adjacent tracks during playback, and to obtain the level difference between the crosstalk components of both adjacent tracks as a tracking error signal. A low frequency signal of f/72 (130 KHz) is used as the pilot signal f.

ATF-1 and ATF-2 also have a pilot signal f.
A sync signal for determining the position where , is recorded is recorded. Since it is difficult to distinguish between on-track and adjacent tracks when there is crosstalk in the sync signal, a sync signal is selected that has a frequency with an azimuth effect and a pattern that does not exist in the PCM signal. The sync signals are different from each other in order to distinguish between the A head and the B head, with the head corresponding to +azimuth being A1 and the head corresponding to -azimuth being B, and the frequency f for the A head. ', 4/18 (=522KHz) sink 1
The signal f2 has a frequency fH/12 (
=784KHz) sync 2 signal f3 is recorded at each predetermined position.

The R-DAT is not provided with an erasing head, and signals are rewritten by overwriting the previous recording, so-called override. Therefore, an erasure signal f4 of frequency fM/6 (=1.56 MHz) is recorded at a predetermined position for erasing the pilot signal II, sync 1 signal f2, and sync 2 signal fY of the previous recording.

The positions of the ATF pilot signals are all different between the on-track and both adjacent tracks, and the level of the on-track pilot signal and the level of the pyloft signal of both adjacent tracks are different in time, and three types of levels are sampled. It is arranged so that you can

Five blocks are allocated to each ATF area of ATF-1 and ATF-2, and pilot signals f are recorded in two of the blocks. Sink signals f2, f3
is recorded using one block or 0.5 block from the center of the position where one adjacent track is recorded. The biloft signal f of the other adjacent track is recorded so that its center is located two blocks after the beginning of the sync signal recorded on the on-track. 1 block of sync signals are assigned to odd frames, and 0.5 blocks of sync signals are assigned to even frames.

As mentioned above, 1. In ATF, the frequency of the sync signal differs depending on the A head and the node to B, and the recording length of the sync signal differs between odd and even frames. Therefore, all four consecutive tracks are given different ATFs, so that they can be distinguished. A as mentioned above
The TF pattern is a 4-track complete type that is repeated every 4 tracks.

By the way, when a magnetic tape recorded in the format shown in FIG. 5fa) is reproduced by a rotary head, an RF multiplied signal as shown in FIG. 7(a) is obtained from the rotary head. For example, if this RF multiplied signal is obtained by reproducing the odd-numbered frame track (A) in FIG.
By passing it through a KHz band pass filter (BP F), a pilot signal f1 as shown in (1)) is obtained.

Section I is due to on-track pilot signals, and sections ■ and ■ are due to crosstalk between pilot signals of (B) odd frame tracks and (B) even frame tracks. When the rotating head is scanning correctly on the track, the envelope levels of sections ■ and ■, that is, ■■ and ■■ in (C) should be equal, but if there is a track deviation, ■■ ≠V■,
The amount and direction of deviation of the rotary head from on-track can be determined by its magnitude and polarity. Therefore, by operating the capstan servo and finely adjusting the tape speed based on the difference between v■ and v■, it becomes possible to run the rotary head on-track.

In the above-mentioned R-DAT, at the final stage of manufacturing, it is necessary to check track curvature and make adjustments so that predetermined recording and reproduction characteristics can be obtained. Track bending refers to the phenomenon in which the running trajectory of the rotating head on the tape is bent.It occurs when there is a deviation in the tape path system or capstan servo system, so based on this check, the tape path system or capstan servo system should be By adjusting the system, it is possible to obtain a device with stable characteristics and less track bending.

This track curvature can be roughly determined by the reproduced RF multiplied signal, but this method cannot be used to check very accurately. Another method is to actually develop the tape recorded with each device and actually measure the bending of the developed tape, but this method is very time consuming and labor intensive, and also requires a lot of effort. It cannot be applied to playback-only devices that do not have

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a rotary head type digital audio device that allows track curvature to be checked easily and with a certain degree of accuracy.

[Summary of the invention]

A check mode setting means is provided which is operated only when performing a check in an adjustment stage during manufacturing, and a first holding means is provided which operates only when the check mode is set by the means and outputs a measurement signal, and a non-check mode is provided. The second holding means for outputting a capstan servo control signal in the check mode can also be used as a means for outputting a capstan servo control signal when the check mode is set;
To easily check track curvature with a certain degree of accuracy.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotary head type digital audio reproducing apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the apparatus of the present invention. In the figure, 11 is a 130 KHz band pass filter (BPF), and its input receives RF multiplied signals from two rotating heads (not shown). .

is entered. The RF multiplied signal includes PCM data, subcode data, pilot signal for ATF, sync signal, etc., and 130KHzBPFII uses this R
It works to pass only the 130 KHz viroft signal component from the F signal.

The pilot signal component obtained at the output of the 130 KHz BPF 11 consists of a biloft signal component of the track being scanned by each rotary head and a crosstalk component of the pilot signals on both adjacent tracks adjacent to the track.

The pilot signal component output from the 130 KHz BPF 11 is input to an envelope detector 12. The envelope detector 12 envelope-detects the pilot signal component, converts it into a DC signal of a magnitude corresponding to its level, and outputs the signal. D output from the envelope detector 12
The C signal is supplied to a first sample and hold (S/H) circuit 13 and a differential amplifier 14 .

The S/H circuit 13 samples and holds the DC signal from the envelope detector 12 using a sampling signal SP1, which will be described later, input from the timing generation circuit I5 to the C input, and supplies this to the manual input of the differential amplifier 14. The differential amplifier 14 takes the difference between the DC signal applied from the envelope detector 12 and the DC signal applied manually from the S/H circuit 13, and sends this to the second S/H circuit.
The signal is supplied to the H circuit 16 and the third S/H circuit 17.

The S/H circuit 16 samples and holds the difference signal from the differential amplifier 14 using a sampling signal SP2, which will be described later, input from the timing generation circuit 15 to its C input, and outputs this as an ATF error signal. The S/H circuit 17 samples and holds the difference signal from the differential amplifier 14 using a sampling signal SPA, which will be described later, input from the timing generation circuit 15 to its C input, and outputs this as a check signal.

The ATF error signal is supplied to a capstan servo in a device (not shown) and is used to track the rotary head with respect to the track on the tape. On the other hand, the check signal is supplied to a display device, an oscilloscope, etc., and is used to check track curvature.

The above RF multiplied signal is also input to BPF18, and the BPF1
8 allows only the sync signal component in the RF signal to pass through and is supplied to the sync detection circuit 19.

When the sync detection circuit 19 detects a sync signal from the sync signal component that has passed through the BPF 18, it sends out a detection pulse to its output, and supplies this to the timing generation circuit 15.

A timing generation mode switching signal is input to the timing generation circuit 15, which becomes H in the non-check mode and L when the switch 20 is turned on in the check mode by operating a mode selection switch (not shown) provided in a position not visible from the outside of the device. The sampling signals SPI and SP2 are output at appropriate timings depending on the mode.
and generate SPA. In addition, the timing generation circuit 15
The operable period is controlled only in the non-check mode by a signal from the system counter 21.

That is, in the non-check mode, as shown in the timing chart of FIG. At an intermediate point in time when the DC signal of the crosstalk component is input to the S/H circuit 13, the sampling signal SPI
occurs. This sampling signal SPI is generated in response to a detection pulse generated when the sync detection circuit 19 detects a sync signal (not shown) recorded on the on-track to indicate the position of the pilot signal of the preceding adjacent track. It will be done. The timing pulse generation circuit 15 also
A sampling signal SP2 is generated two blocks after the generation of the sampling signal SPI.

On the other hand, in the check mode, the erase signal f4 and AT are applied to each track over its entire length as shown in FIG.
By loading a standard check tape with a length of about 30 seconds to 1 minute on which the F Si area is recorded alternately into the device and playing it back, the timing generation circuit 15 generates the timing as shown in FIG. Sampling signal SPI, SP
Generates 2.

The sampling signal SPI is generated in response to the detection of the sync signal in the ATF 6N range, and the sampling signal SP
A is generated two blocks after the sampling signal SPI is generated, and the sampling signal SP2 is the sampling signal S in the ATF area located approximately at the center of the track.
It is generated in synchronization with the generation of PA.

As described above, in the non-check mode, the S/H circuit 13
What is sampled and held in the S/H circuit 16 is the DC level of the crosstalk of the pilot signal of one of the preceding adjacent tracks, and what is sampled and held in the S/H circuit 16 is the DC level difference of the crosstalk between the two adjacent tracks. It comes to be output as an ATF error signal.

In this mode, nothing is held in the S/H circuit 17 and no check signal is output.

On the other hand, in the check mode, the S/H circuit 17' inputs the ATF? of each track of the standard tape every time the sampling signal SPA is generated. In the tI region, the crosstalk level difference between the pilot signals of both adjacent tracks is held, and this is output as a check signal in the form shown in FIG. 4(D). By displaying changes in this check signal on, for example, an oscilloscope, it becomes possible to visually recognize the state of track curvature. and S
In the /H circuit 16, the crosstalk level difference between the pilot signals of both adjacent tracks is held in the ATF area at the middle position of each track by the sampling signal SP2, and this is held in the ATF area as shown in FIG. 4(E). Output as an error signal. This ATF error signal is supplied to the capstan servo for tracking during playback of the standard tape.

In addition, in the check and check modes, the sampling signal S
It is also possible to generate P2 in the ATF area at the beginning and end of each track, and to perform tracking at two points on each track.

With the above configuration, standard tapes can be played back and S/H
By displaying the check signal of the output of the circuit 17, track bending can be carried out easily and with a certain degree of accuracy without using any other equipment.

〔effect〕

As described above, according to the present invention, track curvature can be checked simply and with a certain degree of accuracy by using means that is pre-installed in the device, without requiring any troublesome work.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a rotary head type digital audio playback device according to the present invention, FIG. 2 is a timing chart showing waveforms of various parts in FIG. 1 in non-check mode, and FIG. Figure 4 is a diagram showing the track pattern of the standard tape for checking. Figure 4 is a timing chart diagram showing the waveforms of each part of Figure 1 in check mode. Figure 5 is R.
- An explanatory diagram showing the track format and block format of the DAT, FIG. 6 is an explanatory diagram showing the ATF track pattern of the R-DAT, and FIG. 7 is an explanatory diagram showing the ATF track pattern of the R-DAT.
FIG. 2 is an explanatory diagram illustrating the principle of trunking using track patterns. 13.16.17...Sample hold (S/H
) circuit, 15... timing generation circuit, 19... sink detection circuit, 20... switch.

Claims (1)

[Claims] Each of a plurality of diagonal tracks is provided with a digital signal, a pilot signal consisting of a frequency signal with little azimuth effect, and a tracking signal having a sync signal indicating the position of the pilot signal of the preceding adjacent track. The signal on a recording medium recorded in a predetermined format with independent recording areas in the longitudinal direction of the track is reproduced by at least two rotary heads, and the reproduced signal from each rotary head is used to reproduce the signal from the preceding one. Rotary head type digital audio in which capstan servo control is performed using a level difference signal between the crosstalk of the pilot signal of an adjacent track and the subsequent crosstalk of the pilot signal of the other adjacent track, so that each rotary head scans over the track. In the playback device, a check mode setting means for setting a check mode; and a first circuit for holding a crosstalk level difference between pilot signals of both adjacent tracks each time the tracking signal is inputted and outputting it as a measurement signal when the check mode is set. and a holding means for controlling the crosstalk level difference between the pilot signals of both adjacent tracks each time the tracking signal is input in the non-check mode according to the tracking signal input at a predetermined timing when the check mode is set. and a second holding means for holding a crosstalk level difference between pilot signals of both adjacent tracks and outputting the held level difference as a capstan servo control signal. Digital audio playback device.