JP2610928B2 - Digital signal recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type digital signal recording / reproducing apparatus using a rotary head, and more particularly, to reducing the drum diameter of the rotary head to reduce the size of the apparatus. The present invention also relates to a digital signal recording / reproducing apparatus in which the tape format remains constant.

[Conventional technology]

As a device of this type, a device called a rotary head digital audio tape recorder (R-DAT) has recently been commercialized. In the R-DAT, as shown in FIG. 10, a track length L, an angle θ when two heads of different azimuths provided on a rotating drum run on a magnetic tape T at a predetermined tape speed v. And the pitch P are standardized as a tape format. If the standard is satisfied, the rotational speed R of the rotating drum, the drum diameter D, and the tape winding angle α can be set freely. I have.

The initial products are recommended values to satisfy the above-mentioned standards, that is, the rotation speed R is 2000 rpm and the drum diameter D is 30 m.
m, and the tape wrap angle α was generally 90 °, but recently, in order to reduce the size of the device, the drum diameter D was set to 15 mm and the tape wrap angle α was set to 180 °. And a rotational speed R of 2000 rpm have been proposed.

FIG. 3 is a diagram showing an example of a general circuit configuration of the above-described proposed device. The device includes a mechanism unit 1, a radio frequency (RF) unit 2, an ATF
(Automatic Track Finding) processing unit 3, PLL (Phase La
and a signal processing unit 6, an audio signal unit 7, and a system control unit 8.

In the above-described apparatus, at the time of recording, an unnecessary high-frequency component is removed from the analog signal input to the analog signal input terminal 9 by the low-pass filter (LPF) 71 in the audio signal unit 7. The output of the LPF 71 is provided to an A / D converter 72, where it is converted to a digital signal. The digital signal from the audio signal unit 7 is input to the PCM subcode encoding circuit 61 of the signal processing unit 6. The PCM subcode encoding circuit 61 interleaves the PC data with respect to the data once stored in the RAM 65, generates and adds a correction code and adds a subcode, and then controls the RAM control unit 64. Then, it is stored in the RAM 65 again. The output of the RAM 65 is converted by the 8/10 converter 62 and input to the recording amplifier 21 of the RF unit 2. In the RF unit 2, when the REC control signal from the system control unit 8 is "H", the changeover switch 23
The recording data from the recording amplifier 21 is supplied to the heads 11a and 11b via the switch 23 in order to record the data on the magnetic tape T. The heads 11a and 11b are provided on the rotating drum 11, and perform recording and reproduction of a tape.

At the time of reproduction, the reproduction data read by the heads 11a and 11b is transmitted via the changeover switch 23 to the reproduction amplifier of the RF unit 2.
Entered in 22. The output of the reproduction amplifier 22 is input to the PLL circuit 41 of the PLL section 4, where the period is detected and the reproduction data (PBDATA) and the reproduction clock (PBCK) are divided. PBDA
TA is input together with PBCK to the 8/10 demodulator 67 of the signal processing unit 6 and demodulated, and the output is input to the RAM 65 and stored in the data order under the control of the RAM control unit 64. RAM65
Is connected to a PCM subcode decoding circuit 66, which deinterleaves the data stored in the RAM 65 and performs error correction. The output of the circuit 66 is input to the D / A converter 73 of the audio signal unit 7, is converted into an analog signal, and is input to the LPF 74, where unnecessary high frequency components are removed and output from the analog signal output terminal 10.

The signal processing unit 6 is provided with a fixed frequency generator 63 for generating various fixed frequencies such as ATF.
The frequency signal generated in step (1) is recorded at a predetermined position on the magnetic tape by switching the changeover switch 68 at a predetermined timing.

The rotation of the rotating drum 11, the capstan 12, the supply reel 13 and the take-up reel 14 of the mechanism unit 1 is controlled by servo control. For this reason, a frequency generator (FG) 11c and a pulse generator are generated for the rotating drum 11. Vessel (PG), FG 12a to capstan 12, and reels 13 and 14
Are provided with FGs 13a and 14a, respectively. FG11
The outputs of c and PG11d are supplied to the drum servo circuit 51 of the servo section 5.
The reference signal from the reference signal generator 54 and the P from the PLL unit 4
A phase servo is applied to a drum motor (not shown) so that a recording and reproduction operation can be performed when the heads 11a and 11b are in contact with the tape T and are input together with the BCK. The output of the FG 12a is input to the capstan servo circuit 52 of the servo unit 5 together with the reference signal from the reference signal generator 54 and the error signal indicating the amount of track deviation from the ATF processing unit 3, and the capstan driving the capstan 12 is performed. Servo controls a stun motor (not shown). The outputs of the FGs 13a and 14a are input to a reel servo unit 53 of the servo unit 5 together with a reference signal from a reference signal generator 54, and servo-control a reel motor (not shown) for driving the reels 13 and 14.

In the illustrated example, the drum diameter D is 15 mm and the tape winding angle α is
180 °, the drum 11 rotates at 2000 rpm for both recording and playback in SP mode, and 1000 rpm for both recording and playback in LP mode.
The reference signal is input from the reference signal generator 54 to the drum servo circuit 51 so as to rotate.

The capstan servo circuit 52 has a tape speed v of 8.15 mm / sec in SP mode recording, and a tape speed v in LP mode recording.
A reference signal to be 4.075 mm / sec is input.
At the time of reproduction, the tape feed is controlled so that the track shift amount is detected based on the signal recorded in both the SP mode and the LP mode, and the recorded track is traced.

The automatic control of the track trace during this playback is ATF (Aut
Omatic Track Finding), by inputting the reproduction signal to the digital section 31 of the ATF processing section 3, detects a sync signal from the reproduction signal and samples the sample pulse SP1 and the sample pulse SP1 for sampling the track shift amount of both adjacent tracks. Output SP2. This is input to the analog section 32 of the ATF processing section 3, and the difference between the track shift amounts of both adjacent tracks is detected.
This is used as a tracking control signal at the time of reproduction.

The reel servo circuit 53 is mainly used for the mechanical unit 1 during the search operation.
Supply reel 13 FG 13a and take-up reel 14 F
By controlling the square of the sum of the FG periods of G14a to be constant, control is performed so that the tape feeding speed is constant.

The system controller (system controller) 81 of the system controller 8 controls reading and writing of the subcode signal, and the mechanism controller (mechanical controller) 82 controls the mechanism 1.

The operation of the above configuration will be described in more detail with reference to the timing chart of FIG.

In the SP mode, recording and reproduction are performed by rotating the rotary drum 11 at 2000 rpm. Therefore, as shown in FIG.
11b, the pulse generator 11d generates a switching signal SWP having a period of 30 msec as shown in FIG. 11 (a).

At the time of recording, the REC signal is "H" as shown in FIG.
Thus, the PCM data is completed on two tracks, and one track is composed of two tracks A and B, and the same frame address is added to both tracks. Since the PCM data must be processed and recorded within 30 msec, the recording data (REC DATA) is always recorded as shown in FIG. 11 (c) because the cycle of the switching signal SWP is 30 msec. become.

The A / D data output from the A / D converter 72 is written into the RAM 65 for 30 msec of A ₀ and B ₀ of the switching signal SWP as shown in FIG. 11 (b), and is interleaved, C ₁ and C _2. After the addition, the data is read from the RAM 65 during the period A ₁ and B ₁ of one rotation of the rotating drum.

In the REC DATA of FIG. 11 (c), a signal of a fixed frequency required for the DAT format, such as an ATF sync signal and a pilot signal, is inserted at a predetermined timing by switching the changeover switch 68, and is continuously recorded on the tape.

On the other hand, during reproduction, the REC signal is at the “L” level as shown in FIG. 11 (e), and the reproduced high-frequency signal (PBRF) has a continuous waveform as shown in FIG. 11 (f). This PB
The reproduction clock (PBCK) is extracted from the RF in the PLL unit 4 as shown in FIG. 11 (g), and only the subcode and the PCM unit are reproduced data (PBDATA) as shown in FIG. 11 (h).
Is written to the RAM 65.

Since the reading of the D / A data from the RAM 65 for the D / A conversion by the D / A converter 73 is also performed sequentially at the same frame address, it is performed in units of 30 msec as shown in FIG. 11 (i).

Here, the tracking at the time of reproduction is performed based on the sample pulses SP1 and SP2 shown in FIGS. 11 (j) and (k) which are generated by the digital section 31 of the ATF processing section 3 detecting the ATF sync pattern from the PBRF. Is performed by sampling the track shift amount of both adjacent tracks.

Drum diameter 15mm, wrapping angle α180 °, 2 in SP mode
In the case of 000 rpm and 1000 rpm in the LP mode, at the time of recording / reproducing, the rotating drum 11 rotates as the time t progresses, and the tape T runs at a predetermined speed. Fig. 12 shows tracks and B tracks (during playback)
Can be traced as shown in the figure, and there is no problem in the trace.

[Problems to be solved by the invention]

However, in the above-described conventional apparatus, in the LP mode, the tape speed v must be halved and the number of rotations of the drum must be halved. The RF signal obtained in the mode is as shown in FIGS. 13 (a) and 13 (b). On the other hand, when the drum diameter D is set to 15 mm for miniaturization, the SP mode and the LP
The RF signals in the mode are as shown in FIGS. 14 (a) and (b), respectively.

As can be seen from the comparison between the two, when the drum diameter D is 15 mm, the relative speed between the tape and the head in the LP mode is reduced to one fourth of that in the SP mode of the recommended example.
Problems such as a decrease in signal level and an increase in error rate occur.

To solve such problems, increase the rotation speed of the rotating drum, for example, 4000 rpm in SP mode, 2000 rpm in LP mode.
By doing so, the relative speed between the tape and the head may be increased, but this causes another problem that each head cannot trace the corresponding track.

Therefore, the present invention provides the same tape format obtained when a rotating drum having two heads provided opposite to each other at the same height is rotated at a predetermined rotation speed, at a rotation speed N times the predetermined rotation speed. An object of the present invention is to provide a digital signal recording / reproducing apparatus which can be obtained even when a rotating drum is rotated.

[Means for solving the problem]

In order to solve the above-mentioned problems, an apparatus made according to the present invention has a structure in which a diameter of a rotating drum having two heads provided opposite to each other at the same height is D, a winding angle of a recording medium around the rotating drum is α, A track having a length L, a track angle θ, and a track pitch P obtained when the drum is rotated at a predetermined rotation speed is rotated at N times the predetermined rotation speed. In a helical scan type digital signal recording / reproducing apparatus, the height of one of the two heads is set to (1
−1 / N) While providing a step by raising P, the other head is positioned from the position facing one head. (C is a constant determined by the product of the drum diameter D and the wrapping angle α).

(Operation)

Generally, a helical scan R-type using a rotating drum having two heads provided opposite to each other at the same height.
In the DAT, the product of the diameter D of the rotating drum and the winding angle α of the magnetic data as a recording medium for the rotating drum is made constant,
In addition, when the rotating drum is rotated at a predetermined rotation speed, a tape format having a predetermined value of the track length L, the track angle θ, and the track pitch P is obtained as shown in FIG.
For example, in the case of recording, when the head A starts tracing from the point a of the track A, the head B following the head A starts tracing from the point c of the track B.

Assuming that the distance between the points a and c at this time is d, the relationship with the track pitch P is P = d sin θ.

On the other hand, when the rotating drum is rotated at N times (N ≧ 1) the predetermined number of rotations when the format shown in FIG. 1 is obtained, the B head coming after the A head is not at the point c of the B track. It comes to point b. Therefore, the B head cannot trace the B track.

In order for the B head to trace on the B track, the height of the B head may be made higher than the A head by ΔP in the figure. This ΔP increases as the multiple increases, and 1
Since it approaches 0 as it approaches, ΔP = (1-1 / N) · P. Therefore, if the number of rotations of the rotating drum is doubled, By raising the B head by a half track pitch, the B head comes to be on the B track.

However, when the B head is raised by ΔP, the trace start point of the B head comes to the point e, and is shifted from the point c of the B track by ΔL. In order to set the trace start point of the shifted B head to the point c, the position of the B head may be shifted by an angle β corresponding to ΔL. This ΔL is represented by ΔL = ΔP / tan θ. The winding angle α of the rotating drum and the track length are in a comparative relationship, and β / α = ΔL / L ∴β = ΔL · α / L holds, and D · α = C (= 30 × 90 ° = 9 constants) ∴α = C / D, so Becomes

In the above configuration, by increasing the height of one head by (1-1 / N) P with respect to the other head,
When the number of rotations of the rotating head is set to N times the predetermined number of rotations, the next head compensates for the deviation in the track pitch direction that traces the tape, and moves the other head from the position facing one head. By mounting at a position delayed by the angle with respect to the rotation direction, the deviation in the track length direction can be compensated, and even if the number of rotations is N times, a predetermined tape format can be obtained, and the error rate can be further improved. Etc. can be improved.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

2A and 2B show an embodiment of the present invention, wherein FIG. 2A is a plan view of the rotary drum 11 with a part thereof removed, FIG. 2B is an X arrow diagram in FIG. It is a Y arrow diagram, in which 11a is an A head, 11b is a B head, 111
The upper drum 111 is fixed to a rotating shaft 112 of a drum motor (not shown) and rotates in accordance with the rotation of the drum motor. The lower drum 113 does not rotate.
And 11b are provided in a predetermined relationship, and the lower drum 113 is provided with an obliquely carved lead 114, along which the tape runs.

The illustrated rotating drum 11 has a drum diameter of 15 mm, and has a drum rotation speed of 4000 rpm in the SP mode.
The height of the B head 11b is increased by a half track pitch (= 6.795 μm) with respect to the head 11a to provide a step, and the B head 11b is placed at a distance of 0.
It is mounted at a position delayed by 465mm in the direction of rotation.

An R-
The circuit configuration of the DAT may be basically the same as that described above with reference to FIG. 3, except that the circuits for generating various timings are slightly different.

In the present embodiment, recording and reproduction are performed with the rotation speed of the rotating drum 11 set to 4000 rpm in the SP mode.
As shown in the figure, the switching signal SWP of the heads 11a and 11b is
5 msec.

Then, at the time of recording, audio data for 30 msec (section of A ₀ , B ₀ , A ₁ , B ₁ ) is stored in the RAM 6 as shown in FIG.
5 and write it to the next 15m as shown in FIG.
sec, that is, R in the section of A ₂ (7.5 msec) and B ₂ (7.5 msec)
It is recorded on the tape T as EC DATA. In the next section A ₃ and B ₃ , even if the head is in contact with the tape T, the REC signal becomes “L” level as shown in FIG.

On the other hand, at the time of reproduction, the REC signal becomes "L" level as shown in FIG. 4 (e), and the PBRF signal becomes as shown in FIG. 4 (f).

From such a PBRF signal, the PB as shown in FIG.
CK is extracted. At this time, using only this PBCK, the data of only the subcode and the PCM part is converted into PB DATA as shown in FIG.
Is written to the RAM 65 by the PB DATA write signal as shown in FIG. The data written in the RAM 65 is read by the D / A DATA read signal in FIG. 4 (i) and sent to the audio signal unit 2. Sample pulse SP1 and S
P2 is generated at the timing shown in FIGS. 4 (j) and (k).

In the LP mode, the rotating drum 11 may be rotated at 2000 rpm for recording and reproduction, and the timing chart is the same as that in the SP mode except that one cycle of SWP is 30 msec. Of course, the tape speed is set to half of the SP mode by the capstan servo circuit 52.

More particularly, when using rotating drum 11 having the above configuration, reproduction (PB) sometimes, as shown in FIG. 5, the next head B after A head is tracing the center of the A ₁ track when it came on the tape T, B head traces the center of the B ₁ track. Although then A head comes on the tape T again, this time A head passes through the center of the B ₁ track, then comes B head passes through the center of the A ₂ heads. When the next A head comes on the tape T, A head A ₂
After passing through the center of the track, the above-described pattern is repeated. As a result, the PBRF signal obtained during reproduction in the SP mode using the rotating drum 11 has a waveform as shown in FIG. In FIG. 5, REC indicates the head position at the time of recording, which is shifted by a quarter of the head width from the case of PB.

In the above-described embodiment, the speed is set to 2000 rpm during the reproduction in the LP mode. However, even if the speed is set to 4000 rpm, there is no problem.

FIG. 7 shows the timing of the waveform of each part when the tape recorded at 2000 rpm is reproduced at 4000 rpm in the LP mode, and the SWP signal has a period of 15 mse as shown in FIG. 7 (a).
c, and the PBRF signal waveform is as shown in FIG. 7 (b). In particular, when playing at 4000rpm using a rotary drum 11 of the structure described above the recorded tape in LP mode, as shown in FIG. 8, after playing A ₁ track in the A head, then comes B head B ₁ track is reproduced by. Thereafter, when the A and B heads come on the tape for the fourth time, the same reproduction as in the first time is performed, and thereafter, the same pattern is repeated. As a result, an RF signal waveform enlarged in FIG. 9 is obtained.

In the above embodiment, the RF signal can be completely reproduced only once every four rotations of the drum, but the recorded track is completely traced without applying one track as can be seen from FIG. I have.

At this time, as shown in FIG. 7 (d), after reading the data of the sections A ₀ and B ₀ as PB DATA, reading is not performed up to the section A ₄ and B ₄ . The tracking sampling pulses SP1 and SP2 are generated at timings shown in FIGS. 7 (e) and 7 (f).

In this embodiment, since the relative speed between the tape and the head can be made the same in the LP mode as in the SP mode, the effect of increasing the RF signal level can be obtained.

In the above-described embodiment, the case where the present invention is applied to the R-DAT is shown.
It is equally applicable to millimeter video tape recorders and the like.

(Effect)

As described above, according to the present invention, a predetermined tape format can be obtained even when the rotation of the rotary drum is increased by a simple means of changing the configuration of the rotary drum. The playback speed is increased, the playback signal level is increased, and a playback signal with a low error rate can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining the principle of the present invention, FIG. 2 is a diagram showing a configuration of a rotary drum as one embodiment of the present invention, and FIG. 3 is a diagram of an R-DAT to which the present invention is applied. FIG. 4 shows a general circuit configuration, FIG. 4 is a timing chart showing waveforms of respective parts of the apparatus shown in FIG. 3 using the rotary drum shown in FIG. 2, and FIG. 5 uses the rotary drum shown in FIG. FIG. 6 is a waveform diagram showing details of a PBRF signal obtained by the rotating drum of FIG. 2, and FIG. 7 is a diagram of FIG. 3 in another embodiment of the present invention. FIG. 8 is a timing chart showing waveforms of various parts of the apparatus, FIG. 8 is an explanatory diagram showing the relationship between the head and the track of the rotating drum in the embodiment of FIG. 7, and FIG. 9 is details of the PBRF signal in FIG. FIG. 10 is an explanatory diagram for explaining a tape format, and FIG. 11 is a conventional diagram. FIG. 12 is a timing chart showing waveforms of various parts in FIG. 3, FIG. 12 is an explanatory diagram showing the relationship between the head and the track in the example of FIG. 10, and FIGS. 13 and 14 are rotating drums having different drum diameters. FIG. 3 is a waveform diagram showing a PBRF signal waveform in the SP and LP modes, respectively. 11: rotating drum, 11a, 11b: head, T: tape (recording medium), L: track length, θ: track angle, P: track pitch, D: drum diameter, C: constant.

Claims (1)

(57) [Claims] 1. When the diameter of a rotating drum having two heads provided opposite to each other at the same height is D, the wrapping angle of a recording medium around the rotating drum is α, and the rotating drum is rotated at a predetermined rotation speed. A helical scan type digital signal recording / reproducing apparatus in which the obtained tape format, in which the track length is L, the track angle is θ, and the track pitch is P, is rotated at N times the predetermined number of rotations. In the above, the height of the other head is increased by (1-1 / N) P with respect to one of the two heads to provide a step, and the other head is moved from a position facing the one head. (C is a constant determined by the product of the drum diameter D and the winding angle α). The digital signal recording / reproducing apparatus is mounted at a position delayed with respect to the rotation direction by an angle.