JPH0823966B2 - Signal playback device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type signal reproducing apparatus using a rotary drum having a head, and more particularly to a signal reproducing apparatus having a high-speed search function. .

[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. 5, a track length L and an angle θ when two heads of different azimuths provided on a rotating drum travel on a magnetic tape T having a predetermined tape speed v. And the pitch P are standardized as a tape format, and the rotational speed R, the drum diameter D and the tape winding angle α are set so that a tape format satisfying the standard can be obtained.

The initial product is the recommended value to meet the above standard, that is, the rotation speed R is 2000 rpm and the drum diameter D is 30 m.
m, and 90 ° was used as the tape winding angle α, but recently, in order to downsize the device, the drum diameter D was set to 15 mm and the tape winding angle α was set to 180 °. It is proposed that the rotation speed R is 2000 rpm.

In this case, the relative speed between the tape and the head becomes half of that in the recommended example, which causes a problem that the signal level drops and the error rate deteriorates.

Therefore, the applicant of the present application has previously developed a rotating drum capable of reducing the diameter of the rotating drum without decreasing the relative speed of the tape and the head by increasing the number of rotations of the rotating drum to, for example, 4000 rpm in the SP mode. is suggesting.

Generally, a helical scan type R- using a rotary drum having two heads provided facing each other at the same height.
In DAT, the product of the diameter D of the rotating drum and the winding angle α of the magnetic tape as a recording medium for the rotating drum is constant,
Further, when the rotary drum is rotated at a predetermined number of revolutions, a tape format in which the track length L, the track angle θ and the track pitch P are predetermined values 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 N times ((N ≧ 1)) the predetermined number of rotations when the format of FIG. 5 is obtained, the B head following the A head is at the point c of the B track. Instead, it comes to point b. Therefore, B head is B
You will not be able to trace the track.

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

However, if the B head is raised by ΔP, the trace start point of the B head comes to the point e, which is deviated 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 rotary drum and the track length are in a proportional relationship, and β / α = ΔL / L ∴β = ΔL ・ α / L holds, and D ・ α = C (= 30 × 90 ° = Constant) ∴ 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. It is possible to compensate for the deviation in the track length direction by mounting at a position that is delayed by the angle of 1 to the rotation direction.

FIG. 6 shows an example of a rotary head constructed on the basis of the above-described principle, (a) is a plan view of the rotary drum 11 shown with a part thereof removed, (b) is a view on arrow X in (a),
(C) is a Y arrow view in (a), and in the figure,
11a is an A head, 11b is a B head, 111 is an upper drum that is fixed to a rotary shaft 112 of a drum motor (not shown) and that rotates according to the rotation of the drum motor, and 113 is a lower drum that does not rotate. The A heads 11a and 11b are provided in a predetermined relationship, the lower drum 113 is provided with an obliquely engraved lead 114, and the tape is run along this lead.

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 relative to the head 11a is increased by a half track pitch (= 6.795 μm) to form a step, and the B head 11b is moved from the position facing the A head 11a to 0.
It is installed at a position delayed by 465 ° with respect to the rotation direction.

When the rotary drum 11 having the above-mentioned structure is used, during playback (PB), as shown in FIG. 7, when the A head traces the center of the A ₁ track and then the next B head comes onto the tape T. , B head traces the center of 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. Then, when the A head comes on the tape T next time, the A head passes through the center of the A ₂ track,
The above pattern will be repeated thereafter. As a result, the PBRF signal obtained during reproduction in the SP mode using the rotary drum 11 has a waveform as shown in FIG. Incidentally, REC in FIG. 7 indicates the head position at the time of recording, which is deviated by 1/4 head width from the case of PB.

By the way, R-DAT is capable of high-density recording for a long time, and it is very difficult to search for a target song, so at a speed of approximately ± 200 times the tape running speed during playback in SP mode. The tape is run, and the ID (S-
1D), program number (PNO), and time code reading speed information.

[Problems to be Solved by the Invention]

In order to read information during this high-speed search, it is necessary to make the relative speed between the tape and the head the same as during reproduction. The reason is that when the relative speed changes, the frequency band of the read signal changes, and the frequency characteristics of the head, amplifier, and equalizer differ, so the PLL section,
This is because the frequency band of the signal processing unit also needs to be widened accordingly.

The relationship between the search speed and the drum rotation speed is illustrated by the dotted lines a and b in the graph of FIG. The dotted line a indicates that the number of rotations of the drum during recording and reproduction is 4000rp.
In the case of the relative speed corresponding to m, the dotted line b is the case of the relative speed corresponding to 2000 rpm. As you can see from the graph,
At the time of 200x speed search in the FF direction, about 60, which is about 1.5 times that during playback
The rotating drum 11 has to be rotated at 00 rpm.

The rotating drum 11 is driven by a drum motor, and its rotation speed is changed by changing the voltage applied to the drum motor. Therefore, if the rotation speed is changed in a wide range, it is applied to the drum motor. It becomes necessary to change the applied voltage in a wide range. Therefore,
If you try to secure sufficient response of the servo system,
A large power supply voltage is required, which is a serious problem for a battery-powered portable type R-DAT.

Therefore, the present invention is intended to provide a signal reproducing apparatus capable of reducing the upper limit of the rotational speed of the rotary drum during high-speed search as much as possible.

[Means for solving the problem]

In order to solve the above-mentioned problems, a signal reproducing apparatus having a high-speed search function of a helical scan system using a rotating drum having a head made by the present invention is capable of reproducing a signal reproduced at a relative speed in which relative speeds of a tape and a head are different from each other. It is characterized in that it is provided with means for processing each and a function selecting means for performing a search operation at a lower relative speed during a search in the FF direction and at a higher relative speed during a search in the REW direction.

[Action]

With the above configuration, it becomes possible to process signals reproduced at two relative speeds corresponding to, for example, 4000 rpm and 2000 rpm, and the function selection means, for example, based on the graph of FIG. Rotating drum
In order to select the search operation function so that it is the same as the relative speed when performing playback at 2000 rpm, and the same as the relative speed when performing playback at the rotating drum at 4000 rpm during REW direction search. It becomes possible to change the rotation speed of the rotary drum during high-speed search within a narrower range and lower than the conventional one.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a circuit configuration of an R-DAT configured by the present invention using the rotary drum 11 described above with reference to FIG. 6, including a mechanical section 1, a high frequency (RF) section 2, an ATF (Automatic T).
rack finding) processing unit 3, PLL (Phase Lacked Loop) unit 4, servo unit 5, signal processing unit 6, audio signal unit 7,
It is composed of a system control unit 8 and an operation unit 9.

In the above-described device, during recording by operating the REC button 91 of the operation unit 9, the analog signal input to the analog signal input terminal IN has unnecessary high-frequency components removed by the low-pass filter (LPF) 71 in the audio signal unit 7. To be done. LPF71
The output of is given to the A / D converter 72, where it is converted into 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 sub-code encoding circuit 61 once interleaves the PCM data with respect to these data once stored in the RAM 65, generates and adds a correction code, adds a sub-code, and then controls the RAM control unit 64. And it is stored again in RAM65. 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. RF
In part 2, the REC control signal from the system controller 8 is "H".
When the conversion switch 23 is switched to the REC side,
The recording data from the recording amplifier 21 is supplied to the heads 11a and 11b for recording on the magnetic tape T via the switch 23. The heads 11a and 11b are provided on the rotary drum 11 and record / reproduce tape.

During reproduction by operating the PB button 92 of the operation unit 9, the changeover switches 43 and 44 are switched to the REW (SP) side by a signal from the system control unit 8 as shown in the figure. The reproduction data read by the heads 11a and 11b is converted by the conversion switch 23.
Is input to the reproduction amplifier 22 of the RF unit 2 via. The output of the reproduction amplifier 22 is input to the equalizer amplifier 41a of one channel of the PLL unit 4 and equalized and amplified, and then input to the PLL circuit 42a, where period detection is performed and reproduction data (PBDA
It is divided into TA) and reproduction clock (PBCK). PBDATA is
The signal processing unit 6 together with PBCK via the changeover switches 43 and 44.
8/10 demodulator 67 and is demodulated and its output is RAM6
The data is input to 5 and stored in the order of data under the control of the RAM control unit 64. RAM65 has PCM subcode decoding circuit
66 is connected, and the circuit 66 deinterleaves the data stored in the RAM 65 to perform error correction. Circuit 66
The output of is input to the D / A converter 73 of the audio signal unit 7, converted into an analog signal and input to the LPF 74, where unnecessary high frequency components are removed and the analog signal output terminal OUT
Output from

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 by the generator 63 is generated by switching the changeover switch 68 at a predetermined timing. It is inserted and recorded at a predetermined position on the tape.

The rotation of the rotary drum 11, capstan 12, supply reel 13, and take-up reel 14 of the mechanism unit 1 is controlled by servo control, and therefore the frequency generator (FG) 11c and pulse generation are performed on the rotary drum 11. Vessel (PG) 11d
FG12a for capstan 12 and reels 13 and 1
4 are provided with FG 13a and 14a, respectively. FG1
The outputs of 1c and PG11d are the drum servo circuit 5 of the servo unit 5.
1 to the reference signal from the reference signal generator 54 and from the PLL unit 4
It is input together with PBCK, and servo is applied to a drum motor (not shown) so that recording / reproducing operation and search operation can be performed when the heads 11a and 11b are in contact with the tape T.
The output of FG12a is the capstan servo circuit 5 of the servo unit 5.
2, the reference signal from the reference signal generator 54 and the ATF processing unit 3
Is input together with an error signal indicating the amount of track deviation from the servomotor, and servo controls a capstan motor (not shown) that drives the capstan 12. 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
The reference signal is input from the reference signal generator 54 to the drum servo circuit 51 and controlled so that the drum 11 rotates at 4000 rpm for both recording and reproduction.

Also, at the time of 200 times high speed FF search, at about 4000 rpm, 200
In case of double REW high speed search, the reference signal generator 54 and the drum servo circuit 51 should rotate the rotating drum at about 2000 rpm.
The reference signal is input to.

Further, the capstan servo circuit 52 is supplied with a reference signal for making the tape speed v 8.15 mm / sec in recording. At the time of reproduction, the tape feed is controlled so that the track deviation amount is detected by the recorded signal and the recorded track is traced.

The automatic control of the track trace during this playback is ATF (Aut
Omatic Track Finding), a reproduction signal is input to the digital section 31 of the ATF processing section 3 to detect a sync signal from the reproduction signal, and a sample pulse SP1 and a sampling pulse SP1 for sampling the track deviation 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 sum of the squares of the FG periods of G14a to be constant, the tape feed speed is controlled to be a constant value of about 8.15 mm × 200.

The system controller (system controller) 81 of the system controller 8 reads operation signals from the operation unit 9 and reads and writes sub-code signals and generates various control signals based on them. And the servo unit 5 and the like, respectively.

The FS button 93 of the operation unit 9 is for performing a search operation in the FF direction. When the FS button 93 is operated, the system controller 93 is operated.
Reference numeral 81 applies a control signal for forming the FF search operation state to the mechanical section 1 and also the reference signal generator 54 of the servo section 5.
A control signal for generating the reference signal necessary for the search operation in the FF direction is applied to. In response, the reference signal generator 54
According to the point X on the solid line in FIG. 9, the reel servo 53 receives the reference signal necessary for rotating the rotary drum 11 at about 4000 rpm to the drum servo 51 and the tape feed speed is + (8.15 mm × 20).
The reference signals necessary for rotating the supply reel 13 and the take-up reel 14 are applied so that the value becomes 0). At this time, the capstan 12 is replaced by the capstan servo 52.
Servo control is not performed.

In the state as described above, the heads 11a and 1 on the rotary drum 11 are
The signal reproduced in 1b is supplied to the PLL unit 4 via the changeover switch 23 and the reproduction amplifier 22. At this time, the selector switch 43
Since and 44 are in the state shown in the figure, the signal of the 4.7 MHz channel frequency is reproduced from the magnetic tape T being reproduced,
Normal PBDATA is obtained from the PLL unit 4, and normal search operation is performed.

The RS button 94 is for performing a search operation in the REW direction, and when the RS button 94 is operated, the syscon 81 is placed in the mechanical section 1.
A control signal for forming the REW search operation state is applied, and a control signal for generating a reference signal required for the search operation in the REW direction is applied to the reference signal generator 54 of the servo section 5, and further, to the PLL section 4. A control signal for switching the changeover switches 43 and 44 to the REW side is applied. In response to this, the reference signal generator 54 sends the reference signal necessary for rotating the rotary drum 11 to the drum servo circuit 51 at about 2000 rpm to the reel servo 53 according to the point Y on the solid line in FIG. Speed is −
The reference signals necessary to rotate the supply reel 13 and the take-up reel 14 are applied so that the value becomes (8.15 mm × 200). In this state, a 9.4 MHz signal is obtained and a normal search operation is performed.

The MS button 96 is for selecting the program NO recorded on the magnetic tape to be reproduced and for selecting music by high speed search. When the MS button 96 is operated, the system control unit 8 is specified. The program NO is compared with the current program NO, the search direction is determined based on the comparison result, and the search operation is performed in the same manner as when the FS button 93 or RS button 94 is operated thereafter. The reproduction operation is started from the beginning of the music designated by the information about NO and S-ID.

The above operation will be described in more detail with reference to the timing charts of FIGS. First, FS button 93 or MS
The FF search operation is performed by operating the button 96 and the specified S-ID
When the reproducing operation is started by detecting the
In the FF search operation as shown in FIG. 2 (a), the tape speed is +200 times as shown in FIG. 2 (c), the drum speed is about 4000 rpm as shown in FIG. 2 (d), and the PLL
The channel frequency of section 4 is 4. as shown in Fig. 2 (e).
Each is set to 7MHz.

When the S-ID is detected, the tape speed is gradually reduced to 0 and the mechanical unit 1 is stopped. At this time, the channel is switched to the 9.4MHz side. afterwards,
In order to return the tape for the overrun by setting the drum rotation speed to 4000 rpm, the mechanical unit 1 is set to the review (REView) state at the tape speed of -3 times, the S-ID is detected again, and the mechanical unit 1 is reproduced when detected ( PLAY) state. That is, the tape is run at a constant speed by the capstan 12.

As is apparent from FIG. 2, the drum rotation speed is kept at about 4000 rpm during the FF search and does not change, so it is not necessary to pull in the drum servo early during the search transition.

Next, when the REW search operation is performed by the operation of the RS button 94 or the MS button 96 and the reproduction operation is started by the detection of the predetermined S-ID, the mechanical unit 1 moves the REW as shown in FIG. 3 (a). During search operation, tape speed is -200 times speed, drum speed is 2000 rpm, and channel frequency is 9.4 MHz.
Have been each.

Then, when the S-ID is detected, the tape speed is set to 0 and the drum rotation speed is set to 4000 rpm so that the mechanical unit 1 is stopped, and the tape speed and the drum rotation speed are respectively changed accordingly. Gradually change to 0 and 4000 rpm. After that, the mechanical unit 1 is set to the cue (CUE) state, the tape speed is set to +3 times, and the S-ID is detected again after the S-ID is detected again. Enter the playback operation.

As is clear from FIG. 3, the drum rotation speed is 2000 rpm.
And the difference is relatively small only by switching at 4000 rpm.

Finally, when the search operation is performed in the order of FF search → REW search → FF search, the operation described with reference to FIGS. 2 and 3 is only repeated as shown in FIG. 4, and the rotation speed of the drum is 4000 rpm. It can only be switched to any of 2000 rpm.

In the illustrated embodiment, a device having both recording and reproducing functions is described, but the present invention is also effective when applied to a reproduction-only device having only a reproducing function.

Further, in the embodiment, the drum rotation speed is switched between 4000 rpm and 2000 rpm, but the present invention can be effectively applied to the one in which the rotation speed is switched between 2000 rpm and 1000 rpm.

〔effect〕

As described above, according to the present invention, since the rotational speed of the rotary drum during high-speed search is kept low and the range of change is narrowed, good drum rotation servo characteristics can be obtained with a small rotational speed control voltage. In particular, it is effective for a device using a battery as a power source, and the drum servo can be pulled in in a short time during transition of the search operation, so that a device with quick operation switching can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a circuit configuration of an R-DAT showing an embodiment of the present invention, and FIGS. 2 to 4 are timing chart diagrams showing states of respective parts during a search operation of the circuit of FIG. FIG. 5 is an explanatory view for explaining the principle of the rotary head used in the R-DAT of FIG. 1, and FIG. 6 is a diagram showing a specific configuration of the rotary head in FIG. 1, and (a) is A top view, (b) is a view in the direction of arrow X in (a),
(C) is a view from the arrow Y in (a), FIG. 7 is an explanatory view showing the relationship between the head and the track of the rotary drum of FIG. 6, and FIG. 8 is a PBRF signal obtained by the trace of FIG. FIG. 9 is a waveform diagram showing the relationship between P search speed and drum rotation speed. 4 ... PLL part, 41a, 41b ... Equalizer amplifier, 42a, 42b
...... PLL circuit, 43,44 …… Changeover switch.

Claims (1)

[Claims] 1. A signal reproducing apparatus having a helical scan type high-speed search function using a rotary drum having a head, and means for processing signals reproduced at relative speeds in which the relative speeds of a tape and a head are different from each other, A signal reproducing device, comprising: a function selecting unit that performs a search operation at a lower relative speed during a search in the FF direction and at a higher relative speed during a search in the REW direction.