JPH01224975A - Digital signal reproducing device - Google Patents

Abstract

PURPOSE:To lower the upper bound of the number of the revolutions of a rotating drum at the time of a high-speed search by processing signals reproduced at different relative velocities and executing searching operations at a lower relative velocity at the time of an FF directional search and at a higher relative velocity at the time of a REW directional search respectively. CONSTITUTION:The signals reproduced at two relative velocities, which respectively correspond to, for example, 4,000rpm and 2,000rpm, are processed by a signal processing part 6, and a function selecting means 8 respectively selects functions for the searching operations so that each relative velocity at the time of each search can be the same as that at the time of executing each reproduction by making a rotating drum 11 into 2,000rpm, for example, at the FF directional search and making the rotating drum into 4,000rpm at the time of the REW directional search. Thus, the number of the revolutions of the rotating drum at the time of the high-speed search can be lowered.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a helical scan type digital signal reproducing device using a rotating drum having a head, and particularly to a digital signal reproducing device equipped with a high-speed search function. It is.

[Conventional technology]

As this type of device, a device called a rotary head digital audio tape recorder (R-DAT) has recently been commercialized. In R-DAT, as shown in FIG. 5, when two heads with different azimuths provided on a rotating drum run on a magnetic tape T at a predetermined tape speed V, the track length and angle θ are and pitch P are standardized as a tape format, and the rotation speed R of the rotating drum, the drum diameter, and the tape wrapping angle α are set so as to obtain a tape format that satisfies the standards.

Early products generally used the recommended values to satisfy the above standards, that is, 2000 rpm for the rotation speed R, 30 m1 for the drum diameter, and 90° for the tape wrapping angle α, but recently, In order to reduce the size of the device, the drum diameter was set to 1.5 mm and the tape winding angle α was increased.
It has been proposed that the rotational speed R is 180° and the rotational speed R is 200 rpm.

If this is done, the relative speed between the tape and the head will be half of that in the recommended example, resulting in problems such as a drop in signal level and worsening of the error rate.

Therefore, the applicant first increased the rotation speed of the rotating drum,
For example, the authors have proposed a rotating drum in which the diameter of the rotating drum can be reduced without reducing the relative speed between the tape and the head by setting the speed to 400 Orpm in sp mode.

Generally, R-D is a helical scan method that uses a rotating drum with two heads installed at the same height and facing each other.
In AT, the product of the diameter of the rotating drum and the wrapping angle α of the magnetic tape as a recording medium with respect to the rotating drum is constant,
When the rotary drum is rotated at a predetermined number of rotations, a tape format having a track length, track angle θ, and track pitch P of predetermined values as shown in FIG. 5 is obtained.

For example, during recording, when the A head starts tracing from point a on the A track, the B head next to the A head starts tracing from the 0 point on the B track.

If the distance between point a and point C at this time is d, the relationship with track pitch P is as follows: P=dsinθ.

On the other hand, if the rotating drum is rotated at N times (N22) the predetermined number of rotations to obtain the format shown in Figure 5, the B head that follows the head will be at the b point instead of the 0 point on the B track. It starts to come.

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 should be made higher than the B head by ΔP in the figure. This ΔP increases as the multiple increases, and as it approaches 1, it approaches 0, so it is expressed as ΔP=(1-1/N)·P. Therefore, if the rotational speed of the rotary drum is doubled, ΔP = -P, and by raising the B head by 1/2 track pitch, the B head will be placed on the B track.

However, if the B head is raised by ΔP, the trace start point of the B head will come to the 0 point, and will be shifted by Δ from the 0 point of the B track. In order to set the tracing start point of the B head shifted in this way to 0 point, it is sufficient to shift the position of the B head by an angle β corresponding to ΔL. This ΔL is expressed as ΔL=ΔP/lan θ. There is a proportional relationship between the wrapping angle α of the rotating drum and the track length, β/α=ΔL/L,', β=ΔL・α/above, and D・α=C(=30X90°= constant), °, α= C7
Since it is 0, it becomes .

In the above configuration, by increasing the height of one head by (1-1/N) P higher than the other head,
When the number of revolutions of the rotating head is increased to N times the predetermined number of revolutions, the deviation in the track pitch direction of the next head tracing the tape is compensated for, and the other head is delayed in the direction from the position facing one head. By attaching it to the correct position, it becomes possible to compensate for deviations in the track length direction.

FIG. 6 shows an example of a rotary head constructed based on the above-mentioned principle, in which (a) is a plan view of the rotary drum 11 with a portion removed, (b) is a view in the direction of the X arrow in (a), ( C
) is a Y arrow view in (a), and in the figure, 11
a is the A head; Head to A
and llb are provided in a predetermined relationship, and the lower drum 113 is provided with a diagonally carved lead 114, along which the tape is run.

The illustrated rotary drum 11 has a drum diameter of 15 mm, and the height of the B head Ilb is set to 1/2 track pitch (=6 A step is provided by a height of 0.795 μm), and the B head Ilb is mounted at a position delayed from the position facing the A head Ila by 0.465° with respect to the rotational direction.

When using the rotating drum 11 configured as described above, during playback (PB), as shown in FIG.
When the B head comes onto the tape T after tracing the center of the rack, the B head traces the center of the rack. After that, the A head comes back onto the tape T, but at this time, the A head passes through the center of the B1 track, and the next B head passes through the center of the A2 head. Then, when the A head comes onto the tape T, the A head is
It passes through the center of the track and repeats the pattern described above. As a result, this rotating drum 11
The PBRF signal obtained during reproduction in the SP mode using the PBRF has a waveform as shown in FIG. Note that REC in FIG. 7 indicates the head position at the time of recording, which is shifted by a quarter of the head width from that in the case of PB.

By the way, R-DAT is capable of high-density and long-time recording, and it is very difficult to find the desired song, so the tape running speed when playing in SP mode is approximately ±20
The tape runs at 0x speed and indicates the start of the song recorded in the subcode area on both sides of the PCM area.
D (S-ID), program number (PNO),
It has a high-speed search function that reads time code information.

[Problem 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 playback. The reason for this is that when the relative speed changes, the frequency band of the read signal changes and becomes different from the frequency characteristics of the head, amplifier, equalizer, etc.
This is because the frequency band of the signal processing section also needs to be widened accordingly.

The relationship between the search speed and the drum rotation speed is illustrated by dotted lines a and b in the graph of FIG. 9.

Note that the dotted line a indicates that the drum rotation speed during recording and playback is 400 Or
For the relative speed corresponding to pm, the dotted line is 2000 rpm
This is a case of relative velocity corresponding to m. As is clear from the graph, when searching at 200 times the speed in the FF direction, the rotating drum 11 must be rotated at about 600 rpm, which is about 1.5 times the speed during reproduction.

The rotating drum 11 is driven by a drum motor, and its rotation speed can be changed by changing the voltage applied to the drum motor. It becomes necessary to change the voltage applied over a wide range. Therefore,
When trying to ensure sufficient responsiveness of the servo system,
This requires a large power supply voltage, which is a serious problem for portable type R-DATs that use batteries as a power source.

Therefore, it is an object of the present invention to provide a digital signal reproducing device that can lower the upper limit of the rotational speed of the rotating drum during high-speed search as much as possible.

[Means to solve the problem]

In order to solve the above problems, the digital signal reproducing device according to the present invention includes a means for processing signals reproduced at different relative speeds, and a lower relative speed when searching in the FF direction and a higher relative speed when searching in the REW direction. and a function selection means for performing a search operation at a relative speed of one of the two.

[For production]

With the above configuration, for example, 4000rpm, 2000rpm
It is now possible to process signals reproduced at two relative speeds, each corresponding to p-, and the function selection means reproduces the rotating drum at 2000 rpa+ when searching in the FF direction, based on the graph in FIG. When performing a search in the REW direction, the rotating drum is set at 4000 rpm, and the search operation function is selected so that the relative speed is the same as when performing playback. It becomes possible to change the rotational speed of the rotating drum at a lower rate than before and within a very narrow range.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing the circuit configuration of an R-DAT constructed according to the present invention using the rotating drum 11 described above with reference to FIG.
(Automatic Track Finding)
Processing unit 3, PLL (Phase Lacked
It consists of a loop section 4, a servo section 5, a signal processing section 6, an audio signal section 7, a system control section 8, and an operation section 9.

In the above-mentioned device, when recording by operating the REC button 91 of the operation section 9, unnecessary high frequency components are removed from the analog signal input to the analog signal input terminal IN by the low-pass filter (LPF) 71 in the audio signal section 7. be done. The output of the LPF 71 is given to an A/D converter 72, where it is converted into a digital signal. The digital signal from the audio signal section 7 is input to the PCM subcode encoding circuit 61 of the signal processing section 6. - This PCM subcode encoding circuit 61 interleaps the PCM data, generates and adds a correction code, and adds a subcode to the data that has been stored in the RAM 65. It is stored in the RAM 65 again under control. The output of RAM65 is 8/
10 converter 62 and input to the RFF2O recording amplifier 21. RFF2O is R from the system control unit 8.
When the EC control signal is “°H”, the selector switch 23 is set to RE.
The recording data from the recording amplifier 21 is supplied to the heads lla and llb to be recorded on the magnetic tape T via the switch 23. Head Il
A and llb are provided on the rotating drum ll for recording and reproducing the mitave.

During playback when the PB button 92 of the operating section 9 is operated, the changeover switches 43 and 44 are switched to the REW (SP) side as shown in the figure by a signal from the system control section 8.

The playback data read by the heads lla and llb is transferred to the RFF2O playback amplifier 22 via the changeover switch 23.
is input.

The output of the reproduction amplifier 22 is input to the equalizer amplifier 41a of one channel of the PLL section 4, and after being equalized and amplified, it is input to the PLL circuit 42a, where period detection is performed and the reproduction data (PBDATA) and the reproduction clock are input. (PB
CK).

PBDATA is connected to P through changeover switches 43 and 44.
BC, and is manually demodulated by the 8/10 demodulator 67 of the signal processing section 6, and its output is input to the RAM 65 and stored in data order under the control of the RAM control section 64. A PCM subcode decoding circuit 66 is connected to the RAM 65, and the circuit 66 deinterleaves the data stored in the RAM 65 to perform error correction. The output of the circuit 66 is input to the D/A converter 73 of the audio signal section 7, converted to an analog signal, and input to the LPF 74, where unnecessary high frequency components are removed and output from the analog signal output terminal OUT.

The signal processing section 6 is provided with a fixed frequency generator 63 that generates various fixed frequencies such as ATF.
The frequency signal generated in step 3 is inserted and 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, capstan 12, supply reel 13, and pick-up reel 14 of the mechanism part l is controlled by servo control.
1, the frequency generator (FC) llc and pulse generator (PC) lta are connected to the capstan 12, and the FG12 is connected to the capstan 12.
FGs 13a and 14a are provided for the reels 13 and 14, respectively. FGllc and P
The output of Glid is sent to the drum servo circuit 51 of the servo unit 5.
The reference signal from the reference signal generator 54 and the PBCK from the PLL section 4 are input to the head 11a and itb.
A servo is applied to a drum motor (not shown) so that recording/reproducing operations and search operations can be performed when the drum motor (not shown) is in contact with the tape T. The output of the FG 12a is input to the capstan water circuit 52 of the servo unit 5 together with a reference signal from the reference signal generator 54 and an error signal representing the amount of track deviation from the ATF processing unit 3, and drives the capstan 12. Servo-controls a capstan motor (not shown). The outputs of the FGs 13a and 14a are input to the reel servo unit 53 of the servo unit 5 together with a reference signal from a reference signal generator 54, and servo-controls a reel motor (not shown) that drives the reels 13 and 14.

In the illustrated example, the drum diameter is 15 mm and the tape winding angle α
is 180°, and the reference signal generator 54 is used so that the drum 11 rotates at 4000 rpm for both recording and reproduction.
A reference signal is manually input to the drum servo circuit 51 for control.

Also, when performing a 200x high-speed FF search, it takes about 4000rp.
About 200O when performing a 200x REW high-speed search with i.
Reference signal generator 5 to rotate the rotating drum at rpm
A reference signal is input from 4 to the drum servo circuit 51.

Further, a reference signal is inputted to the capstan servo circuit 52 to set the tape speed V to 8.15 mm/sec during recording. During playback, tape feeding is controlled so that the amount of track deviation is detected based on the recorded signal and the recorded track is traced.

This automatic control of track tracing during playback is performed by ATF.
(Automatic Track Finding
), and the reproduced signal is sent to the digital section 3 of the ATF processing section 3.
1, it detects a sync signal from the reproduced signal and outputs sample pulses SPI and SF3 for sampling the amount of track deviation of both adjacent tracks.

This is input to the analog section 32 of the ATF processing section 3, which detects the difference in the amount of track deviation between both adjacent tracks, and uses this as a tracking control signal during playback. 1
By keeping the sum of the squares of the supply reel 130 FG 13a and the FG circumference of the pick-up reel 14 FG 14a constant, the tape feed speed is approximately 8.15 mm.
Control is performed to maintain a constant value of X200.

System controller (syscon) of system control unit 8
Reference numeral 81 reads operation signals from the operation unit 9, reads and writes subcode signals, and generates various control signals based on these, and a mechanism controller (mechanical controller) 82 controls the mechanism unit 1, servo unit 5, etc. It is something.

The FS button 93 of the operation section 9 is for performing a search operation in the FF direction, and when the FSi port 93 is operated, the system controller 81 causes the mechanism section 1 to perform a search operation in the FF direction. A control signal is applied to the reference signal generator 54 of the servo section 5 to generate a reference signal necessary for the search operation in the FF direction. In response, the reference signal generator 54 operates according to point X on the solid line in FIG.
Rotating drum 11 to drum servo 51 at approximately 4000 rpm
The reel servo 53 provides the reference signal necessary for rotation with +.
A reference signal necessary to rotate the supply reel 13 and the pick-up reel 14 so that the tape feeding speed becomes +(8,15 x 200) is applied to each of the supply reel 13 and the pick-up reel 14. At this time, the capstan 12 is not servo-controlled by the capstan servo 52.

The signals reproduced by the heads 11a and llb on the rotating drum 11 in the above-described state are supplied to the PLL section 4 via the changeover switch 23 and the reproduction amplifier 22. At this time, the changeover switches 43 and 44 are in the state shown, so a signal with a channel frequency of 4.7 Mllz is reproduced from the magnetic tape T being reproduced, and the normal PBDATA is
The information is obtained from the L unit 4, and a normal search operation is performed.

The R3 dark blue 94 is for performing a search operation in the REW direction. When the R3 button 94 is operated, the system controller 81 applies a control signal to the mechanism section 1 to form a REW search operation state, and Reference signal generator 54 of servo unit 5
A control signal is applied to generate a reference signal necessary for the search operation in the REW direction, and a changeover switch 4 is applied to the PLL section 4.
A control signal is applied to switch 3 and 44 to the REW side.

In response, the reference signal generator 54 causes the drum servo circuit 51 to control the rotating drum 11 according to point Y on the solid line in FIG.
The reference signal necessary to rotate at approximately 200 rpm is
The reel servo 53 has a tape feed speed of -(8.15mm).
Reference signals necessary to rotate the supply reel 13 and the pick-up reel 14 so that

In this state, a signal of 9.4 Ml(z) is obtained and a normal search operation is performed.

The MSSO96 is for specifying the program number recorded on the magnetic tape to be reproduced and selecting music through high-speed search.When the MS&096 is operated, the system control unit 8 selects the program number recorded on the magnetic tape to be reproduced. The search direction is determined based on the comparison result, and from then on, FSS Ro93. R3
A search operation is performed in the same way as when the button 94 is operated, and the program No. and 5-I obtained by this search operation are
The reproduction operation is started from the beginning of the music specified by the information regarding D.

The above-mentioned operation will be explained in more detail with reference to the timing charts of FIGS. 2 to 4. First, when the FSSO3X performs an FF search operation by operating the MS button 96 and starts a playback operation upon detection of a predetermined 5-ID, when the mechanism section 1 performs an FF search operation as shown in FIG. 2(a), The tape speed was increased to +200 times as shown in Figure 2 (C), and the drum rotation speed was increased to approximately 400 times as shown in Figure 2 (D).
0 rpm, and the PLLLiO2 channel frequency is set to 4.7 MHz, as shown in FIG. 2(e).

When 5-ID is detected, the tape speed is gradually reduced to 0 and the mechanism section 1 is brought to a stop state. At this time, the channel is switched to the 9.4 Mllz side. After that, the drum rotation speed was set to 400° rpm, the mechanism section 1 was set to the REView state at 13 times the tape speed, and the 5-I
D is detected, and when detected, the mechanism section 1 is regenerated (
PLAY) state. That is, the capstan 12 causes the tape to run at a constant speed.

As is clear from FIG. 2, when the FF servo is set at 1000, the drum rotation speed is maintained at about 400 rpm and does not change, so there is no need to pull in the drum servo quickly during the search transition.

Next, when the REW search operation is performed by operating the R3 button 94 or the MS button 96 and the playback operation is started upon detection of a predetermined 5-ID, the mechanism section 1 performs the REW search operation as shown in FIG. 3(a). During the search operation, the tape speed is -200.
The drum rotation speed is set to 2000 rpm, and the channel frequency is set to 9.4 Mtlz.

When 5-ID is detected, the tape speed is set to O so as to stop the mechanism part 1, and the drum rotational speed is set to 400Orpm, and accordingly, the tape speed and drum rotational speed are set to 0 and 0, respectively. 4000rp
Gradually changes to a+. After that, the mechanical unit 1 sends the cue (C
UE) state, the tape speed is increased to +3 times the speed, a 5-ID redetection operation is performed, a REVie- operation is performed, and when a 5-ID is detected in this REVie- operation, a playback operation begins.

As is clear from Figure 3, the drum rotation speed is 2000 r.
The difference is relatively small because it is only switched between pm and 400 rpm.

Finally, when performing search operations in the order of FF search → REW search → FF search, the operations explained in FIGS. 2 and 3 are simply repeated as shown in FIG. It can simply be switched to either 200 Orpm.

Although the illustrated embodiment describes an apparatus having both recording and reproducing functions, the present invention is also effective when applied to a reproducing-only apparatus having only a reproducing function.

Further, in the embodiment, the drum rotation speed is switched between 4000rpm and 200rpm, but the present invention is 2000rpm.
It can also be effectively applied to a device that switches between pm and 1000 rpm+.

〔effect〕

As explained above, according to the present invention, the rotation speed of the rotating drum during high-speed search is kept low and the range of change is narrowed, so that good drum rotation servo characteristics can be obtained with a small rotation speed control voltage. This is particularly effective for devices using batteries as a power source, and the drum servo can be pulled in in a short time during the transition of the search operation, resulting in effects such as a device that can quickly switch operations.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the circuit configuration of an R-DAT showing an embodiment of the present invention; FIGS. 2 to 4 are timing charts showing the state of each part of the circuit in FIG. 1 during a search operation; Fig. 5 is an explanatory diagram explaining the principle of the rotary head used in the R-DAT of Fig. 1, and Fig. 6 is a diagram showing the specific configuration of the rotary head in Fig. 1. Top view, (b) is the X arrow view in (a), (C
) is a Y arrow line view in (a), Figure 7 is an explanatory diagram showing the relationship between the rotating drum head and track in Figure 6, and Figure 8 shows the PBRF signal obtained by tracing in Figure 7. Waveform diagram FIG. 9 is a graph showing the relationship between P search speed and drum rotation speed. 4... PLL section, 41a, 41b... Equalizer amplifier, 42 a, 42 b... PLL circuit, 43
', 44... Selector switch. Patent applicant Pioneer Corporation σ5coD (1)) S-! D Fig. 2 FF Boo-REW/FF Poute Fig. 4

Claims (1)

[Claims] Means for processing signals reproduced at mutually different relative speeds, and a function for performing a search operation at a lower relative speed when searching in the FF direction and at a higher relative speed when searching in the REW direction. A digital signal reproducing device comprising: selection means.