JPH0581980B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to digital audio tape recorders and digital audio tape recorders that digitally record data such as music signals and image signals using magnetic media such as magnetic tapes. This invention relates to a magnetic recording and reproducing device that can be used in tape decks and the like.

<Conventional technology> If the data to be recorded is converted to PCM and digitally recorded, the signal-to-noise ratio will be significantly improved and extremely excellent sound quality will be obtained. It is in the stage of transformation. In this way, data such as music signals and image signals can be converted to PCM.
When recording and reproducing on a magnetic medium,
A digital signal after PCM conversion requires a wider frequency band than an analog signal before PCM conversion due to sampling and the like. In order to record this broadband signal at high density, a rotating head device is used, in which two recording/reproducing magnetic heads are mounted on a rotating drum facing each other at an angle of 180 degrees. A magnetic tape is wound at a predetermined angle with respect to the cross section of a rotating drum within an angle range of 90 degrees, and during recording or playback operation, the rotating drum rotates at a constant rotational speed and the magnetic tape is The tape runs at a speed that is sufficiently slower than the rotational speed of the rotating drum, and has a configuration similar to that of a video tape recorder.

By the way, such digital audio
Similar to normal tape recorders, tape recorders and the like require a function to search for, for example, the song number of a music signal recorded on a tape by fast-forwarding or rewinding the tape at high speed. In this case, if fast-forwarding and rewinding circuits are added in addition to the recording and playback system, the configuration will become extremely complicated, making the device not only large-sized but also expensive. Therefore, the relative speed between the rotary head device and the magnetic tape when the tape runs at high speed during fast forwarding and rewinding is controlled so that it is the same as during normal playback operation.
It has been considered that the circuit configuration of the reproducing system can also be used for processing, and the following two methods have been considered as means for this purpose.

That is, the first means controls the drive voltage to the drum motor of the rotating drum based on the PLL error voltage of a PLL (phase lock loop) circuit, which is directly proportional to the deviation in relative speed between the rotating head device and the magnetic tape. It is something to do. The second method is to reproduce an ATF (auto track finding) pilot signal for tracking recorded at 130 kHz on a track of a magnetic tape during fast forwarding or rewinding, and use the frequency of the reproduced signal to determine whether the magnetic tape is connected to a rotary head device or not. The relative speed with respect to the magnetic tape is detected, and the drive voltage of the drum motor is controlled based on the detected relative speed.

<Problems to be Solved by the Invention> However, both of the above two types of means still have their own problems. That is, in the first means, the PLL error voltage is exactly proportional to the deviation in relative speed between the rotary head device and the magnetic tape only when the PLL circuit is locked; Since the proportional relationship to the relative speed deviation becomes uncertain, e.g.
When the PLL circuit becomes unlocked due to a non-signal section where no data is recorded on the magnetic tape, the PLL circuit is locked by scanning the rotational speed of the rotating drum. I have to search the speed for this.

On the other hand, the second method uses a 130kHz ATF pilot signal detected during fast forwarding or rewinding.
ATF pilot signals in two adjacent tracks alternately recorded by a pair of magnetic heads may interfere with each other, resulting in a frequency signal containing considerable errors. Therefore, in practical use, it is necessary to provide a protection circuit to treat a sudden change in the detection frequency as an erroneous detection. Moreover, when a protection circuit is provided, when the magnetic tape is rapidly running from a stopped state to a fast forward or rewind state,
Since the rotational speed of the rotating drum rapidly increases in accordance with this rapid change in the running speed of the magnetic tape, the above-mentioned protection circuit is activated, resulting in a delay in the rise in the speed of the rotating drum.

If these problems are solved, this magnetic recording/reproducing device will be a great step forward in its practical application.

<Object of the Invention> The present invention was made in view of the above problems, and when the PLL circuit is unlocked,
By controlling the drive voltage of the rotating drum based on the reproduction frequency of the ATF pilot signal,
By excluding the time for the PLL circuit to search for the speed to be locked, and by adding the PLL error voltage to the drive voltage to the rotating drum by the ATF pilot signal when transitioning from stop to fast forward or rewind operation, the drum motor It is an object of the present invention to provide a magnetic recording/reproducing device which prevents a delay in the rise of the magnetic field.

<Means for Solving the Problems> In order to achieve the above object, the magnetic recording and reproducing apparatus of the present invention winds a magnetic tape in an inclined state around a rotating drum equipped with a pair of magnetic heads. In a magnetic recording and reproducing device that digitally records data such as a music signal on a magnetic tape by rotating both magnetic heads, and then reproduces it from the magnetic tape, the reproduction frequency of the ATF pilot signal reproduced from the magnetic tape is detected, and a predetermined frequency is detected. An ATF pilot frequency error detection circuit that calculates the deviation from the
The output signal of this ATF pilot frequency error detection circuit detects the rotational speed of the rotating drum at which the relative speed between the rotating drum and the magnetic tape reaches a predetermined value, and outputs a rotational speed control signal for the drum motor for driving the rotating drum. A drum-tape relative speed calculation circuit, a PLL circuit that operates to lock at the reference frequency of the reproduction signal from the magnetic head, and this PLL.
a subtraction circuit that subtracts the PLL error voltage of the circuit from the rotational speed control signal voltage; and a PLL unlock detection circuit that detects when the PLL circuit is unlocked and blocks input of the PLL error voltage to the subtraction circuit. The present invention is characterized by a configuration comprising the following.

<Function> When transitioning from playback to fast forward or rewind, the rotational speed of the rotating drum changes to follow the rapid change in the running speed of the magnetic tape, reads the playback frequency of the ATF pilot signal, and adjusts the speed of the rotating drum. A protection circuit of the control system that controls the rotational speed of the drum motor is activated due to the deviation of the relative speed with the magnetic tape from the time of playback, but a subtraction circuit extracts the PLL from the rotational speed control signal voltage of the rotational speed control system.
Subtract the error voltage. Since this PLL error voltage is directly proportional to the deviation of the relative speed during playback, the drum motor can control the rotational speed without delay by following the rapid change in the running speed of the magnetic tape, thereby keeping the relative speed constant. can be kept.

Also, if the PLL circuit becomes unlocked,
The input of the PLL error voltage to the subtraction circuit is cut off by the PLL unlock circuit, and the drum motor is controlled only by the reproduction frequency of the ATF pilot signal, so there is no need to search for the speed at which the PLL circuit locks.

<Example> Hereinafter, preferred examples of the present invention will be described in detail based on the drawings.

Since the magnetic recording/reproducing device according to the present invention is a new and highly accurate type of device, an outline of this type of device will first be explained to facilitate its understanding. As mentioned above, when converting data such as music signals into PCM and recording and reproducing them on a magnetic medium, a wide frequency band is required. In order to record such broadband signals at high density, a rotary head device 1 as shown in FIG. 3 is used. That is, the figure shows a plan view of the rotary head device 1, in which two recording/reproducing magnetic heads 3A and 3B are arranged on the rotary drum 2, facing each other at an angle of 180 degrees, and are different from each other with respect to the rotation axis of the rotary drum 2. A magnetic tape 4 as a magnetic medium is mounted on the rotating drum 2 at an azimuth angle between a supply reel 5 and a take-up reel 6 by a pair of inclined posts 7 and 8. It is wound in a state inclined at a predetermined angle with respect to the cross section of No. 2. The rotating drum 2 rotates in the direction of the arrow B at a constant rotational speed during recording and reproduction, and the magnetic tape 4 runs in the direction of the arrow C at a tape speed of approximately 8 mm/sec, which is sufficiently slower than the rotational speed of the rotating drum 2. do. During rewinding, the rotating drum 2 and the magnetic tape 4 rotate and run in the direction of the arrow B and the direction of the arrow D, respectively, at a speed of approximately 200 degrees compared to the speed during recording and reproduction.
Also, during fast forwarding, the rotating drum 2 and the magnetic tape 4 are in the same direction and approximately 200
Each rotates and travels at a speed of approximately

FIG. 4 shows a track pattern on the magnetic tape 4 recorded by the above-mentioned rotary head device 1, and as mentioned above, the running speed of the magnetic tape 4 is sufficiently compared to the rotation speed of the rotary drum 2. It's late, so
The inclinations of the tracks 9 and 10 are the same as the inclination of the magnetic tape 4 with respect to the rotating drum 2. In the figure, track 9 is recorded by the first magnetic head 3A, and track 10 is recorded by the second magnetic head 3B, since both magnetic heads 3A and 3B have different azimuth angles. Tracks 9 and 10 with different azimuths are recorded alternately. Each track 9, 10 is composed of a plurality of blocks, and one track 9, 10
are subcode area blocks 9A, 9E, 10A, and 10 in which time information, song numbers, etc. are recorded, respectively.
E and magnetic heads 3A and 3B are on tracks 9 and 10.
ATF signal area blocks 9B, 9D, where reference signals for accurately tracing are recorded.
10B, 10D, and PCM signal area blocks 9C, 1 in which data such as music signals and image signals are recorded.
It is divided into 0C and 0C.

FIG. 5 shows the structure of ATF signal area blocks 9B, 9D, 10B, and 10D in the track pattern.
0B, 10D include 130kHz pilot signal recording sections 9B ₁ , 9D ₁ , 10B ₁ , 10D ₁ and 522kHz first sync signal recording sections 10B ₂ , 10D ₂ .
784kHz second sync signal recording section 9B ₃ , 9D ₃ and
1.568MHz erasure signal recording section 9B ₄ , 9D ₄ , 10
B ₄ , 10D ₄ are configured.

6 to 8 are relationship diagrams of velocity vectors between the magnetic tape 4 and the magnetic heads 3A and 3B during playback, fast forwarding, and rewinding [each figure a], and tracks 9 and 10 of the magnetic tape 4, respectively. FIG. In each figure, V _T is the velocity vector of the magnetic tape 4, V _H is the magnetic head 3A,
3B, V is the velocity vector of the magnetic heads 3A and 3B on the magnetic tape 4, and _V0 is the track direction component of the velocity vector V, respectively. In particular, FIGS. 7 and 8 show the speeds of the magnetic heads 3A and 3B when the track direction component _V0 during fast forwarding and rewinding, respectively, is made equal to the track direction component _V0 during playback in FIG. In other words, if the relative speed of the rotary head device 1 with respect to the magnetic tape _{4 is controlled so that the speed vector V H shown} in FIGS. The track direction component V ₀ of the velocity vector V during rewinding is the same as during playback, and the signal reading speed is the same during playback, fast forwarding, and rewinding, and the configuration using PLL circuits, signal processing circuits, etc. Complications can be prevented. The present invention relates to an improvement of a device having such a control function.

FIG. 1 shows a block configuration of a main part of a servo control system according to an embodiment of the present invention, and first, the servo system of the rotating drum 2 will be explained. A data signal recorded on the magnetic tape 4 is reproduced by both magnetic heads 3A and 3B by rotation of the rotary drum 2, and this reproduced signal is amplified by a head amplifier 11. ATF pilot frequency error detection circuit 1 after this
2 detects the deviation of the reproduction frequency of the ATF pilot signal of the reproduction signal from 130kHz and outputs an error signal. Furthermore, the drum-tape relative speed calculation circuit 13 calculates the rotational speed of the rotary drum 2 at which the ATF pilot signal is detected at 130 kHz based on the error signal output from the ATF pilot frequency error detection circuit 12. In other words, the rotation speed of the rotary drum 2 is calculated such that the relative speed between the magnetic tape 4 and the rotary drum 2 is equal to that during reproduction. In response to the drum rotation speed signal output from the drum-tape relative speed calculation circuit 13, the motor rotation speed setting circuit 14 generates a reference clock corresponding to the drum speed. Also, a drum motor 1 which is a drive source for the rotating drum 2
5 is provided with a rotation detection Hall element 16 and a drum phase detection Hall element 17, and the rotation detection Hall element 16 generates 24 pulse signals per rotation of the rotating drum 2. On the other hand, the drum phase detecting Hall element 17 outputs one pulse signal per rotation of the rotating drum 2. Then, the speed error detection circuit 18 compares the drum speed signal set by the motor rotation speed setting circuit 14 and the FG signal detected and output by the rotation detection Hall element 16, and
Outputs a speed error detection signal.

The RF signal detected by the head amplifier 11 is
They are also added to the signal processing circuit 19 and the PLL circuit 20, respectively. As is well known, the PLL circuit 20 includes a phase comparison circuit 20A and a low pass filter 20B.
and a voltage controlled oscillator 20C, the phase difference between the input signal and the signal from the voltage controlled oscillator 20C is constantly compared in a phase comparison circuit 20A, and the output voltage of this phase comparison circuit 20A is smoothed by a low pass filter 20B. The voltage controlled oscillator 20C operates as a control voltage for the voltage controlled oscillator 20C, and acts to match the output frequency of the voltage controlled oscillator 20C to the lock state reference frequency of the input signal.

The basic clock of the RF signal detected by this PLL circuit 20 is given to the signal processing circuit 19, and the signal processing circuit 19 receives the clock from the head amplifier 11.
The RF signal is sent to the voltage controlled oscillator 2 of the PLL circuit 20.
The reference signal of the reference signal generating circuit 21 of the rotary drum 2 is set by the output of the signal processing circuit 19. The output of the reference signal generating circuit 21 is compared with the output of the drum phase detecting Hall element 17 in the phase error detecting circuit 22 to detect the phase error of the rotating drum 2. The phase error signal of this phase error detection circuit 22 and the speed error signal of the speed error detection circuit 18 described above are added in an adder circuit 23 to calculate the total error.

Furthermore, the PLL error voltage output from the low-pass filter 20B in the PLL circuit 20 is
As shown in FIG. 9, the relationship is directly proportional to the relative speed between the magnetic tape 4 and the rotating drum 2 of the rotating head device 1. The PLL error voltage output from the low-pass filter 20B is amplified by the amplifier 25 via the normally closed contact b of the switch 24. Next, in the subtraction circuit 26, the PLL error signal of the amplifier 25 is subtracted from the total error signal from the addition circuit 23,
The drum motor drive circuit 27 is controlled by the output of the subtraction circuit 26, and the rotation of the drum motor 15 is controlled. Further, the switch 24 is a PLL
Switching is controlled by the unlock detection circuit 28. The PLL unlock circuit 28 corrects errors in the digital signal from the signal processing circuit 19, and when the error rate increases to a predetermined percentage or more, it determines that the PLL circuit 20 is not locked and turns on the switch 24. Switch to normally open contact a.

Next, the servo control system for the magnetic tape 4 will be explained. Reel motors 29 and 30 for driving the supply reel 5 and take-up reel 6 are provided with rotation speed detection elements 31 and 32, respectively. The outputs of both rotational speed detection elements 31 and 32 are respectively input to a reel motor rotational speed detection circuit 33, and the rotational speeds of both reel motors 29 and 30, that is, the supply reel 5 and the take-up reel 6 are detected. The rotation speed signal of the larger rotation speed of both reel motors 29 and 30 is output to the reel motor rotation speed error detection circuit 3.
4, the error signal is compared with the set rotation speed signal from the reel motor rotation speed setting circuit 35 and output from the reel motor rotation speed error detection circuit 34.
It is added to a reel motor drive circuit 36 that controls the rotation of both reel motors 29 and 30. Further, the mechanical control circuit 37 detects which mode of stop, playback, recording, fast forward, and rewind mode is in place, and gives instructions to the signal processing circuit 19 and mode setting circuit 38, respectively. The mode setting circuit 38 sets the mode of the drum motor rotation speed setting circuit 14 and the reel motor rotation speed setting circuit 35 in accordance with the mode instructed by the mechanical control circuit 37.

Next, the operation of the embodiment described above will be explained with reference to FIGS. 10 and 11. First, to explain the servo control system for running the magnetic tape 4, the reel motor rotation speed error detection circuit 34 detects the rotation of the larger rotation speed of both reel motors 29 and 30 detected by the reel motor rotation speed detection circuit. The number of rotations is compared with the set rotation speed of the reel motor rotation speed setting circuit 35, and the reel motor drive circuit 36 is controlled by the error signal.
Therefore, both reel motors 29 and 30 are servo-controlled to maintain the reel 5 or 6, which has a higher rotation speed, at a certain constant rotation speed, so that the rotation speed of both reels 5 and 6 becomes the 10th rotation speed. The result will be as shown in the figure.
In this figure, BOT indicates a state where almost all of the magnetic tape 4 is wound on the supply reel 5, EOT shows a state where almost all of the magnetic tape 4 is wound on the take-up reel 6, and COT shows a state where almost all of the magnetic tape 4 is wound on the take-up reel 6. The tape winding amount of No. 5 indicates the same state. Since either reel 5 or 6 is controlled to have a constant rotation speed, the reel 5 at this constant rotation speed
Alternatively, the greater the tape winding amount 6, the greater the running speed of the magnetic tape 4. Therefore, the running speed of the magnetic tape 4 is as shown in FIG.
The running speed reaches the maximum when the tape winding amounts of reels 6 and 6 become equal, and as the tape winding amount of either reel 5 or 6 increases, the running speed decreases.
Since the present invention aims to control the relative speed between the magnetic tape 4 and the rotating drum 2 to be constant, it is necessary to control the rotation of the drum motor 15 in accordance with the characteristic curve shown in FIG.

Next, to explain the operation of the servo control system of the drum motor 15, the PLL error voltage output from the low pass filter 20B of the PLL circuit 20 is as follows.
As shown in FIG. 9, it is directly proportional to the deviation in relative speed between the magnetic tape 4 and the rotating drum 2. Therefore,
If the rotation speed of the drum motor 15 is controlled based on the PLL error voltage, the magnetic tape 4 and the rotating drum 2 can be
It is easy to control the relative speed to a constant value. However, as shown in FIG. 9, the above-mentioned proportional relationship is limited to a range in which the relative speed deviation is within ±10%, and if this limit is exceeded, the PLL circuit 20 loses lock, so the PLL error voltage Becomes indeterminate.

Therefore, when the PLL circuit 20 is unlocked, the PLL unlock detection circuit 28 detects this and connects the switch 24 to the normally open contact a. Therefore, the PLL error voltage is cut off, and the head amplifier 11, ATF pilot frequency error detection circuit 12, drum-tape relative speed calculation circuit 13,
Motor rotation speed setting circuit 14, speed error detection circuit 1
8. A servo control system including the phase error detection circuit 22, the addition circuit 23, and the drum motor drive circuit 27 controls the number of rotations, that is, the rotation speed of the drum motor 15, so that the ATF pilot signal is detected at 130 kHz.

By the way, when fast forwarding or rewinding, the seventh
As shown in FIG. 8 and FIG. 8, each time the magnetic heads 3A, 3B scan the magnetic tape 4 once, two ATF signal area blocks 9B, 9D,
10B and 10D can be read, but since the magnetic heads 3A and 3B pass diagonally through each track 9 and 10 of the magnetic tape 4, the ATF pilot signals of two adjacent tracks 9 and 10 interfere with each other. If such interference occurs, it is extremely likely that the frequency of the ATF pilot signal will be detected incorrectly.

In order to prevent such erroneous detection, the ATF pilot frequency error detection circuit 12, drum-tape relative speed calculation circuit 13, and motor rotation speed setting circuit 14 are constructed as shown in FIG. This configuration will be explained with reference to FIGS. 12 to 17. ATF pilot signal detection circuit 3
9, the RF signal from the head amplifier 11 shown in FIG. 12a is passed through a bandpass filter (not shown).
As shown in Figure 12b, obtained by passing
ATF pilot signal is output. On the other hand, ATF
From the pilot signal detection circuit 40, as shown in FIG.
As shown in the figure, a high level signal is output only during the period in which the ATF pilot signal is output. This ATF pilot signal detection circuit 39 and
Each output signal of the ATF pilot signal detection circuit 40 is inputted to a pilot width counting circuit 42 via an AND circuit 41. The pilot width count circuit 42 detects the cycle width of the ATF pilot signal. To explain in detail, Fig. 13 a, b
are enlarged views of parts of FIGS. 12b and 12c, respectively, and the period width W of the pulse of the ATF pilot signal shown in FIG.
It is detected by counting the count clock from 3. The minimum value of the detected cycle width W is held in the minimum hold circuit 44 while being updated each time.

On the other hand, the drum phase signal generation circuit 45 outputs a drum phase signal synchronized with one rotation of the rotary drum 2 as shown in FIG. 12d, and the reset signal generation circuit 46 outputs a drum phase signal as shown in FIG. 12e. A reset pulse is output in synchronization with the rise and fall of the drum phase signal, and the minimum hold circuit 44 is reset by this reset pulse.
That is, the minimum value of the cycle width W held in the minimum hold circuit 44 is updated during one cycle of the rotary drum 2, and is reset by one revolution of the rotary drum 2.

Further, the minimum value of the cycle width W held in the minimum hold circuit 44 is the maximum value detected and held by the maximum hold circuit 47 during N rotation periods of the rotary drum 2. The rotational speed N of the rotating drum 2 is determined by the frequency division ratio of the frequency dividing circuit 48, and the output of the frequency dividing circuit 48 causes the reset signal generating circuit 49 to output a reset signal every N rotations of the rotating drum 2. The maximum hold circuit 47 is reset. Through the above operation, the cycle width W data output from the maximum hold circuit 47 becomes approximately equal to the average value of N rotations of the rotary drum 2, and the cycle width data of the two adjacent tracks 9 and 10 during fast forwarding or rewinding becomes approximately equal to the average value of N rotations of the rotary drum 2. The influence of interference between each ATF pilot signal is excluded. And the pilot width count circuit 4
The frequency of the ATF pilot signal or the deviation from 130kHz can be calculated from the count number N of the count clock counted in step 2.
Based on the output of the maximum hold circuit 47, the drum-tape relative speed calculation circuit 13 detects the drum rotation speed at which the relative speed between the rotating drum 2 and the magnetic tape 4 reaches a predetermined value, that is, the ATF pilot signal at 130kHz. The drum rotation speed is calculated. Next, the motor rotation speed setting circuit 14
The drum rotation speed setting calculation circuit 50 generates a clock signal that can be compared with the FG signal detected by the rotation detection Hall element 16 according to the drum rotation speed calculated by the drum-tape relative speed calculation circuit 13, and The clock signal is latched in the set rotation speed latch circuit 51 until a reset signal is applied from the reset signal generation circuit 49, and is outputted to the speed error detection circuit 18 as a reference value. Note that the frequency of changing the set speed is determined by the frequency dividing ratio of the frequency dividing circuit 48.

The drum rotation speed setting calculation circuit 50 described above also performs calculations such that the change from the previous setting value is within a certain range, and thereby the ATF.
This prevents errors from being included in the reproduction frequency of the pilot signal. A problem that arises at this time is, for example, when the tape running speed suddenly increases as shown in FIG. 14 when transitioning from a stopped state to a fast-forward state. In order to keep the speed the same as in the case of early ripening, it is necessary to control the rotation speed of the drum motor 15 so that it rises rapidly in accordance with the tape speed, as shown by the solid line curve in FIG. be. However, the drum motor 15 is
Since the rotation is controlled at a cycle determined by a frequency division ratio of 8, the rotation speed changes only in steps, as shown by the dashed line in the figure, and furthermore, the drum rotation speed setting calculation described above Due to the function of the circuit 50 to protect against incorrect detection of the frequency of the ATF pilot signal,
The drum motor 15 will not be able to rapidly increase its speed. When the rotational speed of the drum motor 15 changes as shown in the curve shown by the dashed line in FIG. 15, the deviation of the relative speed between the rotating drum 2 and the magnetic tape 4 from the early stage changes as shown in FIG. 16. However, the driving voltage of the drum motor 15 at this time is
This results in a waveform that changes stepwise, like the curve shown by the one-dot chain line in FIG.

Therefore, in order to solve such problems,
The subtraction circuit 26 shown in FIG. 1 subtracts the PLL error voltage output from the low-pass filter 20B of the PLL circuit 20 from the signal voltage corresponding to the total error obtained by adding the speed error and phase error of the drum motor 15. ing. This PLL error voltage is generated between the rotating drum 2 and the magnetic tape 4 as shown in FIG.
Since the drive voltage of the drum motor 15 is directly proportional to the relative speed between 17, the rotation speed of the drum motor 15 also rises rapidly as shown in the solid line curve in FIG. , the relative speed between the rotating drum 2 and the magnetic tape 4 can be kept equal to that during reproduction.

In addition, when moving from the stopped state to the rewinding state, the operation is almost the same as when moving from the stopped state to the fast forwarding state, and the drum motor 15
The rotational speed of the magnetic tape 4 can be made to follow rapid changes in the running speed of the magnetic tape 4.

<Effects of the Invention> As detailed above, according to the magnetic recording and reproducing apparatus of the present invention, when the PLL circuit is unlocked, the PLL error voltage is cut off, and the rotation drum and magnetic field are adjusted from the reproduction frequency of the ATF pilot signal. Since the relative speed with the head is calculated and the rotational speed of the drum motor is controlled so that this relative speed remains constant, the PLL circuit can be locked by scanning changes in drum speed, unlike conventional devices. There is no need to spend time searching for the drum speed.

Also, if the PLL circuit is locked,
Since the PLL error voltage is subtracted from the drum motor drive control signal obtained by the ATF pilot signal, when transitioning from stop to fast forward or rewind, the drum motor rotational speed rise delay is eliminated, and the drum motor rotational speed can be added to sudden changes in the running speed of the magnetic tape.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a main part of an embodiment of the magnetic recording/reproducing apparatus of the present invention, FIG. 2 is a detailed block diagram of a part of FIG. 1, and FIGS. 3 to 13 are diagrams of the present invention. FIG. 3 is a diagram showing the relationship between a rotary head device and a magnetic tape, FIG. 4 is an explanatory diagram of a track pattern on a magnetic tape, and FIG. 6 is an explanatory diagram showing details of the ATF signal region block in the track pattern, and FIGS. 6a and 6b are diagrams showing the relationship between each velocity vector between the magnetic tape and the magnetic head during playback, and the moving direction of the magnetic tape track and the magnetic head. Figures 7a and b and Figures 8a and b are diagrams of the relationship between the velocity vectors of the magnetic tape and the magnetic head during fast forwarding and rewinding, and the relationship between the moving direction of the track and the magnetic head, respectively. 9 is a characteristic diagram showing the PLL error voltage versus drum-tape relative speed, FIG. 10 is a characteristic diagram showing the rotation speed control of the take-up reel and supply reel, and FIG. 11 is a characteristic diagram showing the magnetic tape running speed control. Figures 12a to 12e are timing charts showing operating voltage waveforms of various parts of the drum motor rotational speed control system based on the ATF pilot signal, and Figures 13a and b.
are enlarged views of Figures 12b and 12c, Figures 14 to 17
The figures show the characteristics of the tape speed, drum motor rotation speed, drum-tape relative speed deviation, and drum motor drive voltage over time in the embodiment apparatus shown in FIGS. 1 and 2, respectively, when transitioning from a stop state to a fast-forward state. It is a diagram. 2...Rotating drum, 3A, 3B...Magnetic head, 4...Magnetic tape, 12...ATF pilot frequency error detection circuit, 13...Drum-tape relative speed calculation circuit, 15...Drum motor, 20
......PLL circuit, 26...Subtraction circuit, 27...
Drum motor drive circuit, 28...PLL unlock detection circuit.

Claims (1)

[Claims] 1 A magnetic tape is wound around a rotating drum equipped with a pair of magnetic heads in an inclined state, and as the rotating drum rotates, data such as music signals are digitally recorded on the magnetic tape by both magnetic heads, and data is reproduced from the magnetic tape. In a recording/reproducing device, detect the reproduction frequency of the ATF pilot signal reproduced from the magnetic tape and calculate the deviation from a predetermined frequency.
ATF pilot frequency error detection circuit and this
A drum that detects the rotational speed of the rotating drum at which the relative speed between the rotating drum and the magnetic tape reaches a predetermined value based on the output signal of the ATF pilot frequency error detection circuit, and outputs a rotational speed control signal for the drum motor for driving the rotating drum. - a tape relative speed calculation circuit, a PLL circuit that operates to lock at the reference frequency of the reproduction signal from the magnetic head, a subtraction circuit that subtracts the PLL error voltage of this PLL circuit from the rotational speed control signal voltage; It detects when the circuit is unlocked and sends the signal to the subtraction circuit.
1. A magnetic recording and reproducing device comprising: a PLL unlock detection circuit that blocks input of a PLL error voltage.