JP3269592B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type magnetic recording / reproducing apparatus such as a VTR (video tape recorder) and a digital audio signal recording / reproducing apparatus. It is possible to detect the rotational phase of the head drum with respect to the tape and provide control of switching timing of a plurality of magnetic heads mounted on the head drum and phase synchronization between a recording signal and the head drum without providing a detecting means. The present invention relates to a possible magnetic recording and reproducing apparatus.

[0002]

2. Description of the Related Art Conventionally, in a VTR or the like, the following method has been used to detect the rotational phase of a head drum.

[0003] For example, "Introduction to Home VTR" by Corona Company
In the apparatus described in (141-144), a magnetic field change by a DPG (Drum Phase Generator) magnet attached to a specific portion of the head drum and rotating with the head drum is detected by a DPG coil fixed outside the head drum. By doing so, the absolute rotational phase of the head drum was detected.

In the device described in Japanese Patent Application Laid-Open No. 2-108265, an address signal recorded in advance at a specific position of a track on a tape is reproduced by a magnetic head mounted on a head drum. And the rotational phase of the head drum with respect to the tape was detected.

[0005]

Among the above-mentioned prior arts, in the former device using the method of detecting the absolute rotation phase of the head drum by DPG, in addition to the DPG magnet and the DPG coil, the DPG signal is also used. Hardware such as an amplification and waveform shaping circuit is required, and therefore, no consideration has been given to cost reduction and system miniaturization.

[0006] Of the above-mentioned prior art, the latter,
In an apparatus that uses a method of detecting the rotation phase of the head drum with respect to the tape at the time of reproduction by relying on an address signal recorded at a specific position of a track on the tape, the position of the address signal and the recording are determined depending on the type of the signal being recorded Since the state is different, the hardware for separating and extracting the address signal is also significantly different, and therefore, versatility has not been considered. Furthermore, since this is a method of detecting the rotational phase of the head drum at the time of reproduction, no special consideration has been given to recording.

The present invention has been made in view of the fact that it was not taken into consideration in the above-mentioned prior art. Therefore, an object of the present invention is to provide a DPG or the like dedicated to detecting the rotational phase of a head drum. Without having hardware,
Another object of the present invention is to provide a magnetic recording / reproducing apparatus capable of detecting the rotation phase of a head drum with respect to a tape regardless of the type of a recorded signal, in both recording and reproduction.

[0008]

According to the present invention, in order to achieve the above-mentioned object, when the head drum starts to rotate, the head drum rotates for at least one rotation (hereinafter referred to as a specific period). Head selection means for continuously selecting one magnetic head from two or more magnetic heads mounted on the drum, and envelope detection means for performing envelope detection of a signal reproduced by the selected magnetic head to obtain an envelope signal And a rotational phase detecting means for detecting the rotational phase of the head drum with respect to the tape from the waveform of the envelope signal obtained in the specific period.

[0009]

The operation principle of the present invention will now be described.

First, the processing content differs depending on whether the operation to be performed is a recording operation or a reproducing operation, and whether the target tape is a recorded tape or an unrecorded tape.

Here, as to whether the operation to be performed is a recording operation or a reproducing operation, the user instructs the magnetic recording and reproducing device to perform an operation to be performed, and the magnetic recording and reproducing device can recognize the instruction. .
On the other hand, whether the target tape is a recorded tape or an unrecorded tape,
One magnetic head is selected from among a plurality of magnetic heads mounted on the head drum, and provisional reproduction is performed by only the magnetic head, and when any reproduction signal is obtained during an arbitrary period, magnetic recording / reproduction is performed. It can be recognized that the device is at least a recorded tape.

As described above, after the operation to be performed and the target tape are determined, the processing is performed in the following four cases. That is, there are four cases of reproducing a recorded tape, recording on a recorded tape, reproducing an unrecorded tape, and recording on an unrecorded tape. Hereinafter, each case will be described.

First, a case where a recorded tape is reproduced will be described. Usually, when performing magnetic recording, a recording signal is frequency-modulated and recorded. Therefore, the tape is run at the same tape speed as at the time of recording and while performing accurate tracking, the recording signal is reproduced by a plurality of magnetic heads mounted on the head drum, and envelope detection (hereinafter referred to as envelope) of the reproduced signal is performed. Detecting), the amplitude of the envelope signal obtained by the detection becomes a constant level. On the other hand, at this time, when one magnetic head is selected from a plurality of magnetic heads and a recording signal is reproduced only by the magnetic head, the waveform of the envelope signal obtained at that time is a portion where the envelope waveform exists (amplitude). Is divided into two parts, a part with a certain level) and a part that does not exist (a part with zero amplitude), and a signal is obtained that clearly shows the period during which the selected magnetic head is in contact with the tape and the period during which it is not. Can be Therefore, by using this envelope signal, the rotation phase of the head drum with respect to the tape can be detected.

However, if the correct head switching timing for a plurality of magnetic heads is not known in advance,
As described above, since accurate tracking cannot be performed at the same tape speed as at the time of recording, simply performing envelope detection on the reproduced signal does not result in the above-described envelope signal (that is, when the selected magnetic head is used). It is not possible to obtain a signal that clearly indicates the period during which the tape is in contact with the tape and the period during which the tape is not in contact.

Therefore, in the present invention, first, the head drum is rotated at an appropriate speed, and the tape is rotated at a speed of m + 1 / n times the tape speed at the time of recording (where m is an integer and n is an integer other than 0). (That is, the vehicle travels with the addition of a fraction of 1 / n). Then, one magnetic head is selected from among a plurality of magnetic heads mounted on the head drum. Play the recorded signal. Then, the reproduced signal is subjected to envelope detection, and the obtained envelope signal is integrated for n rotations in units of one rotation of the head drum. By doing so, a signal that clearly shows a period during which the selected magnetic head is in contact with the tape and a period during which the selected magnetic head is not in contact is obtained as an integral envelope signal. The rotation phase of the drum can be detected.

This operation will be described in more detail. For example, in a helical scan type magnetic recording / reproducing apparatus in which a tape is wound around a head drum on which two magnetic heads are mounted at an angle of 180 ° and recording and reproduction are performed by the magnetic heads, m is set to 0 and n is set to 2.
Consider a case in which a tape is run at 0 + 1/2 speed (ie, 1/2 speed) of the tape speed at the time of recording, and one magnetic head is selected, and a recording signal is reproduced only by the magnetic head. View.

FIG. 3 is an explanatory diagram showing the trajectory of the magnetic head moving on the tape in such a case and the waveforms of the envelope signal and the integral envelope signal obtained at that time.

In FIG. 3, (a) shows the locus of the magnetic head moving on the tape, and (b) shows the waveforms of the envelope signal and the integral envelope signal obtained at that time.

In FIG. 3A, every other track on the tape 1 has the same azimuth. Therefore, the tracks T1 and T3 have the same azimuth, but have different azimuths from the track T2. I have. When such a tape 1 runs in the direction of arrow A at half the speed of the tape at the time of recording and a head drum (not shown) comes into contact with the tape 1 and rotates, the tape 1 mounted on the head drum The first magnetic head CH1 and the second magnetic head CH2 move on the tape 1 at an angle with respect to the tape running direction,
While the head drum makes two rotations, a locus as shown by an arrow is drawn.

That is, in the first rotation, first, the first magnetic head CH1 starting from the temporary switching point (ie, the temporary reference position of the rotation of the head drum) reaches the upper end of the tape 1 and 1, the second magnetic head CH2 comes to hit the tape 1,
The tape 1 moves from the lower end to the upper end. Thereafter, when the second magnetic head CH2 reaches the upper end of the tape 1 and no longer touches the tape 1, the first magnetic head CH1 comes into contact with the tape 1 again, and reaches a temporary switching point from the lower end of the tape 1. . The same applies to the second rotation.

At this time, the first magnetic head CH
When either one of the first and second magnetic heads CH2 is selected and the recording signal is reproduced only by that magnetic head, the signal shown in FIG.
Any one of the waveforms shown in (1) to (4) in (b) is obtained.

In FIG. 3B, (1) and (2) show waveforms when the first magnetic head CH1 is selected. Of these, (1) shows the case where the azimuth of the first magnetic head CH1 is tracked. (2) shows a waveform when the azimuth of the first magnetic head CH1 matches the azimuth of the track T2. (3) and (4) show the second magnetic head CH2.
Are selected when (3) is selected.
(4) shows a waveform when the azimuth of the magnetic head CH2 matches the azimuth of the track T2, and (4) shows a waveform when the azimuth of the second magnetic head CH2 matches the azimuth of the tracks T1 and T3.

That is, for example, when the first magnetic head CH1 is selected and the recording signal is reproduced only by the first magnetic head CH1, the first magnetic head CH1 is selected.
Assuming that the tracks corresponding to the azimuth are T1 and T3, the waveform of the obtained envelope signal is as shown in (1). That is, in the first rotation, first, the first magnetic head CH starting from the temporary switching point
No. 1 moves on the track T1 where the azimuths match, so that an envelope signal having a large amplitude can be obtained.
Magnetic head CH1 reaches the upper end of tape 1 and
Otherwise, the envelope signal cannot be obtained. While the second magnetic head CH2 is in contact with the tape 1, the first magnetic head CH1 does not hit the tape 1, so that no envelope signal is obtained.
When the first magnetic head CH1 hits the tape 1 again, an envelope signal can be obtained. However, at this time, since the first magnetic head CH1 moves on the track T2 having a different azimuth, only the envelope signal having a small amplitude can be obtained. In the second rotation, if the first magnetic head CH1 reaches the upper end of the tape 1 and does not touch the tape 1 again, the envelope signal cannot be obtained again. Then, the second magnetic head CH2 is
While touching, no envelope signal is obtained, and thereafter, when the first magnetic head CH1 comes into contact with the tape 1 again, an envelope signal is also obtained. At this time, since the first magnetic head CH1 moves on the track T3 where the azimuths coincide, an envelope signal having a large amplitude is obtained again.

Next, when the envelope signal obtained as described above is integrated in one rotation unit, one of the waveforms (α) and (β) shown in FIG. 3B is obtained as an integrated envelope signal. One waveform is obtained. That is, since the tape speed is 1/2 the tape speed at the time of recording,
When the envelope signals obtained during the two rotations of the head drum are added and integrated in units of one rotation, the integrated envelope signal has a strip-shaped waveform as shown in (α) or (β).

In FIG. 3B, (α) represents the waveform of the integrated envelope signal obtained by adding and integrating the waveform of the envelope signal shown in (1) or (2), and (β) represents (3) or (3). The waveforms of the integrated envelope signals obtained by adding and integrating the waveforms of the envelope signals shown in 4) are shown. In (α), the strip as a waveform is divided into two strips before and after. However, the front end of the front strip and the rear end of the rear strip are continuous as a rotational phase, so These two strips are actually one strip.

As described above, the waveform of the integrated envelope signal obtained by integrating the envelope signal for two rotations in one rotation unit has a strip shape, that is, the two waveforms of the portion where the envelope waveform exists and the portion where the envelope waveform does not exist. Will be divided into two parts. This means a period during which the selected magnetic head touches the tape and a period during which the selected magnetic head does not touch the tape.

In this way, as the above-mentioned integral envelope signal, a signal that clearly shows a period in which the selected magnetic head is in contact with the tape and a period in which the selected magnetic head is not in contact with the tape is obtained.
Using this integral envelope signal, the rotation phase of the head drum with respect to the tape can be detected. That is,
From such a phase of the integral envelope signal, a correct head switching timing can be generated. After the correct head switching timing is obtained,
The switching signal appropriately switches the plurality of magnetic heads, and reduces the tape speed to a fraction (ie, 1/1).
By returning from the speed to which n) is added to the original target speed, correct reproduction can be performed.

If no signal is obtained as a result of detecting the above-mentioned envelope signal, it is unrecorded. Therefore, whether the tape is a recorded tape or an unrecorded tape is determined by the above-mentioned method. Can be done simultaneously in the process.

As described above, when the envelope signal is detected after the tape speed is added with a fraction of 1 / n to detect the envelope signal, the envelope signal obtained for each rotation of the head drum is different from the track signal. Is often obtained as an envelope signal obtained by reproducing However, as described above, since the reproduced signal is a signal that has been subjected to frequency modulation, the amplitude of the reproduced signal is substantially constant irrespective of the content of the signal. Therefore, the envelope obtained by performing envelope detection on the reproduced signal is obtained. The signal also has a substantially constant amplitude regardless of the track. Therefore, as described with reference to FIG. 3, by integrating each envelope signal obtained by reproducing from each track, even if the waveforms of these envelope signals are combined, a substantially constant amplitude can be obtained, and the rotation of the head drum can be obtained. Phase can be detected.

As described above, the tape speed is reduced to 1 /
When the tape is run with a fraction of n, the phase control in the reproducing operation, that is, the tracking operation is not performed. Usually, in order to perform a tracking operation,
Before that, the correct head switching timing must be known, but in the case of the present invention, the timing is not known in advance. However, as described above, even if the tracking operation is not performed, if the DC gain of the speed system of the tape running control is set sufficiently high and n is not set to an extremely large number, the phase of the tape running becomes large together with the tape running. There is no deviation, and the trajectories of the magnetic head moving on the tape can be arranged at substantially equal intervals as shown in FIG.

Next, a case in which recording is performed on a recorded tape will be described. When a track is already formed on the tape, recording is started from a state where tracking is completed in consideration of connection with a recorded signal. Therefore, the reproduction operation is always performed once. Therefore, when performing the reproducing operation, the same processing as the above-described reproduction of the recorded tape is performed, the rotational phase of the head drum with respect to the tape is detected, and the phase is adjusted so that the rotational phase matches the phase of the signal to be recorded. After the control, the recording of the recording signal may be started.

Next, a case where recording is performed on an unrecorded tape will be described. Even if the tape is an unrecorded tape, the integral envelope signal is detected, and if no signal is obtained as a result, it can be determined that the tape is unrecorded. If not recorded, stop running the tape,
One magnetic head is selected from a plurality of magnetic heads, and a signal is recorded as temporary recording by only the magnetic head over a period of at least one rotation of the head drum. In this way, one track can always be formed with only one selected magnetic head. Then, again, one magnetic head is selected from the plurality of magnetic heads, and the track formed by the temporary recording is immediately reproduced by only the magnetic head, and envelope detection of the reproduced signal is performed. Therefore, if the phase of the obtained envelope signal waveform is checked, the rotational phase of the head drum with respect to the tape can be detected. In this case, since the tape is stopped, the track can be reproduced without fail, and therefore, there is no particular need to perform a process of integrating the envelope signal. The temporarily recorded signal is erased by a rotary erase head.

Next, a case where an unrecorded tape is reproduced will be described. First, the above-mentioned integral envelope signal is detected, and it is determined whether the signal has been recorded or not. If no recording is performed, the tape is run at a speed obtained by adding a fraction 1 / n to the target tape speed m of the reproducing operation, that is, at a speed of m + 1 / n times. Then, a plurality of magnetic heads are sequentially switched every n rotations of the head drum, and it is monitored whether or not an integral envelope signal is detected every n rotations. here,
When the integral envelope signal can be detected, it means that the head has entered the recorded area from the unrecorded area. Therefore, the rotational phase of the head drum with respect to the tape can be detected using the integrated envelope signal. That is, a head switching timing is generated from the phase of the integral envelope signal, and thereafter, the tape speed is returned to m times speed to perform a desired reproducing operation.

As described above, when reproducing an unrecorded tape, a plurality of magnetic heads are sequentially switched every n rotations of the head drum. Therefore, reproduction is performed regardless of whether the selected magnetic head is in contact with the tape or not. However, since the tape is an unrecorded tape and nothing is recorded on the tape, the reproduced image is the same whether or not the tape is in contact with the tape. Next, a case where an envelope signal cannot be correctly detected due to head clogging or tape damage will be described. When the recorded tape is reproduced, if the envelope signal cannot be detected correctly, it is determined that the recording is unrecorded, and the same operation as when recording is not performed is performed. If the clogging of the head and the tape damage are eliminated as a result of the tape running, a correct envelope signal is detected, and the correct reproduction is performed from that point.
Also, when recording on a pre-recorded tape, similarly, if the envelope signal cannot be detected correctly, once it is determined to be unrecorded, temporary recording is performed, and if the reproduced output for that recording cannot be obtained, Inform the user that there is head clogging or tape damage. At this time, provisional recording is performed, but there is no problem since recording is temporarily permitted as a user. Also, the temporarily recorded signal is erased by the rotary erasing head, so that no signal remains. The same processing as described above is performed when head clogging or tape damage occurs during recording or reproduction of an unrecorded tape.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a reproducing system of a magnetic recording / reproducing apparatus as a first embodiment of the present invention. FIG. 2 shows a recording system of a magnetic recording / reproducing apparatus as a first embodiment of the present invention. It is a block diagram. That is, in this embodiment,
A tape is wound around a head drum on which a plurality of magnetic heads are mounted at a winding angle of 180 ° (actually, it is necessary to wind the tape by 180 ° or more in order to create an overlap period in which each magnetic head is playing simultaneously). This is a helical scan type magnetic recording / reproducing apparatus that performs both recording and reproduction by using these magnetic heads.

First, the configuration of the reproducing system will be described. In FIG. 1, 1 is a magnetic tape, 2 is a capstan motor, 3 is a pinch roller, 4 is a CFG (Capstan Freq).
uency Generater) detector, 5 is CFG amplifier, 6 is C
FG waveform shaper, 7 is a capstan motor controller, 8 is a CTL (control) head, 9 is a capstan motor driver / amplifier, 10 is a head drum, 11 is a drum motor, and 12 is DFG (Drum Frequency Generate).
r) detector, 13 is a DFG amplifier, 14 is a DFG waveform shaper, 15 is a drum motor controller, 16 is a drum motor driver / amplifier, 17 and 18 are rotary transformers, 19 and 20 are preamplifiers, and 21 is a reproducing head. A changeover switch (hereinafter, a head changeover switch is abbreviated as a head switch), 22 is a reproduction signal processing circuit, 23 is a low-pass filter (hereinafter, abbreviated as LPF), 24 is an envelope detector, 25 is an envelope integrator, 26 Is a waveform shaper, 27 is an envelope edge detector, 28 is D
An FG numbering processor 29 is a reproduction head switch signal generator, and 30 is a system controller.

Next, the configuration of the recording system will be described. In FIG. 2, components having the same reference numerals as those in FIG. 1 are the same components. 1 and FIG. 2 are different from each other only with respect to the signal lines necessary for the reproducing operation, and in FIG. 2, only the signal lines necessary for the recording operation. , Respectively. 2, reference numerals 31 and 32 denote recording amplifiers, 33 and 34 denote recording head switches, 35 denotes a recording signal processing circuit, 36 denotes a recording head switch signal generator, and 39 and 40 denote rotary transformers.

Next, the reproducing operation of this embodiment will be described with reference to FIG. First, in FIG. 1, to perform reproduction, the drum motor 11 and the capstan motor 2 are started. Regarding the drum motor 11, first, the drum motor controller 15 generates a starting voltage for starting the motor (if the drum motor 11 is a current control type, it generates a starting current. Hereinafter, in this embodiment, the drum motor 11 is used as the drum motor 11). A case where a voltage-controlled motor is used will be described as an example). The starting voltage is applied to the drum motor 11 by the drum motor driver amplifier 16.

FIG. 4 is a waveform diagram showing the waveform of the main signal of FIG. When the drum motor 11 starts rotating, a DFG signal is detected by the DFG detector 12. The DFG signal is appropriately amplified and waveform-shaped by the DFG amplifier 13 and the DFG waveform shaper 14 to generate a rectangular DFG signal as shown in FIG. Drum motor controller 15
Measures the time from the rising edge to the next rising edge of the DFG signal, which is the square wave, the time from the falling edge to the next falling edge, or the time between the falling edge and the falling edge. ,
This is compared with a target value to generate a speed error signal, and a signal obtained by performing appropriate gain and frequency characteristic compensation on the speed error signal is applied to the drum motor driver amplifier 16. Thereby, the speed of the drum motor 11 is controlled.

The same applies to the control of the capstan motor 2. The starting voltage output by the capstan motor controller 7 is applied to the capstan motor 2 through the capstan motor driver / amplifier 9. When the capstan motor 2 starts rotating, the CFG detector 4 detects the CFG.
A signal is detected. This CFG signal is appropriately amplified and waveform-shaped by a CFG amplifier 5 and a CFG waveform shaper 6, and
A CFG signal of a rectangular wave as shown in FIG. The capstan motor controller 7 determines the time from the rising edge to the next rising edge of the CFG signal, which is the rectangular wave, the time from the falling edge to the next falling edge, or the time between the falling edge and the falling edge. The speed error signal is generated by measuring the time between the signals and comparing it with a target value, and a signal obtained by performing appropriate gain and frequency characteristic compensation on the speed error signal is used as a capstan motor driver / amplifier 9. Is applied. This allows
The speed of the capstan motor 2 is controlled.

At this time, the drum motor 11 is in a stopped state or a semi-stopped state (a state in which a DFG signal described later cannot be measured, or a state in which the DFG numbering processor 28 has stopped counting the DFG signal). When the drum motor 11 is started from that state, the system controller 30 sends the capstan motor controller 7
Then, an instruction is sent to add a fraction 1 / n to the target speed m of the capstan motor 2. As a result, the speed of the capstan motor 2 is controlled to be m + 1 / n times the speed at the time of recording (where m is an integer and n is an integer other than 0). At the same time, an instruction is sent from the system controller 30 to the reproducing head switch signal generator 29 to output a head switch signal for selecting only one magnetic head. In accordance with this instruction, the reproducing head switch signal generator 29 outputs a head switch signal that causes the reproducing head switch 21 to select only one magnetic head. As a result, after the two magnetic heads (not shown) mounted on the head drum 10 pass through the rotary transformers 17 and 18 and are appropriately amplified by the preamplifiers 19 and 20, the reproduction head switch is used. 21 selects and outputs only one of them.

The reproduced signal output from the reproducing head switch 21 is subjected to various processes typified by a process of canceling (ie, demodulating) the frequency modulation in the reproduced signal processing circuit 22 to be desired by the user. It is restored to a signal.

For example, if the recording signal is an analog video signal, it undergoes demodulation processing for a frequency-modulated luminance signal and a color signal converted to a low frequency, and performs appropriate waveform equalization and compensation. Output after processing. If the recording signal is a video or audio digital signal,
Demodulates the frequency-modulated coded signal (signal that has been coded for compression and error correction), decodes the coded signal, and converts digital signals to analog signals as necessary. (Note that in FIG. 1,
Although an analog video signal is described as an example, the recording signal may be any signal as long as the recording method is such that the level of the reproduction signal is constant. ).

The reproduction signal output from the reproduction head switch 21 is also input to the envelope detector 24 after unnecessary bands are removed by the LPF 23. The input reproduced signal is subjected to envelope detection in the envelope detector 24 and output as an envelope signal as shown in FIG.

Further, after the envelope signal is sampled by the envelope integrator 25 by the DFG signal output from the DFG waveform shaper 14, as described above in FIG. 3, the recorded tape is reproduced. The signal is integrated for n rotations in units of one rotation of the head drum and output as an integral envelope signal as shown in FIG. 4D (FIG. 4D shows the case where n is 2).

Then, n in one rotation of the head drum
The integrated envelope signal obtained by the rotation integration is subjected to appropriate waveform shaping by the waveform shaper 26, and then the falling edge, rising edge or both phase information thereof is detected by the envelope edge detector 27. ,
The signal is output to the DFG numbering processor 28 (in FIG. 4D, the phase information of the falling edge (downward arrow) of the integral envelope signal is detected). The phase information of the edge of the detected integral envelope signal is the DF
Head drum 10 for tape 1 synchronized with G signal
Is information on the rotation phase. The detection of the phase information of the edge by the envelope edge detector 27 is performed after the integral envelope signal for n rotations of the head drum is obtained, that is, the envelope signal of the nth rotation is output after the head drum rotates n times. It will be done later. Therefore,
In the case of FIG. 4, the processing is performed after the second rotation envelope signal is output.

On the other hand, the DFG numbering processor 28
The rising edges of the DFG signal output from the G waveform shaper 14 are counted, and each rising edge (upward arrow) is numbered as shown in FIG. 4B. Then, when the above-described phase information is input from the envelope edge detector 27, the DFG numbering processor 28 resets the count at an appropriate timing based on the phase information.

That is, in the case of FIG. 4, the envelope edge detector 27 detects the phase information of the falling edge (downward arrow) of the integral envelope signal as shown in FIG. In the processor 28, the rising edge (provisionally numbered “3”) of the DFG signal immediately after the falling edge of the integral envelope signal shown in FIG. Initialize to attach. However, as described above, since the detection of the edge phase information in the envelope edge detector 27 is performed after the output of the envelope signal of the second rotation, actually, the detection immediately after the output of the envelope signal of the second rotation is performed. Is initialized so that the rising edge of the DFG signal is numbered “5”.
D, immediately after the falling edge of the integration envelope signal
This is similar to the case where the rising edge of the FG signal is initialized to be numbered “1”.

In this way, by initializing the number of the rising edge of the DFG signal, the DFG numbering processor 28 performs new numbering thereafter, as shown in FIG. That is, the newly numbered DFG signal, that is, the numbered DFG signal after initialization has information on the rotation phase of the head drum 10 with respect to the tape 1.

Then, the reproducing head switch signal generator 2
Reference numeral 9 denotes two magnetic heads, as shown in FIG. 4E, based on the phase of the numbered DFG signal after initialization output from the DFG numbering processor 28, that is, based on the number assigned. Is generated and output to the reproducing head switch 21. FIG.
In (e), a head switch signal is generated such that the number assigned to the rising edge of the DFG signal is alternately switched at timings of “1” and “4”.

After the above processing, the drum motor controller 15
Is the DF output from the envelope edge detector 27.
The phase of the G signal is compared with the phase of a signal which is internally obtained and serves as a reference for rotation of the drum motor 11 to generate a phase error signal, and the phase error signal is subjected to appropriate gain and frequency characteristic compensation. The obtained signal is added to the speed error signal separately generated as described above, and is output. The added signal controls the speed of the drum motor 11 and the phase of the drum motor 11.

Also, the instruction sent from the system controller 30 to the capstan motor controller 7 to add the fraction 1 / n to the target speed m is canceled, so that the capstan motor controller 7 2 is controlled to the original target speed. Further, the capstan motor controller 7 controls the C
The phase of the TL signal is compared with the phase of a signal which is internally obtained and serves as a reference for rotation of the capstan motor 2 to generate a phase error signal, and the gain and frequency characteristics of the phase error signal are appropriately compensated. The applied signal is added to the speed control signal separately generated as described above and output, and the added signal controls the speed of the capstan motor 2 as well as the phase of the capstan motor 2. Thus, the tracking servo can be applied. However, the phase offset cannot be made zero by itself, and a tracking offset occurs. Therefore, a point where the amplitude of the envelope signal output from the envelope detector 24 is maximized is searched,
Adjust the phase lock point.

The reproduction operation includes fast-forward reproduction and rewind reproduction in addition to normal reproduction. In particular, in a VTR or the like, special reproduction such as slow reproduction or still image reproduction is performed.
However, since any playback needs to be performed after the tracking operation for controlling the tape speed is completed, it is only necessary to transition to each playback after the above operation is completed.
There is no problem at all.

Also, the tape recorded by the helical scan type magnetic recording / reproducing apparatus does not always use the entire end of the tape in the width direction of the tape. In particular, as shown in FIG. 5A, a video track for recording a video signal (an analog audio signal is recorded in a deep layer) and a PCM track for recording a digital audio signal are arranged in series. In the case of the tape 1 or the like, the PCM track is optional and may not be recorded. In such a case, instead of detecting the phase information of the rising edge of the integral envelope signal in the above-described envelope edge detector 27,
As shown in FIG. 5B, the end of each video track (the upper end of the tape 1 shown in FIG. 5A)
It is necessary to always detect the phase information of the falling edge of the integral envelope signal, and to initialize the number of the rising edge of the DFG signal by the falling phase information in the DFG numbering processor 28. .

Next, the recording operation of this embodiment will be described with reference to FIG. First, when recording, it is necessary to determine whether or not the tape is a recorded tape. For this purpose, the above-described envelope detection, integration and the like are performed by the reproduction system shown in FIG. 1, and if the waveform of the resulting integrated envelope signal is an appropriate waveform, it can be determined that the tape is a recorded tape.

Here, if the tape is a recorded tape, the drum motor controller 15 determines the phase of the recording signal and the numbered D after initialization output from the DFG numbering processor 28.
Phase control is performed so as to match the phase of the FG signal (that is, to perform phase synchronization). That is, for example, if the recording signal is an analog video signal, the vertical synchronization signal (V.syn)
c) matches the phase of the numbered DFG signal after initialization, and, if the recording signal is a video or audio digital signal, an address signal assigned to each bit stream defined by the respective standards. And the phase of the numbered DFG signal after initialization (in FIG. 2, an analog video signal is described as an example).

The recording head switch signal generator 36
Generates a head switch signal for switching between the two magnetic heads based on the phase of the numbered DFG signal after initialization output from the DFG numbering processor 28, that is, the number assigned. Two recording head switches 3
3 and 34 respectively. Then, the recording signal output from the recording signal processing circuit 35 is appropriately selected by the two recording head switches 33 and 34 based on the input head switch signal, and the rotary transformer 39,
The data is supplied to two magnetic heads mounted on the head drum 10 via 40 to perform recording.

The recording signal processing circuit 35 performs necessary processing for recording, such as frequency modulation, on the recording signal. For example, if the recording signal is an analog video signal,
The luminance signal is frequency-modulated, the carrier chrominance signal is converted to a low frequency, and further, each signal is subjected to waveform equalization and various kinds of compensation. If the recording signal is a video or audio digital signal, compression and error correction are performed.
This is to frequency-modulate the encoded signal.

Next, if the envelope signal is not detected even if the provisional reproduction is performed and it is determined that the tape is an unrecorded tape, the following processing is performed. First, the system controller 30
It instructs the capstan motor controller 7 to stop the rotation of the capstan motor 2. Then, the system controller 30 further instructs the recording head switch signal generator 36 to output a head switch signal for selecting only one magnetic head. As a result, while the running of the tape 1 is stopped,
Recording can be performed using only the selected magnetic head. In this state, recording is performed for at least one rotation of the head drum. Thereby, a temporary recording track is formed.

Then, in this state, in the reproducing system shown in FIG. 1, only one of the magnetic heads is selected, and reproduction is performed again using only the magnetic head. At this time, since the tape 1 is stopped, the previously recorded signal is reproduced as it is. Thus, the reproduced signal is subjected to envelope detection by the envelope detector 24 to obtain an envelope signal. In this case, since the selected magnetic head is completely on-track on the track on which the recording was temporarily performed, the waveform of the envelope signal becomes almost a strip without integration. Therefore, the envelope integrator 25 performs only sampling of the envelope signal by the DFG signal. The envelope signal output from the envelope integrator 25 is subjected to an appropriate waveform shaping by a waveform shaper 26, and then, an envelope edge detector 27 detects phase information of the edge. The DFG numbering processor 28 resets (initializes) the count at an appropriate timing based on the phase information of the detected edge, and performs new numbering for the subsequent rising edge of the DFG signal. The drum motor controller 15 adjusts the phase of the recording signal and the phase of the numbered DFG signal after initialization from the DFG numbering processor 28 (that is, the phase is synchronized).
Perform phase control. The subsequent processing is the same as the processing for the recorded tape.

The above is the configuration and operation of the present embodiment. According to this embodiment, the helical scan type magnetic recording / reproducing apparatus does not have dedicated hardware for detecting the absolute rotation phase of the head drum, such as DPG, and furthermore, the recorded signal Regardless of the type of
Since the rotational phase of the head drum with respect to the tape can be detected in both recording and reproduction, the cost can be reduced and the size of the system can be reduced.

Next, an example of a rough operation of the entire magnetic recording / reproducing apparatus of the above-described embodiment, including a process at the time of trouble such as when the tape or the head is damaged, will be described.
This will be described in more detail with reference to FIGS.

First, FIG. 6 shows an example of a processing flow at the time of recording. The stopped drum motor 11 is started, the capstan motor 2 is started at 1/2 speed, and the reproducing head switch 21 is used to select only one magnetic head. Then, it is determined whether recording has been performed or not on the basis of the waveform of the integral envelope signal obtained after the head drum 10 has rotated twice. Here, if the waveform of the integral envelope signal is an appropriate waveform, it is determined that the tape is a recorded tape, and
The number of the rising edge of the DFG signal is initialized, the phase of the recording signal is synchronized with the phase of the numbered DFG signal after the initialization, and recording is started.

On the other hand, when the waveform of the integral envelope signal is not an appropriate waveform, the capstan motor 2 is stopped to stop the tape running. And after performing the temporary recording,
Envelope detection is performed in this state. Normally, the envelope signal is always detected here, and after the temporary recording signal is erased by the rotary erasure head, the number of the rising edge of the DFG signal is initialized, and the phase of the recording signal and the number after initialization are numbered. The phase should be synchronized with the phase of the DFG signal to start recording. However, the fact that the envelope signal is not detected means that the tape or the magnetic head is damaged for some reason, and the temporarily recorded signal cannot be reproduced. Therefore, at this time, the processing is terminated by explicitly indicating to the user that the tape or the magnetic head is damaged.

Next, FIG. 7 shows an example of a processing flow at the time of normal reproduction. The stopped drum motor 11 is started, the capstan motor 2 is started at 1/2 speed, and the reproducing head switch 21 is used to select only one magnetic head. Then, based on the waveform of the integral envelope signal obtained after the head drum 10 makes two rotations, it is determined whether recording has been performed or not. Here, if the waveform of the integral envelope signal is an appropriate waveform, it is determined that the tape is a recorded tape, the number of the rising edge of the DFG signal is initialized, and reproduction is started.

On the other hand, if the waveform of the integral envelope signal is not an appropriate waveform, even if the waveform is damage to the tape or the magnetic head, it is determined that the tape is an unrecorded tape, and 1 /
The tape 1 is run at 2 × speed. The magnetic head to be selected is switched by the reproducing head switch 21 every time the head drum 10 makes two rotations, and the waveform of the integral envelope signal obtained every two rotations of the head drum is monitored. Then, when an appropriate waveform is obtained as an integral envelope signal due to a rush from an unrecorded portion of the tape 1 to a recorded portion, elimination of clogging of the head, or termination of a damaged region of the tape, etc. Playback becomes possible.

Next, FIG. 8 shows an example of a processing flow at the time of fast-forward playback or rewind playback (ie, search). The processing at the time of fast forward reproduction or rewind reproduction is almost the same as the processing at the time of normal reproduction described above. The difference is the processing when the waveform of the integral envelope signal is not an appropriate waveform. That is, if the waveform of the integral envelope signal is not an appropriate waveform, it is determined that the tape is an unrecorded tape even if it is damage to the tape or the magnetic head, and m + 1/2.
The tape 1 is run at double speed (m is a normal search speed). And every time the head drum 10 makes two rotations,
The reproduction head switch 21 switches the magnetic head to be selected, and monitors the waveform of the integral envelope signal obtained every two rotations of the head drum.

FIG. 9 is an explanatory diagram showing the locus of the magnetic head moving on the tape in such a case and the waveforms of the envelope signal and the integral envelope signal obtained at that time.

FIG. 9A shows the trajectory of the magnetic head moving on the tape, and FIG. 9B shows the waveforms of the envelope signal and the integral envelope signal obtained at that time. In FIG. 9B, the second magnetic head CH
The waveform when 2 is selected is omitted.

For example, in the case of fast-forwarding at 2-3 times speed, the locus of the magnetic head and the waveform of the envelope signal are as shown in FIG. 9 (FIG. 9 shows the case where the tape speed is 2 + 1/2 times). The waveform of the finally obtained integral envelope signal is the same as that of FIG.

In this way, the waveform of the integral envelope signal is monitored, and thereafter, when the tape 1 enters the unrecorded portion from the unrecorded portion or when the clogging of the head is eliminated or the damaged region of the tape is ended, the integral envelope signal is integrated. When an appropriate waveform is obtained as the envelope signal waveform, correct fast-forward playback or rewind playback can be performed.

The example of the operation of the entire magnetic recording / reproducing apparatus of the above embodiment has been described. By performing the above operation, even if the tape or the magnetic head is damaged at the time of recording, the user can grasp the fact and prevent the meaningless recording from being performed.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 10 is a block diagram showing a reproducing system of a magnetic recording / reproducing apparatus according to a second embodiment of the present invention. FIG.
At 0, the same reference numerals as those in FIG. 1 denote the same components. In addition, 37 is LPF, 38 is ATF (Auto T
rack Finding) error generation circuit.

This embodiment is almost the same as the first embodiment. The difference is that the signal used for phase control of the capstan motor 2 (that is, tracking servo) is not a CTL signal but a pilot signal leaking from adjacent tracks before and after.

That is, the head drum 10 for the tape 1
After the rotation phase is detected, the capstan motor controller 7 controls the phase of the capstan motor 2 (ie, tracking servo). At this time, the capstan motor controller 7 is adjacent to the track currently being reproduced. Since the pilot signals leak from the tracks, the leaked pilot signals are detected by the ATF error generation circuit 38, and the phase of the capstan motor 2 is adjusted so that the leak amounts from the adjacent tracks before and after become equal to each other. Control (ie,
Tracking servo).

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 11 is a block diagram showing a reproducing system of a magnetic recording / reproducing apparatus according to a third embodiment of the present invention. FIG.
In FIG. 1, components having the same reference numerals as those in FIG. 1 are the same components.

This embodiment is almost the same as the first embodiment. The difference is that the signal used for phase control (ie, tracking servo) of the capstan motor 2 is not a CTL signal, but an envelope signal.

That is, unlike the second embodiment, without using pilot signals leaking from adjacent tracks before and after,
By maximizing the level of the envelope signal output from the envelope detector 24, the capstan motor 2
(I.e., tracking servo). With such a configuration, the processing for detecting the rotation phase of the head drum 10 with respect to the tape 1 and the processing for performing the phase control (that is, tracking servo) of the capstan motor 2 can be shared. There is an effect that the cost and the size can be further reduced.

[0079]

As described above, according to the present invention, the DPG
, Etc., without having dedicated hardware for detecting the absolute rotational phase of the head drum, and irrespective of the type of recorded signal, and further, in both recording and reproduction, The rotational phase of the head drum can be detected. Therefore, there is an effect that the size and cost of the system can be reduced.

At the time of recording, the provisional recording operation is performed, so that no special hardware or the like is added.
It is possible to detect damage to the tape or the magnetic head, thereby making it possible to clearly indicate to the user that the tape or the magnetic head is damaged, and thus to provide an effect of preventing meaningless recording.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a reproducing system of a magnetic recording / reproducing apparatus as a first embodiment of the present invention.

FIG. 2 is a block diagram showing a recording system of the magnetic recording / reproducing apparatus as the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a trajectory of a magnetic head moving on a tape when a tape speed is 0 + 1/2 times speed, and waveforms of an envelope signal and an integral envelope signal obtained at that time.

FIG. 4 is a waveform chart showing a waveform of a main part signal of FIG. 1;

FIG. 5 is an explanatory diagram showing a format of a tape in which video tracks and PCM tracks are arranged in series, and waveforms of an envelope signal and a DFG signal obtained at that time.

FIG. 6 is a flowchart illustrating an example of a processing flow during recording according to the first embodiment.

FIG. 7 is a flowchart illustrating an example of a processing flow during normal reproduction according to the first embodiment.

FIG. 8 is a flowchart illustrating an example of a processing flow of fast-forward playback and rewind playback (ie, search) in the first embodiment.

FIG. 9 is an explanatory diagram showing the trajectory of a magnetic head moving on a tape when the tape speed is 2 + 1/2 times speed, and the waveforms of an envelope signal and an integral envelope signal obtained at that time.

FIG. 10 is a block diagram showing a reproducing system of a magnetic recording / reproducing apparatus as a second embodiment of the present invention.

FIG. 11 is a block diagram showing a reproducing system of a magnetic recording / reproducing apparatus as a third embodiment of the present invention.

[Description of Signs] 1 ... magnetic tape, 2 ... capstan motor, 3 ... pinch roller, 4 ... CFG detector, 6 ... CFG waveform shaper, 7
... Capstan motor controller, 8 ... CTL head, 10
... head drum, 11 ... drum motor, 12 ... DFG detector, 14 ... DFG waveform shaper, 15 ... drum motor controller, 17, 18 ... rotary transformer of reproduction signal, 1
9, 20: preamplifier, 21: reproducing head switch, 2
2 ... reproduction signal processing circuit, 24 ... envelope detector, 2
5 Envelope integrator, 27 Envelope edge detector, 28 DFG numbering processor, 29 Reproduction head switch signal generator, 30 System controller, 3
1, 32: recording amplifier, 33, 34: recording head switch, 35: recording signal processing circuit, 36: recording head switch signal generator, 38: ATF error generation circuit, 39, 4
0 ... Rotary transformer for recording signals.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hideo Nishijima 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi, Ltd. Video Media Research Laboratories (72) Koji Kaniwa, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock (72) Inventor Hiroya Abe 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd.Video Media Research Laboratories (72) Yoshio Narita 1410 Inada, Katsuta-shi, Ibaraki, Japan Hitachi, Ltd. Manufacturing Company AV Equipment Division (72) Inventor Akifumi Tabata 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi Image Information Systems, Ltd. (56) References JP-A-48-54912 (JP, A) JP-A-57- 164466 (JP, A) Hikaru 2-144142 (JP, U) (58) Fields surveyed (Int. Cl ^7, DB name) G11B 15/467 -. 15/473 G11B 5/588

Claims (23)

(57) [Claims] 1. A tape is wound around a head drum on which a plurality of magnetic heads are mounted, the head drum is rotated while running the tape, and a signal is recorded on the tape by the plurality of magnetic heads. In a magnetic recording / reproducing apparatus for reproducing a recorded signal, a head selecting means for selecting one magnetic head from the plurality of magnetic heads, and an envelope detecting means for detecting an amplitude level of a signal reproduced by the selected magnetic head Rotating the head drum and stopping the running of the tape
And the head drum rotates at least once.
Over the specified period, the head selection means
Selecting one magnetic head from the number of magnetic heads,
The signal is recorded by the magnetic head, and the recording
The recorded recording track is moved forward by the selected magnetic head.
Playback over a specific period, and adjust the amplitude level of the playback signal.
Detected by the envelope detection means,
From the waveform shape of the
A magnetic recording reproducing device characterized by detecting a rotation phase of a ram.
Raw equipment. 2. A tape is wound around a head drum on which a plurality of magnetic heads are mounted, the head drum is rotated while running the tape, and signals are recorded on the tape by the plurality of magnetic heads. In a magnetic recording / reproducing apparatus for reproducing a recorded signal, a head selecting means for selecting one magnetic head from the plurality of magnetic heads, and an envelope detecting means for detecting an amplitude level of a signal reproduced by the selected magnetic head Starting rotation of the head drum and running of the tape.
And the head drum rotates at least once.
The above-mentioned head selecting means sets the specific period as a unit.
One magnetic head is selected from a plurality of magnetic heads, and the selection is performed.
The amplitude level of the reproduction signal of the selected magnetic head is
Detected by rope detection means, and as a result, envelope
No signal detected or proper envelope waveform
Is not obtained, the above-mentioned specific period as a unit
The selection of the magnetic heads by the head selection means, the e
Repeat the envelope signal detection by the envelope detector.
And then a proper envelope signal is obtained.
From the waveform shape of the envelope signal
Detecting the rotational phase of the head drum with respect to the pump
A magnetic recording / reproducing apparatus characterized by the above-mentioned. 3. The magnetic recording / reproducing apparatus according to claim 2,
Te, binding of the detection of the envelope signal in the specified period
If the envelope signal is not detected or
If the envelope waveform cannot be obtained,
Magnetic recording, characterized in that the step selects another magnetic head
Recording and playback device. 4. A head drive having a plurality of magnetic heads mounted thereon.
Wrapping the tape around the tape and running the tape
By rotating the head drum, the plurality of magnetic heads
Record the signal on the tape, or
In a magnetic recording / reproducing apparatus for reproducing a signal that is present, one magnetic head is selected from the plurality of magnetic heads.
Head selecting means, and a signal reproduced by the selected magnetic head.
Envelope detection means for detecting the amplitude level of the signal.
And Bei, rotate the travel start of said tape of said head drum
And the head drum rotates at least once.
Over a specific period, the plurality of
One of the magnetic heads is selected, and the selected magnetic head is selected.
The amplitude level of the reproduced signal of the magnetic head
The envelope signal is detected by the
When no tape was detected, the running of the tape was stopped.
Thereafter, the head drum is set to the selection for the specified period.
The signal is recorded by the selected magnetic head, and
The recording track formed by the above-mentioned selected magnetic head
In the specific period, the amplitude level of the reproduced signal is
The envelope signal is detected by the envelope detection means, and the envelope signal is detected.
The head drum for the tape from the waveform shape of the signal
Magnetic recording / reproducing apparatus characterized by detecting rotation phase of magnetic recording / reproducing device
Place. 5. The magnetic recording / reproducing apparatus according to claim 4,
And providing an erasing head on the head drum,
The recording track recorded by a magnetic head is
After detecting the rotation phase of the pad drum, the erase head
A magnetic recording / reproducing apparatus characterized by erasing. 6. The method according to claim 1, wherein
In the magnetic recording / reproducing apparatus, the head drive is obtained from a waveform shape of the envelope signal.
The detection of the rotational phase of the system means that the selected magnetic head is
The envelope caused by detaching from the loop
Note that detection is based on the falling edge of the signal.
Magnetic recording and reproducing device. 7. The magnetic recording reproducing apparatus according to any one of claims 1 to 5, wherein the said head drum rotation phase detection from the waveform shape of an envelope signal, the selected magnetic head Te
Said envelope created by initiating contact with the envelope
It is detected based on the rising edge of the rope signal.
And a magnetic recording / reproducing apparatus. 8. The magnetic recording reproducing apparatus according to any one of claims 1 to 7, the rotational frequency of the head drum the envelope signal
Sampling means for sampling at a frequency proportional to
Comprising, from the waveform shape of the envelope signal
The detection of the rotational phase of the head drum refers to the envelope signal.
From the waveform shape of the signal
Magnetic recording / reproducing apparatus characterized by specifying signal phase
Place. 9. A magnetic recording / reproducing apparatus according to claim 8, wherein
Te, sampling phase to or the said sampling means
Count the phase of other signals synchronized with the sampling phase
As a result, the detection of the rotational phase of the head drum is continued.
A magnetic recording / reproducing apparatus. 10. The method according to claim 1, wherein
The magnetic recording / reproducing apparatus according to any one of the preceding claims, further comprising a specifying means, and detecting by the envelope detecting means.
If the emitted envelope signal is not detected
Is applied to the tape or magnetic head by the above-mentioned explicit means.
Characterized by the fact that there is an image to the user.
Energy recording and playback device. 11. A head mounted with a plurality of magnetic heads.
By winding the tape to the ram, before while traveling the tape
The head drum is rotated, and the plurality of magnetic heads
A signal on the tape, or
A magnetic recording / reproducing apparatus for reproducing a current signal, wherein one magnetic head is selected from the plurality of magnetic heads.
Head selecting means, and a signal reproduced by the selected magnetic head.
Envelope detection means for detecting the amplitude level of the signal;
The envelope signal is expressed in units of one rotation of the head drum.
And an envelope integrating means for integrating the rotation of the head drum and the running of the tape.
A specific period during which the head drum rotates a plurality of times or more.
Over, the plurality of magnetic heads are
One magnetic head is selected from the magnetic head, and the selected magnetic head is selected.
The amplitude level of the read signal of the head is detected by the envelope detection.
Means, and the envelope integration means
To perform integration for the specified period, and calculate the integration envelope signal.
From the waveform shape, the head drum with respect to the tape
Magnetic recording / reproducing apparatus characterized by detecting rotational phase
Place. 12. A tape is wound around a head drum on which a plurality of magnetic heads are mounted, the head drum is rotated while running the tape, and a signal is recorded on the tape by the magnetic head, or a signal is recorded on the tape. A magnetic recording / reproducing apparatus for reproducing a signal, a head selecting means for selecting one magnetic head from the plurality of magnetic heads; an envelope detecting means for detecting an amplitude level of a signal reproduced by the selected magnetic head; An envelope integrating means for integrating the envelope signal in units of one rotation of the head drum, rotating the head drum and stopping the running of the tape;
And the plurality of magnetic heads are
One magnetic head is selected from the
At least one rotation
After recording a signal with the magnetic head,
The formed recording track is read by the selected magnetic head.
During a specific period when the head drum rotates a plurality of times or more,
Or play, and detects the amplitude level of the reproduced signal by the envelope detection means, the specific time period is integrated by the envelope integrating means, the waveform of the integrating envelope signal, the rotational phase of the head drum with respect to the tape A magnetic recording / reproducing device for detecting. 13. A tape is wound around a head drum on which a plurality of magnetic heads are mounted, the head drum is rotated while running the tape, and a signal is recorded on the tape by the plurality of magnetic heads. In a magnetic recording / reproducing apparatus for reproducing a recorded signal, a head selecting means for selecting one magnetic head from the plurality of magnetic heads, and an envelope detecting means for detecting an amplitude level of a signal reproduced by the selected magnetic head And an envelope integrating means for integrating the envelope signal in units of one rotation of the head drum , wherein the rotation of the head drum and the running of the tape are started.
A specific period during which the head drum rotates a plurality of times or more.
The plurality of magnetic fields are set by the head selecting means in units of
One magnetic head is selected from the magnetic heads, and the selected
The amplitude level of the reproduction signal of the magnetic head
Detection by the detection means and the envelope integration
Means for integrating for the specified period, and as a result,
No envelope signal is detected or proper envelope
If a rope waveform cannot be obtained, the specified period
Selection of the magnetic head by the head selecting means
Of the envelope signal by the envelope detection means
Detection and integration envelope by the envelope integration means
Loop signal detection repeatedly, and then generate an appropriate waveform.
When the integral envelope signal is detected, the integral
From the waveform shape of the envelope signal to the tape
Magnetic head characterized by detecting the rotational phase of a head drum
Energy recording and playback device. 14. A magnetic recording / reproducing apparatus according to claim 13,
In, binding of the detection of the envelope signal in the specified period
If the envelope signal is not detected or
If the envelope waveform cannot be obtained,
Magnetic recording, characterized in that the step selects another magnetic head
Recording and playback device. 15. A headed device having a plurality of magnetic heads mounted thereon.
Wrap the tape around the ram and move the tape
The head drum is rotated, and the plurality of magnetic heads
A signal on the tape, or
A magnetic recording / reproducing apparatus for reproducing a current signal , wherein one magnetic head is selected from the plurality of magnetic heads.
Head selecting means, and a signal reproduced by the selected magnetic head.
Envelope detection means for detecting the amplitude level of the signal;
The envelope signal is expressed in units of one rotation of the head drum.
And an envelope integrating means for integrating the rotation of the head drum and the running of the tape.
A specific period during which the head drum rotates a plurality of times or more.
Over, the plurality of magnetic heads are
One magnetic head is selected from the heads, and the selected magnetic head is selected.
The amplitude level of the reproduced signal of the
And the envelope integration means
The integration period, and as a result, the integration envelope
If no tape signal is detected, stop running the tape.
After stopping, turn the head drum at least once
Signal is recorded by the selected magnetic head during the rotation period
And selecting a recording track formed by the recording.
Reproduction for the specified period with the magnetic head thus obtained,
When the width level is detected by the envelope detection means,
In both cases, the product of the specific period is obtained by the envelope integration means.
From the waveform shape of the integral envelope signal.
Detecting the rotational phase of the head drum with respect to the pump
A magnetic recording / reproducing apparatus characterized by the above-mentioned. 16. A magnetic recording / reproducing apparatus according to claim 15,
In the above, the head drum is provided with an erasing head,
The recording track recorded by a magnetic head is
After detecting the rotation phase of the pad drum, the erase head
A magnetic recording / reproducing apparatus characterized by erasing. 17. The method according to claim 11 or 13 to 16.
In the magnetic recording / reproducing apparatus according to any one of the preceding claims, the rotational phase of the head drum is adjusted by running the tape.
The tape running speed when recording the tape running speed when detecting
Characterized by controlling the speed to a non-integer multiple of degrees
Recording and playback device. 18. A magnetic recording / reproducing apparatus according to claim 17,
In the above, a speed that is a non-integer multiple of the tape running speed at the time of recording is referred to as recording.
M + 1 / n (m is an integer, n is 0 or more)
Speed), and the specific period is
This is a period in which the pad drum rotates at least n times or more.
A magnetic recording / reproducing apparatus characterized by the above-mentioned. 19. The method according to claim 11, wherein
The magnetic recording / reproducing apparatus according to claim 1, wherein the head is obtained from a waveform shape of the integral envelope signal.
The detection of the rotational phase of the drum means that the selected magnetic head
Is separated from the tape by the integral envelope.
Is detected based on the falling edge of the
A magnetic recording / reproducing apparatus characterized by the above-mentioned. 20. The magnetic recording / reproducing apparatus according to claim 11 , wherein the detection of the rotational phase of the head drum from the waveform shape of the integral envelope signal includes the step of detecting the selected magnetic head.
Said product caused by initiating contact with the tape
Detect based on rising edge of minute envelope signal
A magnetic recording / reproducing apparatus characterized by being performed. 21. The magnetic recording / reproducing apparatus according to claim 11 , wherein the envelope signal is converted to a rotational frequency of the head drum.
Sampling means for sampling at a frequency proportional to
Comprising, from the waveform shape of the envelope signal
The detection of the rotational phase of the head drum refers to the envelope signal.
From the waveform shape of the signal
Magnetic recording / reproducing apparatus characterized by specifying signal phase
Place. 22. A magnetic recording / reproducing apparatus according to claim 21,
Oite, sampling phase to or the said sampling means
Count the phase of other signals synchronized with the sampling phase
As a result, the detection of the rotational phase of the head drum is continued.
A magnetic recording / reproducing apparatus. 23. The method according to claim 11, wherein
The magnetic recording / reproducing apparatus according to claim 1, further comprising an explicit unit, wherein the envelope detecting unit detects
If the envelope signal to be emitted is not detected
Is da the tape or magnetic heads by the emphasizer
Characterized by the fact that there is an image to the user.
Energy recording and playback device.