JPH0463454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic recording/reproducing apparatus, and more particularly to a magnetic recording/reproducing apparatus including improvements in mode discrimination and tracking control.

[Prior Art] Conventionally, in magnetic recording and reproducing apparatuses, there have been two types of tape running control methods, ie, tracking control methods: one using a control signal and the other using a pilot signal.

In the system using control signals, a control track separate from the video signal track is provided on the magnetic tape, and tracking is controlled by recording and reproducing control signals using the control track.

By the way, among magnetic recording and reproducing devices that use control signals, there are devices that can record and play back at multiple tape speeds, and these devices have a mode discrimination function that automatically determines the tape speed during playback. equipment was provided. This mode discrimination device discriminates the tape speed during playback by using the control signal.

In the method using a pilot signal, a pilot signal for tape running control generated in synchronization with the rotation of a rotating magnetic head is superimposed on the video signal track of the magnetic tape and recorded, and during playback,
A pilot signal was detected from the reproduced signal and tracking control was performed using the pilot signal.

Here, as an example of a method using pilot signals, a method using pilot signals of four different frequencies f ₁ , f ₂ , f ₃ , and f ₄ will be described.

FIG. 1 is a block diagram showing the configuration of a conventional magnetic return path regeneration device that performs tracking control using a pilot signal.

First, the configuration of a tracking control means of a conventional magnetic recording/reproducing apparatus will be explained with reference to FIG. In the figure, the video signal input terminal 4 is connected to the adder 1
It is connected to the recording amplifier 5 via 00. The recording amplifier 5 is connected to a rotary transformer 7 via a changeover switch 6, and the rotary transformer 7 is connected to a magnetic head 8. The video signal input terminal 4, the adder 100, the recording amplifier 5, the changeover switch 6, the rotary transformer 7, and the magnetic head 8 constitute a video signal recording circuit. The head switch signal input terminal 1 is connected to a cyclic frequency generator 2 and a changeover switch 18, and the cyclic frequency generator 2 is connected to an adder 100. A head switch signal inputted to the head switch signal input terminal 1 and representing the timing of switching the rotary head is applied to the circulation frequency generator 2 and the changeover switch 18. A cyclic frequency generator 2 sequentially generates a pilot signal in response to the leading and trailing edges of the head switch signal.

During recording, a video signal is input to the video signal input terminal 4, superimposed with a pilot signal in an adder 100, and then supplied to a recording amplifier 5 where it is amplified.
The changeover switch 6 is connected to the recording side, and the output of the recording amplifier 5 is given to the magnetic head 8 via the rotary transformer 7, and the output from the recording amplifier 5 is applied to the magnetic tape (not shown).
recorded above.

The rotary transformer 7 is connected to a regenerative amplifier 9 via a changeover switch 6. Magnetic head 8, rotary transformer 7, selector switch 6, and regenerative amplifier 9
constitutes a video signal reproducing circuit.

During playback, the changeover switch 6 is switched to the playback side, and the video signal including the pilot signal reproduced by the magnetic head 8 is applied to the playback amplifier 9 via the rotary transformer 7 and the changeover switch 6, where it is amplified. The regenerative amplifier 9 is a low pass filter 10
The low pass filter 10 is connected to the mixer 11
connected to. The circulating frequency generator 2 is also connected to the mixer 11 . The output of the regenerative amplifier 9 is applied to a low pass filter 10, and a pilot signal component is extracted from the regenerated signal. This pilot signal component and the pilot signal (hereinafter referred to as carrier signal f _cR during reproduction) sequentially generated by the circulating frequency generator 2 during reproduction are sent to the mixer 1.
1, and a signal component having a frequency corresponding to the frequency difference between both signals is output. mixer 11
are connected to bandpass filters 12 and 13.
The bandpass filter 12 is connected to a detector 14, and the detector 14 is connected to a subtracter 16. Further, the bandpass filter 13 is connected to a detector 15, and the detector 15 is connected to a subtracter 16. The output of the mixer 11 is simultaneously applied to a bandpass filter 12 having a passband of 16KHz and a bandpass filter 13 having a passband of 46KHz. The signal that has passed through the bandpass filter 12 is
Envelope detection is performed by the detector 14, and its output is given to the subtracter 16. On the other hand, the signal that has passed through the bandpass filter 13 is subjected to envelope detection by a wave detector 15, and its output is also given to a subtracter 16. The subtracter 16 is connected to a changeover switch 18 and an inverting amplifier 17, and the inverting amplifier 17 is connected to a changeover switch 18. The changeover switch 18 is connected to a tracking error output terminal 19. The output of the subtracter 16 is outputted to the tracking error output terminal 19 as a signal with the same polarity, or as a signal with the opposite polarity via an inverting amplifier 17, by a changeover switch 18 that is switched in response to the head switch signal. Ru.

FIG. 2 is a diagram showing video signal tracks formed on the magnetic tape 20 so as to be inclined in the longitudinal direction of the tape, and pilot signals recorded in a superimposed manner as a video signal on each video signal track.

Next, the operation of the tracking control means shown in FIG. 1 will be explained with reference to FIG. During recording, the cyclic frequency generator 2 responds to the leading and trailing edges of the head switch signal to generate four different frequencies f ₁ ,
The pilot signals f ₂ , f ₃ , and f ₄ are generated by switching each field. These four different frequencies
f ₁ , f ₂ , f ₃ , f ₄ are, for example, NTSC (National
When recording a video signal using the Television System Committee) method, f ₁ = 102KHz, f ₂ = 118K
Hz, f ₃ = 164KHz, f ₄ = 148KHz, so that the frequency difference α between f ₁ and f ₂ is equal to the frequency difference between f ₄ and f ₃ , and the frequency difference between f ₂ and f ₄ is The frequency difference is set to be approximately twice α. These pilot signals are superimposed on the video signal, and are recorded by the magnetic head 8 on the magnetic tape 20 by forming a video signal track inclined in the longitudinal direction of the tape in field order, as shown in FIG. . In the figure, video signal tracks F ₁ , F ₂ , F ₃ and F ₄ indicate that pilot signals of frequencies f ₁ , f ₂ , f ₃ and f ₄ are recorded, respectively.

During reproduction, the magnetic head 8 reproduces a signal from the video signal track on the magnetic tape 20, and the reproduced signal is applied to the reproduction amplifier 9 via the rotary transformer 7 and the changeover switch 6, where it is amplified. The output of the regenerative amplifier 9 is applied to a low pass filter 10, and the pilot signal component contained in the regenerated signal is extracted.

Here, for example, as shown in FIG. 2, the magnetic head 8 picks up video signal tracks on the magnetic tape 20.
Considering the case where _F1 is being tracked, the pilot signal component reproduced by the magnetic head 8 includes the side lead effect, in addition to the pilot signal of frequency ₁ superimposed on the video signal track _F1 . A pilot signal superimposed on both adjacent tracks (video signal track F ₂ and video signal track F ₄ in the example of FIG. 2) due to crosstalk or the like is also included at the same time. The magnitude of the pilot signals reproduced from these adjacent tracks increases as the amount of positional deviation of the magnetic head 8 from the center of the video signal track that the magnetic head 8 is tracking increases. When tracking the video signal track _F1 , the pilot signal component extracted by the low-pass filter 10 and the frequency generated by the circulating frequency generator 2
A carrier signal of f _cR = f ₁ is given to the mixer 11,
Frequency f ₂ of one adjacent video signal track F ₂ =
118KHz pilot signal and frequency f _cR = f ₁ = 102K
A signal component having a frequency of 16 KHz, which is the difference in frequency from the carrier signal of Hz, a pilot signal of the other adjacent video signal track F ₄ with a frequency F ₄ =148 KHz, and a carrier signal with a frequency f _cR =f ₁ =102 KHz. A signal component with a frequency of 46KHz is obtained with a frequency difference of . These 16 KHz and 46 KHz signal components are further extracted separately by a band pass filter 12 having a pass band of 16 KHz and a band pass filter 13 having a pass band of 46 KHz. The output of the bandpass filter 12 is subjected to envelope detection by the wave detector 14, and the output level is detected by the magnetic head 8.
It represents the amount of positional shift to the adjacent video signal track _F2 on the right side. On the other hand, the output of the bandpass filter 13 is subjected to envelope detection by the detector 15, and the output level represents the amount of positional deviation of the magnetic head 8 to the adjacent video signal track _F4 on the left side. By passing these two outputs through a subtracter 16, the amount of positional deviation of the magnetic head 8 from the center of the video signal track can be obtained.

However, when the magnetic head 8 is tracking the video signal track _F1 or the video signal track _F3 , and when it is tracking the video signal track _F2 or the video signal track _F4 ,
Since the frequency difference between the left and right adjacent tracks is inversely related, the output of the subtracter 16 has an opposite polarity. Therefore, by providing an inverting amplifier 17 for inverting the polarity and switching the changeover switch 18 by the head switch signal, when the magnetic head 8 tracks the video signal track _F2 or the video signal track _F4 , the subtracter 16 It is necessary to invert the polarity of the output.

In this way, a tracking error signal having a voltage corresponding to the amount of positional deviation of the magnetic head 8 from the center of the video signal track is output to the tracking error output terminal 19, and this signal is fed back to the capstan motor. A servo control system is formed and good tracking is performed.

As for tracking control, phase control using a tracking error signal has been described above, but in a magnetic recording/reproducing device using a pilot signal, tracking control, that is, control during playback of the capstan motor that drives the tape, is as follows. This phase control and the speed control using the output pulse signal of the generator for detecting the speed of the capstan motor are performed.

By the way, in contrast to the magnetic recording/reproducing apparatus using a control signal, the only magnetic recording/reproducing apparatus using a pilot signal on the market is one that records/reproduces at a single tape speed. Naturally, therefore, such devices had the drawback of not being provided with a mode discrimination device for determining tape speed.

[Summary of the Invention] The present invention has been made based on the above background, and therefore, the main purpose of the present invention is to record at multiple tape speeds in a magnetic recording/reproducing device using a pilot signal. - When a device capable of playback is configured, when a signal is played back by this magnetic recording/playback device, mode discrimination of the tape speed during recording and tracking phase control are performed alternately at regular intervals. An object of the present invention is to provide a magnetic recording/reproducing device that can perform the following functions.

To summarize this invention, during playback, the speed control of the capstan motor is always performed, phase control is performed by detecting a tracking error signal from the playback signal only for a certain period, and the capstan motor is controlled for the next certain period. The phase control of the stun motor is not performed, and the circuit for detecting the tracking error signal described above is used as a circuit for detecting the pilot signal from the reproduced signal.
This output is used as one input, and the output pulse signal output from the generator for speed detection of the capstan motor is obtained from the other input. The tape speed is determined by counting the number and comparing the counted value with a predetermined reference value.
This is a magnetic recording and reproducing device that alternately performs phase control of a capstan motor and mode discrimination of tape speed at regular intervals.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

[Embodiments of the Invention] Figures 3A and 3B show the relationship between the pattern of a video signal track formed on a magnetic tape and a pilot signal recorded on the video signal track in a superimposed manner with the video signal. FIG. Third
Figure A shows the pattern of the video signal track 22a when the video signal is recorded at a relatively high tape speed _v1 . The tracking pitch along the longitudinal direction of the magnetic tape 21a at this time is defined as _p1 . Third
Figure B shows the video signal track 22 when the video signal is recorded at a relatively low tape speed v ₂ (v ₁ > v ₂ ).
The pattern of b is shown. Magnetic tape 21 at this time
Let p ₂ be the track pitch along the length of b. In each of the video signal tracks 22a and 22b shown in FIGS. 3A and 3B, a pilot signal is recorded superimposed on the video signal as described above. The frequency of the pilot signal is set to be considerably lower than the frequency of the video signal. now,
As pilot signals, different frequencies f ₁ , f ₂ , f ₃ ,
It is assumed that f ₄ (the frequencies are in the order of f ₁ < f ₂ < f ₄ < f ₃ ) is used. Then, as shown in the figure, pilot signals of different frequencies f ₁ , f ₂ , f ₃ , and f ₄ are sequentially recorded on the video signal tracks 22a and 22b so as to be superimposed on the video signal. Therefore, in FIGS. 3A and 3B, for example, a pilot signal of frequency f ₁ is recorded every fourth video signal track, in other words at a pitch interval of 4×p ₁ (or 4×p ₂ ). ing.

FIG. 4 is a block diagram showing the configuration of an embodiment of the present invention. Note that in FIG. 4, the same parts as in FIG. 1 are given the same reference numbers. Fourth
The difference between this figure and the block diagram of the conventional magnetic recording/reproducing apparatus shown in FIG. 1 which performs tracking control using pilot signals is that the detector 14 is used to determine the tape speed mode.
The f ₁ detector 27 is connected to the comparator 29, and the changeover switch 1 is connected to the f ₁ detector 27.
8 is sample hold 32 and changeover switch 3
1, and the sample hold 32 is connected to the changeover switch 31. In the figure, input terminals 23 to 26 are used to detect a tracking error signal and perform phase control of the capstan motor during playback, or to input one type of pilot signal (here, as an example, a pilot signal with a frequency _f1 ). A switching signal is provided that specifies whether to detect the tape speed mode and determine the tape speed mode.

First, the period during which the tape speed mode is determined will be explained. The video signal including the pilot signal reproduced by the magnetic head 8 is transferred to the rotary transformer 7, the changeover switch 6, and the reproduction amplifier 9.
A pilot signal component is extracted from the reproduced signal.
During the period when the tape speed mode is being determined,
Circulating frequency generator 2 always generates only a pilot signal of frequency _f2 . This reproduced pilot signal and the pilot signal of frequency f ₂ from the circulating frequency generator 2 are input to a mixer 11, and a signal component having a frequency corresponding to the frequency difference between the two signals is output. Now, let the frequency of the reproduced pilot signal be f ₁ =
102KHz, _f2 =118KHz, _f3 =164KHz, _f4 =148KHz
Then, the frequency difference between these regenerated pilot signals and the pilot signal of frequency f ₂ =118KHz from the circulating frequency generator 2 is f ₂ −f ₁ =16KHz, f ₂ −f ₂
= 0 KHz, f ₃ - f ₂ = 46 KHz, and f ₄ - f ₂ = 30 KHz, so the output of the mixer 11 is passed through a bandpass filter 12 having a pass band of 16 KHz, and the detector 14 performs envelope detection to detect f ₁ . A pilot signal of frequency f ₁ is detected by the device 27 and outputted to the comparator 29 . A mode signal indicating the current tape speed is given to the f ₁ detector 27 from the input terminal 33, and the frequency f ₁
The output of the detection signal is controlled. On the other hand, the input terminal 28 has an output pulse signal (hereinafter referred to as "CP-FG") of the generator for speed detection of the capstan motor.
is given. Before being applied to the input terminal 28, the CP-FG is amplified and waveform shaped as necessary. CP-FG given from input terminal 28 and
The pilot signal detection output of the frequency f ₁ output from the f ₁ detector 27 is provided to a comparator 29, respectively. Comparator 29 includes at least a counter and a comparator. The counter of the comparator 29 counts the number of pulses of CP-FG applied from the input terminal 28. Also, this counter is f ₁ detector 2
It is reset every time there is a pilot signal detection output of frequency f ₁ given from 7. Therefore, the counter of the comparator 29 measures the interval between when a signal indicating that a pilot signal of a certain frequency f ₁ has been detected is given and when a signal indicating that a pilot signal of the next frequency f ₁ has been detected is given. , the number of CP-FG pulses will be counted. In other words, the counter has a detection interval of the pilot signal of frequency f ₁ , CP
-The number of pulses in FG is used as a coefficient. Then, the count output of this counter is compared, for example, by a comparator to see whether it is larger or smaller than a predetermined reference value. Then, the tape speed during recording of the magnetic tape is automatically determined based on the comparison result, and is output as a determination output from the output terminal 30. This determination output is then applied to a mode switching circuit (not shown), etc., and the playback mode is switched to the determined mode.

The operation of the f ₁ detector described above will be explained in more detail with reference to FIGS. 5A and 5B. Now, the two tape speeds v ₁ and v ₂ shown in FIGS. 3A and 3B
Suppose that the relationship is v ₁ = 2v ₂ . Figure 5A shows
Magnetic tape recorded at tape speed v ₁
FIG. 3 is a diagram showing the operation of the f ₁ detector when playing back with v ₂ . In FIG. 5A, (a) represents the track pattern and the scanning locus of the magnetic head 80, and the broken line represents the scanning locus of the center of the magnetic head 80. In FIG. (b) shows, as an example, the envelope of the reproduction pilot signal of frequency f ₁ when the width of the magnetic head 80 is 0.6 times the track pitch, and the vertical dashed lines indicate the switching timing of the head switch,
The horizontal dashed line represents the threshold for detecting the pilot signal at frequency _f1 . T is the time interval between head switch switching. In case (b), a pilot signal of frequency f ₁ is reproduced from the same video signal track over a period of 4T, and during this period 2
At this time, the reproduced output of the pilot signal of frequency _f1 exceeds the threshold.

When the tape speed during playback is _v2 , the input terminal 33
After detecting the pilot signal of frequency f ₁ as shown in (d) using the mode signal given by
During the 2T period, the detection signal of the pilot signal of frequency _f1 is not output. Therefore,
As shown in (c), a detection signal of frequency f ₁ is output once every time one video signal track on which a pilot signal of frequency f ₁ is recorded is scanned. FIG. 5B shows the scanning locus of the f ₁ detector when a magnetic tape recorded at tape speed v ₂ is reproduced at tape speed v ₁ , and the broken line shows the operation of the magnetic head 81. In FIG. 5B, (a) represents the track pattern and the scanning locus of the center of the magnetic head 81. In FIG. As an example, (b) shows the envelope of the reproduction pilot signal of frequency f ₁ when the width of the magnetic head 81 is 2.4 times the track pitch, where the vertical broken line is the switching timing of the head switch, and the horizontal broken line is the frequency. It represents the threshold for detecting the pilot signal of _f1 . T is the time interval between head switch switching. tape speed
When reproducing at v ₁ , the reproduction output of the pilot signal of frequency f ₁ from the same video signal track on which the pilot signal of frequency f ₁ is recorded exceeds the threshold only once.

When the tape speed during playback is v ₁ , the input terminal 33
There is no period during which the detection signal of frequency f ₁ is not outputted due to the mode signal given from . Therefore, as shown in (c), a detection signal of frequency f ₁ is output once every time one video signal track on which a pilot signal of frequency f ₁ is recorded is scanned.

The operation of the comparator 29 is shown in FIGS. 3A and 3B.
This will be explained in more detail with reference to the drawings. As shown in FIG. 3A, when the tape speed is _v1 and the track pitch of the video signal track 22a is _p1 , the CP counted by the counter (not shown) of the comparator 29
- Let the count number of FG be N ₁ . Similarly, 3rd B
Let _N2 be the count number of CP-FG in the case shown in the figure. Then, the relationship between the track pitches p ₁ and p ₂ and the counts N ₁ and N ₂ of CP-FG is N ₁ /N ₂ = p ₁ /p ₂
It is. Therefore, for example, by setting the predetermined reference value to (N ₁ + N ₂ )/2, CP-
If the FG count is larger than this reference value, it can be determined that the track pitch of the video signal track is _p1 and the running speed of the magnetic tape during recording is _v1 . Conversely, from this standard value, CP−FG
If the count number is small, it can be determined that the running speed of the magnetic tape during recording is _v2 .

As already explained, the frequency of the pilot signal with frequency _f1 is set to a considerably lower frequency (several 100 KHz or less) compared to the frequency of the video signal, so the influence of the azimuth effect of the head during playback is It has a small azimuth, so it can be played back even if the head has a different azimuth than when recording.

At this time, only speed control is performed on the capstan motor. The changeover switch 31 is connected to the input terminal 2
B by the switching signal indicating that it is the period in which the tape speed mode determination given from 5 is being performed.
The phase of the capstan motor is controlled by the sample hold 32, which indicates that it is the period during which the tape speed mode is determined, which is applied from the input terminal 26. The tracking error signal immediately before switching from the period in which the tape speed is being determined to the period in which the tape speed mode is being determined is sampled and held, and is output to the output terminal 19.

Next, a period during which phase control of the capstan motor is performed will be explained. Input terminal 23-2
6 is given a switching signal indicating that it is a period in which phase control of the capstan motor is being performed. A switching signal applied from the input terminal 23 causes the cyclic frequency generator 2 to sequentially generate different frequencies f ₁ , f ₂ , f ₃ , f in response to the leading and trailing edges of the head switch signal input to the video signal input terminal 1. Similarly to the conventional example shown in _FIG . 3
A tracking error signal is outputted to an output terminal 19 via 1. This tracking error signal controls the phase of the capstan motor.

Regarding the above operations, FIG. 6 shows a timing chart when the tape is reproduced at the same tape speed as the recording speed. In the figure, (a) is the head switch signal, (b) is the pilot signal recorded on the video signal track scanned by the magnetic head,
(c) is a switching signal for switching between the period for determining the tape speed mode and the period for controlling the phase of the capstan motor, (d) is the pilot signal output from the circulating frequency generator 2, and (e) is the frequency f. ₁ detection signal.

As shown in Figure 6c, there is a period in which a tracking error signal is detected from the reproduced signal to control the phase of the capstan motor at regular intervals, and a pilot signal with a frequency _f1 is detected from the reproduced signal. The period in which the tape speed mode is determined is alternately repeated. During the period when the tape speed mode is being determined, the capstan motor is controlled only in speed and not in phase. However, if this period is short enough, even if the capstan motor is only under speed control, the phase shift will be small, and as shown in Figure 6d, the phase difference of the capstan motor will be determined by determining the tape speed mode. If the frequency of the pilot signal generated from the cyclic frequency generator 2 and the pilot signal reproduced from the video signal track scanned by the magnetic head are set to be the same when switching to control mode, the tape speed mode can be determined. When switching from phase control to phase control of the capstan motor, phase control of the capstan motor can be smoothly performed.

In the above embodiment, the detection of the pilot signal of frequency f ₁ was used to determine the tape speed mode, but the detection of the pilot signal of frequency f ₃ and the frequency f ₂
By detecting the pilot signal of frequency f ₃ from the output of the detector 15 which has envelope-detected the 46KHz signal component of the frequency difference between the pilot signals, the detection output of the pilot signal of frequency f ₁ and the pilot signal of frequency f ₃ is Alternatively, the counter may be reset by inputting it to the comparator 29 via an OR gate. In this case, the tape speed mode can be determined with half the moving distance of the embodiment shown in FIG. Further, in this case, the predetermined reference value to be compared with the output of the counter of the comparator 29 may be, for example, (N ₁ +N ₂ )/4.

Furthermore, in each of the above embodiments, when only the pilot signal of frequency f ₁ is used from among the four pilot signals of different frequencies f ₁ , f ₂ , f ₃ , f ₄ , the pilot signal of frequency f ₁ and The case where a pilot signal of frequency _f3 is used has been explained. However, it is not limited to this, and the pilot signal of other frequency _f2 ,
The pilot signal with frequency f ₄ may be used alone, or pilot signals with different frequencies f ₁ , f ₂ , f ₃ and f ₄ may be used in appropriate combination.

Furthermore, in each of the above embodiments, four pilot signals having different frequencies are used as the pilot signals because they conform to the format of existing magnetic recording and reproducing apparatuses that use pilot signals. Therefore, even if the number of pilot signals is different from the above four signals, the present invention can be similarly applied to determine the mode.

Further, in each of the above embodiments, in determining the mode of the tape speed, the detection interval of the pilot signal of frequency f ₁ or the pilot signal of frequency f ₁ and the pilot signal of frequency f ₃ is determined based on the CP-FG signal applied from the input terminal 28. Although the method of counting the number of pulses with the counter of the comparator 29 and comparing it with the reference value was shown,
Instead of CP-FG, a suitable clock signal and a mode signal indicating the tape speed at that time are sent to the comparator 29.
, and compare the number of clocks at the detection interval of the pilot signal of frequency ₁ or the pilot signal of frequency f ₁ and the pilot signal of frequency f ₃ with a reference value according to the tape speed at that time. good.

Further, in each of the above embodiments, the comparison is performed digitally, but an analog comparison method or a comparison method using a microcomputer may be used.

[Effects of the Invention] As described above, according to the present invention, the number of pulses of the output pulse signal output from the generator for speed detection of the capstan motor is counted at the detection interval of the pilot signal, and the counted value is calculated. Since the mode discriminating device is capable of discriminating the tape speed mode by comparing it with a predetermined reference value, a pilot signal for tape running control generated in synchronization with the rotation of the rotating magnetic head is applied to the video signal track of the magnetic tape. In a magnetic recording/playback device that records and plays back video signals superimposed on a video signal, it is possible to automatically determine the tape speed mode at the time of recording and playback when recording and playing back at multiple tape speeds. In addition, since the tracking error signal detection circuit is used to time-divisionally detect the tracking error signal and the pilot signal for mode discrimination, tracking phase control and tape speed mode discrimination are possible. A magnetic recording/reproducing apparatus that can perform the operations alternately at regular intervals and has such a function can be constructed at low cost using a small number of parts.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a conventional magnetic recording/reproducing apparatus that performs tracking control using a pilot signal. FIG. 2 is a diagram showing a video signal track formed on a magnetic tape and a magnetic head. FIGS. 3A and 3B are diagrams showing the relationship between the pattern of video signal tracks formed on the magnetic tape at tape speeds v ₁ and v ₂ , respectively, and the pilot signal recorded superimposed on the video signal. . FIG. 4 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 5A is a diagram showing the operation of the f ₁ detector when a magnetic tape recorded at tape speed v ₁ is reproduced at tape speed v ₂ . Fifth
Figure B is a diagram showing the operation of the _f1 detector when a magnetic tape recorded at tape speed _v2 is reproduced at tape speed _v1 . FIG. 6 is a time chart of the operation of the embodiment shown in FIG. In the figure, 2 is a circulating frequency generator, 10 is a low-pass filter, 11 is a mixer, 12 and 13 are breadth filters, 14 and 15 are detectors, 16 is a subtracter, 17 is an inverting amplifier, and 27 is an f ₁ detection vessel, 2
9 is a comparator, and 32 is a sample hold.

Claims (1)

[Scope of Claims] 1 Recording and playback are possible at multiple tape speeds, and a pilot signal generated in synchronization with the rotation of a rotating magnetic head is superimposed on the video signal to be recorded to generate the video signal on the magnetic tape. In a magnetic recording and reproducing apparatus of a type in which recording is performed on a track, a detecting means for detecting the superimposedly recorded pilot signal from a reproduced signal and detecting a tracking error signal during reproduction, and a detecting means for detecting a tracking error signal; A magnetic recording and reproducing apparatus comprising means for measuring the detection interval time of the pilot signal to be detected, and comparison and determination means for comparing the detection interval time with a predetermined reference value and determining the tape speed of the magnetic tape. a mode discriminating device; a driving means for controlling the rotational phase of a capstan motor that drives the magnetic tape based on the output of the detecting means; and a mode discriminating device and a tracking error signal detecting unit that alternately causes the detecting means to perform mode discrimination and tracking error signal detection at regular intervals. 1. A magnetic recording and reproducing device, comprising: switching means for switching between the two modes. 2. The comparison and discrimination means performs the determination by counting the number of output pulses output from the speed detection generator provided in the capstan motor during the detection interval of the pilot signal detected by the detection means. 2. The magnetic recording and reproducing apparatus according to claim 1, wherein the counted value is compared with a predetermined reference value to determine the tape speed of the magnetic tape.