JPH0795845B2 - Magnetic signal reproducing device - Google Patents

Description

The present invention relates to a magnetic signal reproducing apparatus, and more particularly, to a magnetic signal reproducing apparatus capable of realizing noise-free slow reproduction by using a storage means such as a digital memory. Regarding

[Prior Art] A magnetic recording / reproducing apparatus (hereinafter, referred to as "VTR") capable of recording and reproducing a video signal (or a television signal) will be described below as a typical example of the magnetic signal reproducing apparatus. . However, it should be pointed out in advance that the present invention is also intended for a reproduction-only device having no recording function.

Conventionally, there is known a VTR in which a control track is provided on a magnetic tape, a control signal is recorded and reproduced on the control track, and the running control of the magnetic tape is performed by the control signal.

As one of the methods for performing slow playback without noise in such a control signal type VTR,
There is a tape drive that is intermittently driven by repeating running and stopping during slow playback. In such a method, in order to obtain a reproduced image without noise, it is necessary that the positional relationship between the recording track and the rotary head is always within a range where noise does not appear on the reproduced screen when the tape is stopped.
In order to obtain the positional relationship, the control signal reproduced in the tape running state is used as the track position information,
The tape running amount after the control signal is detected is controlled to stop the tape at a position where noise does not appear on the screen.

FIG. 4 is a diagram for explaining the tape running control in the slow playback as described above in the conventional VTR.
In the figure, FIG. 4 (a) shows the torque output Mt of the tape drive motor that drives the capstan shaft used for tape running.
4 (b) shows the tape speed V, and FIG. 4 (c) shows the reproduction output of the control signal C recorded at the running position of the tape. As is apparent from FIG. 4, in the control method of the conventional device,
The magnetic tape is accelerated from time t ₀ to time t ₁ and then run at a constant speed. When the control signal C is detected at time t ₂ , braking is started after a delay time (t ₃ −t ₂ ) and the tape speed is increased. The braking is terminated at time t ₄ when V is almost 0, and the magnetic tape is stopped.

Here, the above-mentioned delay time (t ₃ −t ₂ ) is called a tracking delay time, and by increasing or decreasing this time, the tape feed amount after detecting the control signal C increases or decreases.
And this time is usually adjusted by the VTR user by the variable resistor, so that the magnetic tape can be stopped at the position where the reproduced image is the best, that is, the optimum tape position where there is no noise. Has been

[Problems to be Solved by the Invention] However, there is a drawback in that the above-mentioned work of adjusting the tracking delay time is troublesome for the user. Furthermore, since the relative speed between the magnetic tape and the rotary head changes between the running state and the stopped state of the magnetic tape, the cycle of the reproduction horizontal synchronizing signal changes, and the reproduction screen is displayed each time the magnetic tape is driven. There was also a shortcoming that it wobbled sideways.

Furthermore, in order to realize slow reproduction without blur, it is necessary to reproduce by two magnetic heads having the same azimuth when the magnetic tape is stopped. Therefore, two magnetic heads for normal recording and reproduction are required. In addition, there is a drawback that one or two throw magnetic heads are separately required.

Therefore, the main object of the present invention is to eliminate the problems of the prior art, and to provide noiseless slow reproduction without lateral movement or blurring without performing tracking adjustment and to provide a slow magnetic head. It is an object of the present invention to provide a magnetic signal reproducing device that can be realized without any problems.

[Means for Solving the Problems] In a magnetic signal reproducing apparatus according to the present invention, a rotary drum is provided with first and second magnetic heads having different azimuths, and the heads are switched by a head switching signal. And a helical scan method of obliquely scanning the magnetic tape, and is a magnetic signal reproducing device for reproducing a magnetic tape on which an information signal and a reference signal for notifying the running state of the magnetic tape at a predetermined cycle are recorded. The magnetic tape in response to the output of the slow reproduction command means for reproducing the information signal at a speed slower than the recording speed (normal running speed) when the information signal is recorded on the magnetic tape. Drive means for continuously traveling at a speed lower than the normal traveling speed, and the first or second magnetic head Based on the storage means for storing the reproduced information signal for one field generated and the reference signal and the head switching signal, the number of predetermined pulses generated in response to the head switching signal is counted after the reference signal is detected. Accordingly, the position information detecting means for detecting the relative positional relationship between the magnetic tape and the first and second magnetic heads, and the position detecting means when the magnetic tape is continuously driven at a low speed. The reproduction information signal is written into the storage means and the storage means according to the fact that the relative positional relationship with the first and second magnetic heads has a specific positional relationship predetermined according to the slow speed. In response to the writing / reading control means for controlling the reading of the reproduction information signal from the writing / reading control means, the first or the first during the writing period. Deriving a reproduction information signal reproduced by the magnetic head as an output signal, during readout period is intended to include a switching means for deriving the information signal stored in the storage means as an output signal.

[Operation] In slow reproduction according to the present invention, the magnetic tape is continuously driven at a lower speed than the normal reproduction tape traveling speed. Then, a reproduction signal having a good reproduction level reproduced by the magnetic head in a predetermined period is output as a reproduction signal and written in the storage means. Then, during the period when the reproduction level is low, the signal stored in the storage means is read and output as a reproduction signal.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram of an embodiment of the present invention. The VTR recording and reproducing system shown in FIG.
Head-type helical scan, 1 field per 1
It consists of trucks.

First, the configuration will be described with reference to FIG. 1. In FIG. 1, only the VTR reproducing system relating to the features of the present invention is shown, and the recording system is omitted.

The reproduction outputs of the rotary magnetic heads 1a and 1b are given to the head amplifiers 2a and 2b, respectively. The head amplifiers 2a and 2b amplify the reproduction signals output from the rotary magnetic heads 1a and 1b, respectively. The respective outputs of the head amplifiers 2a and 2b are selected by the switch 3 which is switched according to the head switching signal HSW and are given to the reproduction processing circuit 5. The reproduction processing circuit 5 performs reproduction signal processing on a luminance signal and a chrominance signal included in the reproduction signal and outputs a reproduction video signal. The reproduction video signal processed by the reproduction processing circuit 5 is supplied to one terminal 91 of the switch 9 and also to the A / D converter 6.

The A / D converter 6 converts the reproduced video signal into a digital signal, and supplies the converted digital signal to the memory 7. As the memory 7, a digital memory or the like capable of storing a video signal for one field is used and constitutes a storage means. The digital signal read from the memory 7 is
It is given to the D / A converter 8 and converted into an analog signal.
This analog signal is applied to the other terminal 92 of the switch 9 described above. This switch 9 is switched to the output side (terminal 91 side) of the reproduction processing circuit 5 when writing the digitized video signal in the memory 7, and when the digital signal is read from the memory 7, D The reproduction video signal is output from the output terminal 100 by switching to the output side (terminal 92 side) of the / A converter 8.

The aforementioned head switching signal HSW is also given to the waveform shaping circuit 10. The waveform shaping circuit 10 outputs a pulse signal having a relatively short width at the rising and falling points of the head switching signal HSW. The pulse signal P ₀ output from the waveform shaping circuit 10 has a set input terminal of the flip-flop 11, the first timing circuit 13 and the second timing circuit 16
And given to. The slow reproduction command signal SL input to the input terminal 32 is supplied to the reset input terminal of the flip-flop 11. This slow playback command signal SL is AND gate
It is also given to one input terminal of 12. The Q output of the flip-flop 11 is applied to the other input terminal of the AND gate 12.
The output P ₁ of the AND gate 12 is given to the first timing circuit 13, the frequency divider 21, the frequency divider 26 and the inverter 14.

The reproduction control signal CTL is input to the input end of the switch 17, and the output P ₂ of the first timing circuit 13 is the switch 17
Is given as a control signal. The output of the switch 17 is input to the second timing circuit 16 together with the slow speed command signal Vs. The output P ₃ of the second timing circuit 16 is given to one input terminal of the OR gate 15, and the output of the inverter 14 is inputted to the other input terminal of the OR gate 15. OR gate 15
The output P _{4 of} is supplied to the memory 7 as a write signal and to the switch 9 as a switching signal.

The output of the frequency divider 21 obtained by inputting the output of the reference signal generator 20 such as a crystal oscillator to the frequency divider 21 and the reproduction control signal CTL are input to the phase comparator 22. Here, the reproduction control signal CTL is, for example, position information of the same frequency as the head switching, which is recorded on the tape (not shown) so that the magnetic head and the tape have a certain phase relationship during recording. It is a signal obtained by reproducing the signal during reproduction.

The output of the frequency generator 19 that generates a frequency proportional to the number of revolutions of the tape running motor 18 that drives the magnetic tape is applied to the frequency / voltage converter 27 via the frequency divider 26. The phase comparison error output of the phase comparator 22 and the output of the frequency / voltage converter 27 are input to the adder 23, and the obtained deviation
Ve is amplified by the deviation amplifier 24 and given to the motor drive circuit 25 to drive the tape drive motor 18. Divider 21 and
A slow speed command signal Vs is given to 26, and each frequency division value changes according to the command.

FIG. 2 is a time chart for explaining the operation of FIG. 1, and the specific operation of the embodiment of the present invention will be described with reference to FIGS. 1 and 2. 2 (a) shows the time, and FIG. 2 (b) shows the head switching signal HSW, which is reproduced by the magnetic heads 1a and 1b during the low level and high level periods, respectively. 1
It is a field period.

Since the normal reproduction mode is set before the time t ₀ , the slow reproduction command signal SL is at the low level as shown in FIG. 2D, and becomes the high level after the time t ₀ . However, the output Q of the flip-flop 11 which operates by the rising of the set input and the reset input is as shown in FIG. 2 (e).
Since it shows a low level from time t ₀ to the next head switching time t ₁ , the output P _{1 of the} AND gate remains low level until time t ₁ as shown in FIG. 2 (f). Is. Signal P given to frequency divider 21 and frequency divider 26
_{While 1} (the output of the AND gate 12) is at the low level, each of the frequency dividers 21 and 26 is set to a value such that the normal reproduction running control is performed on the magnetic tape. The tape is controlled to run normally until time t ₁ .

Thus, because until the time t ₁ is output P ₁ of the AND gate 12 is at a low level, the output of inverter 14 becomes a high level until the time t _1, the output P ₄ of the OR gate 15 also FIG. 2 ( Similarly, as shown in k), it becomes high level until time t ₁ . The output P _{4 of the} OR gate 15 is applied to the memory 7 and serves as a write / read control signal and a switching signal for the switch 9. While the output signal P ₄ of the OR gate 15 is at the high level, the memory 7 is in the writing state, and the switch 9 is switched to the contact 91 side. As a result, the reproduction signal processed by the reproduction processing circuit 5 is digitized by the A / D converter 6 and written in the memory 7, and at the same time, is input as a reproduction video signal to the output terminal 100 via the switch 9. . That is, according to FIG. 2, time t ₁
A reproduction signal for one field by the head 1a which ends with is written in the memory 7.

Then, after the time t ₁ , the output P ₁ of the AND gate 12 changes to the high level, but in that case, the frequency division values of the frequency dividers 21 and 26 are the frequency division values during the normal reproduction up to the time t _1. Is set to a value different from. That is, in response to the slow speed command signal Vs given to the frequency dividers 21 and 26, for example, when a slow speed command of 1/3 times the normal reproduction traveling speed is given, the frequency of the output signal of the frequency divider 21 is increased. Is 1 / when running normally
The tape drive motor 18 is rotationally controlled because the frequency division value of the frequency divider 26 becomes three times and the frequency division value of the frequency divider 26 becomes one-third the value during normal reproduction traveling. As a result, the tape is controlled to run at 1/3 the speed of normal playback running. That is, from time t ₁ through the servo pull time, tape will perform low-speed traveling.

On the other hand, the output P ₁ of the AND gate 12 is the output of the waveform shaping circuit 10.
It is given to the first timing circuit 12 together with P ₀ . The first timing circuit 13 starts counting the number of pulses of the pulse signal P ₀ when the output P ₁ of the AND gate 12 rises from a low level to a high level, and the counted value reaches a predetermined value N ₀ . in time t _2, the signal P _2, as in the FIG. 2 (g), varying therefrom to the low level to the high level. Here, the predetermined value N ₀ is set to a time required to realize the low speed traveling control after the time t ₁ , that is, a value longer than the servo pull-in time. Therefore, at the time t ₂ , the tape has already reached a stable low speed. It is running.

The output P ₂ of the first timing circuit 13 serves as a switching signal of the switch 17, and switches when the output P ₂ is at high level.
17 becomes conductive, and the reproduction control signal CTL is applied to the second timing circuit 16 after time t ₂ .
Accordingly, as shown in FIG. 2 (h), the time to the time t ₃
t ₂ first play control signal CTL1 is obtained later, the second
Since the figure is a slow running speed to 1/3 of the normal playback speed, the next reproduction control signal CTL2 appears at time t ₇ after 6 field period. In addition to the output of the switch 17, the output P ₀ of the waveform shaping circuit 16 and the slow speed command signal Vs are given to the second timing circuit 16. Then, as a result, the output P ₃ is derived.

FIG. 3 will be used to explain how the output P ₃ of the second timing circuit 16 is guided. FIG. 3 is an illustrative view showing the relationship between the recording track on the magnetic tape and the scanning locus of the magnetic head. In FIG. 3, 50 is a magnetic tape, and 51 is the running direction of the magnetic tape. Recording tracks T1 and T3 on the tape are recorded by the head 1a, and recording tracks T2 and T4 are recorded by the head 1b.

As described above, since already the magnetic tape at the time t ₂ is controlled continuous stable low-speed running, the time t ₂ later,
There is a fixed phase relationship between the reproduction control signal obtained as the output of the switch 17 and the head switching signal HSW. Therefore, the playback control signal obtained at time t ₃
First appearing in the CTL1 after, in response to the high level of the head switching signal HSW from time t _4, the scanning by the head 1b is performed. In one field period from the time t _4, the head 1b scans the track indicated by a dashed line A of example FIG. 3 (a).

Assuming now that the heads 1a and 1b are a pair of heads having different azimuths, the recording tracks T1, T3 can be obtained from the head 1a, and the recording tracks T2, T4 can be obtained from the head 1b, respectively. . Therefore, in the scanning for one field period by the head 1b from the time t ₄ ,
Since the track T1 is almost scanned, sufficient reproduction output cannot be obtained. Then, from the time t _5, corresponding to the second head switching point of time t ₃ after the scanning by the head 1a is carried out. In one field time (t ₅ -t _4), the tape (1/3) L _P: Since running (L _P mileage tape is traveling in one field period of normal reproduction running), the time t _The scanning locus by the head 1a in the one field period from ₅ is as shown by the dotted line B in FIG. 3 (a), and the head 1a starts from the track T1 and shows a sufficient reproduction signal over the one field period as shown by the horizontal stripes. Is in a state of being able to obtain. Therefore, in the second timing circuit 16, as shown in FIG. 2 (i), when the time t ₅ at which two pulse signals P ₀ appearing after the reproduction control signal CTL1 at time t ₃ is counted is reached, the time is reached. It functions to output the high-level signal shown in FIG. 2 (i) only for one field period up to t ₆ . Since the output P ₃ of the second timing circuit 16 is applied to one input end of the OR gate 15, the output P ₄ of the OR gate 15 also has a field period (t ₆ High level will be output over -t ₅ ). Therefore, the reproduction signal from the head 1a for one field period (t ₆ −t ₅ ) is processed by the reproduction processing circuit 5, written into the memory 7 via the A / D converter 6, and via the switch 9. It is output to the output terminal 100 as a reproduced video signal.

Time t ₆ after the output P ₃ of the second timing circuit 16 is at a low level, and since the output of the inverter 14 is at a low level continuously after time t _1, at time t ₆ after the OR gate 15
Output P ₄ becomes low level, the switch 9 is switched to the terminal 92 side, the content of the memory 7 is read, and the signal analogized by the D / A converter 8 is output from the terminal 100 as a reproduced video signal. .

Then, at time t ₇ , when the reproduction control signal CTL2 is obtained as the output of the switch 17, the same operation as described above is repeated. That is, the dotted line in FIG. 3 (a)
Only one field period (t ₉ -t ₈₎ carried out with the scanning by the head 1a shown in B1, the output P ₃ of the second timing circuit 16 outputs a high level again. And, for the time t ₃ or later, repeat the same operation. By the above operation,
In one embodiment of the present invention, noiseless slow reproduction can be performed.

It should be noted that in the above embodiment, what is written in the memory 7 during low speed traveling is the reproduction signal of the one field period by the head 1a, but the reproduction signal of the one field period by the head 1b may be written. Needless to say.

Further, in the above-described embodiment, what is written in the memory 7 during low-speed running is a reproduction signal for one field period by one of the heads, and the track for giving the reproduction signal is every other track. However, it is possible to eliminate such track jumps. That is, in the second timing circuit 16, the first reproduction control signal input
The number of pulses of the pulse signal P ₀ after CTL1 is set to a predetermined value N ₁ (second
It is as described above that the output P ₃ shows a high level during one field period (t ₆ −t ₅ ) by the head 1 a after counting (two in the example of FIG. 3 and FIG. 3). The number of pulses of the pulse signal P ₀ after CTL1 is counted by a predetermined value N ₂ (N ₂ > N ₁ ). That is, according to the examples of FIGS. 2 and 3, in the one field period after the time t ₀ when N ₂ = 5 is counted, the head 1b scans as shown by the dotted line D in FIG. 3 (b). The track is formed, and scanning is performed so that a sufficient reproduction signal is obtained from the track T2 as shown by vertical stripes. Therefore, the second timing circuit 16 outputs a high level signal as the output P ₃ for one field period shown by the dotted line in FIG. 2 (i). As a result, the output P ₄ of the OR gate 15 also outputs a high level for one field period after the time T ₀ , and writing to the memory 7 is performed during this high level period. As a result, it is possible to eliminate tracks that are missing as information during slow reproduction, and it is possible to obtain a reproduced image with smooth changes.

Further, in the above-described embodiment, the guard bandless recording track has been described, but even in the recording state in which the guard band exists, if the guard band width is smaller than the recording track width, the same effect as described above is obtained. . For example, in the state of azimuthless recording, a guard band generally exists, but noiseless reproduction can be performed as described above regardless of the presence of this guard band. Further, not only the azimuth recording, but also the azimuthless recording state, the noiseless slow reproduction can be performed as described above.

Further, in the above embodiment, the VTR having two heads has been described, but the number of heads is not limited to two, and more heads may be provided.

Further, the present invention is not limited to the case where one field consists of one track, and a channel division type VT in which a signal of one field is divided into, for example, frequency bands and recorded in a plurality of tracks is the same as the above embodiment. The effect of can be obtained.

Further, even in a segment type VTR that records a signal of one field by dividing it into a plurality of tracks, when writing information from a recording track to a memory at the time of slow reproduction, there is no missing track, It is possible to obtain the same effect as that of the above-mentioned embodiment.

Furthermore, in the above embodiment, the analog recording system for recording the analog signal on the magnetic tape is used. However, even in the VTR of the digital recording system for recording the digital signal,
This invention can be applied.

Incidentally, in the above embodiment, in order to detect the running state of the magnetic tape, the reproduction control signal during low speed running was used, but the reference signal serving as a reference is not limited to the reproduction control signal, A signal having a fixed phase relationship with the head switching signal during low speed traveling, such as a cue signal or a pilot signal, may be used as the reference signal.

[Effects of the Invention] As described above, according to the present invention, in slow reproduction, the tape is continuously driven at a lower traveling speed than that during normal traveling at a low speed, and the tape reproduced from the tape during the low speed traveling. After the position information signal, the number of times of head switching is counted a predetermined number, a head for which a reproduction signal of a sufficient level is obtained over a predetermined period is detected, and the reproduction signal of the predetermined period of the head is reproduced and processed as a reproduction video signal. While using, write to storage means such as digital memory,
In the period other than the writing of the predetermined period, the contents of the means are read and output as a reproduced video signal.
Therefore, without adding a slow playback head,
You can achieve slow playback with no noise and no blurring or rolling.

Further, it is possible to realize a reproduction screen without information loss during slow reproduction.

Furthermore, in the transition from the normal reproduction mode to the slow reproduction mode, it is possible to realize a mode transition in which no transient noise appears.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a reproducing system circuit according to an embodiment of the present invention. FIG. 2 is a time chart for explaining the operation of FIG. FIG. 3 is an illustrative view showing the relationship between the recording band of the magnetic tape and the running locus of the magnetic head for explaining FIG. FIG. 4 is a diagram for explaining tape running control during slow playback in a conventional VTR. In the figure, 1a and 1b are magnetic heads, 2a and 2b are head amplifiers, 3,9 and 17 are switches, 5 is a reproduction processing circuit, 6 is an A / D converter, 7 is a memory, and 8 is a D / A converter. , 10 is a waveform shaping circuit, 11 is a flip-flop, 13 is a first timing circuit, 16 is a second timing circuit, 18 is a tape drive motor, and 19 is a frequency generator.

Claims (1)

[Claims] 1. A first rotating drum having different azimuths from each other.
And a second magnetic head, which employs a rotary head system that is switched by a head switching signal and a helical scan system that obliquely scans the magnetic tape, and informs the running state of the magnetic tape at an information signal and a predetermined cycle. A magnetic signal reproducing device for reproducing a magnetic tape on which a reference signal for recording is recorded, the information signal being at a speed slower than a recording speed (normal running speed) when the information signal is recorded on the magnetic tape. A slow drive commanding means for playing back the magnetic tape, and a drive control means for driving the magnetic tape to run continuously at a speed slower than the normal running speed in response to the output of the slow play commanding means. Storage means for storing a reproduction information signal for one field reproduced by two magnetic heads; and the reference signal Further, based on the head switching signal, after detecting the reference signal, the number of predetermined pulses generated in response to the head switching signal is counted, so that the magnetic tape and the first and second magnetic heads are Position information detecting means for detecting a relative positional relationship between the magnetic tape and the first and second magnetic heads detected by the position detecting means when the magnetic tape is continuously driven at the slow speed. In response to the relative positional relationship of being a specific positional relationship that is predetermined according to the slow speed, writing of the reproduction information signal to the storage means and reproduction information from the storage means. Write / read control means for controlling the reading of a signal, and in response to the output of the write / read control means, the first or second magnetic field during a write period. And a switching means for deriving a reproduction information signal reproduced by the head as an output signal, and deriving an information signal stored in the storage means as an output signal during the reading period. .