JPH05101491A - Tape running speed controller for vtr - Google Patents

Abstract

PURPOSE:To attain a servo control of tape running speed even in a recording mode by detecting the running speed of tape and thereby controlling a capstan motor. CONSTITUTION:A 1st magnetic head 3D for recording a control signal CTL of specified cycle on a magnetic tape MT and a 2nd magnetic head 31 for reproducing the control signal record on the tape MT at the downstream side are arranged at interval of integral multiple of the distance Pct of control signal recorded on the magnetic tape MT. Further, a tape running speed detection circuit 33T to detect the running speed of tape MT is provided in accordance with the time difference between the supply control signal of head 3D and the reproduction control signal of head 31, and the rotation of a motor 8 is controlled by a detection output of the circuit 33T, then the running speed of tape MT is servo-controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape traveling speed control device for a VTR suitable for a digital VTR.

[0002]

2. Description of the Related Art Conventionally, a V-1 of a D-1 system (so-called 4: 2: 2 system) for digitally recording a video signal (Y, RY, BY) of a component format has been known. A D-1 VTR (D-1VTR) employs, for example, a 4-channel processing system using four rotary magnetic heads in order to reduce the transmission rate of a large amount of data.

In this D-1 system, an inclined track called a "program track" has two video sectors (half tracks) S for video data as shown in FIG.
It is composed of v and an audio sector Sa for audio data and is formed on the magnetic tape MT. The inclination angle (track angle) of this program track is slightly more than 5 °.

In the case of the 525/60 standard system having 525 lines and a nominal field frequency of 60 Hz, video data for one field is recorded over 20 video sectors for 10 slant tracks. On the other hand, the number of lines is 62
In the case of the 625/50 standard system of 5 lines and field frequency of 50 Hz, the data transmission rate is the same, but since the field period is long, data is recorded over 24 video sectors for 12 slant tracks. As a result, D-
The pattern of the 1-system program track is 525/6
It is substantially common to both the 0 standard system and the 625/50 standard system.

Further, in the D-1 system, recording of one field of video data is started from a sector (upper side in FIG. 5) starting from approximately the center of the magnetic tape and starting from the vicinity of the edge of the tape (see FIG. 5). End at the end of the sector (at 5). Further, a cue audio track Tka, a servo control track Tkc, and a time code track Tkt are provided at both edges of the tape. As shown in FIG. 5, in the servo control track Tkc, among the upper video sectors,
A series of double pulses as shown in FIG. 6 is recorded as a so-called CTL signal in alignment with the starting ends of every four reference sectors.

The numerical values shown in FIG. 6 are based on the 525/60 standard system. In the 525/60 standard system,
When the tape MT runs at a predetermined speed of 286 mm / s, for example, the pitch pct of CTL pulses recorded on the tape
Is, for example, less than 1.91 mm.

[0007]

By the way, as is well known, in the VTR, the FG frequency of the capstan motor is set on the assumption that the tape running speed in the recording mode becomes a constant ratio with the rotation speed of the capstan motor. The servo is controlled so that it becomes constant.

However, in the conventional capstan servo control as described above, when the diameter of the capstan fluctuates according to the change in ambient temperature, the tape running speed also fluctuates accordingly. With the D-1 VTR,
For example, a stainless steel capstan with a diameter of 6 mm is used. The linear expansion coefficient of stainless steel is about 17 × 10 ^-6
Therefore, when the ambient temperature changes by 10 ° C., the diameter of the capstan changes by about 1 μ.

Further, there is a problem that the tape running speed fluctuates because the tape thickness varies from lot to lot. The D-1VTR tape includes a standard tape having a thickness of 16 μ and a long-time tape having a thickness of 13 μ, but the long-time tape has a variation in thickness in the range of, for example, 11.5 to 13.0 μ from lot to lot.

Further, there is a problem that the tape running speed also fluctuates even when the slip ratio between the tape and the capstan changes due to fluctuations in the pressing force of the pinch roller.

In order to solve such a problem, the applicant of the present invention, in Japanese Patent Application No. 2-413789, provides a CTL signal reproducing head downstream of the CTL signal recording head to reproduce C
The tape speed is detected based on the time difference between the TL signal and the recording CTL signal and the distance (tape length) between both heads, and the speed of the capstan motor is controlled to change the capstan diameter due to the ambient temperature change. We have already proposed a "VTR tape running speed control device" that eliminates fluctuations in tape speed during recording caused by variations in tape thickness and tape thickness.

An example of the configuration of the VTR tape traveling speed control device proposed in the above will be described below with reference to FIGS.

FIG. 7 shows the entire structure of the already proposed example, and FIG. 8 shows the structure of the main part thereof. In FIG. 7, a pair of magnetic heads 1A, 1B and 1C, 1D are mounted on a rotary drum 2R at an angular interval of 180 °, and a pair of fixed drums 2T, 2B are arranged above and below the rotary drum 2R. It Further, in the already proposed example, the CTL recording head 3 is attached to the lower fixed drum 2B.

The rotary drum 2R is driven by a motor 4 directly connected to the motor 4. The motor 4 has a rotary phase pulse generator (so-called PG) 5 and a frequency signal generator (so-called F).
G) 6 and are attached. The magnetic tape MT is wound around the fixed drums 2T and 2B in a predetermined angular range, and the tape M
The traveling speed of T is controlled by the capstan 7. A motor 8 is directly connected to the capstan 7 and an FG 9 is attached.

Reference numeral 10 denotes a drum servo circuit, which includes a reference oscillator 11 and is supplied with respective outputs of PG5 and FG6. The drive output of the servo circuit 10 is supplied to the drum motor 4, and at the time of recording, a tracking control signal, a so-called CTL signal, is supplied to the recording head 3 via the mode changeover switch S, and the servo of the tape MT is performed. Written to control track Tkc.

Reference numeral 20 denotes a capstan servo circuit,
A frequency comparator 21 and a reference frequency data forming circuit 22 are provided. The output of the FG 9 is supplied to the comparator 21, is compared with the reference frequency data from the forming circuit 22, and the output of the comparator 21 is supplied to the motor 8 via the amplifier 23.

In this proposed example, a CTL reproducing head 31 is arranged at an appropriate position between the drum 2 and the capstan 7, and a simultaneous reproducing CTL signal from this head 31 is
It is supplied to the tape speed calculation circuit 33 via the waveform shaping circuit 32. The speed calculation circuit 33 includes a recording head 3
In common with, the original CTL signal is supplied. Reference numeral 34 is a ROM that stores reference speed data.
Is supplied to the reference frequency data forming circuit 22 together with the output of the tape speed calculating circuit 33.

The operation of the already proposed example of FIG. 7 will be described with reference to FIGS. 8 and 9. As shown in FIG. 8, depending on the position of the CTL reproducing head 31, the CTL
The distance Dhh along the tape from the recording head 3 is appropriately determined. In the recording mode, since the tape MT runs at the predetermined speed Vnm, the tape M is moved by the head 3 as shown in FIG.
The specific CTL pulse Psr recorded on the T
The time required for playback by Tnm is
It is uniquely determined in correspondence with the distance Dhh between 31.

Therefore, the actual running speed Vmt of the tape MT is calculated by measuring the time difference Thh between the recording CTL pulse Psr and the corresponding CTL pulse Psp reproduced by the head 31 and dividing this by the head distance Dhh. You can ask. In the tape speed calculation circuit 33, the original C
The traveling speed calculation as described above is performed based on the TL signal and the simultaneous reproduction CTL signal.

In the reference frequency data forming circuit 22, the difference between both input speeds, that is, the frequency data corresponding to the speed error is formed based on the operation speed by the tape speed operation circuit 33 and the reference speed data from the ROM 34. It The frequency data is compared with the output of the FG 9 in the comparator 21, and the capstan motor 8 is frequency-servo controlled according to the output of the comparator 21.

Then, as described above, the effects of the fluctuation of the capstan diameter due to the change of the ambient temperature, the variation of the tape thickness, the change of the slip ratio between the tape and the capstan, etc. are eliminated, and the tape MT is moved at a predetermined speed. Drive stably.

By the way, in the D-1 system tape format, as described above, C on the servo control track Tkc is used.
It is specified that the TL pulse is recorded in alignment with the starting end of the reference sector of the program track and in the width direction of the tape. When the VTR different from that used for recording is used, the CTL recording head 3 and the CTL recording head 3 can be reproduced so that the rotary head can reproduce the recording track without deviating from the recording track, that is, the compatibility between the VTRs is maintained. Playhead 3
The arrangement position of 1 is adjusted with an accuracy of 10 μ, for example.

However, in the already proposed example of FIG. 7, the positions of the CTL recording head 3 and the CTL reproducing head 31 and the distance Dhh between the heads 3 and 31 are not specified, so recording is performed by both heads 3 and 31. Or replayed CT
There is a problem that the timings of the L signals are unrelated to each other, and it is difficult to adjust the positions of the heads 3 and 31 to ensure compatibility. Further, since the running speed calculation as described above is performed, there is a problem that the structure of the tape speed calculation circuit 33 is complicated.

Further, when the tape running starts in the recording mode, or when the CTL signal is missing, the reproduction CTL signal cannot be obtained from the head 31 and the tape speed detection (calculation) becomes impossible, and the tape running is stopped. There was a problem that became unstable.

In view of the above point, an object of the present invention is to provide a CTL recording head provided in order to eliminate the influence on the tape speed such as the change of the ambient temperature, the variation of the tape thickness and the change of the slip ratio even in the recording mode. The position of the CTL playback head can be easily adjusted, and
You can control the running speed of the tape with a simple circuit,
VTR that can stably run the tape even when the tape starts to run in the recording mode or when the CTL signal is missing
The present invention provides a tape traveling speed control device.

[0026]

A first aspect of the present invention is provided with a capstan 7 that is in pressure contact with a magnetic tape MT, and a motor 8 that drives this capstan, and servo-controls the running speed Vmt of the magnetic tape. In the tape traveling speed control device of the VTR described above, the first magnetic head 3D for recording the control signal CTL of a predetermined cycle on the magnetic tape, and the magnetic tape is recorded on the magnetic tape at the downstream side of the first magnetic head. The second magnetic head 31 for reproducing the control signal is arranged at an interval of an integer multiple of the interval pct of the control signal recorded on the magnetic tape, and the control is supplied to the first magnetic head. A tape traveling speed detection circuit 33T for detecting the traveling speed of the magnetic tape is provided based on the time difference Thh between the signal and the control signal reproduced by the second magnetic head. By controlling the rotation of the motor based on the detection output of the detection circuit, a tape running speed control device for a VTR in which the running speed of the magnetic tape so that the servo control.

A second aspect of the present invention is a tape traveling speed control device for a VTR, which comprises a capstan that is in pressure contact with a magnetic tape and a motor that drives the capstan, and that servo-controls the traveling speed of the magnetic tape. , A first for recording a control signal CTL of a predetermined cycle on a magnetic tape
Magnetic head 3D, a second magnetic head 31 for reproducing a control signal recorded on a magnetic tape on the downstream side of the first magnetic head, and a control signal supplied to the first magnetic head. A tape running speed detection circuit for detecting the running speed of the magnetic tape is provided based on the time difference Thh from the control signal reproduced by the second magnetic head and the distance Dhh between the first and second magnetic heads. A reproduction control signal detection circuit 35 for detecting the presence / absence of a reproduction control signal from the second magnetic head and a pseudo reference signal generation circuit 34 for generating a pseudo reference signal are provided to reproduce that there is no reproduction control signal. When detected by the control signal detection circuit, the rotation speed of the motor is controlled based on the pseudo reference signal to servo-control the traveling speed of the magnetic tape. It is a degree control device.

[0028]

According to this structure, the CTL recording head and the C
The position of the TL reproducing head can be easily adjusted, the tape running speed can be controlled by a simple circuit, and the running of the tape is stable even when the tape running starts in the recording mode or when the CTL signal is lost.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the tape traveling speed control device for a VTR according to the present invention will be described below with reference to FIGS.

FIG. 1 shows the overall construction of an embodiment of the present invention, and FIG. 2 shows the construction of the main part. In FIGS. 1 and 2, parts corresponding to those in FIGS. 7 and 8 described above are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 1, C is attached to the lower fixed drum 2B.
A TL recording / reproducing head 3D is attached, and the head 3D is connected to the C through the contact on the r side of the changeover switch Sa.
The CTL signal is supplied from the TL signal generation circuit 12. C
A common sync signal is supplied to the TL signal generation circuit 12 from the sync signal generation circuit 11S in common with the drum servo circuit 10.

In this embodiment, as shown in FIG. 2, on the servo control track Tkc of the tape MT, on the basis of the point Qr aligned with the starting end of the reference video sector Svr, the CTL signal of the CTL signal is formed along the tape on the upstream side. Predetermined integer multiple of pitch pct,
For example, the fixed drum 2B is arranged so that the distance Dup is 10 times.
A CTL recording / reproducing head 3D is provided therein. As a result, the distance from the rotary drum 2R (see FIG. 1) can be increased, the head 3D can be easily attached, and the CTL signal is substantially recorded at the reference point Pr.
Further, in the reproduction mode, the tape length between the head 3D and the rotary head is shortened, and the influence of the expansion and contraction of the tape is significantly reduced.

On the other hand, on the downstream side of the reference point Qr along the tape, a predetermined integer multiple of the pitch pct of the CTL signal, for example, 11
The CTL reproducing head 31 is arranged at a position where the distance Ddn is 0 times. Therefore, the distance Dhh along the tape between both heads 3D and 31 is also an integral multiple of the pitch pct of the CTL signal. The output of the CTL reproducing head 31 is supplied to the shaping circuit 32 via the r-side contact of the changeover switch Sb, and the p-side contact of the switch Sb and the r-side contact of the switch Sa are connected.

33T is a tape speed detection circuit and 35 is a CT
In the L signal detection circuit (microprocessor), the output of the shaping circuit 32 is commonly supplied, and the output of the CTL signal detection circuit 35 is supplied as a control signal to the reference frequency data forming circuit 22 and the switch Sc. .. The output of the reference frequency data forming circuit 22 is supplied to the n-side contact of the switch Sc, the output of the ROM 34 is supplied to the s-side contact, and the output of the switch Sc is supplied to the frequency comparator 21. The other structure is similar to that shown in FIG.

Next, referring to FIG. 3 as well, the operation of the main part of the embodiment of the present invention will be described. In the recording mode, the synchronizing signal generating circuit 11S is supplied with the synchronizing signal generated from the video signal to be recorded, and the generating circuit 1S
A synchronizing signal synchronized with the recording video signal is output from 1S.

The switches Sa and Sb are connected to the r side,
The CTL signal from the generation circuit 12 is recorded on the tape MT via the head 3D, and the recorded CTL signal is recorded on the head 31 by the distance Dhh and tape speed Vmt along the tape between the heads 3D and 31. It arrives after the time corresponding to and has elapsed.

As described above, in this embodiment, the head 3
Since the distance Dhh along the tape of D and 31 is set to an integral multiple of the pitch pct of the CTL signal, when the tape speed Vmt is a predetermined value, from the head 31 with the synchronization signal as shown in FIG. 3A as a reference. As shown by the solid line in FIG.
C at the same timing as the original CTL signal as shown in FIG.
The TL signal Po is reproduced. When the tape speed Vmt becomes faster or slower than a predetermined value, the original CTL shown in FIG.
CTL signal P at a timing earlier or later than the signal
f and Ps are reproduced.

In the tape speed detecting circuit 33T, the timing of the reproduction CTL signal as described above and the timing of the original CTL signal are compared, and the tape speed is detected based on the comparison result. Then, the reference frequency data forming circuit 22
Then, based on this tape speed and the reference speed data from the ROM 34, frequency data corresponding to the speed error is formed, and as will be described later, comparison is made via the switch Sc connected to the n side in the normal state. The tape MT is supplied to the container 21, the servo control of the capstan motor 8 is performed, and the tape MT runs stably at a predetermined speed.

In this embodiment, since the distance between the CTL recording head 3D and the CTL reproducing head 31 along the tape is set to an integral multiple of the pitch pct of the CTL signal on the tape, the tape speed detecting circuit 33T reproduces the reproducing CTL. It suffices to compare the timings of the signal and the original CTL signal, and the tape speed calculation as in the previously proposed example is not required, so the circuit configuration becomes simple.

In the case of adjusting the head position, the switch Sb is manually switched while reproducing the standard tape prepared in advance, and the recording / reproducing head 3D and the reproducing head 31.
As shown in FIG. 3, it is sufficient to adjust the position of each head so that the reproduced CTL signal from the head has the same timing as that of the synchronizing signal, and the required accuracy can be easily obtained. In this case, the synchronization signal generation circuit 11S is supplied with the synchronization signal generated from the reproduction video signal, and the generation circuit 11S outputs the synchronization signal synchronized with the reproduction video signal.

Next, referring to FIG. 4 as well, the operation of another main part of the embodiment of the present invention will be described. As described above, when the tape running in the recording mode is started, or when the CTL signal is missing, the reproduction CTL signal cannot be obtained from the head 31, and the tape speed cannot be detected in the already proposed example. .. In this embodiment, the provision of the CTL signal detection circuit 35 deals with the case where the reproduced CTL signal cannot be obtained.

In the recording mode, as shown in FIG. 4, when the tape running is started in step S10, the changeover switch Sc is set to the s side by the control signal from the CTL signal detecting circuit (microprocessor) 35. (Step S11), the speed data stored in the ROM 34 is used as the pseudo reference signal for the frequency comparator 2 of the capstan servo circuit 20.
1 is supplied. This data is obtained in advance by running a standard tape and the like.
T runs at a constant speed close to a predetermined value. This state is maintained until the reproduction circuit CTL signal is detected by the detection circuit 35 (step S12).

When the first reproduction CTL signal is detected in step S12 about 1 second after the tape running is started, the switch Sc is switched to the n side (step S1).
3). The reproduction CTL signal and the original CTL signal are compared in timing in the tape speed detecting circuit 33T, and control frequency data is formed in the data forming circuit 22 based on the comparison result and the reference speed data from the ROM 34. , Frequency comparator 2 via switch Sc
1 to start the servo control of the original tape speed.

Once the reproduced CTL signal is detected, C
The timer built in the TL signal detection circuit 35 is reset and the time counting is started (step S21). Normally,
Until the next CTL signal is reproduced, for example, it takes 1/150 seconds as shown in FIG. 6, so that a predetermined time with an appropriate margin added is waited for (step S2).
2).

At step S23, due to missing or the like,
When the reproduced CTL signal is not detected, the data holding control signal supplied from the detection circuit 35 to the data forming circuit 22 is turned on (step S24), and the control frequency data formed based on the immediately preceding reproduced CTL signal is held. hand,
The capstan servo circuit 20 maintains the previous tape speed.

When the reproduced CTL signal is detected in step S23, the detection circuit 35 moves the data forming circuit 22.
The data holding control signal supplied to the switch is turned off (step S25), and the capstan servo control based on the new reproduced CTL signal is performed. Then, the timer is reset to move to the detection of the next missing CTL signal.

In this embodiment, the CTL signal detection circuit 35
Is provided and the switch Sc or the control frequency data forming circuit 22 is appropriately controlled to avoid an abnormal tape speed and always obtain a stable tape speed even at the tape running start time in the recording mode or when the CTL signal is lost. Be done.

[0048]

As described above in detail, according to the first aspect of the present invention, in the tape traveling speed control device of the capstan servo type VTR, the CTL recording head in the fixed drum and the CTL reproducing head in the downstream side are provided. Distance D along the tape with
hh is set to an integer multiple of the recording pitch pct of the CTL signal on the tape, and a running speed detection circuit for detecting the running speed Vmt of the tape is provided based on the time difference between the original CTL signal and the reproduced CTL signal. Since the rotation of the capstan motor is controlled based on this detection output, the tape traveling speed can be servo-controlled even in the recording mode, and the position adjustment of the CTL recording head and the CTL reproducing head becomes easy, It is possible to obtain a tape traveling speed control device of a VTR that enables the tape traveling speed to be detected with a simple circuit.

According to the second aspect of the present invention, in the tape traveling speed control device of the capstan servo type VTR, the CTL recording head in the fixed drum and the CT on the downstream side are provided.
Distance Dhh along the tape with the L playback head and the original CTL
Based on the time difference between the signal and the reproduction CTL signal, a traveling speed detection circuit for detecting the traveling speed Vmt of the tape is provided, a reproduction control signal detection circuit for detecting the presence or absence of the reproduction CTL signal, and a pseudo reference signal generation circuit. Since the rotation of the capstan motor is controlled based on the pseudo reference signal when the reproduction CTL signal does not exist, the tape can be stably run even at the tape running start time in the recording mode or when the CTL signal is missing. It is possible to obtain a tape traveling speed control device for a VTR.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of a tape traveling speed control device for a VTR according to the present invention.

FIG. 2 is a development view showing a configuration of a main part of an embodiment of the present invention.

FIG. 3 is a waveform diagram for explaining the operation of the main part of the embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of another main part of the embodiment of the present invention.

FIG. 5 is a schematic line plan view for explaining the present invention.

FIG. 6 is a waveform diagram for explaining the present invention.

FIG. 7 is a block diagram showing a configuration example of a tape traveling speed control device of a VTR proposed in the past.

FIG. 8 is a block diagram showing a configuration of a main part of an already proposed example.

FIG. 9 is a waveform diagram for explaining the operation of the already proposed example.

[Explanation of symbols]

 3D CTL recording / reproducing head 7 Capstan 11S Synchronous signal generator 20 Capstan servo circuit 22 Reference frequency data forming circuit 31 CTL reproducing head 33T Tape speed detecting circuit 34 Reference speed data storing circuit (ROM) 35 Reproducing CTL detecting circuit (micro) Processor)

Claims (2)

[Claims] 1. A capstan press-contacted to a magnetic tape,
In a tape traveling speed control device for a VTR, which is provided with a motor for driving the capstan, and which servo-controls the traveling speed of the magnetic tape, a first control means for recording a control signal of a predetermined cycle on the magnetic tape. A magnetic head and a second magnetic head for reproducing the control signal recorded on the magnetic tape on the downstream side of the first magnetic head are provided with an interval between the control signals recorded on the magnetic tape. Of the magnetic tape, and the magnetic tape runs based on the time difference between the control signal supplied to the first magnetic head and the control signal reproduced by the second magnetic head. The magnetic tape is provided by providing a tape running speed detecting circuit for detecting the speed and controlling the rotation of the motor based on the detection output of the tape running speed detecting circuit. Tape running speed controller for VTR, characterized in that the traveling speed so as to servo-control. 2. A capstan that is pressed against a magnetic tape,
In a tape traveling speed control device for a VTR, which is provided with a motor for driving the capstan, and which servo-controls the traveling speed of the magnetic tape, a first control means for recording a control signal of a predetermined cycle on the magnetic tape. A magnetic head, a second magnetic head for reproducing a control signal recorded on the magnetic tape on the downstream side of the first magnetic head, and the control signal supplied to the first magnetic head. A tape running speed detection circuit for detecting the running speed of the magnetic tape based on the time difference from the control signal reproduced by the second magnetic head and the distance between the first and second magnetic heads. And a reproduction control signal detection circuit for detecting the presence or absence of the reproduction control signal from the second magnetic head, and a pseudo reference signal generation circuit for generating a pseudo reference signal. When the reproduction control signal detection circuit detects that the reproduction control signal does not exist, the rotation speed of the motor is controlled based on the pseudo reference signal to servo-control the traveling speed of the magnetic tape. A tape traveling speed control device for a VTR, characterized in that