JPH01273258A - Capstan control method - Google Patents

Abstract

PURPOSE:To eliminate the need of a control track so as to increase the video signal recording area by recording track position signals on a helical video track and reproducing video synchronizing signals from time codes. CONSTITUTION:Reference track position signals are added to video signals at a mixer 12 and recorded on a helical video track on a tape. At the time of reproduction, a detector 10 extracts reproduced video synchronizing signals from reproduced signals from a time code track on the tape and gives the extracted signals to a phase comparator 11 and supplies the error voltage with a reference video synchronizing signal to a switch 15. Simultaneously, another detector 13 inputs reproduced signals from a video track, gives reproduced track position signals to a phase comparator 14, and supplies the error voltage with a reference track position signal to a switch 15. A capstan motor is controlled by means of the error voltage outputted from the switch 15 and the capstan is synchronized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a capstan control method in high-density recording and reproduction of video signals.

2. Description of the Related Art A block diagram of a conventional capstan control method for recording and reproducing video signals in a helical manner is shown in FIG. In FIG. 4, 40 is a video synchronization signal detector that detects a reproduced video synchronization signal from a control track on the tape, and 41 compares the phase of the reference video synchronization signal and the reproduction video synchronization signal from the video synchronization signal detector 40. Phase comparator (1), 4
2 is a mixer that adds a reference track position signal to the video signal;
43 is a track position signal detector that detects a reproduced track position signal from a video signal reproduced from a helical video track on the tape; 44 is a phase between the reference track position signal and the reproduced track position signal from the track position signal detector 43; The phase comparator (2), 45, which compares the error voltage from the phase comparator (1) 41 and the error voltage from the phase comparator (2) 44, detects the phase synchronization output from the phase comparator (1) 41. This is a switch that is switched by a signal.

The operation of the conventional capstan control method configured as described above will be explained below.

First, a reference video synchronization signal is recorded on a control track on the tape, and a reference track position signal is added to the video signal by the mixer 42 and recorded on the helical video track.

Next, at the time of reproduction, a reproduced video synchronization signal is detected from the signal from the control track by a video synchronization signal detector 40 and inputted to a phase comparator (1) 41. Phase comparator (1
) 41, the reference video synchronization signal and the reproduced video synchronization signal are compared in phase, and the error voltage is input to the switch 45.

Further, a reproduced track position signal of the signal from the helical video track is detected by a track position signal detector 43 and inputted to a phase comparator (2) 44. Phase comparator (
2) At 44, phase comparison is performed between the reference track position signal and the reproduced track position signal detected by the track position signal detector 43 from the signal reproduced from the helical video track, and the error voltage is manually input to the switch 45. Ru. Therefore, in the phase comparator (1) 41, a phase synchronization detection signal indicating whether the phase difference of the video synchronization signal is within a certain range or not is determined. When the error voltage becomes 41 and falls within the range, the output of the switch 45 becomes the error voltage of the phase comparator (2) 44, and the error voltage of the remoter is used to control the feed capstan motor and complete synchronization. Met.

Problems to be Solved by the Invention However, the above configuration requires a control track for recording the reference video synchronization signal.

Furthermore, the time code is also recorded on a separate time code track, resulting in two linear tracks on the tape, resulting in a reduction in the recording area for video signals.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a capstan control method that increases the recording area that does not require a control track among the two linear tracks.

Means for Solving the Problems The present invention is an apparatus for recording and reproducing video signals on a tape using a helical track, in which a track position signal is recorded on the helical track together with the video signal, and during reproduction, the track position signal is reproduced from a time suit track. The phase of the capstan is controlled by detecting a video synchronization signal from within the detected time code, and after the phase difference of the video synchronization signal falls within a certain range, the phase control of the capstan is performed using the detected track position signal. This is a capstan control method that switches to

The present invention is an apparatus for recording and reproducing video signals on a helical track, in which a reference track position signal is recorded on a helical video track together with the video signal. Next, during reproduction, the phase of the reproduced video synchronization signal read from the time code originally reproduced from the time code track and the reference video synchronization signal is compared to control the capstan motor. Next, when the phase difference between the two video synchronization signals falls within a certain range, a phase synchronization detection signal indicating this is used to control the motor by comparing the phase of the reproduced track position signal recorded in the helical track and the reference track position signal. The synchronization of the capstan motor is completed.

Example Hereinafter, the present invention will be explained in more detail based on the drawings.

FIG. 1 shows a block diagram in an embodiment of the invention. In FIG. 1, 10 is a video synchronization signal detector that extracts a reproduced video synchronization signal from the reproduction time code, and 11 is a video synchronization signal detector that compares the phase of the reproduced video synchronization signal reproduced by the video synchronization signal 10 with a reference video synchronization signal. Phase comparator (1), 12
13 is a mixer that adds a track position signal to a video signal and records it on a helicopter video track; 13 is a track position signal detector that extracts a reproduced track position signal from a reproduced video signal; 14 is a track position signal detector 13 that reproduces a reproduced track position signal. A phase comparator (2), 15, which compares the phase of the reproduced track position signal and the reference track position signal, is a phase comparator (1) 11
The error voltage of phase comparator (1) 11 and phase comparator (2) 14 is switched and output using a phase synchronization signal that indicates whether the phase difference between the reference and reproduction video synchronization signals is within a certain range or not. This is a switch to

The operation of the capstan control method of this embodiment configured as described above will be described below.

First, the reference track position signal is added to the video signal in the mixer 12 and recorded on the helical video track on the tape. At the time of next playback, the playback time code from the time code track on the tape is sent to the video synchronization signal detector IO. The reproduced video synchronization signal is extracted at the phase comparator (1).
It is input as a comparison signal of 11. Phase comparator (1) 1
1, the phases of the reference video synchronization signal and the reproduced video synchronization signal from the video synchronization signal detector IO are compared, and an error voltage is inputted to the switch 15. At the same time, the reproduced video signal from the helical video track is input to the track position signal detector 13, and the reproduced track position signal therein is extracted and input as a comparison signal to the phase comparator (2) 14. (2) At step 14, phase comparison is performed between the reference track position signal and the reproduced track position signal from the track position signal detector 13, and an error voltage is input to the switch 15. Therefore, the output of the switch 15 is determined by a phase synchronization detection signal indicating whether the phase difference between the reference and reproduction video synchronization signals in the phase comparator (1) is within a certain range or not. (1) 11
If the error voltage is entered, the phase comparator (2)
This results in an error voltage of 14. Then, the capstan motor is controlled by this error voltage, and the synchronization of the capstan is completed.

As described above, according to this embodiment, the video synchronization signal is reproduced from the time code track, and the track position signal is recorded and reproduced from the helical video track, so the control track can be eliminated and the recording area for the video signal can be saved. can be increased.

FIG. 2 shows a block diagram of a video synchronization signal detection means in a second embodiment of the present invention, and FIG. 3 shows a configuration diagram of a time code.

In FIG. 2, 20 is a color frame bit detector that detects the state of color frame bits in the reproduced time code, 21 is a color frame detector that reproduces a color frame from frame display bits in the reproduced time code, and 22 23 is a frame detector which reproduces frames based on the period of the reproduction time code, and a switch 23 which is switched based on the detection signal of the color frame bit detector 2°.

The operation of the video synchronization signal detecting means of this embodiment configured as described above will be explained below with reference to FIG. As shown in FIG. 3(a), the time code consists of a total of 80 bits, which consist of repeating the cycle of a frame signal. 1 of them
The color frame bit is assigned to the 1st bit, and if a color frame signal exists here, it is "l".
, if no color frame exists, a value of "0" is entered in each color frame bit.

Therefore, in the time code reproduced from the time code track in FIG. 2, the color frame bit detector 20 reads the value of the 11th bit to detect the presence or absence of a color frame (FIG. As for the time code, the color frame detector 21 reads the color frame from the frame display bit in the time code and outputs it to the switch 23 (3rd [(c)(d)
)), the same time code reads the frame which is the period of the time conid by the frame detector 22 and switches it to the switch 2.
3 (Fig. 3(b)), then switch 2
3, depending on the presence or absence of a color frame from the color frame bit detector 20, if a color frame exists, the color frame from the color frame detector 21 is output, and if no color frame exists, the frame from the frame detector 22 is output. .

As described above, according to this embodiment, either a color video signal or a black and white video signal can be recorded by detecting the presence or absence of a color frame bit in the time code and reading the period and frame display bit in the time code. Even in such cases, the capstan motor can be controlled by reading it and switching the video synchronization signal read from the time code.

As described in detail, according to the present invention, the track position signal can be recorded and played back on the helical video track, and the video synchronization signal can be played back from within the time code. It can be eliminated. Therefore, the recording area for video signals can be increased. By detecting the presence or absence of a color frame bit in the time code during synchronization of the video synchronization signal, it automatically synchronizes the color frames when recording color video signals, and automatically synchronizes the frames when recording monochrome video signals. The practical effects are great.

It can be done and its practical effects are great.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a capstan control method in an embodiment of the present invention, Fig. 2 is a block diagram of a video synchronization signal detection means, Fig. 3 is a configuration diagram of a time code, and Fig. 4 is a conventional capstan control method. FIG. 2 is a block diagram of the method. 10... Video synchronization signal detector, 11... Phase comparator (1), 12... Mixer, 13... Track position signal detector, 14... Phase comparator (
2), 15... switch, 20... color frame bit detector, 21... color frame detector,
22... Frame detector, 23... Switch 40... Video synchronization signal detector, 41... Phase comparator (1), 42... Mixer, 43
. . . Track position signal detector 44 . . . Phase comparator (2), 45 . . . Switch. Name of agent: Patent attorney Toshio Nakao

Claims (2)

[Claims] (1) A device for recording and reproducing video signals on a tape using a helical track, in which a track position signal is recorded on the helical track along with the video signal, and during playback, a video synchronization signal is generated from the time code reproduced from the time code track. is detected to control the phase of the capstan, and after the phase difference of the video synchronization signal falls within a certain range, the phase control of the capstan is switched to be controlled using the detected track position signal. capstan control method. (2) Color frame bits within the playback timecode.”
If "1" is recorded, the color frame signal is reproduced from the frame display bit of the playback time code to synchronize the color frame, and if "0" is recorded in the color frame bit, the time code is synchronized. 2. The capstan control method according to claim 1, further comprising a video synchronization signal detecting means for reproducing a frame signal having a period and synchronizing the frames.