JPH0140550B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for editing images.

FIG. 1 shows an example of a magnetic tape pattern diagram when a new signal is recorded on an already recorded tape in a conventional home VTR. 1 is the audio track, 2 is the control track, 3 is the video signal track of channel 1, and 4 is the channel 2.
The video signal track is shown below. For home VTRs,
Generally, a two-head helical scan system is adopted, and the video signal is recorded alternately in two heads (channel 1 and channel 2 head) as shown in FIG. Also, these two heads are recorded by changing the head gap direction (azimuth recording).
Therefore, signals recorded on other channel heads can hardly be played back. For this reason, if the two video signal tracks are recorded in a disordered manner at the joint between the images as shown in FIG. 1, during playback, the head of the desired channel also traces the portion recorded by the head of the other channel, and the desired track is trace width decreases. This has resulted in a disadvantage that the reproduction output is reduced, the image S/N ratio is degraded in this portion, white noise is generated, and the image becomes unsightly.

An object of the present invention is to eliminate the unsightly white noise, image S/N degradation, etc. at the image connection portions described above during reproduction.

In order to achieve the above object, the present invention uses a phase control system applied to the capstan motor to compare both comparison signals with the old synchronization signal on the already recorded magnetic tape and the new synchronization signal that is newly recorded. By setting a constant phase relationship between the signals and applying this phase error signal to the capstan motor, recording is started after the old synchronization signal is completely matched with the new synchronization signal. Furthermore, in order to shorten this phase matching time, a circuit was added that generates reverse torque in the capstan motor for a time corresponding to the phase difference between the two, thereby bringing the phases of the two closer together in a short time.

The present invention will be explained in detail below with reference to Examples. The configuration of the present invention is shown in FIG. 2, a time chart showing its operation is shown in FIGS. 3a to 3k, and an embodiment of the main part of the invention is shown in FIG.

In FIG. 2, 5 is a pinch roller, 6 is a capstan shaft, 7 is a capstan motor, 8 is a magnetic tape, and 9 is a control head. 10 is a rotational speed detector that detects a frequency obtained in accordance with the rotation of the capstan, 11 is an amplifier thereof, and 12 is a frequency divider that divides this frequency. 13 is a reference oscillator using a crystal or the like; 14 is a frequency divider that divides the frequency; 15 is a phase comparator that detects the phase difference between the output of this frequency divider 14 (REF30Hz) and the frequency divider 12; Reference numeral 16 indicates a drive amplifier for driving the capstan motor 7. 17 is a switch for switching the connection to the control head 9 during recording and playback; 18 is a reproduction vertical synchronization signal amplifier; 19 is a phase difference detector for detecting the phase difference between the reproduction vertical synchronization signal and the recording vertical synchronization signal; Reference numeral 20 indicates a recording vertical synchronizing signal amplifier.

The operation of this configuration will be explained using the time chart shown in FIG. Normally, the capstan motor 7 divides the output of the 3.58 MHz reference oscillator 13 used in the video signal system by (2 ⁶ × 1866) to obtain a 30 Hz signal, and uses this as the reference signal to perform phase control. It's summery. As a comparison signal, a frequency obtained according to the rotation of the capstan motor 7 during recording is detected by a rotation speed detector 10, and this is frequency-divided to obtain a 60 Hz signal. Here, the recording switch signal 22
When input, the recording start signal 23 is outputted and recording is started after a delay of a time necessary for phase alignment of the reproduction vertical synchronization signal and the recording vertical synchronization signal, which will be described below.

Next, the phase alignment of both vertical synchronization signals will be explained. When the recording switch signal 22 is input, the magnetic tape starts running, and the control head 9 detects a synchronization signal already recorded on the magnetic tape. At this time, the switch 17 is connected to the reproduction side as shown in FIG.
8, a waveform 25 shown in FIG. 3d is taken out.
On the other hand, the synchronization signal extracted from the television signal to be newly recorded is input to the terminal 21, and is passed through the recording vertical synchronization signal amplifier 20 to the waveform 2 shown in FIG.
Get 4. Here, by associating the new and old vertical synchronizing signals with the respective inputs of the capstan phase comparator 15, the phases of the two are matched. That is, the recording vertical synchronizing signal amplifier 20 shown in FIG.
The output 27 of the frequency divider 14 is reset (or preset), and the output of the regenerative vertical sync signal amplifier 18 is used to preset (or reset) the frequency divider 12, as shown in FIG. 3i. Next, the phase comparator 15 integrates a part of the waveform 27 of FIG. 3f, and the signal 28 shown in FIG. 3g is sampled and polled at the rising edge of the signal 30 shown in FIG. Signal 29
get. Drive amplifier 1 uses this as the control voltage.
6. The speed of the capstan motor 7 is changed by this control voltage, and the phase of the old vertical synchronization signal detected from the magnetic tape is matched with the phase of the synchronization signal to be newly recorded. After the phases of both are matched by the above operation, recording is started by the recording start signal 23. At this time, the switch 17 is connected to the recording side opposite to that shown in FIG.
The output of the control head 9 is supplied to the control head 9, and a new synchronization signal is recorded.

Next, the above-mentioned phase matching time reduction circuit will be explained. A phase difference detector 19 using a flip-flop or the like, which uses the new and old synchronization signals as set and reset signals, detects only one pulse wave with a time width corresponding to the phase difference between the two. This pulse wave 32 is shown in FIG. 3k. This signal is applied to the drive amplifier 16, and the speed of the capstan motor 7 is rapidly accelerated or decelerated for this period of time, thereby bringing the phases of the two closer together in a short period of time.

Next, an embodiment of the control portion of this drive amplifier 16 is shown in FIG. In the figure, 33 is a motor coil, 34 is a rotating body that rotates the capstan shaft,
Reference numeral 35 indicates a group of switches for switching the direction of current flowing through the motor coil 33. 36 is the motor coil 33
37 is a switch, 38 is a resistor, 39 is a resistor 40, and a switch 41
42 indicates a control input terminal, respectively. Here, when the pulse 32 shown in FIG.
An appropriate current can be supplied to the motor coil 33 by cutting off the control signal from the motor and supplying the "H" signal of the pulse 32. This allows the capstan motor to generate an appropriate reversing torque, thereby rapidly bringing the two phases closer together. In the above, it has been explained that phase matching is performed by rapidly decelerating the capstan motor, but the same effect can be obtained even if the capstan motor is accelerated.

Furthermore, in a magnetic recording and reproducing apparatus that changes the recording and reproducing time on the same magnetic tape by switching the magnetic tape feeding speed, the video track gap changes depending on the tape speed. Therefore, depending on each tape speed, for example, a switching circuit 39 is provided to switch the voltage supplied to the base of the transistor 36, and the value of the reversal torque can be switched and designed to be optimal.

The above operation can be performed by rewinding the amount of magnetic tape necessary for the above phase alignment by the rewinding operation of the magnetic recording/reproducing device even when the recording is temporarily stopped, for example.

As described above, according to the present invention, when re-recording a part of a magnetic tape that has already been recorded, the video track phase of the already recorded signal and the video track phase of the newly recorded signal can be precisely matched in a short time. By doing so, it is possible to completely eliminate the deterioration of the S/N ratio of the reproduced image and the generation of white noise that occur in this joint portion.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of a conventional magnetic tape pattern at a connecting portion, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, and FIGS.
FIG. 4 is a time chart for explaining the operation shown in FIG. 4, and FIG. 4 is a circuit configuration diagram showing an embodiment of the main part of the present invention. 7... Capstan motor, 9... Control head, 12, 14... Frequency divider, 15... Phase comparator, 16... Drive amplifier, 19... Phase difference detector, 35... Switch group, 37...Switch.

Claims (1)

[Claims] 1 Compare the phase difference between the capstan motor equipped with a motor coil and the playback control signal read out from the control head and the recording synchronization signal obtained from the newly recorded recording signal, and adjust the phase difference according to the comparison result. A first control means that generates a drive current, a switching supply means that switches the direction of the drive current and supplies it to the motor coil, and at the beginning of the comparison period in which the phase difference is compared, a pulse width corresponding to the phase difference is determined. and second control means for controlling the switching supply means so that the direction of the drive current is reversed during this pulse period with respect to the remaining comparison period. playback device.