JPH0312382B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an image editing device, and more particularly to a servo device of a magnetic recording/reproducing device suitable for continuous shooting using a pause mechanism during recording.

[Background of the invention]

The conventional continuous shooting mechanism is, for example,
18805 etc. One of these conventional methods is shown in FIG.

In FIG. 1, 1 is a magnetic tape, 2 is a capstan shaft, 3 is a capstan motor, 4 is a pinch roller, and 5 is a control head. 6 is a vertical synchronization signal input terminal, 7 is a 1/2 frequency divider, 8 is a switch, 9 is a recording amplifier for recording the synchronization signal, and 10 is a reproduction amplifier for reproducing the synchronization signal on the magnetic tape 1. , 11 and 12 indicate switches. 13 is a reference signal generator, 14 is a frequency divider, 15
1 is a phase comparator, 16 is a motor drive circuit, 17 is a frequency generator that generates a frequency according to the rotational speed of the capstan motor, and 18 is a frequency divider. 19 is a pause switch, and 20 is a system controller circuit.

These operations will be explained using the time chart shown in FIG. When performing continuous shooting, it is necessary to synchronize the signal recorded on the magnetic tape 1 with the newly recorded signal, and the means to do this is to use the already recorded synchronization signal (waveform 27) It is necessary to match the phase of the synchronization signal (waveform 23) to be newly recorded. Therefore, after operating the pause switch 19 to start recording, the system controller 20 sends the recording state ("L" period) after a delay for the period necessary for the above-mentioned phase alignment, as shown in waveform 21. . As this phase matching means, a vertical synchronizing signal (waveform
22) is approximately 60Hz, which is divided by 1/2 by frequency divider 7.
Perform frequency division to obtain waveform 23 of approximately 30Hz. This frequency divider 7
For this purpose, use something like monomulti. The output of the reference signal generator 13 (waveform 24) is divided by the output of the frequency divider 7 to produce a reference signal of 30Hz (waveform 25).
Preset the frequency divider 14 to create As a result, the newly recorded synchronization signal (waveform 23) and the reference signal (waveform 25) which is the output of the frequency divider 14 are synchronized. On the other hand, the synchronizing signal (waveform 27) recorded on the magnetic tape 1 is reproduced by the control head 5, amplified by the reproduction amplifier 10, and then inputted to the phase comparator 15 via the switch 12. Here, the phase is compared with the reference signal 25, and the motor drive circuit 16 is controlled by this output to vary the rotational speed of the capstan motor and drive the magnetic tape 1 so that the two have a constant phase relationship. Control. Further, as the phase comparator 15, for example,
A trapezoidal wave 26 is created from the reference signal 25, and this waveform
26 with the reproduction synchronization signal 27 (the value at this time is used as the waveform).
26 (indicated by a dotted line above).

As described above, the newly recorded synchronization signal 23 and the reproduction synchronization signal 27 on the magnetic tape 1 are synchronized. Thereafter, in synchronization with the falling edge of the waveform 21, each switch 8, 11, 12 assumes an inverted position from the state shown in FIG. 1, and enters a recording state. That is, frequency divider 7
The synchronizing signal for newly recording, which is the output of
recorded in On the other hand, the control applied to the capstan motor 3 is such that the output of the frequency generator 17 (waveform 29) is supplied to the phase comparator 15 with a waveform 28 obtained by passing the output (waveform 29) of the frequency generator 17 through the frequency divider 18. . Therefore, the capstan motor 3 is newly controlled by comparing the phases of the reference signal 25 and the waveform 28. During this switching, phase comparator 1
It is necessary to minimize fluctuations in the output error signal of No. 5. The conventional method is to provide a switch 11 and preset the frequency divider 18 by sending the reproduction synchronization signal 27, which is the output of the reproduction amplifier 10, through the switch 11 before starting recording, thereby synchronizing the two. I was thinking about it.

However, in this case, the output waveform 29 of the frequency generator 17 generated during one cycle of the reproduction synchronization signal 27 is
The number of pulses N causes an error of up to (2π/N) radians. The output frequency of this frequency generator 17 is normally on the order of several hundred Hz, and this error (2π/N) cannot be ignored, especially in a long-time recording/playback mode performed by lowering the capstan motor speed. For example, when an error 30 occurs as shown in the figure, the output of the phase comparator 15 fluctuates as shown by the dashed line on the waveform 26 after switching to the recording mode. As a result, the recorded tracks at the joints are disturbed, leading to a decrease in image quality during playback.

[Purpose of the invention]

An object of the present invention is to sufficiently reduce the phase jump error at discontinuous points that occurs in the capstan phase control system during continuous shooting, and to improve the S/N of the reproduced image at the joint.
The objective is to provide a servo system that allows continuous shooting without deterioration.

[Summary of the invention]

The present invention provides a frequency divider that performs capstan phase control in recording mode and generates a reference signal by frequency-dividing a reference high-frequency signal when performing continuous shooting, using a feedback signal from a capstan motor.
By once presetting and synchronizing, phase jump errors are minimized.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

In FIGS. 3 and 4, the same reference numerals as in FIGS. 1 and 2 indicate components having the same functions. 31 in figure
32 is a frequency divider that divides the output of the reference signal generator 13, and 33 is a signal generator that generates a preset signal to the frequency divider 32.

Here, when the pause switch 19 is operated as a continuous shooting operation, the system controller 20 sends a signal, as shown in waveform 21, necessary for phase alignment between the synchronization signal on the magnetic tape 1 and the newly recorded synchronization signal. After a delay of a certain amount of time, the recording state (“L” period) is entered. Here, the switches 8, 12, and 31 are configured to be in the illustrated state during the "H" period of the waveform 21, and are inverted during the "L" period. Here, when the waveform 21 is in the "H" period, the synchronization signal recorded on the magnetic tape 1 is transmitted to the control head 5.
and is reproduced by the reproduction amplifier 10 to become a reproduction synchronization signal 27, and a synchronization signal 23 to be newly recorded is transmitted to the frequency divider 7 from the vertical synchronization signal 22 inputted from the terminal 6.
made through. The phases of these two are matched by the method described in the prior art.

Next, when the waveform 21 switches to "L", the switch 8 becomes conductive and the output 23 of the frequency divider 7 is in a state to be recorded on the magnetic tape 1 via the storage amplifier 9 and the control head 5. Become. Meanwhile, switch 31 is turned off and the preset signal to frequency divider 32 is released. In other words, waveform 21 is "H"
During the phase matching period, the frequency divider 32 is
Like the frequency divider 14 shown in FIG. 1, it is configured to be preset by the output of the frequency divider 7 (waveform 23), so even if the vertical synchronization signal supplied to the input terminal 6 is lost, the The frequency generator 32 is the reference signal generator 13
The output (waveform 24) can be frequency-divided to continuously generate a 30Hz waveform 25. Therefore, even if the synchronization signal of the newly recorded video signal tends to be lost, the necessary synchronization can be performed during splicing.

Next, the output 28 of the frequency divider 18 from the signal generator 33
At least one pulse output synchronized with34
is output and the frequency divider 32 is preset. At the same time, the switch 12 is inverted, and the phase comparator 15
The input to the frequency divider 18 is switched from the reproduction synchronization signal 27 to the output 28 of the frequency divider 18. The preset value of the frequency divider 32 at this time is such that the output error signal of the phase comparator 15 (waveform 26
(indicated by a dotted line above) is set to be the same as the previous value.

The phase jump that occurs at this time reaches a maximum of (2π/M) radians, assuming that the frequency division ratio of the frequency divider 32 is M. (Waveform 35 in the figure) Here, in a normal magnetic recording/reproducing device, the reference signal generator 13 uses 3.58 MHz, which is the color subcarrier of the video signal (or a signal obtained by dividing this appropriately). A sufficiently high value is used compared to N in the prior art.

Furthermore, the signal generator 33 will be explained in detail using FIGS. 5 and 6. In FIGS. 5 and 6, the same reference numerals as in FIGS. 1, 2, 3, and 4 indicate the same functions. In the figure, 36, 37, and 38 are flip-flops, and 39 is an AND gate. The flip-flop 36 uses the output waveform 28 of the frequency divider 18 as a trigger input (operates with a negative trigger), and inputs the output waveform 21 of the system controller 20 as a reset input. At this time, a waveform 40 is obtained at the Q output (the output is an inverted waveform of the Q output). That is,
At the point where waveform 21 becomes "L", flip-flop 36
The reset input is released, and the Q output 40 becomes "H" in synchronization with the next trigger input. The flip-flop 37 then outputs, for example, the output of the reference generator 13.
24 as a trigger, the output of flip-flop 36 is configured as a reset input. Further, the flip-flop 38 has a D input terminal, and the "H" signal is fixedly inputted to the input terminal. The output of the flip-flop 37 is connected as the trigger input, and the same signal as the flip-flop 37 is input as the reset input. At this time, the Q output of flip-flop 37 becomes waveform 41, and the output of flip-flop 38 becomes waveform 42. Furthermore, the output of the AND gate 39 which receives waveform 40 and waveform 42 as input is waveform 34.

Here, the waveform 34 is used as a preset signal for the frequency divider 32, and the waveform 42 is supplied as a switching signal for the switch 12. In this way, the frequency divider 32 that generates the reference signal 25 is preset by the preset signal 34 synchronized with the output of the frequency divider 18 generated from the feedback signal from the capstan motor 3, and then the switch 12 is inverted. This stabilizes the output of the phase comparator 15 during switching transients.

Furthermore, as specific practical examples, Figures 7 and 8
There is a diagram. In FIGS. 7 and 8, the same symbols as in FIGS. 5 and 6 indicate the same functions. In the figure, 43 is a flip-flop. In this embodiment, unlike FIG. 5, the reset signal for the flip-flop 36 is generated by the flip-flop 43.
As an input to the flip-flop 43, a waveform 44 is input as a trigger input from the output of the 1/2 frequency divider 7 via the switch 8. On the other hand, the output 21 of the system controller 20 is input as the reset input. Furthermore, the "H" level is input to the D input.
The output at this time is waveform 45.

That is, after recording the first synchronization signal (waveform 44) to be recorded, the preset pulse 34 of the frequency divider 32 is output. As a result, the recording position of the first recording synchronization signal on the magnetic tape 1 at the start of re-recording is in a state where the capstan motor 3 is controlled at the value before the output signal of the phase comparator 15 fluctuates. Record with . That is, in the recording period in which a new synchronization signal is recorded after the phase adjustment period for continuous shooting ends, the frequency divider 32 is still preset based on the new synchronization signal at the beginning. The synchronization signal recorded at the beginning of the recording period has phase continuity with respect to the old recording synchronization signal recorded immediately before that. In other words, even after the recorded video signal is switched to a new one, at least one synchronization signal used for servo system control that has the same phase as the old synchronization signal is recorded. Therefore, no synchronization disturbance occurs in the servo system before and after switching the video signal. Therefore, according to this embodiment, it is possible to further improve at least the first recording synchronization signal and recording position. In this case, the phase jump of the recording synchronization signal of up to 2π/M occurs after the recorded video signal is switched to a new one, so the above phase jump occurs during playback of the same video signal. . That is, since the phase jump that occurs in the servo system does not occur at the same time as the switching of video content, the unsightliness can be reduced compared to the case where the phase jump occurs simultaneously with the switching of video content.

〔Effect of the invention〕

According to the present invention, the phase jump of the capstan servo system during continuous shooting can be determined by the resolution of the clock frequency that generates the reference signal, so it can be determined with sufficient accuracy and the S/N of the image quality near the joint can be determined. It is possible to improve the deterioration. Furthermore, in the present invention, since the preset signal supplied to the preset type frequency divider is switched, the preset type frequency divider can be used not only during recording and playback, but also during the phase adjustment period required for continuous shooting. Therefore, significant malfunctions of the servo system due to lack of synchronization signals can be prevented in any operating state.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the servo system during conventional continuous shooting, Figure 2 is a waveform diagram explaining the operation of Figure 1, Figure 3 is a block diagram of the servo system of the present invention, and Figure 4 is the Figure 5 is a waveform diagram explaining the operation of Figure 5. Figure 5 is a block diagram showing the main parts of Figure 3.
FIG. 7 is a block diagram showing another embodiment of the present invention, and FIG. 8 is a waveform diagram explaining the operation of FIG. 7. 1... Magnetic tape, 3... Capstan motor, 5... Control head, 8, 11, 1
2, 31... Switch, 13... Reference signal generator, 14, 18... Frequency divider, 15... Phase comparator, 20... System controller, 32... Frequency divider, 33... Signal generator , 36, 37, 38...
...flip flop, 39...AND gate.

Claims (1)

[Scope of Claims] 1. A capstan motor that rotates a capstan that transports a magnetic tape, a frequency generator that generates pulses with a frequency corresponding to the rotational speed of the capstan motor, and a frequency generator that separates the output of the frequency generator. A first frequency divider that rotates, a reference signal generator that generates a reference signal, a second presettable frequency divider that divides the reference signal, and During a predetermined phase adjustment period at the beginning of continuous shooting in which video signals are recorded, each time a new synchronization signal obtained from a newly recorded video signal is generated, this new synchronization signal a first frequency divider; and a first input terminal; and a second input terminal connected to the output of the second frequency divider, detecting the phase difference between the two input signals supplied to the first and second input terminals, and detecting the detected phase difference. A detection control means for controlling the rotation of the capstan motor according to A servo device for a magnetic recording/reproducing device, comprising: switching supply means for supplying the output of the first frequency divider after the end of the adjustment period. 2. The preset means includes a switch operated at the start of continuous shooting, and a pulse signal that, in response to the switch operation, has a first level during the predetermined phase adjustment period and changes to a second level after the period ends. a pulse signal from the controller, the new synchronization signal, the output of the first frequency divider, and a reference signal from the reference signal generator;
a signal generator that generates at least one preset pulse synchronized with the output of the frequency divider with a delay from a new synchronization signal generated immediately after a change in the level of the pulse signal from the controller; 2. A servo device for a magnetic recording/reproducing apparatus according to claim 1, wherein the supply means is switched in response to a preset pulse from said signal generator.