JPS62289074A - Video tape recorder - Google Patents

Abstract

PURPOSE:To generate a horizontal signal synchronizing with a rotary drum, to remove a skew in a horizontal direction and to eliminate the disturbance of a reproduced picture by permitting a rotating signal synchronizing with the rotation of the rotary drum to reset a synchronizing generator circuit when a frame is photographed. CONSTITUTION:A video signal from an image pickup element 21 is supplied to a synthesizer 24. A composite synchronizing signal from a synchronizing signal generator circuit 30 is supplied to supply a composite video signal to a magnetic head H. A resetting signal forming circuit 40 is constituted of a differentiation circuit 41 differentiating one FG pulse obtained during one rotation of the rotary drum 2 and a waveform shaping circuit 42. In a frame photographing mode, a system control circuit 45 supplies a skew correction signal SS to an AND circuit 43 to output a resetting signal SR. It resets the synchronizing signal generator circuit 30 to generate the horizontal synchronizing signal in synchronization with the rotation of the rotatory drum. In terms of the pattern of a video signal recorded on a tape, the current and next recording horizontal periods agree with each other almost completely, thereby suppressing the occurrence of a skew.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] This invention is suitable for application to a portable type camera-integrated video, such as an 8 mm video, and is capable of taking time-lapse pictures. Related to video tape recorders.

[Prior Art] As shown in Figure 11, scene splicing in camera-integrated video (portable video) such as 8 mm video is automatically stopped when a pause button is operated during recording. It will be rewinded for a certain amount of time (0.5s).
ec level) When rewinding, it will be in a stopped state.

Next, when recording, the phase alignment with the video signal to be recorded is performed using the vertical synchronization signal of the recorded track during the rewinding period of the tape, and the last track of the recorded tracks is scanned. When recording, the recorded video signal and the video signal to be newly recorded are synchronized.

In such continuous shooting, since there is no discontinuity at the scene change portion, there is no reproduction noise caused by discontinuity in the video signal, resulting in a very easy-to-see screen.

However, since this splicing method attempts to ensure continuity of the screen based on the vertical synchronization signal of the video signal, if a discontinuity in the horizontal period occurs, a large skew will occur at the top of the playback screen. become.

For example, if the horizontal period becomes discontinuous at the joint between scenes, the waveform of the reproduced video signal becomes discontinuous at the head switching position as shown in FIG. As a result, a skew as shown in FIG. 13 appears on the playback screen. This skew is due to the horizontal blanking signal appearing on the screen.

By the way, when the recording time of a scene is short, as in time-lapse photography, and the time-lapse recording is performed over a considerably long period of time, there is a drawback that when the above-mentioned skew occurs, the reproduced image quality deteriorates significantly.

In other words, skew occurs in each continuous shot scene,
Furthermore, since each scene of the connecting operation has an extremely short recording time of about 1 to 7 frames, the next playback screen will be disturbed by the skew before the skew is eliminated.

The above-mentioned skew occurs when the horizontal period is disturbed due to a slight temperature drift in the servo circuit, or when the synchronization separation circuit of the monitor device malfunctions due to the equivalent pulse, and the horizontal synchronization system performs pseudo-synchronous operation due to the equivalent pulse. It is something that occurs.

In other words, as shown in Fig. 14, the head switching position becomes a free run state, the horizontal synchronization system is pseudo-locked by the equivalent pulse that exists after that, and synchronization gradually begins with the correct horizontal synchronization signal after the equivalent pulse. It is. Therefore, the skew is not recovered within the vertical blanking period.

In order to avoid this skew phenomenon, it is necessary to perform servo control during the continuous shooting operation using not only the vertical synchronization signal but also the horizontal synchronization signal.

FIG. 15 shows an example of a drum motor speed control system constructed in consideration of the above points.

A drum motor 2 for driving a rotating magnetic head (not shown) is provided with a frequency generator 3, and an FG pulse obtained from the frequency generator 3 synchronized with the rotation of the rotating magnetic head is used to generate an FG pulse in an input video signal supplied to a terminal 4. The phase of the vertical synchronization signal is compared with the phase comparator 5, and the phase comparison output is supplied to the drum motor 2 via a low-pass filter 6 and a drive amplifier 7, whereby the motor 2 is driven to rotate in synchronization with the vertical synchronization signal. Ru.

In addition, the horizontal synchronization signal SH can be separated by completely supplying the reproduced video signal (video signal obtained during the phase adjustment period of the connection operation) supplied to the terminal 11 to the synchronization separation circuit 12.

On the other hand, the synchronization separation circuit 13 separates the horizontal synchronization signal in the input video signal, the phase comparator 14 compares the phases of both signals, and the phase comparison output is supplied to the adder 16 via the low-pass filter 15. , and the phase comparison output from the phase comparator 5 to control the rotation of the drum motor 2.

In this way, if the rotational state of the rotating drum is controlled using the horizontal synchronization signal in addition to the vertical synchronization signal, false locking due to equivalent pulses will not occur, and horizontal skew can be removed. be able to.

[Problems to be Solved by the Invention] By the way, if the configuration is such that the rotational state of the rotating drum is controlled using a horizontal synchronization signal in addition to the vertical synchronization signal as described above, the following problems will occur. .

First, in order to eliminate horizontal skew, the above-mentioned configuration must be added.

In this case, if the vertical skew correction circuit system is implemented as an IC, it would be expensive to implement a new horizontal skew correction circuit system as an IC. , it is even more difficult to incorporate both into an IC because existing ICs cannot be used effectively.

Second, as shown in Figure 11, since the reproduced video signal is used only during the phase matching period, it is necessary to control the circuit system to the reproduction state only during this period, and the control system for this purpose is required. The configuration is relatively cumbersome.

Thirdly, since the rotational state of the rotary drum is controlled using a horizontal synchronization signal, it is necessary to configure the circuit so that synchronization can be performed even in the horizontal period. However, in order to enable response in such a short period of time, it is necessary to use circuit elements with a fast response speed, which inevitably becomes expensive, and if the response speed is too fast, it may cause problems such as oscillation. The adjustment is also troublesome.

Therefore, the present invention solves these conventional problems, and provides a video camera having a rotating drum control system suitable for time-lapse photography, which can achieve skew correction with a simple configuration and at low cost. This project proposes a tape recorder.

[Technical Means for Solving the Problems] In order to solve the above-mentioned problems, in the present invention, when the time-lapse mode is selected, the composite The present invention is characterized in that a horizontal synchronization signal synchronized with the rotating drum is generated by resetting the synchronization generation circuit for forming the synchronization signal.

[Function] If the synchronization generation circuit is reset with a rotation signal synchronized with the rotation of the rotating drum during time-lapse photography, the speed control system of the drum motor will not be pseudo-locked by equivalent pulses or the like. As a result, horizontal skew can be removed, so that the playback screen will not be disturbed even during time-lapse shooting.

[Embodiment] Next, an example of a video tape recorder having a rotating drum control system according to the present invention will be described in detail with reference to FIG. 1 and subsequent figures.

Here, in order to perform time-lapse photography, it would be more convenient to provide a dedicated button for use during time-lapse photography, in addition to the operation buttons for normal recording and playback.

This is because in order to photograph the state of flowering and the movement of clouds, it is necessary to record intermittently at regular intervals. This is because it is convenient to be able to perform such time-lapse photography with a single button operation, since there will be no failure in photography.

In this case, by operating the button dedicated to time-lapse shooting,
Each time, as shown in Figure 9, the mode automatically shifts to the recording mode for a certain predetermined period, and when the predetermined period has elapsed,
The system control system shall be controlled so as to automatically shift to stop mode.

The predetermined period refers to a period of approximately 1 to 7 frames.

As shown in FIG. 10, the time-lapse mode may be configured such that by operating the time-lapse button once, several time-frame operations are automatically executed.

FIG. 1 is a system diagram showing an example of a drive control system for a rotating drum, which is a main part of a video tape recorder according to the present invention. The signal is supplied to a synthesizer 24 via a preamplifier 22 and a process processing circuit 23 such as gamma correction. The composite sync signal output from the sync signal generation circuit 30 is supplied to the synthesizer 24 to form a well-known composite video signal.

The composite video signal can be supplied to the rotating magnetic head H via the amplifier 25.

On the other hand, among the composite synchronization signals obtained from the synchronization signal generation circuit 30, the vertical synchronization signal Sv is supplied to the phase comparator 5, where it is phase-compared with a rotation signal synchronized with the rotation of the rotary drum, as in the prior art. As the rotation signal, for example, an FG pulse obtained once per rotation of the rotary drum 2 can be used.

In this invention, in addition to the above-mentioned control system, a reset signal forming circuit 40 is provided, and the synchronizing signal generating circuit 3o is reset by the reset signal SR obtained from this circuit.

The reset signal forming circuit 40 includes a differentiation circuit 41 that differentiates the FG pulse, and a waveform shaping circuit 42 that shapes the waveform of the differential output.
The skew correction signal SS obtained from the system control circuit 45 in the time-lapse mode is supplied to the AND circuit 43, and only when this correction signal SS is obtained, the waveform-shaped signal is sent to the reset signal SR. is output as This reset signal SR is supplied to the control terminal 35 of the synchronization signal generation circuit 30.

FIG. 2 shows an example of the synchronization signal generation circuit 30, and n
It has an oscillator 31 that oscillates at a frequency of fH (n is an integer, fH is a horizontal frequency), and its output is supplied as a clock to a horizontal synchronization counter 32 and a vertical synchronization counter 33. Then, the horizontal synchronization signal S obtained from the carnator 32
H is supplied to the vertical synchronization counter 33 and frequency-divided again to generate a vertical synchronization signal Sv.

The horizontal and vertical synchronization signals St(, Sv) are mixed by a mixer 34 to form a composite synchronization signal. A reset signal SR for horizontal synchronization is supplied to a control terminal 35 of the horizontal synchronization counter 32.

FIG. 3 shows an example of the reset signal forming circuit 40.

In other words, the FG also functions as a head switching pulse.
The pulse is supplied to the differentiating circuit 41 via the phase inverting transistor Q1. This differentiating circuit 41 is composed of a pair of resistors R1, R2 and a capacitor C, and the differential output obtained at the connection point of the pair of resistors R1, R2 is supplied to a waveform shaping transistor Q2. A waveform-shaped pulse is output from the collector, and this is used as the reset signal SR.

Now, FIG. 4 is a waveform diagram showing the relationship between the FG pulse, the forward/reverse switching pulse for the capstan, and time-lapse recording, and it is assumed that the time-lapse recording is performed over a period of two frames.

The reason why the capstan is switched in the opposite direction is that, as shown in FIG. 11, it is necessary to perform phase adjustment in order to perform the connection operation.

The forward/reverse switching pulse and the time-lapse recording pulse are both control signals obtained from the system control circuit 45.

Details in the time-lapse mode are shown in FIG.

First, when the FG pulse (A in the figure) is supplied, a differential pulse as shown in B in the figure is obtained, and this is waveform-shaped to generate the pulse shown in C in the figure, so the skew correction signal SS is Only when the reset signal SR is obtained, the reset signal SR is obtained.

As a result, as shown in FIG. 6, by inputting the reset signal SR, the horizontal synchronization signal SH obtained from the horizontal synchronization counter 32 is generated in synchronization with the rotation of the rotary drum.

As a result, as shown in FIG. 7, the pattern of the video signal recorded on the tape is such that the horizontal periods of the previous and current recordings almost completely match. Note that one rotation of the rotating drum (33, 3
m5ec) is sufficiently small compared to the horizontal period, so when the horizontal synchronizing signal SR is reset by the reset signal SR, the skew component of the video signal recorded on the tape is The scanning period is about 2 to 3 μsec compared to 63.5 μsec.

Therefore, this skew component can be almost ignored.

By the way, in the case where the reset signal is not used as described above, a discontinuous part of the horizontal period will occur between the video signal recorded last time and the video signal recorded this time, as shown in Figure 8. .

[Effects of the Invention] As explained above, according to the present invention, the skew is removed not only in the servo control system but also on the synchronization signal generator side of the camera.

That is, since the reset signal is generated in synchronization with the rotation of the rotary drum and the horizontal synchronization signal is reset by this reset signal, the period of the horizontal synchronization signal is not disturbed at the joint between scenes.

Therefore, the occurrence of skew can be suppressed to a negligible level. In addition, even with this configuration, the circuit configuration is extremely simple, and all that is needed is to reset the horizontal synchronization signal, so the response speed of the circuit is not a particular problem, and there are no restrictions on the circuit configuration. Not so much.

Since this invention can suppress the skew of each scene to an almost negligible level, this invention selects a time-lapse shooting mode in which the interval between scenes is narrow, such as in stop-motion shooting, as described above. It is very suitable for application to a video tape recorder which is made to have the following functions.

[Brief explanation of drawings]

FIG. 1 is a system diagram of essential parts of a rotating drum control system showing an example of a video tape recorder according to the present invention, FIG. 2 is a system diagram showing an example of a synchronizing signal generation circuit, and FIG. 3 is a system diagram of a reset signal forming circuit. A connection diagram showing an example, Figures 4 to 8 are waveform diagrams to explain the operation, Figures 9 and 10 are waveform diagrams to explain the operation of time-lapse shooting, and Figure 11 is an explanatory diagram of the connection operation. , FIG. 12 and FIG. 14 are signal waveform diagrams during continuous shooting, respectively, and FIG. 13 is a diagram showing an example of a skew screen.
FIG. 15 is a system diagram showing an example of a rotating drum control system for explaining the present invention. 21...Image sensor H...Rotating magnetic head 2...ψ drum motor 30...Synchronizing signal generation circuit 40...φ reset signal forming circuit 41...Differentiating circuit 42...Waveform shaping circuit

Claims (1)

[Claims] When the time-lapse mode is selected, a horizontal synchronization signal synchronized with the rotating drum is generated by resetting the synchronization generation circuit for forming a composite synchronization signal based on the synchronization signal obtained in synchronization with the rotation of the rotating drum. A videotape recorder designed to