JP2505655B2 - Video playback device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a field memory.
Video that is used to intermittently play video from a video tape , such as slow-motion playback or frame-by-frame playback
The present invention relates to a playback device .

[0002]

BACKGROUND ART FIG. 4 is a block diagram showing a configuration of a conventional Film image playback device, reference numeral 1 is a recorded video tape, a video signal obtained through the magnetic head 2A, and 2B Is sent to the reproduction signal processing circuit 4 via the changeover switch 3. Reference numeral 5 denotes a memory control circuit, which is the reproduction signal processing circuit 4 described above.
With reference to the sync signal from, the write timing and address of the output signal from the reproduction signal processing circuit 4 to the field memory 6 are generated. Field memory 6
Output is processed by the video signal processing circuit 7 to become the output video signal 8.

Reference numeral 9 denotes a control head. Based on the output of the control head 9, the servo circuit 10
The capstan motor 11 and the reel motor 12 are controlled via the to control the running of the tape in each mode. Reference numeral 13 is a reference signal circuit, which generates a reference signal for writing to the field memory 6 at the time of special reproduction by the head switching signal from the servo circuit 10.

Next, the operation of the above configuration will be described. In normal reproduction, a video signal (hereinafter referred to as a reproduction signal) extracted from the video tape 1 by the magnetic heads 2A and 2B is switched based on a head switching signal (hereinafter referred to as HSW) from the servo circuit 10. 3 is selected as appropriate, and the reproduction signal processing circuit 4 and the video signal processing circuit 7 are selected.
To become the output video signal 8. On the other hand, the servo circuit 10
Controls the capstan motor 11 and the reel motor 12 on the basis of the control signal from the control head 9 and also switches the magnetic heads 2A and 2B.
W is generated.

Next, during slow motion reproduction, a command is issued from the servo circuit 10 in accordance with the specified speed of slow motion, the capstan motor 11 and the reel motor 12 are intermittently driven, and the video tape 1 is sent frame by frame. . At the same time, the servo circuit 10 outputs the signal c during the video tape stop period.

The memory control circuit 5 controls the field memory 6 by the write reference signal e generated by the reference signal circuit 13 on the basis of the signal c during the video tape stop period and the switching signal HSWb to process the reproduction signal. The reproduced signal a is written from the circuit 4 into the field memory 6. After this writing is completed, reading from the field memory 6 is continued. The read video signal d becomes the output video signal 8 through the video signal processing circuit 7.

The capstan motor 1 is then instructed by the servo circuit 10 according to the slow motion speed.
1, the reel motor 12 is driven, the video tape 1
The frame is advanced. At this time, the servo circuit 10, the reference signal circuit 13, and the memory control circuit 5 perform the same operation as described above, and the reproduction signal a one frame after the reproduction signal written in the field memory 6 is stored in the field memory 6. By being written, the contents of the field memory 6 are updated. The contents of the field memory 6 are updated every time the video tape 1 is sent by one frame, as shown in FIG.

[0008]

In conventional movies picture playback apparatus constructed as described above [0008], in slow-motion playback using the field memory 6, the movies image signal H S
Since a method of writing and reading to and from the field memory 6 with the write reference signal c created from Wb as a reference, even a reproduction signal that can obtain a substantially clean screen on the display screen is shown in the timing chart of FIG. as such, there is a case of lack of the horizontal synchronizing signal in the middle of writing the write reference signal e in the field memory 6, the relative positions of the horizontal synchronizing signal of the address and the video signal of the field memory 6 is FIG greatly in this case .

Further, as shown in the timing chart of FIG. 7, even when there is no omission of the horizontal synchronizing signal, when the horizontal synchronizing signal exists near the write reference signal e, for example, in the case of writing, m + 1 of the reproduction signal a. The portion of the horizontal sync signal of the number is written in the line A of the field memory 6, and in the case of writing, the portion of the horizontal sync signal of the reproduced signal a is written in the line of A of the field memory 6, Writing due to fluctuations in the servo circuit 10,
Writing occurs randomly, the video tape 1 is stopped, and the reproduction signal written in the field memory 6 is deviated by one horizontal synchronizing signal, so that one horizontal synchronizing signal rises or falls vertically in the display screen. There was a problem.

The present invention has been made to solve the above-mentioned problems, and writes a video signal to a field memory.
The write reference signal Mutame to control the missing portion of the horizontal synchronizing signal <br/> salmon so that, by controlling the positional relationship between the write reference signal and a horizontal synchronizing signal, there is little vertical up and down movement of the display screen Slow motion playback ,
And to provide a Film image playback apparatus that perform the frame playback.

[0011]

SUMMARY OF THE INVENTION Film image playback apparatus according to the present invention, a video signal recorded on a video tape intermittently
When playing back intermittently, the above video tape
A field memory that stores the video signal reproduced from
Writing to the above field memory based on the head switching signal
Write reference signal generating means for generating an embedded reference signal,
The reference signal generated by the writing reference signal generating means is stored in the water.
Predetermined predetermined so as to avoid the missing part of the flat sync signal
Delay means for delaying the time, and the base delayed by the delay means
Of the video signal to the above field memory based on the quasi signal
A memory control means for controlling storage,
I do. In addition, the video signal recorded on the above video tape
If the video tape is stopped during intermittent playback, the delay above
The presence or absence of the horizontal sync signal at the extended reference signal position is detected.
The positional relationship detecting means to be output and the positional relationship detecting means are
When the flat sync signal is detected, the delay amount of the above delay means is set.
Characterized by having a time constant means for changing a fixed time
It Furthermore, the change in the delay amount by the time constant means is
Set to 1/2 cycle of the horizontal sync signal of the video signal.
And are characterized.

[0012]

According to the present invention, in intermittent reproduction such as slow-motion reproduction or frame-feed reproduction, the reference signal for writing to the field memory is used to avoid the missing portion of the horizontal synchronizing signal.
The address of the field memory and the water of the video signal.
The relative position of the flat sync signal does not shift significantly.
Also, the writing criteria delayed during the video tape stoppage period.
Detects the presence or absence of the horizontal sync signal at the signal position, and
When the sync signal is detected, the delay amount of the delay means is set to a predetermined value.
Time, especially for 1/2 cycle of the horizontal synchronizing signal of the video signal,
Since it is changed, it may change depending on the fluctuation of the servo circuit.
Relative writing position of video signal to field memory
Can it to prevent the change to.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a block diagram showing the structure of Film image playback apparatus according to an embodiment of the present invention. In the figure, the conventional example and the same or corresponding parts described in FIG. 4 are denoted by the same reference numerals, and detailed The description is omitted.

In FIG. 1, 14 is a delay circuit for delaying a field memory write reference signal, 15 is a positional relationship detecting circuit for the reference signal and the horizontal synchronizing signal, and 16 is a gate for limiting the detection period of the positional relationship detecting circuit 15. circuit,
Reference numeral 17 is a time constant circuit for changing the delay amount of the delay circuit 14,
Reference numeral 18 denotes a changeover switch for selectively changing the time constant circuit 17 according to the output from the positional relationship detection circuit 15.

Next, the operation of the above configuration will be described. 2 and 3 are timing charts including the relationship between the write reference signal to the field memory 6 and the horizontal synchronizing signal.

At the time of slow motion reproduction, a command is issued from the servo circuit 10 according to the specified speed of the slow motion, the capstan motor 11 and the reel motor 12 are intermittently driven, and the video tape 1 is sent frame by frame. At the same time, the servo circuit 10 causes the video tape stop period signals c and H.
The point that SWb is output and the field memory write reference signal e is generated based on HSWb among them is the same as the operation described in the conventional example.

The delay circuit 14 delays the writing reference signal e by the time kt shown in FIG. On the other hand, the gate circuit 16 conditions the video tape stop period signal c and HSWb from the servo circuit 10, and the write reference signal f is obtained by delaying the horizontal sync signal h on the write / playback signal side during the video tape stop period. The positional relationship detection circuit 15 detects whether or not there is a falling edge of a plurality of times during one cycle of the slow motion operation. Then, when the horizontal synchronization signal h is not present, the output of the positional relationship detection circuit 15 remains in the previous state, and when the horizontal synchronization signal h is present, the output of the positional relationship detection circuit 15 is inverted,
The changeover switch 18 is set in the opposite state to the previous state, and the time constant circuit 17 is connected to or disconnected from the delay circuit 14.

That is, the timing chart shown in FIG. 3 becomes t0, t1, and t2, and the previous state is t0.
When it is determined that the horizontal synchronization signal h is present when the time constant circuit 17 is connected, the time constant circuit 17 is disconnected,
The delayed write reference signal comes to the position of t1. When the previous state is t0 and the time constant circuit 17 is disconnected, when it is determined that the horizontal synchronizing signal h is present, the time constant circuit 17 is connected and the delayed write reference signal is t.
Position 2 Here, by setting the time constant circuit 17 so that the delay amount of the delay circuit 14 which changes in the time constant circuit 17 becomes 1/2 horizontal synchronizing signal period, the video tape controlled by the servo circuit 10 is controlled. If the stop accuracy (variation width) <1/2 horizontal sync signal period, once the presence or absence of the horizontal sync signal h is determined, at the falling edge of the delayed write reference signal f, the write of FIG. , The m-th horizontal synchronizing signal h is prevented from moving back and forth, and the reproduction signal written in the field memory 6 is written in a regular position each time, and is displayed together with the delay of the reference signal over kt time. This will prevent vertical vertical movement of the screen.

Although the slow motion reproduction using the field memory 6 has been described in the above embodiment, the same effect as in the above embodiment can be achieved even in the frame advance reproduction and other intermittent reproduction operations.

[0020]

As described above, according to the present invention, during intermittent playback such as slow-motion playback or frame-by-frame playback
Horizontal synchronization of video signal writing to field memory
By avoiding the missing parts of the signal,
Relative memory address and horizontal sync signal of video signal
It is possible to prevent a large displacement of the position,
The movement can be suppressed. Also stop videotape
Horizontal alignment at the position of the write reference signal delayed by the period
If the horizontal sync signal is detected by detecting the presence or absence of the synchronization signal
The delay amount of the delay means for a predetermined time, especially when the video signal
Change for 1/2 cycle of the flat sync signal
To the field memory due to the fluctuation of the servo circuit.
Write by preventing relative fluctuation of the video signal writing position
Always keep the positional relationship between the reference signal and horizontal sync signal constant and
Vertical deviation of the image signal on the display screen
In addition, it is easy to see by removing the horizontal shift of one horizontal sync signal.
You can get the playback video.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart showing signal waveforms of respective parts of FIG.

FIG. 3 is a timing chart showing signal waveforms of respective parts of FIG.

FIG. 4 is a block diagram showing a configuration of a conventional video recording / reproducing apparatus.

FIG. 5 is a timing chart showing signal waveforms of respective parts of FIG.

FIG. 6 is a timing diagram showing signal waveforms of respective parts of FIG.

FIG. 7 is a timing chart showing signal waveforms of respective parts of FIG.

[Explanation of symbols]

 13 write reference signal circuit 14 delay circuit 15 positional relationship detection circuit 16 gate circuit 17 time constant circuit 18 changeover switch

Claims (3)

(57) [Claims] 1. A video signal recorded on a video tape
In the video playback device that plays intermittently, the video signal played from the above video tape is played during intermittent playback.
A field memory for storing, write based on the head switching signal to said field memory
A write reference signal generating means for generating a write reference signal, the reference signal the write reference signal generating means has generated water
Predetermined predetermined so as to avoid the missing part of the flat sync signal
Delay means for time delay, based on the reference signal delayed by the delay means, the fee
Memory controller that controls the storage of video signals in the field memory.
An image reproducing apparatus characterized by comprising a step . 2. A video signal recorded on a video tape
During the video tape stoppage during intermittent playback, the above delay
The presence or absence of the horizontal sync signal at the extended reference signal position is detected.
Positional relationship detection means to be output, When the positional relationship detecting means detects a horizontal synchronizing signal
Time constant means for changing the delay amount of the delay means for a predetermined time
The video reproducing apparatus according to claim 1, further comprising:
Place. 3. The change of the delay amount by the time constant means,
Set to 1/2 cycle of the horizontal synchronizing signal of the above video signal
The video reproducing apparatus according to claim 2, wherein