JPH0832000B2 - Magnetic recording / reproducing device - Google Patents

Description

The present invention relates to a magnetic recording / reproducing apparatus using a magnetic tape of the present invention, and more particularly to a magnetic recording / reproducing apparatus capable of realizing a high-speed reproduction screen without noise bars.

[Conventional technology]

FIG. 7 is a plan view showing a conventional magnetic recording / reproducing apparatus disclosed in, for example, Japanese Patent Laid-Open No. 61-51684.
Reference numeral 1 is a deck chassis, 2 is a tape cassette mounted on the deck chassis 1, 3 is a supply side reel of the tape cassette 2, 4 is a winding side reel, and 5 is a magnetic tape. 6
Is a cylinder mounted on the deck chassis 1, 7a and 7b are rotary magnetic heads mounted on the cylinder 6, 8 and 9 are guide rollers provided on both sides of the cylinder 6, 10 and 1
1 is a slant pole. 12 is a first fixed magnetic head for erasing the entire width of the magnetic tape 5, 13 is a second fixed magnetic head for recording control signals and time code signals, 14 is a tension pole, 15 is a capstan shaft, 16 is a capstan It is a pinch roller pressed against the shaft 15.

FIG. 8 is a view showing a tape pattern recorded by the apparatus shown in FIG. 7, and FIG. 9 is a view showing a gap portion of the second fixed magnetic head 13 of FIG.

In FIG. 9, 13a is a first time code recording gap A, 13b is a second time code recording gap B, and 13c is a control signal recording gap C. Further, in FIG. 8, 17 is a video information track recorded by the rotary magnetic heads 7a and 7b, 18 is a video information track which is being completely erased by the first fixed magnetic head 12, and 19 is a track recorded by the gap A13a. A time code track 1 and a control track 20 are recorded by the gap C13c. In FIG. 8, arrow A indicates the traveling direction of the magnetic tape 5.

 Next, the operation will be described.

In FIG. 7, the magnetic tape 5 runs in the direction A shown in FIG. 8 by the rotational drive of the capstan shaft 15 and is in the recording mode. The rotary magnetic heads 7a and 7b mounted on the cylinder 6 are controlled so as to rotate 1/2 in one field, and the video signal is diagonally recorded on the magnetic tape 5 by the rotary magnetic heads 7a and 7b. It will be recorded as 17. When the magnetic tape 5 is a recorded tape, the entire width is erased by the first fixed magnetic head 12 and the tape runs in the direction of the cylinder 6. At the same time as recording by the rotating magnetic heads 7a, 7b, the second fixed magnetic head 1
By 3, the first time code track 19 and the control track 20 are recorded.

During reproduction operation at normal speed, the magnetic tape 5 is run in the A direction by the capstan shaft 15 while reading the CTL signal from the control track 20. That is, the cylinder 6 is driven by the built-in rotation speed detecting means so that the cylinder 6 rotates 1/2 rotation in one field of the video signal.
The rotation speed of the capstan shaft 15 is controlled so that the cycle of the CTL signal synchronized with the rotation speed of the cylinder 6 can be detected. During this normal reproduction, the running position of the magnetic tape 5 can be read by reproducing the first time code track 19 recorded by the gap A13a.

When traveling in the reverse direction, the second time code track 21 can be recorded by the gap B13b. That is, the second time code track 21 is recorded by the gap B13b when the magnetic tape on which the video information track 17 has been recorded in the forward direction is reproduced in the reverse direction. If the second time code track 21 is recorded in this way, then by reading the signal of the first time code track 19 during the forward reproduction and by reading the signal of the second time code track 21 during the backward reproduction. The tape traveling position can be detected.

During fast forward playback, as shown in Fig. 7, the pinch roller 16
Is held in contact with the capstan shaft 15, while the capstan shaft 15 rotates at high speed and the magnetic tape 5 runs at high speed. Since the cylinder 6 is rotated at the same number of revolutions as in the normal reproduction, the scanning loci of the rotary magnetic heads 7a and 7b intersect the video information track 17 shown in FIG. Therefore, the obtained image will be an image including a noise bar. The noise bar generated in the horizontal direction is related to the fast-forward reproduction speed. When the fast-forward speed is slow, the number of noise bars is small, but when the fast-forward speed becomes high, the number of noise bars increases and the screen becomes difficult to see.

The pinch roller 16 is used during fast-reverse playback as in fast-forward playback.
Is in contact with the capstan shaft 15
This is done by reverse rotation of 15 at high speed. At this time as well, as in the case of fast-forward reproduction, the scanning loci of the rotary magnetic heads 7a and 7b intersect with the video information track 17, so that the obtained image becomes an unreadable screen including noise bars.

The first time code track during fast forward playback
The running position of the magnetic tape 5 can be known by reading the signal of 19 and reading the signal of the second time code track 21 at the time of fast reverse reproduction.

However, when sending the magnetic tape to a desired position while observing the contents of the image, there was no choice but to look at the screen including the noise bar generated by the rotary magnetic heads 7a and 7b.

[Problems to be Solved by the Invention]

Since the conventional magnetic recording / reproducing apparatus is configured as described above, when reproducing at a high speed and searching for a desired position while looking at the screen, it is necessary to do this on an unsightly screen containing many noise bars. There was a problem.

The present invention has been made to solve the above-mentioned problems, and it is possible to search for a desired position while looking at a good screen without causing horizontal noise bars on the screen even when playing back at high speed. An object of the present invention is to obtain a magnetic recording / reproducing device capable of performing

[Means for solving the problem]

The magnetic recording / reproducing apparatus according to the present invention, after A / D converting the video signal recorded by the rotary magnetic head during recording,
Write to the memory, read this at a sync frequency lower than the field frequency of the original video signal, D / A convert it, and then use the fixed magnetic head to find the cue recorded on the cue image information track. Video signals are played back by a fixed magnetic head during high-speed playback, and the playback signals are A / D
After the conversion, the data is written in the memory and read out according to the control signal from the memory control circuit to which the screen switching time control circuit is connected.

[Action]

In the present invention, at the time of recording, the cue video signal recorded on the cue video information track is reproduced at high speed after the predetermined field signal or frame signal in the original video signal is converted to the synchronizing frequency. Sometimes it is played back from the cue video information track, this field signal or frame signal is rearranged at the field frequency of the original video signal, and the field repetition or playback cycle is changed according to the time set by the screen switching time control circuit. Since the frame video is displayed on the monitor, it is possible to search while viewing an image without noise bars.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a magnetic recording / reproducing apparatus according to an embodiment of the present invention. In the figure, the same symbols as in FIG. 7 are the same or corresponding parts. Reference numeral 13 'is a second fixed magnetic head for recording and reproducing a control signal and an intermittent video signal.

FIG. 2 is a diagram showing a tape pattern recorded by the apparatus shown in FIG. 1, and FIG. 3 is a diagram showing a gap portion of the second fixed magnetic head 13 'of FIG. In these figures, 13d is a gap D for recording / reproducing intermittent video signals, 13c is a gap C for recording / reproducing control signals, 17 is a video information track recorded by the fixed magnetic heads 7a, 7b, and 18 is a first information track. The video information track being erased by the rotary magnetic head 12 on the full width, 22 is the cue video information track recorded by the gap D13d, and 20 is the gap.
There is a control track recorded by C13c. In FIG. 2, the arrow A indicates the traveling direction of the magnetic tape 5.

FIG. 4 (a) is a block diagram showing a recording circuit system when the cue image information is recorded on the track 22 by the gap D13d. In the figure, 23 is recorded on the image information track 17 by the rotary magnetic heads 7a and 7b. Same video signal,
Reference numeral 24 is an A / D conversion circuit, 25 is a memory, and 26 is a sync separation circuit for extracting a sync signal from the video signal 23. Reference numeral 27 denotes a memory control circuit, which generates a control signal at the time of writing and reading to the memory 25. 28 is a D / which converts the signal read from the memory 25 into an analog signal.
A conversion circuit, 29 is an FM modulation circuit. A recording amplifier 30 is connected to the gap portion D13d of the second fixed magnetic head 13 '. FIG. 4 (b) is the above A / D in FIG. 4 (a).
FIG. 4C is a diagram showing an output signal output from the conversion circuit 24, and FIG. 4C is a diagram showing a video signal read from the memory 25. The shaded field signals in FIG. 4 (b) correspond to the shaded areas in FIG. 4 (c).

FIG. 5 (a) is a block diagram showing a reproducing circuit system for reproducing a signal from the cueing video information track 22 at the time of fast-forward reproduction, in which 31 is a gap D13d of the second fixed magnetic head 13. Reproduction amplifier for amplifying the output signal, 32 FM demodulation circuit, 33 A / D conversion circuit, 34 memory, 3
5 is a memory control circuit for sending control signals to the memory 34 at the time of writing and reading, 36
Is a sync signal generator which, when read from the memory 34, generates a sync signal having the same frequency as the video signal reproduced from the video information track 17 of FIG. Reference numeral 39 is a screen switching time control circuit for setting the holding time of the field signal at the time of reading from the memory 34 in the memory control circuit 35, and the same field signal is read from the memory 34 within the time set by this circuit. Becomes 37 indicates a D / A conversion circuit, and 38 indicates a video signal displayed on a television or the like.

FIG. 5B is a diagram showing an output signal outputted from the A / D conversion circuit 33, and FIG. 5C is a diagram showing a video signal read from the memory 34. In FIG. 5 (c), the video signals are arranged for each frequency generated by the synchronizing signal generator 36, and the same shaded area in FIGS. 5 (b) and 5 (c) indicates the same field signal. Shows.

 Next, the operation will be described.

In the magnetic recording / reproducing apparatus of FIG. 1, when the video signal is recorded on the magnetic tape 5, the cylinder 6 is adjusted so that 1/2 rotation of the cylinder 6 corresponds to the field frequency f _V of the video signal.
Is driven to rotate at a constant speed. The magnetic tape 5 is wound around the cylinder 6 by 180 °, and the rotary magnetic heads 7a and 7b are arranged at positions facing each other by 180 °. Therefore, the section where the rotary magnetic head 7a is in contact with the magnetic tape 5 Then first
Record video signal in the field, then rotary magnetic head
The video signal of the second field is recorded in the section where 7b is in contact with the magnetic tape 5, and the video signal of one frame is recorded by one rotation of the cylinder 6. The magnetic tape 5 is made to run in the direction A shown in FIG. 2 by the rotational drive of the capstan shaft 15. The running speed is a preset constant running speed. In this way, the magnetic tape 5 is run, and the rotary magnetic head is
Recorded at 7a and 7b. In the so-called recording mode, the magnetic tape 5 is moved by the gap C13c of the second fixed magnetic head 13 '.
The control track 20 is recorded at the lower end of the.
In addition, since there is a case of newly recording on a magnetic tape that has already been recorded, in the above recording mode, the first fixed magnetic head 12 is provided prior to the cylinder 6, and the video signal is recorded after erasing the entire width. It will be.

In this embodiment, an intermittent video signal is recorded on the cue video information track 22 by the gap D13d provided in the second fixed magnetic head 13 'in the above recording mode. This will be described in detail with reference to FIGS. 2 and 4. In FIG. 2, reference numeral 17 is a video information track on which a video signal is recorded by the rotary magnetic head 7a or 7b.
The above video signal is transferred to the recording circuit system of FIG.
Can be input as, and processed by this recording circuit system and written in the cue video information track 22. The processing in this recording circuit system is as follows. Video signal 23 is A /
It becomes a digital signal in the D conversion circuit 24. This signal is, as shown in FIG. 4 (b), the field frequency of the video signal.
and it has a side-by-side signal for each f _V. This signal is stored in memory 25
The memory control circuit which obtains the sync signal from the sync separation circuit 26 connected to the video signal 23.
According to 27, only the predetermined field signal is input to the memory 25. For example, when the field signal 1a is input to the memory 25 in FIG. 4 (b), the subsequent field signal is not accepted and the memory control circuit
It is read from the memory 25 at a low clock frequency by the control signal of 27. FIG. 4 (c) shows the read signal. The next field signal input to the memory 25 is 1b, which is also the preceding field signal.
After 1a, the data is read out as shown in FIG. 4 (c). These read signals are converted into analog signals by the D / A conversion circuit 28, and then the FM modulation circuit 29 and the recording amplifier 3
After 0, cue video information track 2 by gap D13d
Written to 2.

Although the video signal is also recorded on the video information track 17, the relationship with the field signal written on the cue video information track 22 will be described with reference to FIG. That is,
In FIG. 2, the shaded tracks show the same field signal, and the field signal written in the video information track 17a and the field signal written in the cue video information track 22a are the same, and 17b is 22b below. , 17
The same field signal is sequentially written such that c is 22c. In the video information track 17, tracks not shaded are field signals thinned out by the memory control circuit 27 of FIG. 4 (a).

 Now, as an example, an actual numerical value will be shown.

In Fig. 1, the cylinder diameter is 62 mm, the magnetic tape feed speed V _T = 33.35 mm / sec, the field frequency f _{V of the} video signal.
= 60 Hz, the video information track 17 in FIG. 2 has a track length L _V ≈97.4 mm and a track pitch P _V = 59 μm. The recording density (recording wavelength) on the cue image information track 22 and the recording density on the image information track 17 are set to be the same.
That is, assuming that the track lengths are set to be the same, the field frequency f _V1 at the time of reading shown in FIG. 4 (c) can be calculated as follows.

Since the original field frequency f _V = 60Hz, Therefore, every 175 fields, the video signal of one field is recorded on the cue video information track 22.

Next, the reproducing operation of the magnetic tape thus recorded will be described.

Since the cue image according to the present invention is not necessary during reproduction at normal speed, reproduction at the time of fast forward or fast reverse will be described here.

In the fast-forward reproduction, the capstan shaft 15 is rotated at a high speed while the magnetic tape 5 is wound around the cylinder 6, so that the magnetic tape 5 travels at a high speed in the direction A in FIG. In FIG. 2, the signal read by the gap D13d of the second fixed magnetic head 13 'becomes a video signal through the reproducing circuit system shown in FIG. 5 (a). That is, the reproduction amplifier
The signal becomes a digital signal through 31, FM demodulation circuit 32 and A / D modulation circuit 33 and is input to the memory 34. The input signal at this time is the field frequency to be finally obtained as shown in FIG. 5 (b). The frequency is different from f _V. Now, FIG. 5 (b)
Field frequency f _V2 <f _V at. An input signal of the memory 34 is controlled by a memory control circuit 35, and a screen switching time control circuit 39 of the memory control circuit 35 defines a field signal switching time. Then, the memory control circuit 35 finally produces the same synchronizing frequency as the field frequency f _{V of the} video signal to be displayed on the monitor by the action of the synchronizing signal generator 36, so that the signal output from the memory 34 becomes the field frequency f _V. Are lined up. For example f _V2 = 1/2 · f _V
Then, if the setting value of the switching time from the screen switching time control circuit is T = 6 × 1 / f _V , the field signal among the field signals 1a, 2a, 3a, ... 1a is written to memory 34, but field signals 2a, 3
a is not accepted. Then, as shown in FIG. 5C, the field signal 1a for 6 fields is read out. The field signal 4a is written to the memory 34 next to the field signal 1a, and this is also read as the field signal 4a for 6 fields.
The signals read from the memory 34 in this way are arranged at the field frequency f _V , and are converted into analog signals by the D / A conversion circuit 37 to become video signals.

Now, as an example, an actual numerical value will be shown. If you set the fast-forward speed to 50 times as fast-forward playback of the magnetic tape recorded with the numerical values of the specific example in the above recording mode, ， From the formula, Becomes That is, 1 / f _V2 = 3.5 × 1 / f _V ....

Further, if the switching time at the time of reading the field signal by the screen switching time control circuit 39 is set to T = 0.5 seconds, then f _V = 60 Hz, so after the same field signal is read for T × f _V = 30 fields, The next field signal is read out.

FIG. 6 (a) shows the output signal of the memory 34 when a new field signal is input to the memory 34 without setting the switching time by the screen switching time control circuit 39, and is processed and output. FIG. 6 (b) shows the output signal of the memory 34 when the switching time by the screen switching time control circuit 39 is set to T = 0.5 seconds. As shown in the figure, when the switching time is not set, the field signal 1a is divided into 3 fields, the field signal 2a is divided into 4 fields, the field signal 3a is divided into 3 fields, and the same field signal is divided into 3 fields and 4 fields. You can see that it is being output. When the switching time is set to T = 0.5 seconds, the first 30 fields are all field signals.
1a is output. At the 31st field, the memory 34
Since the signal written in is the field signal 9a, the field signal 9a is output for all the next 30 fields. In this way, for example, the switching time is T = 0.
If you set it to 5 seconds, you will get a continuous video of still images every 0.5 seconds.

 Next, the operation at the time of fast reverse reproduction will be described.

Similarly to the fast forward reproduction, the fast reverse reproduction is performed by rotating the capstan shaft 15 in the reverse direction at a high speed while the magnetic tape 5 is wound around the cylinder 6, but in FIG. The reading direction of the cueing video information track 22 by the gap D13d of the fixed magnetic head 13 'is opposite to that in the fast forward reproduction. Also in this case, basically, a reproducing circuit as shown in FIG. 5 (a) can be used. Reproduction amplifier 31
From the input to the memory 34, it is the same as during fast-forward reproduction, but when read by the control signal of the memory control circuit 35, the desired video signal is read by reading in the direction opposite to the signal input to the memory 34. Can be played.

In this way, the images obtained by the fast-forward reproduction and the fast-reverse reproduction are complete field images, no noise bar is generated even in the high-speed reproduction, and the high-speed reproduction speed is not affected.

Further, by setting the switching time of the screen switching time control circuit 39 arbitrarily, it is possible to obtain a search image that is easy to see.

Although the field signal is recorded and reproduced on the cue video information track 22 in the above embodiment, it may be a frame signal.

Although the memories 25 and 34 have not been described in detail, the signals shown in FIG. 4 (c) may be read while writing the signals shown in FIG. 4 (b) to the memory 25, for example. Or field memory 2
Even if one field memory is used for writing, one field memory is read while the other field memory is read, and when this read operation is completed, the input and output of the two memories are switched to read the next field signal. Good. The same applies to the memory 34. While the two field memories are used to write the signal of FIG. 5 (b) in one field memory, the signal of FIG. 5 (c) is output from the other field memory. The read operation and the write and read operations may be performed by switching the two memories.

Further, in the embodiment shown in FIG. 1, the gap C13c for recording / reproducing the control signal and the gap D13d for recording / reproducing the cue video information are built in the same fixed magnetic head. It doesn't matter.

〔The invention's effect〕

As described above, according to the present invention, in the magnetic recording / reproducing apparatus, at the time of recording, the predetermined field signal or frame signal in the original video signal is converted to the synchronous frequency and recorded on the cue video information track for high speed reproduction. Sometimes the field signal or frame signal reproduced from this cue video information track is rearranged to the field frequency of the original video signal so that it is displayed on the monitor, and the switching time of this field signal or frame signal can be set arbitrarily. Since the configuration is adopted, there is an effect that a noise bar does not occur in an image even at the time of high-speed reproduction, and an apparatus capable of searching while looking at a good and easy-to-see screen can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing a magnetic recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a view showing a tape pattern recorded by the apparatus of FIG. 1, and FIG. 3 is used for the apparatus of FIG. FIG. 4A is a detailed view of a fixed magnetic head to be used, FIG. 4A is a block diagram of a recording circuit for explaining recording by the apparatus of FIG.
4 (b) and 4 (c) are diagrams showing recorded signals, and FIG.
FIG. 5A is a reproduction circuit block diagram for explaining reproduction by the apparatus of FIG. 1, FIGS. 5B and 5C are diagrams showing reproduced signals, and FIGS. 6A and 6C. FIG. 7B is a diagram showing a reproduced signal when actual numerical values are used, FIG. 7 is a plan view showing a conventional magnetic recording / reproducing apparatus, and FIG. 8 shows a tape pattern recorded by the apparatus shown in FIG. FIG. 9 is a detailed view of the fixed magnetic head of the apparatus shown in FIG. 5 ... Cylinder, 6 ... Magnetic tape, 7a, 7b ... Rotating magnetic head, 13 ... Second fixed magnetic head, 24, 33 ... A / D
Conversion circuit, 25,34 …… Memory, 38,37 …… D / A conversion circuit, 2
7,35 …… Memory control circuit, 22 …… Cue video information track, 39 …… Screen switching time control circuit. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A rotary magnetic head which is provided on the outer circumference of a rotating cylinder, and which scans a magnetic tape running around the outer peripheral surface of the cylinder at a predetermined angle at an angle with respect to the traveling direction thereof to record or reproduce a video signal, A magnetic recording / reproducing apparatus having a fixed magnetic head arranged so as to record or reproduce a signal on the magnetic tape in the traveling direction, wherein the video signal is recorded at a timing of a predetermined field signal or frame signal during recording. The recording field signal or frame signal reproduced from the fixed magnetic head during high-speed running is composed of a recording signal processing unit for writing on the magnetic tape by the fixed magnetic head, a reproduction amplifier, an FM modulator, and an A / D changing circuit. A reproduced signal processing unit for converting into a signal, a memory for temporarily storing the digital signal, And a screen switching time control means for controlling the timing of recording the Le signal to the memory, a magnetic recording and reproducing apparatus characterized by reproducing the still picture is switched in between any screen switching regardless high speed.