JPH07272355A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To stably reproduce a reproducing video signal by calculating a head scanning locus with a head pair switching signal, a reproducing control signal and a capstan frequency generating signal as inputs in a memory control part. CONSTITUTION:A memory control part 1 calculates a head scanning locus with a head pair switching signal S12 as a head pair switching signal, a CTL signal S6 formed by reproducing a control signal (CTL signal) recorded in a magnetic tape and a capstan frequency generating signal (CAP, FG signal) outputted following the rotation of a capstan as inputs and based on these inputted signals and outputs a combination head switching signal S8 and a memory writing permitting signal S2. Thus, by writing stable video signals having a small difference in reproducing leves within one field in a memory part 2, a reproducing video signal in one field is reproducd only from a one video track even during linear slow reproducing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus such as a VTR having a special reproduction function of video.

[0002]

2. Description of the Related Art In recent years, magnetic recording / reproducing devices have become widespread, and there are increasing opportunities for not only performing normal recording / reproducing but also using special reproduction (especially slow reproduction) for image analysis or soft tape production. is doing. However, during linear slow playback in which the running speed of the magnetic tape is simply slowed (the rotation frequency of the capstan is 1 / n), the scanning tracks of the video track recorded on the magnetic tape and the video playback head are greatly deviated. Therefore, the video reproducing head always scans the adjacent video track, and cannot completely scan the video track of the original field to be reproduced, and that portion becomes noise.

Therefore, in order to obtain an image with as little noise as possible during linear slow reproduction, a combination head system or a digital memory in which two image reproducing heads having different azimuth angles are closely arranged is used.

A conventional magnetic recording / reproducing apparatus adopting a combi-head system and a digital memory during slow reproduction is constructed as shown in FIGS. 6 and 7. FIG. 6 shows the structure of a digital memory, and FIG. 7A shows the structure of a combi-head type cylinder. FIG. 7B shows the relationship between the video track, the scanning trace of the combination head, and the reproduction portion.

In FIG. 6, S1 is a reproduced video signal, 14
Is a video output detection unit which determines whether or not the video output of the reproduced video signal S1 is at or above a specified level, and outputs a combination head switching signal S8 when it does not exceed the specified level. 1
Reference numeral 5 is a memory that reads and writes the reproduced video signal S1, writes the reproduced video signal S1 at the timing of the write clock S9, and reads the written contents at the timing of the read clock S10. S11 is a memory output output from the memory 15.

In FIG. 7A showing a combination head type cylinder, reference numeral 16 is a rotary cylinder to which a pair of combination heads are attached, and image reproducing heads 17A, 17
B, 18A and 18B are attached. The video reproducing heads 17A and 18A have an azimuth angle of A, and the video reproducing heads 17B and 18B have an azimuth angle of B.
The video reproducing head 17A and the video reproducing head 17B form a combination head. The video reproducing head 18A and the video reproducing head 18B form a combination head.
Reference numerals 19a and 19b are head pair change-over switches, and the video reproducing heads 17A and 17B are operated by a head pair change-over signal S12.
And the video reproduction heads 18A and 18B. Reference numeral 20 denotes a combination head changeover switch, which changes over the combination reproduction head switching signal S8 between the combination reproduction heads 17A and 17B or 18A and 18B. S11 is a reproduced video signal reproduced by the video reproducing head.

In the scanning track of the video track and the combination head shown in FIG. 7B, 9 is a video track recorded on the magnetic tape, and 21 A and B azimuth are the video tracks recorded with A azimuth. 2 video tracks
1B, 22A is the part reproduced by A azimuth head of the combination head, and 22B is the part reproduced by B azimuth.
Is represented as.

Next, the operation of the apparatus configured as described above will be described. A video recording / reproducing apparatus (hereinafter referred to as VTR) using a magnetic tape as a recording medium records adjacent video tracks with video reproducing heads having different azimuth angles in order to eliminate the guard band and increase the track density of the magnetic tape. Most of the devices adopt a system (tilted azimuth recording system) capable of reproducing only with a video reproducing head having the same azimuth angle as recorded due to loss. When linear slow reproduction is performed by such a VTR of the tilted azimuth recording system, the scanning track of the video track and the video reproducing head is deviated and the adjacent track is always scanned, so that the track portion of the reverse azimuth is not reproduced. Therefore, in a combination head type VTR, a video reproducing head 17A having A azimuth and a video reproducing head 18B having B azimuth are attached to the rotary cylinder 16 so as to face each other by 180 °, and the reverse azimuth is preceded by each video reproducing head. The image reproducing heads 17B and 18A having the same are attached to form a pair of combination heads having both azimuths. Based on a head pair switching signal S12, which one of the video reproducing heads 17A and 17B is used or the video reproducing heads 18B and 18A is used to scan a video track, the head pair changeover switch 19a,
19b selects.

Video track 21 recorded in A azimuth
When the combination head of the image reproducing heads 17A and 17B scans from A, the combination head changeover switch 20 is controlled by the combination head changeover signal S8 so that the image reproducing head 17A having A azimuth reproduces the portion of the image track 22A. However, as the video reproducing head scans, more parts scan the video track 21B recorded in B azimuth. At this time, the reproduced video signal S1
If the level is below the specified level, the video output detector 1
4 determines that the reverse azimuth video track is being reproduced, and the combination head switching signal S8 issues a command to switch the combination head to the reverse azimuth side. That is, the combination head changeover switch 20 is controlled by the combination head changeover signal S8 so that the image reproducing head 17B having B azimuth reproduces the portion 22B of the image track 21B.
In this way, the reproduced video signal S1 is obtained.

Further, in order to make the reproduced video signal S1 thus obtained a more stable video signal, the reproduced video signal S1 is written in the memory 15 at the timing of the write clock S9 and read at the timing of the read clock S10. The memory output S11 is output as a reproduced video output.

[0011]

However, as described above, in the conventional apparatus, the video of two adjacent video tracks are mixed in the playback video signal of one field during the linear slow playback, and the video of one field is reproduced. There is a problem that the reproduced video signal does not reproduce one video track and an incomplete video is reproduced.

It is an object of the present invention to provide a magnetic recording / reproducing apparatus capable of reproducing a reproduced video signal of one field only from one video track even during linear slow reproduction.

[0013]

According to the structure of claim 1, a video signal reproduced by a pair of heads mounted on a rotary cylinder is written, and at least two memories each corresponding to a video track of one field are included. A memory control unit for outputting a memory switching signal designating a memory to be written to the memory unit and a memory write permission signal; and the memory control unit for controlling a head pair switching signal for switching the head pair. A head scanning locus is calculated by inputting a reproduction control signal reproduced from the magnetic tape and a capstan frequency generation signal output with the rotation of the capstan that runs the magnetic tape in the longitudinal direction, and the memory is calculated based on the calculation result. It is predicted that the video track and the video playback head scan will match near the center by controlling the switching signal. Wherein the timing of the scanning and to output the memory write enable signal.

According to a third aspect of the present invention, a memory section for writing a video signal reproduced by a pair of heads attached to a rotary cylinder and including two or more memories respectively corresponding to video tracks of one field, and the memory. A memory control section for outputting a memory switching signal for designating a memory to be written to the section and a memory write permission signal, and a head pair switching signal for switching the head pair to the memory control section and a reproduction control reproduced from a magnetic tape. The signal and the capstan frequency generation signal output along with the rotation of the capstan that runs the magnetic tape in the longitudinal direction are input, and the memory control unit is input first after the reproduction control signal is input. The edge of the capstan frequency generation signal is set to "0" and the cap for one track pitch is set. A capstan frequency generation signal counter that complements the counter value when the stun frequency generation signal is input is provided, and the timing of the reproduction control signal is predicted based on the count value of the capstan frequency generation signal counter. It is characterized in that the memory switching signal is switched before the expected timing to output the memory write enable signal.

[0015]

According to the structure of the present invention, the memory control section calculates the head scanning locus with the head pair switching signal, the reproduction control signal and the capstan frequency generation signal as inputs.
The memory switching signal is controlled based on the calculation result, and the memory write enable signal is output at the timing of the scan where the video track and the video playback head scan are expected to match near the center to output the video signal during special playback to the memory section. Since it is written, it is possible to write a stable video signal with a small difference in the reproduction level of the video signal in one field to the memory, and to reproduce the reproduction video signal of one field even during linear slow reproduction.
It can only be played from one video track.

According to the third aspect of the present invention, the memory control unit uses the capstan frequency generation signal counter to switch the memory switching signal before the control signal is input. Therefore, the rotation of the rotary cylinder and the capstan during the linear throw. Regardless of the phase of travel, even when the rotation of the rotary cylinder and the phase of capstan travel are not in phase during linear throw, a stable video signal with a small difference in the reproduction level of the video signal in one field is stored in the memory section. Can be written to, and the playback video signal of one field can be played back from only one video track even during linear slow playback.

[0017]

Embodiments of the magnetic recording / reproducing apparatus of the present invention will be described below with reference to FIGS.

1 to 4 show a first embodiment. A magnetic recording / reproducing apparatus of the present invention which employs a combi-head system and a digital memory at the time of linear throw is configured as shown in FIG. 1. S1 is a reproduced video signal, 1 is a memory controller, and a head pair switching signal S12. , A control signal recorded on a magnetic tape (hereinafter abbreviated as CTL signal), a CTL signal S6, and a capstan frequency generation signal (hereinafter referred to as CAP.
FG signal) abbreviated as S7 as an input, the head scanning locus is calculated based on the above input signals, and the combination head switching signal S
8 and the memory write enable signal S2. Reference numerals 3 and 4 denote first and second memories, respectively, which correspond to a field in which a track of A azimuth is reproduced and a field in which a track of B azimuth is reproduced. Reference numeral 7 denotes an exclusive OR gate, which receives the head pair switching signal S12 and the combi-head switching signal S8 at its inputs, and outputs a memory switching signal S4 which is the exclusive OR of both. Switch 5
Is the first memory to be written by the memory switching signal S4.
The memory 3 or the second memory 4 is switched. Switch 6
Switches to output the video signal read from the memory opposite to the memory performing the writing operation as the memory output S3.

The cylinder block of this embodiment has the structure shown in FIG. 7 (a) as in the conventional example. FIG. 2A shows the relationship between the video track 11 and the scanning locus of the video reproducing head when the reproduction is performed at 1/4 speed in this embodiment in order for every half rotation of the rotary cylinder. The video track of is recorded in A Azimuth. Of the reproduced video signal S1 shown in FIG.
Are corresponding to the video track 11 of A azimuth reproduced by the video reproducing head. 2C and 2D show the timings of the head pair switching signal S12 and the memory switching signal S4 at the 1/4 speed during linear throw.

FIG. 3 is a timing chart of the memory write enable signal S2. In FIG. FG signal S
A count value S2 of a capstan frequency generation signal counter (hereinafter, abbreviated as CAP.FG counter) 8 that counts 7
0 is the first input CAP.0 after the CTL signal S6 is input. It becomes "0" at the edge of the FG signal S7,
CAP. For one track pitch (hereinafter, abbreviated as TP). F
When the G signal S7 is input, "1TP" to "-1T"
It is configured to be P ″.

Next, the operation of this embodiment configured as described above will be described. In order to eliminate the guard band and increase the track density of the magnetic tape, a video recording / reproducing apparatus using a magnetic tape as a recording medium records adjacent video tracks with video reproducing heads having different azimuth angles and recorded due to azimuth loss. It adopts a system (tilted azimuth recording system) that can be played back only with a video playback head that has the same azimuth angle. When 1 / n times speed linear slow reproduction is performed by such a magnetic recording / reproducing apparatus of the inclined azimuth recording system, the video reproducing head scans the same video track n times while gradually changing the position, and therefore the azimuth is different. With the rotary cylinder in which the video reproducing heads are mounted facing each other by 180 °, the video track is reproduced only n / 2 times. Therefore, as shown in FIG. 7A, a video reproducing head 17A having A azimuth on the rotary cylinder 16 is provided.
And the video playback head 18B with B azimuth 180 °
The video reproducing heads 17B and 18A having opposite azimuths are attached in front of each of the video reproducing heads so as to form a pair of combination heads having both azimuths. As a result, the combination head changeover signal S8 is used to switch the combinational head changeover switch 20 and the head pair changeover signal S12 is used to change the head pair changeover switches 19a and 19b, so that the video reproducing heads 17A and 18A can move the A azimuth video track 11 to n. It is possible to reproduce n times by scanning once.

Further, during the scan in which the most stable signal (the difference in the reproduction output level within one field) is obtained among the reproduced video signals reproduced by these four scans, the memory write enable signal S2 is obtained. Is output.

These are the CAP. Calculated from the count value S20 of the FG counter 8, and when the count value S20 is from "0" to "1TP" at the edge timing of the head pair switching signal S12, A azimuth,
When "-1TP" to "0", the combination head switching signal S8 is switched so as to reproduce B azimuth, and the exclusive OR of the combination head switching signal S8 and the head pair switching signal S12 is used as the memory switching signal S4. The video signal reproduced from the track recorded in azimuth is written into the first memory 3, and the video signal reproduced from the track recorded in B azimuth is written into the second memory 4. Further, since the write permission signal S2 is output at the scanning timing where the scanning of the video track and the scanning of the video reproducing head coincide near the center of the video track, the CAP. Count value S20 of FG counter 8
But for the first time, “(TP / 2)-(TP / n) -α
“However, 0 <α <(TP / n) count value positive or“-(TP / 2)-(TP / n
) -Α "where 0 <α <(TP / n) count value One field interval with a value greater than or equal to negative is output. Α is a constant determined by the speed mode of the magnetic tape.

In this way, the memory write permission signal S2 is output at the timing of the scan in which the video track and the head scan are predicted to coincide near the center, and the reproduced video signal S1 for special reproduction is written in the memory section 2. It is possible to write a stable video signal having a small difference in the reproduction level of the video signal in one field to the memory unit 2 so that the reproduced video signal of one field can be reproduced only from one video track even during the linear slow reproduction.

FIG. 5 shows a second embodiment. The block diagram of the magnetic recording / reproducing apparatus of the second embodiment is the same as FIG. 1 of the first embodiment, but the output timing of the memory switching signal S4 in the memory control unit 1 is different, and the rotation of the rotary cylinder is changed. A stable signal can be written in the memory unit 2 even when the phases of running of the capstan and the capstan do not match.

Prior to the description of the second embodiment, the waveforms of the respective parts when reproducing at 1/2 speed in the first embodiment will be described with reference to the time chart shown in FIG. In the first embodiment, as described above, the memory switching signal S4 is output at the edge timing of the head pair switching signal S12. When the count value S20 of the FG counter 8 is "0 to 1TP", "-1TP to 0" is displayed on the side of the first memory 3.
At this time, the switch is controlled so as to be switched to the side of the second memory 4, but if the rotation of the rotary cylinder 16 and the phase of the traveling of the capstan do not match as shown in FIG. 4, scanning is continued. In the meantime, the deviation between the video track and the scanning track of the video reproducing head becomes large, and it may be impossible to write a stable signal.

On the other hand, FIG. 5 shows the timing of the CAP. FG
As the counter 8, the CAP. Signal that is input first after the CTL signal S6 is input. The edge of the FG signal S7 is set to "0
”. CAP.FG which takes the complement of the counter value when the CAP.FG signal S7 for one track pitch is input
A counter, S4 is a memory switching signal, and S1 is a reproduced video signal obtained at this time.

When the rotation of the rotary cylinder 16 and the running of the capstan are not in phase, the input timings of the head pair switching signal S12 and the CTL signal S6 are shifted, so that in the first embodiment shown in FIG. , CTL signal S6 is input, the memory switching signal S4 is switched at the next edge of the head pair switching signal S12, whereas in the second embodiment shown in FIG. When the FG counter 8 is used to determine that the timing at which the CTL signal S6 is input is closer to the edge of the head pair switching signal S12 before the edge of the next head pair switching signal S12, the CTL signal S6 is input. The memory switching signal S4 is switched before the switching.

That is, at the linear throw of 1 / n times speed, the CAP. FG
The count value S20 of the counter 8 is (1TP / n
), The CAP. Count value S2 of FG counter 8
0 is -1TP / (2 · n) to 1TP-1TP / (2 ·
n), on the side of the first memory 3, 1TP-1TP / (2 · n) to −1TP / (2 ·
In the case of n), the reproduced video signal S6 becomes more stable as compared with the first embodiment by switching the switch to the side of the second memory 4.

As described above, even when the rotation of the rotary cylinder and the running of the capstan are not in phase during the linear slow-motion reproduction, it is possible to perform the noiseless slow-motion reproduction by writing a stable image in the memory.

The H and L of the memory switching signal S4, the head pair switching signal S12 and the combination head switching signal S8 in each of the above embodiments do not limit the present invention.

[0032]

According to the first aspect of the present invention, a memory unit for writing a video signal reproduced by a pair of heads mounted on a rotary cylinder and including two or more memories respectively corresponding to video tracks of one field, A memory control unit for outputting a memory switching signal designating a memory to be written to the memory unit and a memory write permission signal is provided, and the memory control unit reproduces a head pair switching signal for switching the head pair and a magnetic tape. The head scanning locus is calculated by inputting the reproduced control signal and the capstan frequency generation signal output with the rotation of the capstan that runs the magnetic tape in the longitudinal direction, and the memory switching signal is controlled based on the calculation result. However, the scan timing is predicted to match the video track and the video playback head scan near the center. Since the memory write enable signal is output by the memory, the memory control unit calculates the head scanning locus by inputting the head pair switching signal, the reproduction control signal, and the capstan frequency generation signal, and switches the memory based on the calculation result. The signal is controlled, and the memory write enable signal is output at the timing of the scan in which it is predicted that the video track and the video playback head scan will coincide near the center, and the video signal for special playback is written to the memory section. It is possible to write a stable video signal with a small difference in the reproduction level of the video signal to the memory.

According to a third aspect of the present invention, a memory section including two or more memories for writing video signals reproduced by a pair of heads attached to a rotary cylinder and each corresponding to a video track of one field, and the memory. A memory control section for outputting a memory switching signal for designating a memory to be written to the section and a memory write permission signal, and a head pair switching signal for switching the head pair to the memory control section and a reproduction control reproduced from a magnetic tape. The signal and the capstan frequency generation signal output along with the rotation of the capstan that runs the magnetic tape in the longitudinal direction are input, and the memory control unit is input first after the reproduction control signal is input. The edge of the capstan frequency generation signal is set to "0" and the cap for one track pitch is set. A capstan frequency generation signal counter that complements the counter value when the stun frequency generation signal is input is provided, and the timing of the reproduction control signal is predicted based on the count value of the capstan frequency generation signal counter. Since the memory switching signal is switched before the expected timing and the memory write enable signal is output, the memory control unit uses the capstan frequency generation signal counter to switch the memory before the control signal is input. Since the signal is switched, even if the rotation of the rotary cylinder and the phase of the capstan travel are not in phase during the linear throw, the image in one field is not affected regardless of the phase of the rotation of the rotary cylinder and the capstan travel during the linear throw. Stable video signal with little difference in signal reproduction level Signal can be written in the memory section, and a stable reproduced video signal can be reproduced even when the rotation of the rotary cylinder and the running of the capstan are not in phase during linear slow reproduction.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a digital memory of a first embodiment of a magnetic recording / reproducing apparatus of the present invention.

FIG. 2 is a timing chart of the relationship between the video track and the scanning locus of the video reproducing head, the reproduced video signal, the head pair switching signal, and the memory switching signal, which shows the operation during the 1/4 speed reproduction in the first embodiment.

FIG. 3 is a time chart showing the operation at the 1/4 speed reproduction of the first embodiment.

FIG. 4 is 1 / th of the magnetic recording / reproducing apparatus in the first embodiment.
It is a time chart figure which shows operation | movement at the time of 2x speed reproduction.

FIG. 5 is a time chart diagram showing an operation during half-speed reproduction according to the second embodiment.

FIG. 6 is a block diagram of a conventional digital memory.

FIG. 7 is a block diagram of a rotary cylinder of a magnetic recording / reproducing apparatus of a combi head type.

[Explanation of symbols]

 1 memory control unit 2 memory unit 3 first memory 4 second memory 5, 6 switch 7 exclusive OR gate 8 CAP. FG counter S1 playback video signal S2 memory write enable signal S3 memory output S4 memory switching signal S6 CTL signal S7 CAP. FG signal S8 Combi head switching signal S12 Head pair switching signal S20 CAP. Count value of FG counter

Claims (3)

[Claims] 1. A video signal reproduced by a pair of heads attached to a rotary cylinder is written, and a memory section including two or more memories respectively corresponding to video tracks of one field, and the memory section should be written. A memory control unit for outputting a memory switching signal designating a memory and a memory write permission signal is provided, and the memory control unit controls a head pair switching signal for switching the head pair, a reproduction control signal reproduced from a magnetic tape, and a magnetic tape. A head scanning locus is calculated by inputting a capstan frequency generation signal output with the rotation of a capstan running in the longitudinal direction, the memory switching signal is controlled based on the calculation result, and a video track is generated near the center. The video write head scan is predicted to coincide A magnetic recording / reproducing apparatus that outputs a signal. 2. A count value of a capstan frequency generation signal counter, which calculates a shift amount between a video track and a video reproduction head scan and counts the capstan frequency generation signal at an edge timing of a head pair switching signal, by a memory control unit. , (TP / 2)-(TP / n) -α or-(TP / 2)-(TP / n) -α where TP is one track pitch, 1 / n is double speed during linear slow playback, and α is 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the memory write permission signal is output in one field section at a value equal to or larger than a constant determined by the speed mode of the magnetic tape. 3. A video signal reproduced by a pair of heads attached to a rotary cylinder, and a memory section including two or more memories each corresponding to a video track of one field, and the memory section should be written. A memory control unit for outputting a memory switching signal designating a memory and a memory write permission signal is provided, and a head pair switching signal for switching the head pair to the memory control unit, a reproduction control signal reproduced from a magnetic tape, and a magnetic tape lengthwise. The capstan frequency generation signal that is output with the rotation of the capstan that is driven in the direction is input, and the memory control unit receives the reproduction control signal and then the capstan frequency generation signal that is input first. The edge is set to "0" and the capstan frequency generation signal for one track pitch is A capstan frequency generation signal counter that takes the complement of the counter value at the time of input is provided, and the timing of the reproduction control signal is predicted based on the count value of the capstan frequency generation signal counter. A magnetic recording / reproducing apparatus which outputs the memory write permission signal by switching the memory switching signal to.