JPS62236102A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute a high quality recording and reproducing by providing a signal processing means to recording and reproducing a complex video signal with the first and second rotating magnetic heads. CONSTITUTION:A signal processing means 26A to record and reproduce a complex video signal with the first and second rotating magnetic heads 4a and 4b is provided. For example, when the number of the rotation of a rotating magnetic head is made into two times, a video signal track width recorded by an overwriting system to use an azimuth loss can be halved, and therefore, without changing the traveling speed of a magnetic tape, the highest recording frequency can be made into about 14MHz which is double the previous quantity, and the complex color television signal to be recorded can be directly recorded to the magnetic tape without separating Y and C. Thus, the high quality image can be recorded and reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses a rotating magnetic head to sequentially record and/or record one field's worth of composite video signals on a magnetic tape on tracks inclined with respect to the running direction of the magnetic tape. The present invention relates to a magnetic recording/reproducing device such as a video tape recorder that reproduces a video signal from the track (hereinafter referred to as recording/reproducing).

2. Description of the Related Art In a conventional helical scan type rotary head video tape recorder (hereinafter referred to as VTR), for example, V
Taking the H8 system as an example, in order to record one field of video signals on a single track inclined with respect to the running direction of the magnetic tape, basics such as the diameter of the rotating head cylinder, the width of the magnetic tape, and the dimensions of the tape cassette are required. If a numerical value is determined as a standard, the recording frequency of the signal by the rotating magnetic head will also be determined, and currently the highest recording frequency is about 7 MHz.

Problems to be Solved by the Invention However, even if the highest recording frequency is in a band of about y MHz, it is still not satisfactory for achieving even higher image quality. In that case, the composite color television signal to be recorded.

Although it is extremely effective to separate the color signal and luminance signal, convert the separated color signal to a low frequency, and record it, however, because it is AM recording, horizontal noise is basically displayed on the playback screen. However, there were limits to how high image quality could be achieved.

The present invention aims to provide a magnetic recording/reproducing device that is compatible with the current system (for example, VH8 system) and enables recording/reproducing of even higher image quality.

Means for Solving the Problems In order to solve the above problems, the magnetic recording and reproducing apparatus of the present invention uses first and second rotating magnetic heads to record one field of composite video signals onto a magnetic tape. , a magnetic recording/reproducing apparatus that records/reproduces information using tracks inclined with respect to the running direction, wherein the first and second rotating magnetic heads are rotated at a first rotational speed that is a rotational speed during normal recording;
a rotary head drive means capable of rotating at a second rotation speed that is twice as fast as the first rotation speed; and the rotary head drive means is set to obtain the second rotation speed. In this mode, the apparatus further comprises signal processing means for recording/reproducing a composite video signal using the first and second rotating magnetic heads.

By configuring the present invention as described above, when the number of rotations of the rotating magnetic head is doubled, the recorded video signal track width can be halved by the override method using azimuth loss. , without changing the running speed of the magnetic tape, the maximum recording frequency is approximately 14 MH, double that of the conventional method.
The composite color televised signal (NTSC composite signal) that can be recorded as Y,
Since it is possible to record directly onto a magnetic tape without C separation, extremely high quality images can be recorded/reproduced.

EXAMPLES The present invention will be explained below based on illustrated examples. 1st
The figure is a configuration diagram of essential parts of an embodiment of the present invention, and in the figure, 1 is a magnetic tape, 2 is, for example, a rotating upper cylinder 3a, a fixed lower cylinder 3b, and a cylinder that rotates together with the upper cylinder 3a. First and second rotating magnetic heads 4a and 4b having different azimuth angles, and the rotating magnetic head 4a during reproduction,
The reproduction output from the rotary magnetic head 4b is transmitted to an external circuit, and the signal to be recorded from the external circuit is transmitted to the rotary magnetic head 4 during recording.
This is a rotating head cylinder that includes a rotary transformer (not shown) that supplies power to the cylinders a and 4b.

Reference numeral 5 denotes the first and second rotating magnetic healds 4a.

A head drive motor such as a DC brushless motor is used to rotate the head drive motor 4b together with the upper cylinder 3a in the direction of the rotational arrow G. 6 is a head drive motor that drives the head drive motor 6 to rotate at a predetermined speed in accordance with a control signal given to a terminal 7. This is a motor drive circuit that includes a speed control function for It should be noted that this motor drive circuit 6 operates the first and second rotating magnetic heads 4a, 4b at a normal rotational speed (hereinafter referred to as the first When the output from the mode switching means is given, the first and second rotating magnetic heads 4a, 4b are rotated at a rotational speed twice the normal rotational speed (hereinafter referred to as , this is called the second rotational speed).

The head drive motor 5 is controlled to rotate at 3600 rpm. Here, the head drive motor 6 and the motor drive circuit 6 constitute a rotary head drive means.08 and 9 sandwich the magnetic tape 1 and move at a constant speed in the direction of arrow F (for example, in the case of VH8 type tearing, 33.35 slf /5ec)
capstan and pinch roller for running drive, 1
o is a direct drive type capstan motor for rotating the capstan 8, and 11 is an A/C head for recording/reproducing audio signals and control signals.

Reference numeral 12 designates an input terminal into which a signal to be recorded 9, for example, an NTSC system composite video signal, ie, a color television signal, is input, 13 an input amplifier, 14 an FM modulator, and 16 an output power amplifier. the first and second rotating magnetic heads 4a,
+b constitutes a recording system that records directly on the magnetic tape 1 (that is, without separating Y and C as in the conventional case).
6 is an input amplifier, 17 is a demodulator, 1B is a time base corrector (
T IIB*C= Time Ba5e Correc
tor), 19 is an output amplifier, which constitutes a reproduction system that restores the original color television signal from the reproduction outputs of the first and second rotating magnetic heads 4a and 4b and outputs it to the output terminal 20. ing. 21 connects the fa1 and the second rotating magnetic heads 4a, 4b via a rotary transformer to the output side (b) of the output amplifier 16 of the recording system and the input amplifier 160 of the reproduction system, depending on the recording mode and the reproduction mode. Input side? ) is a changeover switch for switching to either of the following.

22 are first and second rotating magnetic heads 4a, 4b
Therefore, the output signal of the input amplifier 16 and the reproduced signal of A
track number detection means for detecting, based on the reproduction control signal from the /C head 11, that four video signal tracks are recorded at one control signal interval;
3 is for automatically switching the rotary head driving means, that is, the first and second rotary magnetic heads +a, 4b, to the second rotational speed mode in accordance with the output based on the detection operation of the track number detecting means 22; This is mode switching means.

24 is a synchronization signal separation circuit for separating the vertical synchronization signal contained in the color television signal applied to the input terminal 12, and its output is supplied to one input terminal of the phase comparison circuit 26.

Here, the signal processing means 26A includes the elements 12 to 24 described above. Note that 27 is a monitor television receiver for displaying the color television signal obtained at the output terminal 20.

Further, 28 indicates the first and second rotating magnetic heads 4a.
, 4b, and its output (PG multiplied signal is input to the other input terminal of the phase comparison circuit 25 through a shifter 29, which is a variable phase shifter. As shown in FIG. 2, the shifter 29 is located near the lower end of video signal tracks A (shown in a satin pattern in the drawing) and B recorded by the first and second rotating magnetic heads 4a and 4b, respectively. The rotational phase of the head drive motor 5 can be varied by adjusting the phase of the PG multiplied signal so that a vertical synchronizing signal can be recorded in the vertical blanking section formed in the vertical blanking section.

Note that FIG. 2 shows an example of a typical recording pattern of the magnetic tape 1 viewed from the magnetic surface. C in the figure represents a control signal, E and E2 represent the first and second audio tracks, and arrows indicate F indicates the running direction of the magnetic tape 10, and arrow G indicates the scanning direction of the rotating magnetic head. Also,
In FIG. 1 and FIG. 10, which will be described later, the switching means for changing the head output and the like are omitted because known ones can be used.

Next, the operation of this embodiment will be explained. First, the first and second
The rotating magnetic heads 4a, 4b are rotated at a normal first rotational speed (
Although not shown in FIG. 1, when recording a color television signal on the magnetic tape 1 by rotating it at a speed of 1,800 rpm), a well-known method is used, which is to separate the color television signal into a luminance signal and a carrier color signal. , the former signal has the leading edge of the synchronization signal at 3.1 MHz and the white beak at 4 MHz.
．． Low carrier FM modulation is performed to achieve a frequency of 5 MHz, and
The latter signal converts the 3.58 MHz carrier wave to a lower frequency (767,0473 KHz) and mixes both signals again to be recorded on the magnetic tape 1. The video signal recording track pattern of the magnetic tape 1 in this case is as shown in FIG. 3(b).

Then, when the magnetic tape recorded in this manner is reproduced at the same first rotation speed, the result is as shown in FIG. 3).

As is clear from (C), the reproduced signal images of tracks A and B (represented by the same symbols A and B, respectively) are displayed on the video screen of the monitor television receiver 27 as shown in FIG. 3 (&). are displayed alternately.

Next, without changing the running speed of the magnetic tape 1, the first and second rotating magnetic heads 41! , ab is 3 times the normal value
When recording a color television signal by rotating at 600 rpm, that is, the second rotation speed, the selector switch 21 is turned to the R side in FIG. In this case, a control signal is given to the motor drive circuit 6, the head drive motor 6 rotates at double speed, and the color television signal input from the input terminal 12 is transmitted to the input amplifier 13.
After being amplified by FM modulator 14, it is FM modulated by output amplifier 15. Changeover switch 21. The first and second rotating magnetic heads 4a, 4b are connected via a rotary transformer.
The data is recorded on the magnetic tape 1 at the same time. That is, it is directly recorded without separating Y and C. Magnetic tape 1 in that case
The video signal recording track pattern is as shown in FIG. 4(b).

It should be noted that the width of each track A, B is % compared to the case of FIG. 3(b) in the rotating magnetic head 4a.

Since the number of rotations of the rotating magnetic head 4b has been doubled (however, the running speed of the magnetic tape remains unchanged).

This is the rounding that resulted in the override (write) by 4b.

When reproducing the magnetic tape 1 shown in FIG. 4 recorded in the above manner, the selector switch 21 in FIG. 1 is turned to the P side.

In this way, the reproduction signals from the rotating magnetic heads 4a, 4b are transferred to the rotary transformer, the changeover switch 21.
Input amplifier 16. Demodulator 171 Time base corrector 18. Output amplifier 19. The signal is supplied to a monitor television receiver 27 through an output terminal 20. On the other hand, a portion of the reproduced television signal, that is, a portion of the output of the input amplifier 16 is input to the track number detection means 22, where four video signal tracks are recorded at one control signal interval. Detect. Then, the mode switching means 23 switches the motor drive circuit 6 according to the detection output.

It is automatically controlled so that the second rotational speed (3eoorpm in this case) is obtained. The image reproduced in this way is shown in FIG. 4(a). : B is divided into upper and lower parts.

Here, when the search speed is increased by increasing the traveling speed of the magnetic tape 1 during the above reproduction, the search speed is increased because the search is performed using a rotating magnetic head having a width approximately twice the width of the video signal recording track. The higher you turn it up, the more noise bars will appear on the video screen. Especially in Figure 4 (
A, 8-screen switching portion as shown in a) generally causes noise bars to become large and skew distortion to occur. Because this seam appears in the center of the video screen, it is difficult to see and search. Figure 6(a), Φ) shows the reproduced signal waveform (a1) of one field when searched as above.
~a4. b, to b4) and a diagram schematically showing a playback screen.

For this reason, the shifter 29 in FIG. 1 is adjusted to advance or delay the rotational phase of the rotary magnetic heads 4h, ab by 90 degrees, so that the first and second heads rotate at the second rotational speed. The rotating magnetic heads 4a and ab each output one field of color television signals over one inclined track and each half of the tracks located on both sides of the track, as shown in FIG. Recording is performed sequentially so that the joint portion of each field formed every other track is located at or approximately at the center in the length direction of the track;
If the vertical synchronizing signal Sv is recorded at the joint, the playback surface will be as shown in FIG. 6(a).
One half of the picture in one field (indicated by A) is located approximately in the center of the video screen, and the other half (indicated by B and B') is divided into upper and lower parts of A. Figures 7(a) and 7(b) show the reproduced signal waveform of one field (b) when searching using a magnetic tape recorded in the pattern shown in Figure 6).
l, b2゜a 1* a 2 + a 3 , a 4
, b 3 * b 4 ) and a reproduction screen. In this way, the connected portion of the screen is shifted vertically on the video screen, making it much easier to see the image to be searched. Note that the time axis corrector 1B shown in FIG. 1 is inserted for the purpose of improving the seam between the divided screens during playback as described above and correcting the jitter component of the color signal. .

In addition, the vertically divided screen (B and B/) is actually partially covered by the escutcheon (edge frame) installed in front of the video tube of the monitor television receiver, so even if it is left as it is, it will be extremely difficult to However, if necessary, the upper and lower split screens (B and B/) may be displayed in colors such as blue or gray, or without coloring, without displaying the image on the upper and lower split screens (B and B/). It may also be displayed as . In that case, a pseudo signal generator 30 as illustrated by the dotted line in FIG.
It is sufficient to provide a color signal or an achromatic color signal therefrom and supply the color signal or achromatic color signal to the input side of the time axis corrector 18. In this way, special effect screens such as search can be easily reproduced and viewed.

Note that in the above embodiments, particularly in FIGS. 2, 3 (b), and 4 (b), the vertical synchronization signal Sv is recorded near one end of each video signal track A, B. but,
If necessary, the vertical synchronization signal Sv is applied to each video signal track A, as illustrated in Fig. 8 (03) or Fig. 9).
The information may be recorded at the center or approximately at the center in the length direction of B. In this case, the following effects can also be obtained.

In other words, when a digital signal containing one character information is inserted near the vertical synchronization signal as in the case of teletext broadcasting, if this is located at the joint near one end of each video track, the normal In consumer VTRs, problems may occur such as signal dropouts occurring during reproduction by a rotating magnetic head or digital signals not being faithfully recorded during recording.

On the other hand, in the case of video signals, not only can signals be spliced relatively easily near the horizontal synchronization signal, but even if one horizontal line is added or missing, the reproduced image will have It doesn't have much of a negative impact.

However, if the signal joins too early or late in time, a discontinuous portion will occur on the playback screen, but this can be easily corrected by the aforementioned time axis corrector 18. Note that, due to recent advances in digital technology and declines in semiconductor prices, the time base corrector 18 is now used as a component in VTRs.
It is becoming easier to load them into equipment.

From the above, it may be more suitable for the coming new media era to switch the projection screen not during the vertical synchronization period as in the past, but rather in the middle of the screen. In addition, it is expected that information necessary for image quality improvement will be inserted near the vertical synchronization signal in the future.
It is of great significance to record almost at the center (basically, the part corresponding to the stable output part of the reproduction output from the rotating magnetic head).

FIG. 10 shows a second embodiment of the present invention, in which a signal processing means 26B converts the reproduced signals of the first and second rotary magnetic heads 4a, 4b, and therefore the output signal of the input amplifier 16, into two tracks. Vertical synchronization signal detection means 31 for detecting that a vertical synchronization signal is recorded at a rate of 1 degree.
In this case as well, the mode switching means 23 operates according to the detection output and automatically switches the rotation speed drive means to the second rotation speed mode during regeneration. The operation is the same as in the previous embodiment. Since the other components are also similar to those in the embodiment shown in FIG. 1, corresponding parts are given the same reference numerals and their explanations will be omitted here.

Effects of the Invention As is clear from the above explanation, according to the magnetic recording and reproducing apparatus of the present invention, the maximum recording frequency can be doubled to approximately 14 MH2 by doubling the rotational speed of the rotating magnetic head. , 9 to 12.3, which corresponds to a broadcast VTR.
The ability to raise the FM carrier frequency to 4.2 to 5.4 MHz in the VH3 system.
), the ability to record directly on magnetic tape as an NTSC composite video signal, etc., making it possible to play back modern VTRs and many video soft tapes recorded with them, while also being able to record/play back with high image quality. It is.

Furthermore, if the vertical synchronization signal is recorded at or approximately at the center of the length of the video signal track as in the above embodiment, data signals such as character signals may be recorded in the vicinity of the vertical synchronization signal. If it is inserted, the data signal can be recorded/played faithfully without any loss, and the noise bar that occurs during playback search can be displayed separately at the top and bottom of the screen instead of in the center. As a result, various effects such as easier searching can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the main parts of an embodiment of the present invention, FIG. 2 is a diagram showing a typical example of a normal tape recording pattern, and FIG.
(a) and (b) in FIGS. 4 and 6, respectively. (0) is a schematic diagram showing the relationship between the playback screen, the tape recording pattern, and a part of the rotary head cylinder in the embodiment of the present invention, and (a) and (a) in FIGS. 6 and 7, respectively.
b) is a schematic diagram showing the playback signal waveform and playback screen of one field at the time of search, and (a) of Fig. 8 and Fig. 9, respectively.
10(C) is a schematic diagram showing the relationship between a reproduction screen, a tape recording pattern, and a part of a rotary head cylinder for detailed explanation of the present invention, and FIG. 10 is a schematic configuration of main parts of another embodiment of the present invention. It is a diagram. 1...magnetic tape, aa, 4b...rotating magnetic head, 5...head drive motor, 6...
... Motor drive circuit, 11 ... A/C head, 22 ... Track number detection means, 23 ...
...Mode switching means, 24...Synchronization separation circuit, 25...Phase comparison circuit, 26A. 26B...Signal processing means, 28...P
G detector, 29...Shifter, 30...
Pseudo signal generator, 31... Vertical synchronization signal detection means. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 6 (in)
(b) Figure 7 Figure 8 Figure 9

Claims (5)

[Claims] (1) Using the first and second rotating magnetic heads,
A magnetic recording and reproducing apparatus that records/reproduces a field worth of composite video signals on a magnetic tape on tracks inclined with respect to the running direction of the magnetic tape, the first and second rotating magnetic heads being rotated during normal recording. a rotating head driving means capable of rotating the rotating head by switching between a first rotational speed and a second rotational speed that is twice the first rotational speed; A magnetic recording/reproducing device comprising a signal processing means for recording/reproducing a composite video signal using the first and second rotating magnetic heads in a mode set to obtain a rotational speed of . Device. (2) The signal processing means includes vertical synchronization signal detection means for detecting that a vertical synchronization signal is recorded once every two tracks from the reproduced signals of the first and second rotating magnetic heads; Claim 1, characterized in that the apparatus includes mode switching means for automatically switching the rotary head driving means to a second rotational speed mode in response to the output of the vertical synchronization signal detection means. The magnetic recording and reproducing device described above. (3) The signal processing means, based on the reproduction signals and reproduction control signals of the first and second rotating magnetic heads,
track number detection means for detecting that four video signal tracks are recorded at one control signal interval; and a rotary head drive means set to a second rotation speed mode in response to the output of the track number detection means. 2. The magnetic recording and reproducing apparatus according to claim 1, further comprising mode switching means for automatically switching modes. (4) The first and second rotating magnetic heads have different azimuth angles and operate so as to sequentially and alternately record one field's worth of composite video signals on one inclined track, and Claims 1 to 3 are characterized in that a vertical synchronization signal is recorded at or approximately at the center of one of these tracks in the longitudinal direction. The magnetic recording/reproducing device according to any one of the above. (5) The first and second rotating magnetic heads are rotated at a second rotational speed with different azimuth angles, and each transmits one field of composite video signals onto one inclined track and , operates to record sequentially over each half of the tracks located on both sides of the track, and the joint portion of each field formed every other track is at or approximately the center in the length direction of the track. The magnetic recording and reproducing apparatus according to any one of claims 1 to 3, characterized in that the vertical synchronization signal is recorded at the joint portion of each field. .