JPH0779484B2 - Video signal recording / reproducing apparatus and recording / reproducing method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording / reproducing apparatus such as a video tape recorder for recording / reproducing video signals and audio signals, and a reproducing method thereof.

Conventional technology Conventional commercial and broadcast video tape recorders (VTRs)
In the field of (abbreviated as), a system has been developed in which a color video signal is decomposed into a two-channel component video signal of a luminance signal and a color signal and recorded and reproduced. For example, M
It is a VTR called format or βCAM. It is a recording method as described in Broadcast Technology Magazine, October 1982, pages 872 to 890, and is called M + format. The recording method is as described on pages 2 and 7 to 12. These two-channel component type VTRs are recorded so that a color signal track is arranged adjacent to a luminance signal track in a recording track recorded on a magnetic tape. Two dedicated magnetic heads are used, and in the end, a total of four magnetic heads are arranged on the rotating cylinder for recording and reproducing luminance signals and color signals, resulting in a complicated head arrangement. There is a problem that

Problems to be Solved by the Invention In a conventional two-channel component VTR, a total of four magnetic heads are used for recording / reproducing a luminance signal and a chrominance signal, each of which is arranged on a rotating cylinder. Generally, the position of the magnetic head on the rotating cylinder determines the recording track pattern of the signal,
The accuracy of the mounting position of the magnetic head on the rotating cylinder is in the unit of micrometer [μm]. That is, the mounting accuracy such as the positions of the plurality of magnetic heads on the circumference of the rotating cylinder and the relative heights between the magnetic heads. In the two-channel component VTR, there is a problem that mounting and adjusting a total of four magnetic heads on the rotating cylinder for recording and reproducing the luminance signal and the chrominance signal becomes very complicated. Also, since there are four magnetic heads, a rotary transformer (RT) requires four channels and a regenerative amplifier also requires four channels, which makes the structure of the mechanical system and circuit system around the electromagnetic conversion system of the VTR very complicated. There is a problem. Further, in the conventional two-channel component VTR, there is a problem that a guard band exists in the recording track pattern and the recording density is low.

In view of the above problems, the present invention has a very simple structure in terms of mechanism and circuit, that is, two magnetic heads for recording and reproducing a luminance signal and a chrominance signal, and is a two-channel component with no guard band and high recording density. It provides a VTR.

Means for Solving the Problems In order to solve the above problems, in the present invention, two channels of memory for storing video signals in a period longer than the vertical synchronizing period of the video signals are prepared, and one rotation time of the rotary cylinder is provided. Is set to be equal to the vertical synchronization period and the time axis compressed luminance signal and chrominance signal are switched in one track to perform recording and reproduction by two magnetic heads having different azimuths.

Action The present invention has the above-described configuration, which is a two-channel component VTR, but has two magnetic heads for recording and reproducing a video signal, and the configuration around the rotary cylinder that requires precision is mechanically and circuitically. It is also possible to realize high-density recording without guard band while realizing extremely easily.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an essential part of an embodiment of the present invention, in which 1 is a recording circuit system, 2 is an electromagnetic conversion system, 3 is a reproducing circuit system, and 4 is a memory control system.

In FIG. 1, a luminance signal as shown in FIG. 2 (a) is inputted to the input terminal 5, and a time axis compressed color signal as shown in FIG. 2 (b) is inputted to the input terminal 6. To be done. The luminance signal (a) and the color signal (b) are shown in units of the vertical synchronization period in FIGS. 2 (c) and (d), respectively. The luminance signal input from the input terminal 5 reaches the sync signal separation circuit 43 via the first memory 7 and SW1 in the memory control system 4. S
W1 is a switch whose input / output path is selected by a recording (R) / reproduction (P) mode selection signal. Also, the input terminal 6
The time-axis-compressed color signal input from the second memory 8
Leading to. The vertical sync signal (Vsync) and the horizontal sync signal (Hsync) detected by the sync signal separation circuit 43 are respectively
Up to a master clock (MCK) generator 44 and a microprocessor 45. The MCK generator 44 produces a 27 MHz master clock and outputs it to the microprocessor 45. Microprocessor 45 is timing generated from Vsync, Hsync, MCK, CLK1, R / W1, CLK2, R / W2
To read / write the first memory 7 and the second memory 8.
Write, that is, output timing is controlled.

Here, the operation of the first memory 7 will be described with reference to FIG. An A / D converter 40 is provided at the input section of the first memory, and an 8-bit digital signal a having a basic clock frequency of 13.5 MHz a
It is converted into 1, a2, ..., A8 and input to the random access memory 41. The random access memory 41 stores and holds it for a time designated and managed by the microprocessor 45. That is, the output timing is controlled by the offset of the read / write address to the memory output from the I / O interface 46. After that,
The 8-bit digital signals b1, b2, ..., B8 of 27 MHz whose basic clock frequency is twice that of 13.5 MHz are time-doubled and output to the D / A converter 42. D / A converter 4
The input of 2 is again converted into an analog signal and output to the FM modulator 9 of FIG. The second memory 8 in FIG.
The operation of each is similar to the operation of the first memory 7.

The relationship of signal input / output timing will be described with reference to FIG. In FIG. 4, (4-1) and (4-2) are a luminance signal and a color signal input to the first memory 7 and the second memory 8, respectively. (4-3) is Vsync. (4-
4) is the output of the first memory 7, and (4-5) is the output of the second memory 8. (4-6) is a signal obtained by combining (4-4) and (4-5), which are compressed twice in the time domain. The combined signal (4-6) is input to the input terminal 11 of the electromagnetic conversion system 2 shown in FIG.

The configuration of the electromagnetic conversion system 2 will be described with reference to FIG.
The signal (4-6) input from the input terminal 11 is input to the R / P mode selection circuit 12. In the recording mode, the switch in the R / P mode selection circuit 12 is switched to the R side, and the signal (4-6) is transmitted through the rotary transformers 13 and 14 to the two magnetic heads D1 and D2 on the rotary cylinder 15.
Leading to. Here, the azimuth angles of the gap portions of the two magnetic heads D1 and D2 have an inverse azimuth relationship with each other. The rotating cylinder 15 makes one rotation in the direction 25 in the Vsnc period (about 1/60 second in the NTSC signal). Also, the magnetic tape 16 is 2
Rotating cylinder 15 held by two fixed posts 23 and 24
It is wound around the circumference of about 180 degrees and is sandwiched between the capstan 7 and the pinch roller 19. The capstan 7 is rotated by the rotation of the capstan motor 18, and drives the magnetic tape 16 in the direction of arrow 20. From the above, it can be seen that in this configuration, the signal recording track is helically formed on the magnetic tape. The moving speed of the magnetic tape 16 changes the recording track width according to a command from the capstan motor drive circuit 21 designated by the operation mode selection switch 22. FIG. 6 (a) is a view of the rotary cylinder as seen from above, and FIG. 6 (b) is a view showing the relative relationship between the magnetic heads D1 and D2. The relative heights of the magnetic heads D1 and D2 are set to be equal.

FIG. 7 shows a first example of a recording pattern on a magnetic tape, in which a luminance signal is recorded in the track group TD1 and a color signal is recorded in the track group TD2. Track groups TD1 and TD2 are
They are recorded by the magnetic heads D1 and D2, respectively. In FIG. 7, the magnetic heads D1 and D2 are indicated by arrows 25.
Scan in the direction. Further, the magnetic tape moves the length 26 during the period in which the rotary cylinder 15 makes one revolution. The length 27 is the guard band width, and the length 28 is the recording track width (in this case, equal to the track width of the magnetic head). Also,
The period 29 is the horizontal synchronization period 1H. In the case of FIG. 7, since there is a guard band, there is a problem that the recording density is low. However, there is an advantage that the structure of an electromagnetic conversion system such as a magnetic head or a rotary transformer is simplified.

FIG. 8 shows a second example of the recording pattern on the magnetic tape. The luminance signal is recorded in the track group TD1 and the color signal is recorded in the track group TD2 so that the first memory and the first memory in FIG. Two
The output signal address and timing of the memory 8 are controlled. Further, the magnetic tape moves by two tracks in a period in which the rotary cylinder 15 makes one rotation. Tape recording efficiency is increased due to guard bandless recording. Moreover, since the signal arrangement in H units is aligned, the crosstalk interference of the sync signal of the adjacent track having particularly large interference energy does not deteriorate the image quality other than the sync signal. That is, the density is higher than that in the case of FIG. 7, and the recording time can be extended.

FIG. 9 is a third example of the recording pattern on the magnetic tape. The track groups TD1 and TD2 are recorded in the form of the first memory and the first memory of FIG. The output signal address and timing of the second memory 8 are controlled. An example of this timing control
Shown in Figure 10. Further, the magnetic tape moves by two tracks in a period in which the rotary cylinder 15 makes one rotation. In this case as well, the tape recording efficiency is increased due to the guard bandless recording. Moreover, not only is the signal sequence in H units aligned, but since signals on adjacent tracks have a high correlation because they are close to each other on the screen, crossing due to the synchronization signal and video signal on adjacent tracks is performed. It is possible to reduce the adverse effect of talk interference on the self-track signal.
That is, since a crosstalk component appears in the vicinity of the FM-modulated video signal carrier frequency of the self-track, the crosstalk component of the adjacent track can be reduced by the principle of the frequency characteristic of the triangular noise in FM demodulation. Therefore, it is possible to further improve the image quality as compared with the case of FIG.

Now, at the time of reproduction, referring to FIG. 5, the signals reproduced by the magnetic heads D1 and D2 are input to the R / P mode selection circuit 12 through the rotary transformers 13 and 14. In the reproduction mode, the switch in the R / P mode selection circuit 12 is switched to the P side, and the reproduction signal is input to the head switching circuit 30. The switch in the head switching circuit 30 switches the switching to a and b by the D head switch signal so that the reproduction envelope signal from the magnetic tape is continuous. Then, a continuous envelope signal is input from the output terminal 31 of FIG. 5 (FIG. 1) to the FM demodulation disconnection 33 through the input terminal 32 of the reproducing circuit system 3. FM demodulator 33
The demodulation signal of FIG. 2 (4-6) is shown in FIG. 2, and in the case of FIGS. 7 and 8, the signal (4- (4) of FIG. 4 is stored in the third memory 34).
7), the signal (4-8) of FIG. 4 is input to the fourth memory 35. The operations of the third memory 34 and the fourth memory 35 are opposite to those of the first memory 7 and the second memory 8, and the signals (4-9) and (4-10) are output from the reproduction circuit system 3, respectively. Output from terminals 36 and 37.

In the above description, the luminance signal and the time axis compression multiplexed color signal are used as the video signal divided into two channels, but the same applies to the case where the luminance signal and the two color difference signals are frequency multiplexed signals. The effect of is obtained. That is, the present invention can be applied to a recording device for video and audio signals that handles an input signal that can be converted into a two-channel signal. That is, the input signal may be a luminance signal and two types of color signals, or may be R, G and B signals. Further, a 1-channel signal in which a luminance signal and a line-sequential color signal are time-axis compression multiplexed like a MAC signal may be used. Further, the signals may be FM-modulated signals of various types of the above-mentioned signals, or the present invention can be applied when the signals added with the digitally-modulated signals are finally divided into two channels. Further, in the embodiment, the time base compression ratios of the signals output from the first memory and the second memory are doubled and the output time widths are made equal, but similar effects can be obtained by changing these values.

EFFECT OF THE INVENTION Conventionally, in a two-channel component type VTR, four magnetic heads are required to record and reproduce a video signal, and the structure of the electromagnetic conversion system is complicated both mechanically and circuitally. is there. However, the present invention has the great advantage that the above-mentioned four magnetic heads are simplified to two and the structure of the electromagnetic conversion system is greatly simplified. Further, although the accuracy of attaching the magnetic head to the rotating cylinder is performed at the level of micron meter, the number of magnetic heads is halved, which brings about an advantage that the work of attachment adjustment and maintenance is greatly simplified.

Further, since there is no guard band in the track pattern, the recording density is increased and the magnetic tape can be effectively used, which is a great advantage.

[Brief description of drawings]

1 is a block diagram of essential parts in an embodiment of the present invention, FIG. 2 is a signal waveform diagram in FIG. 1, FIG. 3 is a block diagram of a first memory in FIG. 1, and FIG. FIG. 5 is a signal waveform diagram in the figure, FIG. 5 is a configuration diagram of the electromagnetic conversion system 2 of FIG. 1, and FIG. 6 is an explanatory diagram of a relative relationship between the rotary cylinder, the magnetic head and the tape of the electromagnetic conversion system 2 of FIG. FIG. 7 is a signal recording pattern diagram on the first magnetic tape in one embodiment of the present invention, FIG. 8 is a signal recording pattern diagram on the second magnetic tape in one embodiment of the present invention, and FIG. A signal recording pattern diagram on a third magnetic tape in one embodiment of the present invention,
FIG. 10 is an explanatory diagram of the signal recording timing for realizing the signal recording pattern of FIG. 1 ... Recording circuit system, 2 ... Reproducing circuit system, 3 ... Electromagnetic conversion system, 4 ... Memory control system, 7 ... First memory, 8 ... Second memory, 9 ... FM modulator, 33 …… FM demodulator, 34 …… Third memory, 35 …… Fourth memory, 43 …… Synchronous signal separation circuit, 44 …… Master clock generator, 45 …… Microprocessor, 46 …… I / O interface

Claims (3)

[Claims] 1. A magnetic recording / reproducing apparatus for recording / reproducing each of component video signals divided into two channels onto a magnetic tape and reproducing the component video signals divided into two channels into first and second components, respectively. A unit for storing in a memory; a unit for time-axis-compressing the component video signal divided into the two channels stored in the first and second memories into a one-channel video signal for each vertical synchronization period; Is wound about 180 degrees on the circumference, and is rotated once every vertical synchronization period, and is arranged about 180 degrees on the circumference of the rotation cylinder and is time-axis compressed. First and second magnetic heads for recording or reproducing the 1-channel video signal, and recordings by the first and second magnetic heads. Control means for controlling the output timing of the 1-channel video signal output from the means for compressing the time axis so that the luminance signal, the chrominance signal and the horizontal synchronizing signal in two adjacent signal tracks are adjacent to each other; Means for storing the 1-channel video signal reproduced by the first and second magnetic heads in third and fourth memories, and the 1-channel video signal stored in the third and fourth memories. A video signal recording / reproducing apparatus comprising: means for expanding the video signal divided into the two channels on a time axis. 2. A means for time-axis compressing a 2-channel video signal stored in the first and second memories into a 1-channel video signal, switching a luminance signal and a chrominance signal every horizontal synchronization period. The magnetic recording / reproducing apparatus according to claim 1, wherein the one-channel video signal is produced. 3. A magnetic recording / reproducing method for recording and reproducing each of component video signals divided into two channels on a magnetic tape, and storing the component video signals divided into two channels, respectively. A step of time-axis-compressing the component video signal stored in the storage step into a video signal of one channel for each vertical synchronization period;
First and second magnetic recordings, which are wound around 0 degree and are arranged about 180 degrees apart on the circumference of a rotating cylinder that makes one rotation for each vertical synchronization period, to record or reproduce the one-channel video signal. A playback step,
The time-axis compression of the 1-channel video signal so that the luminance signal, the chrominance signal, and the horizontal synchronizing signal in two signal tracks adjacent to each other recorded by the first and second magnetic recording / reproducing steps are adjacent to each other. A control step of controlling the output timing from the means for storing, a second storing step of storing the one-channel video signal reproduced by the first and second magnetic recording / reproducing steps, and a second storing step. And a step of time-expanding the stored first channel video signal into the video signals divided into the two channels.