JPS6149875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The following methods have been developed as methods for recording video signals.

That is, as shown in FIG. 1, rotating magnetic heads 1A and 1B are provided with an angular spacing of 180 degrees from each other, and are rotated at a speed of 30 times per second, and the magnetic tape 2 is rotated 180 degrees along the tape guide drum 3. Run diagonally over an angular range of a little over 100°. in this case,
As shown in FIG. 2, the working gaps 4A and 4B of the heads 1A and 1B have different width directions, that is, different azimuth angles. The luminance signal is then converted into an FM signal that occupies the high frequency side of the recordable band, and this FM signal is supplied to the heads 1A and 1B.

Therefore, according to this recording method, one field of the luminance signal is recorded as one magnetic track 5 on the tape 2, as shown in FIG. Since the tracks 5A and 5B are recorded obliquely and the azimuth angles are different between the heads 1A and 1B, the azimuth angles are correspondingly different between the tracks 5A and 5B.

Then, write this recording pattern to head 1.
Consider the case where playback is performed on A and 1B. Then, from tracks 5A and 5B by heads 1A and 1B,
The FM signal is played, but in this case, head 1A
The azimuth angle is different between head 1B and track 5B, and the azimuth angle is different between head 1B and track 5A, and the FM signal is recorded on the high frequency side, so FM signals can be transmitted without causing crosstalk between tracks due to azimuth loss. Can reproduce signals well.

In this way, there is no inter-track crosstalk in the reproduced FM signal, so
During recording, as shown in FIG. 3, the FM signal can be recorded so that there is no guard band between adjacent tracks 5A and 5B, or so that adjacent tracks 5A and 5B partially overlap. The amount of recording can be significantly increased.

In this case, by narrowing the width of the track 5, it should be possible to further increase the recording amount in inverse proportion to the track width.

However, the azimuth loss is
As the track width becomes narrower, it becomes smaller, so if you try to further increase the recording amount by narrowing the width of track 5 without a guard band between tracks 5A and 5B, you can expect a reduction in crosstalk between tracks due to azimuth loss. It disappears.

Furthermore, if adjacent tracks 5A and 5B are recorded so that they partially overlap, the width of track 5 will be narrower than the width of heads 1A and 1B during playback, so when heads 1A and 1B scan the original track 5 during playback, At the same time, a part of the adjacent track 5 is also scanned, making it even harder to expect crosstalk between tracks to be reduced.

In this way, when crosstalk between tracks can no longer be ignored, during playback, the output signal from the FM demodulation circuit contains the original luminance signal as well as the original luminance signal.
An interference signal (beat signal) with a frequency difference between the FM signal and the FM signal due to crosstalk is included. The level of this interference signal is proportional to its frequency.

In this case, as shown in Figure 4 ([1]~
The number [525] indicates the line number), track 5
When the so-called H arrangement (horizontal synchronization arrangement) is performed so that the horizontal synchronization pulse Ph of , the frequencies are approximately equal, so the frequency and level of the interfering signal are low. Therefore, when H arrangement is performed, even if interference signals are generated due to crosstalk, deterioration of the reproduced screen is not a practical problem.

However, when recording and reproducing for a standard time, for example 1 hour, by running the tape 2 at the standard speed, if the H arrangement is performed as shown in Fig. 4, then the tape 2 is, for example 1/2 Driving at low speed for a long time,
That is, when recording and reproducing for two hours, the pitch of the track 5 becomes smaller in the longitudinal direction of the tape 2 as shown in FIG. 5 from the state shown in FIG. 4, so that H-alignment is no longer possible. Therefore, in this case, the original FM signal at a certain point in time and the FM signal due to crosstalk differ greatly in frequency, and the frequency and level of the interference signal become high. As described above, when the frequency and level of the interfering signal become high, the interfering signal appears as beat stripes on the playback screen, significantly reducing the playback image quality.

In view of the above-mentioned points, the present invention attempts to enable H-alignment of the tracks 5 even when recording is performed by changing the running speed of the tape 2.

For this reason, in the present invention, during recording, the heads 1A and 1B are rotated at the frame frequency, and the heads 1A and 1B are deviated by a predetermined amount in the length direction for each track 5 to perform H arrangement. This is what I did.

An example of this will be explained below. In the example below, when the H alignment correction is not performed, as shown in FIG. ).

In FIG. 6, the luminance signal is supplied from the input terminal 11 to the modulation circuit 16 through the signal path of terminal 11 → AGC amplifier 12 → clamp circuit 13 → pre-emphasis circuit 14 → white dark clip circuit 15 → FM modulation circuit 16. , for example, the white peak is 4.5MHz, and the sync chip is 4.5MHz.
It is converted to FM signal Sf of 3.85MHz. This FM signal Sf is then supplied to the heads 1A and 1B through the recording amplifier 17.

The heads 1A, 1B and tape 2 are constructed as explained in FIGS. 1-3. That is, a motor 21 is provided, a pulley 23 is provided on its rotating shaft 22, and a pulley 24 is also provided on the shaft 8 of the capstan 6, and a belt 25 is passed between these pulleys 23 and 24 to move the capstan 6 to a predetermined position. rotated at a speed of The tape 2 is caused to run at a predetermined speed by the capstan 6 and the pinch roller 7.

Further, another pulley 26 is provided on the rotating shaft 22, and a pulley 27 is provided on the rotating shaft 9 of the heads 1A, 1B. It can be rotated at a rather fast speed.

The rotation of the heads 1A and 1B is synchronized with the luminance signal by the servo circuit 30. That is, for example, the pulse generating means 31 is provided on the rotating shaft 9 of the heads 1A, 1B.
One pulse is taken out every 1/2 rotation of , and this pulse is supplied to the sawtooth signal forming circuit 33 through the shaping amplifier 32, and as shown in FIG. 7A, the pulse from the generating means 31 is A sawtooth wave signal Sa with a field period synchronized with is formed, and this signal Sa is sent to the sampling hold circuit 3.
4 as its input signal.

Further, the luminance signal from the amplifier 12 is supplied to a sync separation circuit 35 to extract a vertical sync pulse, and this pulse is supplied to a shaping circuit 36 to
As shown in Figure B, the pulse Pb is narrow,
This pulse Pb is supplied as a control signal to the sampling hold circuit 34 through a delay circuit 37, which will be described later.

In this way, in the sampling and holding circuit 34, the signal Sa is sampled and held by the pulse Pb, and as shown in FIG. Using the pulse Pb as a reference, a DC voltage Ec whose level increases as the phase of the signal Sa becomes faster is extracted.

An electromagnetic brake 38 is provided on the rotating shaft 9 of the heads 1A, 1B, and a voltage Ec from the sampling hold circuit 34 is applied to the brake 3 through an amplifier 39 and a switch circuit 41.
8.

Therefore, when the rotation of heads 1A and 1B becomes faster,
The phase of the signal Sa becomes faster, the level of the voltage Ec rises, and the brake 38 is applied, so the head 1A,
1B rotates in synchronization with the luminance signal. Therefore, one field of the FM signal from the amplifier 17 is 1
It is recorded on the tape 2 as a diagonal magnetic track 5 of the book.

In this case, in order to perform the H arrangement of the tracks 5, the following configuration is further provided. That is,
A delay circuit 37 is provided, which is a variable delay circuit, and pulses from the amplifier 32 are supplied to a control signal forming circuit 42 to form a control signal, and this control signal is sent to the delay circuit 37 to determine the delay time. The delay time τ _d of the delay circuit 37 is supplied as a control signal, and the delay time τ d of the delay circuit 37 is 0.25 per field period, with four field periods as one period, as shown in FIG. 7D.
It is lengthened by τ _h (τ _h is one horizontal period).

Further, the DC voltage from the DC power source 44 is supplied to the switch circuit 41, and the pulse from the amplifier 32 is supplied to the control signal forming circuit 45, so that immediately before the pulse Pb, as shown in FIG. A pulse Pf is formed which is located at the same time and is rising only for, for example, 1 ms, and this pulse Pf is supplied as its control signal to the switch circuit 41, and the switch circuit 41 is connected to the switch circuit 41 when the pulse Pf is falling. Sometimes it is switched to the amplifier 39 side, and when it is starting up, it is switched to the power supply 44 side.

Further, a vertical synchronizing pulse from the separation circuit 35 is supplied to the magnetic head 48 through a recording amplifier 47, and is used as a control pulse during playback on the tape 2.
recorded on the edge of the

On the tape 2 recorded in the above manner, the track pattern is as shown in FIG. 8, and H-alignment is performed.

That is, the pulse Pb from the delay circuit 37 is
As shown in FIG. 7B, if the phase is constant, the rotational phase of the heads 1A and 1B will be constant with respect to the original luminance signal, so this is the same as in the conventional case.
As shown in FIG. 5 and as shown by the broken line in FIG. 8, the track 5 is shifted by 0.75H.

However, in the present invention, since the delay time τ _d of the delay circuit 37 changes as shown in FIG. During the field period _T1 , the pulse P1, shown as pulse _P1 in FIG. 7E, is in phase with the original pulse Pb (FIG. 7B), and during the second field period _T2 , the pulse P ₂ , it is delayed by 0.25τ _h with respect to the original pulse (shown by broken lines in FIGS. 7B and 7E). Additionally, the third and fourth field periods
At T ₃ and T ₄ , the pulse Pb is 0.5τ _h with respect to the original pulse Pb, as shown as pulses P ₃ and P ₄ .
and 0.75τ _h respectively. and this pulse
The rotational phases of heads 1A and 1B are servo-controlled with Pb (P ₁ to _{P 4} ) as a reference.

Therefore, if a track 51 is formed in the first field period _T1 , this track 51
is formed based on the pulse _P1 which is in phase with the original pulse Pb, so as shown in FIG.
It is formed at the same position as shown (track 5 in FIG. 5 is indicated by a broken line in FIG. 8).

Then, in the second field period _T2 , a track 52 is formed based on the pulse _P2 delayed by 0.25τ _h from the original pulse Pb, so this track 52 is moved from the position shown in FIG. Head 1A, 1
It is formed with a deviation of 0.25H in the scanning direction of B. Therefore, the horizontal sync pulse of track 52
The position of Ph is the horizontal synchronizing pulse Ph of track 51.
It will be located next to.

Also, in the third field period _T3 , a track 53 is formed based on the pulse _P3 delayed by _0.5τh from the original pulse Pb, so this track 53 is moved from the position shown in FIG. The heads 1A and 1B are formed offset by 0.5H in the scanning direction. Therefore, the horizontal synchronization pulse Ph of track 53
will be located next to the horizontal synchronization pulse Ph of track 52.

Furthermore, in the fourth field period _T4 , a track 54 is formed based on the pulse _P4 delayed by 0.75τ _h from the original pulse Pb, so this track 54 is moved from the position shown in FIG. The horizontal synchronizing pulse Ph of track 54 is therefore located adjacent to the horizontal synchronizing pulse Ph of track 53.

Since these four field periods T ₁ to _{T 4} are taken as one cycle, the horizontal synchronizing pulses Ph in tracks 51 to 54 are aligned on the same line orthogonal to track 5, that is, the H alignment in track 5 is You will be killed.

In this case, the rotation of heads 1A and 1B is as follows:
Due to inertia and pulse Pb, head 1A, 1
Since it may be difficult to rapidly delay the rotation phase of head B for each track 5 as described above, voltage is supplied from the power supply 44 to the brake 38 by the pulse Pf, and the brake is applied to the rotation of the heads 1A and 1B. is applied, and then head 1 is set based on the pulse Pb.
This is done smoothly when the rotational phase of A, 1B is delayed.

According to the present invention, since the tracks 5 are arranged in H order, even if crosstalk occurs between tracks, it is not affected much and a good reproduction screen can be obtained.

The reproduction system may be the same as before, but
If necessary, processing may be performed in the same manner as when recording.

In the above description, the rotational phase of the heads 1A and 1B is controlled to deviate the heads 1A and 1B in the length direction of the track 5 to perform H arrangement.
It is also possible to perform H arrangement by shifting the heads 1A, 1B in the length direction of the track 5 while keeping the rotational phase of the heads 1A, 1B constant.

FIG. 9 shows an example. That is, in the servo circuit 30, the pulse Pb is supplied to the sampling and hold circuit 37 while its phase remains constant, so that the heads 1A and 1B are rotated in synchronization with the luminance signal.

Further, the heads 1A and 1B include electromechanical transducer elements,
For example, it is attached to the drum 3 through a bimorph plate. That is, as shown in FIGS. 10 and 11, one end of the bimorph plate 61 is connected to the support body 62.
For example, the head 1 is fixed to the head 1 with an adhesive, and the other end is fixed with an adhesive through a support piece 63.
A and 1B are attached, and the support 62 is attached to the drum 3.
For example, it is screwed to the In this case, the direction of polarization of the bimorph plate 61 is set to be the longitudinal direction of the track 5. Therefore, when a voltage is supplied to the bimorph plate 61, the heads 1A and 1B are polarized along the track 5.
is made to deviate in the length direction. Also, 64
is the damper material.

Then, the vertical synchronization pulse from the separation circuit 35 is
The voltage Ed is supplied to the control signal forming circuit 71, and as shown in FIG. It is supplied to the plate 61.

Therefore, if the track 51 is formed in _the field period _T1 as shown in FIG.
Since voltage Ed of E is supplied, heads 1A, 1
B is offset in the length direction of track 5, so if level ΔE is selected in advance, track 5
2 is formed shifted by 0.25H in the scanning direction of the heads 1A and 1B as shown in FIG. 8 from the position shown in FIG.

Similarly, during field periods _T3 and _T4 , heads 1A and 1B are displaced in the length direction of track 5 in response to voltage Ed levels 2ΔE and 3ΔE, so that the track 53 and 5
4 is 0.5H and 0.75H from the position in Figure 5, respectively.
Therefore, the tracks 51 to 54
H sorting is performed.

In the above description, when the rotation direction of the heads 1A, 1B and the running direction of the tape 2 are opposite to each other, the order of the pulses _P1 to _P4 and the order of level changes of the voltage Ed may be reversed. Furthermore, even if the track 5 is shifted by another distance, the H arrangement can be performed in the same manner.

[Brief explanation of the drawing]

Figures 1 to 5, Figures 7 and 8 are diagrams for explaining the present invention, Figure 6 is a system diagram of one example of the present invention, and Figure 9 is a system diagram of another example of the present invention. , FIG. 10 and FIG. 11 are a plan view and a side view of a part thereof, and FIG. 12 is a diagram for explaining the same. 11 is an input terminal, and 30 is a servo circuit.

Claims (1)

[Claims] 1. Convert the luminance signal into an FM signal, supply this FM signal to a rotating magnetic head having an angular interval of 180 degrees from each other, and apply one diagonal line in each predetermined section onto a magnetic tape running at a first speed. In the magnetic recording apparatus, the magnetic tape is recorded at a second speed different from the first speed. When recording by running at a high speed, the rotating magnetic head is moved by the magnetic field by an amount corresponding to the positional deviation in the length direction of the magnetic tracks between the horizontal synchronizing pulses between adjacent magnetic tracks. A magnetic recording device in which the horizontal synchronizing pulses are offset in the length direction of the track so that the horizontal synchronizing pulses are aligned on a line perpendicular to the magnetic track.