JPH03230304A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To suppress the generation of edge noise and to improve the interchangeability of tapes by delaying a recording signal correspondingly to the shear value of a magnetic head, and at the time of reproducing, delaying a reproduced signal obtained from a track which is not delayed at the time of recording only by the same quantity. CONSTITUTION:The delay variables of delay circuits 50, 60 for delaying recording and reproducing signals are switched by the tap of a delay element 51 synchronously with a head switching signal synchronized with the rotation of a rotary drum. It is necessary to reduce the interval of delay variables based upon the taps of the delay elements 51 less than a prescribed value in order to suppress edge noise less than a detection limit and a recording signal to be inputted to the magnetic head is delayed by the delay circuit 50 so that the recording signal can be prevented from being sheared from a tape pattern. At the time of reproducing a signal, the signal is corrected so as to have positional relation with a signal obtained by delaying a reproduced signal from a track in which a signal not delayed at the time of recording is recorded by the same quantity of the recorded signal. Consequently, the generation of edge noise can be suppressed and the interchangeability of tapes can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a video tape recorder (hereinafter referred to as rVTRJ).
The present invention relates to a device for reducing edge noise in a helical scanning magnetic recording/reproducing device such as a helical scanning magnetic recording/reproducing device.

[Conventional technology]

FIG. 15 is a block circuit diagram showing the configuration of a conventional magnetic recording/reproducing apparatus shown in, for example, "rNHK Home Video Technology".

In the figure, (la) and (lb) are magnetic heads,
(2) is magnetic tape, (3) is rotating drum, (4)
is a rotary transformer, (10) is a recording signal processing circuit,
(20) is a reproduction signal processing circuit, and a recording signal processing circuit (1
0) is a Y/C separation circuit (11) that separates a human-powered video signal into a luminance signal and a color signal, and a Y/C separation circuit (11).
) The recording system baseband processing circuit (12) performs processing such as applying emphasis to the luminance signal separated by
), an FM modulator (13) that performs FM modulation on the signal processed by this recording system baseband processing circuit (12), and a recording equalizer that gives frequency characteristics to the signal FM modulated by this FM modulator (13). (14), a recording system color signal processing circuit (15) that performs low frequency conversion etc. on the color signal separated by the Y/C separation circuit (11), a recording equalizer (14), and a recording system color signal processing circuit (15). Circuit (15
) and a recording amplifier (16) that synthesizes signals from the magnetic head (1) and outputs the synthesized signals to the magnetic head (1) via a rotary transformer (4).

The reproduction signal processing circuit (20) also includes a magnetic head (1a).
); a regenerative amplifier (21a) that amplifies the reproduced signal from the
Amplify the reproduced signal from the magnetic head (lb).

regenerative amplifier (21b), regenerative amplifier (21a),
A switch (22) that switches the output of (21b) in synchronization with the rotation of the rotating drum (3), a filter (23) that extracts an FM modulated luminance signal from the output signal of the switch (22), and a filter (23) that extracts an FM-modulated luminance signal from the output signal of the switch (22); A reproducing RF signal processing circuit (24) performs processing such as amplitude restriction on the signal extracted by the reproducing RF signal processing circuit (23);
4); an FM demodulator (25) for FM demodulating the output of 4); and a reproduction baseband signal processing circuit (26) for processing the luminance signal FM demodulated by the FM demodulator (25).
A filter (27) extracts a low-frequency converted color signal from the output signal of the switch (22);
), which restores the low frequency converted color signal extracted by Amplifier (29) that combines and amplifies signals
).

Figure 16 shows a magnetic head (la) attached to a magnetic tape (2).
, (lb), showing the azimuth of the magnetic head (1a) and the magnetic head (1b).
The azimuth is opposite to that of the magnetic head, and if the magnetic head protrudes into an adjacent track, crosstalk is suppressed due to azimuth loss. Figure 16 shows the magnetic head (la) and (lb) based on the track pitch on the tape pattern.
This shows the case where the track width is wider, and crosstalk from adjacent tracks always occurs.

Figure 17 shows that under the conditions of relative velocity Vr 5.8 m/sec, track pitch 7919 μm 1 azimuth ±6°,
FIG. 4 is a crosstalk characteristic diagram using the amount of protrusion to adjacent tracks as a parameter.

Figure 18 shows the magnetic head (la) on the rotating drum (3).
, (lb) is a diagram showing the installation condition, and the magnetic head (
The angle on the rotating drum (Ia) and the magnetic head (lb) is adjusted as close to 180° as possible.

(Hereinafter, this adjustment will be referred to as "180° indexing.") However, since it is mechanically adjusted, it will not be possible to completely 180'
For example, an error of about 0.01° θ
occurs. Increasing the adjustment accuracy beyond this level requires a very long adjustment time, which is not practical.

Figure 19 is a diagram showing the timing of the signal recorded on the tape pattern when ideal 180° indexing is performed and the error θ is 0. The right half is an FM-modulated image signal of white color.

Moreover, FIG. 20 is a diagram showing the timing of the signal recorded on the tape pattern when 180° indexing is not performed ideally and there is an error θ, and FIG.
) and FIG. 20(a) respectively show the magnetic head (1a).
19(b) and 20
Figure (b) shows the signals recorded by the magnetic head (1b), and H in the figure indicates one horizontal scanning period and a second horizontal scanning period.
D in FIG. 0 is a deviation on the tape pattern caused by the 180° indexing error θ.

FIG. 21 is a diagram showing the horizontal synchronizing signal portion of the tape pattern on the magnetic tape. FIG. )
is the case where there is a deviation scale.

When the track width of the magnetic heads (1a) and (1b) is wider than the track pitch on the magnetic tape (2), the 17th
Leher crosstalk as shown in the figure occurs. FM
When such losstalk is mixed into the modulated wave, it affects the signal after demodulation, and the demodulated signal becomes as shown in the following equation.

In addition, ω. is the frequency of the FM modulated wave, A is the amplitude of the FM modulated wave, B is the amplitude of the crosstalk signal, and Δω is the frequency difference between the FM modulated wave and the crosstalk signal. From equation (1), it can be seen that the influence of crosstalk is proportional to the frequency of the crosstalk, and also proportional to the frequency difference between the main signal (FM modulated wave) and the crosstalk.

Furthermore, if there is a deviation as shown in Figure 20(b), the frequency difference between the main signal and the crosstalk becomes large at the edge part where the screen changes from black to white. As shown in the figure, noise occurs at the edge portion of the demodulated signal waveform.

(Invention or Problem to be Solved) Here, suppose that the edge noise cannot be detected if the length of the part where it occurs is within the time limit of one line of resolution, and the relative speed between the magnetic head and the magnetic tape is V to 5.
8m/sec, effective display period T within one scanning line is 60μs
ec, and assuming that the number n of lines at the limit resolution is 400 lines, in order to reduce the edge noise below the detection limit, the amount of deviation is XT D= =0. It needs to be smaller than 87 μm. In order to reduce this deviation to 0°87μm or less, if the drum diameter is 62mm, the accuracy of 180° indexing must be less than 0.0016°, and this level of indexing accuracy must be achieved on the production line. This was difficult to achieve, and also contributed to the decline in tape compatibility.

The inventions as claimed in claims 1 and 2 have been made to solve the above-mentioned problems, and provide a magnetic recording and reproducing device that can suppress the generation of edge noise and has higher tape interoperability. The purpose is to obtain.

[Means to solve the problem]

The magnetic recording/reproducing device according to the invention of claims 1 and 2 delays the signal recorded by the magnetic head by an amount corresponding to the amount of deviation from the normal position of the magnetic head attached to the rotating drum. A recording signal delay means is provided to prevent tracks on the magnetic tape from being misaligned, and during playback, the playback signals from the tracks that were not delayed during recording are delayed by the same amount, so that the playback signals from each track are the same as the original. The present invention is characterized in that the number of reproduced signal delay means is reduced so that the positional relationship is as follows.

(Function) In the first and second aspects of the invention, the recording signal delaying means delays the signal recorded by the magnetic head having the amount of deviation so that the amount of deviation of the track recorded on the magnetic tape is minimized.

Further, the reproduced signal delay means delays the reproduced signals from the tracks in which undelayed signals are recorded by the same amount, and corrects the signals reproduced from each track so that they have the original positional relationship.

(Embodiment of the Invention) Hereinafter, an embodiment of the invention of claim 1 will be described with reference to the drawings.

FIG. 1 is a block circuit diagram showing the configuration of this embodiment, and the same parts as in FIG.
Explain the different parts. In the figure, (50) is a delay circuit that delays the recording signal, and the amount of delay is switched in synchronization with a head switching signal synchronized with the rotating drum (4).

Reference numeral (60) is a delay circuit that delays the reproduced signal, and like the delay circuit (50), the amount of delay is switched in synchronization with a head switching signal synchronized with the rotating drum (4).

FIG. 2 is a block circuit diagram of an example configuration of delay circuits (50) and (60). In the figure, (51) is a delay element, which is composed of, for example, a combination of a CCD, a BBD, an A/D converter, a digital memory, and a D/A converter, and the amount of delay is switched by a tap.

(52) is the first one that selects one tap of the delay element (51).
The switch (53) controls the signal C (shown in FIG. 3(c)) that passes through the delay element (51) and the signal b (shown in FIG. 3(c)) that does not pass through the delay element (51).
(b) as shown in the figure) in synchronization with the head switching signal a (shown in FIG. ) is the third switch that determines the switching phase.

FIG. 3 is a waveform diagram for explaining the operation of the delay circuit (50), in which one period of the head switching signal a corresponds to the rotation drum (3).
When the head switching signal a is at the H level, the magnetic head (1a) performs recording or reproduction, and when the head switching signal a is at the L level, the magnetic head (lb) records or plays. Alternatively, the length of black squares in the figure corresponds to one field of the image signal.

Next, in order to make the edge noise less than the detection limit, it is necessary to make it less than 0.87 μm as described above. This-
Converting to time, the lag time △T is △T=-=150ns
If it is less than ec, edge noise will not be detected.

In other words, in order to keep the edge noise below the detection limit, it is appropriate to set the delay interval between the taps of the delay element (51) to about ΔT or less.

For example, the delay amount of one tap of the delay element (51) is 15
If it is 0 nsec and the number of taps is 16, it is possible to correct a deviation of up to about 14 μm on the tape pattern and eliminate edge noise.

When the diameter of the drum (3) is 62 mm, the angle that can be corrected by this delay element is 0.026°, which is an accuracy that can be sufficiently achieved using current precision assembly technology. Edge noise can be eliminated by delaying the recording signal manually input to the magnetic head (1a) or (1b) using the delay circuit (50) so that the amount of deviation on the tape pattern is eliminated.

During reproduction, the delay circuit (60) performs processing to restore the time difference between the signal recorded by the magnetic head (1a) and the signal recorded by the magnetic head (1b) that was applied during recording.

The operation of this delay circuit (60) is similar to that of the delay circuit (50). Therefore, the same delay circuit can be switched and used for recording and reproduction. However, the magnetic head (1
It is necessary to change the timing of a) and the magnetic head (lb).

In this way, I have talked about edge noise so far,
By operating the delay circuit (50) and the delay circuit (60) in this manner, the apparent 180° indexing accuracy is improved.

Therefore, compatibility is improved when the magnetic tape (2) recorded with this device is played back with another magnetic recording/playback device.

There are the following methods for determining the amount of delay of the delay circuit (50). For example, a tape pattern as shown in FIG. 24(b) is measured, and the amount of delay is determined from the amount of deviation.

As another method, for example, the amount of deviation in the 180° indexing is measured after the adjustment of the 180° indexing is completed, and the amount of delay is determined from the amount of deviation.

In addition, in the above embodiment, the delay circuits (50) and (60
) to switch between a signal C passing through the delay element (51) and a signal not passing through the delay element (51).For example, as shown in FIG. You may also be able to call out. In this case, the magnetic head (1
a), a switch (55) and an inverter (5) for determining which signal of the magnetic head (1b) is delayed;
This has the effect of eliminating the need for 4).

In the above embodiment, the delay circuit (50) is placed at the first stage of the recording signal processing circuit (10), but it may be placed at another location, or only the luminance signal related to edge noise may be delayed.

For example, as shown in FIG. 5, a delay circuit (
50), or as shown in FIG.
The M-modulated luminance signal may be delayed, or, as shown in FIG. 7, a signal obtained by combining the FM-modulated luminance signal and the color signal may be delayed.

In the above embodiment, the recording signal is temporally switched so that the signal recorded by the magnetic head (1a) and the signal recorded by the magnetic head (1b) are switched in time.
), but as shown in FIG. 8, an independent circuit corresponding to the delay amount may be provided so as not to switch over time. In this case, there is an advantage that no problem occurs even if the timing of the head switching signal is shifted.

Furthermore, in each of the above embodiments, the delay circuit (6o) is installed at the position of the reproduction signal processing circuit (20) corresponding to the installation position of the delay circuit (50) of the recording signal processing circuit (lO).
It may be incorporated in other locations and the delay circuit (60) may be omitted.

Further, in each of the above embodiments, the magnetic recording/reproducing device has two magnetic heads, but the number of magnetic heads may be larger than this.

Next, an embodiment of the invention according to claim 2 will be described.

FIG. 9 is a block circuit diagram of this embodiment, in which the same parts as in FIG. 1 are denoted by the same reference numerals, and the explanation thereof will be omitted, and the different parts will be explained.

In the figure, (la) and (lb) are magnetic heads for standard recording, (lc) and (ld) are magnetic heads for long-time recording, and (17) is a magnetic head (la) that transfers recording signals.
), (LBL or magnetic head (LC),
(1d) Switch to switch to (21a) ~(
21dl is a reproduction amplifier that amplifies reproduction signals from the magnetic heads (la) to (ld). magnetic head (la)
, (lc) and magnetic head (lb), (ld
) are head bases (35
) at a distance d, and is attached to the rotating drum (3) in the positional relationship shown in FIG. The azimuth angle of the magnetic heads (la) and (ld) is, for example, +
The magnetic head (lb) is configured at 6°.

The azimuth angle of (1c) is set to -6°.

FIG. 11 is a diagram showing the structure of the rotating drum assembly (3o), in which (33) is a fixed drum, (31) is a connector, and (3o) is a fixed drum.
32) are magnetic heads (1a), (1b) and (1d)
This is a memory element that stores the amount of deviation between (1c) and (1c).

Figure 12 shows the delay circuit (5o) and rotating drum assembly (
30) is shown. (51) is a delay element, CCD,
It is composed of a BBD, an LC delay circuit, a combination of an A/D converter, a digital memory, a D converter, etc., and delays the input from the input terminal I, and outputs it to the output terminals D0 to DI5. Eight signals having different amounts of delay are applied to the output terminals DO to DI8 of the delay element (51). For example, the amount of delay is O to 1.5 μSec in units of 0.1 μSec.

(56) is a multi-selector with input terminals 30-S.

According to the logic, one is selected from the input terminals D0 to DI5 and output to the output terminal Y.

The delay circuit (50) operates by changing the amount of delay based on externally applied logic. This delay amount can be switched, for example, from 0 to 1.5 μsec in units of 0.1 μSec.

(32) is a memory element that stores the amount of deviation from the position for accurate installation of the magnetic heads (la) to (1d), and is composed of, for example, fuse ROM, EP-ROM, EEP-ROM, etc., and connector (31) It is connected to the. Memory element (
32) outputs the mounting deviation amount of the magnetic heads (la) to (1d) to the output terminal D0 according to the combination of the operation mode signal and head switching signal input from the input terminals Ao and At.
Output to ~D. The content to be stored in this memory element (32) is stored in the magnetic heads (1a) to (l) on the rotating drum (3).
After attaching the memory element (d), measure the amount of deviation and remove the memory element (
32).

As shown in Figure 10, the magnetic head has a head base (
35), and these are fixed to the rotating drum (3). The distance d between the magnetic head (la) and the magnetic head (1c) on the head base (35) is
For example, it is attached so that it is 740 μm, but due to mechanical attachment, a deviation of about 3 μm occurs. Therefore, 180° between the magnetic head (1a) and the magnetic head (lb)
Even if the indexing is complete, the magnetic head (1c)
The 180'' index of the magnetic head (1d) will deviate.

Furthermore, in the case of still image reproduction, etc., since a magnetic head (1a) and a magnetic head (ld) are used in combination with the same azimuth, it is necessary that the interval d be accurate.

Under the above conditions, magnetic heads (la), (lb)
.

The relative mounting positions of (lc) and (xd) are determined. This attachment causes the storage element (32) to store the amount of deviation between the position and the actual attachment position of the magnetic head.

As shown in FIG. 12, the input terminal A of the storage element (32)
Input a signal to switch between standard recording mode and long-time recording mode to Q, input a head switching signal to input terminal A,
The output terminals D0 to D of the memory element (32) output data on the amount of deviation corresponding to the magnetic head being used at that time. This data is input to a delay circuit (50), and an appropriate amount of delay is given to the recording signal.

The delay circuit (60) functions to restore the time lag caused by the delay in the delay circuit (50) during recording, and has the same configuration as the delay circuit (50), but the relative amount of delay is It is configured to be opposite to the circuit (60).

In the above embodiment, the delay amount of the delay circuit (50) is determined directly based on the output of the memory element (32), but it may also be determined indirectly. For example, as shown in FIG. The data of the delay element (51) is read by the computer (59) based on the data.
The amount of delay of the delay circuit (50) may be determined by .

Further, in the above embodiment, the delay circuit (50) is placed before the Y/C separation circuit (11), but it may be placed after the Y/C separation circuit (11) as in FIG. Similarly to the figure, the FM modulated luminance signal may be delayed, or similarly to FIG. 7, the signal obtained by combining the FM modulated luminance signal and the color signal may be delayed.

Furthermore, in the above embodiment, a delay element (51) for delaying an analog signal is used in the delay circuit (50), but for example, as shown in FIG. 14, when delaying an FM signal, a binary signal is used. It may be delayed, and in this case, the delay element (5
1) can use a digital shift register, and multiplexers (56a) and (56b) can also be used.
Any device that switches digital signals may be used.

Further, in each of the above embodiments, the delay circuit (60) is incorporated in the position of the reproduction signal processing circuit (20) corresponding to the position in which the delay circuit (50) of the recording signal processing circuit (10) is installed. The delay circuit (60) may also be incorporated in the position.
It doesn't have to be there.

Further, in the above embodiment, a semiconductor memory is used as the memory element (32), but the memory may be stored in a mechanical shape, or may be stored by optical means or magnetic means, for example.

In the above embodiment, the amount of delay was temporally switched by the head switching signal synchronized with the rotation of the rotary drum (3), and recording signals with different amounts of delay were given to the respective magnetic heads (1). Similarly to the figure, an independent circuit corresponding to the amount of delay may be provided so as not to switch over time.

In this case, there is an advantage that no problem occurs even if the timing of the head switching signal is shifted.

〔Effect of the invention〕

According to the invention of claim 1, there is provided a delay means for delaying a recorded signal by an amount corresponding to the amount of deviation from a normal position of a magnetic head attached to a rotating drum, and a delay means for reproducing a signal recorded by the corresponding magnetic head. Recording signal delay means that eliminates edge noise in images and prevents shifts in tracks on the magnetic tape by delaying the signals using the delay means, and upon reproduction, reproduces the same amount of reproduction signals from the tracks that were not delayed during recording. Since the apparatus is equipped with a reproduction signal delay means for delaying the reproduction signal from each track so that the reproduction signal has the original positional relationship, one of each magnetic head is
Even if 80° indexing is not performed accurately, a magnetic recording/reproducing device with less edge noise and good magnetic tape compatibility can be obtained.

Further, according to the invention of claim 2, there is provided a means for storing the amount of deviation of the magnetic head attached to the rotating drum from the normal position, and a means for reading out the amount of deviation of the magnetic head corresponding to the time of recording, and responding to this amount of deviation. a recording signal delay means for delaying a signal recorded by the magnetic head by an amount to prevent a shift in a track on a magnetic tape; and a reproduction signal delaying means for delaying the reproduction signal from each track based on the amount of deviation read from the storage means so that the reproduction signal from each track has the original positional relationship. A similar effect can be obtained.

[Brief explanation of drawings]

1 is a block circuit diagram of an embodiment according to the invention of claim 1, FIG. 2 is a block circuit diagram showing an example of the configuration of a delay circuit according to this embodiment, and FIG. 3 is a delay circuit shown in FIG. 2. FIG. 4 is a block circuit diagram of another configuration example of the delay circuit, FIGS. 5 to 8 are block circuit diagrams of different embodiments according to the invention of claim 1, and FIG. Fig. 9 is a block circuit diagram of an embodiment according to the invention of claim 2, Fig. 10 is a plan view showing the arrangement of the magnetic head in this embodiment, and Fig. 11 shows the arrangement of the rotating drum in this embodiment. A perspective view, FIG. 12 is a block circuit diagram of a configuration example of the delay circuit and its control system in this embodiment, and FIGS. 13 and 14 are respectively different configurations of the delay circuit and its control system in this embodiment. An example block circuit diagram, FIG. 15 is a block circuit diagram of the recording system and reproduction system of a conventional magnetic recording and reproducing device, FIG. 16 is a diagram showing the track pattern of a magnetic tape, and FIG. 17 is a diagram showing crosstalk from adjacent tracks. Figure 18 is a plan view to explain the amount of 180° indexing deviation that occurs when a magnetic head is attached to a rotating drum, and Figure 19 is a characteristic diagram showing the amount of 180° indexing deviation that occurs when a magnetic head is attached to a rotating drum. Timing diagram of recorded signals. Figure 20 is a timing diagram when there is the same <180° index deviation amount. Figure 21 is a diagram showing track patterns with and without 180° index deviation amount. The figure shows edge noise that occurs in the reproduced signal when there is a 180° index deviation. (la), (lb), (lc), (ld)
-Magnetic head, (2)...magnetic tape, (3)...
... Rotating drum, (10) ... Recording signal processing circuit, (
20)...Reproduction signal processing circuit, (32)...Storage element, (50), (60)...Delay circuit, (51)...
)...Delay element, (56), (56a), (
56b)-Multiplexer, (59)--Computer. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In a magnetic recording/reproducing device configured to record and reproduce signals by sequentially forming tracks on a magnetic tape using a plurality of magnetic heads attached to a rotating drum, the magnetic heads attached to the rotating drum A recording signal delay means for delaying the signal recorded by the corresponding magnetic head by an amount corresponding to the amount of deviation from the normal position, and a recording signal delay means for delaying the signal recorded by the corresponding magnetic head by an amount corresponding to the amount of deviation from the normal position; 1. A magnetic recording and reproducing device comprising a reproduced signal delaying means for delaying a reproduced signal by an amount equal to the amount of delay during recording. (2) The recording signal delaying means and the reproduction signal delaying means in claim 1 are based on means for storing the amount of deviation of the corresponding magnetic head from the normal position, and information on the amount of deviation read from the recording means. A magnetic recording/reproducing device comprising means for delaying a signal recorded by a corresponding magnetic head during recording, and delaying a reproduced signal from a track that was not delayed during recording by the same amount during reproduction. .