JPS60201518A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To make disturbance of a picture and noise unremarkably by recording FM carrier corresponding to a prescribed level in place of an FM luminance signal in an instable portion of track width until a servo loop for matching head step is blocked and the difference of the height of two heads reaches a prescribed minute range. CONSTITUTION:A control signal CS going to a high level is obtained from a microcomputer 40 until the servo lock where a signal representing the difference of the height of the head from a comparator circuit 38 reaches a prescribed minute range and the signal CS is fed to switch circuits 15, 21, 25 and they are thrown to the position opposite to the position shown in Fig. Then a signal of a prescribed level, e.g., SYNC chip level ES is obtained from the switch circuit 15 in place of a luminance signal from a pre-emphasis circuit 14, the signal of the level ES is led to am FM modulation circuit 16 and recorded. Since the switch circuits 21, 15 are turned off, a chrominance carrier signal and an FM audio signal are not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention enables variable speed playback such as slow motion playback, still playback, high speed playback, etc. to be performed without noise during °ζ playback in a VTR, for example. The present invention relates to a recording/reproducing device in which a rotating head is provided on an electrostrictive element.

BACKGROUND TECHNOLOGY AND PROBLEMS In the case of a helical scan rotary head type recording/reproducing device such as a VTR, in order to increase the recording density, the angle formed in the width direction of the head gap, that is, the so-called azimuth, is different from each other 2 (1?i+ rotation Using a head, without forming a guard band between tracks as shown in Figure 1,
These two rotary heads alternately form and record one recording trunk TA, TB for each unit time signal.

In this case, during normal playback, the scanning direction of the rotary head coincides with the longitudinal direction of the trunk as indicated by the solid arrow a in the figure, and the two rotary heads are connected to the trunk TA or TB of the corresponding azimuth. You can easily control the tracking to scan the top correctly.
Beautiful playback images without noise can be obtained, but during variable speed playback such as slow motion playback, still playback, or double speed playback, the rotating head straddles multiple recording tracks as shown by the solid arrow in Figure 1. Ready to scan. In this case, the rotating head always scans tracks with different azimuths in one scan, so the reproduced signal 'ζ is missing in that part, and this becomes noise on the reproduced screen. It appears and becomes an unsightly reproduction image.

Therefore, in order to eliminate this drawback, two rotating heads are mounted on a bimorph plate made of an electrostrictive element, and by applying a voltage to the bimorph plate, the rotating heads can be rotated in the height direction perpendicular to the direction of rotation. By applying a predetermined tracking signal voltage corresponding to variable speed playback to this bimorph plate, only one track of the corresponding azimuth can be scanned during variable speed playback as well as during normal playback. There are known devices that control the

FIG. 2 shows an example of the structure of this bimorph plate, and in the figure, (1) and (2) are plates of electrostrictive elements (piezo elements) such as piezoelectric ceramics. These two piezoelectric ceramic plates +11 and (2) are bonded to each other via an electrode layer (3A), and electrode layers (3B) and (3C) are also formed on their exposed surfaces. . Then, the rotary head (4) is placed on a surface provided with, for example, electrodes (3B).

For this bimorph plate, for example, if the electrode (3A) is grounded, the electrodes (3B) and (3C) are connected to each other, and a positive or negative voltage is applied to this connection point, and this voltage application side is fixed, this occurs. By curving the bimorph plate, the end on the helide (4) side in FIG. It will be moved in the direction.

By the way, this bimorph plate shows the amount of deviation according to the magnitude of the applied voltage, but it has hysteresis and has a property that it does not return to the red state immediately when the applied voltage is removed and the voltage is reduced to zero. .

Furthermore, variations in the elements often cause the two bimorph plates to have different biases in the zero voltage state, resulting in a shift in the position of the rotary head in the sieve direction during recording.

If this happens, a difference in level will occur between the two rotating heads on the rotating surface of the rotary head, and if there were no difference in level, the recording tracks TA and TB would be formed with the same width as shown in Figure 1. On the other hand, for example, as shown in Fig. 3, the track TA formed by one rotary head is wide and the other track TB is recorded narrowly, so that it is difficult to extract the signal from the narrower track during playback. There is a possibility that the signal-to-noise ratio may deteriorate.

Therefore, when the 2+llj rotary head provided on the bimorph plate is used for both recording and reproduction, it is necessary to control the position of the rotary head during recording.

Therefore, a means for detecting the difference in the position of the two rotating heads in the crystallographic direction is provided, and the output of this detecting means is used to create a servo loop (hereinafter referred to as
A servo loop (called a servo loop) is formed to align the head level.
Accordingly, a method has been proposed in which the above-mentioned control is performed during recording.

In this case, during the period from the start of recording until the servo loop for adjusting the height of this head is locked, or from the time when this servo loop is unlocked and locked again, the two rotating heads are Since the quotient direction changes variously, the recording trunk width becomes disordered as shown in FIG. 3.

Therefore, during reproduction, the reproduced image is distorted in the portion where the track width is disturbed, resulting in an unsightly image with noticeable noise.

Purpose of the Invention The present invention provides a device that makes screen disturbances and noise less noticeable during playback, even in areas where the servo for aligning head height differences is not locked and the track pinch is disordered during recording. This is what I am trying to do.

SUMMARY OF THE INVENTION This invention records a signal at a constant level in place of the input video signal to be recorded while the servo loop for adjusting the head level difference is not locked during recording. Even if the trunk pitch is disturbed in some areas, a reproduced image with no noticeable disturbance or noise can be obtained.

Embodiment An embodiment of the apparatus of the present invention will be explained by taking an 8 mm video as an example and referring to FIG. 4 and the following.

The method of servo control of the rotary position of the 211^1 rotary head used in this example is as follows.

FIG. 4 shows the track format according to the 8 mm video standard.

Zunawaji, one track has a rotation period of 221 degrees, and the 180 degree rotation part in the latter half of the scanning of the rotary head is used for video signals, FM modulated audio signals, and tracking servo during playback. In the part where the pyro throat signal is frequency multiplexed and recorded, the rotation period of about 30 degrees before that is the recording period of the PCM signal, which is the period of 26.32 degrees in the figure.

As is well known, in the case of 8 mm video, unlike home VTRs, a control track is not formed by a fixed head, but as described above, a control track of 100 mm is used for the tracking servo.
Pilot signals of four types of frequencies f1 to f4 of ~165kllz are frequency-multiplexed and recorded with the video signal. However, since recording and reproducing cannot be performed simultaneously with the same head, this pilot signal cannot be used to adjust the head height difference.

Therefore, in 8mm video, the margin area for after-recording of PCM audio signals is 2.06.
degree rotation period (equivalent to approximately 3H (1 horizontal period for IH))
This section is used to detect differences in the height position of the rotating head.

FIG. 5 shows an enlarged view of the first half of the scanning of this rotary head up to around 30 degrees.
A signal F6 of frequency f5 of llz is recorded in a shaded area not shown in FIG. In this case, this recording part is NTS
In the C-type normal play mode, the playing time is 11 minutes. N
Since the H alignment is IH in the normal play mode of the TSC system, the recording portion of this signal F5 does not overlap between adjacent tracks, as is clearly seen in the figure.

Then, for 111 minutes after the recording period of the IH signal F5, the reproduction mode (PB) is forced during recording.

In this way, if the scanning direction of the head and the moving direction of the tape are as shown in the arrows in FIG. When this happens, the signal F5 recorded on the previous track is extracted as crosstalk (the azimuth is a different track, but the frequency f5 is low, so the azimuth loss is small). Therefore, if the bimorph plate is controlled so that the amount of crosstalk of this signal F5 is equal to 2 (at the rotary head 11d),
The height positions of the two rotary heads can be made equal.

In this case, the control may be performed by keeping one bimorph plate fixed without controlling it and controlling only the bimorph plate of the other rotating head, or by controlling only the bimorph plate of the other rotating head.
Of course, the bimorph plates of the two rotary heads may be differentially controlled.

FIG. 6 is a block diagram of an example of a recording/reproducing apparatus according to the present invention including a servo loop for adjusting the height of the rotary head.

This example is an example in which the servo loop for level difference alignment of the rotary head is made to partially overlap the tracking servo loop for re-positioning.

During recording, a color video signal through an input terminal (11) is supplied to a Y/C separation circuit (13) via an AGC circuit (12) and is separated into a luminance signal Y and a carrier color signal C.

The luminance signal Y is supplied to the switch circuit (15) via the pre-emphasis circuit (14). This switch circuit (
15) is switched to the state shown in the figure in the steady state when the head step difference servo is locked, and the luminance signal Y is supplied to the FM modulation circuit (16) and FM modulated, and this is passed through the bypass filter (17). Synthesis circuit (18)
supplied to

Further, the carrier color signal C is supplied to a frequency conversion circuit (20) via a pre-emphasis circuit (19), and the color subcarrier frequency is frequency-converted so as to be on the lower frequency side of the FM luminance signal. Then, this low-pass conversion carrier color signal is passed through a low-pass filter (21) that is turned on in a regular seat state where the head height difference adjustment servo is locked.
2) to the combining circuit (18), where it is combined with the FM luminance signal. The combined output signal from this combining circuit (18) is supplied to a combining circuit (23). On the other hand, the terminal (2
From 4), the switch circuit (25) turns on the regular seating state.
The FM-modulated audio signal is supplied to this synthesis circuit (23). A frequency multiplexed signal of the luminance signal, carrier color signal and audio signal from the synthesis circuit (23) is supplied to a recording/reproduction switching and timing control circuit (26).

Further, (28) is a pilot signal generation circuit, and in this example, from this circuit (28), five types of frequencies f1 to
A pilot signal of f5 is obtained. Among them, f1 to f4
As mentioned above, the signals of the four frequencies listed above are signals that are frequency-multiplexed and recorded with the video signal for the tracking control phase during playback.

These four types of frequency signals are supplied to a recording/reproduction switching and timing control circuit (26) via a signal generation order control circuit (29).

This recording/reproduction switching and timing control circuit (26) is a microcomputer (hereinafter abbreviated as microcomputer).
Recording/reproducing switching and head switching are performed by the control signal from (40), and during recording, the FM-modulated luminance signal, the carrier color signal converted to its lower frequency side, and the FM-modulated audio signal are processed. A frequency multiplexed signal consisting of a pilot signal of any one of frequencies f1 to f4 of the dfffi type is obtained, and this is sequentially supplied to the rotary heads HA and HB through head amplifiers (27A) and (27B), and the above-mentioned The 180 degree rotation section in FIG. 4 is recorded on the bone portion.

In this case, four types of pyro-node signals are applied to each track at frequencies fi, f2, . f3. The f+ data is sequentially and cyclically switched and recorded "ζ".

In this case, the rotary heads HA and HB are both recording and reproducing heads, and are fixed on the bimorph plates BA and BB so as to enable variable speed reproduction.

As mentioned above, the switching of the timing control circuit (26) is completely controlled by the microcomputer (40), but this microcomputer (40) has a button to control the rotational phases of the rotary heads HA and HB. At the same time, a signal indicating whether the drum servo is locked and a signal indicating whether the capstan servo is locked are supplied, and the switching signal is formed based on the signal PC.

Next, during playback, the helide amplifier (31^) and (31B
) is switched by the timing control circuit (26), and the reproduced signal is sent to the terminal (
30) and supplied to the recycled yarn.

Further, the reproduced signal is supplied to a low-pass filter (32), and reproduced pilot signals of frequencies 11 to f4 are extracted and supplied to a tracking error signal generation circuit (33). This tracking error signal generation circuit (33)
is supplied with one of the signals of frequencies f1 to f4 from the signal generation order control circuit (29) to form a tracking error voltage of the rotary head for one track. And this is the recording/playback selector switch (
The signal is supplied to one input terminal of the comparator circuit (41) through the reproducing side contact PB of the comparator circuit (41). This comparison circuit (41) is connected to A
The digital signal supplied from the microcomputer (40) to the D/A converter (42) is a digital signal corresponding to the analog signal supplied to one input end of the comparison circuit (41). It's a signal.

Then, this digital signal is converted into an analog signal by the D/A converter (42), and this is obtained by sampling and holding circuit (438) (43B) (43G
). In these sampling and hold circuits (43A) to 143c), the output of the D/A converter (42) is sampled by a sampling signal that is sampled multiple times during the 180° period during which the rotating heald scans, and the sampling value is will be held. This hold output becomes a tracking error signal per track. This sampling pulse is supplied from a microcomputer (40). The tracking error signal obtained in this way is low bass fi / I < evening (44^)
.

(44B) and amplifiers (45^) and (45B) are supplied to the bimorph plates BA and BB on which the heads HA and HB are attached, so that the rotating heads HA and HB always correctly scan one recording track. The servo is applied to

The output of the sampling hold circuit (43C) is supplied to the capstan servo circuit (46) through a low-pass filter (44C), and the capstan servo during playback (corresponds to tracking servo using a control signal from a conventional fixed head) It is offered to

The head level difference alignment during recording is controlled as follows.

That is, prior to recording the video signal and the like, the pilot signal of frequency f5 for adjusting the height position is recorded and reproduced as described above. That is, the pilot signal generation circuit (28
), for example, a signal F5 of 230kllz is obtained, which is supplied to the switching timing control circuit (26), and is switched to one turn in the bone for a period of lH within the area of the after-recording margin after the PCM signal recording area mentioned above. The data is supplied to the rads HA and HB and recorded at the shaded positions in FIG.

Then, when recording using this signal F5 as follows,
The height position of the two rotating heads is adjusted.

That is, during recording, when the recording of the signal F6 over one horizontal period is completed, the timing control circuit (26) is switched to the reproduction side by the signal from the microcomputer (40), and the amplifier (27^) (27B) is switched to the amplifier (27B). 31A) (
The power is switched to the 31B') side. Therefore, the signals from the rotating heads HA and °HB are transmitted to the head amplifier (31
A) and (, 31B > are supplied to a bandpass filter (35) that extracts only the signal F5, and this signal F5 is extracted as crosstalk from the adjacent track. The signal obtained from this bandpass filter (35) F
5 is supplied to an envelope detection circuit (36), and its crosstalk level is detected. The output of this envelope detection circuit (36) is then supplied to sampling and holding circuits (37^) and (37B). The sampling hold circuit (37A) is for sampling the crosstalk component of the signal F5 from the head HA and holding the sampled value, and the sampling hold circuit (37B) is for sampling the crosstalk component of the signal F5 from the head HA. This is a circuit for sampling crosstalk components and holding the sampled value. Sampling signals SP1 and SF3 for this purpose are supplied from the microcomputer (40). The hold outputs from the sampling and hold circuits (37^) and (37B) are fed (Jti) to one and the other input terminals of the comparator circuit (38) and compared, and the comparison error output is sent to the recording side of the switch (34). Contact point REC
is supplied to This switch (34) is always set when recording.
The contact is switched to the REC side, so that the signal from the comparator circuit (38) is supplied to one input terminal of a comparator circuit (42) that forms an A/D converter together with the D/A converter (41). Therefore, an output corresponding to the comparison error signal from the comparison circuit (38) is obtained from the D/A converter (41), and this is supplied to the sampling and holding circuits (43A) and (43B>).

During this recording, the signal supplied from the microcomputer (40) to the D/A converter (42) is changed according to the timing of the head switching signal RF (Fig. 7A), and the video track of the head HA is changed. During the scanning period (see FIG. 7B), a signal corresponding to the output of the comparator circuit (38) is obtained, which is returned to an analog signal by the D/A converter (42), which is then sent to the sampling and hold circuit (
438), the signal is sampled and held by the sampling signal SP3 (FIG. 4F) from the microcomputer (40).

Also, during the video track scanning period of the head HB (see C in the same figure), a fixed value is output from the microcomputer (40), which is converted into an analog signal by the D/A converter (42), and then converted into an analog signal. In the sampling and holding circuit (43B), the signal is sampled and held by the sampling pulse SP4 (G in the figure).

Therefore, the sampling hold output SHA (D in the same figure) is the output of the two heads H.
The voltage of the difference between the positions of A and HB in the height direction is obtained by changing each rotation of the head HA, and the output SHB (E in the figure) of the sampling bold circuit (43B) is set to a fixed value.

The output of the sampling hold circuit (43A) is then sent to the bimorph board B to which the head HA is attached via a low-pass filter (44A) and an amplifier (45A).
A is applied, and this bimorph plate BA produces a mechanical deflection, changing the quotient position of the head HA. On the other hand, the output of the sampling hold circuit (43B) is similarly supplied to the bimorph board BH through a low-pass filter (44B> and an amplifier (45B)), but since this is a fixed voltage, the position in the height direction of the rotating head HB is However, a change in the height position of the rotary head HA changes the output of the comparison circuit (38), forming a servo loop in which it is again supplied to the bimorph plate BA. 2 rotating heads HA and H
The steps of B are aligned so that they are at the same height.

The sampling hold circuit (43G) is for the capstan servo, and for example, during the period of the sampling pulse, a certain signal is supplied from the microcomputer (40), this is sampled bold, and this is passed through the low-pass filter (44C). Cav’s tongue servo episode b!
8 (46).

A speed error signal is supplied to this servo circuit (46), and the error voltage is supplied to the capstan motor to apply speed servo during recording.

In this way, the height positions of the heads HA and HB are different, and there is a difference in height until the height positions of the rotating heads HA and HB are adjusted to a certain minute range by the servo loop for adjusting the height difference between the two heads. As mentioned above, the recording track width is disturbed, so the microcomputer (40) sends a signal indicating the difference in head height position from the comparison circuit IR (38) to a certain minute range. The control signal c remains high until the servo locks.
s is obtained, and this is the switch circuit (15) (21)
(25), and each is switched to a state opposite to that shown in the figure.

Then, instead of the brightness signal from the pre-emphasis circuit (14), the switch circuit (15) obtains a signal at a certain level, for example, the sync tip level Es, and this
The signal is supplied to the M modulation circuit (16) and recorded. Further, since the switch circuits (21) and 25) are turned off, the carrier color signal and the FM audio signal are not recorded. Therefore, in the part where the trunk width is unstable until the step adjustment servo locks, the 180° rotation angle part, which is the video signal recording area, contains the FM carrier wave and pilot corresponding to the synchronization knob level. Only the signal will be recorded.

Therefore, when this is played back, in areas where the recording track width is unstable and the head step alignment servo is not locked, the playback screen will be a dark level and a constant brightness, and image disturbances and noise will be noticeable. No way.

It goes without saying that the constant level signal recorded in place of the brightness signal in the part where the servo for adjusting the head level difference is unstable is not limited to the signal at the sync chip level. Any signal with an inconspicuous brightness level is sufficient.

In addition, in the example shown in Figure 6, the carrier color signal and FM audio signal were also prevented from being recorded in areas where the servo loop for step alignment was unstable, but these signals were recorded to the extent that they were not noticeable as noise under the playback screen. If so, recording may be performed even during periods when the servo for head level difference alignment is unstable.

Further, the present invention is not limited to the case of 8 mm video, but can be applied to any device that uses a servo circuit to adjust the level difference of a rotary head during recording.

Effects of the Invention According to the present invention, in a portion where the track width is unstable until the servo loop for adjusting the head level difference is locked and the difference in the height position of the two heads falls within a predetermined minute range,
FMill that supports a fixed level instead of FM brightness signal
Since the transmitted waves are recorded, during playback, the entire playback screen has a constant brightness corresponding to the constant level, and image disturbances and noise are less noticeable.

[Brief explanation of the drawing]

Fig. 1 shows an example of a recording track pattern of a helical scan type two-rotation head type, Fig. 2 shows an example of the structure of a bimorph plate, and Fig. 3 shows an example of a recording track pattern with a helical scan type two-rotation head type. A diagram illustrating an example of recording trasokpatamun in a certain case,
Fig. 4 is a diagram for explaining the track format of 8 mm video, Fig. 5 is a diagram for explaining an example of means for detecting differences in head height position, and Fig. 6 is an example of the device of this invention. The block diagram of FIG. 7 is a time chart for explaining the same. HA and HB are rotating heads, BA and BB are bimorph plates, (28) is a pilot signal generation circuit, (38) is a comparison to obtain error voltages according to the difference in height position of two rotating heads HA and HB. It is a circuit.

Claims (1)

[Claims] A device for recording and reproducing video signals on a recording medium by alternately forming one diagonal track every unit time using two rotary heads that also serve as recording and reproducing. A rotary head is provided on the electrostrictive element, and these two rotary heads are movable in the height direction perpendicular to the direction of rotation, and during recording, the two rotary heads are rotated and the height of the gutter is adjusted. Means for detecting a difference in directional position is provided, and the output of the detecting means changes the height position of at least one of the rotary heads to equalize the height position of both, thereby keeping the recording trunk pitch constant. 1. A recording/reproducing device having a servo loop that records a signal at a constant level in place of the video signal until the servo loop locks.