JPS6396719A - Video tape recorder - Google Patents

Abstract

PURPOSE:To attain good position relation between two magnetic heads, by reproducing reference signals recorded on a magnetic tape by first and second magnetic heads, by the second and first magnetic heads, and displacing an electro-mechanical conversion element so as to set reproduction levels equal. CONSTITUTION:A third magnetic head 3d is mounted at a position preceding to the second magnetic head 3b on a rotary drum 4, and at the time of recording, the third magnetic head 3d being at a preceding position reproduces the reference signal recorded on the magnetic tape 1 by the second magnetic head 3b, and detects the edge of a recording track. The electro-mechanical conversion element 2b is displaced so as to arrange the edge of the second magnetic head 3b to a detected edge, and also, the first and second magnetic heads 3a and 3b reproduce the reference signals recorded on the magnetic tape 1 by the second and first magnetic heads 3b and 3a, and the electro-mechanical conversion elements 2a and 2b are displaced so as to set the reproduction levels equal. In this way, the absolute position relation between the magnetic heads 3a and 3b can be held in a good state.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A. Field of industrial application B. Overview of the invention C. Prior art D. Problems to be solved by the invention E. Means for solving point 11a (Fig. 1) F. Effect G. Example G1. Configuration of video tape recorder G2. Recording BACKGROUND OF THE INVENTION The present invention relates to a video tape recorder in which a magnetic head for recording is attached to a rotating drum via an electro-mechanical conversion element such as a bimorph.

B. Summary of the Invention The present invention records video signals by forming diagonal tracks alternately on a magnetic tape using first and second magnetic heads attached to a rotating drum via an electro-mechanical conversion element. In a video tape recorder, a third magnetic head is mounted on the rotating drum at a position preceding the second magnetic head, and during recording, the third magnetic head at the preceding position receives the reference signal recorded on the magnetic tape. The edge of the recording track is detected by the second magnetic head, and the electro-mechanical transducer is moved so that the edge of the second magnetic head is aligned with the detected edge.
The reference signal recorded on the magnetic tape by the magnetic head of
And by shifting the electro-mechanical transducer so that the reproduction level becomes equal during reproduction with the first magnetic head, the absolute positional relationship between the two recording magnetic heads during recording is good. It was designed to be preserved.

C. Prior Art Conventionally, in a helical scanning video tape recorder,
There is a rotating head drum constructed by attaching a magnetic head to an electro-mechanical transducer such as a bimorph. This bimorph is constructed by sandwiching a thin film of silver or the like between piezoelectric ceramics, and by supplying the required driving voltage to this bimorph, the magnetic head is displaced in a direction approximately perpendicular to the scanning direction. Devices are known in which a magnetic head accurately traces an inclined track on a tape from beginning to end. Such a device is generally used during variable speed playback, but it is also used as DTF (DynaIli).
c Track Following) device. In this DTP device, when performing special playback, such as several times faster fast-forward playback (cue) or rewind playback (review), as shown in Figure 6 or Figure 7, the recording trunk (1a) of the magnetic tape +1) and In order to correct the difference in the inclination angle of the trajectory (1b) of the magnetic head, a gradient voltage from +y to -VoM or from -VoM to +VoM as shown in FIG. 8B or C is applied to the bimorph to adjust the magnetic head. The trajectory (1b) is the recording track (la)
I'm trying to match that. That is, for example, when a positive voltage is applied to the bimorph, the bimorph (2) bends upward as shown in FIG.
), and when a negative voltage is applied to the bimorph, the bimorph (2) bends downward as shown in Figure 1O, and the magnetic head (3) moves towards the tape (1).
) will be in a state where it is tilted downward. The degree of deflection of the bimorph (2) is proportional to the supply voltage, and the higher the supply voltage, the more the magnetic head (3) bends.

Therefore, when a side slope voltage from 10 VO to -Vo(v) shown in FIG. 8B is applied to the bimorph (2), the head (3
) gradually moves from an upwardly directed state to a downwardly directed state, and the magnetic head (3) traces the supply of the gradient voltage from +Vo to -VoM over one track of the tape (1). (When the pulse wave is at a high level as shown in FIG. 8A) By performing the synchronization, the recording track (la) of the tape+1> at the time of cue and the magnetic head (3) as shown in FIG.
The angular deviation from the locus (lb) of is eliminated. Also, the 8th
From -Vo (%') to +Vo, which is the opposite of Figure 8B shown in Figure C.
When a ramp voltage to (v) is supplied to bimorph (2),
The magnetic head (3) moves in the opposite direction to that described above, and the review temporary tape as shown in Fig. 7 is produced! 1) recording track (1)
There is no angular deviation between a) and the trajectory (1b) of the head (3).

D. Problems to be Solved by the Invention Incidentally, there are cases where a magnetic head attached via an electro-mechanical transducer such as a bimorph as described above is also used during recording. During this recording, it is not necessary to shift the electro-mechanical transducer because the same recording track is always formed. However, during long-term variable speed playback, etc. change of)
When such a change occurs over time, there is an inconvenience that good recording of the signal is not possible. In other words, in the case of a helical scanning video tape recorder that uses two magnetic heads used in general video tape recorders to alternately scan the magnetic tape, the relative position (height) of the two magnetic heads is ) If the relationship is not in a predetermined state, the recording pattern will not be formed well, so it is necessary to adjust the height of the magnetic head before recording.

As a method of height adjustment, for example, Japanese Patent Application No. 60-31
As shown in No. 310, the reference signal recorded on the tape by one of the two magnetic heads is reproduced by the other magnetic head, and the reference signal recorded on the tape by the other magnetic head is reproduced by one of the magnetic heads. It is conceivable to perform reproduction with a head and adjust the height of the magnetic head so that the reproduction level of both magnetic heads is equal. By adjusting in this way, it is possible to maintain a good relative positional relationship between the two magnetic heads.

However, such adjustment of the relative positional relationship alone may be insufficient. For example, when recording, it is necessary to erase information previously recorded on a tape using an erasing head, and a so-called flying erase head attached to a rotating drum is sometimes used as the erasing head. This flying erase head is installed at a position preceding the magnetic head that performs recording on the rotating drum.
Erasing is performed immediately before recording is performed on one track or two tracks at a time. By performing erasing with the flying erase head in this manner, it is possible to record a good video signal without image disturbance at the seam. When this flying erase head is provided on a rotating drum, if the flying erase head is not placed in a position that accurately precedes the recording track formed by the recording magnetic head, there will be residual erasing and complete erasure will not be performed. For this reason, the magnetic head for recording must match not only the relative relationship with the 2 fM head but also the absolute positional relationship (height) with the erasing head fixed to the rotating drum.

In view of the above, an object of the present invention is to provide a video tape recorder that can maintain a good absolute positional relationship between two magnetic heads attached via an electro-mechanical conversion element during recording. .

E. Means for Solving the Problems The video tape recorder of the present invention includes an electro-mechanical conversion element (2a) on a rotating drum (4), as shown in FIG.
, (2b), the magnetic tape (1
) in a videotape recorder that records video signals by forming diagonal tracks alternately on a rotating drum (4).
A third magnetic head (3d) is installed in a position preceding the second magnetic head (3b) above, and during recording, the third magnetic head (3d) in the preceding position is placed on the magnetic tape (1). The recorded reference signal is reproduced by the second magnetic head (3b) to detect the edge of the recording track, and the electro-mechanical conversion element ( 2b), and the reference signal recorded on the magnetic tape +1) by the first and second magnetic heads (3a) and (3b) is transferred to the second and first magnetic heads (3b) and (3a). The electro-mechanical conversion element (2a), (
2b) is made to shift.

F Function According to the video tape recorder of the present invention, the reference signal recorded on the magnetic tape (1) by the third magnetic head (3d) which is fixedly mounted on the rotating drum (4) and whose height does not change during recording. The second magnetic head (3b
), the absolute height of this second magnetic head (3b) during recording is always the same, and the height of the second magnetic head (3b) with this adjusted height is always the same. and vJl
By adjusting the relative height of the first magnetic head (3a) using the reference signal, the first magnetic head (3a) also has the same absolute height during recording, and the first magnetic head (3a) for recording also has the same absolute height. ．． The absolute positional relationship between the second magnetic heads (3a) and (3b) is maintained well.

G. Embodiment Hereinafter, an embodiment of the video tape recorder of the present invention will be described with reference to FIGS. 1 to 5. This figure 1 to 5
In the figures, parts corresponding to FIGS. 6 to 1θ are designated by the same reference numerals, and detailed explanation thereof will be omitted.

G□Configuration of video tape recorder The video tape recorder of this example has a magnetic tape 118.
This is so-called 8mm video, and is configured to record an audio PCM signal together with a video signal.
As shown in the figure, two magnetic heads (3a) and (3b), which have different azimuth angles, serve as magnetic heads for recording and reproducing, and are attached to a rotary drum (4) at 180 degrees.
It is provided in a symmetrical position and has a magnetic field (3a),
(3b) is a helical scanning type in which recording and reproduction of C old and CI+2 are performed alternately. Then, the magnetic tape (1) is wound around the circumferential surface of this rotating drum (4) within a range of, for example, 221 degrees, and the first 36 degrees of this 221 degrees
The audio PCM signal is recorded and reproduced in the 180 degree interval, and the video signal is recorded and reproduced in the remaining 180 degree interval. Then, the first and second magnetic heads (3
a) and (3b) are bimorph 1 (2a) and (
2b) is fixed to the rotating drum <4) via the bimorph height (2a).

Depending on the voltage applied to the magnetic heads (2b), the heights of the magnetic heads (3a) and (3b) change as shown in FIG. 9 or 10. Moreover, this rotating drum (4) has f
9 in the rotational direction (4r) from the f1l magnetic head (3a)
An erase head (3c), which is a flying erase head, is directly fixed at a position 0° ahead of the second magnetic head (3b), and a reference head (3d) is located 90° ahead of the second magnetic head (3b) in the rotational direction (4r). It is fixed directly.

With this configuration, when the side surface of the rotating drum (4) is expanded, it becomes as shown in FIG. 3.

In FIG. 3, (4a) indicates the center line of the side surface of the rotating drum (4), and the magnetic heads (3a) and (3b) are on this center line (4a) during recording. Then, the erasure head (3c) in the most advanced position is the magnetic tape (
1) A track (lat) that has a width to simultaneously erase two tracks of the upper recording track (1a) and is recorded by the first magnetic head (3a) and a second magnetic head (3b).
It is located at a position preceding the track (laz) on which recording is performed. The reference head (3d) has an azimuth angle in the same direction as the second magnetic head (3b), and the track (laz) on which recording is performed with the second magnetic head (3b).
It is in a position that precedes the The first and second magnetic heads (3a) and (3b) are mounted on a bimorph plate (2a).
, (2b) causes the height to change in the upward direction U or downward direction d with respect to the center line (4a).

Each of the heads (3a) to (3d) thus arranged on the rotating drum (4) is supplied with a signal during recording using a circuit configuration as shown in FIG. That is, a recording system circuit (not shown) is installed for each head on which recording signals such as video signals are recorded.
Recording signal input terminals (5a) and (5b) supplied from
are connected to the bimorph plate (2a) via mixing circuits (6a) and (6b) and recording signal amplifiers (7a) and (7b), respectively.
and (2b) are connected to the first and second magnetic heads (3a) and (3b) on the terminals (5a), (5
The signal obtained in b) is recorded. And 200kH
A reference signal generator (8) that outputs a relatively low frequency reference signal (pilot signal) of about z is connected to a connection switch (9a
) and (9c) to the mixing circuits (6a) and (6b)
By controlling the connection switches (9a) and (9b) by the recording timing generation circuit (10), the recording signal is connected to the first and second magnetic healds (3a) and (3b). A folded reference signal is provided. Further, this reference signal generator (8) is connected to a reference head (3d) via a series circuit of a connection switch (9c) and a recording signal amplification '/5 (7c), and a recording timing generation circuit (1
By controlling the connection switch (9c) by the reference head (3d), the reference signal output from the reference signal generator (8) is supplied to the reference head (3d).

In addition, the first and second magnetic heads (3a) and (3b)
is a playback circuit (not shown) that processes normal playback signals.
The circuit for detecting the reference signal described above is also connected thereto. That is, as shown in FIG.
The magnetic heads (3a) and (3b) have reproduction reference signal amplifiers (lla) and (llb), respectively, and a detection circuit (
12a) and (12b) to the level comparison circuit (17).
) is connected. This level comparison circuit (17) is a circuit that compares the output levels of the reference signals reproduced by the first and second magnetic heads (3a) and (3b), and is a circuit that compares the output levels of the reference signals reproduced by the first and second magnetic heads (3a) and (3b). Instructs the control voltage generation circuit (18) to generate a control voltage signal. A control voltage signal output by the pymorph height control voltage generation circuit (18) is supplied to the bimorph plate (2a) supporting the first magnetic head (3a) via a drive circuit (16a). In this way, the voltage signal is transferred to the bimorph plate (2
a), the bimorph plate (2a) is displaced and the height of the first magnetic head (3a) is changed. Also,
Output No. 13 of the detection circuit (12b) for detecting the reference signal reproduced by the second magnetic head (3b) is supplied to the lower edge detection circuit (13).

This lower edge detection circuit (13) is a circuit that detects the lower edge of the recording track of the reproduced reference signal, and supplies a hold signal to the sampling hold circuit (14) according to the detection state of this lower edge detection circuit (13). . This sampling hold circuit (14) is supplied with a wobbling voltage signal from the wobbling voltage generating circuit (15), and the lower edge detection circuit (14) receives a wobbling voltage signal from the wobbling voltage generating circuit (15). 3 (13) holds the wobbling voltage signal. and,
The output signal of this sampling hold circuit (14) is sent to the second magnetic head (3) via the drive circuit (16b).
b) is fed to the bimorph plate (2b) supporting the bimorph plate (2b).

By supplying the voltage signal to the bimorph plate (2b) in this manner, the bimorph plate (2b) is displaced and the height of the second magnetic head (3b) is changed.

Operation during G2 recording Next, the operation when recording video signals etc. on a magnetic tape with the video tape recorder of this example will be explained in Figs. 4 and 5.
This will be explained with reference to the figures. First, 18 of the rotating drum (4)
Switching pulse No. 177 (
In synchronization with FIG. 5A), video signals are recorded alternately by the first magnetic head (3a) and the second magnetic head (3b). That is, as shown in Figure 5, the first magnetic head (3
8) Each magnetic tape scanning period CHI-1, CHI-2.
The period corresponding to the drum angle of 180 degrees in the second half of ... (V-
REC) and a second magnetic head (3) as shown in FIG. 5F.
b) Each magnetic tape scanning period CI+2-r, CH
The input terminal (5a),
The video signal supplied to (5b) is recorded. So ξ
7, the scanning period of each head Cl-1, CH2-t,
First half drum angle 3 of Cl-2, Cl2-2...
During a period corresponding to 6 degrees (PCM-RPC), recording of the PCM audio signal supplied to the input terminals (5a) and (5b) corresponding to the video signal is performed.

Signal recording is performed in this manner, and the height of the recording magnetic heads (3a) and (3b) is adjusted from the start of recording until several tracks are scanned. In this example, as shown in FIG. 4, this height adjustment is performed on the second magnetic head (3b) in the section (2) in which several tracks are scanned from the start of recording, and then the second magnetic head (3b) is adjusted in the section (3) in which the magnetic head scans the next several tracks. The first magnetic head (3a) is adjusted in section (2), and recording that does not require height adjustment is performed in the subsequent section (2).

First, to explain the adjustment of the second magnetic head (3b) in section (2), as shown in FIG.
, C112-2"" PCM audio signal recording section PCM-RFC and video signal recording section V-)' of CHI2-+m? E
For example, a period corresponding to 3 horizontal scanning periods (3H) of a video signal during an interval 90 degrees preceding the interval between C and C (for example, a part of the vertical blanking period in which a vertical synchronizing signal is recorded). Only the P-REC connection switch (9c) is closed according to an instruction from the recording timing generation circuit (10), and the reference signal output from the reference signal generator (7) is recorded by the reference head (3d).

The reference signals thus recorded on the magnetic tape at predetermined intervals are reproduced by a second magnetic head (3b) disposed immediately after the magnetic tape as shown in FIG.

That is, the recording operation is switched to the reproducing operation only during the 3H period between the PCM audio signal recording section PCM-REC and the video signal recording section V-REC during the scanning period of the second magnetic head (3b) described above. , regenerates the reference signal and converts the lower edge detection circuit (
At step 17), the lower edge of this reference signal recording track is detected. As shown in FIG. 3, if the reference signal is recorded on the track (la2) at the reference head (3d), the lower edge to be detected is the lower edge e of this track (laz) when the second magnetic head The lower edge detection circuit (13) detects the reproduced signal of (3b), and holds the wobbling voltage signal when this lower edge e is aligned with the lower edge of the second magnetic head (3b). e and magnetic head (
3b) and the lower end thereof (the state shown in FIG. 3) is maintained. In order to align the bottom edges in this way, it actually requires scanning several tracks, shown as section I.

When the height adjustment of the second magnetic head (3b) is completed in this way, the second magnetic head (3b) is
), the height of the first magnetic head (3a) is adjusted. This adjustment is performed during the scanning period immediately after the last scanning period CH2-+m in which the height of the second magnetic head (3b) is adjusted. From 1st. both second magnetic heads (3a),
In step (3b), the reference signal is recorded and reproduced. That is, as shown in FIG. 5, both heads (3a) in section (3),
(3b) scanning period C old-◆].

CH2-5ex”...CHI-n, Cl12
-n, the period of 3H between the PCM audio signal recording section PCM-REC and the video signal recording section V-REC (P-REC
), the connection switch (9a) or (9b) is closed according to instructions from the recording timing generation circuit (10), and the reference signal output from the reference signal generator (8) is connected to the terminal (5a).
, (5b) is superimposed on the recording signal obtained by the first and second magnetic heads (3a) and (3b).

At the same time as this recording, the same magnetic heads (3a) and (3b) reproduce the crosstalk component of this reference signal recorded by the other head. That is, the first magnetic head (3
With the signal reproduced by a), the second
The magnetic head (3b) reproduces the crosstalk component of the reference signal of the track recorded immediately before, and the detection circuit (12b) uses the signal reproduced by the second magnetic head (3b) to detect the crosstalk component of the reference signal of the track recorded immediately before. 3a) reproduces the crosstalk component of the reference signal of the track recorded immediately before. And these two heads (3a).

The signal level of the crosstalk component reproduced by (3b) is compared by the level comparison circuit (17), and a control signal is supplied to the bimorph height control voltage generation circuit (18) so that the signal levels are the same, and the signal level The bimorph height control voltage signal supplied to the bimorph plate (2a) supporting the first magnetic head (3a) is changed until the values become the same. By doing this, the first magnetic head (3a)
For example, as shown in FIG. 3, if the first magnetic head (3a) is scanning over the track (fax>),
The second magnetic head (3b) has an adjacent track (la2
) will now be scanned accurately. When this happens, this head height is maintained during recording.

In this way, both magnetic heads (3a), (3
In order to align b), it is actually necessary to scan several tracks shown as section 1.

In section (3) after the height adjustment has been performed in this way, the reference signal is not recorded by each head, and the head height is maintained and the first and second magnetic heads (3a),
At (3b), the video signal and PCM audio signal are recorded.

As described above, according to the video tape recorder of this example, at the start of recording, the reference head (3d) whose height is fixed for several tracks records reference No. 14, and the bimorph board is set to meet this reference signal. Since the height of the second magnetic head (3b) above (2b) is adjusted, the second magnetic head (3b) can always be adjusted to the same height. Since the first magnetic head (3a) adjusts the relative position with the second magnetic head (3b) whose absolute position has been adjusted, as a result, the first magnetic head (3a)
) will also have its absolute position adjusted. For this reason,
Not only the relative relationship between the two magnetic heads (3a) and (3b) but also the positional (height) relationship between the erasing head (3c) and the recording magnetic head (3a) and (3b) is improved. The erasing head (3c) does not erase or leave any data unused, thereby preventing the erasing head (3c) from erasing errors and recording good signals. In addition, in this example, a reference head (3d) with a width of one track is used instead of an erasing head (3c) as the head for recording the reference signal, so the recording of the reference signal can be minimized, and the recording track can be used effectively and efficiently.

Although the magnetic head (3d) for recording the reference signal was provided at a position 90 degrees ahead of the head (3h) for recording the video signal, other angles may be selected.

However, in this case, it is necessary to change the timing at which the reference signal is recorded. Furthermore, in the above embodiment, the first . Although the second magnetic heads (3a) and (3b) are adjusted only once each, readjustment may be performed at predetermined intervals during long-term recording. Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and can take various other configurations without departing from the gist of the present invention.

Effects of the Invention According to the video tape recorder of the present invention, during recording, data is recorded on the magnetic tape (1) by the third magnetic head (3d) which is fixedly mounted on the rotating drum (4) and whose height does not change. The second magnetic head (3b
), and also adjust the height of the first magnetic head (3a) in accordance with the reference signal recorded on the magnetic tape (11) using both the first and second magnetic heads (3a) and (3b). By making this adjustment, the absolute height during recording is always the same, and the first and second recording magnetic heads (
There is an advantage that the positional relationship between 3a) and 3b and the erasing magnetic head is maintained well, and good signal recording is performed without miserasing by the erasing head.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the video tape recorder of the present invention, FIGS. 2 and 3 are block diagrams each showing a rotating drum of one embodiment, and FIGS. 4 and 5 are block diagrams showing one embodiment of the video tape recorder. Diagrams for explanation, FIG. 6 to FIG. 1O are diagrams for explanation of the conventional example, respectively. (1) is a magnetic tape, (2δ) and (2b) are bimorph plates, (3a) and (3b) are respectively ff1l and the second magnetic head, (3c) is an erasing head, (3d) is a reference head, ( 4) is a rotating drum.

Claims (1)

[Claims] A first device attached to a rotating drum via an electro-mechanical conversion element.
and a video tape recorder that records video signals by alternately forming diagonal tracks on a magnetic tape using a second magnetic head, wherein a third magnetic head is located on the rotating drum at a position preceding the second magnetic head. The head is attached, and during recording, the second magnetic head reproduces the reference signal recorded on the magnetic tape by the third magnetic head located in the preceding position, detects the edge of the recording track, and detects the edge of the recording track. The electro-mechanical transducer is moved so that the edges of the second magnetic head are aligned, and the reference signals recorded on the magnetic tape by the first and second magnetic heads are transferred to the second and first magnetic heads. A video tape recorder characterized in that the electro-mechanical conversion element is shifted so that reproduction levels are equal when reproduced by a magnetic head.