JPH0421390B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary head type video signal reproducing apparatus, and more particularly to a rotary head type video signal reproducing apparatus capable of still image reproduction and slow motion reproduction.

Video tape recorders (VTRs) record and play back video signals by winding magnetic tape diagonally around a rotating head drum. In order to enable high-density recording, an azimuth recording method is adopted. A pair of tilted rotating heads are used to form an azimuth track on the tape, thereby preventing crosstalk problems caused by tracing of adjacent tracks, and achieving high density recording using narrow recording tracks.

Also, such azimuthal recording type helical VTR
In 2005, a rotary head drum provided with a double azimuth head in addition to a main rotary head for video reproduction has been proposed. Such a two-headed helical
During normal playback, VTRs use the main rotating head.
A double azimuth head is used for slow playback or still playback. A schematic arrangement of the rotary head of such a device is shown in FIG. As shown in the figure, the rotating head A is a head having a positive azimuth,
Head B is arranged as a head with negative azimuth, and an auxiliary head with positive azimuth for still image reproduction or slow motion reproduction is provided on the side of head B. And during normal video playback, A
A video signal is extracted by tracing adjacent tracks of azimuth recording on the tape using the positive azimuth head of B and the negative azimuth head of B. During still reproduction, following the tracing of the A positive azimuth head, the B-side auxiliary positive azimuth head traces the same track, thereby reproducing still image signals from a tape recorded in one track and one field. This makes it possible to reproduce still images without image blur even in fast-moving scenes. In the conventional apparatus as described above, the auxiliary head is used only for still/slow playback, so the operating rate of the auxiliary head is low, resulting in a high cost apparatus.

In recent years, there has been a trend to narrow the track pitch in order to perform high-density recording and reproduction on magnetic recording media, and more accurate tracking systems for magnetic heads to trace this have been studied. For this purpose, an automatic scan tracking device using a bimorph plate of piezoelectric elements as a head support arm is being considered. For example, JP-A-51-61815
I am familiar with the issue bulletin. This discloses a system in which a rotary head structure is provided with one or more auxiliary heads, and automatic tracking is performed by deflection of a piezoelectric element based on the output of the auxiliary head. All of the auxiliary heads used in such devices are used for reproducing control pilot signals or detecting the envelope of video signals, and are not actively used for reproducing video signals.

The purpose of the present invention is to obtain a device that eliminates the drawbacks of the conventional method as described above.It uses an auxiliary head to perform more accurate tracking control, and at the same time, it is possible to reproduce at a speed different from that during recording. It is an object of the present invention to provide a rotating head type video signal reproducing device.

An example in which an embodiment of the present invention is applied to a helical scan type video tape recorder will be described with reference to FIGS. 1 to 3. Note that this embodiment also uses the same arrangement of the heads as shown in FIG. 1 described above. In Fig. 1, T is a magnetic tape DRM is a drum that guides the tape T, CAP is a capstan roller that works together with a pinch roller PIN to convey the tape T in the direction of arrow B, and GD is a guide guide for the tape T. The pin, Ha, has a positive azimuth and is the main head used for recording and normal playback.H1 and _{H2 have} a negative azimuth, and are auxiliary heads used for detecting tracking errors and playing back images during still and slow motion. , arrow A indicates the direction of rotation of the head, and arrow α indicates the direction of travel of the head.

FIG. 2 is a schematic diagram showing another specific example of the head configuration in this embodiment. In FIG. 2, the main head is indicated by Ha2 and Hb2 to distinguish the conventional head, and the auxiliary head is indicated by _h12 .

In the figure, Ha2 has positive azimuth,
Main head used for recording and normal playback. _h12 is an auxiliary head that has a negative azimuth and is used for detecting mistracking and reproducing images during still and slow motion, and the arrow β indicates the running direction of the head. The width W _A of the main head Ha is the track pitch P
It shall be wider than . The width _w12 of the auxiliary head _h12 is narrower than the track pitch P, and the width w12 of the auxiliary head h12 is narrower than the track pitch P.
The center line of Ha2 in the running direction and the center line of auxiliary head _h12 in the running direction are shifted by Δl. △l is
Set W _A /2>(W ₁₂ /2) + △l. The distance in the traveling direction between the gap centers of the main head Ha2 and the auxiliary head _h12 is a constant value for 1H.
In this example, it is set to 1H. These two heads Ha2 and _h12 are fixed in the above-mentioned positional relationship on a diaphragm (not shown) using a bimorph oscillator. The other negative azimuth head that performs recording may have the same configuration as the positive azimuth head described above, or it may be a conventional single-rotation head, but in this example, it is a single-rotation head.
Let it be Hb2. The width Wb of the head Hb2 is wider than the track pitch P.

FIG. 3 is a block diagram of the reproduction circuit of the embodiment of FIG. 2.

In the figure, 20, 21 and 22 are heads.
₂₃ and 24 are switch circuits that are switched depending on the reproduction mode, 25 and 26 are amplitude detection circuits, and 27 and 28 are low-pass filters that obtain DC voltage. , 29 is a peak hold circuit that holds the peak of the reproduced output, 30 is an adder, 31 is a differential amplifier circuit, 32 is a comparator, 33 is a bimorph drive circuit, 34 is a bimorph oscillator,
35 is a changeover switch for changing the head to be used; 36
37 is a luminance signal reproduction processing circuit, 37 is a color signal reproduction processing circuit, 38 is a 1H delay circuit for time correction, 39
is a speed control circuit that controls the rotation speed of the capstan roller CAP (FIG. 1) using a signal from the reproduction mode control line ML.

When reproducing a magnetic tape recorded azimuthally using the circuit shown in the figure at the same running speed as when recording, the outputs obtained from the main heads Ha2 and Hb2 are applied to amplifiers 21 and 22 and amplified to an appropriate level. Thereafter, the signal is guided to a changeover switch 35 via switch circuits 23 and 24 which are switched by a signal on the reproduction mode control line ML. Brightness regeneration processing circuit 36
The signal then passes through the color reproduction processing circuit 37 and becomes a reproduced video signal. The output from the main head Ha2 is applied to an amplifier 21, branched off, guided to an amplitude detection circuit 25 for detection, and then a peak hold circuit 29 which holds the maximum value of the envelope for a very long time. and is held. Further, the envelope detected at 25 is converted into a DC voltage by a low-pass filter 27 that follows the output of the main head Ha2. The output of the auxiliary head _h12 is sent to the amplitude detector 26.
is detected by the auxiliary head by the low-pass filter 28.
The DC voltage follows the output of _h12 . main head
The voltages corresponding to the outputs of Ha2 and the auxiliary head _h12 are added by the adding circuit 30 and then compared with the peak-held voltage by the comparator 32, and the output voltage of the adding circuit 30 is compared to this peak-held voltage. The direction of tracking deviation is detected depending on whether the difference is large or small. Further, the voltage corresponding to the output of the main head Ha2 passes through the peak hold voltage and the differential amplifier circuit 31 to obtain a voltage corresponding to the difference between these outputs, thereby detecting the amount of tracking deviation. In FIG. 5, the track pitch is P, the track width of the main head Ha2 is W _A , the track width of the auxiliary head h ₁₂ is W ₁₂ ,
The peak hold circuit 29, the adder 30, and the differential amplifier circuit 3 in _FIG .
FIG. 1 is a diagram showing the relationship between each output voltage of No. 1 and the amount of tracking deviation. As shown in the figure, when the tracking deviates, the output level of the differential amplifier circuit 31 increases in accordance with the amount of deviation, and
It can be seen that the output level becomes higher or lower than the output level of the peak hold circuit 29 depending on the direction of the tracking shift. These signals are sent to the bimorph drive circuit 3.
3 to move the bimorph oscillator 34 so that the main head Ha2 accurately traces the track. Next, in the case of still playback, the control line ML becomes high level, the speed control circuit 39 stops transporting the tape T, and the switch circuit 2
3 and 24 are switched to the broken line side, and the main head Ha2 is separated from the video signal reproduction processing circuit.

On the other hand, the auxiliary head _h12 is connected to a video signal reproduction processing circuit by a switch circuit 23 and is used for reproducing the video signal. Also, the auxiliary head
The output from _h12 is disconnected from the tracking control system, and the main head Ha2 is fixed at the same position as during recording. However, since the auxiliary head _h12 lags the main head Ha2 by 1H, the main head Hb
2 and a time lag occurs. Therefore, the main head
The output of Hb2 is guided by the switch circuit 24 to a 1H delay circuit 38, and is delayed by 1H. As a result, the main head Hb2 and the auxiliary head _h12
Since the outputs of the main head Hb2 and the auxiliary head _H12 have the same azimuth, it is possible to reproduce stills from the same field.

FIG. 4 is a block diagram showing another embodiment of the reproducing circuit having the head configuration shown in FIG. 2. Ha
3 is a main head which has a positive azimuth and is used for recording and normal playback, and _h13 is an auxiliary head which has a negative azimuth and is used for detecting mistracking and reproducing video during still and slow motion. The auxiliary head _h13 is attached to the main head Ha3 in a configuration similar to that shown in FIG. Hb3 has a negative azimuth and is a main head used for recording and reproduction, and _h23 has a positive azimuth and is an auxiliary head for detecting mistracking. Auxiliary head
h ₂₃ is the main head Ha3, similar to h ₁₂ and Ha2 in Figure 2.
It is installed in a position 1H behind.

In the figure, 39, 40, 41, and 42 are
₄₃ and ₄₄ are switch circuits that switch between recording mode and playback mode; ₄₅ is a changeover switch that switches the head in use; 46 and 47 are amplitude detection circuits, 48 and 49 are low-pass filters that obtain DC voltage, 50 is a peak hold circuit that holds the peak of the reproduced output, 51 is an adder, 52 is a differential amplifier circuit, 53 is a comparator, and 54 and 55 is a bimorph resonator with a head attached; 56 is a bimorph drive circuit that displaces the bimorph by an amount corresponding to the output from the differential amplifier circuit 52 using the signal from the comparator 53 and the signal corresponding to the reproduction mode channel; 57 5 is a luminance signal reproduction processing circuit; 58 is a color signal reproduction processing circuit;
9 is a 1H delay circuit, and 60 is a speed control circuit similar to 39 in FIG.

When reproducing a magnetic tape recorded azimuthally using the circuit shown in the figure at the same running speed as when recording, the outputs obtained from the main heads Ha3 and Hb3 are applied to amplifiers 40 and 41 and amplified to an appropriate level. Thereafter, the signal is guided to a changeover switch 45 via switch circuits 43 and 44 which are switched depending on the recording/reproduction mode. The signal then passes through a luminance reproduction processing circuit 57 and a color signal reproduction processing circuit 58 to become a reproduced video signal.

In addition, the outputs from the main heads Ha3 and Hb3 are branched after passing through a changeover switch 45, and are branched off to an amplitude detection circuit 47.
guided by. The wave is detected by the detection circuit 47, and then the maximum value of the envelope is held by the peak hold circuit 50 for an extremely long time.

Furthermore, the detection output of the detection circuit 47 becomes a DC voltage that follows the outputs of the main heads Ha3 and Hb3 by the low-pass filter 49. The outputs of the auxiliary heads h ₁₃ and h ₂₃ are also detected by the amplitude detection circuit 46, and
8, the DC voltage follows the outputs of the auxiliary heads h ₁₃ and h ₂₃ . The DC voltages corresponding to the outputs of the main heads Ha3, Hb3 and the auxiliary heads _h13 , _h23 are added by an adder circuit 51, and then compared with the output voltage of the peak hold circuit 50 by a comparator 53,
Depending on whether the output voltage of the adder circuit 51 is larger or smaller than the output voltage of the peak hold circuit 50, the direction of the racking deviation is detected. Furthermore, the main head
The DC voltage according to the outputs of Ha3 and Hb3 is input to one input terminal of the differential amplifier circuit 52, and the output of the peak hold circuit 50 is input to the other input terminal, and an output according to the input voltage difference is input. voltage can be obtained. The output voltage means the amount of tracking deviation. The bimorph drive circuit 56 uses the outputs of the comparator 53 and the differential amplifier 52 to drive the bimorph oscillators 54 and 5 so that the main heads Ha3 and Hb3 accurately trace the recording track during normal playback.
Control 5.

Next, in the case of still mode, the signal level of the mode control signal line ML becomes high level, the switch circuits 43 and 44 are switched to the position shown by the broken line, and the auxiliary head _h13 is connected to the video signal reproduction processing circuits 57 and 58. , used for reproducing video signals. main head
The output of Ha3 is used only for tracking control. In the mistracking control systems 46 to 53, since the signal level of the mode control signal line ML is high, the auxiliary head _h13 can correctly trace the recording track by reversing the driving direction of the bimorph with respect to the normal playback mode. In order to work as if
The auxiliary head _h13 traces precisely on the negative azimuth track.

On the other hand, the signal from the main head Hb3 is transmitted to the switch circuit 4.
4 to the 1H delay circuit 59, and is delayed by 1H. The outputs of the auxiliary head _h13 and the main head Hb3 are aligned in time, making it possible to reproduce frames from the same field, so-called "one field still".

In the embodiments of FIGS. 2, 3, and 4,
Although only still and slow playback has been described, various modifications can be made to playback at a speed different from the playback speed, such as double speed, within the scope of the claims of the present invention.

As explained in detail in the embodiments above, in the rotary head type video signal reproducing apparatus of the present invention, the reproducing head scans according to the curvature of the recorded track, regardless of whether it is normal playback or special playback, so that high-quality video is always produced. This method is effective in a rotating head type video signal reproducing apparatus that performs high-density azimuth recording. Furthermore, since it is possible to select a head with an effective azimuth angle, it is expected that image quality will be improved in various modes, especially when reproducing images.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the configuration of an auxiliary head in a conventional two-head helical VTR, FIG. 3 is a block diagram showing an example of the configuration of a reproducing circuit in the device according to FIG. 2, and FIG. , FIG. 3 is a schematic diagram showing the track and head trajectory during still playback in the apparatus shown in FIG. 2, FIG.
FIG. 4 is a block diagram showing another example of the structure of the reproducing circuit in the illustrated apparatus, and FIG. 5 shows the relationship between the level of each part of FIG. 3 and the tracking error. Add to show.
It is. Ha2, Hb2, Ha3, Hb3 are main heads, _h12 , _h13 , _h23 are auxiliary heads, 43, 44 are switch circuits, 45 is a changeover switch, 50 is a peak hold circuit, 51 is an adder, 52 is a differential 53 is a comparator, 54 and 55 are bimorph oscillators, and 57 is a bimorph drive circuit.

Claims (1)

[Scope of Claims] 1. A first reproduction mode in which a video signal on a strip-shaped recording medium in which recording tracks with different azimuth angles are alternately formed at a predetermined track pitch is reproduced at substantially the same speed as the recording speed; a rotating main head having a track width wider than the track pitch; and a rotating main head having a track width narrower than the track pitch, the rotating main head having a track width narrower than the track pitch, a rotary auxiliary head having an azimuth angle different from that of the main head; the rotary auxiliary head is arranged close to the rotary main head so that they always have a predetermined positional relationship; Shifting the main rotary head in the track width direction from the center of the track, and making the amount of shift within 1/2 of the difference in track width between the main rotary head and the auxiliary rotary head; video signal reproducing means for reproducing the video signal using the rotary main head in the first reproducing mode, and reproducing the video signal using at least the rotary auxiliary head in the second mode; The tracking control of the rotary main head is performed by detecting the amount of tracking deviation using the output of the rotary main head, and detecting the direction of tracking deviation using the output of the rotary main head and the output of the rotation auxiliary head. What is claimed is: 1. A rotary head type video signal reproducing apparatus, comprising tracking control means for performing the following steps.