JPS63168869A - Rotary head type recording device - Google Patents

Abstract

PURPOSE:To realize the phase control with high accuracy by controlling the position of a rotary head based on the phase difference detected by a phase comparing means. CONSTITUTION:A phase comparing means 22a compares the phase of a signal (c) obtained by dividing the output of a phase detector 16 which detects the rotational phase of a rotary head with the phase of a dividing signal of the vertical synchronizing signal obtained from a video signal (b). A waveform shaping circuit 18b produces a reference signal (e) having the same period as the output of the detector 16. A phase comparing means 22b compares the signal (e) with the output (a) of the detector 16. Then the rotational phase of the rotary head is controlled based on a difference of phases detected by both means 22a and 22b. Thus it is possible to control the phase for each revolution regardless of the rotational frequency of a drum and to improve the phase control accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for recording video signals using a one-rotation head, and particularly to control of the rotational phase of the rotary head in this apparatus.

[Prior Art] This issue 11 relates to a rotary head type recording device, and the following explanation will be given using a video tape recorder (VTR) as an example of this type of device.

In recent years, VTRs have been trending toward smaller size, lighter weight, and lower cost, but the diameter of the drum has remained the same as before, four heads are placed orthogonally on the drum, and the four heads are used selectively. There is a VTR (hereinafter referred to as a small-diameter drum VTR) that performs recording and reproduction.

Fig. 2 is a plan view from above of the tape running system centered on the drum part of the VTR using the small diameter drum, l is the small diameter drum, 2 is a tape guide post, 3 is the tape, and 4 is the rotation. Pulse generator (PG) for phase detection
, 5A, 5B.

5C and 5D are heads.

In Fig. 2, the tape is wrapped around a small diameter drum l at an angle of 270', and each head is moved to head 5A, head 5B, head 5C, head 5 every time this small diameter drum l rotates nine times.
By switching to D, each head records one field's worth of video signals.

By the way, 2 Hetsu 1 ~ Helical scan type VTR
The rotational speed of a tram motor with a normal diameter used for recording NTSC video signals is 180
0 rpm (30H2), and a frequency generator (hereinafter referred to as FG) is installed as a speed detector on the drum as a rotating body.
By keeping the output frequency constant, IAgg is used so that the drum rotates at a constant speed.

A tape running system for a drum having a normal diameter is shown in FIG. In Figure 3, 2' is post, 4' is PG, SR,
SL is the head, 6 is the drum and the second [same symbol as A is the same -
or a corresponding portion.

In FIG. 3, the heads SR are opposed to each other.

A drum with a head 5L rotates at 1800 rpm, and P is used as a rotational phase detector of the tram 6, which is a rotating body.
There is a G4'. The diameters of the drums shown in FIGS. 2 and 3 are made different so that the relative speed of each head with respect to the tape is the same.

When recording an NTSC video signal on the tram 6, which has four normal diameters, the signal of PG4' becomes a 30Hz signal, and since the video signal is input at 60H2, the video signal Vertical synchronization signal (below) -V, 5YNC
By comparing the phase with the frequency divided into stations, the rotational phase of the drum can be controlled. A timing chart at this time is shown in the fourth UA. In Figure 4, (a) is PG4
', (b) shows the video signal, and (c) shows the output timing of a phase comparator (not shown).

As is clear from FIG. 4, the signal of PG4' (a) which is outputted one pulse per one rotation of the drum, and the signal obtained by frequency-dividing V and 5YNC of the input video signal (b) are not shown. The output timing (c) of the phase comparator when the phase is compared with the phase comparator is 30Hz, and this output, that is, PC (
The tram motor is controlled by the output signal of the phase comparator.

NT by a VTR using a small diameter drum in Figure 2.
Considering the case of recording and reproducing video signals using the SC system, the small diameter drum 1 rotates 45 times per second. Then, every time this small diameter tram l rotates by %, the heads 5A, 5
60) IZ by switching B, 5C, 5D to 1 trouble
V, 5YNC of 1 field each head 5A, 5B
, 5C.

It becomes possible to switch to 5D and record.

In addition, for the small diameter tram 1, a timing chart similar to the timing chart for the drum 6 having a normal diameter is used as a position detector for the small diameter tram 1 as a rotating body. .

Shown in (c). In FIG. 5, (a) is a signal from the PC 4, (b) is a video signal, and (c) is a signal obtained by dividing the signal (a) by h.

5th r? 1, the signal (A) of PC4 in the small diameter tram 1 is 45H2. Also, since the input video signal (b) (7) V, 5YNC is 'j; The output timing of the illustrated phase comparator is 15H2.

[Problems to be Solved by the Invention] In the conventional VTR having a small-diameter drum as described above, when applying phase control to the drum, the 45H2 PG signal is tail-divided, and the 60H2 V, 5YNC signal is used. Is this P
The output timing of C is 15H2. Therefore, in the case of a drum with a normal diameter, the rotational phase can only be determined with a period twice the output signal of the PC, and if the drum has a small diameter,
Since the position can be controlled only once during rotation, control accuracy deteriorates. Therefore, the V recorded on the tape
, 5YNC may be out of alignment with the track, causing unevenness in the tape pattern, and when this tape is played back on another VTR, there is a problem of negative effects such as skew distortion.

The present invention was made in view of the problems of the prior art, and an object of the present invention is to provide a recording device that can perform highly accurate control using a wide circuit in phase control of a rotary spatula that rotates at any period. do.

[Means for Solving the Problems] In order to achieve the above object, the rotary head type recording device according to this invention uses a signal obtained by frequency-dividing the output of a phase detector that detects the rotational phase of the rotary head, and means for comparing the phase of a vertical synchronization signal obtained from a video signal with a frequency-divided signal; generating a reference signal having the same period as the output of the phase detector; and determining the phase of the reference signal and the output of the phase detector; The rotational phase of the rotary head is controlled based on the phase difference detected by each of the phase comparison means.

[Function] With the above configuration, the phase of the rotary head in the present invention can be controlled every rotation with a simple circuit configuration, and it has become possible to perform phase control as high as 11 degrees.

[Embodiment] FIG. 1 is a circuit block diagram schematically showing main parts in an embodiment of the present invention. In FIG. 1, 11 is a frequency comparator, 22a and 22b are phase comparators, 12 is a synchronous separation circuit, 13 is an h frequency divider, 14 is a filter, 15 is a motor drive circuit, and 16 is a 45H2 reference pulse generator. pulse oscillator.

17a and 17b are preamplifiers, 18a and 18b are waveform shaping circuits, 19 is a frequency-voltage converter (hereinafter referred to as an F-V converter), 20 is a station frequency divider, and 21 is an adder. Further, the same reference numerals as in FIG. 2 indicate the same or corresponding parts.

FIG. 5 is a timing chart of FIG. 1, where the signals (A), (B), and (C) are as explained above, (D) is the output timing of the phase comparator 22a, and (E) is the timing chart of FIG. Output signal of pulse oscillator 16.

(f) shows the output timing of the phase comparator 22b.

:t'S1 In the figure, as the small diameter drum l rotates, a speed detection signal having a frequency corresponding to the rotational speed is output from an unillustrated FG provided on the small diameter tram l, and the waveform is shaped through the preamplifier 17a. circuit 18a
A pulse waveform (hereinafter referred to as FG pulse) is output. This FG pulse is compared with a reference pulse (G) from a pulse oscillator (not shown) in a frequency comparator 11, and an output having a frequency corresponding to the frequency difference from this frequency comparator 11 is sent to an F-V converter 19. and is converted into voltage by this F-V converter 19.

The output voltage of this F-V converter 19 is supplied to an adder 21 as a rotation speed control signal.

On the other hand, the signal from FG4 mentioned above is a signal whose period is one revolution of the small diameter drum l, and this signal from FG4 is also amplified by the preamplifier 17b and is then amplified by the waveform shaping circuit 18.
b becomes a 45H2 pulse signal. This 45H2
The pulse signal is divided by the local frequency divider 20 to 15
This becomes an H2 pulse signal. In addition, the sync separation circuit 12 extracts V, 5 from the video signal (b) to be recorded.
YNC is separated and the extracted 60Hz V, 5Y
The frequency of NC is divided into a 15H2 signal by the % frequency divider 13, and the phases of this 15Hz V, 5YNC and the 15H2 signal obtained by dividing the frequency of FG4 mentioned earlier are compared by the phase comparator 22a. Therefore, the C1 first phase control voltage is obtained.

On the other hand, 45 output from the waveform shaping circuit 18b described above
The H2 pulse signal is supplied to the phase comparator 22b, and its phase is compared with the 45H2 reference signal supplied from the pulse oscillator 16. The output signal of this phase comparator 22b is input to the adder 21 as a second phase comparison voltage.

and one or more speed control voltages and a first . A second phase control voltage is added by an adder 21, a high-frequency component of the output of the adder 21 is removed by a filter 14, and the output of this filter 14 is applied to a motor drive circuit 15.
controls the motors of the

Further, since the addition ratio of the above three types of limiting a voltages can be selected by the adder 21 depending on its input resistance, the optimum voltage ratio can be selected.

If controlled by the circuit configuration as described above, the small diameter drum 1 will be controlled at 1 as shown at points a, b, c, and d in FIG.
Position control is performed every rotation, compared to the conventional example.
The accuracy of phase control can be further improved.

It should be noted that this embodiment is shown for recording, but for playback,
Since there is no video @ signal to be input, the phase of the rotating drum can be controlled by the output of the phase comparator 22b.Also, if you want to adjust the recording height of V and 5YNC chibuts during recording, use the pulse The phase of the output pulse of the oscillator 16 may be adjusted.

[Effects of the Invention] As explained above, the present invention provides a phase difference between the frequency-divided signal of the output of the phase detector that detects the rotational phase of the rotary head and the frequency-divided signal of the vertical synchronization signal obtained from the video signal. and means for generating a reference signal having the same period as the output of the phase detector and comparing the phase of this reference signal with the output of the phase detector, and each of the phase comparison means Since the position of the rotary head is controlled based on the detected phase difference, it is possible to control the phase of each rotation of the drum at any rotation speed, which has the effect of improving the accuracy of phase control. .

[Brief explanation of the drawing]

Fig. 1 is a circuit block diagram showing a schematic configuration of the main parts of a VTR that is an embodiment of the present invention, and Fig. 2 is a diagram showing a tape running system centered on the drum section of a VTR using a small diameter drum, seen from the 1 side. Figure 3 is a top view of the tape running system centered on the drum part of a VTR using a drum with a normal diameter, Figure 4 is a timing chart of each part of Figure JS3, Figure 5 1 is a timing chart of each part in FIGS. 1 and 2. FIG. In the figure. l: Small diameter drum 11: Frequency comparator 12 Two-synchronous separation circuit 13: % frequency divider 14: Filter 15: Motor drive circuit 16: Pulse oscillator 17a, 17b: Brianb 18a, 18b
: Waveform shaping circuit 19: F-V converter 20: Station frequency divider 21: Adder 22a, 22b: Phase comparator agent Patent attorney 1) Haru Kitatake Figure 1 Figure 5

Claims (1)

[Claims] In a device that records video signals using a rotating head, the phase of a signal obtained by frequency-dividing the output of a phase detector that detects the rotational phase of the rotating head and a frequency-divided signal of a vertical synchronization signal obtained from the video signal. and means for generating a reference signal having the same period as the output of the phase detector and comparing the phase of this reference signal with the output of the phase detector, and each of the phase comparison means A rotary head type recording device characterized in that a rotational phase of a rotary head is controlled based on a detected phase difference.