JPH0315270B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary head tape recorder for reproducing information signals such as video signals from a magnetic tape using a rotary head.

The present invention automatically performs so-called tracking control to match a recording track and a reproduction scanning locus. In this case, by using the output of the rotary head to detect tracking errors, a tracking error signal with a good S/N ratio can be obtained. Further, according to the present invention, by using a tape guide drum having a diameter that is 2/3 that of the tape guide drum of a conventional rotary two-head type tape recorder, the rotary tape recorder is compatible with the conventional rotary two-head tape recorder. A head type tape recorder can be realized.

An embodiment of the present invention will be described below.
In FIG. 1, reference numerals 1A, 1B, 1C, and 1D designate rotary heads arranged at the same height with angular spacing of 90 DEG from each other, and 2 designates a tape guide drum. The tape guide drum 2 consists of a rotating upper drum and a fixed lower drum, and rotating heads 1A to 1D are arranged on the lower surface of the upper drum, and a rotating disk is arranged between the fixed upper drum and the lower drum. , rotary heads 1A to 1D are arranged on this rotary disk. In addition, rotating heads 1A to 1D
Among them, the angles formed by the caps are different between one pair and the other pair, which face each other at an angular interval of 180°. In other words, rotating heads 1A to 1D
If a line perpendicular to the scanning direction of is taken as a reference, the angle formed by the gap of the rotary heads 1A, 1C has a deviation of +α (for example, α=7°) with respect to this line, and on the other hand,
The angles formed by the gaps of the rotary heads 1B and 1D are made to have a deviation of 1 α. in this way,
By varying the angles formed by the gaps, crosstalk components from adjacent tracks can be suppressed during playback. Such a recording method is called inclined azimuth recording.

The magnetic tape 3 is wrapped around the circumferential surface of the tape guide drum 2 at a wrapping angle of 270° or slightly larger.
is passed diagonally. By setting the diameter of the tape guide drum 2 to 2/3 of the diameter of a conventional two-head rotating VTR, the length of sliding contact between the magnetic tape 3 and the rotating heads 1A to 1D becomes equal, and the tape guide The inclination of the magnetic tape 3 on the circumferential surface of the drum 2 is the same as before, and the rotation speed of the rotary heads 1A to 1D is set to 45 revolutions per second so that the above-mentioned sliding contact period is 1 fill as before. If the scanning speed of the magnetic tape 3 is also the same as that of the conventional one, it is possible to obtain a recording pattern exactly the same as that of the conventional rotary two-head type VTR.

As shown in FIG. 2A, the rotating heads 1A, 1D, 1 are connected to the magnetic tape 3 running in the direction of the arrow.
C, 1B slide in this order, and the scanning loci 4A, 4D, 4C, 4B diagonally move from the bottom to the top of the magnetic tape 3.
are drawn in sequence. When recording color video signals,
One of the recording signals consisting of an FM-modulated luminance signal and a carrier color signal frequency-converted to a low carrier frequency.
Each field is supplied to the rotary head in the order 1A, 1B, 1C, 1D. In FIG. 2A, the thick solid line indicates the locus of the section in which the recording signal is supplied. The pitch P of the scanning locus of the rotating heads 1A to 1D is 3 times the magnetic tape in 1/180 second.
corresponds to the amount of movement of the rotary head 1A~
The track width W of 1D is (W=3P). Therefore, as shown in FIG. 2B, the scanning trajectories 4A to 4D are adjusted so that the track pitch is also W.
Tracks R _A to R _D corresponding to these are formed. This track pattern is exactly the same as that of a conventional rotating two-head type VTR.

As mentioned above, among the rotary heads 1A to 1D, the angle formed by the gap in one pair of rotary heads 1A is
1C and the other pair of rotating heads 1B and 1D, adjacent tracks in the track pattern shown in FIG. 2B are formed by recording heads with different gap angles. It is. In addition, the low-frequency conversion color signal in the recorded signal is
Phase control (the phase of one of the adjacent tracks is
Invert every 1H (1 horizontal period), or shift the phase of both by 90° in the opposite direction every 1H)
has been done.

In this way, the recording signal can be transferred to the conventional rotary two-head type.
If it is the same as that of a VTR, it is possible to record exactly the same as before. In other words, in one embodiment of the present invention, not only the magnetic tape recorded as described above but also the conventional rotary two-head type VTR can be used.
It is also possible to reproduce a magnetic tape recorded by this embodiment, and conversely, a magnetic tape recorded by this embodiment can be reproduced by a conventional rotary two-head VTR.

However, the present invention is not limited to the case where it is compatible with conventional devices, but may be applied to cases where, for example, an audio signal is interpolated into a recorded video signal by band division or the like.

Now, the case of reproducing the magnetic tape 3 on which a track pattern as shown in FIG. 2B is formed will be explained. As shown in FIG.
Each output of A to 1D is supplied to reproducing amplifiers 5A to 5D via a rotary transformer (not shown). The outputs S _A to S _D of the reproduction amplifiers 5A to 5D are supplied to each input terminal a to d of the switch circuit 6, and
It is supplied to each of envelope detection circuits 8A to 8D. The switch circuit 6 sequentially takes out the outputs of the reproduction amplifiers 5A to 5D for each field and guides them to the reproduction output terminal 7. This playback output terminal 7
The reproduced signal appearing in the image is divided into a modulated luminance signal and a low-frequency conversion color signal, and these are supplied to separate processing systems to obtain a reproduced color video signal.

In addition, the detection outputs E _A to E _D formed by the envelope detection circuits 8A to 8D are sent to the switch circuit 9.
and input terminals a to d of the switch circuit 10. The outputs of the switch circuits 9 and 10 are input to the level comparison circuit 11,
The output of this level comparison circuit 11 is the time constant circuit 13
The signal is taken out as a tracking control signal to the terminal 14 via. The level comparison circuit 11 has a terminal 12
For example, the level comparison operation is performed only in the high level section by the control pulse Pt from the control pulse Pt. The switch circuits 9 and 10 are controlled so that the input terminals a to d are sequentially connected to the output terminal in one field period. A switch circuit 6 which is alternately switched at these field cycles,
The connection state of 9 and 10 is controlled in a constant positional relationship with the scanning of the rotary heads 1A to 1D. For this reason, a magnetic phase detection means (not shown) is provided to detect the rotational phase of the rotary heads 1A to 1D, and the detection output forms pulses for controlling the above-mentioned switch circuits 6, 9, and 10. .

Here, in a state where there is no tracking error in which the center of the track and the center of the reproduction scanning locus of the rotary head coincide, the output of the reproduction amplifiers 5A to 5D is
S _A to S _D are as shown in FIG. 4A. To explain using FIGS. 2A and 2B, first, the rotary head 1A scans the track R _A to obtain a reproduced signal S _A of normal amplitude as shown in FIG. 4A. The rotary head 1D comes into contact with the magnetic tape 1/180 seconds later than the rotary head 1A, and draws a trajectory centered on 4D. In this case, rotating head 1
Since 1/3 of the track width W of D overlaps with track R _B , the amplitude of the reproduced signal S _D becomes 1/3 of the normal one. Similarly, the rotary head 1C comes into contact with the magnetic tape 1/180 second behind the rotary head 1D, and
A trajectory centered at C is drawn, and 1/3 of the track width W of the rotary head 1C overlaps with the track R _A , so the amplitude of the reproduced signal S _C becomes 1/3 of the normal one.
Furthermore, as the rotary head 1A separates from the magnetic tape 3, the rotary head 1B comes into contact with the magnetic tape 3,
Draw a trajectory centered on 4B, and find the track width W
will match track R _B. Therefore, among the reproduced outputs shown in FIG. Thereafter, operations similar to those described above are repeated.

Further, detection voltages E _A -ED shown in FIG. 4B appear from envelope detection circuits 8A- _8D , respectively, corresponding to reproduced signals S _A -S _D shown in FIG. 4A. These detection voltages E _A to E _D are applied to switch circuits 9 and 10.
is supplied to The switch circuits 9 and 10 are both 1
The input terminals are switched in the order of a, b, c, and d for each field, and the switching phase of the switch circuit 10 is 1 with respect to the switch circuit 9.
It is said that the field was delayed. In FIG. 4B, the symbol F _AD indicates one field period in which the input terminal a and the output terminal are connected in the switch circuit 9, and the input terminal d and the output terminal in the switch circuit 10 are connected. F _BA , F _CB , and F _DC each represent a field period indicating the connection state of the switch circuits 9 and 10.

During each of these field periods, the detected voltages passed through the switch circuits 9 and 10 are supplied to the level comparison circuit 11, and the level difference therebetween is detected. In this case, the control pulse Pt shown in FIG.
The level comparison operation is performed only in the detection sections T _AD , T _BA , T _CB , and T _DC where T is at a high level. _{In other words , each _ _ _ _ _ _ _ _ _ _ _} A level comparison operation is performed in the detection section, and detection voltages E _AD , E _BA , E _CB , and E _DC are generated. These detected voltages are averaged by a time constant circuit 13 and outputted to an output terminal 14 as a tracking control signal. This tracking control signal is supplied to the servo circuit.

As mentioned above, if there is no tracking error, the detection voltages of E _AD , E _BA , E _CB , and E _DC are all 0.
becomes. Here, as shown in FIG. 5A, if the tracking is correct, the scanning locus center 4A~
The rotating head 1A is centered around 4A' to 4D' which are shifted in the direction opposite to the traveling direction of the magnetic tape 3 with respect to 4D.
.about.1D scans the track, the detected voltages _{E.sub.A.about.ED} from the envelope detection circuits _8A.about.8D become as shown in FIG. 5B. In FIG. 5B, the waveform indicated by the broken line represents the detected voltage in the case of correct tracking. For example, in the detection section T _DC , the area where the rotating head 1D overlaps with tracks of the same azimuth widens, the detected voltage E _D of one side becomes larger, and the area where the rotating head 1C overlaps with tracks of the same azimuth becomes narrower, and the area where the rotating head 1D overlaps with tracks of the same azimuth becomes smaller, and the detected voltage of the other side becomes larger. Voltage E _C becomes smaller and a positive detection voltage E _DC is generated. Similarly, positive detection voltages E _AD , E _BA , and E _CB are generated in other detection sections T _AD , T _BA , and T _CB , respectively. The level of this detection voltage is proportional to the amount of tracking error.

In addition, in FIG. 6A, if the center of the scanning locus deviates from the correct one in the same direction as the traveling direction of the magnetic tape 3, as shown by 4A' to 4D',
Detection voltages E _{A -ED} shown in FIG. 6B are generated. At this time, detection voltages -E _AD , -E _BA , -E _CB , -E _DC having negative polarity and levels proportional to the amount of tracking error are obtained in each detection period.

In this way, a negative detection voltage is generated when the direction of the tracking error is the same as the tape traveling direction, and a positive detection voltage is generated when the direction is opposite, so tracking control may be performed to cancel this tracking error. FIG. 7 shows an example of a servo circuit when the drum motor 15 for rotating the rotary heads 1A to 1D and the capstan motor 16 for rotating the capstan are configured as DC motors. The drum motor 15 receives an error signal from the drum speed servo circuit 17 and an error signal from the drum phase servo circuit 18 through a synthesizer 19.
is supplied to the motor drive circuit 20 via the motor drive circuit 20, thereby rotating at a constant speed and a predetermined phase. Reference numeral 21 denotes a detection coil for detecting the rotational phase of the rotary heads 1A to 1D. For example, two magnetic pieces spaced apart by 270 degrees and magnetized in opposite directions rotate together with the rotary head. coil 2
1, a detection signal that changes from negative to positive is generated alternately when it changes from positive to negative, and the detection circuit 22 distinguishes this difference, and the two types of detected signals are sent to the set and reset terminals of the flip-flop 23, respectively. A pulse is provided. The output of the flip-flop 23 is supplied to a drum speed servo circuit 17 and a drum phase servo circuit 18, respectively. Although not shown, the output of the flip-flop 23 is used as a switching pulse for switching the reproduction output. In the drum speed servo circuit 17, a speed error of the drum motor 15 is detected using the detection signal taken out by the detection coil 21 during both recording and reproduction, and the drum motor 15 is caused to rotate at a constant speed. Ru. Further, a servo reference signal is supplied to a terminal indicated by 24. At the time of recording,
During playback, the vertical synchronization signal separated from the video signal is generated by frequency-dividing the output of the reference oscillator.
A Hz signal is used as the servo reference signal. A phase error in the drum motor 15 is detected using the servo reference signal and the detection signal, and the drum motor 15 is caused to rotate at a predetermined rotational phase.

The capstan motor 16 is also provided with a speed servo circuit and a phase servo circuit, respectively. A detection coil 25 is provided to magnetically detect the rotation of the capstan motor 16, and the output of the detection coil 25 is used to rotate the capstan motor 16 at a constant speed. That is, the detection signal from the detection coil 25 is supplied to the waveform shaping circuit 26, which converts the detection signal into a detection pulse having both rising and falling points at the zero-crossing point. ) 27 and the slope forming circuit 28, and the gate pulse generated by supplying the above-mentioned detection pulse to the gate pulse generation circuit 30 is supplied to the gate circuit 29, and the gate pulse is The output of the circuit 29 is passed through the hold circuit 31 to the motor drive circuit 32.
is supplied to

The monomulti 27 described above is for delaying the detection pulse, and the amount of delay in this case is controlled by the error signal from the phase servo circuit. During recording, a detection signal corresponding to the rotational phase of the flywheel of the capstan is applied to the terminal 34,
A gate pulse is supplied to the gate circuit 37 via the monomulti 35 and the slope forming circuit 36, and a gate pulse generated by the gate pulse generation circuit 39 from the servo reference signal is supplied to the gate circuit 37, and the output of this gate circuit 37 is held. It is applied to the delay amount control terminal of the monomulti 27 via the circuit 38.
The phase of the gate pulse generated by the gate pulse generation circuit 39 is determined by the control voltage supplied via the switch 33 which is switched during recording and reproduction. During recording, a predetermined voltage is applied to generate a gate pulse of a predetermined phase, and during reproduction, a tracking control signal is supplied from the terminal 14. In this case, the tracking control signal changes positive and negative around the voltage at the time of recording.

FIG. 8 shows another example of the servo circuit. In this example, one AC motor synchronized with the commercial power supply is used to drive both the rotary head and the capstan, and the brake is applied by an error signal from the drum phase servo circuit. Reference numerals 21a and 21b indicate detection coils arranged at an angular interval of, for example, 270 degrees, and a detection signal is generated from the detection coils 21a and 21b each time a magnetic piece rotating together with the rotating head approaches.
This detection signal is supplied to monomultis 41a, 41b, and 41c via amplifiers 40a and 40b.
The outputs of the monomultis 41a and 41b are supplied to the flip-flop 42, and a switching pulse is generated at the terminal 43. In addition, the output of the monomulti 41c is passed through the monomulti 44 to the slave forming circuit 45.
The ramp wave appearing at its output is supplied to the gate circuit 46. A gate pulse generated by a gate pulse generation circuit 48 is supplied to the gate circuit 46 from a vertical synchronizing signal applied to a terminal 47, and its output is supplied to the recording side terminal of the switch 50 via a hold circuit 49. . switch 5
The zero output is applied to the brake coil 52 via the amplifier 51. During playback, switch circuit 5
0 is switched and, as mentioned above, the time constant circuit 13
A tracking control signal generated from the brake coil 52 is supplied to the brake coil 52.

Tracking control may be performed using a servo circuit other than the one shown in FIGS. 7 and 8. Further, the rotary heads 1A to 1D are supported by electromechanical transducers such as piezoelectric elements and configured to be able to be displaced in a direction perpendicular to the scanning direction, and tracking control signals are supplied to the electromechanical transducers. You may also do so.

In addition, in the servo circuits of FIGS. 7 and 8 described above, the vertical synchronization signal separated during recording may be recorded as a control signal in the longitudinal direction of the tape to form exactly the same recording pattern as the conventional one. .

In the embodiment of the present invention described above, when the detected voltages E _A to E _D include errors due to variations in the output of the rotating heads 1A to 1D, uneven contact with the tape, variations in the characteristics of a pair of heads, etc. I decided to think about it. Let E ₀ be the correct level of the detected voltage obtained in the detection section in a state where there is no tracking error, and the detected voltages E _A , E _B , E _C
It is assumed that each of the error voltages in the relationship (e _A > e _B > e _C ) is included. In other words, E _A = E ₀ + e _A E _B = E ₀ + e _B E _C = E ₀ + e _C E _D = E ₀ . At this time, the detection voltages sequentially obtained in each detection section within one period of four fields are as follows.

E _AD ＝E _A −E _D ＝e _A E _BA ＝E _B −E _A ＝e _B −e _A E _CB ＝E _C −E _B ＝e _C −e _B E _DC ＝E _D −E _C ＝−e _CAs is clear from the above equation, the sum of error voltages for one period is 0. Therefore, the level comparison circuit 11
If the time constant circuit 13 is connected to the circuit and the time constant is selected such that the detected voltage does not fluctuate within one cycle as described above, it is possible to avoid the influence of the error voltage.

As understood from the description of one embodiment above,
According to this invention, automatic tracking control can be performed using a detection voltage with a good S/N formed by using the output of a rotating head,
There is no need to reproduce the control signal as in the conventional method. In addition, compared to the conventional two-head VTR with two rotating heads spaced 180 degrees apart,
The diameter of the tape guide drum in the roller invention was reduced to 2/3.
If so, it is possible to realize a rotary head type tape recorder which is compatible with conventional devices and which is also smaller in size. Furthermore, in the present invention, if an audio signal is recorded during a track along with a video signal, a fixed head not only for control signals but also for audio is not required, and it is possible to realize a tape recorder that does not require any fixed head. can.

Note that the present invention is applicable not only to color video signals but also to the case of reproducing other information signals such as audio PCM signals.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a head configuration in an embodiment of the present invention, FIG. 2 is a schematic diagram used to explain the relationship between a rotating head and a magnetic tape in an embodiment of the invention, and FIG. FIGS. 4, 5, and 6 are waveform diagrams used to explain the operation of the embodiment of the invention. FIGS. FIG. 2 is a blotter diagram showing one example and another example of a servo circuit to which the present invention is applied. 1A, 1B, 1C, 1D are rotating heads, 2 is a tape guide drum, 3 is a magnetic tape, R _A to R _D are tracks, 6, 9, 10 are switch circuits, 8A to 8
D is a detection circuit, 11 is a level comparison circuit, and 13 is a time constant circuit.

Claims (1)

[Claims] 1. A tape on which information signals are recorded by inclined azimuth recording is run while being wrapped around the circumferential surface of a tape guide drum at a wrapping angle of at least 270°, and the tapes are facing each other at an angular interval of approximately 90°. Four rotary heads whose gap angles are the same are made to slide on the tape, and among the four rotary heads, the recording head and the recording head whose gap angles match are sequentially output. Of the other rotary heads that do not take out this playback output, the outputs of the two rotary heads are taken out, the two obtained outputs are compared, and the error signal obtained from this comparison is A rotary head type tape recorder in which the relative positional relationship between the scanning locus of the rotary head and the recording track of the tape is controlled based on the following.