JP2000067403A - Rotary transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to decrease crosstalks of recording signals to regenerative signals by a simple method by arranging a recording signal pair on a perpendicular bisector of a straight line connecting the regenerative signal pair to each other when the recording signals and the regenerative signals are balance circuits. SOLUTION: The coated optical fibers a, b of the recording signal pair are arranged on the perpendicular bisector connecting the coated fibers A, B of the regenerative signal pair to each other. These signal pairs are so constituted that the points a, A, B and the points b, A, B respectively constitute isosceles triangles. The magnitude of the magnetic fields that the currents flowing in the coated optical fiber (a) and the coated optical fiber (b) impart to the respective coated optical fibers A, B of the signal pair on the reproduction side is respectively equal. Since the coated optical fibers a, b of the recording signal pairs are balance circuits, the currents flowing in the coated optical fibers a, b are the same in the magnitude and are different in the polarity. And also, the magnetic fields to be applied to the coated optical fibers A, B are the differential component of the magnetic fields by the coated optical fiber (a) and the coated optical fiber (b) and are diminished. In addition, since the coated optical fibers A, B of the regenerative signal pair are the balance circuits the influence thereof is further the differential-component and is drastically reduced. The crosstalks of the recording signals to the regenerative signals can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary transformer, and more particularly, to an improvement in a method of drawing a signal line of the rotary transformer.

[0002]

2. Description of the Related Art In a VTR, a rotary transformer is often used for exchanging a recording signal and a reproduction signal with a rotating drum. In a VTR with a large rotating drum diameter, even if the rotary transformer has multiple channels, the distance between the lead wires can be ensured, so that crosstalk (crosstalk) due to electrostatic coupling or electromagnetic coupling between the lead wires did not cause much problem. . In this case, the influence of coupling and level difference between heads and lines rather than between leads is often a problem.

For example, a 1/2 inch broadcast VTR (D-
In one example of Data), since the recording amplifier and the reproducing amplifier are built in the drum, the level of the recording signal is lowered so as not to affect the reproducing signal, and the voltage level ratio between the recording signal and the reproducing signal is set to 0. .33: 1.0 to avoid the effect of crosstalk. Also, the distance between the terminals is relatively wide. On the other hand, in an example of a 1/4 inch VTR (hereinafter abbreviated as DV), since a recording amplifier and a reproduction amplifier are not built in the drum, the voltage level ratio between the recording signal and the reproduction signal is 100,000 as an actually measured value. : 1 (10 V / 0.1
mV) at 100 dB and a current level ratio of 22,000: 1.
(80 mA / 3.6 μA) to 86 dB.

In the digital video format, the recommended drum diameter is as small as 21.4 mm. If the tape pattern is the same, the diameter of the drum can be arbitrarily set, but it is better to adopt the recommended diameter for downsizing.

Further, in a quadruple-speed transfer VTR, 14 erasing heads are used when the erasing heads are A channel and B channel, and 1E channel, 1O channel, 2E channel, and 20 erasing head are used.
In the case of a channel, 16 heads are required, and the number of lead wires is as large as 30. Further, the lead wire can be pulled out only from under the drum, and the space for the lead wire is limited for the purpose of maintaining the rigidity of the drum structure, and the distance between the lead wires cannot be secured. In addition, the rotary transformer has a double structure in order to secure the number of channels. In order to avoid crosstalk, recording and reproduction are separated on the inner side and the outer side. For this reason, the electromagnetic coupling in the transformer can be improved, but the lead wires come closer.

If there is a large level difference as in the case of DV, and if simultaneous reproduction is to be performed while suppressing interference of the recording signal with the reproduction signal, if the allowable crosstalk is 30 dB, the coupling should be at least -116 dB or less. And must be. The generation of crosstalk due to current is explained by mutual induction. 1) When a current flows through a conductor, a magnetic field is generated according to the Ampere right-hand screw law and Biot-Savart law. 2) The magnetic field exerts a force on the conductor according to Framing's left-hand rule, and 3) a current flows as a reaction of this force. It goes through the process. Further, when the distance between the conductors is small and the facing area is large, a capacitance is formed between the conductors, and coupling by voltage occurs.

FIG. 4 shows the structure of a rotary drum used in a DV, FIG. 5 shows a conventional example of drawing out lead wires from the stator of a 14-channel rotary transformer using this rotary drum, and FIG. An example of the channel arrangement of the transformer is shown. Further, FIG. 7 shows the reproduction (P
B) The pair of signal lines on the side and the recording (RE
The arrangement of two pairs of signal lines on the C) side is shown in plan view. FIG. 8 is a schematic view of a cross section of the rotary transformer.

In the method of drawing out lead wires from the stator of the rotary transformer shown in FIG. 5, the signal pair on the reproduction (PB) side is on the inner circumference (inner) side, and the signal pair on the recording (REC) side and the erasure signal pair are on the outer circumference (inner). It is placed on the outer side and played back (P
With respect to one signal pair on the B) side, a signal pair on the reproduction (PB) side and a signal pair on the recording (REC) side and for erasing are arranged at positions shifted from each other. As shown in FIGS. 5 and 7, the current arrangement of the DV leader lines is a parallelogram or a scalene triangle.

The core a of the recording-side REC1 signal pair and the recording-side R
When the schematic diagram of the magnetic field lines from the core wire d of the EC2 signal pair is represented by concentric circles, the magnitude of the effect of the current flowing through these core wires a and d on each of the core wires A and B of the reproduction-side signal pair is as follows. It turns out that they are different. When the reproduced signal is a differential signal, the coupling coefficient between the core a and the core A is K'1, the coupling coefficient between the core a and the core B is K'2, and the coupling coefficient between the core d and the core A is Is K′3, the coupling coefficient between the core wire d and the core wire B is K′4, the current flowing through the core wire a is a, and the current flowing through the core wire d is d. = (AK'1-aK'2) + (dK'3-dK '
4)

[0010]

As described above, in a conventional rotary transformer for a small rotary drum, a large number of lead wires must be arranged in a small area, and a level difference between a recording signal and a reproduction signal is required. Therefore, the effect of crosstalk of the recorded signal on the reproduced signal is a problem.

An object of the present invention is to provide a rotary transformer for a small rotating drum capable of reducing crosstalk of a recording signal to a reproduction signal by a relatively simple method.

[0012]

According to the present invention, there is provided a rotary transformer for inputting a recording signal to a head disposed on a rotary drum and outputting a reproduction signal from the head. When the reproduction signal is a balanced line, the recording signal pair is arranged on a vertical bisector of a straight line connecting the pair of reproduction signal pairs.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a rotary transformer according to the present invention will be described in detail with reference to the accompanying drawings. FIG.
The arrangement of lead wires drawn from the stator of the 14-channel rotary transformer according to one embodiment of the present invention is shown below. FIG. 2 shows an arrangement of a pair of signal lines on the reproduction (PB) side and a pair of signal lines on the recording (REC) side opposed thereto. Further, FIG. 3 shows a schematic view of a cross section of the rotary transformer in this case. FIG. 4 shows a configuration diagram of a rotary drum using the rotary transformer of the present invention.

In these figures, 1 is a video head,
2 is a contact, 3 is an upper drum, 4 is a flange, 5 is a lower drum, 6 is an inner stator of a rotary transformer, 7
Is an inner rotor of the rotary transformer, 8 is an outer stator of the rotary transformer, 9 is an outer rotor of the rotary transformer, 10 is a ball bearing, 11 is a pressurized spacer, 12 is a stator of the motor, 13 is a rotor of the motor,
14 is a lead wire, PB is a reproduction signal pair, REC is a recording signal pair, and ERASE is an erase signal pair. Also, in FIG.
h is the A channel, Bch is the B channel, Ech is the even channel, Och is the odd channel, (10 μm
m) indicates a signal reproducing head output having a recording width of 10 μm.

In the present invention, the recording signal pair a, b
Are arranged on a perpendicular bisector of a straight line connecting the reproduction signal pairs A and B. That is, the arrangement is such that the points a, A, B and the points b, A, B each form an isosceles triangle.

In FIG. 2, the cores a and b of the recording-side signal pair are shown.
The schematic diagram of the magnetic field lines from the circle is shown by concentric circles. It can be seen that the magnitudes of the magnetic fields that the currents flowing through these cores a and b give to the cores A and B of the signal pair on the reproduction side are equal. Since the recording signal pairs a and b are balanced lines,
The currents flowing through b have the same magnitude and different polarities. Therefore, the magnetic field applied to the cores A and B becomes a difference between the magnetic fields of the cores a and b and becomes smaller. Also, the reproduction signal pair A,
Since it is a B-balanced line, its effect is a further difference, which is much smaller than in the case of the conventional example shown in FIG.

The coupling coefficient between the cores a and A is K1, the coupling coefficient between the cores a and B is K2, the coupling coefficient between the cores b and A is K3, and the core b and the core are K. The coupling coefficient between the wires B is K4, the current flowing through the core a is a, and the current flowing through the core b is b
Then, the influence E is E = (aK1−aK2) + (bK3−bK4), and the points a, A, B and the points b, A, B are each 2
Assuming that an equilateral triangle is correctly formed, K1 = K
2. Since K3 = K4, they are offset, and E = (aK1−aK2) + (bK3−bK4) = 0 Further, the distance between the core a and the core b is between the core a and the core A or the center. When the distance between the wire a and the wire B is sufficiently smaller than the distance between the wire a and the wire B, the effect of the magnetic field from the wire a and the wire b becomes a difference and becomes sufficiently small.
Is always smaller.

As described above, the recording signal pairs a and b are arranged on the perpendicular bisector of a straight line connecting the reproduction signal pairs A and B, and the distance between the cords a and b is determined by the cord. When the distance is sufficiently smaller than the distance between a and the core A or between the core a and the core B, the influence of the magnetic field that the recording signal current gives to the reproduction signal, that is, the crosstalk due to the current can be sufficiently reduced. Furthermore, if the distance between the core wire a and the core wire A or between the core wire a and the core wire B can be increased, the capacitance between them can be reduced, so that the influence of the electric field is reduced, and the core wire a and the core wire are reduced. The effect can be further reduced by reducing the distance between b.

[0019]

As described above, according to the first aspect of the present invention, there is provided a rotary transformer for inputting a recording signal to a head disposed on a rotary drum and outputting a reproduction signal from the head. Is a balanced line, the recording signal pair is arranged on a vertical bisector of a straight line connecting the pair of reproduction signal pairs. This makes it possible to reduce the crosstalk of the recording signal to the reproduction signal by a relatively simple method even if the distance between the lead wires is small, and to realize a smaller rotating drum. Simultaneous reproduction at the time of recording can be realized.

According to a second aspect of the present invention, the distance between the recording signal pair and the reproduction signal pair is set to be sufficiently larger than the distance between the recording signal pair. This makes it possible to further reduce crosstalk of the recording signal to the reproduction signal.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an arrangement of lead wires drawn from a stator of a rotary transformer according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement of a reproduction signal pair and a recording signal pair facing the reproduction signal pair.

FIG. 3 is a schematic sectional view of the rotary transformer according to the embodiment of FIG. 1;

FIG. 4 is a configuration diagram of a rotary drum to which the present invention is applied.

FIG. 5 is an explanatory view of a conventional example of drawing out a lead wire from a stator of a 14-channel rotary transformer.

FIG. 6 is a table showing an example of a channel arrangement of a 14-channel rotary transformer.

FIG. 7 is an explanatory view showing the arrangement of two pairs of a conventional reproduction signal line pair and a recording signal pair opposed thereto.

FIG. 8 is a schematic sectional view of a conventional rotary transformer.

[Explanation of symbols]

1 ... video head, 2 ... contact, 3 ... upper drum, 4
... Flange, 5 ... Lower drum, 6 ... Inner stator of rotary transformer, 7 ... Inner rotor of rotary transformer, 8 ... Outer stator of rotary transformer, 9 ... Outer rotor of rotary transformer, 10 ... Ball bearing, 11 ... Pressurized Seat, 12 ... stator of motor, 13
... Motor rotor, 14 ... lead wire, PB ... reproduction signal pair, REC ... recording signal pair, ERASE ... erase signal pair.

Claims (2)

[Claims] 1. A rotary transformer for inputting a recording signal to a head arranged on a rotating drum and outputting a reproduction signal from the head, wherein the recording signal pair is a signal line when the recording signal and the reproduction signal are balanced lines. A rotary transformer, which is arranged on a vertical bisector of a straight line connecting a pair of reproduction signal pairs. 2. The rotary transformer according to claim 1, wherein a distance between the recording signal pair and the reproduction signal pair is set sufficiently larger than a distance between the recording signal pair.