JPH02308402A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce the crosstalk in a rotary transformer by providing alternately a channel for SP and a channel for LP, and providing a switch means for short-circuiting a stator winding of the channel being in an unused state. CONSTITUTION:Each of rotor windings of adjacent channels of a rotary transformer 7, for instance, 5a and 5a' is connected to a head 2a for SP and a head 2a' for LP, and this device is provided with a switch means consisting of switches 12a - 12d and switches 12a' - 12d', etc., for short-circuiting a stator winding of the channel to which the head for LP of the rotary transformer is connected, and a stator winding of the channel to which the head for SP is connected, at the time of a standard mode and at the time of a long time mode, respectively. Therefore, the crosstalk in the rotary transformer 7 can be reduced enough by a simple constitution.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording/reproducing device (including a recording-only machine or a reproduction-only machine) such as a VTR (video tape recorder), and includes four magnetic recording/reproducing devices. A standard speed head and four long-time speed heads are mounted on a rotating drum at 90° each.
This is to reduce the wolf talk in a rotary transformer such as a VTR, which is arranged at intervals, and the magnetic tape is wound around the rotating drum so as to slightly exceed 270 degrees.

[Conventional technologies] In general, for VTRs, the diameter of the rotating drum is made small for miniaturization, and four heads are arranged on this rotating drum at 90° intervals, and the circumferential surface of the rotating drum is 270
A device in which magnetic tape is wound over an angle of ＠ (actually about 15 degrees more than 270 degrees) is known.

FIG. 4 schematically shows the surroundings of the rotating drum of the VTR, where reference numeral 1 indicates the rotating drum, 2a, 2b, 2c.
, 2d are heads arranged at 90° intervals on the rotating drum 1, and 3 is a magnetic tape.
is wound around the rotating drum 1 at an angle of slightly over 270°.

Note that the symbols indicating the heads, such as 2a, 2b, 2c, and 2d mentioned above, are used uniformly in each drawing, so
Hereinafter, detailed explanation thereof may be omitted.

The heads 2a to 2d described above have a gap 18a in FIG.
As shown in the enlarged view of the vicinity of 18b, 18c, and 18d,
Heads 2a and 20 have the same azimuth, and heads 2b and 2
d also has the same azimuth, but heads 2a and 2C and 2b
and 2d is the reverse azimuth.

FIG. 6 schematically shows the recording pattern on the magnetic tape 3 described in FIG. 4 and the positional relationship of the heads 2a to 2d in the recording pattern. In the above VTR, during recording, when the head 2a reaches the beginning of the 30th winding of the magnetic tape, that is, at the position shown in FIG. 6(b), a recording current flows, passing through (C) and (d), as shown in (e). When the winding end position is reached, the recording current stops, and at this time, the recording current flows through the head 2b, which is at the winding start position. The rotary drum l rotates three times in one cycle from the heads 2a to 2d, and by sequentially switching the recording current to these heads 2a to 2d, recording tracks A, corresponding to the heads 2a to 2d are created. B, C, and D are formed one after another. Note that the recording track width W (shown in FIG. 6(a)) is determined by the running speed of the magnetic tape 30.

FIG. 7 schematically shows the reproducing state of the head 2a and the other heads 2b, 2c, and 2d when the head 2a is reproducing the recording track A with on-tracking during reproduction. Ta, Tb, Tc, and Td represent each head 2a to 2.
It shows the time when d is played, and it is actually played back at the same time.

Of the heads 2a to 2d, the reproduction signal is obtained from the rad 2a for a time corresponding to Ta for the entire recording track A, and the reproduction signal is obtained from the head 2b for a time corresponding to Ta.
It is the first 2/3 of the time of b, and from the diagonally shaded part of the recording track D with the same azimuth, head 2C
The reproduction signal is obtained from the head 2d during the time before 1/3 and after 1/3 of Tc, and the reproduction signal is obtained from the head 2d from the diagonally shaded portion of the recording track A with the same azimuth. This is 2/3 of the time after Td, and is from the diagonally shaded portion of recording track B having the same azimuth.

By the way, signal transmission between the heads 2a to 2d attached to the rotary drum l and rotating with respect to the VTR body and a circuit board (not shown) fixed to the VTR body, that is, transmission from the circuit board supplying a recording current to the head;
The output signal reproduced by the head is normally supplied to the circuit board via a multi-channel rotary transformer having a channel consisting of a rotor winding and a stator winding for each head. Figure 8 schematically shows a plan view of a flat rotary transformer, Figure 9 schematically shows a front view of a cylindrical rotary transformer, and Figure 10 schematically shows an exploded state of a cylindrical rotary transformer. 4 represents a planar rotary transformer, 7 represents a cylindrical rotary transformer, 6a, 5b, and 5C15d represent channels for each of the heads, and 6 represents a short ring. Further, in FIG. 10, reference numeral 19 indicates a rotor, 20 a stator, 21 a rotor winding, and 22 a stator winding.

By the way, crosstalk occurs between adjacent windings of a rotary transformer. On the other hand, as explained in FIG.
, 2d, and even when other heads are on track, there are playback signals from heads that are not on track. For this reason, in the rotary transformer, in order to prevent crosstalk from a channel connected to a head that is not in an on-track state to a channel connected to a head that is in an on-track state, a short ring is installed between channels 5a to 5d. Some have 6. A circuit shown in FIG. 11 is also known which is processed in terms of circuitry without providing such a short ring 6.

Figure 11 shows 5! of the recording/playback system of a VTR. The playback status is shown. In Figure 11, 8
a-8b-8c% 8d is playback preamplifier, 9a, 9
b, 9c, 9d are recording amplifiers, lO is terminals swa, sw
The terminals PB of each of the heads 2a to 2d are
A switch 11 is controlled by the head switching pulse and switches 12a, 12a, 12a, 12a, 12a, 11, which switch the output to each head when recording from the terminal RFC.
2b, 12c, 12d are rotary transformers 4 (or 7)
13 is a switch drive circuit that drives the switches 12a to 126; and 13 is a switch drive circuit that drives the switches 12a to 126.
-s w d is controlled by the head switching pulse described above.

The head switching pulses supplied to the terminals swa - swd are generated by detecting the rotational phase of the rotary drum 10, and are shown in (a), (b) and () of FIG. 12, respectively.
c) and (d).

The low periods of (a) to (d) are the heads 2a to 2, respectively.
The signal is regenerated by d, and the switches 12a to 12d are closed during the high period.

By the switching pulse shown in FIG. 12, for example, when the head 2a is playing, the channels 5b, 5c of the rotary transformer connected to the other heads 2b, 2C12d,
5d stator winding is switch 12b, 12c, 12d
, the coupled inductance of the rotary transformer decreases, and a short ring is formed by the winding in a pseudo manner. As a result, the channels 5b, 5c,
The amount of crosstalk from 5d to 5a can be reduced to a level that poses no problem in practice.

Also, symbols 16a, 16b, 16c, 18d are turned on during recording (off during playback), 17a, 17b, ! 7c,
Reference numeral 17d indicates a recording/reproduction changeover switch that is turned on during reproduction (off during recording).

Details of the switch drive circuit 13 are shown in FIG. 13. This switch drive circuit 13 drives the short-circuit switches 12a to 12d, so there are four identical circuits. Here, one circuit in which the switch 12a is driven by being controlled by the head switching pulse shown in FIG. 12 will be described. The terminal S W a is a terminal to which the switching pulse shown in FIG. 12(a) is input, and the terminal S W a is connected to the base of the transistor Q1 via the base resistor R1 of the transistor Q1. . The collector of this transistor Q1 is always connected to a DC5V terminal AL5 which serves as a power supply, and an emitter follower is formed with an emitter resistor R2 connected to the emitter. The emitter of the transistor Q1 is connected to the emitter of the transistor Q2, and the base of the transistor Q2 is connected via a resistor R3 to a terminal n of a control line (not shown) which becomes low during reproduction.

When this terminal PB becomes low during reproduction, the transistor Q2 is turned on. The collector of this transistor Q2 is connected to the base of a transistor Q3 via a resistor R4. This transistor Q3 serves as the switch 12a, and its collector and emitter are connected to the stator winding of the channel 5a of the rotary transformer 4 (or 7).

When the switching pulse input to the terminal S W a during reproduction is high, the emitter of the transistor Q1 is also high, and since the transistor Q2 is also on, the base of the transistor Q3 is also high via the resistor R4. ,
The transistor Q3 is turned on and the stator windings are shorted. When the switching pulse input to the terminal S W a is low, the transistor Q3 is turned off, and the stator winding signal flows to the preamplifier 8a. In this way, only when the head 2a is reproducing the recording track A, the transistor Q3 is turned off, and this transistor is connected to the other head 2b.

Turns on while 2c and 2d are playing. The terminal SwbS
The other three circuits connected to swc%swd operate similarly.

It goes without saying that the head switching pulses inputted to the terminals swa to swd are generated at a timing such that each of the heads 2a to 2d matches each recording track A to D.

The above explanation is for the case where things recorded at standard tape speed are played back at standard tape speed, but there are also VTRs that play back things recorded at tape speed for a long time at tape speed. In this case, it is desirable to provide a total of eight dedicated heads (with different track widths) for standard speed (hereinafter referred to as SP) and long-time speed (hereinafter referred to as LP). In this case, an 8-channel rotary transformer is required, and for this reason conventionally two 4-channel flat plate rotary transformers or a cylindrical 3N rotary transformer as shown in Fig. 14 has been used. , recently the first
As shown in Figure 5, a cylindrical rotary transformer divided into SP and LP is used.

14 and 15 schematically show a rotary transformer, and in FIG. 14, reference numeral 23 indicates a winding groove provided in the rotor 19, and 24 indicates a winding groove provided in the stator 20. be. In FIG. 15, symbols 5a', 5
b', 5c', and 5d' indicate channels for LP in the rotary transformer 7.

Even with conventionally used rotary transformers like this,
In order to prevent crosstalk between the windings, a short ring is inserted between the windings, or the stator windings in the rotary transformer of the unused head are short-circuited by head switching pulses in the same way as explained in FIG. 11 above. It is necessary to provide circuits for SP and LP, respectively.

[Problems to be Solved by the Invention] By the way, providing a short ring in the rotary transformer as described above not only increases the size of the rotary transformer but also increases the cost. When providing a circuit for shorting the stator windings, the switch drive circuit 13 explained with reference to FIG.・There is a drawback that click noise is mixed into the playback signal when it is turned off.

This invention eliminates the above-mentioned conventional drawbacks,
It has four heads for SP and four heads for LP,
Easily eliminates crosstalk between channels of a rotary transformer that transmits signals with the head of a magnetic recording and reproducing device that records signals on a magnetic tape wound at an angle of slightly more than 270 degrees or reproduces recorded signals. The present invention provides a magnetic recording/reproducing device which is sufficiently small due to its configuration.

Means for Solving the Problem] In order to solve the above problem, the present invention uses four S
It is equipped with a P head, four LP heads, and a multi-channel rotary transformer that transmits signals between these SP heads and LP heads and the circuit of the main body of the device. A magnetic tape is wound around the surface at an angle of slightly more than 270 degrees, and the magnetic tape is scanned by the head described above in a direction crossing the running direction of the magnetic tape, thereby recording a signal on the magnetic tape, or recording a signal on the magnetic tape. In a magnetic recording and reproducing device configured to reproduce signals from a tape, rotor windings of adjacent channels of the rotary transformer are connected to the SP head and the LP head, respectively;
That is, SP channels and LP channels are arranged alternately, and a switch means is provided to short-circuit the stator windings of channels for unused speeds.

[Operation] In the magnetic recording/reproducing device configured as above,
In the standard mode, the stator winding of the LP channel is short-circuited, and in the long-term mode, the stator winding of the SP channel is short-circuited to act as a pseudo short ring, thereby reducing crosstalk between channels.

In addition, in order to fully obtain the effect of this pseudo short ring, it is necessary to reduce the impedance of the winding.
By shorting the terminal side of the stator winding by a circuit connected to the stator winding, the coupling impedance is reduced, and therefore the impedance and dance of the winding are reduced, and the sufficient effect of the pseudo short ring described above is achieved. can get.

This effect as a pseudo short ring is effective not only during playback but also during recording.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a recording/reproducing system of a magnetic recording/reproducing apparatus, and reference numeral 7 indicates a cylindrical rotary transformer. FIG. 2 schematically shows this cylindrical rotary transformer 7, in which SPP channels 5a to 5d and LPP channels 5a'' to 5d' are arranged alternately. Since the basic configuration for LP is the same as that shown in FIG. Therefore, detailed explanation thereof will be omitted. FIG. 1 shows playback in standard mode. Each channel 5a of the rotary transformer 7
~5d, 5a'~5d' The switches that short the stator windings are 12 for SP.
a to 12d, and 12a' to 12d' are provided for LP. Reference numeral 14 is an output LP for SP during playback.
A switch 15 is used to switch between SPP manual input and LP input during recording, and is controlled by a switching pulse between SP and LP input to a terminal 25. 26 and 27 are terminals to which control signals for LP and SP are manually input, respectively.

In the standard mode, a high control signal is input to the terminal 27, which causes the switch 1 to switch as shown in the figure.
28' to 12d' are turned on, and the windings of the LP channels 5a' to 5d' of the rotary transformer 7 become pseudo short rings, and the crosstalk between the SP channels 5a to 5d is sufficiently reduced. Ru.

In this state, the signals reproduced from the SP heads 2a to 2d pass through the rotary transformer 7 to the preamplifiers 8a to 8d.
The output is outputted to the terminal PB through the changeover switches 10 and 14.

Also, during recording, a signal to be recorded from the terminal REC passes through the changeover switches 15 and 11 to the recording amplifiers 9a to 9.
d, and this output is supplied as a recording current to the SPP heads 2a to 2d via the rotary transformer 7.

In the long-term mode, a high control signal is input to the terminal 26, thereby causing the switches 12a to 12d to
is turned on, and the windings of channels 5a to 5d for SP of rotary transformer 7 become pseudo short rings, and LP
Crosstalk between channels 5a' to 5d' is sufficiently reduced.

In this state, the signals reproduced from the LP heads 2a' to 2d' pass through the rotary transformer 7 to the preamplifier 8a'.
~8d', and its output is input to the changeover switch 10.
' and 14 and is output to terminal PB.

Also, during recording, the signal to be recorded from the terminal REC passes through the changeover switches 15 and 11' and passes through the recording amplifier 9a'.
.about.9d' is manually input, and the output thereof is supplied as a recording current to the LPP heads 2a' to 2d' via the rotary transformer 7.

FIG. 3 shows another embodiment, in which the preamplifier 8a
8d, recording amplifiers 9a to 9d, etc. are commonly used for SP and LP, and the same reference numerals as in FIG. 1 indicate those having the same effect. This figure shows playback in standard mode.

In the standard mode, the control signal to the terminal 26 is high, and the switches 12a'' to 12d' are turned on. When these switches 12a' to 12d' are turned on, the rotary transformer 70 channels 5a' to 12d' are turned on. The stator winding 5d' is short-circuited, and the winding of the channel constitutes a pseudo short ring.

During playback in this state, regarding the head 2a, the playback signal from the head passes through the rotary transformer 70 channel 5a and is input to the preamplifier 8a, and one end of the stator winding of this channel 5a is turned on. It is grounded through the switch 12a' and the changeover switch 17a which is turned on during playback.

When recording, regarding the head 2a, the recording amplifier 9
The recording current outputted from the terminal a flows through the switch 12a' which is turned on as described above, flows to the stator winding of the channel 5a of the rotary transformer 7, and is grounded through the changeover switch 16a which is turned on during recording. be done. A recording current is supplied to the head 2a by the current flowing through the stator winding of the channel 5a.

Although the above description concerns the head 2a, the same applies to the other heads 20 to 2d.

In the long-term mode, the control signal to the terminal 27 is high, and the switches 12a to 12d of Yoshimi Mae are turned on. When these switches 12a to 12d are turned on, the stator windings of the channels 5a to 5d of the rotary transformer 70 are shorted, and the windings of the channels constitute a pseudo short ring.

When playing in this state, regarding head 2a',
The reproduced signal from the head is transmitted to the rotary transformer 70 channel 5a' and the switch 12a which is turned on.
The signal is input to the preamplifier 8a through the channel 5a', and one end of the stator winding of the channel 5a' is grounded through the changeover switch 17a which is turned on during reproduction.

At the time of recording, regarding the head 2a'', the recording current output from the recording amplifier 9a flows into the stator winding of the channel 5a' of the rotary transformer 7, passes through the switch I2a which is turned on as described above, and is turned on during recording. It is grounded through the changeover switch 16a which is turned on.The recording current is supplied to the head 2a' by the current flowing through the stator winding of the channel 5a'.

Although the above description concerns the head 2a', the same applies to the other heads 2c' to 2d'.

In the above-mentioned FIG. 2, channels 5a to 5d and 5a' to 5d' of the rotary transformer 70 are
15b15b', OCl 09. However, if channels 5a to 5d for SP and channels 5a' to 5d' for LP are alternated, the order becomes second.
It is not limited to the illustration.

[Effects of the Invention] As described above, the present invention includes four SP heads 2a to 2d arranged on the rotating drum 1 at 90° intervals, and four SP heads 2a to 2d arranged on the rotating drum 1 at 90° intervals. a multi-channel rotary transformer 7 that transmits signals between the LP heads 2a' to 2d', these SP heads and LP heads, and the circuit of the main body of the device including the rotary drum 1;
The magnetic tape 3 is wound around the circumferential surface of the rotary drum 1 at an angle slightly exceeding 270 degrees, and the magnetic tape 3 is wound in a direction crossing the running direction of the magnetic tape 2a.
2d, 2a' and 2d', thereby recording signals on the magnetic tape 3 or reproducing signals from the magnetic tape 3. The rotor windings of the channels, for example 5a and 5a', are in contact with the SP head 2a and the LP head 2a', respectively, and in the standard mode, the stator of the channel to which the LP head of the rotary transformer 7 is connected Switches 12a to 12d and 12a' to short-circuit the windings and, in the long-term mode, the stator windings of the channels to which the SP head is connected]
Since the switch means consisting of 2d' etc. is provided, crosstalk in the rotary transformer 7 can be sufficiently reduced with a simple configuration.

Recently, there has been a remarkable trend towards miniaturization and lower prices of magnetic recording/reproducing devices, and while 270゜ winding devices are often used, there is also a trend toward specialization of SP and LP heads in order to obtain high performance. Because of this, the circuit around the head tends to become complicated. The present invention solves these problems and has the effect of reducing cost and circuit area.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a front view schematically showing a rotary transformer used in the one shown in FIG. 1, and FIG. 3 is a block diagram showing another embodiment. . Figures 4 to 15 are for explaining the conventional system. Figure 4 is a plan view schematically showing the vicinity of the rotating drum, and Figure 5 is an enlarged view of the vicinity of the head gap. FIG. 6 is a developed view schematically showing the recording pattern on the magnetic tape and the position of the head relative to it; FIG. 7 is a schematic diagram schematically showing the playback status of the head with respect to the recording track; The figure is a plan view schematically showing a rotary transformer, FIG. 9 is a front view schematically showing a rotary transformer, and FIG. 10 is an exploded perspective view schematically showing a rotary transformer.
Fig. 11 is a block diagram showing an outline of the recording and reproducing system of a VTR, Fig. 12 [J is a time chart for explaining the operation of the main parts of Fig. 11, and Fig. 13 shows the main parts of Fig. 11. The circuit diagram, FIG. 14 is a sectional view schematically showing the rotary transformer, and FIG. 15 is a front view schematically showing the rotary transformer. 1: Rotating drum, 2 a to 2 d, 2 a'
~2 d: head, 3: magnetic tape, 5a-5d, 5
a' to 5d' two channels, 7: M type rotary transformer, 12a to 12d, 12a' to 12d':
switch.

Claims (1)

[Claims] 4 standard speed heads arranged at 90° intervals on the rotating drum, 4 long speed heads arranged at 90° intervals on the rotating drum, and these standard speed heads and long It is equipped with a multi-channel rotary transformer that transmits signals between the time speed head and the circuit of the main body of the device equipped with the rotary drum, and a magnetic tape is wound around the circumferential surface of the rotary drum so as to slightly exceed 270 degrees. In a magnetic recording and reproducing apparatus, the magnetic tape is scanned by the head in a direction crossing the running direction of the magnetic tape, thereby recording signals on the magnetic tape or reproducing signals from the magnetic tape. The rotor windings of adjacent channels of the rotary transformer are connected to the standard speed head and the long speed head, respectively, and in the standard mode, the stator windings of the channel to which the long speed head of the rotary transformer is connected are connected. 1. A magnetic recording and reproducing device characterized in that a switch means is provided for shorting a wire and a stator winding of a channel connected to a standard speed head when in a long-time mode.