JPS61224106A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent invasion of crosstalk component by connecting an impedance means showing a low impedance at a frequency of a signal invaded as crosstalk in parallel with a winding of a rotary transformer so as to bring the winding into nearly short-circuit state to the crosstalk component. CONSTITUTION:A series resonance circuit 25 comprising of a coil L and a capacitor C is connected in parallel with a stator winding 23. The resonance frequency of the series resonance circuit 25 is set to the frequency band of a sound signal recorded/reproduced by a rotary head for sound signal. Then the series resonance circuit 25 has the lowest impedance at the frequency band of the sound signal, and no crosstalk component is sent in the signal at the frequency above because it is short-circuited across the winding 23, and the same effect as a short ring is obtained. This is applied also to the sound signal rotary head.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a helical scan video tape recorder (hereinafter referred to as a VTR) equipped with a rotary head for audio signals and a rotary head for erasing in addition to a rotary head for video signals. )
The present invention relates to magnetic recording and reproducing devices such as.

[Technical background of the invention]

In a helical scan VTR, signals are transmitted between a magnetic head and a recording/reproducing amplifier via a four-tally transformer.

In such a system, when trying to transmit different signals at the same time, crosstalk occurs between the respective signals. For this reason, conventionally there was a shield between each winding.
A ring is inserted to prevent crosstalk.

FIG. 5 shows the stay of a rotary transformer that has one set of video signal rotary heads, one set of audio signal rotary heads, and an erasing rotary head. (or a welfare rotor).

The erasing head is a head that erases a location where a recording track is to be formed, prior to a video signal rotating head or an audio signal rotating head. Further, the rotary head for audio signals is, for example, a head that records frequency-modulated audio signals.

In the figure, (a) t (b) I (d) I (
f) @ (h) is a groove formed in the stator (or rotor) 11 for arranging the windings. (c)
, (e) and (g) are grooves similarly formed for arranging the seal ring. Generally, due to the relationship of the coupling coefficient, the windings of the two systems are placed on the innermost circumference,
Next, the 1st ring, then the 2 audio systems, and then the 1st ring.
Finally, the erasure winding is placed. Also,
Since the crosstalk between the windings increases as the frequency decreases, a fault ring is usually placed between the two audio systems as well.

[Problems with background technology]

However, in the case of a configuration in which crosstalk is prevented by sealing as described above, as the number of types of signals to be transmitted increases, as in the example shown in Fig. 5, the number of grooves formed on the stator and rotor increases. , there is a problem that manufacturing becomes difficult.

[Purpose of the invention]

This invention was made to deal with the above circumstances,
It is an object of the present invention to provide a magnetic recording/reproducing device configured to eliminate crosstalk without using sealing.

[Summary of the invention]

In this invention, an impedance means having a low impedance at the frequency of a signal mixed as crosstalk is connected in parallel to the winding of a rotary transformer.
The windings are almost short-circuited to prevent crosstalk components from entering.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of one embodiment.

In the figure, 21 is a rotating head for erasing.

22 is a winding on the rotor side of this head 21, and 23 is a winding on the stator side. 24 is a recording amplifier. A series resonant circuit 25 consisting of a coil 2 and a capacitor (0) is connected in parallel to the stator side winding 23. Although not shown, a series resonant circuit is connected in parallel to the stator side winding of the audio signal rotary head in the same way.The resonance of this series resonant circuit is The frequency is
Set to the frequency of the erase signal.

According to such a configuration, the series resonant circuit 25 has the lowest impedance in the audio signal frequency band. Therefore, for signals of such frequencies, winding 2
30 is short-circuited at both ends and crosstalk components are not transmitted.
You can get the same effect as a sheet ring. This also applies to the audio signal rotary head side.

Therefore, according to this embodiment, as shown in FIG. 2, it is possible to omit the shifting between the audio winding and the cancellation winding.

In addition to this, as shown in FIG. 3, it is possible to use an elimination winding in place of the shunt ring between the two audio system windings. In the case of the example shown in FIG. 2, the number of grooves can be reduced by one compared to the example shown in FIG. Similarly,
In the example of FIG. 3, the number can be reduced by two.

Therefore, according to this embodiment, even if the number of transmission signals increases, an increase in manufacturing costs can be suppressed as much as possible.

Note that the above configuration is possible when the audio signal and the cancellation signal do not overlap in frequency. Regarding this point, in a VTR equipped with a rotary erasing head, there is generally no problem because the two signal frequencies are set so as not to overlap. For example, in the VH8 system, the carrier frequencies of the two audio signals are set to 1.3 MHz and 1.7 MHz, respectively, but the frequency of the cancellation signal is set to several MHz in terms of cancellation efficiency.
It is set to Hz.

In addition, as mentioned above, when handling two systems of audio signals, it is sufficient to prepare a series resonant circuit for each signal and connect these to the winding 23 in parallel.

FIG. 4 is a circuit diagram showing another embodiment of the invention.

In this embodiment, attention is paid to the fact that the erasing head 21 is not used in the reproduction mode, and a switch circuit 26 is connected in series to the winding 23 in addition to a series resonant circuit 25.

This switch circuit 26 is turned on in the playback mode, and with such a configuration in which both ends of the winding 23 are short-circuited, in the playback mode, the ability to eliminate crosstalk of the audio signal is achieved only by the series resonant circuit 25. This can be improved compared to the case where it is used.

Note that, of course, in the present invention, a series resonant circuit or a switch circuit may be connected in parallel to the winding on the rotor side.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a magnetic recording/reproducing device configured to eliminate crosstalk without using sealing.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, FIGS. 2 and 3 are structural diagrams of a stator (or rotor) shown to explain the effect of FIG. 1, and FIG. A circuit diagram showing a second embodiment of the present invention, and FIG. 5 is a structural diagram of a stator (or rotor) shown to explain the conventional problem. 21... Erasing head, 22... Rotor side winding 1,
23... Stator @ winding, 24... Recording amplifier,
25...Series resonant circuit, 26...Switch circuit. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 F

Claims (1)

[Scope of Claims] In a magnetic recording/reproducing device equipped with a rotary head for erasing in addition to a rotary head for information signals, the rotary head is connected in parallel to the winding of a rotary transformer corresponding to the rotary head for erasing signals. A magnetic device comprising: a first impedance means having a low impedance at the information signal frequency; and a second impedance means having a low impedance at the information signal frequency, the second impedance means being connected in parallel to the winding of a rotary transformer corresponding to the erasing rotary head. Recording and playback device.