JPH0316103Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for properly adjusting the azimuth of a reproducing head without malfunction by reproducing audio signals recorded on a magnetic tape in a magnetic recording/reproducing apparatus.

As an automatic azimuth adjustment device for a reproducing head, the present applicant previously proposed the use of a magnetic head as described in Japanese Patent Application No. 194613/1983.

That is, FIG. 1 shows an embodiment of such a magnetic head, and in the figure, Ma ₁ and Ma ₂ are upper and lower division parts that divide the left core half of a pair of abutted core halves into upper and lower parts; Further, Mb ₂ and Mb ₁ are upper and lower division parts that divide the right core half into upper and lower parts, and the division parts Ma ₁ and Mb ₁ have a thickness of, for example, 0.4 mm, and the division parts Ma ₂ and Mb ₂ have a thickness of 0.2 mm, Therefore, the track contacting surface consisting of these cores is the recording track width of a stereo recording tape (0.6 mm).
It corresponds to

Among the above division parts, the division part with the largest division width
_{Coils a , ​}
b are wound respectively. Also, M indicates the gap position of the head.

If the magnetic head with the above structure is used as a playback head, coils a and b will divide and play back the same track on the magnetic tape, thereby producing playback signals Sa and Sb picked up from coils a and b.
This playback head azimuth can be adjusted using

That is, the signal (Sa+Sb) extracted from both ends 7 and 9 of coil a and coil b connected in series is amplified as an audio signal, and is used as the first reproduction signal for azimuth adjustment. The signal Sb taken out between the connection points 8 and 9 of the coil b is used as the second reproduction signal for azimuth adjustment, and these are waveform-shaped and their phases are compared. recording head 28
2, the leaking magnetic field lines B from the recording head pass through the core of the reproducing head and enter the original reproduction signal from the magnetic tape as a crossfeed. However, the first reproduction signal (Sa+Sb) is the sum of the crossfeed picked up by core Ma ₁ and core Mb ₁ , but in this case, the magnetic field lines B due to the crossfeed are applied from the same direction as shown in Figure 2. , the direction of the electromotive force generated in the coil a wound around the core Ma ₁ and the core
The directions of the electromotive forces generated in the coil b wound around Mb ₁ are opposite to each other and cancel each other out. On the other hand, a second reproduction signal is extracted as an azimuth adjustment signal.
In Sb, an electromotive force is generated in the coil b wound only by the magnetic field lines passing through the core Mb ₁ , so the crossfeed added to the signal extracted from the original magnetic tape becomes large, causing a malfunction in azimuth adjustment. .

The present invention relates to a device for removing this crossfeed, and will be described in detail below with reference to the drawings.

In Figure 3, the audio input signal S ₁ is the recording amplifier 2.
5, its output terminal 2 is connected to the input terminal 3 of the recording equalizer amplifier 26, and its output terminal 4 is connected to the bias trap circuit 38.
is connected to the input terminal 5 of the recording head 28 via the recording head 28, and the other input terminal 6 of the recording head 28 is connected to ground. Further, the output terminal 10 of the bias oscillation circuit 27 is connected to the input terminal 5 of the recording head 28. On the other hand, the output terminal 7 of the playback head 29
is connected to the input terminal 11 of the first reproduction equalizer amplifier 30, and the connection point terminal 8 between coil a and coil b of the reproduction head 29 is connected to the input terminal 12 of the second reproduction equalizer amplifier 31. The other output terminal 9 of the coil is connected to ground. The output terminal 13 of the first reproduction equalizer amplifier is connected to the input terminal 15 of the first waveform shaping circuit 32, and the output terminal 14 of the second reproduction equalizer amplifier 31 is connected to the second waveform shaping circuit 33.
is connected to the input terminal 16 of. The output terminal 17 of the first waveform shaping circuit 32 is connected to one input terminal 19 of the phase comparison circuit 34, and the output terminal 18 of the second waveform shaping circuit 33 is connected to the other input terminal 20 of the phase comparison circuit 34. has been done. The output terminal 21 of the phase comparison circuit 34 is connected to the input terminal 22 of the motor drive circuit 35.
The output terminal 23 of the regeneration azimuth adjustment motor 36
It is connected to the. Also recording equalizer amplifier 2
Output terminal 4 of 6 is a capacitor connected in series.
C ₁ and the second reproduction equalizer amplifier 3 via an impedance circuit 39 composed of a resistor R ₁
It is connected to the output terminal 14 of 1. 37 indicates a magnetic tape.

When simultaneously recording and reproducing in a three-head magnetic recording and reproducing apparatus having the above circuit configuration, the signal _S1 recorded on the magnetic tape 37 is amplified by the recording amplifier 25, equalized by the recording equalizer amplifier 26, and sent to the recording head 28. Flows as a signal current. When a part of this signal is electromagnetically converted by the recording head 28, it is transferred to the recording head 28 as leakage magnetic field lines B.
The recording head 29 is located close to the recording head 29.
At this time, in the case of the structure of the reproducing head 29 as described above, this leakage magnetic field line B is caused by the core of the reproducing head 29.
As a crossfeed picked up by coil b wound around Mb ₁ , it is mixed with the signal reproduced via the magnetic tape 37 and multiplexed as a second reproduction signal Sb to terminal 8 at the connection point between reproduction head coil a and coil b. It will be output to . This second reproduction signal Sb
is amplified by the second reproduction equalizer amplifier 31 and inputted to the second waveform shaping circuit 33 as a signal for azimuth adjustment. Furthermore, the magnetic field lines B picked up by the cores Ma ₁ and Mb ₁ are canceled out to the output terminal 7 where the coil a and coil b of the reproduction head 29 are connected in series, and the signal via the magnetic tape 37 is output as the first reproduction signal. be done. This first reproduction signal (Sa+Sb)
is amplified by the first reproduction equalizer circuit 30, inputted to the first waveform shaping circuit 32 as a signal for azimuth adjustment, and outputted as the audio output signal So. These waveform-shaped first and second reproduction signals enter the phase comparison circuit 34, where the phase difference between these signals is detected as the inclination of the reproduction head 29, and the reproduction azimuth is adjusted via the motor drive circuit 35. The motor 36 corrects the inclination, but since the above-mentioned second reproduction signal Sb contains multiple cross-feed components,
There is a risk of malfunction during phase comparison. Therefore, in order to remove this cross-feed component, an impedance is installed between the second reproduction equalizer amplifier 31 and the second waveform shaping circuit 33 by connecting the output terminal 4 of the recording equalizer amplifier 26 to the capacitor C ₁ and the resistor R ₁ in series. A recording signal of an appropriate level is added through the circuit. At this time, consideration must be given to adding a signal having a phase opposite to that of the cross-feed component. Further, the value of the resistor R ₁ is selected to be sufficiently large compared to the output impedance of the second reproduction equalizer amplifier 31.

In other words, the cross-feed component mixed in the second reproduction signal Sb can be canceled by directly adding a recording signal having the opposite phase and the same level to the cross-feed component through the impedance circuit. The measurement results according to the above-mentioned embodiments show that the crossfeed component of each frequency was improved by a maximum of 20 dB or more in the mid-high frequency band of 2 kHz to 20 kHz.

Since the azimuth adjustment using the first and second reproduction signals is well known, the details thereof will be omitted. As described above, according to the present invention, it is possible to effectively cancel the crossfeed that occurs when recording and playback are performed simultaneously with a three-head type magnetic recording/playback device with a simple circuit, so that the first Furthermore, there is an effect that automatic azimuth adjustment of the reproducing head can be accurately performed without malfunction by using the second reproducing signal.

[Brief explanation of the drawing]

FIG. 1 shows the structure of a reproducing head according to an embodiment of the present invention. FIG. 2 shows leakage lines of magnetic force B due to the crossfeed acting on the reproducing head. FIG. 3 shows a circuit diagram of an embodiment of the present invention. 25... Recording amplifier, 26... Recording equalizer amplifier, 27... Bias oscillation circuit, 28...
Recording head, 29...Playback head, 30...1st
Reproduction equalizer amplifier, 31...Second reproduction equalizer amplifier, 32...First waveform shaping circuit, 33...Second waveform shaping circuit, 34...Phase comparison circuit, 35...Motor drive circuit, 36 ……
Reproduction azimuth adjustment motor, 37...Magnetic tape, 38...Bias trap circuit, 39...Impedance circuit, _C1 ...Capacitor, _R1 ...
…resistance.

Claims (1)

[Scope of utility model registration request] A core for at least one recording track on a magnetic tape is formed of a pair of abutting core halves, and is divided into upper and lower parts in the width direction of the recording track, and has an upper portion of one of the pair of core halves and A first reproduction signal taken out from both ends of the coils connected in series in a reproduction head having coils wound respectively on the lower part of the other head, and a second reproduction signal taken out from the connection point of the windings. In the apparatus for adjusting the azimuth of the playback head by comparing the phases of the playback head, a part of the recording signal of the recording signal circuit connected to the recording head disposed close to the playback head is transmitted to the second impedance circuit through a required impedance circuit. The crossfeed is supplied to a second signal system for amplifying a playback signal, thereby canceling the influence of the crossfeed from the recording head on the playback head only in the second signal system. Feed cancel device.