JPS5984332A - Device for automatically adjusting azimuth of reproducing head - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution and reduce the cost of the titled device, by generating an inversion signal which inverts a signal to high level and low level in response to the advance and delay of the signal phase and adding the inversion signal to an azimuth adjusting means. CONSTITUTION:When the azimuth of a reproducing head 1 is not under an appropriate condition and the phase of one phase comparison signal advances than that of the other phase comparison signal, the level of an inversion signal at the output point O1 of a phase comparison circuit 8 becomes high level Va by a high-level signal from the output terminal Q1 of a flip-flop circuit FF1. When the level becomes high, a dead zone setting circuit 15 outputs a high-level signal and closes the analog switches SW1 and SW2 of a switching circuit 16. In response to the closing, the high level Vb of the inversion signal is inputted into the switching circuit 16 and added to an azimuth adjusting means thus, the azimuth of the reproducing head 1 is adjusted. When such an arrangement is made, the circuit constitution can be simplified and the cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording/reproducing apparatus and to an improvement in an automatic azimuth adjustment device for a reproducing head thereof.

For example, if the azimuth of the playback head is not appropriate, there will be a phase shift between the left and right recording tracks (tj) and the high-frequency playback characteristics will deteriorate. For example, a device for adjusting the azimuth of reproduction to rad using a signal has been proposed in Japanese Patent Publication No. 14597/1983.

This device divides the recording track of any channel of the recording tape to be played back, for example, the right channel, into a ten-half part and an F-half part by means of a specially constructed playback head, scans them individually, and obtains data from each part. f) Phase difference light between raw signals? detection(
-1 The iCL automatically adjusts the azimuth of the playback head based on this phase difference.

However, with such conventional devices, it is necessary to detect the amount of phase difference between the reproduced signals, but the amount of phase difference obtained by skillfully dividing the recording trunk of one channel and detecting gaps is usually extremely small. If an attempt is made to adjust the azimuth of the control head using a feedback system (11 threads) based on From a practical standpoint, the problem is practicality.

The present invention has been made in order to improve the performance of such a conventional device. the first and second formed from
Compare the phases of the digit fl=I comparison signals, generate an inverted signal that inverts to a high level and a low level in response to the lead and lag of the digit from 1 to the other, and generate the inverted signal. ?
The azimuth adjustment means is configured to adjust the azimuth of the reproduction to rad by adding it to the azimuth adjustment means, and the azimuth adjustment means includes a dead zone setting circuit that monitors integral information of the inverted signal to start and stop the adjustment. , the input detection sensitivity of the dead zone setting circuit can be changed.
It is characterized by being considered a Noh play.

The present invention will be described below with reference to the embodiments shown in the drawings. In FIG.
Only the parts corresponding to the sound tracks are shown. ), the audio signal recorded on the recording track of the right channel of the recording tape is divided into, for example, the upper half and the T half and scanned,
Each coil a.

The reproduced signals 8a and Sb are obtained at 8b. The synthesized signal Sa + sb of the reproduced signals is a right channel reproduced signal reproduced by a normal reproduction head, and is sent as an audio 1 regeneration signal from an output terminal O to a modified audio signal reproducing circuit (not shown).

In addition, the composite signal Sa + -8b and the signal sh are azimuth adjustment No. 4F4 and No. 1. After the signals are made to the same level by amplifiers 2 and 3, they are passed through a bandpass filter 4.
. and diode l) 1°D2
The positive component of each rectangular wave signal passing through is inputted to the phase ratio 1 circuit 8 as a phase comparison signal.

The phase comparator circuit 8 compares the phases of the bite signals with the above-mentioned two phase ratios, and in response to the phase lead and lag with respect to the other force, the level state is inverted to the Akane level Va or to the low level O. A signal is generated at its output point 01. The phase comparator circuit 8 includes a D-type flip-flop circuit FFl and a NOR circuit M.
N01 (and consists of diodes D3e and D4, the flip-flop circuit FF1 has a data terminal DI to which the output of the waveform conversion circuit 7 is inputted via the diode DI, and an output of the hourglass conversion circuit 6 is inputted via the diode 1)2. has a clock terminal CL, a reset terminal f(1), an output terminal Q1, an inverted output terminal Ql, and a set terminal 81 grounded. Terminal Qx is NOR circuit N
The output terminal of the NOR circuit NOH is connected to the output point 01 via the diode D4. The reset terminal 1 (1 and the input terminal of the other output of the NOR circuit NOH are respectively D, which will be described later).
It is connected to the output terminal Q2 and the inverted output terminal Q2 of the type flip-flop circuit FF2.

The level detection circuit 12 sets the phase comparator circuit 8 in the active state when the internal node 1 is reproducing the audio signal, that is, when the level of the reproduced signal is equal to or higher than a predetermined value D.
The detection sensitivity switching circuit 13 is controlled via the time constant circuit 14 in response to the presence or absence of the audio raw signal, and the dead zone setting circuit 1
This is to raise or lower the detection sensitivity of step 5. The level detection circuit 12 is an l) type flip-flop circuit 1. IP+
The reset 91^1 child R2 is provided with the positive component of the composite output obtained by combining the outputs of the bandpass filters 4 and 5, and its data terminal D2 and clock terminals CJ, i2 are both grounded, and their set terminal S2 is connected to the power supply +VCC. Here, D type flip-flop circuit II''1゛1
and pl+'2 is DUAL, J)-TYPE 1;'LLP FL( commercially available from Tokyo Shibaura Electric Co., Ltd.
JP (product number TC4013BP) is preferably used.

The time constant circuit 14 includes resistors H1, n2 . It consists of It3, capacitor C1, and diode D5, and in response to the output state of output terminal Q2 of FF2, diode J)5 and resistor R
The charge of capacitor C1 via 2 or resistance J? 1 and R
The capacitor C] is discharged through the capacitor 3, and the capacitors and resistors are set so that the charging time is short and the discharging time is long.

Detection sensitivity switching circuit] 3 is a switching transistor Tr
1. Diode'') 6. NAND circuit 1dN1 :ry Consists of capacitors C2, C3 and resistors R4, r<5, etc., especially the ratio Jl! l! 2) The resistor R5 and capacitor C3 connected to the power point 01 and the ground +UJ constitute a JQ, i, j, division circuit that provides integral information of the inverted signal.

The further unit zone setting circuit 15 is a transistor Tr2.
? Tr3 r ”r4, diode I) 7 etc./A
Z) Compares the integrated output of the first integrating circuit with the reference level vb supplied from the reference power supply +vb to the base of the transistor Tr4, and sets this integrated output level to the reference level vb. On the other hand, when it does not fall within the dead zone level, a low level signal is output and the analog switch SW2 of the switch circuit 16 (described later) is closed, and when it falls within the dead zone level, a low level signal is output. and release these wigs.

Note that the dead zone level in this embodiment is set to vb±1.2 volts by the I[+ direction-position of the transistors Tr2 to Tr4 and the diode J)7.

The output point 01 of the phase comparator circuit 8, which is connected to the reference power supply +vh through the resistor 1 (o, is connected to the switch circuit) 6. The connection point between the analog switches SW1 and sW2 and the base k
m H'i, capacitor C4 & connected between source + vb
*: A second integration circuit is formed with the resistor I (6).The resistor II7 connected in parallel to the capacitor C4 is a discharge resistor when the analog switches 8W1 and 8W2 are open.

8I! The output of the 4λ circuit of 2 is an analog switch SW,
.

When the plate 2 is equalized, it is supplied to a motor drive circuit 9, and the output of the circuit 9 is a drive control motor 10x for azimuth adjustment that changes the azimuth of the reproducing head.

The motor drive circuit 9 includes an operational amplifier 17 and a transistor Tr.
5. The Ill power of the second integrating circuit is input to the (=) input terminal of the operational amplifier 17, which is configured with Ill, 6 and resistors 1 (8, It9, etc.) and whose (+) input terminal is connected to the reference a+vb. Ru.

The pressure level of the power supply ±νCC to which each collector of the transistor Lf5*i'f6 is connected is the same as the above-mentioned D.
type flip flop times jl? 51'F] is set equal to the level Va of the high-level signal outputted by the high-level signal VH, and the heavy pressure levels VH and VI:+ are set in the relationship Va=2vb.

In addition, the analog switch 8W1°S of the switch circuit 16
When W2 is open, the (-) input terminal of the operational amplifier 17 is maintained at level VbK, and the resistor 1 (8) and the resistor 11μ of R9 are set equal so that the motor drive output becomes zero.

FIG. 2 shows an example of the azimuth adjustment mechanism. When the motor 10 rotates, the pulley 11b and the gear 11 are connected to each other via the belt 11aY.
c rotates, and the lever 11 d, one end of which meshes with the gear 11 c, rotates to rotate the pivot HeY), and the link IJf is rotated.
'Move the wedge through g. As a result, the reproducing head 1 rotates about the fulcrum P by t[/Ic, and its azimuth changes.

In the second configuration, when a back door reproduction signal is obtained from the reproduction head 1 and a high level signal is applied to the reset terminal R2 of the flip-flop circuit Flil 2 of the level detection circuit 12, the output terminal Q2 of FF2 and the inverted output Terminal Q2
The respective output states change from the cylinder level and low level states to low level and high level states, respectively, and the input of the flip-flop circuit FF of the phase comparison circuit 8 and the glue set terminal R1 changes from the quotient to the low level signal. , also the NOR circuit N
Since the inputs of the OH input terminals change from low to high level signals, one phase comparison signal (clock terminal C'10 input) corresponds to the other phase comparison signal (data terminal D10 input). F depending on the phase lead or lag of
The quotient level va and the low level 0 <g signal, or the low level and the crystal level signals are output to the output terminal Q1 of F1 and the inversion amount input terminal Q.

On the other hand, in response to the output change from high level to low level at the output terminal Q2 of Fp2, the capacitor C1 of the time constant circuit 14 is connected to the resistor n3. Discharge is started via nl, but since the discharge time is set long, after this output change, it will continue for a predetermined time Ill (for example, 10 sec).
The switching transistor Tr1 of the detection sensitivity switching circuit 13 is kept in the on state until the time period elapses. This maintains the grounded state of the capacitor C2 via the high resistance R4)i, so that the detection sensitivity of the dead zone setting circuit 15 remains high.

Here, if the azimuth of the reproducing head I is not in a proper state and the phase of one of the phase comparison signals mentioned above is ahead of the other, the level of the inverted signal at the output point O1 of the phase comparison circuit w18 is the output of FF1. The high level signal from the terminal Q1 causes the high level Va. As a result, the integral output level of the second integrating circuit gradually decreases from the reference level vb to V-^, and when it exceeds the dead zone upper limit level Vb + 1.2 volts, the dead zone setting circuit 15 outputs a high level signal sound. Analog switch 5Wx of switch circuit 16
Close t8W2. In response to this closing, the high level vb of the inverted signal is input to the switch circuit 16, and the integrated output of the second integrating circuit exceeds the reference level vb, so the azimuth adjustment motor lO rotates in one predetermined direction. Start and move the playback head IFc' in the direction where its azimuth is appropriate.

Then, when the azimuth of the reproduced signal "H" exceeds the proper position and the phase relationship of the phase comparison signal is reversed, the level of the inverted signal is inverted to the low level 0. As a result, the output level of the second 11-bit circuit is When this falls below the reference level vb, the motor lO reverses and returns the azimuth of the playback head 1 to the proper position 161. In this way, the playback head l vibrates to its proper azimuth position l), and its amplitude also becomes smaller as the inversion repetition of the inverted signal becomes faster <1'x.

On the other hand, the output level of the 10th) integrating circuit also gradually decreases in response to the inverted line return of the inverted signal, and when it enters the dead zone, the dead zone setting circuit 15 outputs a low level signal and switches the analog switch SWI TSW2. Open.

As a result, the motor IO stops, and the reproducing head 1 is brought to rest at a substantially appropriate azimuth position.

Conversely, even if the operation is started from a state in which the phase of one phase comparison signal lags that of the other, the rTj raw head will be kept at approximately the correct azimuth position (fl, Ic), but in this case it will be dead. Zone Shimo 1 Sawa level vb -1,
Analog switch sw1 in relation to 2 volts.

SW2 is turned on and off.

Such azimuth adjustment is sufficiently completed within the above-mentioned time TI in which the detection sensitivity is maintained at a high state, and after the time 1+1 has elapsed after the detection of the old voice reproduction signal, the detection sensitivity switching circuit 1
The switching transistor Tr1 of No. 3 is turned off, the capacitor C2 is connected in parallel to the capacitor C3, and the detection sensitivity of the dead zone setting circuit 15 is reduced. This results in
A playback head with an appropriate azimuth is prevented from moving unnecessarily in response to an exceptional phase shift between phase comparison signals due to tape bending or the like.

Moreover, this state of low detection sensitivity is caused by the level detection time tN11.
2 does not detect the audio reproduction signal and the low level signal is output from the output terminal Q2 of the lower k2, it is immediately released. Therefore, the detection sensitivity is always returned to the normal state at the beginning of an unrecorded part between songs, so for example, if tape playback is started from a recorded part at the end of a song, immediately after that, the detection sensitivity Even when the recording section is used, the azimuth of the playback head l is adjusted to the correct position by the sound/voice reproduction signal from the recording section at the beginning of the next song.

As described above, according to the device of the present invention, the azimuth adjustment of the 41) head is automatically adjusted by detecting the phase lead or lag of one of the comparative No. 41s obtained by dividing and reproducing the same recording trunk with respect to the other. I'll tell you what to do.

In addition, without driving the interview motor with reverse rotation No. 46,
Since it is driven via a switch circuit,
In addition to preventing the playback head from being forced to move to 7 other than when adjusting the azimuth, the δ-molecular or low-level inversion signal is not input directly to the motor drive circuit, but is input through the integral circuit. This prevents the motor from reaching and rotating violently at the start of adjustment, and prevents the audio being output to the circuit (
++ The influence on the raw signal can be suppressed.

In addition, Fig. 3 shows the actual 410//i of the 4i4 comparator circuit.
+j example, li"li'3 is its data terminal JJ3
This is a D-type flip syrup circuit in which a phase ratio soft signal is input to each of the clocks 3 and 3, and the outputs of the output terminal Q3 and the inverted output terminal Q3 respectively receive both phase comparison signals. 1.l1il of level detection circuit L2
It is input to the NAND circuit N1+N2 along with the inverted output of 2,
The output of NAND circuit N1 is inverter ■, diode D8
By the way, the output of 2 to the NAND circuit is Dimate D9
are outputted to output point 03 via respectively.

Therefore, this output point 03 has a mo high level (N5Q
An inverted signal of a low level (repetitive signal of a reference level and a low level) is output.
do.

Further, the apparatus of the present invention is not limited to the above-described embodiment, and it goes without saying that the width of the dead zone, etc. can be set freely.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the circuit configuration of the instant Mi example of the present invention;
The figure shows an example of the rjimasu adjustment mechanism used in the present invention.1-
3 and 3 are circuit diagrams showing another embodiment of the phase comparator circuit. ■...Playback head, 2, 3...Amplifier, 4.5...
・Band filter, 6, 7 pass waveform conversion circuit, 8... Phase comparison circuit, 9... Motor drive circuit, 10... Motor, 12... Level detection circuit, 13... Detection sensitivity 9
J conversion circuit, ■4... Time constant circuit, 15... Dead zone setting circuit. ≠Figure 2Figure 3

Claims (2)

[Claims] (1) Forming first and second phase comparison signals giving azimuth information of the playback head from divided playback signals obtained by a playback head that plays back the same recording track of the recording tape in the width direction of the recording track. , the first
and a second phase comparison signal, generates an inverted signal that inverts to a high level and a low level in response to the phase lead or lag of one of the signals relative to the other, and applies the inverted signal to the azimuth adjustment means. ′, the azimuth of the reproducing head is adjusted to Fl, and the azimuth adjusting means includes a dead zone setting circuit that monitors integral information χ of the inverted signal in order to start and stop adjustment;
An automatic azimuth adjustment device for a reproducing head characterized in that the dead zone setting circuit has a switchable detection AeG&. (2) The azimuth adjustment device for a reproducing head according to claim 1, wherein the human power detection sensitivity switching circuit lowers the detection sensitivity every time the reproduction signal is obtained and after R is light for a certain period of time.