JPS63288450A - Method for adjusting atf gain of rotary head type tape recorder - Google Patents

Abstract

PURPOSE:To correct the slippage of an ATF error signal property simply in short time by adjusting the gain on each head of an error signal amplifier so that the addition level of the crosstalk component of adjacent two tracks may become of a reference level. CONSTITUTION:An AFT error signal is formed based on the crosstalk component corrected so that the S characteristic of the ATF error signal set in the slope becoming in 1/2 of a standard level N at the position of the center of a tracing track may become the reference characteristic. Therefore, the stage to reproduce the reference tape for adjusting a peak level and to adjust the set-in on each head of a reproducing signal amplifier with a reference level K as the aiming level and the state to adjust the set gain on each head of the error signal amplifier in (2K-N)/(2K-M) times so that an addition level M may become of the standard level N by reproducing the reference tape for slope adjustment are executed in order. The slippage in the ATF error signal characteristic based on the dispersion in the side lead effect of both rotary heads is thus adjusted simply in a short time and corrected accurately.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is directed to the detection of ATF error signals caused by variations in head characteristics of a rotary head type tape recorder that performs area-divided ATF tracking servo, such as a rotary head type digital audio tape recorder. The present invention relates to an ATF gain adjustment method for a rotary head tape recorder that adjusts and corrects deviations in characteristics.

[Conventional technology]

Conventionally, a rotary head type digital audio recorder (hereinafter referred to as DAT) has been described, for example, on pages 109 to +14 of the April 1987 issue of the magazine "Television Technology" (Denshi Gijutsu Publishing Co., Ltd.). A pair of rotary heads for recording and reproducing having mutually opposite azimuth angles, which are mounted at positions 180 degrees apart on the rotary cylinder, alternately rotate a magnetic tape that is wound around the rotary cylinder at 90 degrees and runs. It is configured to perform helical scanning, recording, and playback.

Note that in the case of R-DAT, the gap width between both heads is set to about 1.5 times the track pitch (track width).

For example, as stated in the specification and drawings of Japanese Patent Application No. 1988-80818, at the time of recording,
PCM such as audio information is recorded on each track of the tape formed by one scan of both rotary heads.
A recording information signal consisting of a signal, a pilot signal for tracking control, and a synchronization signal as a sampling reference for the pilot signal are time-divisionally recorded in a predetermined format, that is, an area division type format.

By the way, in the above-mentioned area square format, an ATF area of a certain length is independently provided at the beginning and end of the trace of each track of the tape, in which the above-mentioned pilot signal, synchronization signal, and erase signal are recorded. An area for recording the PCM signal is provided between both tracking areas.

In addition, the recording pattern in the ATF area is a 4-track complete tracking format, that is, the same pattern appears every 4 tracks, and the recording pattern is recorded in the playback signal based on the detection of the synchronization signal of the trace track included in the playback signal. The recording lengths and recording positions of the synchronization signal, pilot signal, and erasure signal are set to be different so that the crosstalk components of the pilot signal from each of the two tracks adjacent to the included trace track can be sampled.

The synchronization signal is 52m67KHz for each track.

78400 KHz alternately, pilot signal and cancellation signal are 180.67 KHz and 1.568 KHz
MHz, and the synchronization signal and pilot signal are set at frequencies sufficiently lower than the frequency band of the PCM signal so that they can be extracted by frequency separation.

In other words, the track pattern of the R-DAT tape is as shown in Figure 3, (A).

CB) are reverse azimuth tracks formed alternately on the magnetic tape by recording scans of both rotary heads; (TI)
, (T2) are the beginnings of each track (A) and (B).

This is an ATF area provided independently at the end, and there is a P between areas (Tl) and (T2) of each track (A) and (B).
A recording area for CM signals is provided.

Also, (8a) and (8b) are 521L67 KH7,,
Recording position of each synchronization signal of 78400KH7, (P
) and (E) indicate the recording positions of the pilot signal and erase signal, respectively.

Additionally, τ in the figure indicates the length of one block of the PCM signal,
Both areas (TI) and (T2) are each set to 5τ.

Then, during playback, the playback signals alternately output from the surface rotating head by scanning are input to the tracking device, and the synchronization detection section of the device digitally detects the playback of the synchronization signal of the trace track. A sampling pulse of the Talostok component of the pilot signal from each of the two adjacent tracks of the trace track included in the reproduced signal is formed by timing control based on .

Furthermore, the sampling circuit section of the tracking device samples the playback signals in areas (TI) and (T2) that have been filtered from the playback signal based on the sampling pulse of the synchronization detection section, and extracts the pilot signals from each of the two adjacent tracks. In addition to extracting the crosstalk component, the signal of the level difference between the two extracted crosstalk components,
That is, a signal that changes in a figure-8 characteristic according to tracking deviation is formed as an ATF error signal for tracking servo.

After the ATF error signal from the sampling circuit is amplified by an error signal amplifier for output amplification, it is supplied to the capstan motor drive circuit to control the rotational phase of the capstan motor to control the tape running phase. death,
Tracking of the surface rotation head is controlled by a so-called ATF racking servo, and the surface rotation head is brought into an on-track state.

By the way, the pilot signal of the trace track is Po
, if the crosstalk components of the pilot signals from two adjacent tracks are PI and P2, the two adjacent tracks are tracks with opposite azimuth angles to the trace head, so the levels of both crosstalk components PI and P2 are equal to the pilot signal PO.
becomes lower.

In addition, the levels of the signal component and crosstalk component of the trace track change depending on the tracking position of the surface rotating head, and the levels of the signal P o (pylon) and both crosstalk components PI and P2 change depending on the tracking position of the trace head. , change as shown by the solid line pO and the solid lines pl and p2 in FIG. 4, respectively, and at this time, the ATF error signal becomes as shown in FIG.

In Figures 4 and 5, 0° indicates the center position of the trace track at the azimuth angle of the trace head, and ±180° indicates the center position of each of the two adjacent tracks at the opposite azimuth angle to the trace head. The range of ±90° is one track pitch of the trace track.

As is clear from FIGS. 4 and 5, the trace head is controlled to be on-track to the trace track by performing tracking control so that the level difference force between the biconvex stalk components PI and P2 becomes O. .

[Problem that the invention seeks to solve]

By the way, the side lead effect of the surface rotation head.

In other words, the effect of reproducing and outputting both crosstalk components PI and P2 from adjacent tracks with opposite azimuths varies from head to head. Therefore, even at the same tracking position, the levels of crosstalk components PI and P2 vary depending on the head. are different.

Assume that the reproduction output characteristics of each rotating surface head for reverse azimuth tracks, that is, the off-track output characteristics, become as shown by the solid line and the dashed-dotted line in FIG. 6, respectively, due to variations in the side read effect.

Note that 00 in Fig. 6 indicates the center position of the off-track with the opposite azimuth angle to the head, that is, the position of ±180° in Figs. Each center position is shown.

At this time, the range from approximately ±90° to ±1800 in Fig. 6 is particularly important for actual tracking control, and the level in this range, that is, the level of crosstalk component P+ or P2 of tracking control, is the slope of the slope. Based on variations, for example, if the AT
The character 8 characteristic of the F error signal deviates from the reference characteristic and varies, making it impossible to perform good tracking control.

Therefore, when manufacturing R-DAT, etc., the gain of the tracking device is adjusted for each head, the servo gain, that is, the ATF gain is adjusted, and the variation in the characteristics of the ATF error signal is corrected. It is necessary to adjust and correct deviations in ATF error signal characteristics due to variations in lead effects.

A simple way to adjust the ATF gain is to play the tape while controlling tracking, and at this time,
Crosstalk component PI using an oscilloscope, etc.
Based on the measurement of P2, the crosstalk component PL' in the trace of both rotary heads or the level of a specific tracking position of P2 is translated in parallel, and the amplifier gain of each head of the reproduced signal is adjusted. In this case, even if the crosstalk levels of points a and b or points a/ and b/ match,
Solid line in Figure 6.

Since the slope of the one-dot chain line is not adjusted, it is impossible to accurately correct deviations in the characteristics of the ATF error signal, and there is a problem in that the tracking characteristics cannot be properly corrected.

On the other hand, a method to accurately adjust the ATF gain is to use a complex analysis device called a servo analyzer.
Based on the analysis results of the tracking response when a disturbance is applied to the tracking control, fine adjustment of the amplifier gain for each head of the reproduction signal and the ATF error signal is repeated many times. One possible method is to adjust all characteristics, including the gradients of the solid line and the dashed-dotted line, to the standard characteristics, but in this case, it would take a lot of time and effort to adjust the amplifier gain for each head in order to make complete adjustments.
For example, it takes tens of minutes or several hours, and the adjustment operation becomes complicated, so there is a problem that it cannot be applied when a simple adjustment in a short time is required, such as during manufacturing.

[Means for solving problems]

This invention was made with the above points in mind,
Independent AT of each track formed by helical scan
A magnetic tape on which a pilot signal for tracking control and a synchronization signal as a sampling reference for the pilot signal are recorded in the F area in a predetermined format is used for recording and reproducing at mutually opposite azimuth angles with a gap width greater than the track width. Helical scanning is performed alternately by a pair of rotating heads,
During playback, a tracking device to which the playback signals of both heads are input detects the playback of the synchronization signal of the trace track at the azimuth angle of the trace head, and the trace included in the playback signal is detected based on the detection. A crosstalk component of the pilot signal from each of two adjacent tracks at opposite azimuth angles to the head is sampled, and an ATF error signal for tracking servo is formed based on the level difference between the two sampled crosstalk components, and the error signal is ATF error signal characteristics based on variations in the side read effect of the two heads of a rotary head type data recorder that controls the running phase of the tape and the tracking of the two heads by controlling the phase of the capstan motor based on the signal. In the ATF gain adjustment method for a rotary head tape recorder that adjusts and corrects deviation, the tracking device includes a sampling circuit for sampling both crosstalk components by amplifying the playback signal with a gain set for each of the heads by switching the gain. and an error signal amplifier that amplifies the error signal by a set gain of each of the two heads by gain switching and outputs the error signal to the drive circuit of the capstan motor during adjustment. A reference tape for peak level adjustment for each head, on which the pilot signal is recorded only on tracks at opposite azimuth angles to each head, is played back with the running phase control stopped, and during the playback, the playback signal is The level of the pilot signal in the reproduced signal via an amplifier is measured to detect the crosstalk peak level of each of the two heads, and the level of the pilot signal of the reproduced signal amplifier is adjusted so that the peak level becomes equal to the reference level Iv. After adjusting the set gain of each head and adjusting the reproduction signal amplifier, at least the AT of each track is adjusted.
The standard tape for gradient adjustment on which the F area is normally recorded is played back by controlling the running phase, and during the playback, the addition level M of the two crosstalk components of each of the two heads is measured, and the addition level M of the two crosstalk components of each of the two heads is measured. Level M is standard rep/I/N
The set gain of each head of the error signal amplifier is set to (2K-N)/
Rotating head type data recorder (7) A characterized in that the ATF error signal characteristic deviation is adjusted and corrected by adjusting the ATF error signal characteristic by (2K-M) times.
This is a TF gain adjustment method.

[For production]

Therefore, by adjusting the set gain of the reproduced signal amplifier for each head, the characteristics of the crosstalk component of the reproduced signal can be changed, for example, from the peak levels of the solid line and the dashed-dotted line in FIG. 6 to the reference level K in FIG. 1(a). Then, by measuring the addition level M, a level that is twice the crosstalk component at 00° in FIG. 1(b), that is, the center position of the trace track, is measured. At this time, the addition level /v M Fi changes at twice the slope of the characteristic of the crosstalk component based on the side lead effect.

Then, by adjusting the set gain for each head of the error signal amplifier to (2K-N > / (2K-M > times the current gain) and adjusting the addition level M to the standard level N, , the peak level becomes the standard level K and the standard level N at the center position of the trace track.
Characteristics set to a slope of 1/2K, that is, ATF
An ATF error signal is formed based on the crosstalk component of the characteristic corrected so that the figure 8 characteristic of the error signal becomes the reference characteristic.

Therefore, the process of playing back the reference tape for peak level adjustment, adjusting the set gain for each head of the playback signal amplifier using the reference level K as the target level, and the step of playing back the reference tape for slope adjustment, and setting the addition level M as the standard Variations in the characteristics of the ATF error signal can be corrected by simply performing the steps of adjusting the set gain for each head of the error signal amplifier by C2K-N >/< 2K-M) times so that the level /l/N is achieved. As a result, deviations in ATF error signal characteristics due to variations in the side read effects of both rotary heads can be easily adjusted and accurately corrected in a short time.

〔Example〕

Next, the present invention will be explained in detail with reference to FIGS. 1 and 2 showing one embodiment thereof.

Figure 2 shows the configuration of the R-DAT tracking device during adjustment. In the figure, (1) is a playback signal input terminal, which is connected to a terminal for recording and playback at mutually opposite azimuth angles provided on the rotating cylinder. A pair of rotating heads (hereinafter referred to as A).

The reproduction signals of the B head (referred to as the B head) are combined and inputted via the head changeover switch. Reference numeral (2) denotes a head switching signal input terminal, into which a head switching signal whose level is inverted every half rotation of the rotary cylinder in synchronization with the trace start ends of heads A and B is input.

(3) is a playback signal amplifier connected to the input terminal (1), which amplifies and outputs the playback signals of the A and B heads.
7 door amplifiers (4B) and (4b) to B, and both amplifiers (4a
).

(4b) Gain adjustment variable resistors (5B) and (5b) that adjust the respective output gains, and a switch that switches and outputs the output signal of the sliding piece of the variable resistors (5a) and (5b) according to the head switching signal. It consists of (6).

(7) is a low-pass filter connected to the switching piece of the switch (6), which frequency-separates and extracts almost only the pilot signal component for tracking control of the reproduced signal output from the switch (6).

(8) is an envelope detection circuit connected to the filter (7), which performs envelope detection on the output signal of the filter (7) and outputs the envelope detection circuit. (9) is a sampling section connected to the detection circuit (8); The second sample-and-hold circuit (10, consisting of αυ and a subtracter@) samples the crosstalk components from two adjacent tracks included in the playback signals of the A and B heads using the pre-hold (described later), and An ATF error signal of the level difference between the talk components is formed and output.

a3 is an error signal amplifier connected to the sampling section (9), which consists of a gain control amplifier α for amplifying the ATF error signal, a resistor αQ is provided between the input terminal of the amplifier Q4) and the ground, and , amplifier σa
A variable resistor (168) for adjusting the A head gain is provided between the input terminal and the output terminal of the variable resistor (168).
16a) in parallel with a variable resistor (+
6b) and the head switching signal.

A variable resistor (16B) is provided in series with a switch aη to be turned off, and is turned on or off based on the on/off state of the switch αη.

(16b) The ATF error signal for each head is amplified and output using the gain set by adjusting each.

(to) is an error signal output terminal that outputs the ATF error signal of the amplifier Q5 to the drive circuit section of the capstan motor.

09 is an equalizer circuit for waveform equalization connected to the input terminal (1), and 翺 is a comparator for digital conversion that binarizes the output signal of the equalizer circuit aI, consisting of a zero-cross comparator. (211 is a control unit connected to the comparator ω, which is formed using a microcomputer, etc., and synchronizes the trace track from the output signal of the comparator based on the head switching signal of the input terminal (2). Digitally detects signal reproduction and uses sample and hold circuit aO1
αυ is a crosstalk component PI from two adjacent tracks,
Each of the sampling pulses SPI and SP2 of P2 is output.

@ is an adder that adds the output signal of the detection circuit (8) and the output signal of the sample-and-hold circuit 00, and a third sample-and-hold circuit that samples the output signal of the adder ■ using the sampling pulse SP2K; Outputs a signal with the addition level of crosstalk components from the track.

(241, +251 are the filter (7) and the first and second terminals connected to the output terminals of the sample and hold circuit, respectively.
These are test terminals, and can be connected to, for example, a spectrum analyzer and a voltmeter.

Then, the reproduced signals of the A and B heads are inputted to the amplifiers (4a), (4b) and the equalizer circuit 00 via the input terminal (1), and at this time, the switch based on the head switching signal of the input terminal (2) Based on the switching of (6), when the A head playback signal is input, the amplifier (4a
) is selected and output to the filter (7),
When the playback signal from the B head is input, the amplifier (4b)
The output signal of the head is selected and output to the filter (7), and the reproduced signal of the A and B heads is transmitted to the resistor (5) by the amplifier (3).
B) and (5b), the signal is amplified with a gain set for each head.

Roughly speaking, the frequency component of the pilot signal, that is, the pilot signal component, is extracted from the input reproduced signal by the filter (7), and the filter (7) extracts the frequency component of the pilot signal from the input reproduction signal, and the filter (7) extracts the frequency component of the pilot signal from the input reproduction signal.
Then, the extracted pilot signal component is output.

Then, by the envelope detection of the detection circuit (8), the sample and hold circuit α0. subtractor 0
a. An envelope detection signal of the pilot signal component included in the reproduced signal is output to the adder.

On the other hand, the reproduced signal whose waveform has been equalized by the equalizer circuit a9 is binarized and digitized by the comparator (1), and is input to the control section 211.

By the way, the control unit 21J includes a synchronization pattern detection means for digitally detecting the pattern of the synchronization signal from the digital signal of the comparator, and a crosstalk component PI, based on the reproduction of the synchronization signal based on the detection by the detection means. It is provided with a sampling pulse forming means that completely forms and outputs the sampling pulses SP l and SF3 of P2.

When the digital signal of the comparator (E) is input to the synchronization pattern detection means, the detection means detects the frequency (9,408
The digital signal of the comparator is sampled at a frequency (MHz), the inversion period of the digital signal of the comparator is detected, and the inversion period is the frequency of the synchronization signal (522, 67K).
A synchronization detection pulse is generated every Hz or 78400 KI (z) period.

Furthermore, the synchronization detection pulse is inputted to the sampling pulse forming means, which determines the trace track based on the head switching signal of the input terminal (2) and detects the period ≠ order based on the counting of the synchronization detection pulse. Toyoshi,
At least A of each track in the track pattern of Figure 3.
When playing back a regular magnetic tape on which TF areas (Tl) and (T2) are normally recorded, trace track areas (TI) and (T2) (-based on the detection of playback of each synchronization signal) and the area of 2 adjacent tracks (
TI), (T2) Sampling pulses SPI and SP2 are formed at the timing when the crosstalk components of the respective pilot signals are reproduced and input.

In other words, as is clear from Fig. 3, the track (A
), (B), the length of the synchronization signal of the area (TI) is lτ
Then, the length of the synchronization signal in area (T2) will also be Iτ, and if the length of the synchronization signal in area (TI) becomes 0.57, the length of the synchronization signal in area (T2) will also become 0.57. Become.

Furthermore, when the synchronization signal begins to be reproduced and the synchronization detection pulse begins to be output, the output signal of the detection circuit (8) is transmitted to one of the two adjacent tracks, that is, the area (Tl) of the track traced before the trace track. ) or (T2
) becomes a crosstalk component of the pilot signal, and when approximately 2τ has elapsed since the start of input of the synchronization detection pulse, the output signal of the detection circuit (8) is traced to the other of the two adjacent tracks, that is, the next trace track. Track area (TI).

(T2) Becomes a crosstalk component of each pilot signal.

Furthermore, the head switching signal of the input terminal (2) is A.

Since it changes in synchronization with the head switching of the B head, the trace track changes to the track (
It is possible to determine in advance which one is A) or (B).

Therefore, the sampling pulse forming means predicts the frequency of the synchronization signal reproduced from the trace track by determining the trace track based on the head switching signal, and forms the sampling pulse BP+ when the synchronization detection pulse starts to be input. and outputs it to the sample-and-hold circuit αq, and starts counting the synchronization detection pulses.

Based on the determination of whether the count value of the synchronization detection pulse reaches the respective count values of 0.5τ and lτ, it is determined whether or not the synchronization signal is being reproduced, and the length of the synchronization signal is 0.57, 1τ, determine the trace track based on the identification of the length of the synchronization signal only when reproducing the synchronization signal, and start sampling when 2τ has elapsed from the start of counting of synchronization detection pulses. Pulse 8P
2 is formed and output to the sample hold circuit αυ,■.

Therefore, when a regular magnetic tape is reproduced, based on KU and sampling pulse 8P+, the sample pre-hold circuit (IG) outputs the adjacent two signals output from the detection circuit (8).
Crosstalk component of the pilot signal on one side of the track,
For example, the crosstalk component P1 indicated by the solid line pl in FIG. 9 is sampled and held.

Then, since the output signal of the detection circuit (8) is subtracted by the subtracter (a) from the hold signal of the sample and hold circuit C1O, the crosstalk component Pt and the detected signal are sent from the subtracter (6) to the sample and hold circuit q1). When a signal with a level difference from the pilot component output from the circuit (8) is output and the sampling pulse SP2 is output,
Since the pilot component output from the detection circuit (8) is, for example, the crosstalk component P2K of the track on the advancing side of the solid line p2 in the diagram, the signal sampled and held by the sample and hold circuit αυ based on the sampling pulse SP2K is This becomes a signal of the level difference between the talk components PI and P2.

Further, the output signal of the sample and hold circuit αυ is input to the amplifier α→, and at this time, the gain of the amplifier α4 is switched for each head by turning on and off the switch θ'7I based on the head switching signal of the input terminal (2). Well, the amplifier (
), the IIIJ signal of the sample and hold circuit αη is amplified by the resistors (+68) and (+6b) with the gain set for each head. At this time, if the variation in the ATF error signal characteristics is corrected, the amplifier side The signal output from to the output terminal (to) becomes an ATF error signal for tracking servo that changes in a figure-8 characteristic as shown in FIG. 5 in accordance with the tracking deviation of the A and B heads.

Then, the ATF error signal at the output terminal (to) is supplied to the drive circuit of the capstan motor as a phase control signal, and the running phase of the tape is controlled so that the level of the ATF error signal becomes 0, turning on the trace track. The head is controlled to track, and the tracking control of both heads is performed by ATF servo.

By the way, the loop gain of the ATF servo in Figure 2.

In other words, the ATF gain is Habo amplifier (3), (1
It is determined by the set gain of 3, and the resistance (5B) and (5
b), (16a).

If (+6b) is not adjusted, the figure 8 characteristic of the ATF error signal will deviate from the standard characteristic due to variations in the side read effect of both heads, and in this case, the phase control of the capstan motor will fluctuate every time the head is switched. Good tracking control cannot be performed.

Based on the variations in the side read effect, the off-track characteristics of both heads are determined by the solid line 1 in FIG. 6, for example.
In this case, in order to correct the variation in the side read effect of both heads and perform good tracking control, the slope and peak level of the solid line and the dashed-dotted line in the same figure must be set to the specified values. The ATF gain for each head may be adjusted so that the ATF error signal can be obtained with the slope and level corrected, and the figure-8 characteristic of the ATF error signal may be corrected to the standard characteristic.

On the other hand, since the side read effect of both heads is almost the same on the left and right sides of the gap of the same head, for example, the slopes of the solid line and the dashed-dotted line on the left and right sides of the same head are equal, and therefore, Crosstalk component PI, P2
For example, as is clear from FIG. 4, the crosstalk components Pt and P2 are always at the same level at the center of the trace track.

Moreover, when tracking is controlled by the ATF error signal, even if there are variations in the side read effects of both heads, both heads are drawn to the center of the trace track, and the tracking positions of both heads are at least equal to the Rontalk component. P+.

Within the range where P2 can be obtained at the same time, for example +45 in Figure 4
It will be within the range of -45°.

Then, as shown by the solid line and the dashed-dotted line in FIG. 1(a),
Peak level of off-track characteristics of both heads,
In other words, the resistor (5B
), (5b), the crosstalk components PI, P are adjusted while tracking is controlled by the ATF error signal.
When the addition level M of 2 is measured, the addition level tv
M is 00 in the same figure (b), that is, the crosstalk component PI or 2 of P2 at the center position of the trace track.
As the level increases, it changes according to the gradients of the crosstalk components PI and P2, as shown by the solid line and the dashed-dotted line in FIG.

For example, if the tracking position is a variable X, the crosstalk component PI is a variable, and the level of P2 is a variable Y, then
-y component PI, P2 Y=αX+β, Y=-rg
It can be expressed as l + p (α and β are constants),
At this time, α is the slope of the off-track characteristic.

Then, when the peak level of the off-track characteristic is adjusted and fixed at the reference level/I/K as described above, the constant β is -aX'(X' is, for example, the +45° position in Fig. 1 (a)) The addition level M is 2(K-αX')=2β
A constant value of , i.e.
The level will be twice that of Y when .

Furthermore, if we calculate < 2K-M )/2X', we get the gradient α
To correct the slope α to the reference slope, the addition level when x = o' when the slope is the reference, that is, the standard level consisting of the addition level M when using the above-mentioned reference head. Based on N, the gradient α is <2K-N>/<2K
-M) Just multiply it.

After fixing the crosstalk peak level to the reference level K, adjust the resistors (16B) and (16b) to adjust the gain for each head of the amplifier to (2K-N)/(2K) of the current gain. -M), an ATF error signal can be obtained with the slope α corrected to the reference slope.

Note that 00 on the horizontal axis in FIG. 1(a) indicates the off-track center as in FIG. 6, and θ° on the horizontal axis in FIG. 1(b)
indicates the center of the trace track as in the first diagram,
The solid line and the dashed-dotted line in FIG. 2B indicate the crosstalk components PI and P2, respectively.

That is, each of the two heads reproduces a pilot signal of a track at an opposite azimuth angle to that of each of the two heads.
At this time, the resistor (5B), (
5b) to adjust the gain for each head of the amplifier (3), and then measure the crosstalk component Pr and the addition level M of P2 when both heads trace while controlling tracking using the ATF error signal. Then, the gain for each head on the amplifier side is the current gain C2K-N>
/ < 2K-M ) times and resistor (16B) so that the addition rep/I/M becomes the standard level N.

(+6b) If each is adjusted, an ATF error signal is formed based on the crosstalk component with the characteristic that the peak level is equal to the standard level 7 and KK, and the standard level N is 172K at the center position of the trace track. As a result, the deviation in the ATF error signal characteristics due to variations in the side read effects of both heads is corrected.

By the way, the gain adjustment for each head of amplifier (3) is as follows.
For example, it is difficult to perform this with a regular magnetic tape as shown in FIG.

Therefore, the track (B) of the track pattern in Fig. 3,
(A) Prepare a magnetic tape on which a pilot signal of arbitrary length is recorded only on each head as a reference tape (hereinafter referred to as peak adjustment tape) for the peak level mtl of the crosstalk component of each of the A and B heads. .

Then, when the phase control of the capstan motor is stopped, the tape running phase control is stopped, and both peak adjustment tapes are specially reproduced, phase control is not performed.
The tracking phase of the head during playback shifts continuously, and at this time, by measuring the level of the test terminal @ or the output level of the detection circuit (8), heads A and B each track the track at the opposite azimuth angle to both heads. By measuring the peak level when reproducing the pilot signal, that is, the crosstalk peak level, the gain can be adjusted for each head of the amplifier (3).

On the other hand, in order to adjust the gain for each head during the amplifier, use a regular magnetic field in which at least the ATF areas (TI) and (T2) of each track (A) and (B) are normally recorded using the track pattern shown in Figure 3. A tape is prepared as a reference tape for gradient adjustment (hereinafter referred to as gradient adjustment tape).

Then, after adjusting the amplifier (3), for example, head switching is stopped and the gradient adjustment tape is played back, and while the A head is being adjusted, the phase of the capstan motor is controlled by the ATF error signal based on the A head playback signal. During adjustment of the B head, the phase of the capstan motor is controlled by the ATF error signal based on the reproduction signal of B/>rad, and the tape running phase is controlled.

Furthermore, based on the sampling pulse SP2K output from the control section a during playback, the output signal of the adder (2) is sampled and held by the sample and hold circuit (3), and the level of the test terminal (support) is measured and the addition level M By measuring this, it is possible to adjust the gain for each head when using an amplifier.

Therefore, in this embodiment, as a peak adjustment tape for the A head, a magnetic tape is prepared in which a pilot signal is recorded on the entirety of each track CB) and an erase signal is recorded on the entirety of each track (8), and As a peak adjustment tape, a magnetic tape is prepared in which a pilot signal is recorded on the entirety of each track (A), and an erase signal is recorded on the entirety of each track CB), and as a slope adjustment tape,
Area (TI) of each track (A), CB), (
Only T2) was recorded normally.

A magnetic tape is prepared in which erase signals are recorded in the remaining portions of each track (A) and (B).

Also, as a gain adjustment method for amplifier (3) and α1,
After adjusting each head of amplifier (3), adjust the amplifier □
There are two possible methods: □□ to adjust each head, or to adjust amplifier (3) and (13) to head A, and then adjust amplifier (3) and C13 to head B. You can adjust it by
In this embodiment, adjustment is performed using the former method.

Furthermore, in this embodiment, test terminals (24+, +2
Connect the spectrum analyzer and poletometer to 51, crosstalk peak level, and addition level M.
Measure each.

Next, the procedure and operation during adjustment will be explained.

First, in the process of adjusting the gain of the amplifier (3), first, in order to adjust the gain of the A head of the amplifier (3),
The peak adjustment tape of the head is played back, and at this time, the connection between the output terminal O8 and the drive circuit of the capstan motor is opened in advance, and control of the running phase of the tape is stopped.
A drive voltage lower than that during normal playback is applied to the capstan motor to run the tape at a low speed so that the tracking position of the A head shifts slowly and continuously.

Then, the signal of the test terminal (24I), that is, the pilot signal output from the filter (7), is measured with a spectrum analyzer, and the crosstalk peak level obtained when the A head reproduces the pilot signal of the track (B) is measured. At the same time, the resistor (5a) is adjusted, and the gain of the A head of the amplifier (3) is adjusted so that the crosstalk peak level becomes the reference level /L/.

Next, in order to adjust the gain of the B head of the amplifier (3), the B head peak adjustment tape is played back under the same conditions as the A head peak adjustment tape, and the signal at the test terminal - is measured. First, adjust the resistor (5b) and adjust the gain of the B head of the amplifier (3) so that the crosstalk peak level or reference level is reached.

Furthermore, when the gain adjustment of both heads of the amplifier (3) is completed, the process moves on to the gain adjustment of amplifier a3, and at this time, the connection between the output terminal (to) and the drive circuit of the capstan motor is closed. At the same time, switching of the head selection switch or switch (6) at the front stage of the input terminal (1) based on the head switching signal is prohibited, and while the gain of the A head of the amplifier α1 is being adjusted, only the playback signal of the A head is filtered (
7), and during the gain adjustment of the B head during amplification, settings are made so that only the reproduction signal of the B head is input to the filter (7).

First, in order to adjust the gain of the A head of amplifier a3, for example, switch (6) is connected to amplifier (4a).
At this time, based on the playback signal of the A head, the ATF error signal controls the capstan motor position +11t- to control the running phase of the tape. (ATF) Tracking is controlled by a racking servo, and the level in the test terminal is measured with a voltometer to measure the addition level M.

Furthermore, to the measured addition level M and the reference level,
Based on the standard level tv N, adjust the resistor (16B) to adjust the gain of the A head of the amplifier α to the current gain (2
K-N)/(2K-M) times.

In reality, the level of the test terminal is the standard level N.
Adjust the resistor (16a) so that

Next, adjust the gain of the B head when using the amplifier.
For example, if the switch (6) is fixed to the amplifier (4b) side and the slope adjustment tape is played normally, then the resistor (+6b) is adjusted in the same way as the gain adjustment of the A head, and the amplifier σ B head Adjust the gain.

Then, when the gain adjustment of amplifier α1 is completed, the ATF
The gain adjustment is completed, and at this time, the deviation in the characteristics of the ATF error signal due to variations in the side read effects of both heads is corrected.

Therefore, adjust the gain for each head of the amplifier (3) so that the peak level of the signal at the test terminal (2I) becomes the reference level, and then adjust the level of the test terminal (□□□) to the standard level/L. All you need to do is adjust the gain for each head of amplifier 03 so that /N.
Since there is no need to repeat the gain adjustment in step 3, the ATF gain can be accurately adjusted in a short time and easily, and the deviation in the ATF error' signal characteristics due to variations in the side read effects of both heads can be adjusted and corrected. Can be done.

In the case of the above embodiment, the signal inside the test terminal was measured with a spectrum analyzer and the gain of the amplifier (3) was adjusted.
It may also be used to adjust the gain of the detector circuit (
It is sufficient to measure the peak level of the output signal in step 8) with a peak-hold meter or voltmeter, and adjust the measured level to the reference level, which also has the advantage of reducing the cost of the measuring equipment.

Further, in the above embodiment, the present invention is applied to ATF gain adjustment of a DAT, but it can of course be applied to various rotary head type tape recorders that control head tracking by area-divided ATF (racking servo).

〔Effect of the invention〕

As described above, according to the ATF gain adjustment method for a rotary head tape recorder of the present invention, a reference tape for peak level adjustment is played back, and the playback is performed so that the peak level of the played pilot signal becomes the reference level. After adjusting the gain for each head of the signal amplifier, play the reference tape for gradient adjustment, and adjust the gain for each head of the error signal amplifier so that the sum level M of the crosstalk components of two adjacent tracks becomes the standard level N. of the current gain (2K-N
)/C2K-M), it is possible to quickly and easily adjust the ATF gain and correct deviations in the ATF error signal characteristics due to variations in the side read effects of both heads. .

[Brief explanation of the drawing]

FIGS. 1 and 2 show one embodiment of the ATF gain adjustment method for a rotary head tape recorder according to the present invention.
Figures (a) and (b) are waveform diagrams for explaining adjustment, respectively.
Fig. 2 is a circuit block diagram, and Figs. 3 to 6 are diagrams explaining the track pattern of a digital audio tape recorder, a characteristic diagram of a pilot signal component, a characteristic diagram of an ATF error signal, and a diagram explaining variations in off-track characteristics, respectively. It is. (3)...Reproduction signal amplifier, α3...Error signal amplifier, [Yes], (251...Test terminal.

Claims (1)

[Claims] (1) A magnetic tape on which a pilot signal for tracking control and a synchronization signal as a sampling reference for the pilot signal are recorded in a predetermined format in an independent ATF area of each track formed by helical scanning, with a gap larger than the track width. A pair of rotary recording and reproducing heads having a width with opposite azimuth angles perform helical scanning alternately, and during reproduction, a tracking device to which the reproduction signals of both heads are input, traces a trace track at the azimuth angle of the trace head. detecting reproduction of the synchronization signal of , and sampling crosstalk components of the pilot signal from each of two adjacent tracks at opposite azimuth angles to the trace head included in the reproduction signal based on the detection; An ATF error signal for tracking servo is formed based on the level difference between the two crosstalk components, and the running phase of the tape is controlled by phase control of the capstan motor based on the error signal, and tracking of the two heads is performed. An ATF for a rotary head tape recorder that adjusts and corrects deviations in error signal characteristics based on variations in side read effects of both heads of the rotary head tape recorder.
In the gain adjustment method, the tracking device includes a playback signal amplifier that amplifies the playback signal with the set gain of each of the heads by gain switching and outputs the amplified signal to the sampling circuit section of both the crosstalk components; and an error signal amplifier that amplifies a signal with a gain set for each of the heads and outputs the signal to a drive circuit section of the capstan motor, and during adjustment, the pilot signal is transmitted only to tracks at opposite azimuth angles to each of the heads. The recorded reference tape for peak level adjustment for each head is played back with the running phase control stopped, and during the playback, the level of the pilot signal in the playback signal via the playback signal amplifier is adjusted. measuring the crosstalk peak level of each of the two heads, adjusting the set gain of each of the two heads of the reproduction signal amplifier so that the peak level becomes a reference level, and After adjustment, at least the ATF of each track
The standard tape for gradient adjustment on which the area has been recorded normally is played back by controlling the running phase, and during the playback, the addition level M of the crosstalk components of both the heads is measured, and the addition level M is measured. In order to make M become the standard level N, set gains of both heads of the error signal amplifier are adjusted to the current gain (2K-N)/(2K-
M) ATF of a rotary head tape recorder, characterized in that the ATF is adjusted twice to correct the deviation of the ATF error signal characteristics.
Gain adjustment method.