JPH0675318B2 - Tracking device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking device of a helical scanning type magnetic recording / reproducing apparatus.

2. Description of the Related Art Generally, in a helical scan type magnetic recording / reproducing apparatus, when special reproduction is performed, the tape speed is different from that during recording, so that the scanning locus of the rotary magnetic head is different from the recording track and cannot be properly tracked. Further, even in the case of normal reproduction, if the apparatus is different from that at the time of recording, correct tracking may not be possible due to various mechanical precision differences and tape running condition differences.

Conventionally, in order to solve the above-mentioned problems, a rotary magnetic head is configured to be displaceable in the track width direction by a piezoelectric element having a bimorph structure, and the piezoelectric element is generated according to a tracking error signal obtained from the rotary magnetic head during reproduction. A method of tracking by driving the motor is used (for example, Japanese Patent Publication No. 61-27808).

Problems to be Solved by the Invention However, in the conventional method as described above, (1)
Electric power must be supplied to the rotating piezoelectric element, which requires a brush / slip ring, which causes problems in cost and reliability. (2) Generally, piezoelectric elements lack stability and have drifting distortion. Therefore, the head driven by the piezoelectric element can be used only for reproduction, and a recording head is required as a device, so that the number of rotary transformers must be increased and the structure of the rotary drum that requires high precision becomes complicated. Yield deteriorates during assembly,
(3) In addition, since it is difficult to displace the tip of the head parallel to the track width direction, especially when reproducing a signal recorded with a short wavelength, the head touch becomes worse and the S / N of the reproduced signal is increased.
Have problems such as deterioration.

The present invention has been made in view of the above problems, and by dynamically controlling the feeding of the tape, a reproducing scanning head is unnecessary, and a helical scan type magnetic head that enables tracking with a good head touch. A tracking device for a recording / reproducing device is provided.

Means for Solving the Problems In order to solve the above problems, in the tracking device of the present invention, every time the rotating drum rotates by an angle θ _P , a rotating magnetic head arranged on the rotating drum moves θ _W on the magnetic tape. (However, in a magnetic recording / reproducing apparatus for recording / reproducing a signal by scanning over a rotation angle of θ _W <θ _P ), a tension control means for controlling the tension of the magnetic tape in the rotating drum portion, and the rotating drum. And a capstan movably arranged between the rotating drum and the capstan to change the length of the magnetic tape, a post actuator for driving the tracking guide post, and a drive for driving the post actuator. Means, a capstan drive means for driving the gapstan, and the rotating magnetic head. A tracking error signal detecting means for detecting a tracking error signal from a signal reproduced by a video signal and a band separating means for separating the tracking error signal into a low frequency component and a high frequency component are constituted, and at the time of reproduction, the cap The stun drive means controls the rotation of the capstan according to the low frequency component of the tracking error signal, and the drive means sets the period in which the rotary drum rotates by the angle θ _P as one cycle, and the rotary magnetic head moves on the magnetic tape. In the first period of scanning, the post actuator is driven by the high frequency component of the tracking error signal to control the tracking guide post position, and in the other second period, the tracking error signal in the initial period of the one cycle is substantially The tracking guide post is moved to a position where it becomes zero. .

With the above-described structure, the present invention controls the rotational phase of the capstan in accordance with the low frequency component of the tracking error signal detected by the tracking error signal detecting means during reproduction, thereby performing tracking on average, and tracking error The rotary magnetic head is recorded on the magnetic tape by driving the post actuator according to the high frequency component of the signal to control the position of the tracking guide post and changing the longitudinal position of the magnetic tape on the rotary drum. By accurately scanning the track and correcting the tracking guide post so that it will be the next tracking initial position during the period when the rotary magnetic head does not need to perform tracking, the rotary magnetic head always performs stable tracking on the recording track. Can be scanned Wear.

Example Hereinafter, regarding the tracking device of one example of the present invention,
A description will be given with reference to the drawings.

FIG. 1 is a block diagram of the essential parts of a magnetic recording / reproducing apparatus according to the present invention. FIG. 2 is a post layout diagram showing the positional relationship between the guide posts P6, P8 and the tracking guide post P7 in FIG. 1, and FIG. FIG. 4 is a block diagram of a main part of the tracking device according to the present invention, and is an explanatory diagram showing the relationship between the recording tracks of the magnetic tape 3 and the scanning loci of the rotary magnetic head.

In FIG. 1, reference numeral 1 is a supply reel, 2a is a reel motor for applying torque to the supply reel 1 to apply tension to the magnetic tape 3, and 2b is a motor drive circuit for supplying electric power to the reel motor 2a. The magnetic tape 3 reaches the rotary drum 5 from the supply reel 1 via the guide post P1, the tension post P2 and the guide posts P3, P4 arranged at one end of the tension lever, and reaches the rotary runner 5 at θ _W = 90 (degrees). And is attached to the capstan 9 and pinch roller 10 via the guide posts P5, P6, the tracking guide post P7, and the guide post P8, and reaches a take-up reel (not shown). The capstan 9 transfers the magnetic tape 3 to the take-up reel at a constant speed during recording and reproduction. The rotary drum 5 has two rotary magnetic heads 5a and 5b θ.
They are arranged at an interval of _P = 180 (degrees). That is, the rotary magnetic heads 5a and 5b alternately scan the magnetic tape 3 over an angle of θ _W each time the rotary drum 5 rotates by θ _P.

The tension lever 4a having the tension post P2 at one end is configured to be rotatable around the other end 4e as a fulcrum, and the tension of the magnetic tape 3 imparts a counterclockwise turning force to support one end on the fixed portion. A clockwise turning force is applied by the spring 4b. A magnet piece 4c is arranged substantially in the center of the tension lever 4a, and a magnetic sensor 4d is arranged in the fixed portion so as to face the magnet piece 4c. The magnetic sensor 4d detects the amount of rotation of the tension lever. Motor drive circuit
2b is a reel motor that supplies electric power corresponding to the output of the magnetic sensor 4d.
2a, and the tension post 4a is controlled so as to always be in a predetermined position. That is, the tension of the magnetic tape 3 is kept constant. The tension post P2, the tension lever 4a, the spring 4b, the magnet piece 4c, the magnetic sensor 4d, the motor drive circuit 2b, and the reel motor 2a constitute tension control means. 6b is a post actuator composed of a piezoelectric element, one end of which is fixedly arranged through a fixing member 6a, the other end of which is provided with a tracking guide post P7, and the rear side of which the docking guide post P7 is arranged has a magnet piece 6c. Are arranged. Reference numeral 6d denotes a magnetic sensor which is arranged on the fixed portion so as to face the magnet piece 6c and detects the position of the tracking guide post. The tracking guide post P7 is fixed at a predetermined position during recording, and is moved by the post actuator 6b during reproduction to change the path of the magnetic tape.

The guide posts P6, P8 and the tracking guide post P7 have a positional relationship as shown in FIG. 2, and in this embodiment, they are arranged so that the distances from the tracking guide points P7 to the guide posts P6, P8 are equal. The tracking guide post P7 is fixed at the position Y ₀ at the time of recording without performing the tracking operation. At this time, the length L ₀ of the magnetic tape 3 from the guide posts P6 to P8 is Is. When the tracking actuator 6b is driven and the position of the tracking guide post P7 is slightly displaced by ± δY, the length L of the magnetic tape 3 from the guide post P7 to P8 is L = L ₀ ± δY ・ (4 ・ Y ₀ / L ₀ ) L ₀ ± k ₀ · δY; k ₀ = 4 · Y ₀ / L ₀ can be approximated.

That is, when the tracking guide post P7 is displaced by δY, the length of the magnetic tape 3 from the guide posts P6 to P8 changes by δL = k ₀ · δY.

Since the capstan 9 is controlled so as to transfer the magnetic tape 3 at a constant speed, this δL changes the transfer of the magnetic tape 3 on the rotating drum 5 side. In response to this change, the tension control means operates so as to keep the tension of the magnetic tape 3 constant, so that the rotary magnetic heads 5a and 5b can maintain good contact with the magnetic tape 3 and stably reproduce the signal. can do.

FIG. 3 is a block diagram of a main part of a tracking device according to the present invention. In FIG. 3, the same components as those in FIG. 1 are designated by the same symbols. In FIG. 3, reference numeral 11 is a pulse generator, which is at a high level during the first period during which the rotary magnetic heads 5a and 5b scan the magnetic tape 3 over the rotation angle θ _W , and is at a low level during the other second period. Outputs a pulse signal. A switch circuit 12 selects and outputs a reproduction signal reproduced by the rotary magnetic heads 5a and 5b. Reference numeral 13 is a tracking error detecting means for detecting a positional deviation ε (deviation in the track width direction) of the rotary magnetic heads 5a and 5b with respect to the recording track position, and the output of the switch circuit 12 is inputted to the tracking error signal from the input signal to another signal. And outputs a tracking error signal.

Reference numeral 20 denotes a band separation means, which is composed of a high-pass filter and a low-pass filter, and separates the tracking error signal into a low-pass component and a high-pass component and outputs it. Practically, the break frequency of the high-pass filter and the low-pass filter is set to a low frequency with respect to the rotation speed n (rps) of the rotary drum 5.

21b is a capstan motor for driving the capstan 9, 2
1a is a capstan motor drive circuit
21b and the capstan drive circuit 21a constitute a capstan drive means. The low frequency component of the tracking error signal separated by the band separation means 20 is input to the capstan drive circuit 21a, and power corresponding to the input signal is supplied to the capstan motor 21b to control the rotation phase of the capstan 9. . By controlling the capstan 9 in this way, the average value of the tracking error signal becomes zero. That is, the rotary magnetic heads 3a and 3b track the recording tracks of the magnetic tape 3 with an average deviation of zero.

The magnetic sensor 6d detects the position Y of the tracking guide post P7 by detecting the magnetic flux of the magnet piece 6c.

Reference numeral 14 is a drive means, which is a drive circuit 14a, a latch means 14b, an arithmetic means.
Drive circuit 14a and a latch circuit.
The tracking error signal of the high frequency component separated by the band separation means 20, the magnetic sensor 6d, and the output of the pulse generator 11 are input to 14b. The computing means 14c includes a latch means 14b
Two outputs are input to the drive circuit 14a. In the first period in which the rotary magnetic heads 5a and 5b scan the magnetic tape 3, the drive circuit 14a responds to the tracking error signal separated by the band separation means 20, and the tracking guide post P7 has δY = (ε / sin θ ) / K ₀
(Θ; tilt angle of recording track with respect to longitudinal direction of magnetic tape 3) Tracking actuator 6b
Is driven to control the position of the magnetic tape so that the rotary magnetic heads 5a and 5b can accurately scan the recording track to perform tracking.

The latching means 14b latches the two input signals by the rising edge of the pulse generator 11 to latch the tracking position error ε _i and the position Y _i of the tracking guide post 7 at the beginning of the first period.

The calculating means 14c is Y _i + ε _i / sin (θ) in the first period.
/ K ₀ is calculated and the movement target position Y _T of the tracking guide post P7 in the second period is set and output. In the second period, the drive circuit 14a moves to the tracking guide post P
The tracking actuator 6b is driven by the output of the magnetic sensor 6d so that 7 becomes the target position Y _T , so that the tracking position deviation at the beginning of the next first period becomes substantially zero.

The above operation will be described more specifically with reference to an example.

Tracking is performed by the rotating magnetic heads 5a and 5b that scan the recorded magnetic tape 3 recorded at the recording track angle θ with respect to the longitudinal direction of the magnetic tape at a scanning angle of θ ′ with respect to the longitudinal direction of the magnetic tape due to mechanical error or the like. Set the position of guide post P7 to Y
_When it is fixed to ₀ and played back, a tracking error occurs.
FIG. 4 shows the relationship between the recording tracks that can occur in this case and the scanning trajectory of the rotary magnetic head. In FIG. 4, the solid line shows the center of the recording track, and the broken line shows the center of the scanning locus of the rotary magnetic head. Ie rotating magnetic head 3
The tracking position error ε with respect to the recording track generated by the scanning of the magnetic tape 3 by a and 3b varies linearly from + ε ₁ (μm) to −ε ₂ (μm).

This position deviation is detected as a tracking error signal by the tracking error detection means 13, its low frequency component is separated by the band separation means 20, and the rotational phase of the capstan is controlled by the separated low frequency component to obtain the position deviation ε. The average value is zero. That is, ε ₁ = ε ₂ .

When this position deviation ε is converted into a deviation λ in the longitudinal direction of the magnetic tape 3, λ = ε / sin θ.

The tracking position deviation can be made zero by displacing the magnetic tape 3 by λ (μm) in the longitudinal direction with respect to the tracking position deviation of ε.

Then, the initial tracking position deviation ε _i during the first period in which the rotary magnetic heads 3a and 3b scan the magnetic tape 3 and the position Y _i of the tracking guide post P7 (ε _i = ε ₁ , Y at the beginning of the tracking operation) _i = Y ₀ ) latch means 14b
Then, the tracking guide post P7 is moved to a position of Y _T = Y _i + ε _i / sin (θ) / k ₀ in the second period next [Y _T = Y ₀ + ε ₁ / sin (In the initial tracking operation, θ)
/ K ₀ ], and the magnetic tape 3 is moved in the longitudinal direction so that the tracking position deviation at the beginning of the next first period becomes zero. Then, in the first period, the tracking actuator 6b is driven so that the tracking detection signal detected by the tracking detection means 13 becomes substantially zero, and the position of the tracking guide post P7 is controlled to change the position of the magnetic tape 3 in the longitudinal direction. By doing so, the rotary magnetic heads 3a and 3b accurately scan the recording tracks of the magnetic tape 3.

As described above, according to the present invention, every time the rotating drum rotates by the angle θ _P , the rotating magnetic head moves on the magnetic tape by θ _W (θ _W <
In a magnetic recording / reproducing apparatus for recording and reproducing a signal by scanning over a rotation angle of (θ _P ), a tension control means for controlling the tension of a magnetic tape, and a tracking guide post and a tracking for varying a magnetic tape length from a capstan to a rotating drum. A post actuator for driving the guide post, a tracking error signal detecting means for detecting a tracking error signal from the rotating magnetic head during reproduction, a band separating means for separating the tracking error signal into a low frequency component and a high frequency component, and a tracking actuator. The driving means for driving and the capstan driving means for driving the capstan are configured, and at the time of reproduction, the tracking phase is controlled by controlling the rotation phase of the capstan with respect to the tracking error in the low range, and with respect to the tracking error in the high range. Is a rotating magnetic head on a magnetic tape In the first period of scanning and reproducing the signal, the tracking actuator is driven by the tracking error signal to perform tracking and the rotating magnetic head does not scan the magnetic tape. In the second period, the tracking guide post is moved to a predetermined position. The rotating magnetic head can be stably and accurately scanned on the recording track recorded on the magnetic tape.
Further, the following effects are exhibited.

(1) Since the tracking can be performed without displacing the rotating magnetic head as in the conventional case, the structure of the rotating drum is simple.

(2) Since the tracking can be performed without displacing the rotary head, the touch between the tape and the rotary magnetic head (head touch) is stable, and the signal recorded in the short wavelength can be stably reproduced.

(3) In particular, it is effective for a magnetic recording / reproducing apparatus of a digital recording system (for example, a system such as R / DAT) in which a signal is time-axis compressed and recorded intermittently on a magnetic tape, and head touch is stable and high. It is possible to narrow the track because it can be tracked with high accuracy.

(4) Since the low band tracking error is tracked by the capstan, the movable range of the tracking guide post can be reduced. Needless to say, the present invention can obtain the same effect when the tracking error signal is detected intermittently from the recording track.

[Brief description of drawings]

FIG. 1 is a block diagram of the essential parts of a magnetic recording / reproducing device according to the present invention, FIG. 2 is a post layout diagram, FIG. 3 is a block diagram of the essential parts of a tracking device according to the present invention, and FIG. FIG. 6 is a relationship diagram showing the relationship between the recording track on the tape and the scanning trajectory of the rotary magnetic head. 1 ... Supply reel, 2a ... Reel motor, 2b ... Motor drive circuit, 3 ... Magnetic tape, 4a ... Tension lever, 4b ... Spring, 4c ... Magnet piece, 4d ... Magnetic sensor, 5
...... Rotary drum, 5a, 5b …… Rotary magnetic head, 6b …… Tracking actuator, 6c …… Magnet piece, 6d …… Magnetic sensor, 9 …… Capstan, 10 …… Pinch roller, P2
...... Tension post, P7 …… Tracking post, 11
...... Pulse generator, 13 …… Tracking error detection means,
14a ... Drive circuit, 14b ... Latch circuit, 14c ... Arithmetic circuit, 20 ... Band separation means, 21a ... Capstan drive circuit, 21b ... Capstan motor.

Claims (2)

[Claims] 1. A rotating magnetic head disposed on the rotating drum rotates θ on the magnetic tape every time the rotating drum rotates by an angle θ _P.
Scan over the rotation angle of _W (where θ _W <θ _P ),
In a magnetic recording / reproducing apparatus for recording / reproducing a signal, tension control means for controlling the tension of the magnetic tape in the rotary drum portion, and movably arranged between the rotary drum and a capstan from the rotary drum to the capstan. A tracking guide post for varying the length of the magnetic tape to reach, a post actuator for driving the tracking guide post, a driving means for driving the post actuator, a capstan driving means for driving the capstan, and the rotating magnetic field. A tracking error signal detecting means for detecting a tracking error signal from a signal reproduced by the head, and a band separating means for separating the tracking error signal into a low frequency component and a high frequency component are constituted, and the cap is used during reproduction. The stun drive means is the tiger Controls the rotation of the capstan by low frequency components of the king error signal, a first of said rotary magnetic head and the drive means is a one cycle period of the rotary drum is rotated the angle theta _P scans the said magnetic tape During the period, the post actuator is driven by the high frequency component of the tracking error signal to control the position of the tracking guide post, and during the other second period, the position of the tracking guide post becomes a predetermined position. A tracking device characterized by being adapted to drive a post actuator. 2. The post actuator includes position detecting means for detecting the position of the tracking guide post, and the driving means and the high-frequency tracking error signal separated by the band separating means at the beginning of the first period and the position. Latching means for latching the post position signal detected by the detecting means, and computing means for computing the signal latched by the latching means and outputting a signal as a target position for moving the tracking guide post in the second period, and The tracking according to claim (1), which comprises a drive circuit for driving a post actuator, and drives the post actuator in a second period so that the position of the tracking guide post becomes the target position. apparatus.