JPS5822981B2 - Rotation detection device for magnetic recording and reproducing devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotation detecting device for a magnetic recording/reproducing device, which separately detects rotational errors due to rotational unevenness in the direction of rotational force of a recording medium and rotational errors due to rotational unevenness in the direction of axial deviation of the recording medium. The object of the present invention is to provide a rotation detection device capable of detecting rotation.

A disk-shaped recording medium rotated by a motor is generally
The motor rotates with rotational fluctuations that are a combination of rotational fluctuations in the direction of rotational force caused by torque fluctuations in the motor itself and rotational fluctuations in the direction of axis deviation caused by play or eccentricity of the rotating shaft of the motor.

However, rotation control of conventional magnetic recording and reproducing devices generally ignores rotational unevenness in the direction of axis deviation and controls only rotational unevenness in the direction of rotational force.

For this reason, in conventional devices, when rotational unevenness in the direction of rotational force is improved through control, the rotational unevenness in the direction of off-axis becomes a value that cannot be ignored, and this rotational unevenness in the direction of off-axis becomes a so-called disturbance that increases jitter. There were some drawbacks, such as:

The present invention eliminates the above-mentioned drawbacks, and embodiments thereof will be described below with reference to the drawings.

FIG. 1 shows the relationship between a magnetic recording medium, a control head, and a video head used in an embodiment of a rotation detecting device for a magnetic recording/reproducing apparatus according to the present invention.

In the figure, reference numeral 1 denotes a still image magnetic recording medium used for recording and reproducing still image broadcasting using the J-Levy multi-gravity system, and control signals 3a and 3b are recorded on the surface thereof.

2a and 2b are control heads; 4a; Reference numeral 4b denotes a video head, which is installed diametrically above the rotating shaft 6.

For still image broadcasting using the TV multi-gravity system, for example, a static 1L image broadcast tsubo 1 is placed between each field a of the current broadcast wave.
Information signals for one horizontal scanning period (IH) each different from the video signal are sequentially inserted and broadcast.

When recording and reproducing this still image broadcast, the first 1H of the still image broadcast video signal is recorded in the video head 4a during the first rotation of the recording medium 1, and the next IH is recorded during the second rotation of the recording medium 1.
By repeating this operation, the video signal 5a is recorded by the video head 4a into one video rack for one field of still images over one round.

Next, the video signal 5a is played back by the video head 4a, and at the same time, the video head 41) is operated in the same manner as described above.
At this point, the next signal 5b is recorded for the next one field over one cycle on another track.

Next, after erasing the signal 5a instantaneously during the first revolution when recording the signal 5a, the next signal 5a is further recorded on the same track for one field, and at the same time, the head 4b is used to record the signal 5a. Play 5b.

In this way, the video heads 4a, 4b can be connected to, for example, 4.
The recording operation is repeated alternately with a recording time of 5 seconds.

Here, the recording medium 1 rotates in the direction of the arrow while causing rotational unevenness in the rotational force direction and rotational unevenness in the axis deviation direction, and a certain amount of soft rotation @
Let us consider the phase of the control signal detected by the control heads 2a and 2b when 6 is displaced to the position 6'.

If the rotation @ 6 degrees fWjf is rotating, then the control signal 3 detected by the control 1 roll-\rad 2a
The phase error of the signal 3a detected by the head 2a when the phase of signal a is shifted to φ4 and the position of the rotation axis 6' is △φA
If the phase of the signal 3b detected by the head 2b is displaced to the position of the rotation axis C when the head 2b rotates at M rotation position 6 for one rotation, and the phase error of the signal 3b detected by the head 2b is △φI3, The phases of the control signals 3a, 3b detected by the heads 2a, 2b, respectively, are φA+Δφ4 . φB+△φo.

The signals detected by the heads 2a and 2b are amplified by amplifiers 7a and 7b, respectively, as shown in FIG. 2, and then supplied to phase comparators 3a and Bb.

- The current broadcasting video signal input from the input terminal 9 is separated from the horizontal synchronization signal by the horizontal synchronization separation circuit 10 and supplied to the phase comparator 11, where the voltage controlled oscillator 12
The oscillation frequency of the voltage controlled oscillator 12 is compared with the phase of the signal obtained by dividing the output oscillation frequency of 63 kHz by the frequency divider 13, and a phase comparison error voltage whose level changes according to the phase difference is extracted. Control.

Bow aiming phase comparators 8a, 8b from voltage controlled oscillator 12
Where is the amplifier supplied? a, the phase of the signal from 71) φA+△φA.

ψB+ΔφB and the phase φ of the reference signal from the voltage controlled oscillator 12.

are respectively converted into phase ratio axes, and phase error signals of φ-Δφ and even 1-φ are extracted.

That is, the phases φA and φB of the signals detected by the heads 2a and 2b, respectively, are the phase φ of the reference signal.

This is because the phase error φ due to rotational unevenness in the rotational force direction is added to (φA−φB−φ).

+φ), and the phases of the signals from amplifiers 7a and 7b are respectively (φ
A+△φA)−φ.

−φ+△φA, (φB to φB) −φ.

-φ+△φB and 1. toφ4・−1△φ. △φB−△
If φ is set, the phase error φ from the phase comparators $a and gb, respectively.
-Δφ and φ+Δφ signals are taken out.

This phase error includes a phase error φ due to rotational unevenness in the direction of rotational force.
and a phase error Δφ due to rotational unevenness in the direction of axis deviation.

The signal of φ to the phase error φ−· is given by the control coefficient (', (s)
) circuit and adder (hereinafter simply referred to as adder) 14a, and the control coefficient (' to 2 (S)) circuit and adder (hereinafter referred to as adder) 14b, -
The signal of the power and phase error φ-1-Δφ is supplied to the adder 14a, and is also supplied via the inverter 15 to the adder 14b.

The rotation error of the signal obtained by multiplying the control coefficient by 1 (s) in the adder 14a becomes 2, φ, and the adder 16a,
The rotational error of the signal supplied to 16b and the control coefficient multiplied by 2 (s) in adder 14b is -2
becomes 2Δψ, and is supplied to the adder 16b via the adder 16a and the inverter 17.

Note that the adders 14a and 14I] are phase 1 comparators 8a and 8
This is a circuit that adjusts the frequency characteristics and the first gain of the output signal 2φ of the oro of b and the output signal −2△φ of the difference, and the altitude error and phase error are It is included.

In the adder 16a, 2△φ is added to the rotation error 2, the signal of φ, the rotation error -2, and 2 (2△φ to K1φ-).
) is supplied to the switch circuit 18, and the adder 16b adds a signal of 1φ to rotation error 2 and a signal of 2Δφ to rotation error 2, resulting in 2(K1φ−1− to 2Δψ
) and is supplied to the switch circuit 18.

Note that the rotation error 2 of the adder 16a (K1φ−1〈2△ψ
) is the output phase error φ, −△φ of the phase comparator 8a.
is 1.2 multiplied by 2, and -force adder 16b
The rotation error 2 (K1φ10 to 2△φ) is the phase comparator 81]
The output phase errors φ and △φ are multiplied by 2, 1.2, and 2, respectively, and both of them have a rotation error of 1φ due to rotational unevenness in the rotational force direction and a rotational error of 2△ψ due to rotational unevenness in the axis misalignment direction.
including.

Here, the switch circuit 18 is connected to the video head 4a.

The adder 16 is set to operate corresponding to the recording time of the head 4b, and the adder 16 is set to operate corresponding to the recording time of the head 4a.
The rotational error 2 (K1φ− to 2φ) of the output signal of a is taken out, and during the 101 period that the head 4 b is recording, the rotational error 2 of the output signal of the adder 16b (2△φ to K1φ1000) is taken out. is taken out.

In this way, the signals taken out corresponding to the recording time of the video heads 4a and 4b are supplied to the motor 20 via the motor drive circuit 19, and the video signals are transmitted to the video head during recording without being affected by rotation errors. Motor 20 so that it can be recorded
control the rotation.

Thereby, the video heads 4a and 4b can accurately record video signals without being affected by rotational unevenness in the direction of rotational force and rotational unevenness in the direction of axis deviation.

Although the rotation error of the video head during playback cannot be eliminated, since playback does not require improvement of the rotational unevenness as much as during recording, there is virtually no problem.

Here, the video heads 4a and 4b are not in the vicinity of the control heads 2a and 2b, respectively (video head 4a and 4b are not located near the control heads 2a and 2b, respectively).
, 4b are control heads 2a, respectively.

2b) or when a ball bearing is used for the bearing of the motor 20 and the vibration is relatively large, improvement in rotational unevenness in the direction of shaft misalignment cannot be expected to be significant. , it is only necessary to improve rotational unevenness in the direction of rotational force.

Therefore, in such a case, the phase comparator circuit 8 shown in FIG.
between a and adder 14b, inverter 15 and adder 14
A switch circuit is provided between the adder 14a and the adder 14a, and only 1φ of the rotational error 2 is extracted from the adder 14a to improve only the rotational unevenness in the rotational force direction.

As described above, the rotation detecting device of the magnetic recording/reproducing apparatus according to the present invention has a first sensor which is in a diametrical force with respect to the rotating shaft of a disk-shaped magnetic recording medium and detects a control signal corresponding to the rotation of the recording medium. and a second control signal detection means, and first and second phases for respectively detecting a phase error by comparing the phase of the old name from the first and second control signal detection means with the phase of the reference signal, respectively. Comparison means, first
and a first calculation means for calculating the sum of the phase errors from the second phase comparison means and multiplying the sum by a first predetermined side m coefficient to extract a rotational error signal due to uniform rotational unevenness in the direction of the rotational force of the recording medium. , taking the difference between the phase errors from the first and second phase comparing means and multiplying the difference by a second predetermined coefficient] to extract a rotational error signal due to rotational unevenness of the recording medium in the direction of axis deviation. Since the rotational error due to rotational unevenness in the rotational force direction of the recording medium and the rotational error due to rotational unevenness in the axis misalignment direction can be detected separately, this error signal is expressed as a rotational control signal for the recording medium. If used, the recording medium can be accurately rotated without rotational unevenness in the rotational force direction and rotational unevenness in the axis deviation direction, and video signals can be recorded and played back alternately at predetermined time intervals on two video racks on the recording medium. first and second recording and reproducing means for calculating the sum of the signals from the first and second calculating means, and third calculating means for calculating the sum of the signals from the first and second calculating means, and the difference between the signals from the first and second calculating means. and means for alternately extracting rotation error signals from the third and fourth calculation means corresponding to predetermined recording periods of the first and second recording and reproducing means, respectively. Therefore, if the signals alternately taken out from this means are used as both rotational side signals of a recording medium such as a device for recording and reproducing still image broadcasting using a television multigravity type, rotational errors during recording can be reduced. The first and second recording and reproducing means can record the video signal for static 11-images satisfactorily.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between a magnetic recording medium, a control head, and a video head used in an embodiment of a rotation detection device for a magnetic recording and reproducing apparatus according to the present invention, and FIG. 2 is a diagram showing the relationship between a magnetic recording medium and a control head and a video head for a magnetic recording and reproducing apparatus according to the present invention. FIG. 2 is a block system diagram of an embodiment of the rotation detection device of FIG. 1...Magnetic recording medium, 2a, 2b...
Control head, 4a, 4b...Video head, 6°C...Rotation I axis, 8a, 8b...
... Phase comparator, 12 ... Voltage controlled oscillator,
i4a, 14b... control coefficient circuit and adder,
15.17...Inverter, 16a, 16b
... Adder, 18 ... Switch circuit,
20...Motor.

Claims (1)

[Scope of Claims] 1. First and second control signal detection units provided diametrically opposite to the rotational axis of the disk-shaped magnetic recording medium and detecting control signals corresponding to the rotation of the recording medium, respectively. means, first and second phase comparison means for respectively detecting phase errors by comparing the phases of the signals from the first and second control signal detection means with the phase of the reference signal, respectively; and a second phase ratio axis means, which calculates the sum of the phase errors and multiplies them by a first predetermined control coefficient to extract a rotational error signal due to rotational unevenness of the recording medium in the direction of the rotational force.
and the first and second phase comparing means, and multiplying the difference by a second predetermined control coefficient to extract a rotational error signal due to uneven rotation of the recording medium in the direction of axis deviation. A rotation detecting device for a magnetic recording/reproducing device, comprising a second calculation means. 2. First and second control signal detection means that are provided diametrically opposite to the rotation axis of the disk-shaped magnetic recording medium and detect control signals corresponding to the rotation of the recording medium, and the recording medium. first and second recording and reproducing means for alternately recording and reproducing video signals on the upper two video tracks at predetermined time intervals; and detecting the phases of the signals from the first and second control signal detecting means. first and second phase comparison means for respectively detecting a phase error by comparing the phase with the phase of a reference signal; and a first predetermined value for calculating the sum of the phase errors from the first and second phase comparison means. a first calculating means for extracting a co-rotation error signal due to rotational unevenness in the direction of rotational force of the recording medium by multiplying the control coefficient; and calculating a difference in phase errors from the first and second phase ratio axis means; A second calculation means for extracting a rotational error signal due to rotational unevenness in the axis misalignment direction of the recording medium F by multiplying it by a second predetermined control coefficient, and calculating the sum of the signals from the first and second calculation means. A third arithmetic means, a fourth arithmetic means that takes the difference between the signals from the first and second arithmetic means, and a rotation error signal from the third and fourth arithmetic means, respectively. A rotation detecting device for a magnetic recording/reproducing apparatus, characterized in that it comprises: and means for alternately extracting data corresponding to a predetermined recording period of the second recording/reproducing means.