JPS6031022B2 - Method and apparatus for compensating eccentricity of recording track - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for compensating for track eccentricity occurring during reproduction of a rotating recording member, and in particular for compensating for tracking errors and velocity errors resulting from such eccentricity. It relates to a technology that allows even more information to be packed into a recording section.

Many recording devices record and store information in the form of disks.

For example, rigid or floppy disks are used to store digital information, both magnetic and optical disks are used to store video information, and acoustic information is stored mechanically on honograph disks. . In many cases, it is necessary to position a reproducing transducer or read head with a high degree of precision to a desired data track on a recording member. This is because most of the information tracks of such recording units are in the form of concentric circles or in the form of a spiral, and the inside of the information tracks is only about 0.125 columns (5 mm), and the tracks are on the recording member. This is because they are only separated by a very small distance. In some cases, the recording tracks also include precisely spaced timing or index signals used for control purposes. It is therefore clear that how small the spacing of the track and index signals can be made is directly dependent on how accurately the transducer can be positioned relative to the recording member. When retrieving information from a disk-shaped recording member, the rotating disk and the circular or spiral recording tracks already recorded on the disk may not be perfectly concentric.

In other words, the center of the track may deviate from the center of rotation of the disc during playback. This problem arises because a given machine may concentrically record information on a disc and for some reason remove the disc from the machine prior to playback. When information is to be retrieved from this disk, it is very difficult to return the disk to its true or original center of rotation, whether it is installed in the same machine or in a different machine. Therefore, during playback, the center of the information track no longer coincides with the center of rotation of the disc. The result is that the recording tracks are radially "deviated" relative to the playback transducer, which is typically kept at a constant distance from the center of rotation of the disk. The output signal from the corresponding transducer of the selected track's information is therefore adjusted to twice the angular rotational speed of the disk, and in extreme cases adjacent tracks may be moved to the point where they are opposite the transducer. , in which case the output from the transducer will be completely erroneous. In addition to the introduced radial tracking error, the eccentricity of the track during playback causes track velocity and timing errors.

In other words, as the disk rotates at a constant angular velocity, as the track deflects radially inward and outward relative to the transducer, the velocity of the track past the transducer increases or decreases correspondingly, i.e., half the time the track is It goes slow and the other half of the time it goes too fast. Thus, for example, control or index points. The information taken from a track, such as a track, will vary in time with respect to a fixed time reference, such as a timing signal synchronized to the rotation of the disk. Therefore, the index information retrieved from the disk becomes unsuitable for controlling related counterfeiting. Additionally, if the data on the disc is frequency modulated during playback from an eccentric track, the retrieved signal will be frequency modulated at a frequency equal to the disc rotational speed, causing other filtering problems and issues other than those mentioned above. creating control problems. After recording, the center of the recording track and the center of rotation of the recording member during playback are not perfectly concentric, causing the azimuth angle between the head and the recording member to change with each rotation of the disk member.

This degrades the output signal from the regenerative transducer and causes significant wear on the associated components. Many types of electrical devices have been proposed for compensating for tracking errors that occur during playback of rotating recording members such as disks. Such devices are disclosed, for example, in U.S. Pat.
No. 15 and No. 386474. One type of device uses a reproducing transducer that has two or more sensing coils aligned perpendicular to the recording tracks of the disk. The outputs of the coils are then compared to generate a tracking error signal. This error signal changes in magnitude and polarity as the track deviates radially inward or outward from its central position opposite the transducer. This error signal is then used to control the positioning device to move the regenerative transducer radially inward or outward as necessary to maintain the track in a centered position opposite the transducer. Other types of devices use a pair of transducers placed perpendicular to the recording tracks of the disk that hold the recorded frequencies.

Each transducer generates a signal at the track frequency,
The signal level is proportional to the transducer section facing the track. The two signal levels are compared to generate a difference signal that controls the actuator to move the transducer radially inward or outward to maintain the transducer in a centered position on the track.

Yet another device uses optical detection means and a servo loop of the same type to compensate for track eccentricity.

However, none of these prior art devices accurately compensate for track eccentricity. First, as servo conventional devices, these devices cannot anticipate or measure the degree of eccentricity before setting up exact compensation for tracking errors. Furthermore, there is no compensation for variations in track speed or timing caused by eccentricity of the track. Therefore, the information retrieved from the disk still varies in time and frequency, which may cause errors and malfunctions in devices controlled by the information on the disk. Furthermore, these known devices are completely incapable of correcting for azimuth variations between the transducer and the disk caused by the track offset D.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved technique for compensating for the eccentricity of recording tracks that occurs in a rotatable recording member during reproduction.

Another object of the present invention is to provide a reproduction method that compensates for tracking errors and speed or timing errors caused by eccentricity of the recording tracks of a rotatable recording member. Yet another object of the present invention is to provide a method for determining the degree of eccentricity of a recording track of a recording member before retrieving data from the track. Yet another object of the invention is to provide a method for improving the quality of the reproduced signal corresponding to information recorded on eccentric tracks of a rotatable recording member. Still another object of the invention is to provide an apparatus for measuring and compensating for tracking errors and speed or timing errors caused by eccentricity of recording tracks of a recording member during playback. .

Other objects of the invention will become apparent from the description below.

The invention thus comprises a number of steps, and the relationship of one or more of such steps to each other, the apparatus embodying the features of the structure, the combination of elements acting on the steps, and The entire arrangement of parts is described in detail below, and the subject matter of the invention is pointed out in the claims.

Simply put, compensation along the radius of the recording track to correct tracking error of the recording track that occurs on a rotatable recording member such as a disk, and to correct velocity errors, ie timing errors, of the recording track. It has been found that the compensation along the arc of the recording track of is exactly equal to the compensation along the radius of rotation of the disk and the compensation along the tangent to the rotation track of the disk. Therefore,
Reproduction is performed by moving the reproduction transducer at the same angular velocity and phase as the center of the recording track along a circular path with the same radius as the circle described by the center of the recording track (defined as the eccentric circle) due to rotation of the disk. Compensation for eccentricity of recording tracks inside can be precisely achieved. According to the method of the invention, as soon as it is known that the recording track is eccentric, the magnitude of the eccentricity is determined.

By using this information to provide the correct circular motion to the regenerative transducer, exact compensation for tracking errors and velocity or timing errors caused by eccentricity is achieved. Tracking error and velocity error compensation automatically maintains the playback transducer in the correct azimuth with respect to the disk. In a typical application of the method of the invention, the compensator is incorporated into a standard reproduction machine.

The playback machine includes a playback transducer having a flexible mount and a transducer relative to the mount both radially and tangentially of a disk rotationally mounted to the playback machine. The arrangement is conventional except that the transducer is arranged to vibrate, thus allowing the transducer to move along a quadrangle opposite the recording tracks on the disk. A playback machine incorporating the device according to the invention is preferably operated in a set mode in order to measure the magnitude of the eccentricity occurring in the recording track of the disc and its phase with respect to the rotation of the disc.

Using this information, the device should vibrate the playback transducer radially and tangentially to the disk so that the playback transducer moves in a circle with the same radius, angular velocity, and phase as the eccentric circle made by the center of the track. Determine the proper mid-shake and phase. During normal operation of the playback machine, the information produced by the device then causes the transducer to vibrate so that it performs a compensating circular movement relative to the selected track of the disk. Thus, as shown in the signal from the reproducing transducer, the information retrieved from the disk is free of any vibration, frequency, or timing fluctuations caused by eccentricity of the recording tracks of the disk. Various specific configurations for achieving such bias compensation are discussed in detail below. The apparatus of the invention thus predicts and measures the magnitude of the track eccentricity occurring in the recording member and its phase relative to the rotation of the recording member, and uses this information to accurately compensate for the deviation D. Generates the signal necessary to rotate the regenerative transducer.

In addition to compensating for radial tracking errors, as has been done heretofore, it also accurately compensates for velocity errors, or timing errors, caused by offsets of 0'. Therefore, data such as control bits and index bits can be packed closer together around the arc of the track and still be read out reliably. Furthermore, undesirable modulation effects of frequencies recorded on the disc are also reduced. lastly,
The apparatus of the present invention maintains the transducer in a constant azimuth, reducing the quality of the output signal from the transducer and the wear and tear of the parts. The present invention will now be described in detail with reference to the accompanying drawings. Referring first to Figures 2 and 3 of the accompanying drawings, it will be seen that data or information is recorded by a machine on a disk or similar storage device. When the disc is retrieved by another machine, the center of rotation of the disc during playback may not coincide with the center of a track already recorded on the disc.

FIG. 2 therefore shows a disk 10 on which information has already been recorded along a circular track T centered at T'. By rotating the disc member 10 counterclockwise about the center of rotation X, information is now retrieved from the disc member 10 installed in the playback machine. As is clear from FIG. 2, the center of rotation is separated from the center of the track by a distance representing the eccentricity of the track during playback. During playback, therefore, the track T moves radially relative to the transducer L, which is mounted at a fixed distance from the center of rotation X. This movement is expressed by the following equation. 6 Nigo COS t
{1} However, 6: Transducer L
and track T = eccentric distance = angular velocity of disk t = time Thus, from equation '1', track T and transducer L
It is clear that the distance between and therefore the signal level from the transducer is modulated by twice the rotational speed of the disk.

The proper speed at which the truck passes the transducer is:

S='2} where s=appropriate track speed r=radius of track=angular velocity of the disk Meanwhile, the incremental speed variation caused by the tracking error 8 is as follows.

In SE6, s = Speed fluctuation due to tracking error 6 = Distance between transducer L and track T = Disk angular velocity Therefore, from equation {1-, t2} and '3', As is clear, the total track speed S' can be expressed as:

9 2 S 1 1 1 0 COS t 2 Therefore, the speed S' of the truck passing the transducer L also changes in a periodic manner.

Half the time when the track is located radially outward from the transducer, the track is moving too far, and half the time when it is located radially inward from the transducer, the track is moving too slowly. This causes frequency variations in the output signal from the regenerative transducer. Also, the index point of the track also changes over time with respect to a constant reference signal. Since the coefficient of the cosine relationship in equation '1} is , it is clear that any correction to the radial tracking error is along the radius r of the track.

On the other hand, since what is the coefficient of the cosine relationship in equation (4), it is clear that the correction of velocity fluctuation by the tracking error is along the arc of the track. and along the arc of the track is exactly equal to the correction along the radius of rotation of the disk and along the tangent to the track on which the disk actually rotates (i.e. perpendicular to the radius of rotation). ing.

In FIG. 3, X is the actual center around which the recording member 10 rotates during playback. The center of this rotation is offset from the center of the already recorded track T by a distance 'representing the eccentric distance of the track, as shown in FIG. Points A, B,
C and D are the track center T at the 1/4 point of the playback rotation.
' (Fig. 2), and this center is moving at the speed t. All these points are located on an eccentric circle M that represents the path of the track center T' during playback. Arc A, B,
C and D represent tracks of equal radius arising from the track center positions A, B, C, and D, and arc × represents the correct track, that is, the rotating track, arising from the center of rotation, assuming that there is no eccentricity. ing.

By deflecting the transducer L along the radius of rotation of the disk (here referred to as the y-direction) and along the trailing line of the rotating track (here referred to as the y-direction), the transducer is placed in all tracks A, B, C, and D. It is clear from FIG. 3 that the positions can be set at opposing points.

These intersection points are designated a, b, c, and d in FIG. It is also clear from FIG. 3 that these points a, b, c, and d are all on the circle N, and the radius thereof is equal to the radius e of the eccentric circle M. Thus, by moving the transducer L through a circular path N' having the same radius as the circle M and in phase with the instantaneous position of the track center r, both tracking errors and speed or timing errors can be compensated for. Thus, if the transducer is rotated in the correct circular path described above, for any instantaneous position P of the track center T' that produces a track P during playback, there will be a point P in that track that is swept by the transducer L. Track and velocity compensation is thereby performed exactly, rather than approximately, by reproducing the actual transducer movement required to achieve compensation so that the transducer automatically follows the correct path N during a read operation. This means that the decision can be made before the change and the controller can also be set appropriately. Further measurements and corrections during playback, such as by servo followers (which were required in known compensation arrangements comparable to the present invention, but which still do not provide accurate compensation) are no longer necessary. Not. FIG. 1 shows a simple apparatus for implementing the proposed compensation technique.

For example, the recording section 1 may be a hard disk or a floppy disk having an information track T already recorded thereon. These tracks may be concentric circles or may be a single spiral wound several times. In the latter case, it is desirable to make a circular track T on the outside for setting the compensating correction. Disc 10 is placed on turntable 12 of a conventional playback machine.

The turntable 12 is rotated counterclockwise in the embodiment shown by a synchronous motor 14 connected to a standard 60 Hz power supply I6. Typically, floppy disks are rotated at 36 pm, while magnetic disks used for video are rotated at 360 pm. For some reason, the center of rotation of the disk 10 deviates from the center of the track T, causing the track to become eccentric with respect to the center of rotation of the disk 10. The device of the invention comprises a regenerative transducer L connected by a rigid horizontal arm 17 to an upright flexible rod 18;
The lower end of is supported by the base member 22.

This particular form of support for the transducer L is merely for deciphering the invention. Base member 2
2 is movable for roughly positioning the transducer L over a selected one of the tracks T by an actuator or other suitable means as is conventionally done in such reproduction machines. It is.

This rough positioning of the transducer may be performed as disclosed in the aforementioned patent. A small AC motor 24 is attached to the flexible rod 18.

The motor 24 has a rotating field coil 24a and its armature 24b is fixed to the rod 18. The motor 24 is connected to the variable phase controller 2 by a switch 25.
Connected to 6. This controller 26 is connected to the coil 24 of the motor.
A receives the voltage from the power source 16 so that it rotates in the direction of the rebound meter. The motor also has a small threaded stub shaft 28 projecting radially from its side, and a small internally threaded, weighted sleeve 32 is screwed onto the shaft 28. ing. motor 2
This sleeve 32 rotates eccentrically when 4 is energized, the magnitude of the eccentricity being determined by the position of the weight 32 relative to the shaft 28.
can be adjustably positioned along shaft 28. Also shown in FIG. 1 is the information reproduction portion of transducer L, which includes a pair of separate magnetic elements 36 and 38.

Each element includes an electromagnetic coil 36a and 38a, respectively. The magnetic pole and airgap portions 36b, 38b represent the active area of the associated airgap of these magnetic elements, so that each of these elements has an area of underlying track T (which corresponds to the track shown in FIG. 1). ) are magnetically cooperating with each other. Coils 36a and 38a are connected in a simple bridge circuit, the core circuit comprising a resistor 42 connected between the common center connection of coils 36a and 38a and an adjustable tap 44a of potentiometer 44, The terminals are connected to the external terminals of coils 36a, 38a.

This circuit has an amplitude proportional to the difference in amplitude between the signals from the two coils, and a polarity corresponding to the polarity of the signal from transducer element 36 or 38, whichever has the greater amplitude. The outputs of coils 36a and 38a are connected in series with opposite polarity to each other to provide an electrical error signal having an electrical error signal. This error signal appears between the common connection of coils 36a and 38a and adjustable tap 44a and is applied to error signal multiplier 48. Error signal multiplier 4
The output of 8 is applied to a voltmeter 54 and also to a phase comparator 56.
is applied to

This phase comparator 56 also receives the frequency of the power supply voltage from the power supply 16. The phase difference between the two signals applied to this comparator 56 is indicated to a koto detector 58. Data signal intensifier 6 for intensifying the signal generated by transducer L' after completing compensation correction during a data read operation.
0 is also provided. The output of the multiplier 60 is applied to conventional data reading circuitry found in playback machines of this common type. In another construction, a shaft encoder or tachometer signal generator fixed for rotation with turntable 12 or motor shaft 14a provides a reference signal to comparator 56 and uses the frequency of power supply 16 to Motors 14 and 24 may also be driven.

During playback, when the track deviates radially relative to the transducer L, each transducer element 36, 38 is slightly displaced from the position opposite the track T, so that the output signal from each transducer L element 36, 38 is oscillated. Modulated.

When transducer L is centered directly over track T as shown in FIG. 1, the outputs from both transducer elements are equal and no output signal is applied to intensifier 48. FIG. 4a shows the modulation envelope of the output signal from transducer element 36. FIG.

The corresponding envelope of the output signal from element 38 is also the same except that it is 1800 degrees out of phase with respect to the waveform of FIG. 4a.
(Points A to D in FIGS. 4a to 4d correspond to instantaneous positions A to D of the track center r in FIG. 3.) Therefore,
The output from the error signal multiplier 48 is also a periodic signal, i.e. a sine wave, whose amplitude as measured by the voltmeter 54 is the fourth
It is equal to the depth m of the modulation envelope due to eccentricity shown in Figure a. Voltmeter 54 therefore indicates the magnitude of the increasing radial tracking error. Additionally, the output of comparator 56 shown to detector 58 is indicative of the phase difference between the error signal from intensifier 48 and the rotation of disk 10.

This is because the rotation of disk 10 is synchronized to the frequency of power supply 16. With zero tracking error and velocity error, the error signal from the multiplier 48 has essentially zero amplitude and is exactly in phase with the power supply 16 signal. Therefore, under this condition, the voltmeter 54
indicates zero volts and detector 58 indicates zero.
On the other hand, when track T deviates from transducer L, the magnitude of the displacement is indicated by voltmeter 54, and the direction of displacement and rate of change is indicated by the magnitude and direction of movement of the pointer of detector 58. To compensate for track eccentricity prior to regeneration, the machine of FIG. 1 is operated in a set-up or start-up mode in which the normal readout circuitry is disabled.

The transducer L is positioned over a selected, preferably outer circular track T (or a circular setting track if data is recorded spirally on the disc 10'). When the motor 14 is energized, the magnitude of the eccentricity of the track and its phase relative to the rotation of the member 10 are indicated to the voltmeter 54 and detector 58, respectively. If the track is eccentric, switch 25 closes and causes motor 24 to rotate, causing transducer L to move in a circular path opposite the selected track T. The radius, angular velocity and phase of this circular path of the transducer are determined by the eccentric circle M (third
If the radius, angular velocity and phase are exactly equal to those shown in FIG. On the other hand, if the transducer circular path is not equal to the eccentric circle, one or both of voltmeter 54 and detector 58 will indicate that condition by producing an appropriate indication. In such a case, phase controller 26 is adjusted until detector 58 indicates a zero condition. Motor 24 is then stopped by opening switch 25, and sleeve 32 is adjusted as necessary to cause a zero volt reading on voltmeter 54 when motor 24 is started again by closing switch 25. At this point, the transducer L follows the correct strategy to accurately compensate for the eccentricity of the track T.

Thereby, the compensation measuring device is disconnected from the playback machine at the input to the intensifier 48 and the disk 1 is
The reading circuit can be reconnected to retrieve information from zero. The phase controller 26 and sleeve 32 settings remain the same until another disk 10 is installed on the turntable 12. FIG. 5 shows another technique for moving the regenerative transducer L in a proper circular path to compensate for track eccentricity.

Here, the flexible rod 6 on which the transducer L is suspended
The rod is attached to one end of the crab body 6 with an open end.
2, and the other end of the rod is connected to the top surface of the sparrow. The ridge 62 is connected to the base member 22, which is roughly positioned to place the transducer L opposite a selected track of the disk 10. The rod 60 has a rectangular cross section;
A pair of pipelators 64 and 66 are positioned opposite adjacent sides of the rod 60 and are suitably fixed to the side walls of the parallax body 62.

These piperators 64 and 66 are driven by an alternating electrical signal from a voltage generator 68. The two piperators are operated in quadrature, so that a signal applied to one piperator, such as piperator 64, is applied via differentiating circuit 72.

Voltage generator 68 receives the signal from power supply 16 and has separately controllable phase and amplitude controllers 68a and 68b so that the amplitude and phase of its output signal can be individually varied. . With this configuration, the transducer L can be moved in a compensated circular path such that the radius of this circular path and its phase angle with respect to the rotation of the disk 10 can be adjusted to offset the eccentricity by appropriately adjusting the controllers 68a and 68b. It can be set so that it is exactly equal to the circle M (Fig. 3). In the configuration of FIG. 5, the movement of transducer L can be manually adjusted based on the readings of voltmeter 54 and detector 58 (FIG. 1) without the need to restrain the movement of the transducer.

However, it is more preferred that the controllers 68a and 68b set it automatically. That is, the intensifier 48 and the phase comparator 5
The signals from 6 are processed in a computer indicated by dotted lines 78 in FIG. The computer then determines the proper amplitude and phase settings for the voltage generator controllers 68a and 68b, and the pipe plates 64, 66 are energized to rotate transducer L to that point to compensate. The compensation determination circuit, including the computer, is then disabled. Of course, the computer 78 can also be used to calculate the phase settings of the structure of FIG. 1 and the settings of the sleeve 32. The compensation techniques described herein are relatively independent of the type of transducer used.

For example, transducer elements 36 and 38 may be placed opposite the tracks of disk 10 as disclosed in U.S. Pat. No. 3,840,893. In this case, the difference signals from the two transducers applied to intensifier 48 (FIG. 1) similarly serve to provide tracking and velocity compensation. The magnitude and phase angle of the track drum 0 relative to the rotation of the disk 10 can also be detected by observing the frequency variations of the output signal from the transducer. That is, when a certain analog or digital signal is recorded on the track T, its frequency is modulated by the rotational speed of the disk 10. In particular, section 4b
Its variation according to the curve of the figure is highest at point C and lowest at point A. Also, as shown by the dotted line in Figure 5,
Transducer L has a pair of auxiliary transducers, namely inner and outer auxiliary transducers L and L.
2 can be provided. In this case, the output signals of these auxiliary transducers are modulated as shown by FIGS. 4c and 4d. That is, point C in Figure 3
When the track T deviates outward from the transducer L, as in , the inner auxiliary transducer L, is located completely out of its track and therefore its output is zero, but in this case the outer auxiliary transducer L, Since L is located directly above the track, the output of this auxiliary transducer is maximum. On the contrary, when the track T deviates inwardly from the transducer L, as at point A in FIG. Meanwhile, outer transducer L2 is completely off its track and its output is zero. Therefore, these signals are used to control the intensifier 48 and comparator 56 (first
An error signal can be generated in FIG. In practice, any two of the signals in FIG. 4 may be used to accurately compensate for track deviation D by this technique.

After proper compensation, m in FIG. 4a becomes zero as described above. Also, the signal in FIG. 4b becomes a straight line, and the signals in FIGS. 4c and 4d approach zero and become continuous rather than intermittent. Typically, the transducer output signal (FIG. 4a) is always provided and one of the other signals is utilized. Otherwise, a two-element transducer producing two signals in quadrature phase shift, as in FIG. 4a, is used as described with respect to FIG. 1. FIG. 6 shows an embodiment of an apparatus useful for compensating for optical recording track eccentricity that occurs on video discs.

In this case, there is a track near the edge of the recording disk in which one frequency is recorded for "setting". If the track eccentricity occurs, the frequency of the signal read from the disk will change as shown in Figure 4b. In this configuration, information is read from the disk 10 by a radiation beam.

After generating the beam and interacting with the disk 10, the information contained in the disk is detected by an optical device housed in the sparrow body 82. The cliff body 82 is the base member 2
2 and the entire weight can be moved to roughly position the beam spot opposite a selected track T of the disk 10. This optical device includes a light source 84.

The light is collimated by a lens 86 and a semi-transparent mirror 8
8 to a movable mirror 92. This light beam is reflected by a mirror 92 and passes through a contrast lens 94 to reach a spot S on the disk 10. This ray is disk 1
0 information is reflected back to mirror 92 and onto mirror 98, which images the modulated beam to a detector 96 which generates a corresponding electrical signal, which is applied to data signal intensifier 60 (FIG. 1). Compensation for eccentric track T is done by mirror 9.
This is achieved by tilting the forehead.

In particular, this mirror 92 has hinges 10 on its adjacent edges.
2 and 103 are provided, these hinges being configured with respect to each other and to the support to permit tilting of the mirror 92 about two mutually perpendicular axes. The mutually perpendicular axes are such that when the mirror 92 is tilted about the hinge 102 the spot of light imaged onto the disc 10 is moved in the radial direction of the disc and the mirror 92 is tilted about the hinge 102.
When tilted around 3, the light spot is oriented so that it is moved in a direction perpendicular to the radius. Hisoji 102
A pair of pipers 104 and 106 are provided on the green side of the mirror facing 103 and 103, respectively.

The armature of the piperator is connected to the mirror so that the mirror can be erected or tilted relative to its two hinges. In practice, it is more convenient to arrange two separate mirrors in the beam path and to tilt each of them relative to one hinge. In either case, these piperators operate similarly and have the same function as piperators 64 and 66 of FIG. 5 in that they are driven in quadrature phase shift by a signal from voltage generator 68 (FIG. 5). achieve. Therefore, the phase and amplitude of the signal from the voltage generator 68 is such that the light spot S moves on the disk 10 along a circle with a radius, angular velocity and phase that match the eccentric circle M (FIG. 3). The mirror 92 is moved between its two hinges 10 so as to be imaged.
It is adjusted to be oblique around 2 and 103. The tracking error is detected by measurement detector 110, which is a grid similar to that disclosed in US Pat. No. 3,4015.

As stated in the above-mentioned US patent, an image corresponding to the pattern of tracks T and thus having a grating structure is placed on the detector 1.
Received by 10. By means of a suitable pick-up element, the position of the grid image of the track pattern relative to the grid detector 11 generates a signal representing the position of the scanning spot S on the disk 10'. Measurement detector 11
The zero output is applied to discriminator 114. Discriminator 1 14
The peak deviation of the signal from fo from the intensifier 4 in FIG.
8 and is applied to a voltmeter 54 and a comparator 56 as before, and is applied to a voltmeter 54 and a comparator 56, as before.
An indication of the magnitude of the eccentricity of the track T and its phase with respect to the rotation of is obtained. Also, as mentioned above with regard to Figure 5,
This information is processed by a computer and a voltage generator 6
8 can be used to automatically generate the required mid-oscillation and phase control signals. Once these controllers are properly set, the output of the voltage generator is applied to the piperators 104 and 106 as required to move the scanning beam spot S along a circle that coincides with the eccentric circle.
to tilt the mirror 92. In this regard, the sixth
The device shown can be operated in normal regeneration mode with the tracking device inactive. It is therefore clear from the above description that the technique described above can be used to move the reproducing transducer of a recording machine in such a way as to accurately compensate for the eccentricity of the recording track that occurs during reproduction. Furthermore,
The magnitude and phase angle of the eccentricity relative to the rotation of the recording member can be measured, and the proper settings can be made to move the transducer to compensate for the eccentricity before playback. Therefore, the servo-driven slack bodies used in known devices of this type are not required. The method and method of the present invention not only corrects for radial tracking errors due to eccentricity, but also compensates for speed fluctuations and timing variations caused by eccentricity.

Control signals or index points can therefore be recorded along the track at very closely spaced locations, yet reliably read by a playback machine. Thus,
More information can be packed into a given area of a recording member than was previously possible. The compensation device described above requires only a few simple parts so that its incorporation into a reclamation machine does not significantly increase the overall cost of such a machine.

It will be clear that the above objectives have thus been effectively achieved.

It should also be understood that variations may be made in the structure of the method and apparatus described above without departing from the scope of the invention. Therefore,
It is to be noted that all matter contained in the above description and accompanying drawings is intended to be illustrative of the invention and not to limit the invention. It is also to be understood that the claims encompass all the general and specific features of the invention described above.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a device according to the present invention for compensating for track eccentricity occurring on a recording member during reproduction, FIGS. 2 and 3 are diagrams showing a compensation method used in the device of FIG. 1,
4a to 4d are graphs for explaining the present invention, FIG. 5 is a block diagram showing another embodiment of the present invention, and FIG. 6 is a diagram showing still another embodiment of the present invention. be. 10...Disc, T...Circular track, T'...Track T
center, X...center of rotation, L...transducer, M...eccentric circle, N...correct path, 12...
Turntable, 14...Synchronous motor, 16...Power supply, 17
...Arm, 18...Flexible rod, 22...Base member, 24...Small AC motor, 24a...
Field coil, 24b... Armature, 25... Switch, 26... Variable phase controller, 28... Shaft, 32... Sleeve, 36, 38... Pair of magnetic elements, 36a , 38a... electromagnetic coil, 36b, 38b
...Magnetic pole and air gap portion, 42...Resistance, 44.
...Potentiometer, 48...Error signal intensifier,
54... Voltmeter, 56... Phase comparator, 58...
Winding detector, 60...data signal intensifier. FIG. l FIG. 2 FIG. 3 FIG. 5 FIG. 4q FIG. 4b FIG. 4c FIG. 4d FIG. 6

Claims (1)

[Claims] 1. Tracking error and speed in a reproducing device when reading information from a rotating recording member having an eccentric recording track in which the center of the recording track moves along an eccentric circle around the rotational axis of the recording member. A method for compensating for both errors, comprising: mounting information reading means for movement in a circular path opposite a recording track on a recording member; and moving said information reading means around said circular path. operating the reproducing device in a set mode; adjusting the radius of the circular path to be equal to the distance between the axis of rotation of the recording member and the center of the eccentric recording track; and the information reading means. adjusting the phase of the motion of the recording member to a phase corresponding to the phase angle of the instantaneous position of the center of the eccentric recording track around the rotational axis of the recording member, the information reading means recording during the reproduction period. A method for compensating for tracking errors and speed errors, characterized in that the reproduction device is operated in a normal reproduction mode by giving the information reading means a movement adjusted as described above so as to follow the track. . 2. The method according to claim 1, wherein the information reading means is moved in a circular path by simultaneously displacing the recording member along a radius of the center of rotation and a straight line perpendicular to the radius. 3. The step of adjusting the radius of the circular path determines the magnitude of the amplitude or frequency modulation caused by the eccentricity of the recording track in the signal generated by the reading means for reading information from the recording track, and the adjusted radius is applied to the amplitude or frequency modulation caused by the eccentricity of the recording track. The phasing of the movement of the reading means is carried out by determining the phase difference between said modulation and the rotation of the recording member, and adjusting the phase of said movement to be proportional to the magnitude of the modulation. 2. The method according to claim 1, which is carried out by selecting the phase to be equal. 4. The method of claim 3, wherein the magnitude of the modulation is determined by measuring the difference between the frequency of the signal from the transducer and a fixed reference frequency. 5. Determining the magnitude of modulation by generating a signal representing the difference between signal levels read from a recording track at a pair of points along a straight line at an angle to the recording track. The method described in Section 3. 6. Claims 3 and 4, wherein the phase difference is determined by measuring the phase difference between the signal from the transducer and a second signal synchronized with the rotation of the recording member. or the method described in any of paragraph 5. 7. A device for compensating for both tracking error and speed error in a reproducing device when reading information from a flat plate-shaped rotating recording member having an eccentric recording track whose center rotates around the rotational axis of the rotating member along an eccentric circle. the reproducing device is set to a setting mode, the reproducing device comprising: an information reading means mounted to move in a circular path facing a recording track on a recording member; and means for moving the information reading member around the circular path; means for adjusting the radius of the circular path to equalize the distance between the rotation axis of the recording member and the center of the eccentric recording track; means for adjusting the phase to correspond to the phase angle of the instantaneous position of the center of the eccentric recording track about the axis of rotation; A device for compensating tracking and velocity errors, characterized in that it comprises means for operating the regeneration device in a normal regeneration mode by applying a circular motion with path radius adjustment and motion phase adjustment. 8 The means for moving the information reading means around the circular path includes a first displacement means for displacing the transducer in a direction along the radius of the rotation center of the recording member, and a first displacement means for displacing the transducer in a direction along the radius of the rotation center of the recording member. and second displacement means for displacing along a straight line perpendicular to . 9. The circular path radius adjusting means includes means for determining the amplitude or frequency modulation caused by the eccentricity of the recording track in the signal generated by the information reading means when the information reading means reads information from the recording track; The motion phase adjusting means includes means for determining the phase difference between said modulation and the rotation of the recording member, and the compensation device includes means for moving the information reading means in a circular path whose radius is proportional to the magnitude of said modulation. In order to move with a phase equal to the phase of the above modulation,
9. The apparatus according to claim 7, further comprising means for controlling means for interlocking the information reading means. 10. The information reading means includes a pair of reading elements arranged in a straight line substantially perpendicular to the recording track to generate a pair of signals 180° out of phase, and the modulation magnitude determining means includes: 10. The apparatus of claim 9, further comprising means for determining the amplitude difference of the signals generated by the read elements. 11. The modulation magnitude determining means includes fixed reference frequency generating means and means for determining the difference between the frequency of the signal generated from the information reading means and the reference frequency to generate a difference signal, 10. Apparatus according to claim 9, wherein the means for moving the information reading means are controlled by said difference signal. 12 The phase difference determining means includes means for generating a second signal synchronized with the rotation of the recording member, and means for comparing the phase of the difference signal and the second signal to generate a phase error signal, and 10. Apparatus according to claim 9, wherein the phase adjustment means are controlled in accordance with said phase error signal. 13. Claim 9, wherein the phase difference determining means includes means for generating a second signal synchronized with the rotation of the recording member, and means for comparing the phase of modulation and the phase of the second signal. Apparatus described in section. 14. The apparatus of claim 12 or 13, wherein the second signal generating device includes a tachometer coupled for rotation with the recording member. 15. The information reading means is mounted on an elongated flexible member extending along the second axis, and the means for moving the information reading means includes a weight attached to the flexible member and a weight that is attached to the flexible member. means for rotatably mounting radially outwardly from the second axis; means for rotating the weight about the second axis; and means for rotating the weight in phase with the modulation of the signal from the information reading means. and means for adjusting the phase of the weight rotation means to cause the flexible member to flex from the second axis to move the information reading means in a circular path. An apparatus according to any one of claims 9 to 14. 16 The information reading means is mounted on an elongated flexible member extending along one axis, and the means for moving the information reading means moves the flexible member from the one axis to the recording member. a first bending means for bending in a direction parallel to the radius of the rotation center; and a first bending means for bending the flexible member from the one axis along a straight line perpendicular to the radius of the rotation center of the recording member; a second flexing means; means for driving each of the first and second flexing means in orthogonal relation to each other so as to flex the flexible member along a circular path; means for controlling the means driving means with a phase equal to the phase of the modulation of the signal from the information reading means; and means for controlling the amplitude of said bending means driving means to make the radius of the circular path proportional to the magnitude of said modulation. 15. An apparatus according to any one of claims 9 to 14, comprising: 17 The first and second bending means are comprised of a pair of vibrators, and the bending means driving means is comprised of a voltage generator that provides an alternating current signal to each of the vibrators to control the amplitude of the bending means driving means. 17. The apparatus of claim 16, wherein the means for controlling separately the amplitude and phase of the output from the voltage generator.