JPH11273276A - Disk drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy and also to prevent the increase of the device scale due to the feedback mechanism by eliminating the control error in the feedback mechanism which is used for detecting the position of a pickup and feeding it back to the operation of the thread feeding mechanism. SOLUTION: A magnet 18 on which N-poles and S-poles are alternately magnetized on the outer peripheral surface 20, is arranged in the rotation system of the thread feeding mechanism 7 so as to rotate in accordance with the operation of the thread feeding mechanism, and also a magnetic reluctance detecting element 19 is arranged so as to confront with the outer peripheral surface of the magnet, then the position of the pickup 6 is detected by such a manner that the magnetic borders of the N-poles and S-poles are detected by the magnetic reluctance detecting element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving the movement accuracy of a thread feed mechanism for moving a pickup in a disk drive.

[0002]

2. Description of the Related Art In a disk drive device for writing information on a disk-shaped recording medium (hereinafter, referred to as a "recording medium disk") and / or reading information recorded on the recording medium disk, information writing is performed. The pickup for reading and / or reading is freely moved from the inner periphery to the outer periphery of the recording medium disk by a thread feed mechanism driven by a so-called thread motor.

The control of the thread feed mechanism is performed based on information obtained from a feedback mechanism for information on the position of a pickup provided in a transmission path for transmitting the rotation of the thread motor.

FIGS. 7 and 8 schematically show the structure of a feedback mechanism a in a conventional disk drive device. The feedback mechanism a is provided, for example, coaxially with the rotation axis of a sled motor b. So-called FG
(Frequency Generator) This is a so-called thread servo in which the position of the pickup is detected by a detecting means and this is fed back to the operation of the thread motor.

The feedback mechanism a is coaxial with the rotation axis of the sled motor b and is provided on the lower surface d of a disk-shaped FG magnet c which rotates with the rotation of the sled motor b.
N poles and S poles are alternately magnetized at equal intervals, and opposed to the lower surface d, as a magnetic sensor, for example, two Hall elements e
And f with respect to the magnetization pattern of the FG magnet c are 9
It is arranged on the substrate g so as to have a positional relationship of 0 degree phase.

Therefore, when the FG magnet c rotates,
The Hall elements e and f detect the magnetic boundary between the N pole and the S pole of the FG magnet c and output sinusoidal electric signals having phases different from each other by 90 degrees. Thus, the thread servo performs the feedback control of the thread feed mechanism (thread motor).

[0007]

However, the feedback mechanism a in the conventional disk drive has the following problems.

That is, the substrate g is necessary only for arranging the hall elements e and f, which adversely affects the size reduction and cost reduction of the disk drive device.

In addition, since the Hall elements e and f are mounted on the substrate g by soldering, the positioning accuracy of the Hall elements e and f varies greatly, thereby causing an error in feedback control. There was a problem. This is because the output values of the Hall elements e and f are reduced due to the radial displacement of the FG magnet c, or the Hall elements e and f are respectively displaced in the circumferential direction of the FG magnet c. Is caused by the fact that the phase of the sinusoidal FG output signal deviates from 90 degrees.

Further, in the case of using the two Hall elements e and f, such as the feedback mechanism a, the phase of the sine-wave FG output signal tends to shift due to the above-mentioned problem relating to the positioning accuracy. There has been a problem that the magnetization pitches of the N and S poles of the FG magnet c can be reduced only within a range in which the variation in the positions of the Hall elements e and f can be absorbed. This limits the resolution of the feedback mechanism a, so that the thread feed mechanism transmits the rotation of the thread motor b to the pickup via a transmission mechanism having a large reduction ratio, that is, the rotation of the thread motor b. If the rotation of the sled motor b for a certain amount of movement of the pickup is not increased and the resolution of the FG detecting means is not increased in a pseudo manner than when the pickup is directly transmitted to the pickup, the information of the feedback mechanism a is used. Makes it difficult to move the pickup minutely. In the above-described thread feed mechanism, the pickup drives the rotation of the thread motor b via a transmission mechanism having a large reduction ratio, and thus has a disadvantage that the thread feed mechanism is complicated and large.

Further, since the Hall elements e and f are attached to the substrate g by soldering, the heights of the magnetic detection surfaces thereof vary, and as a result, F
The gap (gap) between the lower surface d of the G magnet c and the Hall element e differs from that of the Hall element e, and the output value of the signal varies, causing an error in the feedback control of the thread feed mechanism. there were.

Therefore, the present invention improves the accuracy by eliminating the control error in the feedback mechanism for detecting the position of the pickup and feeding it back to the operation of the sled feed mechanism, and improving the device caused by the feedback mechanism. It is an object to prevent an increase in size.

[0013]

In order to solve the above-mentioned problems, a disk drive device according to the present invention comprises a thread feeding mechanism in which a magnet having N poles and S poles alternately magnetized on the outer peripheral surface is provided in a rotating system of a thread feeding mechanism. The pickup is arranged so as to rotate with the operation of the feed mechanism, and a magnetoresistive detecting element is arranged opposite to the outer peripheral surface of the magnet, and the magnetic boundary between the N pole and the S pole is detected by the magnetoresistive detecting element. Is detected.

Therefore, since the two-phase FG output signal is obtained by one magnetic resistance detecting element, it is not necessary to use a plurality of magnetic sensors as in the case of using a Hall element as a magnetic sensor. It is possible to prevent the phase of the FG output signal from deviating due to the error of (1), and to reduce the magnetization pitch of the N pole and S pole of the magnet, thereby improving the resolution of position detection of the pickup. It becomes possible.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a disk drive device according to an embodiment of the present invention. still,
In the illustrated embodiment, the present invention is applied to a CD-ROM drive.

FIGS. 1 to 3 show a first embodiment.

As schematically shown in FIG. 1, the CD-ROM drive 1 has a base unit 2 disposed in a casing (not shown). The base unit 2 is a sheet metal on which various members described later are mounted. A chassis 3 made of a material is supported on the housing by rubber dampers 4, 4, 4.

On the chassis 3, a turntable 5, an optical pickup 6, a thread feed mechanism 7, and the like, which are rotated by a spindle motor (not shown), are mounted.

The optical pickup 6 is supported by a guide shaft 8 and a sub-guide shaft 9 and is clamped on the turntable 5 by a recording medium disk (hereinafter, “disk”).
That. And (10) movable in the radial direction.

The thread feed mechanism 7 includes a thread motor 1
1, a drive gear 13 connected to a rotation shaft 12 of the thread motor 11, a rack member 14 connected to the optical pickup 6 and meshing with the drive gear 13 to constitute a rack and pinion mechanism, an FG detection mechanism 15, and the like. It has. The support plate 16 for supporting the sled motor 11 is fixed to the lower surface of the chassis 3 as shown in FIG. 1, and the sled motor 11 projects upward from the sled motor opening.

The support plate 16 is provided with the thread motor 1.
The drive gear 13 is formed integrally with the outer periphery of the rotor 17 of the thread motor 11. That is, a stator coil (not shown) is arranged on the support plate 16, and the rotor 17 integrated with the drive gear 13 is supported by the rotating shaft 12 so as to cover the periphery of the stator coil. It is arranged rotatably.

Therefore, the rotor 17 of the sled motor 11
Is rotated from the drive gear 13 to the rack member 14, and is converted into parallel movement, thereby moving the optical pickup 6 in the radial direction of the disk 10 on the turntable 5.

As shown in FIGS. 2 and 3, the FG detecting mechanism 15 is integrally disposed on a support plate 16 of the sled motor 11, has an FG magnet 18 and a magnetic sensor 19, and has a sled motor. By directly detecting the rotation angle of the optical pickup 11, information on the amount of movement of the optical pickup 6 is detected and fed back to control the rotation of the sled motor 11 by, for example, a sled servo or the like.

That is, as shown in FIGS. 2 and 3, a substantially annular FG magnet 18 is integrally formed on the outer periphery of the rotor 17 and below the drive gear 13 or separately. Is connected and fixed (externally fitted to the outer periphery of the rotor 17).
It is formed by doing. The FG magnet 1
Reference numeral 8 denotes an N-pole and an S-pole alternately magnetized on the outer peripheral surface 20 at equal intervals.

As described above, when the magnetic sensor 19 is arranged on the support plate 16 which is the stator substrate of the thread motor 11, a substrate necessary only for mounting the magnetic sensor 19 is not required. Becomes possible.

As the magnetic sensor 19, for example, an MR (magnetic resistance detection) element is used, and a sine wave FG output signal having a phase difference of 90 degrees is output. As shown in FIG. Detecting surface 21 is FG magnet 1
The thread motor 11 is disposed so as to face the outer peripheral surface 20 and is attached to the support plate 16 of the thread motor 11 by screwing. Note that the configuration of the magnetic sensor 19 is not limited to the above, and the number and phase of the FG output signal can be freely selected by using a plurality of MR elements.

When the rotor 17 of the sled motor rotates, the FG magnet 18 also rotates at the same time, and the magnetic sensor 19 detects the magnetic boundary between the N pole and the S pole of the FG magnet 18. 1
9 outputs a sinusoidal FG output signal having a phase difference of 90 degrees. The FG from the magnetic sensor 19
The output signal is input to a thread servo circuit (not shown) for controlling the operation of the thread motor 11. Then, the thread servo circuit outputs the FG output signal to the thread motor 11.
Is processed as information relating to the rotation angle of the optical pickup 6, that is, the current position of the optical pickup 6, and this information is fed back to the operation of the thread motor 11 to control the position of the optical pickup 6.

FIGS. 4 to 6 show a second embodiment of the disk drive device of the present invention. The CD-ROM drive device 30 according to the second embodiment described below is the same as the CD-R drive device according to the first embodiment.
The OM drive device 1 is different from the OM drive device 1 only in the structure of the thread feed mechanism and the location of the FG detection mechanism, and the other parts have basically the same configuration, although the shape and structure of the details are different. The same reference numerals as in the first embodiment denote the same parts as those in the first embodiment, and a detailed description thereof will be omitted.

As shown schematically in FIG. 4, the CD-ROM drive 30 has a base unit 31 disposed in a casing (not shown), and the base unit 31 has various members described later mounted thereon. A chassis 32 made of a sheet metal material is supported on the housing by rubber dampers 4, 4,....

On the chassis 32 are mounted a turntable 5, which is rotated by a spindle motor (not shown), an optical pickup 6, a thread feed mechanism 33, and the like.

The optical pickup 6 is supported by a guide shaft 8 and a sub-guide shaft 9 and is clamped on the turntable 5 by a recording medium disk (hereinafter, “disk”).
That. And (10) movable in the radial direction.

The sled feed mechanism 33 includes a sled motor 34, a first drive gear 36 connected to a rotating shaft 35 of the sled motor 34, and a rack member 14 connected to the first drive gear 36 and the optical pickup 6. Second to fourth drive gears 37, 38 interposed as a speed reduction mechanism between
39 and an FG detection mechanism 40. The sled motor 34 is fixed to the lower surface of the chassis 32, and the rotation shaft 35 of the sled motor 34 projects upward.

The second drive gear 37 and the third drive gear 38 are arranged coaxially, that is, a third drive gear having a small diameter is fixed below the second drive gear 37 having a large diameter. Have been. Therefore, the first drive gear 36 and the second drive gear 37 mesh with each other, the third drive gear 38 meshes with the fourth drive gear 39 having the largest diameter, and the fourth drive gear 39
Is also engaged with the rack member 14 to function as a pinion gear.

Accordingly, when the sled motor 34 rotates, the rotational movement thereof is transmitted to the fourth drive gear 3 via the first drive gear 36, the second drive gear 37, and the third drive gear 38.
9, and the rotational motion of the fourth drive gear 39 is transmitted to the rack member 14 and converted into parallel motion,
Put the optical pickup 6 on the disc 1 on the turntable 5
0 in the radial direction.

The FG detecting mechanism 40 has an FG magnet 41 and a magnetic sensor 19, as shown in FIGS. 5 and 6, and detects the rotation angle of the sled motor 34 so that the moving amount of the optical pickup 6 can be changed. And detects the information on the feedback and feeds it back to control the rotation of the sled motor 34 by, for example, a sled servo.

That is, as shown in FIGS. 5 and 6, the FG magnet 41 has a substantially disk shape. It is fixed coaxially with the second drive gear 37 and the third drive gear 38 and is arranged above the second drive gear 37. The FG magnet 41 has an outer peripheral surface 42.
And N poles and S poles are alternately magnetized at equal intervals.

The magnetic sensor 19 is connected to the sensor substrate 4
3 on the sensor substrate 4 by an appropriate method.
3 is fixed on the chassis 32 by screws or the like, as shown in FIGS. Note that the magnetic sensor 19 may be directly fixed to the chassis 32 instead of being fixed on the sensor substrate 43.

When the sled motor 34 rotates, as described above, the rotation of the sled motor 34 causes the first drive gear 3 to rotate.
6 and transmitted to the second drive gear 37 at a reduced speed. Then, the FG magnet 41 also rotates at the same time as the second drive gear 37, and the magnetic boundary between the N pole and the S pole of the FG magnet 41 is detected by the magnetic sensor 19. Is output. The FG output signal from the magnetic sensor 19 is input to a thread servo circuit (not shown) for controlling the operation of the thread motor 34, and the thread servo circuit outputs the FG output signal to the rotation angle of the thread motor 34, that is, the optical pickup. 6 is processed as information on the current position, and this information is fed back to the operation of the thread motor 34 to control the position of the optical pickup 6.

It should be noted that F described in each of the above embodiments is used.
The G detection mechanism is used not only in a drive using a compact disk (CD) such as a CD-ROM drive, but also in a drive device using another disk-shaped recording medium such as a so-called DVD, MD, MO, HD, and LD. A pickup for reading or writing information recorded on a disk-shaped recording medium may be used as a feedback mechanism for feedback-controlling a thread motor necessary for moving the disk-shaped recording medium from the inner circumference to the outer circumference. It is possible.

Further, the FG detecting mechanism using an MR element as a magnetic sensor can reduce the error of position detection of the pickup and improve the resolution, so that the driving force of the sled motor in the disk drive device is picked up. A method in which a thread feed mechanism for transmitting to a drive directly drives a pickup by a drive gear attached to a rotation shaft of a thread motor, and one or more other gears are interposed between the drive gear and the pickup in order to obtain a reduction ratio. It becomes possible to correspond to both methods. The point is that any mechanism that can provide the FG detection mechanism in the power transmission path of the thread feed mechanism can be used.

Further, in a thread feed mechanism having a configuration in which the FG magnet does not need to make one or more rotations in a range in which the pickup moves from the inner circumference to the outer circumference of the disk-shaped recording medium, the attachment to the FG magnet is not performed. The magnet is
Only the range of the rotation angle of the FG magnet may be used. In this case, the outer shape of the FG magnet does not need to be circular, and may be any suitable shape that can detect magnetism with a magnetic sensor such as a fan.

[0042]

As is apparent from the above description, the disk drive apparatus of the present invention includes a magnet in which the N pole and the S pole are alternately magnetized on the outer peripheral surface in the rotation system of the thread feed mechanism. And a magnetoresistive detecting element is arranged to face the outer peripheral surface of the magnet, and N is detected by the magnetoresistive detecting element.
The position of the pickup is detected by detecting the magnetic boundary between the pole and the S pole. Since a two-phase FG output signal is obtained by one magnetoresistive detecting element, a Hall element is used as a magnetic sensor. As described above, it is not necessary to use a plurality of magnetic sensors, it is possible to prevent the phase of the FG output signal from being shifted due to an error in the mounting position of the magnetic sensor, and to attach the N and S poles of the magnet. This makes it possible to reduce the magnetic pitch, thereby improving the resolution of position detection of the pickup, making it possible to move the pickup extremely minutely and to quickly move the pickup to an arbitrary position.

According to the second aspect of the present invention, since the magnet is arranged coaxially with the thread motor, the magnetic sensor can be provided integrally with the thread motor, so that the disk can be provided. This can contribute to downsizing of the drive device.

Further, according to the third aspect of the present invention, the sled feed mechanism is of a type in which the pickup is directly driven by a drive gear fixed to the rotary shaft of the sled motor, so that the sled feed mechanism is downsized. It is possible to reduce the size of the entire disk drive device.

It should be noted that the specific shapes and structures of the respective parts shown in the above-described embodiment are merely examples for embodying the present invention, and the technical features of the present invention will be described below. The scope should not be construed as limiting.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the disk drive device of the present invention together with FIG. 2 and FIG. 3, and FIG. 1 is a plan view showing an overall outline.

FIG. 2 is an enlarged plan view showing a main part.

FIG. 3 is an enlarged side view showing a main part.

FIG. 4 shows a second embodiment of the disk drive device of the present invention together with FIGS. 5 and 6, and FIG. 4 is a plan view showing the overall outline.

FIG. 5 is an enlarged plan view showing a main part.

FIG. 6 is an enlarged sectional view taken along the line VI-VI of FIG. 4;

7 shows an example of a feedback mechanism in a conventional disk drive together with FIG. 8, and FIG. 7 is a plan view.

FIG. 8 is a side view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Disk drive device, 6 ... Pickup, 7 ... Thread feed mechanism, 10 ... Disk-shaped recording medium, 11 ... Thread motor, 13 ... Drive gear, 18 ... Magnet, 1
9: magnetic resistance element, 20: outer peripheral surface, 30: disk drive device, 33: sled feed mechanism, 34: sled motor, 41: FG magnet, 42: outer peripheral surface

Claims (3)

[Claims] 1. A disc feed mechanism driven by a thread motor, which is movable in a radial direction of a disc-shaped recording medium, reads information recorded on the disc-shaped recording medium, and / or reads information on the disc-shaped recording medium. In a disk drive device having a pickup for performing the recording of (i), a magnet in which the N pole and the S pole are alternately magnetized on the outer peripheral surface is rotated in the rotation system of the sled feed mechanism in accordance with the operation of the sled feed mechanism. In addition to the arrangement, a magnetic resistance detecting element is disposed so as to face the outer peripheral surface of the magnet, and the position of the pickup is detected by detecting the magnetic boundary between the N pole and the S pole by the magnetic resistance detecting element. Characterized disk drive device. 2. The disk drive device according to claim 1, wherein the magnet is arranged coaxially with the sled motor. 3. The disk drive device according to claim 2, wherein the thread feed mechanism is configured to directly drive the pickup by a drive gear fixed to a rotation shaft of the thread motor.