JP2001215131A - Rotation detector, production method of the rotation detector and pickup drive mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exactly detect rotation state of a gear and a pinion to be detected even with generation of a slip between a motor shaft and the pinion by combining a magnet and the gear or the pinion. SOLUTION: On the plane of a drive gear 4 pressed into the motor shaft of a motor, a plurality of dents 21 are formed radially for holes 20 with the same intervals when forming the resin of the drive gear 4. By filling the dents 21 with magnetic powder and pressing, a magnetic body with the same shape of the dents 21 is formed in the dents 21. By giving a strong magnetic field to the magnetic body in the shaft direction of the drive gear 4, feeble magnetic field regions are magnetized to be turned to magnets. The variation of the magnetic flux due to rotational movement of the magnets is detected with a magnetic field sensor so that the rotation state of the drive gear 4 can be exactly detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to an optical disk drive, an information recording medium drive such as an HDD, FDD, ZIP or the like, or a copying machine. The present invention relates to a rotation detecting device for obtaining the information, a manufacturing method thereof, and a pickup driving mechanism applied to the information recording medium driving device as described above.

[0002]

2. Description of the Related Art An optical pickup provided in an optical disk drive device focuses a light beam emitted by a semiconductor laser as a light source on an objective lens to form a light spot, and shines the light spot on an optical disk as an information recording medium. Recording, reproducing, and erasing information. In order to perform such an operation, an optical pickup driving mechanism for moving the optical pickup in the radial direction of the disk-shaped optical disk so that the optical pickup faces the information recording position on the optical disk surface is required.

A conventional technique of this kind is disclosed in
There is an optical pickup device described in JP-177740A. According to this publication, a configuration is described in which a drive shaft of a drive motor protrudes from both ends of the drive motor, a gear or pinion is provided at one motor shaft end, and an encoder plate is provided at the other end.

FIG. 7 is an explanatory view showing a main part of a conventional optical pickup driving mechanism, wherein 50 is a motor, 51 is a driving gear, 52 is an encoder plate having a plurality of slits provided radially and at equal intervals, A drive gear 51 and an encoder plate 52 are provided on a motor shaft of the motor 50. 5
3, 54 are intermediate gears, 55 is a lead screw,
The intermediate gear 54 is fitted to a lead screw 55, and the driving gear 51 and the intermediate gear 54 are meshed with the intermediate gear 53. 56 is a pickup, 57 is a leaf spring, 5
Numeral 8 denotes a rack, and a rack 56 is elastically supported via a leaf spring 57 on a pickup 56, only a part of which is shown, and the rack 58 is engaged with a lead screw 55. Reference numeral 59 denotes a photointerrupter. The photointerrupter 59 has a built-in LED, which is a light emitting source, and a PD, which is a photoelectric conversion element, facing each other.
Is arranged on one surface side of the encoder plate 52, and PD is arranged on the other surface side of the encoder plate 52.

When the motor 50 rotates, the driving force output from the motor 50 is transmitted to the intermediate gear 54 via the driving gear 51 and the intermediate gear 53, and the lead screw 55 rotates, and the rotation is transmitted to the rack 58. As a result, the pickup 56 is driven and moves along the axial direction of the lead screw 55.

Further, when the encoder plate 52 rotates together with the drive gear 51, the luminous flux emitted from the LED is blocked by the encoder plate 52 or not blocked by the slit, so that the output of the PD changes. As a result, the rotation state of the encoder plate 52 can be detected based on the output of the PD, and the position information of the pickup 56 can be obtained.

[0007]

The above-mentioned prior art has the following problems.

In optical detection using a photo interrupter, erroneous detection may be performed when dust or dirt is attached to a slit. Further, since the sensor requires a light source and a photoelectric conversion element, it is impossible to reduce the size of the photointerrupter itself.

In optical detection using a photo interrupter, the detection resolution is the width of the slit. In order to achieve a smaller resolution, it is necessary to process the slit width to be small. However, in resin molding, the limit is about 0.5 to 0.7 mm. Therefore, the detection resolution is 0.5 mm or more.

Therefore, if magnetic detection is used instead of optical detection, a magnet is required as an object to be detected. However, at present, it is difficult to integrally form the magnet and a transmission means such as a gear or a pinion. If it is difficult to integrally form the magnet and the transmission means, the cost of parts (the cost of parts simply due to the large number of parts, the cost of transportation) and the cost of assembling (two parts for assembling to the motor shaft) It is not possible to reduce the number of processes and the cost of process time).

If it is difficult to integrally form the magnet and the transmission means, it is necessary to separate the magnet and the transmission means and fix them to the motor shaft. In this case, the motor shaft and the transmission means slip and slip. Does occur, the magnet does not slip because it is fixed to the motor shaft separately from the transmission means.
The magnet will rotate even if the transmission means is not rotating.
That is, the rotation state of the transmission means to be detected cannot be accurately detected.

It is an object of the present invention to provide a rotation detecting device and a pickup driving mechanism which solve the above problems, prevent the above-described erroneous detection, and realize a fine detection resolution. I do.

[0013]

According to a first aspect of the present invention, there is provided a rotation detecting device fixed to a rotary shaft provided in a rotary drive source and transmitting the rotation of the rotary shaft to another drive system. In a rotation detecting device that detects a rotation state of a drive transmission unit, magnetic powder is pressed into a plurality of recesses formed in the drive transmission unit, and a magnetic field in a fixed direction is applied to each of the plurality of recesses. Forming a minute magnetic area formed by magnetizing the magnetic powder in a certain direction, and a magnetic field detecting means for detecting a change in a magnetic field generated from the minute magnetic area, and driving based on an output of the magnetic field detecting means. The rotation state of the transmission means is detected. With this configuration, the drive transmission means and the micro magnetic area can be easily integrated, and even if the drive transmission means is displaced from the rotation axis by slipping, the micro magnetic area is simultaneously moved with respect to the rotation axis. Due to the deviation, erroneous detection can be prevented.

Further, the rotation detecting device of the present invention is a rotation detecting device which is fixed to a rotation shaft provided in a rotation driving source and detects a rotation state of a drive transmission means for transmitting the rotation of the rotation shaft to another driving system. In forming the drive transmission means, a sheet metal material having a concave portion is integrated by insert molding, a magnetic powder is pressed into the concave portion, and a magnetic field is applied to each of the magnetic powders of the plurality of concave portions. Forming a minute magnetic area formed by magnetizing the magnetic powder in a certain direction, and a magnetic field detecting means for detecting a change in a magnetic field generated from the minute magnetic area, and driving based on an output of the magnetic field detecting means. The rotation state of the transmission means is detected. With this configuration, the drive transmission means and the micro magnetic area can be easily integrated, and even if the drive transmission means is displaced from the rotation axis by slipping, the micro magnetic area is simultaneously moved with respect to the rotation axis. Due to the deviation, erroneous detection can be prevented.
In addition, since the shape of the concave portion can be stabilized, the minute magnetic sections can be arranged at an accurate pitch.

Further, the rotation detecting device according to the present invention is characterized in that the recess is formed by etching. With this configuration, the concave portions can be formed at a more accurate pitch.

Further, the rotation detecting device of the present invention is a rotation detecting device which is fixed to a rotating shaft provided in a rotating drive source and detects a rotating state of a drive transmitting means for transmitting the rotation of the rotating shaft to another driving system. In the above, the drive transmission means is a gear, and in this gear, magnetic powder is press-fitted into a groove between teeth in a region other than a region meshing with the drive transmission means of another drive system, and into each magnetic powder of the plurality of grooves. On the other hand, magnetic powder is press-fitted into the plurality of recesses formed in the drive transmission means, and a magnetic field in a fixed direction is applied to the magnetic powder in each of the plurality of recesses to magnetize the magnetic powder in a fixed direction. Forming a minute magnetic area, comprising magnetic field detecting means for detecting a change in a magnetic field generated from the minute magnetic area, and detecting a rotation state of the drive transmission means based on an output of the magnetic field detecting means. I do. With this configuration, the drive transmission means can be easily integrated with the micro magnetic area,
Even if the drive transmission means shifts with respect to the rotation axis due to slippage, the micro magnetic area also shifts with respect to the rotation axis at the same time, so that erroneous detection can be prevented. Further, there is no need to specially process the drive transmission means to provide the minute magnetic area.

Further, the rotation detecting device according to the present invention is characterized in that the magnetic field detecting means is constituted by a magnetoresistive element. With this configuration, the detection resolution can be improved.

Further, the optical pickup driving mechanism of the present invention comprises:
An optical pickup for recording, reproducing, and erasing information by forming a light spot on an information recording medium; a rotary drive source for driving the optical pickup; and a drive provided at the tip of a rotary shaft of the rotary drive source Transmission means, drive conversion means for converting rotational movement into linear movement of the optical pickup, and intermediate transmission means for transmitting rotation of the drive transmission means to the drive conversion means; In a pickup drive mechanism driven in a direction parallel to a plane, the rotation detection device of the present invention described above is provided for detecting the rotation state of the rotation drive source, and the optical pickup is provided based on a detection result of the rotation detection device. Is acquired. With this configuration, the drive transmission means and the micro magnetic area can be easily integrated, and even if the drive transmission means is displaced from the rotation axis by slipping, the micro magnetic area is simultaneously moved with respect to the rotation axis. Since misdetection can be prevented due to the displacement, the reliability of the position information of the optical pickup acquired based on the detection result of the rotation detecting device is improved.

Further, the method for manufacturing a rotation detecting device according to the present invention comprises:
A plurality of magnetized bodies are provided in a drive transmission unit fixed to a rotation shaft provided in a rotary drive source and transmitting the rotation of the rotation shaft to another drive system, and a magnetic field generated from the magnetized body is detected by a magnetic field detection unit. A manufacturing method for manufacturing a rotation detection device that detects a rotation state based on an output of the magnetic field detection means, wherein pressure is applied to the magnetic powder disposed at a predetermined position of the drive transmission means to solidify the magnetic powder. Forming a plurality of magnetized bodies by applying a magnetic field to the solidified magnetic powder and magnetizing the solidified magnetic powder in a certain direction. With this configuration, the drive transmission unit and the magnetized body that generates the magnetic field can be easily integrated.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory view showing a main part of an apparatus according to an embodiment of the present invention, wherein 1 is a motor, 2 is a bracket for holding the motor 1, 3 is a base for fixing the bracket 2, and the motor 1 is It is fixed to the base 3 via the bracket 2. 4 is a drive gear fixed to the motor shaft of the motor 1, 5 is a magnetic field detection sensor arranged near the drive gear 4, 6 and 7 are intermediate gears, 8 is an intermediate transmission shaft, and 9 is a lead screw. The intermediate gear 6 is fitted to the intermediate transmission shaft 8, the intermediate gear 7 is fitted to the lead screw 9, and both the intermediate transmission shaft 8 and the lead screw 9 are rotatably held by the bracket 2. The intermediate gear 6 meshes with the gear 7.

10 is a pickup, 11 is a leaf spring, 12
Indicates a rack. A preload is applied to the lead screw 9 by being pressed in the axial direction by the leaf spring 11. A leaf spring 11 is fixed to the pickup 10 of which only a part is illustrated, and a rack 12 is elastically supported at a free end of the leaf spring 11. A preload is applied to the screw 9 by pressing in the axial direction by a leaf spring 11.

When the motor 1 rotates, the driving force output from the motor 1 is transmitted to the intermediate gear 7 via the driving gear 4 and the intermediate gear 6 to rotate the lead screw 9, and the rotation is transmitted to the rack 12. You. Then, the rotational torque given to the lead screw 9 by the rack 12 is converted into a thrust for driving the pickup 10 in the radial direction of the disc-shaped information recording medium (not shown). The preload for pressing the rack 12 against the lead screw 9 is given by the spring force of the leaf spring 11.

FIG. 2 is a perspective view showing the structure of a drive gear in the device according to the first embodiment of the present invention.
Holes provided for press-fitting into the motor shaft of
2 shows a plurality of recesses for an encoder which are radially formed with respect to 0 and are formed at equal intervals. The drive gear 4 is processed by resin molding, and the concave portion 21 is formed during the resin molding.
The magnetic powder is put in the recess 21. By applying pressure to the magnetic powder placed in the recess 21, a magnetic body having the same shape as the recess 21 is formed in the recess 21. This will be referred to as a very small magnetic field area. By applying a strong magnetic field in the axial direction of the drive gear 4 to the minute magnetic field area, the minute magnetic field area becomes magnetized with magnetism. The direction of the magnetic field generated by the minute magnetic field area is the axial direction of the drive gear 4.

FIG. 3 is a partial cross-sectional side view of the drive gear in the vicinity of the minute magnetic field area, and reference numeral 22 denotes a magnet formed in the minute magnetic field area.

The magnet 22 in the minute magnetic field section is magnetized in the axial direction (Y direction) of the drive gear 21 to generate a magnetic field. The arrow in the figure indicates the direction of the generated magnetic field. Since the directions of the magnetizing magnetic fields of the magnets 22 are the same, a magnetic field in the opposite direction is generated between the magnets 22 in the minute magnetic field area. For this,
As shown in FIG. 4, a magnetic field is generated between the magnets 22 in each minute magnetic field section.

Reference numeral 23 denotes a magnetoresistive element (hereinafter, referred to as an MR element) provided in the magnetic field detection sensor 5 for detecting a magnetic field generated between the magnets 22 in each minute magnetic field section. The MR element 23 detects a magnetic field in the X direction shown in FIG. Therefore, the output of the MR element 23 becomes the absolute value of the detected magnetic field, and becomes an electric signal having a waveform as shown in FIG. The wavelength of the output from the MR element 23 is １ ／ of the pitch P of the magnets 22 in the minute magnetic section.

It should be noted that a Hall element can be applied as the magnetic detection element of the magnetic field detection sensor 5. The Hall element detects a magnetic field in the Y direction. Therefore, the output of the Hall element is as shown in FIG. That is, the wavelength of the output waveform of the Hall element is の of the pitch P of the magnets 22 in the minute magnetic area.

When the drive gear 4 rotates in conjunction with the rotation of the motor 1, the magnetic field detection sensor 5 detects
An electric signal having a waveform shown in (a) and (b) is output. The electric signal is converted into, for example, a pulse wave, and the number of pulses is counted. Location information can be obtained.

FIG. 5 is a perspective view showing the configuration of a drive gear in the device according to the second embodiment of the present invention. Reference numeral 30 denotes a drive gear, and 31 is formed on the center shaft of the drive gear 30, and is fitted to the motor shaft. The holes 32 are made of stainless steel, and are circular slit plates formed with a plurality of slits 33 formed at equal intervals in a radial direction from the center with respect to the outer peripheral portion.

The slit plate 32 has a slit 3 in advance.
After forming 3, the main body of the drive gear 30 is put into a molding die when resin molding. By so-called insert molding, the slit plate 32 is formed integrally with the drive gear 30 while being disposed on the side of the main body. Then, magnetic powder is put into each slit 33 and magnetized to form a minute magnetic area. Here, at the time of insert molding,
If the resin does not flow into the slit 33, the slit plate 32
Can be used as it is, but when resin may flow into the slit 33, molding may be performed with a disk closing the bottom of the slit 33 interposed.

The slit 33 is formed by etching or pressing. In particular, in the case of etching, the shape error can be reduced, and furthermore, it can be formed as a concave portion, and the slit plate 32 can be used alone for insert molding.

FIG. 6 is a perspective view showing the structure of the drive gear in the device according to the third embodiment of the present invention. Reference numeral 40 denotes a drive gear made by resin molding. Holes provided for fitting with the motor shaft, 42
Denotes gear teeth formed on the outer periphery of the drive gear 40.

After the drive gear 40 is resin-molded and the teeth 42 are formed, magnetic powder is put into a part of the concave portion formed between the teeth 42 and pressure is applied. 43 are formed. By applying a magnetic field to the magnetic solid 43 and magnetizing it, the magnetic solid 43 becomes a minute magnetic area, and can be detected by the magnetic field detection sensor 5 as an encoder. When the magnetic solid 43 is magnetized in the longitudinal direction of the drive gear 40 (in the direction of the center axis of the hole 41), the minute magnet provided on the drive gear 40 already described with reference to FIGS. It is possible to detect the magnetic flux in the minute magnetic area by the magnetic field detection sensor 5 in the same direction as the magnetic area.

When the magnetic solid 43 is magnetized, it may be magnetized in the radial direction of the drive gear 40. In this case, by providing the magnetic field detection sensor 5 at a position facing the magnetic solid 43 in a direction facing the teeth 42, it is possible to detect the magnetic flux in the minute magnetic section.

[0036]

According to the present invention constructed as described above, the drive transmission means provided on the motor shaft for transmitting the rotation of the motor to another drive system is magnetized in a certain direction. A minute magnetic section is provided integrally, and the rotation of the drive gear can be detected by detecting a magnetic flux generated from the minute magnetic section that rotates with the rotation of the drive transmission means. As a result, the drive transmission means moves relative to the rotating shaft. Even if it is displaced, the minute magnetic area is similarly displaced with respect to the rotation axis, so that erroneous detection is eliminated. Also, since the number of parts is reduced, it is possible to reduce parts costs and assembling costs.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a main part of an apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a drive gear in the device according to the first embodiment of the present invention.

FIG. 3 is a partial cross-sectional side view of the vicinity of a minute magnetic field area of the drive gear.

FIG. 4 is a waveform chart showing an output waveform of an MR element.

FIG. 5 is a perspective view showing a configuration of a drive gear in the device according to the second embodiment of the present invention.

FIG. 6 is a perspective view showing a configuration of a drive gear in a device according to a third embodiment of the present invention.

FIG. 7 is an explanatory view showing a main part of a conventional optical pickup driving mechanism.

[Explanation of symbols]

 Reference Signs List 1 motor 2 bracket 3 base 4, 30, 40 drive gear 5 magnetic field detection sensor 6, 7 intermediate gear 8 intermediate transmission shaft 9 lead screw 10 pickup 11 leaf spring 12 rack 20, 31, 41 hole 21 concave portion 22 magnet 23 MR element 31 Hole 33 Slit 42 Tooth 43 Magnetic solid

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 21/08 G11B 21/08 C

Claims (7)

[Claims] 1. A rotation detecting device which is fixed to a rotation shaft provided in a rotation drive source and detects a rotation state of a drive transmission means for transmitting the rotation of the rotation shaft to another drive system, wherein: A magnetic powder is pressed into the formed plurality of recesses, and a magnetic field in a fixed direction is applied to the magnetic powder in each of the plurality of recesses to form a minute magnetic area formed by magnetizing the magnetic powder in a fixed direction. And a magnetic field detecting means for detecting a change in a magnetic field generated from the minute magnetic area, and detecting a rotation state of the drive transmitting means based on an output of the magnetic field detecting means. 2. A rotation detecting device which is fixed to a rotation shaft provided in a rotation drive source and detects a rotation state of a drive transmission means for transmitting rotation of the rotation shaft to another drive system, wherein the drive transmission means is At the time of molding, a sheet metal material having a concave portion is integrated by insert molding, a magnetic powder is pressed into the concave portion, and a magnetic field is applied to each of the magnetic powders of the plurality of concave portions to keep the magnetic powder constant. Magnetic field detecting means for detecting a change in a magnetic field generated from the minute magnetic area, and detecting a rotation state of the drive transmitting means based on an output of the magnetic field detecting means. A rotation detecting device. 3. The rotation detecting device according to claim 2, wherein the recess is formed by etching. 4. A rotation detecting device which is fixed to a rotation shaft provided in a rotation drive source and detects a rotation state of a drive transmission means for transmitting the rotation of the rotation shaft to another drive system, wherein the drive transmission means comprises: As a gear, magnetic powder is press-fitted into a groove between teeth in a region other than a region where the gear meshes with a drive transmission unit of another drive system, and the drive transmission unit is supplied to the magnetic powder of each of the plurality of grooves. A magnetic powder is pressed into the formed plurality of recesses, and a magnetic field in a fixed direction is applied to the magnetic powder in each of the plurality of recesses to form a minute magnetic area formed by magnetizing the magnetic powder in a fixed direction. And a magnetic field detecting means for detecting a change in a magnetic field generated from the minute magnetic area, and detecting a rotation state of the drive transmitting means based on an output of the magnetic field detecting means. 5. The rotation detecting device according to claim 1, wherein said magnetic field detecting means is constituted by a magnetoresistive effect element. 6. An optical pickup for recording, reproducing and erasing information by forming a light spot on an information recording medium, a rotary drive source for driving the optical pickup, and a tip of a rotary shaft of the rotary drive source. A drive transmission means provided in the optical pickup, a drive conversion means for converting the rotational motion into a linear motion of the optical pickup, and an intermediate transmission means for transmitting the rotation of the drive transmission means to the drive conversion means, the optical pickup A pickup drive mechanism for driving in a direction parallel to a recording surface of an information recording medium, wherein a rotation state of the rotation drive source is detected.
A pickup drive mechanism provided with the rotation detecting device according to 2, 3, 4, or 5, and acquiring position information of the optical pickup based on a detection result of the rotation detecting device. 7. A plurality of magnetized bodies are provided on a drive transmitting means fixed to a rotating shaft provided in a rotary drive source and for transmitting rotation of the rotating shaft to another drive system, and a magnetic field generated from the magnetized body is provided. A method for manufacturing a rotation detection device that detects by a magnetic field detection means and detects a rotation state based on an output of the magnetic field detection means, wherein pressure is applied to magnetic powder disposed at a predetermined position of the drive transmission means. And applying a magnetic field to the solidified magnetic powder to magnetize the solidified magnetic powder in a certain direction to form the plurality of magnetized bodies.