JPH0481810B2 - - Google Patents

Description

[Detailed description of the invention] Technical field The present invention relates to an optical information recording/reproducing device.

BACKGROUND ART Disks such as video disks and digital audio disks, which are information recording media, are
The information signal is recorded by irradiating the recording surface with a fine spot of light to form pits corresponding to the information signal as spiral tracks. Further, when reproducing an information signal recorded in this manner, a spot light is irradiated onto the track and the reflected or transmitted light is used to reproduce the original information signal.

Various devices for reproducing or recording information signals have already been developed. Specifically, the device includes a light emitting element such as a laser diode, an objective lens that focuses the irradiation light emitted by the light emitting element on the disk recording surface as a spot light, and a device that precisely directs the irradiation light to a predetermined position on the disk recording surface. It includes a servo drive mechanism that servo drives the objective lens in the direction of the optical axis of the objective lens and in a direction perpendicular thereto to achieve focusing. Of these, at least the objective lens and the servo drive mechanism are held by a predetermined holding member, and are moved together with the holding member along the disk recording surface as the disk rotates. Therefore, a support means for movably supporting the holding member along the disk recording surface and a moving force applying means for applying a moving force to the holding member are provided. An example of the moving force applying means is a linear motor. The linear motor includes a magnetic circuit as a secondary side consisting of a longitudinal magnet and a longitudinal yoke extending along the moving direction of the holding member and engaged with each other, and a primary winding attached to the holding member. It consists of a coil.

On the other hand, for the purpose of controlling the moving speed of the holding member, a speed detection means for detecting the same speed of the holding member is provided. One example of the speed detection means is a detection coil attached to the holding member such that the coil center axis is parallel to the moving direction of the holding member, and a detection coil provided extending in the moving direction of the holding member. Some devices consist of a longitudinal magnetic circuit that generates a magnetic flux that interlinks with a detection coil.

An optical information recording and reproducing device that uses a combination of the moving force imparting means and speed detecting means configured as described above has already been developed, but in this optical information recording and reproducing device, a linear motor is used to move the holding member. The present invention has two magnetic circuits: one is a magnetic circuit, and the other is a magnetic circuit as a component of the speed detecting means. Therefore, it has been difficult to downsize the recording/reproducing apparatus as a whole, and this has led to an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and its purpose is to provide an optical information recording/reproducing device that can be easily reduced in overall cost and size.

In the optical information recording and reproducing apparatus according to the present invention, a magnetic circuit of a linear motor that applies a moving force to a holding member holding an objective lens and its servo drive mechanism has a speed detection means for detecting the moving speed of the holding member. It is characterized in that it is also used as a magnetic circuit.

Embodiments Hereinafter, an optical information recording/reproducing apparatus as an embodiment of the present invention will be described with reference to the accompanying drawings.

Frame 1 shown in FIGS. 1 to 4 is
It is provided within a housing (not shown) of the optical information recording/reproducing device, and is attached to the housing via four leg members 2 and 3. Note that the frame 1 is made of aluminum or an alloy thereof.

A pair of cylindrical steel support rails 5 and 6 extending in the direction of arrow Y and the opposite direction and spaced apart in the direction of arrow Z and the opposite direction are fixed to this frame 1 at both ends thereof. .
A longitudinal pick-up body 7 serving as a holding member extending in the direction of arrow Z and the opposite direction thereof is positioned so as to be sandwiched between the support rails 5 and 6, and is movably supported by the support rails. has been done. This pick-up body 7 is also made of aluminum or its alloy. Two steel rollers 8 are attached to one side of the pick-up body 7 to roll on the support rail 5.
Further, a total of four other steel rollers 9, two on each side of the pick-up body 7, are attached at two distances from each other in the moving direction of the pick-up body, and are attached to the other support rail 6. are in contact. As is particularly clear from FIG. 4, the pick-up body 7 is supported at three points by both support rails 5 and 6 via the aforementioned rollers 8 and 9.

As shown in FIG. 4, a roller 8 provided on one side of the pick-up body 7 is attached to the free end of a swing lever 12 which is attached to the pick-up body via a pin 11 so as to be swingable in the direction of arrow R. is attached to. Note that the direction of arrow R is perpendicular to the direction of movement of the pick-up body (the direction of arrow R and the opposite direction). Further, a spring member 13 is provided as a pressing means for pressing the roller 8 against the support rail 5. By pressing the roller 8 on the one-point side of the three-point support described above against the support rail 5 in this way, the rollers 9 on the other two-point sides are also pressed against the other support rail 6 by the reaction force. Note that the optical information recording/reproducing device is installed so that the direction of arrow Z is the anti-gravity direction. That is, the roller 8 on the one-point side is always positioned in the anti-gravity direction with respect to the roller 9 on the two-point side. As a result, the spring member 13 for pressing the roller against the support rail 5 is no longer subject to the large weight of the pick-up body 7 or the like.

The pick-up body 7 is supported by the support rails 5, 6, the steel rollers 8, 9, the spring member 13, and the surrounding small members related thereto.
Supporting means is configured to support the recording medium movably along the recording surface of the disk 15, which is a recording medium.

As shown in FIGS. 2 and 4, the frame 1 includes longitudinal magnets 16 and longitudinal magnets that extend along the moving direction of the pick-up body 7 (direction of arrow Y and the opposite direction) and are fixed to each other. A pair of longitudinal magnetic circuits 2 consisting of yokes 17 and 18
0 is fixed. Further, as shown in FIG. 2, a pair of drive coils 21 are attached to the pickup body 7 so that the center axis of the coils is parallel to the direction of movement of the pickup body. The magnetic circuit 20 described above interlinks with the drive coil.

A linear motor is configured as a moving force applying means that generates magnetic flux and, together with the drive coil, applies a moving force to the moving optical system including the pickup body 7.

Note that the linear motor has a pick-up body 7.
A moving force is applied to a portion of the moving optical system that corresponds to a node of primary transverse vibration.

As shown in FIG. 2, a detection coil 22 is attached to the outer periphery of each drive coil 21 so that the coil center axis is concentric with the coil center axis of the drive coil.
is wound. The magnetic flux emitted from the magnetic circuit 20 of the linear motor described above also interlinks with this detection coil 22. These magnetic circuit 20 and detection coil 22 constitute a speed detecting means for detecting the moving speed of the pickup body 7 and controlling the moving speed. That is, the magnetic circuit 20 constituting the linear motor is also used as the magnetic circuit of the speed detecting means.

As is clear from FIG. 2, the aforementioned steel rollers 8 and 9 are arranged on the yoke 17 side of the magnetic circuit 20.

As shown in Figures 1, 3 and 4,
A flat rectangular parallelepiped holding member 25 is attached to the rear end of the frame 1 . As shown in FIG. 5, this holding member 25 includes a laser diode 27 as a light emitting element, a collimator lens 28 that converts the irradiation light emitted from the laser diode into parallel light, a condensing lens 29, and a disc 15. The light receiving element 30 receives the reflected light from the recording surface to obtain an information signal, and the collimator lens 28 shapes the irradiation pattern of the parallel light, guides it to an objective lens (described later), and directs it from the disk recording surface. A compound prism 31 that guides the reflected light to a light receiving element 30 is attached, and an astigmatism element 32 that imparts astigmatism to the reflected light for the purpose of detecting a focal error of the light beam emitted toward the disk recording surface is attached. It is being Further, as shown in FIG. 5, on the side of the composite prism 31, there is a monitor light receiving element 34 for detecting a part of the parallel light that is reflected within the composite prism and irradiated to the outside. is located.

FIG. 6 shows the - arrow view with respect to FIG. 5, and as is clear from both figures, the laser diode 27 is fitted into a counterbore formed in a rectangular plate-shaped holder 35. , is attached to the holding member 25 via the holder. As shown in FIG. 6, a substantially triangular holding plate 36 is provided to prevent the laser diode 27 from coming off from the holder 35, and is fixed to the holder 35 with screws 37.

The rectangular plate-shaped holder 35 described above is movable with respect to the holding member 25 together with the supported laser diode 27 in a plane perpendicular to the optical axis of the laser diode, in this case, in the direction of arrow Y and in the opposite direction. It's summery. As a result, the relative positions of the laser diode 27 and the collimator lens 28 within the plane are adjusted, and the parallel light emitted toward the pick-up body 7 through the collimator lens 28 is made to match the moving direction of the pick-up body. be.

Note that the laser diode 27, the collimator lens 28, the composite prism 31, and the holding member 25 that holds them are collectively referred to as a light source mount. Further, the light source mount is movable in parallel in the direction of arrow Z perpendicular to the optical axis of the parallel light emitted toward the pick-up body 7 through the collimator lens 28 and the compound prism 31, and in the opposite direction. Further, the objective lens and its servo drive mechanism, which will be described later, are movable in parallel on the pick-up body 7 in the direction of arrow Y and in the opposite direction. As a result, the relative position of the light source mount and the objective lens (described later) is adjusted in the Y-Z plane, and the central axis of the intensity distribution of the parallel light emitted toward the pick-up body 7 is aligned with the light of the objective lens (described later). It can be aligned with the axis.

FIG. 7 shows the - arrow direction with respect to FIG. 5, and as is clear from both figures, the light receiving element 3
0 is also attached to the holding member 25 via a rectangular plate-shaped holder 39.
is attached to. This holder 39 is
It has a notch 40 that has a clearance in the Y direction, the Y direction, and each opposite direction and is engaged with a screw 41, and is fixed to the holding member 25 by the screw 41, and the position is within the range of the clearance. Adjustable.

Figures 8 and 9 are respectively related to Figure 5.
As shown in the figures, the parts of the holding member 25 that hold the collimator lens 28, the condensing lens 29, and the astigmatism element 32 are oriented toward the optical path. The grooves 43, 44 and 45 are V-shaped in cross section at right angles.

As shown in FIG. 5, the composite prism 31 is formed by joining two prisms, a first prism 48 and a second prism 49. The first prism 48 is
a circular correction surface 50 that is inclined at a predetermined angle with respect to the parallel light obtained through the collimator lens 28 and performs circular correction of the parallel light (makes the elliptical irradiation pattern of the parallel light circular); a total reflection surface 51 that totally reflects parallel light transmitted through the surface;
It has a polarized light reflecting surface 52 for transmitting the parallel light reflected by the total reflection surface and for guiding the reflected light from the disk recording surface to the light receiving element 30. Further, the second prism 49 is attached to this polarized light reflecting surface 52, and works in cooperation with the polarized light reflecting surface to guide the reflected light from the disk recording surface to the light receiving element 30. The polarization reflecting surface 52 extends widely to serve as a reference surface, and by using the reference surface as a reference, the second prism 49 and the like can be easily positioned. As shown in FIG. 5, the angle between the parallel light emitted through the collimator lens 28 and this reference plane is 45°. By this,
The input optical axis 54 and the output optical axis 55 with respect to the composite prism 31 are parallel to each other, making it easy to arrange the laser diode 27 and the light receiving element 30.

As shown in FIG. 3, the pick-up body 7 includes a total reflection prism 5 as a guide means for bending the optical path of the parallel light emitted through the collimator lens 28 and the compound prism 31 at right angles.
7 is provided. In addition, as shown in FIGS. 1 and 2, the pick-up body 7 includes:
It includes an objective lens 58 for converging the parallel light that has passed through the total reflection prism 57 on the recording surface of the disk 15 as a minute spot light, a holder 59 and a support member 60 (shown in the first figure), and the objective lens is arranged along its optical axis. An objective lens support mechanism that supports the objective lens movably in two directions: the direction (direction of arrow F) and the direction perpendicular to this (direction of arrow T), a magnetic circuit consisting of a magnet 62 and a yoke 63, and a magnetic flux from the magnetic circuit are chained together. A driving source is provided which is composed of a coil (not shown) wound around the holder 59 so as to intersect with each other, and which applies a force to move the objective lens 58 in the two directions mentioned above. Note that this drive source and the objective lens support mechanism described above are collectively referred to as a servo drive mechanism. That is, the servo drive mechanism drives the objective lens 58 using electromagnetic force.

As shown in FIG. 4, a flexible printed circuit board 65 is provided for supplying a drive current to the servo drive mechanism mounted on the pickup body 7. The printed circuit board is bent into a U-shape in its thickness direction, and is disposed within the movement locus of the pick-up body 7 so that its thickness direction is parallel to the recording surface of the disk 15.

As shown in FIGS. 1, 3, and 4, a turntable 66 is provided in front of the pickup body 7 and rotates while supporting the disk 15. As shown in FIGS.

Effects of the Invention As detailed above, in the optical information recording and reproducing apparatus according to the present invention, the magnetic circuit of the linear motor that applies a moving force to the holding member (pickup body 7) holding the objective lens 58 and its servo drive mechanism. 20 is speed detection means (including detection coil 22) for detecting the moving speed of the holding member.
It is also used as a magnetic circuit.

Therefore, it is becoming easier to achieve overall cost reduction and miniaturization.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the internal structure of a main part of an optical information recording/reproducing apparatus according to the present invention, FIGS. 2 and 3 are a cross-sectional view and a cross-sectional view, respectively, of FIG. Regarding the figure - arrow view, 5th
The figures are partially detailed views of the internal structure, Figures 6 to 9.
The figures are a cross-sectional view, a cross-sectional view, a cross-sectional view, and a cross-sectional view of FIG. 5, respectively. Explanation of symbols of main parts, 5, 6... Support rail, 7... Pick up body, 8, 9... Steel roller, 13... Spring member, 15... Disk,
16... Longitudinal magnet, 17, 18... Longitudinal yoke, 20... Longitudinal magnetic circuit, 21... Drive coil, 22... Detection coil, 25... Holding member, 2
7... Laser diode, 28... Collimator lens, 29... Condensing lens, 30... Light receiving element,
31... Composite prism, 32... Astigmatism element,
34... Monitor light receiving element, 43, 44, 45...
... V-shaped groove, 48 ... First prism, 49 ... Second prism, 50 ... Circular correction surface, 51 ... Total reflection surface, 52 ... Polarization reflection surface, 58 ... Objective lens, 65 ... Flexible printed circuit board, 66...turntable.

Claims (1)

[Claims] 1 A plurality of optical elements including a light emitting element and an objective lens that focuses irradiation light emitted from the light emitting element onto a recording surface of a recording medium, a servo drive mechanism that servo drives the objective lens, and at least the objective lens and the servo drive. A holding member holding a mechanism, a supporting means supporting the holding member movably along the recording surface, a moving force applying means applying a moving force to the holding member, and detecting a moving speed of the holding member. and speed detection means for
The moving force applying means is provided extending in the moving direction and interlinks with the driving coil attached to the holding member such that the coil center axis is parallel to the moving direction of the holding member. The speed detecting means includes a linear motor comprising a longitudinal magnetic circuit that generates magnetic flux, and the speed detecting means includes a detecting coil attached to the holding member concentrically with the drive coil so that the central axis of the coil is parallel to the moving direction. An optical information recording/reproducing device characterized in that the longitudinal magnetic circuit also serves as a magnetic circuit that generates a magnetic flux that interlinks with the detection coil.