JPS6028038A - Optical information reader - Google Patents

Abstract

PURPOSE:To obtain easily stable read information by having different structures between tracking and focusing magnetic circuit systems and positioning a tracking coil at the neutral point of a magnetic flux of a magnet. CONSTITUTION:An inside yoke 33, a ring magnet 34 and an outside yoke 35 constitute a magnetic circuit system for focus control which shifts a lens holding arm 37 in the thrust direction. While an outside yoke 25, a magnet 26 and an inside yoke 36 constitute a magnetic circuit system for tracking control which revolves the arm 37 around a support shaft 29. Furthermore, a screw is unfastened to move a control plate 27 and a holding stage 19. Thus a coil 45 and the yoke 36 can be positioned at the center of the magnetic flux of a magnet 26. Therefore, the stable read information is easily obtained with no high accuracy of parts.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an optical information reading device that optically reads information from an information track recorded on an information recording surface of a disk or the like.

BACKGROUND TECHNOLOGY In general, when such an information reading device is driven and scanned relative to a disk, a tracking and focus error correction signal is given to the built-in optical beam steering means to constantly direct the optical beam onto the information track. It is configured to converge to a normal position.

By the way, the means for controlling the above-mentioned light beam are as follows: (1) Moving the entire case containing the light emitting element diffraction grating, beam splitter, wavelength plate, prism, objective lens, etc. by applying a tracking error correction signal to a tracking operation coil. This method performs control in the radial direction by applying a focus error correction signal to a focus operation coil to move the objective lens up and down.

Alternatively, it was developed as an improvement method for
As disclosed in Japanese Patent No. 210457, coils for focusing and tracking operations are provided on the outer periphery of the holding tube of the objective lens, and yokes and magnets are provided on the inside and outside of the holding tube, respectively. A system that performs tracking and focusing by applying focus and tracking error correction signals to the coil and moving the holding cylinder in the thrust direction and radial direction.

etc. have been developed.

The method described in (■) above has a structure in which a coil magnet or the like is combined with the objective lens to vibrate either the focus control mechanism or the objective lens itself, so it is extremely small and difficult to assemble, maintain, and inspect. However, since the coils for focusing and tracking operations are wound around the outer circumference of the lens holding cylinder in (2), the focus system mechanism can be constructed relatively large, and the holding cylinder can be rotated and moved up and down. Since it has a structure in which thrust and radial movement of the objective lens can be obtained by movement, it has the advantage that it can be made smaller overall compared to the method (2).

However, in this method (■), each yoke and magnet are shared for tracking and focusing, and they are fixedly installed on one plywood, so it is difficult to assemble to improve the precision of parts and eliminate variations during assembly. Without it, the operation becomes unstable and the information cannot be read reliably.

OBJECTS OF THE INVENTION As mentioned above, the present invention was invented in view of the drawbacks of the conventional devices, and the magnetic circuit systems for tracking and focusing have completely different structures, and at least the tracking coil is It is an object of the present invention to provide a device that can be aligned to the neutral point of the magnetic flux of a magnet, and can obtain an optimal assembled state and stably read information even if the accuracy of one component is somewhat poor.

Configuration of the Present Invention> Hereinafter, an embodiment of an optical information reading device according to the present invention will be described in detail with reference to the accompanying drawings.

Of the accompanying drawings, FIGS. 1 to 3 show an exploded perspective view, an assembled perspective view, and a plan view of one embodiment of the optical information reading device according to the present invention, and FIG. A front sectional view taken along line 1-1' in the figure is shown.

In these figures, reference numeral 1 denotes a device body having an optical system support hole 2 with one side open, and screws on both sides of the rear edge, which has a bearing hole 3 and a light passage hole 4 in the center. hole 6
A convex step 5 having a similar step 5 is provided, and a protrusion 7 having a similar step 5 is provided at the center of the front edge to protrude forward.

Reference numeral 9 denotes a light beam generator, which is generally known and includes a light emitting element (laser diode) 1 housed in a holding tube 101.
15 Diffraction grating 12. It consists of a beam splitter 13, a collimator lens 141X, a wavelength plate 15, and a prism 16 as a light beam path changing means fixed on the inclined surface lO'' of the support piece 10' at the tip of the holding cylinder 10,
The prism 16 is accommodated in the optical system support hole 2ζ so as to be located directly below the light passage hole 4.

Reference numeral 17 denotes a light-receiving element consisting of a four-split photodiode or the like, which is fitted into a support hole 8 opened in the front face of the apparatus main body 1, and whose light-receiving surface is connected to the optical system so as to receive the reflected light beam from the beam splitter 13. It faces into the system support hole 2.

18 is an adjustment screw screwed into the bottom surface of the device main body 1 and whose tip engages with the lower surface of the support piece 10' of the holding cylinder;
By rotating the screw 18 with a screwdriver or the like, the support piece lO' is moved up and down as shown in FIG. The surface 16b can be adjusted to be parallel to the optical axis of the light beam O that reaches the reflective surface i6a of the prism 16 from the light emitting element 11.

Here, the reason why it is possible to adjust with the adjustment screw 18 is that the angle LABC of the prism 16 is
(45°) variation and the fixed surface 16 of the prism 16
The objective is to correct the deviation in the parallel relationship between the optical axis of the light beam 0 and the optical axis of the light beam 0.

That is, the prism 16 is provided to change the direction of the light beam from the light emitting element 11 so as to direct the light beam toward the center of an objective lens, which will be described later, and to converge the light beam perpendicularly to a regular position on the information track from the objective lens. However, the above angle L
If ABC is not 45 degrees or if there is a deviation in the parallel relationship between the fixed surface 16b and the optical axis of the light beam 0, there is a problem that the optical axis of the light beam cannot be aligned with the center of the objective lens.

Conventionally, this problem has been solved by increasing the processing precision of the prism and its support piece, but this requires advanced processing technology and is expensive.

In consideration of this problem, the present invention provides the supporting piece 10 as described above.
' Close the top surface of the sloped surface IO "This sloped surface 10" East j ()! Fix the Jism 16, and then tighten the adjustment screw 18.
By operating the prism 6, the fixed surface 16b of the prism 6 is made parallel to the optical axis of the light beam, and the optical axis of the light beam is aligned with the center of the objective lens.

Reference numeral 19 denotes a base plate l made of a non-magnetic material placed on the device main body l between each of the stepped portions 5, and a shaft hole 20 communicating with the bearing hole 3 and the light passage hole 4, respectively, in the center of the plate surface. Light hole 2
1 and a bone protrusion 23 having screw holes 22 at both ends of the front edge, and supporting pieces 24 having a "<" shape on the upper surface on both side edges.
has been established.

An outer yoke 25 for tracking operation, which has approximately the same shape and size as the support pieces, is fixed to the surfaces of these support pieces 24 and 24 that face each other, and these outer yokes 25.
Magnets 26 for two-target tracking operations are fixed to mutually opposing surfaces of the magnets 25, respectively.

27 has a fulcrum shaft 29 perpendicularly penetrating and fixed in the center of the plate surface, and has an extension part 28 at the front part.
The adjusting plate is made of non-magnetic material or magnetic material, and has arc-shaped adjustment holes 30 on both sides of the extending portion 28 and the rear edge.
is placed on the stepped portion 5 of the apparatus main body l from the -L side of the base plate 19, and is configured to sandwich the base plate 19 by screwing the screws 31 into the screw holes 6 through each adjustment hole 30. It is fixed on the main body l of the device.

This first adjusting plate 27
By being fixed on top of the base plate 1, the lower end of the fulcrum shaft 29
9 is inserted into the bearing hole 3 of the device body 1 through the shaft hole 20, and a light passage hole 32 provided at the center of the plate surface is inserted into each of the light passage holes 4.
．． It is connected to 21.

Reference numeral 33.33 denotes an inner yoke for focus operation fixed on the first adjustment plate 27 so as to sandwich the fulcrum shaft 29 back and forth. The above-mentioned light passage hole 32 is provided in the.

Reference numeral 34 denotes a ring magnet for focus operation fixed to the upper surface of the first adjustment plate 27 so as to surround the inner yoke 33, and a Q-ring shaped outer yoke 35 for focus operation is fixed to the upper surface of the ring magnet. .

Reference numeral 36 denotes an inner yoke for tracking operation made of an arcuate plate material, which is connected to the outer yoke 2 for tracking operation.
5. It is fixed to the outer periphery of the ring magnet 34 and the outer yoke 35 so as to correspond to the magnet 26.

In short, an inner yoke 33 for focusing operation, a ring magnet 34, an outer yoke 35, and an inner yoke 36 for tracking operation are fixed to the first adjusting plate 27.

Reference numeral 37 designates a lens holding arm with arc-shaped supporting pieces 38 facing downward at both ends, and a shaft insertion hole in the center of the plate surface through which the fulcrum shaft 29 is inserted so as to be rotatable and vertically movable (moveable in the thrust direction). It has 39. A holding port 41 for holding an objective and a lens 40 is provided on one outside of the contact 39 so as to sandwich the shaft insertion port 39, and a weight 42 is fixed to the other outside.

Further, this lens holding arm 37 is integrally provided with a cylindrical bobbin 43 on its lower surface, and is inserted into and supported by the fulcrum shaft 29 through the shaft insertion port 39, so that the bobbin 43 can be inserted into the inner side. A distance between the yoke 33 and the ring magnet 34 (outer yoke 35) is suspended.

This bobbin 43 has a focus operation coil 44 wound around its outer periphery, and moves the lens holding arm in the thrust direction together with the inner yoke 33, ring magnet 34 and outer yoke 35, that is, the first coil 44 for focus adjustment. It forms the motor.

Further, the arm 37 has a tracking operation coil 45 attached to the outer surface of the support piece 38, and the outer yoke 25,
The magnet 26 and the inner yoke 36 together form a second motor for moving the lens holding arm in the radial direction, that is, for tracking adjustment.

Reference numeral 46 designates a lens radial direction adjustment plate (hereinafter referred to as a second adjustment plate), which has adjustment holes 47 at both ends and a folded piece 48 having a pivot shaft 49 on the upper surface at the center of the front edge. , is placed on the bone protrusion 23 on the base plate 19, and is fixed on the bone protrusion 23 by screwing the screw 50 into the screw hole 22 through the adjustment hole 47, and by loosening the screw 50, the fulcrum is fixed. It can slide in a direction perpendicular to the axis 29.

Reference numeral 51 denotes a socket 52 for the pivot shaft 491 of the second adjusting plate 46.
It is a neutral holder made of a rubber plate which is pivotally supported by a stopper 53 and prevented from coming off by a stopper 53, and is fixed to the front edge of the lens holding arm 37 with its rear edge.

By fixing the rear edge of the neutral holder 51 to the front edge of the lens holding arm 37 in this way, the lens holding arm 37 is placed in a state floating above the pedestal 19 in the axial direction of the fulcrum shaft 29, that is, in the neutral state. As a result, the coils 44.45 for focus operation and tracking operation are magnetically coupled to the corresponding inner and outer yokes and magnets, respectively, and the arm 37 is activated by a signal applied to each coil 44.45. It is in a state where it can rotate and move in the thrust direction.

Effects of the Present Invention> Although the present invention is constructed as shown on paper, its effects will be explained next.

It should be noted that the optical information reading device of the present invention configured as described above is entirely located within the player body as shown by the arrow A in FIG.
, B direction by a drive motor, and the focus operation coil 44 and tracking operation coil 45 are connected to a focus servo circuit and a tracking servo circuit (not shown) to obtain servo signals, respectively. .

Now, when the player is in the playback state, the light beam generator 9
The light beam 0 output from the light emitting element 11 of the diffraction grating 1
2. Beam splitter 13, collimator lens 14.
It passes through the q wavelength plate 15 and hits the reflective surface 16a of the prism 16, where the optical path is changed and the light passes through the optical holes 4, 21, 32, . The objective lens 40 passes through the inner yokes 33 and 33,
The lens 40 focuses the light onto the information track of the disk D.

Then, the reflected light beam containing the information component reflected from the disk D is conversely transmitted through the objective lens 40 through each light passage hole 4.
21. It reaches the reflective surface 16a of the prism 16 through 32,
After the optical path has been changed here, the y-wave plate 15. The light passes through the collimator lens 14, reaches the beam splitter 13, is reflected, and is irradiated onto the light-receiving surface of the light-receiving element 17.

As described above, the light beam output from the light emitting element 11 is reflected on the information track of the disk D and is received by the light receiving element 17 in a state containing information.
The focus servo circuit and the tracking servo circuit operate according to the light reception state at the coils 44 and 45 to provide focus and tracking error correction signals for correcting focus and tracking errors to the coils 44 and 45.

When the focus error correction signal is applied to the focus operation coil 44, the first motor consisting of the coil 44, inner and outer yokes 33, 35, and ring magnet 34 is activated to move the lens holding arm 37 to the neutral holding device. The objective lens 40 is moved up and down in the thrust direction along the fulcrum shaft 29 against the elasticity of the lens 51 to obtain the optimum focus.

When the tracking error correction signal is applied to the tracking operation coil 45, a second motor consisting of the coil 45, the inner and outer yokes 36, 25, and the magnet 26 is activated to move the lens holding arm 37 to the neutral position. The objective lens 40 is rotated about the fulcrum shaft 29 against the elasticity of the holder 51, that is, moved in the radial direction, so that the convergence point of the light beam by the objective lens 40 is located on the information track.

The optical information reading device according to the present invention operates while the player is being driven as described above.
When the incident angle of the upwardly focused light beam is not perpendicular to the tangential direction of the information track, it is preferable to adjust it by rotating the adjustment screw 18 to the left or right. That is,
Rotate the adjustment screw 18 to the left or right to move the prism 16 up and down via the support piece 10', and align the fixed surface 16b of the prism 16 with the optical axis of the light beam from the light emitting element 11 to the reflective surface 16a. On the other hand, when the optical axis of the light beam is adjusted to be parallel to the object lens, the optical axis of the light beam coincides with the center of the objective lens, and the light beam is irradiated perpendicularly to the tangential direction of the information track.

In addition, when adjusting the positional relationship between the inner and outer yokes 36.25 and the magnet 26 that correspond to the tracking operation coil 45 on the lens holding arm 37, use the screw 31.
It is best to loosen the adjustment plate 27 and the pedestal 19 to position the coil 45 and the inner yoke 36 at the center of the magnetic flux of the magnet 26.

When aligning the objective lens 40 in the radial direction, loosen the screw 50 and move the second adjusting plate 46 on the pedestal 19, and move the lens holding arm 37 in the radial direction via the neutral holder 51. It is best to rotate it in the direction shown below.

This positioning of the objective lens 40 and the tracking operation coil 45. By aligning the magnet 26 and the like, the optical axis of the light beam and the center of the objective lens can be aligned, and the tracking operation coil 45 of the lens holding arm 37 can be aligned. The center of the magnetic flux of the magnet 26 for tracking operation is aligned with the inner yoke 36, etc., and as a result, the objective lens can be moved stably in the radial direction, and the light beam can be properly focused on the information track of the disk. You can get points.

Effects of the Present Invention Since the present invention is constructed as shown on paper, the plywood can be rotated around the fulcrum axis by loosening the fixing means (screw 31 and the first adjusting plate in the embodiment). , the coil for tracking operation provided on the lens holding arm can be positioned at the neutral point of the magnet for tracking operation, so even if the precision of the parts is somewhat poor, it can be compensated for and assembled in the optimal state during assembly. This is an excellent invention that can guarantee stable operation.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the optical information reading device according to the present invention, FIGS. 2 and 3 are a perspective view and a plan view of the same device in an assembled state, and FIG. 4 is the same as FIG. 3. A sectional view taken along the line j-1', and FIG. 5 is an enlarged sectional view of the main part of FIG. 4. 19: Base plate, 25 and 26: Outer yoke and magnet for tracking operation, 29: Fulcrum shaft, 37: Lens holding arm %4o: Objective lens, 45 Coil for tracking operation. Agent: Patent attorney Aihiko Fuku (and 2 others) 1st illustration

Claims (1)

[Claims] 1. A lens holding arm that is rotatable around a fulcrum axis and can slide in the thrust direction of the fulcrum axis and has a tracking operation coil at both ends, and a lens holding arm that is held at a distance from the fulcrum axis by the lens holding arm. objective lens,
A plywood plate rotatably inserted into the fulcrum shaft below the lens holding arm, and an outer side for tracking operation provided on the base plate so as to correspond to both of the tracking operation coils at a certain distance. An optical system comprising a cork, a tracking magnet fixed to a surface of the outer cork that corresponds to the tracking coil, and means for fixing the base plate at an arbitrary position around the fulcrum axis. Information reading device.