JPS6028031A - Optical information reader - Google Patents

Abstract

PURPOSE:To improve the accuracy in reading information by shifting an optical path changing means like a prism with a control means to make the optical axis of a light beam coincide with the center of an objective lens. CONSTITUTION:When the incident angle of the light beam focused on a disk from an objective lens 40 is not vertical toward the tangent line of an information track, a control screw 18 is turned right or left for adjustment of said incident angle. In other words, a prism 16 is moved up and down via a support bar 10'' by turning the screw 18. Thus the welded surface 16b of the prism 16 is controlled so as to be set parallel to the optical axis of the light beam reaching a reflecting surface 16a from a light emitting element 11. As a result, the optical axis of the light beam is coincident with the center of the lens 40. Thus the light beam is irradiated to a direction vertical toward the tangent line of the information track. In such a way, the accuray is improved in reading information.

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 Art> Generally, in such a device, a light beam generated from a light emitting element is guided to a prism, which is an optical path changing means, via a beam splitter, etc., and the optical path is changed here and is directed onto an information recording surface by an objective lens. The reflected light beam that has been converged and reflected from the recording surface is guided again to the beam splitter through the objective lens and prism, and is then received by a light receiving element to read information.

By the way, in conventional such devices, the prism is fixedly provided in the optical path, so the light beam guided from the prism to the objective lens may vary due to variations in the processing accuracy of the prism, dimensional errors in the prism support, etc. In some cases, it was not possible to align the axis with the center of the objective lens.

<Object of the present invention> The present invention was invented in view of the above-mentioned drawbacks of the conventional apparatus, and the optical axis of the light beam is aligned with the objective lens by moving the optical path changing means such as a prism with the adjusting means. Our goal is to provide an optical information reading device that can align the center and read information more accurately.

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 8 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 II' in the figure is shown.

In these figures, 1 is the main body of the device which has an optical system support hole 2 with one side open, and screws are installed on both sides of the rear edge of the upper surface, 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) housed in a holding cylinder IO.
2 diffraction gratings +2. Beam splitter It, collimator lens + 4, l/4 wavelength plate 15 and the above-mentioned holding tube 10
A light beam optical path changing means fixed on the inclined surface 10' of the support piece 10' at the tip of the support piece 10' is housed in the optical system support hole 2 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 device main body 1, and whose light-receiving surface is arranged to receive the reflected light beam from the beam splitter 18. 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 10' is moved up and down as shown in FIG. The surface 16b can be adjusted so as to be parallel to the optical axis of the light beam 0 extending from the light emitting element 11 to the reflective surface 16a of the prism 16.

Here, the reason why it is possible to adjust with the adjustment screw I8 is that the angle LABc of the prism 16 is
(45A5 variations and the fixed surface of the prism 16 +6
In other words, the prism 16 changes the direction of the light beam from the light emitting element 11 and directs it toward the center of the objective lens, which will be described later. The lens is provided to converge the light beam perpendicularly to a regular position on the information track, but the above angle L
If ABC is not 45 degrees or there is a deviation in the parallel relationship between the fixed surface 16b and the optical axis of the light beam 00, 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.
The prism 16 is fixed on the inclined surface 10'' with the top surface of the prism 10 as the inclined surface 10", and then, by operating the adjustment screw +8, the fixed surface +6b of the prism 16 is set parallel to the optical axis. The optical axis of the light beam is aligned with the center of the objective lens.

Reference numeral 19 denotes a plywood board made of a non-magnetic material placed on the device main body l between 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, and an optical passage. Hole 21
and a receiving projection 2 having screw holes 22 at both ends of the front edge.
3, and support pieces 24 with a "<" shape on the upper surface are erected on both side edges.

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 is a magnetic circuit system adjustment plate (hereinafter referred to as the first
It is made of a non-magnetic material or a magnetic material and has arc-shaped adjustment holes 80 on both sides of the extension part 28 and the rear edge, respectively, and has arc-shaped adjustment holes 80 on both sides of the extension part 28 and the rear edge part, and the plate is made of a non-magnetic material or a magnetic material. It is placed on the stepped portion 5 of the body 1, and is fixed on the device main body 1 so as to sandwich the base plate 19 by screwing the screws 81 into the screw holes 6 through each adjustment hole 30.

The first adjustment plate 27 is thus arranged in the device main body I.
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 88.83 denotes an inner yoke for focus operation fixed on the adjustment plate 27 so as to sandwich the fulcrum shaft 29 back and forth, and the first adjustment plate 27 between these two yokes 38.88
The light passage hole 32 is provided above.

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 ring-shaped outer yoke 35 for focus operation is fixed to the upper surface of the ring magnet. .

36 is an inner yoke for tracking operation made of arc-shaped QJ material, and the outer yoke 2 for tracking operation is
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, the inner yoke 33° ring magnet 34 for focusing operation. An outer yoke 85 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 arcuate supporting pieces 38 facing downward at both ends, and a shaft insertion member inserted into the fulcrum shaft 29 at the center of the plate surface so as to be rotatable and vertically movable (moveable in the thrust direction). It has an opening 39. A holding opening 41 for holding an objective lens 40 is provided on one outside of the opening 39 so as to sandwich the shaft insertion opening 39, and a weight 4 is provided on the other outside.
2 is fixed.

Further, this lens holding arm 87 has a cylindrical bobbin 48 integrally provided on its lower surface, and is inserted and supported by the fulcrum shaft 29 through the shaft insertion port 39, so that the bobbin 48 can be inserted into the inner side. It is suspended between the yoke 33 and the ring magnet 84 (outer yoke 85).

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 83, the ring magnet 34, and the outer yoke 35, that is, the first focus adjustment stop. It forms the motor structure.

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,
Together with the magnet 26 and the inner yoke 36, it forms 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 receiving protrusion 23 on the base plate 19, and is fixed on the receiving protrusion 23 by passing the screw 50 through the adjustment hole 47 and screwing it into the rhinoceros i22.
By loosening the fulcrum shaft 29, it can be slid in a direction perpendicular to the fulcrum shaft 29.

Reference numeral 51 denotes a neutral holder made of a rubber material which is pivotally supported on the pivot shaft 49 of the second adjusting plate 46 through an insertion port 52 and secured with a stopper 5BK. It is fixed to the front edge of the lens holding arm 87.

By fixing the rear edge of the neutral holder 51 to the front line of the lens holding arm 37 in this manner, 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 a neutral state. As a result, coils 44 and 45 for focus operation and tracking operation are respectively provided.

Magnetically coupled to the outer yoke and magnet, each coil 4
The arm 37 can be rotated and moved in the thrust direction by the signal given to the arm 37 at 4.45.

Effects of the Present Invention Since the present invention is constructed in a practical manner, 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. There is.

Now, when the player is in the playback state, the light beam generator 9
The light beam 0 outputted from the light emitting element 11 of the diffraction grating 12. Beam splitter - 18° collimator lens +
4. The light passes through the I/4 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 light holes 4 and 2.
1, 12, and the objective lens 4 through the inner yoke 83°33.
0 and is focused onto the information track of disk D by the lens 4°.

Then, the reflected light beam containing the information component reflected from the disk D is conversely transmitted through the objective lens 4o through each light passage hole 4.
, 21.7. g to the reflective surface +6a of the prism 16, where the optical path is changed, and then the quarter-wave plate 15.g. The beam splitter 13 passes through the collimator lens 14
The light is reflected and irradiated onto the light-receiving surface of the light-receiving element I7.

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, the inner and outer yokes 38□85, and the ring magnet 34 is activated to hold the lens holding arm 37 neutrally. The objective lens 40 and the fulcrum shaft 29 resist the elasticity of the tool 51.
The lens is moved up and down along the thrust direction to obtain the optimum focus. Further, when the tracking error correction signal is applied to the tracking action 2 coil 45, the coil 4
5, the inner and outer yokes 86, 25, and the magnet 26 actuate the lens holding arm 37 against the elasticity of the neutral holder 51 to move the objective lens 40 around the fulcrum shaft 29. It is rotated, that is, moved in the radial direction, to position the convergence point of the light beam by the objective lens 40 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,
By rotating the adjustment screw 18 to the left or right, the prism 16 is moved up and down via the support piece 10', and the fixed surface 16b of the prism 16 is aligned with the optical axis of the light beam from the light emitting element 11 to the reflective surface 16a. When the optical axis of the light beam is adjusted to be parallel to the center of the objective lens, 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 86.25 and the magnet 26 that correspond to the tracking operation coil 45 on the lens holding arm 37, use the screw 81.
Loosen and move the first adjustment plate 27 and pedestal 19 to center the magnetic flux of the magnet 26 in the coil 45. It is preferable to position the inner yoke 36 and execute this operation.

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 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 stably moved in the radial direction, and an appropriate light beam can be directed onto the information track of the disk. A convergence point can be obtained.

Effects of the Present Invention Since the present invention is configured as shown on paper, it is possible to align the optical axis of the light beam with the center of the objective lens by moving the optical path changing means such as a prism using the adjusting means. I can do it,
Therefore, this is an excellent invention that allows information to be read from the information recording surface more accurately.

[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 8 are perspective views and plan views of the same device in an assembled state, and FIG. 4 is the same as FIG. 3. FIG. 5 is a sectional view taken along the line II', and FIG. 5 is an enlarged sectional view of the main part of FIG. 4. 1: light emitting element, 16: prism, 18: adjustment screw, 40
:Objective lens. Agent Benken♀ Aihiko Fukushi (and 2 others) No. ／
figure

Claims (1)

[Claims] 1. The light beam emitted from the light emitting element is guided to an objective lens by changing its optical path using an optical path changing means having a reflective surface midway, and is converged by the objective and lens and irradiated onto an information recording surface to optically read information. In the optical system, the optical axis of the light beam whose optical path has been changed by being reflected by the reflecting surface is aligned with the center of the objective lens by moving the optical path changing means with an adjusting means. information reading device.