JPS6028040A - Optical information reader - Google Patents

Abstract

PURPOSE:To improve the accuracy when the information is read out of an information track by attaining the control of position for a neutral position holding tool which holds an objective lends holding arm at a neutral position in the thrust and radial directions. CONSTITUTION:A neutral position holding tool 51 made of a rubber material is supported at an insertion opening 52 by a support shaft 49 of a control plate 46 and fixed by a fixing tool 53. This tool 51 is welded at the front edge of a lens holding arm 37 at the rear edge part of the tool 51. Thus the arm 37 floats over a holding stage 19 in the axis direction of a fulcrum shaft 29, that is, the arm 37 is set at its neutral position. As a result, focusing and tracking coils 44 and 45 are connected magnetically to corresponding inside and outside yokes and magnets respectively. Furthermore, the plate 46 is moved on the stage 19 after unfastening a screw 50 and the arm 37 is turned in the radial direction via the tool 51. Thus the coincidence is obtained between the center of an objective lens and the optical axis of a light beam. Thus the information can be read with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical information reading device that optically reads information from a computer.

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 include: (1) a light emitting element, a diffraction grating, and a beam splitter 1174;
By moving the entire case that houses the wave plate, prism, objective lens, etc. by applying a tracking error correction signal to the tracking operation coil, radial direction control is executed, and focus control is performed to the focus operation coil to eliminate the 7-occasion error. This method is executed by applying a correction signal and moving the objective lens up and down.

Or ■ @,? This method was developed as a j4e method, and as disclosed in Japanese Patent Application Laid-Open No. 57-210457, coils for focusing and tracking operations are provided inside and outside the outer periphery of the holding cylinder of the objective lens. A system in which a yoke and a magnet are provided on the inside and outside of the cylinder, and tracking and focusing are performed by applying focus and tracking error correction signals to each coil to move the holding cylinder in the thrust direction and radial direction.

etc. have been developed.

In the method (■) above, the focus control mechanism uses a coil to vibrate the objective lens itself.

Because it has a structure in which a magnet, etc. is combined with the objective lens, it has the disadvantage that it is extremely small and difficult to assemble and maintain and inspect.However, in the method (■), the objective lens is decentered. In order to wrap a coil for focusing and tracking operations around the outer circumference of the lens holding tube provided,
Since it has a structure that allows the movement of the focus system to be obtained, it has the advantage that it can be made smaller overall compared to the system (2).

However, in this method (■), an elastic plate is generally installed between the plywood and the lens holding tube in order to obtain a neutral point in the thrust and radial directions of the lens holding tube, but this elastic plate can be adjusted in position. Because it does not have a function, it is difficult to align the center of the objective lens with the optical axis of the light beam due to dimensional variations in each component, assembly errors, etc., and in some cases, the light beam is placed at the correct position on the information track in the correct condition. It had the disadvantage of not being able to converge.

<Object of the present invention> The present invention was invented in view of the above-mentioned drawbacks of the conventional apparatus, and the present invention is directed to a neutral holder that holds a holding means for holding an objective lens at a neutral position in the thrust and radial directions. It is intended to be adjustable and to overcome the drawbacks of conventional devices.

The male side will be explained in detail according to the attached 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 the line I-■' in the figure is shown.

In these figures, l is the main body of the device with an optical system support hole 2 open on one side, and screws 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) 11 housed in a holding cylinder lO.
1 diffraction grating +2. Beam splitter 13, collimator lens l4, I/4 wavelength plate 15 and the above holding cylinder lO
The light beam optical path changing means is fixed on the inclined surface IO" of the support piece 10' at the tip of the support piece 10' and is housed in the system support hole 2.

Reference numeral 17 denotes a light-receiving element consisting of a four-split photoda, diode, etc., which is fitted into a support hole 8 opened at the front of the apparatus main body l, and whose light-receiving surface is arranged to receive the reflected light beam from the beam splitter 13. It faces into the optical system support hole 2.

Reference numeral 18 is an adjustment screw screwed into the bottom surface of the device main body l 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 supporting piece 10' is moved up and down as shown in FIG. The surface +6b can be adjusted so as to be parallel to the optical axis of the light beam 0 that reaches the reflective surface 16a of the prism 16 from the light emitting element II.

Here, the reason why it is possible to adjust with the adjustment screw 1'8 is that the angle L AB of the prism 16 is
C (45°) and the prism I6, that is, the prism 16, changes the direction of the light beam from the light emitting element II and directs it to the central force direction of the objective lens, which will be described later. It is provided to converge the light beam perpendicular to the position, but if the angle LABC 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 0, the objective lens There is a problem in that the optical axis of the light beam cannot be aligned with the center.

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 I6 is fixed on the inclined surface 10'' with the upper surface of the inclined surface 10'', and then, by operating the adjustment screw 18, the fixed surface +6b of the prism 16 is made parallel to the optical axis of the light beam, The optical axis of the beam is made to coincide with the center of the objective lens.

Reference numeral 19 denotes a plywood board made of a non-magnetic material placed on the device body 1 between the stepped portions 5, and has 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 2-
1 and a receiving protrusion 23 having a screw hole 22 at both ends of the front edge, and a support piece 24 shaped like [<] 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 is a magnetic circuit 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 30 on both sides of the extension part 28 and the rear edge, respectively, and has arc-shaped adjustment holes 30 on both sides of the extension part 28 and the rear edge. Step 5 of l
and fixed on each body 1.

This first adjusting plate 27
By being fixed to the upper part, the lower end of the fulcrum shaft 29 is inserted into the bearing hole 3 of the apparatus body l through the shaft hole 20 of the base plate 19, and the light passage hole 32 provided in the center of the plate surface is inserted into each of the above-mentioned light passage holes 4. , 21.

Reference numerals 33 and 38 denote inner yokes for focus operation that are fixed on the first adjustment plate 27 so as to sandwich the fulcrum shaft 29 back and forth. The light passage hole 32 is provided.

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. .

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

In short, the inner yoke 33° ring magnet 34 for focusing operation. 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 lens 40 is provided on one outside of the vaginal opening 39 so as to sandwich the shaft insertion port 39, and a weight 4 is provided on the other outside.
2 is fixed.

Further, this lens holding arm 37 has a cylindrical bobbin 43 integrally provided 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 48 can be inserted into the inner side. Hanging between yoke 33 and ring magnet 34 (outer yoke 35).

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 338 ring magnet 34 and 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 magneto-soto 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 projection 23 on the base plate 19, and is fixed on the receiving projection 23 by screwing the screw 50 into the screw hole 22 through the adjustment hole 47, and by loosening the screw 50. , can slide in a direction perpendicular to the cap 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 hole 52 and is prevented from coming off with a stopper 53. and is fixed to the front edge of the lens holding arm 37.

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.

It is magnetically coupled to the outer yoke and the magnet, and the arm 37 can be rotated and moved in the thrust direction by signals given to each coil.

Function of the present invention Since the present invention is constructed in a diagonal manner, its function will be explained next.

The optical information reading device of the present invention configured as shown in 4Q above is located within the player body as shown by 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. 0 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 passes through the diffraction grating 12, the beam splitter 18, and the collimator lens 14.
, the reflective surface 16a of the prism 16 via the I/4 wavelength plate 15
At this point, the optical path is changed to the optical hole 4.21, 1.
32 and the inner yoke 33, the light passes through the objective lens 40, and is focused onto the information track of the disk D by the lens 40.

Then, the reflected light beam containing the information component reflected from the disk D is conversely transmitted from the objective lens 40 to each light passage hole 4.
21.12, it reaches the reflective surface +6a of the prism 16,
After changing the optical path here, 1/4 wavelength plate 1'2g
The above beam splitter via the remeter lens 14! 3
The light is reflected and 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, a first motor consisting of the coil 44, inner and outer yokes 83, 85, and ring magnet 34 is activated to move the lens holding arm 37 to a 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, the second motor consisting of the coil 45, the inner and outer yokes 36, 25, and the magnet 26 operates to move the lens holding arm 37. The objective lens 40 is rotated about the fulcrum shaft 29 against the elasticity of the neutral 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 +6b of the prism 16 with respect to the optical axis of the light beam from the light emitting element 11 to the reflective surface +6a. 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.

Eh, v k' 蝙椿ah 7.8 □ top. ,,7 yoke 77@inner and outer yoke 86.25 corresponding to working coil 45
When adjusting the positional relationship of the magnet 26, loosen the screw 31 and move the first adjustment plate 27 and pedestal 19 to align the coil 45. with the center of the magnetic flux of the magnet 26. inner yoke 36
It is best to position and execute.

Further, when aligning the objective lens 4o in the radial direction, loosen the screw 5o and move the second adjustment plate 46 on the pedestal 19, and move the lens holding arm 37 via the neutral holder 51. It is best to rotate it in the radial direction.

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 inner yoke 36% and the magnetic flux center of the tracking operation maknet 26 are aligned, and as a result, the objective lens can be moved stably 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 in a diagonal manner, the center of the objective lens can be adjusted by moving the adjustment plate and rotating the lens holding arm around the fulcrum axis via the neutral holder. It is possible to provide a device in which the optical axes of the light beams can be aligned and, therefore, information can be read accurately from the information track.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an embodiment of an 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 a diagram showing FIG. 8. 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. 29: fulcrum shaft, 37: lens holding arm, 40: objective lens, 46: second adjustment plate, 51: neutral holder.

Claims (1)

[Claims] 1. A lens holding arm that is rotatable about the fulcrum shaft and slidably supported in the thrust direction of the fulcrum shaft, an objective lens provided on the lens holding arm at a distance from the fulcrum shaft, and the fulcrum shaft. an adjustment plate that can be slid in a direction perpendicular to the 3D and fixed at any position, one end of which is fixed to the lens holding arm, and the other end of which is fixed to the adjustment plate, and the lens holding arm is held in a neutral state on the fulcrum axis; An optical system comprising: a neutral holder made of an elastic member; first motor means for moving the lens holding arm in a thrust direction; and second motor means for rotating the lens holding arm about the fulcrum shaft. Information reading device.