JPH0386929A - Detached optical pickup device - Google Patents

Abstract

PURPOSE:To provide the optical axes of fixed optical system wholly on the same plane and to make the optical pickup device thin by supporting a deflecting member so as to be rotated around the axis parallel to the optical axis of a light flux to be made incident from a light flux emitting system for executing tracking operation. CONSTITUTION:The light flux to be emitted from a semiconductor laser 31 in a fixed optical system B is passed through a coupling lens 32, polarizing beam splitter 33 and quarter wave plate 34, which constitute the light flux emitting system, and afterwards, the light flux is made incident on a polarizing prism 35. After the light flux is polarized in this prism, the light flux is emitted to a moving optic system A. Namely, the optical axes of the light fluxes from the light flux emitting system of this fixed optical system B to the polarizing prism 35 are wholly arranged in the same line and the polarizing prism 35 is turned at a prescribed angle with the emitting optical axis of the semiconductor laser 31 as a center and the tracking operation is executed. Thus, the optical axes of the fixed optical system can be wholly set in the same line and the device can be made thin.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention records and reproduces information on an optical information recording medium via a fixed optical system and a moving optical system, and also records and reproduces information on an optical information recording medium using reflected light from the optical information recording medium. The present invention relates to a separate type optical pickup device that performs focus servo and tracking servo using the following.

[Prior Art] An optical pickup device used for recording and reproducing information on an optical disk is provided with a tracking device for positioning a light spot on the surface of the optical disk, that is, for performing a tracking operation. This tracking device precisely positions the light beam as a spot on the optical disc surface by deflecting the light beam emitted from a semiconductor laser by a tracking mirror and passing it through a focusing optical head while adjusting the optical path.

Furthermore, in general optical pickup devices, in order to perform high-speed access operations, for example,
As described in Japanese Patent No. 869, a two-stage positioning mechanism consisting of a coarse positioning mechanism and a fine positioning mechanism using the tracking device described above is often employed.

In such a two-stage positioning device, if there is mechanical interference between the two positioning mechanisms, it will cause a disturbance that impedes the positioning operation, and if there is a weight imbalance around the rotation axis of the tracking mirror used for the tracking moving surface, A rotational moment about the axis is generated by the moving surface of the rough positioning mechanism, and the tracking mirror is shaken by this.

Therefore, in Japanese Patent Application Laid-Open No. 60-163235, the rotation axis of the tracking mirror is arranged almost parallel to the moving direction of the coarse positioning mechanism, and an optical system that rotates the direction of deflection of light from the tracking mirror by 90 degrees is used in the tracking mirror. and the focusing optical system.

That is, as shown in FIG. 9, a semiconductor laser 2 and a plurality of reflecting mirrors 3 are mounted on the optical pickup body 1.
, a galvanometer mirror 4, an objective lens 5, etc. are mounted. In this case, the light emitted by the semiconductor laser 2 is focused by the objective lens 5 and irradiated onto the surface of the optical disk 6. Adjustment of the position of the light spot (tracking servo)
As a method, by moving the optical pickup main body l mounted on the roller 7 in the theta direction S,
Then, make rough adjustments to the rack position, and also make the theta direction S.
Fine adjustment of the position of the track 8 formed on the optical disk 6 is performed by rotating a galvanometer mirror 4 having a rotating shaft.

Therefore, by setting the rotation axis of the galvanometer mirror 4 parallel to the theta direction S, the mechanical interference between the coarse positioning mechanism and the fine positioning mechanism can be eliminated, and a stable light spot can be irradiated at all times. can be done. In addition, it eliminates mechanical interference between the movement of the optical pickup and the rotation of the tracking mirror, eliminates the influence of weight imbalance around the rotation axis of the tracking mirror, and enables stable spot positioning control as well as track access. The access time can be shortened by eliminating the vibration of the racking mirror caused by the movement of the optical pickup.

However, in such conventional devices, the entire optical pickup is configured to move in the radial direction of the optical disk, so the weight of the movable part is large, making it impossible to perform sufficiently high-speed access operations.

Furthermore, since an optical system that rotates the deflection direction by 90 degrees is required, the number of optical parts has increased, and the weight of the moving parts has increased, making it difficult to eliminate mechanical interference due to the movement of the moving parts. However, it has not been possible to achieve a complete reduction in access time.

To solve this problem, we installed a tracking mirror on a fixed part to eliminate mechanical interference caused by the movement of the movable part.
A device that reduces the weight of the movable part and shortens the access time has been proposed by the applicant in Japanese Patent Laid-Open No. 63-227842.

In this proposed device, as shown in FIG.
The light beam emitted from the semiconductor laser 10 of the fixed optical system B is collimated by the coupling lens 12 constituting the light beam output system, and is parallelized by the deflection beam splitter 13 and 1/4.
After passing through the wavelength plate 14, the light is deflected by a deflection prism 15, and the deflected light is again deflected by a tracking mirror 16 and output to the moving optical system A.

The moving optical system A is reciprocated in the radial direction (theta direction S) of the optical disc 23, and is
3 is placed on a turntable fixed to a rotating shaft (not shown).

A carriage base 18 of this moving optical system A is installed on a guide rail 22 disposed in the longitudinal direction S so as to be movable back and forth via rollers 18a. and an objective lens 20 are mounted. The light flux incident from the fixed optical system B is deflected by a deflection prism 21 and then focused by an objective lens 20 so as to form a minute spot on the optical information recording medium of the optical disc 23. The focusing of the objective lens 20 is controlled by a focus actuator 9, which is shown in a simplified manner.

On the other hand, the reflected light from the optical disk 23 is reflected by the objective lens 2
0 and the deflection prism 21 to the fixed optical system B, and the tracking mirror 16 and the deflection prism 15.1.
After successively passing through the /4 wavelength plate 14, the beam is deflected by the deflection beam splitter 13 and passed through the condensing lens 25 and the cylindrical lens 26 to be given astigmatism.
The light is incident on the dividing element 27, whereby a predetermined information signal is detected, a focus error signal and a track error signal are detected, and the information signal is further reproduced. Based on the focus error signal, the focus actuator 19 is operated to control the movement of the objective lens 20 in the optical axis direction, and the tracking mirror 16 is rotated to perform tracking based on the tracking error signal.

Since the mechanism including the tracking mirror 16 that performs tracking servo is provided in the fixed optical system B, the weight of the movable optical system A, which is the movable part, is significantly reduced, thereby significantly shortening the access time. In addition, it is possible to eliminate mechanical interference with the fixed optical system B due to the movement of the moving optical system A.

[Problems to be Solved by the Invention] However, in this device, the deflection prism 15 is arranged to face above or below the tracking mirror 16, and the optical path a from the deflection prism 5 to the tracking mirror 16 is connected to the light beam output system. It is necessary to provide the optical path separately from the optical path in For this reason, the optical axes of the fixed optical system B cannot all be provided in the same line, making it difficult to reduce the thickness of the optical pickup device. That is, the optical path a from the deflection prism 15 to the tracking mirror 16
is set in a direction perpendicular to the surface of the optical disc 23, and is set in a direction perpendicular to the optical path connecting the fixed optical system B and the moving optical system A. Therefore, the optical path C in the direction perpendicular to the surface of the optical disc 23 becomes long, and the space in the height direction H of the optical pickup device becomes large.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a separate optical pickup device in which all the optical axes of the fixed optical system B can be provided in the same plane, and the device can be made thinner.

[Means for Solving the Problems] In order to achieve the above object, the invention described in claim 1 includes a fixed optical system including a light beam output system.

In a separate optical pickup device comprising a movable optical system that irradiates a light flux emitted from the fixed optical system onto an optical disk, the fixed optical system deflects and moves the light flux emitted from the light flux output system. The optical system is provided with a deflection member for outputting the light beam, and the deflection member is rotatably supported around an axis parallel to the optical axis of the light beam incident from the light beam output system so as to perform a tracking operation. We are hiring.

Further, the invention described in claim 2 provides the separation type optical pickup device described in claim 5, wherein the deflection member is arranged at a predetermined rotation angle that coincides with the optical axis of the light beam incident from the light beam output system. A configuration is adopted in which the shaft is supported by at least a pair of leaf springs so as to be rotated around a moving axis.

Furthermore, the invention described in claim 3 collimates the light emitted from the semiconductor laser using a coupling lens, passes the collimated light through a deflection beam splinter, and outputs the light from the fixed optical system to the outside. Then, this emitted light is reflected by a deflection prism placed in the moving optical system,
After condensing the light with an objective lens, information is recorded and reproduced by irradiating the light onto an optical information recording medium placed outside the moving optical system, and the reflected light from the optical information recording medium is transmitted to the moving optical system. In a separate optical pickup device that detects a focus error signal, an l-rack error signal, etc. by passing through the optical system and guiding it again to the signal detection section of the fixed optical system, the light emitted from the semiconductor laser is connected to the deflected beam. A first deflection member rotatable about an axis perpendicular to the surface of the optical information recording medium is disposed on the optical path in the fixed optical system that goes outside via the splitter, and the first deflection member a second deflection member that deflects the deflected light emitted from the fixed optical system and incident into the moving optical system by 90' within a parallel plane of the optical information recording medium on an optical path between which the deflected light is guided to the deflection prism; A configuration with .

[Function] In the means having the configuration described in claim 1, the light beam emitted from the light beam output system of the fixed optical system is immediately emitted to the movable optical system via the deflection member, and the deflection member is fixed. The tracking operation is performed by rotating the optical system around an axis parallel to the optical axis of the emitted light beam from the optical system.

Therefore, there is no need to provide an optical path separate from the optical path in the light beam output system of the fixed optical system between the deflection member of the fixed optical system and the moving optical system, and the optical axes of the fixed optical system are all provided in the same line. It looks like this.

Further, in the means having the configuration described in claim 2, the rotational movement of the deflection member accompanying the tracking moving surface is performed so as not to cause a positional deviation from the optical axis of the emitted light beam from the fixed optical system. Therefore, the light receiving area and rotation space required for the deflection member can be minimized.

Furthermore, in the means having the structure described in claim 3, in the fixed optical system, an optical path emitted from the semiconductor laser, passed through the deflection beam splitter, and reflected by the first deflection member; Optical pickup The space in the height direction of the device (direction perpendicular to the surface of the optical information recording medium) is omitted.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

As shown in Figure 1, a moving optical system A and a fixed optical system B
is installed on a base frame which is not shown in the figure. The light beam emitted from the semiconductor laser 31 in the fixed optical system B is transmitted through the coupling lens 32 . After passing through a deflection beam splitter 33 and a quarter-wave plate 34, the light enters a deflection prism 35, where it is deflected and then emitted to a moving optical system A. That is, the optical axes of the light beams from the light beam output system of the fixed optical system B to the deflection prism 35 are all arranged in the same line.

The moving optical system A is reciprocated in the radial direction of an optical disk 43 indicated by a broken line, and the optical disk 43 is placed on a turntable fixed to a rotating shaft (not shown). . In this moving optical system A, a carriage base 38 is installed on a guide rail 42 so as to be movable back and forth in the radial direction of the optical disk 43, and a deflection prism 4 is mounted on the carriage base 38.
1 and an objective lens 40 are provided. The light beam emitted from the fixed optical system B is directed to the deflection prism 41.
After being deflected by the objective lens 40, the light is focused to form a minute spot on the optical information recording medium of the optical disc 43.

At this time, the objective lens 40 is focused by a focus actuator (not shown).

Further, the reflected light from the optical disk 43 is emitted again to the fixed optical system B via the objective lens 40 and the deflection prism t141. The light flux returned to the fixed optical system B is deflected by a quarter-wave plate 34 and a deflection beam splitter 33 via a deflection prism 35, and is incident on a quarter-dividing element 47 through a condenser lens 45 and a cylindrical lens 46. As a result, an information signal is detected, as well as a focus error signal and a tracking error signal. Based on the focus error signal, the focus actuator is operated to control the movement of the objective lens 40 in the optical axis direction, and the opening mechanism for the deflection prism 35 is operated based on the track error signal, so that the deflection prism 35 is laser 3
It is designed to be rotated over a predetermined angle about the output optical axis of No. 1.

Furthermore, an embodiment of the support system for the deflection prism 35 is shown in FIGS. 2(a) and 2(b). Figure 2 (a
) and (b), the deflection prism 45 is supported on the main body side via a pair of leaf springs 48, 48. Each of these leaf springs 48 extends from a fixed end on the main body side in a direction perpendicular to the emission optical axis X of the semiconductor laser 31, and extends in a plane perpendicular to the emission optical axis X of the semiconductor laser 31. It is installed so that it can be bent around the fixed end on the main body side. As a result, the deflection prism 35 is rotated around the emission optical axis X of the three semiconductor lasers within a rotation angle range necessary for tracking. At this time, the deflection prism 4 is defined by the arrangement of the drawing plate springs 48, 48.
The rotation axis 5 is formed at a position where extension lines 48a, 48a from the fixed end edge portion of each leaf spring 48 on the deflection prism 35 side intersect. And the above both extension lines 4
The intersection position of 8a and 48a, that is, the rotation axis of the deflection prism 35 is configured to coincide with the emission optical axis X of the semiconductor laser 31.

The tracking operation of the polarized II'+] prism 35 in such an embodiment will be explained with reference to FIG. First, in FIG. 3(a), the lower side is the semiconductor laser 31 side, and the right side is the moving optical system A side. Also, Fig. 3(b) and (
c) is a diagram seen from the semiconductor laser 31 side. If it is necessary to tilt the emitted light from the fixed optical system B by θ in the tracking direction in order to perform a tracking operation, as shown in FIG. 3(c), the semiconductor laser 31
The deflection prism 35 is rotated by 0 around the optical axis X of the emitted light. As a result, the light emitted from the fixed optical system B is tilted by O in the tracking direction.

Furthermore, for comparison, FIG. 4 shows that the rotation axis of the deflection prism 35 is arranged so as not to coincide with the optical axis X of the emitted light of the semiconductor laser 3t, and the light ipHl A case is shown in which the deflection prism 35 is rotated about an arbitrary parallel axis Y. Figures 4(a) and (b).

(c) is a diagram corresponding to FIGS. 3(a), (b), and (0), respectively. In the comparative example shown in FIG. 4, a semiconductor laser 3 is used for tracking operation.
When the deflection prism 35 is rotated by 0 around an arbitrary axis Y that is parallel to the optical axis In this case, Fig. 4 (
As shown in C), the emitted light beam of the semiconductor laser 31 is misaligned with respect to the reflective surface of the rotated deflection prism 35, and the emitted light beam from the semiconductor laser 31 deviates from the reflective surface of the deflection prism 35. It is possible that

For this reason, the deflection prism 3 in the case shown in FIG.
The reflective surface 5 requires a wider area than in the case of Fig. 3, and the movement space f'+4 for the rotation of the deflection prism 35 is the same angle in the case of Fig. 3 and the case of Fig. 4. The rotation surface in FIG. 4 is larger than that in FIG. 4, which becomes an obstacle in the design of the display system and the support system.

From the above, it is preferable that the rotation axis of the deflection prism 35 coincides with the emission optical axis of the semiconductor laser 31.

The above-described support structure is similarly effective even when the deflection prism 35 is not directly supported but is fixed to a holder member and then the holder member is supported. Further, even when the leaf springs 48 are configured in a plurality of pairs, similar actions and effects can be obtained.
The installation angle of each leaf spring 48 is also not limited to the illustrated case.

5(a) and 5(b) show another embodiment of a support system for aligning the deflection prism 35 with the emission optical axis X of the semiconductor laser 31. In FIGS.

In the embodiment shown in FIGS. 5(a) and 5(b), the deflection prism 35 is supported by three leaf springs 49. In the embodiment shown in FIGS. Each leaf spring 49 extends in a direction parallel to the emission optical axis X of the semiconductor laser 31, and is arranged on a concentric circle centered on the emission optical axis X of the semiconductor laser 31. It is arranged so that it can be bent in the tangential direction of the main body side fixed end.

Further, the extension lines of the plate springs 49 in the plate width direction are supported so as to intersect on the emitted light $111X of the semiconductor laser 31. As a result, the rotation axis of the deflection prism 35 is made to coincide with the emission optical axis X of the semiconductor laser 31, and the deflection prism 3
5 is adapted to be rotated. Even in such an embodiment, the same functions and effects as in the above embodiment can be obtained.

The support method shown in FIG. 5 does not directly support the deflection prism 35, as in the above embodiment, but instead fixes the deflection prism 35 to a holder member and then supports the holder member. The present invention is also effective in the case where the above-mentioned leaf springs 49 are used, and the number of leaf springs 49 and the installation angle of the leaf springs are not limited to those shown in the drawings.

Furthermore, in the above embodiment, a deflection prism is used as a deflection member having a rotation axis at least parallel to the emission optical axis X of the semiconductor laser 31, but other materials such as a flat deflection mirror may also be used In this case, similar actions and effects can be obtained.

Next, in the embodiment shown in FIG. 6, within the fixed optical system B, the light emitted from the semiconductor laser 50 is placed on the optical path of the light emitted to the outside via the deflection beam splinter 52. A tracking mirror 68 is provided as a first deflection member that is rotatable about an axis perpendicular to the surface of the optical disk 62. In the moving optical system A, the light that is deflected by the tracking mirror 68, emitted from the fixed optical system B, and entered into the moving optical system A is placed on the optical path of the optical disk 62 while being guided to the deflection prism 60. Light incident in parallel planes is 90'
The deflection prism 69 as a second deflection member to deflect is R
e).

In such a configuration, the light emitted from the semiconductor laser 50 passes through the coupling lens 51, the polarizing beam splitter 52, the wavelength plate 53 in sequence, is reflected by the tracking mirror 68, and is emitted from the fixed optical system B. is guided into the moving optical system A. The light incident on the moving optical system A is reflected by the deflection prism 69, further reflected by the deflection prism 69 in a direction perpendicular to the surface of the optical disk 62, and is condensed by the objective lens 61 to be focused on the surface of the optical disk 62. is irradiated. Further, the light reflected by the optical disk 62 is transmitted through the objective lens 60. The deflection prisms 60 and 69 are sequentially valved, and the beam enters the fixed optical system B again, is sequentially reflected by the tracking mirror 68 and the deflection beam splitter 52, and is guided into the signal detection section 63, thereby detecting focus error signals and tracking errors. Detection of signal 8-A5 is performed.

In this case, as shown in FIGS. 7 and 8, by rotating the tracking mirror 68 about an axis perpendicular to the surface of the optical disk 62, the light deflected by the tracking mirror 68 is The polarization angle changes within a plane parallel to the surface of the optical disk 62 on which the track mark O is formed, and the light with the changed polarization angle passes through the deflection prism 6.
The light beam is deflected by 90° by the deflection prism 60, and then reflected by the deflection prism 60 and irradiated onto the surface of the optical disk 62.

By providing this deflection prism 69, light can be deflected in a direction across the racks 70. Therefore, tracking servo can be performed by rotating the tracking mirror 68 based on the tracking error signal detected within the signal detection section 63. Note that the mechanism for performing focus servo can be performed using the astigmatism method as in the conventional case.

As described above, by providing the tracking mirror 68 rotatable in a plane around the axis perpendicular to the surface of the optical disk 62 in the fixed optical system B, all the optical components in the fixed optical system B can be arranged in the same plane. As a result, the thickness of the separate optical pickup in the height direction (the direction 11'0 perpendicular to the optical disk surface) can be made much thinner than in the past.

[Effect of the invention As stated above, the invention stated in claim 1 is:
While deflecting the light beam from the light beam output system of the fixed optical system, so as to eliminate the need to provide an optical path separate from the light path in the light beam output system of the fixed optical system between the fixed optical system and the moving optical system. A deflection member is provided to direct the light to the moving optical system,
Since this deflection member is rotated around an axis parallel to the optical axis of the emitted light beam from the fixed optical system to perform the tracking operation, it is possible to set all the optical axes of the fixed optical system in the same line. This allows the optical pickup device to be made thinner. Further, since there is no need to provide an optical path separate from the optical path in the light beam output system of the fixed light l: system, the number of parts can be reduced by one, and the number of parts can thereby be reduced to 11.

Further, the invention described in claim 2 is such that the rotational movement of the deflection member accompanying the tracking moving surface is performed so that the optical axis of the emitted light flux from the fixed optical system is not misaligned. Since the deflection member is configured to rotate around a predetermined rotation axis that coincides with the optical axis of the light flux incident from the system, in addition to the effects described in claim 1,
The light-receiving area and rotation space required for the deflection member can be minimized, thereby making it possible to further reduce the thickness and weight of the optical pink-up device.

Furthermore, the invention described in item 3 is such that a first deflection member is disposed on the optical path of the fixed optical system, and the first deflection member is rotatable about an axis perpendicular to the surface of the optical information recording medium. A second deflection member is disposed on the optical path between which the light that has been deflected by the fixed optical system, exits from the fixed optical system, and enters the moving optical system is guided to the G prism, and deflects the light by 90'' in a plane parallel to the optical information recording medium. As a result, tracking servo can be performed by rotating the first deflection member in a plane parallel to the optical information recording medium, and thereby all optical components in the fixed optical system can be arranged in the same plane. As a result, it is possible to save space in the height direction of the optical pickup device (in the direction perpendicular to the surface of the optical information recording medium), and the overall configuration of the device can be made more compact than before. It is something.

[Brief explanation of drawings]

The first construction drawing is a schematic plan view showing an optical pickup device according to an embodiment of the present invention, and FIGS. 2(a) and 2(b)
) is an explanatory plan view and an explanatory rear view showing the support structure of the deflection member in the embodiment shown in FIG. 1, and FIG.
), (b), (c) and Fig. 4 (a), (b), (c
) is the deflection representing the tracking operation of the deflection member) i'+
5(d) and (b) are an enlarged explanatory view of the J member, and FIG. 7 and 8 are block diagrams showing other embodiments, and FIGS. 7 and 8 are optical path diagrams and perspective views thereof showing how the optical path is changed by the tracking mirror in the embodiment shown in FIG. FIG. 10 is a schematic side view showing an optical pickup device in a conventional proposed example. A...Moving light 'Z: system, B...Fixed optical system, 31,
50... Semiconductor laser, 35,4↓... Deflection prism, 40.61... Objective lens, 47... Light receiving element. 68...First deflection member, 69...Second deflection member. (Other names) v) 40 v) 7 days 1580 1P) q form a mouth

Claims (1)

[Scope of Claims] 1. A separate optical pickup device comprising a fixed optical system including a light beam output system and a moving optical system that irradiates the light beam emitted from the fixed optical system onto an optical disk, The optical system is equipped with a deflection member that deflects the light flux emitted from the light flux output system and outputs it to the moving optical system, and the deflection member deflects the light flux incident from the light flux output system so as to perform a tracking operation. A separate optical pickup device characterized in that the device is rotatably supported around an axis parallel to the optical axis of the device. 2. In the separated optical pickup device according to claim 1, the deflection member is rotated at least about a predetermined rotation axis that coincides with the optical axis of the light beam incident from the light beam output system. A separate optical pickup device characterized by being supported by a pair of leaf springs. 3. The light emitted from the semiconductor laser is collimated by a coupling lens, the collimated light passes through a polarizing beam splitter and is emitted from the fixed optical system to the outside, and the emitted light is sent into the moving optical system. The light is reflected by a deflecting prism placed in the system, focused by an objective lens, and then irradiated onto an optical information recording medium placed outside the moving optical system, thereby recording and reproducing information. In a separate optical pickup device that detects a focus error signal, a tracking error signal, etc. by passing reflected light from a medium through the moving optical system and guiding it again to a signal detection section of the fixed optical system, the light emitted from the semiconductor laser A first deflection member rotatable about an axis perpendicular to the surface of the optical information recording medium is disposed on an optical path in the fixed optical system on which the deflected light is directed to the outside via the deflection beam splitter. , 90 degrees within a parallel plane of the optical information recording medium on the optical path between which the light deflected by the first deflection member, emitted from the fixed optical system, and entered into the moving optical system is guided to the deflection prism. A separation type optical pickup device characterized in that a second deflection member for deflecting the light is provided.