JP2746303B2 - Optical head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention optically records information on an optical disc and / or
And an optical head used in an optical recording / reproducing apparatus for reproducing.

(Prior Art) With the aim of increasing the recording capacity and increasing the density, information recording and / or reproduction on an optical disk has become popular. On the other hand, it is necessary to move the objective lens of the optical head.

To move such an optical head, a DC motor is driven, the gears are decelerated, the gears are moved by meshing the gears with a rack arranged in the optical head, the lead screw is rotated using the DC motor as a drive source, There is known a method in which a lead pin engaged with a lead screw is provided on an optical head to move the optical head. For high-speed access, there is a demand that the optical head be miniaturized as much as possible.
Therefore, the movable optical system is divided into a movable optical system such as an objective lens and a fixed optical system such as a light source detection sensor, and the movable optical system is made as lightweight and compact as possible. The optical head having such a configuration is assembled, for example, in a configuration as shown in FIG. 2 and FIG. That is, the optical system of the optical head generally adopts a configuration as shown in FIG. Here, a divergent light beam is directed to the collimator lens 3 from the semiconductor laser 2 as a light source,
Here, the light is transmitted as a parallel light beam through the polarization beam splitter 4 and is brought to the objective lens 6 via a bending mirror 5 as an optical path polarizing means. The luminous flux is condensed by the objective lens 6 and is radiated on the recording surface of the optical disc 1 as a required light beam spot. Then, the reflected light from the recording pit goes back through the objective 6 and the bending mirror 5, is separated by the polarization beam splitter 4, and is directed to the sensor lens 7. The light beam that has passed through the sensor lens 7 is incident on the sensor 9 as converged light. In order to enable signal extraction for the purpose of autofocus, a cylindrical lens 8 for generating astigmatism is provided during this time. Provide. Here, only the objective lens 6 and the bending mirror 5 are used as a movable optical system, and the others are used as fixed optical systems.
The movable optical system is mounted on a carriage 12, as shown in FIG. 3, and the carriage 12 is provided with an actuator 11 for auto-focusing the objective lens 6. The carriage 12 has an optical head frame 20 parallel to the optical axis connecting the polarizing beam splitter 4 and the bending mirror 5.
The carriage 12 is movably supported by a pair of guide shafts 13, and a drive coil 14 of a linear motor is mounted on one side of the carriage 12. A main yoke 15 is provided through the drive coil 14 of the linear motor and parallel to the guide shaft 13, and a sub-yoke 16 parallel to the main yoke 15 is provided outside the drive coil 14 via a spacer yoke 18. Is provided. Thus, when the drive coil 14 is energized, the carriage 12 moves forward or backward along the guide shaft 13 in the direction of the current, and is moved in the radial direction of the optical disc 1. The optical head frame 20 includes an optical head block 21 of a fixed optical system incorporating a semiconductor laser 2, a collimator lens 3, a polarizing beam splitter 4, a sensor lens 7, a cylindrical lens 8, a detection sensor 9, and the like. Etc. are fixed.

In the drawing, reference numeral 19 denotes a motor for driving the optical disc 1, and reference numerals 22 and 23 denote mounting pieces and mounting screws for fixing the guide shaft 13 to the optical head frame 20.

(Problem to be Solved by the Invention) The problem here is how to make optical adjustment between the movable optical system and the fixed optical system. That is, in the above example, it is necessary to strictly adjust the optical axis connecting the polarization beam splitter 4 and the bending mirror 5, and to increase the parallelism between the guide axis 13 and the optical axis. FIG. 4 shows a state in which the parallelism between the optical axis and the guide axis 13 is poor. In this case, the distance between the optical axes (the optical axis a of the polarizing beam splitter 4 and the optical axis b of the bending mirror 5 is different). (Between) is inclined. FIG. 5 shows a state in which there is no inclination between the optical axes a and b, but the parallelism between the optical axis and the guide shaft 13 is poor.
As a result, in any case, depending on the position of the objective lens 6 (determined by the amount of movement of the carriage), the irradiation light beam and the reflected light beam are displaced, and stable auto-focus and auto-tracking control cannot be performed. The information rate is increased due to the unstable reproduction of the information.

Therefore, screws cannot be fixed until the optical head block 21 of the fixed optical system is completely positioned. However, this positioning is extremely difficult because there is no mechanical reference to the movable optical system. For this reason, time consumption at the time of assembly is large, and work efficiency is low. In particular, there is a difficulty that adjustment between the optical axes and adjustment of the parallelism between the optical axis and the guide shaft 13 must be performed simultaneously.

(Object of the Invention) The present invention has been made based on the above circumstances, and a relative positioning of a movable optical system and a fixed optical system is facilitated by providing a guide relative to a mechanical relative reference to the movable optical system. It is intended to provide an optical head.

(Means for Solving the Problems) For this reason, according to the present invention, an optical head frame having a pair of guide shafts in the radial direction of the optical disk is provided with a fixed optical device such as a light source for irradiating the optical disk surface and a sensor for receiving a reflected light beam. And an objective lens for guiding a light beam from the fixed optical system to the optical disk surface via an optical path parallel to the guide axis and guiding reflected light from the optical disk surface to a sensor of the fixed optical system. In an optical head configured to guide a movable optical system by the guide shaft, an optical head block for incorporating a fixed optical system into the optical head frame is integrally formed, and the optical head block formed on the optical head block is formed. The guide shaft and the optical head on the optical head frame are fixed by abutting and fixing the guide shaft on the position regulating surface of the guide shaft. In addition to regulating the relative position of the deblock, a movable optical system is incorporated in a carriage provided for the guide shaft with reference to the guide shaft.

(Operation) As described above, when the guide shaft is mounted on the optical head frame, the relative position between the guide shaft and the fixed optical system is regulated. On the other hand, since the movable optical system on the carriage is incorporated with reference to the guide shaft, the assembling process is performed. Thus, the optical axes of the fixed optical system and the movable optical system are naturally aligned, and the parallelism between the guide axis and the optical axis can be structurally ensured.

(Example) Hereinafter, an example of the present invention will be specifically described with reference to FIG. The same parts as those in the description of the conventional example are denoted by the same reference numerals, and description thereof will be omitted. Here, an optical head block 21 for incorporating a fixed optical system
Is formed integrally with the optical head frame 20 during molding. Each mounting portion of the semiconductor laser 2, the collimator lens 3, the polarizing beam splitter 4, the sensor lens 7, the cylindrical lens 8, and the sensor 9 is formed with strict dimensions. Can be configured. The optical head block 21 includes a semiconductor laser 2, a collimator lens 3,
Position regulating surfaces 21a, 21a 'of the guide shafts 13, 13 are formed so as to sandwich the optical axis passing through the polarizing beam splitter 4, and each end of the guide shafts 13, 13 is brought into contact with the mounting piece 22, By fixing 22 to the optical head frame 20 with screws 23, 23,
The parallelism between the optical axis and the guide shafts 13, 13 can be ensured. A movable optical system, that is, a bending mirror 5 and an objective lens 6, are set on the carriage 12 guided by the guide shafts 13, 13 with dimensions set based on the guide shafts 13, 13. For this purpose, the guide shaft
The guide holes 12a for the holes 13 and 13 are accurately formed in the carriage 12 based on the parallelism with the optical axis.

Therefore, the parallelism between the optical axis and the guide axis in the fixed optical system can be completely ensured in the directions of the arrows A and B (in the direction of the arrow B, the parallelism with the optical axis is maintained on the upper surface of the optical head frame 20). If so, it will naturally be aligned with the optical axis during assembly). If the movable optical system is correctly assembled to the carriage 12, the parallelism between the optical axis and the guide axis of the movable optical system can be naturally ensured by assembling the carriage 12 and the guide shaft. Optical axis alignment can be realized by itself, eliminating the need for complicated adjustments as in the prior art.

(Effects of the Invention) Since the present invention has been described in detail above, a fixed optical system in an optical head block integrated with an optical head frame with reference to a guide shaft for guiding a carriage incorporating a movable optical system. The optical axis can be positioned by itself during the assembling process, and there is no time loss in optical axis alignment, and the operation can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is a configuration diagram of an optical system for explaining a conventional example, FIG. 3 is a perspective view of a conventional example, and FIGS. It is a related position figure which expressed a problem of position gap in a drawing. 4 ... Polarizing beam splitter, 5 ... Bending mirror, 11 ...
… Actuator, 12 …… carriage, 12a …… guide hole, 1
3 ... guide shaft, 20 ... optical head frame, 21 ... optical head block, 21a, 21a '... position regulating surface, 22 ...
Mounting piece, 23 ... Mounting screw.

Claims (1)

(57) [Claims] An optical head frame provided with a pair of guide shafts in a radial direction of an optical disk is provided with a fixed optical system such as a light source for irradiating the optical disk surface and a sensor for receiving a reflected light beam, and is provided in parallel with the guide axis. A movable optical system such as an objective lens for guiding a light flux from the fixed optical system to the optical disk surface via an optical path and guiding reflected light from the optical disk surface to a sensor of the fixed optical system is guided by the guide shaft. In the optical head configured as described above, an optical head block for incorporating a fixed optical system in the optical head frame is integrally formed, and the guide shaft is formed on a position regulating surface of the guide shaft formed in the optical head block. By abutting and fixing, while regulating the relative position of the guide shaft and the optical head block on the optical head frame, An optical head to a carriage provided for serial guide shaft is characterized in that the movable optical system is incorporated as a reference the guide shaft.