JPH0718010Y2 - Optical pickup device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an optical pickup device that can be used in an optical disk device, a magneto-optical disk device, or the like.

(Prior Art) In an optical pickup device, it is necessary to accurately arrange three-dimensionally optical elements such as a semiconductor laser, a prism, and a collimator lens. Conventionally, a frame is used to accurately position and fix these optical elements, but each optical element has a unique shape and mounting posture, so that the frame has a complicated shape. Therefore, conventionally, the frame is made by integral molding such as die casting or resin molding.

(Problems to be solved by the invention) According to the conventional optical pickup device, since the frame is integrally molded, the frame may be distorted due to uneven thickness or local difference in shape during molding. Occurs, which lowers the positioning accuracy of the optical element required for the optical pickup device. Although the optical element is generally fixed to the frame by adhesion, if the frame is distorted, the optical element is distorted and optical aberration is easily generated. Making the frame a solid structure to prevent distortion is a bottleneck to miniaturization.

The present invention has been made in order to solve such a conventional problem, and by stacking a frame for fixing optical elements on a substrate made of a cold-rolled plate for maintaining accuracy, it is possible to maintain high accuracy and reduce size. It is an object of the present invention to provide a highly reliable optical pickup device.

(Means for Solving Problems) According to the present invention, a frame is constituted by a substrate made of a cold rolled plate and a fixed support frame made of a molded product and fixedly supported on the substrate. The movable support frame that holds the objective lens is positioned on the fixed support frame that is integrally formed with the mounting parts of all the optical elements that are fixed to the frame, such as the light receiving element. Characteristically, the objective lens that is controllably supported and movable with respect to the frame is supported by the substrate that is a cold-rolled plate, and all the optical elements that are fixed with respect to the frame are attached to the fixed frame. And

(Operation) A frame is composed of a substrate made of a cold rolled plate and a fixed support frame made of a molded product. Excluding the objective lens,
All the optical elements to be fixed to the frame, such as the semiconductor laser, the beam splitter, and the light receiving element, are attached to the optical element attaching portion formed on the fixed support frame. The fixed support frame is accurately fixed and supported by a substrate made of a cold-rolled plate that is homogeneous, has high strength, and has high rigidity. The objective lens is supported by a substrate made of a cold rolled plate through a movable supporting frame in a position controllable manner, and is used for tracking and focusing.

(Example) Hereinafter, an example of an optical pickup device according to the present invention will be described with reference to the drawings.

In FIGS. 1 to 5, reference numeral 30 indicates a fixed support frame for fixing the optical element, and the fixed support frame 30 is made by integral molding such as die casting or resin molding. Opening grooves 34, 38, 40 and an open portion 36 are formed on the bottom surface side of the fixed support frame 30 (see FIG. 5). Each of the open grooves 34, 38, 40 is provided with the open portion 36 at the center.
And the open grooves 34, 38 and the open grooves 38, 40 form an angle of 90 degrees with each other. A hole 32 communicating with the open groove 34 is formed from one side of the fixed support frame 30, and the semiconductor laser 10 is fitted into the hole 32. The diffraction grating 16 held by the holder 18 is provided in the open groove 34.
Is fitted. A semiconductor laser 10 is provided in the opening 36.
A beam splitter 12 for splitting the laser light from is fixed obliquely. An inclined surface 42 communicating with the open groove 38 is formed at the outer end of the fixed support frame 30.
A mirror 26 for fixing the laser beam split by the beam splitter 12 to an objective lens described later is fixed to 42.
A holder 22 holding a sensor lens 20 which is a concave lens is fitted in the open groove 40. On the outer end surface of the fixed support frame 30, a light receiving element 14 that receives the laser light that has passed through the lens 20 is fixed by a holder 24. The bottom surface side of the fixed support frame 30 is placed on the substrate 46, and is fixed to the substrate 46 by screwing with the bottom surface as an attachment reference surface. As a result, the fixed support frame 30 has its open surface covered with the substrate 46 and is fixed in a hermetically sealed manner.

The substrate 46 and the fixed support frame 30 form a frame. In other words, the frame is divided into the substrate 46 and the fixed support frame 30.

The substrate 46 is made of a cold-rolled plate that is homogeneous, has high strength, and has high rigidity. A steel plate, aluminum, brass or the like can be used as the material. A fixed support frame 30 is provided on the substrate 46.
Bearing 48 is fixed to the side of the mounting part of
A shaft 50 is fitted in the bearing 48. A movable support frame 52 is fitted on the upper end of the shaft 50 so as to be movable and rotatable in the axial direction. An objective lens 54 and a balance weight 56 are fitted to the movable support frame 52 with a shaft 50 interposed therebetween, and a pair of focusing lenses with a shaft 50 sandwiched between them on a line orthogonal to the line connecting these lenses 54 and the balance weight 56. The coils 58, 58 are fixed. These coils 58,58
A set of two tracking coils 60, 60 is fixed to each of them. The objective lens 54 is located above the mirror 26.

Thus, except for the objective lens 54, all the optical elements to be fixed to the frame, such as the semiconductor laser 10, the beam splitter 12, the light receiving element 14, etc., are attached to the optical element attachment portion formed in the fixed support frame 30, and Fixed support frame
30 is a substrate made of a cold rolled plate that constitutes the frame
It is fixed at 46. On the other hand, the objective lens 54 is axially attached to the substrate 46 made of a cold rolled plate via the movable supporting frame 52.
It is supported so as to be movable in 50 directions and rotatable about an axis 50.

Two pairs of horseshoe-shaped cores 62, 62 are fixed on both sides of the board 46, and one of the pair of magnetic pole pieces of each core 62, 62 rising upward has a permanent magnet 64, 64 is stuck. One pole piece of each core 62, 62 advances into the focusing coils 58, 58, and each core 62, 62
One side of the coils 58, 58 and the coils 60, 60 are sandwiched by a pair of magnetic pole pieces 62. Therefore, the coils 58,58
Focusing control can be performed by moving the objective lens block 52 in the optical axis direction of the objective lens 54 by controlling the energization of the objective lens 54. Tracking control can be performed by rotating it around. The components including the block 52, the objective lens 54, the coils 58 and 60, the permanent magnets 64 and 64, etc. constitute an actuator for performing focusing and tracking, and a cover 80 is covered on this actuator portion. The cover 80 is formed with a window hole 82 for passing light from the objective lens 54.

A bearing portion that engages with the guide shaft 78 is provided at one end of the substrate 46.
66 is formed. Further, a bent portion 47 for screwing the bearing member 68 is formed on the other end of the substrate 46. The bearing member 68 has bearing portions 70, 70 at both ends.
The bearings 70, 70 are penetrated by another guide shaft (not shown) parallel to the guide shaft 78. The substrate 46 can be moved by being guided by these guide shafts, whereby the entire optical pickup device is moved in a direction traversing a recording track of a disc (not shown).

Another bearing member 72 can be screwed to the bottom surface of the substrate 46. Bent portions are formed at both ends of the bearing member 72, and bearing portions 74 and 76 are formed at the bent portions, respectively. The bearings 74 and 76 are penetrated by a guide shaft similar to the guide shaft 78. The substrate 46 can be moved by being guided by these guide shafts, so that the entire optical pickup device can be moved in the direction traversing the recording track of the disc.

The two bearing members 68 and 72 are selectively used. For example, when a thin type is required such as a portable optical disk device, the bearing member 68 is used, and the thin type is not required.
The bearing member 72 is used when it is required to prevent the spread in the front-rear and left-right directions.

The laser light emitted from the semiconductor laser 10 is a diffraction grating.
After passing through 16, a part is bent at a right angle by the beam splitter 12, further bent at a right angle by a mirror 26, passes through an objective lens 54, and is converged on a recording track of a disc (not shown). The light reflected by the disk passes through the objective lens 54, is reflected by the mirror 26, passes through the beam splitter 12, passes through the sensor lens 20, and is received by the light receiving element 14. As is well known, a focus signal and a track signal can be obtained from the light receiving element 14 in addition to the information signal recorded on the disc, and the reading signal is also used for focusing control and tracking control.

According to the above-described embodiment, the frame of the optical pickup is not integrally formed as a single frame but is divided into the fixed support frame 30 for holding the optical element and the substrate 46 made of a cold rolled plate, and the objective lens is used. Except for 54, the frame structure is formed by stacking the reference surface of the fixed support frame 30 on which all the optical elements to be fixed to the frame are attached to the substrate 46, so that a cold rolling plate of uniform, high strength and high rigidity. Since the board 46 made of is prevented from deforming the frame after assembling, and all the optical elements to be fixed are attached to one common component, the fixed support frame 30, it is extremely easy to position each optical element. Moreover, the accumulation of assembly errors is eliminated, and stable optical characteristics with little aberration can be obtained. Also, a substrate made of cold rolled plate
By using 46 together, the thickness of the fixed support frame 30 can be made thin, and the size and weight can be reduced. Further, since the movable support frame 52 holding the objective lens 54 is also supported by the substrate 46 which is a cold rolled plate of uniform, high strength and high rigidity,
The relative positional relationship between the fixed optical element attached to the fixed support frame 30 and the objective lens 54 is maintained with high accuracy, and stable focusing control and racking control are possible.

Some optical elements need to be adjusted after being assembled in the support frame. Such a thing may be elastically movably attached via, for example, a leaf spring. Moreover, adjustment may be performed by forming an adjustment hole in the support frame or the substrate. Even when the adjustment hole is formed, this does not impair the above-described effects of the present invention.

(Effects of the Invention) According to the present invention, the frame of the optical pickup is not integrally formed as one frame but is divided into a fixed support frame for holding the optical element and a substrate made of a cold rolled plate. Except for the objective lens, the frame structure was constructed by stacking a fixed support frame on which all the optical elements to be fixed to the frame were attached to the substrate. Since the deformation of the frame after assembly is prevented and all the optical elements to be fixed are attached to one common part called the fixed support frame, it is extremely easy to position each optical element and there is no error in assembly. It is possible to obtain stable optical characteristics with a small amount of aberration. Also,
The thickness of the fixed support frame can be thinned by using the cold-rolled plate together, and the size and weight can be reduced.
Further, since the movable support frame holding the objective lens is also supported by the substrate made of a cold rolled plate of uniform, high strength and high rigidity, the fixed optical element mounted on the fixed support frame and the objective lens are The relative positional relationship is maintained accurately and stable focusing control and tracking control are possible.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of an optical pickup device according to the present invention, FIG. 2 is a plan view of the same embodiment, FIG. 3 is a side sectional view of the same, and FIG. 4 is a line in FIG. A sectional view taken along the line IV-IV and FIG. 5 are bottom views of the support frame in the above embodiment. 10 …… Semiconductor laser, 12 …… Beam splitter, 14 ……
Light receiving element, 30 ... Fixed support frame, 46 ... Substrate, 52 ...
… Movable support frame, 54… Objective lens.

Claims (1)

[Scope of utility model registration request] 1. A frame is composed of a substrate made of a cold rolled plate and a fixed support frame made of a molded product and fixedly supported on the substrate, and fixed to the frame such as a semiconductor laser, a beam splitter, a light receiving element and the like. The mounting portions of all the optical elements are formed integrally with the fixed support frame, and the substrate made of cold rolled plate that constitutes the frame is
A movable supporting frame holding an objective lens is supported in a position controllable manner, and the objective lens movable with respect to the frame is supported by a substrate made of the cold rolling plate, and all optical elements fixed with respect to the frame are supported. Is an optical pickup device mounted on the fixed frame.