JPH052123B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to optical information processing devices such as optical pickup devices, and particularly to improving the accuracy of optical components of the devices.

[Conventional technology]

FIG. 5 is a schematic diagram showing a conventional optical pickup device.

In the figure, 51 is the main body of the optical pickup device, 52 is an optical disk as an optical information medium, and 53
54 is a laser diode, 54 is a diffraction grating that separates the laser light from the laser diode 53 into a plurality of light beams, and 55 is a light separator that separates the light from the diffraction grating 54 into a pair of reflected light and transmitted light. a half prism, 56 is a collimating lens that converts the transmitted light from this half prism 55 into a parallel beam, 57 is a total reflection mirror that bends the parallel beam from this collimating lens 56 at right angles, and 58 is a parallel beam from this total reflection mirror. Light flux to optical disk 5
This is an objective lens that condenses light as a spot S onto a pit (not shown) formed at 2.

The reflected light (return light) from the spot S is transmitted through the objective lens 58 → total reflection mirror 57 → collimating lens 5
6, the light is projected onto a half prism 55, and the half prism 55 further separates a pair of reflected lights into transmitted lights. In this example reflected light is used. 5
9 is a spherical lens into which this reflected light enters; 60 is a cylindrical lens that converges the light from this spherical lens 59 in one direction; and 61 is a light detection device consisting of a six-part element that receives the converged light from this cylindrical lens 60. It is a vessel.

FIG. 6 is an exploded perspective view showing the detailed structure of a sensor lens consisting of a spherical lens 59 and a cylindrical lens 60 as an optical component for processing the return light from the optical disk 52. In the figure, 63 is a holder that holds each lens 59, 60, and the upper part of the cylindrical body is notched corresponding to the shape of each lens. The side surface 62 formed substantially parallel to the holder 63 is aligned with the reference surface 64 of the holder 63, and the spherical lens 59 is mounted thereon to assemble.

The operation of the optical pickup device assembled in this manner will be described below with reference to FIGS. 7 to 9. The photodetector 61 shown in FIGS. 7 and 8 consists of four elements A, B, C, and D divided into four parts in the shape of a square in the center, and two elements E and F arranged on both sides of the four elements A, B, C, and D. Consists of elements. The return light from the optical disk 52 passes through a spherical lens 59 and a cylindrical lens 60 and is projected onto a photodetector 61. Among the light beams diffracted by the diffraction grating 54, this return light is of the 0th order, which has the strongest intensity. Light P and ±1st order light Q1, Q on both sides of it
2, the 0th-order light P is at the center of elements A, B, C, and D of the photodetector 61, and the 0th-order light P is at the center of elements A, B, C, and
Each component is arranged at a geometrically fixed position so that the ±1st-order lights Q1 and Q2 are focused on F, respectively.

The 0th order light P is detected by the photodetector 6 when the spot S is focused with high precision on a pit (not shown) of the disk 52.
The positions of the spherical lens 59 and the cylindrical lens 60 are adjusted in the optical axis direction so that each of the elements A, B, C, and D of 1 forms a perfect circle at the center. FIG. 7 shows the state at this time, and in this state, the output relationship from the photodetector 61 is as shown in equation (1).

I=(A+C)-(B+D)=0...(1) Here, when the distance between the disk 52 and the objective lens 58 changes, depending on the direction, the 0th order light P as shown in FIG. , ±1st-order lights Q1 and Q2 are deformed into elliptical shapes in directions having angles of 90° with respect to the base line M in the 45° direction. The state at this time is expressed by the output relationship from the photodetector 61 as shown in equations (2) and (3).

I = (A + C) - (B + D) > 0 ... (2) I = (A + C) - (B + D) < 0 ... (3) In the state shown by formulas (2) and (3), light detection By adjusting the objective lens 58 in the direction of equation (1) using the servo mechanism (not shown) according to the output of the device 61, the signal output of equation (4) is always stably obtained in the state of equation (1). .

A+B+C+D=I ₀ ...(4) The sensitivity of the servo mechanism at this time is determined by i/x shown in Figure 9, and it is necessary for the optical pickup device to fall within a certain range. be.

[Problem that the invention seeks to solve]

By the way, in terms of structure, the conventional spherical lens 5
9 and the cylindrical lens 60 are both formed by polishing glass, resulting in an extremely excessive cost burden. Place two more parts in holder 63
It had to be assembled with high precision, and this work was also excessively costly. Furthermore, as optical pickup devices have become smaller in recent years, optical components have also been required to be smaller, and efforts have been made to integrate spherical lenses and cylindrical lenses by molding, and to reduce the outer diameter of the lenses.

However, sensor lenses that are integrated and miniaturized through molding have a highly accurate spherical shape and a highly accurate cylindrical shape for the area through which light passes, as well as uniform refraction. For example, in the area around the gate where the molding material is injected during injection molding, differences in cooling rate may cause the surface accuracy to decrease or the refractive index to be uneven. As a result, the transmitted wavefront aberration as a lens deteriorates, and the state of curve Y in FIG. 9 changes to curve N.
changes to the state of Therefore, the sensitivity is i/x→is/
x, the stability of the servo mechanism is lost, and Equation (1)
It becomes difficult to maintain a constant distance between the objective lens 58 and the disk 52 in this state. The limit of this aberration deterioration is, for example, about 0.3 μm, and when forming a sensor lens, it is necessary to minimize the aberration deterioration due to the influence of the gate in the region through which light passes.

This invention was made to solve these problems, and aims to provide an optical information processing device that does not cause deterioration in the precision of optical components and can achieve cost reduction. .

[Means for solving problems]

The optical information processing device according to the present invention includes an optical component including a light transmitting part consisting of a spherical part and a cylindrical part, and a gate part formed by molding the spherical part so as to protrude outward in the outer circumferential direction of the spherical part. A synthetic resin material is injected through the gate part so that the side surface of the collar part is approximately parallel to the generatrix of the cylindrical surface of the cylindrical part. The holding body is provided with a positioning cutout portion corresponding to the collar portion, and a positioning portion for positioning the holding body at a predetermined angle with respect to the photodetector.

[Effect]

In this invention, since the gate portion during molding corresponds to the end surface of the flange portion, the light transmitting portion is not affected by this gate portion.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view showing essential parts of an embodiment of the present invention. In the figure, 1 is a sensor lens which is an optical component integrally molded of plastic or the like, and 2 is a sensor lens of this sensor lens 1. A spherical lens is formed as a spherical part formed on one surface, and a cylindrical lens 3 is a cylindrical part formed on the other surface, and these spherical lens 2 and cylindrical lens 3 serve as a light transmitting part. Reference numeral 4 denotes a pair of flange portions formed in a convex manner on the upper part of the outer peripheral side surface of the sensor lens 1, 5 is a side surface of this flange portion as a reference portion, and cylindrical lens 3
It is formed substantially parallel to the generatrix L of the cylindrical surface. 6
is the end face of the flange portion 4 and serves as a gate portion when injection molding is performed using plastic or the like. Reference numeral 7 designates a cylindrical holder as a holder for storing the sensor lens 1, and 8 designates a pair of positioning notches formed at one end of the holder 7 to correspond to the flange 4 of the sensor lens 1. 9 forms a straight line K so as to match the plane G formed by the side surfaces 5 of the pair of collar parts 4. 10 connects this holder 7 to a detector 61
The main body 51 is tilted at a predetermined angle, for example, 45 degrees.
A groove is used as a positioning part to be attached to the holder.

FIG. 2 is a schematic configuration diagram schematically showing the main parts of this embodiment.

In the figure, reference numeral 11 denotes a fixing screw, which is screwed through a screw hole 12 formed opposite to the groove 10 of the holder 7 attached to the main body 51.

With this configuration, the generatrix L of the sensor lens 1 always maintains a constant geometrical shape with respect to the holder 7 by matching the base line G formed by the pair of flanges 4 with the base line K of the holder 7. This holder 7 can be attached to the main body 51.
Align the screw hole 12 with the groove 10 and insert the screw 11.
By fixing the detector 61 through the
The alternating angle between the base line M and the generatrix L can be maintained at 45 degrees, and since the gate part 6 is integrally molded with plastic with the flange part 4, it is compact and inexpensive, with no aberration deterioration due to the influence of the gate part 6. The sensor lens 1 can be attached to the holder 7 very easily. Also, in this example,
A convex flange 4 provided on the outer shape of the sensor lens 1
Since the side surface 5 of the cylindrical lens 3 is used as a reference part and the end face of the flange part 4 is used as a gate part 6, the outer diameter of the lens can be made extremely small by making the shape of the cylindrical lens 3 circular. 3 and 4 show other embodiments in which one flange 1 is attached to the sensor lens 21.
4, and the end face of this collar part 14 is connected to the gate part 16.
Furthermore, the side surface 15 of the flange 14 is attached to the holder 1.
It is assembled by fitting it into the positioning notch 18 of No. 7, and even in this way, a compact sensor lens without aberration deterioration can be realized. In each of the above embodiments, the convex portion having one or two reference straight portions is formed to match the direction of the generatrix L, but the present invention is not limited to this. It is sufficient if it can be specified uniformly for the holder.

〔Effect of the invention〕

As explained above, this invention uses optical components such as
a light transmitting part consisting of a spherical part and a cylindrical part;
The spherical part is formed to protrude toward the outer circumferential direction and has a flange part whose end face corresponds to the gate part during molding, and the side surface of the flange part corresponds to the cylindrical surface of the cylindrical part. The synthetic resin material is integrally molded by injecting it through the gate part so that it is approximately parallel to the generatrix, and the holding body is provided with a positioning notch corresponding to the collar part, and the holding body is By providing a positioning part that positions the photodetector at a predetermined angle, the light transmitting part is not affected by aberration deterioration caused by the gate part, so synthetic resin can be used without deteriorating the accuracy of optical parts. This has the effect of being able to be integrally molded and achieving cost reduction. Further, it becomes possible to incorporate the optical component into the holder with high precision, and the holder can be positioned at a predetermined angle with respect to the photodetector.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of essential parts of a first embodiment of the present invention, Fig. 2 is a schematic configuration diagram showing the attachment of the above embodiment to the main body, and Figs. 3 and 4 are views of other embodiments. FIG. 5 is a schematic diagram of a conventional optical pickup device, FIG. 6 is an exploded perspective view of the main portion thereof, and FIGS. 7 to 9 are diagrams for explaining the operation of the optical pickup device. 1, 21... optical component, 2, 3... light transmitting part,
2... Spherical shaped part, 3... Cylindrical shaped part, 4, 14
...Trim part, 5, 15...Side side of collar part, 6, 16...
...Gate part, 7, 17...Holding body, 8, 18...
Positioning notch, 10... Groove (positioning part),
52... Optical information medium, 61... Photodetector. In addition,
The same reference numerals are used for the same or corresponding parts in the figures.

Claims (1)

[Claims] 1. An optical component that processes the return light from the optical information medium, a holder that holds this optical component, and a light that detects the light that has passed through the optical component and controls the focusing position of the light on the optical information medium. In the optical information processing device, the optical component includes a light transmitting portion including a spherical portion and a cylindrical portion, and an end surface of the spherical portion that is formed so as to protrude outward in the outer circumferential direction of the spherical portion. and a flange portion corresponding to the gate portion, and a synthetic resin material is injected through the gate portion such that the side surface of the flange portion is approximately parallel to the generatrix of the cylindrical surface of the cylindrical portion. The holder is integrally molded by doing so, and the holder is provided with a positioning notch corresponding to the flange, and a positioning part for positioning the holder at a predetermined angle with respect to the photodetector. An optical information processing device.