JPH117651A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve position accuracy of each parts and to reduce the number of parts by forming a part at least opposing to a laser chip of a laser cap of hologram with a transparent synthetic resin material and forming hologram at a transparent part of a cap. SOLUTION: A hologram laser 3 is constituted so that a chip pedestal 11 on which a laser chip 9 and a photodiode are mounted is mounted on the prescribed position of a printed board 2 and a hologram element 12 is mounted on the prescribed position of the printed board 2 so as to cover the chip pedestal 11. The hologram element 12 is made of transparent synthetic resin, and diffraction grating 14 is formed at the inside plane of one side plane of a cap body 13 of a small box type of which the lower plane is made open and a hologram 15 is formed at the outside plane. Thereby, positioning between the hologram 15 and the cap body 13 is not required, position accuracy between the hologram 15 and the cap body 13 can be improved, the number of parts can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for reducing the number of components and improving the positional accuracy between components in an optical pickup device using a hologram laser.

[0002]

2. Description of the Related Art In recent years, a hologram laser has been employed in response to a demand for miniaturization of an optical pickup device. In such a hologram laser, a hologram is arranged in front of a laser chip, a return light condensed by a collimator lens is input, and the diffracted light is condensed on a photodiode for signal detection, whereby an RF signal and a focus error signal , A tracking error signal and the like.

FIGS. 3 and 4 schematically show an optical pickup using a conventional hologram.

The optical pickup device a includes a hologram laser b having a light receiving portion for oscillating a laser beam and receiving a return light thereof, a collimating lens c disposed in front of the hologram laser b in the emission direction, and It has a prism mirror d for bending the optical axis of the laser light at a substantially right angle, and an objective lens f for condensing the laser light on the signal surface of the optical disk e. The objective lens f is supported by a biaxial actuator (not shown).

The hologram laser b has a chip base (L) on which a laser chip g and a photodiode h are mounted.
Also called OP (Laser on photodetector). ) I, a stem j for supporting the chip base i, a cap k made of a metal material and having a bottomed cylindrical shape and attached to the stem j so as to cover the chip base i; And a hologram element m attached to the cap k so as to cover the through hole 1 formed in the hologram element m.

The hologram element m has a diffraction grating o formed on a surface of the small plate n made of synthetic resin facing the laser chip g, and a hologram formed on a surface opposite to the surface on which the diffraction grating o is formed. p is formed. Such a hologram laser b is generally called a can-type hologram laser.

The laser beam emitted from the laser chip g passes through the through hole 1 of the cap k and forms three beams for generating a signal for tracking servo by the diffraction grating o. The laser beam is emitted from the hologram laser b through m. And
The laser light emitted from the hologram laser b passes through a collimator lens c, is bent at a substantially right angle by a prism mirror d, and is then focused on a signal surface of an optical disk e by an objective lens f.

The return light reflected by the optical disk e travels in the above-mentioned optical path in the opposite direction, and the diffracted light diffracted by the hologram p is condensed on the photodiode h to generate various signals.

[0009]

However, in the above-described conventional optical pickup device a, it is difficult to improve the positional accuracy between the laser chip g, the photodiode h and the hologram element m, There was a problem that the score was high.

That is, the laser chip g and the hologram p
First, the chip base i on which the laser chip g is mounted is positioned with respect to the stem j, the hologram element m is positioned with respect to the cap k, and the cap k is mounted on the stem j with respect to the stem j. Since the stem j and the cap k are interposed between the chip base i and the hologram element m, it is difficult to increase the positional accuracy between the chip base i and the hologram element m, Accordingly, the number of parts is increased, and assembling workability and the number of assembling steps are increased.

Accordingly, an object of the present invention is to improve the positional accuracy of each component and reduce the number of components.

[0012]

In order to solve the above-mentioned problems, an optical pickup device according to the present invention comprises a hologram laser cap formed of a synthetic resin material having at least a portion opposed to a laser chip. A hologram is formed on a transparent portion of the cap.

Therefore, since the hologram is formed on the cap when forming the hologram laser, there is no need to position the hologram element with respect to the cap as in the prior art, and the positional accuracy of both can be increased accordingly. In addition, the number of components can be reduced as compared with the related art, whereby the workability of assembling the optical pickup device can be improved and the number of assembling steps can be reduced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the optical pickup device of the present invention will be described below with reference to the accompanying drawings.

In the embodiment shown in the drawings, the present invention is applied to an optical pickup device for a mini disk (MD). Further, the main part of the present invention resides in the hologram laser, and the other parts of the optical pickup device are the same as those described in the above conventional example. Therefore, the hologram laser which is the main part will be mainly described.

FIGS. 1 and 2 show an optical pickup device 1.
FIG. 1 is a schematic view showing the entire structure of an optical pickup device 1 including a printed circuit board 2 serving as a base member, a hologram laser 3 disposed on the printed circuit board 2, and an emission direction of the laser light of the hologram laser 3. A collimating lens 4 disposed in front; a prism mirror 5 for bending the optical axis of the laser light at a substantially right angle; and an objective lens 7 for condensing the laser light on the optical disk 6
And a shaft actuator 8.

The optical pickup device 1 has the above-mentioned objective lens 7 by a thread mechanism (not shown).
Are arranged to move in the radial direction of the optical disk 6.

The hologram laser 3 includes a chip base 1 on which a laser chip 9 and a photodiode 10 are mounted.
1 and a hologram element 12 positioned so as to cover the chip base 11, and the hologram element 12 is formed on one side surface of a cap box 13 made of transparent synthetic resin and having a small box shape with an open lower surface. A diffraction grating 14 is formed on the inner surface, and a hologram 15 is formed on the outer surface. As a result, the hologram 15 is formed integrally with the cap body 13, so that the hologram 15 and the cap body 1 are formed.
Positioning with the position 3 becomes unnecessary.

The hologram element 12 is formed such that its internal space is slightly larger than the chip base 11, and covers the chip base 11 mounted at a predetermined position on the printed circuit board 2 from above. Is mounted on the printed circuit board 2 to form the hologram laser 3.

The hologram element 12 mounted on the printed board 2 is positioned such that its diffraction grating 14 faces the laser chip 9 on the chip base 11.

Since the hologram element 12 and the laser chip 9 are respectively mounted on the same printed circuit board 2, the hologram element 12 and the laser chip 9 are compared with the can-type hologram laser b shown as the conventional example. 9 can be improved. Also, the hologram element 12 has an internal space that is only slightly larger than the chip base 11, so that the hologram element 12 is smaller than the can-type hologram laser b shown in the above-described conventional example, and in particular, is orthogonal to the laser optical axis. The size in the direction can be reduced.

Collimator lens 4 and prism mirror 5
Are disposed on the printed circuit board 2 in that order in front of the hologram laser 3 in the emission direction.

The biaxial actuator 8 is connected to the printed circuit board 2
The objective lens 7 is movably supported in two directions (a focusing direction and a tracking direction) via a suspension 17 on a supporting portion 16 supported by the camera. , To move.

As a result, the hologram laser 3, the collimating lens 4, the prism mirror 5, and the support portion 16 of the biaxial actuator 8 are mounted or supported on one printed circuit board 2, thereby improving the positional accuracy between the components. And the size of the hologram laser 3 can be reduced as described above.
The overall thickness can be reduced.

These parts (hologram laser 3,
Since the base member on which the collimator lens 4, the prism mirror 5, and the support portion 16) of the biaxial actuator 8 are mounted or supported is the printed circuit board 2, the number of components can be reduced without preparing a separate component serving as the base member. The wiring to the hologram laser 3 and the biaxial actuator 8 can be performed through a printed circuit board, and there is no need to perform separate wiring.

In the optical pickup device 1, the can-type hologram laser b shown in the conventional example can be used.
The laser light emitted from the laser chip 9 passes through the collimator lens 4, the prism mirror 5, and the objective lens 7 in the same manner as the optical pickup device a using
Is condensed on the signal surface. The return light travels in the opposite direction in the optical path, is diffracted by the hologram 15, and the diffracted light is condensed on the photodiode 10 to generate various signals.

In the above embodiment, the case where various signals are generated by the photodiode 10 of the hologram laser 3 has been described. However, the optical pickup device of the present invention is not limited to this. 5 and a polarizing beam splitter (a polarizing beam splitter PBS, a Wollaston prism, etc.) are arranged, and the return light separated by this is focused on a predetermined light receiving element (RF light receiving element, APC light receiving element, etc.). Then, a predetermined signal may be extracted.

[0028]

As is apparent from the above description, according to the optical pickup device of the present invention, the cap of the hologram laser is made of a synthetic resin material in which at least the portion facing the laser chip is transparent. Since the hologram is formed directly on the transparent portion of the cap, the positioning of the hologram and the cap is not required, and the positional accuracy between the two can be improved, and the number of parts is smaller than in the past. can do.

According to the optical pickup apparatus of the present invention, since the laser chip and the cap mounted on the chip base of the hologram laser are provided on one base member, the positional accuracy between the hologram and the laser chip is improved. Can be further increased, and the number of parts can be reduced as compared with the related art.

According to the optical pickup device of the present invention, the base member on which the hologram laser is mounted has the collimating lens, the rising mirror for bending the optical axis of the laser beam at a substantially right angle, and the support of the biaxial actuator. Since the parts are provided, the positional accuracy between the components can be improved, and the size of the entire optical pickup device can be reduced.

According to the optical pickup device of the present invention, since the base member is a printed board, another member is not required as the base member, and the hologram laser and the two-axis actuator are not required. Wiring can be performed through a printed circuit board, and there is no need to separately perform wiring.

It should be noted that the specific shapes and structures of the optical pickup device described in the above embodiments are merely examples for embodying the present invention, and the technical scope of the present invention is not limited thereto. Must not be interpreted restrictively.

[Brief description of the drawings]

FIG. 1 schematically shows an embodiment of the optical pickup device of the present invention together with FIG. 2, and FIG. 1 is a plan view.

FIG. 2 is a side view.

FIG. 3 schematically shows an example of a conventional optical pickup device together with FIG. 4, and FIG. 3 is a plan view.

FIG. 4 is a side view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical pick-up apparatus, 2 ... Printed circuit board (base member), 3 ... Hologram laser, 4 ... Collimating lens, 5 ... Prism mirror, 8 ... Biaxial actuator, 9
... Laser chip, 11 ... Chip base, 13 ... Cap body (cap), 15 ... Hologram, 16 ... Support part

Claims (5)

[Claims] 1. An optical pickup device using a hologram laser, wherein the hologram laser has at least a chip base on which a laser chip is mounted, and at least a part which covers the chip base and is opposed to the laser chip. An optical pickup device comprising: a cap formed of a synthetic resin material; and a hologram formed on a transparent portion of the cap. 2. The optical pickup device according to claim 1, wherein the chip base and the cap are provided on one base member. 3. A base member on which a hologram laser is mounted is provided with a collimating lens, a rising mirror for bending an optical axis of a laser beam at a substantially right angle, and a support portion for a two-axis actuator. An optical pickup device according to item 1. 4. The optical pickup device according to claim 2, wherein the base member is a printed circuit board. 5. The optical pickup device according to claim 3, wherein the base member is a printed circuit board.