JPS58114338A - Optical pickup - Google Patents

Abstract

PURPOSE:To simplify the exchange of semiconductor lasers, by unifying a semiconductor laser and a collimator lens with the interchangeability secured between them. CONSTITUTION:For a parallel beam generating parts 11, a semiconductor laser 1 and a collimator lens 3 are incorporated into a cylindrical case 12. The parts 11 is previously adjusted so that the light passed through the lens 3 is turned into parallel beams which are parallel to the optical axis of the lens 3. Then the parts 11 is put into a hole 15 of a case 10 of the pickup main body, and a positioning pin 14 is fitted at a recess part 16 and then attached removably into a screw hole 18 of the case 10 by means of a screw 17. In such a way, the laser 1 can be simply exchanged.

Description

[Detailed description of the invention] This invention relates to an optical pickup.

Optical information e-recording and reproducing devices (hereinafter referred to as optical recording and reproducing devices) using semiconductor lasers are the same as conventional iii! One of the features of this method is that both the device and the recording medium have a longer lifespan than the recording/reproducing method using the 11C head or the reproducing method using a needle.

Of these, recording media have a semi-permanent lifespan, but
The device has a limited lifespan, and that lifespan is mainly determined by the lifespan of the semiconductor laser. Furthermore, since the lifespan of these semiconductor lasers varies greatly from one device to another, it has become inevitable to replace semiconductor lasers in optical recording and reproducing devices.

Figure 1 shows an example of an optical pickup, in which the light emitted from the chip 2 of the semiconductor laser 1 is converted into parallel light 11 by the collimating lens 3, reflected upward by the polarizing beam splitter 4, and then divided into circles and quarters. The light passes through the single-wavelength plate 5 and is focused onto the signal surface of the disk 7 by the focus lens 6.

This light is further reflected on the signal surface and sent to the quarter-wave plate 5.
, passes through the polarizing beam splitter 4, and is imaged onto a photodetector 9 by a lens system 8.

The optical pickup that has been proposed conventionally is
In addition to what is shown in the figure, it is expected that a method of replacing only the semiconductor laser will not be taken, but a method of replacing the entire optical pickup will be taken. However, this method is disadvantageous in terms of cost compared to the method of replacing the semiconductor laser 1, and considering cost reduction due to mass production of the semiconductor laser 1 in the future, it is increasingly desirable to replace only the semiconductor laser 1. It comes to number 4.

In addition, when replacing the entire optical pickup, various adjustments are required depending on the position of the focus lens 6, variations in tilt, etc., so it is extremely difficult for the user to replace it himself, and it is difficult to replace it by himself. Expected to be replaced. This is uneconomical in terms of the means of transportation as well as the cost of the parts mentioned in m.

For the above reasons, it is much more advantageous to replace only the semiconductor laser l than to replace the entire optical pickup. However, the position of the chip 2 of the semiconductor laser l has some dimensional tolerance with respect to the reference plane with the outer frame of the laser l, and there is also a focal length of the collimating lens 3! Since there is a variation of 1 degree, the half-quadruple laser 1
Even if the angle is changed, it is not possible to obtain parallel rays that are symmetrical about the optical axis passing through the collimating lens 3.

That is, as shown in FIG. 2, if the chip 2 of the semiconductor laser 1 is at an angle of 9 to the optical axis of the collimating lens 3, the parallel light mF! after passing through the lens 30! However, the resulting light beam is tilted with respect to the optical axis. Further, as shown in FIG. 3, when the chip 2 is located outside the focal point of the collimating lens 3, the light after passing through the lens 3 becomes convergent light. On the other hand, if the chip 2 is located inside the focal point, the light will become scattered after passing through the lens 30.Also, even if the chip 2 is in the correct position as shown in Figure 4, the focal length of the collimating lens 3 will be long. If the focal length of lens 3 is short, the light will become a divergent light after passing through the lens 30. Therefore, the purpose of this present invention is to make it possible to achieve a diverging light without making complicated adjustments. You can simply replace the semiconductor V-Zuna,
Moreover, it is an object of the present invention to provide an optical pickup that requires fewer parts to be replaced when replacing a semiconductor radar.

An embodiment of this invention is shown in FIGS. 5 and 6. In the figure, 10 is a pickup main body case, and 11 is an optical axis-symmetrical parallel beam generating component. This parallel ray generating component 11
The semiconductor laser 1 and the collimating lens 3 are assembled in a cylindrical case 12, and adjusted in advance so that the light after passing through the collimating lens 30 becomes a parallel beam that is axially symmetrical with respect to the optical axis of the collimating lens 3. It is something. An end plate 12M is attached to one end of the cylindrical case 12, and a terminal pin 13 of the semiconductor laser 1 protrudes from the back surface of the end plate 121.

The cylindrical case 12 has a positioning pin 14 on its outer peripheral surface. The pickup body case 10 incorporates a polarizing beam splitter 4, a quarter-wave plate 5, a focus lens 6, a lens system 8, and a photodetector 9 as shown in FIG. It has a circular insertion hole 18 into which it is inserted. Insertion hole 15 skin 1i1iK
A recess 16 is provided in which the positioning pin 14 of the parallel light generating component 11 is fitted. The parallel light generating component 11 is inserted into the insertion hole l of the pickup body case 10. 5, recess 1.
and the positioning pin 14 are inserted together and removably attached to a screw hole 18 of the civic up main body case 10 with a screw 17.

In this way, the semiconductor laser 1 and the collimating lens 3 are integrated to form the parallel beam generating component 11, and are adjusted in advance. Therefore, if the entire parallel beam generating component 11 is replaced when replacing the semiconductor laser f1, it will always be possible to Parallel light beams that are symmetrical about the optical axis can be obtained, and even after the laser beam is replaced, it is possible to form a correct image on the photodetector 9. The circumferential positioning of the parallel beam generating component 11 and the pickup main body case 10 is performed by fitting the positioning protrusion 14 of the parallel beam generating component 11 into the recess 16 of the pickup main body case 10. Thereby, axially symmetrical parallel light beams having nine predetermined optical directions can be made to enter the optical system of the pickup main body case 10.

Previously, it was replaced with the replacement of the semiconductor laser l, and the 61
Since one item is only the collimating lens 3, there are fewer parts to be replaced than in the case of replacing the entire big afde, and the laser can be replaced at a low cost.

7Fg#i In place of the positioning protrusion 14 and recess 16C shown in FIG. This allows four wire connections to be made at the same time. The rest is the same as the first embodiment.

In each of the above embodiments, the positioning means was provided using the cylindrical case 12 on the outer shell of the parallel ray generating component 11, but if the outer shell of the parallel ray generating component 11 was made into a rectangular cylinder, the positioning means would be unstable. be.

As described above, in the optical big ARA 1 of the present invention, the semiconductor laser and the collimating lens are combined into a parallel beam generating component, and this combined component is replaced as a whole, so that the following effects can be obtained. . ■Since there are few parts to be replaced, lasers can be replaced at low cost. ■Can be easily replaced by the user. (2) Parallel rays that are axially symmetrical can always be incident on the optical axis of the optical system.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of a conventional optical pickup, and Figs. 2 to 4 show foreshadowing of light rays according to changes in the position of the semiconductor laser chip and changes in the focal length of the collimating lens. 5 is an exploded perspective view of one embodiment of the present invention, FIG. 6 is an explanatory diagram showing a cross section of the axisymmetric parallel ray generating component, and FIG. 7 is an exploded perspective view of another embodiment. be. DESCRIPTION OF SYMBOLS 1... Semiconductor laser, 2... Chip, 3... Collimating lens, 9... Detector, 10-... Pickup body case, -11-... Optical axis symmetrical parallel beam generating component, 12...・Cylindrical case, 15...insertion hole, 1
9°...Terminal pin, 20...Socket Figure 1 Figure 4

Claims (2)

[Claims] (1) A pickup main body case, a semiconductor laser, and a collimating lens are integrally combined, a parallel light generating part that is removably attached to the pickup main stop case and is symmetrical about the optical axis, and a part that is attached to the front pickup main body case. A nine optical system comprising a photodetector and an optical system provided in the big-up main body case to condense the light generated by the optical axis symmetrical parallel light beam generating component onto a recording medium and to direct the reflected light to the photodetector. Type pickup・ (2) The optical axis-symmetrical parallel light generating component houses the semiconductor laser described in K11l in a cylindrical case and the collimating lens, and has a terminal pin on the outside of the cylindrical case whose axial direction is parallel to this cylindrical case. MTS No. (1) of the patent claim, wherein the pickup body case has a fitting portion into which the cylindrical case of the original axially symmetrical parallel light beam generating component is fitted, and a socket into which the terminal pin is inserted. ) Optical pickup described in section.