JPS60205835A - Optical head - Google Patents

Abstract

PURPOSE:To attain easy and accurate control so that a focus error signal is set at 0 in a focused state by securing such constitution where a bushing that supports a 4-split optical sensor can move toward an optical axis within a boss by means of a control screw. CONSTITUTION:The light of a light source 1 is irradiated on a recording medium 4 via an objective lens 3, and this reflected light is received by a 4-split optical sensor 7. A bushing 13 that supports the sensor 7 is put into a boss 14 and can move toward an optical axis. A control screw 20 is turned while a focus error signal VF sent from the sensor 7 is observed, and the optical axis position of the sensor 7 is controlled so that the signal VF is set at 0 in a focused state. Then said optical axis position is fixed by driving a screw 18. Thus the position of the sensor 7 can be controlled easily and accurately.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an optical head for an optical information recording medium such as an optical disk, and more specifically, to a position in the optical axis direction of a four-split optical sensor that receives reflected light from the recording medium. The present invention relates to an optical head equipped with a mechanism for adjusting.

[Prior Art] FIG. 1 is a sectional view showing an example of a conventional optical head used in an optical recording/reproducing device. In this figure, light emitted from a semiconductor laser 1 is converted into a parallel beam by a collimator lens 2, and recorded by an objective lens 3.
A minute spot is irradiated onto the medium 4. The reflected light from the recording medium 4 is transmitted through the objective lens 3. It passes through a collimator lens 2, is directed by an optical isolator 5, passes through a cylindrical lens 6, and is focused on a quadrant optical pin I7.

FIG. 2 shows the shape of the optical image focused on the 4-split optical lens, and this shape changes depending on the distance between the recording medium 4 and the objective lens 3.

If the recording medium 4 and the recording medium 3 are too far apart, (9) is too close, (c)
indicate the in-focus state.

FIG. 3 is an explanatory diagram of the diagonal differential outputs of the four-split optical sensor 7. Here, the solid line is the case when the optical system is ideally configured, and at the in-focus position, the focus error signal V
F becomes zero. The broken line indicates a case where the constants of the optical system (for example, the focal length of a lens, the distance between lenses, etc.) are not configured as designed values, and the focus error signal VF does not become zero at the in-focus position.

In the conventional optical head shown in FIG. 1, in order to adjust the focus error signal VF to zero at the in-focus position, the bodies 9 and 1 to 8 supporting the optical sensor 7 are connected. The thickness is adjusted by interposing a spacer 10 or the like with an appropriate thickness between them. Note that 11 is a set screw.

However, a head with such a configuration has the drawback that it is difficult to perform accurate adjustment, and the adjustment itself is extremely complicated.

[Object of the Invention] The present invention has been made in view of the above problems, and its object is to provide an optical sensor that can easily and accurately adjust iuJ so that the focus error signal becomes zero in the focused state. The object of the present invention is to realize an optical head having a position adjustment mechanism.

[Structure of the Invention] The present invention achieves this object by providing an optical head that irradiates light from a light source through an objective lens onto an optical recording medium and receives reflected light from the recording medium with a four-split optical sensor. , a bushing that supports and fixes the four-split optical sensor and has a longitudinal end in the optical axis direction of the optical sensor on the outside, and a boss into which the bushing is inserted so as to be movable in the optical axis direction of the optical sensor. , a screw that fits into the boss and whose tip end engages with the groove of the bushing, and an adjustment screw that moves the bushing in the optical axis direction of the optical sensor.

[Embodiment 1] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 4 is a sectional view showing a tenth embodiment of the optical head according to the present invention. In this figure, parts corresponding to those of the apparatus shown in FIG. 1 are denoted by the same reference numerals. Reference numeral 12 denotes an optical sensor position adjustment mechanism, which is a feature of the present invention, and is attached to the body 9. In this mechanism 12, 7 is a 4-split optical sensor that receives the light that has passed through the cylindrical lens 6, 13 is a bushing that supports and fixes the 4-split optical sensor 7, and 14 is a bushing 13 that is aligned in the optical axis direction of the optical sensor 7. This boss is inserted with a loose fit so that it can be moved.

FIG. 5 is a sectional view of the bushing 13 and the boss 14. As shown in this cross-sectional view, the bushing 13 is provided with a screw hole 15 on its central axis (in the optical axis direction of the hinge 7), and has a screw hole 15 on the outside in contact with the boss 14. is provided. In the groove 16, a leaf spring 1 is inserted.
7 is inserted, and this leaf spring 17 presses the bushing 13 against the boss 14 to prevent backlash due to the gap between the bushing 13 and the boss 14. Reference numeral 18 denotes a screw that fits into the boss 14, the tip of which is fitted into the groove 16, so that the bushing 13 does not move in the circumferential direction but moves linearly in the optical axis direction. Note that a hole is provided in the center of the leaf spring 17, into which the tip of the screw 18 is inserted to determine the position between the two. Also, by tightening the screw 18, the bushing 13 can be attached to the boss 1.
It is fixed to 4.

Returning to FIG. 4, 19 is an outer frame that covers the end surface of the boss 14;
0 is an adjustment screw fitted into the outer frame 19, and the tip of this adjustment screw 20 is screwed into a screw hole 15 provided in the bushing 13. Therefore, by turning the adjustment screw 20 71, the position of the bushing 13, that is, the 4-split optical sensor 7, in the optical axis direction can be adjusted. In addition, the outer frame 19
And the adjustment screw 20 can be removed after position adjustment.

In the optical head 43 constructed in this way, the position adjustment of the optical hinge is performed as follows.

(I) Insert the adjustment screw 20 into the screw hole 15 of the bushing '13.
Screw into.

(It) Fix the outer frame 19 of the adjustment screw 20 to the boss 14.

<m> Loosen the screw 18.

(IV) While observing the focus error signal VF from the 4-split optical sensor 7, turn the adjustment screw 20 and adjust the position of the 4-split optical sensor 7 in the optical axis direction so that the focus error signal becomes zero in the focused state. Adjust.

(V) Tighten the screw 18 to fix the position of the 4-split optical sensor 7 in the optical axis direction.

(After adjusting Vl, remove the il!l setting screw 20 and outer frame 19.

[Effects of the Invention] As explained above, according to the present invention, it is possible to realize an optical head that can accurately and easily adjust the position of the 4-split optical sensor to an appropriate position.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an example of a conventional device, and Fig. 2 is a sectional view showing an example of a conventional device.
FIG. 3 is an explanatory diagram of the shape of the optical image on the divided optical sensor, FIG. 3 is an explanatory diagram of the focus error signal from the four-divided optical sensor, FIG. 4 is a cross-sectional view of the structure of an example of the optical head according to the present invention, and FIG. is the fourth
FIG. 2 is an enlarged cross-sectional view of main parts of the bushing and boss in the figure. 1...Semiconductor laser 3...Objective lens 4...Recording medium 7...Four division light pin 13...Bushing 14...Boss 15...Screw hole 16...Full 18 ...screw 2o...adjustment screw CO:

Claims (1)

[Claims] In an optical head that irradiates light from a light source onto an optical recording medium via an objective lens and receives reflected light from the recording medium with a 4-split optical sensor, the 4-split optical sensor is supported and the optical head is placed outside. a bushing having a longitudinal groove in the optical axis direction of the sensor; a boss into which the bushing is inserted so as to be movable in the optical axis direction of the optical sensor; An optical head comprising: a screw that engages with the bushing; and an adjustment screw that moves the bushing in the optical axis direction of the optical sensor.