JPH0547011A - Method for adjusting light convergence position of optical pickup and optical pickup - Google Patents

Abstract

PURPOSE:To freely adjust a flare angle of the optical flux of the incident light on an objective lens by using a collimation piezoelectric lens as a collimator lens, relating to light convergence position adjusting method of an optical pickup and the optical pickup. CONSTITUTION:The flare angle of a laser beam optical flux 2a is adjusted by a collimation piezoelectric lens which changes a refractive index by piezoelectric interaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a light focusing position in an optical pickup and an optical pickup, and in particular, by using a collimating piezoelectric lens as a collimating lens, the spread angle of a light flux of incident light on an objective lens can be increased. It relates to a new improvement for freely adjusting.

[0002]

2. Description of the Related Art Generally, as a method for adjusting a light focusing position in an optical pickup of this type which has been used conventionally,
As shown in FIG. 5, a laser beam 1a from a laser light source 1 made of a semiconductor laser passes through a fixed collimating lens 2 as a lens light beam 2a, passes through an objective lens 3, and is focused on a disc 4 made of an optical disc. Is configured to tie. Further, an actuator 7 such as a step motor is connected to the objective lens 3 via a connecting means 6, and the operation of the actuator 7 causes the objective lens 3 to reciprocate in the direction of arrow A so that the focal position is changed. It is a configuration that can be changed.

[0003]

Since the optical focusing position adjusting method and the optical pickup in the conventional optical pickup are configured as described above, there are the following problems. That is, since the objective lens is moved to adjust the focal position, an actuator having a large thrust is required to move the objective lens largely, and it is extremely difficult to miniaturize the optical pickup, for example. .. Moreover, for this reason, the exercise performance is deteriorated and the information access time is lengthened.

The present invention has been made to solve the above problems, and in particular, by using a collimating piezoelectric lens as the collimating lens, the divergence angle of the luminous flux of the incident light on the objective lens can be freely adjusted. An object of the present invention is to provide a method for adjusting a light focusing position in an optical pickup which is adjusted, and an optical pickup.

[0005]

A method for adjusting a light focusing position in an optical pickup according to the present invention is a light focusing method in an optical pickup in which a laser beam in an optical path from a laser light source is incident on a disk through an objective lens. In the position adjusting method, the divergence angle of the laser light flux is adjusted by a collimating piezoelectric lens that changes the refractive index by a piezoelectric action.

An optical pickup according to the present invention is an optical pickup in which a laser beam in an optical path from a laser light source is made incident on a disk through an objective lens, and the laser light source is placed between the objective lenses and a collimating piezoelectric lens. Is provided.

[0007]

In the optical focusing position adjusting method and the optical pickup according to the present invention, since the collimating piezoelectric lens is provided between the laser light source and the objective lens, the signal applied to the collimating piezoelectric lens is changed. As a result, the refractive index of the collimating piezoelectric lens can be arbitrarily changed. Therefore, with this collimating piezoelectric lens, the divergence angle of the laser light flux in the optical path can be adjusted, and the focusing position on the optical axis of the objective lens can be easily adjusted.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the optical focusing position adjusting method and the optical pickup according to the present invention will be described in detail below with reference to the drawings. It should be noted that the same or equivalent parts as those of the conventional example will be described by attaching the same reference numerals. Figure 1
4 to 4 show an optical focusing position adjusting method and an optical pickup in the optical pickup according to the present invention.
1 is an overall configuration diagram, FIG. 2 is a configuration diagram showing a case of focusing outside the objective lens focus position, FIG. 3 is a configuration diagram showing a case of focusing at the objective lens focus position, and FIG. 4 is a view showing the objective lens focus position. It is a block diagram which shows the case where it focuses on an inner side.

In FIG. 1, reference numeral 1 denotes a laser light source composed of a semiconductor laser, and a laser beam 1a from this laser light source 1 is passed through a collimating piezoelectric lens 2A as a laser beam 2a to a main body (not shown). A focal point 5 is formed on a surface 4a of a disc 4 such as an optical disc through a fixedly arranged objective lens 3.

An optical path 10 is formed in the laser beam 2a from the laser light source 1 to the objective lens 3,
The collimating piezoelectric lens 2A is located in the optical path 10.

A pair of electrodes 2Aa and 2Ab are formed on the outer circumference of the collimating piezoelectric lens 2A. By applying a signal between the electrodes 2Aa and 2Ab, the collimating piezoelectric lens 2A changes its refractive index. It can be changed, for example, in the case of the refractive index n ₁ as shown in FIG.
Focusing on the outside of the focal point of the objective lens, focusing at the focal point of the objective lens when the refractive index is n ₀ as shown in FIG. 3, and further when focusing at the refractive index n ₂ as shown in FIG. Focuses inside the lens focus position. The above-mentioned refractive indices have a relationship of n ₁ > n ₀ > n ₂ .

Therefore, the collimating piezoelectric lens 2A
By selecting the applied signal to the optical path 10, the divergence angle of the laser beam 2a in the optical path 10 can be adjusted, and the focusing position (focus point 5) of the objective lens 3 on the objective lens optical axis 3A can be arbitrarily selected. The focus on can be adjusted freely.

[0013]

Since the optical focusing position adjusting method and the optical pickup in the optical pickup according to the present invention are configured as described above, the following effects can be obtained. That is, since the collimating lens in the optical path is a collimating piezoelectric lens, the refractive index can be changed according to the applied signal, and there is no need to move the objective lens as in the conventional case.
It is possible to reduce the weight and improve athletic performance and shorten information access time.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an optical focusing position adjusting method and an optical pickup in an optical pickup according to the present invention.

FIG. 2 is a configuration diagram showing a case of focusing outside an objective lens focal position.

FIG. 3 is a configuration diagram showing a case of focusing on a focal position of an objective lens.

FIG. 4 is a configuration diagram showing a case of focusing on an inner side of a focal position of an objective lens.

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

[Explanation of symbols]

 1 Laser Light Source 2a Laser Beam 2A Piezoelectric Lens for Collimation 3 Objective Lens 4 Disc 10 Optical Path

Claims (2)

[Claims] 1. A light focusing position adjustment in an optical pickup in which a laser beam (2a) in an optical path (10) from a laser light source (1) is made incident on a disk (4) through an objective lens (3). In the method, the divergence angle of the laser beam (2a) is adjusted by a collimating piezoelectric lens (2A) that changes a refractive index by a piezoelectric action, and a method for adjusting a light focusing position in an optical pickup. 2. An optical pickup in which a laser beam (2a) in an optical path (10) from a laser light source (1) is incident on a disk (4) through an objective lens (3). An optical pickup comprising a collimating piezoelectric lens (2A) provided between (1) and an objective lens (3).