JPH0648574Y2 - Optical pickup inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention detects the amount of displacement of an objective lens in an optical pickup used in an optical disk device or the like in order to measure the current sensitivity or frequency characteristics thereof. The present invention relates to improvement of an optical pickup inspection device.

<Prior Art> FIG. 5 is a block diagram showing an example of a conventional optical pickup inspection apparatus. In the figure, 1 is an optical pickup and 2 is its objective lens. Reference numeral 3 is a light source for irradiating parallel light onto the upper part of the objective lens 2 (lens barrel), 4 is a light receiving element for receiving the parallel light, and 5 is a conversion circuit for converting an output current of the light receiving element 4 into a displacement signal.

In the optical pickup inspection device configured as above, the parallel light emitted from the light source 3 is blocked by the objective lens 2, and the amount of light incident on the light receiving element 4 changes according to the amount of displacement. In the illustrated state, the displacement amount of the objective lens 2 in the focus direction F is detected, but if the side wall of the objective lens 2 is irradiated with light, the displacement amount in the tracking direction can also be detected.

FIG. 6 is a block diagram showing another example of the conventional optical pickup inspection device. In the apparatus shown in the figure, a reflection sheet 6 or the like is attached to the upper part of the objective lens 2, and the displacement amount of the objective lens 2 is measured by using a reflection type displacement converter 7.

<Problems to be Solved by the Invention> However, in the apparatus shown in FIG. 5, since the lens barrel of the objective lens 2 must be irradiated with light, the amount of displacement in the state where the objective lens 2 enters the optical pickup 1 is large. Cannot be detected, and the type and measurement range of the optical pickup 1 that can be measured are limited.

Further, in the apparatus shown in FIG. 6, the reflecting sheet 6 is attached to the objective lens 2.
Since it is necessary to attach such as, there is a risk that the lens surface will be soiled, and the weight thereof will be a load on the lens drive system, and accurate characteristics cannot be measured. Further, the displacement of the objective lens 2 in the tracking direction cannot be detected.

The present invention eliminates the above-mentioned drawbacks of the conventional device and simplifies an optical pickup inspection device capable of accurately detecting the displacement amount of the objective lens over the entire movement range regardless of the type of the optical pickup. It is intended to be realized by such a configuration.

<Means for Solving the Problems> An optical pickup inspection device of the present invention is an aperture stop which is arranged at a position that blocks light emitted from an objective lens of an optical pickup and has a small hole at a position decentered from the center of the objective lens. And a position detector that receives the light that has passed through the small hole and detects the incident position thereof.

<Operation> As described above, if the position detector receives the light that has passed through the diaphragm having the small hole at the position eccentric from the center of the objective lens, the light to the position detector is changed according to the displacement of the objective lens. Since the incident position of is changed, the displacement amount of the objective lens can be detected from the incident position. Also,
This change in the incident position is sensitive to both displacements of the objective lens in the focus direction and the tracking direction. Therefore, it is possible to measure the displacement amount of the objective lens in the focus direction and the tracking direction at the same time with one detector. You can

<Embodiment> FIG. 1 is a block diagram showing an embodiment of an optical pickup inspection apparatus of the present invention. In the figure, the same parts as those in FIG. 5 are designated by the same reference numerals. Reference numeral 8 denotes a diaphragm arranged at a position for blocking the light emitted from the objective lens 2. The diaphragm 8 is provided with a small hole (pinhole) 9 at a position decentered from the center (optical axis) of the objective lens 2. ing. Reference numeral 10 denotes a position detector that receives the light that has passed through the small hole 9 and detects the incident position.

Further, in FIG. 2, a convex lens 11 is inserted between the diaphragm 8 and the diaphragm 8 in order to increase the detection sensitivity of the position detector 10.

In the apparatus configured as described above, when the objective lens 2 is displaced in the focus direction F and the tracking direction T, the incident position of the light that has passed through the small hole 9 in the position detector 10 changes. Therefore, the position corresponding to this incident position The displacement amount of the objective lens 2 can be detected from the output signal of the detector 10.

For example, if the objective lens 2 is displaced from P1 to P2 in the focus direction F as shown in FIG.
The incident position at 10 moves from p1 to p2.

Further, as shown in FIG. 4, when the position of the eyelet 9 is set on the axis orthogonal to the tracking direction T in the objective lens 2, the position detector 10 when the objective lens 2 is displaced in the tracking direction T is detected. The incident position at moves in the direction T '. This is a direction orthogonal to the movement direction with respect to the focus direction F. Therefore, by detecting the output components of the position detector 10 in the two axial directions, the displacement of the objective lens 2 in the focus direction F and the tracking direction T can be easily detected.

As described above, when the displacement amount of the objective lens 2 is detected by using the light emitted from the optical pickup 1, the displacement amount is detected over the entire moving range of the objective lens 2 without the need of a light source for detection. Can be detected.

<Effect of Device> As described above, in the optical pickup inspection device of the present invention, a small hole is placed at a position that blocks light emitted from the objective lens of the optical pickup and is eccentric from the center of the objective lens. Since it has the stop and the position detector that receives the light that has passed through this small hole and detects the incident position, the incident position of the light on the position detector changes according to the displacement of the objective lens. However, regardless of the type of the optical pickup, it is possible to realize an optical pickup inspection device capable of accurately detecting the displacement amount of the objective lens over the entire moving range with a simple configuration.

[Brief description of drawings]

1 to 4 are configuration diagrams showing an embodiment of an optical pickup inspection device of the present invention, and FIGS. 5 and 6 are configuration diagrams showing an example of a conventional optical pickup inspection device. 1 ... Optical pickup, 2 ... Objective lens, 3 ... Light source, 4 ... Light receiving element, 5 ... Conversion circuit, 6 ... Reflection sheet, 7 ... Displacement converter, 8 ... Aperture, 9 ... Small holes, 10 ...
… Position detector, 11… Convex lens.

Claims (1)

[Scope of utility model registration request] 1. A diaphragm having a small hole arranged at a position for blocking light emitted from an objective lens of an optical pickup and having a small hole at a position eccentric from the center of the objective lens, and an incident position for receiving light passing through the small hole. An optical pickup inspection device comprising a position detector for detecting the.