JPH0414631A - Objective lens drive device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an optical information recording/reproducing device for optically recording and reproducing information. The present invention relates to an objective lens driving device.

(Prior Art) This type of objective lens driving device, as shown in FIG. It has a configuration in which a base 4 on the wing tip side is connected to an optical head portion 5 containing an optical system (not shown), and the objective lens holder 2 is centered around a support shaft 6 that stands upright on the base 4. Rotation is controlled electromagnetically. Further, an optical window 8 is opened in the cover 3 on the disk-shaped recording medium 7 side, located on the optical axis of the objective lens l, and an optical window 9 is opened in the base 4 on the opposite side. It is open.

(Problem to be Solved by the Invention) In such a configuration, when the recording medium 7 is driven and rotated, the airflow generated on the surface of the recording medium 7 causes dust in the air to flow through the optical window 8 to the actuator cover 3. Following the path shown by the arrow, it reaches the optical window 9, and further penetrates into the optical head portion 5, where the internal optical components,
There is a risk of it adhering to the light receiving sensor and contaminating it. Therefore, there is a drawback that normal optical signal input and output cannot be obtained.

(Object of the Invention) The present invention has been made based on the above-mentioned principle, and even if dust enters the actuator cover, it can substantially prevent the dust from entering the optical system, thereby ensuring normal optical signals. The objective is to provide an objective lens drive device that is devised to ensure input and output.

(Means for Solving the Problem) Therefore, in the present invention, when information is recorded on or reproduced from a disk-shaped recording medium, a laser beam is focused on the recording layer of the recording medium. The objective lens drive device includes an actuator cover that covers an objective lens and an objective lens holder that supports the objective lens, and is provided with an actuator cover that is located on the optical axis of the objective lens on the actuator cover and a base that supports the actuator cover. Optical windows are provided on the recording medium side and the opposite side thereof, and a cylindrical member is coaxially arranged extending from the optical window side on the opposite side within the light amount of the objective lens in the objective lens holder. .

(Function) Therefore, even if dust enters the actuator cover through the optical window on the recording medium side on the airflow, the airflow is suppressed by the cylindrical member, and the airflow is suppressed and It is possible to prevent dust from entering the optical system through the optical system, and to ensure normal output of optical signals.

(Example) Hereinafter, an example of the present invention will be specifically described with reference to FIGS. 1 and 2. Note that the same reference numerals are given to the same components as in the description of the conventional example, and the description thereof will be omitted. In particular, in this embodiment, a cylindrical member 10 whose length is set in consideration of the axial control operation range of the objective lens holder 2 with respect to the support shaft 6 is used to It stands upright from the base 4 so as to surround the optical window 9.

Therefore, a part of the airflow generated by the rotation of the recording medium 7 enters the actuator cover 3 through the optical window 8 and directs the surroundings of the objective lens holder 2 as shown by the arrow in the figure. Even if the dust enters the lower side, the outer circumferential wall of the cylindrical member 10 prevents the airflow and prevents the dust from rising within the light amount of the objective lens 1. Therefore, the inner surface of the objective lens 1 Also, it is possible to prevent dust from entering the optical system of the optical head portion communicating through the optical window 9.

Note that the position of the objective lens 1 indicated by a dotted line in the figure indicates the maximum lowering position of the lens during focus control. Further, in the figure, reference numeral 11 is a bearing provided on the optical head portion 5, and reference numeral 12 is a rail that guides the movement of the optical head portion 5 via this bearing.

Note that the gap between the outer circumferential wall of the cylindrical member 10 and the inner circumferential wall of the front tube of the objective lens 1 may be set to a desired dimension. Further, if the objective lens is placed at the position indicated by the dotted line when recording or reproducing is not performed, the cylindrical member 10 can completely prevent dust from entering the substantial optical path of the objective lens 1.

(Effects of the Invention) The present invention has been described in detail above, and since the cylindrical member disposed coaxially with the optical axis of the objective lens prevents dust from entering the optical head, the optical head For example, optical members such as flip-up mirrors and polarizing beam splitters, and light receiving sensors are not contaminated, and therefore there are no problems such as a decrease in the amount of light beam, and highly reliable signal output can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing an embodiment of the present invention, FIG. 2 is an external perspective view, and FIG. 3 is a longitudinal sectional side view showing a conventional example. 1... Objective lens, 2... Objective lens holder, 3...
...Actuator cover, 4...Base, 5...Optical head portion, 6...Spindle, 7...Recording medium, 8,
9... Optical constriction 10... Cylindrical member.

Claims (1)

[Claims] An objective lens and an objective supporting the objective lens in an objective lens drive device for condensing a laser beam onto a recording layer of the recording medium when recording or reproducing information on a disk-shaped recording medium. an actuator cover that covers the lens holder; an optical window is provided on the actuator cover and a base supporting the actuator cover on the optical axis of the objective lens on the recording medium side and on the opposite side; An objective lens driving device characterized in that a cylindrical member is disposed coaxially within the optical tube of the objective lens in the lens holder, extending from the optical window side on the opposite side.