JPS6224448A - Objective lens cleaning method for optical pickup - Google Patents

Abstract

PURPOSE:To remove dirt, dust, or the like sticking on an objective lens with a quick flow of air by controlling an optical disc and a pickup device so that their relative speeds are raised before the start of reproducing. CONSTITUTION:When a driving voltage for kick of a spindle motor M is set to a value larger than that of a normal kick voltage, the number of revolutions of an optical disc D is raised quickly to 1.5-3-fold steady number of revolutions before the start of reproducing. The kick voltage is turned off, and a brake voltage is impressed if necessary, and rotation servo is applied when the number of revolutions approaches the steady number of revolutions, and the state is switched to the reproducing state. A high wind pressure is impressed to an objective lens of the pickup by the wind velocity of the optical disc D which is caused when the number of revolutions is a peak. Thus, dirt, dust, or the like which is stuck to the surface of the objective lens and cannot be removed in a normal rotative speed is blown off.

Description

[Detailed description of the invention] [Industrial application field] This invention]! 1 is related to the optical disc ++T production device,
In particular, the present invention relates to a method for cleaning an objective lens of an optical pickup that irradiates an optical disc with a laser beam or the like.

[A essential point of the invention]

This invention is an optical disc 1 that irradiates a rotating optical disc with a light beam and reads recorded information from the reflected light.
In the first recording device, the relative speed of the optical disc and the pickup device is controlled to be high, for example, before the first recording starts, so that the relative speed of the optical disc and the pickup device, which is generated at that time, is controlled to be high. It is designed to remove attached dust or dirt.

[Conventional technology]

An optical disc playback device that forms a spiral or concentric solid track on an optical disc and reads uneven pit information recorded on the track while irradiating laser light, for example, has a high recording rate. Because facial information is stored based on density, it is used in video equipment and other data filing devices.

Incidentally, in such an optical disc reproducing device, a focusing circular objective lens is mounted on the pickup device in order to irradiate a light beam onto a minute recording track (1 to 2 m). Since the light is irradiated from below towards the end of the objective lens, dust, dirt, etc. inside the device tend to accumulate on the long surface of this objective lens. This results in a reduction in the amount of black light passing through the objective lens, resulting in a problem that the reproduced signal deteriorates.

[Problem that the invention seeks to solve]

Therefore, in order to eliminate the adhesion of such dust and dirt, it has been considered to mechanically seal the entire optical disc playback device or to make the pickup device a sealed layer; Configuring the entire pickup device in a sealed manner increases costs in terms of heat dissipation measures, and it is mechanically difficult to construct the pickup device in a sealed manner.

This invention was made in view of this problem, and uses an air flow to remove dirt or dust that adheres to the objective lens of an optical pickup, and this cleaning operation constantly prevents the S/N from deteriorating. A method for cleaning an objective lens of an optical pickup is provided.

[Means for solving problems]

When an optical disc is loaded into an optical disc reproducing device, a driving means is provided which rapidly increases the rotational speed of the optical disc and applies a large air flow to the objective lens of a pickup located close to the optical disc.

[Effect]

The distance between the optical disk and the objective lens that irradiates the optical disk with laser light is about a few centimeters, and when the optical disk rotates at high speed, a considerably large wind pressure is applied to the objective lens due to the airflow caused by the rotation. Therefore, when the optical disk is rotated at a linear velocity that is difficult to occur in normal regeneration, the removal of dust, dirt, etc. attached to the objective lens is promoted, and its cleaning action reduces the light transmittance of the objective lens. .

〔Example〕

The outline of the optical disc reproducing apparatus is shown in FIG. 1. When a video disc is mounted, an objective lens L of an optical pickup P is placed below an optical disc D having a layer φ of 300 m in diameter. The optical pickup P normally has the inner circumference side of the optical disc D as its home position, and when the optical disc D rotates at a constant speed at the start of playback, it reads the disc code recorded on the inner circumference and then starts the playback operation. .

That is, in such an optical disc reproducing apparatus, when the optical disc D is loaded, the spindle motor M
is kicked, and the rotation servo is applied when the spindle motor M reaches a constant rotation speed. Then, the pickup P reads information from the optical disc while moving toward the outer circumference.

Therefore, in the method for cleaning an objective lens of an optical pickup according to the present invention, first, the drive voltage at the time of kicking is set to be higher than the normal kicking voltage. Then,
As shown in Fig. 2, the rotational speed of the optical disc D rapidly increases before the start of playback, and the rotational speed of the optical disk D increases from 1.5 to the steady rotational speed.
It will increase 3 times. Then, the kick voltage is turned off, and if necessary, the brake voltage is applied conversely, and when the rotational speed approaches the steady rotational speed, the rotation servo is applied and the regeneration state is entered.

Then, strong wind pressure is applied to the objective lens of the pickup due to the wind speed of the optical disk D caused when the rotation speed reaches its peak, and dust attached to the surface of the objective lens that cannot be removed at normal rotation speed is removed. , or can blow away dirt to improve the cleaning effect.
L.

Next, a second embodiment of the invention will be described.

Constant optical diffuser angle (CAV) (1800 rpm)
3, the linear velocity vc near the inner circumference is approximately 10 m/s, which is the lowest linear velocity.

Therefore, the wind current caused by the rotation of the optical disc D is small. Therefore, in the case of this invention, as shown in FIG. 4, the position of the optical pickup P is
control so that it is set near the outermost circumference of the optical disc.

Then, as can be easily understood from Figure 3, the rotation speed is 1.
Since the linear velocity is 2.5 to 3 times that of 80 rpm, considerable wind pressure hits the objective lens L of the optical pickup as the optical disk rotates, blowing away dust or dirt attached to the surface of the objective lens L. It works effectively with L.

Thereafter, when the optical disk D reaches a constant speed of rotation, the optical pickup is moved to the home position on the inner circumference, and the playback operation is started.

Therefore, since dust or dirt attached to the objective lens L can be effectively removed before starting reproduction, the light transmission of the objective lens L is always corrected, and the S/F of the reproduced RF signal is
N can be directed to 1.

In the case of the CLV system, the rotation speed of the spindle motor may be controlled to decrease in proportion to the position of the optical pickup P after the start, as shown by the dotted line in FIG. 4.

As explained above, two methods have been shown as examples for setting the relative speed of the optical disc and the pickup to a large value before starting playback, but when these methods are combined, it is possible to further increase the relative speed of the optical disc before starting playback. The relative speed between D and the pickup P can be increased, and the cleaning effect of the objective lens is improved.

That is, as shown in FIG. 1, when two optical disks are loaded, the pickup P is positioned near the outermost circumference of the disk, and the spindle motor M is activated at this set position by a high kink voltage. Then, when the spindle motor M reaches the maximum rotation speed, the kick voltage is cut off, and the pickup P is moved to the home position on the inner circumference, and when the rotation speed of the optical pickup P approaches the steady rotation speed, the kick voltage is cut off. Add the rotation servo and set it to playback mode at the same time.

〔Effect of the invention〕

As explained above, the method for cleaning the objective lens of an optical pickup according to the present invention involves driving the spindle motor before starting playback so as to obtain a high rotational linear velocity that cannot be obtained with a normal playback condition JF6, or at the initial stage of the pickup. Since the position is set, there is an advantage that dust or dirt that is hardly removed under normal rotation can be removed from the surface of the objective lens. Therefore, the light transmittance of the objective lens deteriorates with long-term use, so the cleaning work that is required for this purpose can be reduced, and at the same time, it is possible to obtain an RF reproduction signal with an excellent S/N ratio. Demonstrate.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining the objective lens cleaning method of an optical pickup according to the present invention, FIG. 2 is a graph showing the tendency of the disk rotation speed to realize an embodiment of the cleaning method of the present invention, The figure is a graph showing the relationship between disk rotation speed and linear velocity in the CLV system, and Figure 4 is a graph showing the pickup movement and disk rotation speed6.
In the figure, D indicates an optical disk, P indicates a pickup device, L indicates an objective lens, M indicates a spindle motor, and X indicates the position of the pickup. Showing the relationship bag between Reno χ and Thess 2 -rLT! I diagram 1st
Fig. time → a rotation speed and p + main control graph Fig. 2 Diameter d (cm) - Rotation speed for CAV method and M section of the rock cliff Fig. 3

Claims (2)

[Claims] (1) In an optical disc playback device equipped with an optical pickup device that irradiates an optical disc with a light beam and reads information recorded on the optical disc, a spindle motor that rotates the optical disc performs the following steps before starting playback: A method for cleaning an objective lens of an optical pickup, characterized in that the objective lens of an optical pickup is driven at a rotation speed higher than the normal reproduction maximum rotation speed. (2) In an optical disc playback device equipped with a pickup that irradiates an optical disc with a light beam and reads information recorded on the optical disc, the pickup is positioned near the outermost circumference of the optical disc before starting playback. A method for cleaning an objective lens of an optical pickup, the method comprising: driving the optical disc at this position to at least a rotational speed during normal playback, and then controlling the pickup to move to a home position on an inner periphery.