JPH03122833A - Stain detector for optical disk recording and reproducing 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 a dirt detection device for detecting dirt on an objective lens in an optical disc recording/reproducing device.

[Conventional technology]

In an optical disc recording/reproducing device, since the optical disc is inserted into and taken out from the disc tray or cartridge pocket, dust and dirt are likely to adhere to the objective lens and the optical disc. Therefore, for example, if the objective lens in the optical head becomes dirty due to adhesion of dust or the like, this will lead to a decrease in laser light output and deteriorate the recording and reproducing state. Therefore, in conventional optical disc recording and reproducing devices, a cover is provided above the objective lens when not recording or reproducing, and
A dirt detection device as described in Japanese Patent No. 74130 has been proposed.

In this dirt detection device, the laser light output measuring means is composed of a reflecting mirror, and the reflecting mirror is installed near the focal point of the objective lens, so that when the laser light output falls below a standard value, dirt adheres to the objective lens. The system determines that cleaning is necessary and notifies the user of the need for cleaning.

[Problem to be solved by the invention]

In the above conventional technology, the reflecting mirror is fixed near the focal point of the objective lens, but since the detection output changes depending on the distance between the reflecting mirror and the objective lens, in order to accurately measure the laser light output, it is necessary to fix the reflecting mirror near the focal point of the objective lens. The positional accuracy of the objective lens must be within ±several tens of μm with respect to the focal position. For this reason, there is a problem in that the reflecting mirror and the objective lens must be precisely attached and fixed.

The purpose of the present invention is to solve the problems of the prior art described above,
In addition to preventing dirt on the objective lens, precise mounting and fixing of the reflecting mirror and objective lens is not required, and the laser light output can be detected accurately to accurately understand the state of dirt on the objective lens. The object of the present invention is to provide a dirt detection device capable of detecting dirt.

(Means for solving the 1m problem) The above purpose is to cover the objective lens of the optical head with a cover provided with a reflecting mirror when the original disc is not being recorded or played back, and to measure the laser light output when the original disc is not being recorded or played back. This is achieved by measuring the laser light output while controlling the focus servo control to focus the light spot on the reflecting mirror to detect the adhesion of dust or dirt.

[Effect]

According to the present invention, the focus servo control operates so that the laser beam from the objective lens is always focused on the reflection mirror surface, so even if there is some variation in the attachment of the reflection mirror and the objective lens, the laser beam Light output can be detected accurately. As a result, the state of adhesion of dust and dirt on the objective lens can be detected, and by determining whether or not cleaning of the laser beam emitting section is necessary, good recording and reproduction can always be performed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a dirt detection device as an embodiment of the present invention, and shows the peripheral portion of an optical head of an optical disk recording/reproducing device. In FIG. 1, l is an optical head, which includes an objective lens 2, a laser element 3, a collimator lens 4, a beam splitter 5, a condenser lens 6, and a photodetector 7.
It is made up of. Reference numeral 8 indicates a reflecting mirror; 9, a slider for moving the light beam; 10, a comparison circuit for comparing the output ' of the photodetector 7 with a reference value; and 14, a cover.

The operation of the apparatus configured as described above will be explained below.

Before and after recording and reproducing an optical disk (not shown), the objective lens 2 of the optical disc 1 is closed to the cover 14 as shown in FIG.
This prevents dirt from adhering to the objective lens 2 of the optical lens.

This cover 14 also prevents dirt from adhering to the reflecting mirror 8. The reflecting mirror 8 is directly above the objective lens 2, and
It is located near the height of the disk surface when the original disk is installed. In this state, laser light is output from the laser element 3 of the optical head 1.

The laser beam passes through a collimator lens 4, a beam splitter 5,
The light passes through the objective lens 2 and is output toward the reflecting mirror 8.

Although not shown in the figure, by operating the focus servo that is normally performed during disc playback,
Control is performed by moving the objective lens 2 in the vertical direction so that the light spot emitted from the objective lens 2 is focused on the reflecting mirror 8. The focused laser beam is reflected by a reflecting mirror 8, passes through an objective lens 2, a beam splitter 5, and a condensing lens 6, and is focused on a photodetector 7. Photodetector 7
outputs a signal corresponding to the focused laser beam.

This signal output enters a comparator circuit 10 and is compared with a reference value. The standard value corresponds to the optimum laser beam,
When a signal output lower than this value is input, it is determined that the optical parts of the optical radar 1 are contaminated, and a warning is given that cleaning is required.

FIG. 2 is an explanatory diagram showing an example of the mounting position of the cover opened in FIG. 1. In FIG. 2, 1 is an optical head similar to that shown in FIG. 1, 2 is an objective lens, 8 is a reflecting mirror, 13 is a spindle motor, and 14 is a cover. Further, 11 is an optical disk, which is housed in a cartridge 12. 15 is a cartridge pocket;
When the cartridge 12 is inserted, the cartridge pocket 15 moves together and the optical disk 11 inside the cartridge 12 is set on the spindle motor 13.

Before recording and reproducing the optical disc 11, the optical head 1 is housed under a cover 14 fixed in a place where it will not interfere with the loading operation, and the objective lens 2 of the optical disc 1 is prevented from getting dirty. There is. At this position, dirt on the optical components of the optical head 1 explained in FIG. 1 is detected.
If dirt is detected, it will alert you that cleaning is required.

When no dirt is detected, the slider 9 moves the optical disk l in the direction of the arrow, the optical disc 11 is set on the spindle motor 13, and normal recording and reproduction is performed.

FIG. 3 is an explanatory diagram showing another example of the mounting position of the cover provided in FIG. 1. 3 is the same as FIG. 2 except that the mounting positions and shapes of the reflecting mirror 8 and cover 14 are different.

Before recording and playing back an optical disc, the optical head l
is located under the cover 14 provided at the bottom of the cartridge pocket 15, and prevents the objective lens 2 of the optical head 1 from getting dirty. At this position, dirt on the optical components of the optical head l explained in FIG. 1 is detected. If dirt is detected, it will alert you that cleaning is required. When no dirt is detected, the optical head 1 is moved in the direction of the arrow by the slider 9, the cartridge pocket 15 is moved from the position a to the position b, and the optical disc 11 is set.

In the example shown in FIG. 3, the reflecting mirror 8 and cover 14 are provided at the bottom of the cartridge pocket 15, so that it can be made more compact than in the example shown in FIG.

FIG. 4 is a configuration diagram showing a dirt detection device as another embodiment of the present invention. In FIG. 4, the optical head 1 in FIG. 1 is replaced with a separate head, and is basically the same as in FIG. 1 except that it is divided into a movable optical system 17 and a fixed optical system 18. Reference numeral 16 denotes an upright mirror that changes the direction of the laser beam from the fixed optical system 18 and irradiates the optical disk 11 with it. A backing 19 prevents the movable optical system 17 from colliding with the fixed optical system 18, and also prevents dirt and dust from entering the optical system as described later.

Before and after recording and reproducing the optical disc 11, the movable optical system 17 is fixed in close contact with the fixed optical system 18 with the backing 19 in between. At this time, the movable optical system 17
These prevent dirt and dust from entering the optical head. This cover 14
At the same time, it also prevents dirt from adhering to the reflecting mirror 8.

At this time, the reflection mirror 8 is located directly above the objective lens 2 and near the height of the disk surface when the optical disk 11 is mounted. Here, the optical helad 1 explained in FIG.
The system detects dirt on the optical parts of the camera, and if dirt is detected, it issues a warning that cleaning is required. When no dirt is detected, the movable optical system 17 is moved by the slider 9, and normal recording and reproduction is performed as shown in FIG.

〔Effect of the invention〕

Since the present invention is configured as described above, it has the following effects.

When the optical disk is not being recorded or reproduced, covering the optical head with a cover provided with a reflection mirror can prevent dirt from adhering to the objective lens and reflection mirror. In addition, by focusing the light spot on the reflective surface of the reflective mirror at this position using focus servo control, the laser light output can be detected with high accuracy even if the reflective mirror and objective lens are not precisely mounted and fixed. can do. Therefore, it is possible to accurately grasp the state of dirt adhesion on the objective lens, and it is possible to warn that cleaning is necessary. Therefore, maintenance of the optical disc recording and reproducing apparatus can be effectively carried out.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing a dirt detection device as a part of the present invention, Fig. 2 is an explanatory diagram showing an example of the mounting position of the cover in Fig. 1, and Fig. 3 is an illustration of the installation of the cover in Fig. 1. An explanatory diagram showing another example of the position, and FIG. 4 is a configuration diagram showing a dirt detection device as another embodiment of the present invention. l...Optical head 2...Objective lens 3...
- Laser element 7... Photodetector 8... Reflection mirror 10... Comparison circuit 11... Optical disk 14... Cover 15... Cartridge pocket 16... Raising mirror 17... Movable Optical system 1
8...Fixed optical system

Claims (1)

[Claims] 1. An optical head having at least a laser light source and an objective lens is provided, and during recording/reproduction, the laser light emitted by the laser light source is directed onto the disc surface of the optical disc by the objective lens under focus servo control. In an optical disc recording and reproducing apparatus capable of controlling the position of the objective lens so that light is focused with just focus on The objective lens covers the objective lens of the optical head, and controls the focus servo so that the laser beam emitted by the laser light source is focused by the objective lens onto the mirror surface of the reflecting mirror with just focus. The lens position is controlled, the laser beam reflected by the reflecting mirror is detected, and whether or not the objective lens is dirty is detected from the detected laser beam. Dirt detection device. 2. The dirt detection device according to claim 1, wherein the cover having the reflective mirror is provided at a lower part of a cartridge that accommodates the optical disc. 3. In the dirt detection device according to claim 1, the optical head includes a fixed optical system whose position is fixed, and a movable optical system whose position is movable and has at least the objective lens. The movable optical system is fixed to the fixed optical system in close contact with the fixed optical system, and the objective lens of the movable optical system is covered by the cover when not recording or reproducing. dirt detection device.