JPH0266728A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To detect the output reduction of a photodetector due to the sticking of the dust and stain of an objective lens in an optical head by providing a reflecting mirror and outputting an abnormality detecting signal when the reflecting light quantity is lower than a constant level. CONSTITUTION:With a light beam from a laser diode 11 in an optical head 1, a reference reflecting mirror 2 is irradiated through an optical system 3 and the reflecting light is detected through the optical system 3 by a light detector 12 again. At this time, when the dust and the stain are stuck to an objective lens 31 in the head 1, the emitting light quantity emitted through a lens 31 is reduced, the output of the detector 12 is reduced. The output of the detector 12 is lower than a reference voltage 41 of a differential discriminator 4, and then, the differential discriminator 4 outputs an abnormality detecting signal 42.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical information recording/reproducing apparatus, and more particularly to an optical recording/reproducing apparatus having an abnormality determination function of an optical head.

Prior Art Generally, in this type of optical information recording/reproducing device,
In order to stabilize the light output emitted from the optical head, the amount of light emitted from the laser diode is detected, and automatic output control is performed so that this detected amount remains constant. The conventional optical information recording/reproducing device will be explained using FIG. 2.

FIG. 2 is a schematic diagram showing an example of automatic output control in a conventional optical information recording/reproducing device. In the figure, 1 is an optical head, 5 is a difference device, 6 is a laser diode drive current control circuit, and 51 is a reference voltage.

The optical head 1 includes an optical system 3 including an objective lens 31, a prism 32, and a lens 33, a laser diode 11, and a photodetector 13.

Note that the laser diode 11 and the photodetector 13 may be integrally molded.

In this configuration, a part of the amount of light emitted from the laser diode 11 in the optical head 1 is detected by the photodetector 13, and the difference between the output of this photodetector 13 and a reference voltage 51 that determines a predetermined amount of light emitted from the laser diode is detected. is determined in the differentiator 5.

The laser diode drive current control circuit 6 increases or decreases the drive current flowing through the laser diode 11 based on the output of the differentiator 5, controls the output of the photodetector 13 to always be the same as the reference voltage 51, and controls the laser diode. It operates to keep the light output from 11 constant.

However, in the automatic output control of the optical output described above, if dust or dirt from the usage environment of the optical information recording/reproducing device adheres to the objective lens 31 in the optical head, the optical head 1
It is impossible to detect a decrease in the amount of light emitted from the
There was a drawback that recording and reproduction could not be performed with a predetermined amount of light.

Furthermore, if a very thin layer of dust or dirt adheres to the objective lens 31 in the optical head, the film may deteriorate the aperture of the emitted beam even if it does not cause a decrease in the amount of light emitted from the optical head 1. There is a drawback that the amount of light reflected from the optical head 1 from an optical disk (not shown) to a detector (not shown) in the optical head 1 is reduced, which may increase errors in information recording/reproduction or cause malfunctions in servo control. .

OBJECTS OF THE INVENTION It is an object of the present invention to provide an optical information recording/reproducing device that can detect a decrease in the output of a photodetector due to adhesion of dust or dirt to an objective lens in an optical head.

Composition of the Invention The optical information recording and reproducing apparatus of the present invention is an optical information recording and reproducing apparatus that includes a laser light source and a lens that focuses the emitted light of the laser light source on a predetermined position. a reflecting means for reflecting the emitted light condensed by the lens; a signal transmitting means for transmitting a signal corresponding to the amount of reflected light from the reflecting means; and an output signal of the signal transmitting means set in advance. and comparison means for comparing the reference signal with the reference signal.

Example Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic diagram of an embodiment of an optical information recording/reproducing apparatus according to the present invention, and parts equivalent to those in FIG. 2 are designated by the same reference numerals.

In the figure, an optical information recording/reproducing apparatus according to an embodiment of the present invention includes an optical head 1, a reference reflection mirror 2 that reflects light emitted from an objective lens 31 in the optical head 1, and a laser beam in the optical head 1. An optical system 3 that irradiates a light beam from a diode 11 onto a disk (not shown) and guides the reflected light to a photodetector 12, and a difference device 4 that compares the output of the photodetector 12 with a determination reference voltage 41. It is composed of:

Note that the other parts have the same configuration as in FIG. 2, so their explanation will be omitted.

It is assumed that the reference reflection mirror 2 is mounted at the same distance from the objective lens 31 or at the same position as the optical disk.

In this configuration, the light beam from the laser diode 11 in the optical head 1 passes through the optical system 3 and is irradiated onto the reference reflection mirror 2, and the reflected light passes through the optical system 3 again and is detected by the photodetector 12. be done.

In this case, if dust or dirt adheres to the objective lens 31 in the optical head 1, the amount of light emitted through the objective lens 31 decreases, and thus the output of the photodetector 12 decreases.

Furthermore, if a very thin layer of dust or dirt adheres to the objective lens 31 in the optical head 1, the film will deteriorate the aperture of the emitted light beam even if it does not cause a decrease in the amount of light emitted from the optical head 1. let Then, the amount of light reflected from the optical disk to the photodetector 12 in the optical head 1 decreases, and the output of the photodetector 12 decreases.

In this embodiment, the objective lens 31 in the optical head 1
The determination reference voltage 41 is set to a certain percentage (for example, 95%) of the output voltage of the photodetector 12 in an initial state where no dust or dirt is attached. By doing this, when the output voltage of the photodetector 12 becomes lower than the determination reference voltage 41 (that is,
When the amount of reflected light decreases below a certain percentage of the initial state), the differentiator 4 outputs an abnormality detection signal 42.

That is, according to the present invention, a decrease in the output of the photodetector 12 due to a decrease in the amount of light emitted from the optical head 1 or a decrease in the output of the photodetector 12 due to adhesion of dust or dirt to the objective lens 31 in the optical head 1 is detected.
By issuing a warning to the operator, it becomes possible to clean the objective lens and adjust the amount of emitted light before errors in information recording and reproduction increase.

Note that the reference reflection mirror 2 is fixed within the housing, and the displacement is sufficient so that the optical head 1 can be moved to the position of the reference reflection mirror 2.

Alternatively, a reference reflection mirror having the same shape as the optical disc may be prepared and set in the same manner as the optical disc at the time of inspection or the like.

Furthermore, a configuration may be adopted in which the reference reflection mirror is lifted to a predetermined position when no optical disc is set.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention provides a reference reflecting mirror, and outputs an abnormality detection signal when the amount of reflected light from the reference reflecting mirror becomes lower than a certain level, thereby controlling the amount of light emitted from the optical head. This has the advantage that it is possible to detect at an early stage a decrease in the output of the photodetector due to a decrease in the output of the photodetector due to a decrease in the output power or a decrease in the output of the photodetector due to dust or dirt adhering to the objective lens.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an optical information recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a conventional optical information recording/reproducing apparatus. Explanation of symbols of main parts 2...Reference reflecting mirror 3...Optical system 4.5...Differentiator 11...Laser diode 12.13... ...Photodetector 31...Objective lens

Claims (1)

[Claims] (1) An optical information recording/reproducing device comprising a laser light source and a lens that focuses the emitted light of the laser light source on a predetermined position, the emitted light being provided at the predetermined position and focused by the lens. a reflecting means for reflecting light, a signal transmitting means for transmitting a signal according to the amount of reflected light from the reflecting means, and a comparing means for comparing an output signal of the signal transmitting means with a preset reference signal. An optical information recording/reproducing device comprising: