JPH0519207B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for recording and reproducing information with good quality when recording and reproducing information such as video signals on a disk-shaped recording medium using a light beam such as a laser. It is related to.

Conventional configurations and their problems Traditionally, as seen in the example of optical video disks, signals are recorded on a disk-shaped recording medium (hereinafter referred to as a disk) as concentric or spiral recording loci with unevenness or shading. As a binary signal,
Devices that perform high-density recording and reproduction are being considered. In such devices, the recorded signal is
The signal is subjected to FM modulation or PCM processing, converted to a binary signal, recorded as recording pits on a recording medium, and then reproduced.

Furthermore, in the case of such a recording/reproducing apparatus, the recording pits are generally minute, about 1 μm in diameter, and the recording track pitch is also about 1.5 to 3 μm, so that a large-capacity signal recording/reproducing apparatus can be obtained.

In such devices, when a light beam such as a laser is used to record signals as pits with unevenness or shading, the light beam is generally focused to a diameter of 1 μm or less, and the heat is used to make the recording medium uneven or dark and dark. This causes the formation of pits.

When a device using the above recording method is manufactured to record and reproduce signals, the area around the recording medium and optical system is rarely completely sealed and free from dust and other contaminants. This is because, in the case of the above-mentioned signal recording and reproducing apparatuses, there are many apparatus designs in which one of the major features is that the recording medium can be easily replaced. The fact that the recording medium can be easily replaced means that even if the device is designed with considerable consideration given to the ingress of dust, it is not possible to completely prevent contamination. It is possible that this may affect the performance of the optical system.

First, as shown in FIG. 1, as a conventional example of a device for recording and reproducing signals on a disk-shaped recording medium using light such as a laser, a still image of a television signal of one frame per track of one rotation of the disk is shown. An optical recording and reproducing apparatus for recording and reproducing will be explained.

A video signal input from a signal input terminal 1 is processed by a signal processing circuit 2 and guided to a semiconductor laser drive circuit 3.

The light emitted from the semiconductor laser 4 passes through a lens system 5, is reflected by a polarizing beam splitter 6, and is
The beam passes through four plates 7, is focused through an aperture lens 8, and is irradiated onto a disk 10. The aperture lens 8 is connected to the disk 10 by the focus element 9.
The light beam moves to follow the surface wobbling of the disk 10, and the light beam is always focused on the disk 10.

The light beam reflected from the disk 10 is λ/4
passes through the plate 7, passes through the polarizing beam splitter 6,
The light is incident on the light receiver 14.

The electrical signal output from the light receiver 14 is sent to the head amplifier 1.
5, passes through a signal processing circuit 16 including demodulation, and is output as a reproduced signal from a signal output terminal 17.

When such an apparatus records one frame of an NTSC television signal image per one rotation of the disk, the motor 11 is rotated at 1800 rpm. 1 revolution detector 1
2 detects one rotation of the motor 11, processes the signal in the one rotation detection processing circuit 13, and supplies a signal of one rotation to the semiconductor laser drive circuit 3 when recording an image signal. A frame-only signal is supplied to the semiconductor laser 4. In this way, one frame of image can be recorded in one rotation of the disk, and one image can be recorded one after another in one rotation of the disk.

These devices have major features such as high-density recording because they use light, and less deterioration in image quality because they use non-contact recording and playback.
Considerable measures must be taken to prevent dirt on the lens system and dirt on the disk surface.

As a countermeasure against contamination due to dust, it is sufficient to completely seal the optical system and disk section, but in general, many information recording and reproducing devices using optical disks take advantage of the fact that the disks can be easily replaced. There is a limit to the ability to create a structure where the disk part can be easily replaced and prevent dirt from getting dirty, and if you consider the long period of 3 to 5 years, dirt from dirt will inevitably occur.

The reason why many devices that use light take advantage of the fact that disks can be easily replaced is because they can be used again in good performance by wiping away dirt from the optical lens and disk surface with a cloth or other material. It is.

Since deterioration in information recording and reproduction caused by contamination of the optical system or disk by dust occurs gradually over a long period of time, it is often difficult to determine when to remove the contamination by dust.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a device that accurately informs the device user of this point and records and reproduces information using light while always maintaining good performance.

Composition of the Invention The present invention provides an optical information recording system in which a dirt detector of an optical system having a second optical system different from a first optical system for recording and/or reproducing information on a recording medium is disposed near a recording medium. The reproduction apparatus uses dirt detection information of the second optical system in the optical system dirt detector as detection information of the dirt state of the recording medium or the first optical system.

DESCRIPTION OF EMBODIMENTS FIG. 2 shows an embodiment of the present invention. In FIG. 2, the same numbers as in FIG. 1 indicate the same things.

In FIG. 2, the output of the dust sensor 18 is
A sensor output processing circuit 19 performs circuit processing, and the processed output is supplied to a display signal output terminal 20.
In the sensor output processing circuit 19, for example, a level where dust is detected is processed as a high level, and a level where no dust is detected is processed as a low level. The signal supplied to the display signal output terminal 20 can be used, for example, to light up a dirt indicator lamp, or if the device has a microcomputer, it can be used to notify the microcomputer and process it. .

When a signal is output to the display signal output terminal 20, various methods can be considered for processing or displaying the dirt status of the optical system or disk using that signal, but the method of detection by the dust sensor 18 is the key to the present invention. Since it is important for stable operation of the system, the dust sensor 18 will be explained in more detail next.

FIG. 3 shows a perspective view of one embodiment of the dust sensor 18.

In FIG. 3, light emitted from a light emitter 21 passes through a glass plate 23, a light receiving window 24, and enters a light receiver 22. The emitted light beam 25 is obliquely incident on the glass plate 23 as shown. The light receiving window 24 is made of glass, etc., and dust etc.
It is processed so that it does not fall into 2. The convex portion with the light receiving window 24 is smaller than the glass plate 23. Therefore, if the dust sensor shown in FIG. 3 is arranged vertically as shown, the glass plate 23 will come out from the convex part where the light-receiving window 24 is located, and the dust falling from above will be directly transmitted to a part of the glass plate 23. It's starting to look like it's coming. The passing point of the light beam 25 on the glass plate 23 is arranged so as to pass through the above-mentioned point on the glass plate 23 where dust and the like accumulate.

As shown in the embodiment of FIG. 3, a dust sensor is placed near the optical system or disk of the optical information recording/reproducing device at a location where the optical system or disk is likely to be more contaminated with dust or the like. .

The light beam 25 from the light emitter 21 is normally incident on the light receiver 22 with good performance, and a direct current depending on the amount of light received is sent to the sensor processing circuit 19. The light intensity of the light beam 25 decreases as dirt such as dust increases at the point where the glass plate 23 passes.
The output of the light receiver 22 begins to decrease. The sensor processing circuit 19 monitors the amount of decrease in the output current of the light receiver 22, and if the decrease exceeds a certain amount, it determines that dirt has become more severe due to dust, etc., and changes the signal sent to the display signal output terminal.

By taking measures against temporal changes and temperature changes in the light receiver 21, the light receiver 22, etc., such a sensor can be operated more stably. This countermeasure can be realized, for example, by performing power servo of the light receiver 21 using reflected light from the glass plate 23.

When a dirt detection signal appears on the display signal output terminal 20, and the dirt indicator lamp lights up or an appropriate display is made by the microcomputer, the user of this device can clean the optical system of the device, clean the disk, and clean the dirt according to the present invention. Clean the sensor 18.

As mentioned above, one of the characteristics of optical information recording and reproducing devices is that cleaning the optical system and recording medium is generally easy, and there is no deterioration of the recorded information. This means that it can be returned to its initial state of good performance.

Effects of the Invention As explained above, by using the present invention, it is possible to prevent information from deteriorating due to dust, etc. in an optical information recording/reproducing device that uses a light source such as a laser, and to use the device in a high-quality condition at all times. It can have great effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional optical recording and reproducing apparatus for recording and reproducing still images, FIG. 2 is a block diagram of an optical recording and reproducing apparatus according to an embodiment of the present invention, and FIG. 3 is a block diagram of the same embodiment. FIG. 2 is a perspective view of a specific example of an optical dirt detector in FIG. 4... Semiconductor laser, 10... Disk, 18
...dust sensor, 19...sensor output processing circuit, 21...sensor light emitter, 22...sensor light receiver, 23...glass plate.

Claims (1)

[Scope of Claims] 1. A first optical system using a light source such as a semiconductor laser is configured to record and/or reproduce information on a recording medium such as a disk-shaped recording medium, and is configured to record and/or reproduce information on a recording medium such as a disc-shaped recording medium, An optical system dirt detector having a second optical system different from the first optical system is arranged, and the dirt detection information from the optical system dirt detector is used to detect the dirt state of the first optical system. An optical information recording/reproducing device characterized in that the detection means is used as a detection means. 2. An optical information recording and reproducing device characterized in that the optical dirt detector is an optical dirt detector that combines a light emitting diode, a light-transmissible dust accumulation plate, and a light receiver.