JPH04105824U - Magneto-optical recording medium inspection device - Google Patents

Abstract

(57) [Summary] [Purpose] Simultaneously erases data from magneto-optical recording media and inspects for defects such as damage. [Structure] A laser diode 2 irradiates a magneto-optical disk 6 with laser light to erase data recorded on the magneto-optical disk 6. The reflected light obtained at that time is detected by photodetection circuits 9 and 10. The detected reflected light is compared with a predetermined reference value by comparators 15 and 17. If the comparison result is higher than a predetermined reference voltage, it is determined that the magneto-optical disk has a defect such as damage.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea is a magneto-optical recording medium inspection system that inspects magneto-optical disks for defects such as damage. Regarding the location.

0002

[Conventional technology]

The magneto-optical disks currently in use cannot be overwritten. For this reason When recording new data on a magneto-optical disk that already has data recorded on it. must be erased once before use.

0003 Erasing of the magneto-optical disk can be performed all at once using an electromagnet or the like. deer However, TbFeC, which is currently the most commonly used material for magneto-optical disks, O has a very large holding force, so depending on its composition, it can be used as an electromagnet of about 20KOe. The data recorded on the magneto-optical disk cannot be erased all at once. There is also one.

0004 In this case, to erase data recorded on the magneto-optical disk, Use a disk driver to drive the tracks of the magneto-optical disk from the inner or outer circumference. The magneto-optical disk is irradiated with a laser beam for erasing all tracks.

[0005] Also, when inspecting the magneto-optical disk for damage, etc., use the magneto-optical disk driver. All tracks on the magneto-optical disk can be tracked in order from the inner or outer track using A laser beam is irradiated to the area for inspection.

[0006]

[Problem that the idea aims to solve]

However, since the storage capacity of magneto-optical disks is large, several hundred MB, A magneto-optical disk driver is used to erase data recorded on the disk. Use It takes a very long time to irradiate a magneto-optical disk with a laser beam for erasing. do.

[0007] Similarly, it takes a long time to inspect magneto-optical disks for damage, etc. . Conventionally, erasing and inspection are performed separately, which is extremely inefficient. It was something.

[0008] This idea is based on erasing data recorded on magneto-optical disks and magneto-optical disks. The purpose of this is to enable simultaneous inspection of defects such as damage to blocks.

[0009]

[Means to solve the problem]

The magneto-optical recording medium inspection device according to the first invention applies a predetermined magnetic field to the magneto-optical recording medium. A means for generating a magnetic field to apply a predetermined magnetic field to the magneto-optical recording medium to which the predetermined magnetic field is applied. A laser that irradiates laser light to erase data recorded on the magneto-optical recording medium. a light receiving means for receiving reflected light from the magneto-optical recording medium irradiated with the laser light; , comparing the amount of reflected light received by the light receiving means with a predetermined threshold level. From the comparison means and the comparison results of the above comparison means, defects such as damage to the magneto-optical recording medium can be determined. The device is characterized in that it includes a detection circuit that detects defects.

0010 The magneto-optical recording medium inspection device according to the second invention applies a predetermined magnetic field to the magneto-optical recording medium. A means for generating a magnetic field to apply a predetermined magnetic field to the magneto-optical recording medium to which the predetermined magnetic field is applied. A laser that irradiates laser light to erase data recorded on the magneto-optical recording medium. The light source splits the reflected light from the magnetic recording medium irradiated with the laser light into two beams. Polarizing beam splitter, two beams split by the above polarizing beam splitter Two light receiving means that receive the reflected light of the bundle, and two light receiving means that receive the reflected light of the bundle. A calculation means for calculating the difference between the two reflected light amounts, and a difference signal calculated by the above calculation means. A comparison means for comparing with a predetermined threshold level, and a comparison result of the above comparison means. The present invention is characterized in that it is equipped with a detection circuit for detecting defects such as damage to the magneto-optical recording medium. be a sign.

[0011] The magneto-optical recording medium includes a spindle motor that rotates the magneto-optical recording medium. The laser light source and the light receiving means or two light receiving means while rotating the medium. is preferably moved from the inner circumference to the outer circumference or from the outer circumference to the inner circumference of the magneto-optical recording medium.

0012 The threshold of the above comparison means corresponds to the intensity of the laser light output from the above laser light source. It is preferable to change the value level.

[0013]

[Effect]

According to the first idea, a predetermined magnetic field is applied to the magneto-optical recording medium by a magnetic field generating means. It will be done. Erasing data recorded on a magneto-optical recording medium using a laser light source The magneto-optical recording medium is irradiated with laser light for this purpose. This allows the data to be recorded on the magneto-optical recording medium. The recorded data will be deleted.

[0014] The light receiving means receives the reflected light from the magneto-optical recording medium, and the amount of received light and a predetermined threshold are determined. is compared with the new value. If the magneto-optical recording medium has a defect such as damage, the defect is As the reflectance changes at a certain location, the amount of light received by the light receiving means may be large or small. Become. Therefore, defects such as damage to the magneto-optical recording medium can be detected from the comparison results.

[0015] With the second idea, a predetermined magnetic field is applied to the magneto-optical recording medium by the magnetic field generating means. available. Erases data recorded on a magneto-optical recording medium using a laser light source. The magneto-optical recording medium is irradiated with a laser beam for recording. This makes magneto-optical recording media The recorded data will be erased.

[0016] The reflected light from the magneto-optical recording medium is split into two beams by a polarizing beam splitter. be done. The divided reflected light is received by two light receiving means, and the difference in the amount of light between them is detected. is calculated by the calculation means. The calculated difference in light amount is a magneto-optical signal. Calculation The difference in the amount of light obtained is compared using a predetermined threshold.

[0017] If there is a defect such as damage on the magneto-optical recording medium, perform a reaction at the location of the defect. Since the polarization plane of the emitted light changes significantly, the amount of magneto-optical signals obtained from the calculation means also increases. It changes a lot. Inspecting magneto-optical recording media based on comparison results between magneto-optical signals and predetermined levels will be carried out.

[0018]

【Example】

Figure 1 shows an embodiment of this invention, and is a block diagram of a magneto-optical disk inspection device. It is. Figures 2(A), (B) and 3(A), (B) show the output of the circuit block shown in Figure 1. This shows the power voltage waveform.

[0019] The magneto-optical disk 6 is rotated by a spindle motor 32. Also magneto-optical A magnetic head 31 driven by a magnetic head drive circuit 30 drives the disk 6. A constant magnetic field is given.

[0020] A laser diode is used to erase data recorded on the magneto-optical disk 6. Contains code 2.

[0021] Laser diode 2 is driven by laser diode drive circuit 1 . The laser light emitted from the laser diode 2 is collimated by the collimating lens 3. The collimated light is applied to the beam shaping prism 4. beam shaping prism 4 makes the cross section of the collimated light circular.

[0022] The collimated light shaped by the beam shaping prism 4 is sent to the beam splitter 5. The light is reflected by the magneto-optical disk 6 and irradiated onto the magneto-optical disk 6. From this, it is recorded on the magneto-optical disk 6. The recorded data will be deleted.

[0023] The collimated light irradiated onto the magneto-optical disk 6 is reflected, and the reflected light becomes a beam. The signal is transmitted through a wave splitter 5 and applied to a 1/2 wavelength plate 7. By the 1/2 wavelength plate 7 Therefore, the polarization plane of the reflected light from the magneto-optical disk 6 is rotated by 45 degrees. The opposite side of the magneto-optical disk 6 The emitted light is further applied to a polarizing beam splitter 8, which separates two beams for each polarization component. It is divided into bundles.

[0024] The two divided light beams are given to photodetector circuits 9 and 10, and the respective incident light beams are A current corresponding to the amount of light is output. The output current of photodetector circuits 9 and 10 is current voltage It is applied to conversion amplifier circuits 11 and 12 and converted into a voltage.

[0025] The output voltages of current-voltage conversion amplifier circuits 11 and 12 are sent to addition circuit 13 and subtraction circuit 14. given, the sum and difference of input voltages as shown in Figure 2(A) and Figure 3(A) are obtained. It will be done. Here, the differential voltage represents the magneto-optical signal of the magneto-optical disk 6. If the disc 6 is in an unrecorded state, there will be only a constant DC component. Output from adder circuit 13 The sum voltage output from the subtraction circuit 14 is sent to the comparator 15, and the difference voltage output from the subtraction circuit 14 is sent to the comparator 15. data 17 respectively.

[0026] Comparator 15 receives a predetermined reference voltage from reference power supply 16, and comparator 17 receives a predetermined reference voltage from reference power supply 16. A predetermined reference voltage from a reference power source 18 is applied to each of them. These reference voltages can be changed depending on the intensity of the emitted light from the laser diode 2.

[0027] Comparator 15 compares the reference voltage with the input sum voltage. If the input sum voltage is higher than the reference voltage, a defect signal as shown in Figure 2(B) will be output. be done. This defect signal is given to the defect measurement circuit 20, and is detected by the defect measurement circuit 20. The presence or absence of damage to the magneto-optical disk 6, the number and size of damage, etc. are detected.

[0028] Also, comparator 17 compares the reference voltage and the input differential voltage. If the input differential voltage is higher than the reference voltage by comparison, a defect signal as shown in Figure 3(B) will be generated. is output. This defect signal is given to the defect measuring circuit 21, and this defect measuring circuit 21 The presence or absence of damage to the magneto-optical disk 6, the number of damage, the size of damage, etc. are detected by this.

[0029] While the magneto-optical disk 6 is rotating, all tracks on the magneto-optical disk 6 are Data is erased and inspected for defects.

[0030] In this way, the recorded data on the magneto-optical disk 6 can be erased and its defects inspected. They will be held at the same time.

[0031]

[Effect of the idea]

According to the first idea, data is recorded on a magneto-optical recording medium by a laser diode. The magneto-optical recording medium is irradiated with a laser beam to erase the data stored in the magneto-optical recording medium. The data recorded on the recording medium will be erased. Light obtained when erasing data The reflected light from the magnetic recording medium can be used to inspect magneto-optical recording media for defects and erase data. be able to do it at the same time.

[0032] Therefore, erasing data from magneto-optical recording media and detecting defects in magneto-optical recording media are essential. You will be able to conduct inspections more efficiently. Especially output when erasing data on magneto-optical recording media. The intensity of the laser beam output during playback is greater than that of the laser beam output during playback. A large amount of reflected light can be obtained, and the accuracy of inspecting defects in magneto-optical recording media can also be improved.

[0033] The second invention also allows recording on a magneto-optical recording medium using a laser diode. A laser beam is irradiated onto the magneto-optical recording medium to erase the data stored in it. The data recorded on the magneto-optical recording medium is erased. from magneto-optical recording media The reflected light is split into two by a polarizing beam splitter, and the difference between them is detected.

[0034] If there is a defect such as damage on the magneto-optical recording medium, it will be biased at the location of the defect. Since the facing surface changes, the amount of light received by the light receiving means increases. For this reason, the comparison results show that magneto-optical Defects such as damage to the recording medium are detected.

[0035] Also in the second invention, erasure of data on optical recording media and defects in magneto-optical recording media will be able to perform inspections more efficiently.

[0036] In particular, according to the second idea, the difference signal obtained from the reflected light from the magneto-optical recording medium Because it inspects magneto-optical recording media, it is possible to perform highly accurate inspections. I'm going to growl.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of this invention, and is a block diagram of a magneto-optical disk inspection apparatus.

[Figure 2] (A) shows the output waveform of the adder circuit shown in Figure 1, and (B) shows the output waveform of the adder circuit shown in Figure 1.
shows the output waveform of the comparator shown in FIG.

[Figure 3] (A) shows the output waveform of the subtraction circuit shown in Figure 1, and (B) shows the output waveform of the subtraction circuit shown in Figure 1.
shows the output waveform of the comparator shown in FIG.

[Explanation of symbols]

2 Laser diode 6 Magneto-optical disk 8 Polarizing beam splitter 9,10 Photodetection circuit 15, 17 comparator 16, 18 Defect measurement circuit 32 spindle motor

Claims (4)

[Scope of utility model registration request] Claim 1: A magnetic field generating means for applying a predetermined magnetic field to a magneto-optical recording medium, irradiating the magneto-optical recording medium to which the predetermined magnetic field is applied with a predetermined laser beam, and recording on the magneto-optical recording medium. a laser light source for erasing data contained in the data, a light receiving means for receiving reflected light from the magneto-optical recording medium irradiated with the laser light, and a comparison means for comparing the amount of reflected light received by the light receiving means with a predetermined threshold level. , and a detection circuit for detecting defects such as damage in the magneto-optical recording medium from the comparison results of the comparison means. 2. A magnetic field generating means for applying a predetermined magnetic field to a magneto-optical recording medium, irradiating the magneto-optical recording medium to which the predetermined magnetic field is applied with a predetermined laser beam, and recording on the magneto-optical recording medium. a laser light source for erasing the data contained in the data; a polarizing beam splitter for splitting the reflected light from the magneto-optical recording medium irradiated with the laser beam into two beams;
two light receiving means that receive the reflected light of the two beams split by the splitter; a calculating means that calculates the difference between the two amounts of reflected light received by the two light receiving means; and a difference signal calculated by the calculating means. What is claimed is: 1. A magneto-optical recording medium inspection apparatus, comprising: a comparison means for comparing a predetermined threshold level with a predetermined threshold level; and a detection circuit for detecting defects such as damage in the magneto-optical recording medium from the comparison result of the comparison means. 3. A spindle motor for rotating the magneto-optical recording medium, the laser light source and the light receiving means or two light receiving means being directed from the inner periphery of the magneto-optical recording medium while rotating the magneto-optical recording medium. 3. The magneto-optical recording medium inspection apparatus according to claim 1, wherein the magneto-optical recording medium is moved from the outer circumference or from the outer circumference to the inner circumference. 4. The magneto-optical recording medium inspection apparatus according to claim 1, wherein the threshold level of the comparison means is changed in accordance with the intensity of the laser light output from the laser light source.