JPH0682472B2 - Optical recording device - Google Patents

Description

The present invention relates to an optical recording apparatus capable of writing new information while erasing.

(B) Conventional technology A recording / reproducing apparatus for information using the magneto-optical effect, for example,
It is disclosed in JP-A-57-117106. According to this prior art shown in FIG. 5, the information signal and the address signal are recorded on the same recording track (the address signal is, for example, formed every one rotation of the disk, that is, in the one radial direction). It has been recorded in advance, and it has a structure that cannot be erased by an erasing beam). It is possible to record new information with the succeeding recording beam while erasing the recorded information with the preceding erasing beam. That is, the erasing beam and the recording beam are applied to the tracks adjacent to each other or separated from each other by two tracks or more, the address is detected by the erasing beam, and the bias magnetic field is switched for each track. It becomes possible to record new information by the recording beam while erasing the data.

By the way, in the prior art shown in FIG. 5 described above, the laser diode (1) for the erasing beam and the laser diode (2) for the recording beam are separate, which makes the device complicated and large. There's a problem. Further, during erasing / recording, the reflected light from the disk of the erasing beam and the recording beam reaches the beam splitter (3), but if the wavelengths of both beams are close, the beam splitter (3) Also, the reflected light of the recording beam that has been modulated based on the recorded information is detected by the photo sensor (4), which originally does not sufficiently separate the two beams and needs to detect the address signal by receiving only the reflected light of the erasing beam. However, there is a drawback that the address signal cannot be read accurately.

In FIG. 5, reference numeral (5) is an objective lens, and (D)
Is a magneto-optical disk, (6) is a half mirror, and (7) is a reproduction signal detecting photosensor. The laser diode (2) is also used as a reproducing beam by reducing its oscillation output. During reproduction, the reproducing beam output from the laser diode (2) is incident on the photo sensor (7). As a result, a reproduction signal can be obtained from the photo sensor (7).

(C) Problems to be solved by the present invention The present invention solves the above-mentioned drawbacks of the prior art, simplifies the structure of the optical system to downsize the device, and accurately reads the address signal at the time of recording. It is intended.

D means for solving the problems laser diode means having at least two emission points for a recording beam and an erasing beam, and a photosensor means for receiving at least reflected light or transmitted light of the erasing beam. Set up. Then, the recording beam and the erasing beam are applied to different tracks with respect to the spiral or concentric track on which the address signal and the information signal are recorded, and the reflected beam or the transmitted beam of the erasing beam is changed. The photo sensor means for detecting the address signal is arranged at a corresponding position.

By using laser diode means having at least two emission points for the operation recording beam and the erasing beam, each beam is not adjacent to the same track but adjacent (tracks separated by one pitch) or two or more tracks apart. It can irradiate a truck. The reflected light or transmitted light from the disk of the recording beam does not reach the photosensor means provided at the position corresponding to the reflected light or the transmitted light of the erase beam from the disk. Moreover, the photo sensor means is not affected by the recording beam modulated by the information to be recorded. An accurate address signal can be read.

F. Embodiment In FIG. 1, the laser diode array (10) has two emitting points and outputs an erasing beam (B ₁ ) and a recording / reproducing beam (B ₂ ). The beam passes through a collimator lens (11) and a beam splitter (12) and is focused on the magneto-optical disk (D) surface by an objective lens (13). The state is as shown in Fig. 2. The erasing beam (B ₁ )
The recording / reproducing beam (B ₂ ) preceded by and is focused on the adjacent track (T ₂ ) of the track (T ₁ ) on which the erasing beam (B ₁ ) is focused (more than 2 tracks apart). It may be focused on a truck). The address signal (A) is recorded on a specific portion (for example, on one radial line) of the disk (D) in a form that cannot be erased by the erasing beam (B ₁ ) (for example, in the form of unevenness). The information signal is magneto-optically recorded in the track (T) having a groove shape for tracking. The track (T) is formed spirally or concentrically with respect to the disk (D).

The beam reflected by the disk (D) is an objective lens (13), a beam splitter (12), a half-wave plate (14),
It reaches the polarized beam splitter (1) through the condenser lens (15). The polarized beam splitter (16) separates the polarized light components (P component and S component) based on the respective polarized light components, one through the cylindrical lens (17) and the other directly through the photo sensor means (18) (21). Reach.

The structure of the photo sensor means (18) (21) is as shown in FIG. Each of the photo sensor means (18) (21) has two photo sensors (19) (20), (22) (23). The photosensors (19) (22) are arranged at positions for receiving the erasing beam (B ₁ ), and the photosensors (20) (23) are arranged at positions for receiving the recording / reproducing beam (B ₂ ). The photo sensor (20) is a four-division photo sensor, and the photo sensor (23) is a two-division photo sensor.

Now, at the time of recording, the reflected light of the erasing beam (B ₁ ) is incident on the photosensors (19) (22), but either photosensor may derive the address signal. At this time, the reflected light of the recording beam (B ₂ ) is the photo sensor (19).
Since it is not incident on (22), an accurate address signal can be obtained. Further, the focus error signal can be obtained from the 4-division photo sensor (20) and the tracking error signal can be obtained from the 2-division photo sensor (23) as well known in the art. The reflected light of the recording beam (B ₂ ) modulated by the information signal to be recorded is incident on these photosensors (20) (23), but the recording information signal, the focus error signal and the tracking error signal Since the frequency bands differ greatly, there is no problem in detecting the focus error signal and the tracking error signal.

Further, the photo sensors (19) (22) are used as two-division and four-division photo sensors to generate a tracking error signal and a focus error signal together with an address signal (that is, a tracking error signal and a focus error signal based on the reflected light of the erasing beam). It is also possible to create an error signal),
The embodiment shown in FIG. 3 in which the focus error signal and the tracking error signal are created based on the reflected light of the recording beam applied to the track to be actually recorded is
More accurate focus error signal and tracking error signal can be obtained.

On the other hand, at the time of reproduction, by reducing the oscillation output of the laser diode (10), the reproduction beam can be obtained from the laser diode (10) instead of the recording beam. In this case, the photo sensor (20) and the photo sensor (2
Although it is possible to obtain a reproduction signal from one of 3), a reproduction signal having a good SN ratio can be obtained by the configuration in which the difference output of these is obtained from the operational amplifier (24). Further, the focus error signal and the tracking error signal can be obtained from the photo sensors (20) and (23) as in the recording. Further, the address signal is changed to an erasing beam to obtain a reproducing beam by reducing the oscillation output of the laser diode (10), and the photo sensor (19) or (2
2) The address signal can be obtained from Also, the third
An address signal may be obtained from the output side of the operational amplifier (25) shown in the figure.

FIG. 4 shows another embodiment in which only the photo sensor (18) is provided. In this case, it is possible to obtain a reproduction signal from the operational amplifier (26), a tracking error signal from (27) and a focus error signal from (28). However, as shown in FIG. 3, since the differential output of the two photosensors (20) (23) having a pushable relationship is not used, the SN ratio of the obtained reproduced signal is lowered. That is, the reproducing beam entering the polarized beam splitter (16) is polarized in the P-polarized direction or the S-polarized direction according to the recording signal, and is separated by the polarized beam splitter (16). 20) The SN ratio is doubled when the difference output of (23) is used as the reproduction signal.

The embodiment described above is an example of magneto-optical recording, but it can be applied to a type in which information is recorded by changing the reflectance or transmittance of the disk. In short, the feature of the present invention resides in that a laser diode array having two radiating points for an erasing beam and a recording beam is used and a photosensor for detecting an address signal is arranged at a position corresponding to the erasing beam. .

Effect of the Invention According to the present invention described above, the optical system is simple, the apparatus can be downsized, and an accurate address signal can be detected during recording.

[Brief description of drawings]

FIG. 1 is a diagram showing an optical recording apparatus of the present invention, FIG. 2 is a diagram showing a relationship between a beam and a track, FIG. 3 is a diagram showing a relationship between a photo sensor and a beam, and FIG. 4 is another embodiment. FIG. 5 is a diagram showing the relationship between the photo sensor and the beam in FIG. 5, and FIG. 5 is a diagram showing a conventional device. (10) is a laser diode array, (16) is a polarized beam splitter, (18) (19) (20) (21) (22) (23) is a photo sensor, (B ₁ ) is an erasing beam, and (B ₂ ) Is a beam for recording.

Claims (1)

[Claims] 1. Laser diode means having at least two emission points for a recording beam and an erasing beam,
At least a photosensor means for receiving the reflected light or transmitted light of the erasing beam from the recording medium, and erasing the recording beam with respect to the spiral or concentric track on which the address signal and the information signal are recorded The optical recording device is characterized in that the photo beam is irradiated to different tracks and the photo sensor means for detecting the address signal is arranged at a position corresponding to the reflected light or the transmitted light of the erasing beam. .