JPS6355737A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To minimize deterioration due to the reproduced light of a recording medium and to contrive to improve C/N in a reproduction mode by switching the waveform of light in a recording mode and that in the reproduction mode. CONSTITUTION:In the recording mode a recording laser 12 is driven, and a recording layer wavelength lambda1 is set close to the absorption maximum 800-90nm. On the other hand, in the reproduction mode a reproduction laser 14 is driven, and a reproduction laser wavelength lambda2 is set close to the reflection maximum 600-700nm. A control circuit not shown in figure switches laser in the recording and reproduction modes. Thus the deterioration due to the reproduced light of the recording medium can be minimized, and the C/N of a signal in the reproduction mode is improved. On top of that, the service life of the recording medium can be prolonged. In the recording mode optical energy is exploited at most, and sensitivity in the recording mode is enhanced.

Description

[Detailed description of the invention] [Industrial application field] The present invention irradiates an optical information recording medium with light.

Regarding an optical information recording/reproducing device that records and reproduces information, in detail, light from a laser or the like is focused into a minute light beam with a diameter of approximately 1=1 by using a lens, etc., and is irradiated onto an optical information recording film to form a light beam on the recording surface. Optical information recording/reproduction that records information signals at high density by changing the state of the information, and then reproduces the recorded signals by detecting changes in the state using light with a lower intensity than during recording. Regarding equipment.

[Prior Art] Conventionally, as an example of the above-mentioned optical information recording and reproducing apparatus, a method has been proposed in which a rotating optical disk is irradiated with a laser beam having the small beam diameter.

In this apparatus, a predetermined signal is recorded on the optical disk using the energy of the laser beam by intensity modulating the laser beam irradiated onto the optical disk with a recording signal. - On the other hand, to reproduce a signal, a recorded signal is reproduced by irradiating a laser beam of a constant intensity onto a signal recording area of an optical disc and detecting a change in reflected light or transmitted light from the optical disc. As such recording and reproducing apparatuses, write-once type and rewritable type are conventionally known.

As a write-once recording and reproducing method, the thermal energy of the irradiated laser is used to locally evaporate the recording film and form bits (holes) to record the signal. A common method is to reproduce the recorded signal by detecting the change in the state using weak light.

Further, as a non-rewritable upper type recording and reproducing method, there is, for example, a magneto-optical recording method. In this method, information is recorded by irradiating a magneto-optical recording medium with a laser beam modulated by a recording signal and making the direction of magnetization of that part opposite to that of the surrounding area. During reproduction, a continuous laser beam is irradiated onto the recording medium, and information is detected using the magnetic Kerr effect in which the plane of polarization of the reflected light from the recording medium rotates according to the magnetization direction.

[Problems that R-Ming attempts to solve] However, in the conventional write-once method described above, since the same wavelength of laser is used for both recording and reproduction, the temperature of the recording RWA rises during reproduction and recording deteriorates. There was a drawback. In particular, when organic dyes were used as recording materials, the deterioration was remarkable.

Further, even in a rewritable type such as a magneto-optical recording device, there is a problem in that repeated irradiation with reproduction light causes fatigue deterioration of the magneto-optical recording film, which lowers the S and /N of the recorded signal.

[Means for Solving the Problems] In view of the problems of the prior art described above, an object of the present invention is to provide an optical information recording/reproducing device that can prevent deterioration of an optical information recording film due to irradiation with reproduction light. There is a particular thing.

The purpose of the above is to irradiate light onto an optical information recording medium to record, record, and reproduce information in an optical information recording/reproducing device. This is achieved by an optical information recording/reproducing device characterized by having means for switching.

- Specifically, the reproduction destination may be set to a wavelength that has substantially less influence on deterioration of the recording medium. Note that "substantially little effect" does not mean that the light itself from the laser light source must be light that does not have a negative effect on the recording medium, but rather that there are optical elements in the optical path to the recording medium or This also includes the case where the light that is substantially irradiated onto the recording film does not cause deterioration due to a protective film or the like on the surface.

One method for reducing the influence is, for example, in a write-once type device, a method of setting the recording wavelength to the maximum absorption wavelength of the recording film of the recording medium and setting the reproduction wavelength to the maximum reflection wavelength of the recording film.

[Function] According to the optical information recording/reproducing device as described above, deterioration of the recording medium due to the reproduction light can be extremely reduced, so that the C/N of the signal during reproduction is improved.

The life of the recording medium can be extended. In addition, since the light energy can be used to the maximum during recording,
This has the advantage of improving sensitivity during recording.

[Example] Hereinafter, the optical information recording and reproducing apparatus of the present invention will be described as an example.
This will be explained in detail below.

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

In the figure, reference numerals 12 and 14 indicate lasers that emit light of wavelengths 1 and 2, respectively, and the light from these lasers is made into parallel light beams by collimator lenses 11 and 13, respectively. Reference numeral 10 denotes a gicroic mirror, which transmits light with a wavelength of 1 and reflects light with a wavelength of 2. 4
3 is a polarizing beam splitter, 3 is a two-dimensional drive type actuator, 2 is an objective lens that focuses light on the recording medium surface 1, 15 is a quarter wavelength plate, 5 is a half mirror, 6 is a focus error signal 8 is a sensor lens for condensing light onto a two-split photodiode 7 for detecting a tracking error signal.

Figure 2 is a diagram showing an example of the wavelength dependence of absorbance and reflectance of a recording medium (optical disc made of organic dye: polymethine dye). ``
The operation of the lunar device will be explained. Here, the description will be made assuming that the wavelength of the recording laser beam is 1 and the wavelength of the reproducing laser beam is 2.

The optical information recording/reproducing apparatus of the present invention drives the recording laser 12 during recording, and drives the reproducing laser 14 during reproduction. Switching of the laser during recording and reproduction is performed by a control circuit (not shown).

The laser beams emitted from the laser 12 and the laser 14 are respectively made into parallel light beams by collimator lenses 11 and 13, and then made to have the same optical path by the guichroic mirror 10. This light is polarized beam splitter 4.1/4
The light is convergently projected onto the optical disk by the objective lens 2 held in the two-dimensional drive type actuator 3 through the wavelength plate 15, and forms a light beam spot on the recording film surface l.

The light reflected by the optical disk passes through the objective lens 2.1/4 again.
The light passes through the wavelength plate 15, is reflected by the polarizing beam splitter 4, and is split into two beams by the half mirror 5. The beam passing through the half mirror 5 is focused by a sensor lens 6 onto a two-split photodiode 7 for detecting a focus error signal, and a conventionally known focus error signal is detected in response to the movement thereof. Further, the reflected beam is focused by a sensor lens 8 onto a two-split photodiode 9 for detecting a tracking error signal, and a conventionally known tracking error signal is detected in accordance with the movement thereof. Furthermore, a reproduction signal of the signal recorded on the optical disk is obtained by the photodiode 7 or 9.

As described above, FIG. 2 is a diagram showing an example of the wavelength (horizontal axis) dependence of the absorbance (right vertical axis) and reflectance (left vertical axis) of an optical disc.

When using a disk with this characteristic, if the recording laser beam I is set at 800 to 900 nm near the absorption maximum,
Light-to-thermal conversion is performed efficiently, and recording becomes convoluted with low laser power.

On the other hand, the reproduction laser wavelength input 2 is 600 to 7, which is near the reflection maximum.
If set to 00nm, sufficient reproduction signal strength can be obtained even if the reproduction laser output is reduced, and the absorbance is small.
Thermal deterioration of the i-film is less likely to occur.

For example, in the above example, the recording laser 12 has a wavelength of 8
A 30 nm semiconductor laser may be used, and the reproducing laser 14 may be a He-Ne laser with a wavelength of 9633 nm, or a semiconductor laser that emits light as close to 600 nm as possible.

As described above, by setting the recording wavelength input 1 and the reproduction wave injection 2 near the maximum absorbance and the maximum reflectance, respectively, the reproduction wavelength can be set at 830n.

m, reproduction power 2 mW'? ? The one whose recording disappears after 100 reproductions has a reproduction wavelength of 633 nm and a reproduction power of 2 mW.
Even if you play more than 10,000 pages, the recording is now saved.

The present invention is not limited to the above-mentioned embodiments, and various modifications and applications are possible.

For example, a variable wavelength laser may be used in place of the recording laser in FIG. It is also possible to use an optical system ''7 in which the microink mirror IO is omitted. In this case, the recording wavelength and the reproduction wavelength are made variable so that they can be set depending on the characteristics of the recording medium (not limited to write-once optical recording media, but also includes replaceable optical recording media). If you keep it, it will be more versatile,
More preferred.

Note that when setting according to the characteristics of the recording medium, it is necessary to consider not only the absorption and reflection characteristics of the recording film itself, but also the characteristics including the protective resin film of the optical disc.

[Effects of the Invention] As explained above, according to the optical information recording and reproducing apparatus of the present invention, by switching the wavelength of light during recording and the wavelength of light during reproduction, deterioration of the recording medium by the reproducing light can be prevented. It is possible to significantly reduce the amount of noise, thereby achieving an improvement in C/N during reproduction. Furthermore, the sensitivity during recording can also be improved at the same time.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an optical information recording/reproducing apparatus of the present invention, and FIG. 2 is a diagram showing an example of wavelength dependence of absorbance and reflectance of a recording medium. Optical information recording film 2: Objective lens 3: Two-dimensional drive type actuator 4.5: Half mirror 6, 8: Sensor lens 7: Two-split photodiode for detecting focusing error signal 9 Two-split photodiode for detecting tracking error signal 10: Dichroic mirror 11. 13: Collimator lens 12. 14: Laser light source 15: 1/4 wavelength plate Agent Patent attorney Jo Yamashita Taira Kaigara-t ㅅ; Sir 2

Claims (3)

[Claims] (1) An optical information recording and reproducing device that records and reproduces information by irradiating light onto an optical information recording medium, characterized by having means for switching the wavelength of light during recording and the wavelength of light during reproduction. An optical information recording and reproducing device. (2) The wavelength during recording is set to the maximum absorption wavelength of the recording film of the recording medium, and the wavelength during reproduction is set to the maximum reflection wavelength of the recording film. Optical information recording and reproducing device. (3) The optical information recording/reproducing apparatus according to claim 1, wherein the light used during reproduction has a wavelength that has substantially little effect on deterioration of the recording medium.