JPH0749623Y2 - Optical information recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information by using laser beams of two different wavelengths.

<Prior Art> As a method of increasing the amount of information in an optical information recording / reproducing apparatus, there is a method of reducing the size of pits as information provided on an information recording medium to increase the number of pits. The size of the pit is reduced by shortening the wavelength of the laser beam with which the information recording medium is irradiated. In order to provide such small pits or pits of normal size on the information recording medium, and to reproduce information from these pits, a laser beam with a wavelength corresponding to the size of each pit is recorded. It is necessary to irradiate the medium.

As an optical information recording / reproducing apparatus for recording / reproducing information by irradiating an information recording medium with laser beams of two different wavelengths, a pickup for irradiating a laser beam of a normal wavelength and a short wavelength It is known that two pickups for irradiating a laser beam are separately arranged.

<Problems to be Solved by the Invention> However, the conventional optical information recording / reproducing apparatus described above
Since the two pickups are provided, there is a problem that the size of the entire apparatus becomes large and the cost becomes high.

Therefore, an object of the present invention is to record and reproduce information by irradiating an information recording medium with a laser beam having a normal wavelength and a laser beam having a short wavelength with one pickup, and it is inexpensive and has a small optical size. An object is to provide an information recording / reproducing device.

<Means for Solving the Problems> In order to achieve the above object, the present invention irradiates an information recording medium with laser beams having two different wavelengths to record information on the information recording medium. In an optical information recording / reproducing apparatus for reproducing information recorded on a recording medium, one laser beam source for emitting laser beams of two different wavelengths, a first wavelength and a second wavelength, and a laser emitted by the laser beam source. A reflection / transmission element that reflects and transmits the beam; a first organic dye film that passes only the laser beam of the first wavelength among the laser beams reflected by the reflection / transmission element; and a laser beam that passes through the reflection / transmission element. A second organic dye film that passes only the laser beam of the second wavelength, and a laser beam of the first wavelength that passes through the first organic dye film. And a second condensing element for condensing the laser beam of the second wavelength, which has passed through the second organic dye film, on the information recording medium. It is characterized by that.

<Operation> One laser beam source emits two different laser beams of the first wavelength and the second wavelength. Then, the laser beam emitted from the laser beam source is reflected and transmitted by the reflection / transmission element. Next, of the laser beam reflected by the reflective / transmissive element, only the laser beam of the first wavelength is passed by the first organic dye film, while only the laser beam of the second wavelength is transmitted by the reflective / transmissive element. Through the second organic dye film. And
The first focusing element focuses the laser beam of the first wavelength that has passed through the first organic dye film on the information recording medium. Also,
The second focusing element focuses the laser beam of the second wavelength that has passed through the second organic dye film on the information recording medium. In this way, it is possible to irradiate the information recording medium with laser beams of two different wavelengths to form pits of two different sizes on the information recording medium, and to reproduce the information of these pits.

<Embodiment> Hereinafter, the present invention will be described in detail with reference to an illustrated embodiment.

In FIG. 1, 1 is an optical disc as an information recording medium, 2 is arranged so as to face the optical disc 1, the optical disc 1 is irradiated with laser beams of two different wavelengths, and the laser beam is emitted according to the wavelength of the laser beam. This is a pickup that records pits as information on the optical disc 1 while reproducing information from the recorded pits.

The pickup 2 has a semiconductor laser 3 which simultaneously emits and emits laser beams of two different wavelengths, a first wavelength and a second wavelength. As the semiconductor laser 3, for example, a type in which a longitudinal mode is changed to a multimode can be used. Such a technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-155537. In addition, in order to obtain good characteristics and reliability in this type of semiconductor laser, a plurality of current injection electrode regions for injecting current into the laser active layer are provided with various widths and lengths. There is known a structure in which the small electrode regions are connected (Japanese Patent Laid-Open No. 57-36887). It is also known that a semiconductor laser device that forms an internal cavity mode with two end faces has a reflecting mirror facing one end face to form not only the internal cavity mode but also the external cavity mode, thereby forming a multimode. (JP-A-61-214145). These can also be adopted as the semiconductor laser. The radial laser beam emitted from the semiconductor laser 3 is collimated by the collimator lens 5 and is incident on the reflection / transmission element 6. This reflective / transmissive element 6
Is designed to transmit the incident laser beam in the same direction as the incident direction and reflect it in the direction perpendicular to the incident direction. The reflective / transmissive element 6 includes a first organic dye film 7 that absorbs a laser beam having a second wavelength and transmits a laser beam having a first wavelength among the reflected laser beam, and a first organic dye film 7 that transmits the laser beam having the first wavelength. A second organic dye film 8 which absorbs a laser beam of one wavelength and transmits a laser beam of a second wavelength is attached. As the materials for the first organic dye film 7 and the second organic dye film 8, phthalocyanine-based pigments, induslen-based dyes, polycyclic-based pigments, naphthol-based pigments, acetoacetic alinide-based coloring agents, etc. are vaporized. Then, a film formed (typically by vapor deposition) can be used. The types of dyes are set in accordance with the wavelengths to be transmitted by the first organic dye film 7 and the second organic dye film 8. Such a technique is disclosed in, for example, Japanese Patent Laid-Open No. 58-34961. The laser beam of the first wavelength transmitted through the first organic dye film 7 is a reflection element.
The light is reflected at a right angle by 10 and travels in a direction parallel to the transmitted laser beam, and is incident on the first condensing element 11. On the other hand, the laser beam of the second wavelength that has passed through the second organic dye film 8 travels straight to enter the second condensing element 12. The first light condensing element 11 and the second light condensing element 12 are driven by the first driving device 14 and the second driving device 15, respectively, and focus the incident parallel light on the pit portion of the optical disk. The first driving device 14 and the second driving device 15 drive the first and second condensing elements in synchronization with the movement of the pit portion so that the laser beam is accurately focused on the pit portion of the optical disc 1. It is like this. The laser beam of the first wavelength focused on the pit portion by the first focusing element 11 is
It is reflected at this pit and travels in the opposite direction along the incident path to the first
After passing through the condensing element 11 and being reflected by the reflecting element 10, the first
The light passes through the organic dye film 7 and the reflective / transmissive element 6 and enters the spot lens 16. On the other hand, the laser beam of the second wavelength focused on the pit portion by the second focusing element 12 is
It is reflected by this pit and travels in the opposite direction on the incident path to the second
After passing through the light collecting element 12 and the second organic dye film 8,
The light is reflected by the reflective / transmissive element 6 in the right angle direction and enters the spot lens 16. The laser beams of the first wavelength and the second wavelength which are incident on the spot lens 16 are
After being converged by 16, it is further converged by a cylindrical lens 17 and enters a prism 18. The prism 18 separates the laser beam in which the first wavelength and the second wavelength are mixed into laser beams of respective wavelengths, and irradiates the photodetector 20 with the laser beam. The photodetector 20 has a light receiving surface 21 for receiving the laser beam of the first wavelength and a light receiving surface 22 for receiving the laser beam of the second wavelength. The photodetector 20 converts the light information received by the light receiving surfaces 21, 22 into an electric signal. Has become.

In the above configuration, the laser beams of the first wavelength and the second wavelength emitted from the semiconductor laser 3 are collimated by the collimator lens 5 and are incident on the reflection / transmission element 6. Of the laser beam reflected by the reflective / transmissive element 6, only the laser beam of the first wavelength is used for the first organic dye film 7
After passing through and being reflected by the reflecting element 10, the first condensing element 11
Thus, the light is focused on a pit portion having a size corresponding to the first wavelength of the optical disc 1. On the other hand, of the laser beams transmitted through the reflective / transmissive element 6, only the laser beam of the second wavelength passes through the second organic dye film 8 and then the second condensing element 12
Thus, the light is focused on a pit portion having a size corresponding to the second wavelength of the optical disc 1. The information on each pit is read by the laser beam focused on each pit. The laser beam of the first wavelength and the laser beam of the second wavelength which read the information of each pit are incident on the spot lens 16 as described above. The laser beam in which the two wavelengths are mixed is converged by the spot lens 16 and the cylindrical lens 17, and then separated by the prism 18 into the laser beam of the first wavelength and the laser beam of the second wavelength. Then, the laser beam of the first wavelength and the laser beam of the second wavelength are respectively received by the light receiving surface 21 and the light receiving surface 22 of the photodetector 20, and the optical information thereof is converted into an electric signal.

In this way, one semiconductor laser 3 provided in the pickup 2 emits laser beams of two different wavelengths, that is, the first wavelength and the second wavelength, and the laser beam is reflected by the reflection / transmission element 6 and transmitted therethrough. Of the reflected laser beam, only the laser beam of the first wavelength is passed through the first organic dye film 7, and the passed laser beam of the first wavelength is focused on the optical disc 1 by the first focusing element 11. Of the transmitted laser beam, only the laser beam having the second wavelength is passed through the second organic dye film 8, and the passed laser beam having the second wavelength is passed through the second condensing element 12.
Since the optical disc is focused on the disc 1, one pickup can irradiate the optical disc with laser beams having two different wavelengths to record / reproduce information, and reduce the size of the entire device. You can

<Effect of Device> As is apparent from the above, in the optical information recording / reproducing device of the present invention, one laser beam source emits laser beams of two different wavelengths, the first wavelength and the second wavelength, and The reflection / transmission element reflects and transmits the laser beam emitted from the beam source, and the first organic dye film passes only the laser beam of the first wavelength among the laser beams reflected by the reflection / transmission element. The first condensing element focuses the laser beam of one wavelength on the information recording medium, while the second organic dye film passes only the laser beam of the second wavelength among the laser beams transmitted by the reflective / transmissive element, Since the second condensing element condenses the passed laser beam of the second wavelength on the information recording medium, one device can generate laser beams of two different wavelengths. Information can be recorded / reproduced by irradiating the information recording medium with a beam, and the size of the entire apparatus can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the optical information recording / reproducing apparatus of the present invention. 1 ... Optical disc, 2 ... Pickup, 3 ... Semiconductor laser, 6 ... Reflective / transmissive element, 7 ... First organic dye film, 8 ... Second organic dye film, 11 ... First condensing element, 12 ...
… Second condensing element.

Claims (1)

[Scope of utility model registration request] 1. An optical information recording / reproducing apparatus for irradiating an information recording medium with laser beams having two different wavelengths to record information on the information recording medium, while reproducing the information recorded on the information recording medium. A laser beam source that emits laser beams of two different wavelengths, a first wavelength and a second wavelength, a reflective transmission element that reflects and transmits the laser beam emitted by the laser beam source, and the reflective transmission element First of the laser beams reflected by
A first organic dye film that allows only a laser beam of a wavelength to pass therethrough;
A second organic dye film that allows only a laser beam having a wavelength to pass therethrough; a first condensing element that condenses the laser beam having a first wavelength that has passed through the first organic dye film onto the information recording medium; An optical information recording / reproducing apparatus comprising: a second condensing element that condenses a laser beam having a second wavelength that has passed through the organic dye film onto the information recording medium.