JP2002288873A - Optical information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording and reproducing device that can prevent the spot diameter from becoming large and is capable of miniaturizing. SOLUTION: The optical information recording and reproducing device of this invention has a micromirror array 4 consisting of mirrors disposed in the route of a laser beam emitted from a laser beam source 1 to change its direction. This optical information recording and reproducing device adjusts the angle of the laser beam to the field lens to correct the spherical aberration when recording and reproducing the signals on an optical disk having one or more surfaces by using the above micromirror array.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording or reproducing optical information on an optical information recording medium such as an optical disk.

[0002]

2. Description of the Related Art Hitherto, an optical disk as one of optical information recording media has been proposed which has a plurality of data surfaces. Incidentally, DVDs having a two-layer data surface have been commercialized. When recording or reproducing optical information on or from an optical disc having a plurality of data surfaces, it is necessary to focus on a desired data surface. However, conventional optical pickup devices generate spherical aberration. Spot diameter becomes large. In order to deal with this, FIG.
Optical information recording / reproducing apparatuses shown in FIG. The optical information recording / reproducing apparatus shown in FIG.
, A condenser lens 106, and a photodetector 107. The light emitting diode 101 emits a laser beam 108. Laser light 10 emitted from light emitting diode 1
8 is converted into parallel light by a collimator lens 102 and separated by a beam splitter 103. A part of the laser beam 108 separated by the beam splitter 103 is reflected by a mirror 104 and is incident on an objective lens 105 to be imaged by the objective lens 105.
The optical disk 109 is located at the image forming position of the objective lens 105.
Is arranged. The laser beam 108 formed by the objective lens 105 writes optical information on an optical disk 109 and records it. The optical disk 108 has a plurality of data surfaces. On the other hand, when reproducing the optical information recorded on the optical disk 109, the laser beam 108 emitted from the light emitting diode 101 is transmitted through the collimator lens 102, the beam splitter 103, the mirror 104, and the objective lens 105 as described above. To the objective lens 1
The light is detected by being received by a photodetector 107 via a mirror 05, a mirror 104, a beam splitter 103, and a condenser lens 106. The optical information recording / reproducing apparatus shown in FIG. 11 includes a light emitting diode 101 and a collimating lens 102.
, A beam splitter 103, a mirror 104, an objective lens 105, a condenser lens 106, and a photodetector 10.
7 and the objective lens 105 and the optical disk 109
And a spherical aberration correction plate 110 is disposed between them. The spherical aberration correction plate 110 is moved by the driving device 111.

[0003]

However, in the conventional optical information recording / reproducing apparatus shown in FIG. 10, when recording or reproducing optical information on a multi-layer optical disc, the optical information recording / reproducing apparatus is required to operate from an objective lens to a target data surface. Since the thickness of the base material of the optical disc changes for each data layer, there is a problem that a data surface having a large spot diameter is formed. In addition, the conventional optical information recording / reproducing apparatus shown in FIG. 11 needs to have a driving device, and thus has a problem that it becomes large. An object of the present invention is to provide an optical information recording / reproducing apparatus which can prevent a spot diameter from becoming large and can be downsized.

[0004]

According to a first aspect of the present invention, there is provided a micro-mirror array having a plurality of mirrors in an optical path of laser light emitted from one laser light source. The direction of the laser beam is changed by a lever micromirror array. According to a second aspect of the present invention, a micromirror array having a plurality of mirrors is arranged in an optical path of laser light emitted from a laser light source in order to compensate for spherical aberration during recording and reproduction of an optical disk having a plurality of data surfaces. Then, the radiation angle of the laser light incident on the objective lens is adjusted by the micro mirror array. According to a third aspect of the present invention, in the optical information recording / reproducing apparatus according to the second aspect, a spot measuring device is disposed at a predetermined distance from the objective lens in an image forming direction of the objective lens. A correction plate for correcting the thickness from the surface of the optical disc to the data surface between the objective lens and each of the mirrors of the micromirror array so that the spot diameter measured by the spot measuring device is minimized. The information of each mirror is stored in the optical information recording / reproducing device in a state where the angle is adjusted, and recording / reproducing of the optical disk is performed using the information. According to a fourth aspect of the present invention, in the optical information recording / reproducing apparatus according to the third aspect,
When projecting the light image from the objective lens onto the spot measuring device, one mirror of the micro mirror array is kept in a state where light from all mirrors of the micro mirror array does not enter the spot measuring device. Is rotated so that only the light reflected from the mirror enters the spot measuring device.

According to a fifth aspect of the present invention, in the optical information recording / reproducing apparatus according to the fourth aspect, when the radiation angle of the laser light is adjusted in a plurality of data layers of the optical disc, one of the optical discs is adjusted. After calculating the angle of each mirror from the data layer of the layer, the center of the optical axis on the micromirror array is obtained, and only the mirrors arranged concentrically from the center are turned on and adjusted. And According to a sixth aspect of the present invention, in the optical information recording / reproducing apparatus according to the first aspect, when recording / reproducing an optical disk having a data surface of one or more layers, the laser light emitted from the light source is By adjusting the emission angle of the laser beam incident on the objective lens using the micromirror array, a plurality of focal points are created, and a plurality of data are recorded or reproduced at one time. According to a seventh aspect of the present invention, in the optical information recording / reproducing apparatus according to the sixth aspect, the optical information recording / reproducing apparatus is point-symmetric with respect to a position of an optical axis of light incident on the micromirror array, and is always on a concentric circle. The irradiation direction of the mirror is assigned such that there is a mirror of the micromirror array corresponding to all focal points. According to an eighth aspect of the present invention, in the optical information recording / reproducing apparatus according to the sixth aspect, recording is performed by changing an angle of a mirror of the micromirror array without blinking the light source. According to a ninth aspect of the present invention, in the optical information recording / reproducing apparatus according to the first aspect, when recording or reproducing an optical disk having a plurality of data surfaces and having no optically defined data surface, Using the micromirror array to adjust the emission angle of the laser light incident on the objective lens, to create a plurality of focal points, and to generate a focus servo signal by positioning one of the focal points on the surface of the optical disc. Features. According to a tenth aspect of the present invention, in the optical information recording / reproducing apparatus according to the ninth aspect, when recording or reproducing an optical disk having a plurality of data surfaces and having no optically defined data surface, and controlling by adding the voltage value for each data surface to the focus servo error signal.

[0006]

Next, embodiments of the present invention will be described in detail with reference to the drawings. First, a first embodiment according to the first and second aspects of the invention will be described. FIG. 1 is a diagram showing a configuration of an optical information recording / reproducing apparatus according to a first embodiment of the present invention. As shown in FIG. 1, an optical information recording / reproducing apparatus according to a first embodiment of the present invention includes a light emitting diode 1, which is a laser light source, a collimating lens 2, a beam splitter 3, a micro mirror array 4, An objective lens 5, a condenser lens 6, and a photodetector 7 are provided.
The light emitting diode 1 emits a laser beam 8. The laser light 8 emitted from the light emitting diode 1 is collimated by the collimator lens 2 and separated by the beam splitter 3. A part of the laser beam 8 separated by the beam splitter 3 is reflected by the micromirror array 4 and is incident on the objective lens 5 to form an image by the objective lens 5. In the imaging position of the objective lens 5,
An optical disk 9 is arranged. The laser light 8 imaged by the objective lens 5 writes and records optical information on an optical disk 9. The optical disk 8 has a plurality of data surfaces. On the other hand, when reproducing the optical information recorded on the optical disk 9, the laser light 8 emitted from the light emitting diode 1 is transmitted through the collimating lens 2, the beam splitter 3, the micro mirror array 4, and the objective lens 5 as described above. Irradiated on the optical disk 9, the reflected light from the optical disk 9 is detected by being received by the photodetector 7 via the objective lens 5, the micro mirror array 4, the beam splitter 3, and the condenser lens 6. As shown in FIG. 2, the micromirror array 4 has a plurality of minute mirrors 4a integrated. Each of these mirrors 4a can change the angle. For example, as the micromirror array 4, there is a DMD manufactured by TEXAS INSTRUMENTS. When the mirror 4a is arranged to be inclined as shown in FIG. 3A, the micromirror array 4 can condense the diffused light and turn it into parallel light. The micromirror array 4 can diverge parallel light when the mirror 4a is arranged at an angle as shown in FIG. 3B. For this reason, in the optical information recording / reproducing apparatus shown in FIG. 1, the micromirror array 4 changes the angle of light incident on the objective lens 5 according to the data surface of the optical disk 9,
Spherical aberration can be compensated.

Next, a second embodiment according to the third, fourth and fifth aspects of the present invention will be described. FIG. 4 is a diagram showing a configuration of an optical information recording / reproducing apparatus according to the second embodiment of the present invention. In the second embodiment of the present invention, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals. As shown in FIG. 4, the optical information recording / reproducing apparatus according to the second embodiment of the present invention differs from the first embodiment of the present invention in that
A spot measuring device 10 is arranged at a predetermined distance from the objective lens 5 in the image forming direction, and a correction plate 11 is arranged between the spot measuring device 10 and the objective lens 5. The laser beam 8 emitted from the light emitting diode 1 enters the spot measuring device 10 through the correction plate 11 via the collimator lens 2, the beam splitter 3, the micro mirror array 4, and the objective lens 5 as described above. The spot measuring device 10 displays the spot narrowed down by the objective lens 5 on a spot measuring monitor 10a. Here, the micromirror array 4 is adjusted so that the spot (image) projected on the spot measurement monitor 10a is minimized. The voltage applied to each mirror 4a corresponding to the angle of each mirror 4a at this time is stored as information, and this information is stored for each data layer, and when reproducing the optical information of the optical disk 9, this information is stored. Micro mirror array 4 based on
By applying a voltage to, the spherical aberration can be corrected. At this time, the correction plate 11 used is
Therefore, the correction plate 11 must be changed for each data layer. At this time, when adjusting a plurality of mirrors 4a at a time when adjusting the mirror 4a, one mirror 4a is adjusted.
Even if a is adjusted, the change is difficult to understand and adjustment becomes difficult. Therefore, as shown in FIG. 5, when the light image from the objective lens 5 is projected on the spot measuring device 10, light from all the mirrors 4a of the micromirror array 4 is prevented from entering the spot measuring device 10. Then, one mirror 4a of the micromirror array 4 is rotated and adjusted so that only the light reflected from the mirror 4a enters the spot measuring device 10. Such an adjustment is sequentially performed on each of all the mirrors 4a of the micromirror array 4. Thereby, adjustment for a certain data layer of the optical disc 9 becomes possible.

Although this embodiment is reliable for adjusting each of the mirrors 4a, the mirror 4a for a certain layer is adjusted.
Must be adjusted by the number of mirrors 4a. For example, if the micromirror array 4 has 100
When the mirror 4a is composed of ten thousand mirrors, all the mirrors 4a must be adjusted, and the amount of work becomes enormous. Then, a mirror 4a at the center of the micromirror array 4 of the light incident on the micromirror array 4 is determined from the angle information or the applied voltage of each mirror obtained on the data surface of the first layer of the optical disk 9, and If the concentric mirrors 4a are adjusted collectively around the mirror 4a, the adjustment time can be reduced. The adjusting means first applies the angle information of each mirror 4a of the adjacent data layer of the optical disk 9 to only one mirror 4a as an initial value, and then adjusts the amount of change by the above-described method. Find out. And only to each concentric mirror 4a,
The adjustment can be performed by applying the angle information of each mirror 4a of the adjacent data layer of the optical disk 9 and the sum of the change amounts.

Next, a third embodiment according to the sixth, seventh and eighth aspects of the present invention will be described. FIG. 7 is a diagram showing a configuration of an optical information recording / reproducing apparatus according to the third embodiment of the present invention. In the third embodiment of the present invention, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals. In the optical information recording / reproducing apparatus shown in FIG. 7, a multi-beam can be obtained by allocating the angle of the reflected light of the micro mirror array 4 to a plurality of directions. FIG.
In the example shown in FIG. 7, mirrors are allocated to two focal points and adjusted. At this time, if there is a bias in the way the mirrors are allocated, there will be a difference in the spot diameter. This is because the spot diameter is governed by the wavelength of the light source and the NA of the lens, and
Is affected by the effective diameter of the incident light. Therefore,
When allocating the mirrors 4a, the mirrors 4a must be allocated such that the effective diameters of the laser beams 8 corresponding to the respective focal points become equal. For that purpose, it is only necessary that there be mirrors 4a corresponding to all the focal points concentrically around the optical axis. Thereby, the spot diameter on the data surface of the optical disk 9 can be made equal. However, since the incident light is reflected on the data surface, a mirror 4a for returning the light to the photodetector 7 is required at a position where the light emitted from a certain mirror 4a returns. On the other hand, since the mirror 4a receiving the reflected light also needs to transmit the light from the laser beam 8 to the optical disk 9, the mirror 4a that is always point-symmetric with respect to the optical axis needs to be paired. In this case, if the angle of the mirror 4a is changed instead of the blinking of the laser light 8 to control the incidence of the laser light 8 on the objective lens 5, optical information can be written. At this time, the angle of the mirror 4a must be shifted at random so that the beam does not move in the same direction and erase other data.

Next, a fourth aspect according to the present invention will be described.
An embodiment will be described. FIG. 7 is a diagram showing a configuration of an optical information recording / reproducing apparatus according to the fourth embodiment of the present invention. In the fourth embodiment of the present invention, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals. As a multilayer optical disk, there is an optical disk 9 having no optical layer configuration. Usually, in the case of the optical disk 9,
A focus servo signal is generated by an astigmatism method, a knife edge method, or the like using reflection and a refractive index difference at a boundary of a data layer. However, in the case of the optical disk 9 having no optical layer configuration, it is difficult to extract the focus servo signal because there is no boundary surface. The only boundary surface is the surface of the optical disk 9 which is an optical boundary between the air and the optical disk 9. Therefore, in the optical information recording / reproducing apparatus shown in FIG. 7, the reflected light from the micromirror array 4 is made into a multi-beam as shown in FIG. 6, and at least one beam is applied to the surface of the optical disk 9 to generate a focus servo signal. Thus, control in the optical axis direction becomes possible. For example, using a signal on the surface of the optical disk 9, focus servo is performed by an astigmatism method, a knife edge method, or the like, and the focus is always fixed on the surface of the optical disk 9. Is constant, the focal point of the optical disk 9 always traces a certain depth from the surface of the optical disk 9. As for the change of the data surface of the optical disc 9, an S-shaped signal of a focus error as shown in FIG. 8 is generated by using an astigmatism method, a knife edge method, or the like, and a voltage with respect to the depth is obtained in advance. Then, as shown in FIG. 9, by adding an offset voltage corresponding to the data plane to the focus error signal, it is possible to focus on an arbitrary data plane.

[0011]

As described above, according to the first aspect of the present invention, a micromirror array having a plurality of mirrors is arranged on the optical path of laser light emitted from one laser light source. Since the direction of the laser beam is changed by the array, it is possible to prevent the spot diameter from increasing and to reduce the size.
According to the invention described in claim 2, in addition to the effects of the invention described in claim 1, it is suitable for downsizing the device. Further, according to the invention described in claim 3 or 4, according to claim 1
In addition to the effects of the invention described in (1), the mirror of the micromirror array can be adjusted with high accuracy. According to the invention described in claim 5, in addition to the effect of the invention described in claim 1, the time for adjusting the mirrors of the micromirror array can be significantly reduced. According to the invention of claim 6, in addition to the effect of the invention of claim 1, high-speed reading of optical information is enabled by making the reflected light from the micromirror array a multi-beam, Efficiency is higher than that using a diffraction grating. According to the invention described in claim 7,
In addition to the effect of the first aspect, the spot diameter can be easily made uniform. According to the invention described in claim 8, in addition to the effect of the invention described in claim 1, writing can be performed with a multi-beam, so that high-speed recording is enabled. According to the ninth aspect of the present invention, in the first aspect,
In addition to the effects of the invention described in (1), it is possible to perform focus control of a multilayer optical disc whose data surface cannot be distinguished optically. According to the tenth aspect, in the first aspect,
In addition to the effects of the invention described in (1), it is possible to control the movement and focus between layers of a multilayer optical disc whose data surface cannot be distinguished optically.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical information recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a front view showing a micro mirror array of the optical information recording / reproducing apparatus of FIG.

FIG. 3 is a diagram for explaining an operation of a micro mirror array of the optical information recording / reproducing apparatus of FIG.

FIG. 4 is a diagram showing a configuration of an optical information recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a main part of an optical information recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 6 is another diagram showing a configuration of a main part of the optical information recording / reproducing apparatus according to the second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of an optical information recording / reproducing device according to third and fourth embodiments of the present invention.

FIG. 8 is a diagram for explaining an operation of an optical information recording / reproducing apparatus according to a fourth embodiment of the present invention.

FIG. 9 is another diagram for explaining the operation of the optical information recording / reproducing apparatus according to the fourth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of an example of a conventional optical information recording / reproducing apparatus.

FIG. 11 is a diagram showing the configuration of another example of a conventional optical information recording / reproducing device.

[Explanation of symbols]

1 light emitting diode, 2 collimating lens, 3 beam splitter, 4 micro mirror array, 5 objective lens, 6 focusing lens, 7 photodetector, 8 laser light,
9 Optical disk, 10 spot measuring device.

Claims (10)

[Claims] 1. An optical information recording apparatus comprising: a micromirror array having a plurality of mirrors arranged in an optical path of laser light emitted from one laser light source; and the direction of the laser light is changed by the micromirror array. Playback device. 2. A micro-mirror array having a plurality of mirrors arranged in an optical path of laser light emitted from a laser light source to compensate for spherical aberration during recording and reproduction of an optical disk having a plurality of data surfaces. An optical information recording / reproducing apparatus, wherein a mirror array adjusts a radiation angle of the laser light incident on an objective lens. 3. The optical information recording / reproducing apparatus according to claim 2, wherein a spot measuring device is arranged at a predetermined distance from the objective lens in an image forming direction of the objective lens, and the spot measuring device and the objective lens are arranged. A correction plate for correcting the thickness from the surface of the optical disk to the data surface is arranged therebetween, and the angle of each mirror of the micromirror array is adjusted so that the spot diameter measured by the spot measuring device is minimized. The optical information recording / reproducing apparatus, wherein information of each mirror is stored in the optical information recording / reproducing apparatus in a state where the information is read, and recording / reproducing of an optical disk is performed using the information. 4. The optical information recording / reproducing apparatus according to claim 3, wherein when projecting an optical image from the objective lens onto the spot measuring device, light from all mirrors of the micromirror array is used for the spot measurement. An optical information recording / reproducing apparatus, wherein one mirror of the micromirror array is rotated in a state where it does not enter the spot measuring device so that only light reflected from the mirror enters the spot measuring device. . 5. The optical information recording / reproducing apparatus according to claim 4, wherein when adjusting a radiation angle of the laser beam in a plurality of data layers of the optical disc, each of the plurality of data layers starts from a first data layer of the optical disc. An optical information recording / reproducing apparatus comprising: determining a mirror angle; determining a center of an optical axis on the micromirror array; and adjusting only a mirror arranged concentrically from the center. 6. The optical information recording / reproducing apparatus according to claim 1, wherein, when recording / reproducing an optical disk having a data surface of one or more layers, the laser beam emitted from the light source is transmitted to the micromirror array. An optical information recording / reproducing apparatus, wherein a plurality of focal points are formed and a plurality of data are recorded or reproduced at one time by adjusting a radiation angle of a laser beam incident on the objective lens by using the method. 7. The optical information recording / reproducing apparatus according to claim 6, wherein the optical information recording / reproducing apparatus is point-symmetric with respect to a position of an optical axis of light incident on the micromirror array, and is always concentric with all focal points. An optical information recording / reproducing apparatus, wherein an irradiation direction of the mirror is assigned so that a corresponding mirror of the micromirror array exists. 8. The optical information recording / reproducing apparatus according to claim 6, wherein the recording is performed by changing an angle of a mirror of the micro mirror array without blinking the light source. . 9. The optical information recording / reproducing apparatus according to claim 1, wherein the micromirror array is used when recording or reproducing an optical disk having a plurality of data surfaces and having no optically defined data surface. A plurality of focal points are created by adjusting a radiation angle of the laser light incident on the objective lens by using a light source, and a focus servo signal is generated by positioning one of the focal points on the surface of the optical disc. Information recording and playback device. 10. The optical information recording / reproducing apparatus according to claim 9, wherein when performing recording or reproduction on an optical disk having a plurality of data surfaces and having an optically undefined data surface, a focus servo error signal is generated. An optical information recording / reproducing apparatus, wherein the control is performed by adding a voltage value for each data surface to the data information.