KR100233115B1 - Optical pickup device - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs:

An optical disc recording and reproducing apparatus.

I. The technical problem the invention is trying to solve:

Cost reduction and data processing efficiency of optical pickup.

All. The gist of the solution of the invention:

The present invention relates to an optical pickup apparatus in an optical disk recording / reproducing apparatus, comprising: a mount mounted on a substrate, and mounted on both sides of the mount, and emitting first and second laser lights having different powers during data recording and reading data from each other. Release The first and second laser light output units emitting only one of the first and second laser lights, the first and second laser lights are focused, and the energy of the first and second laser lights that are focused are coupled. A lens unit for ringing to make light suitable for recording or reading data on a disc, a collimator lens for converting light through the lens unit into parallel rays of light, and passing incident light from the collimator lens and reflecting the reflected light in a 90 ° direction. A beam splitter for dividing the incident light and the reflected light by switching to a light beam; and detecting the reflected light converted by 90 ° from the beam splitter when data is read. And an objective lens configured to focus the incident light through the beam splitter on the disk and to reflect the reflected light from the disk into parallel light.

la. Important uses of the invention:

Optical pickup device

Description

Optical pickup

The present invention relates to an optical disc recording and reproducing apparatus, and more particularly, to an optical pickup apparatus for recording data to and reading data from an optical disc.

Among the various devices constituting the CD system, the optical pickup can be said to be the heart of the CD system, which performs optical signal detection. In addition to the basic condition that the pickup of the CD system has, the following conditions are additionally required.

(1) It should be small.

(2) Be able to read CD type signal stably.

The function of the pickup on the CD is to focus the laser beam on the disc with an objective lens and receive the returned light and fix it with an electrical signal. The pickup of the CD is composed of various types, and Fig. 1 shows the configuration of the optical pickup based on the three beam method.

Referring to FIG. 1, a laser generated by a laser diode 2 is converted into parallel light through a collimator lens 6. In the three-beam method, a diffraction grating 4 for beam splitting is inserted between the laser diode 2 and the collimator lens 6 or between the collimator lens 6 and the beam splitter 8. In general, the diffraction grating 4 is a small slit carved into the surface of an optical material such as glass (glass) at equal intervals, thereby generating three beams. When the laser beam passes through the diffraction grating 4, the waves of the light through each slit interfere with each other at the exit, so that the 0th order diffraction light at the center and the angles at right and left symmetry are changed by ± 1st order, ± 2nd order, or ± 3rd order diffraction. Light and so on. Since the diffracted light is attenuated at higher orders, three diffracted lights are selected as the highest 0th diffraction light and the second ± 1st diffraction light, and the next higher order diffracted light is masked and cut. This gives three beams.

The laser light, which has become parallel light by the collimator lens 6, is focused on the objective lens 12 through the beam splitter 8 and the quarter wave plate 10, and the diameter is reflected on the reflective surface of the disc 14. A beam spot of about 1 μm is made. The reflected light from the disk 14 becomes parallel light through the objective lens 12 and passes through the quarter wave plate 10, but in the beam splitter 8, the direction is suddenly changed by 90 degrees to the photo detector 20. This is because the beam splitter 8 separates incident light and reflected light. The incident light and the reflected light are distinguished by the quarter wave plate 10.

The reflected light changed in the 90 [deg.] Direction by the beam splitter arrives at the photodetector 20 composed of the photodiode through the condenser lens 16 and the cylindrical lens 18, and converts the focusing and tracking data signal into an optical-to-electrical signal. As described above, a focusing method using the condenser lens 16, the cylindrical lens 18, and the photodetector 20 is an astigmatic method.

When the optical pickup as described above is used for recording and reproduction, there is a disadvantage in that the optical power emitted from the laser diode 2 must be tuned in circuit because the optical power required during recording and reproduction is different.

Patent No. 96-62476 (Invention: Optical Pick-Up Device), which was previously filed by the applicant of the present application to solve this disadvantage, uses two light sources (two laser diodes) having different optical powers in a single optical module. And / or a reproducible optical pickup apparatus. The optical pickup device employs two light sources having different powers in the optical module, and uses a phtorefrative crystal element to obtain light suitable for recording and reproduction. As a result, the tuning circuit becomes unnecessary, and the circuit structure required of the optical pickup device can be greatly simplified. However, the optical pickup device disclosed in Patent Application No. 96-62476 has a phase conjugate signal when a beam reflected from a disk is incident to the photorefractive crystal element in the opposite direction due to the characteristics of the optical refraction crystal element. There is a disadvantage that can damage the beam.

Accordingly, an object of the present invention is to provide an optical pickup apparatus for solving signal beam damage due to phase matching generated when using a photorefractive crystal device as described above.

Another object of the present invention is to provide an optical pickup apparatus for improving the speed of recording data on an optical disc in an optical disc recording and reproducing apparatus.

Another object of the present invention is to provide an optical pickup apparatus that can reduce the cost of optical pickup and increase the data throughput.

In accordance with the above object, the present invention relates to an optical pickup apparatus of an optical disc recording / reproducing apparatus, wherein the optical pickup apparatus of the optical disc recording / reproducing apparatus is provided with a mount provided on a substrate and provided on both sides of the mount, respectively, to record data. First and second laser light emitting parts emitting first and second laser light having different powers and outputting only one of the first and second laser light when reading data; and the first and second emitted light. A lens unit which focuses the laser light and couples the energy of the collected first and second laser light to be light suitable for recording or reading data on the disc; and a collimator lens for making the light through the lens unit be parallel rays of light. And a beam splitter for passing the incident light from the collimator lens and converting the reflected light in the 90 ° direction to separate the incident light from the reflected light. And a light detector for detecting reflected light converted from the beam splitter by 90 ° when reading data, and an objective lens for focusing incident light through the beam splitter on the disk and making the reflected light on the disk be parallel light. It is done.

1 is a schematic configuration diagram of an optical pickup commonly used;

2 is a block diagram of an optical pickup according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are denoted by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

As shown in FIG. 1, when the optical pickup using one laser diode is used for recording and reproduction, the optical power emitted from the laser diode because the optical power required for recording and reproduction is different as described above. There is a disadvantage in that the circuit is tuned. In addition, the power of the laser diode required for recording must have a power of 50 mW. A laser diode component with a power capacity of 50 mW, for example, is more expensive than two laser diode components where the sum of the power of the two laser diodes is about 50 mW.

On the other hand, the optical pickup device disclosed in the previously filed Patent No. 96-62476 is a hologram optical pickup device, as described above, the beam reflected from the disk due to the characteristics of the photorefractive crystal device is again photorefractive in the opposite direction When incident on the crystal device, phase conjugation may occur to damage the signal beam.

In the present invention, in order to solve these disadvantages or problems, a holo lens, a focusing lens, a photorefractive crystal element, and a collimator lens are added to a general type of pickup, and have a power lower than that of a single laser diode as well as cost. This makes a light source using two laser diodes much cheaper. Two light sources form two light spots on the disk to improve data throughput.

2 is a block diagram of an optical pickup according to an embodiment of the present invention. 2, the first laser diode 36 and the second laser diode 40, which are laser light sources, are mounted on upper ends of both sides of the mount 32 installed on the substrate 30, and the first and second lasers are mounted on the lower end of the mount 32. The first and second monitor photodiodes 34 and 38 for monitoring the amount of light emitted from the diodes 36 and 40 are mounted. The first and second laser diodes 36 and 40 have at least less power than one laser diode with high power (eg 50 mW). For example, it has a power of 10mW and 30mW. Currently, two laser diodes with low power are cheaper in cost than one laser diode with high power. Therefore, the laser light emitted from the first laser diode 36 and the second laser diode 40 has a different amount of light.

In the present invention, both the laser diodes 36 and 40 shown in FIG. 2 are used for data recording, and only one of the two laser diodes 36 and 40 is used for data reading. Such implementation in the present invention increases the data recording speed. Therefore, although not specifically mentioned in the following description, it is to be understood that both laser diodes are used to record data on the disk 54 and only one laser is used to read data.

On the mount 32 equipped with the first and second laser diodes 36 and 40, the holo lens 42, the condenser lens 44, the photorefractive crystal element 46, the collimator lens 48, the beam splitter, as shown in FIG. 2, according to an embodiment of the present invention. 50, and objective 52.

The laser light generated by the first and second laser diodes 36 and 40 during data recording is diffracted through the lens 42 alone and collected through the condenser lens 44 and applied to the photorefractive crystal element 46. The photorefractive crystal element 46 couples the energy of two incident laser beams so as to be suitable for data recording. The two laser beams passing through the photorefractive crystal element 46 become parallel rays through the collimator lens 48. The beam is then focused through an objective lens 52 through a beam splitter 50 and a quarter wave plate 51 to create a recording beam spot of about 1 탆 in diameter on the face of the disk 54. At this time, there are two recording beam spots formed on the disk 14.

Meanwhile, when data is read, laser light generated from one of the first and second laser diodes 36 and 40 generates one beam spot on the disk 54 through the electrical process. In this case, the photorefractive crystal device 46 of FIG. 2 couples the energy of the incident laser light to be suitable for data reading. The reflected light from the disk 14 becomes parallel light through the objective lens 52 and passes through the quarter wave plate 51. However, the beam splitter 50 suddenly changes the direction by 90 degrees to the photo detector 60. This is because the beam splitter 50 separates incident light and reflected light. The incident light and the reflected light are distinguished by the quarter wave plate 10. The reflected light changed in the 90 [deg.] Direction by the beam splitter arrives at the photodetector 60 composed of the photodiode through the condenser lens 56 and the cylindrical lens 58, and converts the focusing and tracking data signal into an optical-to-electrical signal.

In the servo method of the optical pickup apparatus applied to the embodiment of the present invention, the focusing servo is set by the astigmatic method and the tracking servo is set by the push-pull method. In the above-described embodiment of the present invention, the photorefractive crystal device 46 generates an energy coupling to be suitable for data recording. The efficiency of the photorefractive crystal device 46 is increased between the condenser lens 44, the photorefractive crystal device 46, and the collimator lens 48 of FIG. Medium may also be added.

In the above description of the present invention, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be defined by the equivalents of the claims and the claims.

As described above, the present invention includes an optical pickup device including two laser diodes in a general pickup configuration, and an optical pickup device including lenses for eliminating signal beam damage due to phase matching generated when using the photorefractive crystal device. Not only does it eliminate the signal beam damage caused by phase matching during use, but it also reduces the cost of optical pickup and increases data throughput.

Claims (4)

In the optical pickup apparatus of the optical disc recording and reproducing apparatus, A mount mounted on a substrate, First and second laser light emitting units respectively installed on both sides of the mount and emitting first and second laser lights having different powers when writing data and emitting only one of the first and second laser lights when reading data. Wow, A lens unit for focusing the emitted first and second laser light and coupling energy of the focused first and second laser light to be light suitable for recording or reading data on the disc; A collimator lens for converting light through the lens unit into parallel rays of light; A beam splitter for passing the incident light from the collimator lens and converting the reflected light in a 90 ° direction to separate the incident light from the reflected light; A light detector which detects the reflected light converted by 90 ° in the beam splitter when data is read; And an objective lens for focusing the incident light through the beam splitter on the disk and making the reflected light on the disk be parallel light. The method of claim 1, wherein the lens unit Holo lenses for diffracting the laser light generated by the first and second laser diodes, A condenser lens for condensing laser light through the holo lens; And a photorefractive crystal element for coupling energy of one or two laser lights through a condenser lens to be light suitable for reading or recording data. The optical pickup apparatus of claim 2, wherein a medium is added between the holo lens, the condenser lens, and the photorefractive crystal element to increase the efficiency of the energy coupling. The method according to claim 2 or 3, further comprising a first and second monitor photodetectors for monitoring the first and second laser light amounts emitted from the first and second laser light emitting units. Optical pickup device.

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