KR0127519B1 - Light pick-up apparatus - Google Patents

Abstract

The incidence beam is projected from the beam separation point(41a) to the objective lens(36). Thru the objective lens(36), the projected beam is collected on the recording side of the disk, having the reflective beam from the recording side of the disk converted into parallel beam by the objective lens(36), then the reflective beam from the parallel beam, after being deflected, is brought into contact with the collimation lens(32b) to be projected to the beam receiving diode(37). Therefore, based on the laser beam received by the beam receiving diode(37), focusing detection, tracking detection, and correcting and information reading are carried out.

Description

Optical pickup device

1 to 3 illustrate the structure of a conventional optical pickup apparatus.

4 is a schematic diagram showing the configuration of an optical pickup apparatus according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

30: laser light source, 31: diffraction grating,

32: collimated lens, 33: light receiving element,

34: romvoid prism, 35: right angle prism,

36: objective lens, 37: photodiode,

41: reflection prism, 42: Wallastone Prism,

43: sensor lens

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup apparatus, and more particularly, to an improvement of an optical pickup apparatus for reading information recorded on an optical disk dedicated for reproduction or an optical magnetic disk capable of recording and reproduction.

In general, a disc reproducing system that uses an optical property to read information recorded on the surface of an information recording medium such as a laser disc or a compact disc or mini disc by a laser beam is irradiated with the laser beam on the surface of the information recording medium. And an optical pickup apparatus adapted to receive the reflected light reflected from the surface of the information recording medium to read the information.

Such an optical pickup apparatus is classified into a 1 beam method using a single laser beam and a 3 beam method using a single laser beam by splitting it into three.

Here, in the case of the first beam method, as shown in FIG. 1, a laser light source 10 composed of a laser diode to generate a laser beam and a laser beam emitted from the laser light source 10 are converted into parallel light. A collimator lens 11, which is converted into parallel light by the collimator lens 11, and enters through a beam splitter 12 and a quarter wave plate 13 into a laser beam. The objective lens 14 which condenses on the surface of D), the reflective surface R of the disk D, is exactly comprised, and the reflected light reflected from the reflective surface R of the disk D is an objective lens ( 14, the polarized plane is changed by 90 ° in the quarter wave plate 13, and then the reflected light is separated from the non-impeller 12 which separates the incident light from the laser beam and the reflected light. The connection len which connects the reflected light to the optical pickup device. It is equipped to four divided light-receiving diode (17) for receiving via; (16 Knige edge) of the connected light reflected cylindrical lens or by the knife edge 15 and the connecting lens 15.

As is well known, the beam splitter 12 is constructed by obliquely arranging two rectangular prisms and polarized on the inclined surface of the prism in any one direction so as to ensure straightness with respect to incident light while reflecting 90 ° in the transverse direction with respect to the reflected light. The film is applied. Further, the quarter-wave plate 13 has a function of converting linearly polarized light into circular light or converting circularly flat light into linearly polarized light by using birefringence.

In the case of the three-beam method, the front or rear of the collimating lens 11, that is, between the laser light source 10 and the collimating lens 11 or between the collimating lens 11 and the beam splitter 12 A diffraction grating 18 for dividing the laser beam into three is provided.

According to the optical pickup apparatus of the above-described configuration, the laser beam radiated from the laser light source 10 is converted into parallel light in the collimated lens 11 (in the three beam method, divided by three by the diffraction grating 18). Next, a beam spot of approximately 1 μm on the reflective surface R of the disk D in the objective lens 14 through the beam split 12 and the quarter wave plate 13 separating the incident light and the reflected light. Spots). The laser beam irradiated onto the disk D has a different amount of reflected light depending on the presence or absence of the pit P on which information is recorded, and the reflected light is converted into parallel light in the objective lens 14 and then the quarter wave plate 13 ), The polarization plane is changed by 90 degrees, and then the direction is changed in the beam splitter 12 so as to be connected by the connection lens 15. The position of the optical pick-up device with respect to the disk D in accordance with the connected reflected light is received by the four-segment light-receiving diode 17 through the cylindrical lens or knife edge 16 and focused on the light-receiving diode 17. In addition to determining the accuracy, information is reproduced based on the amount of reflected light determined by the pitch P of the disk D. FIG.

By the way, in the conventional optical pickup apparatus having the above-described configuration, the incident light of the laser beam emitted from the laser light source 10 composed of the laser diode and the reflected light emitted from the reflecting surface R of the disk D are received and the disk ( The laser beam passes through a plurality of incidence and reflectometer components between the light receiving diodes 17 which obtain an electrical signal relating to the information recorded in D), and for that reason, the optical pickup apparatus has a relatively complicated structure. . Furthermore, in the case of the quarter-wave plate 13 which converts the reflected light by 90 ° to the incident light, antireflection coating is performed on the surface thereof, so that strict limitations are imposed on the thickness and cutting angle appropriate for the wavelength of the laser beam used. The production is not easy.

Since the laser diode constituting the laser light source and the disk and the light receiving diode receiving the reflected light reflected from the reflecting surface exist on different planes, the size of the entire optical pickup apparatus is inevitably increased. In view of this, studies on the simplification of the optical pickup device have been conducted, and the optical pickup device of the type shown in FIG. 2 has been proposed. According to the optical pickup device, the laser pickup is composed of a laser diode. To the collimated lens 22 and the collimated lens 22 for converting the generated laser light source 20 and the laser beam emitted from the laser light source 20 and incident through the rectangular prism 21 into parallel light. An objective lens 23 for condensing the laser beam converted into parallel light by the disk D, and positioning the objective lens 23 such that the objective lens 23 is accurately focused at a target position of the disk D. Reflecting light reflected from the focusing coil 24, the plurality of magnets 25, and the disk D for adjustment is converted into parallel light by the objective lens 23, and the rectangular prism 21 is passed through the collimating lens 22. In the transverse direction from the reflective surface The light-emitting diode 26 which receives the converted reflected light is comprised.

According to the optical pickup apparatus of the above-described configuration, the collimated lens 22 is designed to use only the portion having the good characteristics of the laser beam radiated from the laser light source 20 by being disposed close to the objective lens 23, Compared to the optical pickup device shown in FIG. 1, the use of a beam splitter or a quarter wave plate is excluded.

Therefore, although the optical pickup device shown in FIG. 2 has a relatively simple configuration, the collimating lens 22, the objective lens 23, and the positioning of the objective lens 23 for converting the laser beam into parallel light are provided. (I.e., a plurality of magnets 25 for focusing) are not only required, but each component is arranged in line according to the steps for signal detection, which makes the configuration considerably complicated and increases the volume of the optical head. The process is complicated.

In general, the optical pickup device employed in the mini-disc player is, as shown in FIG. 3, a laser light source 30 composed of a laser diode to generate a laser beam, and a laser beam from the laser light source 30. A diffraction grating (Grating; 31) for dividing the beam into three beams; a collimator lens (32a) for converting the laser beam emitted from the laser light source 30 into parallel light; The incident beam from the laser light source 30 through the collimated lens 32a is inclined at a predetermined angle so as to be directed to the light receiving element 33 which controls the amount of light while ensuring straightness. Half Mirror) and the reflected light reflected from the recording surface of the disk D through the coated polarizing surface 34a, the polarizing surface 34a and the right-angle prism 35, and the objective lens 36 at a predetermined angle (e.g., 90 °) Rhombold Prism 34 having a total reflection coating reflecting surface 34b inclined at a predetermined angle so as to be deflected in the transverse direction, and a Wallastone prism that polarizes light reflected from the reflecting surface 34b. (Wollastone Prism; 42), a collimated lens 32b that focuses the reflected light through the wall-stone prism 42, and generates an aberration for the focused light to enter the light-receiving diode 37 for data reading. Sensor Lens (43) It can be configured.

In the optical pickup device having the above-described configuration, the laser beam radiated from the laser light source 30 is divided into three by the diffraction grating 31, converted into collimated light by the collimated lens 32a, and then the romvoid prism 34 The incident light and the reflected light are separated from the polarization plane 34a of the light beam, and the reflected light is incident on the light receiving element 33 to act to control the output light amount of the laser light source 30, while the incident light is a right prism 35. 90 degrees by (), and is focused on the recording surface of the disk (D) through the objective lens (36). Thereafter, the reflected light reflected from the recording surface of the disk D is converted into parallel light by the objective lens 36 and directed through the right angle prism 35 to the romboid prism 34. Accordingly, the parallel light is moved downward by 90 ° by the polarization plane 34a of the romboid prism 34 to the reflection surface 34b, and laterally turned from the reflection surface 34b again to the wallastone. Since the light is polarized by the prism 42 and then focused by the collimated lens 32b, the light is incident on the light-emitting diode 37 while generating astigmatism through the sensor lens 43, thereby performing data reading.

According to the optical pickup device used in such a mini-disc player, since the laser light source (i.e., laser diode) and the light receiving diode (i.e. photodiode) are located on one plane, the height and volume are reduced, but the optical pickup device is constructed. It has the disadvantage of increasing the number of components.

Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide an optical pickup apparatus for irradiating a laser beam to a read-only optical disc or a magneto-optical disc capable of recording and reproducing, and detecting light from the disc to read information. To provide an optical pickup device configured to reduce the height and components by simply designing the structure of the optical head.

In order to achieve the above object, an optical pickup apparatus according to an embodiment of the present invention includes a laser beam source generating a laser beam, a diffraction grating dividing the laser beam emitted from the laser light source into three beams, and the diffraction grating A collimating lens for converting the passed laser beam into parallel light, an objective lens for condensing the laser beam converted into parallel light by the collimating lens, and a light receiving diode for receiving the reflected light reflected from the recording surface of the disk An optical pickup apparatus, comprising: a reflection disposed between the collimated lens and the objective lens to totally reflect an incident ratio from the laser light source through the collimated lens toward the objective lens while being reflected from the disk through the objective lens The beam separation surface that allows the beam to pass through, and the beam separation surface And a reflection prism having a total reflection surface configured to totally reflect the passed light to the light-emitting diode via a wallastone prism, a collimated lens, and a sensor lens, and the wallastone prism is totally reflected from the reflection prism. An optical pickup apparatus formed integrally with the reflective prism is provided so as to coincide with the optical axis of the reflected light.

According to the present invention configured as described above, the laser beam radiated from the laser light source is totally reflected toward the objective lens at the beam separation plane of the reflective prism through the diffraction grating and the collimated lens, and the laser beam incident on the objective lens is The reflected light reflected from the surface of the disk is converted into parallel light through the objective lens, passes through the beam separation plane of the reflecting prism, and is laterally converted from the total reflection surface to be received by the light receiving diode. Reading of the recorded information becomes possible.

Hereinafter, with reference to the accompanying drawings will be described the present invention in more detail.

FIG. 4 is a schematic view showing the configuration of an optical pickup apparatus according to an embodiment of the present invention, and has the same components as those described in FIG. 3 (ie, the disk D, the laser light source 30, and the diffraction grating 31). , Collimated lenses 32a and 32b, objective lens 36, light-receiving diode 37, wallastone prism 42, and sensor lens 43] are omitted.

Reference numeral 41 is a reflection prism provided between the collimating lens 32a and the objective lens 36.

The reflective prism 41 reflects the laser beam from the laser light source 30 incident through the collimated lens 32a toward the objective lens 36 and is reflected from the disk D. The beam splitting surface 41a inclined at a predetermined angle with the predetermined polarizing film applied so as to pass the reflection beam converted into parallel light through the objective lens 36 and the beam passing through the beam separating surface 41a. It has a total reflection surface 41b inclined at a predetermined angle with a total reflection coating so as to totally reflect the reflection beam toward the light-emitting diode 37. In addition, since the reflective prism 41 and the wallace prism 42 are integrally formed, the reflected light through the total reflection surface 41b is polarized by the wallace prism 42.

Referring to the information reading operation by another optical pickup device according to an embodiment of the present invention configured as described above are as follows.

First, the laser beam emitted from the laser light source 30 is divided into three by the diffraction grating 31 and converted into parallel light in the collimated lens 32a and then incident on the beam separation surface 41a of the reflective prism 41. do. The incident light is redirected from the beam separation surface 41a toward the objective lens 36 and is incident thereon, and is focused on the recording surface of the disc D through the objective lens 36. Thereafter, the reflected light reflected from the recording surface of the disk D is converted into parallel light by the objective lens 36 and then directed to the reflective prism 41. Subsequently, the reflected light converted into parallel light passes through the beam separation surface 41a of the reflection prism 41 as it is and is reflected to the reflection prism 41 separately from the total reflection surface 41b (that is, separately from the beam separation surface 41a). The total reflection coating surface provided] is deflected by a predetermined angle (for example, about 90 °) in the same horizontal direction as the laser light source 30. The deflected reflected light is polarized by the wall raster prism 42 formed integrally with the reflective prism 41 and then focused in the collimated lens 32b to generate astigmatism through the sensor lens 43 while receiving the photodiode 37 Incident).

Accordingly, focusing detection, tracking detection, and information reading are performed based on the laser beam received by the light receiving diode 37.

As described above, according to the present invention, the laser beam radiated from the laser light source is irradiated onto the surface of the disc after total reflection toward the objective lens at the beam separation plane of the reflective prism through the diffraction grating and the collimated lens, and the surface of the disc Reflected light reflected from the object is converted into parallel light through the objective lens and passed through the beam separation plane of the reflecting prism, and then converted from the total reflection plane to the transverse direction (that is, the same horizontal direction as the laser light source) to be received by the light receiving diode. By eliminating the need for a right-angle prism, there is an advantage that the height and components are remarkably simplified compared to the optical system structure of the conventional optical pickup apparatus.

Claims (1)

A laser beam passing through the diffraction grating 31 and a diffraction grating 31 for dividing the laser light source 30 generating a laser beam, the laser beam radiated from the laser light source 30 into three beams as parallel light. The collimating lens 32a to be converted, the laser beam converted into parallel light by the collimating lens 32a, the objective lens 36 condensing on the disk D, and the reflected light reflected from the recording surface of the disk D. An optical pickup apparatus having a light receiving diode 37 for receiving light through a collimated lens 32b and a sensor lens 43, wherein the collimator is disposed between the collimated lens 32a and the objective lens 36. While total reflection of the incident beam from the laser light source 30 through the mate lens 32a toward the objective lens 36, the reflection beam reflected from the disk D through the objective lens 36 is passed through as it is. Intended Total reflection to the light-emitting diode 37 through the wall separation surface 41a and the beam separation surface 41a via the wallastone prism 42, the collimating lens 32b, and the sensor lens 43; A reflection prism 41 is further provided with a total reflection surface 41b, which is adapted to be made, and the wallastone prism 42 is adapted to match the optical axis of the reflected light totally reflected from the reflection prism 41. 41) An optical pickup apparatus, characterized in that formed integrally with.