KR20000056434A - Optical Disk Apparatus of Modified Beam Splitter - Google Patents

Abstract

PURPOSE: An optical disk optics for transforming a beam splitter structure is provided to narrowly design a space of the optics and to increase optical efficiency of a laser beam to perform a focusing process of an optical spot, by transmitting a laser beam to a recording surface of an optical disk to receive a beam reflected in the recording surface through an optical path, to read data of the optical disk. CONSTITUTION: An optical disk optics for transforming a beam splitter structure comprises a laser diode(10), a beam splitter(20), a collimating lens(30), an objective lens(40), an optical detector(60), and a focusing/circular lens(50). The laser diode generates a laser beam to radiate the beam, to optically read data of an optical disk. The beam splitter is designed to equalize optical amounts of a first transmitted light and a first reflected light. The first transmitted light is transmitted to a first surface(21). The beam splitter is designed to transmit a second reflected light to the first surface, when the first transmitted light is totally reflected in a second surface(22). The collimating lens parallels the laser beam to collimate the beam. The objective lens receives a parallel ray to form an optical spot in a recording surface of the optical disk. The optical detector receives the laser beam to read the data of the optical disk according to a predetermined optical detecting system. The focusing/circular lens converts the laser beam with an astigmatism to perform a focus servo function.

Description

Optical Disk Apparatus of Modified Beam Splitter

The present invention relates to an optical disk optical system in which the structure of a beam splitter is modified. More particularly, the optical disk optical system includes a first reflected light reflecting from a first surface, which is a light incident surface, and a first transmitting light through the first surface. The first reflected light and the second reflected light according to a thickness of a beam splitter designed to have the same amount of light transmitted and to totally reflect the first projection light on the second surface, which is a light transmission surface, so that the second reflected light is transmitted toward the first surface. Adjust the reflected angle between the reflected light, and enter the laser beam to the recording surface of the optical disk via the optical path passed by the first reflected light to the beam reflected from the recording surface of the optical disk through the optical path passed by the second reflected light An optical disk optical system in which the structure of a beam splitter that receives light and reads data recorded on an optical disk is modified.

In general, a recording medium for recording and reproducing information such as an image, sound, or data with high density is made of a disk, a card, or a tape, but a disk is mainly used. Recently, the field of optical disc devices has been developed from Laser Disk (LD), Compact Disk (CD) to Digital Versatile Disc (Read Only Memory). Discs are generally classified into CDs and DVDs. CDs are classified into CD-ROM (Read Only Memory) and CD-RW (Rewritable), and DVDs are divided into DVD-ROM and DVD-RAM (Random Access Memory). In addition, the DVD is a DVD-S in which only one information is recorded in a single layer on one track, and a DVD-D in which two information is simultaneously recorded in a dual layer on one track. Separated by.

Until now, DVD-RAM optical systems have a large numerical aperture of the objective lens to increase recording density, and a short wavelength light source of 650 nm allows recording and playback on a DVD-RAM, while playing CD-ROMs or CDs. It was developed to be able to play / record RW. In addition, the DVD-ROM optical system was developed to be compatible with the DVD-ROM and CD-ROM.

In general optical disk optical systems, as shown in Fig. 1, the laser diode 1 is configured to generate a laser beam having a unique wavelength.

A beam splitter 2 reflects one diffused laser beam emitted from the laser diode 1.

The collimating lens 3 collimates the collimating lens 3 and converts it into parallel light when one diffusing laser beam is reflected from the beam splitter 2 and irradiated.

The objective lens 4 collects the laser beam of parallel light converted by the collimating lens 3 and irradiates the optical disk D.

On the other hand, the focusing / cylindrical lens 5 converts the laser beam reflected from the optical disk D to astigmatism to perform a focus servo.

The four-segment photodetector 6 detects a reproduction signal and an error signal (focusing error and tracking error) by using a push-pull and astigmatism method for one beam received in four areas, and focusing servo and tracking servo. It is configured to perform.

Referring to the operation of the optical disk optical system, first, when the diffused laser beam is generated and emitted from the laser diode (1) is incident to the beam splitter (2), reflected by the beam splitter (2), reflected by the beam splitter (2) The diffused laser beam is incident on the collimating lens 3 and is converted into parallel light in the collimating lens 3. Then, the laser beam changed into collimated light from the collimating lens 3 is incident on the objective lens 4, and the objective lens 4 condenses the laser beam and irradiates the recording surface of the optical disk D, that is, the pit. do.

In addition, the laser beam irradiated and reflected on the recording surface of the optical disk D is sequentially passed through the objective lens 4, the collimating lens 3, the beam splitter 2, and the focusing / cylindrical lens 5. The photodetector 6 received by the split photodetector 6 performs the focusing servo and the tracking servo by the push-pull method and the astigmatism method with the received laser beam, and simultaneously converts the laser beam into an electrical signal to convert the optical disk ( Read the data recorded in D).

However, in the conventional optical disk optical system as described above, the laser beam is incident on the recording surface of the optical disk via the optical path through which the reflected light reflected from the light incident surface of the beam splitter passes, and the light incident surface of the beam splitter The optical disc optical system occupies a space because the optical disk receives a beam reflected from the recording surface of the optical disk through the optical path through the transmitted light passing through the transmission surface, which is the rear surface of the beam splitter, and reads the data recorded on the optical disk. On the other hand, the optical disk drive has become a factor of inhibiting miniaturization and slimming, while the optical efficiency of the laser beam is lowered, and the focusing of the optical spot is poor due to various causes.

Accordingly, the present invention has been made to solve such a problem, and in the optical disk optical system, the amount of light of the first reflected light reflected from the first surface, which is the light incident surface, and the first transmitted light transmitted through the first surface is the same. A reflected angle between the first reflected light and the second reflected light according to a thickness of a beam splitter designed to totally reflect the first projection light on a second surface that is a light transmission surface and transmit the second reflected light toward the first surface The laser beam is incident on the recording surface of the optical disk via the optical path through which the first reflected light passes, and receives the beam reflected from the recording surface of the optical disk through the optical path through the second reflected light to the optical disk. By reading the recorded data, you can narrowly design the space occupied by the optical disc optics, as well as the optical To the excellent rate and it is an object to provide an optical disc optical system, the focusing is such that the solid modifying the structure of the beam splitter of the light spot.

1 is a configuration diagram showing the configuration of a conventional optical disk device,

Figure 2 is a block diagram showing a preferred embodiment of the optical disk optical system modified the structure of the beam splitter according to the present invention

3 is a configuration diagram of a four-segment light detector that detects a signal by a general push-pull method and an astigmatism method.

<Description of the code | symbol about the principal part of drawing>

10: laser diode 20: beam splitter

21: first surface 22: second surface

30: collimation lens 40: objective lens

50: focusing / cylindrical lens 60: light detector

D: optical disc

A feature of the present invention for achieving the above object comprises: a first light source for generating and irradiating a first light having a predetermined magnitude of wavelength to optically read data of an optical disc; The second light on the second surface, which is a light transmitting surface, is designed to have the same amount of light of the first reflected light that is installed on the first light path and reflects on the first surface, the light incident surface, and the first transmitted light that passes through the first surface. A beam splitter designed for total reflection of the first projection light and transmission of the second reflected light toward the first surface;

A collimating lens for collimating and collimating the first light reflected by the beam splitter through an optical path through the first reflected light;

An objective lens positioned between the optical disk and the collimating lens to converge the parallel light to form an optical spot on the recording surface of the optical disk;

And a light detector which receives a beam reflected from the recording surface of the optical disk via the optical path via the second reflected light and reads data recorded on the optical disk according to a predetermined optical detection method.

Here, it is preferable that a focusing / cylindrical lens is disposed between the objective lens and the light detector to convert the laser beam reflected from the optical disk D to astigmatism for a function of performing focus servo. Do.

In addition, the beam splitter may adjust the reflected angle between the first reflected light and the second reflected light according to its thickness.

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

Figure 2 is a block diagram showing a preferred embodiment of the optical disk optical system modified the structure of the beam splitter according to the present invention.

A laser diode 10 for generating and irradiating a laser beam having a predetermined size wavelength to optically read data of the optical disc D;

It is designed to be equal to the amount of light of the first reflected light that is installed on the path of the laser beam and reflected from the first surface 21, which is a light incident surface, and the first transmitted light that passes through the first surface 21, and is a light transmission surface. A beam splitter (20) designed to totally reflect the first projection light at a second surface (22) so that a second reflected light is transmitted toward the first surface (21);

A collimation lens (30) for collimating and collimating the laser beam reflected by the beam splitter through an optical path through which the first reflected light passes;

An objective lens (40) positioned between the optical disk (D) and the collimating lens to converge the parallel light to form an optical spot on the recording surface of the optical disk (D);

An optical detector (60) which receives the laser beam reflected from the recording surface of the optical disk (D) via the optical path via the second reflected light and reads data recorded on the optical disk according to a predetermined optical detection method;

A focusing / cylindrical lens positioned between the objective lens 40 and the light detector 60 for converting the laser beam reflected from the optical disk D to astigmatism for a function of performing a focus servo ( 50).

Looking at the operation of the optical disk optical system according to the present invention with reference to Figure 2 the laser diode 10 is configured to generate a laser beam having a wavelength of 650nm for CD or 780nm for DVD.

The beam splitter 20 is designed to have the same amount of light of the first reflected light reflected from the first surface 21, which is a light incident surface, and the first transmitted light passing through the first surface 21, and is the second surface, which is a light transmission surface. At 22, the first projection light is totally reflected so that the second reflected light is transmitted toward the first surface 21.

At this time, the impermeable layer 23 is bonded and laminated to the second surface 22 so that total reflection occurs at the second surface 22. In addition, when manufacturing the beam splitter 20, the thickness d of the beam splitter 20 is variously changed to adjust the reflected angle between the first reflected light and the second reflected light to a desired angle, and the first The laser beam is incident on the recording surface of the optical disk via the optical path through which the reflected light passes, and the light reflected from the recording surface of the optical disk is received through the optical path via the second reflected light to read the data recorded on the optical disk. Make sure

The collimating lens 30 is configured to change one diffused laser beam into parallel light when it is reflected through the beam splitter 20. That is, the laser beam reflected from the beam splitter is collimated by collimating the laser beam reflected through the optical path through which the first reflected light passes.

An objective lens 40 is positioned between the optical disk D and the collimating lens 30 to collect a laser beam of parallel light converted by the collimating lens 30 to irradiate the optical disk D. An optical spot is formed on the recording surface of the disk D, and the focusing / cylindrical lens 50 is positioned between the objective lens 40 and the light detecting unit 60 so as to perform the focus servo. The laser beam reflected from the disk D is converted to astigmatism.

The optical detector 60 receives the laser beam reflected from the recording surface of the optical disk D through the optical path through which the second reflected light passes, and reads the data recorded on the optical disk according to a predetermined optical detection method.

For example, the light detector 60 reproduces a single beam received in four areas A, B, C, and D using a push-pull and astigmatism method and a reproduction signal and an error signal (focusing error and tracking error). Detect and perform focusing servo and tracking servo.

Here, the push-pull method and the astigmatism method will be described. As shown in FIG. The light detector 60 is typically provided with a focusing / cylindrical lens 50 that focuses light and focuses only one of the vertical and horizontal directions orthogonal to the optical axis of the focused light beam and transmits the light in the other direction as it is. The light formed through the focusing / cylindrical lens 50 becomes as shown in FIG. 3 (b) in the case of the focal point, and as shown in FIG. 3 (a) or FIG. The focusing error signal for compensating for the focus error is a sum of the diagonal areas and is a differential value, that is, a signal difference between A + D and B + C. When the tracking error occurs, the light is shifted to the left or the right, so the value of the tracking error signal is the signal difference between A + C and B + D. The value of the reproduction signal is the sum of the signals of all the regions, that is, A + B + C + D.

Terminologies used herein are terms defined in consideration of functions in the present invention, which may vary according to the intention or customs of those skilled in the art, and the definitions should be made based on the contents throughout the present application. will be. Although specific embodiments of the invention have been described and illustrated, it will be apparent that the invention may be embodied in various modifications by those skilled in the art.

In addition, since the present invention has been described through the preferred embodiment of the present invention, in view of the technical difficulty aspects of the present invention, those having ordinary skill in the art can easily be different from another embodiment of the present invention. As modifications may be made, it is obvious that both the embodiments and modifications cited in the above description belong to the appended claims.

As described above, in the optical disk optical system, the second surface, which is designed to have the same amount of light of the first reflected light that reflects on the first surface, which is the light incident surface, and the first transmitted light that passes through the first surface, is the light transmissive surface. The reflected angle between the first reflected light and the second reflected light is adjusted according to the thickness of the beam splitter designed to totally reflect the first projection light to transmit the second reflected light toward the first surface, and the first reflected light passes through According to the present invention, the laser beam is incident on the recording surface of the optical disk via the optical path to receive the beam reflected from the recording surface of the optical disk via the optical path through which the second reflected light is received, thereby reading the data recorded on the optical disk. In addition, the space occupied by the optical disc optical system can be narrowly designed, and the optical efficiency of the laser beam can be improved. This has the effect of focusing of the pot so that excellent.

Claims (4)

In optical disc optics: A first light source for generating and irradiating first light having a predetermined size wavelength for optically reading data of the optical disc; The second light on the second surface, which is a light transmitting surface, is designed to have the same amount of light of the first reflected light that is installed on the first light path and reflects on the first surface, the light incident surface, and the first transmitted light that passes through the first surface. A beam splitter designed for total reflection of the first projection light and transmission of the second reflected light toward the first surface; A collimating lens for collimating and collimating the first light reflected by the beam splitter through an optical path through the first reflected light; An objective lens positioned between the optical disk and the collimating lens to converge the parallel light to form an optical spot on the recording surface of the optical disk; And And a light detector for receiving the light reflected from the recording surface of the optical disk through the optical path passed by the second reflected light, and reading the data recorded on the optical disk according to a predetermined optical detection method. Optical disk optical system modified. The method of claim 1, And a focusing / cylindrical lens positioned between the objective lens and the light detector to convert the laser beam reflected from the optical disk D to astigmatism for a function of performing focus servo. Optical disk optical system with a modified structure of the beam splitter. The optical disk optical system of claim 1, wherein the beam splitter adjusts a reflected angle between the first reflected light and the second reflected light according to a thickness of the beam splitter. The optical disk optical system according to claim 1, wherein the first light source is a laser diode.