KR100302498B1 - Optical pickup device - Google Patents

Abstract

According to the present invention, a light receiving element capable of receiving light beams having different wavelengths corresponding to a plurality of modes is integrated with a light emitting element emitting light beams having any one of the plurality of wavelengths, thereby forming light emission and a light receiving path. An optical pickup apparatus for minimizing optical means, the optical pickup apparatus processing light beam signals of a plurality of modes for reproducing different types of disks, comprising: a first light emitting body emitting a beam of a first wavelength, and the first light emitting apparatus; A second light emitting body emitting a beam of a second wavelength different from one wavelength, and the first light emitting body and the second light emitting body reflecting from the disk after the light emitted from the first light emitting body and the second light emitting body are irradiated onto the disk. Hologram model in which the photoelectric conversion means for receiving the beam and converting it into an electrical signal, and the hologram for injecting the beam reflected from the disk to the observation conversion means side And installed on the beam passing path between the disc and the hologram module to guide the beam emitted from the first and second light emitters to the disc and guide the beam reflected from the disc to the hologram module according to the type of the mounted disc. It is composed of an optical means including a beam splitter to reduce the manufacturing cost as well as to shorten the light receiving path to minimize the optical loss on the path and is a very useful invention aimed at miniaturization of the optical pickup device.

Description

Optical pickup device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup apparatus capable of playing / recording different types of discs, and more particularly, to receive light beams having different wavelengths corresponding to a CD or DVD playback / recording mode using one light receiving element. Accordingly, the optical pickup apparatus can be miniaturized by minimizing the number of optical means for forming the light emission and the light receiving paths having a plurality of wavelengths provided in the optical pickup apparatus capable of both playing and recording CDs or DVDs. It is about.

Read-only CDs (hereinafter referred to as "normal CDs"), which are general optical disks, have a pitch between tracks of 1.6 µm and a length of the pitch within the tracks of 0.9 µm. The digital multi-function disc (DVD: Digital Video Disc, hereinafter referred to as 'DVD') has a pitch between tracks of 0.87 mu m and a pit length of 0.4 mu m to 1.87 mu m. Accordingly, the optical beams used for the general CDs and DVDs are required to have optimal optical wavelengths of 780 nm and 650 nm, respectively. However, in the optical pickup apparatus which combines and reproduces both general CDs and DVDs, only one 650 nm laser diode (LD) is used. The recording / reproducing operation of the two types of optical discs (normal CD and DVD) was performed by using.

However, recordable CDs (CD-Rs) or rewritable CDs (CR-RWs) for recording signals by changing the crystal structure of the optical disc medium are manufactured to be used only for light beams of 780 nm, from which time CDs and DVDs can be used. The combined optical pickup device has a 780 nm laser diode for recording or reproducing a signal on a CD (CD, CD-R, CD-RW) and a 650 nm laser diode for recording or reproducing a signal on a DVD. All of them are provided and the recording / reproducing operation is performed using the corresponding laser diode according to the type of the optical disk.

In the conventional optical pickup apparatus, as shown in FIG. 1, a light beam having a specific wavelength range (780 nm or 680 nm) is emitted to form an optical spot on the recording surface of the optical disc, and receives the reflected light of the formed optical spot. Hologram Pickup Module (HPM) (10, 11) for converting into electrical signals: Polarization Beam Splitter (PBS) for changing the transmission path of the light beam according to the direction of the incident light beam (PBS) (20) : A collimator lens 40 for converting and outputting the incident light beam into horizontal light; and a focus lens 30 for condensing the converted and output horizontal light as a light spot on a recording surface of the optical disk. Was composed.

On the other hand, the hologram pickup module (HPM) is a light emitting diode (LD) for generating a light beam having a specific wavelength range, and the light beam generated from the light emitting diode is incident to the optical disk and the light beam reflected from the optical disk A hologram distributed according to the formed pattern, and a photo diode (PD) for receiving a light beam output according to the distribution characteristic of the hologram and converting the light beam into an electrical signal are integrated.

In the conventional optical pickup apparatus configured as described above, when the optical disk is a CD, as shown in FIG. 2A, the light beam emitted from the laser diode emitting the light beam of 780 nm passes through a grating plate. After being separated into a) beam and two sub-beams and transmitted through the 780nm hologram is output from the hologram pickup module (10).

The light beam output as described above is incident to the polarization beam splitter 20, and the incident light beam passes through the collimator lens 40 and is converted into horizontal light. The converted horizontal light is condensed by the focus lens 30, thereby forming light spots having a diameter of 1 탆 or less on the recording surface of the optical disk. The light spot formed as described above is reflected from the optical disk and undergoes the reverse process as described above, and is inputted into the hologram pickup module 10 and then partitioned each region of the 780 nm light receiving diode through the 780 nm hologram (a Separately incident to, b, c, e, f, the electrical signals A, B, C, E, and F are photoelectrically converted from each of the areas to be separated and output.

That is, AB of the separately outputted electric signals is used as a focus error signal EF as a tracking error signal, and the electric signals A, B and C of the a, b and c regions passing through the hologram are summed to obtain a high frequency component. It is reproduced and output as an RF signal.

On the other hand, when the optical disk is a DVD, the 650 nm light beam generated from the hologram pickup module 11 of Figure 2b is transmitted from the hologram pickup module 11 through the 650 nm hologram and the polarization beam splitter 20 The light is incident on the collimator lens 40 and then transmitted to the collimator lens 40 in order to be converted into horizontal light. The converted horizontal light having different wavelengths is condensed by the focus lens 30 to form optical spots having a diameter of 1 μm or less on the recording surface of the optical disk. The optical spots formed as described above are reflected from the optical disk to form the hologram. The electrical signals corresponding to the amount of light input into the pickup module 11 and detected from each of the zones a, b, c and d of the 650 nm light-receiving diode via the 650 nm hologram are A, B, C and D. From this, the focus error signal corresponds to AB, the tracking error signal corresponds to a phase difference between C and D, and the high frequency signal corresponds to A + B + C + D.

However, the 650 nm hologram pickup module used when the optical disk is a DVD is only sold at a specific company (eg, Sharp) due to the complicated and difficult manufacturing process, and is sold very exclusively and at high cost.

Accordingly, FIG. 3, which is another conventional optical pickup device having a hologram pickup module, does not use the expensive 650 nm hologram pickup module shown in FIG. 2, and uses a general 650 nm light emitting diode and a 650 nm light receiving diode. In order to prevent the occurrence of astigmatism (rotational translucent mirror 50, and a transparent plate 60 to compensate for the optical path that is changed according to the rotation angle of the translucent mirror (50) It was configured to include.

In the operation of the optical pickup device configured as described above, first, the light beam generated from the 650 nm light emitting diode 1 is changed into an optical path by the polarization beam splitter 20 to be incident on the translucent mirror 50, and the translucent mirror The light beam incident on 50 is formed as light spots on the recording surface of the optical disc (i.e., DVD) via the collimator lens 40 and the focus lens 30 in sequence. The light spot is reflected from the optical disk and passes through the focus lens 30 and the collimator lens 40 in turn, and then passes through the translucent mirror 50 and the transparent plate 60 to the 650 nm light-receiving diode 2. Will be incident.

However, the optical pickup device of FIG. 3 using each of the 650 nm light emitting diodes and the light receiving diodes by replacing the expensive 650 nm hologram pickup module as described above, has increased the number of optical components to be added additionally, the light beam The longer the path and the longer the transmission of each optical component, the lower the light efficiency due to the reduced amount of light, as well as the tolerance (error for the minimum separation distance between the optical components) to be considered in the arrangement of the optical components. There is a problem in that signal interference is generated between the optical parts disposed adjacent to each other because it is not secured, thereby making the operation of the optical pickup device unstable.

Accordingly, the present invention has been made to solve the above problems, by integrating a light receiving element capable of receiving light beams having a plurality of wavelengths with a light emitting element emitting light beams having any one of the plurality of wavelengths. It is an object of the present invention to provide an optical pickup device that minimizes the optical means required for light emission and light receiving path formation.

1 is a block diagram of a conventional optical pickup device using a general hologram pickup module (HPM),

Figure 2a shows the internal structure of the hologram pickup module for a CD (read only CD)

Figure 2b shows the internal structure of the hologram pickup module for DVD (DVD)

3 is a configuration diagram of another conventional optical pickup device using one hologram pickup module.

Figure 4 shows the configuration of an embodiment in which the optical pickup device according to the present invention is applied to the hologram pickup module

5 illustrates the internal structure of the hologram pickup module according to the present invention.

FIG. 6 illustrates light receiving characteristics of the light receiving diode of FIG. 5.

7 shows the configuration of another embodiment in which the optical pickup device according to the present invention is applied to a hologram pickup module.

* Explanation of symbols for main parts of the drawings

1: Light emitting diode (LD) 2: Light receiving diode (PD)

10,11: hologram pickup module (HPM) 20: polarized beam splitter (PBS)

21: thin film translucent mirror 50: translucent mirror

30: Focus Lens 40: Collimator Lens

60: transparent plate 100: hybrid hologram pickup module

An optical pickup apparatus according to the present invention for achieving the above object is a first light emitting body for emitting a beam of a first wavelength in an optical pickup apparatus for processing a light beam signal of a plurality of modes for playing different types of discs; And a second light emitter for emitting a beam having a second wavelength different from the first wavelength, and the first light emitter and the second light emitted from the disk after the light emitted by the first light emitter and the second light emitter are irradiated onto the disk. The first light emitter and the first light emitter and the first light emitter and the first disc according to the type of the disc; and a hologram module having an integrated hologram for receiving a beam of a light emitter and converting the light into an electrical signal. A beam between the disc and the hologram module to guide the beam emitted from the light emitter to the disc and direct the beam reflected off the disc to the hologram module And it is characterized in that there is constituted an optical means including a beam splitter which is installed on the path.

In the optical pickup apparatus according to the present invention configured as described above, light beams having different wavelengths, respectively emitted from a plurality of light emitting means, are incident on the recording medium by the optical means and then reflected from the recording medium. The light beam having the light beam is received by the optical means into one photoelectric conversion means, and the photoelectric conversion means converts the light beams of different wavelengths to be received into electrical signals.

Hereinafter, a preferred embodiment of the optical pickup device according to the present invention will be described in detail with reference to the accompanying drawings.

Figure 4 shows the configuration of an embodiment in which the optical pickup device according to the present invention is applied to the hologram pickup module, the light emitting diode (1) for emitting a light beam having a wavelength of 650nm: and emits a light beam having a wavelength of 780nm Mixed hologram 100 for receiving light beams of 650 nm and 780 nm: Polarization Beam Splitter (PBS) for changing the transmission path of light beams according to the direction of incident light beams (PBS) 20: Number of incident light beams A collimator lens 40 for converting and outputting to flat light; and a focus lens 30 for condensing the converted output horizontal light to a light spot on a recording surface of the optical disk, wherein the mixed type As shown in FIG. 5, the hologram 100 is formed of a mixed hologram (Co-Hologram) in which a material (shape, depth, pitch interval, etc.) is formed differently from a hologram for 650 nm or a hologram for 780 nm. The 650㎚ / 780㎚ light-receiving diodes, and light emitting diode 780㎚ photoelectric conversion according to a light beam which is incident on the respective regions separate so characteristic in accordance with the generation pattern of the mixed type hologram in the light amount is integrated.

The operation of the optical pickup apparatus according to the present invention configured as described above is a 780 nm light beam from a 780 nm light emitting diode integrated in the mixed hologram pickup module 100 when the mounted optical disc is a CD as in the conventional example. When the optical disk output through the mixed hologram (Co-Hologram) and seated is a DVD, a 650 nm light beam is emitted from the 650 nm light emitting diode 1.

The light beam having a specific wavelength range (780 nm or 650 nm) that emits light as described above is formed by the external polarizing beam splitter 20 to form an optical path in the optical disk direction and is incident on the collimator lens 40. The incident light beam is converted into horizontal light by the collimator lens 40 and then formed into a light spot on the recording surface of the optical disk by the focus lens 30.

The optical spot formed on the optical disk recording surface as described above passes through the focus lens 30 and the collimator lens 40, and then the optical path is changed by the polarizing beam splitter 20 to enter the mixed hologram pickup module 100. And the incident light beam passes through a mixed hologram (Co-Hologram) in the mixed hologram pickup module 100 so as to be divided into a plurality of regions (a, b, c, d) as shown in FIG. 5 for 650/780 nm. Inputs are separated into light-emitting diodes.

Meanwhile, as the 650/780 nm combined light receiving diode, as shown in FIG. 6, a light receiving diode having a characteristic of having a light receiving rate is remarkable for a light beam having a wavelength range of 650 nm to 780 nm.

As described above, the light beam separately input into each of the regions (a, b, c, and d) is then converted into an electrical signal (A, B, C, D) corresponding to the amount of light incident in each region. Among the electrical signals, AB is used as a focusing error signal, CD is a tracking error signal, and A + B + C + D is used as an RF signal of a high frequency component.

On the other hand, when the wavelength range of the light beam is 780 nm (when the optical disk is a CD), the tracking error signal is a (CD), that is, the difference of the electrical signal, whereas the wavelength range of the light beam is 650 nm (optical disk is In the case of DVD), the tracking error signal corresponds to the phase difference of (CD).

FIG. 7 illustrates a configuration of another embodiment in which the optical pickup device according to the present invention is applied to a hologram pickup module, except that the polarizing beam splitter 20 is replaced with a thin film translucent mirror 21 to reduce manufacturing cost. 4 and the angle θ at which the light beam emitted from the 650 nm light emitting diode 1 is incident on the surface of the thin film translucent mirror 21 is set within a range of 45 ° to 60 °. do.

The thin film mirror 21 is formed of a transmissive surface 21 a and a reflective surface 21 b having a thin film formed thereon. The beam emitted from the 650 nm light emitting diode 1 is incident on the transmission surface 21a, and the beam emitted from the 780 nm light emitting diode (not shown) of the hologram pickup module 100 is the reflection surface 21b. The 650 nm light emitting diode 1 and the hologram pickup module 100 are disposed with respect to the thin film translucent mirror 21 so as to be incident on the thin film translucent mirror 21.

When the optical disk seated in the optical pickup device configured as described above is a DVD, the angle at which the light beam emitted from the 650 nm light emitting diode 1 forms the surface of the thin film translucent mirror 21 is within the range described above. (A + a), a 650 nm light beam emitted from the 650 nm light emitting diode 1 is incident at an angle of θ to the surface of the thin film translucent mirror 21 and is transmitted therefrom to the collimator lens 40 and the collimator lens 40. Scanned to the recording surface of the optical disk via the objective lens 30 in sequence.

In contrast, when the seated optical disk is a general CD, the light emitting path having the same length as the light emitting path formed when the seated optical disk is a DVD is formed, but the 780 nm light emitting diode in the hybrid hologram pickup module 100 is formed. The light beams emitted from the light beams (not shown) are incident to the thin film translucent mirror 21 at an angle δ greater than 45 ° and then reflected, and are collimated with the collimator lens 40 and the objective lens in the same way as the 650 nm light beam. 30) is scanned onto the recording surface of the optical disk.

Each light beam (650 nm or 780 nm) reflected from the optical disk is incident on the thin film translucent mirror 21 through the objective lens 30 and the collimator lens 40 and then reflected to the hologram pickup module 100. The light is received by a 650/780 nm combined light-emitting diode in the cell, and converted into a corresponding electric signal.

Another embodiment of the present invention described above is a thin film translucent thin film polarizing beam splitter when compared with the optical pickup device in which the 650 nm light emitting diode 1 and the mixed hologram pickup module 100 formed at right angles are described with reference to FIG. 4. The manufacturing cost can be reduced by replacing the mirror 21, and each light beam (650 nm,) within the range that the angle (θ = 45 ° + a) formed with the incident surface of the 650 nm light beam does not exceed 60 °. As the inclination (a) of the thin film translucent mirror which determines the angles (?, Δ) of 780 nm) with the incident surface is increased, the device can be miniaturized.

The optical pickup apparatus according to the present invention configured and operated as described above receives light beams having different wavelengths corresponding to a CD or DVD playback / recording mode using one light receiving device, thereby reducing manufacturing costs and receiving paths. It is a very useful invention that minimizes the optical loss on the path by shortening and miniaturization of the optical pickup device.

Claims (5)

An optical pickup apparatus for processing light beam signals of a plurality of modes for playing different types of discs, A first light emitting body emitting a beam of a first wavelength A second light emitting body emitting a beam of a second wavelength different from the first wavelength; Photoelectric conversion means for receiving the beams of the first light emitting body and the second light emitting body to the disk, and then receiving the beams of the first light emitting body and the second light emitting body reflected from the disk and converting the light into electrical signals; A hologram module in which a hologram for injecting a beam reflected from the disk is incident on the spectral conversion means side; According to the type of the mounted disk is installed on the beam passing path between the disk and the hologram module to guide the beam emitted from the first and second light emitting body to the disk and the beam reflected from the disk to the hologram module An optical pickup apparatus composed of optical means including a beam splitter. The method of claim 3 Wherein the first light emitter emits a DVD-based light beam and the second light emitter emits a CD-based light beam An optical pickup apparatus for processing light beam signals of a plurality of modes for playing different types of discs, A first light emitting body emitting a beam of a first wavelength A second light emitting body emitting a beam of a second wavelength different from the first wavelength; A photoelectric conversion means for receiving beams emitted from the first and second light emitters onto a disc and receiving beams of the first and second light emitters reflected from the disc and converting the beams into electrical signals; A hologram module in which a hologram for injecting a beam reflected from the disk to the photoelectric conversion means is integrated; According to the type of the mounted disk is installed on the beam passing path between the disk and the hologram module to guide the beam emitted from the first and second light emitting body to the disk and the beam reflected from the disk to the hologram module And optical means including a thin film translucent mirror for transmitting or reflecting a beam emitted from the first or second light emitting body, respectively, and reflecting the beam reflected from the disk to the hologram module. The method of claim 3 The thin film translucent mirror is optical pickup device, characterized in that the surface is installed so as to be in the range of 45 ° ~ 60 ° with the transmitted incident beam The method of claim 3 One of the light emitters emits CD-based beams and the other emits DVD-based beams. The thin film translucent mirror reflects a CD-based beam and transmits a DVD-based beam to an optical pickup device.