KR100255676B1 - Optical pickup device as type of integrated optic-element - Google Patents

Abstract

PURPOSE: An optical element integrated-typed dual focus optical pickup device is provided to vary incident optical strength distributions of a luminous flux relating to a spherical aberration, and to actively convert a numerical aperture of an objective lens, to deteriorate the spherical aberration, so as to make a digital audio disk compatible with a digital video disk. CONSTITUTION: An integrated optical element(20) comprises as follows. A transmission-typed wavelength plate(30) delays phases of laser beams on an upper surface. A multi-division photo detector(40) receives a reflection light. A reflection-typed wavelength plate(24) converts a polarization of the reflection light. A Fresnel lens(26) condenses a light on the entire surface of the reflection-typed wavelength plate(24) to shorten optical paths, and generates astigmatism. A polarization separator(22) separates optical paths of an incident light and a reflection light. A laser diode(10) emits laser beams(P wave) polarized as horizontal components, relating to a progress direction of a light from a lower direction of the integrated optical element(20). An optical control plate(50) comprises as follows. An inner circular plate(56) transmits a narrow laser beam between the integrated optical element(20) and optical disks(60,70) with the first transmission rate. An outer plate(57) transmits a wide laser beam with the second transmission rate. The first transmission rate is set bigger than the second transmission rate. An objective lens(100) condenses the laser beams on the optical disks(60,70).

Description

Optical element integrated dual focus optical pickup device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element integrated dual focus optical pickup device. In particular, the spherical aberration caused by the difference in the thickness of the optical disk and the recording surface of the signal information varies the incident light intensity distribution of the light beam incident on the objective lens. The present invention relates to an optical element integrated dual focus optical pickup device capable of actively reproducing digital audio and digital video discs since the number NA is actively converted and spherical aberration is significantly reduced.

In general, an optical data recording medium, that is, an optical disk, is divided into a digital audio disk (DAD) for music playback having a thickness of 1.2 mm and a digital video disk (DVD) having a thickness of 0.6 mm, and has a thickness of 1.2 mm. Digital audio discs record data in multiple layers on one side, and 0.6 mm thick digital video discs record data in multiple layers in the middle to record a large amount of data on a single disc.

An optical pickup apparatus for reproducing data recorded on the above two types of discs reads information recorded on a 1.2 mm thick digital audio disc and a 0.6 mm thick digital video disc. Since the track pitch of the image is 0.74 µm and the shortest length between the pit, which is the recording signal, is 0.4 µm, the diameter of the optical spot must be different during playback because the track pitch is different from that of a digital audio disc having 1.6 µm and the shortest length between the feet is 0.834 µm. Because spherical aberrations do not match, simultaneous playback is impossible, and optical aberration is increased due to the difference of 0.6mm thickness of the discs. Only the recorded information on one of the 1.2mm discs could be read.

Therefore, an objective lens having a numerical aperture NA of 0.6 designed for a 0.6 mm disk as shown in the detailed view of FIG. 1 to selectively read out information recorded on a 1.2 mm disk and a 0.6 mm disk in recent years. And a dual focus lens in which the holographic optical element 1120 having the multi-stage diffraction layers w1, w2, h0 formed by etching is adopted, and is diffracted by the holographic optical element 1120. Since the zero-order light goes straight and the first-diffracted laser light becomes divergent light, a dual focus optical pickup device for controlling the diffraction efficiency and appropriately distributing the amount of light has been developed.

As shown in FIG. 1, the dual focus optical pickup device employing the holographic optical device 1120 includes a laser diode 1100 that scans laser light having a linearly polarized constant wavelength, and the laser diode 1100. A diffraction grating 1105 which separates the laser beam scanned by the laser beam into a zero-order diffraction light and a ± first-order diffraction light for detecting a tracking error signal, that is, a three beam, and at one side of the diffraction grating 1105 A beam splitter 1110 for transmitting and reflecting the scanned laser light at a predetermined ratio with a predetermined slope, a collimator lens 1115 for converting the laser light via the beam splitter 1110 into parallel light; The holographic optical element 1120 for distributing the amount of light by adjusting the diffraction efficiency of the parallel light via the collimator lens 1115 and the laser light via the holographic optical element 1120 for 0.6 mm digital discs. An objective lens 1130 that reads the recorded information by focusing on a disk 1150 (hereinafter referred to as "first disk") and a 1.2 mm disk (hereinafter referred to as "second disk") that is a digital audio disk; Astigmatism generating lens 1140 for generating a focusing error signal by the astigmatism method for detecting an error signal in the laser light with recorded information, and detecting the optical information passing through the astigmatism generating lens 1140 And a photodetector 1145 for converting the signal into a current signal.

In operation of the conventional optical pickup apparatus having such a configuration, first, the laser light having a predetermined oscillation wavelength is scanned by the laser diode 1100 and incident on the diffraction grating 1105, and the incident laser light is incident on the diffraction grating 1105. ) And radiated into 0th and ± 1st light, that is, three beams. The three beams are used for tracking errors. The three beams penetrate the diffraction grating 1105 and enter the beam splitter 1110. The three beams are reflected and transmitted at a constant rate by the beam splitter 1110. The laser light reflected from the reflected and transmitted laser light is incident from the beam splitter 1110 to the collimator lens 1115, and the laser light passes through the collimator lens 1115, thereby providing linearity. The laser light, which is thus provided with linearity and becomes parallel light, is incident from the collimator lens 1115 into the holographic optical element 1120, and the laser light is diffracted by the holographic optical lens 1120. Since the zero diffraction light goes straight among the diffracted laser beams, the light is collected in a spot having a diameter of 1.6 μm on the first disc 1150 having a diameter of 0.6 mm through the aperture of the objective lens 1130 having a numerical aperture of 0.6, Since the light is converted into divergent light and condensed narrowly by the objective lens, the light is condensed on the second disk 1155 in an airy shape having a diameter of 0.8 μm, so that the laser light is reflected almost as it is in the absence of the pit 1155 on the disk. To return to the objective lens 1130, but where the pit 1155 is present, the laser light is diffracted by the pit 1155 and emitted outside the range of the objective lens 1130, thereby causing only a part of the incident light to return. Thereby generating a light quantity difference in the photodetector 1145. This is because the depth of the pit 1155 is set to λ / 4 of the wavelength, and the reflected light is canceled by interference due to different half wavelengths above and below the pit 1155, thereby reducing the amount of light returned to the photodetector 1145.

The modulated reflected light reflected by the first disk 1150 or the second disk 1160 is returned to the beam splitter 1110 via the holographic optical device 1120 and the collimator lens 1115. The reflected light is reflected and transmitted again at a constant rate, and the laser light transmitted by the beam splitter 1110 is moved straight toward the photodetector 1145. The modulated reflected light is irradiated from the beam splitter 1110 to the astigmatism generating lens 1140, and the reflected light is generated by the astigmatism generating lens 1140 to detect a focus error, and thus the photodetector 1145. The reflected light, which is modulated by the disk, is converted into RF (RF), focus error detection, tracking control, and information into a current by a photodetector, which is converted into an original signal by a control circuit (not shown). Demodulation is performed.

Therefore, as described above, the laser light emitted from the laser diode 1100 is collected in different airy shapes on the disk via the holographic optical device 1120, so that the beam focus is formed at different positions so that the thickness is 1.2 mm. The disc and the information recorded on the 0.6 mm disc can be selectively read.

However, such a conventional dual focus optical pickup device has a processing effect due to the complex arrangement of the holographic optical element 1120 and the objective lens 1130 using diffraction of light in order to focus the optical disk with a double focus according to the thickness of the disk. Since a high level of technical skill is required, manufacturing is difficult and at the same time, the holographic optical device 1120 is fixed to the mover 1125 and thus adversely affects the dynamic characteristics of the actuator, and from the first disk 1150 to the second disk 1160. In the case of change, there is a problem that the obstacle of miniaturization of the optical pickup due to the enlargement of the objective lens by increasing the focal length of the objective lens due to the aberration change and the increase of the design dimension due to maintaining a predetermined distance between the optical elements.

The present invention has been made in view of the above problems, and improves the dynamic characteristics of the actuator by solving the complexity of manufacturing and compensation of aberration changes due to the precise interlayer alignment of the holographic optical element by etching, An optical element integrated optical pickup device capable of miniaturizing the optical pickup device by reducing the design dimension by eliminating the problem of adjusting the focal length of the objective lens due to aberration changes during reproduction caused by a plurality of disc thickness differences. The purpose is to provide.

In order to achieve the above object, the optical system configuration of the present invention,

A multi-segment photodetector for receiving reflected light on one side and outputting an electrical signal, a reflective wave plate provided on the opposite surface of the photo detector to change the phase of the reflected light, and an optical path shortened in front of the reflected wave plate. A Fresnel lens for condensing the light and generating astigmatism for error signal detection, and a laser beam having a component parallel to the incidence plane formed on the inclined plane between the Fresnel lens and the photodetector mounting surface. An integrated optical element which is formed integrally with the polarization splitter for transmitting and reflecting the laser light of a component perpendicular to the incident surface and installed below the optical disk;

A laser diode scanning a laser light polarized with a component perpendicular to a traveling direction of light from below the integrated optical device;

An inner circular plate formed between the integrated optical element and the optical disk and formed of a combat film for transmitting a narrow laser light at a transmittance of 1, and an outer plate formed of a semi-transmissive film for transmitting a wide laser light at a transmittance of 1/2 An optical control plate for adjusting the outermost incident angle of the laser light focused on the optical disk;

It comprises an objective lens for focusing the laser light via the light control on the optical disk,

The circuit system configuration of the present invention includes: reproduction signal processing means to which an electrical signal output from each of the light receiving sections is applied;

A tracking control device and a focus control device for controlling the tracking error and the focus error based on the signal applied from the reproduction signal processing means;

A digital signal processing apparatus for correcting an optical signal based on a signal applied from said reproduction signal processing means;

A motor control device for controlling the disc motor based on a signal output from the digital signal processing device;

An optical element integrated dual focus optical pickup device comprising a microcomputer for selectively controlling the tracking control device, the focus control device, and the motor control device based on the reproduction signal generated by the optical system when setting the play mode of the circuit system. to provide.

1 is a block diagram of a conventional optical pickup device;

2 is a block diagram of an optical pickup apparatus according to the present invention;

3 is a layout view of an optical system of the present invention;

Figure 4 is an installation state of the photo detector according to the present invention,

5 (a) is a graph showing the crosstalk change of the present invention according to the numerical aperture of the objective lens;

5 (b) is a graph showing a change in the reproduction signal of the present invention according to the change in the numerical aperture of the objective lens;

6 is a schematic diagram of an operating state in which the optical system according to the present invention plays a digital video disc;

7 is a schematic diagram of an operating state in which the optical system according to the present invention plays a digital audio disc;

8 is a detailed view of a Fresnel lens and a photo detector for detecting an error signal of an optical signal in the optical system of the present invention;

9 is a detailed circuit diagram of a reproduction signal processing means of the present invention;

10 is a circuit diagram showing an entire circuit system according to an embodiment of the present invention;

11 is an exploded perspective view of an optical pickup actuator applied to the present invention.

<Explanation of symbols for main parts of drawing>

10: laser diode 20: direct optical element

22: polarization separator 24: reflective wave plate

26 Fresnel lens 30 Transmissive wave plate

40: photo detector 50: light control plate

56: inner circular plate 57: outer plate

60, 70: optical disk 100: objective lens

101: objective lens holder 120: plate

140: holder gel 200: playback signal processing means

300: digital signal processing device 310: motor control device

320: microcomputer 330: focus control device

340: tracking control device

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

The present invention is to change the incident light intensity distribution of the light beam incident on the objective lens to be focused on the optical disk, so that the numerical aperture (NA) of the objective lens is actively converted to reproduce the digital audio and digital video disc.

This embodiment of the optical pickup device of the present invention is composed of an optical system (B) and a circuit system (A) as shown in FIG.

As shown in FIG. 3, the optical system B of the optical pickup device converts the path and polarization of the laser light under the optical discs 60 and 70, and receives the reflected light to output an electrical signal. 20), a laser diode 10 in which a laser beam having a horizontal component, that is, a laser beam delayed in phase with a P wave, is emitted in a downward direction from the integrated optical element 20 to a laser beam having a predetermined wavelength, and the integrated optical An optical control plate 50 for transmitting the laser light separately between the device 20 and the optical disks 60 and 70 at different transmittances according to the width, and a laser light passing through the optical control plate 50 to the optical disks 60 and 70. It consists of an objective lens 100 to focus on.

The integrated optical device 20 is formed of a rectangular glass face, and on one side is provided a multi-segment photo detector 40 for receiving the reflected light reflected on the optical disks 60 and 70, and the photo detector 40. On the opposite side of the reflection wave plate 24 is provided to convert the phase of the reflected light. In general, the reflective wavelength plate 24 is a quarter-wave plate using the birefringence of the prism to delay the phase of the reflected light. A Fresnel lens 30 is formed on the reflective wavelength plate 24. The Fresnel lens 30 has a vertical radius R1 and a horizontal radius R2 as shown in FIG. At the same time, the spherical surface of the lens is concentrically formed in multiple stages at different intervals to condense the laser light, thereby shortening the optical path, and the Fresnel lens 30 generates astigmatism in the imaging of the laser light. The focus error signal is detected from the photodetector 40 divided into S2, S3, and S4. Further, the polarization separator 22 formed on the comb face between the mounting surface of the Fresnel lens 30 and the photo detector 40 separates the optical paths of the incident light and the reflected light. The polarization splitting section 22 has a characteristic of transmitting the laser light (P wave) of the component parallel to the incident surface and reflecting the laser light (S wave) of the vertical component, and the incident light is the laser diode 10. Since the P wave is emitted from the polarization splitter 22 and the incident light is transmitted, the incident light is transmitted, the light is straightened, and the reflected light delayed by the S wave is reflected, thereby making the light path between the incident light and the reflected light different.

The light control plate 50 separates and transmits light at different transmittances depending on the width of incident light. The inner circular plate 56 transmits narrow incident light at a transmittance of 1, and an external transmissive incident light having a width of 1/2 at a transmittance of 1/2. The plate 57 is comprised. Thus, the light adjusting plate 50 is formed of an annular light-transmitting film to adjust the outermost incident angles θ1 and θ2 that are collected on the optical discs 60 and 70 based on the optical axis. Since the outermost incident angles θ1 and θ2 are proportional to the numerical aperture, the amount of light is controlled by the transmittance according to the width, and when the light is focused at different incidence angles on the optical discs 60 and 70, the numerical aperture NA may be adjusted. will be.

The numerical aperture controlled by the light control plate 50 is arranged as follows.

The diameters of the light spots focused on the optical discs 60 and 70 by the optical system B according to the present invention are differently determined according to the outermost incident angles θ1 and θ2. When the outermost incident angle irradiated to the digital video disk 60 having a thickness of 0.6 mm is θ2, and the outermost incident angle irradiated to the digital audio disk 70 having a thickness of 1.2 mm is θ1, and the refractive index of the medium is η, The determination of the numerical aperture NA for is determined by the following equation.

N.A.1 = ηsinθ1 N.A.2 = ηsinθ2

According to Equation 1, when the refractive indices are the same, the numerical aperture (rate) is proportional to the outermost incident angles θ1 and θ2, so that θ2> θ1 is determined as N.A.2> N.A.1.

Then, the size of the light spots due to the different numerical apertures is determined by the following expression (2). The radius W of the beam (K is a constant determined by the intensity distribution of the light),

Therefore, the diameter of the light spot is in inverse proportion to the numerical aperture.

Therefore, in the case of the optical disc 60 having a thickness of 0.6 mm, since the track interval and the size of the pit 65 as the signal surface are small, a small optical spot diameter is required, and thus an opening larger than the optical disc 70 having a thickness of 1.2 mm. You will need a number of objectives. At this time, even if the beam spot diameter becomes slightly larger on the optical disk 70 having a thickness of 1.2 mm, the optical signal can be read, and the objective lens 100 having the numerical aperture (NA = 0.6) dedicated to the digital video disk 60 can be obtained. As a result, compatible playback will be attempted.

The relationship between the numerical aperture and the light width incident on the objective lens is determined by the following equation. If D and f are the focal lengths of the objective lenses,

D = 2 × f × (N.A.)

That is, by controlling the incident light width to the objective lens having the same focal length in Equation 3, it is possible to adjust the effective N.A.

In the present invention, since a single objective lens, i.e., an objective lens 100 for digital video disc, is adopted based on the same focal length, the optical signal is read out on the optical disc 60 having a thickness of 0.6 mm without generating spherical aberration.

However, in this case, when the optical disc 70 having a thickness of 1.2 mm is read out, first, when the focus compensation is not performed, the focusing accuracy is not accurate due to defocus, and the error occurrence width becomes large. Second, the disc thickness difference The spherical aberration causes the increase in the distribution light intensity of the side lobe of the laser beam and the decrease in the central intensity distribution, thereby increasing the crosstalk between adjacent signals and decreasing the signal-to-noise ratio (S / N ratio). The optical performance is significantly lowered, making it impossible to read optical information. Therefore, the effective N.A. must be adjusted by Equation 3 above. The range of these effective openings is determined as follows.

First, the amount of spherical aberration caused by the difference in disk thickness is determined by the following equation (4). If the refractive index is η and the disk thickness change is Δd,

On the other hand, if the amount of aberration generated by defocus is ΔZ, Equation 4 is modified as follows.

The cumulative wave front aberration of the optical system of the present invention can be expressed by the aberration system from the relationship between the center intensity distribution and the wave aberration by matching the spherical aberration by equating the aberration generation amount of Equation 4 to a value compensated for defocusing. According to marechal's criterion that should be less than 0.07λ, the effect on the defocus can be eliminated, thus approaching the anhydrometer.

Therefore, when the numerical aperture is compensated for in the above equations, the maximum value of spherical aberration value 0.5 is obtained. That is, the effective number of openings should be 0.5 or less, and the minimum value is limited to Equation 2, thereby increasing the diameter of the light spot. The increase in the light spot diameter causes a crosstalk caused by an increase in the light spot size rather than the crosstalk due to the change in the intensity distribution due to the generated aberration, thereby lowering the signal-to-noise ratio. Therefore, since the minimum value is limited to the intensity distribution of the generated aberration, when the optical disk having a thickness of 0.6 mm is read out by the objective lens having a numerical aperture of 0.6 used in this embodiment, the effective number of openings is summarized as follows.

0.27 <N.A.≤0.5

In this way, the result of the change of the crosstalk according to the change of the numerical aperture and the sensitivity size of the reproduction signal can be found in the values shown in Figs. 5 (a) and (b). In the present invention, the numerical aperture is determined to be 0.3. .

Therefore, when the outermost incident angles θ1 and θ2 from the optical control plate 50 to the optical discs 60 and 70 are adjusted by Equations 1 to 6, the numerical aperture is adjusted so that only the optical disc 60 having a thickness of 0.6 mm may be used. The objective lens 100 can reproduce the optical disk 70 having a thickness of 1.2 mm, and the spherical aberration generated during the compatible reproduction is reproduced by fighting the narrow laser light, that is, the laser light around the optical axis. Regeneration can be excellent.

Next will be described the operation of the present invention is adopted that the light control plate 50 capable of adjusting the numerical aperture as described above.

First, as shown in FIG. 6, a laser light having a predetermined wavelength is emitted from the laser diode 10, which is a light component parallel to the incident surface with respect to the traveling direction of the laser light. For example, P-polarized light is emitted. The polarization is adjusted so as to emit laser light. The polarized laser light is irradiated from the laser diode 10 to the polarization separator 22 of the integrated optical element 20. Since the laser light is P-polarized light, the laser beam is transmitted through the polarization separator 22. The laser beam transmitted through the polarization separator 22 is irradiated from the polarization separator 22 to the transmission wavelength plate 40, and the laser light is linearly polarized by the transmission wavelength plate 40 into circularly polarized light. .

The laser light polarized by the circularly polarized light is irradiated from the transmission wavelength plate 40, that is, from the integrated optical element 20 to the light control plate 50, and the laser light is controlled by the light control plate 50. The control of the amount of transmission is to selectively transmit while varying the light intensity distribution of the incident light intensity, the laser light through the inner circular plate 56 of the light control plate 50 is fighting, and the laser light through the outer plate 57 is transflected. The laser beam passing through the inner circular plate 56 is condensed separately, and the laser beam transmitted through the outer plate 57 is focused at the outermost incident angle θ1 with respect to the optical axis via the objective lens 100. Via (100), the outermost incident angle is focused on θ2 with respect to the optical axis. That is, the laser beams passing through the light control plate 50 constituted by the inner circular plate 56 and the outer plate 57 have different outermost incident angles θ1 and θ2, respectively, and are different from each other by Equations 1 to 6 described above. The light is condensed onto the optical discs 60 and 70 by the numerical aperture NA.

By the way, the laser light collected by the objective lens 100 via the light control plate 50 at different numerical apertures is different from the outermost incident angles θ1 and θ2 of the laser light when incident on the optical discs 60 and 70. As described above, the difference in the diameter of the light spot is smaller than the light transmitted through the outer plate 57 than the light collected through the inner circular plate 56 of the light control plate 50.

Thus, when the optical discs 60 and 70 are reproduced, for example, the digital video disc 60 having a thickness of 0.6 mm, the external plate 57 is semi-transmissive to the light control plate 50 and the objective lens 100. As a result of the numerical aperture 0.6, an optical spot having a size of about 0.8 占 퐉 is formed on the optical disk 60 at θ2 with respect to the optical axis, and is interfering with diffraction on the recording surface 65 to read optical information with the amount of light and the presence or absence of light. At this time, since the objective lens 100 dedicated to the digital video disc 60 is used in the present invention, it is condensed accurately without generating spherical aberration in the recording surface.

When the digital audio disc 70 having a thickness of 1.2 mm is reproduced, as shown in FIG. 7, the laser light that has been battled on the inner circular plate 56 is focused by the objective lens 100 at a numerical aperture of 0.3 and is focused on the optical axis. Is focused on the optical disc 70 at? 1.

Thus, the laser light, which reads the optical information on each of the optical disks 60 and 70 in the above-described process, is irradiated to the transmission wavelength plate 40 via the objective lens 100 and the light control plate 50. In the laser beam, circularly polarized light is polarized by linearly polarized light when the transmission wavelength plate 40 is transmitted. At this time, since the linearly polarized laser light is incident on the transmissive wave plate 40 when the inverted circular polarized light is reflected on the optical disks 60 and 70, the linearly polarized laser light has a polarization direction orthogonal to the time of incidence upon the initial transmissive wave plate 40. Linear polarization. The laser light of the inverted linearly polarized light is irradiated to the polarization separator 22, and the laser light of the linearly polarized light is reflected by the polarization separator 22.

The reflected laser light is irradiated from the polarization separator 22 to the reflective wavelength plate 24 and the Fresnel lens 26, and the laser light is reflected by the astigmatism generated by the Fresnel lens 40. The phase wave plate 24 is retarded by the laser light of the parallel component, that is, P-polarized light. Thus, the laser light is totally reflected by the reflective wavelength plate 24, transmitted through the polarization separator 22, and irradiated to the photodetector 40 provided on the opposite surface.

And, as shown in Figure 2 in the signal processing diagram of the optical system (B) and the circuit system (A) according to an embodiment of the present invention, the laser light irradiated by the photo detector 40 is converted into an electrical signal by the photoelectric effect Is converted.

The conversion to the electrical signal is the photo detector 40 is formed of four segments (S1, S2, S3, S4) as shown in Figure 8, irradiated to each segment (S1, S2, S3, S4) The reflected light is converted into an electrical signal by the photoelectric effect, and the electrical signals converted in each of the segments S1, S2, S3, and S4 are respectively represented by the RF signal calculating device 210 and the focusing error signal. In the computing device 230 and the tracking error signal computing device 220, the RF signal = S1 + S2 + S3 + S4, the focusing error signal = (S1 + S4)-(S2 + S3), and the tracking error signal = (S1 + It is calculated and output as S2)-(S3 + S4).

In this way, the electrical signal converted by the photodetector 40 is calculated from each of the computing devices 210, 220, 230 and applied to the reproduction signal processing means 200, and focusing with the tracking error signal computing device 220 among these signals. The signal output from the error signal calculator 230 is input to the microcomputer 320 and simultaneously controls the tracking controller 340 and the focus controller 330 based on the tracking error and focus error signals. The RF signal computed and output by the RF signal calculation device 210 is applied to the digital signal processing device 300 via the reproduction signal processing means 200.

When the actuator is operated up and down based on the focus error signal output as described above, an RF signal is generated from the reflected light of the laser light irradiated on the optical disk 60 having a thickness of 0.6 mm. At this time, when the voltage level applied to the focus coil included in the actuator increases, the voltage value of the electrical signal detected by the photodetector 40 and reflected by the 0.6 mm thick optical disk 60 and the 1.2 mm thick optical disk 70 Since the voltage value of the electric signal reflected and detected by is set to the offset voltage value in the focus control apparatus 330, the initial focusing positions of the respective optical disks 60 and 70 are controlled.

However, the RF signal is determined whether the RF signal is generated according to the optical disk 70 having a thickness of 1.2 mm and the optical disk 60 having a thickness of 0.6 mm, and the optical disk 60 is processed when the signal output from the photodetector 40 is processed. The difference in the amount of reflected light due to the difference in thickness between the 70 and the 70 is initially set so that the RF signal is not generated during the reproduction of the optical disk 60 having the thickness of 0.6 mm, the RF signal is generated only when the optical disk 70 having the thickness of 1.2 mm is reproduced. As it will be described in more detail as follows.

First, when the reproduction signal is detected by the photodetector 40 on the digital audio disc 70 having a thickness of 1.2 mm by the optical system B acting as shown in FIG. 7, the detailed circuit system A of FIG. As shown in FIG. 2, the high frequency signal RF or HF is applied to the digital signal processing apparatus 300 when the reproduction signal processing means 200 processes the reproduction signal. In addition, the microcomputer 320 provides a signal suitable for the optical disk 70 having a thickness of 1.2 mm to the focus control device 330 that performs the focus control function while simultaneously adjusting the initial optical spot signal of the objective lens 100. do.

In addition, the microcomputer 320 is connected to the motor control device 310 responsible for the control of the disk rotation motor 317 to rotate at an appropriate speed according to each optical disk (60, 70). The motor control device 310 is connected to the digital signal processing device 300.

Thus, the microcomputer 320 controls the switch SW1 to set the offset initial value to the first resistance value RC to set the initial focus position of the actuator. When an RF signal is detected while the actuator is moving to the initial position, a voltage is applied to the comparator C1, and when the signal is higher than the reference voltage Vc set by the resistor Rt, the output signal of the comparator C1 is output. Since the input microcomputer 320 determines that a high frequency (RF) signal is generated above an effective value, the playback mode of the digital audio disc 70 is automatically set.

Thus, the microcomputer 320 outputs a control signal to the motor control circuit 315, and the motor control circuit 315 controls the disk motor 317 at a constant linear velocity and at a reference speed. Control.

In this way, the microcomputer 320 turns off the switch SW4 while holding the switch SW5 in the focus control device 330, the tracking control device 340, the motor control device 310, and the reproduction signal processing means 200 as it is. After switching, the switch SW3 is switched to apply a control signal to the motor control circuit 315, and the switch SW6 for connecting the focus error signal FES output from the reproduction signal processing means 200 is turned on. Thus, the focus error signal FES controls the focus control device 330 by turning on the switch SW6 and the tracking error signal TES is applied to the tracking control device 340 so that focus and tracking are controlled. .

In addition, when the switch SW3 of the motor controller 310 is switched and connected to the digital signal processor 300, the motor control signal output from the digital signal processor 300 is applied to the motor controller 310. The disk motor 317 controls the linear constant speed CLV.

Thus, the optical signal is properly read out through the tracking and focusing control devices 330 and 340 and the linear constant speed control.

When the reproduction signal is detected by the photo detector 40 on the digital video disc 60 having a thickness of 0.6 mm by the optical system B shown in FIG. 6, the actuator is transferred so that a high frequency (RF) signal is not generated. Therefore, the microcomputer 320 switches the switch SW1 to set the second resistor value Rs as the offset resistor. Thus, if the actuator is transferred and no RF signal is detected during the transfer, the disc may be missing or a disc error may occur.

Thus, when a high frequency (RF or HF) signal is detected according to the offset resistances Rs and Rc as described above, the motor control circuit 315 controls the disc motor 317 under the control of the microcomputer 320. Control at the constant constant speed (CLV) and at the same time control the reference speed. Thus, the gain value is adjusted. The description of the gain value is as follows.

First, when it is determined whether the microcomputer 320 detects the RF signal according to the type of the disk, that is, the set offset resistors Rs and Rc, the microcomputer 320 switches the switch SW3 of the motor controller 310. The disk motor 317 is rotated at a low speed from the path of the variable resistor R3. The disk motor 317 is connected to the power amplifier 316, which is connected to the motor control circuit 315.

On the other hand, the microcomputer 320 turns on the switch SW4 of the focus control device 330 again, and when the switch SW4 is turned on, the oscillator 333 generates a triangular wave. This triangular wave is applied to the actuator from the oscillation device 333, and the actuator is transferred by the signal of the triangular wave.

Here, the switch SW6 is turned off when the switch SW4 is on, and the switch SW6 is turned on when the switch SW4 is off. The microcomputer 320 switches the switch SW1 to select an offset resistance value, and then switches the switch SW5 of the reproduction signal processing means 200 to generate an output when an RF signal is detected by the reproduction signal processing means 200 ( G1 'G2' G3 '), and when the RF signal is not detected, that is, when the digital video disc 60 is reproduced, the output G1' G2 'G3' is connected to gains G1, G2, G3.

The reproduction signal processing means 200 sets the signal path of the analog switch array SW5 based on the signal of the photodetector 40. When this signal path is set, the gain G1 is reproduced when the digital video disc 60 is reproduced. OP-AMP output terminal is applied from an unillustrated OP-AMP (Operationl Amplifier) output stage having G2 and G3, and an OP-AMP output stage having gains G1 ', G2', and G3 'during reproduction of the digital audio disc 70. Output signals are applied. At this time, since a G≤G 'relationship is established between the gain G and the gain G', each signal output from the OP-AMP is RF signal calculating device 210 and focusing error calculation shown in FIG. The device 230 and the tracking error calculator 220 calculate the RF signal RFS, the focus signal FES, and the tracking signal TES. The signals calculated in this way are transferred to the digital signal processing apparatus 300, the focus control apparatus 330, and the tracking control apparatus 340 to control focusing, tracking, and signal reproduction, respectively. Since the control devices 330 and 340 apply error signals to the focusing coil 345 and the tracking coil 335 of the optical pickup actuator in which the objective lens 100 is installed, the actuator moving part is driven to provide proper focus and tracking control. will be.

On the other hand, the actuator of the optical pickup device in which the optical system B controlled by the circuit system A is installed is a device for driving the objective lens holder, in order to accurately irradiate the laser light focused by the objective lens onto the pit on the disc. The objective lens holder is finely driven in the radial direction of the disc and the laser beam axis to maintain the tracking and focusing of the laser light accurately.

As shown in FIG. 11, the optical pickup actuator according to the present invention includes an objective lens holder 101 on which the objective lens 100 is installed, a plate 120 on which the objective lens holder 101 is driven, It is attached to one side of the plate 120 is composed of a holder gel 140 to attenuate the vibration of the objective lens holder 100.

The objective lens holder 101 has a holder through-hole 102 through which laser light passes, and an objective lens 100 for converging laser light on an optical disc. The optical control plate 50, the integrated optical device 20, and the laser diode 10 are installed below the objective lens holder 101, and the driving force of the electromagnetic force line is generated around the objective lens holder 101. The focusing coil 335 for driving the lens 100 in the optical axis direction is wound, and a plurality of coils wound to one side of the objective lens holder 101 are installed to the outside of the focusing coil 335 so as to face each other. A tracking coil 345 for driving the objective lens holder 101 perpendicular to the optical axis is generated by generating a driving force, and the tracking coil 345 and the other side of the objective lens holder 101 outside the focusing coil 335 are attached. Coil to which focusing coil 335 is fused Seabiscuit is configured (110) is attached.

In addition, the tracking coil 345 is connected to the tracking control device 340 shown in FIG. 10, and the focus coil 335 is connected to the focus control device 330.

In addition, the plate 120 has a laser diode 10 having laser light emitted therein, and an inner yoke 125 having magnetic lines absorbed on both sides of the mounting surface of the integrated optical device 20. An outer yoke 126 to which the magnet 130 is attached is formed at both sides of the outer circumferential surface of the through hole 121, that is, the outer side of the inner yoke 125, and a holder yoke 131 is formed at one side of the plate 120. The holder yoke 131 is attached with a holder gel 140 into which a viscous force gel 141 is injected, and a suspension PC ratio 150 to which an input / output signal of a servo system is transmitted to one side of the holder gel 140. Is attached.

Thus, the coil PC 110 may apply an input / output signal of the suspension PC 150 to the focusing coil 335 and the tracking coil 345, and the suspension supporting the objective lens holder 101 to be driven on the plate 120. The wire 160 is fused to penetrate the holder gel 140, and the suspension wire 160 is fused to the suspension PCB 150 and is installed to be driven.

When the conventional optical pickup actuator having such a configuration is operated, first, when the play mode of the optical pickup apparatus is set, this reproduction signal is transmitted to the tracking control device 340 and the focus in the reproduction signal processing means 200 shown in FIG. Applied to the control device 330 and applied to the suspension PC ratio 150 again, the reproduction signal is detected by the suspension PC ratio 150 and the focusing error signal FES and the tracking error TES at the same time as the laser beam is emitted. Recognize it. The recognition signal is transmitted from the suspension PC ratio 150 to the suspension wire 160, and the recognition signal is applied to the coil PC ratio 110 by the suspension wire 160. The error recognition signal applied to the coil PC 110 is applied to the focusing coil 335 and the tracking coil 345, and the focusing coil 335 and the tracking coil () by the optical signals reflected from the optical discs 60 and 70. Current is applied to the 345 to generate an electromagnetic force. The objective lens holder 101 is driven in the direction of the laser beam axis and the direction perpendicular to the disk by the generated electromagnetic force, and the laser light is tracked and focused on the optical disks 60 and 70 by the driving of the objective lens holder 101. This correction is performed to form an accurate light spot and to read the optical information by the correct light quantity difference.

On the other hand, the objective lens holder 101 is driven according to the detection signal of the tracking error and the focusing error, the object lens holder 101 is driven by the suspension wire 160, so unnecessary of the objective lens holder 101 The residual driving force and the vibration applied to the actuator are rapidly attenuated by the gel 141 of the holder gel 140 to ensure accurate driving of the objective lens holder 101.

In addition, a gel in which the colloidal solution is solidified into a gel is injected into the holder gel 140 through which the suspension wire 160 penetrates to attenuate the residual vibration of the suspension wire 160. The gel is gelatin It is injected into the rectangular groove of the holder gel 140 as an elastic gel having elasticity by removing moisture from the phase.

In this way, the optical signal detected from the actuator of the optical pickup apparatus provided with the optical system B is applied to the circuit system A as an electrical signal, and the applied electrical signal is optical information read out on the optical disc by the circuit system A. Is output as an original audio signal and a video signal, and the output optical signal is demodulated by the circuit system A into an original signal so as to obtain user's desired optical information.

The optical element integrated dual focus optical pickup apparatus of the present invention changes the spherical aberration caused by the difference in the thickness of the optical disk and the recording surface of the signal information, thereby varying the incident light intensity distribution of the light beam incident on the objective lens. Actively converted, the spherical aberration is significantly reduced, enabling compatible playback of digital audio and digital video discs, and integrated optical systems that convert optical paths or read optical information, simplifying alignment of optical elements. At the same time, since each optical element is arranged at the correct position during manufacturing, it can reduce the manufacturing cost of the optical pickup device and improve the reliability, and there is no loss in the control of the amount of light, so the function of the optical pickup device is improved. It is effective.

Claims (10)

A transmissive wave plate 30 disposed below the optical discs 60 and 70 and retarding the phase of the laser light on the upper surface thereof, a multi-segment photodetector 40 in which reflected light is received from a lower side of the transmissive wave plate, and the photo; The reflective wavelength plate 24 provided on the opposite surface of the detector 40 converts the polarization of the reflected light, and condenses the light in front of the reflective wavelength plate 24 to shorten the optical path and at the same time the error signal. A polarization separation unit for forming a Fresnel lens 26 for generating astigmatism for detection, and a slanted surface between the Fresnel lens 26 and the photo detector 40 mounting surface to separate the optical path of the incident light and the reflected light An integrated optical element 20 consisting of 22; A laser diode 10 emitting laser light (P wave) polarized in a horizontal component with respect to the traveling direction of light from below the integrated optical element 20; Between the integrated optical device 20 and the optical disks 60 and 70, an inner circular plate 56 for transmitting narrow laser light at a first transmittance and an outer plate 57 for transmitting wide laser light at a second transmittance The light transmittance plate 50 is configured such that the first transmittance is set larger than the second transmittance; An objective lens 100 for condensing laser light via the light control plate 50 on the optical discs 60 and 70; Optical element integrated dual focus optical pickup device characterized in that it comprises an optical system (B) formed of the component. The apparatus of claim 1, wherein an electrical signal output from the integrated optical device 20 is applied to the optical system B to output a signal to the tracking control device 340 and the focus control device 330. 200 and the microcomputer 320 for selectively controlling the tracking control device 340, the focus control device 330, and the motor control device 310 by the electric signals output from the reproduction processing signal processing means 200, respectively. Optical element integrated dual focus optical pickup device, characterized in that further comprises a circuit system (A) consisting of. The optical device integrated dual type according to claim 1, wherein the polarization separator 22 transmits the laser light having a component parallel to the incident surface and reflects the laser light having a component perpendicular to the incident surface. Focus optical pickup device. The optical element integrated dual focus light according to claim 1, wherein the inner circular plate (56) has a transmissive film of 1 and the outer plate (57) has a semi-transmissive film (1/2). Pickup device. The optical element integrated dual focus optical pickup apparatus of claim 1, wherein the optical control plate (50) adjusts the outermost incident angles (θ1, θ2) of the laser light focused on the optical disc. The optical element integrated dual focus optical pickup apparatus of claim 1, wherein the light control plate is integrally installed with the objective lens. The actuator according to claim 1, wherein the actuator on which the optical system (B) is mounted comprises: an objective lens holder (101) on which the objective lens (100) is mounted, a plate (120) on which the objective lens holder (101) is driven, and And a holder gel (140) attached to one side of the plate (120) to attenuate vibration of the objective lens holder (100). 8. The optical device integrated device of claim 1, wherein the objective lens 100, the light control plate 50, and the integrated optical device 20 are integrally installed on the plate 120 and interlocked with an actuator. Dual focus optical pickup. 8. The objective lens holder (101) according to claim 7, wherein the objective lens holder (101) has a holder through hole (102) through which the laser light passes through the center, and the laser light on the optical discs (60, 70) on the upper side of the holder through hole (102). Around the objective lens 100 to focus, the optical control plate 50 and the integrated optical element 20 and the laser diode 10 provided below the objective lens holder 101, and around the objective lens holder 101 A focusing coil 335 for driving the objective lens 100 in the optical axis direction by generating a driving force of an electromagnetic force line, and a plurality of coils wound on one side of the objective lens holder 101 outside the focusing coil 335 The tracking coil 345 which is installed to face and generates the driving force of the electromagnetic force line to drive the objective lens holder 101 perpendicular to the optical axis, and the tracking coil on the other side of the objective lens holder 101 outside the focusing coil 335 345 and the coil PC (110) where the focusing coil (335) is fused Optical element integrated dual focus optical pickup device comprising a. 8. The plate (120) according to claim 7, wherein the plate (120) includes a laser diode (10) in which laser light is emitted in the center, an inner yoke (125) in which magnetic force lines are absorbed on both sides of the mounting surface of the laser diode (10), and the inner side thereof. An outer yoke 126 to which the magnet 130 is attached to the outside of the yoke 125, a holder yoke 131 formed on one side of the plate 120, and a holder gel in which gel is injected from the holder yoke 131. And a suspension PCB 150 to which an input / output signal of the circuit system A is applied to one side of the holder gel 140.

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