KR100255675B1 - 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 diffraction grating(30) is installed on a lower side of optical disks(60,70), and diffracts laser beams for error signal detecting on an upper surface. The first and the second light receiver(40,45) are installed by being faced with both lower sides of the diffraction grating(30). A reflection-typed wavelength plate(24) converts a polarization of a reflection light on an installed surface of the first light receiver(40). 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 wavelength plate(50) separately transmits the laser beams between the integrated optical element(20) and the optical disks(60,70), with different transmission rates according to optical width, and converts phases of the laser beams. 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 first light receiving part and a second light receiving part which are opposite to both sides of the rectangular standing surface, a reflective wave plate for converting the phase of reflected light on the mounting surface of the first light receiving part, and incident light for error detection on the upper side of the rectangular shape A diffraction grating diffracted into the main beam and the sub-beam, and a polarization splitting part formed on the inclined surface of the first light receiving part and the second light receiving part mounting surface to separate the optical paths of the incident light and the reflected light, and the like are formed below the optical disk. Integrated optical elements;

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 transmissive wave plate for converting the phase of the laser light, a combat film for transmitting a narrow laser light through the transmissive wave plate at a transmittance of 1, and the transmissive wave plate. An optical control wavelength plate composed of an outer plate formed of a semi-transmissive film for transmitting the laser light having a wide width at a transmittance of 1/2, and an optical control plate for controlling the outermost incident angle of the laser light focused on the optical disc;

It comprises an objective lens for focusing the laser light via the optical control wavelength plate 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;

4 is an installation state of the light receiving unit 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 showing that an error signal of an optical signal is detected 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

30: diffraction grating 40, 45: light receiving part

50: light control wavelength plate 54: transmission wave 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 includes an integrated optical device 20 that converts the path and polarization of the laser light under the optical discs 60 and 70, and receives the reflected light. The laser diode 10 emits a laser beam having a predetermined wavelength below the integrated optical device 20, and the laser light is transmitted between the integrated optical device 20 and the optical disks 60 and 70 at different transmittances depending on the width. And an objective lens 100 for focusing the optical disks 60 and 70 on the optical disks 60 and 70.

The integrated optical device 20 is formed of a rectangular glass face, and a diffraction grating 30 is installed on the top surface to diffract the laser light to detect an error signal so as to use a zero diffraction light and a first diffraction light. As a result, the first light receiving portion 40 and the second light receiving portion 45 are opposed to each other, standing on both sides under the installation surface of the diffraction grating 30. Since the plurality of light receiving parts 40 and 45 are spaced apart from each other to form an image at an arbitrary point between the light receiving parts, an optical signal is condensed on each of the light receiving parts 40 and 45, and the light signals are output as electrical signals. As shown in FIG. 4, each of the light receiving units 40 and 45 has three segments S, S1, S2, and S as the light receiving unit. ', S1', S2 '), and the center segments S, S' are divided into three (D, D1, D2, D 'D1', D2 '). Therefore, the reflected light irradiated to the center segments S and S 'detects a focus error and the segments S1, S2, S1' and S2 'on both sides detect the tracking error, i.e., the beam size method and the three beam method. By this, the focus error and tracking error signals are detected. In addition, a reflection type wave plate 24 is provided on the mounting surface of the first light receiving unit 40 to convert the phase of the reflected light. The reflection type wave plate 24 generally has a quarter wavelength using a birefringence phenomenon of a prism. The plate delays the phase of the laser light. In addition, the polarization separator 22 formed between the first light receiving part 40 and the second light receiving part 45 on the combing surface 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 incident light into the polarization separator 22, the incident light is transmitted, the light is passed through the light, and the light is reflected on the optical disks 60 and 70. Make the light path different.

In addition, the light control wavelength plate 50 is composed of a light control plate 52 and a transmission wavelength plate 54, which transmits and separates at different transmittances depending on the width of the incident light and retards the phase of the incident light. The printing plate 52 is composed of an inner circular plate 56 for overcoming narrow incident light at a transmittance of 1 and an outer plate 57 for semitransmitting incident light of a wide width at a transmittance of 1/2. The light regulating 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, the beam spot diameter can read an optical signal even if it is somewhat larger on the optical disk 70 having a thickness of 1.2 mm, so that the objective lens 100 having a 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.

When the aberration generation amount of Equation 4 is equal to the value compensated for defocusing and the spherical aberration is matched, the cumulative total of the optical system (B) of the present invention can be expressed by the aberration system from the relationship between the central intensity distribution and the wave aberration According to Marmarechal's criterion that the wave front aberration should be less than 0.07λ, the effect on the defocus can be eliminated, so it is approached to the aberration meter.

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 wavelength plate 50 to the optical discs 60 and 70 are adjusted by the equations 1 to 6, the numerical aperture is adjusted so that the optical disc 60 dedicated to the thickness of 0.6 mm. ) The dedicated 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 combating the narrow laser light, that is, the laser light around the optical axis. And compatible playback can be excellent.

Next will be described the operation of the present invention that is adopted by the optical control wavelength 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 diffraction grating 30, and the laser light is irradiated by the diffraction grating 30 to the main beam (zero order light) and the sub beam (± 1). Is diffracted by +/- 2, ..., of which 0-order light and ± 1-order light are used for tracking errors. Thus, the laser light diffracted in this way is irradiated from the diffraction grating 30, that is, the integrated optical element 20 to the light control wavelength plate 50, and the laser beam is controlled by the light control wavelength 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 beam passing through the inner circular plate 56 in the light control plate 52 of the light control wavelength plate 50 is overpowered, the outer plate 57 The laser beam passing through the beam is semi-transmissive so that the laser beam passes through the inner circular plate 56 and the outer beam 57 is focused on the optical axis via the objective lens 100 at the same time. The outgoing angle of the laser beam transmitted through the objective lens 100 is focused on the optical axis at θ2. That is, the laser beams passing through the light control plate 52 composed of the inner circular plate 56 and the outer plate 57 have different outer angles of incidence angles θ1 and θ2, respectively. The numerical aperture NA passes through the transmissive wave plate 54 at the same time. The thus transmitted laser light is polarized linearly by circularly polarized light by the transmission wavelength plate 54 of the light control wavelength plate 50. The laser light polarized by the circularly polarized light is irradiated onto the objective lens 100 from the light control wavelength plate 50 and focused on the optical disks 60 and 70.

By the way, the laser light focused by the objective lens 100 via the optical control wavelength plate 50 with the numerical apertures different from each other when the incident light on the optical disks 60 and 70 is incident to the outermost incident angles θ1 and θ2 of the laser light. As described above, the difference in the diameter of the light spot is smaller than the light transmitted through the outer plate 57 and collected through the inner circular plate 56 of the light control plate 52.

Thus, in the case of reproducing the respective optical disks 60 and 70, for example, the digital video disk 60 having a thickness of 0.6 mm, the external plate 57 is transflected so that the optical control wavelength plate 52 and the objective lens 100 are transmitted. By the numerical aperture 0.6, the optical spot having a size of about 0.8 占 퐉 is formed on the optical disc 60 at θ2 with respect to the optical axis, and the optical information is read out by the diffraction and the presence or absence of light on the recording surface 65. 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 polarized by the transmissive wave plate 54 to be objective lens 100. Is condensed at a numerical aperture of 0.3 and condensed on the optical disc 70 at θ1 with respect to the optical axis.

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 light control wavelength plate 50 via the objective lens 100. In the laser beam, circularly polarized light is polarized by linearly polarized light when the transmission wavelength plate 54 of the light control wavelength plate 50 is transmitted.

The inverted linearly polarized laser light is irradiated from the light control wavelength plate 50 to the polarization separator 22 of the integrated optical element 20, and the laser light of the linearly polarized light is reflected by the polarization separator 22. do. The reflected laser light is irradiated from the polarization separator 22 to the first light receiving part 40 and the reflective wavelength plate 24, and the laser light extracts a single optical signal to the first light receiving part 40 and reflects it. It is reflected by the wave plate 24 and at the same time, the reflection wave plate 24 is again phase-delayed by the laser light, ie, P-polarized light, of parallel components. Thus, the laser light is totally reflected by the reflective wavelength plate 24 and irradiated to the second light receiving portion 45 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 to each of the light receiving portion (40, 45) by the photoelectric effect It is converted into an electrical signal.

The conversion to the electrical signal is performed by the first and second light receiving units 40 and 45 as shown in FIGS. 4 and 8, respectively, in three segments S, S1, S2, S ', S1' and S2 '. The middle segments S and S 'are divided into three (D, D1, D2, D' D1 ', D2'). Therefore, the reflected light irradiated to the center segments S and S 'detects a focus error, and the segments S1, S2, S1' and S2 'on both sides detect the tracking error and are converted into an electrical signal by the photoelectric effect. As shown in FIG. 9, the electrical signals converted in each segment are respectively obtained from the RF signal calculator 210, the focusing error signal calculator 230, and the tracking error signal calculator 220. = S + S1 + S2 + S '+ S1' + S2 '), focusing error signal (FES = {D + {D1' + D2 '}}-{D' + {D1 + D2}}) and tracking error signal It is calculated and output as (TES = {S1 + S2 '}-{S2 + S1'}).

In this way, the electrical signals converted from the first light receiving portion 40 and the second light receiving portion 45 are applied to the reproduction signal processing means 200 from the respective computing devices 220 and 230, and among these signals, the tracking error signal calculating device ( The signal calculated by the 220 and the focusing 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 the focus error signal. . 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 electric signal detected by each of the light receiving units 40 and 45 reflected by the 0.6 mm thick optical disk 60 and the 1.2 mm thick optical disk Since the voltage value reflected and detected by 70 is set to the offset voltage value in the focus control device 330, the initial focus positions according to the different optical discs 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. In processing the signals output from the respective photodetectors 40 and 45, the RF signal is determined. The difference in the amount of reflected light due to the thickness difference between the optical disks 60 and 70 is initially set so that an RF signal is not generated during the reproduction of the optical disk 60 having a thickness of 0.6 mm, and only when the optical disk 70 having a 1.2 mm thickness is reproduced. The signal is generated, which will be described in more detail as follows.

First, when a reproduction signal is detected by the photodetectors 40 and 45 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 of FIG. As shown in A), 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 a reproduction signal is detected by the optical detectors 40 and 45 on the digital video disk 60 having a thickness of 0.6 mm by the optical system B shown in FIG. 6, the actuator is transferred and a high frequency (RF) signal is generated. 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 signals of the photodetectors 40 and 45. When this signal path is set, the gain is reproduced when the digital video disc 60 is reproduced. An output signal is applied from an unillustrated OP-AMP (Operationl Amplifier) output stage having (G1, G2, G3), and OP- having gains (G1 ', G2', G3 ') during reproduction of the digital audio disc 70. Output signals are applied from the AMP output stage. 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 wavelength plate 50, the integrated optical element 20, and the laser diode 10 are installed below the objective lens holder 101, and generate driving force of the electromagnetic force line around the objective lens holder 101. Focus coils 335 for driving the objective lens 100 in the optical axis direction are wound, and a plurality of coils wound to one side of the objective lens holder 101 are provided to the outside of the focus coil 335 to face each other. A tracking coil 345 for driving the objective lens holder 101 perpendicular to the optical axis by generating a driving force of the electromagnetic force line is attached, and a tracking coil 345 on the other side of the objective lens holder 101 outside the focus coil 335. And the nose to which the focus coil 335 is fused One PC 110 is attached to the configuration.

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, a suspension for applying the input / output signal of the suspension PCB 150 to the focus coil 335 and the tracking coil 345 to the coil PC 110 and 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 focus coil 335 and the tracking coil 345, and the focus coil 335 and the tracking coil () by the optical signals reflected from the optical disks 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 (13)

A diffraction grating 30 disposed below the optical discs 60 and 70 and diffracting the laser light for error signal detection on an upper surface thereof, and a first light receiving part 40 disposed to face both sides below the diffraction grating 30; And a second wavelength receiving part 45, a reflective wavelength plate 24 for converting the polarization of the reflected light on the mounting surface of the first light receiving part 40, and the first light receiving part 40 and the second light receiving part 45. An integrated optical element 20 formed on the hypotenuse of the installation surface and formed of a polarization separator 22 separating the optical paths of the incident light and the reflected light; 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; An optical control wavelength plate 50 which separates and transmits the laser light between the integrated optical device 20 and the optical disks 60 and 70 at different transmittances according to the widths, and converts phases; An objective lens 100 for condensing laser light via the optical control wavelength 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. 2. The light control wavelength plate (50) according to claim 1, wherein the light control wavelength plate (50) separates and transmits the transmission type wavelength plate (54) for delaying the phase of the laser light and the laser beam passing through the transmission type wavelength plate (54) at different transmittances depending on the width. Optical element integrated dual focus optical pickup device, characterized in that consisting of a light control plate (52). 5. The light regulating plate (52) according to claim 4, wherein the light regulating plate (52) comprises an inner circular plate (56) for transmitting a narrow laser light at a first transmittance, and an outer plate (57) for transmitting a wide laser light at a second transmittance. An optical element integrated dual focus optical pickup apparatus, characterized in that the first transmittance is set larger than the second transmittance. The optical element integrated dual focus light according to claim 5, 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 (52) 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 laser diode (10) emits laser light (P wave) polarized in a horizontal component with respect to a traveling direction of light. 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). The optical 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 to interlock with an actuator. Dual focus optical pickup. 12. The objective lens holder (101) according to claim 10, wherein the objective lens holder (101) has a holder through hole (102) through which laser light passes through the center, and the laser light on the optical disks (60, 70) above the holder through hole (102). Generates the driving force of the electromagnetic force line around the objective lens 100 to focus, the optical control plate 50 and the integrated optical element 20 provided below the objective lens holder 101, and the objective lens holder 101 A focus coil 335 for driving the objective lens 100 in the optical axis direction, and a plurality of coils wound on one side of the objective lens holder 101 from the outside of the focus coil 335 are installed to face each other. The tracking coil 345 for driving the objective lens holder 101 perpendicular to the optical axis by generating a driving force of the tracking coil, and the tracking coil 345 and the focus coil on the other side of the objective lens holder 101 outside the focus coil 335. 335 is made, including the coil PC 110 to be fused The optical element integrated dual focus optical pickup apparatus is characterized in that. 11. The plate 120 includes an integrated optical element 20 having laser light emitted therein, an inner yoke 125 having magnetic lines of force absorbed on both sides of an installation surface of the laser diode 10, An outer yoke 126 to which the magnet 130 is attached to the outside of the inner yoke 125, a holder yoke 131 formed on one side of the plate 120, and a holder in which gel is injected from the holder yoke 131. An optical element integrated dual focus optical pickup apparatus comprising a gel (140) and a suspension PC (150) to which an input / output signal of the circuit system (B) is applied to one side of the holder gel (140).

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