KR100238281B1 - Compatible optical pickup apparatus - Google Patents

Abstract

Disc-compatible optical pickup apparatus capable of interchangeably employing disc-type recording media having different formats.

The disclosed compatible optical pickup apparatus includes: a first optical unit for generating and irradiating light of a first wavelength and receiving incident light to detect information and an error signal of a recording medium; A second optical unit for generating and irradiating light having a second wavelength different from the first optical unit and receiving incident light to detect information and an error signal of a recording medium; An objective lens disposed on an optical path between the first and second optical units and the recording medium and converging incident light to be formed on the recording medium; A first reflecting surface disposed on an optical path between the first and second optical units and the objective lens, the first reflecting surface reflecting light of a first wavelength incident to be inclined to face the first optical unit and the objective lens, and a second A focal position where light emitted from each of the first and second optical units is formed, including an optical coupler and an optical coupler disposed to be inclined to face the optical lens and the objective lens, the optical coupler having a second reflection surface reflecting light of an incident second wavelength. It is characterized by being different from each other.

Description

Compatible optical pickup apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compatible optical pickup apparatus, and more particularly, to a disc compatible optical pickup apparatus capable of interchangeably employing disk-type recording media having different formats.

In general, an optical pickup apparatus is employed in a compact disc player (CDP), a digital video disc player (DVDP), a CD-ROM drive, a DVD-ROM drive, or the like to perform recording / reproduction of information on a recording medium in a non-contact manner.

DVDP and DVD-ROM drives are attracting attention in the video / audio field as devices capable of high-density recording / playback. The optical pickup device employed in this DVDP employs not only digital video discs (DVDs) but also compact discs (CDs), CD-Rs (Recordables), CD-Is, and CD-Gs as recording media for compatibility. Even if so, it should be possible to record and / or reproduce information.

However, the thickness of the DVD has been standardized to a different specification from the thickness of the CD family due to mechanical disc tilt tolerance and objective lens numerical aperture. That is, the thickness of the existing CD family is 1.2mm while the DVD is 0.6mm. As described above, since the thicknesses of the CD family and the DVD are different from each other, spherical aberration due to the difference in thickness occurs when the optical pickup device for DVD is applied to the CD family. This spherical aberration causes a problem of failing to obtain sufficient light intensity for recording the information signal or deterioration of the signal during reproduction.

Also, in the wavelength of the reproduction light source, DVD has been standardized into a wavelength range different from that of the CD family. That is, the wavelength of the reproduction light source for the existing CD family is approximately 780 nm, while the wavelength of the reproduction light source is approximately 650 nm.

Due to such a difference in standardization, since information recorded on a DVD cannot be reproduced by a normal CDP, development of an optical pickup device for a DVD is required. At this time, the optical pickup device for DVD should also be compatible with the existing CD family.

In view of the foregoing, a disc-compatible optical pickup device having different formats has been disclosed.

Disclosed disc compatible optical pickup devices use a single light source to focus on overcoming problems caused by the difference in thickness between discs. A light source that emits short wavelength (approximately 650 nm) light suitable for the DVD format is employed. In this case, deterioration of about 5% occurs as compared with an optical pickup apparatus employing a light source that emits light in the 780 nm wavelength region, but this is not a big problem because it is within the tolerance range during reproduction.

However, in the case where CD-R, which is a recordable disc of the CD family, is used as the recording medium, when using a light source that emits light in an approximately 650 nm wavelength region, as shown in FIG. It differs from the case where the light source which emits the light of an area is employ | adopted. Since the CD-R has an organic dye film recording layer as is well known, when the light of the 650 nm wavelength region is used due to the difference in sensitivity, the reflectance of the disk is low and the signal cannot be reproduced.

In order to overcome this problem, as shown in FIG. 2, a compatible optical pickup apparatus employing two light sources has been disclosed.

As shown, the first light source 21 emits light having a wavelength of 635 nm as a light source, and the second light source 31 emits light having a wavelength of 780 nm. The first light source 21 is for a relatively thin disk 10a, for example a DVD, and the second light source 31 is for a relatively thick disk 10b, for example, a CD family.

The light emitted from the first light source 21 is reflected by the polarization beam splitter 23 and directed toward the disk 10. In this case, the interference filter 33, the quarter-wave plate 11, the hologram element 13, and the objective lens 15 are positioned on the optical path between the polarization beam splitter 23 and the disk 10. The interference filter 33 reflects the light emitted from the second light source 31 toward the disk 10 and transmits the light incident from the disk 10. The quarter-wave plate 11 is an optical member for converting the polarization state of the incident light. The light irradiated from the first light source 21 and the second light source 31 passes through the quarter-wave plate 11 twice, and the polarized light splitter 23 is rotated by 90 °. The light detector 17 passes through the polarization beam splitter 23 and detects an information signal and an error signal. The hologram element 13 has a predetermined diffraction pattern formed at the center of the surface thereof. Since the light emitted from the first light source 21 is incident to a larger area than the region where the diffraction pattern is formed, the light is passed through the hologram element 13 in a non-diffracted state, i. It forms on the disk 10a.

On the other hand, the light emitted from the second light source 31 is diffracted at the small divergence angle in the hologram element 13. This diffracted + first order diffracted light is formed on the disk 10b having a relatively thick thickness.

The objective lens 15 causes the light emitted from the first light source 21 and the second light source 31 to be formed on the recording surface of the disc 10. In this case, the light spot emitted from the first light source 21 and the light emitted from the second light source 31 form light spots at different positions.

In this way, the compatible optical pickup device provided can be used even when CD-R is employed as the recording medium by using two wavelengths.

However, since the hologram element 13 in which the diffraction pattern is formed on the predetermined area is disposed on the optical path, it is substantially the same as using two lenses, making it difficult to miniaturize and optically arrange the device. In addition, although there is an advantage of using one photodetector, it is difficult to assemble because the alignment of the optical axis of the photodetector is required for two lights having different wavelengths at the same time.

Accordingly, an object of the present invention is to provide a compatible optical pickup apparatus capable of interchangeably employing different disks having a simple optical structure and a format that is easy to arrange optically. There is this.

1 is a graph showing the sensitivity according to the wavelength of a light source when CD-R is employed as a recording medium.

Figure 2 is a schematic configuration showing an optical arrangement of a conventional compatible optical pickup device.

3 is a schematic diagram showing an optical arrangement of a compatible optical pickup device according to a first embodiment of the present invention.

Figure 4 is a graph showing the light transmittance according to the wavelength at each of the first and second reflective surface of the optical coupler according to the present invention.

5 is a schematic diagram showing an optical arrangement of a compatible optical pickup device according to a second embodiment of the present invention.

6 is a schematic diagram showing an optical arrangement of a compatible optical pickup apparatus according to a third embodiment of the present invention.

7 is a schematic diagram showing an optical arrangement of a compatible optical pickup apparatus according to a fourth embodiment of the present invention.

8 is a schematic cross-sectional view showing the light source and the photodetector integrated optical module shown in FIG.

9 is a schematic diagram showing an optical arrangement of a compatible optical pickup apparatus according to a fifth embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

10 Recording medium 100 First optical unit 111,131 First light source

113 first beam splitter 113 a first mirror

115 1st cylindrical lens 120,140 1st photodetector

133 The first hologram element 135 The first housing 150 The first mount

155 1st lead 161 1st board

200 ... 2nd optical unit 211,231 ... 2nd light source

213 ... 2nd beam splitter 213a ... 2nd mirror

215 2nd cylindrical lens 220,240 2nd photodetector

233 2nd hologram element 235 2nd housing 250 2nd mount

255 ... 2nd lead 261 ... 2nd substrate 300 ... optical coupler

310 ... first reflecting surface 320 ... second reflecting surface 330 ... objective lens

340 collimating lens 350 variable aperture

In order to achieve the above object, the compatible optical pickup device according to the present invention, the first optical unit for generating and irradiating the light of the first wavelength and receiving the incident light to detect information and error signals of the recording medium Wow; A second optical unit for generating and irradiating light having a second wavelength different from the first optical unit and receiving incident light to detect information and an error signal of a recording medium; An objective lens disposed on an optical path between the first and second optical units and the recording medium and converging incident light to be formed on the recording medium; A first half disposed on an optical path between the first and second optical units and the objective lens and disposed to be inclined to face the first optical unit and the objective lens to reflect light of the first wavelength incident thereto; Each of the first and second optical units including an optical coupler having an inclined surface and a second reflecting surface disposed to be inclined to face the second optical unit and the objective lens and reflecting light of the second wavelength incident thereto. It is characterized in that the focal positions formed by the light emitted from the different from each other.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention;

3 is a schematic view showing an optical arrangement of a compatible optical pickup device according to a first embodiment of the present invention.

As shown, the compatible optical pickup device generates and emits light having different wavelengths, and receives the light reflected from the recording medium 10 to detect information and error signals of the recording medium 10. And an objective lens 330 for focusing incident light onto a recording surface of the recording medium 10, the first and second optical units 100 and 200, and the objective lens. First and second reflecting surfaces disposed on an optical path between the first and second optical units 100 and 200 to guide light incident from the first and second optical units 100 and 200 toward the recording medium 10. And an optocoupler 300 having 310 and 320.

The first optical unit 100 is a first about 650 nm suitable for the case where a relatively thin disk 10a such as a DVD or a DVD-ROM, for example, a 0.6 mm thick disk is employed as the recording medium 10. Generate and emit light of the wavelength. On the other hand, the second optical unit 200 is approximately 780 nm suitable for the case where a relatively thick disk 10b such as a CD family, especially a CD-R, for example, a 1.2 mm thick disk is employed as the recording medium 10. Generate and emit light of a second wavelength of. Here, the first optical unit 100 and the second optical unit 200 are located on different optical paths, and are selectively driven according to the type of disc employed as the recording medium 10.

The driving mechanism of the first optical unit 100 and the second optical unit 200 may be a manual method in which a user selects a type of the recording medium 10 employed, and a type of the recording medium 10 employed. It can be divided into automatic methods that are automatically detected and selected by the disc player. Since such a driving mechanism is widely known, its detailed description is omitted.

It is preferable that the divergence angle of the light emitted from the first optical unit 100 and the divergence angle of the light emitted from the second optical unit 200 are the same. This is to change the parallel light for each of the two divergent angles when employing the collimating lens (340 of FIG. 5) to be described later. On the other hand, the distance between the first optical unit 100 and the optical coupler 300 is disposed relatively larger than the distance between the second optical unit 200 and the optical coupler 300, the first The area of light occupying the reflective surface 310 is preferably larger than the area of light occupying the second reflective surface 320. This is for the focal position of the light emitted from the first optical unit 100 to pass through the objective lens 330 to be formed on the relatively thin disk 10a.

The first optical unit 100 is disposed between the first light source 111 for generating and outputting laser light having a first wavelength and the first light source 111 and the optical coupler 300 to provide a path of incident light. The first beam splitter 113 to be converted and the light incident through the optical coupler 300 are received through the first beam splitter 113 to detect the information signal and the error signal of the recording medium 10. And a first photodetector 120. The first beam splitter 113 includes a first mirror surface 113a disposed obliquely with respect to the light source 111 and the optical coupler 300, and includes a normal beam that transmits or reflects incident light by a predetermined light quantity ratio. It is a splitter or a polarizing beam splitter which transmits or reflects according to the polarization component of incident light. A first cylindrical lens 115 is further provided on the optical path between the first beam splitter 113 and the first photodetector 120 to cause astigmatism.

The second optical unit 200 includes a second light source 211, a second beam splitter 213, a second cylindrical lens 215, and a second photodetector 220. The optical arrangement of the second optical unit 200 and its role is substantially performed by the first light source 111, the first beam splitter 113, the first cylindrical lens 115, and the first optical unit 100. Since it is the same as or similar to the first photodetector 120, a detailed description thereof will be omitted. However, the first light source 111 emits light having a first wavelength, for example, 650 nm, while the second light source 211 emits light having a second wavelength, for example, 780 nm.

The optical coupler 300 changes the traveling path of the light incident from the first optical unit 100 and the second optical unit 200 toward the objective lens 330. To this end, the optical coupler 300 is disposed to be inclined such that the first reflective surface 310 faces the first optical unit 100 and the objective lens 330. The second reflecting surface 320 is disposed to be inclined to face the second optical unit 200 and the objective lens 330. The characteristics of the first reflective surface 310 and the second reflective surface 320 will be described with reference to FIG. 4. Each of the first reflecting surface 310 and the second reflecting surface 320 is coated to transmit light of a predetermined wavelength region and reflect light of another wavelength region. Referring to FIG. 4, as shown by the curve B, the first reflection surface 310 totally reflects wavelengths of less than about 700 nm, and transmits about 85% of wavelengths of about 730 nm or more. On the other hand, as shown by the curve A, the second reflecting surface 320 totally reflects a wavelength of about 730 nm or more and transmits about 85% of a wavelength of less than about 700 nm. As described above, by forming the first reflection surface 310 and the second reflection surface 320, light of the first wavelength is generally transmitted to the second reflection surface 320, and the first reflection surface ( In 310, it is totally reflected. On the other hand, light of the second wavelength is generally transmitted through the first reflection surface 310 and totally reflected by the second reflection surface 320. Accordingly, the optical coupler 300 may separate the path of the light of the first wavelength and the light of the second wavelength.

The objective lens 330 is a member that focuses the light emitted from the first and second light sources 111 and 211 to form a light spot on the recording medium 10. In order to be mounted on the actuator (not shown) is driven. The objective lens 330 may be processed into a spherical surface so as to be suitable for any one of recording media having different thicknesses, and the Korean Patent Application No. 95-31679 (objective lens 330) apparatus and stabilized by the present applicant. A method of obtaining a focus servo signal, an optical pickup apparatus employing the same, a method of discriminating disks of different thicknesses, a method of reproducing and recording information from disks of different thicknesses, and a method of manufacturing a lens), and Korean Patent Application No. The objective lens 330 device proposed through the objective lens 330 device and the optical pickup device employing the objective lens 330 device may be employed.

A compatible optical pickup apparatus according to a second embodiment of the present invention will be described with reference to FIG. As shown, the compatible optical pickup apparatus according to the second embodiment of the present invention is substantially the same as the compatible optical pickup apparatus according to the first embodiment described with reference to FIG. However, in the optical configuration, the collimating lens 340 is further provided on the optical path between the optical coupler 300 and the objective lens 330. Here, the members using the same member number as in FIG. 3 are the same or similar members as in FIG. 3, and a detailed description thereof will be omitted.

The collimating lens 340 converts divergent light incident from the optocoupler 300 into parallel light.

As described above, the distance between the objective lens 330 and the optical coupler 300 is adjusted by employing the collimating lens 340 on the optical path between the optical coupler 300 and the objective lens 330. Can be facilitated.

A compatible optical pickup apparatus according to a third embodiment of the present invention will be described with reference to FIG. The compatible optical pickup apparatus according to the third embodiment of the present invention is substantially the same as the compatible optical pickup apparatus according to the first and second embodiments of the present invention described with reference to FIGS. 3 and 5. However, in the optical configuration, the variable stop 350 is further provided on the optical path between the optical coupler 300 and the objective lens 330. The variable stop 350 determines the transmission region of the incident light. For example, when the first optical unit 100 operates, the opening 350a is adjusted to be different from the transmission region of the light when the second optical unit 200 operates, thereby transmitting the objective lens 330. Thus, the focus position of the light spot formed on the recording medium 10 can be changed. Here, the members using the same reference numerals as those of Figs. 3 and 5 are the same or similar members as those of Figs.

7 and 8, the optical arrangement of the compatible optical pickup apparatus according to the fourth embodiment of the present invention will be described in detail.

As shown, the compatible optical pickup apparatus according to the fourth embodiment of the present invention generates light of the first and second wavelengths and receives light reflected from the recording medium 10, respectively. The optical coupler 300 having the first and second optical units 100 and 200, the first and second reflecting surfaces 310 and 320 to selectively transmit and reflect reflecting wavelengths, and incident light And an objective lens 330 to be attached to the recording medium 10. The optical configuration and function of the optical coupler 300 and the objective lens 330 are optical couplers according to the first, second and third embodiments of the present invention described with reference to FIGS. 3, 5 and 6. 300 and the objective lens 330 are substantially the same, detailed description thereof will be omitted.

The compatible optical pickup apparatus according to the fourth embodiment of the present invention is characterized in that each of the first and second optical units 100 and 200 is optically modularized.

The first optical unit 100 is disposed on an optical path between the first light source 131 and the first light source 131 and the optical coupler 300 to generate and emit laser light having a first wavelength. The first hologram element 133 which transmits light incident from the first light source 131 side and the light incident from the optocoupler 300 is diffracted and transmitted by diffraction transmission of the first hologram element 133. And a first photodetector 140 which receives light and detects an information signal and an error signal of the recording medium 10. In addition, the first optical unit 100 includes a first substrate 161 on which the first light source 131 and the first photodetector 140 are installed, and surrounds the first substrate 161 and the first hologram. A first housing 135 having a projection hole in which the element 133 is installed, and formed through the first substrate 161 and electrically connected to the first light source 131 and the first photodetector 140. It further comprises a plurality of first leads (155). Here, when the edge-emitting laser is employed as the first light source 131, as shown in the drawing, the first light source 131 is one side of the first mount 150 provided on the first substrate 161 Is installed on.

The second optical unit 200 is disposed on an optical path between the second light source 231 and the second light source 231 and the optical coupler 300 to generate and emit laser light having a second wavelength. The second hologram element 233 which transmits light incident from the second light source 231 side and transmits the light incident from the optocoupler 300 side is diffracted and transmitted through the second hologram element 233. And a second photodetector 240 which receives light and detects an information signal and an error signal of the recording medium, for example, a disk having a relatively thick thickness. In addition, the first optical unit 100 may include a second substrate 261 on which the second light source 231 and the second photodetector 240 are installed, and the second substrate 261. A second housing 235 having a projection hole in which the element 233 is installed, and formed through the second substrate 261 and electrically connected to the second light source 231 and the second photodetector 240. It further comprises a plurality of second leads (255). Here, when the edge-emitting laser is employed as the second light source 231, as shown in the drawing, the second light source 231 is one side surface of the second mount 250 provided on the second substrate 261. Is installed on.

The first optical unit 100 and the second optical unit 200 have substantially the same optical configuration, and the difference between the wavelengths of light emitted from the first and second light sources 131 and 231 are different from each other. have. For example, the first wavelength of light emitted from the first light source 131 is light of a 650 nm wavelength region suitable when the relatively thin disk 10a is employed as the recording medium 10. On the other hand, the light of the second wavelength emitted from the second light source 231 is light of a 780 nm wavelength region suitable when the relatively thick disk 10b is employed as the recording medium 10.

As described above, the structure of the first optical unit 100 and the second optical unit 200 can be made compact by modularizing each of them.

A compatible optical pickup apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. As shown, the compatible optical pickup apparatus according to the fifth embodiment of the present invention is substantially the same as the compatible optical pickup apparatus according to the fourth embodiment described with reference to FIGS. 7 and 8. However, in the optical configuration, the collimating lens 340 is further provided on the optical path between the optical coupler 300 and the objective lens 330. Here, the members using the same member number as in FIG. 7 are the same or similar members as in FIG. 7, and a detailed description thereof will be omitted.

The collimating lens 340 converts divergent light incident from the optocoupler 300 into parallel light.

As described above, the distance between the objective lens 330 and the optical coupler 300 is adjusted by employing the collimating lens 340 on the optical path between the optical coupler 300 and the objective lens 330. Can be facilitated. Although not shown, a variable aperture 350 may be further provided on the optical path between the collimating lens 340 and the objective lens 330 to limit a light transmission area of incident light.

Although the present invention has been described with reference to the embodiments illustrated in the accompanying drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. .

As described above, the compatible optical pickup apparatus according to the embodiments of the present invention configured includes first and second optical units configured to emit light having different wavelengths, and selectively depending on the type of recording medium employed. By using this, it is possible to fundamentally prevent data from being destroyed upon reproduction of information recorded on a CD family, in particular, a CD-R made of an organic dye recording film layer. Further, by selectively using two optical units, the life of the optical pickup device can be extended. In addition, by employing the above-described optical coupler, the optical configuration of the optical system can be greatly simplified.

Claims (13)

A first optical unit including a first light source for generating and irradiating light of a first wavelength and a first light detector for receiving the light reflected from the recording medium to detect information and an error signal of the recording medium; A second optical source including a second light source for generating and irradiating light having a second wavelength different from the first optical unit, and a second optical detector for receiving information reflected from the recording medium and detecting information and error signals of the recording medium; A unit; An objective lens disposed on an optical path between the first and second optical units and the recording medium and converging incident light to be formed on the recording medium; A first half disposed on an optical path between the first and second optical units and the objective lens and disposed to be inclined to face the first optical unit and the objective lens to reflect light of the first wavelength incident thereto; Each of the first and second optical units including an optical coupler having an inclined surface and a second reflecting surface disposed to be inclined to face the second optical unit and the objective lens and reflecting light of the second wavelength incident thereto. Compatible optical pickup device, characterized in that the focal position formed by the light emitted from the different from each other. 2. The compatible optical pickup apparatus of claim 1, wherein the first wavelength is about 650 nm and the second wavelength is about 780 nm. The light emitting device of claim 2, wherein each of the first and second optical units emits light having the same divergence angle. The distance between the first optical unit and the optical coupler is disposed relatively larger than the distance between the second optical unit and the optical coupler, so that the area of the light occupying the first reflective surface is the second reflective surface. Compatible optical pickup device characterized in that the area larger than the occupied light. The collimating lens according to any one of claims 1 to 3, further comprising a collimating lens disposed on an optical path between the optocoupler and the objective lens to convert incident divergent light into parallel light. Compatible optical pickup device. The compatible optical pickup according to any one of claims 1 to 3, further comprising a variable aperture disposed on an optical path between the optical coupler and the objective lens to determine a transmission region of incident light. Device. The method of claim 1, wherein the first optical unit, Disposed between the first light source, the first photodetector, and the optical coupler, the light irradiated from the first light source is directed to the optical coupler, and the light incident from the optical coupler is directed to the first photodetector; And a first beam splitter for converting a path of incident light to face the first beam splitter. 7. The compatible optical pickup apparatus of claim 6, further comprising a first cylindrical lens that causes astigmatism on an optical path between the first beam splitter and the first photodetector. The method of claim 1, wherein the first optical unit, Disposed between the first light source, the first photodetector, and the optocoupler, the light irradiated from the first light source passes straight toward the optocoupler, and the light incident from the optocoupler side is directed to the first photodetector And a first hologram element to diffractly transmit toward. The method of claim 6, wherein the first optical unit, A first housing having a first substrate on which the first light source and the first photodetector are installed; a first housing having a projection hole surrounding the first substrate and on which the first hologram element is installed; and formed through the first substrate. And a plurality of first leads electrically connected to the first light source and the first photodetector. The method of claim 1 or claim 6, wherein the second optical unit, Disposed between the second light source, the second photodetector, and the optocoupler, and the light irradiated from the second light source is directed to the optocoupler, and the light incident from the optocoupler side is directed to the second photodetector; And a second beam splitter for converting a path of incident light to face the second beam splitter. 11. The compatible optical pickup apparatus of claim 10, further comprising a second cylindrical lens that causes astigmatism on an optical path between the second beam splitter and the second photodetector. The method of claim 1 or claim 6, wherein the second optical unit, Disposed between the second light source, the second photodetector, and the optical coupler, the light irradiated from the second light source passes straight toward the optical coupler, and the light incident from the optical coupler side passes to the second photodetector; And a second hologram element for diffraction transmission toward the light source. The method of claim 12, wherein the second optical unit, A second housing having the second light source and a second substrate on which the second photodetector is installed, a second housing having a projection hole surrounding the second substrate and on which the second hologram element is installed, and penetrating through the second substrate; And a plurality of second leads electrically connected to the second light source and the second photodetector.

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