Optical pickup and optical disc read-write device

Abstract

The embodiment of the invention provides an optical pickup and an optical disc read-write device, relates to the technical field of optical disc read-write, and aims to solve the problem that the service life of the optical pickup and the service life of an optical disc driver are limited by the service life of a laser. The optical pickup comprises a light source part and an action part, wherein the light source part is used for generating a light source beam projected to the action part; and the action part is used for receiving the light source beam and performing data reading and writing on the optical disk by using the light source beam. At least part of wavelength in the light source beam is a first wavelength, the light source part comprises N first wavelength lasers, the first wavelength lasers are used for generating first wavelength laser beams of the first wavelength, and the first wavelength laser beams are used for forming the light source beam. Wherein N is a positive integer greater than or equal to 2; the N first wavelength lasers can work alternately under the control of the control circuit. The optical pickup can be applied to an optical disc read-write device.

Description

Technical Field

[0001] The present application relates to the technical field of optical disc reading and writing, and in particular to an optical pickup and an optical disc reading and writing device. Background Art

[0002] An optical drive (abbreviated as an optical drive in this article) refers to a device that uses lasers to write or read data on various types of optical discs, such as CDs (Compact Discs), DVDs (Digital Video Discs), and BDs (Blu-ray Discs). The optical pickup is a key component in an optical drive for laser writing, reading, and servoing optical discs, which usually includes components such as lasers, objective lenses, and photoelectric sensors.

[0003] However, since the continuous light emission life of the laser is limited, the service life of the optical pickup and the optical disk drive is restricted. Summary of the invention

[0004] The embodiments of the present application provide an optical pickup and an optical disc reading and writing device, which are used to improve the problem that the service life of the optical pickup and the optical disc drive is restricted by the service life of the laser.

[0005] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides an optical pickup, which includes a light source part and an active part. The light source part is used to generate a light source beam projected to the active part; the active part is used to receive the light source beam and use the light source beam to read and write data on an optical disc.

[0007] At least part of the wavelength of the light source beam is the first wavelength. The light source part includes N first wavelength lasers. The first wavelength lasers are used to generate a first wavelength laser beam of a first wavelength. The first wavelength laser beam is used to form the light source beam.

[0008] Wherein, N is a positive integer greater than or equal to 2; the N first wavelength lasers can work in succession under the control of the control circuit.

[0009] In the optical pickup provided in the embodiment of the present application, the light source part is provided with two or more identical first wavelength lasers, and each first wavelength laser can provide a laser beam used as a working beam for the operation of the optical pickup. The first wavelength laser in the light source part can also take over the work under the control of the control circuit, so that the service life of the optical pickup can get rid of the limitation of the service life of a single laser, and extend the service life of the optical pickup; and compared with the optical pickup in the related art that needs to be replaced as a whole due to laser failure, the method of setting two or more first wavelength lasers has obvious cost advantages.

[0010] In some embodiments, the light source part also includes a first beam combining device and a first diffraction grating; wherein the first beam combining device is used to receive the first wavelength laser beam generated by N first wavelength lasers and project the first wavelength laser beam onto the first diffraction grating.

[0011] The first diffraction grating is used to split the first wavelength laser beam into a first beam, a second beam and a third beam, and project the first beam, the second beam and the third beam to the action portion.

[0012] The active part is used to receive the first light beam, the second light beam and the third light beam, and use the first light beam to perform data reading and writing and focusing servo on the optical disc, and use the second light beam and the third light beam to perform tracking servo on the optical disc.

[0013] In the optical pickup provided in the embodiment of the present application, the light source part adopts a first wavelength laser to realize functions such as data reading and writing and servo control of the optical disc. The optical path is simple, easy to implement, and conducive to reducing costs.

[0014] In some embodiments, in the light source part, N is 2, and the two first wavelength lasers are respectively a first laser and a second laser.

[0015] The first laser is used to generate a first laser beam, and the second laser is used to generate a second laser beam; the wavelength of the first laser beam is a first wavelength, and it is linearly polarized light in a first polarization direction; the wavelength of the second laser beam is the first wavelength, and it is linearly polarized light in a second polarization direction; the first polarization direction and the second polarization direction are perpendicular to each other.

[0016] The first beam combining device includes a first polarization beam splitter prism, which is used to receive the first laser beam and the second laser beam, convert the polarization direction of the second laser beam into the first polarization direction, and project the first laser beam and the second laser beam onto the first diffraction grating.

[0017] In the optical pickup provided in the embodiment of the present application, the light source part adopts two first wavelength lasers, and combines the light through a polarization beam splitter prism, which has the advantages of simple optical path, easy implementation and low cost.

[0018] In some embodiments, the light source part further includes a first beam combining device, a second beam combining device and a second wavelength laser, wherein the first beam combining device is used to receive the first wavelength laser beams generated by N first wavelength lasers and project the first wavelength laser beams to the second beam combining device.

[0019] The second wavelength laser is used to generate a second wavelength laser beam of a second wavelength and project the second wavelength laser beam to the second beam combining device; the second beam combining device is used to combine the first wavelength laser beam and the second wavelength laser beam and project them to the active part.

[0020] The active part is used to receive the first wavelength laser beam and the second wavelength laser beam, and use the first wavelength laser beam to write data to the optical disc, use the second wavelength laser beam to perform tracking servo on the optical disc, use the first wavelength laser beam or the second wavelength laser beam to read data from the optical disc, and use the first wavelength laser beam or the second wavelength laser beam to perform focusing servo on the optical disc.

[0021] In the optical pickup provided in this embodiment, two lasers with different wavelengths are used to implement functions such as data writing, data reading, focusing servo and tracking servo on the optical disc. Compared with the optical pickup in the related art that uses a single laser to implement the above functions, such a design can extend the service life of the optical pickup.

[0022] In some embodiments, the light source portion further includes a second diffraction grating, which is disposed between the second wavelength laser and the second beam combining device. The second wavelength laser is used to generate a second wavelength laser beam, and the second wavelength laser beam is projected onto the second diffraction grating; the second diffraction grating is used to split the second wavelength laser beam into a first beam, a second beam, and a third beam, and the first beam, the second beam, and the third beam are all projected onto the second beam combining device;

[0023] The second beam combining device is used for combining the first wavelength laser beam, the first light beam, the second light beam and the third light beam and projecting them to the action part.

[0024] The active part is used to receive the first wavelength laser beam, the first light beam, the second light beam and the third light beam, and use the first wavelength laser beam to write data to the optical disc, use the first light beam to read data and perform focusing servo on the optical disc, and use the second light beam and the third light beam to perform tracking servo on the optical disc.

[0025] Since the laser needs to have a high output power when writing data to the optical disc, the service life will be significantly shortened. In the optical pickup provided in the embodiment of the present application, a first wavelength laser is used to write data to the optical disc, and a second wavelength laser is used to read data, focus servo and tracking servo; and, N first wavelength lasers are provided, and the N first wavelength lasers can take over the work under the control of the control circuit. Such a design can further extend the service life of the optical pickup. Moreover, compared with the optical pickup in the related art that needs to be replaced as a whole due to laser failure, the optical pickup provided by this embodiment has obvious cost advantages.

[0026] In some embodiments, the light source part includes M second wavelength lasers, where M is a positive integer greater than or equal to 2, and the M second wavelength lasers can work in succession under the control of the control circuit. Such a design also serves the purpose of extending the service life of the optical pickup.

[0027] In some embodiments, the second beam combining device includes a dichroic mirror. Such a design has the advantages of simple optical path, easy implementation and low cost.

[0028] In some embodiments, the active part includes a light isolating device, an objective lens, and a photoelectric sensor; the light isolating device is used to receive the light beam from the light source, and project the light beam from the light source to the objective lens to form an incident light beam from the optical disc; the light isolating device is also used to receive the optical disc reflected light beam reflected from the optical disc, and project the optical disc reflected light beam to the photoelectric sensor. The active part adopts the above optical path design, which has the advantages of simple optical path, easy implementation, and low cost.

[0029] In a second aspect, an embodiment of the present application provides an optical disc reading and writing device, which includes a circuit board and an optical pickup as described in any one of the embodiments of the first aspect, and the optical pickup is electrically connected to the circuit board.

[0030] The technical effect that can be achieved by the optical disc reading and writing device provided in the embodiment of the present application is the same as the technical effect that can be achieved by the optical pickup in any of the above embodiments, and will not be described in detail here.

[0031] In some embodiments, the optical disc reading and writing device further includes a control circuit, and the control circuit includes a power supply, a switching control circuit and a constant power control circuit.

[0032] The switching control circuit is arranged between the power supply and the N first wavelength lasers, and is used to control the N first wavelength lasers to work in succession according to the power supply current of the power supply. The constant power control circuit is arranged between the power supply and the N first wavelength lasers, and is used for the first wavelength lasers to work at a constant output power.

[0033] The control circuit designed as above can realize aging failure detection of the laser on the basis of realizing constant power control, and can control the succession work of the laser based on the result of aging failure detection; it has the advantages of rich circuit functions, easy implementation, and accurate switching control.

[0034] In some embodiments, the switching control circuit includes a voltage comparator and a multiplex switch, wherein the multiplex switch has N conduction states, and the N conduction states respectively realize conduction between the N first wavelength lasers and the power supply.

[0035] The voltage comparator is used to output a level signal for switching the conduction state to the multiplex switch when the supply current is greater than the failure current threshold.

[0036] In the switching control circuit provided in the embodiment of the present application, a voltage comparator and a multiplexer switch are used to implement switching control based on aging failure detection, and the combination of components is simple and easy to implement.

[0037] In some embodiments, the control circuit is integrated in the optical pickup, or integrated in the circuit board. In the switching control circuit provided in the embodiment of the present application, it can be set in different positions and use different product forms. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the structure of an optical disc reading and writing device provided in an embodiment of the present application;

[0039] Figure 2 A schematic diagram of the structure of an optical pickup provided in an embodiment of the present application;

[0040] Figure 3 A schematic diagram of an optical path of an optical pickup provided in an embodiment of the present application;

[0041] Figure 4 A schematic diagram of the principle of a polarization beam splitter prism provided in an embodiment of the present application;

[0042] Figure 5 for Figure 3 Schematic diagram of the principle of the first diffraction grating;

[0043] Figure 6 A circuit diagram of a control circuit provided in an embodiment of the present application;

[0044] Figure 7 for Figure 6 A circuit diagram of a switching control circuit;

[0045] Figure 8 A circuit diagram of another control circuit provided in an embodiment of the present application;

[0046] Fig. 9 A schematic structural diagram of a light source part in another optical pickup provided in an embodiment of the present application;

[0047] Fig.10 A schematic diagram of the optical path of another optical pickup provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0049] In the following, in the embodiments of the present application, the terms "first", "second", etc. are only used for convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, "plurality" means two or more.

[0050] In the embodiments of the present application, "up", "down", "left" and "right" are not limited to being defined relative to the orientation of the components schematically placed in the drawings. It should be understood that these directional terms may be relative concepts. They are used for relative description and clarification, and may change accordingly according to changes in the orientation of the components placed in the drawings.

[0051] In the embodiments of the present application, unless the context requires otherwise, throughout the specification and claims, the term "including" is interpreted as an open, inclusive meaning, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "exemplarily" or "some examples" and the like are intended to indicate that specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present application. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics described may be included in any one or more embodiments or examples in any appropriate manner.

[0052] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of variation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0053] As used herein, "parallel", "perpendicular", and "equal" include the situations described and situations similar to the situations described, and the range of the similar situations is within the acceptable deviation range, wherein the acceptable deviation range is determined by a person of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, wherein the acceptable deviation range of approximate parallelism may be, for example, a deviation within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, wherein the acceptable deviation range of approximate perpendicularity may also be, for example, a deviation within 5°. "Equal" includes absolute equality and approximate equality, wherein the acceptable deviation range of approximate equality may be, for example, the difference between the two equalities is less than or equal to 5% of either one.

[0054] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0055] In the embodiments of the present application, exemplary embodiments are described with reference to cross-sectional views and / or plan views and / or equivalent circuit diagrams as idealized exemplary drawings. In the drawings, the thickness of the layers and regions is magnified for clarity. Therefore, it is conceivable that the shape changes relative to the drawings are caused by, for example, manufacturing technology and / or tolerances. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but include shape deviations caused by, for example, manufacturing. For example, an etched region shown as a rectangle will generally have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shapes of the regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0056] The embodiment of the present application provides a CD-ROM reading and writing device, which may be a CD-ROM drive (hereinafter referred to as a CD-ROM drive), where the CD-ROM drive may be a device that can be externally connected to an electronic device such as a computer, or may be a device integrated into an electronic device such as a computer. The CD-ROM reading and writing device may also be an electronic device such as a computer integrated with a CD-ROM drive. Computers and other electronic devices can read and write information on CDs through CD-ROM drives. The CD-ROM reading and writing device may also be a player product that can work independently, such as a CD player, a DVD player, and a BD player.

[0057] For example, Figure 1 As shown, the optical disc reading and writing device 100 includes a circuit board 3, a spindle motor 2 and an optical pickup 1, wherein the circuit board 3 is electrically connected to the spindle motor 2, and the spindle motor 2 is used to drive the optical disc to rotate; the optical pickup 1 is arranged on one side of the spindle motor 2 and is electrically connected to the circuit board 3; the optical pickup 1 is used to read and write data on the optical disc.

[0058] The embodiment of the present application also provides an optical pickup 1, which can be applied to the above-mentioned optical disc reading and writing device 100. Figure 2 As shown, the optical pickup 1 includes a light source part 4 and an action part 5; wherein the light source part 4 is used to generate a light source beam P0 projected to the action part 5; the action part 5 is used to receive the light source beam P0 and use the light source beam P0 to read and write data on the optical disc 6.

[0059] In this embodiment, if Figure 3 As shown, the light source part 4 includes a first wavelength laser, a first beam combining device and a first diffraction grating 10; wherein the first wavelength laser refers to a semiconductor laser (LaserDiode, abbreviated as LD) capable of generating a first wavelength laser beam, and the wavelength of the first wavelength laser beam is a first wavelength, and the size of the first wavelength is related to the type of product adapted by the optical pickup 1. For example, for the optical pickup 1 applicable to CD optical discs, the first wavelength may be 780nm; for the optical pickup 1 applicable to DVD optical discs, the first wavelength may be 650nm; for the optical pickup 1 applicable to BD optical discs, the first wavelength may be 405nm.

[0060] The optical pickup 1 provided in the embodiment of the present application can be applied to various types of optical discs 6, so the size of the first wavelength is not limited. In some other embodiments, the first wavelength laser can also be a solid laser, a gas laser or other laser that can generate a laser beam of the first wavelength.

[0061] Please continue to refer to Figure 3 In the light source part 4, two first wavelength lasers are provided, namely, the first laser 7 and the second laser 9; the first laser 7 is used to generate the first laser beam P1, and the second laser 9 is used to generate the second laser beam P2. The wavelengths of the first laser beam P1 and the second laser beam P2 are both the first wavelength, and they are orthogonal linear polarized lights; that is, the first laser beam P1 is linear polarized light in the first polarization direction, and the second laser beam P2 is linear polarized light in the second polarization direction, and the first polarization direction and the second polarization direction are perpendicular to each other. Exemplarily, the first laser beam P1 is P polarized light, and the second laser beam P2 is S polarized light; in another exemplary embodiment, the first laser beam P1 is S polarized light, and the second laser beam P2 is P polarized light.

[0062] The following takes the case where the first polarization direction is a parallel polarization direction, the first laser beam P1 is a P polarized light, the second polarization direction is a vertical polarization direction, and the second laser beam P2 is an S polarized light as an example to exemplify the scheme provided in the embodiment of the present application. Those skilled in the art can adjust the scheme to the case where the first laser beam P1 is an S polarized light and the second laser beam P2 is a P polarized light according to the following description.

[0063] The first laser 7 can project the first laser beam P1 (P polarized light) to the first beam combining device, and the second laser 9 can also project the second laser beam P2 (S polarized light) to the first beam combining device. The first beam combining device is used to receive the first laser beam P1 (P polarized light) and the second laser beam P2 (S polarized light), and project both the first laser beam P1 (P polarized light) and the second laser beam P2 (S polarized light) to the first diffraction grating 10; at the same time, the polarization direction of the second laser beam P2 (S polarized light) is adjusted to the first polarization direction, so that the polarization directions of the first laser beam P1 and the second laser beam P2 projected to the first diffraction grating 10 are both the first polarization direction. In this embodiment, the first laser beam P1 and the second laser beam P2 projected to the first diffraction grating 10 are both P polarized light.

[0064] It can be seen from the above description that the first beam combining device is a polarization beam combiner, which can be implemented by using a polarization beam splitter prism. A polarization beam splitter prism is an optical element that can separate the horizontal polarization and the vertical polarization of light.

[0065] like Figure 4 As shown, the polarization splitter prism is a square prism formed by combining two right-angle prisms, and its outer surface includes four end faces, namely the first end face S1, the second end face S2, the third end face S3 and the fourth end face S4; wherein the first end face S1 and the second end face S2 are arranged opposite to each other in the first direction and are both perpendicular to the first direction; the third end face S3 and the fourth end face S4 are arranged opposite to each other in the second direction and are both perpendicular to the second direction; the second direction and the first direction can be perpendicular to each other.

[0066] The polarization beam splitter prism also has a beam splitting surface S0 located inside, the beam splitting surface S0 is tilted relative to the first direction and the second direction, the first end surface S1 and the second end surface S2 are located on both sides of the beam splitting surface S0, the first end surface S1 and the third end surface S3 are located on the same side of the beam splitting surface S0, and the fourth end surface S4 and the second end surface S2 are located on the other side of the beam splitting surface S0. The beam splitting surface S0 can reflect S polarized light and transmit P polarized light, so an incident light beam containing P polarized light and S polarized light (such as natural light, orthogonal linear polarized light, etc.) can be split; thereby forming a P polarized light transmission light path connecting the first end surface S1 and the second end surface S2, and forming an S polarized reflection light path connecting the first end surface S1 and the third end surface S3.

[0067] Polarization beam splitters can be used as polarization beam splitters, such as Figure 4 As shown in part (a), in this case, the P polarized light ( Figure 4 dot symbol) and S polarized light ( Figure 4The incident light beam (represented by a vertical short line symbol) is irradiated to the splitting surface S0 through the first end surface S1, the S polarized light reflected by the splitting surface S0 is emitted from the third end surface S3, and the P polarized light transmitted by the splitting surface S0 is emitted from the second end surface S2; thereby realizing the function of polarization splitting.

[0068] Polarization beam splitters can also be used in reverse to act as polarization beam combiners, such as Figure 4 As shown in part (b), in this case, P polarized light is incident on the second end surface S2 and irradiates the splitting surface S0, and is emitted from the first end surface S1 after being transmitted through the splitting surface S0; S polarized light is incident on the third end surface S3 and irradiates the splitting surface S0, and is converted into P polarized light after being reflected by the splitting surface S0 and is emitted from the first end surface S1.

[0069] In this embodiment, the first beam combining device includes a first polarization beam splitting prism 8, such as Figure 3 As shown, the second end surface S1 of the first polarization beam splitter prism 8 is opposite to the first laser 7, the third end surface S3 is opposite to the second laser 9, and the first end surface S1 is opposite to the first diffraction grating 10. The first laser beam P1 (P polarized light) generated by the first laser 7 is irradiated to the first diffraction grating 10 after passing through the first polarization beam splitter prism 8; the second laser beam P2 (S polarized light) generated by the second laser 9 is converted into P polarized light after passing through the first polarization beam splitter prism 8, and also irradiates the first diffraction grating 10.

[0070] The first diffraction grating 10 is a grating structure that can periodically modulate the amplitude or phase (or both) of the incident light. Figure 5 As shown, the first diffraction grating 10 can diffract the incident first laser beam P1 and the second laser beam P2 into diffraction beams of different orders, such as a 0th order diffraction beam, a +1st order diffraction beam, a -1st order diffraction beam, and the like.

[0071] For ease of description, the 0th order diffraction beam formed by the first diffraction grating 10 is referred to as the first beam, the +1st order diffraction beam is referred to as the second beam, and the -1st order diffraction beam is referred to as the third beam. That is, the first diffraction grating 10 can split the incident first laser beam P1 and the second laser beam P2 into the first beam, the second beam, and the third beam. The first diffraction grating 10 is also used to project the first beam, the second beam, and the third beam to the action portion 5.

[0072] In this article, the light beam projected from the light source part 4 to the action part 5 is collectively referred to as the light source beam P0; it can be seen from the above description that the light source beam P0 can include the first beam, the second beam and the third beam after the first laser beam P1 is split by the first diffraction grating 10, and can also include the first beam, the second beam and the third beam after the second laser beam P2 is split by the first diffraction grating 10. The wavelength of the light source beam P0 is the first wavelength, and it is linearly polarized light in the first polarization direction. The action part 5 is used to receive the light source beam P0, and can use the first beam to read and write data and perform focusing servo on the optical disc 6, and can use the second beam and the third beam to perform tracking servo on the optical disc 6.

[0073] Please continue to refer to Figure 3 The function part 5 includes an optical isolation device, an objective lens 15 and a photoelectric sensor (PhotoDetector Integrated Circuit, abbreviated as PDIC) 17, wherein the optical isolation device is used to receive the light source beam P0 (including the first light beam, the second light beam and the third light beam), and project the light source beam P0 to the objective lens 15 as the optical disc incident beam P3. The optical disc incident beam P3 is focused on the corresponding recording surface of the optical disc 6 after being emitted by the objective lens 15; after the action of the reflective layer in the optical disc 6, the optical disc incident beam P3 is converted into an optical disc reflected beam P4 carrying information. The optical disc reflected beam P4 returns to the optical isolation device through the objective lens 15. The optical isolation device is also used to receive the returned optical disc reflected beam P4 and project the optical disc reflected beam P4 to the photoelectric sensor 17; after receiving the optical disc reflected beam P4, the photoelectric sensor 17 converts the optical signal into an electrical signal to realize functions such as data reading and servo control of the optical disc 6.

[0074] like Figure 3 As shown, in this embodiment, the optical isolation device includes a second polarization beam splitter prism 11, a collimating lens 12 and a quarter-wave plate (Quarter-wave plate, abbreviated as QWP) 13. Figure 3 The second end surface S2 in the second polarization beam splitter prism 11 is arranged opposite to the first diffraction grating 10, and is used to receive the light source beam P0. As can be seen from the above description, the wavelength of the light source beam P0 incident on the action part 5 is the first wavelength and is P polarized light. The light source beam P0 is incident on the second end surface S2 and irradiates the beam splitting surface S0; after being transmitted through the beam splitting surface S0, it is emitted from the first end surface S1; at this time, the light source beam P0 is still P polarized light.

[0075] The collimating lens 12 is disposed opposite to the first end surface S1 of the second polarization beam splitter prism 11 , and is used for receiving the light source beam P0 emitted from the first end surface S1 , and collimating the divergent light into a parallel beam and then irradiating the parallel beam to the quarter wave plate 13 .

[0076] The quarter wave plate 13, also known as a "quarter phase delay plate", is a birefringent single crystal wave plate of a certain thickness. When light passes through the quarter wave plate 13 from normal incidence, the phase difference between ordinary light (o light) and extraordinary light (e light) is equal to π / 2 or an odd multiple thereof. When P polarized light passes through the quarter wave plate 13 twice, it can be converted into S polarized light; when S polarized light passes through the quarter wave plate 13 twice, it can be converted into P polarized light.

[0077] In this embodiment, the collimated light source beam P0 is a P polarized light, which is projected toward the objective lens 15 after passing through the quarter wave plate 13 and is used as the optical disc incident beam P3. The optical disc incident beam P3 is irradiated onto the optical disc 6 to form an optical disc reflected beam P4, which is returned to the first end surface S1 of the second polarization beam splitter prism 11 through the objective lens 15, the quarter wave plate 13 and the collimating lens 12.

[0078] It can be seen from the above description that after passing through the quarter wave plate 13 twice, the optical disc reflected light beam P4 is converted into S polarized light, and the S polarized light is irradiated to the splitting surface S0 through the first end surface S1, and the splitting surface S0 reflects the S polarized light and emits it from the third end surface S3; the focusing lens 16 is arranged opposite to the third end surface S3, and the photoelectric sensor 17 is arranged on the side of the focusing lens 16 away from the third end surface S3. The focusing lens 16 is used to receive the optical disc reflected light beam P4 emitted from the third end surface S3, and focus the optical disc reflected light beam P4 and project it to the photoelectric sensor 17.

[0079] In some embodiments, the active part 5 further includes a reflector 14, which is disposed between the optical isolation device and the objective lens 15, and is used to change the propagation direction of the light beam to achieve redirection of the light beam.

[0080] In the optical pickup 1 provided in the above embodiment, the light source part 4 includes two first wavelength lasers, namely the first laser 7 and the second laser 9; with such a design, during the operation of the optical pickup 1, the first laser 7 and the second laser 9 can be controlled to take over the work, so that the service life of the optical pickup 1 can be freed from the limitation of the service life of a single laser, thereby extending the service life of the optical pickup 1; and, compared with the related art in which the optical pickup 1 needs to be replaced as a whole due to laser failure, the method of setting two first wavelength lasers has obvious cost advantages.

[0081] In order to control the successive operation of the first laser 7 and the second laser 9 , the embodiment of the present application also provides a control circuit applied to the above-mentioned optical pickup 1 , which can be integrated in the optical pickup 1 or in the optical disc reading and writing device 100 .

[0082] The control circuit can implement switching control based on aging failure detection of the laser, that is, when it is detected that the normal operation of the currently working first wavelength laser is affected by aging failure, another first wavelength laser is controlled to take over the operation.

[0083] For example, Figure 6 As shown, the control circuit 18 includes a power supply 19, a switching control circuit 20 and a constant power control circuit 21, wherein the power supply 19 is electrically connected to the switching control circuit 20 and the constant power control circuit 21, and the switching control circuit 20 is connected to the first laser 7 and the second laser 9, and is used to control the conduction status of the first laser 7 and the second laser 9 with the power supply 19; so that when the optical pickup 1 is working, only one of the first laser 7 and the second laser 9 is turned on, and the conduction status of the first laser 7 and the second laser 9 with the power supply 19 can be switched.

[0084] The constant power control circuit 21 is also connected to the first laser 7 and the second laser 9, and is used to perform constant power control on the first laser 7 and the second laser 9 that are connected to the power supply 19, that is, to control the first laser 7 and the second laser 9 that are in the on state to have a stable output power. As can be seen from the above description, the first laser 7 and the second laser 9 are both semiconductor lasers. As the light emission time increases, the semiconductor laser will age due to defects in the single crystal material, movement of the tube core welding, etc., so that the threshold current increases and the output power decreases. However, the optical pickup 1 requires a laser with stable power for data reading and writing and servo control of the optical disc 6. Therefore, in order to improve the defect of the semiconductor laser that the output power is reduced due to aging, constant power control can be performed by the constant power control circuit 21. The principle of the constant power control circuit 21 to achieve constant power control is: detect the threshold current of the semiconductor laser, when the threshold current of the semiconductor laser increases due to aging, control the power supply 19 to increase the supply current to compensate for the output power decreased due to aging, so that the semiconductor laser can maintain a constant or substantially constant output power to ensure the working performance of the optical pickup 1.

[0085] However, when the threshold current of the semiconductor laser rises too high, for example, greater than 50%, continuing to apply a larger supply current will not make the semiconductor laser work for a long time, indicating that the semiconductor laser has a relatively large defect at this time and can be determined to be failed. Therefore, in the control circuit 18 that uses the constant power control circuit 21 to perform constant power control, the aging failure of the first laser 7 or the second laser 9 in the on state can be judged based on the size of the supply current; for example, a failure current threshold can be set, and when the supply current (corresponding to the actual threshold current) is higher than the failure current threshold, it can be determined that the first laser 7 or the second laser 9 currently on is failed.

[0086] In the control circuit 18 provided in the embodiment of the present application, the switching control circuit 20 can obtain the failure status of the currently turned-on first laser 7 or second laser 9 according to the relationship between the power supply current and the failure current threshold, and thereby control the conduction state of the first laser 7 and the second laser 9. The working process of the switching control circuit 20 controlling the conduction state of the first laser 7 and the second laser 9 is as follows:

[0087] Assume that the switching control circuit 20 first controls the conduction state between the first laser 7 and the power supply 19, and the power supply 19 provides electric energy to the first laser 7, so that the first laser 7 works; the second laser 9 cannot work because it is not connected to the power supply 19. As the use time of the first laser 7 increases, the threshold current slowly increases; due to the action of the constant power control circuit 21, the power supply current output by the power supply 19 to the first laser 7 also increases. When the power supply current exceeds the failure current threshold, it can be determined that the first laser 7 fails. When the power supply current exceeds the failure current threshold, the switching control circuit 20 switches the conduction state between the first laser 7 and the second laser 9 and the power supply 19; that is, the connection between the first laser 7 and the power supply 19 is cut off, so that the second laser 9 and the power supply 19 are connected; thereby controlling the first laser 7 to stop working and controlling the second laser 9 to take over the work of the first laser 7.

[0088] In some embodiments, Figure 7 As shown, the switching control circuit 20 includes a voltage comparator 23 and a multiplexing switch 22. The voltage comparator 23 is used to compare the power supply current with the failure current threshold. When the power supply current is less than or equal to the failure current threshold, a first level signal is output; when the power supply current is greater than the failure current threshold, a second level signal is output. The output end of the voltage comparator 23 is electrically connected to the multiplexing switch 22. The multiplexing switch 22 has at least two conduction states, and the conduction state can be controlled according to the level signal output by the voltage comparator 23.

[0089] Exemplarily, the multiplexing switch 22 has a first conduction state for conducting the first laser 7 and the power supply 19, and a second conduction state for conducting the second laser 9 and the power supply 19. When the multiplexing switch 22 receives the first level signal output by the voltage comparator 23, the multiplexing switch 22 is controlled to be in the first conduction state, and when the voltage comparator 23 is in the second conduction state, the multiplexing switch 22 is controlled to be in the second conduction state.

[0090] In the above embodiment, the control circuit 18 controls the first laser 7 and the second laser 9 to work in succession based on the aging failure detection of the laser, but the embodiment of the present application is not limited to this. In some embodiments, the control circuit 18 can also control the first laser 7 and the second laser 9 to work alternately, that is, after the first laser 7 is controlled to work for a certain period of time, the second laser 9 is controlled to take over the work; after the second laser 9 works for a certain period of time, the first laser 7 is controlled to take over the work; and the cycle is repeated in sequence. This control strategy can still enable the service life of the optical pickup 1 to get rid of the limitation of the service life of a single laser and extend the service life of the optical pickup 1. Moreover, compared with the related art where the optical pickup 1 needs to be replaced as a whole due to laser failure, it still has obvious cost advantages.

[0091] For example, Figure 8 As shown, the control circuit 18 for realizing the alternating operation control of the first laser 7 and the second laser 9 may include a power supply 19 and a switching control circuit 20. The switching control circuit 20 includes a timing circuit 24 and a multiplexer switch 22. The timing circuit 24 may output a level signal for controlling the multiplexer switch 22 to switch to a conducting state after a certain period of time, thereby controlling the first laser 7 and the second laser 9 to work alternately.

[0092] In the above embodiment, the light source part 4 is provided with two first wavelength lasers as an example for explanation, but the embodiment of the present application is not limited to this, and the light source part 4 may include N first wavelength lasers, where N is a positive integer greater than or equal to 2. The embodiment of the present application does not limit the number of first wavelength lasers. For the case of two or more first wavelength lasers, the control circuit 18 and the optical path design can be adjusted with reference to the above. For example, for the multiplexer 22 in the switching control circuit 20, it includes N conduction states; the N conduction states are used to respectively conduct the N first wavelength lasers and the power supply 19; the voltage comparator 23 and the timing circuit 24 can both output a level signal of switching the conduction state to the multiplexer 22.

[0093] It can be seen from the above description that in the optical pickup 1 provided in the embodiment of the present application, the light source part 4 is provided with two or more identical first wavelength lasers, and each first wavelength laser can be implemented to provide a laser beam used as a working beam for the operation of the optical pickup 1; the optical pickup 1 also includes a control circuit 18, and the control circuit 18 can take over the operation of the first wavelength laser in the light source part 4, so that the service life of the optical pickup 1 can get rid of the limitation of the service life of a single laser, thereby extending the service life of the optical pickup 1; and, compared with the related art in which the optical pickup 1 needs to be replaced as a whole due to laser failure, the method of setting two or more first wavelength lasers has obvious cost advantages.

[0094] The present application embodiment also provides another optical pickup 1, such as Fig. 9 As shown in FIG. 1 , the difference between the optical pickup 1 and the optical pickup 1 in the above embodiment lies in the light source part 4. In the optical pickup 1 provided in this embodiment, the light source part 4 includes a first light source part 41, a second light source part 42, and a second beam combining device 43; wherein the first light source part 41 includes two first wavelength lasers and a first beam combining device; the structure and working principle of the first light source part 41 can be referred to in the attached Figure 3 As well as the relevant descriptions above, I will not repeat them here.

[0095] For ease of description, the laser beam projected from the first light source portion 41 to the second beam combining device 43 is referred to herein as a first wavelength laser beam P10. As can be seen from the above description, the wavelength of the first wavelength laser beam P10 is a first wavelength, and is linearly polarized light in a first polarization direction.

[0096] like Fig. 9 and Fig.10 As shown, the second light source section 42 includes a second wavelength laser 25 and a second diffraction grating 26, wherein the second wavelength laser 25 is used to generate a laser beam of a second wavelength, which is referred to as a second wavelength laser beam P20 herein. The wavelength of the second wavelength laser beam P20 is the second wavelength, and it is linearly polarized light in the first polarization direction.

[0097] The second wavelength laser 25 projects the second wavelength laser beam P20 to the second diffraction grating 26, and the second diffraction grating 26 can diffract the incident second wavelength laser beam P20 into diffraction beams of different orders, such as a 0-order diffraction grating, a +1-order diffraction beam, a -1-order diffraction beam, etc. In this article, the 0-order diffraction beam formed by the diffraction of the second diffraction grating 26 is referred to as the first beam, the +1-order diffraction beam is referred to as the second beam, and the -1-order diffraction beam is referred to as the third beam. In other words, the second diffraction grating 26 can split the incident second wavelength laser beam P20 into a first beam, a second beam, and a third beam, and project the first beam, the second beam, and the third beam to the second beam combining device 43.

[0098] The second beam combining device 43 is used to receive the first wavelength laser beam P10 (wavelength is the first wavelength), the first light beam (wavelength is the second wavelength), the second light beam (wavelength is the second wavelength) and the third light beam (wavelength is the second wavelength), and combine the light beams of different wavelengths and project them to the active part 5.

[0099] The second beam combining device 43 may use a dichroic mirror 27. The dichroic mirror 27 is also called a two-phase mirror, which has the characteristics of almost completely transmitting a certain wavelength of light and almost completely reflecting other wavelengths of light. Therefore, the dichroic mirror 27 can be used as a beam splitting element to split the incident light beam into light beams with different wavelengths and emit them in different directions; the dichroic mirror can also be used as a light combining element, that is, to combine the incident light beams with different wavelengths and emit them in the same direction.

[0100] In this embodiment, the dichroic mirror 27 has a reflection light path and a transmission light path, and the output ends of the reflection light path and the transmission light path are the same and are arranged opposite to the action part 5. The input end of the transmission light path is arranged opposite to the first polarization beam splitter prism 8 in the first light source part 41, and is used to receive the first wavelength laser beam P10; the input end of the transmission light path is arranged opposite to the second diffraction grating 26 in the second light source part 42, and is used to receive the first light beam, the second light beam and the third light beam formed by the diffraction of the second wavelength laser beam P20.

[0101] After receiving the first wavelength laser beam, the first light beam, the second light beam and the third light beam, the dichroic mirror 27 projects them to the active part 5. Herein, the light beams projected from the light source part 4 to the active part 5 are collectively referred to as light source beams P0.

[0102] After receiving the light source beam P0, the action part 5 can use the first wavelength laser beam to write data to the optical disc 6, use the first beam to read data and perform focus servo on the optical disc 6, and use the second beam and the third beam to perform tracking servo on the optical disc 6. The structure and working principle of the action part 5 are the same as above, and will not be repeated here.

[0103] In the optical pickup 1 provided in this embodiment, two lasers with different wavelengths are used to implement functions such as data writing, data reading, focusing servo and tracking servo on the optical disc 6. Such a design can extend the service life of the optical pickup 1 compared with the optical pickup 1 in the related art that uses a single laser to implement the above functions.

[0104] In addition, since the laser needs to have a high output power when writing data to the optical disc 6, the service life will be significantly shortened. Based on this, in the optical pickup 1 provided in this embodiment, a first wavelength laser is used to write data to the optical disc 6, and a second wavelength laser 25 is used to read data, focus servo and tracking servo; and, two first wavelength lasers are provided, and the two first wavelength lasers can take over the work under the control of the control circuit 18. Such a design can further extend the service life of the optical pickup 1. Moreover, compared with the optical pickup 1 in the related art that needs to be replaced as a whole due to laser failure, the optical pickup 1 provided in this embodiment has obvious cost advantages.

[0105] In the optical pickup 1 provided in this embodiment, since a first wavelength laser is required to write data to the optical disc 6, the size of the first wavelength is related to the type of product adapted by the optical pickup 1. For example, for the optical pickup 1 applicable to CD optical discs, the first wavelength may be 780nm; for the optical pickup 1 applicable to DVD optical discs, the first wavelength may be 650nm; for the optical pickup 1 applicable to BD optical discs, the first wavelength may be 405nm.

[0106] The second wavelength can be different from the first wavelength. In some embodiments, the second wavelength is greater than the first wavelength. For example, the first wavelength laser is a blue laser and the second wavelength laser is a red laser. Generally, lasers with larger wavelengths are cheaper than lasers with smaller wavelengths. For example, the cost of a red laser is significantly lower than that of a blue laser. Therefore, the above design can reduce costs without affecting the function of the optical pickup 1.

[0107] In the above embodiment, the first light source part 41 is provided with two first wavelength lasers as an example for explanation, but the embodiment of the present application is not limited to this. The first light source part 41 may include N first wavelength lasers, where N is a positive integer greater than or equal to 2; this part of the content can refer to the relevant description above.

[0108] In some embodiments, the second light source part 41 can be provided with M second wavelength lasers 25 with reference to the first light source part 41, where M is a positive integer greater than or equal to 2. In addition, corresponding control circuits are provided for the M second wavelength lasers 25, so that the M second wavelength lasers 25 can work in succession under the control of the control circuit; thereby, the service life of the optical pickup 1 is extended.

[0109] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An optical pickup, It is characterized in that The optical pickup comprises a light source part and an action part, wherein the light source part is used to generate a light source beam projected to the action part; the action part is used to receive the light source beam and use the light source beam to read and write data on the optical disc; The wavelength of at least part of the light source beam is a first wavelength, the light source part includes N first wavelength lasers, the first wavelength lasers are used to generate a first wavelength laser beam of a first wavelength, and the first wavelength laser beam is used to form the light source beam; Wherein, N is a positive integer greater than or equal to 2; N lasers of the first wavelength can work in succession under the control of the control circuit.

2. The optical pickup according to claim 1, It is characterized in that The light source part also includes a first beam combining device and a first diffraction grating; The first beam combining device is used to receive the first wavelength laser beams generated by N first wavelength lasers, and project the first wavelength laser beams to the first diffraction grating; The first diffraction grating is used to split the first wavelength laser beam into a first beam, a second beam and a third beam, and project the first beam, the second beam and the third beam to the action part; The active part is used to receive the first light beam, the second light beam and the third light beam, and use the first light beam to perform data reading and writing and focusing servo on the optical disc, and use the second light beam and the third light beam to perform tracking servo on the optical disc.

3. The optical pickup according to claim 2, It is characterized in that In the light source part, N is 2, and the two first wavelength lasers are respectively a first laser and a second laser; The first laser is used to generate a first laser beam, and the second laser is used to generate a second laser beam; the wavelength of the first laser beam is a first wavelength, and is linearly polarized light in a first polarization direction; the wavelength of the second laser beam is the first wavelength, and is linearly polarized light in a second polarization direction; the first polarization direction and the second polarization direction are perpendicular to each other; The first beam combining device includes a first polarization beam splitter prism, which is used to receive the first laser beam and the second laser beam, convert the polarization direction of the second laser beam into the first polarization direction, and project the first laser beam and the second laser beam onto the first diffraction grating.

4. The optical pickup according to claim 1, It is characterized in that At least part of the wavelength of the light source beam is a second wavelength; the light source part also includes a first beam combining device, a second beam combining device and a second wavelength laser; The first beam combining device is used to receive the first wavelength laser beams generated by N first wavelength lasers, and project the first wavelength laser beams to the second beam combining device; The second wavelength laser is used to generate a second wavelength laser beam of a second wavelength, and project the second wavelength laser beam to the second beam combining device; The second beam combining device is used to combine the first wavelength laser beam and the second wavelength laser beam and project them to the action part; The active part is used to receive the first wavelength laser beam and the second wavelength laser beam, and use the first wavelength laser beam to write data to the optical disc, use the second wavelength laser beam to perform tracking servo on the optical disc, use the first wavelength laser beam or the second wavelength laser beam to read data from the optical disc, and use the first wavelength laser beam or the second wavelength laser beam to perform focusing servo on the optical disc.

5. The optical pickup according to claim 4, It is characterized in that The light source part further includes a second diffraction grating, and the second diffraction grating is arranged between the second wavelength laser and the second beam combining device; The second wavelength laser is used to generate a second wavelength laser beam, and the second wavelength laser beam is projected onto the second diffraction grating; the second diffraction grating is used to split the second wavelength laser beam into a first beam, a second beam and a third beam, and the first beam, the second beam and the third beam are all projected onto the second beam combining device; The second beam combining device is used to combine the first wavelength laser beam, the first light beam, the second light beam and the third light beam and project them to the action part; The active part is used to receive the first wavelength laser beam, the first light beam, the second light beam and the third light beam, and use the first wavelength laser beam to write data to the optical disc, use the first light beam to read data and perform focusing servo on the optical disc, and use the second light beam and the third light beam to perform tracking servo on the optical disc.

6. The optical pickup according to claim 5, It is characterized in that The light source part includes M second wavelength lasers, wherein M is a positive integer greater than or equal to 2, and the M second wavelength lasers can work in succession under the control of the control circuit.

7. The optical pickup according to any one of claims 4 to 6, It is characterized in that The second beam combining device includes a dichroic mirror.

8. The optical pickup according to any one of claims 1 to 7, It is characterized in that The functional part includes a light isolating device, an objective lens and a photoelectric sensor; The optical isolation device is used to receive the light source beam and project the light source beam to the objective lens to form an incident beam of the optical disc; the optical isolation device is also used to receive a reflected optical disc beam reflected by the optical disc and project the reflected optical disc beam to the photoelectric sensor.

9. An optical disc reading and writing device, It is characterized in that include: Circuit boards; as well as The optical pickup according to any one of claims 1 to 8; the optical pickup is electrically connected to the circuit board.

10. The optical disc reading and writing device according to claim 9, It is characterized in that The optical disc reading and writing device further comprises a control circuit, and the control circuit comprises: Power supply; a switching control circuit, the switching control circuit being arranged between the power supply and the N first wavelength lasers, and being used for controlling the N first wavelength lasers to work in succession according to the power supply current of the power supply; and A constant power control circuit is provided between the power supply and the N first wavelength lasers, and is used for the first wavelength lasers to operate at a constant output power.

11. The optical disc reading and writing device according to claim 10, It is characterized in that The switching control circuit includes a voltage comparator and a multiplex switch; The multiplexing opening has N conduction states, and the N conduction states respectively realize conduction between N first wavelength lasers and the power supply; The voltage comparator is used for outputting a level signal for switching the conduction state to the multiplexing switch when the supply current is greater than the failure current threshold.

12. The optical disc reading and writing device according to claim 10 or 11, It is characterized in that The control circuit is integrated in the optical pickup, or integrated in the circuit board.

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