Optical pickup device and optical disc reading / writing device

Abstract

Embodiments of the present application relate to the technical field of optical disc reading / writing, and provide an optical pickup device and an optical disc reading / writing device, for use in solving the problem that the service life of an optical pickup device and the service life of an optical disc driver are restricted by the service life of a laser. The optical pickup device comprises a light source part and an acting part; the light source part is used for generating light source beams to be projected to the acting part; and the acting part is used for receiving the light source beams and using the light source beams to carry out data reading / writing on an optical disc. The wavelength of at least some of the light source beams 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 having the first wavelength; and the first wavelength laser beams are used for forming the light source beams. N is a positive integer greater than or equal to 2; and the N first wavelength lasers can work alternately under the control of a control circuit. The optical pickup device can be applied to the optical disc reading / writing device.

Description

Optical pickup and optical disc reading and writing device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 23, 2023, with application number 202311589397.8 and application name “An optical pickup and optical disc reading and writing device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] 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

[0003] An optical disc drive (herein referred to as an optical drive) uses lasers to write data to or read data from 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 disc drive for writing, reading, and servoing optical discs. It typically includes components such as a laser, an objective lens, and a photoelectric sensor.

[0004] However, since the laser's continuous light emission life is limited, it restricts the service life of the optical pickup and optical disc drive. Summary of the Invention

[0005] 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.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides an optical pickup, which includes a light source part and an active part, wherein the light source part is used to generate a light source beam projected onto 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.

[0008] 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 the first wavelength. The first wavelength laser beam is used to form the light source beam.

[0009] 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.

[0010] In the optical pickup provided in the embodiment of the present application, the light source portion is provided with two or more identical first wavelength lasers, each of which can provide a laser beam serving as a working beam for the operation of the optical pickup. The first wavelength lasers in the light source portion can also take over operation under the control of the control circuit, thereby freeing the service life of the optical pickup from the limitation of the service life of a single laser and extending the service life of the optical pickup. Moreover, compared with the related art in which the optical pickup needs to be replaced as a whole due to laser failure, the method of providing two or more first wavelength lasers has a significant cost advantage.

[0011] In some embodiments, the light source part further 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 beams generated by N first wavelength lasers and project the first wavelength laser beams onto the first diffraction grating.

[0012] 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 an active portion.

[0013] 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 focus servo on the optical disc, and use the second light beam and the third light beam to perform tracking servo on the optical disc.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] In some embodiments, the light source section further includes a first beam combining device, a second beam combining device, and a second wavelength laser, wherein the first beam combining device is configured to receive the first wavelength laser beams generated by the N first wavelength lasers and project the first wavelength laser beams to the second beam combining device.

[0020] 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.

[0021] 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.

[0022] The optical pickup provided in this embodiment uses two lasers with different wavelengths to perform functions such as writing and reading data from an optical disc, and performing focus and tracking servos. This design can extend the service life of the optical pickup compared to related art optical pickups that use a single laser to perform these functions.

[0023] 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 configured 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 configured to split the second 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 onto the second beam combining device.

[0024] 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 active part.

[0025] 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.

[0026] 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 for data reading, focusing servo and tracking servo; and, there are N first wavelength lasers, 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.

[0027] In some embodiments, the light source portion 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. This design also serves the purpose of extending the service life of the optical pickup.

[0028] 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.

[0029] In some embodiments, the active portion includes an optical isolator, an objective lens, and a photoelectric sensor. The optical isolator receives a light beam from a light source and projects it onto the objective lens, forming an incident light beam for the optical disc. The optical isolator also receives a reflected light beam from the optical disc and projects it onto the photoelectric sensor. The active portion utilizes the aforementioned optical path design, which offers advantages such as a simple optical path, ease of implementation, and low cost.

[0030] 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, wherein the optical pickup is electrically connected to the circuit board.

[0031] The technical effects that can be achieved by the optical disc reading and writing device provided in the embodiment of the present application are the same as the technical effects that can be achieved by the optical pickup in any of the above embodiments, and will not be described in detail here.

[0032] In some embodiments, the optical disc reading and writing device further includes a control circuit, which includes a power supply, a switching control circuit, and a constant power control circuit.

[0033] The switching control circuit is provided 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 provided between the power supply and the N first wavelength lasers, and is used to operate the first wavelength lasers at a constant output power.

[0034] The control circuit designed as above can realize the aging failure detection of the laser on the basis of achieving constant power control, and can control the laser's succession work based on the results of aging failure detection; it has the advantages of rich circuit functions, easy implementation, and accurate switching control.

[0035] In some embodiments, the switching control circuit includes a voltage comparator and a multiplexing switch, wherein the multiplexing switch has N conduction states, and the N conduction states respectively enable conduction between the N first wavelength lasers and the power supply.

[0036] The voltage comparator is used to output a level signal for switching the multiplexer switch to an on state when the supply current is greater than the failure current threshold.

[0037] 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. The combination of components is simple and easy to implement.

[0038] In some embodiments, the control circuit is integrated into the optical pickup, or integrated into 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

[0039] FIG1 is a schematic structural diagram of an optical disc reading and writing device provided in an embodiment of the present application;

[0040] FIG2 is a schematic structural diagram of an optical pickup provided in an embodiment of the present application;

[0041] FIG3 is a schematic diagram of an optical path of an optical pickup provided in an embodiment of the present application;

[0042] FIG4 is a schematic diagram showing the principle of a polarization beam splitter prism provided in an embodiment of the present application;

[0043] FIG5 is a schematic diagram of the principle of the first diffraction grating in FIG3 ;

[0044] FIG6 is a circuit diagram of a control circuit provided in an embodiment of the present application;

[0045] FIG7 is a circuit diagram of the switching control circuit in FIG6 ;

[0046] FIG8 is a circuit diagram of another control circuit provided in an embodiment of the present application;

[0047] FIG9 is a schematic structural diagram of a light source portion in another optical pickup provided in an embodiment of the present application;

[0048] FIG10 is a schematic diagram of an optical path of another optical pickup provided in an embodiment of the present application. DETAILED DESCRIPTION

[0049] The following will describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0050] In the following embodiments of the present application, the terms "first," "second," etc. are used for convenience of description only and should not 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 this application, unless otherwise specified, "plurality" means two or more.

[0051] 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 descriptions and clarifications, and may change accordingly according to changes in the orientation of the components in the drawings.

[0052] In the embodiments of the present application, unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as open and inclusive, 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 the 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 may be included in any one or more embodiments or examples in any appropriate manner.

[0053] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of deviation 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).

[0054] 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 an acceptable deviation range, wherein the acceptable deviation range is as 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 the specific 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 can be, for example, a deviation within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, wherein the acceptable deviation range of approximate perpendicularity can also be, for example, a deviation within 5°. "Equal" includes absolute equality and approximate equality, wherein the acceptable deviation range of approximate equality can be, for example, that the difference between the two equals is less than or equal to 5% of either one.

[0055] It will be understood that when a layer or 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 therebetween.

[0056] 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 thicknesses of layers and regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are conceivable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically 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 regions of the device and are not intended to limit the scope of the exemplary embodiments.

[0057] An embodiment of the present application provides an optical disc reading and writing device, which may be an optical disc drive (hereinafter referred to as an optical disc drive). The optical disc 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 optical disc reading and writing device may also be an electronic device such as a computer integrated with an optical disc drive. An electronic device such as a computer reads and writes information on an optical disc through the optical disc drive. The optical disc 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.

[0058] Exemplarily, as shown in Figure 1, 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.

[0059] The present embodiment also provides an optical pickup 1, which can be used in the aforementioned optical disc read / write device 100. As shown in FIG2 , the optical pickup 1 includes a light source portion 4 and an active portion 5. The light source portion 4 is configured to generate a light beam P0 that is projected onto the active portion 5. The active portion 5 is configured to receive the light beam P0 and utilize the light beam P0 to read and write data from an optical disc 6.

[0060] In this embodiment, as shown in FIG3 , the light source section 4 includes a first wavelength laser, a first beam combining device, and a first diffraction grating 10. The first wavelength laser refers to a semiconductor laser (LD) capable of generating a first wavelength laser beam. The wavelength of the first wavelength laser beam is a first wavelength, and the magnitude of the first wavelength is related to the type of product compatible with the optical pickup 1. For example, for an optical pickup 1 suitable for CDs, the first wavelength may be 780 nm; for an optical pickup 1 suitable for DVDs, the first wavelength may be 650 nm; and for an optical pickup 1 suitable for BDs, the first wavelength may be 405 nm.

[0061] The optical pickup 1 provided in the embodiment of the present application is applicable to a variety of different 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.

[0062] Continuing with reference to FIG3 , in the light source section 4 , two first wavelength lasers are provided, namely a first laser 7 and a second laser 9 ; the first laser 7 is used to generate a first laser beam P1, and the second laser 9 is used to generate a second laser beam P2. The wavelengths of the first laser beam P1 and the second laser beam P2 are both the first wavelength, and are orthogonal linearly polarized light; that is, the first laser beam P1 is linearly polarized light in a first polarization direction, and the second laser beam P2 is linearly polarized light in a 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.

[0063] The following uses a parallel polarization direction as the first polarization direction, a P-polarized first laser beam P1 as the second polarization direction, a perpendicular polarization direction as the second laser beam P2 as the S-polarized light as an example to illustrate the solution provided in the embodiments of this application. Those skilled in the art can adjust the solution to the case where the first laser beam P1 is S-polarized light and the second laser beam P2 is P-polarized light based on the following description.

[0064] The first laser 7 can project the first laser beam P1 (P-polarized light) onto the first beam combining device, and the second laser 9 can also project the second laser beam P2 (S-polarized light) onto 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) onto the first diffraction grating 10. Simultaneously, 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 onto 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 onto the first diffraction grating 10 are both P-polarized light.

[0065] As can be seen from the above description, 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 vertical polarization of light.

[0066] As shown in FIG4 , the polarization beam splitter prism is a square prism formed by combining two right-angle prisms, and its outer surface includes four end faces, namely a first end face S1, a second end face S2, a third end face S3, and a fourth end face S4; wherein the first end face S1 and the second end face S2 are arranged relative to each other in a first direction and are both perpendicular to the first direction; the third end face S3 and the fourth end face S4 are arranged relative to each other in a second direction and are both perpendicular to the second direction; the second direction and the first direction may be perpendicular to each other.

[0067] The polarization beam splitter prism also has an internal beam splitting surface S0, which is tilted relative to both the first and second directions. A first end surface S1 and a second end surface S2 are located on either side 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. Therefore, it can split an incident light beam containing P-polarized light and S-polarized light (such as natural light or orthogonal linearly polarized light), thereby forming a P-polarized light transmission path connecting the first end surface S1 and the second end surface S2, and an S-polarized light reflection path connecting the first end surface S1 and the third end surface S3.

[0068] A polarization beam splitter prism can be used as a polarization beam splitter, as shown in part (a) of Figure 4. In this case, an incident light beam containing P-polarized light (represented by a dot symbol in Figure 4) and S-polarized light (represented by a vertical short line symbol in Figure 4) is irradiated onto the beam splitting surface S0 through the first end surface S1. The S-polarized light reflected by the beam splitting surface S0 is emitted from the third end surface S3, and the P-polarized light transmitted through the beam splitting surface S0 is emitted from the second end surface S2; thereby realizing the function of polarization splitting.

[0069] The polarization beam splitter prism can also be used in reverse as a polarization beam combiner, as shown in part (b) of Figure 4. In this case, P-polarized light is incident on the second end surface S2 and irradiated on the beam splitting surface S0, and is emitted from the first end surface S1 after being transmitted through the beam splitting surface S0; S-polarized light is incident on the third end surface S3 and irradiated on the beam splitting surface S0, and is converted into P-polarized light after being reflected by the beam splitting surface S0 and is emitted from the first end surface S1.

[0070] In this embodiment, the first beam combining device includes a first polarization beam splitter prism 8. As shown in FIG3 , the second end surface S1 of the first polarization beam splitter prism 8 faces the first laser 7, the third end surface S3 faces the second laser 9, and the first end surface S1 faces the first diffraction grating 10. The first laser beam P1 (P-polarized light) generated by the first laser 7 passes through the first polarization beam splitter prism 8 and is then irradiated onto the first diffraction grating 10. 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 is also irradiated onto the first diffraction grating 10.

[0071] The first diffraction grating 10 is a grating structure that can periodically spatially modulate the amplitude or phase (or both) of the incident light; in this embodiment, as shown in Figure 5, 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, etc.

[0072] For ease of description, the 0th-order diffracted beam formed by the first diffraction grating 10 is referred to herein as the first beam, the +1st-order diffracted beam is referred to as the second beam, and the -1st-order diffracted beam is referred to as the third beam. In other words, the first diffraction grating 10 can split the incident first laser beam P1 and second laser beam P2 into the first, second, and third beams. The first diffraction grating 10 is also configured to project the first, second, and third beams onto the active portion 5.

[0073] Herein, the light beam projected from the light source portion 4 to the active portion 5 is collectively referred to as the light source beam P0. As can be seen from the above description, the light source beam P0 may include the first, second, and third light beams formed after the first laser beam P1 is split by the first diffraction grating 10, or the first, second, and third light beams formed after the second laser beam P2 is split by the first diffraction grating 10. The light source beam P0 has a wavelength of the first wavelength and is linearly polarized in the first polarization direction. The active portion 5 is used to receive the light source beam P0 and can use the first beam to read and write data and perform focus servo on the optical disc 6, and can use the second and third beams to perform tracking servo on the optical disc 6.

[0074] Continuing with reference to FIG3 , the active portion 5 includes an optical isolation device, an objective lens 15, and a photodetector integrated circuit (PDIC) 17. The optical isolation device is configured to receive the light source beam P0 (including the first, second, and third light beams) and project the light source beam P0 toward the objective lens 15 as the optical disc incident beam P3. The optical disc incident beam P3 is focused onto the corresponding recording surface of the optical disc 6 after being emitted by the objective lens 15. After passing through the reflective layer of 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 configured to receive the returned optical disc reflected beam P4 and project the optical disc reflected beam P4 onto the photodetector 17. Upon receiving the optical disc reflected beam P4, the photodetector 17 converts the optical signal into an electrical signal to implement functions such as data reading and servo control of the optical disc 6.

[0075] As shown in Figure 3, in this embodiment, the optical isolation device includes a second polarization beam splitter prism 11, a collimating lens 12, and a quarter-wave plate (QWP) 13. Referring to Figure 3, the second end surface S2 of the second polarization beam splitter prism 11 is disposed opposite the first diffraction grating 10 and is configured to receive the light source light beam P0. As described above, the light source light beam P0 incident on the active portion 5 has a first wavelength and is P-polarized light. After being incident on the second end surface S2, the light source light beam P0 is irradiated onto the beam splitting surface S0. After being transmitted through the beam splitting surface S0, the light source light beam P0 is emitted from the first end surface S1. At this point, the light source light beam P0 is still P-polarized light.

[0076] The collimating lens 12 is disposed opposite to the first end surface S1 of the second polarization beam splitter prism 11 , and is configured to receive the light source beam P0 emitted from the first end surface S1 , collimate the divergent light into a parallel beam, and then irradiate the parallel beam to the quarter-wave plate 13 .

[0077] Quarter-wave plate 13, also known as a "quarter phase retarder," is a birefringent single-crystal wave plate of a predetermined thickness. When light passes through quarter-wave plate 13 at normal incidence, the phase difference between the ordinary light (o light) and the extraordinary light (e light) is equal to π / 2 or an odd multiple thereof. P-polarized light passing through quarter-wave plate 13 twice is converted to S-polarized light; S-polarized light passing through quarter-wave plate 13 twice is converted to P-polarized light.

[0078] In this embodiment, the collimated light source beam P0 is P-polarized light. After passing through the quarter-wave plate 13, the light source beam P0 is projected toward the objective lens 15, serving as the optical disc incident beam P3. The optical disc incident beam P3 strikes the optical disc 6 and forms a reflected optical disc beam P4. The reflected optical disc beam P4 then passes through the objective lens 15, the quarter-wave plate 13, and the collimating lens 12 and returns to the first end surface S1 of the second polarization beam splitter prism 11.

[0079] As can be seen from the above description, after passing through the quarter-wave plate 13 twice, the optical disc reflected light beam P4 is converted into S-polarized light. This S-polarized light then passes through the first end surface S1 and strikes the beam splitter surface S0, which reflects the S-polarized light and emits it from the third end surface S3. The focusing lens 16 is positioned opposite the third end surface S3, and the photosensor 17 is positioned on the side of the focusing lens 16 away from the third end surface S3. The focusing lens 16 receives the optical disc reflected light beam P4 emitted from the third end surface S3, focuses the optical disc reflected light beam P4, and projects it onto the photosensor 17.

[0080] 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.

[0081] 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.

[0082] In order to realize the control of the first laser 7 and the second laser 9 working in succession, the embodiment of the present application also provides a control circuit applied to the above-mentioned optical pickup 1, which can be integrated into the optical pickup 1 or into the optical disc reading and writing device 100.

[0083] 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.

[0084] Exemplarily, as shown in Figure 6, 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.

[0085] 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 when connected to the power supply 19. This means that the first laser 7 and the second laser 9, when in the on state, have a stable output power. As described above, the first laser 7 and the second laser 9 are both semiconductor lasers. As the emission time increases, the semiconductor lasers may age due to defects in the single crystal material, die soldering movement, and other factors, causing the threshold current to increase and the output power to decrease. However, the optical pickup 1 requires a laser with stable power for reading and writing data on the optical disc 6 and for servo control. Therefore, to address the problem of reduced output power due to aging of the semiconductor laser, constant power control can be implemented using the constant power control circuit 21. The constant power control circuit 21 implements constant power control by detecting the threshold current of the semiconductor laser. When the threshold current increases due to aging, the power supply 19 is controlled to increase the supply current to compensate for the reduced output power due to aging. This allows the semiconductor laser to maintain a constant or substantially constant output power, thereby ensuring the performance of the optical pickup 1.

[0086] However, when the threshold current of the semiconductor laser rises too high, for example, greater than 50%, continuing to apply a higher supply current will not allow the semiconductor laser to operate for a long time, indicating that the semiconductor laser has a relatively large defect and can be determined to be failed. Therefore, in the control circuit 18 using the constant power control circuit 21 for constant power control, the aging failure of the first laser 7 or the second laser 9 in the conductive state can be determined based on the magnitude 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 currently conductive first laser 7 or the second laser 9 has failed.

[0087] 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 based on the relationship between the 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:

[0088] Assume that the switching control circuit 20 first controls the connection between the first laser 7 and the power supply 19. The power supply 19 provides power to the first laser 7, causing it to operate. However, the second laser 9, because it is disconnected from the power supply 19, cannot operate. As the first laser 7 ages, its threshold current slowly increases. Due to the action of the constant power control circuit 21, the current output by the power supply 19 to the first laser 7 also increases. When the current exceeds the failure current threshold, the first laser 7 is determined to have failed. When the current exceeds the failure current threshold, the switching control circuit 20 switches the connection between the first laser 7 and the second laser 9 and the power supply 19, disconnecting the first laser 7 from the power supply 19 and connecting the second laser 9 to the power supply 19. This stops the first laser 7 and allows the second laser 9 to take over.

[0089] In some embodiments, as shown in FIG7 , the switching control circuit 20 includes a voltage comparator 23 and a multiplexer switch 22. The voltage comparator 23 is configured to compare the supply current with a failure current threshold. When the supply current is less than or equal to the failure current threshold, the comparator outputs a first level signal; when the supply current is greater than the failure current threshold, the comparator outputs a second level signal. The output of the voltage comparator 23 is electrically connected to the multiplexer switch 22. The multiplexer switch 22 has at least two conduction states and can control the conduction state based on the level signal output by the voltage comparator 23.

[0090] Exemplarily, the multiplexing switch 22 has a first conduction state for turning on the first laser 7 and the power supply 19, and a second conduction state for turning on 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.

[0091] 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 embodiments of the present application are 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 controlling the first laser 7 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 continues. This control strategy can still enable the service life of the optical pickup 1 to break away from the limitation of the service life of a single laser, thereby extending the service life of the optical pickup 1. Moreover, compared with the related art in which the optical pickup 1 needs to be replaced as a whole due to laser failure, it still has obvious cost advantages.

[0092] Exemplarily, as shown in FIG8 , a control circuit 18 for realizing the control of the alternating operation 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 22. The timing circuit 24 may output a level signal for controlling the multiplexer 22 to switch to a conductive state after a certain period of time, thereby controlling the alternating operation of the first laser 7 and the second laser 9.

[0093] 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. 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.

[0094] 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 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 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 or more first wavelength lasers has obvious cost advantages.

[0095] The present embodiment also provides another optical pickup 1, as shown in FIG9 . This optical pickup 1 differs from the optical pickup 1 in the above embodiment in the light source section 4. In the optical pickup 1 provided in this embodiment, the light source section 4 includes a first light source section 41, a second light source section 42, and a second beam combining device 43. The first light source section 41 includes two first wavelength lasers and a first beam combining device. The structure and operating principle of the first light source section 41 can be found in FIG3 and the related description above, and will not be repeated here.

[0096] 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 it is linearly polarized light in a first polarization direction.

[0097] As shown in Figures 9 and 10, the second light source section 42 includes a second wavelength laser 25 and a second diffraction grating 26. The second wavelength laser 25 is used to generate a laser beam of a second wavelength, which is referred to herein as a second wavelength laser beam P20. The second wavelength laser beam P20 has a second wavelength and is linearly polarized light in the first polarization direction.

[0098] The second wavelength laser 25 projects the second wavelength laser beam P20 onto the second diffraction grating 26. The second diffraction grating 26 can diffract the incident second wavelength laser beam P20 into diffraction beams of different orders, such as a 0th order diffraction grating, a +1st order diffraction beam, a -1st order diffraction beam, etc. Herein, the 0th order diffraction beam formed by the second diffraction grating 26 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. 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 onto the second beam combining device 43.

[0099] 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.

[0100] The second beam combining device 43 can utilize dichroic mirrors 27. Dichroic mirrors 27, also known as two-phase mirrors, have the characteristic of almost completely transmitting light of certain wavelengths while almost completely reflecting light of other wavelengths. Therefore, dichroic mirrors 27 can function as beam splitters, splitting an incident light beam into beams of different wavelengths and emitting them in different directions. They can also function as beam combiners, combining incident light beams of different wavelengths and emitting them in the same direction.

[0101] In this embodiment, dichroic mirror 27 has a reflective optical path and a transmissive optical path. The output ends of the reflective optical path and the transmissive optical path are the same and are disposed opposite to active portion 5. The input end of the transmissive optical path is disposed opposite to first polarization beam splitter prism 8 in first light source portion 41 and is configured to receive first wavelength laser beam P10. The input end of the transmissive optical path is disposed opposite to second diffraction grating 26 in second light source portion 42 and is configured to receive first, second, and third light beams formed by diffracting second wavelength laser beam P20.

[0102] 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.

[0103] After receiving light source beam P0, active portion 5 can use the first wavelength laser beam to write data to optical disc 6, use the first beam to read data and perform focus servo on optical disc 6, and use the second and third beams to perform tracking servo on optical disc 6. The structure and operating principle of active portion 5 are the same as above and will not be repeated here.

[0104] In the optical pickup 1 provided in this embodiment, two lasers with different wavelengths are used to implement functions such as data writing and reading from the optical disc 6, as well as focus servo and tracking servo. This design can extend the service life of the optical pickup 1 compared to related art optical pickups 1 that use a single laser to implement these functions.

[0105] 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, which needs to be replaced as a whole due to laser failure, the optical pickup 1 provided by this embodiment has obvious cost advantages.

[0106] In the optical pickup 1 provided in this embodiment, a laser with a first wavelength is used to write data to the optical disc 6. Therefore, the size of the first wavelength is related to the type of product to which the optical pickup 1 is adapted. For example, for an optical pickup 1 adapted for CDs, the first wavelength may be 780 nm; for an optical pickup 1 adapted for DVDs, the first wavelength may be 650 nm; and for an optical pickup 1 adapted for BDs, the first wavelength may be 405 nm.

[0107] 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 longer wavelengths are less expensive than lasers with shorter 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.

[0108] 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.

[0109] In some embodiments, the second light source section 41 can be provided with M second wavelength lasers 25 with reference to the first light source section 41, where M is a positive integer greater than or equal to 2. Furthermore, 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 extending the service life of the optical pickup 1.

[0110] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An optical pickup, 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 device according to claim 1, 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, 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 device according to claim 1, 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 device according to claim 4, 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 device according to claim 5, 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 device according to any one of claims 4 to 6, characterized in that: The second beam combining device includes a dichroic mirror.

8. The optical pickup device according to any one of claims 1 to 7, 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, 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, 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, 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, characterized in that: The control circuit is integrated in the optical pickup, or integrated in the circuit board.

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